The dependence of HNO2 mutagenesis in phage T4 on ligase and the lack of dependence of 2AP mutagenesis on repair functions

A temperature sensitive ligase allele of phage T4 reduced or eliminated HNO2 induced reversion of am mutants. Since at the temperatures used, the ligase mutant is defective in the repair of some types of lethal lesions (i.e., UV, MMS and EMS induced lesions) these results indicate that HNO2 mutagenesis may occur through a ligase dependent repair pathway. In contrast, 2AP induced mutation was not inhibited by mutants defective in the gene 30 ligase or in genes 32, 39, 41, 42, 44, 45, 46, 47, 49, 52, 56, 58-61 and v. This indicates that 2AP mutagenesis probably does not depend on a repair pathway in phage T4.     

Inbreeding and canine mammary cancer: a retrospective study

Using files of the Animal Neoplasm Registry (ANR) in Alameda and Contra Costa Counties, California, we conducted a retrospective study to compare the degree of inbreeding in the ancestry of purebred dogs with mammary and other cancers, and of those without tumors. Wright's coefficients of inbreeding, calculated for all animals in the three groups, ranged from 0.000 to 0.535. The median inbreeding coefficients of the mammary cancer and comparison groups (consisting of other cancers) were approximately twice that of the nonneoplastic group, but neither difference was statistically significant. Dogs with mammary adenocarcinoma and mixed mammary cancer had similar degrees of inbreeding.     

Relationship between dam's age at bull's birth and bull's genetic evaluation

After accounting for year of birth of bulls, younger dams produced superior sons. Bulls' PD, parent average, and pedigree index milk decreased with increasing age of dams at bull's birth. This appears to be due to decrease in maternal grandsire's PD milk and dam's Cow Index milk with increase in age of dam. Younger dams have an advantage of potentially higher genetic merit due to genetic trend but have less information included in their evaluations. Bull's latest parent average and pedigree index overestimated latest PD milk. This overestimation was not different with age of dam at bull's birth, suggesting that the bias in predicting bulls' PD from eventual evaluations of dams chosen at a younger age is not different than for dams chosen at a later age. Data were for 2826 bulls sampled by four AI organizations and born between 1965 and 1981. The increase in PD milk of bulls was about 27 kg/yr, but the trend was larger (45 kg/yr) during the last 5 yr. Inclusion of dam's age did not improve prediction of bull's PD milk. Maternal grandsire's PD milk was the primary variable associated with dam's age that accounted for lower bull's PD milk, mainly because older dams tended to have sires of lower genetic merit.     

纤维基材料的仿生学研究动向

纤维基技术的应用对仿生学的成功发展呈现出巨大的潜力,因为宇宙成物在生长过程、多毛结构和增强纤维方面具有许多相似性.约七年前,邓肯道夫纺织技术与工艺研究所协同众位生物学家一起开创了仿生学的研发,至今方兴未艾.     

Interactions in compatible polymer systems

Summary Dynamic mechanical measurements on polystyrene — poly(vinylmethylether) blends are demonstrating that the relaxation processes in the blends are mainly connected with the motions of the poly(vinylmethylether) chain.Concerning the effect of mixing on topological properties of the blends, an increase of the polydispersity of the relaxation processes is detected in blends with high molecular weight polystyrene while low molecular weight polystyrene exerts an effect of dilution upon the relaxation of the high molecular poly(vinylmethylether) chains.From these measurements as well as from thermoanalytical data it results that the energetic interaction is more pronounced in the blends with oligomeric than with high molecular weight polystyrene. The glass transition temperature shows a larger deviation from additivity for blends with high molecular polystyrene than for those with oligomeric polystyrene.Herrn Prof. Dr. M. Kryszewski zum 60. Geburtstag herzlichst gewidmet     

Buchbesprechungen

Ohne Zusammenfassung     

Buchbesprechungen

Ohne Zusammenfassung