Regeneration of NAD(+) cofactor by photosensitized electron transfer in an immobilized alcohol dehydrogenase system

The irradiation with visible light of a photosensitizer dye like methylene blue was used to regenerate by electron transfer the oxidized form of a pyridine nucleotide coenzyme (NAD(+)). The process has been studied on a common enzymatic reaction: ethanol oxidation by alcohol-NAD(+) oxidoreductase immobilized on polyacrylamide gel or porous glass balls. In the experimental conditions used, the initial NAD(+) recycling rates were 2.33 x 10(4) cycles/h (polyacrylamide) and 3 x 10(4) cycles/h (glass balls). A total number of 49.5 x 10(4) cycles was obtained for 13 runs of 2 h. The enzyme immobilization strongly increased its stability: after 28 days at 20 degrees C, the residual activity was 25% of the initial value.     

Regular and irregular divisions of Lepidoptera spermatocytes as related to the speed of meiotic prophase

Lepidoptera males bear two kinds of meiotic divisions. One is regular (eupyrene) and leads to nucleate, fertilizing spermatozoa. The other (apyrene) shows metaphase I chromosomes clumping together into irregular masses which later split forming daughter cells with unbalanced sets of chromosomes which are eventually extruded from the cells; hence, the spermatids develop into anucleate spermatozoa of unknown function. The apyrene divisions are induced by a haemolymph factor which becomes functional towards pupation. Using incorporation of tritiated thymidine at the premeiotic S-phase as a marker for timing, it was found that the prophase of the apyrene spermatocyte is shorter than that of the eupyrene spermatocyte. It is proposed that meiosis-specific proteins cannot be synthesized during the shortened apyrene prophase and that this is correlated with the irregular chromosome behaviour during the subsequent metaphase-telophase of these spermatocytes.     

Antigenic, functional, and molecular genetic studies of human natural killer cells and cytotoxic T lymphocytes not restricted by the major histocompatibility complex

Cytotoxicity not restricted by the major histocompatibility complex (MHC) is mediated by two distinct types of lymphocyte: natural killer (NK) cells and non-MHC-restricted cytotoxic T lymphocytes (CTL). These two types of cytotoxic lymphocytes can be distinguished by antigenic phenotype, function, and molecular genetic studies. In human peripheral blood, NK cells are identified by expression of the Leu-19 and/or CD16 cell surface antigens, and lack of CD3/T cell antigen receptor (Ti) complex expression (i.e., CD3-,Leu-19+). Peripheral blood non-MHC-restricted CTL express both CD3 and Leu-19 (i.e., CD3+, Leu-19+, referred to as Leu-19+ T cells). Both Leu-19+ T cells and NK cells lyse "NK-sensitive" hematopoietic tumor cell targets, such as K562, without deliberate immunization of the host. However, most "NK activity" in peripheral blood is mediated by NK cells, because they are usually more abundant and more efficient cytotoxic effectors than Leu-19+ T cells. The cytolytic activity of both NK cells and Leu-19+ T cells against hematopoietic targets was enhanced by recombinant interleukin 2 (rIL 2). NK cells, but not peripheral blood Leu-19+ T cells, were also capable of lysing solid tumor cell targets after short-term culture in rIL 2. Southern blot analysis of NK cells revealed that both the T cell antigen receptor beta-chain genes and the T cell-associated gamma genes were not rearranged, but were in germ-line configuration. These findings indicate that NK cells are distinct in lineage from T lymphocytes and do not use the T cell antigen receptor genes for target recognition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis of sulfated proteoglycans throughout the cell cycle in smooth muscle cells from pig aorta

Cultured smooth muscle cells from pig aorta arrested in G0 phase by serum deprivation were stimulated to proliferate by replacing the medium with one containing 10% serum. Studies in DNA replication and proliferation of cells showed a relatively good synchrony: 90% of the cells were in G1 phase for 16 h after addition of serum; they entered S phase between 18 and 24 h, completed S phase and traversed G2 phase between 24 and 30–32 h; 75% of these cells multiplied after 30–32 h and the remainder were blocked at the end of G2 phase. The synthesis and secretion of sulfated proteoglycans were examined throughout a full cell cycle using metabolic labelling with [³⁵S]sulfate. Smooth muscle cells in G1 or G2 phase synthesized and secreted sulfated proteoglycans with a possible pause at the end of the G2 phase but at the beginning of the S phase and during mitosis the incorporation of [³⁵S]sulfate into these macromolecules stopped entirely. Structural characteristics of sulfated proteoglycans secreted into the medium during G1 phase and an entire cell cycle were investigated. The proportion of proteoglycan complexes and the relative hydrodynamic size of monomers and of constituent subunits of complexes were determined after chromatography on Sepharose CL-2B and CL-6B columns run under both associative and dissociative conditions. No significant differences were observed for the periods of the cell cycle that were studied:

1. 1. [³⁵S]Proteoglycan complexes represented at the end of G1 phase and of the cell cycle respectively 19 and 16% of the total [³⁵S]proteoglycans secreted into the medium.

2. 2. More than 90% of the subunits, obtained after dissociation of complexes, were characterized by a similar k_av after chromatography on Sepharose CL-2B columns eluted under dissociative conditions (k_av 0.68 at the end of G1 phase and 0.65 at the end of full cell cycle).

3. 3. About 95% of monomers synthesized at the two stages of the cell cycle were eluted at k_av 0.25 after chromatography on Sepharose CL-6B column run under associative conditions and were characterized by a similar glycosaminoglycan distribution. These results suggest that smooth muscle cells in culture liberate similar populations of proteoglycans into the medium during the G1 and G2 phases.

     

Modifications of sphingomyelin and phosphatidylcholine metabolism by tricyclic antidepressants and phenothiazines

Phenothiazines and tricyclic antidepressants, when added to culture medium, gave rise in several types of cells (C6 rat glioma cells and human fibroblasts), to a decrease in lysosomal sphingomyelinase activity. The effect of chlorpromazine and desipramine was dose dependent, and was observed after 3 hours of incubation with the drugs at concentrations ranging between 1 and 10 microM. In C6 glioma cell cultures, the decrease in sphingomyelinase activity was related to the clinical effectiveness of phenothiazines, tricyclic antidepressants and derivatives. Incorporation of (choline-14C) sphingomyelin showed that the metabolic pathway implying the synthesis of phosphatidylcholine from the hydrolysis of sphingomyelin and/or transfer of phosphorylcholine to phosphatidylcholine was also partially reduced.     

Enhancement of Oxygen-Evolution in Photosystem II-Phycobilisome Particles from Porphyridium cruentum

Oxygen-evolving photosystem II-phycobilisome particles froma red alga were inhibited 50–80% by aging, dilution, lowpH and salt-washing. Bovine serum albumin, and dithiothreitolwere found to stimulate activity in all but salt-washed particles.CaCl₂ and MnCl₂ partially restored activity lost after agingor dilution. ¹Current address: Waksman Institute of Microbiology, RutgersUniversity, Piscataway, New Jersey 08854-0759, U.S.A. (Received October 5, 1985; Accepted March 31, 1986)     

Incidence of occult lumbro-sacral spina bifida in parents of children with spina bifida (concerning 80 pairs of parents with affected children)

Authors examined 80 pairs of parents with affected children with spina-bifida. They compared the incidence of spina-bifida occulta in parents and in 211 controls. The conclusion is: there is no increased incidence of spina-bifida occulta in parents of spina-bifida.     

在AppleⅡ型微机上实现核酸数据处理的工作程序

本文报道了在AppleⅡ型微机上实现核酸数据处理的一系列工作程序。应用这些程序,可进行核酸数据的贮存、对指定的核酸数据结构的改造、限制性内切酶识别位点的检索、核酸序列至蛋白序列的翻译、相关核酸序列及蛋白序列的同源性比较、氨基酸密码使用频率的统计和基因的启动子结构的初步探索等方面的工作。     

Transferrin in isolated cells from rat duodenum and jejunum

Mucosal transferrin was determined as transferrin-like immunoreactivity (TLIR) by means of a 2-site immunoradiometric assay (IRMA). Scraped-off mucosal tissue as well as isolated mucosal cells from the duodenum and jejunum of normal and iron-deficient rats before and after a washing procedure were examined. In iron-deficient rats there was about twice as much TLIR in scraped-off mucosal tissue as in the untreated animals. In the duodenum and jejunum of normal and iron-deficient rats, TLIR contents of the isolated cells in the magnitude of 320-510 ng/mg dry weight were found. Washing isolated cells three times in ice-cold Hank's solution resulted in a nearly tenfold decrease of TLIR content in all groups. In contrast the cells' RNA content remained unchanged.