Sequence analyses of feline B7 costimulatory molecules

Using RT-PCR amplifications with mRNA from mitogen-stimulated feline peripheral blood mononuclear cells, cDNA of feline B7-1 (CD80) and B7-2 (CD86) were cloned. The cDNA were sequenced and putative translated protein sequences compared with known counterpart sequences. Hydrophilicity patterns of the feline CD80 and CD86 which were only 26.8% identical at the amino acid sequence were very distinct from each other, but similar to the putative human CD80 and CD86 proteins, respectively. The feline CD80 gene encoded a protein of 292 amino acids and the CD86 gene encoded a protein of 329 amino acids. Amino-terminal signal sequences, extracellular Ig V- and Ig C-like domains, transmembrane domains, and carboxyl cytoplasmic domains were identified in both molecules. Although the most conserved domain among the CD80 sequences was the Ig C-like domain, the most conserved domain among the CD86 sequences was the Ig V-like domain. Among the known sequences, the bovine CD80 and the porcine CD86 sequences available for comparisons were identified as most closely related to the feline CD80 (63.3%) and CD86 (67.5%), respectively. The mouse molecules were the least identical (43.6 and 43.6%, respectively) with the feline CD80 and CD86 proteins. The human CD80 and CD86 molecules were 56.3 and 57.0% identical with the feline molecules.     

关于内蒙古大兴安岭林区大径材培育的探讨

文章通过对内蒙古大兴安岭林区培育大径材的目的、意义、必要性及方法等方面的分析,论述了大径级材培育是促进林区生态、经济和社会协调发展的有力措施。     

Isotopic fractionation of stratospheric nitrous oxide

We propose an isotopic fractionation mechanism, based on photolytic destruction, to explain the 15N/14N and 18O/16O fractionation of stratospheric nitrous oxide (N2O) and reconcile laboratory experiments with atmospheric observations. The theory predicts that (i) the isotopomers 15N14N16O and 14N15N16O have very different isotopic fractionations in the stratosphere, and (ii) laboratory photolysis experiments conducted at 205 nanometers should better simulate the observed isotopic fractionation of stratospheric N2O. Modeling results indicate that there is no compelling reason to invoke a significant chemical source of N2O in the middle atmosphere and that individual N2O isotopomers might be useful tracers of stratospheric air parcel motion.