Biotransformation, by Enterobacter agglomerans, of pyrimidine acyclonucleosides to acyclonucleotides.

The ability of Enterobacter agglomerans to transform naturally occurring nucleosides into nucleotides has been utilized to transform newly synthesized pyrimidine acyclonucleosides into the corresponding acyclonucleotides. Unselected bacteria were used as the source of nucleoside phosphotransferase, the phosphate group donor being 4-nitrophenyl phosphate in the presence of Zn2+ ions. Optimal reaction conditions are outlined.     

Microbial degradation of bitumen

Summary A blown bitumen Mexphalte R 90/40 with a high content of saturated hydrocarbons was degraded by several microorganisms to the same extent. In batch cultures ofSaccharomycopsis lipolytica, maximal biodegradation was estimated to be about 9% w/w, 3.2·10^–3 g/cm² and 3.1·10^–3 cm of degraded bitumen. The Mexphalte R 90/40 degradation rate was closely coupled to biofilm formation. The microbial activity concerned predominantly the oxidation of saturated hydrocarbons. A direct distillation bitumen 80/100 with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons and resins was more resistant to biodegradation.     

Effect of 15(R)-15-methyl-prostaglandin E2 on iron absorption in the rat

Summary The administration of 15(R)-15-methyl prostaglandin E₂ (15(R)-15-M-PGE₂) in vivo significantly diminished the uptake of⁵⁹Fe into blood, spleen, liver, femur and dried intestine of rats, whereas acetylsalicylic acid (ASA) increased the counts significantly. This effect of ASA was counteracted by 15(R)-15-M-PGE₂. It is suggested that prostaglandins (PGs) might play an important role in inhibiting iron absorption at the intestinal level.This work was supported by grant No.6638 from CONICET (Argentina). The technical assistance of Mrs María E. Castro and Norma Rizzo is gratefully acknowleged.     

The Study of the Grit-blasting Parameters and Their Effects on the Adhesive Strength of the Plasma Sprayed Coatings

Surface Preparation is very important in adhesive b on ding of spray coatings to the surface of a work piece. The common practice is gr it-blasting of the surface before subjecting it to the spray coating process. In this study, grit-blasting of an AISI 4130 steel (of different heat treatmen ts) with Al 2O 3 particles was studied. Various grit-blasting parameters such as blasting particle size, the distance between blasting nozzle and the work pi ece (25, 30 and 40 cm.), blasting pressure (3,4,5,6 and ...     

Comparative study of the karyotypes of two Egyptian species of bats,Taphozous perforatus andTaphozous nudiventris (Chiroptera: Mammalia)

A detailed karyotypic analysis of two Egyptian species of bats,Taphozous perforatus andTaphozous nudiventris, was made on the basis of conventional data and G-band patterns. No detectable karyotypic difference was found between the two species (2n=42, F.N. 64). By comparison of G-band patterns, some differences between the two species were seen in the corresponding autosomal pairs. These results are reported for the first time in Egypt.     

Increased assembly of cytoskeletal proteins associated with the transformation of human liver cells into fibroblast-like cells.

A topoisomerase II inhibitor, novobiocin, and a deacetylase inhibitor, butyrate, synergistically transformed human liver cells into fibroblast-like cells. This morphological change was associated with an increased production of procollagen type III peptide and a simultaneous assembly of actin, tubulin, vimentin and cytokeratin. Novobiocin and butyrate had no marked effect on the phosphorylation state of cytokeratin proteins, but synergistically enhanced [3H]acetate uptake. From these results, it can be speculated that protein acetylation plays an important role in inducing the assembly of cytoskeletal proteins and the morphological transformation of human liver cells.     

新世纪图书馆员社会角色转换研究综述

就近几年图书馆界关于新世纪馆员意识转换及社会角色转换等方面的研究进行了综述，指出新时期的馆员要实现自我社会角色的转换，首先是要明确转换的必要性，然后采取有效的策略逐步地、系统地推进转换，才能取得较好的效果。     

The behavior of the homozygous and heterozygous sub-types of rats which are genetically-selected for diabetes insipidus: A comparison with Long Evans and Wistar stocks

Several aspects of spontaneous and conditioned behavior (food and water intake, locomotion and emotionality, passive and active avoidance acquisition and retention) of standard (albino and pigmented) rats, and rats heterozygous (HEDI) and homozygous (HODI) for diabetes insipidus, are reviewed. As would be expected, HODI rats have been repeatedly found to consume far more fluid than either HEDI or control rats. Pigmented rats appear to be more active than albinos. HODI rats exhibit less marked emotional responses than do control rats, among which the pigmented ones exhibit the highest emotionality. Light aversion is more evident in albino than in pigmented rats. No differences are found among HEDI, HODI and normal Long Evans rats. It is quite difficult to provide a clear-cut statement concerning inter-strain differences in passive avoidance behavior, possibly because of the variety of techniques employed. In any case, HODI rats do not perform worse than normal controls do. In one-way active avoidance paradigms, pigmented rats perform better than albinos, and the performance of HODI rats does not differ from that of controls. In two-way avoidance paradigms, albinos appear to outperform pigmented rats. Once again, there are no obvious differences between HODI and control animals.In addition to indicating that HODI rats may actually be less emotional than the other groups of rats reviewed here, the studies described once again fail to confirm the previously alleged functions of vasopressin in memory consolidation.     

Sound communication inNezara viridula (L.) (Heteroptera: Pentatomidae): Further evidence that signal transmission is substrate-borne

We investigated the sound communication associated with mating inNezara viridula (L.) to clarify conflicting reports on the medium through which acoustic signals are borne. Recordings made from virgin pairs ofN. viridula during precopulatory and compulatory behaviour have revealed that signals transmitted as vibrations through the substrate are a more likely means of communication than signals transmitted by a radiation of sound pressure waves through the air (at least in Australian populations). We present evidence (additional to that already in the literature) that air-borne acoustics are an unlikely mechanism of sexual communication in this species. Specifically, the recorded pulse train patterns showed no consistency or repeatability in relation to different stages of mating behaviour. In contrast, frequency spectrograms of substrate-borne signals reveal repeatable patterns that do correspond with the stage of mating behaviour.