云南叶螨属一新种(蜱螨目:叶螨科)

在鉴定云南叶螨标本时,发现叶螨属一新种,现记述如下。模式标本保存于上海农学院。本文量度单位均为微米。 食禾叶螨Tetranychus graminivorus新种(图1—14) 雌螨 体长(包括喙)454,宽298。椭圆形。浅黄绿色。须肢端感器圆柱形,长6.8,     

Specific detection of N-acetylglucosamine-containing oligosaccharide chains on ovine submaxillary asialomucin

Human milk beta-N-acetylglucosaminide beta 1 leads to 4-galactosyltransferase (EC 2.4.1.38) was used to galactosylate ovine submaxillary asialomucin to saturation. The major [14C]galactosylated product chain was obtained as a reduced oligosaccharide by beta-elimination under reducing conditions. Analysis by Bio-Gel filtration and gas-liquid chromatography indicated that this compound was a tetrasaccharide composed of galactose, N-acetylglucosamine and reduced N-acetylgalactosamine in a molar ratio of 2:0.9:0.8. Periodate oxidation studies before and after mild acid hydrolysis in addition to thin-layer chromatography revealed that the most probable structure of the tetrasaccharide is Gal beta 1 leads to 3([14C]Gal beta 1 leads to 4GlcNAc beta 1 leads to 6)GalNAcol. Thus it appears that Gal beta 1 leads to 3(GlcNAc beta 1 leads to 6)GalNAc units occur as minor chains on the asialomucin. The potential interference of these chains in the assay of alpha-N-acetylgalactosaminylprotein beta 1 leads to 3-galactosyltransferase activity using ovine submaxillary asialomucin as an acceptor can be counteracted by the addition of N-acetylglucosamine.     

Unique acceptors for poly(ADP-ribose) in resting,proliferating and DNA-damaged human lymphocytes

Acceptor proteins for poly(adenosine diphosphoribosyl)ation were determined in resting human lymphocytes, in lymphocytes with N-methyl-N′-nitro-N-nitrosoguanidine-induced DNA damage and in lymphocytes stimulated to proliferate by phytohemagglutinin. Kinetic studies showed that the increase in ADP-ribosylation which occurred in response to N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) treatment was greater in magnitude but more transient in duration than that which occurred in phytohemagglutinin-stimulated cells. Gel electrophoretic analyses revealed that MNNG treatment and phytohemagglutinin stimulation both caused an increase in ADP-ribosylation of poly(ADP-ribose) polymerase and core histones. In MNNG-treated cells, an increase in ADP-ribosylation of histone H1 was also observed. In contrast, phytohemagglutinin-stimulated cells showed no increase in ADP-ribosylation of histone H1. In MNNG-treated cells there was also ADP-ribosylation of a protein of molecular weight 62 000, while in phytohemagglutinin-stimulated cells there was a marked increase in ADP-ribosylation of a protein of molecular weight 96000. MNNG treatment of phytohemagglutinin-stimulated cells produced a pattern of ADP-ribosylation that appeared to be due to the combined effects of the individual treatments. 3-Aminobenzamide effectively inhibited ADP-ribosylation under all treatment conditions.     

Scanning Electron Microscopic Studies of Candida albicans

A scanning electron microscopic study of selected morphological stages of Candida albicans is presented. Stages represented are budding yeast cells, mycelial-like forms, chlamydospores, germ tube formation, and an unusual rough cell type.     

Esterases of Drosophila II. Biochemical Studies of Esterase-5 in D. pseudoobscura

In vitro enzyme hybridization was carried out with combinations of six allozymic variants of Esterase-5 from Drosophila pseudoobscura. Studies on heat stability and specific activity changes accompanying hybridization were done to examine the possible expression of overdominance at the biochemical level. In 11 of 15 combinations no significant change in specific activity was found following hybridization. In two cases hybridization resulted in a decrease in activity in the mixture, while in two cases esterase activity was elevated. Heat stability studies, in several cases, revealed reduced rates of inactivation in in vitro and in vivo heterozygotes compared with homozygotes. From these and other data a model for the molecular mechanism of heterosis is presented.     

The production, isolation, and characterization of a grisein-like sideromycin complex

Streplomyces griscus var. X-2455 produces an antibiotic complex which is active in vitro against a number of gram-positive and gram-negative bacteria and in mice against systemic infections caused by K, pneumoniae and D, pneumoniac. In view of the favorable chemotherapeutic index and the broad in vitro spectrum of crude concentrates, isolation of the pure antibiotic complex and the individual constituents was undertaken. The antibiotics referred to as Ho 5-2667, Ro 7-7730, and Ho 7-7731 can be differentiated by tle, ultraviolet light absorption spectra, and in vitro antibacterial activities. They all contain iron and may be classified as sideromycins. From antibiotic concentrates an antibacterially inactive substance was isolated and identified as N-acetyltyramine.     

Gene products of Amphiuma: An amphibian with an excessive amount of DNA

The nuclei of Amphiuma contain 168 pg of DNA, 28 times that contained in human nuclei. Although many higher organisms appear to possess an excessive amount of DNA, in Amphiuma this has been carried to the extreme. Studies of this organism thus may provide some insight into how this excess DNA is used. This organism presumably evolved by numerous polyploidy and gene duplication events. Do its gene products present multiple electrophoretic forms? Are they quantitatively increased to the same degree as the DNA? Electrophoresis of Amphiuma glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, acid phosphatase, lactic dehydrogenase, and hemoglobin failed to show any evidence for multiple electrophoretic forms of these respective gene products. The amount of hemoglobin, G6PD, and 6PGD per red cell was increased to a comparable or even greater degree than the DNA. Analytical ultracentrifugation demonstrated a satellite band of DNA with a density of 1.720 corresponding to a GC content of 61%. This probably represents DNA coding for ribosomal RNA. Electron microscopy of liver nuclei showed a significant amount of condensed chromatin. The implications of these observations are discussed.