Dynamic evolution of bitter taste receptor genes in vertebrates

Background  

Sensing bitter tastes is crucial for many animals because it can prevent them from ingesting harmful foods. This process is mainly mediated by the bitter taste receptors (T2R), which are largely expressed in the taste buds. Previous studies have identified some T2R gene repertoires, and marked variation in repertoire size has been noted among species. However, the mechanisms underlying the evolution of vertebrate T2R genes remain poorly understood.     

E. coli expression of a soluble, active single-chain antibody variable fragment containing a nuclear localization signal

Single-chain antibody variable fragment (scFv) proteins consist of an antibody heavy chain variable sequence joined via a flexible linker to a light chain variable sequence. Prior work has shown that ScFv 18-2 binds the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and sensitizes cancer cells to radiation following nuclear microinjection. A potential clinical delivery strategy is based on modification of the scFv so that it can be taken up into cells and imported to the nucleus. This will require development of an expression system for a nuclear localization signal (NLS)-tagged scFv derivative. We found, however, that addition of the highly basic NLS severely compromised expression in the host–vector system used for the parental scFv. After testing a variety of host strains, fusion partners, and NLS sequences and placements, successful expression was obtained with a construct containing a stabilizing N-terminal maltose binding protein tag and a single, optimized, C-terminal NLS moiety. Amylose affinity-purified ScFv 18-2 NLS protein was stable to storage at 4 °C in the presence of glycerol or trehalose, bound selectively to an epitope peptide, and was cleavable at an engineered Factor Xa protease site. Following lipid-mediated uptake into cultured cells, NLS-tagged ScFv 18-2, unlike the parental ScFv 18-2, localized predominantly in the cell nucleus.     

仙湖苏铁群落优势种群的生态位特征

采用生态位宽度和生态位重叠探讨仙湖苏铁群落优势种群的生态位特征。结果表明,群落中生态位宽度大的优势种群,对其它种群的生态位重叠大,而生态位宽度小的种群对生态位宽度大的种群的生态位重叠不一定大;如果2个种群生态位宽度相近,则存在着较大的生态位重叠。优势种之间生态位重叠大,由于存在资源竞争,导致群落组成和结构发生变化从而影响群落的演替发展。相同的物种对在不同层次其生态位重叠水平不一致,从林下层到立木层,物种对的生态位重叠程度降低。仙湖苏铁种群与立木层中生性树种的生态位重叠大,由于植株高度的差异,它们之间可能存在着促进而非竞争关系,因此调整群落林分组成,使群落向着以中生性树种为优势种的方向发展,也许是促进仙湖苏铁种群恢复和发展的有利措施。     

Increased lysine content in rice grains by over-accumulation of BiP in the endosperm

Over-accumulation of lysine-rich binding protein (BiP) in the rice endosperm caused strong endoplasmic reticulum (ER) stress and reduced seed storage proteins, resulting in a relative increase in nutritionally balanced non-seed storage proteins. We show that transgenic rice with over-accumulated BiP was a high-lysine rice germplasm and that the over-accumulation of BiP in the endosperm offered a unique strategy to improve the lysine content of cereal grains.     

珠江三角洲三水市种植业结构优化研究

珠江三角洲具有悠久的基塘系统立体生态农业的经营历史 ,随着经济的飞速发展 ,农业生产日益追求经济高增长。但由于物质和能量的不合理投入 ,种养方式不科学 ,农业在获得经济效益增长的同时 ,较大程度上恶化了生态环境 ,导致经济与生态的矛盾日益加深。如何协调经济发展与生态保护两者的关系 ,走可持续发展道路 ,成为亟待解决的问题。本文从产业结构和生产模式科学规划布局的角度 ,探讨经济和生态两者相互协调的途径 ,并以珠江三角洲代表性的农业地区三水市种植业系统为研究对象 ,应用层次分析 (ＡＨＰ)法和线性规划 (ＬＰ)法[4 ]构建系统的…     

14-3-3 proteins regulate glycogen synthase 3beta phosphorylation and inhibit cardiomyocyte hypertrophy

14-3-3 proteins are dimeric phophoserine-binding molecules that participate in important cellular processes such as cell proliferation, cell-cycle control and the stress response. In this work, we report that several isoforms of 14-3-3s are expressed in neonatal rat cardiomyocytes. To understand their function, we utilized a general 14-3-3 peptide inhibitor, R18, to disrupt 14-3-3 functions in cardiomyocytes. Cardiomyocytes infected with adenovirus-expressing YFP-R18 (AdR18) exhibited markedly increased protein synthesis and atrial natriuretic peptide production and potentiated the responses to norepinephrine stimulation. This response was blocked by the pretreatment with LY294002, a phosphoinositide 3-kinase (PI3K) inhibitor. Consistent with a role of PI3K in the R18 effect, R18 induced phosphorylation of a protein cloned from the vakt oncogene of retrovirus AKT8 (Akt - also called protein kinase B, PKB) at Ser473 and glycogen synthase 3beta (GSK3beta) at Ser9, but not extracellular signal-regulated kinase 1/2 (ERK1/2). AdR18-induced PKB and GSK3beta phosphorylation was completely blocked by LY294002. In addition, a member of the nuclear factor of activated T cells (NFAT) family, NFAT3, was converted into faster mobility forms and translocated into the nucleus upon the treatment of AdR18. These results suggest that 14-3-3s inhibits cardiomyocytes hypertrophy through regulation of the PI3K/PKB/GSK3beta and NFAT pathway.     

有机溶剂中固定化脂肪酶催化硅醇的酯化反应

固定化Mucor miehei脂肪酶可催化有机硅醇和脂肪酸的酯化反应．对固定化酶用量、脂肪酸链长、不同有机硅醇底物、有机溶剂极性和水含量等影响因素进行了初步研究．     

大鼠心内精氨酸血管加压素免疫反应阳性神经元的观察

本文用精氨酸血管加压素抗血清作为第一级抗体,通过石蜡切片免疫组织化学 PAP 法对大鼠心内神经节进行了研究,发现心内不仅存在精氨酸血管加压素免疫反应阳性的神经纤维,而且含有该免疫反应阳性的神经细胞。关于精氨酸血管加压素免疫反应阳性的胞体和纤维在心内存在的生理学意义本文进行了讨论。     

Regulation of Xenopus gastrulation by ErbB signaling

During Xenopus gastrulation, mesendodermal cells are internalized and display different movements. Head mesoderm migrates along the blastocoel roof, while trunk mesoderm undergoes convergent extension (C&E). Different signals are implicated in these processes. Our previous studies reveal that signals through ErbB receptor tyrosine kinases modulate Xenopus gastrulation, but the mechanisms employed are not understood. Here we report that ErbB signals control both C&E and head mesoderm migration. Inhibition of ErbB pathway blocks elongation of dorsal marginal zone explants and activin-treated animal caps without removing mesodermal gene expression. Bipolar cell shape and cell mixing in the dorsal region are impaired. Inhibition of ErbB signaling also interferes with migration of prechordal mesoderm on fibronectin. Cell-cell and cell-matrix interaction and cell spreading are reduced when ErbB signaling is blocked. Using antisense morpholino oligonucleotides, we show that ErbB4 is involved in Xenopus gastrulation morphogenesis, and it partially regulates cell movements through modulation of cell adhesion and membrane protrusions. Our results reveal for the first time that vertebrate ErbB signaling modulates gastrulation movements, thus providing a novel pathway, in addition to non-canonical Wnt and FGF signals, that controls gastrulation. We further demonstrate that regulation of cell adhesive properties and cell morphology may underlie the functions of ErbBs in gastrulation.