THE CELLULAR IMMUNE RESPONSE OF DAPHNIA MAGNA UNDER HOST–PARASITE GENETIC VARIATION AND VARIATION IN INITIAL DOSE

In invertebrate–parasite systems, the likelihood of infection following parasite exposure is often dependent on the specific combination of host and parasite genotypes (termed genetic specificity). Genetic specificity can maintain diversity in host and parasite populations and is a major component of the Red Queen hypothesis. However, invertebrate immune systems are thought to only distinguish between broad classes of parasite. Using a natural host–parasite system with a well‐established pattern of genetic specificity, the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa, we found that only hosts from susceptible host–parasite genetic combinations mounted a cellular response following exposure to the parasite. These data are compatible with the hypothesis that genetic specificity is attributable to barrier defenses at the site of infection (the gut), and that the systemic immune response is general, reporting the number of parasite spores entering the hemocoel. Further supporting this, we found that larger cellular responses occurred at higher initial parasite doses. By studying the natural infection route, where parasites must pass barrier defenses before interacting with systemic immune responses, these data shed light on which components of invertebrate defense underlie genetic specificity.     

胸腺对雌性大鼠肝脏抗氧化功能的影响及其与细胞免疫、性激素水平的关系

雌性成年大鼠切除胸腺后,其肝脏脂质过氧化产物丙二醛增多,还原型谷胱甘肽(GSH)含量减少,微粒体和线粒体膜流动性降低。隔日1次皮下注射自猪胸腺提取的胸腺因子D(TFD)2mg/kg共3月,可逆转去胸腺大鼠上述指标的变化。为了探讨胸腺影响肝脏抗氧化功能的中间途径,还测定了脾T淋巴细胞增殖反应及血浆性激素水平。结果表明,去胸腺大鼠脾脏T淋巴细胞增殖反应减弱、血浆雌二醇/睾酮比值下降;给予TFD可逆转其变化。实验结果提示,胸腺对大鼠肝脏抗氧化功能的影响可能与胸腺-内分泌-免疫网络有关。     

TWO INNEXINS OF Spodoptera litura INFLUENCES HEMICHANNEL AND GAP JUNCTION FUNCTIONS IN CELLULAR IMMUNE RESPONSES

Insect cellular immune responses include encapsulation, nodule formation, and phagocytosis. Hemichannels and gap junctions are involved in these cellular actions. Innexins (Inxs: analogous to the vertebrate connexins) form hemichannels and gap junctions, but the molecular mechanisms underlying their biology is still unclear. In this article, we reported a steady‐state level of Inxs (SpliInxs) in hemocytes of Spodoptera litura, which formed nonfunctional hemichannels on the cell surface to maintain normal metabolism. We also reported that two innnexins (SpliInx2 and SpliInx3) were expressed significantly higher in hemocytes compared to other tissues, suggesting that they play important roles in hemocytes. Amino acid analysis found that two cysteine residues in two extracellular loops provided the capability for SpliInx2 and SpliInx3 hemichannels to dock into gap junctions. Western blotting demonstrated that both extracellular and intracellular loops of SpliInx3 and the extracellular loops of SpliInx2 might undergo posttranslational modification during the formation of a steady‐state hemichannel. During hemichannel formation, SpliInx2 presented as one isoform, while SpliInx3 presented as three isoforms. These results provide fundamental knowledge for further study of how steady‐state levels of SpliInxs are dynamically adjusted to perform cellular immune responses under immune challenge.     

PARASITE VIRULENCE AND HOST IMMUNE DEFENSE: HOST IMMUNE RESPONSE IS RELATED TO NEST REUSE IN BIRDS

The evolution of parasite virulence has been hypothesized to be related to the mode of parasite transmission; horizontally transmitted parasites can afford to damage their hosts more than vertically transmitted parasites because increased virulence does not reduce the probability of transmission to new hosts. This relationship between mode of transmission and virulence would particularly select for improved immune defense in hosts that are subject to horizontally transmitted parasites. Among avian hosts, hole nesters and colonial nesters frequently reuse nest sites because of nest-site limitation, and this results in an increased frequency of horizontal transmission. Comparison of the size of two organs involved in the immune defense between pairs of bird species being either hole or open nesters, or colonially or solitarily nesting birds, respectively, revealed that the size of the bursa of Fabricius and the spleen were consistently larger in hole nesters than in open nesters, and similarly in colonially breeding bird species than in solitarily breeding species. These results support the hypothesis that mode of parasite transmission affects the evolution of immune defence in hosts.     

草鱼Noxa基因克隆及其应答GCRV入侵的表达响应

研究通过获得草鱼Noxa基因(Cinoxa)全长cDNA, 进行序列分析和进化树构建, 使用定量PCR (qPCR)的方法研究其在GCRV刺激下的表达模式。研究发现, 草鱼Noxa基因的蛋白序列与斑马鱼Noxa基因具有高度相似性。通过分析草鱼和斑马鱼的Noxa基因的蛋白三维结构(3D)模型, 研究发现两者具有高度一致的蛋白三维结构模式, 该模型与高等哺乳类中的Bcl-2家族蛋白中C端结构域同源。对Cinoxa在GCRV刺激下的表达模式的研究表明, Cinoxa在GCRV感染后中肾、脾脏和头肾中表达发生显著性变化, 攻毒后24h和120h出现显著上调表达。研究表明草鱼Noxa为斑马鱼Noxa的同源基因, 并且参与了草鱼对GCRV入侵的应答反应, 为深入研究鱼类Noxa应答病毒入侵的功能和转录调控机制奠定了基础。     

甲1(H1N1)和甲3(H3N2)型流感病毒在小鼠体内诱导细胞免疫反应的研究

比较了甲型流感病毒A/HK/123/77(H1N1)和A/Qld/6/72(H3N2)及其具有相应表面抗原的两个冷适应基因重分配株(Cold-Adapted Reassortant)的子代毒株CR35和CR6,在小鼠体内诱导初次细胞毒性T细胞(简称Tc)反应的能力。静脉注射相同剂量病毒后第6天,甲3型A/QLd和CR6所诱导的脾细胞Tc活性均比甲1型A/HK和CR35者高100倍。编码内部蛋白的基因相同而表面抗原的基因不同的CR6与CR35所诱导的Tc活性也不同,说明了表面抗原决定着初次Tc反应的强度。用无关的流感病毒A/SW/72(H6N5)攻击已用低剂量(10~4EID_(?))病毒致敏的小鼠表明,对A/Qld和CR6致敏者所诱导的第二次Tc活性,比A/HK和CR3S致敏者的稍高;但对用大剂量病毒致敏者,则均能产生同样好的第二次Tc活性。对Tc识别感染靶细胞上的病毒成份进行了讨论。     

INDUCTION OF CELLULAR PROCESSES CONTAINING COLLAGENASE AND RETINOID BY INTEGRIN-BINDING TO INTERSTITIAL COLLAGEN IN HEPATIC STELLATE CELL CULTURE

Cultered hepatic stellate cells were induced to elongate long, multipolar cellular processes by interstitial collagen gel used as a substratum, as compared to flattened or round cell shapes on polystyrene surface or on Matrigel containing the basement membrane components, respectively. The process induction was inhibited by several reagents as follows: (1) anti-integrin α2 antibody; (2) an oligopeptide, DGEA, an integrin-binding sequence in type I collagen molecule; (3) wortmannin, a phosphatidylinositol 3-kinase inhibitor. Protein tyrosine phosphorylation was enhanced throughout cells including cellular processes by culturing on type I collagen gel. Dual fluorescence staining showed that the core of the processes contained microtubules, whereas the periphery of the processes comprised fibrillar actin. Thus, the process extension was found to depend on integrin-binding to type I collagen fibres, followed by signal transduction and cytoskeleton assembly. The cellular processes included interstitial collagenase and vitamin A-containing lipid droplets. The lipid droplets and vitamin A-autofluorescence were increased by retinyl acetate addition to the culture medium, suggesting an important role of processes in hepatic stellate cell function.     

饲料糖对彭泽鲫生长和生理机能的影响

用分别含20%(低)、40%(高)葡萄糖和糊精的等氮(粗蛋白为35%风干物质)等能(16.4kJ/g)饲料饲养平均尾重为(2.40±0.16)g澎泽鲫Carassius auratus var. Pengze 16周,研究饲料糖种类和水平对鲫鱼生长、抗氧化力、非特异性免疫力和镉耐受性的影响,探讨鲫鱼对糖的利用能力及糖的生理功效。另用相同的饲料在相似的条件下饲养初重为(7.14±0.85)g的鲫鱼8周后胸腔注射12.5mg/kg体重的氯化镉溶液,观察其24h的存活率。实验结果表明饲料糖种类和水平都没有对鲫鱼的生长、脾指数和肝指数造成显著影响。高糖组糖化血红蛋白GHb值较高(P<0.05)。肝胰脏超氧化物歧化酶SOD活性、血浆SOD活性和总抗氧化力T-AOC各组差异不显著,肝胰脏的T-AOC为葡萄糖组显著高于糊精组(P<0.05)。补体溶血活性、血浆溶菌酶活性各组差异不显著。红细胞脆性高糖组显著低于低糖组(P<0.05)。镉染毒存活率各组差异不显著。上述结果提示40%饲料糖对鲫鱼生理功能没有不良影响,一定量的饲料糖有利于提高鲫鱼的抗氧化力。       

半滑舌鳎AKT-ineracting protein基因的克隆及免疫应答表达分析

研究克隆了半滑舌鳎Cynoglossus semilaevis膜蛋白AKT-interacting protein (AKTIP)基因, 研究了其在健康组织中的表达模式、鳗弧菌(Vibrio anguillarum)感染后免疫组织和不同病原物刺激外周血淋巴细胞中的表达特征。通过常规克隆和RACE技术, 获得的半滑舌鳎AKTIP基因全长cDNA序列为1224 bp, 其中包括5'-UTR为116 bp, 3'-UTR为117 bp和完整的ORF序列891 bp, 编码296个氨基酸, 预测蛋白质的等电点(PI)为9.12,分子量是33.74 kD; 同源比对发现半滑舌鳎AKTIP的氨基酸序列在不同物种之间具有较高的保守性; 荧光实时定量PCR (qRT-PCR)检测到半滑舌鳎各个组织中均有AKTIP基因的表达, 在卵巢中表达量最高; 鳗弧菌感染半滑舌鳎后, AKTIP基因在肝、鳃、血液、肠、头肾和脾中均上调表达; 病原模拟物PGN、LPS、poly I:C和WGP刺激半滑舌鳎外周血淋巴细胞均诱导AKTIP基因下调表达。研究表明半滑舌鳎AKTIP基因参与了机体免疫反应为给半滑舌鳎免疫防御技术的研究提供理论依据。     

THE RESPONSE TO SELECTION FOR FAST LARVAL DEVELOPMENT IN DROSOPHILA MELANOGASTER AND ITS EFFECT ON ADULT WEIGHT: AN EXAMPLE OF A FITNESS TRADE-OFF

A selection experiment using Drosophila melanogaster revealed a strong trade-off between adult weight and larval development time (LDT), supporting the view that antagonistic pleiotropy for these two fitness traits determines mean adult size. Two experimental lines of flies were selected for a shorter LDT (measured from egg laying to pupation). After 15 generations LDT was reduced by an average of 7.9%. The response appeared to be controlled primarily by autosomal loci. A correlated response to the selection was a reduction in adult dry weight: individuals from the selected populations were on average 15.1% lighter than the controls. The lighter females of the selected lines showed a 35% drop in fecundity, but no change in longevity. Thus, there is no direct relationship between LDT and adult longevity. The genetic correlation between weight and LDT, as measured from their joint response to selection, was 0.86. Although there was weak evidence for dominance in LDT, there was none for weight, making it unlikely that selection acting on this antagonistic pleiotropy could lead to a stable polymorphism. In all lines, sex differences in weight violated expectations based on intrasex genetic correlations: Females, being larger than males, ought to require a longer LDT, whereas there was a slight trend in the opposite direction. Because the sexual dimorphism in size was not significantly altered by selection, it appears that the controlling loci are either invariant or have very limited pleiotropic effect on developmental time. It is suggested that they probably control some intrinsic, energy-intensive developmental process in males.