An unusual Group 2 LEA gene family in citrus responsive to low temperature

Six cDNAs representing unique cold-induced sequences have been cloned from the hardy citrus relative Poncirus trifoliata. Among these, pBCORc115 and pBCORc119 were found to belong to the same gene family. Sequencing data indicated that pBCORc115 and pBCORc119 each contained an open reading frame, coding for a 19.8 kDa protein (COR19) and a smaller 11.4 kDa protein (COR11) respectively. Inspection of the deduced amino acid sequences revealed three large repeats in COR19, but only one was present in the COR11. Two elements: a Q-clustered tract and a K-rich motif were identified in each repeat. The K-rich motifs were similar to those of cotton D-11 and Group 2 LEA proteins. A Serine-cluster, a common feature in many Group 2 LEA-like proteins, was also found in these proteins, but it was in an unusual position at the carboxy-terminus. A bipartite motif of basic residues, similar to known nuclear targeting sequences, was also present in COR19 and COR11, suggesting that members of this protein family may have a nuclear targeting function. The expression of COR19 mRNA in response to cold acclimation, drought, flooding, and salinization was examined. COR19 expression in leaf tissue was induced in response to cold acclimation, but repressed during drought and flooding stress.     

Characterization of the IS895 family of insertion sequences from the cyanobacterium Anabaena sp. strain PCC 7120.

A family of repetitive elements from the cyanobacterium Anabaena sp. strain PCC 7120 was identified through the proximity of one element to the psbAI gene. Four members of this seven-member family were isolated and shown to have structures characteristic of bacterial insertion sequences. Each element is approximately 1,200 bp in length, is delimited by a 30-bp inverted repeat, and contains two open reading frames in tandem on the same DNA strand. The four copies differ from each other by small insertions or deletions, some of which alter the open reading frames. By using a system designed to trap insertion elements, one of the elements, denoted IS895, was shown to be mobile. The target site was not duplicated upon insertion of the element. Two other filamentous cyanobacterial strains were also found to contain sequences homologous to IS895.     

草鱼出血病病毒对其它鱼的感染性研究

用草鱼出血病病鱼分离出的草鱼出血病病毒(Grass carp hemorrhage virus,GCHV)感染其它常见鱼并用ELISA方法检查感染鱼组织提取液,结果表明:青鱼、鲢鱼、布氏鳌条对GCHV抗体呈阳性反应;鲤鱼、鳙鱼、鲫鱼、团头鲂、泥鳅则呈阴性反应。综合感染鱼发病症状及死亡特征,初步认为:青鱼对GCHV是易感的,GCHV能在鲢鱼、布氏蟹条体内增值,但毒力较低,鳙鱼、鲫鱼、团头鲂、鲤鱼、泥鳅能抗GCHV感染。     

Biotinylation of double stranded DNA after transamination

The bisulfite catalyzed transamination of cytidine and cytosine has been reported to be single strand specific, but local thermal instabilities of the DNA double helix, coupled with the extreme sensitivity of the Biotin-Avidin revelation methods, allows the random labelling of cytosines in d.s. DNA to detectable levels for those purposes where the overall label can be very low. We have evaluated the use of this reaction to prepare double stranded DNA molecules containing N4-aminoethyl-cytosine (4-aeC). After this step 4-aeC residues can be conjugated to biotinyl-n-hydroxysuccinimide ester yielding biotinylated DNA. This reaction allows the massive production of biotinylated probes. Labelled DNA can serve as molecular weight marker and positive control in Southern-blots. Moreover it can be useful in the study of DNA-protein interaction and in the isolation of d.s. DNA-binding proteins through chromatographic procedures.     

The expression of granulocyte/macrophage colony-stimulating factor in activated mouse lymphocytes declines with age

The expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) was studied in spleen lymphocytes isolated from male C57BL/6J mice of 6, 20, and 29 months of age. GM-CSF expression (biological activity and mRNA level) was maximum after culturing the lymphocytes for 45 hr with concanavalin A and phorbol myristate acetate. The induction of both GM-CSF activity and mRNA levels was observed to decline over 60% between 6 and 29 months of age. The age-related decline in the level of GM-CSF paralleled the age-related decline in the mRNA levels of interleukin-2 and interleukin-3.     

益生菌调控肠道屏障功能预防家禽球虫病的研究进展

球虫病给养禽业带来巨大经济损失,人们对绿色健康食品的迫切需求使球虫病的防控面临新的挑战.伴随世界"禁抗"进程的不断推进,家禽养殖业亟需一种安全有效的新型抗球虫方法.益生菌可竞争性排斥病原菌定殖以防止球虫病继发感染,可刺激宿主抗菌肽、黏蛋白和紧密连接蛋白的分泌以抵御球虫入侵,还可激活免疫反应以增强机体抗球虫感染的能力.本...