Development of male-incubated ovaries in the gypsy moth,Lymantria dispar

Ovaries from Lymantria dispar females were transplanted into an environment lacking vitellogenin, the male milieu, in order to determine how the presence of vitellogenin in the hemolymph affects the process of protein uptake by gypsy moth oocytes. When undeveloped ovaries from newly ecdysed last instar females were transplanted into males of the same stage, follicles detached from the germarium and increased in size, but the growth of oocytes proceeded more slowly than those from female controls. Although chorion fromation was delayed in male-grown ovaries, scanning electron microscopy of chorionated eggs recovered from adult males showed that a chorion with normal surface architecture was formed by the adult stage. SDS-PAGE analysis of the male-grown ovaries and hemolymph from males receiving ovaries showed that vitellogenin production was not stimulated by the organ transplant and only male hemolymph proteins were internalized by the male-incubated ovaries. Thus, in the absence of vitellogenin, endocytosis of male hemolymph proteins occurred, but the rate of oocyte growth was slowed.     

Patterns of haemolymph vitellogenin and ovarian vitellin in the German cockroach, and the role of Juvenile Hormone

Abstract. The concentrations of fat body and haemolymph vitellogenin and ovarian vitellin during the first gonadotropic cycle of the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae) have been studied. For these purposes, a polyclonal antibody against B. germanica vitellogenin and vitellin has been obtained, and an ELISA to quantify these proteins has been developed. Ovarian vitellin levels follow a pattern which parallels those of basal oocyte growth and Juvenile Hormone production by the corpora allata. This suggests that Juvenile Hormone regulates vitellogenin uptake into oocytes. Fat body and haemolymph vitellogenin levels give cyclic and parallel patterns. However, the cycle of Juvenile Hormone appears delayed with respect to that of vitellogenin. We suggest that the production of Juvenile Hormone, although cyclic in profile, does not modulate alone the cycle of vitellogenin. At least a supplementary mechanism, apparently independent of Juvenile Hormone, may be involved in the decline of vitellogenin production at the end of the vitellogenic cycle.     

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。     

The roles of juvenile hormone and 20-hydroxy-ecdysone during vitellogenesis in isolated abdomens of Drosophila melanogaster

Both juvenile hormone and 20-hydroxy-ecdysone seem to be involved in the regulation of vitellogenesis in Drosophila melanogaster. It is the purpose of this paper to begin to define the functions of these two hormones. Although vitellogenin synthesis does not occur at a high rate in 1-day-old female abdomens isolated from the head and thorax before 0.75 hr after eclosion, both ZR515 (a juvenile hormone analogue) and 20-hydroxy-ecdysone can cause in these preparations vitellogenin synthesis and secretion into the haemolymph. The synthesis and secretion into the haemolymph of all three vitellogenins which are detectable by electrophoresis in sodium dodecyl sulphate-containing gels of polyacrylamide is promoted by both hormones. That result excludes the hypothesis that these two hormones regulate the synthesis of different vitellogenins. A dose-response curve showed that an injection of 0.2 μl of a 10^?6 M 20-hydroxy-ecdysone solution was sufficient to promote vitellogenin synthesis and secretion in isolated abdomens. Ovaries from isolated female abdomens treated with juvenile hormone analogue showed nearly normal amounts of all three vitellogenins and morphologically normal advanced vitellogenic follicles, whereas ovaries from isolated abdomens treated with 20-hydroxy-ecdysone contained little vitellogenin and no vitellogenic follicles. We conclude that under the conditions used, juvenile hormone permits vitellogenin uptake into the oöcyte much more readily than does 20-hydroxy-ecdysone.     

Influence of a juvenile hormone analogue on vitellogenin synthesis and oögenesis in larvae of Nauphoeta cinerea

In experiments on the synthesis of the vitellogenic protein, farnesylmethylester, a juvenile hormone (JH) analogue, was injected into female Nauphoeta cinerea larvae at various stages during their development. Two and 4 days after injection, 2 μl of haemolymph were assayed in a vitellogenin immunodiffusion test. In second last and last instar larvae less than 6 days before adult ecdysis, high doses (100 μg) of farnesylmethylester are necessary to induce vitellogenin synthesis, whereas older last stage larvae and decapitated adults respond to small doses (1 μg) with the synthesis of vitellogenin. It seems that the competence to synthesize the vitellogenic protein changes at the time of induction of the moulting process. If farnesylmethylester is injected into last instar larvae with a supposedly high titre of ecdysone, the vitellogenic protein can be detected in the haemolymph of a small percentage of animals only.Oöcyte maturation can be observed in last instar larvae injected after the fifth to ninth day with farnesylmethylester. The observed volume changes of the corpora allata suggest that an absence of JH for a short time is necessary for the oöcytes to become competent to grow. Last instar larvae treated with farnesylmethylester become larval-adult intermediates with partly developed oöcytes, demonstrating a simultaneous juvenilizing and gonadotropic influence of the JH analogue. In last instar larvae injected with farnesylmethylester a partial degeneration of already maturing oöcytes is induced at the time when the ecdysone titre is supposedly high and the possible reasons for this are discussed.     

Effects of pituitary glycoprotein hormones and thyroid hormones on in-vitro vitellogenin incorporation into organ-cultured oocytes in the Japanese eel, Anguilla japonica

The objectives of the present study were to establish a long-term culture system for previtellogenic ovarian fragments of the Japanese eel (Anguilla japonica) and to identify the effects of salmon pituitary glycoprotein fraction (SPG), thyroxine (T4), and 3,5,3'-triiodothyronine (T3) on the uptake of vitellogenin (VTG) by cultured ovarian fragments evidenced by the appearance of yolk globules (YGs) within the oocytes. Yolk globules first appeared in the oocytes incubated in media containing only VTG (VTG-only group) after 9 days, whereas YGs began to accumulate in the oocytes of ovarian fragments cultured in media containing VTG+SPG (SPG group) following only 3 days of incubation. Furthermore, the occurrence of vitellogenic oocytes (%VO) and proportion of YGs within oocytes (%YG area) were significantly higher in follicles cultured in 30 ng/ml SPG throughout the culture period. No such stimulatory effects of T4 on VTG uptake were observed. Incubation of ovarian fragments with VTG and T3 (T3 group; 50 ng/ml) resulted in an increased %VO compared to follicles in the VTG group by day 9 of culture, and from day 10 onwards, both %VO and %YG area became significantly higher in follicles of the T3 group. Interestingly, SPG stimulated VTG incorporation and YG accumulation even in small oocytes (approximately 150 microm), whereas T3 showed these effects only in larger sized oocytes (> 180 microm). These results suggest that both SPG and T3 can accelerate VTG incorporation, but the mechanisms whereby this is achieved may differ between these hormone preparations.     

Haemolymph ecdysteroid levels and cellular events in the intermoult/moult sequence of Calpodes ethlius

The haemolymph ecdysteroid titre of the last larval and pupal stadia of Calpodes ethlius was determined by radioimmunoassay. During the last larval stadium, four significant ecdysteroid peaks are present, two of which have been reported for other Lepidoptera. The first peak occurs 12 hr after ecdysis and correlates temporally with nucleolar activity, RNA synthesis and organelle formation in the fat body and epidermis. It correlates also with fat body DNA synthesis, polyploidy and the initiation of a low rate of lipid synthesis. Another peak, at 78 hr, starts its increase when the prothoracic glands no longer require the influence of the brain to produce ecdysone for pupation, and marks the first critical period. It correlates with the initiation of epidermal DNA synthesis and mitosis, and with the progressive determination of pupal characteristics (change in commitment, reprogramming). This ecdysteroid peak may also be involved in the massive intermoult syntheses in the epidermis (lamellate cuticle, wax) and the fat body (lipid, protein). The largest ecdysteroid peak is seen at 162 hr, 6 hr after the tissues no longer require the prothoracic glands for pupation (second critical period). It correlates temporally with the cessation of massive synthetic activity in both epidermis and fat body and initiates preparation for pupal synthesis in both tissues. At this time the ratio of ecdysone: 20-hydroxyecdysone is ～ 1 : 6.6.In common with other Lepidoptera, a single large ecdysteroid peak occurs during the first half of the pupal stadium. Comparisons between these events and the ecdysteroid titre are made between Calpodes and other insects.     

Stress inhibits seasonal and FSH-induced ovarian recrudescence in the lizard,Mabuya carinata

Stressors (handling, chasing, and noise) applied randomly five times per day for one month to lizards during the recrudescence phase of the ovarian cycle caused a significant reduction in mean number of oocytes and primordial follicles when compared to those of controls. Further, vitellogenic follicles were absent in the ovary of lizards subjected to stressors. Administration of bovine FSH during post-breeding regression phase of the ovarian cycle induced ovarian recrudescence as shown by significant increases in the mean number of oogonia, oocytes, and primordial follicles compared to controls, as well as vitellogenic growth of follicles. However, lizards treated with FSH and exposed to stressors did not exhibit ovarian recrudescence. Furthermore, FSH administration during the post-breeding regression phase caused a significant increase in serum levels of estradiol compared to controls, which was accompanied by significant increases in the relative weight of the liver and oviduct, as well as vitellogenic growth of follicles. Despite administration of FSH to lizards subjected to stressors, there was neither any increase in serum levels of estradiol and weight of the liver nor vitellogenic growth of follicles. The results indicate that repeated application of stressors inhibits vitellogenic growth of follicles by suppression of steroidogenic activity in M. carinata. This is the first report revealing that the ovary does not respond to gonadotrophin treatment under stressful conditions in reptiles.     

亚洲玉米螟末龄幼虫促前胸腺激素与蜕皮甾类激素滴度的变化

用放射免疫分析法(Radioimmunoassay,RIA)以12小时间隔测定了亚洲玉米螟Ostrinia tfurnacalis末龄非滞育幼虫血淋巴中蜕皮甾类激素滴度.通过前胸腺体外培养,以12小时间隔测定了前胸腺体外分泌活性的变化.发现二者的变化在相同发育阶段是一致的.在亚洲玉米螟上建立了促前胸腺激素(PTTH)体外测定法,并用此法以24小时间隔测定了末龄幼虫脑和血淋巴中PTTH滴度.发现血淋巴中PTTH滴度在末龄第5和7天各有一高峰,脑中只在第5天有一高峰.     

Ecdysone 20-hydroxylation and 3-epimerization in larvae of the gypsy moth,Lymantria dispar L.: tissue distribution and developmental changes

The potential for ecdysone metabolism was determined for various larval tissues of the gypsy moth, Lymantria dispar. Homogenates of fat body, midguts, and Malpighian tubules, taken on different days during the second half of the fifth instar, were incubated with [(3)H]ecdysone, and the products were analyzed by reversed-phase and normal-phase HPLC. All tissues showed conversion to 20-hydroxyecdysone, and midguts also produced 3-epiecdysone. Ecdysone 20-monooxygenase (E20MO) activity in the fat body increased from a low level on day 5 to a peak on day 11, coinciding with the peak in the hemolymph ecdysteroid titer on the penultimate day of the instar. Midguts and Malpighian tubules showed E20MO activity only during the last 3 or 4days of the instar, with the highest activity also occurring on the penultimate day. For the midguts, the appearance of the E20MO coincided with the transition from larval to pupal tissue. No activity was detected in larval midguts. 3-Epiecdysone formation, however, was mainly found in larval midguts, with only marginal activity detectable in pupal midguts.     

Photoperiodic sensitivity and diapause induction during ovarian,embryonic and larval development of the flesh fly,Sarcophaga argyrostoma

Sensitivity to the daily photoperiod, particularly with respect to pupal diapause induction, was studied during ovarian, embryonic, and larval development of the flesh flySarcophaga argyrostoma. Large flies were shown to have a greater number of primary follicles in their ovaries and to be capable of limited ovarian maturation in the absence of exogenous protein (autogeny). Such ovarian development occurred independently of photoperiod. However, long days experienced during embryogenesis caused more rapid development, and earlier larviposition, than short days. Short days during embryonic and subsequent larval development also induced pupal diapause, whereas long days led to continuous or non-diapause development of the pupae. Pupal diapause could not be induced by photoperiods during the vitellogenic phase of ovarian development. InSarcophaga argyrostoma, a maternal effect preventing pupal diapause among the progeny of files with a diapause history was not observed.     

Interpopulation quality in gypsy moths with implications for success of two pupal parasitoids: Brachymeria intermedia (Nees) and Coccygomimus turionellae (L.)*

Abstract.

• 1 Gypsy moth egg masses were collected from innocuous, release and outbreak populations and reared in the laboratory on synthetic diet under identical conditions.
• 2 Outbreak population gypsy moths hatched sooner, were smaller and less fecund than innocuous or release gypsy moths, but had a higher concentration of total carbohydrates in their haemolymph.
• 3 Pupae from each population source were submitted to parasitization by two pupal parasitoids. Emerging B.intermedia, an established parasitoid of the gypsy moth associated with outbreak populations, were largest on outbreak source gypsy moths. C. turionellae, not a usual parasitoid of the gypsy moth, were largest when emerging from innocuous or release population gypsy moths. Implications for population dynamics of the gypsy moth are discussed.

     

The relationship between nutrition,vitellogenin, vitellin and ovarian development in the housefly, Musca domestica L.

The effect of adult nutrition on oögenesis during the first gonotropic cycle was studied in three strains of the housefly, Musca domestica. Two of the strains were anautogenous and the third was autogenous. In these strains, three subunits (51, 43 and 42 kdaltons) of vitellogenin and vitellin were electrophoretically identical using SDS-PAGE electrophoresis for haemolymph proteins of vitellogenic females and for egg extracts. Each developmental stage of the ovary in individual females flies of both autogenous and anautogenous strains fed on either sugar or protein clearly reflected the appearance of electrophoretic bands for vitellogenin and vitellin. Using immunological analysis, a very small amount of vitellogenin was detectable in the haemolymph of previtellogenic flies. The highest level of vitellogenin appeared in the haemolymph at the middle of vitellogenic phase and reached about 25% of the total haemolymph protein. There were differences in vitellogenin concentration in females with mature eggs between the two anautogenous strains: vitellogenin was not detectable in one strain, and the other showed 30% of the maximal level.     

Quantification of vitellogenesis and its control by 20-hydroxyecdysone in the ixodid tick,Amblyomma hebraeum

Ovaries of the ixodid tick, Amblyomma hebraeum Koch, grew rapidly after engorgment as a result of yolk uptake. At 26 °C, oviposition began by day 10 post-engorgement, plateaued on days 16-18, and ended by day 38. Vitellin (Vt) was partially purified from ovaries of day 10 engorged ticks by gel filtration and ion exchange chromatography. This Vt comprises seven major and several minor polypeptides. Two polypeptides (211 and 148 kD) from haemolymph of engorged female ticks corresponded to minor polypeptides of similar molecular weight in the ovary. The haemolymph titre of the 211 and 148 kD polypeptides increased up to the onset of oviposition. These polypeptides were absent in males and non-vitellogenic females (day 0 engorged or day 10 partially-fed females), and were thus designated as vitellogenin (Vg). Antibodies raised against haemolymph Vg211 and 148 recognized these polypeptides in partially purified Vt, as well as six of the seven major polypeptides. Using these antibodies we developed an indirect, competitive ELISA to quantify Vg. Rise in haemolymph Vg-concentration lagged slightly behind the rise in haemolymph ecdysteroid (ES)-concentration, and Vg-synthesis was stimulated by injections of 20E into non-vitellogenic females. These observations indicate that an ES is the vitellogenic hormone in A. hebraeum.     

Asynchrony between Host Plant and Insects-Defoliator within a Tritrophic System: The Role of Herbivore Innate Immunity

The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects’ fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon. However, the spreading of this phenomenon through the food chain, and especially those mechanisms operating this spreading, are still unclear. In this paper, we study the effect of seasonally declined leafquality (estimated in terms of phenolics and nitrogen content) on herbivore fitness, immune parameters and resistance against pathogen by using the silver birch Betula pendula—gypsy moth Lymantria dispar—nucleopolyhedrovirus as the tritrophic system. We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph. In addition, the larval susceptibility to exogenous nucleopolyhydrovirus infection as well as covert virus activation were both enhanced due to the phenological mismatch. The observed effects of phenological mismatch on insect-baculovirus interaction may partially explain the strong and fast fluctuations in the population dynamics of the gypsy moth that is often observed in the studied part of the defoliator area. This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.     

Extracellular concentrating of proteins in the cecropia moth follicle

Yolk proteins, derived from the blood, are incorporated into the oocytes of insects and certain vertebrates by pinocytosis, but reach the oocyte surface only after penetrating the surrounding follicular epithelium via intercellular channels. In an investigation of the events occurring in these intrafollicular spaces, the dense extracellular material present between the follicle cells and in the oocyte's brush border was extracted from vitellogenic cecropia moth follicles by soaking in physiological saline. Quantitative immunochemical determination of several eluted blood proteins revealed that these components had been more concentrated in the extracellular spaces than in the blood. The average concentration factors were 2.5 for the predominant yolk protein, vitellogenin, and 4.5 for the carotenoid protein. Since injected foreign proteins were also accumulated in the spaces, the concentrating mechanism seemed to act on all available proteins. However, in vitro inhibition of yolk formation with dinitrophenol resulted in a selective increase in the amount of extracellular vitellogenin in follicles which had been previously exposed to a medium low in this protein, suggesting accumulation of a factor with a specific affinity for it. Furthermore under certain conditions vitellogenin was more readily released from the concentrate than was the carotenoid protein. These results indicate that, despite apparent lack of discrimination in the binding of blood proteins in the spaces, extracellular interactions may contribute to the selectivity known to occur during vitellogenesis.     

Hemolymph juvenile hormone titers in pupal and adult stages of southwestern corn borer [Diatraea grandiosella (pyralidae)] and relationship with egg development

Juvenile hormones I, II and III were monitored in hemolymph of pupal and adult stages of various ages of Diatraea grandiosella females. JH III was the predominant homologue followed by JH II, and JH I was rarely detectable. At day 5 after pupation, no JH was detectable. JH titers increased from 7.5days after pupation to a peak of 24.8ngml(-1) JH II and 26ngml(-1) JH III at adult emergence and then declined to low levels by 24h after emergence. Ovarian development in D. grandiosella parallels changes in hemolymph JH titers, but the role of JH in vitellogenesis is unclear since the time of vitellogenesis initiation has yet to be determined. No apparent vitellogenin deposition was observed in eggs 5days after pupation. Some oocytes were partially vitellogenic by 7.5days after pupation and oocytes continued to grow afterwards, but no oocytes were chorionated during the pupal stage. Chorionated oocytes were observed in 24-h-old female moths. Juvenile hormone is essential for chorion formation in this species, because decapitated pupae treated with 10&mgr;g JH III in corn oil developed chorionated oocytes while decapitated pupae treated with corn oil did not.     

Identification,accumulation, and biosynthesis of the cuticular hydrocarbons of the southern armyworm,Spodoptera eridania (cramer) (lepidoptera: Noctuidae)

The accumulation and biosynthesis of cuticular and internal hydrocarbons in the Southern armyworm, Spodoptera eridania, were examined at closely timed intervals during larval and pupal development. Gas chromatography-mass spectrometry (GC-MS) was used to identify n-alkanes, monomethylalkanes, and dimethylalkanes ranging in chain length from 23 to 35 carbons. The amount of cuticular hydrocarbon stayed relatively constant during each stadium, while the amount of internal hydrocarbon increased dramatically during the first half of each larval stadium, presumably to replace the cuticular hydrocarbon lost on the shed cast skin with each molt. The accumulation of internal hydrocarbon was mirrored by large increases in the rate of incorporation of labeled acetate into the hydrocarbon fraction. Hydrocarbon production fell to very low rates during the latter part of the fourth and fifth larval stadia. Relatively high rates of hydrocarbon production were observed during the first and last one-third of the pupal stage and essentially all of the hydrocarbons produced during this stage remained internal. These data document large changes in the rates of hydrocarbon production during development in S. eridania and suggest that most of the hydrocarbon produced during each stage was stored internally and then transported to the cuticle of the next stage.