Interpopulation differences in pupal size and fecundity are not associated with occurrence of outbreaks in Epirrita autumnata (Lepidoptera, Geometridae)

Abstract.

• 1 Among-population differences in pupal mass were studied in a geometrid, Epirrita autumnata. Some Epirrita autumnata populations regularly reach outbreak densities while others are never known to do so. Because adults do not feed, pupal mass of females correlates strongly with fecundity.
• 2 Larvae were collected from twelve field sites. Ten of our sample populations originated within the outbreak range of the species and represented different phases of outbreaks. Two populations originated outside the outbreak range.
• 3 Pupal mass of field-collected E. autumnata varied significantly among populations. The peak phase populations had the smallest pupae and the biggest were found in low density populations outside the outbreak range.
• 4 Offspring of moths from each population were reared under identical conditions in two larval densities. Significant differences were not found in pupal mass among populations. That is, the inherent size, correlated with fecundity of moths, was not different between populations originating within and outside the outbreak range, nor among collections from different densities or phases of the outbreaks.
• 5 Rearing density did not interact in a consistent way with population.
• 6 As far as size and fecundity are concerned, the results do not support Chitty's hypothesis that differences in genetic composition of the population at low and high density phases generate cyclic fluctuations of population density.
• 7 Because no hereditary or maternal differences were found in size and fecundity between E.autumnata originating within and outside the outbreak range, variation in reproductive capacity cannot explain why outbreaks occur only in some populations.

     

食道癌组织miR-21、miR-182表达与临床病理特征及预后的关系

目的:探讨食道癌组织微小RNA-21(miR-21)、微小RNA-182(miR-182)表达与临床病理特征及预后的关系。方法:选取2011年4月到2013年7月期间在我院接受手术治疗的食道癌患者84例,取患者的癌组织和癌旁正常组织作为检验标本,比较癌组织和癌旁正常组织中miR-21、mi R-182的表达水平,并分析食道癌组织中mi R-182、mi R-21的表达与临床病理特征及预后的关系。结果:癌组织中mi R-21、mi R-182的相对表达量明显高于癌旁正常组织,差异有统计学意义(P<0.05)。食道癌组织中mi R-21的表达与淋巴结转移、临床分期有关(P<0.05),与性别、年龄、分化程度、肿瘤大小无关(P>0.05);食道癌患者癌组织中miR-182的表达与年龄、性别、肿瘤大小无关(P>0.05),与分化程度、临床分期、淋巴结转移有关(P<0.05)。食道癌癌组织中miR-21、miR-182高表达患者的中位生存时间均低于低表达患者,差异有统计学意义(P<0.05)。结论:食道癌组织mi R-21、mi R-182表达与患者的部分临床病理特征及预后有关,两者有望成为食道癌新的治疗靶点。     

Ferricrocin synthesis in Magnaporthe grisea and its role in pathogenicity in rice

Iron is an essential element for the growth of nearly all organisms. In order to overcome the problem of its low bioavailability, microorganisms (including fungi) secrete siderophores, high-affinity iron chelators. As the acquisition of iron is also a key step in infection processes, siderophores have been considered as potential virulence factors in several host–pathogen interactions. Most fungi produce siderophores of the hydroxamate-type, which are synthesized by non-ribosomal peptide synthetases (NRPSs). Magnaporthe grisea , the causal agent of rice blast disease, produces ferricrocin as intracellular storage siderophore and excretes coprogens. In the M. grisea genome we identified SSM1 , an NRPS gene, and a gene encoding an l -ornithine N5-monooxygenase ( OMO1 ) that is clustered with SSM1 and responsible for catalysing the first step in siderophore biosynthesis, the N⁵ hydroxylation of ornithine. Disruption of SSM1 confirmed that the gene encodes ferricrocin synthetase. Pathogenicity of these mutants towards rice was reduced, suggesting a role of this siderophore in pathogenicity of M. grisea .     

丹参生物工程的研究与开发

中药材的品质改良是中药现代化进程中的一个重要问题,现代生物工程技术是进行中药材品质改良的可行途径之一。对丹参的组织培养、毛状根诱导培养及基因工程等方面的最新进展作一综述,以期为利用生物工程技术遗传改良丹参品质提供一些参考。     

Anion channel SLAH3 functions in nitrate‐dependent alleviation of ammonium toxicity in Arabidopsis

Slow anion channels (SLAC/SLAH) are efflux channels previously shown to be critical for stomatal regulation. However, detailed analysis using the β‐glucuronidase reporter gene showed that members of the SLAC/SLAH gene family are predominantly expressed in roots, in addition to stomatal guard cells, implicating distinct function(s) of SLAC/SLAH in the roots. Comprehensive mutant analyses of all slac/slah mutants indicated that slah3 plants showed a greater growth defect than wild‐type plants when ammonium was supplied as the sole nitrogen source. Ammonium toxicity was mimicked by acidic pH in nitrogen‐free external medium, suggesting that medium acidification by ammonium‐fed plants may underlie ammonium toxicity. Interestingly, such toxicity was more severe in slah3 mutants and, particularly in wild‐type plants, was alleviated by supplementing the media with micromolar levels of nitrate. These data thus provide evidence that SLAH3, a nitrate efflux channel, plays a role in nitrate‐dependent alleviation of ammonium toxicity in plants.     

Physiological dormancy in seeds of two endemic species of Begonia from Yunnan Province,China: diagnosis and classification

With the purpose of assessing the status of dormancy in seeds of two Begonia species (Begonia lithophila and Begonia guishanensis), freshly matured seeds were given gibberellic acid and moist chilling and allowed to dry after ripening. The seeds were then germinated on media with or without KNO₃ at 15, 20, 25, 30 and 18/25°C. All three treatments significantly increased germination percentages. Examination by X‐ray revealed that seeds of both species have a fully developed embryo and thus have no morphological component of dormancy; seeds readily imbibed water and KNO₃ solution. Therefore, we conclude that seeds of the two Begonia species have non‐deep physiological dormancy. Although KNO₃ significantly increased germination in both species, alternating temperatures did not, suggesting that the most favorable microhabitat for germination is small‐scale disturbances under the forest canopy.     

The effects of nutrient enrichment on a freshwater meiofaunal assemblage

1. The effects of eutrophication on phytoplankton, zooplankton and fish in lakes are well known. By contrast, little is known about the response of the zoobenthos to nutrient enrichment, while smaller organisms, such as the meiofauna, have for the most part been neglected. 2. In a long‐term (16 months) microcosm experiment, we assessed the effects of five levels of nutrients [total phosphorus (TP), 7–250 μg L^?1; nitrate, 2–8 mg L^?1] on a freshwater meiofaunal assemblage and on nematode diversity in particular. 3. Within the first 8 months, meiofaunal succession was only weakly affected, whereas, during the last 4 months, nutrient addition influenced most of the main taxa, with a concomitant change in the assemblage structure. 4. The density of the numerically dominant nematodes decreased upon nutrient enrichment, whereas ostracods became more numerous. Other taxa, including copepods, reached a maximum at intermediate nutrient levels or, in case of oligochaetes, were almost unaffected by nutrient enrichment. However, the changes in the density of the main taxa were usually insufficient to alter their biomass. Consequently, meiofaunal biomass was remarkably unresponsive to nutrient addition, while meiofaunal density displayed a unimodal relationship, with a peak at a TP concentration of 30 μg L^?1. In addition, nematode species richness decreased significantly with increasing nutrient concentrations. 5. We hypothesise that the response of meiofaunal taxa to nutrients is attributable to the development of primary producers, which shifted with enrichment from low densities of edible diatoms and unicellular green algae to large standing stocks of inedible forms, such as Lemna minor and Cladophora spp.     

Interactions between TIME and PIN could play a role in the system that controls the duration of diapause development and synchronization with seasonal cycles in the silkworm Bombyx mori*

The significance of winter cold in the termination of diapause was investigated with regards to TIME and PIN in eggs of the silkworm Bombyx mori. TIME (time interval measuring enzyme) is an ATPase that can measure time intervals by exhibiting a transitory burst of activation of the enzyme in accordance with diapause development, which requires cold for resumption of embryonic development in the silkworm. The possible timer function of TIME comprises a built‐in mechanism in the protein structure. TIME is a metallo‐glycoprotein consisting of 156 amino acid residues with a unique sequence in the N‐terminal region to which a sugar chain is attached. PIN (peptidyl inhibitory needle) inhibits the ATPase activity of TIME. PIN is not a simple enzyme inhibitor, but holds the timer by forming a time‐regulatory complex with TIME. The carbohydrate moiety of TIME is essential for the assembly of a high‐affinity PIN‐binding site within the timer motif of the TIME structure. The binding interaction between TIME and PIN was much tighter (nearly 1000 times) at 25°C than that at 4°C, as measured by fluorescence polarization. Because the logEC₅₀ at 4°C was approximately 7 nmol/L, PIN must dissociate from TIME at the physiological concentration of TIME in eggs in the winter cold. Based on the results of our study, we propose that the dissociation of the TIME–PIN complex in the winter cold cues a series of conformational changes of TIME, ultimately reaching the active form of ATPase which in turn causes the completion of diapause development and initiates new developmental programs.     

treegraph: automated drawing of complex tree figures using an extensible tree description format

treegraph assists in producing complex ready‐to‐publish figures of phylogenetic trees. The TGF format used by the program automates formatting of several different statistical support value types (confidence estimates) per tree node. Moreover, internal text and graphical labels are automatically arranged at the nodes as are annotations for clades or groups of terminals. treegraph imports nexus trees and related file formats. Beyond common tree edit operations, simultaneous pruning of subtrees (simplification of the tree to higher order clades) and saving of subtrees is possible. treegraph exports to the standard vector graphics formats Scalable Vector Graphics and PostScript.     

广州市园林植物多样性及其效应的调查研究

选取广州市信园为研究个案,同时先取市内有代表性的5个生态园林区作对比进行植物多样性调查,计算物种多样性指数(SW指数).并把计算结果分别与园区内其它生物多样性的调查结果和环境指标(温度、湿度、土壤含水量、有机质质量分数、含氮量)的检测结果进行分析.结果表明:①有机质质量百分比随植物SW指数上升呈增高趋势, 良好的土壤环境又会促进植物多样性发展;②鸟类、其他小型动物的种类数随植物SW指数上升呈现增高趋势,即植物多样性决定动物物种丰富程度.建议广州市园区的SW指数不应低于2.5.