The fluorescence staining method and scanning electron microscopy （SEM） were used to study the effect of ozone （O3） inactivating Cryptosporidium in water and cell ultrastructures variation to shed light on the mec...The fluorescence staining method and scanning electron microscopy （SEM） were used to study the effect of ozone （O3） inactivating Cryptosporidium in water and cell ultrastructures variation to shed light on the mechanism of inactivation preliminarily. Results indicated that O3 had a stronger inactivating capability. When the concentration of O3 was above 3.0 mg/L and the contact time was up to 7 min, a significant inactivating effect could be achieved. The turbidity on inactivation effects was also found to be statistically significant in artificial water. With increases in turbidity, the inactivating effect decreased. Inactivation rate improved with a temperature increase from 5 to 25℃, but decreased beyond this. The inactivating capability of O3 was found to be stronger under acidic than that under alkalic conditions. When the concentration of organic matter in the reaction system was increased, the competition between Cryptosporidium and organics with O3 probably took place, thereby reducing the inactivation rate. In addition, the cellular morphology of Cryptosporidium varied with different contact times. At zero contact time, cells were rotundity and sphericity, at 60 sec they became folded, underwent emboly, and burst at 480 sec, the cell membrane of Cryptosporidium shrinked and collapsed completely.展开更多
The morphology and structures of antennal sensilla of Helicoverpa armigera are observed under scanning and transmission electron microscopes. Antennae of Helicoverpa armigera are made up of scapus, pedicel and flagell...The morphology and structures of antennal sensilla of Helicoverpa armigera are observed under scanning and transmission electron microscopes. Antennae of Helicoverpa armigera are made up of scapus, pedicel and flagellum that the latter consists of 70 - 82 segments. The inner side surface of antenna is cat-aphracted and most of the antennal sensilla lie on its outer, upper and lower surfaces. Both the antennae of male and female contain five kinds of antennal sensilla, namely, sensillum trichodeum, sensillum basicon-icum, sensillum chaeticum, ear-shaped sensillum and sensillum coeloconicum, and the kinds, number and distribution of antennal sensilla of both sexes are similar. There are a large number of serrate cuticular processes on antennal surface, especially on the middle and basic parts of antenna. Sensillum trichodeum and sensillum basiconicum, the main chemical odor receptors on antennae of Helicoverpa armigera, consist of cuticular-wall, sheath cells, lymph and dendrites. There are significant differences between the internal structures of the two kinds of sensilla. In sensillum trichodeum, the cuticular-wall is thicker, less lipophilic pore channels and has one or a few dendrites, while in sensillum basiconicum, the cuticular-wall is thinner, abundant lipophilic pore channels and has much more dendrites.展开更多
The therapeutic actions of Qing Luo Yin (QLY清络饮) with heat property and Wen Luo Yin (WLY温络饮) with cold property on pain, swelling of the ankle, arthritis index and ultrastructures of synoviocytes were compared i...The therapeutic actions of Qing Luo Yin (QLY清络饮) with heat property and Wen Luo Yin (WLY温络饮) with cold property on pain, swelling of the ankle, arthritis index and ultrastructures of synoviocytes were compared in rats of type II collagen-induced arthritis (CIA), with tripterygium glycosidorum (TG) used as control. The results indicated that both QLY and WLY could reduce pain, swelling of the ankle and the arthritis index of CIA, and QLY had better effects in reducing the swelling of the ankle and controlling the secondary pathological lesions as compared with WLY. Investigation on the ultrastructures of synoviocytes indicated that both QLY and WLY could reduce the number of Golgi apparatus, rough surface endoplasmic reticulum, dense bodies, matrix filaments and vacuoles so as to suppress the excessive secretion of synoviocytes in rats of CIA.展开更多
Fourteen normal human placental villi at a fetal age of 5-8 weeks were examined withelectron microscope. The results were vide infra.(1)The cytotrophoblasts were characterized by largenucleus with less heterochromatin...Fourteen normal human placental villi at a fetal age of 5-8 weeks were examined withelectron microscope. The results were vide infra.(1)The cytotrophoblasts were characterized by largenucleus with less heterochromatin and prominent nucleolus with a number of free polyribosomes as well asscattered mitochondria in the cytoplasm.(2) There was a layer of dense microvilli on the surface of thesyncytiotrophoblastic cells.The size and shape of microvilli were variable. Usually fine globular expansions were present at the apical pole of microvilli and the cell membrane between the base of microvillihad invaginations into the cytoplasm forming small vesicles and tubules. Rough endoplasmic reticulum,free polyribosomes,mitochondria, lipid droplets and few myelinlike figures were also found in the cytoplasm.Part of cytoplasm penetrated into the interspaces of cytotrophoblastic cells and became in directcontact with the basement membrane.(3) Numerous desmosomes were seen between the cells of cytotrophoblast and syncytiotrophoblast.And (4) in the strom a of villi,mesenchymal cells were abundant inrough endoplasmic reticulum and well developed Golgi complex. Mesenchymat cells were markedlyfunctionally active. Ultrastructural characteristics of placental villin in connexion with their functionwere discussed.展开更多
Portschinskia Semenov is a rare genus of bot fies whose larvae are obligate parasites of pikas and murine rodents,crucial for understanding the evolutionary biology of Oestridae.However,limited information on their ad...Portschinskia Semenov is a rare genus of bot fies whose larvae are obligate parasites of pikas and murine rodents,crucial for understanding the evolutionary biology of Oestridae.However,limited information on their adult biology and early immature stages has hindered the progress.Here,we provided the frst documentation of adult oviposition,behavior,and morphology of newly hatched frst instars of P.magnifca Pleske.Using confocal laser scanning microscopy and scanning electron microscopy,we characterized the ultrastructure of egg and frst-instar larva,identifying key traits facilitating attachment.Eggs were deposited individually or in groups,and glued on non-host surfaces with white adhesive substances,without specialized attachment organ.Newly hatched frst instars were circled with an anterior spinose band on each body segment except the anal division,awaited hosts in an upright position,and anchored to the egg shell by their anal division,likely supported by curved spines originating from the peritreme of the posterior spiracles.Evolutionary analyses of reproductive behavior across the 4 bot fy subfamilies reveal at least 3 times independent evolution of oviposition on non-host surfaces in Portschinskia or the Hypodermatinae clade as a sister group to Ochotonia,Gasterophilus pecorum(Fabricius)(Gasterophilinae),and Cuterebrinae.In contrast,species in the Oestrinae are larviparous,depositing frst instars directly onto hosts.Our fndings shed light on oviposition behavior and early immature morphology of the rare genus Portschinskia,offering insights into reproductive strategies and evolutionary adaptations of bot fies.展开更多
[Objectives]To elucidate the impact of different drying temperatures on the biochemical profile of tobacco(Nicotiana tabacum L.)leaves,the chemical constituents and ultrastructure of Yunyan 87 leaves subjected to diff...[Objectives]To elucidate the impact of different drying temperatures on the biochemical profile of tobacco(Nicotiana tabacum L.)leaves,the chemical constituents and ultrastructure of Yunyan 87 leaves subjected to different curing temperature settings.[Methods]Near-infrared spectroscopy techniques were utilized to analyze tobacco leaf samples,comparing the changes in chemical constituents at different curing temperatures.[Results]The CK treatment resulted in lower concentrations of nicotine,total nitrogen,chlorine,potassium,and starch,while simultaneously enhancing the levels of total sugar,reducing sugar,and protein.In comparison to the T treatment,the CK treatment appropriately altered the cell structure,reducing the content of cell wall substances.[Conclusions]These findings suggest that low-temperature curing at 44℃during the color-fixing stage is beneficial for improving the quality of tobacco leaves.展开更多
Rapid urbanization has contributed to global increases in air pollution derived from urban areas.Unlike natural forests,urban forests are exposed to higher concentrations of airborne pollutants due to the strong urban...Rapid urbanization has contributed to global increases in air pollution derived from urban areas.Unlike natural forests,urban forests are exposed to higher concentrations of airborne pollutants due to the strong urban-suburban-rural pollutant emission gradients.However,there remains a pressing lack of available information pertaining to the urban air pollutionrelated effects on the leaf economics spectrum,anatomical,ultrastructural,and stomatal traits of tree species along an urban-rural gradient.Here,the degree to which urban air pollution impacts the adaption of greening tree species and associated service functions was assessed by sampling five common tree species(Acer pictum,Fraxinus chinensis,Koelreuteria paniculata,Salix babylonica,Sophora japonica)along urban-rural-natural forests in the Beijing metropolitan region of China.These analyses revealed a significant reduction in leaf mass per unit area(-13.4%),leaf thickness(-16.7%),and stomatal area(-27.5%)with increasing proximity to areas of greater air pollution that coincide with significant increases in leaf tissue density(+12.6%),leaf nitrogen content(+10.1%),relative chlorophyll content(+2.7%),and stomatal density(+11.9%).Higher air pollution levels were associated with organelle changes including gradual disintegration of chloroplasts,larger intercellular spaces and apparent starch and plastoglobuli deposition.Air pollutionwas conducive to the strengthening of the trade-off potential and adaptation strategies of trees in urban ecosystems,which are associated with trees with a rapid investment return strategy associated with thick leaves and strong photosynthetic capacity.These results provide strong empirical evidence of the profound air pollution-induced changes in leaf functional traits and adaption ability of urban forest tree species.展开更多
Background:Astrocyte endfeet(AEF)serves as a key element of the blood-brain barrier and is important for the survival and maintenance of neuronal function.However,the immunohistochemical and ultrastructural changes of...Background:Astrocyte endfeet(AEF)serves as a key element of the blood-brain barrier and is important for the survival and maintenance of neuronal function.However,the immunohistochemical and ultrastructural changes of AEF in the CA1 and CA3 areas of the hippocampus over time following cerebral ischemia-reperfusion(IR)injury have not been well elucidated.Objectives:We investigated chronological changes in AEF in the gerbil hippocampal CA1 area from 3 h to 10 days following transient forebrain ischemia(TFI),and examined their association with neuronal death and tissue repair following IR injury.Changes in the CA3 area were also examined at 10 days post-TFI for comparative purposes.Methods:Neuronal death was confirmed using histochemistry,immunohistochemistry,and histofluorescence.Changes in AEF were examined by double immunofluorescence with glial fibrillary acidic protein(GFAP)and glucose transporter 1(GLUT1),and by transmission electron microscopy(TEM)for ultrastructural changes.Results:Significant TFI-induced neuronal death occurred in the CA1 area on day 5 following IR injury and persisted until 10 days after TFI,while no neuronal death(or loss)was found in the CA3 area after TFI.Looking at TFI-induced changes in AEF,at 3 and 6 h after TFI,GFAP-immunoreactive(+)AEF in the CA1 area appeared swollen and harbored enlarged,dark mitochondria,and the swelling was reduced by 1-day post-TFI.On 2 and 5 days following TFI,GFAP+AEF were markedly enlarged and fragmented,containing shrunken mitochondria,vacuolations,and sparse organelles.Ten days post-TFI,the ends of GFAP+astrocytic processes extended to microvessels,appeared edematous,and were filled with cellular debris.In the CA3 area,AEF was slightly dilated at 10 days after TFI.These findings indicate that damage to or disruption of AEF in the CA1 area occurs in the early phase after 5-min TFI but is rarely observed in the CA3 area.Conclusion:Taken together,damage to or disruption of AEF following ischemic insults may be strongly linked to neuronal death/loss.展开更多
Background:The medicinal material known as Os Draconis(Longgu)originates from fossilized remains of ancient mammals and is widely used in treating emotional and mental conditions.However,fossil resources are nonrenewa...Background:The medicinal material known as Os Draconis(Longgu)originates from fossilized remains of ancient mammals and is widely used in treating emotional and mental conditions.However,fossil resources are nonrenewable,and clinical demand is increasingly difficult to meet,leading to a proliferation of counterfeit products.During prolonged geological burial,static pressure from the surrounding strata severely compromises the microstructural integrity of osteons in Os Draconis,but Os Draconis still largely retains the structural features of mammalian bone.Methods:Using verified authentic Os Draconis samples over 10,000 years old as a baseline,this study summarizes the ultrastructural characteristics of genuine Os Draconis.Employing electron probe microanalysis and optical polarized light microscopy,we examined 28 batches of authentic Os Draconis and 31 batches of counterfeits to identify their ultrastructural differences.Key points for ultrastructural identification of Os Draconis were compiled,and a new identification approach was proposed based on these differences.Results:Authentic Os Draconis exhibited distinct ultrastructural markers:irregularly shaped osteons with traversing fissures,deformed/displaced Haversian canals,and secondary mineral infill(predominantly calcium carbonate).Counterfeits showed regular osteon arrangements,absent traversal fissures,and homogeneous hydroxyapatite composition.Lab-simulated samples lacked structural degradation features.EPMA confirmed calcium carbonate infill in fossilized Haversian canals,while elemental profiles differentiated lacunae types(void vs.mineral-packed).Conclusion:The study established ultrastructural criteria for authentic Os Draconis identification:osteon deformation,geological fissures penetrating bone units,and heterogenous mineral deposition.These features,unattainable in counterfeits or modern processed bones,provide a cost-effective,accurate identification method.This approach bridges gaps in TCM material standardization and supports quality control for clinical applications.展开更多
Rhododendron micranthum Turcz.is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China.We selected 3-year saplings and subjected them to four distinct light condi-tio...Rhododendron micranthum Turcz.is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China.We selected 3-year saplings and subjected them to four distinct light condi-tions:full light(CK),70%light(L1),50%light(L2),and 30%light(L3)to investigate variations in morphology,photosynthetic responses,stomatal ultrastructure as well as the mechanisms through which these saplings adapt to differing lighting environments.The results indicate that L2 leaves exhibit significantly greater length,width,and petiole development compared to other treatments across varying intensities.Over time,chlorophyll content and PSII levels in L2-treated saplings surpass those observed in other treatments;Proline(PRO),malondialdehyde(MDA),and soluble protein(SP)contents are markedly lower under L2 treatment.Catalase(CAT)and superoxide dismutase(SOD)demonstrate significant correlations across various light con-ditions but respond differently among treatments,indicat-ing distinct species sensitivities to light intensity while both contribute to environmental stress resistance mechanisms.Findings reveal that R.micranthum saplings at 50%light intensity benefit from enhanced protection via antioxidant enzymes,and shading reduces osmotic adjustment sub-stances yet increases chlorophyll content.Stomatal length/width along with conductance rates and net photosynthesis rates for L2 exceed those of CK,suggesting an improved photosynthetic structure conducive to efficient photosynthe-sis under this condition.Thus,moderate shading represents optimal growth at 50%illumination,a critical factor promot-ing sapling development.This research elucidates the ideal environment for R.micranthum adaptation to varying light conditions supporting future conservation initiatives.展开更多
The giant triton snail Charonia tritonis is a marine large carnivorous gastropoda inhabiting in the Indo-Pacific Ocean.Their splendid and highly organized Charonia tritonis shells are attractive;however few studies ha...The giant triton snail Charonia tritonis is a marine large carnivorous gastropoda inhabiting in the Indo-Pacific Ocean.Their splendid and highly organized Charonia tritonis shells are attractive;however few studies have been conducted on shell ultra-structure and pigmentation.The arrangements of crossed-lamellar structures were distinctive for the giant triton snail shell,showing three layers of mineral structures in the cross-section.The 1st-order and 2nd-order lamellae of the shell were around 10-20μm and the crystals in outer layers intersected at right angles in this species.They were identified as aragonite crystals by Raman scattering,and granular organic matrix were attached to the aragonite mineral phase closely.Furthermore,the dominant Raman spectra from polyene pigments in the shell were characterized at wavenumbers of 1123 cm^(-1)and 1504 cm^(-1),assigned to stretching vibrations of carbon-carbon single(C-C)and double(C=C)bonds,and the polyene chain was confirmed with 11-12 C-C bonds and 12-13 conju-gated C=C bonds.The research will lay a foundation for exploring the relationship between the calcareous shell and the formation of shell color in the giant triton snail.展开更多
Abundant sphaeroidal acritarch Leiosphaeridia asperata,with vesicle size ranging from 13 to 360 μm,occurred in the Proterozoic Liulaobei Formation shales in Huainan,Anhui Province.TEM/SEM studies of these sphaeroidal...Abundant sphaeroidal acritarch Leiosphaeridia asperata,with vesicle size ranging from 13 to 360 μm,occurred in the Proterozoic Liulaobei Formation shales in Huainan,Anhui Province.TEM/SEM studies of these sphaeroidal acritarchs have revealed complex ultrastructures,including ridges,bands,and possible trilaminar structures(TLS).Ridges,spaced ~1 μm apart,are distributed regularly on the vesicle internal surface of one specimen.Some specimens have alternating electron-dense and electron-tenuous bands that are perpendicular to vesicle walls.Some specimens have trilaminar structures(TLS),while a few others have both bands and TLS.These wall ultrastructures provide evidence that the Liulaobei leiosphaerids are of green microalgae.The variation in wall ultrastructures may represent various stages in a life cycle or developmental phases in the cyst formation analogous to some modern chlorophyceaen microalgae.展开更多
An SEM study has been conducted to examine the ultrastructures in the spirotheca of Fusulinella and to reveal the ultra-features of the basic layers consisting of the spirotheca of Fusulinella. The study has demonstra...An SEM study has been conducted to examine the ultrastructures in the spirotheca of Fusulinella and to reveal the ultra-features of the basic layers consisting of the spirotheca of Fusulinella. The study has demonstrated that the diaphanotheca in the spirotheca of Fusulinella could be considered as a secondary structure.展开更多
The myelin sheath is a lipoprotein-rich,multilayered structure capable of increasing conduction velocity in central and peripheral myelinated nerve fibers.Due to the complex structure and composition of myelin,various...The myelin sheath is a lipoprotein-rich,multilayered structure capable of increasing conduction velocity in central and peripheral myelinated nerve fibers.Due to the complex structure and composition of myelin,various histological techniques have been developed over the centuries to evaluate myelin under normal,pathological or experimental conditions.Today,methods to assess myelin integrity or content are key tools in both clinical diagnosis and neuroscience research.In this review,we provide an updated summary of the composition and structure of the myelin sheath and discuss some histological procedures,from tissue fixation and processing techniques to the most used and practical myelin histological staining methods.Considering the lipoprotein nature of myelin,the main features and technical details of the different available methods that can be used to evaluate the lipid or protein components of myelin are described,as well as the precise ultrastructural techniques.展开更多
The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different ...The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different light intensities in various habitats affect eco-physiological characteristics of saplings and their natural regeneration.In this study,the light intensity in T.sinense habitats was simulated by artificial shading(L1:100%NS(natural sunlight)in the open;L2:50%NS in a forest gap or edge;L3:10%NS in understory)to investigate differences in morphology,leaf structure,physiology,and photosynthesis of 2-year-old sap-lings,and to analyze the mechanism of light intensity on sapling establishment.Significant differences were observed in morphology(including leaf area,and specific leaf area)under different light intensities.Compared to L1 and L3,chloroplast structure in L2 was intact.With increasing time,superoxide dismutase(SOD)and catalase(CAT)activities in L2 became gradually higher than under the other light intensities,while malondialdehyde(MDA)content was opposite.Shading decreased osmoregulation substance contents of leaves but increased chlorophyll.The results suggest that light intensities significantly affect the eco-physiological characteristics of T.sinense saplings and they would respond most favorably at intermediate levels of light by optimizing eco-physiological characteristics.Therefore,50%natural sunlight should be created to promote saplings establishment and population recovery of T.sinense during in situ conservation,including sowing mature seeds in forest edges or gaps and providing appropriate shade protection for seedlings and saplings in the open.展开更多
In this study,the morphology and ultrastructure of the compound eye of L.lewisii were investigated using scanning electron microscopy(SEM),transmission electron microscopy(TEM),microcomputed tomography(μCT),and 3D re...In this study,the morphology and ultrastructure of the compound eye of L.lewisii were investigated using scanning electron microscopy(SEM),transmission electron microscopy(TEM),microcomputed tomography(μCT),and 3D reconstruction.The compound eye of L.lewisii was of the apposition type,with an average of 121.88±7.64 ommatidia in males and 119.00±4.71 ommatidia in females.Each ommatidium was composed of a biconvex cornea,an acone consisting of four cone cells,eight retinular cells along with the rhabdom,two primary pigment cells,and numerous secondary pigment cells.The open type of rhabdom in L.lewisii consists of six peripheral rhabdomeres contributed by the six peripheral retinular cells(R1~R6)and two vertically attached central rhabdomeres contributed by R7 and R8 respectively.The orientation of microvilli suggested a weak sensitivity to polarized light perception.展开更多
BACKGROUND Excessive saturated fat intake compromises the integrity of the intestinal mucosa,leading to low-grade inflammation,impaired mucosal integrity,and increased intestinal permeability,resulting in the migratio...BACKGROUND Excessive saturated fat intake compromises the integrity of the intestinal mucosa,leading to low-grade inflammation,impaired mucosal integrity,and increased intestinal permeability,resulting in the migration of lipopolysaccharide(LPS)to other tissues.AIM To evaluate the chronic effects(at 10 and 16 wk)of a high-fat diet(HFD)(with 50%energy as fat)on the phylogenetic gut microbiota distribution and intestinal barrier structure and protection in C57BL/6 mice.METHODS Forty adult male mice were divided into four nutritional groups,where the letters refer to the type of diet(control and HFD or HF)and the numbers refer to the period(in weeks)of diet administration:Control diet for 10 wk,HFD for 10 wk,control diet for 16 wk,and HFD for 16 wk.After sacrifice,biochemical,molecular,and stereological analyses were performed.RESULTS The HF groups were overweight,had gut dysbiosis,had a progressive decrease in occludin immunostaining,and had increased LPS concentrations.Dietary progression reduced the number of goblet cells per large intestine area and Mucin2 expression in the HF16 group,consistent with a completely disarranged intestinal ultrastructure after 16 wk of HFD intake.CONCLUSION Chronic HFD intake causes overweight,gut dysbiosis,and morphological and functional alterations of the intestinal barrier after 10 or 16 wk.Time-dependent reductions in goblet cell numerical density and mucus production have emerged as targets for countering obesity-driven intestinal damage.展开更多
All nuclei in mesophyll cells of Artemisia marschalliana are located in vacuoles and occupy up to 90% of their volume. The ultrastructural organization of chromatin in nuclei shows different degrees of its decondensat...All nuclei in mesophyll cells of Artemisia marschalliana are located in vacuoles and occupy up to 90% of their volume. The ultrastructural organization of chromatin in nuclei shows different degrees of its decondensation, up to complete separation of DNA from histones. It is possible that the separation of DNA from histones enables Artemisia to grow in soils with high salinity.展开更多
The toxic effects of different gradient concentrations of Hg2+ and Cd2+ on chlorophyll content, chlorophyll a/b value, photosynthetic O-2 evolution, respiration rate, anti-oxidase system (superoxide dismulase (SOD), c...The toxic effects of different gradient concentrations of Hg2+ and Cd2+ on chlorophyll content, chlorophyll a/b value, photosynthetic O-2 evolution, respiration rate, anti-oxidase system (superoxide dismulase (SOD), catalase (CAT), peroxidase (POD)) and ultrastructure of the cells of Azolla imbricata (Roxb.) Nakai were studied. The results showed that with Hg2+ and Cd2+ increase, chlorophyll content and chlorophyll a/b value, photosynthetic O-2 evolution decreased drastically; respiration rate peaked at 2 mg/L pollutant and declined afterwards. The activities of SOD, CAT and POD increased first and decreased afterwards except the activity of POD, which decreased with the increasing of Cd2+ concentration. Ultrastructural observation showed that the extent of ultrastructural damage was much more serious with higher pollutant concentration and longer time of stress. This resulted in swelling of chloroplast, disruption and disappearance of chloroplast membrane and disintegration of chloroplasts; swelling of cristae of mitochondria, deformation and vacuolization of mitochondria; condensation of chromatin in nucleus, dispersion of nucleolus and disruption of nuclear membrane. The experimental results showed: (1) Hg2+ and Cd2+ pollution not only destroyed physiological activities, but also caused irreversible damage to its ultrastructure, thus leading the cells to death; (2) With increase in the stress of Hg2+ and Cd2+, ultrastructural damage was related to the changes of plant physiology; (3) The toxic symptoms of plant showed an evident correlation between dose and effect; (4) The toxicity of Cd2+ on A. imbricata is heavier than that of Hg2+ under the same treatment time and concentration. The lethal concentration of Hg2+ to A. imbricata ranged from 3.5 to 4 mg/L, and that of Cd2+ ranged from 3 to 3.5 mg/L. The damage of cell ultrastructure on Anabaena azollae Strasburger was observed. The results indicated that tolerance of Azolla imbricata for Hg2+ and Cd2+ was higher than that of A. imbricata.展开更多
Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing...Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing ribosomes, mitochondria and Golgi bodies in the dense cytoplasm. During the wall thickening, the number of rough endoplasmic reticulum and Golgi bodies increased apparently. There were two kinds of Golgi vesicles, together with the ones from endoplasmic reticulum formed transport vesicles. Many microtubules were arranged parallel to the long axis of the cell adjacent to the plasmalemma. Along with the further development of fiber, polylamellate structure of the secondary wall appeared, with concurrent agglutination of chromatin in the nucleus, swelling and disintegration of organelles, while cortical microtubules were still arranged neatly against the inner side of plasmalemma. Lomasomes could be observed between the wall and plasmalemma. The results indicated that the organelles, such as Golgi bodies together with small vesicles, rough endoplasmic reticulum and lomasomes, played the key role in the thickening and lignification of the secondary wall of bamboo fiber, though cortical microtubules were correlative with the process as well.展开更多
基金supported by the National High Technology Research and Development Program (863) of China(No. 2006AAZ309)
文摘The fluorescence staining method and scanning electron microscopy （SEM） were used to study the effect of ozone （O3） inactivating Cryptosporidium in water and cell ultrastructures variation to shed light on the mechanism of inactivation preliminarily. Results indicated that O3 had a stronger inactivating capability. When the concentration of O3 was above 3.0 mg/L and the contact time was up to 7 min, a significant inactivating effect could be achieved. The turbidity on inactivation effects was also found to be statistically significant in artificial water. With increases in turbidity, the inactivating effect decreased. Inactivation rate improved with a temperature increase from 5 to 25℃, but decreased beyond this. The inactivating capability of O3 was found to be stronger under acidic than that under alkalic conditions. When the concentration of organic matter in the reaction system was increased, the competition between Cryptosporidium and organics with O3 probably took place, thereby reducing the inactivation rate. In addition, the cellular morphology of Cryptosporidium varied with different contact times. At zero contact time, cells were rotundity and sphericity, at 60 sec they became folded, underwent emboly, and burst at 480 sec, the cell membrane of Cryptosporidium shrinked and collapsed completely.
文摘The morphology and structures of antennal sensilla of Helicoverpa armigera are observed under scanning and transmission electron microscopes. Antennae of Helicoverpa armigera are made up of scapus, pedicel and flagellum that the latter consists of 70 - 82 segments. The inner side surface of antenna is cat-aphracted and most of the antennal sensilla lie on its outer, upper and lower surfaces. Both the antennae of male and female contain five kinds of antennal sensilla, namely, sensillum trichodeum, sensillum basicon-icum, sensillum chaeticum, ear-shaped sensillum and sensillum coeloconicum, and the kinds, number and distribution of antennal sensilla of both sexes are similar. There are a large number of serrate cuticular processes on antennal surface, especially on the middle and basic parts of antenna. Sensillum trichodeum and sensillum basiconicum, the main chemical odor receptors on antennae of Helicoverpa armigera, consist of cuticular-wall, sheath cells, lymph and dendrites. There are significant differences between the internal structures of the two kinds of sensilla. In sensillum trichodeum, the cuticular-wall is thicker, less lipophilic pore channels and has one or a few dendrites, while in sensillum basiconicum, the cuticular-wall is thinner, abundant lipophilic pore channels and has much more dendrites.
文摘The therapeutic actions of Qing Luo Yin (QLY清络饮) with heat property and Wen Luo Yin (WLY温络饮) with cold property on pain, swelling of the ankle, arthritis index and ultrastructures of synoviocytes were compared in rats of type II collagen-induced arthritis (CIA), with tripterygium glycosidorum (TG) used as control. The results indicated that both QLY and WLY could reduce pain, swelling of the ankle and the arthritis index of CIA, and QLY had better effects in reducing the swelling of the ankle and controlling the secondary pathological lesions as compared with WLY. Investigation on the ultrastructures of synoviocytes indicated that both QLY and WLY could reduce the number of Golgi apparatus, rough surface endoplasmic reticulum, dense bodies, matrix filaments and vacuoles so as to suppress the excessive secretion of synoviocytes in rats of CIA.
文摘Fourteen normal human placental villi at a fetal age of 5-8 weeks were examined withelectron microscope. The results were vide infra.(1)The cytotrophoblasts were characterized by largenucleus with less heterochromatin and prominent nucleolus with a number of free polyribosomes as well asscattered mitochondria in the cytoplasm.(2) There was a layer of dense microvilli on the surface of thesyncytiotrophoblastic cells.The size and shape of microvilli were variable. Usually fine globular expansions were present at the apical pole of microvilli and the cell membrane between the base of microvillihad invaginations into the cytoplasm forming small vesicles and tubules. Rough endoplasmic reticulum,free polyribosomes,mitochondria, lipid droplets and few myelinlike figures were also found in the cytoplasm.Part of cytoplasm penetrated into the interspaces of cytotrophoblastic cells and became in directcontact with the basement membrane.(3) Numerous desmosomes were seen between the cells of cytotrophoblast and syncytiotrophoblast.And (4) in the strom a of villi,mesenchymal cells were abundant inrough endoplasmic reticulum and well developed Golgi complex. Mesenchymat cells were markedlyfunctionally active. Ultrastructural characteristics of placental villin in connexion with their functionwere discussed.
基金supported by the National Natural Science Foundation of China(grant numbers 32170450 and 31872964)Science&Technology Fundamental Resources Investigation Program(grant number 2022FY202100).
文摘Portschinskia Semenov is a rare genus of bot fies whose larvae are obligate parasites of pikas and murine rodents,crucial for understanding the evolutionary biology of Oestridae.However,limited information on their adult biology and early immature stages has hindered the progress.Here,we provided the frst documentation of adult oviposition,behavior,and morphology of newly hatched frst instars of P.magnifca Pleske.Using confocal laser scanning microscopy and scanning electron microscopy,we characterized the ultrastructure of egg and frst-instar larva,identifying key traits facilitating attachment.Eggs were deposited individually or in groups,and glued on non-host surfaces with white adhesive substances,without specialized attachment organ.Newly hatched frst instars were circled with an anterior spinose band on each body segment except the anal division,awaited hosts in an upright position,and anchored to the egg shell by their anal division,likely supported by curved spines originating from the peritreme of the posterior spiracles.Evolutionary analyses of reproductive behavior across the 4 bot fy subfamilies reveal at least 3 times independent evolution of oviposition on non-host surfaces in Portschinskia or the Hypodermatinae clade as a sister group to Ochotonia,Gasterophilus pecorum(Fabricius)(Gasterophilinae),and Cuterebrinae.In contrast,species in the Oestrinae are larviparous,depositing frst instars directly onto hosts.Our fndings shed light on oviposition behavior and early immature morphology of the rare genus Portschinskia,offering insights into reproductive strategies and evolutionary adaptations of bot fies.
基金Supported by the Science and Technology Project of Guizhou Provincial Company,CNTC(2023XM22)Science and Technology Program of Science and Technology Department of Guizhou Province(QKHPTRC-GCC[2023]067,QKHJC-ZK[2022]YB288)+2 种基金Science and Technology Project of Bijie City of Guizhou Provincial Tobacco Company(2021520500240228)Science and Technology Project of Zunyi City of Guizhou Provincial Tobacco Company(2023XM06)Science and Technology Project of Guizhou Academy of Tobacco Science(GZYKY2022-02).
文摘[Objectives]To elucidate the impact of different drying temperatures on the biochemical profile of tobacco(Nicotiana tabacum L.)leaves,the chemical constituents and ultrastructure of Yunyan 87 leaves subjected to different curing temperature settings.[Methods]Near-infrared spectroscopy techniques were utilized to analyze tobacco leaf samples,comparing the changes in chemical constituents at different curing temperatures.[Results]The CK treatment resulted in lower concentrations of nicotine,total nitrogen,chlorine,potassium,and starch,while simultaneously enhancing the levels of total sugar,reducing sugar,and protein.In comparison to the T treatment,the CK treatment appropriately altered the cell structure,reducing the content of cell wall substances.[Conclusions]These findings suggest that low-temperature curing at 44℃during the color-fixing stage is beneficial for improving the quality of tobacco leaves.
基金supported by the National Natural Science Foundation of China(No.32271673)5·5 Engineering Research&Innovation Team Project of Beijing Forestry University(No.BLRC2023B06).
文摘Rapid urbanization has contributed to global increases in air pollution derived from urban areas.Unlike natural forests,urban forests are exposed to higher concentrations of airborne pollutants due to the strong urban-suburban-rural pollutant emission gradients.However,there remains a pressing lack of available information pertaining to the urban air pollutionrelated effects on the leaf economics spectrum,anatomical,ultrastructural,and stomatal traits of tree species along an urban-rural gradient.Here,the degree to which urban air pollution impacts the adaption of greening tree species and associated service functions was assessed by sampling five common tree species(Acer pictum,Fraxinus chinensis,Koelreuteria paniculata,Salix babylonica,Sophora japonica)along urban-rural-natural forests in the Beijing metropolitan region of China.These analyses revealed a significant reduction in leaf mass per unit area(-13.4%),leaf thickness(-16.7%),and stomatal area(-27.5%)with increasing proximity to areas of greater air pollution that coincide with significant increases in leaf tissue density(+12.6%),leaf nitrogen content(+10.1%),relative chlorophyll content(+2.7%),and stomatal density(+11.9%).Higher air pollution levels were associated with organelle changes including gradual disintegration of chloroplasts,larger intercellular spaces and apparent starch and plastoglobuli deposition.Air pollutionwas conducive to the strengthening of the trade-off potential and adaptation strategies of trees in urban ecosystems,which are associated with trees with a rapid investment return strategy associated with thick leaves and strong photosynthetic capacity.These results provide strong empirical evidence of the profound air pollution-induced changes in leaf functional traits and adaption ability of urban forest tree species.
基金supported by 2024 Research Grant from Kangwon National University(M.C.S)and the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2021R1A2C1094224)(J.H.A).
文摘Background:Astrocyte endfeet(AEF)serves as a key element of the blood-brain barrier and is important for the survival and maintenance of neuronal function.However,the immunohistochemical and ultrastructural changes of AEF in the CA1 and CA3 areas of the hippocampus over time following cerebral ischemia-reperfusion(IR)injury have not been well elucidated.Objectives:We investigated chronological changes in AEF in the gerbil hippocampal CA1 area from 3 h to 10 days following transient forebrain ischemia(TFI),and examined their association with neuronal death and tissue repair following IR injury.Changes in the CA3 area were also examined at 10 days post-TFI for comparative purposes.Methods:Neuronal death was confirmed using histochemistry,immunohistochemistry,and histofluorescence.Changes in AEF were examined by double immunofluorescence with glial fibrillary acidic protein(GFAP)and glucose transporter 1(GLUT1),and by transmission electron microscopy(TEM)for ultrastructural changes.Results:Significant TFI-induced neuronal death occurred in the CA1 area on day 5 following IR injury and persisted until 10 days after TFI,while no neuronal death(or loss)was found in the CA3 area after TFI.Looking at TFI-induced changes in AEF,at 3 and 6 h after TFI,GFAP-immunoreactive(+)AEF in the CA1 area appeared swollen and harbored enlarged,dark mitochondria,and the swelling was reduced by 1-day post-TFI.On 2 and 5 days following TFI,GFAP+AEF were markedly enlarged and fragmented,containing shrunken mitochondria,vacuolations,and sparse organelles.Ten days post-TFI,the ends of GFAP+astrocytic processes extended to microvessels,appeared edematous,and were filled with cellular debris.In the CA3 area,AEF was slightly dilated at 10 days after TFI.These findings indicate that damage to or disruption of AEF in the CA1 area occurs in the early phase after 5-min TFI but is rarely observed in the CA3 area.Conclusion:Taken together,damage to or disruption of AEF following ischemic insults may be strongly linked to neuronal death/loss.
基金supported by the Scientific and Technological Innovation Project of the China Academy of Chinese Medical Sciences(CI2021A04013)the National Natural Science Foundation of China(82204610)+1 种基金the Qihang Talent Program(L2022046)the Fundamental Research Funds for the Central Public Welfare Research Institutes(ZZ15-YQ-041 and L2021029).
文摘Background:The medicinal material known as Os Draconis(Longgu)originates from fossilized remains of ancient mammals and is widely used in treating emotional and mental conditions.However,fossil resources are nonrenewable,and clinical demand is increasingly difficult to meet,leading to a proliferation of counterfeit products.During prolonged geological burial,static pressure from the surrounding strata severely compromises the microstructural integrity of osteons in Os Draconis,but Os Draconis still largely retains the structural features of mammalian bone.Methods:Using verified authentic Os Draconis samples over 10,000 years old as a baseline,this study summarizes the ultrastructural characteristics of genuine Os Draconis.Employing electron probe microanalysis and optical polarized light microscopy,we examined 28 batches of authentic Os Draconis and 31 batches of counterfeits to identify their ultrastructural differences.Key points for ultrastructural identification of Os Draconis were compiled,and a new identification approach was proposed based on these differences.Results:Authentic Os Draconis exhibited distinct ultrastructural markers:irregularly shaped osteons with traversing fissures,deformed/displaced Haversian canals,and secondary mineral infill(predominantly calcium carbonate).Counterfeits showed regular osteon arrangements,absent traversal fissures,and homogeneous hydroxyapatite composition.Lab-simulated samples lacked structural degradation features.EPMA confirmed calcium carbonate infill in fossilized Haversian canals,while elemental profiles differentiated lacunae types(void vs.mineral-packed).Conclusion:The study established ultrastructural criteria for authentic Os Draconis identification:osteon deformation,geological fissures penetrating bone units,and heterogenous mineral deposition.These features,unattainable in counterfeits or modern processed bones,provide a cost-effective,accurate identification method.This approach bridges gaps in TCM material standardization and supports quality control for clinical applications.
基金funded by the National Natural Science Foundation of China(No.32171770)Natural Science Foundation Program of Jilin Provincial Department of Education(No.JJKH20230074KJ).
文摘Rhododendron micranthum Turcz.is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China.We selected 3-year saplings and subjected them to four distinct light condi-tions:full light(CK),70%light(L1),50%light(L2),and 30%light(L3)to investigate variations in morphology,photosynthetic responses,stomatal ultrastructure as well as the mechanisms through which these saplings adapt to differing lighting environments.The results indicate that L2 leaves exhibit significantly greater length,width,and petiole development compared to other treatments across varying intensities.Over time,chlorophyll content and PSII levels in L2-treated saplings surpass those observed in other treatments;Proline(PRO),malondialdehyde(MDA),and soluble protein(SP)contents are markedly lower under L2 treatment.Catalase(CAT)and superoxide dismutase(SOD)demonstrate significant correlations across various light con-ditions but respond differently among treatments,indicat-ing distinct species sensitivities to light intensity while both contribute to environmental stress resistance mechanisms.Findings reveal that R.micranthum saplings at 50%light intensity benefit from enhanced protection via antioxidant enzymes,and shading reduces osmotic adjustment sub-stances yet increases chlorophyll content.Stomatal length/width along with conductance rates and net photosynthesis rates for L2 exceed those of CK,suggesting an improved photosynthetic structure conducive to efficient photosynthe-sis under this condition.Thus,moderate shading represents optimal growth at 50%illumination,a critical factor promot-ing sapling development.This research elucidates the ideal environment for R.micranthum adaptation to varying light conditions supporting future conservation initiatives.
基金funded by the Guangzhou Sci-ence and Technology Project(No.201803020017).
文摘The giant triton snail Charonia tritonis is a marine large carnivorous gastropoda inhabiting in the Indo-Pacific Ocean.Their splendid and highly organized Charonia tritonis shells are attractive;however few studies have been conducted on shell ultra-structure and pigmentation.The arrangements of crossed-lamellar structures were distinctive for the giant triton snail shell,showing three layers of mineral structures in the cross-section.The 1st-order and 2nd-order lamellae of the shell were around 10-20μm and the crystals in outer layers intersected at right angles in this species.They were identified as aragonite crystals by Raman scattering,and granular organic matrix were attached to the aragonite mineral phase closely.Furthermore,the dominant Raman spectra from polyene pigments in the shell were characterized at wavenumbers of 1123 cm^(-1)and 1504 cm^(-1),assigned to stretching vibrations of carbon-carbon single(C-C)and double(C=C)bonds,and the polyene chain was confirmed with 11-12 C-C bonds and 12-13 conju-gated C=C bonds.The research will lay a foundation for exploring the relationship between the calcareous shell and the formation of shell color in the giant triton snail.
基金supported financially by Chinese Academy of Sciences (Grant No. KZCX2-YW-153)National Basic Research Program of China (Grant No. 2006CB806400National Natural Science Foundation of China (Grant Nos. 40772021,40625006)
文摘Abundant sphaeroidal acritarch Leiosphaeridia asperata,with vesicle size ranging from 13 to 360 μm,occurred in the Proterozoic Liulaobei Formation shales in Huainan,Anhui Province.TEM/SEM studies of these sphaeroidal acritarchs have revealed complex ultrastructures,including ridges,bands,and possible trilaminar structures(TLS).Ridges,spaced ~1 μm apart,are distributed regularly on the vesicle internal surface of one specimen.Some specimens have alternating electron-dense and electron-tenuous bands that are perpendicular to vesicle walls.Some specimens have trilaminar structures(TLS),while a few others have both bands and TLS.These wall ultrastructures provide evidence that the Liulaobei leiosphaerids are of green microalgae.The variation in wall ultrastructures may represent various stages in a life cycle or developmental phases in the cyst formation analogous to some modern chlorophyceaen microalgae.
基金Project supported by a grant from the Chinese National Natural Science Foundation for Young Scientists
文摘An SEM study has been conducted to examine the ultrastructures in the spirotheca of Fusulinella and to reveal the ultra-features of the basic layers consisting of the spirotheca of Fusulinella. The study has demonstrated that the diaphanotheca in the spirotheca of Fusulinella could be considered as a secondary structure.
基金supported by the Spanish“Plan Nacional de Investigación Científica,Desarrollo e Innovación Tecnológica,Ministerio de Economía y Competitividad(Instituto de Salud CarlosⅢ)”,Grant FIS PI20-0318 co-financed by“Fondo Europeo de Desarrollo Regional ERDF-FEDER European Union”Grant P18-RT-5059“Plan Andaluz de Investigación,Desarrollo e Innovación(PAIDI 2020),Consejería de Transformación Económica,Industria,Conocimiento y Universidades,Junta de Andalucía,Espana”(all to VC)Grant PPJIA202219“Ayudas del plan propio UGR 2022,Plan propio de investigación y transferencia,Universidad de Granada,Espana”(to JCA andóDGG)。
文摘The myelin sheath is a lipoprotein-rich,multilayered structure capable of increasing conduction velocity in central and peripheral myelinated nerve fibers.Due to the complex structure and composition of myelin,various histological techniques have been developed over the centuries to evaluate myelin under normal,pathological or experimental conditions.Today,methods to assess myelin integrity or content are key tools in both clinical diagnosis and neuroscience research.In this review,we provide an updated summary of the composition and structure of the myelin sheath and discuss some histological procedures,from tissue fixation and processing techniques to the most used and practical myelin histological staining methods.Considering the lipoprotein nature of myelin,the main features and technical details of the different available methods that can be used to evaluate the lipid or protein components of myelin are described,as well as the precise ultrastructural techniques.
基金funded by the National Natural Science Foundation of China (No.32070371)the Innovation Team Funds of China West Normal University (No.KCXTD2022-4)+1 种基金the fund of Sichuan Meigu Dafegnding National Nature Reserve (No.mgdfd2022-13)Sichuan Micang Mountain National Nature Reserve (No.N5108212022000043)。
文摘The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different light intensities in various habitats affect eco-physiological characteristics of saplings and their natural regeneration.In this study,the light intensity in T.sinense habitats was simulated by artificial shading(L1:100%NS(natural sunlight)in the open;L2:50%NS in a forest gap or edge;L3:10%NS in understory)to investigate differences in morphology,leaf structure,physiology,and photosynthesis of 2-year-old sap-lings,and to analyze the mechanism of light intensity on sapling establishment.Significant differences were observed in morphology(including leaf area,and specific leaf area)under different light intensities.Compared to L1 and L3,chloroplast structure in L2 was intact.With increasing time,superoxide dismutase(SOD)and catalase(CAT)activities in L2 became gradually higher than under the other light intensities,while malondialdehyde(MDA)content was opposite.Shading decreased osmoregulation substance contents of leaves but increased chlorophyll.The results suggest that light intensities significantly affect the eco-physiological characteristics of T.sinense saplings and they would respond most favorably at intermediate levels of light by optimizing eco-physiological characteristics.Therefore,50%natural sunlight should be created to promote saplings establishment and population recovery of T.sinense during in situ conservation,including sowing mature seeds in forest edges or gaps and providing appropriate shade protection for seedlings and saplings in the open.
文摘In this study,the morphology and ultrastructure of the compound eye of L.lewisii were investigated using scanning electron microscopy(SEM),transmission electron microscopy(TEM),microcomputed tomography(μCT),and 3D reconstruction.The compound eye of L.lewisii was of the apposition type,with an average of 121.88±7.64 ommatidia in males and 119.00±4.71 ommatidia in females.Each ommatidium was composed of a biconvex cornea,an acone consisting of four cone cells,eight retinular cells along with the rhabdom,two primary pigment cells,and numerous secondary pigment cells.The open type of rhabdom in L.lewisii consists of six peripheral rhabdomeres contributed by the six peripheral retinular cells(R1~R6)and two vertically attached central rhabdomeres contributed by R7 and R8 respectively.The orientation of microvilli suggested a weak sensitivity to polarized light perception.
文摘BACKGROUND Excessive saturated fat intake compromises the integrity of the intestinal mucosa,leading to low-grade inflammation,impaired mucosal integrity,and increased intestinal permeability,resulting in the migration of lipopolysaccharide(LPS)to other tissues.AIM To evaluate the chronic effects(at 10 and 16 wk)of a high-fat diet(HFD)(with 50%energy as fat)on the phylogenetic gut microbiota distribution and intestinal barrier structure and protection in C57BL/6 mice.METHODS Forty adult male mice were divided into four nutritional groups,where the letters refer to the type of diet(control and HFD or HF)and the numbers refer to the period(in weeks)of diet administration:Control diet for 10 wk,HFD for 10 wk,control diet for 16 wk,and HFD for 16 wk.After sacrifice,biochemical,molecular,and stereological analyses were performed.RESULTS The HF groups were overweight,had gut dysbiosis,had a progressive decrease in occludin immunostaining,and had increased LPS concentrations.Dietary progression reduced the number of goblet cells per large intestine area and Mucin2 expression in the HF16 group,consistent with a completely disarranged intestinal ultrastructure after 16 wk of HFD intake.CONCLUSION Chronic HFD intake causes overweight,gut dysbiosis,and morphological and functional alterations of the intestinal barrier after 10 or 16 wk.Time-dependent reductions in goblet cell numerical density and mucus production have emerged as targets for countering obesity-driven intestinal damage.
文摘All nuclei in mesophyll cells of Artemisia marschalliana are located in vacuoles and occupy up to 90% of their volume. The ultrastructural organization of chromatin in nuclei shows different degrees of its decondensation, up to complete separation of DNA from histones. It is possible that the separation of DNA from histones enables Artemisia to grow in soils with high salinity.
文摘The toxic effects of different gradient concentrations of Hg2+ and Cd2+ on chlorophyll content, chlorophyll a/b value, photosynthetic O-2 evolution, respiration rate, anti-oxidase system (superoxide dismulase (SOD), catalase (CAT), peroxidase (POD)) and ultrastructure of the cells of Azolla imbricata (Roxb.) Nakai were studied. The results showed that with Hg2+ and Cd2+ increase, chlorophyll content and chlorophyll a/b value, photosynthetic O-2 evolution decreased drastically; respiration rate peaked at 2 mg/L pollutant and declined afterwards. The activities of SOD, CAT and POD increased first and decreased afterwards except the activity of POD, which decreased with the increasing of Cd2+ concentration. Ultrastructural observation showed that the extent of ultrastructural damage was much more serious with higher pollutant concentration and longer time of stress. This resulted in swelling of chloroplast, disruption and disappearance of chloroplast membrane and disintegration of chloroplasts; swelling of cristae of mitochondria, deformation and vacuolization of mitochondria; condensation of chromatin in nucleus, dispersion of nucleolus and disruption of nuclear membrane. The experimental results showed: (1) Hg2+ and Cd2+ pollution not only destroyed physiological activities, but also caused irreversible damage to its ultrastructure, thus leading the cells to death; (2) With increase in the stress of Hg2+ and Cd2+, ultrastructural damage was related to the changes of plant physiology; (3) The toxic symptoms of plant showed an evident correlation between dose and effect; (4) The toxicity of Cd2+ on A. imbricata is heavier than that of Hg2+ under the same treatment time and concentration. The lethal concentration of Hg2+ to A. imbricata ranged from 3.5 to 4 mg/L, and that of Cd2+ ranged from 3 to 3.5 mg/L. The damage of cell ultrastructure on Anabaena azollae Strasburger was observed. The results indicated that tolerance of Azolla imbricata for Hg2+ and Cd2+ was higher than that of A. imbricata.
文摘Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing ribosomes, mitochondria and Golgi bodies in the dense cytoplasm. During the wall thickening, the number of rough endoplasmic reticulum and Golgi bodies increased apparently. There were two kinds of Golgi vesicles, together with the ones from endoplasmic reticulum formed transport vesicles. Many microtubules were arranged parallel to the long axis of the cell adjacent to the plasmalemma. Along with the further development of fiber, polylamellate structure of the secondary wall appeared, with concurrent agglutination of chromatin in the nucleus, swelling and disintegration of organelles, while cortical microtubules were still arranged neatly against the inner side of plasmalemma. Lomasomes could be observed between the wall and plasmalemma. The results indicated that the organelles, such as Golgi bodies together with small vesicles, rough endoplasmic reticulum and lomasomes, played the key role in the thickening and lignification of the secondary wall of bamboo fiber, though cortical microtubules were correlative with the process as well.
