Evolution of Host Search Strategies in Entomopathogenic Nematodes

There is interspecific variation in infective juvenile behavior within the entomopathogenic nematode genus Steinernema. This variation is consistent with use of different foraging strategies along a continuum between ambush and cruise foraging. To address questions about the evolution of foraging strategy, behavioral and morphological characters were mapped onto a phylogeny of Steinernema. Three species, all in the same clade, were classified as ambushers based on standing bout duration and host-finding ability. One clade of six species were all cruisers based on both host-finding and lack of standing behavior. All species in the ambusher clade had a high rate of jumping, all species in the cruiser clade had no jumping, and most intermediate foragers exhibited some level of jumping. Response to volatile and contact host cues was variable, even within a foraging strategy. Infective juveniles in the ambusher clade were all in the smallest size category, species in the cruiser clade were in the largest size categories, and intermediate foragers tended to be more intermediate in size. We hypothesize that the ancestral Steinernema species was an intermediate forager and that ambush and cruise foraging both evolved at least once in the genus.     

Construction of an <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> cell-surface display system using a putative GPI-anchored protein

A novel cell-surface display system was constructed in Aspergillus oryzae. Each of the five genes encoding the putative cell-wall-localized protein from the A. oryzae genome was cloned and these cell-surface anchor functions were examined by fusion to the C-terminal of the green fluorescent protein (GFP). Using the MP1 and CWP proteins as anchor proteins, GFP signals were strongly observed on the cell surface of recombinant A. oryzae. When these proteins were used as anchor proteins for cell-surface display of β-glucosidase from A. oryzae, enzyme activity was detected on the cell surface. In particular, β-glucosidase activity of recombinant A. oryzae using MP1, a putative glycosylphosphatidylinositol (GPI) anchor protein was higher than CWP. Based on these results, it was concluded that the MP1 protein can act as a GPI-anchor protein in A. oryzae, and the proposed cell-surface display system using MP1 allows for the display of heterogeneous and endogenous proteins.     

接种外生菌根对辽东栎幼苗生长的影响

辽东栎 (Quercusliaotungensis)是中国特有的栎林树种 ,也是中国暖温带落叶阔叶林的主要优势树种之一。铆钉菇 (Gomphidiusviscidus)和臭红菇 (Russulafoetens)是在自然环境中与其共生形成外生菌根的真菌。在温室花盆中播种辽东栎种子获得辽东栎幼苗 ,并对幼苗接种铆钉菇和臭红菇合成外生菌根 ,比较了有菌根和无菌根辽东栎幼苗生长、光合蒸腾特性、氮磷含量的差异。外生菌根对辽东栎幼苗的生长有明显的促进作用 ,有菌根幼苗的生物量、株高、净光合速率和水分利用效率高于无菌根幼苗 ,蒸腾速率则相反。有菌根幼苗的氮磷含量分别为无菌根幼苗的 1.7倍和 2 .2倍 ,外生菌根的合成还改变了氮磷在幼苗器官间的分配比例 ,与无菌根幼苗相比 ,有菌根幼苗茎中的氮磷减少 ,而叶片中的磷显著增加。同时接种铆钉菇和臭红菇的生长促进效果优于单独接种。     

林木群体遗传多样性和多位点遗传结构

本文评述了群体同工酶基因位点遗传结构研究中的主要度量方法及其在森林树种中的应用概况。群体遗传结构可由单位点和多位点两类参数度量。 文中对这两类度量及其关系分别进行了讨论。阐明了多位点遗传结构的信息对林木改良和资源保存策略的重要意义。     

二色补血草LbDREB基因在酵母中的抗逆性分析

利用酵母表达系统研究了二色补血草的DREB基因（LbDREB）对不同胁迫的抗性。将LbDREB构建到酵母表达载体pYES2中,转化到酿酒酵母INVSc1菌株中,并以转空pYES2质粒的酵母INVSc1（pYES2）作为对照,通过比较两种酵母在不同胁迫下的存活率来研究LbDREB基因对NaCl、KH_2PO_4、Na_2CO_3、NaHCO_3、低温、干旱、CuSO_4和CdCl_2胁迫的抗性。结果表明,LbDREB转化的酵母在各种胁迫下的存活率均明显高于转空pYES2的对照酵母,说明LbDREB基因除了具有传统认为的抗旱、耐盐、抗寒的作用外,还具有抗KH_2PO_4、Na_2CO_3、NaHCO_3、CuSO_4和CdCl_2等胁迫的能力。     

Microbial ecology of four coral atolls in the Northern Line Islands

Microbes are key players in both healthy and degraded coral reefs. A combination of metagenomics, microscopy, culturing, and water chemistry were used to characterize microbial communities on four coral atolls in the Northern Line Islands, central Pacific. Kingman, a small uninhabited atoll which lies most northerly in the chain, had microbial and water chemistry characteristic of an open ocean ecosystem. On this atoll the microbial community was equally divided between autotrophs (mostly Prochlorococcus spp.) and heterotrophs. In contrast, Kiritimati, a large and populated ( approximately 5500 people) atoll, which is most southerly in the chain, had microbial and water chemistry characteristic of a near-shore environment. On Kiritimati, there were 10 times more microbial cells and virus-like particles in the water column and these microbes were dominated by heterotrophs, including a large percentage of potential pathogens. Culturable Vibrios were common only on Kiritimati. The benthic community on Kiritimati had the highest prevalence of coral disease and lowest coral cover. The middle atolls, Palmyra and Tabuaeran, had intermediate densities of microbes and viruses and higher percentages of autotrophic microbes than either Kingman or Kiritimati. The differences in microbial communities across atolls could reflect variation in 1) oceaonographic and/or hydrographic conditions or 2) human impacts associated with land-use and fishing. The fact that historically Kingman and Kiritimati did not differ strongly in their fish or benthic communities (both had large numbers of sharks and high coral cover) suggest an anthropogenic component in the differences in the microbial communities. Kingman is one of the world's most pristine coral reefs, and this dataset should serve as a baseline for future studies of coral reef microbes. Obtaining the microbial data set, from atolls is particularly important given the association of microbes in the ongoing degradation of coral reef ecosystems worldwide.     

中国麋鹿遗传多样性现状与保护对策

通过对麋鹿野生种群的绝灭过程、圈养历史、种群增长及遗传多样性状况的分析研究,认为麋鹿脱离野生种群成为完全的圈养群体约有100多年的历史,捕猎和栖息地丧失是其绝灭的根本原因。麋鹿最初引入欧洲时曾经历了严重的近交衰退阶段,目前其耐受近交的能力显著增强。截至1994年我国麋鹿已达近500只,其遗传变异量约为其野生种群的70%。在我国重建麋鹿自然种群不仅完全可能,而且也只有如此才能使麋鹿在自然中进化并丰富其受损的遗传多样性。     

Characterization of the conformational changes of acetohydroxy acid isomeroreductase induced by the binding of Mg2+ ions, NADPH, and a competitive inhibitor.

Acetohydroxy acid isomeroreductase (EC 1.1.1.86), the second enzyme of the parallel branched chain amino acid pathway, is a homodimer with an Mr of approximately 114000 which in the presence of Mg2+ ions catalyzes an unusual alkyl migration followed by an NADPH-dependent reduction. Prior binding of NADPH and Mg2+ to the enzyme was shown to be required for substrate or competitive inhibitor [N-hydroxy-N-isopropyloxamate (IpOHA)] binding [Dumas, R., et al. (1994) Biochem. J. 301, 813-820]. Moreover, crystallographic data for the enzyme-NADPH-Mg2+-IpOHA complex [Biou, V., et al. (1997) EMBO J. 16, 3405-3415] have shown that IpOHA was completely buried inside the active site. These observations raised the question of how the reaction intermediate analogue inhibitor can reach the active site and implied that conformational changes occurred during the binding process. With a view of characterizing these conformational changes, H-D exchange experiments combined with mass spectrometry were performed. Results demonstrated that Mg2+ ions and NADPH binding led to an initial conformational change at the interface of the two domains of each monomer. Binding of the two cofactors to isomeroreductase alters the structure of the active site to promote inhibitor (substrate) binding, in agreement with the ordered mechanism of the enzyme. Structural changes remote from the active site were also found. They were interpreted as long-range structural effects on the two domains and on the two monomers in the time course of the ligand binding process.     

Global phosphoproteome of HT-29 human colon adenocarcinoma cells

Phosphorylation events in cellular signaling cascades triggered by a variety of cellular stimuli modulate protein function, leading to diverse cellular outcomes including cell division, growth, death, and differentiation. Abnormal regulation of protein phosphorylation due to mutation or overexpression of signaling proteins often results in various disease states. We provide here a list of protein phosphorylation sites identified from HT-29 human colon adenocarcinoma cell line by immobilized metal affinity chromatography (IMAC) combined with liquid chromatography (LC)-tandem mass spectrometry (MS/MS) analysis. In this study, proteins extracted from HT-29 whole cell lysates were digested with trypsin and carboxylate groups on the resulting peptides were converted to methyl esters. Derivatized phosphorylated peptides were enriched using Fe(3+)-chelated metal affinity resin. Phosphopeptides retained by IMAC were separated by high performance liquid chromatography (HPLC) and analyzed by electrospray ionization-quadrupole-time-of-flight (ESI-Q-TOF) mass spectrometry. We identified 238 phosphorylation sites, 213 of which could be conclusively localized to a single residue, from 116 proteins by searching MS/MS spectra against the human protein database using MASCOT. Peptide identification and phosphorylation site assignment were confirmed by manual inspection of the MS/MS spectra. Many of the phosphorylation sites identified in our results have not been described previously in the scientific literature. We attempted to ascribe functionality to the sites identified in this work by searching for potential kinase motifs with Scansite (http://scansite.mit.edu) and obtaining information on kinase substrate selectivity from Pattern Explorer (http://scansite.mit.edu/pe). The list of protein phosphorylation sites identified in the present experiment provides broad information on phosphorylated proteins under normal (asynchronous) cell culture conditions. Sites identified in this study may be utilized as surrogate bio-markers to assess the activity of selected kinases and signaling pathways from different cell states and exogenous stimuli.