天兰冰草染色体对小冰麦外植体再生能力的影响及基因的染色体定位

本文研究了天兰冰草（Ａｇｒｏｐｙｒｏｎｉｎｔｅｒｍｅｄｉｕｍ２ｎ＝４２）染色体导入小麦后对小冰麦外植体再生能力的影响,从而分析调控再生能力的基因所在天兰冰草染色体的定位。对异源八倍体小冰麦的研究表明,与天兰冰草强再生能力有关的基因主要分布在附加到中２的冰草染色体组上;对７个异附加系小冰麦的研究进一步表明,冰草强再生能力的性状由多基因调控,这些基因主要分布在附加到ＴＡＩ－１１、ＴＡＩ－１２、ＴＡＩ－１３的冰草染色体上。此外,小冰麦杂种Ｆ１的研究表明,在组织培养中同样能够表现出杂种优势。     

Glutamate-induced swelling of cultured astrocytes is mediated by metabotropic glutamate receptor

The effects of glutamate and its agonists and antagonists on the swelling of cultured astrocytes were studied. Swelling of astrocytes was measured by [3H]-O-methyl-D-glucose uptake. Glutamate at 0.5, 1 and 10mmol/L and irons-l-aminocyclopentane-1,3-dicarboxylic acid (trans-ACPD), a metabotropic glutamate receptor (mGluR) agonist, at 1 mmol/L caused a significant increase in astrocytic volume, whereas alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) was not effective. L-2-amino-3-phosphonopropionic acid (L-AP3), an antagonist of mGluR, blocked the astrocytic swelling induced by trans-ACPD or glutamate. In Ca2+-free condition, glutamate was no longer effective. Swelling of astrocytes induced by glutamate was not blocked by CdCl2 at 20 μmol/L, but significantly reduced by CdCl2 at 300 μmol/L and dantrolene at 30 μmol/L. These findings indicate that mGluR activation results in astrocytic swelling and both extracellular calcium and internal calcium stores play important roles in the genes     

PCR-based gene targeting of the inducible nitric oxide synthase (NOS2) locus in murine ES cells,a new and more cost-effective approach

Gene targeting by double homologous recombination in murine embryonic stem (ES) cells is a powerful tool used to study the cellular consequences of specific genetic mutations. A typical targeting construct consists of a neomycin phosphotransferase (neo) gene flanked by genomic DNA fragments that are homologous to sequences in the target chromosomal locus. Homologous DNA fragments are typically cloned from a murine genomic DNA library. Here we describe an alternative approach whereby the inducible nitric oxide synthase (NOS2) gene locus is partially mapped and homologous DNA sequences obtained using a long-range PCR method. A 7 kb NOS2 amplicon is used to construct a targeting vector where theneo gene is flanked by PCR-derived homologous DNA sequences. The vector also includes a thymidine kinase (tk) negative-selectable marker gene. Following transfection into ES cells, the PCR-based targeting vector undergoes efficient homologous recombination into the NOS2 locus. Thus, PCR-based gene targeting can be a valuable alternative to the conventional cloning approach. It expedites the acquisition of homologous genomic DNA sequences and simplifies the construction of targeting plasmids by making use of defined cloning sites. This approach should result in substantial time and cost savings for appropriate homologous recombination projects.     

Inhibitory effect of esculentoside A on tumour necrosis factor alpha production by human monocytes

Esculentoside A (EsA) is a saponin isolated from the roots of Phytolacca esculenta. Previous experiments have shown that it has strong anti-inflammatory effects. Tumour necrosis factor (TNF) is a very important inflammatory mediator. It is known that there are two types of TNF-TNFalpha is from macrophages/monocytes and TNFbeta is from activated lymphocytes. In order to study the mechanism of the anti-inflammatory effect of EsA, it was determined whether TNFalpha production from human peripheral monocytes was altered by EsA under lipopolysaccharide (LPS)-stimulated conditions. EsA was found to decrease TNFalpha production in a dose-dependent manner at concentrations higher than 1 mumol/l EsA. Recent studies have shown that EsA has a curative effect on chocolate cyst and other inflammatory diseases. Our previous studies have shown that EsA could reduce the release of platelet activating factor (PAF) from rat macrophages, and inhibit interleukin-1 and interleukin-6 production from routine macrophages. The reducing effects of EsA on the release of TNFalpha, IL-1, IL-6 and PAF may explain its anti-inflammatory effect.     

采后大蒜鳞茎的生理生化变化及其贮藏技术

采后大蒜鳞茎的生理生化变化及其贮藏技术刘淑娴,李月标,陈芳,张东林,蒋跃明（中国科学院华南植物研究所,广州５１０６５０）摘要大蒜鳞茎在室温下贮藏２个月后,胚芽开始生长．随着胚芽生长,呼吸速率、蛋白质和维生素Ｃ含量逐渐增高;而可溶性糖和干物质含量下降。...     

Cambrian lobopodians–ancestors of extant onychophorans?

This paper is a review of published information on fossil lobopodians, with addition of observations and ideas based on new material. It is also an analysis of the phytogeny of the group, and presents a new classification. A character shared by three or four families, yet not seen before, is a pair of enlarged sclerites covering the head. This forms an argument for re-orienting Hallucigenia once again. This genus no longer being enigmatic, a corner-stone in Stephen Jay Gould's evidence for extinct phyla is therefore gone. It is suggested that the lobopodians, phylum Lobopodia, are arranged in two classes, the extinct Xenusia for marine forms, and the Onychophora for terrestrial forms. The marine lobopodians are morphologically much more diverse than the extant onychophorans, a condition expressed in the classification. New taxa are: Hallucigenia fortis sp. nov., the families Luolishaniidae, Cardiodictyidae and Onychodictyidae, and the new orders Archonychophora, Scleronychophora and Paronychophora.     

IL-4-based helper activity of CD4 T cells is radiation sensitive

The capacity of CD4⁺ T cells to induce IgG synthesis in B cells has been known to be radioresistant for more than 20 years. However, the radiation sensitivity of helper T cells with regard to their ability to induce the synthesis of isotypes other than IgG has not been studied. We therefore irradiated KLH-primed lymph node T cells and examined their capacity to induce IgG, IgM, and IgE synthesis in hapten-primed B cells. We demonstrated that while the capacity of KLH-primed lymph node cells to induce IgG synthesis was not affected by irradiation, the capacity of such T cells to induce IgE synthesis was greatly reduced by γ-irradiation. This was consistent with our observations that IL-4 and IL-5 synthesis in such cells was greatly diminished by irradiation, whereas IL-2 synthesis was only minimally affected. A similar differential sensitivity to irradiation of the helper activity of Th1 and Th2 clones was observed with regard to their ability to induce IgE and IgG synthesis under cognate conditions. Irradiation greatly inhibited the capacity of Th2 clones to induce IgE synthesis, but only minimally affected the capacity of Th1 clones to induce IgG synthesis in primed B cells. The capacity of irradiated Th2 clones to induce IgE synthesis was restored by the addition of IL-4 and IL-5. These results taken together indicated that the sensitivity to irradiation of T helper cells with regard to the induction of IgE but not IgG synthesis was due to the sensitivity to irradiation of the production of IL-4 but not of IL-2. Thus, although some functions of CD4⁺ T cells are resistant to radiation, other functions, particularly those that depend on the production of IL-4 and IL-5, are greatly diminished by ionizing radiation.