An experiment was conducted to evaluate the effects of feeding various sources of dietary lipid on weight gain, feed conversion, survival and fatty acid composition of juvenile red swamp crawfish, Procam-barus clarkii...An experiment was conducted to evaluate the effects of feeding various sources of dietary lipid on weight gain, feed conversion, survival and fatty acid composition of juvenile red swamp crawfish, Procam-barus clarkii. Six semi-purified diets containing vitamin-free casein, defatted soybean meal, 0. 5% choline chloride, 0. 5% glycine and 0. 5% cholesterol were supplemented with 6. 0% of either anchovy oil, linseed oil, soybean oil, rapeseed oil, safflower oil or pork lard. Each diet was fed to crawfish (3. 07±0. 21 g average weight) in three replicate aquaria for 60 days. Survival rate, weight gain and feed conversion were best for crawfish fed the diet containing anchovy oil. Crawfish fed the linseed oil diet had the second highest weight gain, followed by crawfish on soybean oil, repaseed oil, safflower oil and pork lard diets, respectively. Feed conversion values were a reflection of weight gain. Results showed that both n-6 and n-3 fatty acids are dietary essential for juvenile Procambarus clarkii, although n-3 fatty acids promoted faster growth than n-6. However, highly unsaturated fatty acids (HUFA) (20 : 5n-3 and 22 :6n-3) had better growth-promoting effect than 18 : 3n-3, due probably to the limited ability of crawfish to bioconvert fatty acids to polyenoic forms of longer chain length. The fatty acid composition of the crawfish generally reflected that of the dietary lipids, especially for the diets containing unsaturated fatty acids.展开更多
The full-length cDNA sequence of prophenoloxidase was obtained through RACE technology. The complete cDNA sequence is 3 721-bp long, containing an open reading frame （ORF） of 1 881 bp, a 154-bp 5′-untranslated regi...The full-length cDNA sequence of prophenoloxidase was obtained through RACE technology. The complete cDNA sequence is 3 721-bp long, containing an open reading frame （ORF） of 1 881 bp, a 154-bp 5′-untranslated region, and a 1 686- bp 3′-untranslated region with three potential functional poly（A） signals （AATAAA）. The molecular mass of the deduced amino acid sequence （627 aa） was 72.3 kDa with an estimatedpI of 5.88. It contained putative copper-binding sites （copper A： 131, 135, 167 and copper B： 301,305, 341）, and a tentative complement-like motif （GCGWPDHL）. Eight potential N-linked glycosylation sites were predicted to be present in P. clarkii prophenoloxidase. Similar to those in other arthropod prophenoloxidases reported so far, no signal peptide was detected in the crayfish prophenoloxidase. The phylogenetic trees confirmed that P. clarkii prophenoloxidase was most closely related to that of freshwater crayfish P. leniusculus and more closely related to other crustacean prophenoloxidases from shrimp, prawn, and lobster than to the insect prophenoloxidases. Besides, two putative introns were found in this sequence of genomic DNA.展开更多
The effect of starvation on physiological and biochemical indicators of body, muscle and hepatopancreas were investigated for juvenile red swamp crawfish （Procambarus clarkii）, and the results showed the effect was ...The effect of starvation on physiological and biochemical indicators of body, muscle and hepatopancreas were investigated for juvenile red swamp crawfish （Procambarus clarkii）, and the results showed the effect was obvious. In a 70-day starvation experiment, mean body weight, exuvial rate, abdominal muscle ratio and hepatosomatic index decreased significantly. The percentage of protein, fat, ash and moisture were also significantly affected. The protein content decreased sharply at Day 30 onward and the percentage of fat decreased rapidly from Day 50 and on. The percentages of ash and moisture started to increase significantly at Day 40 and 30 respectively. After the starvation experiment, the hepatopancreatic total and neutral lipid content decreased slightly from 23.90% to 20.39% and 73.75% to 70.35%, while the hepatopancreatic polar lipid content increased from 23.81% to 27.32%. On the other hand, all the muscular total, neutral and polar lipid contents, and the muscular fatty acid compositions did not change significantly except for the hepatopancreatic fatty acid composition. The relative percentages of 14：0, 16：0, 16：1n-7 and 18：1n-9 were decreased by 55.17%, 11.11%, 8.5% and 6.70% from the initial values, and the relative percentages of 18：2n-6, 18：3n-3, 20：4n-6, 20：5n-3 and 22：6n-3 increased obviously from 5.2%, 3.9%,4, 2.4%, 10.6%, and 13.7% to 7.1%, 5.0%, 2.8%, 11.5%, and 14.4% respectively. Preference of utilization of fatty acids from hepatopancreas during starvation was as follows： 14：0〉16：0〉16：1n-7〉18：1n-9, and the conservation of highly unsaturated fatty acids was in the order of： 18：2n-6 〉18：3n-3〉20：4n-6〉20：5n-3〉22：6n-3.展开更多
The morbidity and mortality peak of farmed Procambarus clarkii occurs around May every year,a phenomenon known as"Black May"disease(BMD).Increasing evidence shows that the intestinal flora is closely related...The morbidity and mortality peak of farmed Procambarus clarkii occurs around May every year,a phenomenon known as"Black May"disease(BMD).Increasing evidence shows that the intestinal flora is closely related to host health.We analyzed and compared the microbiota of healthy and BMDaffected P.clarkii intestines.The results show that there was no significant difference in bacterial a-diversity(richness P=0.59;evenness P=0.43;and diversity P=0.052)between the diseased group and the control group.Four dominant phyla in the intestines of crayfish in the control group,namely Tenericutes(30.86%),Bacteroidetes(29.99%),Firmicutes(22.23%),and Proteobacteria(15.23%),were identified.However,a striking shift in the microbial compo sition were found in the intestines of P.clarkii with BMD.Bacteroidetes was a dominant phylum in healthy P.clarkii,whereas the prevalence was low in diseased P.clarkii(1.87%).By contrast,the prevalence of Proteobacteria was significantly higher(P<0.05)in P.clarkii with BMD than in P.clarkii without BMD.Candidatus Bacilloplasma,Bacteroides,Vibrio,and Aeromonas showed significant differences(P<0.05)at the genus level.Tax4 Fun function prediction indicated that the relative abundance of genes involved in energy metabolism in the intestinal flora of P.clarkii with BMD was significantly reduced(P<0.05).Therefore,BMD can change the composition of the intestinal microbiota of P.clarkii.This study contributes to the understanding of the relationship between intestinal flora and host especially in aquatic animals.展开更多
[ Objective] To provide basic research parameters for the laboratory culture of Procambarus clarkii using Salix saposhnikovii and the breeding materials for the clean environment-friendly aquaculture. [Method] The de-...[ Objective] To provide basic research parameters for the laboratory culture of Procambarus clarkii using Salix saposhnikovii and the breeding materials for the clean environment-friendly aquaculture. [Method] The de-aerated water was used to culture the post larvae and P. clarkii juvenile. The effects of S. saposhnikovii roots on the survival rate, body length increase and body length variation coefficient of P. clarkii were in- vestigated. The survival rate of juvenile P. clarkii in the V class wastewater at 2 ammonia nitrogen concentrations were examined. [ Result] The post larvae of P. clarkii cultivated with S. saposhnikovii in the de-aerated water had significantly higher survival rate and longer body length than the control （ P 〈 0.05）, but there was no significant difference between the 2 treatments in the variation coefficient of body length. In the wastewater containing 2 mg/L ammonia nitrogen, the survival rate and ammonia nitrogen wastewater purification rate of the experimental juvenile P. clarkii were higher than the control. When the concentration of ammonia nitrogen increased to 10 mg/L, the survival rate of the experimental juvenile P. clarkii was still higher than the control, but there was no significant difference between the 2 groups in the purification rate of ammonia nitrogen. [ Conclu- sien] S. saposhnikovii has significant effect on the survival rate and growth of juvenile P. clarloTand can purify the wastewater containing 2 -10 mg/L ammonia nitrogen.展开更多
Procambarus clarkii is native to the south-central United States （Louisiana） and northeastern Mexico, and is a highly efficient predator that poses a damager to native species after its introduction or invasion. In ...Procambarus clarkii is native to the south-central United States （Louisiana） and northeastern Mexico, and is a highly efficient predator that poses a damager to native species after its introduction or invasion. In its natural habitat, P. clarkii consumes Carassius auratus, however, whether C. auratus recognizes P. clarkii as a predator is not yet clear. In laboratory experiments, we investigated whether experienced and inexperienced C. auratus recognize P. clarkii as a predatory threat and the specific sensory modality used by C. auratus to respond to chemical and visual stimuli from P. clarkii. In the chemical stimuli experiment, two kinds of chemical stimuli were used, water from a tub containing P. clarkii previously fed with C. auratus （C. auratus diet cues） and water from a tub containing unfed P. clarkii （P. clarkii cues）. In the visual experiment, experienced C. auratus decreased activity, but inexperienced C.auratus avoided the predator compartment. When C. auratus diet cues were presented, both experienced and inexperienced C. auratus increased the use of shelter, decreased activity in the initial response phase. Compared with the blank treatment, experienced C. auratus responded to P. clarkii cues by decreasing activity; however, inexperienced C. auratus showed no reduction in activity. C. auratus appears to recognize P. clarkii as a predator both through visual and chemical cues. Further analysis revealed that C. auratus may recognize R clarkii visually through the disturbances caused by P. clarkii movement and chemically by detecting conspecific alarm cues in the diet of P. clarkii. The results also indicate that ex- perienced C. auratus can recognize R clarkii by innate chemical cues from P. clarkii, whereas inexperienced C. auratus cannot [Current Zoology 57 （3）： 330-339, 2011].展开更多
The red swamp crayfish,Procambarus clarkii,is an economically important species especially in China.Their exoskeleton places serious constraints on growth and culture management.Their growth is achieved through interm...The red swamp crayfish,Procambarus clarkii,is an economically important species especially in China.Their exoskeleton places serious constraints on growth and culture management.Their growth is achieved through intermittent molting/ecdysis.The longitudinal genetic dynamics for growth-related traits at different ecdysial points in P.clarkii has been unclear to date.In this study,conditional genetic analysis was carried out for growth-related traits(body weight,body length,chela length,and cephalothorax length)based upon a mixed genetic model with conditional additive,dominance,and genotype by environment effects in P.clarkii.A complete diallel cross was made among three geographic populations of P.clarkii for the genetic mating design.Results of the conditional genetic analysis showed that from 4 th molt to 9 th molt the conditional additive variations were increased significantly whereas the conditional non-additive genetic variations(dominance and genotype by environment interaction)were decreased significantly for these growth-related traits.This indicated that lots of new expression of additive effect genes for body weight,body length,chela length,and cephalothorax length occurred during ontogeny,and environment played a signifi cant role in the expression of genes affecting these growth-related traits.Growth of the four traits was mainly affected by non-additive genetic effects in early developmental stage(prior to 4 th molt).The cumulative conditional additive variation for the growth-related traits from 4 th molt to 9 th molt accounted for a large majority of the total conditional additive variations from 2 nd molt to 9 th molt,indicating that this period was very important for the growth of this species.Using the conditional analysis method,dynamics of growth-related traits during an important ontogenetic phase of red swamp crayfish was uncovered.Our results provide valuable insights into refining production of this species.展开更多
Different concentrations of four metals namely copper, lead, chrome and cadmium were evaluated in crayfish Procambarus clarkii tissues (carapace, flesh) for a six-month period, from March to August 2013 in the Rharb o...Different concentrations of four metals namely copper, lead, chrome and cadmium were evaluated in crayfish Procambarus clarkii tissues (carapace, flesh) for a six-month period, from March to August 2013 in the Rharb of Morocco (Lagoon Merja Zerga and Nador canal). The determination of heavy metals was carried using atomic absorption spectroscopy Varian VV20. The results obtained revealed a metal’s contamination of Procambarus clarkii in both sites. Concentrations of heavy metals examined Procambarus clarkii carapace ranged as follows: Merja Zerga (Pb 2.07 - 6.7 μg/g;Cu 2.9 - 9.97 μg/g;Cr 0.89 - 14.22 μg/g dry weight) and Nador canal: (Pb 0.08 - 7.8 μg/g;Cu 3.40 - 9.3 μg/g;Cr 0.87 - 3.5 μg/g dry weight). Concentrations of heavy metals found in flesh were as follows: Merja Zerga (Pb 0.02 - 5.25 μg/g;Cu 9.58 - 23.59 μg/g;Cr 0 - 2.71 μg/g dry weight) and Nador canal (Pb 0.06 - 6.81 μg/g;Cu 9.5 - 37.20 μg/g;Cr 0 - 3.23 μg/g dry weight). The distribution of those metals in Procambarus clarkii shows high levels of contamination for lead, copper and chrome with an absence of cadmium in both sites (Merja Zerga and Nador canal). The concentrations differed in carapace and flesh.展开更多
The red swamp crayfish(Procambarus clarkii)is a species from the northeast of Mexico and the central south of the United States(Louisiana),actually is the dominant macroinvertebrate in several countries.It was introdu...The red swamp crayfish(Procambarus clarkii)is a species from the northeast of Mexico and the central south of the United States(Louisiana),actually is the dominant macroinvertebrate in several countries.It was introduced to several countries,generally for gastronomic reasons or to repopulate destroyed areas by a disease.While the first introduction of this species into the world is well-documented,little is known about its pathways of invasion and the reason for its rapid spread in several countries.P.clarkii is an aggressive crustacean that multiplies very fast and adapts to features of the invaded location.Adults of the species can disperse up to 1.6 km on land.Also,they dig deep holes which allows them to establish easily in wetlands and adjacent waterbodies that are hydrologically disconnected.This study takes place in the Gharb area(northwestern of Morocco)where several carcasses of P.clarkii have been found in different places.In the present study,it is a question of understanding how this species was introduced in this area,to establish a map of propagation of the species,and to evaluate the damage that it would have caused in the rice growing of Gharb.In Morocco,it was first sighted in the Gharb area in 2008 in the commune of Sidi Allal Tazi.Following this discovery,possible ways of the species introduction and the dispersal modes were explored that P.clarkii could use to invade the Gharb area.The results of this study can be used by natural resource managers,rice farmers,fishermen and the local population,to help them to locate the spread of P.clarkii,to identify vectors that move P.clarkii across political boundaries and illustrate the importance of limiting and prohibiting the movement of this invasive species across boundaries or into new ecosystems.展开更多
基金supported by the Scientific Fund of Hubei Agricultural Collegea grant from the Ministry of Education in Hubei Province,P.R.China
文摘An experiment was conducted to evaluate the effects of feeding various sources of dietary lipid on weight gain, feed conversion, survival and fatty acid composition of juvenile red swamp crawfish, Procam-barus clarkii. Six semi-purified diets containing vitamin-free casein, defatted soybean meal, 0. 5% choline chloride, 0. 5% glycine and 0. 5% cholesterol were supplemented with 6. 0% of either anchovy oil, linseed oil, soybean oil, rapeseed oil, safflower oil or pork lard. Each diet was fed to crawfish (3. 07±0. 21 g average weight) in three replicate aquaria for 60 days. Survival rate, weight gain and feed conversion were best for crawfish fed the diet containing anchovy oil. Crawfish fed the linseed oil diet had the second highest weight gain, followed by crawfish on soybean oil, repaseed oil, safflower oil and pork lard diets, respectively. Feed conversion values were a reflection of weight gain. Results showed that both n-6 and n-3 fatty acids are dietary essential for juvenile Procambarus clarkii, although n-3 fatty acids promoted faster growth than n-6. However, highly unsaturated fatty acids (HUFA) (20 : 5n-3 and 22 :6n-3) had better growth-promoting effect than 18 : 3n-3, due probably to the limited ability of crawfish to bioconvert fatty acids to polyenoic forms of longer chain length. The fatty acid composition of the crawfish generally reflected that of the dietary lipids, especially for the diets containing unsaturated fatty acids.
基金financed by the Key Technology R&D Program from the Ministry of Science and Technology,China (2006BAD06A01)the Opening Subject of Hubei Key Lab of Animal Embryo & Molecular Breeding (2007ZD07)the Promoting Fund of Anhui Province Finance Department, China (05C1001)
文摘The full-length cDNA sequence of prophenoloxidase was obtained through RACE technology. The complete cDNA sequence is 3 721-bp long, containing an open reading frame （ORF） of 1 881 bp, a 154-bp 5′-untranslated region, and a 1 686- bp 3′-untranslated region with three potential functional poly（A） signals （AATAAA）. The molecular mass of the deduced amino acid sequence （627 aa） was 72.3 kDa with an estimatedpI of 5.88. It contained putative copper-binding sites （copper A： 131, 135, 167 and copper B： 301,305, 341）, and a tentative complement-like motif （GCGWPDHL）. Eight potential N-linked glycosylation sites were predicted to be present in P. clarkii prophenoloxidase. Similar to those in other arthropod prophenoloxidases reported so far, no signal peptide was detected in the crayfish prophenoloxidase. The phylogenetic trees confirmed that P. clarkii prophenoloxidase was most closely related to that of freshwater crayfish P. leniusculus and more closely related to other crustacean prophenoloxidases from shrimp, prawn, and lobster than to the insect prophenoloxidases. Besides, two putative introns were found in this sequence of genomic DNA.
基金Supported by the Scientific Fund of Chinese Postdoctor (No. 2002032195).
文摘The effect of starvation on physiological and biochemical indicators of body, muscle and hepatopancreas were investigated for juvenile red swamp crawfish （Procambarus clarkii）, and the results showed the effect was obvious. In a 70-day starvation experiment, mean body weight, exuvial rate, abdominal muscle ratio and hepatosomatic index decreased significantly. The percentage of protein, fat, ash and moisture were also significantly affected. The protein content decreased sharply at Day 30 onward and the percentage of fat decreased rapidly from Day 50 and on. The percentages of ash and moisture started to increase significantly at Day 40 and 30 respectively. After the starvation experiment, the hepatopancreatic total and neutral lipid content decreased slightly from 23.90% to 20.39% and 73.75% to 70.35%, while the hepatopancreatic polar lipid content increased from 23.81% to 27.32%. On the other hand, all the muscular total, neutral and polar lipid contents, and the muscular fatty acid compositions did not change significantly except for the hepatopancreatic fatty acid composition. The relative percentages of 14：0, 16：0, 16：1n-7 and 18：1n-9 were decreased by 55.17%, 11.11%, 8.5% and 6.70% from the initial values, and the relative percentages of 18：2n-6, 18：3n-3, 20：4n-6, 20：5n-3 and 22：6n-3 increased obviously from 5.2%, 3.9%,4, 2.4%, 10.6%, and 13.7% to 7.1%, 5.0%, 2.8%, 11.5%, and 14.4% respectively. Preference of utilization of fatty acids from hepatopancreas during starvation was as follows： 14：0〉16：0〉16：1n-7〉18：1n-9, and the conservation of highly unsaturated fatty acids was in the order of： 18：2n-6 〉18：3n-3〉20：4n-6〉20：5n-3〉22：6n-3.
基金Supported by the Natural Science Fund Project of Jiangsu Province(No.BK20181138)the Central Public-Interest Scientifi c Institution Basal Research Fund,Freshwater Fisheries Research Center,CAFS(No.2019JBFZ09)。
文摘The morbidity and mortality peak of farmed Procambarus clarkii occurs around May every year,a phenomenon known as"Black May"disease(BMD).Increasing evidence shows that the intestinal flora is closely related to host health.We analyzed and compared the microbiota of healthy and BMDaffected P.clarkii intestines.The results show that there was no significant difference in bacterial a-diversity(richness P=0.59;evenness P=0.43;and diversity P=0.052)between the diseased group and the control group.Four dominant phyla in the intestines of crayfish in the control group,namely Tenericutes(30.86%),Bacteroidetes(29.99%),Firmicutes(22.23%),and Proteobacteria(15.23%),were identified.However,a striking shift in the microbial compo sition were found in the intestines of P.clarkii with BMD.Bacteroidetes was a dominant phylum in healthy P.clarkii,whereas the prevalence was low in diseased P.clarkii(1.87%).By contrast,the prevalence of Proteobacteria was significantly higher(P<0.05)in P.clarkii with BMD than in P.clarkii without BMD.Candidatus Bacilloplasma,Bacteroides,Vibrio,and Aeromonas showed significant differences(P<0.05)at the genus level.Tax4 Fun function prediction indicated that the relative abundance of genes involved in energy metabolism in the intestinal flora of P.clarkii with BMD was significantly reduced(P<0.05).Therefore,BMD can change the composition of the intestinal microbiota of P.clarkii.This study contributes to the understanding of the relationship between intestinal flora and host especially in aquatic animals.
基金funded by the Special Fund Project for the Scientific Research of the Forest Public Welfare Industry,State Forestry Bureau of China ( 200904001)the Three Projects of Aquatic Products of Jiangsu Province ( PJ2010-53)
文摘[ Objective] To provide basic research parameters for the laboratory culture of Procambarus clarkii using Salix saposhnikovii and the breeding materials for the clean environment-friendly aquaculture. [Method] The de-aerated water was used to culture the post larvae and P. clarkii juvenile. The effects of S. saposhnikovii roots on the survival rate, body length increase and body length variation coefficient of P. clarkii were in- vestigated. The survival rate of juvenile P. clarkii in the V class wastewater at 2 ammonia nitrogen concentrations were examined. [ Result] The post larvae of P. clarkii cultivated with S. saposhnikovii in the de-aerated water had significantly higher survival rate and longer body length than the control （ P 〈 0.05）, but there was no significant difference between the 2 treatments in the variation coefficient of body length. In the wastewater containing 2 mg/L ammonia nitrogen, the survival rate and ammonia nitrogen wastewater purification rate of the experimental juvenile P. clarkii were higher than the control. When the concentration of ammonia nitrogen increased to 10 mg/L, the survival rate of the experimental juvenile P. clarkii was still higher than the control, but there was no significant difference between the 2 groups in the purification rate of ammonia nitrogen. [ Conclu- sien] S. saposhnikovii has significant effect on the survival rate and growth of juvenile P. clarloTand can purify the wastewater containing 2 -10 mg/L ammonia nitrogen.
基金We would like to thank the undergradu- ate students from Guangxi Normal University, Yueni Huang, Chun Lan, and Caigui Nong, for their assistance in our experiment. This study was financially supported by Guangxi Science Foundation （2011GXNSFE018005）, Guangxi Key Laboratory of Environmental Engineering, Protection, and Assessment Kadoorie Farm ＆ Botanic Garden Corporation, Hong Kong and the Creative Team Project of the universities of Guangxi province, China.
文摘Procambarus clarkii is native to the south-central United States （Louisiana） and northeastern Mexico, and is a highly efficient predator that poses a damager to native species after its introduction or invasion. In its natural habitat, P. clarkii consumes Carassius auratus, however, whether C. auratus recognizes P. clarkii as a predator is not yet clear. In laboratory experiments, we investigated whether experienced and inexperienced C. auratus recognize P. clarkii as a predatory threat and the specific sensory modality used by C. auratus to respond to chemical and visual stimuli from P. clarkii. In the chemical stimuli experiment, two kinds of chemical stimuli were used, water from a tub containing P. clarkii previously fed with C. auratus （C. auratus diet cues） and water from a tub containing unfed P. clarkii （P. clarkii cues）. In the visual experiment, experienced C. auratus decreased activity, but inexperienced C.auratus avoided the predator compartment. When C. auratus diet cues were presented, both experienced and inexperienced C. auratus increased the use of shelter, decreased activity in the initial response phase. Compared with the blank treatment, experienced C. auratus responded to P. clarkii cues by decreasing activity; however, inexperienced C. auratus showed no reduction in activity. C. auratus appears to recognize P. clarkii as a predator both through visual and chemical cues. Further analysis revealed that C. auratus may recognize R clarkii visually through the disturbances caused by P. clarkii movement and chemically by detecting conspecific alarm cues in the diet of P. clarkii. The results also indicate that ex- perienced C. auratus can recognize R clarkii by innate chemical cues from P. clarkii, whereas inexperienced C. auratus cannot [Current Zoology 57 （3）： 330-339, 2011].
基金Supported by the National Natural Science Foundation of China(No.31672648)the Jiangsu Collaborative Innovation Center of Regional Modern Agriculture&Environmental Protection and Huaiyin Normal University(No.HSXT2-107)the Science&Technology Program of Huaiyin Normal University(No.31WH000)。
文摘The red swamp crayfish,Procambarus clarkii,is an economically important species especially in China.Their exoskeleton places serious constraints on growth and culture management.Their growth is achieved through intermittent molting/ecdysis.The longitudinal genetic dynamics for growth-related traits at different ecdysial points in P.clarkii has been unclear to date.In this study,conditional genetic analysis was carried out for growth-related traits(body weight,body length,chela length,and cephalothorax length)based upon a mixed genetic model with conditional additive,dominance,and genotype by environment effects in P.clarkii.A complete diallel cross was made among three geographic populations of P.clarkii for the genetic mating design.Results of the conditional genetic analysis showed that from 4 th molt to 9 th molt the conditional additive variations were increased significantly whereas the conditional non-additive genetic variations(dominance and genotype by environment interaction)were decreased significantly for these growth-related traits.This indicated that lots of new expression of additive effect genes for body weight,body length,chela length,and cephalothorax length occurred during ontogeny,and environment played a signifi cant role in the expression of genes affecting these growth-related traits.Growth of the four traits was mainly affected by non-additive genetic effects in early developmental stage(prior to 4 th molt).The cumulative conditional additive variation for the growth-related traits from 4 th molt to 9 th molt accounted for a large majority of the total conditional additive variations from 2 nd molt to 9 th molt,indicating that this period was very important for the growth of this species.Using the conditional analysis method,dynamics of growth-related traits during an important ontogenetic phase of red swamp crayfish was uncovered.Our results provide valuable insights into refining production of this species.
文摘Different concentrations of four metals namely copper, lead, chrome and cadmium were evaluated in crayfish Procambarus clarkii tissues (carapace, flesh) for a six-month period, from March to August 2013 in the Rharb of Morocco (Lagoon Merja Zerga and Nador canal). The determination of heavy metals was carried using atomic absorption spectroscopy Varian VV20. The results obtained revealed a metal’s contamination of Procambarus clarkii in both sites. Concentrations of heavy metals examined Procambarus clarkii carapace ranged as follows: Merja Zerga (Pb 2.07 - 6.7 μg/g;Cu 2.9 - 9.97 μg/g;Cr 0.89 - 14.22 μg/g dry weight) and Nador canal: (Pb 0.08 - 7.8 μg/g;Cu 3.40 - 9.3 μg/g;Cr 0.87 - 3.5 μg/g dry weight). Concentrations of heavy metals found in flesh were as follows: Merja Zerga (Pb 0.02 - 5.25 μg/g;Cu 9.58 - 23.59 μg/g;Cr 0 - 2.71 μg/g dry weight) and Nador canal (Pb 0.06 - 6.81 μg/g;Cu 9.5 - 37.20 μg/g;Cr 0 - 3.23 μg/g dry weight). The distribution of those metals in Procambarus clarkii shows high levels of contamination for lead, copper and chrome with an absence of cadmium in both sites (Merja Zerga and Nador canal). The concentrations differed in carapace and flesh.
文摘The red swamp crayfish(Procambarus clarkii)is a species from the northeast of Mexico and the central south of the United States(Louisiana),actually is the dominant macroinvertebrate in several countries.It was introduced to several countries,generally for gastronomic reasons or to repopulate destroyed areas by a disease.While the first introduction of this species into the world is well-documented,little is known about its pathways of invasion and the reason for its rapid spread in several countries.P.clarkii is an aggressive crustacean that multiplies very fast and adapts to features of the invaded location.Adults of the species can disperse up to 1.6 km on land.Also,they dig deep holes which allows them to establish easily in wetlands and adjacent waterbodies that are hydrologically disconnected.This study takes place in the Gharb area(northwestern of Morocco)where several carcasses of P.clarkii have been found in different places.In the present study,it is a question of understanding how this species was introduced in this area,to establish a map of propagation of the species,and to evaluate the damage that it would have caused in the rice growing of Gharb.In Morocco,it was first sighted in the Gharb area in 2008 in the commune of Sidi Allal Tazi.Following this discovery,possible ways of the species introduction and the dispersal modes were explored that P.clarkii could use to invade the Gharb area.The results of this study can be used by natural resource managers,rice farmers,fishermen and the local population,to help them to locate the spread of P.clarkii,to identify vectors that move P.clarkii across political boundaries and illustrate the importance of limiting and prohibiting the movement of this invasive species across boundaries or into new ecosystems.
