Effects of different photoperiods on growth, stress and haematological parameters in juvenile great sturgeon Huso huso

The effects of constant light (24L:00D), no light (00L:24D) and two light–dark periods (18L:06D;12L:12D) on the growth, stress and haematological variables were assessed in juvenile great sturgeon, Huso huso . During the 8-week experimental period, juveniles (22.5 ± 0.6 g) were kept under a 150 lx light intensity in fibreglass tanks (0.8 m², 500 L). Differences in growth were insignificant during the experiment, but lactate levels were higher in the 00L:24D and 24L:00D photoperiods compared with 12L:12D and 18L:06D photoperiods. Cortisol levels did not show differences among the various photoperiods. At the end of the experimental period, fish reared under a 12L:12D photoperiod had higher haemoglobin values and erythrocyte numbers than in the other photoperiods, while no differences were found between groups with regard to haematocrit values or leucocyte numbers. The highest survival rate (89%) was observed in the 12L:12D period in which the levels of lactate and cortisol as stress indicators were minimal. The results indicate that various photoperiods cause different stress levels in juvenile great sturgeon and have no significant effects on growth, at least in short time periods.     

Digestibility of selected feedstuffs in subadult Caspian great sturgeon,Huso huso using settlement faecal collection and stripping methods

Apparent crude protein (ADC_CP), crude fat (ADC_CF) and gross energy (ADC_GE) digestibility coefficients of several typical and novel feedstuffs were determined to be employed in the formulated diets of subadult beluga (17.70 ± 0.234 kg) diets via two faecal collection methods of settlement (SFCM) and stripping (StM). The tested feedstuffs included three fish meals, three terrestrial animal by‐products, three plant protein concentrates, nine high‐protein plant meals and three low plant protein meals. ADC_CP values varied in different fish meals ranging from 89.5% for Mexican sardine meal to 93.2% for anchovy meal with SFCM. ADC_CP values for plant protein concentrates ranged from 82.8% for wheat gluten meal to 92% for soy protein with SFCM. ADC_CP ranged from 37.2% for whole wheat to 75.6% for spirulina meal with SFCM. ADC_GE was lower in low‐protein plant meals (64.1%) in comparison to high‐protein plant meals (70.2%). Fish meals showed the highest ADC_CF values. A significant (P < 0.05) quadratic regression relation (r² = 0.92) was observed among in vivo ADC_CP of five feedstuff classes fed to beluga and in vitro ADC_CP. The differences among ADC values appear to be significantly related to the effects of feedstuffs and therefore diet and faecal collection methods.     

Growth efficiency, body composition, survival and haematological changes in great sturgeon (Huso huso Linnaeus, 1758) juveniles fed diets supplemented with different levels of Ergosan

Growth performance, carcass quality, survival and haematological responses were determined when Huso huso juvenile (41.7±1.8 g) fed diets containing Ergosan (an algal product) at 0, 2.0, 4.0 and 6.0 g kg⁻¹ for 60 days. Each diet was fed to triplicate groups of fish at 10-day intervals (1–10, 20–30 and 40–50 with non-supplemented diets and 10–20, 30–40 and 50–60 with supplemented diets). Results showed that fish fed diets containing Ergosan had significantly higher growth than the control group ( P <0.05). Survival was not different among all dietary treatments ( P >0.05). Food conversion ratio in the fish fed a diet containing 4.0 and 6.0 g kg⁻¹ Ergosan was significantly better than the other treatments ( P <0.05), whereas protein efficiency ratio was not different between experimental diets. Lymphocyte count in the fish fed diets containing Ergosan was higher than the other treatments. Haematocrit, haemoglobin (Hb) concentration, number of erythrocytes, total leucocytes, monocyte, eosinophil, myelocyte, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration were not different between treatments. Neutrophil count in the control group was higher than the fish fed supplemented diets. Furthermore, whole body lipid, moisture and fibre were not different among dietary treatments ( P >0.05) but body protein in the fish fed a diet containing Ergosan at the level of 2.0 and 4.0 g kg⁻¹ was higher than the other treatments. Whole body ash content was higher in the control group. It was concluded that dietary administration of Ergosan can influence some growth and haematological parameters in great sturgeon, H. huso juveniles.     

Gonadogenesis in scallop Chlamys farreri and Cf‐foxl2 expression pattern during gonadal sex differentiation

Gonad development and sexual differentiation are important biological processes. More insight is needed in these processes to improve selection and breeding efficiency in the production of culture animals for monosex farm operations of commercially important shellfish species. Foxl2 is the earliest known sex dimorphic marker of ovarian differentiation in mammals, but studies on foxl2 in invertebrate species are rare. This study revealed the gonadogenesis and expression characteristics of foxl2 during the gonadal differentiation in the scallop Chlamys farreri, an important commercial mollusk in China. The result showed that C. farreri gonad becomes visible once juveniles reach a shell height of 5.5 mm. Sex can be distinguished based on gonad histology in animals with a minimum shell height of 9 mm. Expression of Cf‐foxl2 (C. farreri foxl2) was first observed in cytoplasm of ovarian germ and follicle cells, just after the initiation of ovarian differentiation. Results indicate that Cf‐foxl2 can be used as an early sex‐marker gene, and may have participated in the regulation of ovary differentiation in C. farreri.     

斑节对虾Chitinase-2基因的克隆及其在蜕皮和幼体发育过程中的表达分析

研究以斑节对虾(Penaeus monodon)转录组获得的几丁质酶基因(Pm Chi)片段,运用RACE技术克隆了PmChi基因c DNA全长,命名为PmChi-2。PmChi-2基因c DNA全长2 050 bp,其中5'-非编码区(5'-UTR)144 bp、3'-UTR 319 bp和开放阅读框(ORF)1 587 bp,编码528个氨基酸。生物信息学分析显示,PmChi-2与其他甲壳动物Chi-2的相似性为78%~97%。实时荧光定量PCR结果显示,PmChi-2在蜕皮前期(D期)表皮中表达水平最高,在胃、鳃、腹神经节和眼柄中表达水平依次降低,在其他组织(肝胰腺、肠、肌肉、心脏)中几乎不表达。不同蜕皮阶段,PmChi-2在鳃、胃和表皮3种组织中的表达变化模式基本一致,均在蜕皮期(E期)表达量最低,而最高表达量在鳃中出现在蜕皮后期(A期),在胃和表皮中为D期。幼体不同发育阶段分析揭示PmChi-2 mRNA在幼体发育阶段的无节幼体到糠虾幼体第二期表达量维持在一个低水平,在糠虾幼体第三期PmChi-2 mRNA表达水平显著升高,在仔虾期又显著下降,推测PmChi-2 mRNA可能与斑节对虾幼体发育密切相关。研究结果表明PmChi-2基因可能在斑节对虾蜕皮以及幼体的变态发育中发挥重要作用,为深入研究斑节对虾几丁质酶发育调控提供了重要信息。     

中华鳖NR5a2基因的克隆与表达分析

为了解NR5a2在中华鳖(Pelodiscus sinensis)性腺分化过程中的作用,通过RACE技术克隆获得中华鳖NR5a2 cDNA。结果显示:该基因序列全长为2 674 bp,开放阅读框为1 608 bp,编码535个氨基酸,5′非编码区长度为40 bp,3′非编码区长度为1 026 bp。生物信息学分析表明该基因编码的蛋白质分子质量为60.5 ku,等电点为8.57,具有保守的ZnF-C4结构域和HOLI结构域。氨基酸多重序列比对分析表明中华鳖NR5a2基因与西部锦龟(Chrysemys picta bellii)的相似性最高,其次是原鸡(Gallus gallus)。系统进化分析表明中华鳖NR5a2与西部锦龟的亲缘关系最近。实时荧光定量PCR结果表明NR5a2在中华鳖不同组织中均有表达,且卵巢组织中的表达量显著高于精巢组织。31.5℃孵化条件下,不同发育时期的中华鳖胚胎组织中发现NR5a2基因在17期时表达量达到最高,随后显著下降。结果表明NR5a2可能参与中华鳖的性别分化。     

高温诱导对性成熟尼罗罗非鱼性腺中性别分化相关基因表达的影响

利用qRT-PCR系统分析了高温诱导对8月龄尼罗罗非鱼(Oreochromis niloticus)性腺组织中8个性别分化相关基因、4个热激蛋白基因及2个甲基转移酶基因表达的影响。结果显示, 高温诱导能显著下调卵巢发育相关基因Cyp19a1a、ERα和ERβ的表达水平(P<0.05), 但对雌鱼精巢发育相关基因Cyp11b2和Dmrt1的表达水平没有显著影响(P>0.05), 这与高温对性腺分化期罗非鱼性别分化相关基因表达的影响不同。高温诱导后雌雄鱼性腺中Hsp70的表达水平显著上升(P<0.05), 而DNAJB1的表达水平却显著下降(P<0.05), Hsp27和Hsp90的表达水平无显著变化。高温诱导能显著上调雌鱼性腺中Dnmt1与Dnmt3a基因的表达水平(P<0.05)。本研究通过分析高温诱导对性成熟尼罗罗非鱼性别分化相关基因表达的影响, 旨在揭示高温诱导对罗非鱼性别分化相关基因表达的影响具有一定的时期特异性, 为研究温度影响鱼类性别分化的分子机理提供基础。

     

Effects of dietary L‐carnitine level on growth performance,body composition and antioxidant status in beluga (Huso huso L. 1758)

A 17‐week feeding trial was carried out to evaluate the effects of dietary L‐carnitine level in beluga, Huso huso. A total of fish averaging 1247 ± 15.6 g (mean ± SD) were randomly distributed into 18 fibreglass tanks, and each tank holding 10 fish was then randomly assigned to one of three replicates of six diets with 50, 150, 350, 650, 950 and 1250 mg L‐carnitine kg^?1 diet. At the end of 17 weeks of feeding trial, average weight gain (WG), feed efficiency (FE), protein efficiency ratio (PER) and condition factor (CF) of fish fed 350 mg kg^?1 diet were significantly (P < 0.05) higher than those of fish fed 50, 150, 950 and 1250 mg kg^?1 diets. WG, FE, PER and CF of beluga fed 650 mg kg^?1 diet were also significantly higher than those of fish fed 50, 950 and 1250 mg kg^?1 diets. Whole body and muscle protein were significantly improved by the elevation of dietary L‐carnitine level up to 350 mg kg^?1. Liver superoxide dismutase and glutathione peroxidase activities of fish fed 350 and 650 mg kg^?1 diets were significantly higher than those of fish fed 50, 950 and 1250 mg kg^?1 diets. The dietary L‐carnitine level of 350–650 mg kg^?1 diet could improve growth performance, feed utilization, protein‐sparing effects of lipid, antioxidant defence system and reproductive success. Polynomial regression of WG suggested that the optimum dietary L‐carnitine level was 480 mg kg^?1 diet. Therefore, these results may indicate that the optimum dietary L‐carnitine could be higher than 350 but <650 mg kg^?1 diet in beluga reared in intensive culture conditions.     

金钱鱼孕激素受体基因的克隆、鉴定与表达研究

核受体(Pgr),隶属于核受体超家族,由核受体亚家族3C组成员3基因编码.孕酮通过结合Pg r介导其在脊椎动物繁殖过程中的生理学功能,因此,研究金钱鱼核受体基因(pg r基因)在不同组织及不同发育时期性腺中的表达模式,有助于为金钱鱼的繁殖提供理论依据.笔者克隆金钱鱼的pg r基因,用Megalign软件比较Pgr氨基酸...     

拟穴青蟹Sp-Sox14基因在胚胎发育和性腺发育过程中的表达

为了解Sox14基因在拟穴青蟹胚胎发育和性腺发育过程中可能起到的调控作用,实验从青蟹性腺转录组数据库中得到全长为2558 bp的Sp-Sox14 c DNA序列,该序列编码一个包含427个氨基酸的蛋白,包含一个HMG-box。进化树分析表明,Sp-Sox14与其他节肢动物的Sox14亲缘关系较近。实时定量PCR结果显示,Sp-Sox14在成蟹雌雄各组织中均有不同程度的表达,其中在卵巢和雄蟹心脏中的表达量最高。在胚胎发育过程中,SpSox14在复眼色素形成期的表达量显著高于其他时期。在性腺不同发育阶段,Sp-Sox14在卵黄发生前期(O2)的表达量显著高于卵巢其他发育阶段;而在精巢发育过程中,其表达量在成熟精子期(T3)高于精母细胞期(T1)和精子细胞期(T2)。推测其参与卵巢的前期发育以及精子成熟等过程。整胚原位杂交结果显示,Sp-Sox14在青蟹胚胎复眼色素形成期阳性信号定位于头部以及鄂足附近,在近孵化期定位于复眼附近,幼体孵出期则在头部仍有少量信号,暗示其与青蟹神经器官的形成以及体节附肢的发生有关。     

西伯利亚鲟不同性别与卵巢发育时期血液性类固醇激素的差异与判别分析

利用电化学发光免疫分析法(ECLIA)测定了人工养殖西伯利亚鲟(Acipenser baerii baerii)不同性别和卵巢发育时期血浆中睾酮(T)和雌二醇(E2)的含量。利用活组织取样的方法,根据性别和卵子颜色及大小将实验鱼分为成熟雄鱼(M)、雌鱼Ⅲ期、Ⅳ期和Ⅴ期共4个组。研究结果表明,西伯利亚鲟血浆T含量雄鱼高于雌鱼(P<0.01),且雄鱼与雌鱼Ⅲ期和Ⅴ期组有极显著性差异(P<0.01),而E2含量除与雌鱼Ⅳ期有极显著性差异外(P<0.01),与雌鱼Ⅲ期和Ⅴ期组无显著性差异(P>0.05),雄鱼表现为T含量和T/E2比值高,而E2含量低。雌鱼随卵巢的发育T和E2含量均表现为"先上升,后下降"的趋势,即Ⅳ期组性类固醇激素的含量明显高于Ⅲ期和Ⅴ期,且差异极显著(P<0.01)。根据血浆中T和E2的含量建立了西伯利亚鲟性别和性腺发育时期的4个判别函数:YM=-11.322+0.043T+0.153E2,YⅢ=-1.390+0.000T+0.061E2,YⅣ=-18.074+0.032T+3.305E2,YⅤ=-2.316+0.785T+0.008E2,经检验总体判别准确率为95%,其中对性别的判别准确率为100%,对雌鱼卵巢发育时期的判别准确率为93%。     

团头鲂性腺发育不同时期组织学观察及Kiss2／Kiss2r基因表达分析

Kiss基因（Kisspeptin）及其受体Kissr基因（Kiss receptor）组成的系统参与下丘脑-垂体-性腺轴功能的调节,在脊椎动物青春期启动的过程中发挥重要作用。该研究通过组织切片技术观察了团头鲂（Megalobrama amblycephala）卵巢和精巢的不同分期,进一步采用荧光定量PCR技术分析比较了团头鲂Kiss2和Kiss2r基因在雌、雄性腺不同时期对应的脑、垂体、性腺组织中的表达量。组织切片观察明确鉴别出团头鲂卵巢和精巢发育Ⅰ期至Ⅵ期的性腺组织结构,基因荧光定量PCR分析结果表明Kiss2/Kiss2r系统主要是通过增加团头鲂卵巢发育Ⅱ期时脑和垂体的表达量以及Ⅲ期精巢的表达量来发挥生殖启动作用。     

拟穴青蟹PHGPx基因的克隆及其表达分析

磷脂氢谷胱甘肽过氧化物酶(Phospholipid hydroperoxide Glutathione Peroxidase, PHGPx)是GPx基因家族的重要一员,能特异地清除磷脂和胆固醇等氢过氧化物,在机体抗氧化、抗凋亡、抗炎症以及雄性性成熟等过程中发挥着重要的作用。本研究从实验室拟穴青蟹(Scylla Paramamosain)转录组数据库中筛选出该基因的EST序列,利用SMART-RACE 技术克隆得到该基因的全长cDNA。经Blast 比对后,其与丰年虾(Artemia franciscana)的PHGPx氨基酸序列一致性最高,达到69%。同时系统进化树分析表明,该基因与其他物种的PHGPx(GPx4)聚为一支,而与GPx1、GPx2等亚型距离较远,故命名该基因为Sp-PHGPx。实时定量PCR结果显示,Sp-PHGPx在成熟青蟹雌雄各组织中均有不同程度的表达,其中精巢的表达量最高;且在雌雄相同组织中,雌性性腺的表达量显著低于雄性;而在鳃和心脏中的表达量显著高于雄性。在性腺不同发育阶段,Sp-PHGPx在卵巢发育过程中的表达量差异不显著;而在精巢发育过程中,其表达量在精子细胞期(T2期)显著高于精母细胞期(T1期)和成熟精子期(T3期),同时也显著高于卵巢发育各时期的表达量。在LPS应激下,鳃和肝胰腺中Sp-PHGPx的表达量分别在6h和12h显著上调;H2O2应激下,鳃中的表达量在3 h显著升高,肝胰腺中的表达量在被检测的各时相中无显著差异。以上结果表明,Sp-PHGPx可能在免疫防御反应以及精巢的发育和成熟等过程中发挥着重要作用。     

半滑舌鳎Shh基因的克隆与表达及甲基化分析

通过RACE方法获得半滑舌鳎(Cynoglossus semilaevis)Hh基因家族的Shh基因,该基因全长1 922 bp,其中5′UTR 266 bp,3′UTR 360 bp,ORF1 296 bp,编码431个氨基酸,经预测该多肽的相对分子质量为47.28 k D,理论等电点6.95,具有Hh基因家族特有的保守结构域。氨基酸序列分析表明,半滑舌鳎Shh与牙鲆的同源性最高,为82%,与其他鱼类同源性为74%~81%,与非洲爪蟾的同源性为61%,与人和鼠的同源性为63%~64%。甲基化结果显示,Shh基因在1龄卵巢中的甲基化程度普遍低于雄鱼与伪雄鱼精巢。基因表达分析显示,Shh基因在胚胎期的囊胚期表达显著高于其它时期(P0.05),在雌雄成鱼8个组织器官均表达,在雌性性腺分化的关键期孵化后50 d,雌性性腺中表达量较前期升高,且显著高于同时期雄性性腺中的表达(P0.05),在雄性性腺分化的关键期80~95 d,Shh基因在雄性中的表达水平显著升高(P0.05),在8月龄、1龄及2龄雌鱼性腺中表达显著高于雄鱼与伪雄鱼。本研究表明,半滑舌鳎Shh基因在进化中高度保守,与胚胎分化、组织器官形成、雌雄性腺分化及性腺发育密切相关。     

Influence of pejerrey Odontesthes bonariensis (Valenciennes, 1835) broodstock age on gamete quality,reproductive performance and plasma sex steroid levels during the spawning season

This study evaluated the effect of pejerrey Odontesthes bonariensis (Valenciennes, 1835) broodstock age on gamete and spawning quality and its relationship with sex steroid plasma levels. Sperm was analysed using a computer‐assisted sperm analysis (CASA) developed for pejerrey. Semen samples were taken from all fish from mid age groups (5‐ and 7‐year fish), but it was not possible to obtain stripped semen samples from all fish of younger (3‐year) or older (10‐year) groups. The highest relative sperm weight and sperm concentration were recorded in 5‐ and 7‐year groups respectively, while viability was not different between age groups. It was not possible to identify an effect of age on sperm quality by CASA. Non‐viable spawned eggs were obtained in the 3‐year group and, the relative fecundity and the relative number of fertilized eggs decreased with age in other groups. Fertilization and hatching rates showed the highest values in the 10‐year group. However, the estimated number of hatched larvae was similar in 5‐, 7‐ and 10‐year fish. A clear effect of age on 11 ketotestosterone (11‐KT) and estradiol (E₂) levels was identified, with the highest values in the 5‐ and 7‐year groups. These results might be related to the onset of puberty in the 3‐year group and ageing in the 10‐year group. Considering that the estimated number of larvae obtained was similar among age groups, the results of this study suggest that broodstock maintenance cost could be reduced by using mid‐age fish rather than older fish in pejerrey hatcheries.     

尼罗罗非鱼卵巢发育过程中性类固醇激素与卵黄蛋白原含量变化及Vtg mRNA 表达特征

通过组织切片、酶联免疫吸附及荧光定量PCR等方法,研究了尼罗罗非鱼(Oreochromis niloticus)卵巢发育过程中性类固醇激素(雌二醇E2、孕酮P)、卵黄蛋白原(Vtg)含量及Vtg mRNA相对表达水平变化规律。结果表明,尼罗罗非鱼性腺指数(GSI)与卵巢成熟发育间呈同步性变化,Ⅴ期达到峰值。血清中E2含量自卵巢Ⅱ期开始显著升高,Ⅳ期达到峰值,Ⅴ期后显著下降;血清P含量自卵巢Ⅱ期开始不断升高,Ⅴ期达到峰值,Ⅵ期显著下降;E2、P分别在卵巢成熟发育前期与后期发挥作用。肝中Vtg含量先升、后降,Ⅳ期达峰值;血清、卵巢中Vtg含量均自Ⅱ期开始增加,Ⅴ期达峰值,Ⅵ期显著降低;不同组织中Vtg含量变化与卵巢成熟发育间存在密切关联。肝中Vtg mRNA表达水平在Ⅲ期达到峰值,Ⅳ期后持续下调;卵巢中Vtg mRNA表达水平相对较低,Ⅴ期达到峰值;初步推测肝、卵巢同是尼罗罗非鱼Vtg合成部位,肝是Vtg合成的主要器官,在卵黄积累阶段最为活跃,而卵巢Vtg合成水平相对较低。     

拟穴青蟹不同发育时期胚胎基因表达的内参基因的筛选

为获得适用于研究拟穴青蟹(Scylla paramamosain)不同发育时期胚胎基因表达的内参基因,本研究采用3个内参基因筛选软件geNorm、NormFinder及BestKeeper对微管蛋白α1A(Tuba1a)、核糖体蛋白L13(Rpl13)、泛素(UBQ)、核糖体蛋白S6激酶(Rps6)、精氨酸激酶(Ak)、3-磷酸甘油脱氢酶(gapdh)、28S核糖体RNA(28S)、18S核糖体RNA(18S)和延伸因子1A基因(EF-1α)等9个常用候选内参基因在拟穴青蟹不同发育时期胚胎的表达稳定性进行分析。geNorm分析表明, EF-1α和Rpl13的表达稳定性最高,并且采用2个内参基因同时校正目标基因的定量结果可以达到最优效果; NormFinder分析表明, gapdh和EF-1α是9个候选内参基因中表达最稳定的; BestKeeper分析表明,gapdh的标准偏差和变异系数是9个候选基因中最低的。综合3个内参基因筛选软件,可以选用EF-1α,或选用EF-1α和gapdh双内参同时校正拟穴青蟹不同胚胎发育时期各基因的表达情况。     

Characterization of the quality of the gametes and sex steroid levels during spring and summer spawning events in pejerrey Odontesthes bonariensis reared under natural conditions of temperature and photoperiod

Pejerrey Odontesthes bonariensis spawning period takes place during the end of winter and spring and, depending on temperature conditions, during late summer and autumn. Nevertheless, the occurrence and quality of the summer–autumn spawning period have not been well documented and are not considered for aquaculture production. In this context, this study aimed to characterize the reproductive activity of pejerrey reared in captivity under natural conditions of temperature and photoperiod throughout a year in order to summarize the spawning quality of the two spawning periods. The present results showed that pejerrey might spawn from late winter to the end of the spring with a peak in October (mid‐spring) and, also during summer and early autumn, interrupted by a period of 56 days without spawning activity in between. The extension of both spawning periods was almost equal (67 and 69 days). Nevertheless, higher relative fecundity and larger egg size were observed during the first spawning period, associated with higher levels of oestradiol measured in females demonstrating that it is better than the second spawning. The fertilization rate was not affected throughout the reproductive periods. These differences in the reproductive parameters are discussed in order to design specific strategies to increase seed production.     

Effects of acute and chronic zinc exposure on steroid hormone receptor expression in the lined seahorse,Hippocampus erectus

The element zinc (Zn) can elicit a variety of physiological responses in animals, particularly through its effects on steroid hormone receptor expression. Here, we evaluated the effects of Zn on the expression profiles of steroid hormone receptors in the lined seahorse, Hippocampus erectus, following experimental acute and chronic Zn exposure. Complex response patterns were observed; however, steroid hormone receptor expression in liver and kidney following 12‐day Zn injection (acute exposure) differed significantly from the control treatments. Apparent effects on hepatic lipid metabolism and osmotic regulation in the kidney need detailed investigation. Furthermore, 49‐day (chronic) waterborne Zn exposure produced a significant decrease in both estrogen receptor (ER) expression levels and estradiol concentrations. In additional, chronic exposure led to a substantial reduction of hepatic adipose cells, implying that Zn may regulate hepatic lipid metabolism via ER and estradiol. Our study demonstrated the effects of both acute and chronic Zn exposure on expression patterns of steroid hormone receptors, which will contribute to understanding the mechanism of Zn‐induced hepatic lipid metabolism and other physiological responses in seahorses.     

达氏鲟dmc1基因的克隆及在精子生成中的表达分析

DNA减数分裂重组酶1基因(disrupted meiotic cDNA,dmc1)是一个在减数分裂时期特异表达的基因,为减数分裂同源染色体配对所必需。为研究dmc1基因在达氏鲟(Acipenser dabryanus)不同组织的表达特征,从达氏鲟性腺转录组数据库搜索得到该基因并设计引物,克隆获得达氏鲟dmc1的编码区序列,其中开放阅读框(ORF)为1 029 bp,编码342个氨基酸。运用生物信息学方法分析达氏鲟dmc1基因编码的蛋白序列和系统进化关系,推测达氏鲟Dmc1蛋白的分子量为82.696 kDa,理论等电点(PI)为5.04;多重序列比对发现,Dmc1氨氮酸序列在进化中可能比较保守。系统进化分析显示,AdDmc1属于RecA家族Dmc1蛋白分支,且与四足动物类聚为一支。RT-PCR结果表明,dmc1基因在精巢和卵巢中特异表达。结合组织学结果通过实时荧光定量PCR研究dmc1基因在精子生成过程中的表达特征发现,dmc1基因在0~Ⅰ期精巢中不表达;在Ⅱ、Ⅲ、Ⅳ期精巢中,其表达量逐渐升高并在Ⅳ期精巢中达到最高;在Ⅴ期精巢中,其表达量显著性下降(P<0.05),因此推断达氏鲟dmc1基因可能是减数分裂时期特异表达的基因,研究结果可为后续达氏鲟初级和次级精母细胞的鉴定奠定基础。