Characterization of recombinant human CXCR4 in insect cells: role of extracellular domains and N-glycosylation in ligand binding.

The cDNA of the human CXCR4/fusin was isolated from a human HeLa cell cDNA library by PCR and functionally expressed in Sf9 insect cells. The recombinant receptor was found to bind its natural ligand SDF-1alpha with an affinity comparable to that of the native receptor. Sequence-specific antibodies against each of the four extracellular domains were generated and used to investigate the interactions between the different domains of the receptor and the ligand. Each of the four antibodies was found to be able to inhibit ligand binding. CXCR4 was shown to be a glycoprotein. The role of N-glycosylation of CXCR4 in ligand binding was investigated in the insect cells overexpressed with recombinant CXCR4. Two potential N-glycosylation sites (Asn-11 and Asn-176) were either singly or doubly mutated to a leucine residue. Both single mutant receptors exhibited a significant decrease in ligand binding activity and affinity. The double mutant receptor showed little binding activity. Our data suggest that all of the extracellular domains are involved in ligand-receptor interactions and that N-glycosylation is required to maintain high-affinity ligand binding.     

皱纹盘鲍脓疱病的组织学和超微结构研究

１９９３年９月以来,大连地区许多养鲍厂的皱纹盘鲍都发生了严重的脓疱病。通过病理组织切片研究证明,脓疱病的病灶是从鲍足下表面开始逐渐扩展向足的深部,由于该病的唯一病原菌－河流弧菌Ⅱ的大量繁殖瞳的结缔组织、肌纤维坏死瓦解或破碎,病灶中只剩下鲍的血淋巴细胞、弧菌及细胞碎片。     

2009年中国植物科学若干领域重要研究进展

2009年中国植物科学在水稻和拟南芥研究等方面取得＂爆发性＂的快速发展。中国科学家在植物科学各领域中取得了大量的原创性研究成果,尤其是在基于新一代测序技术和计算生物学理论的基因组学、水稻功能基因挖掘、激素受体和信号转导以及转基因作物产业化和生态安全性研究等方面取得一系列重大进展,受到了国内外广泛关注。该文对2009年中国本土植物生命科学若干领域取得的重要研究进展进行概括性评述,旨在全面追踪当前中国植物科学领域发展的最新前沿和热点事件,并展现我国科学家们所取得的杰出成就。     

In vivo anti-inflammatory and antioxidant properties of ellagitannin metabolite urolithin A

Urolithin A is a major metabolite produced by rats and humans after consumption of pomegranate juice or pure ellagitannin geraniin. In this study, we investigated the anti-inflammatory effect of urolithin A on carrageenan-induced paw edema in mice. The volume of paw edema was reduced at 1h after oral administration of urolithin A. In addition, plasma in treated mice exhibited significant oxygen radical antioxidant capacity (ORAC) scores with high plasma levels of the unconjugated form at 1h after oral administration of urolithin A. These results indicate strong associations among plasma urolithin A levels, the plasma ORAC scores, and anti-inflammatory effects and may help explain a mechanism by which ellagitannins confer protection against inflammatory diseases.     

Sodium-pump activity and its inhibition by extracellular calcium in cardiac myocytes of guinea pigs

Myocardial sodium-pump activity was examined from ouabain-sensitive ⁸⁶Rb⁺ uptake using myocytes isolated from guinea-pig heart. Either sodium loading or the sodium ionophore, monensin, increased ⁸⁶Rb⁺ uptake by over 400%, indicating that the amount of Na⁺ available to the pump is the primary determinant of its activity, and that the sodium pump has a substantial reserve capacity in quiescent myocytes. Moreover, the degree of the above stimulation is markedly higher than corresponding values reported with multicellular preparations, suggesting that diffusion barriers make it impossible to observe the capacity of the sodium pump in the latter preparations. Removal of extracellular Ca²⁺ increased ouabain-sensitive ⁸⁶Rb⁺ uptake, probably by enhancing turnover of the sodium pump rather than increasing availability of Na⁺ to the pump.     

A novel zinc-carboxypeptidase SURO-1 regulates cuticle formation and body morphogenesis in Caenorhabditis elegans

Cuticle formation and molting are critical for the development of Caenorhabditis elegans. To understand cuticle formation more clearly, we screened for suppressors in transgenic worms that expressed dominant ROL-6 collagen proteins. The suro-1 mutant, which is mild dumpy, exhibited a different ROL-6::GFP localization pattern compared to other Dpy mutants. We identified mutations in three suro-1 mutants, and found that suro-1 (ORF R11A5.7) encodes a putative zinc-carboxypeptidase homologue. The expression of this enzyme in the hypodermis and the genetic interactions between this enzyme and other collagen-modifying enzyme mutants suggest a regulatory role in collagen processing and cuticle organization for this novel carboxypeptidase. These findings aid our understanding of cuticle formation during worm development.     

Moramonas marocensis gen. nov., sp. nov.: a jakobid flagellate isolated from desert soil with a bacteria-like,but bloated mitochondrial genome

A new jakobid genus has been isolated from Moroccan desert soil. The cyst-forming protist Moramonas marocensis gen. nov., sp. nov. has two anteriorly inserted flagella of which one points to the posterior cell pole accompanying the ventral feeding groove and is equipped with a dorsal vane—a feature typical for the Jakobida. It further shows a flagellar root system consisting of singlet microtubular root, left root (R1), right root (R2) and typical fibres associated with R1 and R2. The affiliation of M. marocensis to the Jakobida was confirmed by molecular phylogenetic analyses of the SSU rRNA gene, five nuclear genes and 66 mitochondrial protein-coding genes. The mitochondrial genome has the high number of genes typical for jakobids, and bacterial features, such as the four-subunit RNA polymerase and Shine–Dalgarno sequences upstream of the coding regions of several genes. The M. marocensis mitochondrial genome encodes a similar number of genes as other jakobids, but is unique in its very large genome size (greater than 264 kbp), which is three to four times higher than that of any other jakobid species investigated yet. This increase seems to be due to a massive expansion in non-coding DNA, creating a bloated genome like those of plant mitochondria.     

Pseudo-random mating systems for 3-allele loci

A random mating population attains equilibrium by the Hardy-Weinberg law. By demonstrating some simple examples for 2-allele loci, Li (1988) showed that a nonrandom mating population of certain mating patterns may also attain equilibrium. He called such a type of population a pseudo-random mating population. Tai (1990), then, gave a generalized representation of these pseudo-random mating systems. In this paper the clear patterns of pseudo-random mating behavior for a 3-allele locus are derived. Both autosomal and sex-linked systems are discussed. The study of these mating patterns provides a way to understand the complicated mating system of a population, which usually is only with difficulty realized through sampled individuals from that population.