Signaling through CD5 Activates a Pathway Involving Phosphatidylinositol 3-Kinase, Vav, and Rac1 in Human Mature T Lymphocytes

CD5 acts as a coreceptor on T lymphocytes and plays an important role in T-cell signaling and T-cell–B-cell interactions. Costimulation of T lymphocytes with anti-CD5 antibodies results in an increase of the intracellular Ca²⁺ levels, and subsequently in the activation of Ca²⁺/calmodulin-dependent (CaM) kinase type IV. In the present study, we have characterized the initial signaling pathway induced by anti-CD5 costimulation. The activation of phosphatidylinositol (PI) 3-kinase through tyrosine phosphorylation of its p85 subunit is a proximal event in the CD5-signaling pathway and leads to the activation of the lipid kinase activity of the p110 subunit. The PI 3-kinase inhibitors wortmannin and LY294002 inhibit the CD5-induced response as assessed in interleukin-2 (IL-2) secretion experiments. The expression of an inactivated Rac1 mutant (Rac1 · N17) in T lymphocytes transfected with an IL-2 promoter-driven reporter construct also abrogates the response to CD5 costimulation, while the expression of a constitutively active Rac1 mutant (Rac1-V12) completely replaces the CD5 costimulatory signal. The Rac1-specific guanine nucleotide exchange factor Vav is heavily phosphorylated on tyrosine residues upon CD5 costimulation, which is a prerequisite for its activation. A role for Vav in the CD5-induced signaling pathway is further supported by the findings that the expression of a dominant negative Vav mutant (Vav-C) completely abolishes the response to CD5 costimulation while the expression of a constitutively active Vav mutant [Vav(Δ1–65)] makes the CD5 costimulation signal superfluous. Wortmannin is unable to block the Vav(Δ1–65)- or Rac1 · V12-induced signals, indicating that both Vav and Rac1 function downstream from PI 3-kinase. Vav and Rac1 both act upstream from the CD5-induced activation of CaM kinase IV, since KN-62, an inhibitor of CaM kinases, and a dominant negative CaM kinase IV mutant block the Vav(Δ1–65)-and Rac1 · V12-mediated signals. We propose a model for the CD5-induced signaling pathway in which the PI 3-kinase lipid products, together with tyrosine phosphorylation, activate Vav, resulting in the activation of Rac1 by the Vav-mediated exchange of GDP for GTP.     

谷氨酸对嗜铬细胞瘤细胞热休克蛋白70 mRNA的诱导分析

热休克反应普遍存在于从细菌到人的整个生物界。除热外,多种应激原都可引起热休克蛋白的诱导。至于神经递质是否能够诱导热休克蛋白的表达,目前并不清楚。本文以诱导型热休克蛋白（ｈｓｐ）７０的ｃＤＮＡ为探针,运用Ｎｏｒｔｈｅｒｎ ｂｌｏｔ的方法,在嗜铬细胞瘤细胞（ＰＣ１２）上,分析了谷氨酸和乙酰胆碱对ｈｓｐ７０ ｍＲＮＡ的诱导作用。在此基础上又初步分析了起作用的递质受体。结果表明：在一定的浓度（５０￣５００     

Dietary Response of Chimpanzees and Cercopithecines to Seasonal Variation in Fruit Abundance. I. Antifeedants

In order to understand dietary differentiation among frugivorous primates with simple stomachs, we present the first comparison of plant diets between chimpanzees and cercopithecine monkeys that controls for food abundance. Our aim was to test the hypothesis that monkeys have a more diverse diet as a result of their dietary tolerance for chemical antifeedants. Our study species are chimpanzees, blue monkeys, redtail monkeys, and gray-cheeked mangabeys living in overlapping ranges in Kibale National Park, Uganda. We indexed food abundance by the percentage of trees having ripe fruit within the range of each group; it varied widely during the year. Chimpanzees spent almost 3 times as much of their feeding time eating ripe fruits as the monkeys did and confined their diets almost exclusively to ripe fruits when they were abundant. Monkeys maintained a diverse diet at all times. When ripe fruit was scarce chimpanzee and monkey diets diverged. Chimpanzees relied on piths as their main fallback food, whereas monkeys turned to unripe fruits and seeds. For each primate group we calculated the total weighted mean intake of 5 antifeedants; condensed tannins (CT), total tannins assayed by radial diffusion (RD), monoterpenoids (MT), triterpenoids (TT), and neutral-detergent fiber (NDF). Monkeys had absolutely higher intakes of CT, RD, MT, and TT than those of chimpanzees, and their intake of NDF did not differ from that of chimpanzees, appearing relatively high given their lower body weights. However contrary to expectation, dietary divergence during fruit scarcity was not associated with any change in absolute or relative intake of antifeedants. For example, fruit scarcity did not affect the relative intake of antifeedants by cercopithecines compared to chimpanzees. Our results establish chimpanzees as ripe-fruit specialists, whereas cercopithecines are generalists with a higher intake of antifeedants. The low representation of ripe fruits in the diets of cercopithecines has not been explained. An important next step is to test the hypothesis that the difference between Kibale chimpanzees and cercopithecines represents a more general difference between apes and monkeys.     

SAMPLE SIZE ESTIMATION FOR GENE ACTION ANALYSIS BY USING ORTHOGONAL CONTRAST

IIntroductionTheuseofrestrlctlonfragmentlengthpolymorphism（RFLP）markershasgreatlyslmpllfledthegeneticanalysisofquantitativetraits,providingareliableandextensiveframeworkofquantltatlvemarkerstowhichquantltatlyetyaitIOCI（QTL）clnhilinked［‘］．TodetectthelinkagebetwwenRFLPmarkersandPhenotyPlcvariationsoh－served,generallinearmodelofanalysisofvariance（ANOVA）hasbeenextensivelyusedL‘zJ．ByusingF、populations,thecompletegeneticInformation,thatIs,thethreegenotypesofageneticfact…     

毛萼田菁和其它茎瘤固氮植物(综述)

近来,豆科植物茎瘤固氮研究取得很大进展,这种双重固氮能力在农业上具有很大应用潜力。茎瘤固氮植物主要有三个属,即田菁属（Ｓｅｓｂａｎｉａ）、合萌属（Ａｅｓｃｈｙｎｏｎｍｅｎｅ）和假含羞草属（Ｎｅｐｔｕｎｉａ）。本文论述它们的生长特性、茎瘤的形成、固氮及在农业上的应用。     

Association mapping of leaf traits, flowering time, and phytate content in Brassica rapa.

Association mapping was used to investigate the genetic basis of variation within Brassica rapa, which is an important vegetable and oil crop. We analyzed the variation of phytate and phosphate levels in seeds and leaves and additional developmental and morphological traits in a set of diverse B. rapa accessions and tested association of these traits with AFLP markers. The analysis of population structure revealed four subgroups in the population. Trait values differed between these subgroups, thus defining associations between population structure and trait values, even for traits such as phytate and phosphate levels. Marker-trait associations were investigated both with and without taking population structure into account. One hundred and seventy markers were found to be associated with the observed traits without correction for population structure. Association analysis with correction for population structure led to the identification of 27 markers, 6 of which had known map positions; 3 of these were confirmed in additional QTL mapping studies.     

Next-generation bis-locked nucleic acids with stacking linker and 2′-glycylamino-LNA show enhanced DNA invasion into supercoiled duplexes

Targeting and invading double-stranded DNA with synthetic oligonucleotides under physiological conditions remain a challenge. Bis-locked nucleic acids (bisLNAs) are clamp-forming oligonucleotides able to invade into supercoiled DNA via combined Hoogsteen and Watson–Crick binding. To improve the bisLNA design, we investigated its mechanism of binding. Our results suggest that bisLNAs bind via Hoogsteen-arm first, followed by Watson–Crick arm invasion, initiated at the tail. Based on this proposed hybridization mechanism, we designed next-generation bisLNAs with a novel linker able to stack to adjacent nucleobases, a new strategy previously not applied for any type of clamp-constructs. Although the Hoogsteen-arm limits the invasion, upon incorporation of the stacking linker, bisLNA invasion is significantly more efficient than for non-clamp, or nucleotide-linker containing LNA-constructs. Further improvements were obtained by substituting LNA with 2′-glycylamino-LNA, contributing a positive charge. For regular bisLNAs a 14-nt tail significantly enhances invasion. However, when two stacking linkers were incorporated, tail-less bisLNAs were able to efficiently invade. Finally, successful targeting of plasmids inside bacteria clearly demonstrates that strand invasion can take place in a biologically relevant context.     

Characterization and primary functional analysis of a bamboo NAC gene targeted by miR164b

Key message

PeSNAC1 , a stress-related NAC1 from Phyllostachys edulis , was characterized. Ectopic expression in Arabidopsis indicated that PeSNAC1 together with ped -miR164b participated in the regulation of organ boundaries and stress tolerance.

Abstract

NAC (NAM, ATAF1/2 and CUC2) participates in many different processes regulating plant growth, development, and stress response. A total of 125 NAC genes have been predicted in moso bamboo (Phyllostachys edulis), but their roles are poorly understood. PeSNAC1 targeted by ped-miR164b was focused for further study. The cleavage of PeSNAC1 mRNA guided by ped-miR164b was validated using RLM-5′ RACE. Tissue-specific expression analysis demonstrated that ped-miR164b had a declining trend from root, sheath, leaf, to that of stem, which was opposite to that of PeSNAC1. Transgenic Arabidopsis plants overexpressing either PeSNAC1 (OX-PeSNAC1) or, ped-miR164b (OX-ped-miR164b) driven by the CaMV35S promoter were generated. OX-ped-miR164b plants showed similar phenotype of cuc2 mutants whose growth was seriously suppressed. Compared with Col-0, sense OX-PeSNAC1 plants grew rapidly and flowered earlier, whereas antisense plants grew slowly and exhibited delayed flowering. Sense OX-PeSNAC1 plants had the greatest number of lateral roots, while antisense OX-PeSNAC1 and OX-ped-miR164b plants had fewer lateral roots than Col-0. Under NaCl and PEG6000 stresses, survival rates were higher and F _v/F _m values declined more slowly in sense OX-PeSNAC1 plants than in Col-0, with lower survival rates and a more rapid decrease in F _v/F _m values conversely observed in antisense OX-PeSNAC1 and OX-ped-miR164b plants. These findings indicated that ped-miR164b-targeted PeSNAC1 may play key roles in plant development and tolerance to salinity and drought stresses.