中药固真方对一些与细胞增殖有关基因表达的影响

 中药固真方对一些与细胞增殖有关基因表达的影响姚明忠,顾文聪,丁卫,韩志芬,杜国光（上海中医药大学生物化学教研室,上海２０００３２）（北京医科大学生物化学与分子生物学系,北京１０００８３）中药固真方（ＶＲＦ）具有补肾益精、延缓衰老的作用［１］．能提高成...     

Apoptosis and nutrition: Involvement of amino acid transport system in repression of hybridoma cell death

Mouse hybridoma cells cultured on the verge of starvation-induced apoptosis, i.e. in a medium diluted with saline, proved to serve as a sensitive screening system for apoptosis-suppressing activity of nutrient medium components. Conventional amino acid mixtures were found to suppress the starvation-induced apoptosis, whereas a vitamin mixture was ineffective. (Frank F (1995) Biotechnol. Bioeng. 45: 86–90). Recent experiments showed that suppression of apoptosis, and concurrent resumption of growth, could be achieved by addition of single substances at millimolar concentrations. The set of active substances included certain coded L-amino acids (glycine, alanine, serine, threonine, proline, asparagine, glutamine, histidine), non-coded amino acids (-alanine, taurine, 4-aminobutyric acid), and a non-metabolizable analogue (2-aminoisobutyric acid). This finding shows that some amino acids do not act solely as nutrients, but also as specific signal molecules. The specificity of the effect points to the involvement of adaptively regulated amino acid transport systems A and N in maintaining the balance between triggering and suppression of starvation-induced apoptosis.     

Mechanisms of increasing the intensity of ultraviolet fluorescence of irradiated cells

As shown on the in vitro irradiated Ehrlich ascites tumor cells the increase in the intensity of ultraviolet fluorescence (UVF) of the exposed cells occurs only in such incubation conditions when an increase in the tryptophan content of irradiated cells becomes possible. The increase in the UVF intensity and in the tryptophan content are quantitatively identical. It is concluded that the increase in the content of the fluorescing substance, tryptophan, in the irradiated cells is the cause of the increase in the UVF intensity.     

Valine-sensitive acetohydroxy acid synthases in Escherichia coli K-12: unique regulation modulated by multiple genetic sites.

Summary Spontaneous mutants (146) of Escherichia coli K-12 were selected that were resistant to inhibition of growth by 1.2 mM L-valine (Val^r). The Val^r isolates, containing acetohydroxy acid synthase resistant to feedback inhibition by L-valine (AHAS^r), were classed according to cotransduction of the mutation with leu. Several mutations resulting in an AHAS^r phenotype were found to be cotransducible with glyA. However, no mutations causing a Val^r phenotype were linked to ilv. AHAS activity was more closely examined in representatives of three classes of mutants with Val^r linked to leu, labeled ilv-660, ilv-661, and ilv-662. The ilvE503 allele in E. coli K-12, known to cause a two- to three-fold derepression of AHAS, was found to affect regulation of synthesis of both valine-sensitive AHAS (AHAS^s) and AHAS^r in the mutants containing ilv-660 and ilv-661, whereas it affected repression of AHAS^s, only, in the mutant containing ilv-662. Further, both AHAS^s and AHAS^r in the ilv-661 mutant were repressed by valine, whereas valine did not repress AHAS^r synthesis in the strain carrying ilv-660 and only partially repressed AHAS^r in the strain carrying ilv-662. Unexpectedly, AHAS^r synthesis in strains carrying ilv-660 or ilv-662 was repressible by leucine. The ilv-660 locus appears to be similar in position to ilvH and encodes a product that confers valine-sensitivity upon AHAS activity in the wild-type E. coli K-12. The ilv-660 and ilv-662 loci may normally encode products that influence both the feedback sensitivity of AHAS and control of AHAS biosynthesis.     

Purification and characterization of two isoenzymes of lipoxygenase from soybeans

A chromatographic procedure for the purification of two lipoxygenase isoenzymes (linoleate: O₂ oxidoreductase, EC 1.13.11.12.) from soybean is described. The procedure for the purification of isoenzyme L-1 includes optimalized extraction, ammonium sulfate fractionation, heat treatment and gradient elution from a CM-Sephadex C-50 column. The purification of L-2 includes ammonium sulfate fractionation, gelfiltration on Sephadex G-150 and gradient elution from a DEAE-cellulose column. Both isoenzymes L-1 and L-2 appear homogeneous after Disc-PAGE. The isoelectric points are 5.6 for L-1 and 5.8 for L-2. Molecular weights are estimated as 100,000 for L-1 as well as L-2 applying three different methods. Both isoenzymes contain 0.9 mol iron per mol protien. The estimated turn over numbers are 8,200 mol linoleate per mol enzyme and min for L-1 and 3,100 for L-2. Amino acid compositions determined after acid hydrolysis show marked differences between L-1 and L-2, particularly with respect to the amino acids Lys, Phe, Ser, Gly and Leu. L-1 posesses a total of 9 cysteine molecules, 6 of which are present as disulfide bonds. L-2 posesses a total of 8 cysteine molecules with only one disulfide bond.These results have been presented in part at the 13th ISF Congress in Marseille on 2nd September 1976     

Two possible conformations of the repetitive site of the immunoglobulin G3 hinge region

Conformational analysis of immunoglobulin G3 (IgG3) hinge region repeating part was performed. In approximation of backbone regular conformations for the case of C2 symmetry (the symmetry axis is perpendicular to S-S bridges and passes through their midpoint) on the basis of total analysis of ring geometry possibilities and estimation of steric conditions, the existence of two conformations with n = 3 (3(10) helix type and polyproline II type) was inferred. A possible role of these conformations in the immunoglobulin functioning was discussed.     

Use of whey for production of exocellular polysaccharide by a mutant strain ofXanthomonas campestris

Growth and kinetics of the production of exocellular polysaccharide was studied in a mutant strain ofXanthomonas campestris lac ⁺ during cultivation in a submerged culture in a medium containing whey. The maximum production of the polymer was observed at the initial stage of the stationary growth phase of the culture. The mean production yield was about 1.4%. The results were comparable with those obtained during cultivation on a lactose medium. Translated by Č. Novotny     

Histological characterization of in vitro regenerated structures of Panax ginseng

Callus was induced from mature leaf lamina, petiole, stem, and main and branch root of Panax ginseng and maintained under different nutrient and light conditions. Heterogenous callus cultures differentiated organoids and/or embryoids. Embryoids that arose from callus cultures of leaf origin germinated into shoots. The occurrence of the early stages of different regenerated structures was proved on histological level.