菜蛾盘绒茧蜂多分DNA病毒的特性及其对小菜蛾幼虫的生理效应

对菜蛾盘绒茧蜂Cotesia plutellae多分DNA病毒的特性及其对寄主小菜蛾Plutella xylostella幼虫的生理效应进行了研究。结果表明：菜蛾盘绒茧蜂雌蜂输卵管萼中含有大量的多分DNA病毒（polydnavirus, PDV）;一个PDV内含多个核衣壳,最多可达16个;核衣壳长40～168 nm,直径39～40 nm;PDV仅在输卵管萼细胞内复制;雌蜂产卵时,随蜂卵将PDV注入寄主血腔,并扩散到寄主的许多组织中;PDV可能先通过脱膜再侵染寄主组织。雌蜂经Co⁶⁰辐射处理后再寄生（即假寄生）小菜蛾2龄、3龄和4龄初期的幼虫,被寄生后的寄主幼虫几乎全部不能化蛹,但末龄（即4龄）幼虫期显著延长,并在寄生后期,幼虫胸部有褐色的短翅芽出现;即将化蛹的4龄末小菜蛾幼虫被假寄生后,即使每头寄主被过寄生9次,依然能正常化蛹,但不能羽化。假寄生与正常寄生后寄主的脂肪体数量和形态结构有明显的不同,推测在正常寄生的情况下蜂卵孵化时释放的畸形细胞及随后的幼蜂可能对脂肪体的结构产生了作用。     

Evidence for a chromosomal location of polydnavirus DNA in the ichneumonid parasitoid Hyposoter fugitivus.

Evidence is presented in support of a chromosomal location for sequences homologous to polydnavirus DNA in the ichneumonid parasitoid Hyposoter fugitivus. In this study, four different viral genome segments were cloned and used as probes against genomic DNA extracted from male parasitoids and digested with a variety of restriction enzymes. Each probe typically identified a single off-size fragment (OSF) in the case of enzymes not cutting viral genome segments, while two OSFs were generated by enzymes cutting at one and two sites. While extra OSFs were occasionally observed, these were invariably found to be due to the presence of polymorphic restriction sites in flanking chromosomal DNA. Analysis of these data suggests that a single, stable chromosomal locus exists for sequences homologous to each viral genome segment; the data also indicate that viral and cognate parasitoid genomic DNAs are largely if not entirely colinear.     

Energy status in the fat body of Trichoplusia ni parasitized by the insect parasite Hyposoter exiguae

The levels of adenylate nucleotides were examined in 4th-instar Trichoplusia ni larvae 3 days after parasitization by the insect parasite Hyposoter exiguae. In general, parasitization caused a decrease in the level of ATP and increased ADP and AMP levels. These changes resulted in alteration of the adenylate kinase mass-action ratio. The overall energy status of parasitized larvae, however, as indicated by energy ratios, including the “energy charge,” was affected only slightly. The result demonstrates that the host maintained an active and viable metabolic state despite extensive alterations in physiology which occur at this stage of the parasite-host association.     

Influence of dietary nicotine on the fall armyworm, Spodoptera frugiperda and its parasitoid, the ichneumonid wasp Hyposoter annulipes

Experiments were conducted to determine the influence of nicotine (at a range of concentrations) in the food of an herbivorous host on the development, size and survival of its parasitoid. Fall armyworms, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) were reared on diets of 0, 0.025, 0.050 and 0.075% nicotine and exposed to parasitism by Hyposoter annulipes (Hymenoptera: Ichneumonidae). As nicotine concentration increased parasitoid mortality and development time increased and adult weight decreased. Development time, pupal weight and survival were recorded for unparasitized armyworms. Unparasitized fall armyworms showed lengthened development and higher mortality but pupal weights were greatest at intermediate nicotine concentrations.

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Résumé Des quantités croissantes de nicotine dans l'alimentation ont prolongé la durée du développement des chenilles saines, bien que l'effet ait chuté aux concentrations les plus élevées. Le sexe de la noctuelle n'a pas eu d'effet sur la durée du développement ou l'action de la nicotine. L'influence de la nicotine sur le poids des chrysalides est inhabituel, en ce sens que les chrysalides les plus lourdes ont été obtenues aux concentrations moyennes. Des hypothèses sont proposés sur l'origine de ce phénomène. La mortalité et la durée de développement de H. annulipes ont augmenté et le poids des adultes a diminué quand la concentration de l'aliment de l'hôte en nicotine s'est élevée. L'effet différente de la nicotine sur des générations successives a pu provenir de modifications de la toxicité de la nicotine en fonction de changements dans la qualité de l'aliment. Quoi qu'il en soit, l'augmentation de la concentration de la nicotine dans l'alimentation de l'hôte a eu un effet négatif cohérent sur la valeur adaptative de H. annulipes.

     

Nuclear secretory particles associated with the calyx cells of the ichneumonid parasitoid Campoletis sonorensis (Cameron)

Summary The present study is an ultrastructural investigation of the calyx region of the ichneumonid endoparasitoid Campoletis sonorensis. It appears that synthesis of electrondense secretory particles occurs within nuclei of calyx cells. The particles consist of an ovocylindrical electron-dense inner core and a surrounding unit membrane. After their formation the particles pass from the nucleus by budding through both membranes of the nuclear envelope. The particles, along with fully developed parasitoid eggs concentrate within the lateral oviduct lumen. Feulgen histochemical studies suggest the presence of DNA within the calyx fluid. The possible function of the particles is discussed.Approved for publication as TA 11744 by the Director, Texas Agricultural Experiment Station. Conducted in cooperation with the USDA and supported in part by Cotton, Inc. Grant CI—199 with funds made available through the USDA. Appreciation is also expressed to Sigma Xi for its contribution of funds during this study.     

Survey of medical training in cytopathology carried out by the journal Cytopathology

Anshu, A. Herbert, B. Cochand‐Priollet, P. Cross, M. Desai, R. Dina, J. Duskova, A. Evered, A. Farnsworth, W. Gray, S. S. Gupta, K. Kapila, I. Kardum‐Skelin, V. Kloboves‐Prevodnik, T. K. Kobayashi, H. Koutselini, W. Olszewski, B. Onal, M. B. Pitman, ?. Marin?ek, T. Sauer, U. Schenck, F. Schmitt, I. Shabalova, J. H. F. Smith, E. Tani, L. Vass, P. Vielh and H. Wiener
Survey of medical training in cytopathology carried out by the journal Cytopathology This report of the Editorial Advisory Board of Cytopathology gives the results of a survey of medical practitioners in cytopathology, which aimed to find out their views on the current situation in undergraduate and postgraduate training in their institutions and countries. The results show that training in cytopathology and histopathology are largely carried out at postgraduate level and tend to be organized nationally rather than locally. Histopathology was regarded as essential for training in cytopathology by 89.5% of respondents and was mandatory according to 83.1%. Mandatory cytopathology sections of histopathology were reported by 67.3% and specific examinations in cytopathology by 55.4%. The main deficiencies in training were due to its variability; there were insufficient numbers of pathologists interested in cytology and a consequent lack of training to a high level of competence. Pathologists without specific training in cytopathology signed out cytology reports according to 54.7% of responses, more often in centres where training was 3–6 months or less duration. Although 92.2% of respondents thought that specialist cytology should not be reported by pathologists without experience in general cytopathology, that practice was reported by 30.9%, more often in centres with small workloads. The survey report recommends that 6–12 months should be dedicated to cytopathology during histopathology training, with optional additional training for those wanting to carry out independent practice in cytopathology. Formal accreditation should be mandatory for independent practice in cytopathology. When necessary, temporary placements to centres of good practice should be available for trainees intending to practise independently in cytopathology. There should be adequate numbers of pathologists trained in cytopathology to a high level of competence; some of their time could be released by training cytotechnologists and trainee pathologists to prescreen cytology slides and assess adequacy of fine‐needle aspiration samples when immediate diagnosis was not required. The survey demonstrated a clear need for European and international guidelines for training in cytopathology.     

Characterization of microsatellite loci in two primary parasitoids of the butterfly Melitaea cinxia,Cotesia melitaearum and Hyposoter horticola (Hymenoptera)

Five polymorphic microsatellite loci were isolated from Cotesia melitaearum (Wilkinson) and three from Hyposoter horticola (Gravenhost). Both of these parasitic Hymenoptera use the butterfly Melitaea cinxia (Linnaeus) exclusively as their host in the Åland islands in SW Finland. Allelic diversity and heterozygosity were quantified in samples from the Åland islands and other localities around Europe. In addition, microsatellite loci for C. melitaearum were tested in five other Cotesia species: C. acuminata (Reinhard), C. bignellii (Marshall), C. congregata (Say), C. cynthiae (Nixon) and C. koebelei (Riley) from several different host species in Europe and Asia.     

Functional endogenous viral elements in the genome of the parasitoid wasp Cotesia congregata: insights into the evolutionary dynamics of bracoviruses

Bracoviruses represent the most complex endogenous viral elements (EVEs) described to date. Nudiviral genes have been hosted within parasitoid wasp genomes since approximately 100 Ma. They play a crucial role in the wasp life cycle as they produce bracovirus particles, which are injected into parasitized lepidopteran hosts during wasp oviposition. Bracovirus particles encapsidate multiple dsDNA circles encoding virulence genes. Their expression in parasitized caterpillars is essential for wasp parasitism success. Here, we report on the genomic organization of the proviral segments (i.e. master sequences used to produce the encapsidated dsDNA circles) present in the Cotesia congregata parasitoid wasp genome. The provirus is composed of a macrolocus, comprising two-thirds of the proviral segments and of seven dispersed loci, each containing one to three segments. Comparative genomic analyses with closely related species gave insights into the evolutionary dynamics of bracovirus genomes. Conserved synteny in the different wasp genomes showed the orthology of the proviral macrolocus across different species. The nudiviral gene odv-e66-like1 is conserved within the macrolocus, suggesting an ancient co-localization of the nudiviral genome and bracovirus proviral segments. By contrast, the evolution of proviral segments within the macrolocus has involved a series of lineage-specific duplications.     

菜蛾盘绒茧蜂卵携带的免疫抑制因子

抑制寄主昆虫的免疫反应是内寄生蜂存活的关键。菜蛾盘绒茧蜂Cotesia vestalis（Haliday）寄生小菜蛾Plutella xylostella （L.）幼虫后,蜂卵如何逃避和抑制寄主的免疫攻击,尚未得到全面揭示。本文采用电镜技术系统观察了菜蛾盘绒茧蜂卵表面的超微结构。结果显示：蜂卵表面覆盖有纤维层和絮状的类病毒样纤丝（VLFs）,同时携带了含多分DNA病毒粒子（PDV）的萼液。在寄生初期,包裹在蜂卵表面的纤维层和VLFs首先起到保护蜂卵不被小菜蛾血细胞包囊的被动防御作用。随后,PDV发挥主动的免疫抑制作用。通过假寄生手段,证明了菜蛾盘绒茧蜂PDV (CvBV) 具有较持久的克服寄主免疫攻击的能力,是主要的免疫抑制因子。在假寄生后连续8 d的观察时间内,菜蛾盘绒茧蜂的蜂卵均未被包囊。结果提示,在菜蛾盘绒茧蜂-小菜蛾寄生体系中,菜蛾盘绒茧蜂采取被动防御和主动攻击两种方式应对寄主小菜蛾的免疫攻击。     

The effect of parasitism byHyposoter didymator [Hym.: Ichneumonidae] on food consumption and utilization bySpodoptera litura [Lep.: Noctuidae]

The effect of parasitism byHyposoter didymator (Thunb.) [Hym.: Ichneumonidae] on food consumption and utilization bySpodoptera litura (Fb.) [Lep.: Noctuidae] was studied for seven days, during which the parasitoid completed its larval development. Food consumption, weight gained and faeces produced were significantly less in parasitized larvae than in unparasitized larvae after the 4^th day following parasitization. Approximate digestibility was higher in parasitized larvae after the 2^nd day following parasitization. Efficiency of conversion of ingested and digested food into body weight was greater in unparasitized larvae after the 2^nd day of parasitization. There seems to be a definite immediate advantage to the crop on releasing the parasitoid due to the reduced consumption of food. Contribution No. 46004 of Biological Control Centre (NCIPM), Bangalore 560 024.     

Fate of polydnavirus DNA of the egg-larval parasitoid Chelonus inanitus in the host Spodoptera littoralis

In situ hybridizations show that 5 min after parasitization, polydnavirus DNA is in close vicinity of the parasitoid egg, but 5 h later also in the yolk and partially in the host embryo. Fifteen hours after parasitization, the viral DNA is seen all over the host embryo and hardly in the yolk. The tissue distribution of the viral DNA was analysed and quantified by dot blots in the fifth instar parasitized larvae. On a per host basis, haemocytes and fat body contained the highest amount of viral DNA, while nervous tissue, intestinal tract and carcass contained less. Of the three viral segments tested, all were found in all tissues. Relative to the quantity of host DNA, viral DNA was most abundant in haemocytes, about five times less abundant in fat body and nervous tissue and about 25 times less abundant in intestinal tract. The total quantity of viral DNA per host was 444+/-145 pg which is similar to the quantity injected by the wasp; thus, the viral DNA persists throughout parasitization. The parasitoid larva contains 820+/-80 pg viral DNA integrated in the genome. This illustrates that the dose of viral DNA injected in virions represents approximately one third of the total viral genomic information present in a host at a late stage of parasitism.     

Quantitative trait loci involved in the reproductive success of a parasitoid wasp

Dissecting the genetic basis of intraspecific variations in life history traits is essential to understand their evolution, notably for potential biocontrol agents. Such variations are observed in the endoparasitoid Cotesia typhae (Hymenoptera: Braconidae), specialized on the pest Sesamia nonagrioides (Lepidoptera: Noctuidae). Previously, we identified two strains of C. typhae that differed significantly for life history traits on an allopatric host population. To investigate the genetic basis underlying these phenotypic differences, we used a quantitative trait locus (QTL) approach based on restriction site‐associated DNA markers. The characteristic of C. typhae reproduction allowed us generating sisters sharing almost the same genetic content, named clonal sibship. Crosses between individuals from the two strains were performed to generate F2 and F8 recombinant CSS. The genotypes of 181 clonal sibships were determined as well as the phenotypes of the corresponding 4,000 females. Informative markers were then used to build a high‐quality genetic map. These 465 markers spanned a total length of 1,300 cM and were organized in 10 linkage groups which corresponded to the number of C. typhae chromosomes. Three QTLs were detected for parasitism success and two for offspring number, while none were identified for sex ratio. The QTLs explained, respectively, 27.7% and 24.5% of the phenotypic variation observed. The gene content of the genomic intervals was investigated based on the genome of C. congregata and revealed 67 interesting candidates, as potentially involved in the studied traits, including components of the venom and of the symbiotic virus (bracovirus) shown to be necessary for parasitism success in related wasps.     

The effects of host deprivation on the calyx cells of Nasonia vitripennis (walker) (hymenoptera: Pteromalidae)

Summary 1. The changes in the ultrastructure of the cells of the calyx in the female reproductive system of Nasonia vitripennis are described during a period extending from a condition when host puparia are readily available to a condition of prolonged host deprivation.2. In conditions when host puparia are available, the calyx cells resemble typical secretory cells with rough endoplasmic reticulum, Golgi complex and mitochondria. After periods of host deprivation the calyx cells increase in size, the organelles change and become reorientated and cytolysomes appear producing a configuration of cells undergoing autophagy.3. When host puparia become available again, the cells show an ability to recover and recommence production of secretory droplets.     

Proximal location of mouse prostate epithelial stem cells: a model of prostatic homeostasis

Stem cells are believed to regulate normal prostatic homeostasis and to play a role in the etiology of prostate cancer and benign prostatic hyperplasia. We show here that the proximal region of mouse prostatic ducts is enriched in a subpopulation of epithelial cells that exhibit three important attributes of epithelial stem cells: they are slow cycling, possess a high in vitro proliferative potential, and can reconstitute highly branched glandular ductal structures in collagen gels. We propose a model of prostatic homeostasis in which mouse prostatic epithelial stem cells are concentrated in the proximal region of prostatic ducts while the transit-amplifying cells occupy the distal region of the ducts. This model can account for many biological differences between cells of the proximal and distal regions, and has implications for prostatic disease formation.     

Host searching behavior and potential of an aquatic ichneumonid pupal parasitoid of rice caseworm (Parapoynx stagnalis) in an upland rice paddy agro-ecosystem of the Western Ghats,India

Parapoynx stagnalis (Zeller) (=Nymphula depunctalis (Guenée), is a sporadic rice paddy pest of south and southeast Asian rice paddy fields, and widely known as rice caseworm. A recent outbreak of the pest was observed in the upland rice paddy agro-ecosystem of the central Western Ghats, India. No potential natural enemies of this pest have so far been reported, mainly due to the semi-aquatic behavior of the larvae and pupae. However, an undescribed aquatic ichneumonid wasp species (belonging to a genus near Litochila) is reported as a potentially useful early stage pupal parasitoid of this pest in our study. The host searching behavior and potential of the parasitoid wasp was studied in detail using both field and laboratory experiments. The adult female wasps usually dive into the water in search of the host pupae, remaining under water for a maximum of 90.2s, while searching for rice caseworm pupae. In field and laboratory experiments, we found 73% of the parasitized pupae of P. stagnalis kept under water yielded adult parasitic wasps. However, no parasitoids emerged from parasitized host pupae maintained in dry terrariums. Sex ratio was 2.8:1. The present discovery of the semi-aquatic parasitoid wasp could aid in better management of the rice caseworm population in rice paddy fields.     

The role of c-Fes in vascular endothelial growth factor-A-mediated signaling by endothelial cells

c-Fes plays pivotal roles in angiogenic cellular responses of endothelial cells. Here we examined the role of c-Fes in vascular endothelial growth factor-A (VEGF-A)-mediated signaling pathways in endothelial cells. We introduced either wild-type or kinase-inactive c-Fes in porcine aortic endothelial (PAE) cell lines, which endogenously express VEGF receptor (VEGFR)-1, and PAE cells ectopically expressing VEGFR-2 (denoted KDR/PAE cells) and generated stable cell lines. VEGF-A induced autophosphorylation of c-Fes only in KDR/PAE cells, suggesting that VEGFR-2 was required for its activation. Expression of kinase-inactive c-Fes failed to demonstrate dominant negative effect on VEGF-A-induced chemotaxis and capillary morphogenesis. Phosphoinositide 3-kinase (PI3-kinase) was activated in KDR/PAE cells and c-Fes contributed to this process in a kinase activity-dependent manner. However, VEGFR-2, insulin receptor substrate-1, and c-Src were also involved in VEGF-A-induced activation of PI3-kinase, resulting in the compensation in cells expressing kinase-inactive c-Fes. Interestingly, overexpression of wild-type c-Fes in PAE cells induced VEGF-A-independent capillary morphogenesis. Considered collectively, VEGF-A activated PI3-kinase partly through c-Fes and increase in c-Fes kinase activity enhanced capillary morphogenesis by yet unknown signaling pathways.     

Changes in the haemolymph proteome of Spodoptera littoralis induced by the parasitoid Chelonus inanitus or its polydnavirus and physiological implications

The egg-larval parasitoid Chelonus inanitus induces in its host Spodoptera littoralis two major developmental effects, namely a precocious onset of metamorphosis followed by a developmental arrest in the prepupal stage. Along with each egg, the wasp injects polydnavirus and venom into the host egg. The polydnavirus has been shown to play a major role in inducing the developmental arrest while the parasitoid larva is instrumental in inducing the precocious onset of metamorphosis. Here we report that experimental dilution of haemolymph of polydnavirus-containing larvae can partially prevent the developmental arrest while injection of native, but not of heat-treated, haemolymph or plasma from polydnavirus-containing larvae into nonparasitized larvae could induce developmental arrest in 14-15% of the larvae. This illustrates that heat-labile factors present in haemolymph play a role in causing developmental arrest. Injection of parasitoid medium increased the proportion of larvae entering metamorphosis precociously while injection of antibodies against a parasitoid-released protein had the opposite effect; this indicates that this protein and possibly other parasitoid-released substances are involved in inducing the precocious onset of metamorphosis. Analysis of the plasma proteome of nonparasitized, parasitized and polydnavirus-containing larvae revealed that the developmental effects are associated with only minor differences: eleven low abundant viral or virus-induced proteins and five parasitoid-released proteins were seen at specific stages of the host.