A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λ phage. The genetic elements used i...A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λ phage. The genetic elements used include a regulatory protein gene （merR） along with operator/promoter （O/P） derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg（Ⅱ） ions in the concentration range of 100–1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different （P 0.05） for each concentration of inducing Hg（Ⅱ） ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg（Ⅱ） in water samples.展开更多
Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or acceler...Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey males and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population [Current Zoology 56 （1）： 57-64 2010].展开更多
As one of the top four commercially important species in China,yellow croaker(Larimichthys polyactis)with two geographic subpopulations,has undergone profound changes during the last several decades.It is widely compr...As one of the top four commercially important species in China,yellow croaker(Larimichthys polyactis)with two geographic subpopulations,has undergone profound changes during the last several decades.It is widely comprehended that understanding its population dynamics is critically important for sustainable management of this valuable fishery in China.The only two existing population dynamics models assessed the population of yellow croaker using short time-series data,without considering geographical variations.In this study,Bayesian models with and without hierarchical subpopulation structure were developed to explore the spatial heterogeneity of the population dynamics of yellow croaker from 1968 to 2015.Alternative hypotheses were constructed to test potential temporal patterns in yellow croaker’s population dynamics.Substantial variations in population dynamics characteristics among space and time were found through this study.The population growth rate was revealed to increase since the late 1980s,and the catchability increased more than twice from 1981 to 2015.The East China Sea’s subpopulation witnesses faster growth,but suffers from higher fishing pressure than that in the Bohai Sea and Yellow Sea.The global population and two subpopulations all have high risks of overfishing and being overfished according to the MSY-based reference points in recent years.More conservative management strategies with subpopulation considerations are imperative for the fishery management of yellow croaker in China.The methodology developed in this study could also be applied to the stock assessment and fishery management of other species,especially for those species with large spatial heterogeneity data.展开更多
Cancer is the cell fleeing from death by blocking the pathways of the intrinsic and the extrinsic program of cell death (Apoptosis). The success depends on making the programs of cell death run again.
DEAR EDITOR,Anadromous Coilia nasus is a socioeconomically important species from the middle and lower reaches of the Yangtze River,China.Here,we compared growth and feeding of C.nasus larvae in four reaches along the...DEAR EDITOR,Anadromous Coilia nasus is a socioeconomically important species from the middle and lower reaches of the Yangtze River,China.Here,we compared growth and feeding of C.nasus larvae in four reaches along the full migration corridor of the river(640 km)to determine how fitness varies between progenies of short-and long-distance migrants.Results demonstrated that larvae collected in downstream sections grew faster,exhibited higher feeding intensities.展开更多
A mass-balanced Ecopath model presents a quantitative description of the trophic structure,fl ow of energy and trophic interaction among ecological groups of an ecosystem.The Ecopath with Ecosim(EwE)modeling program(V...A mass-balanced Ecopath model presents a quantitative description of the trophic structure,fl ow of energy and trophic interaction among ecological groups of an ecosystem.The Ecopath with Ecosim(EwE)modeling program(Version 6.5)was used to develop a preliminary trophic model for a tropical freshwater reservoir.The total fi sh biomass was 6.245 t/km 2 and the highest trophic level of the reservoir was 3.362(for snakehead).The ecosystem is phytoplankton based because primary producers originated 68%and detritus originated 32%of the total fl ow from lower trophic level.The gross effi ciency of the fi shery was 0.004,suggesting the ineffi ciency of the system.The positive eff ect of phytoplankton and detritus on most of the other groups were evident from mixed trophic analysis while moderately higher ecotrophic effi ciency(EE)of phytoplankton shows the ecosystem’s potential bottom-up control.The competition for the same resources among diff erent groups was also obvious.The ratio of primary production/respiration(1.969)suggests that the ecosystem is at the developing stage and utmost contemplation should be given to concerned human activities.The low value of relative ascendancy(30.13)and overhead(69.87)reveals the stability of the ecosystem and some degrees of maturity.It also predicts the presence of signifi cant strength in reserve of the system to withstand or overcome any perturbation.However,ecologically sustainable resource management plans should be implemented to ensure the sustainability of this reservoir resources.展开更多
Objective:To examine sex reversal both by oral and by immersion using 17α-methyltestosterone on the methyltestosterone residual concentration and the organ histopathology of tilapia fish.Methods:This study used oral ...Objective:To examine sex reversal both by oral and by immersion using 17α-methyltestosterone on the methyltestosterone residual concentration and the organ histopathology of tilapia fish.Methods:This study used oral and immersion treatment methods for sex reversal of tilapia fish and used normal fish as the control and each treatment was repeated 4 times.17α-methyltestosterone at dosages of 60 mg/kg feed and 0.5 mg/L were used for oral and immersion methods,respectively.In the first step,tilapia fry were reared at 100 L aquaria,with a density of 1 fish/L for 2 months.In the next step,male tilapias were reared at happa(net cage)of(2×1×1)m3 size in the controlled pond,with a density of 30 fish/happa for 3 months.The methyltestosterone residual concentrations were analyzed by one-way analysis of variance and Duncan's multiple range tests,while organ histopathology was analyzed by descriptive method.Results:Residual concentrations in the serum of methyltestosterone-treated fish were significantly lower than that in normal fish,especially in 4-and 5-month-old tilapias with averages of less than 5μg/L,while in normal fish was more than 5μg/L.In the flesh,methyltestosterone residual concentrations showed relatively no significant differences between the oral and immersion treatment groups and methyltestosterone-treated fish remained lower compared to normal fish,except in 5-month-old tilapia.Methyltestosterone-treated tilapia exhibited histopathological changes on gill,liver,kidneys,and intestine organs.Conclusions:Sex reversal either by oral or by immersion has methyltestosterone residual concentration,but does not exceed the limits(5μg/L or 5μg/kg)of synthetic steroid on the fish body,although methyltestosterone causes histopathological changes on gill,liver,kidneys,and intestine.展开更多
Therapeutic strategies for destroying cancer cells by making its death programs run again. The normal cell passes through several stages (Accumulation stage, Detoxification stage, Formation of free radical stage and A...Therapeutic strategies for destroying cancer cells by making its death programs run again. The normal cell passes through several stages (Accumulation stage, Detoxification stage, Formation of free radical stage and Activation of nuclear factor kappa B stage and the shutting down of programs of cell death stage) to become a cancerous cell. The success of the therapeutic strategy to treat cancer depends on making either one or both programs of cell death run again. Shutting down one stage completely will be sufficient to stop the transformation of the natural cell into a cancerous cell, which eliminates the production of hydrogen peroxide, thus the activity of the NF-Kb will be inhibited. However, shutting down all stages is the most comprehensive therapeutic strategy and guarantees treatment success.展开更多
Cancer is cell fleeing from death by blocking the intrinsic and extrinsic programs of cell death. The six elements that shut down those programs are: muc-1, muc-4, muc-16, Bcl-2, MMPs and decoy R3. The nuclear factor-...Cancer is cell fleeing from death by blocking the intrinsic and extrinsic programs of cell death. The six elements that shut down those programs are: muc-1, muc-4, muc-16, Bcl-2, MMPs and decoy R3. The nuclear factor-kappa B (NF-Kb) stimulates the expression of genes responsible for the production of those elements, which are used by cells to block those two programs. In other words, the nuclear factor kappa B (NF-KB) is responsible for blocking both programs. Therefore, the nuclear factor kappa B (NF-Kb) is the true cause of cancer.展开更多
In eastern North America, white-tailed deer(Odocoileus virginianus) can have profound influences on forest biodiversity and forest successional processes.Moderate to high deer populations in the central Appalachians h...In eastern North America, white-tailed deer(Odocoileus virginianus) can have profound influences on forest biodiversity and forest successional processes.Moderate to high deer populations in the central Appalachians have resulted in lower forest biodiversity.Legacy effects in some areas persist even following deer population reductions or declines. This has prompted managers to consider deer population management goals in light of policies designed to support conservation of biodiversity and forest regeneration while continuing to support ample recreational hunting opportunities. However,despite known relationships between herbivory intensity and biodiversity impact, little information exists on the predictability of herbivory intensity across the varied and spatially diverse habitat conditions of the central Appalachians. We examined the predictability of browsing rates across central Appalachian landscapes at four environmental scales: vegetative community characteristics, physical environment, habitat configuration, and local human and deer population demographics. In an information-theoretic approach, we found that a model fitting the number of stems browsed relative to local vegetation characteristics received most(62%) of the overall support of all tested models assessing herbivory impact. Our data suggest that deer herbivory responded most predictably to differences in vegetation quantity and type. No other spatial factors or demographic factors consistently affected browsing intensity. Because herbivory, vegetation communities, and productivity vary spatially, we suggest that effective broad-scale herbivory impact assessment should include spatially-balanced vegetation monitoring that accounts for regional differences in deer forage preference.Effective monitoring is necessary to avoid biodiversity impacts and deleterious changes in vegetation community composition that are difficult to reverse and/or may not be detected using traditional deer-density based management goals.展开更多
Enhanced vegetation index(EVI)data can be used to identify and define the space in which ungulates practice parturition and encounter predation.This study explores the use of EVI data to identify landscapes linked to ...Enhanced vegetation index(EVI)data can be used to identify and define the space in which ungulates practice parturition and encounter predation.This study explores the use of EVI data to identify landscapes linked to ungulate parturition and predation events across space,time,and environmental conditions.As a case study,we used the moose population(Alces alces)of northern Minnesota in the USA.Using remotely sensed EVI data rasters and global positioning system collar data,we quantified how vegetation phenology and moose movement shaped the births and predation of 52 moose calves from 2013 to 2020 on or adjacent to the Grand Portage Indian Reservation.The known sources of predation were American black bears(Ursus americanus,n=22)and gray wolves(Canis lupus,n=28).Satellite-derived data summarizing seasonal landscape features at the local level revealed that landscape heterogeneity use by moose can help to quantitatively identify landscapes of parturition and predation in space and time across large areas.Vegetation phenology proved to be differentiable between adult moose ranges,sites of cow parturition,and sites of calf predation.Landscape characteristics of each moose group were consistent and tractable based on environment,suggesting that sites of parturition and predation of moose are predictable in space and time.It is possible that moose selected specific landscapes for parturition despite risk of increased predation of their calves,which could be an example of an"ecological trap."This analytical framework can be employed to identify areas for future ungulate research on the impacts of landscape on parturition and predation dynamics.展开更多
Given the likelihood of regional extirpation of several once-common bat species in eastern North America from white-nose syndrome,it is critical that the impacts of forest management activities,such as prescribed fire...Given the likelihood of regional extirpation of several once-common bat species in eastern North America from white-nose syndrome,it is critical that the impacts of forest management activities,such as prescribed fire,are known in order to minimize potentially additive negative effects on bat populations.Historic wildfires may offer a suitable surrogate to assess long-term burn impacts on bats for planning,implementing and assessing burn programs.To examine the effects of historic fire on bats,we sampled bat activities at 24 transect locations in burned and unburned forest stands in the central Appalachian Mountains of Shenandoah National Park(SNP),Virginia,USA.There was limited evidence of positive fire effects over time on hoary bats(Lasiurus cinereus Beauvois)and big brown bats(Eptesicus fuscus Beauvois)occupancy.Overall,there were few or mostly equivocal relationships of bat occupancy relative to burn conditions or time since fire in SNP across species using a false-positive occupancy approach.Our results suggest that fire does not strongly affect bat site occupancy short-or long-term in the central Appalachians.展开更多
The present study examined the influence of leucine metabolite β-hydroxy-β-methylbutyrate （HMB） on the nonspecific cellular and humoral defence mechanisms and protection against Yersinia ruckeri and Aeromonas salm...The present study examined the influence of leucine metabolite β-hydroxy-β-methylbutyrate （HMB） on the nonspecific cellular and humoral defence mechanisms and protection against Yersinia ruckeri and Aeromonas salmonicida in juvenile pikeperch （Sander lucioperca）. The fish was fed with a commercial trout pellets, containing either 0 （control group） or 50 mg HMB kg^-1 body weight day^-1 （HMB fed group）. After four weeks feeding, 20 pikeperch from each group were anaesthetised and blood and pronephros samples were taken. The levels of the following immunological parameters were measured： respiratory burst activity of phagocytes, potential killing activity of phagocytes, lymphocytes proliferation stimulated by concanavaline A or lipopolisaccharide, lysozyme activity in serum, ceruloplasmin activity in serum, total protein in serum and total immunoglobulin （Ig） level in serum. A disease challenge test using Yersinia ruckeri or Aeromonas salmonicida was conducted after 4 weeks of feeding. The levels of all immunological parameters excluding ceruloplasmin activity and total protein in serum were statistically significantly higher （P 〈 0.05） in the HMB treated group compared to the control group. Feeding with HMB has led to a significant decrease in the mortality after the challenge trial with Y. ruckeri （30% lower mortality than in the control group） and with theA. salmonicida （40% lower mortality than in the control group）. The current study strongly suggests that feeding pikeperch with HMB in dose 50 mg kg^-1 body weight day^-1 may improve the innate immunity and decrease the mortality rates after experimental infection with pathogenic bacteria Y. ruckeri and A. salmonicida.展开更多
The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch ...The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch forecast,and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort(CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method,the method developed here does not need the assumption of constant Z throughout the time,but the Z values in n continuous years are assumed constant,and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z,and the estimated rates of change from this approach are close to the true change rates(the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore,the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them,but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod(G adus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997,and obtained reasonable estimates of time-based Z.展开更多
The night sky is the venue of an ancient acoustic battle between echolocating bats and their insect prey. Many tiger moths （Lepidoptera： Arctiidae） answer the attack calls of bats with a barrage of high frequency c...The night sky is the venue of an ancient acoustic battle between echolocating bats and their insect prey. Many tiger moths （Lepidoptera： Arctiidae） answer the attack calls of bats with a barrage of high frequency clicks. Some moth species use these clicks for acoustic aposematism and mimicry, and others for sonar jamming, however, most of the work on these defensive functions has been done on individual moth species. We here analyze the diversity of structure in tiger moth sounds liom 26 spe- cies collected at three locations in North and South America. A principal components analysis of the anti-bat tiger moth sounds reveals that they vary markedly along three axes： （1） frequency, （2） duty cycle （sound production per unit time） and frequency modulation, and （3） modulation cycle （clicks produced during flexion and relaxation of the sound producing tymbal） structure. Tiger moth species appear to cluster into two distinct groups： one with low duty cycle and few clicks per modulation cycle that supports an acoustic aposematism function, and a second with high duty cycle and many clicks per modulation cycle that is con- sistent with a sonar jamming function. This is the first evidence from a community-level analysis to support multiple functions for tiger moth sounds. We also provide evidence supporting an evolutionary history for the development of these strategies. Further- more, cross-correlation and spectrogram correlation measurements failed to support a ＂phantom echo＂ mechanism underlying sonar jamming, and instead point towards echo interference [Current Zoology 56 （3）： 358-369, 2010].展开更多
Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a ...Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.展开更多
In this study,we investigated the transcriptional spatio-temporal dynamics of the taste 1 receptor(T1R)gene family repertoire in seabream(Sparus aurata[sa]),during larval ontogeny and in adult tissues.In early larval ...In this study,we investigated the transcriptional spatio-temporal dynamics of the taste 1 receptor(T1R)gene family repertoire in seabream(Sparus aurata[sa]),during larval ontogeny and in adult tissues.In early larval development,sa T1R expression arises heterochronously,i.e.the extraoral taste-related perception in the gastrointestinal tract(GIT)anticipates first exogenous feeding(at 9 days post hatching[dph]),followed by the buccal/intraoral perception from 14 dph onwards,supporting the hypothesis that the early onset of the molecular machinery underlying sa T1R expression in the GIT is not induced by food but rather genetically hardwired.During adulthood,we characterized the expression patterns of sa T1R within specific tissues(n=4)distributed in oropharingeal,GIT and brain regions substantiating their functional versatility as chemosensory signaling players to a variety of biological functions beyond oral taste sensation.Further,we provided for the first time direct evidences in fish for m RNA coexpression of a subset of sa T1R genes(mostly sa T1R3,i.e.the common subunit of the heterodimeric T1R complexes for the detection of“sweet”and“umami”substances),with the selected gut peptides ghrelin(ghr),cholecystokinin(cck),hormone peptide yy(pyy)and proglucagon(pg).Each peptide defines the enteroendocrine cells(ECCs)identity,and establishes on morphological basis,a direct link for T1R chemosensing in the regulation of fish digestive processes.Finally,we analyzed the spatial gene expression patterns of 2 taste signaling components functionally homologous to the mammalian G(i)a subunit gustducin,namely sa G(i)a1 and sa G(i)a2,and demonstrated their co-localization with the sa T1R3in EECs,thus validating their direct involvement in taste-like transduction mechanisms of the fish GIT.In conclusion,data provide new insights in the evolutionary conservation of gut sensing in fish suggesting a conserved role for nutrient sensors modulating entero-endocrine secretion.展开更多
基金Director, Central Institute of Fisheries Education, Mumbaifor providing facility and financial assistance in the form of Masters’ Fellowship during the research period
文摘A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λ phage. The genetic elements used include a regulatory protein gene （merR） along with operator/promoter （O/P） derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg（Ⅱ） ions in the concentration range of 100–1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different （P 0.05） for each concentration of inducing Hg（Ⅱ） ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg（Ⅱ） in water samples.
基金supported by the Netherlands Science Fotmdation (NWO-ALW 810.64.011)research grants from Leiden University Fundthe Schure-Beijerinck-Popping Foundation
文摘Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey males and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population [Current Zoology 56 （1）： 57-64 2010].
基金Foundation item:The National Key R&D Program of China under contract No.2017YFE0104400the National Natural Science Foundation of China under contract No.31772852the Fundamental Research Funds for the Central Universities under contract Nos 201512002 and 201562030.
文摘As one of the top four commercially important species in China,yellow croaker(Larimichthys polyactis)with two geographic subpopulations,has undergone profound changes during the last several decades.It is widely comprehended that understanding its population dynamics is critically important for sustainable management of this valuable fishery in China.The only two existing population dynamics models assessed the population of yellow croaker using short time-series data,without considering geographical variations.In this study,Bayesian models with and without hierarchical subpopulation structure were developed to explore the spatial heterogeneity of the population dynamics of yellow croaker from 1968 to 2015.Alternative hypotheses were constructed to test potential temporal patterns in yellow croaker’s population dynamics.Substantial variations in population dynamics characteristics among space and time were found through this study.The population growth rate was revealed to increase since the late 1980s,and the catchability increased more than twice from 1981 to 2015.The East China Sea’s subpopulation witnesses faster growth,but suffers from higher fishing pressure than that in the Bohai Sea and Yellow Sea.The global population and two subpopulations all have high risks of overfishing and being overfished according to the MSY-based reference points in recent years.More conservative management strategies with subpopulation considerations are imperative for the fishery management of yellow croaker in China.The methodology developed in this study could also be applied to the stock assessment and fishery management of other species,especially for those species with large spatial heterogeneity data.
文摘Cancer is the cell fleeing from death by blocking the pathways of the intrinsic and the extrinsic program of cell death (Apoptosis). The success depends on making the programs of cell death run again.
基金supported by the National Natural Science Foundation of China(32002394,31570420)supported by the Peter B.Moyle&California Trout Endowment for Coldwater Fish Conservationthe California Agricultural Experimental Station of the University of California Davis(CA-D-WFB-2467-H)。
文摘DEAR EDITOR,Anadromous Coilia nasus is a socioeconomically important species from the middle and lower reaches of the Yangtze River,China.Here,we compared growth and feeding of C.nasus larvae in four reaches along the full migration corridor of the river(640 km)to determine how fitness varies between progenies of short-and long-distance migrants.Results demonstrated that larvae collected in downstream sections grew faster,exhibited higher feeding intensities.
文摘A mass-balanced Ecopath model presents a quantitative description of the trophic structure,fl ow of energy and trophic interaction among ecological groups of an ecosystem.The Ecopath with Ecosim(EwE)modeling program(Version 6.5)was used to develop a preliminary trophic model for a tropical freshwater reservoir.The total fi sh biomass was 6.245 t/km 2 and the highest trophic level of the reservoir was 3.362(for snakehead).The ecosystem is phytoplankton based because primary producers originated 68%and detritus originated 32%of the total fl ow from lower trophic level.The gross effi ciency of the fi shery was 0.004,suggesting the ineffi ciency of the system.The positive eff ect of phytoplankton and detritus on most of the other groups were evident from mixed trophic analysis while moderately higher ecotrophic effi ciency(EE)of phytoplankton shows the ecosystem’s potential bottom-up control.The competition for the same resources among diff erent groups was also obvious.The ratio of primary production/respiration(1.969)suggests that the ecosystem is at the developing stage and utmost contemplation should be given to concerned human activities.The low value of relative ascendancy(30.13)and overhead(69.87)reveals the stability of the ecosystem and some degrees of maturity.It also predicts the presence of signifi cant strength in reserve of the system to withstand or overcome any perturbation.However,ecologically sustainable resource management plans should be implemented to ensure the sustainability of this reservoir resources.
文摘Objective:To examine sex reversal both by oral and by immersion using 17α-methyltestosterone on the methyltestosterone residual concentration and the organ histopathology of tilapia fish.Methods:This study used oral and immersion treatment methods for sex reversal of tilapia fish and used normal fish as the control and each treatment was repeated 4 times.17α-methyltestosterone at dosages of 60 mg/kg feed and 0.5 mg/L were used for oral and immersion methods,respectively.In the first step,tilapia fry were reared at 100 L aquaria,with a density of 1 fish/L for 2 months.In the next step,male tilapias were reared at happa(net cage)of(2×1×1)m3 size in the controlled pond,with a density of 30 fish/happa for 3 months.The methyltestosterone residual concentrations were analyzed by one-way analysis of variance and Duncan's multiple range tests,while organ histopathology was analyzed by descriptive method.Results:Residual concentrations in the serum of methyltestosterone-treated fish were significantly lower than that in normal fish,especially in 4-and 5-month-old tilapias with averages of less than 5μg/L,while in normal fish was more than 5μg/L.In the flesh,methyltestosterone residual concentrations showed relatively no significant differences between the oral and immersion treatment groups and methyltestosterone-treated fish remained lower compared to normal fish,except in 5-month-old tilapia.Methyltestosterone-treated tilapia exhibited histopathological changes on gill,liver,kidneys,and intestine organs.Conclusions:Sex reversal either by oral or by immersion has methyltestosterone residual concentration,but does not exceed the limits(5μg/L or 5μg/kg)of synthetic steroid on the fish body,although methyltestosterone causes histopathological changes on gill,liver,kidneys,and intestine.
文摘Therapeutic strategies for destroying cancer cells by making its death programs run again. The normal cell passes through several stages (Accumulation stage, Detoxification stage, Formation of free radical stage and Activation of nuclear factor kappa B stage and the shutting down of programs of cell death stage) to become a cancerous cell. The success of the therapeutic strategy to treat cancer depends on making either one or both programs of cell death run again. Shutting down one stage completely will be sufficient to stop the transformation of the natural cell into a cancerous cell, which eliminates the production of hydrogen peroxide, thus the activity of the NF-Kb will be inhibited. However, shutting down all stages is the most comprehensive therapeutic strategy and guarantees treatment success.
文摘Cancer is cell fleeing from death by blocking the intrinsic and extrinsic programs of cell death. The six elements that shut down those programs are: muc-1, muc-4, muc-16, Bcl-2, MMPs and decoy R3. The nuclear factor-kappa B (NF-Kb) stimulates the expression of genes responsible for the production of those elements, which are used by cells to block those two programs. In other words, the nuclear factor kappa B (NF-KB) is responsible for blocking both programs. Therefore, the nuclear factor kappa B (NF-Kb) is the true cause of cancer.
基金financially supported by the Wildlife and Sport Fish Restoration Program,Project WE99,Contract 2012-13694 to Virginia Tech
文摘In eastern North America, white-tailed deer(Odocoileus virginianus) can have profound influences on forest biodiversity and forest successional processes.Moderate to high deer populations in the central Appalachians have resulted in lower forest biodiversity.Legacy effects in some areas persist even following deer population reductions or declines. This has prompted managers to consider deer population management goals in light of policies designed to support conservation of biodiversity and forest regeneration while continuing to support ample recreational hunting opportunities. However,despite known relationships between herbivory intensity and biodiversity impact, little information exists on the predictability of herbivory intensity across the varied and spatially diverse habitat conditions of the central Appalachians. We examined the predictability of browsing rates across central Appalachian landscapes at four environmental scales: vegetative community characteristics, physical environment, habitat configuration, and local human and deer population demographics. In an information-theoretic approach, we found that a model fitting the number of stems browsed relative to local vegetation characteristics received most(62%) of the overall support of all tested models assessing herbivory impact. Our data suggest that deer herbivory responded most predictably to differences in vegetation quantity and type. No other spatial factors or demographic factors consistently affected browsing intensity. Because herbivory, vegetation communities, and productivity vary spatially, we suggest that effective broad-scale herbivory impact assessment should include spatially-balanced vegetation monitoring that accounts for regional differences in deer forage preference.Effective monitoring is necessary to avoid biodiversity impacts and deleterious changes in vegetation community composition that are difficult to reverse and/or may not be detected using traditional deer-density based management goals.
基金This project was funded by the U.S.Fish and Wildlife Service Tribal Wildlife Grant,U.S.Environmental Protection Agency Great Lakes Restoration InitiativeBureau of Indian Affairs Endangered Species Program+1 种基金Funding was also provided by the Minnesota Zoo Ulysses S.Seal Conservation GrantIndianapolis Zoo Conservation Fund.
文摘Enhanced vegetation index(EVI)data can be used to identify and define the space in which ungulates practice parturition and encounter predation.This study explores the use of EVI data to identify landscapes linked to ungulate parturition and predation events across space,time,and environmental conditions.As a case study,we used the moose population(Alces alces)of northern Minnesota in the USA.Using remotely sensed EVI data rasters and global positioning system collar data,we quantified how vegetation phenology and moose movement shaped the births and predation of 52 moose calves from 2013 to 2020 on or adjacent to the Grand Portage Indian Reservation.The known sources of predation were American black bears(Ursus americanus,n=22)and gray wolves(Canis lupus,n=28).Satellite-derived data summarizing seasonal landscape features at the local level revealed that landscape heterogeneity use by moose can help to quantitatively identify landscapes of parturition and predation in space and time across large areas.Vegetation phenology proved to be differentiable between adult moose ranges,sites of cow parturition,and sites of calf predation.Landscape characteristics of each moose group were consistent and tractable based on environment,suggesting that sites of parturition and predation of moose are predictable in space and time.It is possible that moose selected specific landscapes for parturition despite risk of increased predation of their calves,which could be an example of an"ecological trap."This analytical framework can be employed to identify areas for future ungulate research on the impacts of landscape on parturition and predation dynamics.
基金This work was supported by the Joint Fire Science Program(Grant#G14AC00316)National Park Service Whitenose Syndrome Program(Grant#P14AC01042)through the Southern Appalachian Cooperative Ecosystem Studies Unit at Virginia Tech.
文摘Given the likelihood of regional extirpation of several once-common bat species in eastern North America from white-nose syndrome,it is critical that the impacts of forest management activities,such as prescribed fire,are known in order to minimize potentially additive negative effects on bat populations.Historic wildfires may offer a suitable surrogate to assess long-term burn impacts on bats for planning,implementing and assessing burn programs.To examine the effects of historic fire on bats,we sampled bat activities at 24 transect locations in burned and unburned forest stands in the central Appalachian Mountains of Shenandoah National Park(SNP),Virginia,USA.There was limited evidence of positive fire effects over time on hoary bats(Lasiurus cinereus Beauvois)and big brown bats(Eptesicus fuscus Beauvois)occupancy.Overall,there were few or mostly equivocal relationships of bat occupancy relative to burn conditions or time since fire in SNP across species using a false-positive occupancy approach.Our results suggest that fire does not strongly affect bat site occupancy short-or long-term in the central Appalachians.
文摘The present study examined the influence of leucine metabolite β-hydroxy-β-methylbutyrate （HMB） on the nonspecific cellular and humoral defence mechanisms and protection against Yersinia ruckeri and Aeromonas salmonicida in juvenile pikeperch （Sander lucioperca）. The fish was fed with a commercial trout pellets, containing either 0 （control group） or 50 mg HMB kg^-1 body weight day^-1 （HMB fed group）. After four weeks feeding, 20 pikeperch from each group were anaesthetised and blood and pronephros samples were taken. The levels of the following immunological parameters were measured： respiratory burst activity of phagocytes, potential killing activity of phagocytes, lymphocytes proliferation stimulated by concanavaline A or lipopolisaccharide, lysozyme activity in serum, ceruloplasmin activity in serum, total protein in serum and total immunoglobulin （Ig） level in serum. A disease challenge test using Yersinia ruckeri or Aeromonas salmonicida was conducted after 4 weeks of feeding. The levels of all immunological parameters excluding ceruloplasmin activity and total protein in serum were statistically significantly higher （P 〈 0.05） in the HMB treated group compared to the control group. Feeding with HMB has led to a significant decrease in the mortality after the challenge trial with Y. ruckeri （30% lower mortality than in the control group） and with theA. salmonicida （40% lower mortality than in the control group）. The current study strongly suggests that feeding pikeperch with HMB in dose 50 mg kg^-1 body weight day^-1 may improve the innate immunity and decrease the mortality rates after experimental infection with pathogenic bacteria Y. ruckeri and A. salmonicida.
基金Supported by the USDA Cooperative State Research,Education and Extension Service,Hatch Project(No.0210510)the National Natural Science Foundations of China(Nos.31270527,40801225)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY13D010005)the Young Academic Leaders Climbing Program of Zhejiang Province(No.pd2013222)
文摘The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch forecast,and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort(CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method,the method developed here does not need the assumption of constant Z throughout the time,but the Z values in n continuous years are assumed constant,and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z,and the estimated rates of change from this approach are close to the true change rates(the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore,the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them,but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod(G adus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997,and obtained reasonable estimates of time-based Z.
基金support from the Richter Foundation(JRB)a Wake Forest University Dean's Fellowship (AJC)from the National Science Foundation #IBN-0135825 (WEC)
文摘The night sky is the venue of an ancient acoustic battle between echolocating bats and their insect prey. Many tiger moths （Lepidoptera： Arctiidae） answer the attack calls of bats with a barrage of high frequency clicks. Some moth species use these clicks for acoustic aposematism and mimicry, and others for sonar jamming, however, most of the work on these defensive functions has been done on individual moth species. We here analyze the diversity of structure in tiger moth sounds liom 26 spe- cies collected at three locations in North and South America. A principal components analysis of the anti-bat tiger moth sounds reveals that they vary markedly along three axes： （1） frequency, （2） duty cycle （sound production per unit time） and frequency modulation, and （3） modulation cycle （clicks produced during flexion and relaxation of the sound producing tymbal） structure. Tiger moth species appear to cluster into two distinct groups： one with low duty cycle and few clicks per modulation cycle that supports an acoustic aposematism function, and a second with high duty cycle and many clicks per modulation cycle that is con- sistent with a sonar jamming function. This is the first evidence from a community-level analysis to support multiple functions for tiger moth sounds. We also provide evidence supporting an evolutionary history for the development of these strategies. Further- more, cross-correlation and spectrogram correlation measurements failed to support a ＂phantom echo＂ mechanism underlying sonar jamming, and instead point towards echo interference [Current Zoology 56 （3）： 358-369, 2010].
文摘Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.
基金covered by the National Research Agency(AEI,Spain)(grant number:PID2019-103969RB-C33)to Jos e M.Cerd a-Reverter。
文摘In this study,we investigated the transcriptional spatio-temporal dynamics of the taste 1 receptor(T1R)gene family repertoire in seabream(Sparus aurata[sa]),during larval ontogeny and in adult tissues.In early larval development,sa T1R expression arises heterochronously,i.e.the extraoral taste-related perception in the gastrointestinal tract(GIT)anticipates first exogenous feeding(at 9 days post hatching[dph]),followed by the buccal/intraoral perception from 14 dph onwards,supporting the hypothesis that the early onset of the molecular machinery underlying sa T1R expression in the GIT is not induced by food but rather genetically hardwired.During adulthood,we characterized the expression patterns of sa T1R within specific tissues(n=4)distributed in oropharingeal,GIT and brain regions substantiating their functional versatility as chemosensory signaling players to a variety of biological functions beyond oral taste sensation.Further,we provided for the first time direct evidences in fish for m RNA coexpression of a subset of sa T1R genes(mostly sa T1R3,i.e.the common subunit of the heterodimeric T1R complexes for the detection of“sweet”and“umami”substances),with the selected gut peptides ghrelin(ghr),cholecystokinin(cck),hormone peptide yy(pyy)and proglucagon(pg).Each peptide defines the enteroendocrine cells(ECCs)identity,and establishes on morphological basis,a direct link for T1R chemosensing in the regulation of fish digestive processes.Finally,we analyzed the spatial gene expression patterns of 2 taste signaling components functionally homologous to the mammalian G(i)a subunit gustducin,namely sa G(i)a1 and sa G(i)a2,and demonstrated their co-localization with the sa T1R3in EECs,thus validating their direct involvement in taste-like transduction mechanisms of the fish GIT.In conclusion,data provide new insights in the evolutionary conservation of gut sensing in fish suggesting a conserved role for nutrient sensors modulating entero-endocrine secretion.
