The contribution of symbiotic yeast to toxin resistance of the cigarette beetle (Lasioderma serricorne)

Representative plant allelochemicals were tested for toxicity to larvae of the cigarette beetle Lasioderma serricorne (F.) that were either untreated, treated with fungicides, or treated to render them free of symbiotic yeast (aposymbiotic) through surface sterilization of eggs. Insects rendered symbiont-free had higher mortality and/or developmental rates than controls when fed diets containing flavone, resorcinol or tannic acid. Fungicides reduced symbiont populations and/or caused morphological abnormalities. Two hydrolytic enzymes, which made up a significant protion of mycetome hydrolytic activity, were absent when symbionts were not present, as indicated by gel electrophoresis. This information indicates symbionts do contribute to the survival of their host by detoxifying toxins.

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Résumé La toxicité relative de substances allélochimiques végétales typiques a été examinée sur des larves de L. serricorne F. traitées aux fongicides et rendues aposymbiotiques par stérilisation superficielle des ufs. La toxicité de la nicotine est relativement inaffectée chez les larves aposymbiotiques; cependant les toxicités des resorcinol, flavone et acide tannique sont significativement augmentées chez les insectes ayant reçu un traitement pour éliminer leurs symbiontes. L'électrophorèse sur gel a montré que quelques enzymes responsables de l'hydrolyse du 1-naphthyl acétate, réaction enzymatique de la détoxification enzymatique, sont absentes chez les insectes aposymbiotiques. L'acide sorbique a réduit significativement l'effectif de symbiontes, tandis que le bénomyl a réduit leur gamme provoquant la multiplication anormale d'autres espèces. Ces résultats montrent que les symbiontes contribuent aux possibilités de détoxification de l'insecte. L'élimination des symbiontes peut être une technique efficace pour lutter contre les insectes qui en contiennent, puisqu'elle les priverait de leur contribution à l'alimentation et à la détoxification. Cette stratégie est vraisemblablement compatible avec des programmes de lutte intégrée, puisque les prédateurs et parasites ne contiennent pas de symbiontes.

     

农业部召开全国农业学校植物生态学教学讨论会

我国现有地区以上中等农业学校224所,分布全国各地,担负着全国中级农业科技人才的培养和县以下在职农业技术干部的轮训任务。实践证明,中等农业学校是我国初、高级农业教育和研究机构中承上启下的组成部分,是加速农业现代化建设的重要方面军。中等农业学校教育质量的高低,与专业基础课——植物及植物生理学教学质量的好坏是密切相关的。1980年5月农业部教育局颁布《植物及植物生理教学大纲》的     

Intracellular pH controls protein synthesis rate in the sea urchine egg and early embryo.

Direct comparisons between intracellular pH and protein synthesis in the sea urchin egg and early embryo show that pH controls protein synthesis rate in a highly sensitive and reversible manner. The entire increase and maintenance of protein synthesis at fertilization or parthenogenetic activation could be accounted for by a permanent increase in intracellular pH. However, unfertilized eggs whose intracellular pH has been raised artificially by ammonia take at least 30 min longer to reach the rate of protein synthesis seen in fertilized eggs. This time lag for ammonia activation and the decrease in protein synthesis rate during mitosis suggest that other unknown factors can also influence protein synthesis rate during fertilization and early embryogenesis.     

Light Effects in Yeast: Evidence for Participation of Cytochromes in Photoinhibition of Growth and Transport in Saccharomyces cerevisiae Cultured at Low Temperatures

Visible light of moderate intensity inhibits growth, respiration, protein synthesis, and membrane transport in bakers' yeast and has a deleterious effect on membrane integrity. The results of this study indicate that these effects require the presence of cytochromes b and a/a(3). The light sensitivities of growth rate and [(14)C]histidine uptake in wild-type rho(+) Y185 and D225-5A strains of Saccharomyces cerevisiae were compared with those in a variety of mutants lacking cytochrome b or a/a(3) or both; a close correlation was found between the presence of these respiratory pigments and photosensitivity. Thus, strain TL5-3C, a nuclear petite lacking cytochromes b, a, and a(3), was resistant to light; strain GL5-6A, another nuclear petite having reduced amounts of cytochromes a and a(3), was partially resistant; strains MB127-20C and MB1-6C, nuclear petites lacking only cytochrome b, were also only partially resistant to light; whereas mutants containing all three cytochromes but having their respiratory chain either nonfunctional (strain ZK3-6B) or uncoupled (strain 18-27/t12) were fully sensitive to light. Finally, an equal-energy, broad-band action spectrum for the light inhibition of growth and transport indicated that blue light (408 nm) was most effective; these wavelengths correspond to the Soret region of the cytochrome absorption spectrum. The results suggest, therefore, that the yeast cytochromes b, a, and a(3) are the primary photoreceptors for the inhibitory effects of light and, perhaps, for other processes, such as the entrainment of biological rhythms in this species.     

Identification of Ly 5 on the surface of ‘natural killer’ cells in normal and athymic inbred mouse strains

This report that (1) cells mediating NK activity in different inbred mouse strains selectively express one of two allelic products specified by theLy-5 locus (or a locus tightly linked to it) and (2) this surface structure may directly contribute to NK-mediated cytolysis, since Ly 5 antiserum specifically inhibits NK activity in vitro in the absence of complement.     

Electrophysiological study of coupling between cultured cells of the mouse mammary gland in five distinct physiological states.

Electrical coupling has been observed between cultured cells of the mouse mammary gland in five distinct physiological or pathological states. We have employed young primary cultures of cells dissociated from the following tissues: normal glands from young virgin or midpregnant females, hyperplastic alveolar nodules (believed to be precancerous) transplanted in gland-free mammary fat pads, and spontaneous mammary adenocarcinomas and their pulmonary metastases. All successfully impaled pairs of cells (a total of 97 pairs) were found to be ionically coupled. Furthermore, in normal and tumor cell cultures, electrical coupling was observed between dome-dome and dome-nondome cell pairs. This study correlates with electronmicroscopic studies of fresh normal, hyperplastic, and tumor samples, which show the presence of gap junctions in all three.     

A Revision of the Cytology and Ontogeny of Several Deficiencies in the 3a1–3c6 Region of the X Chromosome of DROSOPHILA MELANOGASTER

The cytology and developmental attributes of 18 deficiency mutations in the 3A1–3C6 region of the salivary gland X chromosome of Drosophila melanogaster have been investigated. The cytological limits of several older deficiencies have been revised and clarified and several new deficiencies are characterized. The deficiency mutants, with one possible exception, show a lethal phase in the late embryonic period or the early first larval instar. In contrast, the earliest acting point mutation lethals exposed by these deficiencies generally exhibit a somewhat later, post-embryonic lethality, perhaps indicating that the deficiencies are having some cumulative or synergistic impact on development. However, even with this difference in time of lethality, it is still possible to conclude that it is not the absolute size of the deficiency but rather the character of the loci deleted that determines the impact on development. Observations on the morphology of lethal embryos shows that while this analysis is internally consistent, it does not agree with earlier work. None of the 3A1–3C6 deficiencies causes any major teratologies during embryogenesis. Furthermore, the "earliest acting" gene in this region does not lie in band 3C1 but is most likely associated with bands 3A8–10.     

ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα

ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα.