In vitro effect of pituitary,interrenal and gonadal hormones on vitellogenin synthesis in primary hepatocyte cultures of Chalcalburnus tarichi

Vitellogenin (Vtg) is an important precursor yolk protein in egg‐laying vertebrates, including fish. The 17β‐oestradiol (E2) plays a crucial role in the Vtg synthesis; moreover, certain hormones can stimulate Vtg synthesis. We investigated the possible role of E2, carp recombinant growth hormone (crGH), insulin (Ins), progesterone (P4) and 11‐deoxycortisol (11‐DOC) hormones in Vtg synthesis on primary juvenile Chalcalburnus tarichi hepatocyte culture. The amount of Vtg in the medium was measured at 2‐day intervals using enzyme‐linked immunosorbent assay (ELISA). The hepatocytes were maintained in culture for more than 2 weeks without the addition of serum components. Vitellogenin localization was visualized with the immunofluorescence method in E2‐supplemented hepatocytes. Among hormones applied to the culture, only E2 had an influence on Vtg synthesis in a time‐dependent manner, while crGH, Ins, P4 and 11‐DOC had no effect. However, in hepatocytes stimulated with E2 in combination with P4, a lower Vtg production was seen compared with Vtg produced when hepatocytes were stimulated with E2 alone. P4 proved to have potentiating effects on co‐treatment with E2‐induced Vtg production. As a result, E2 and P4 are the most important hormones for Vtg synthesis in juvenile C. tarichi hepatocyte culture.     

Dietary fish oil replacement by soybean oil: Effect on plasma vitellogenin,sex steroids and ovarian steroidogenesis in Chinese strip‐necked turtles (Mauremys sinensis)

In order to investigate the effects of dietary fish oil replacement, the turtles (Mauremys sinensis) were fed four experimental diets for 10 months: FO (100% fish oil), FSO (70% fish oil and 30% soybean oil), SFO (30% fish oil and 70% soybean oil) and SO (100% soybean oil), sampled at pre‐vitellogenesis, vitellogenesis and post‐vitellogenesis. The results showed that plasma gonadotropin‐releasing hormone (GnRH) levels were the highest at pre‐vitellogenesis, which promoted the secretion of gonadotropin and sex steroids. Therefore, plasma luteinizing hormone (LH) and estrogen (E₂) levels were significantly increased at post‐vitellogenesis (p < 0.05), while follicle‐stimulating hormone (FSH) levels increased at vitellogenesis (p < 0.05). The FO and FSO groups had significantly higher GnRH and E₂ levels than the other two groups (p < 0.05). In addition, plasma vitellogenin (Vtg) levels significantly increased at vitellogenesis and post‐vitellogenesis (p < 0.05), which were significantly higher in the groups of FO and FSO than SO (p < 0.05). Moreover, the expression levels of hepatic estrogen receptor α (Erα) mRNA were significantly increased at vitellogenesis and post‐vitellogenesis while ovarian Cyp19α1α mRNA were significantly increased at post‐vitellogenesis (p < 0.05), and both were the lowest in SO. Taken together, the replacement of fish oil with 66.7% soybean oil is feasible.     

壬基酚胁迫对幼龄泥鳅雌激素活性及抗氧化酶活力的影响

【目的】研究壬基酚(Nonylphenol,NP)对幼龄泥鳅的急性毒性效应、雌激素效应及抗氧化酶活力的影响。【方法】将NP设为1.50,1.78,2.12,2.52,3.00mg/L 5个质量浓度梯度,观察泥鳅在NP中暴露24,48,72,96h的死亡率,计算半致死质量浓度(LC50)和安全质量浓度(SC);根据安全质量浓度设0.125,0.150,0.188,0.250,0.375mg/L 5个NP组,将泥鳅于其中暴露15d后,取样测定泥鳅血清卵黄蛋白原(VTG)含量及肝脏超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活力。【结果】NP对幼龄泥鳅暴露24,48,72,96h的LC50分别为3.892,2.942,2.366,2.033mg/L,SC为0.504mg/L;雄性幼龄泥鳅在不同质量浓度NP中暴露15d时,血清VTG含量均极显著增加,且随着NP质量浓度增大而升高;在0.125,0.150,0.188mg/L NP中暴露15d时,幼龄泥鳅SOD和CAT活力随着NP质量浓度增大而升高,在0.188mg/L时达到最大,之后随NP质量浓度的继续增大而呈下降趋势。【结论】NP对幼龄泥鳅具有高毒性,毒性效应随NP质量浓度增大及胁迫时间延长而增大;NP对雄性幼龄泥鳅血清VTG具有显著诱导效应,且诱导效应随NP质量浓度增大而增强。     

蜜蜂卵黄原蛋白的研究进展

卵黄原蛋白是当前蜜蜂生理生化研究中最活跃的领域之一。主要介绍了卵黄原蛋白的国内外研究进展。蜜蜂作为一种进化的社会性昆虫,有其特殊的调控机制,卵黄原蛋白是其调控机制的主要因子。蜜蜂卵黄原蛋白不仅与保幼激素相互调节,而且与长寿存在一定关系。卵黄原蛋白调控着使执行巢内任务的蜜蜂转变为采集蜂,而且血淋巴中卵黄原蛋白的效价高低影响蜜蜂抗氧化能力,蜂王比工蜂的抗氧化能力强,从而蜂王寿命比一般工蜂长;越冬蜂却是例外,由于不执行哺育任务和采集行为,并且减少了外界环境的影响,越冬蜂的寿命增加;此外,卵黄原蛋白影响蜜蜂繁殖力,产卵蜂王卵黄原蛋白的效价很高,而无生殖力的工蜂卵黄原蛋白效价很低,相反产卵工蜂的卵黄原蛋白效价与老蜂王相似。     

彭泽鲫F_1、F_2代雌雄鱼VtgB和ZP2表达及卵黄蛋白原含量差异研究

雌核发育彭泽鲫后代理论上应为全雌群体,前期研究发现实验室养殖彭泽鲫F1代(相比池塘养殖)和实验室高密度养殖F2代(1.28尾/L,相比低密度0.64尾/L)组中出现了高比例的雄鱼。之前研究认为Vtg B和ZP2基因是雌性特异性表达的基因,本试验对F1、F2代雌雄鱼Vtg B和ZP2表达及卵黄蛋白原含量差异进行研究,结果发现,实验室养殖F1代雄鱼性腺中Vtg B和ZP2的表达分别极显著和显著高于雌鱼(P0.01,P0.05);池塘养殖F1代雄鱼性腺中Vtg B和ZP2的表达分别极显著高于和低于雌鱼(P0.01);F2代低密度养殖组中雄鱼性腺中ZP2的表达极显著高于雌鱼(P0.01)。实验室养殖F1代雄鱼肝胰脏中Vtg B和ZP2的表达分别极显著高于和低于雌鱼(P0.01);池塘养殖F1代雄鱼肝胰脏Vtg B和ZP2的表达均极显著低于雌鱼(P0.01);F2代雄鱼肝胰脏中Vtg B和ZP2的表达极显著高于雌鱼(P0.01)。F1代实验室养殖雄鱼全鱼卵黄蛋白原含量极显著低于雌鱼(P0.01);F1代池塘养殖雄鱼性腺、肝胰脏中卵黄蛋白原含量分别极显著高于和低于雌鱼(P0.01);F2代雄鱼性腺、肝胰脏中卵黄蛋白原含量极显著高于雌鱼(P0.01)。本研究表明,彭泽鲫Vtg B和ZP2基因并非雌性特异性表达,且不同的养殖方式、密度影响雌雄鱼Vtg B和ZP2表达及卵黄蛋白原含量。     

脊尾白虾VgR基因克隆及其在卵巢发育过程中的表达分析

为了解卵黄蛋白原受体(vitellogenin receptor,Vg R)在脊尾白虾卵巢发育中的作用,采用同源克隆和RACE技术,克隆了脊尾白虾Vg R基因全长c DNA序列,用实时荧光定量PCR方法分析了Vg R基因在雌虾不同组织、卵巢发育不同时期的表达特征。结果显示,脊尾白虾Vg R基因全长5892 bp,开放阅读框5661 bp,编码1886个氨基酸。脊尾白虾Vg R具有低密度脂蛋白受体(LDLR)家族典型结构特征,属于LDLR家族,进化上与日本沼虾等甲壳动物Vg R亲缘关系最近,然后与昆虫Vg R分支聚为一支,而与LDLR家族中其他成员亲缘关系较远。脊尾白虾Vg R在各组织中均有表达,但主要在卵巢内表达。随着卵巢的发育,卵巢Vg R表达量逐渐升高,在III期达到最大,与肝胰腺Vg表达量、血液Vg浓度变化趋势相一致;而在卵巢成熟时,卵巢Vg R表达量降到了最低,与肝胰腺Vg表达情况截然相反;排卵后的恢复期,血液中Vg浓度仍维持在较高水平,卵巢Vg R表达量又升至III期水平,同时卵巢Vg表达量也升至最高。由此可见,甲壳动物与昆虫Vg R起源于同一祖先,但在进化上已形成独立一支;脊尾白虾卵巢成熟前,卵巢主要通过Vg R介导作用摄取血液中Vg,以供卵巢快速成熟;卵巢成熟期,肝胰腺呈现补偿性合成Vg,以尽快恢复其营养储备功能;卵巢恢复期,卵巢通过Vg R介导摄入外源Vg和内源合成Vg两种途径,为卵巢二次发育提供营养物质。     

The Development of Adultoid Reproductives and Brachypterous Neotenic Reproductives From the Last Instar Nymphs in Reticulitermes labralis (Isoptera: Rhinotermitidae): A Comparative Study

Secondary reproductives develop primarily from nymphs. However, they have been rarely studied; in particular, the development of adultoid reproductives (AR) with floppy wings is still unclear. In this study, the change in juvenile hormone (JH) levels, vitellogenin gene expression, and oogenesis during the development of AR and brachypterous neotenic reproductives (BN) from the last instar nymphs of Reticulitermes labralis are investigated and compared. The results showed that the AR derived from the last instar nymphs by molting, and they were more similar to neotenic reproductives in morphology. In addition, the paired AR were not able to survive in the absence of workers. In R. labralis, the process of the last instar nymphs developing into AR and BN took an increase in JH level as a starting point. The JH level of the last instar nymphs molting into BN was approximately 1.5-fold higher than that of the AR. Additionally, The JHIII level of BN peaked on day 5, and that of AR peaked on day 10, which induced the onset of vitellogenesis in BN and AR, respectively. After molting, the vitellogenin gene expression levels of both BN and AR initially increased and then declined, and the expression levels in the BN were significantly higher than those in the AR. In addition, the oocytes of BN matured earlier than those of the AR, and the number of eggs laid by the BN was higher than the number laid by the AR. Our results demonstrate that, in R. labralis, the last instar nymphs can develop into AR, which are significantly different from BN in their development.