家蝇卵巢摄取卵黄蛋白的机理

在家蝇Ｍｕｓｃａ　ｄｏｍｅｓｔｉｃａ　ｖｉａｉｎａ的印黄发生过程中,卵母细胞摄取卵黄原蛋白与滤沟开放是相关的。观察不同发育时期的家蝇滤泡结果表明,在摄取活动最旺盛的时期也就是卵黄发生的顶盛时期,其滤泡开放程度最大,而在卵黄发生前期和后期基本上没有摄取活动,此时的滤泡上皮细胞间不开放。卵巢体外培养的激素处理表明,ＪＨ可以促进滤泡开放。家蝇卵巢微粒体制备物的Ｎａ＋－Ｋ＋ＡＴＰ酶活力在卵巢发育过程中存在着动态变化。羽化后２４小时时有一定的酶活性,随着卵黄发生的进行,酶活力逐渐增加,到现化４８小时时酶活力最高,然后又开始下降,到弱化７２小时时已经很小。羽化３２小时的家蝇点滴或注射ＪＨ之后,测得的卵巢微粒体制备物的Ｎａ＋－Ｋ＋ＡＴＰ酶活力比正常羽化３６小时的高,羽化率４４小时的家蝇点滴和注射ＪＨ之后,测得酶活力比正常羽化４８小时的低．羽化３６小时和４８小时的家蝇卵巢微粒体制备物与ＪＨ共同作用后,其Ｎａ＋－Ｋ＋ＡＴＰ酶的活力分别增加２．９５倍和３．５０倍,羽化４８小时的家蝇卵巢在含有ＪＨ的培养液中培养后,其匀浆液的酶活性为对照组的１．２６倍。由此我们可以推测在家蝇的卵黄发生过程中,ＪＨ通过促进滤泡开放和增加卵巢微粒体制     

家蝇卵巢中保幼激素结合蛋白的研究(英语)

本文运用活性炭结合试验测定了家蝇卵巢中保幼激素结合蛋白(JHBP)的含量.卵巢中JHBP对JHⅢ有较高的结合活性,其结合常数为2.1×10~(-8)M,~3H保幼激素Ⅲ(~3H-JH)和JHBP的结合可被未标记的JH Ⅲ抑制,但保幼激素的类似物ZR 512或ZR515均无抑制效应.卵巢中JHBP的含量在家蝇羽化后48小时达最大值,是羽化后60小时、72小时家蝇卵巢中JHBP含量的6.5倍和15.5倍.羽化后24小时、36小时的家蝇卵巢无JHBP的结合活性.若刚羽化的家蝇用JHⅢ处理,36小时后,JHBP则可检测到.本实验的结果表明卵巢中JHBP浓度的变动可能和JH对家蝇卵黄发生的作用有关.     

家蝇的卵黄发生及其激素调节

用5—15%SDS-PAGE分析表明,家蝇Musce domestica viaina卵黄蛋白由三个亚基组成,其亚基分子量分别为58KD、50KD、48KD.火箭免疫电泳的结果表明,脂肪体、血淋巴和卵巢内卵黄原蛋白的变化具有密切的相关性,卵黄原蛋白在体内最早出现在羽化后30小时左右,然后迅速增加,在羽化后48小时,脂肪体和血淋巴中卵黄原蛋白含量达到最大值,卵巢开始沉积卵黄蛋白在羽化后30小时,到产卵前达到最大值,脂肪体在离体培养条件下,通过测定³H-亮氨酸掺入卵黄原蛋白的量,对不同发育时期家蝇脂肪体合成卵黄原蛋白的能力及激素的调节作用进行了研究,结果表明,羽化12小时后,合成能力迅速上升,48小时时形成高峰,60小时后迅速下跌直至产卵,其合成能力一直维持在低水平,产卵后合成能力又迅速回升,激素处理结果表明,保幼激素可以促进卵黄发生前期和后期家蝇脂肪体的卵黄原蛋白合成,20-羟基蜕皮酮可以大幅度促进卵黄发生期家蝇脂肪体的卵黄原蛋白合成.当二种激素共同处理时,对卵黄发生前期和卵黄发生期的家蝇脂肪体有协同促进作用,而对卵黄发生后期的脂肪体没有这种作用.本文还对家蝇卵黄发生过程中脂肪体、血淋巴和卵巢三者之间的关系及家蝇卵黄发生的激素调节进行了讨论.     

早熟素II对家蝇卵黄发生的影响

本实验通过卵巢发育分级的解剖观察、可溶性蛋白质和核酸的定量测定、火箭免疫电泳定量测定卵黄原蛋白及激素处理等方法,研究了早熟素对家蝇(Muscadomestica vicina)卵黄发生的影响。试验结果表明用20ug早熟素处理每头刚羽化家蝇时,家蝇卵黄发生处于不完全抑制状态,其卵黄发生过程比对照组“延迟”约12小时。处理后48小时,血淋巴中卵黄原蛋白的滴度为lo.5ug/ul,接近对照组,而其卵巢鲜重和发育等级明显低于对照组,这种不完全抑制状态表明卵母细胞对卵黄原蛋白的吸收作用受到抑制。当用高剂量100ug早熟素11处理每头刚羽化家蝇时,血淋巴中卵黄原蛋白滴度、卵巢鲜重及其发育均受到明显的抑制,这种抑制效应能自然恢复。 当早熟素11和保幼激素(JH-III)、20-羟基蜕皮酮共同处理时,保幼激素具有明显的去抑制作用,可使血淋巴中卵黄蛋白浓度成倍增加,20-羟基蜕皮酮的去抑制效应不明显。本文还对早熟素作用于双翅目昆虫的方式作了讨论。     

昆虫卵母细胞对卵黄物质的摄取过程

昆虫卵母细胞如何摄取卵黄物质是卵黄发生研究中的关键问题之一,摄取作用具有高度的选择性和种属特异性。滤泡通过滤泡开放作用使Vg积聚在卵母细胞表面,保幼激素作用于Na~+/K~+ATP酶而调节滤泡开放,其摄取作用的分子机理在于卵母细胞膜上有Vg特异受体,Vg分子通过受体调节的内吞作用进入卵母细胞,并积累形成卵黄球。     

家蝇卵巢在体外培育中摄取卵黄蛋白

本文报道家蝇Musca domestica卵巢在体外培养条件下,摄取异硫氰萤光素标记的家蝇卵黄蛋白的特点。用Grace's培养液标记蛋白浓度为2mg/m1,在27℃条件下培养2小时,卵巢摄取量依赖于培养液中卵黄蛋白浓度和温度,摄取高峰在羽化后48小时,正值卵母细胞发育阶段进入6-8时期。培养液中加入JHIII,能促进摄取,JHIIl的浓度和摄取量无明显相关性。乌本苷、牛血清蛋白和叠氮钠显著抑制卵巢的摄取活动。     

抑卵激素对家蝇卵巢周期性发育的调控

抑卵激素是调控家蝇Musca dorncstica vicina卵巢周期性发育的关键因子之一。在家蝇中,当第一个周期的卵母细胞处于卵黄发生期或卵黄发生后期时,其第二个周期的卵母细胞的发育不进入卵黄发生期。本文建立了家蝇抑卵激素的生物测定方法,即用一对卵巢提取物注射1头羽化后12h家蝇,并在羽化后60h观察卵母细胞的发育及卵黄蛋白的沉积情况。抑卵激素的作用首先是延缓了卵母细胞在卵黄发生前期的发育;其次,抑卵激素抑制脂肪体中卵黄蛋白的合成,导致血淋巴中卵黄蛋白含量的下降,从而抑制了卵母细胞的发育。抑卵激素并不抑制卵母细胞对卵黄原蛋白的摄取。卵发育神经激素可以颉抗抑卵激素的抑制作用。抑卵激素无种属特异性。     

营养制剂对间歇性寒冷暴露大鼠子宫、卵巢内HPO轴功能及能量代谢的影响*

目的: 观察一种自行设计的营养制剂对间歇性寒冷暴露SD雌性大鼠下丘脑-垂体-卵巢轴(HPO轴)功能及能量代谢的影响。 方法: 将雌性SD大鼠分为对照组、寒冷暴露组、营养制剂组,每组11只。对照组、寒冷暴露组每日灌胃蒸馏水,营养制剂组每日灌胃营养制剂,灌胃后寒冷暴露组、营养制剂组每日于-10℃冷舱内暴露4 h,持续14 d后,取血清、子宫、卵巢,采用酶联免疫吸附(ELISA)法测定血清卵泡刺激素(FSH)、黄体生成素(LH)等激素指标,采用比色法等检测ATP酶等能量代谢相关指标。 结果: 与对照组相比,寒冷暴露显著上调大鼠卵巢中FSHR、LHR蛋白表达,增强子宫和卵巢Na⁺-K⁺-ATP酶、Ca²⁺-Mg²⁺-ATP酶活性(P<0.05);与寒冷暴露组相比,营养制剂能够下调低氧暴露大鼠卵巢FSHR、LHR蛋白的表达,抑制卵巢和子宫中Na⁺-K⁺-ATP酶、Ca²⁺-Mg²⁺-ATP酶的活性(P<0.05)。 结论: 营养制剂可以有效改善间歇性寒冷暴露对子宫、卵巢内HPO轴相关受体表达和能量代谢的影响。     

家蝇对拟除虫菊酯农药的抗性机制

本文对二氯苯醚菊酯和溴氰菊酯分别选择的高抗性家蝇(Musca domestica vicina)品系2Cl-R及Dec-R的抗性机制进行了研究.应用生物测定、增效剂,体内试验的表皮穿透作用、离体条件的解毒酶系活性的增加以及家蝇头部ATP酶活力的研究结果表明,两种拟除虫菊酯高抗性家蝇品系的表皮穿透性均比正常品系NP为慢,特别是Dec-R品系极慢.酯酶和多功能氧化酶及其末端的细胞色素P-450的活性在两个抗性品系中都比NP品系有不同程度的增高,但2Cl-R品系以氧化酶为主,而Dec-R品系似以酯酶占优势.Dec-R品系的Na⁺—K⁺-ATP酶活力低于NP品系的46%,而2Cl-R品系与NP品系相等.Mg²⁺-ATP酶活性在两个抗性品系中均高于正常品系.Mg²⁺-ATP酶可能也是拟除虫菊酯的一个重要靶标部位.     

七星瓢虫雌成虫卵巢发育不同阶段体内保幼激素的含量

本文以大蜡螟Galleria mellonella(L.)为生测昆虫,应用蜡测定法(Wax test)测定了取食天然食物及人工饲料的七星瓢虫雌成虫在不同卵巢发育阶段体内保幼激素(JH)的含量。取食蚜虫者羽化后8日左右(卵巢管内出现第三卵母细胞,卵黄大量沉积即将排卵),雅虫JH含量达到高峰(593.3G.U.),但一经开始排卵(羽化后约10日左右)保幼激素的含量猛然下降。直至持续产卵达10次的雌虫(羽化后约25日)JH含量仍保持在比较平稳的状态。取食人工饲料者卵巢发育缓慢,羽化30日后不产卵个体的JH水平仍很低,仅及取食蚜虫组高峰的1/6。这一结果证实了JH对七星瓢虫雌成虫卵巢发育及排卵的调控,也指出了取食人工饲料的雌虫产卵率及产卵量明显偏低的重要原因。 在应用蜡测法的过程中肯定了JH浓度与大蜡螟蛾中胸背板保持的部分蛹皮面积之部的关系。     

Ecdysteroids regulate yolk protein uptake by Drosophila melanogaster oocytes

Juvenile hormones (JHs) are thought to drive the regulation of yolk protein uptake by ovaries in Drosophila melanogaster. However, the level of JH production in a mutant stock (ap(56f)) is depressed yet the flies are normally vitellogenic. The production of ecdysteroids by these ap(56f) ovaries in vitro is elevated above that of wild-type ovaries. The incubation of wild-type ovaries in the presence of 0.1mM JHB(3) increased ecdysteroid biosynthesis only during the first 18h following eclosion. Female Drosophila melanogaster undergo a pre-vitellogenic reproductive diapause when exposed to low temperature (11 degrees C) and a short-day photoperiod (L12:D12). The rate of ecdysteroid synthesis by the ovaries, but not JH production, increased within 12h of a temperature upshift to 25 degrees C from a basal level of 20+/-1pg/10 pair of ovaries/5h to a sustained level of 150+/-20pg/10 pair/5h. Vitellogenic oocytes were noted in all females within 12h of this temperature upshift. Diapause was also terminated by the injection of 1&mgr;g of 20-hydroxyecdysone into the abdomens of diapausing females as determined by an increase in ovary size, and the appearance of vitellogenic oocytes as compared to controls. These results are consistent with a revised model for the regulation of yolk protein uptake by ovaries in which ecdysteroids, and not JHs, play the prominent role.     

Ecdysteroids and oocyte development in the black fly <Emphasis Type="Italic">Simulium vittatum</Emphasis>

Background

Oocyte development was studied in the autogenous black fly, Simulium vittatum (Diptera, Nematocera), a vector of Onchocerca volvulus, the causative agent of onchocerciasis.

Results

Oocyte growth was nearly linear between adult eclosion and was complete by 72 hours at 21°C. The oocyte became opaque at 14 hours after eclosion indicating the initiation of protein yolk deposition. The accumulation of vitellogenin was measured using SDS-PAGE. The density of the yolk protein bands at about 200 and 65 kDa increased during the first and second days after eclosion. The amount of protein in the 200 kDa band of vitellogenin, determined using densitometry, rapidly increased between 12 and 25 hours after eclosion. Ecdysteroid levels were measured using a competitive ELISA. Ecdysteroid levels increased rapidly and subsequently declined during the first day after eclosion.

Conclusion

These data show a correlation between the appearance of vitellogenin in the oocyte, and the rise in ecdysteroids. A possible relationship to molting of the nematode, Onchocerca volvulus, is discussed.

     

Regulation of vitellogenesis in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Studies were undertaken to investigate vitellogenesis and its regulation in female adults of the fall armyworm, Spodoptera frugiperda. A single female-specific protein, likely to be the S. frugiperda vitellogenin (Vg), appeared approximately 5 h after adult eclosion in the hemolymph of virgin females. The concentration of the protein increased with age as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed. A protein with the same relative molecular mass was also present in egg extracts, but absent from hemolymph samples from male moths. The relative molecular mass of the designated S. frugiperda Vg was determined as 164.5+/-2.5 kDa. Vitellogenic oocytes became visible 36-48 h after emergence and egg deposition began on day 3 of adult life. Vg could not be detected in the hemolymph of females decapitated directly after eclosion. When decapitated virgin females were injected with the JH-mimic methoprene (MP), the level of Vg was comparable to that in non-decapitated moths, indicating that vitellogenesis in S. frugiperda depends on juvenile hormone (JH). However, the number of vitellogenic oocytes was somewhat lower than in non-decapitated virgin females. Injection of 20-hydroxyecdysone (20E) promoted Vg production to a similar extent in decapitated female moths, but in contrast to methoprene injection, treatment with 20E never resulted in the production of vitellogenic oocytes. In vitro cultivated ovaries of adult females dissected directly after eclosion produced lower amounts of ecdysteroids than those isolated on day 1 after emergence. Our results suggest a crucial role for 20E in the induction of vitellogenesis in the noctuid S. frugiperda, while JH seems to be essential for the continued uptake of Vg by developing oocytes and may trigger 20E biosynthesis in the ovary.     

Nonvitellogenic female sterile mutants and the regulation of vitellogenesis in Drosophila melanogaster.

The genetic and endocrine regulation of vitellogenesis was investigated by studying 18 female sterile mutations that disrupt the development of normal vitellogenic follicles. Applications of exogenous juvenile hormone analog and reciprocal ovarian transplants between flies of different genotypes were employed to accomplish our first two objectives: to find (1) whether the mutation blocked development of the ovary directly, and (2) whether the mutation altered the hormonal milieu. In 15 of the mutants the developmental defect was localized to the ovary, but in the other 3 the ovary was competent to respond to a permissive environment. The internal milieu of these three mutants (ap⁴, fs(3)A1, fs(2)A18) was unable to provoke normal development in wild-type ovaries, suggesting that these mutations cause endocrine defects. Our third objective was to find whether an endocrine organ was itself defective in any of these mutants. The corpus allatum from two of the mutants was unable to provoke vitellogenesis in isolated wild-type abdomens, but corpora allata from wild-type females or from other mutants were able to promote maturation of ovarian follicles in isolated abdomens. Our fourth objective was to find whether any of the mutants were able to produce yolk proteins. Immunoelectrophoresis of fly hemolymph demonstrated that in all mutants tested vitellogenins were found in the blood. These experiments permit four main conclusions. First, they identify the first Drosophila mutants in which an endocrine gland is shown to be intrinsically defective during adulthood. Second, they show that the production of morphologically normal late previtellogenic follicles is not required for the induction of vitellogenin synthesis and secretion. Third, they show that juvenile hormone can cause ovarian follicles to sequester yolk in mutant flies. And finally, they show that mutants with defective corpora allata still synthesize and secrete vitellogenin. Taken together, these conclusions suggest that in Drosophila melanogaster the uptake of vitellogenin into follicles depends upon the availability of juvenile hormone, but that the synthesis and secretion of vitellogenin are independent of both normal ovaries and totally normal corpora allata.     

Juvenile Hormone titre and vitellogenin gene expression related to ovarian development in primary reproductives compared with nymphs and nymphoid reproductives of the termite Reticulitermes speratus

To elucidate the reproductive cycle of termite queens, incipient colonies of Reticulitemes speratus (Isoptera: Rhinotermitidae) are established under laboratory conditions, and the transition of colony development is observed at 0.5, 1.5, 2.5, 3.5, and 7.5 months (stages I–V, respectively) after colony foundation. Ovarian development, vitellogenin gene expression and Juvenile Hormone (JH) titres are examined in the queens and in nonphysogastric nymphoids collected from natural colonies. A reproductive cycle in queens is observed, in which the oviposition rate is relatively higher during stages I and II, and then decreases during stages III and IV. Vitellogenic oocytes are not observed in the ovaries during stages III and IV, and the expression level of the vitellogenin gene is low, suggesting that egg production in queens is repressed during these stages. However, vitellogenin gene expression and egg deposition in queens resumes during stage V. Juvenile Hormone levels rise during the transition from nymphs to stage I queens, and elevated JH titres are observed also during stages III and IV. The decrease in JH titre in queens at stage II precedes the decline in vitellogenesis at stages III and IV. Thus, JH titre and vitellogenesis are correlated in an offset pattern. However, nonphysogastric nymphoid reproductives do not have vitellogenic oocytes in their ovaries, and their JH titre is two‐fold higher than that of queens, suggesting that elevated JH titre precedes vitellogenesis, as in queens.