High K+-induced release of somatostatin from the cortical preparation of rat brain.

Release of endogenous somatostatin (SRIF) from the rat cerebral cortical slices incubated in Krebs-bicarbonate buffer was increased from the basal rate of 3.4 +/- 0.6% of the total SRIF content in 15 min at [K+]o = 5.6 mM, to 13.1 +/- 1.6% upon raising the [K+]o to 56.6 mM. The high-K+ evoked SRIF release was absent when Ca++ in the medium was replaced by Mn++. The isolated synaptosomes from rat cerebral cortex contain 13.2 +/- 3.1 ng SRIF/mg protein compared to 0.33 +/- 0.01 ng/mg protein in the cortical tissue as a whole, suggesting that nerve terminals are the main source of the peptide released upon membrane depolarization.     

A meiotic gene conversion gradient opposite to the direction of transcription.

Genetic recombination involves classical crossing-over and gene conversion (aberrant segregation). In fungi that produce an ascus containing four spores, a gene conversion event is manifested as 3:1 or 1:3 (or more rarely 4:0 or 0:4) segregations, in contrast to the normal mendelian 2:2 segregation. Polarity is one of the properties of gene conversion; in almost all cases the frequency of conversion exhibits a gradient across the gene monitored. The frequency of conversion is usually independent of the specific allele used as a marker, but dependent on its location. An interpretation of conversion polarity is that it is caused by the existence of specific initiation sites for meiotic recombination, located at the high end of the polarity gradient. Here we show that the polarity gradient for the HIS2 gene of Saccharomyces cerevisiae is high at the 3' end of the gene, implying that the promoter of HIS2 is not the initiation site.     

危机期间践行良好的科学

 科学共同体是人类文明中一种特有的组织，是科学家在科学活动中通过相对稳定的联系而结成的组织和团体，是集体科学劳动的一般社会存在形式。科学发展极大地推动了社会进步，科学与社会的联系比过去更加紧密，科学共同体的社会责任也在不断增强，本次新冠肺炎疫情在全球形势严峻，也暴露出科学共同体开展推进开放合作的迫切性。发展科学知识、服务人类社会是科学共同体的价值担当，也是科技期刊和出版机构应承担的责任。面对抗击新冠肺炎疫情的重大挑战，在疫情爆发之时，作为科技期刊和出版商，我认为在危急时刻，科技期刊和出版商在信息处理方面的表现尤为重要，要保证信息的可发现性、具备能快速应对大量的信息的能力以及确保信息有价值。     

Crystal structure and molecular interactions of tropomyosin.

The three-dimensional structure of tropomyosin filaments has been determined by X-ray crystallography. The ends of the molecules were located by reference to the single pair of cysteine residues. Departures from the alpha-helical-coiled coil conformation may occur in localised domains along the molecule as well as at the overlapping ends.