Geographic variation in reproductive success of the parasitoid Asobara tabida in larvae of several Drosophila species

Abstract.

• 1 Asobara tabida is a parasitoid of Drosophila larvae in fermenting substrates. Because it is a widespread species, it may encounter different biotic and abiotic circumstances in various parts of its range.
• 2 The species composition of the host population varies over the parasitoid's range: D.obscura-group species (especially D.subobscura) are the main hosts for northwestern and central European parasitoids; D.melanogaster is the main host for southern European parasitoids.
• 3 D.melanogaster larvae can defend themselves against A.tabida by encapsulating the parasitoid egg, and survival in D.melanogaster is always lower than in D.subobscura.
• 4 Parasitoids from southern European populations are much better able to survive in D.melanogaster than their northwestern and central European conspecifics; parasitoids from different populations are equally well able to survive in D.subobscura.
• 5 The lower survival in D.melanogaster may be partly compensated for by the larger size of parasitoids emerging from this host species compared to parasitoids emerging from D.subobscura.
• 6 Within population groups, larger A.tabida females have more eggs in their ovarioles. Additionally, southern European females have more eggs and less fat than northern and western/central European females. The relationship between size and longevity is ambiguous.
• 7 It is concluded that parasitoids from different populations are adapted to region-specific circumstances.

     

Heat and starvation induced hormesis in longevity of Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) adult females

Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) is an important endoparasitoid of Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) larvae and pupae. Previous studies have showed that environmental stress induced hormesis in a variety of organisms. In the present study, we investigated the effects of heat and starvation stress on the survival and induced hormesis in longevity of O. sokolowskii adult females under laboratory conditions. Results showed that temperature and exposure time significantly affected the survival rate of O. sokolowskii adult females with the extreme temperatures and/or longer durations proving to be more lethal. When O. sokolowskii adult females were heat-treated for 0.5, 1, 2, 4, and 8 h, LTemp₅₀ were >50.00, 43.24, 38.82, 38.32, and 38.17 °C, respectively. LTime₅₀ at the threshold temperature of 38 °C was 3.90 h. The sub-lethal temperature exposure for a certain time period reduced the survival numbers, but increased the longevity of survived adult females at the condition of starvation. The exposure for 2 h at 36 and 38 °C reduced the survival numbers by 26.67% and 46.67%, but extended the longevity of the survived adult females by 65.89% and 55.37% in comparison with those in the control, respectively. These results suggest O. sokolowskii adult female has the potential of thermal resistance, and its longevity will increase via heat and starvation treatment.     

呈现新型冠状病毒RBD抗原病毒样颗粒的表达与鉴定*

目的:以乙型肝炎病毒核心抗原HBcAg为载体,构建呈现新冠病毒刺突蛋白受体结合域的病毒样颗粒,并鉴定其免疫原性,为新冠病毒疫苗的开发提供新思路。方法:在乙型肝炎病毒核心蛋白氨基酸编码序列第78和81位插入新冠病毒刺突蛋白受体结合域(RBD),并通过柔性linker(G4S)3进行连接,序列优化后将融合基因克隆到原核表达载体pET-28a(+),转化表达菌Rosetta,在自诱导培养基中诱导表达,菌体破碎后经蔗糖密度梯度离心,透析浓缩的方法纯化病毒样颗粒。SDS-PAGE、Western blot、透射电子显微镜检测和鉴定VLPs。将制备的VLPs与佐剂等比例混合经皮下免疫BALB/c小鼠,ELISA检测小鼠血清中特异性抗体,分析该HBc-RBD VLPs的免疫原性。结果:在自诱导培养基中,大肠埃希菌可表达部分可溶的VLPs,经蔗糖密度梯度离心纯化后在透射电子显微镜下可以观察到病毒样颗粒的存在。动物实验表明HBc-RBD VLPs刺激小鼠产生了特异性抗体。结论:在原核表达系统中成功表达了展示RBD抗原的VLPs,并通过小鼠实验初步验证了免疫原性,为新冠病毒疫苗的研发提供了新方向。     

志贺菌的质粒图谱分析

目的：分析志贺菌的质粒图谱及其与细菌药物敏感性的相关性。方法：从菌痢患者粪便标本中分离6株福氏志贺菌和4株宋内志贺菌,分别对其质粒图谱及药物敏感性进行分析。结果：不同菌株的质粒图谱具有明显的差异,但福氏志贺菌的5株以及宋内志贺菌的3株具有分子量23Kb的质粒带。各菌株的质粒图谱与其对头孢三嗪,头孢唑啉,环丙沙星,诺氟沙星,氯霉素的耐药特性无明显相关性。结论：获自患者的福氏志贺菌和宋内志贺菌具有不同的质粒图谱以及抗菌药物敏感性,提示在我市引起菌痢的志贺菌具有不同的来源。     

全错位排列问题的基于表面的DNA计算模型

生物表面技术是DNA计算的一种实现方式,是近年来生命科学的新兴研究领域．而全错位排列问题作为组合数学中一个重要的问题,到目前为止还没有好的算法．在DNA表面技术的基础上,首次提出了全错位排列问题的基于表面的DNA计算模型,并对模型进行了简单的分析．     

EFFECT OF ACETYLATION AND METHYLATION ON THE SWEETNESS INTENSITY OF THAUMATIN I

The lysine residues in thaumatin I were chemically modifiedby acetylation with acetic anhydride and by reductive methylation,under various conditions. The acetylated and methylated thaumatinswere isolated by ion-exchange chromatography. The number ofremaining free amino groups was determined by trinitrophenylation. At least four acetylated thaumatins with either one, two, threeor four acetylated amino groups were obtained as well as onemethylated thaumatin with six dimethyl lysine residues and onemonomethyl lysine residue. The sweetness intensity of the acetylated thaumatins decreasedwith the increasing number of acetylated amino groups; the sweettaste had disappeared completely when four amino groups wereacetylated. The methylated thaumatin with seven modified lysineresidues had a sweetness intensity practically equal to thatof the original thaumatin. The total net change, i.e. the isoelectric point of thaumatin,might play a role in the physiological behaviour of thaumatincausing a sweet taste sensation.