Cloning and sequence analysis of cDNA for bovine carboxypeptidase E

Carboxypeptidase E (enkephalin convertase) was first identified as the carboxypeptidase B-like enzyme involved in the biosynthesis of enkephalin in bovine adrenal chromaffin granules. A similar enzyme is present in many brain regions and in purified secretory granules from rat pituitary and rat insulinoma. Within the secretory granules, carboxypeptidase E (CPE) activity is found in both a soluble and a membrane-bound form, which differ slightly in relative molecular mass (Mr). Here, to investigate whether the CPE activities in the various tissues are produced from a single gene, purified CPE was partially sequenced and oligonucleotide probes were used to isolate a clone encoding CPE from a bovine pituitary complementary DNA library. This cDNA hybridizes to bovine pituitary poly(A)+ RNAs of approximately 3.3, 2.6 and 2.1 kilobases (kb), with the 3.3-kb messenger RNA the predominant species. The predicted amino-acid sequence of the cDNA clone contains the partially determined sequences of CPE, several pairs of basic amino acids and displays some homology with both carboxypeptidases A and B. Restriction analysis of bovine genomic DNA suggests only one gene for CPE. This is consistent with a broad role for CPE in the biosynthesis of many neuropeptides.     

A study and critique of the teaching of the history of science and technology. Interim report by the committee on undergraduate education of the history of science society (U.S.A.)

A great deal is known about the technical issues surrounding the introduction of Hugo De Vries's mutation theory and the subsequent development of the modern genetical theory of natural selection. But so far little has been done to relate these events to the wider issues of the time. This article suggests that extra-scientific factors played a significant role, and substantiates this by comparing De Vries's respect for the original Darwinian spirit with Thomas Hunt Morgan's use of the mutation theory as part of an attack on the whole philosophy of Darwinism. In particular, it is argued that Morgan's attitude was dictated by his moral objections to the picture of a world dominated by struggle.     

Population dynamics of the bark-dwelling spider Eustala perfida Mello-Leitão, 1947 (Araneidae)

Population dynamics of spiders may vary according to biotic and abiotic factors. We studied the phenology of the bark-dwelling spider Eustala perfida over a two-year period and investigated how temperature, precipitation, and prey availability were associated with the population of this species. The population of E. perfida presented a well-defined fluctuation, with one reproductive cycle per year. The recruitment of spiders occurred in summer, followed by successive phenological peaks at all stages of development. The species is protogynic, and the population of adult males peaks in the cold/dry season, indicating a winter mature phenological pattern. The diet of E. perfida is composed mainly of medium-sized homopterans, complemented by small dipterans and hymenopterans. We found that the higher abundance of spiders occurred two months after the highest values of precipitation and temperature, and three months after the higher abundance of potential prey items. These results indicate that spiders require time to respond to changes in environmental conditions. The species’ natural history and the structure of the trunks in which it lives may also affect the number of individuals in a particular area and over time.     

影响聚丙烯酰胺在土壤和水分管理应用的因素

水溶性阴离子聚丙烯酰胺(PAMs)。因其影响土壤的分散、结絮和团聚作用，稳定土壤的结构争提高土壤的渗流，使得土壤地表水的径流、土壤侵蚀和板结程度降低到最小。已被应用于不同的农业目标来有效地控制土壤侵蚀、保护地下水水质和显著地降低动物废弃水中的细菌和养分含量。对影响PAM在土壤和水分管理应用的因素，从土壤和水特性包括土壤质地、溶解盐的浓度、有机质含量对PAM吸附的影响，PAM分子量及其电荷在土壤渗透作用中的作用等两方面进行了评述，介绍了PAM在土壤和水中降解与环境安全问题和今后研究的某些方向。参36。