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1.
The teleost Scatophagus argus is a species whose females grows faster than males. Growth hormone(gh) mRNA abundance in females pituitary is higher than that in males; however the mechanism underlining such differential is still unknown. Growth hormone(GH) is tightly associated with GH-releasing hormone(Ghrh) in vertebrates. In this study, Ghrh gene(ghrh) and its receptor gene, ghrhr, were isolated from S. argus. Tissue expression analysis showed that ghrh and ghrhr were mainly expressed in hypothalamus while ghrhr was expressed in pituitary and gh was predominantly expressed in pituitary. Twenty cultured S. argus individuals were used to compare ghrh, ghrhr and gh mRNA abundances, 120 g and 181 g average weight for male(n =11) and female(n = 9), respectively. Real-time PCR indicated that the ghrh and ghrhr mRNA abundances in male hypothalamus were significantly higher than those in female hypothalamus while that of gh mRNA abundance was significantly higher in female pituitary than in male pituitary. The ghrh and ghrhr mRNA abundances were significantly up-regulated in female hypothalamus 3 h after injection of 0.1 mg kg~(-1) body weight Ghrh while pituitary ghrhr and gh mRNA abundances were not affected. In female hypothalamus, ghrh and ghrhr m RNA abundances were not affected at 6 h post-injection of 4 mg kg~(-1) body weight 17α-methyltes-tosterone(17α-MT) or 17β-Estradiol(E2). In female pituitary, ghrhr m RNA abundance was down-regulated by 17α-MT while that of gh m RNA abundance was up-regulated by E2. Our findings indicated that E2, rather than Ghrh, plays an important role in up-regulating the expression of gh in female S. argus, which should aid to understand the sexual dimorphism of teleost growth.  相似文献   

2.
The serum thyroid hormone and plasma catecholamine were examined in 18 male and 2 female members of the Chinese Antarctic Expedition (who spent the 2000 or 2001 austral winter at the Great Wall Station) . The changes of serum thyroid hormone i. e. total thyroxine (TT4) and free T4 (FT4) , total triodothyronine (TT3) and freeT3 ( FT3 ) , thyroid stimulating hormone ( TSH ) and plasma catecholamine, including norepinephrine (NE) , epinephrine ( E) and dopamine ( DA ) , were investigated by Chemoluminescence Immunoassay (CLIA) and High Performance Liquid Chromatography with electrochemical detection (HPLC-ECD) . Samples were taken at different time; (1)1 day before departure to Antarctica (16th expedition 1999/12/ 09; 17th expedition 2000/12/06). (2) 1 day after returned to China after living 54 weeks in Antarctica ( 16th expedition 2000/12/25 ; 17th expedition 2001/12/25 ). Comparing the data of before departure and returned, results showed that there was a significant decrease in the contents of TT4 (P <  相似文献   

3.
This paper determined the abundance of General Aerobic heterotrophic Bacteria(GAB) in surficial sediments from the Chukchi Sea and the Canadian basin by using MPN and discussed their geographical distribution.The result shows that the determination percentages of the GAB were high,even till 100 percentage.The abundance range and averages of GAB for 4℃and 25℃ were from 4.00×102 to 2.40×106,1.71×106 ind.·g-1(wet sample) and from 2.40×105 to 2.40×107,1.10×107 ind.·g-1(wet sample) respectively.Not only the abundance range but also the averages of GAB in 25℃ were higher than that in 4℃.The abundance of GAB in sediments show a tendency that it is roughly greater in the lower latitudinal area than in the higher latitudinal area.The abundance of GAB increased from east to west as for the longitudinal distribution.With the water depth increasing,the abundance of GAB at 4℃ decreased,but GBA at 25℃ is not changed obviously with water depth.It seems that warmer circumstantial temperature is more suitable for some GAB.  相似文献   

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6.
During the first Chinese Scientific Expedition to the Arctic in July - September 1999, cyanobacteria in the Bering Sea were measured by epifluorescence microscopy. Cyanobacterial abundance varied from 0 to 7. 93 × 103 cell/ml and decreased along a northerly directed latitudinal gradient in horizontal distribution. Cyanobacteria did not occur at station Bl - 12 (north of 60 °N). Vertically, high cya-nobacterial abundance appeared in the upper 25 - 50 m and decreased rapidly below 50 m. There were no cyanobacteria at the 150 m. Seawater temperature and NH4+ -N are suggested to affect the distribution of cyanobacteria.  相似文献   

7.
Viable cell count was used to determine whether Metschnikowia sp.C14 can colonize the intestine of juvenile sea cucumber Apostichopus japonicus.Sea cucumber individuals were divided into two groups,which were fed the control diet for 38 days or the C14-supplemented diet at 105 cells g−1 diet for 28 days,then the control diet from day 29 to day 38.The number of C14 cells in the intestine of sea cucumber fed the C14-supplemented diet significantly increased from day 7 to day 28,and decreased from day 29 to day 38.Sea cucumber fed with the diet containing C14 showed a significant increase in trypsin activity and lipase activity from day 21 to day 33 compared with the control.Feeding C14 significantly improved the phagocytic activity and respiratory burst in coelomocytes from day 21 to day 35 and from day 14 to day 38,respectively.In addition,there was an obvious enhancement in lysozyme activity(from day 21 to day 38 or day 33),phenoloxidase activity(from day 21 to day 28)and total nitric oxide synthase activity(from day 14 to day 38)in coelomic fluid supernatant and/or coelomocyte cell lysate supernatant compared with the control.There were significant positive correlations between the number of C14 cells colonizing the intestine and trypsin activity of the intestine,lysozyme activity of the coelomic fluid supernatant and coelomocyte lysate supernatant from sea cucumber.These data suggested that the number of C14 cells should be maintained at 105 cfu(colony-forming units)g−1 intestine material for the maximum benefit.  相似文献   

8.
To investigate the effects of salinity on early development of Chinese mitten crab(Eriocheir sinensis),and the salinity tolerance mechanism of embryos,different developmental stages of embryos(gastrula,eyespot and pre-hatching stage),and hatched stage I zoea and megalopa,were exposed to a range of salinities(1,5,10,15(control),20,25,30,35 and 40).Hatching,survival and molting were monitored.Effects of 24-hour hypersaline(35)and hyposaline(1)stress on egg diameter,water content,Na~+/K~+-ATPase(NKA)activity,and crustacean hyperglycemic hormone(CHH)gene mRNA expression in embryos and megalopa,are reported.Embryos are more tolerant of low(≤5)than high(≥25)salinities,with optimum ranges for gastrula and pre-hatching stage embryos being 5-20,and for eyespot embryo and stage I zoea,10-20.Most megalopa can molt to the first juvenile instar by day 5 at salinities between 1 and 40,whereas molting of megalopa stages was delayed at 40.Hypersaline conditions resulted in a loss of moisture,reduction of egg volume,and a significant increase in NKA activity and CHH mRNA expression at some developmental stages.Hyposaline conditions did not affect moisture content or egg volume,but resulted in decreased NKA activity and CHH mRNA expression in embryos.For megalopa stages,NKA activity was significantly upregulated following both hypo-and hypersaline stress.Our results suggest high salinity will inhibit development and hatching of E.sinensis embryos,and low salinity will affect the survival of their stage I zoea.Increased NKA activity in embryos and megalopa stages might indicate a hyporegulation response under hypersaline conditions.These findings provide useful information for spawning ground protection of indigenous E.sinensis and enrich the knowledge of embryonic tolerance mechanisms of hyperregulating crustaceans following osmotic stress.  相似文献   

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10.
The abundance and size composition of stream isopods Lirceus fontinalis were investigated from April 2001 to August 2002 in 3 streams in southern Ontario, Canada. Effects of current speed was released from the analysis by choosing slow flowing water. The effects of substrate, season and water depth on the abundance, distribution and size composition of the isopods were analyzed. It was found that substrate and season influence isopods the most. The rocky substrate with attached filamentous macro-algae contains an isopod abundance 7.05 times that of bare rock substrate and 14.6 times that of fine-sand and mud substrate. There was a large variation with respect to seasonality in both abundance and size composition of the isopods, with the highest abundance occurring in summer and the lowest in winter and spring; individual isopods also tend to be larger in the winter and spring. In all substrates, shallow areas tend to support higher densities of isopods than deeper areas.  相似文献   

11.
LAS degradation rate in Donghu Lake water under aerobic was much faster than under anaerobic condition . The half life of LAS in aerobic and anaerobic environment was 3.2 days and 57 days, respectively . The degradation rate at 25-27℃was approximately 20 times higher than that at 1.5-3.5℃.In a laboratory model aquatic ecosystem, two stages of bioconcentration in fish , daphnia and snail were observed . The first stage , on second day exposure , resulted from accumulation of intact LAS , and the second stage , on 16th day exposure , was due to metabolites . The bioconcentration factor (BCF) of LAS was extremely low in the muscle of hybrid carp (0.64), but rather high (2485) in the gall bladder .  相似文献   

12.
The Yellow Sea Cold Water Mass （YSCWM） was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly sampling along three transects across the northern boundary of the YSCWM during 2009-2010. Results show that thermal stratification existed from June to October and that the vertical thermal difference increased with depth. Generally, total abundance was lowest in October and highest in June, and the female/male sex ratio was highest in February and lowest in August. Evident spatial differences in abundance were observed during the existence of the YSCWM. In June, total abundance averaged 158.8 ind/m~ at well-stratified stations, and 532.1 ind/m3 at other stations. Similarly, high abundances of 322.0 and 324.4 ind/m3 were recorded from July to August inside the YSCWM, while the abundance decreased from 50.4 to 1.9 ind/m3 outside the water mass. C. sinicus distribution tended to even out over the study area in September when the YSCWM disappeared. We believe that the YSCWM may retard population recruitment in spring and preserve abundant cohorts in summer. The summer population was transported to neritic waters in autumn. In addition to low temperatures, stable vertical structure was also an essential condition for preservation of the summer population. C. sinicus can survive the summer in marginal areas in high abundance, but the population structure is completely different in terms of C5 proportion and sex ratio.  相似文献   

13.
Seasonal netzplankton samples from stations in the Changjiang (Yangtze River) Estuary were collected from May, 2004 to February, 2005. The dominant species and their contribution to the total zooplankton abundance were determined. Moreover, the relationship between the salinity and abundance was studied with stepwise linear regression. During the whole year, the salinity was positively correlated with the abundance, while the temperature, negatively. Linear regression analysis showed also a high positive correlation with salinity for total abundance in August and November, while in February and May, no obvious relations were found. The most abundant community was composed of neritic and brackish-water species. The North Passage (NP) (salinity <5) was greatly diluted by freshwater while the North Branch (NB) was brackish water with salinity range of 12–28. Consequently, clear decline in abundance of zooplankton was along the estuarine haloclines from the maximum in the area of high salinity to the minimum in the limnetic zone. Total zooplankton abundance and biomass were lower in NP than the NB in all seasons. In short, the salinity influenced the abundance of each species of zooplankton, and ultimately determined the total abundance of zooplankton. Furthermore, a winter peak in the abundance existed, which might be caused by the flourishing of Sinocalanus sinensis, a widely distributed species in the Changjiang Estuary.  相似文献   

14.
The neon flying squid, Ommastrephes bartramii, is a species of economically important cephalopod in the Northwest Pacific Ocean. Its short lifespan increases the susceptibility of the distribution and abundance to the direct impact of the environmental conditions. Based on the generalized linear model(GLM) and generalized additive model(GAM), the commercial fishery data from the Chinese squid-jigging fleets during 1995 to 2011 were used to examine the interannual and seasonal variability in the abundance of O. bartramii, and to evaluate the influences of variables on the abundance(catch per unit effort, CPUE). The results from GLM suggested that year, month, latitude, sea surface temperature(SST), mixed layer depth(MLD), and the interaction term(SST×MLD) were significant factors. The optimal model based on GAM included all the six significant variables and could explain 42.43% of the variance in nominal CPUE. The importance of the six variables was ranked by decreasing magnitude: year, month, latitude, SST, MLD and SST×MLD. The squid was mainly distributed in the waters between 40?N and 44?N in the Northwest Pacific Ocean. The optimal ranges of SST and MLD were from 14 to 20℃ and from 10 to 30 m, respectively. The squid abundance greatly fluctuated from 1995 to 2011. The CPUE was low during 1995–2002 and high during 2003–2008. Furthermore, the squid abundance was typically high in August. The interannual and seasonal variabilities in the squid abundance were associated with the variations of marine environmental conditions and the life history characteristics of squid.  相似文献   

15.
Flow cytometric determinations of the abundance distribution and community structure of picophytoplankton (i.e.,Prochlorococcus spp.,orange fluorescence Synechococcus spp.and picoeukaryotes) were used for samples taken from the Philippine Sea in the western tropical Pacific Ocean from September to October of 2004.A fluorescence probe was employed to detect Chlorophyll a (Chl a).Abundances of Prochlorococcus spp.,orange fluorescence Synechococcus spp.and picoeukaryotes ranged from 0.1 to 58×103 cells ml-1,0.38 to 17×102 cells ml-1 and 0.42 to 26×102 cells ml-1,respectively.Synechococcus spp.and picoeukaryotes co-occurred in relatively shallow water with the maximum abundance observed at 50 to 70 m depth,while Prochlorococcus spp.only occurred in the 70 to 200 m layer.Prochlorococcus spp.was the dominant picophytoplankton population in terms of abundance and biomass.The cell size and carbon biomass content were estimated for the three picophytoplankton groups.In addition,among the three groups of picophytoplankton,the relative contribution of red fluorescence to the total red fluorescence varied with depth.The fluorescence and light scatter properties of individual cells indicated that in the upper 100 m layer,picoeukaryotes were a major contributor to total red fluorescence,while at the depth below 100 m,Prochlorococcus spp.and Synechococcus spp.made an important contribution to the total red fluorescence.  相似文献   

16.
The culture of Sertoli cells has become an indispensable resource in studying spermatogenesis.A new Sertoli cell line(POSC) that consisted predominantly of fibroblast-like cells was derived from the testis of the olive flounder Paralichthys olivaceus and sub-cultured for 48 passages.Analysis of the mtDNA COI gene partial sequence confirmed that the cell line was from P.olivaceus.Cells were optimally maintained at 25℃ in DMEM/F12 medium supplemented with fetal bovine serum,basic fibroblast growth factor,and epidermal growth factor.The growth curve of POSC showed a typical "S" shape.Chromosome analysis revealed that the cell line possessed the normal P.olivaceus diploid karyotype of 2n=48t.POSC expressed dmrt1 but not vasa,which was detected using RT-PCR and sequencing.Immunocytochemistry revealed that the cells exhibited the testicular Sertoli cell marker FasL.Therefore,POSC appeared to consist of testicular Sertoli cells.Bright fluorescent signals were observed after the cells were transfected with pEGFP-N3 plasmid,with the transfection efficiency reaching 10%.This research not only offers an ideal model for further gene expression and regulation studies on P.olivaceus,but also serves as valuable material in studying fish spermatogenesis,Sertoli cell-germ cell interactions,and the mechanism of growth and development of testis.  相似文献   

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18.
We describe organogenesis at a histological level in American shad( Alosa sapidissima) larvae from 0 until 45 days after hatching(DAH). Larval development was divided into four stages based on the feeding mode,external morphological features,and structural changes in the organs: stage 1(0–2 DAH),stage 2(3–5 DAH),stage 3(6–26 DAH) and stage 4(27–45 DAH). At early stage 2(3 DAH),American shad larvae developed the initial digestive and absorptive tissues,including the mouth and anal opening,buccopharyngeal cavity,oesophagus,incipient stomach,anterior and posterior intestine,differentiated hepatocytes,and exocrine pancreas. The digestive and absorptive capacity developed further in stages 2 to 3,at which time the pharyngeal teeth,taste buds,gut mucosa folds,differentiated stomach,and gastric glands could be observed. Four defined compartments were discernible in the heart at 4 DAH. From 3 to 13 DAH,the excretory systems started to develop,accompanied by urinary bladder opening,the appearance and development of primordial pronephros,and the proliferation and convolution of renal tubules. Primordial gills were detected at 2 DAH,the pseudobranch was visible at 6 DAH,and the filaments and lamellae proliferated rapidly during stage 3. The primordial swim bladder was first observed at 2 DAH and started to inflate at 9 DAH; from then on,it expanded constantly. The spleen was first observed at 8 DAH and the thymus was evident at 12 DAH. From stage 4 onwards,most organs essentially manifested an increase in size,number,and complexity of tissue structure.  相似文献   

19.
In order to understand the large-scale spatial distribution characteristics of picoplankton,nanophytoplankton and virio-plankton and their relationship with environmental variables in coastal and offshore waters,flow cytometry(FCM) was used to ana-lyze microbial abundance of samples collected in summer from four depths at 36 stations in the North Yellow Sea(NYS).The data revealed spatial heterogeneity in microbial populations in the offshore and near-shore waters of the NYS during the summer.For the surface layer,picoeukaryotes were abundant in the near-shore waters,Synechococcus was abundant in the offshore areas,and bacte-rial and viral abundances were high in the near-shore waters around the Liaodong peninsula.In the near-shore waters,no significant vertical variation of picophytoplankton(0.2-2μm) abundance was found.However,the nanophytoplankton abundance was higher in the upper layers(from the surface to 10 m depth) than in the bottom layer.For the offshore waters,both pico-and nanophytoplankton(2-20μm) abundance decreased sharply with depth in the North Yellow Sea Cold Water Mass(NYSCWM).But,for the vertical dis-tribution of virus and bacteria abundance,no significant variation was observed in both near-shore and offshore waters.Autotrophic microbes were more sensitive to environmental change than heterotrophic microbes and viruses.Viruses showed a positive correla-tion with bacterial abundance,suggesting that the bacteriophage might be prominent for virioplankton(about 0.45μm) in summer in the NYS and that viral abundance might play an important role in microbial loop functions.  相似文献   

20.
Pituitary adenylate cyclase activating polypeptide(PACAP)and growth hormone-releasing hormone(GHRH)play important roles in the GH/IGF growth axis in fishes.To determine whether epigenetic change is involved in the regulation of pacap and ghrh responses to low salinity stress in Cynoglossus semilaevis,the correlation between growth traits,DNA methylation status and gene expression level in low salinity(15,S15)and optimal salinity(30,S30)at day 7(D7)and day 60(D60)were analyzed.Results showed that exposure to low salinity for 60 days attenuated C.semilaevis growth rate.Under low salinity,DNA methylation level of pacap promoter increased in females and decreased in males at day 7,but inverted at day 60.Additionally,pacap expression was up-regulated in both males and females.The pacap promoter methylation level was higher and expression level was lower in female than in male.The results suggest that pacap promoter methylation level is negatively correlated to mRNA level and positively correlated to body weight,while gene expression level is negatively related with body weight.With the decrease of salinity,DNA methylation level of ghrh promoter and exon1,as well as its gene expression displayed minor changes.Overall,pacap gene seems to play an important role in fish growth,contributing to female growth superiority,while ghrh gene seems not pertinent under salinity stress.The results indicate that low salinity potentially affects fish growth through regulating DNA methylation in pacap promoter.This study expands the understanding of the molecular mechanism of how salinity modulates fish growth from the epigenetic perspective.  相似文献   

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