Seminiferous tubule transfection in vitro to define post-meiotic gene regulation

Background  

Post-meiotically expressed genes in the testis are essential for the proper progression of spermatogenesis, and yet, aside from the construction of individual transgenic mice using specific promoters to drive reporter plasmids, there are only very limited possibilities for relevant and quantitative analysis of gene promoters. This is due to the special nature of post-meiotic haploid cells, which to date are not represented in any appropriate cell-lines. This article reports the development of novel methodology using isolated and cultured rat seminiferous tubules in a multiwell format, into which promoter-reporter constructs can be introduced by a combination of microinjection and electroporation.     

Experimentelle analyse der infektion und des entwicklungszyklus vonMalamoeba scolyti inDryocoetes autographus [Coleoptera: scolytidae]

Malamoeba scolyti (Purrini), ein Parasit im Verdauungstrakt des BorkenkäfersDryocoetes autographus (Ratz.), schmarotzt intrazellulär in bestimmten Abschnitten des Mitteldarmepithels und im Epithel der Malpighischen Gefä\e. Sie zerstört die befallenen Epithelzellen, wobei sie sich bis zum zystenstadium entwickeln kann. in umfangreichen Infektionsexperimenten wird gezeigt, daß die Infektion in den vordersten Krypten des Mitteldarms beginnt und sich in mehreren Infecktionswellen bis zu den hintersten Darmdivertikeln und den Malpighischen Gefäßen ausbreitet. Bei 20° Dauertemperatur nimmt die Erstinfektion etwa 6 Tage, der gesamte Krankheitsverlauf bis zum Exitus des Wirtes 5 bis 7 Wochen in Anspruch. Im Gegensatz zu anderen Beschreibungen konnte nur eine einzige Form von Trophozoiten beobachtet werden. Auf die mögliche Bedeutung dieses Umstandes für die taxonomische Identität der Amöbe wird hingewiesen.     

The rad16 gene of Schizosaccharomyces pombe: a homolog of the RAD1 gene of Saccharomyces cerevisiae.

The rad10, rad16, rad20, and swi9 mutants of the fission yeast Schizosaccharomyces pombe, isolated by their radiation sensitivity or abnormal mating-type switching, have been shown previously to be allelic. We have cloned DNA correcting the UV sensitivity or mating-type switching phenotype of these mutants and shown that the correcting DNA is encompassed in a single open reading frame. The gene, which we will refer to as rad16, is approximately 3 kb in length, contains seven introns, and encodes a protein of 892 amino acids. It is not essential for viability of S. pombe. The predicted protein is the homolog of the Saccharomyces cerevisiae RAD1 protein, which is involved in an early step in excision-repair of UV damage from DNA. The approximately 30% sequence identity between the predicted proteins from the two yeasts is distributed throughout the protein. Two-hybrid experiments indicate a strong protein-protein interaction between the products of the rad16 and swi10 genes of S. pombe, which mirrors that reported for RAD1 and RAD10 in S. cerevisiae. We have identified the mutations in the four alleles of rad16. They mapped to the N-terminal (rad10), central (rad20), and C-terminal (rad16 and swi9) regions. The rad10 and rad20 mutations are in the splice donor sequences of introns 2 and 4, respectively. The plasmid correcting the UV sensitivity of the rad20 mutation was missing the sequence corresponding to the 335 N-terminal amino acids of the predicted protein. Neither smaller nor larger truncations were, however, able to correct its UV sensitivity.     

慢性心功能不全大鼠心脏和血淋巴细胞β-肾上腺素受体的改变

在主动脉与肾动脉缩窄造成的慢性心功能不全大鼠,血浆儿茶酚胺浓度增高;心脏β-肾上腺素受体(β-AR)数量增加,其中β_1-AR及其mRNA增加,而β_2-AR及其mRNA不变;左心房异丙基肾上腺素(ISO)浓度-收缩效应曲线右移;而心肌ISO浓度-cAMP蓄积曲线无显著改变;血淋巴细胞β-AR数量显著减少.结果提示心功能不全时心脏β_1-AR数量增多,但其介导的正性变力效应反而降低,在cAMP生成以后的信号转导过程或心肌收缩成分功能存在障碍,而血淋巴细胞β-AR的改变与心脏β-AR的功能改变平行.     

Tetrazolium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction by mycoplasmas.

We investigated 22 mycoplasma and acholeplasma species for their ability to reduce tetrazolium salts by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The test results were evaluated visually, as well as spectrophotometrically, by using an enzyme-linked immunosorbent assay reader. Our results were very similar to the results obtained when the tetrazolium salt reduction assay described by Aluotto et al. was used. However, the MTT reduction assay appeared to be better because it is faster, more objective and sensitive, easier to evaluate, and less expensive; in addition, it allows quantitative determinations. By using regression analysis a linear correlation between formazan production and the number of colony-forming units was demonstrated for all of the species investigated, indicating that the MTT assay can also be used for growth, toxicity, or chemosensitivity tests for the mycoplasma species that are capable of reducing tetrazolium salts.     

乳源耐甲氧西林金黄色葡萄球菌icaA/D基因缺失株的构建及其生物被膜形成能力与耐药性分析

[背景]耐甲氧西林金黄色葡萄球菌(Methicillin Resistant Staphylococcus aureus,MRSA)是一种具有多重耐药性的人畜共患病原菌,常引起奶牛乳房炎等疾病.形成生物被膜是MRSA重要的耐药机制之一.研究发现ica操纵子调控的胞间多糖黏附素(Polysaccharide Interc...