Mating Behavior of Cephalonomia tarsalis (Ashmead) (Hymenoptera: Bethylidae) and the Effect of Female Mating Frequency on Offspring Production

The courtship behavior of Cephalonomia tarsalis, a solitary semiectoparasitoid of Oryzaephilus surinamensis, was investigated in the laboratory. Courtship behavior includes a series of stereotypic movements. Males play the most active role, executing the majority of courtship action, and females respond with relatively limited observable behaviors. Males typically keep antennae still during encounters with females prior to mounting, which may be correlated with recognition of the female's sexual status. After mounting, males display a series of movements on females, such as antennae touching female's antennae, antennae or mouth touching female's head or thorax, and walking around on female, which may serve to stimulate females towards increased receptivity. Females signal receptivity by assuming a stereotypical posture of remaining stationary, with head down, and antennae still in front of the body. The male then inserts his aedeagus and the pair copulates. After an average of 40.4 s of copulation, females signal the end of copulation by waving the antennae and moving away from the copulation site. Males continue copulating for a short time after females start moving but dismount soon thereafter. After dismounting, the two wasps move away from each other immediately, and they typically begin grooming. Neither males nor females exhibit mating preference based on mate's mating status in both choice and no-choice tests. The male is polygynous and the mated female can mate multiple times within the first 3 days after starting oviposition. However, female mating frequency does not affect the production of female progeny.     

Colonization genetics of an animal-dispersed plant (Vaccinium membranaceum) at Mount St Helens, Washington

Population founding and spatial spread may profoundly influence later population genetic structure, but their effects are difficult to quantify when population history is unknown. We examined the genetic effects of founder group formation in a recently founded population of the animal-dispersed Vaccinium membranaceum (black huckleberry) on new volcanic deposits at Mount St Helens (Washington, USA) 24 years post-eruption. Using amplified fragment length polymorphisms and assignment tests, we determined sources of the newly founded population and characterized genetic variation within new and source populations. Our analyses indicate that while founders were derived from many sources, about half originated from a small number of plants that survived the 1980 eruption in pockets of remnant soil embedded within primary successional areas. We found no evidence of a strong founder effect in the new population; indeed genetic diversity in the newly founded population tended to be higher than in some of the source regions. Similarly, formation of the new population did not increase among-population genetic variance, and there was no evidence of kin-structured dispersal in the new population. These results indicate that high gene flow among sources and long-distance dispersal were important processes shaping the genetic diversity in this young V. membranaceum population. Other species with similar dispersal abilities may also be able to colonize new habitats without significant reduction in genetic diversity or increase in differentiation among populations.     

Patterns of differentiation in a colour polymorphism and in neutral markers reveal rapid genetic changes in natural damselfly populations

The existence and mode of selection operating on heritable adaptive traits can be inferred by comparing population differentiation in neutral genetic variation between populations (often using F(ST) values) with the corresponding estimates for adaptive traits. Such comparisons indicate if selection acts in a diversifying way between populations, in which case differentiation in selected traits is expected to exceed differentiation in neutral markers [F(ST )(selected) > F(ST )(neutral)], or if negative frequency-dependent selection maintains genetic polymorphisms and pulls populations towards a common stable equilibrium [F(ST) (selected) < F(ST) (neutral)]. Here, we compared F(ST) values for putatively neutral data (obtained using amplified fragment length polymorphism) with estimates of differentiation in morph frequencies in the colour-polymorphic damselfly Ischnura elegans. We found that in the first year (2000), population differentiation in morph frequencies was significantly greater than differentiation in neutral loci, while in 2002 (only 2 years and 2 generations later), population differentiation in morph frequencies had decreased to a level significantly lower than differentiation in neutral loci. Genetic drift as an explanation for population differentiation in morph frequencies could thus be rejected in both years. These results indicate that the type and/or strength of selection on morph frequencies in this system can change substantially between years. We suggest that an approach to a common equilibrium morph frequency across all populations, driven by negative frequency-dependent selection, is the cause of these temporal changes. We conclude that inferences about selection obtained by comparing F(ST) values from neutral and adaptive genetic variation are most useful when spatial and temporal data are available from several populations and time points and when such information is combined with other ecological sources of data.     

Fungal colonization of synthetic substrates for use in space craft

Summary Materials being used or considered for use in space flight were examined for their susceptibility to fungal colonization. The materials included soft goods (clothing) and insulation and fabrication products such as Velcro^® attachments and elastic cord binders. Materials were exposed for at least 28 days in a highhumidity chamber colonized with over 50 species of fungi, including those species recommended for determining recalcitrance of materials to fungal biodegradation. At least nine of 25 products demonstrated extensive microscopic colonization by fungi, mostly byAcremonium obclavatum. Challenge procedures that rely on observations with the unaided eye, or 40×magnification of growth by a restricted number of fungal species with a cellulosic substrate as a positive control, are insufficient for determining the resistance of synthetic substrates to fungal colonization.     

单增李斯特菌感染胎盘相关毒力因子的研究进展

单核细胞增生李斯特氏菌(Listeria monocytogenes,LM)是一种可引起李斯特菌病的食源性致病菌。由于妊娠相关免疫缺陷和LM对非吞噬细胞独特的细胞内感染能力,孕妇是LM的主要目标人群。LM可穿过胎盘屏障,对胎儿造成重大伤害,包括早产、流产甚至死产。胎盘特异性毒力因子的作用对LM感染期间穿过胎盘屏障并感染胎儿尤为重要。文中介绍了国内外近年在孕妇中发生LM感染的事件,详细讨论了LM垂直传播以及在胎盘定殖机制方面的研究进展,着重讨论并分析了LM与感染胎盘相关毒力因子的最新发现,以期为今后防控LM的胎盘感染并保障食品安全提供参考。     

On the origin of the Norwegian lemming

The Pleistocene glacial cycles resulted in significant changes in species distributions, and it has been discussed whether this caused increased rates of population divergence and speciation. One species that is likely to have evolved during the Pleistocene is the Norwegian lemming (Lemmus lemmus). However, the origin of this species, both in terms of when and from what ancestral taxon it evolved, has been difficult to ascertain. Here, we use ancient DNA recovered from lemming remains from a series of Late Pleistocene and Holocene sites to explore the species' evolutionary history. The results revealed considerable genetic differentiation between glacial and contemporary samples. Moreover, the analyses provided strong support for a divergence time prior to the Last Glacial Maximum (LGM), therefore likely ruling out a postglacial colonization of Scandinavia. Consequently, it appears that the Norwegian lemming evolved from a small population that survived the LGM in an ice‐free Scandinavian refugium.     

Macaronesia: a source of hidden genetic diversity for post‐glacial recolonization of western Europe in the leafy liverwort Radula lindenbergiana

Aim Bryophytes exhibit apparently low rates of endemism in Macaronesia and differ from angiosperms in their diversity patterns by the widespread occurrence of endemics within and among archipelagos. This paper investigates the phylogeography of the leafy liverwort Radula lindenbergiana to determine: (1) whether or not morphologically cryptic diversification has occurred in Macaronesia, and (2) the relationships between Macaronesian and continental populations. Location Macaronesia, Europe, Africa. Methods Eighty‐four samples were collected across the species’ distribution range and sequenced at four chloroplast DNA (cpDNA) loci (atpB–rbcL, trnG, trnL and rps4). Phylogenetic reconstructions and Bayesian ancestral area reconstructions were used in combination with population genetics statistics (H, N_ST, F_ST) to describe the pattern of present genetic diversity in R. lindenbergiana and infer its biogeographic history. Results Patterns of genetic diversity in R. lindenbergiana exhibit a striking westwards gradient, wherein haplotype (0.90) and nucleotide (0.0038 ± 0.0019) diversity peak in Macaronesia, with a substantial endemic component. We found 20.9% of the genetic variance between biogeographic regions, and most pairwise F_ST comparisons between regions are significantly different from zero. The global N_ST (0.78) is significantly higher than the global F_ST (0.20), providing evidence for the presence of phylogeographic signal in the data. Ancestral area reconstructions suggest that the haplotypes currently found in western Europe share a Macaronesian common ancestor. Main conclusions The haplotype diversification exhibited by R. lindenbergiana in Macaronesia is comparable to that reported for many angiosperm groups at the species level. The apparent lack of radiation among Macaronesian bryophytes may thus reflect the reduced morphology of bryophytes in comparison with angiosperms. The high diversity found among Macaronesian haplotypes, especially in Madeira and the Canary Islands, and the significant N_ST/F_ST ratio between Macaronesia and all the other biogeographic regions (an indication that mutation rate exceeds dispersal rates) suggest that Macaronesian archipelagos could have served as a refugium during the Quaternary glaciations. Many haplotypes currently found in Europe share a Macaronesian common ancestor, and this further suggests that Macaronesia might have played a key role in the back‐colonization of the continent.     

云南肺癌易感性与HLA-A，HLA-B，DRB1，DQB1等位基因频率的相关性研究

目的:测定云南肺癌患者人类白细胞抗原(human leukocyte antigen,HLA)-A、B、DRB1、DQB1等位基因出现频率,探讨HLA各等位基因位点与云南省肺癌发病易感性的相关性。方法:采用病例-对照相关分析方法,选取云南籍肺癌患者和健康个体各30例,应用序列特异性引物聚合酶链反应(polymerase chain reaction-sequence specific primer,PCR-SSP)对HLA-A、HLA-B、HLA-DRB1及HLA-DQB1等位基因频率进行测定,与正常组对比测算相对危险因子(relative risk,RR)。结果:肺癌组的HLA-A~*02频率为90.0%(A~*0201为主),B~*46频率为40.0%,DRB1~*15频率为40.0%,较对照组的43.30%、0%、10.0%明显升高(Pc0.05,RR1)。肺癌组的HLA-A~*31频率为3.30%,A~*33频率为6.70%,B~*27频率为3.30%,B~*52频率为6.70%,DRB1~*03频率为0%,DRB3~*01频率为60.0%,DQB1~*02频率为0%,DQB1~*06频率为0%,较对照组的23.30%、26.70%、26.70%、26.70%、23.30%、86.70%、23.30%、26.70%降低明显,(RR1,Pc0.05)。结论:云南肺癌易感性可能与HLA-A~*02的频率(90%)具有相关性;而HLA-A~*31、HLA-A~*33、HLA-B~*52、HLA-B~*27、HLA-DRB1-~*03、HLA-DRB3~*01、HLA-DQB1~*02及HLA-DQB1~*06在肺癌患者中的频率较低,在云南肺癌发病中可能具有遗传拮抗作用。