Methyl palmitate: a novel product of the Medfly (Ceratitis capitata) corpus allatum

The corpus allatum (CA) of adult female Ceratitis capitata produces methyl palmitate (MP) in vitro, in addition to JHB₃ and JH III. Biosynthesized MP migrates on TLC and co-elutes from RP-18 HPLC with synthetic MP. Its identity is verified herein by GCMS. MP production is up-regulated twofold by mevastatin, an inhibitor of mevalonic acid-dependent isoprene biosynthesis. Fosmidomycin, an inhibitor of mevalonic acid-independent isoprene synthesis in graminaceous plants, up-regulates MP synthesis by about fourfold. However, it does not depress JHB₃ biosynthesis concurrently. This suggests that the initial enzyme(s) in the conversion of 1-deoxy-xylulose 5-phosphate to isoprene is presumably present in C. capitata, but is inhibited by fosmidomycin, and this inhibition diverts precursors to MP synthesis. Phytol, an acyclic diterpene, might be suppressing isoprene biosynthesis by CA, thereby resulting in a fourfold increase in the MP biosynthesis. Linolenic acid is an end-product and its presence in incubation media up-regulates MP biosynthesis by twofold, presumably due to the feedback diversion to biosynthesis of C_16:0 and its methyl ester. Biosynthesis of MP is markedly depressed after mating, while otherwise maintained at significantly higher levels in virgin females. MP biosynthesis is significantly reduced in virgin females by direct axonal control but is less consistent after mating.  

Presence and titer of methyl palmitate in the Medfly (Ceratitis capitata) during reproductive maturation

The relative amounts of methyl palmitate (MP) during the first 10 days post-eclosion were determined in whole-body extracts of adult female Ceratitis capitata by SIM monitoring of the 74 m/z fragment. MP peaks in receptive 3-day-old virgin females coincide with previously reported production of Juvenile Hormone (JH) by the corpus allatum (CA). Mating in the Medfly induces female non-receptivity. Indirect evidence suggests that the mevalonate pathway to sesquiterpene biosynthesis is underdeveloped in newly eclosed females. We propose that the pathway leading to synthesis of JH is markedly diverted in non-receptive virgin females to fatty acid synthesis, and partly so-in non-receptive mated females, leading to production of palmitic acid, presumably methylated thereafter. MP is depressed and remains marginal thereafter for the 7 days examined in the virgin female but goes through an apparent second cycle in the mated female. This contrasts with the consistent increase of allatal biosynthesis of MP of virgin and mated females previously reported and suggests additional control mechanisms in vivo. During the period of reduced receptivity following the first mating a second apparent peak of MP is observed. MP is a metabolic default metabolite of reproductively immature females whose putative role in reproductive physiology remains to be defined.  

Methyl palmitate: a novel product of the Medfly (Ceratitis capitata) corpus allatum

The corpus allatum (CA) of adult female Ceratitis capitata produces methyl palmitate (MP) in vitro, in addition to JHB₃ and JH III. Biosynthesized MP migrates on TLC and co-elutes from RP-18 HPLC with synthetic MP. Its identity is verified herein by GCMS. MP production is up-regulated twofold by mevastatin, an inhibitor of mevalonic acid-dependent isoprene biosynthesis. Fosmidomycin, an inhibitor of mevalonic acid-independent isoprene synthesis in graminaceous plants, up-regulates MP synthesis by about fourfold. However, it does not depress JHB₃ biosynthesis concurrently. This suggests that the initial enzyme(s) in the conversion of 1-deoxy-xylulose 5-phosphate to isoprene is presumably present in C. capitata, but is inhibited by fosmidomycin, and this inhibition diverts precursors to MP synthesis. Phytol, an acyclic diterpene, might be suppressing isoprene biosynthesis by CA, thereby resulting in a fourfold increase in the MP biosynthesis. Linolenic acid is an end-product and its presence in incubation media up-regulates MP biosynthesis by twofold, presumably due to the feedback diversion to biosynthesis of C_16:0 and its methyl ester. Biosynthesis of MP is markedly depressed after mating, while otherwise maintained at significantly higher levels in virgin females. MP biosynthesis is significantly reduced in virgin females by direct axonal control but is less consistent after mating.  

Electroantennogram responses of Zabrotes subfasciatus to odours of the sexual partner

Odours of female Zabrotes subfasciatus Boh, elicit strong electroantennogram (EAG) responses in their sexual partners. Virgin female insects used in experiments were of different ages and given seeds, or not, of the host plant, Phaseolus vulgaris L. The odours of females which did not get host plant seeds, do not elicit EAG responses in virgin males, until they are at least 6 days old. On the other hand, the release of the sex pheromone as perceived by the male antennae, occurs earlier in the life of females when they are in contact with the host plant's seeds. This suggests that the sexual attractiveness of the females of this specialist insect is probably closely correlated with vitellogenesis. The latter is indeed highly dependent on host plant stimulation.Résumé Des EAG sont enregistrés chez les mâles de Zabrotes subfasciatus en réponse à l'odeur du partenaire sexuel. Les insectes femelles, utilisés dans les expériences sont d'âges différents, vierges et mis en présence ou non de graines de la plante-hôte, Phaseolus vulgaris. Les odeurs des femelles vierges mises en absence des graines n'évoquent pas de réponses électroantennographiques chez les mâles vierges — tout au moins tant qu'elles n'ont pas atteint un âge relativement avancé (6 jours environ). Par contre, le contact avec les graines de la plante-hôte favorise une émission plus précoce de la phéromone sexuelle perçue par les antennes des mâles. Ceci nous fait supposer que l'attractivité sexuelle des femelles est probablement corrélée à la vitellogenèse, elle-même très dépendante de la stimulation par la plante-hôte chez cet insecte spécialiste.  

Kisspeptins/GPR54神经内分泌系统对哺乳动物生殖活动的调控

哺乳动物的生殖活动受到神经内分泌系统的精确调控。近年来的研究表明,KISS-1基因的表达产物Kisspeptins及其G蛋白偶联受体（G protein coupled receptor 54,GPR54）在这一调控网络中发挥着重要作用,与哺乳动物青春期启动、发情排卵及季节性繁殖等过程密切相关。该文就近年来Kisspeptins/GPR54系统对哺乳动物生殖活动调控的研究进展进行简述。  

Alternative dynamical states in stage-structured consumer populations

The population dynamics of a consumer population with an internal structure is investigated. The population is divided into juvenile and adult individuals that consume different resources and do not interfere with each other. Over a broad range of external conditions (varying mortality and different resource levels), alternative stable states exist. These population states correspond to domination of juveniles and domination of adults, respectively. When mortality is varied, hysteresis between the alternative states only occurs if juveniles have more resources than adults. In the opposite case the juvenile-dominated state is stable for all values of mortality, but the adult-dominated state is not. When the population is modelled with more than one juvenile stage, the adult-dominated state becomes a periodic orbit due to a delay in the regulatory mechanism of the population dynamics. It is shown numerically that the stage-structured model converges to a model with continuous size structure for very large numbers of successive juvenile stages.  

昆虫卵黄原蛋白受体(VgRs)及其主要功能综述

卵黄原蛋白受体(VgRs)属于低密度脂蛋白受体家族成员,具有该家族典型的保守结构域,包括配体结合域,表皮生长因子前体同源域,跨膜域,0-联糖功能域,以及胞质尾域.昆虫VgRs通常具有卵巢特异性,是卵黄原蛋白Vg的专一性胞吞作用受体,可介导Vg进入昆虫卵母细胞,而后沉淀积累形成昆虫生殖必须的卵黄蛋白YP.VgRs介导的胞吞作用是一个动态循环过程,它是卵黄发生的基础,对昆虫卵母细胞发育起着至关重要的作用.近年来的研究表明,VgRs不仅与卵巢激活、卵黄发生与卵子形成密切相关,而且在昆虫信息交流、社会分化、行为构建以及免疫调控等中也起到了至关重要的作用,已成为潜在的害虫控制新靶标.本文首次对昆虫VgRs基因的序列信息,分子结构,系统进化,表达模式以及调控功能等方面进行了综述,旨在为了解VgRs基因的研究进展及前景提供参考,对进一步改进害虫生态控制的策略和措施也具有指导意义.  

笼养狗獾东北亚种繁殖规律

2013年3 ~ 10月，使用红外监控设备对哈尔滨市松北区某狗獾养殖场的24只笼养东北亚种狗獾 （Meles meles amurensis）的繁殖行为进行全天候观察记录。狗獾3月末至5月初交配，翌年3月末至4月初产仔，妊娠期长达11 ~ 12个月。而以往国内文献报道狗獾交配时间主要分布于7 ~ 8月，这种交配时间的变化表明其延迟着床的时间可能也存在较大变化。对交配期内全天各时段交配频次的观察发现，交配可在全天任一时间段发生，昼、夜差异不大。交配时长10 ~ 110 min，多数交配的时长为60 ~ 80 min。观察还发现，狗獾交配期内交配频次和时长具有明显的周期性变化。