A SPOROPHYTE CELL WALL PROTEIN OF THE RED ALGA PORPHYRA PURPUREA (RHODOPHYTA) IS A NOVEL MEMBER OF THE CHYMOTRYPSIN FAMILY OF SERINE PROTEASES1

A complementary DNA (cDNA) clone from a Porphyra purpurea (Roth) C. Agardh sporophyte-specific subtracted cDNA library was found to encode a protein similar to serine proteases of the chymotrypsin class. The encoded protein contains a typical signal peptide and is particularly similar to chymotrypsins in the regions surrounding the active site residues and the activation site where cleavage of the propeptide occurs. In addition, the six cysteine residues characteristic of chymotrypsins are conserved. However, two of the three residues of the active site His/Asp/Ser charge relay triad have been replaced, indicating that the protein is unlikely to have peptidase activity. Northern hybridization confirmed that this cDNA is derived from an abundant, sporophyte-specific messenger RNA (mRNA). The presence of signal peptide on the encoded protein and the abundance of its mRNA suggested that this protein might be localized in the cell wall. Consequently, sporophyte cell walls were isolated and a major protein having a molecular weight similar to that estimated for the encoded protein was purified. N-terminal sequence analysis indicated that this cell wall protein is identical to that encoded by the cDNA with the amino terminus of the mature protein beginning at the activation site. This cell wall structural protein appears to have evolved from a chymotrypsin-like progenitor but has been adapted to bind cell wall proteins and/or polysaccharides rather than to cleave proteins.     

盐胁迫对不同抗盐性小麦叶片荧光诱导动力学的影响

以不同抗盐性小麦为材料,研究了ＮａＣｌ胁迫对叶片叶绿素ａ荧光诱导动力学的影响。指出１５０ｍｍｏｌ／ＬＮａＣｌ使小麦幼苗生长降低,叶绿素含量下降,同时使光系统Ⅱ的潜在光化学活性和原初光能转化率降低,使光反应受到抑制。     

TAR载体克隆染色体目的片段的研究进展

分离染色体DNA上的目的片段,对其进行结构及功能的分析,对于发现新基因,研究基因功能都具有很大的意义。利用TAR克隆技术可以直接从基因组中分离所需的目的片段,这比传统的通过筛库获得目的片段的方法简便、快速、准确并且特异性强 。     

肝X受体α在泡沫细胞胆固醇流出中的调控作用

以THP-1巨噬细胞源性泡沫细胞为研究对象,观察肝X受体α(LXRα)在THP-1巨噬细胞源性泡沫细胞胆固醇流出中的调控作用.结果发现,22(R)-羟基胆固醇剂量依赖性增加THP-1巨噬细胞源性泡沫细胞胆固醇流出, 而DIDS剂量依赖性减少THP-1巨噬细胞源性泡沫细胞胆固醇流出.逆转录聚合酶链反应显示, 22(R)-羟基胆固醇可增加THP-1巨噬细胞源性泡沫细胞LXRα mRNA的表达, DIDS可抑制THP-1巨噬细胞源性泡沫细胞LXRα mRNA的表达.结果提示,LXRα在巨噬细胞源性泡沫细胞胆固醇流出中起着重要的调控作用,这为开发和寻找抗动脉粥样硬化药物提供了新的思路.     

Overexpression of TaHSF3 in Transgenic Arabidopsis Enhances Tolerance to Extreme Temperatures

Heat shock factors (HSFs) in plants regulate heat stress response by mediating expression of a set of heat shock protein (HSP) genes. In the present study, we isolated a novel heat shock gene, TaHSF3, encoding a protein of 315 amino acids in wheat. Phylogenetic analysis showed that TaHSF3 belonged to HSF class B2. Subcellular localization analysis indicated that TaHSF3 localized in nuclei. TaHSF3 was highly expressed in wheat spikes and showed intermediate expression levels in roots, stems, and leaves under normal conditions. It was highly upregulated in wheat seedlings by heat and cold and to a lesser extent by drought and NaCl and ABA treatments. Overexpression of TaHSF3 in Arabidopsis enhanced tolerance to extreme temperatures. Frequency of survival of three TaHSF3 transgenic Arabidopsis lines was 75–91 % after heat treatment and 85–95 % after freezing treatment compared to 25 and 10 %, respectively, in wild-type plants (WT). Leaf chlorophyll contents of the transformants were higher (0.52–0.67 mg/g) than WT (0.35 mg/g) after heat treatment, and the relative electrical conductivities of the transformants after freezing treatment were lower (from 17.56 to 18.6 %) than those of WT (37.5 %). The TaHSF3 gene from wheat therefore confers tolerance to extreme temperatures in transgenic Arabidopsis by activating HSPs, such as HSP70.     

刺激黄雀新纹状体前部大细胞核外侧部对发声和呼吸的影响

实验材料为乌拉坦麻醉的鸣禽黄雀（Ｃａｒｄｕｅｌｉｓ ｓｐｉｎｕｓ）。观察了电及化学刺激新纹状体前部大细胞核外侧部（１ＭＡＮ）对发声和呼吸的影响。结果如下：（１）电刺激１ＭＡＮ的不同区域都引起鸣叫反应。（２）长串电脉冲刺激１ＭＡＮ使呼吸频率增加,呼吸幅度降低。（３）短串电脉冲刺激１ＭＡＮ,落位于吸气相,产生吸气要断效应;落位于呼气相,可使呼气时程延长,以冲刺激１ＭＡＮ,落位于吸气相,产生吸气切断效应     

Fas is not essential for lamina propria T lymphocyte homeostasis

IL-2 receptor alpha-deficient (IL2Ralpha-/-) mice spontaneously accumulate vast numbers of intestinal lamina propria (LP) T cells and develop bowel inflammation. The accumulation of T cells in IL2Ralpha-/- mice is thought to result, in part, from defective Fas-induced cell death. To understand the role of cell proliferation and death in regulating LP T cells in IL2Ralpha-/- mice, we have directly examined the proliferation and Fas sensitivity of wild-type, lpr/lpr, and IL2Ralpha-/- LP T cells. In wild-type mice, 5'-bromodeoxyuridine (BrdU) labeling and Fas susceptibility are greatest in CD44Hi LP T cells. Fas-deficient lpr/lpr mice have normal total numbers of LP T cells, despite an increased proportion of BrdU+ T cells. By contrast, IL2Ralpha-/- mice possess increased total numbers of LP T cells, despite normal proportions of BrdU+ LP T cells. Finally, wild-type and IL2Ralpha-/- LP T cells are equivalently Fas sensitive. These results demonstrate that LP T cells proliferate and are Fas-sensitive cells. IL2Ralpha-/- mice accumulate a large number of these Fas-sensitive LP T cells and clearly differ from Fas-deficient lpr/lpr mice in this regard. Thus our studies reveal that Fas is dispensable for LP T cell homeostasis and suggest that the intestinal inflammation observed in IL2Ralpha-/- mice is independent of defective Fas-induced cell death.     

In situ hydrogen utilization for high fraction acetate production in mixed culture hollow-fiber membrane biofilm reactor

Syngas fermentation is a promising route for resource recovery. Acetate is an important industrial chemical product and also an attractive precursor for liquid biofuels production. This study demonstrated high fraction acetate production from syngas (H₂ and CO₂) in a hollow-fiber membrane biofilm reactor, in which the hydrogen utilizing efficiency reached 100 % during the operational period. The maximum concentration of acetate in batch mode was 12.5 g/L, while the acetate concentration in continuous mode with a hydraulic retention time of 9 days was 3.6?±?0.1 g/L. Since butyrate concentration was rather low and below 0.1 g/L, the acetate fraction was higher than 99 % in both batch and continuous modes. Microbial community analysis showed that the biofilm was dominated by Clostridium spp., such as Clostridium ljungdahlii and Clostridium drakei, the percentage of which was 70.5 %. This study demonstrates a potential technology for the in situ utilization of syngas and valuable chemical production.