Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

大鼠发育过程中肝、肺r-GT酶活性和定位

用生物化学和组织化学方法研究正常发育中大鼠肝、肺r-GT活性和定位。结果表明:肝r-GT活性自胚龄17天开始升高,21天达高峰,出生第一天明显降低,第六天降至接近成年低水平。在胚胎期肝r-GT主要位于肝细胞内,出生后则主要位于胆小管。该结果提示胚胎期肝r-GT主要参与肝细胞膜上氨基酸的转运。出生后可能主要参与解毒功能,大鼠肺r-GT活性随发育逐步升高,主要分布于肺支气管上皮细胞。提示肺r-GT可能参与解毒功能。     

Platelet-collagen interaction. Inhibition by a monoclonal antibody raised against collagen receptor

Monoclonal antibodies to the purified platelet type I collagen receptor were produced to study platelet receptor function. The antibody specifically reacted with the platelet receptor in immunoblot experiments. The IgG purified from the monoclonal antibodies and isolated Fab' fragments inhibited the binding of radiolabeled alpha 1(I) chain to washed platelets competitively. Soluble and fibrillar type I collagen-induced platelet aggregations were inhibited by purified IgG suggesting that soluble and fibrillar collagens shared a common receptor. The adhesion of platelets to an artificial collagen matrix was also inhibited by the monoclonal antibody. However, adenosine diphosphate-induced platelet aggregation was not inhibited by the same amount of IgG that inhibited collagen-induced platelet aggregation. The results suggest that collagen-induced platelet aggregation is mediated through the interaction of collagen with the platelet receptor.     

Retention of enzymatic activity by N-terminal domain (1-78) T4-lysozyme: expression of synthetic DNA in Escherichia coli

DNA of 235 b.p. coding for N-terminal domain (1-78) T4-lysozyme was synthesized and cloned by ligating twelve synthetic fragments with a linearized plasmid pUCE8 followed by transformation. On expression in E. coli strain JM103 cells, colonies containing the synthetic DNA were found to be lytic. On purification, clone ptly. 23-5 was found to contain polypeptide (M.W. 10,500), corresponding to N-terminal domain, its dimeric and aggregate form. It was identified by amino acid sequence analysis of the dimeric form.     

Nucleotide sequence structure and consistency of a developmentally regulated DNA deletion in Tetrahymena thermophila.

DNA deletion by site-specific chromosome breakage and rejoining occurs extensively during macronuclear development in the ciliate Tetrahymena thermophila. We have sequenced both the micronuclear (germ line) and rearranged macronuclear (somatic) forms of one region from which 1.1 kilobases of micronuclear DNA are reproducibly deleted during macronuclear development. The deletion junctions lie within a pair of 6-base-pair direct repeats. The termini of the deleted sequence are not inverted repeats. The precision of deletion at the nucleotide level was also characterized by hybridization with a synthetic oligonucleotide matching the determined macronuclear (rejoined) junction sequence. This deletion occurs in a remarkably sequence-specific manner. However, a very minor degree of variability in the macronuclear junction sequences was detected and was shown to be inherent in the mechanism of deletion itself. These results suggest that DNA deletion during macronuclear development in T. thermophila may constitute a novel type of DNA recombination and that it can create sequence heterogeneity on the order of a few base pairs at rejoining junctions.     

记辽宁东部新鳞齿鱼属一新种

本文记述了产自辽宁东部红庙子盆地下桦皮甸子组的新鳞齿鱼属—新种——Neolepidotes liaodongensis sp. nov..根据新材料,将 Neolepidotes 与 Lepidotes 等属作了补充比较,增订了新鳞齿鱼属的特征.     

Lysophosphatidylcholine metabolism and lipoprotein secretion by cultured rat hepatocytes deficient in choline.

A protein kinase activity was identified in pig brain that co-purified with microtubules through repeated cycles of temperature-dependent assembly and disassembly. The microtubule-associated protein kinase (MTAK) phosphorylated histone H1; this activity was not stimulated by cyclic nucleotides. Ca2+ plus calmodulin, phospholipids or polyamines. MTAK did not phosphorylate synthetic peptides which are substrates for cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase. Ca2+/calmodulin-dependent protein kinase II, protein kinase C or casein kinase II. MTAK activity was inhibited by trifluoperazine [IC50 (median inhibitory concn.) = 600 microM] in a Ca2+-independent fashion. Ca2+ alone was inhibitory [IC50 = 4 mM). MTAK was not inhibited by heparin, a potent inhibitor of casein kinase II, nor a synthetic peptide inhibitor of cyclic AMP-dependent protein kinase. MTAK demonstrated a broad pH maximum (7.5-8.5) and an apparent Km for ATP of 45 microM. Mg2+ was required for enzyme activity and could not be replaced by Mn2+. MTAK phosphorylated serine and threonine residues on histone H1. MTAK is a unique cofactor-independent protein kinase that binds to microtubule structures.     

E.p.r.-spectroscopic studies on the molybdenum-iron site of nitrogenase from Clostridium pasteurianum.

The e.p.r. spectroscopy of the nitrogenase molybdenum-iron protein from Clostridium pasteurianum was re-investigated. The sharpness of the delta Ms = +/- 3 g'z peak from the +/- 3/2 Kramer's doublet enables the observation and quantification of incompletely resolved hyperfine splittings from the stable magnetic nuclei 95Mo and 57Fe in samples enriched in these isotopes. No couplings to 1H or 17O could be discerned by examination of spectra from samples exchanged into 2H2O and H2(17)O respectively. Simulation of the spectrum from 95Mo-enriched samples yields a hyperfine coupling of 2.9 MHz, and indicates that the earlier electron-nuclear-double-resonance-derived estimate of 8.1 +/- 0.2 MHz is substantially in error.     

Genetic convergence during serial in vitro passage of a polyclonal squamous cell carcinoma

A cell line was established from an in situ squamous cell carcinoma of the skin (Bowen's disease), and its in vitro karyotypic evolution was cytogenetically analyzed. Initially, considerable genetic heterogeneity was evident. Nine cytogenetically abnormal clones, eight of which were apparently unrelated, were found among the 83 metaphases analyzed from the primary culture and the first passage. With increasing time in culture this complexity was reduced, so that a single clone dominated passages 7-11. The clone that emerged from this genetic convergence had a t(12;17)(p13;q21) as the sole abnormality. Our findings indicate that the cytogenetic multiclonality that has been repeatedly detected in short-term cultures of squamous cell carcinomas is not caused by the in vitro conditions. Instead, the principles of Darwinian selection apply: the altered, but stable, selection pressure facing a newly established and initially multiclonal cell line will lead to a reduction of genetic heterogeneity until the one clone that now has the proliferative advantage outgrows the other subpopulations.