633菌剂发酵条件的研究

This paper reports the fermentation techmology of bacterial feed NO.633. A new fermentational technic, which was composed of fermentation medium, optimum pH,temperature, airate flow, pot pressure and fermentation time, was established.     

Charge effect on the colchicine binding-site of tubulin

Poly(L-lysine) was found to enhance colchicine binding activity of brain tubulin to a several folds. Bases of biological interests that were tested and found to be inactive were spermine, spermidine and even L-lysine. Part of this enhance binding is due to the increase in the affinity of colchicine-tubulin interaction in the presence of poly(L-lysine). Moreover, poly(L-lysine) stabilized the colchicine binding site of tubulin against thermal denaturation.     

Simulation results with stepwise mutation model and their interpretations

Summary Monte Carlo simulations are performed to compare the predictions based on the two presently used theoretical models for studying genetic variations in natural populations, the infinite allele model and the stepwise mutation model. Distribution of heterozygosity is noticed to be similar under these models until the product of population size and mutation rate is large. It is seen that electromorphs with high population frequency usually contain older alleles (at the codon level) than an electromorph of low population frequency. The interpretations of these results in explaining the allelic variations at electrophoretic level is also discussed.Research supported by U.S. Public Health Service General Research Support Grant 5 SO 5 RR 07148 from the University of Texas Health Science Center, Graduate School of Biomedical Sciences, Houston, Texas     

The role of ribose-binding protein in transport and chemotaxis in Escherichia coli K12.

The ribose-binding protein of Escherichia coli [Willis, R. C., and Furlong, C. E. (1974) J. Biol. Chem.249, 6926–6929] has been shown to be a required common receptor component for high-affinity ribose transport and for chemotaxis toward this attractant. Mutants devoid of the ribose-binding protein are missing high-affinity ribose transport and do not respond chemotactically to this sugar, whereas the response to other attractants is normal. Eight independently isolated ribose-positive revertant strains regained the binding protein, high-affinity ribose transport, and ribose chemotaxis. One revertant which grows slowly on ribose as a sole carbon source did not regain the binding protein, high-affinity transport, or ribose chemotaxis.     

Effects of nitric oxide on growth of maize seedling leaves in the presence or absence of ultraviolet-B radiation

The leaves of maize seedlings were used to measure leaf biomass including leaf length, width and weight, and to examine the relationship between nitric oxide (NO) synthase activity in microsomes and cytosol to the exo- and endo-beta-glucanase activity during growth. It was found that ultraviolet-B radiation (UV-B radiation) strongly induced nitric oxide synthase (NOS) activity but caused both a decrease of leaf biomass and exo- or endo-beta-glucanase activity. In contrast, the NOS inhibitor and NO donor largely decreased the activity of NOS in non-irradiated seedlings. The inhibitor also reduced exo- and endo-beta-glucanase activity and leaf biomass while the donor increased the enzyme activity and leaf biomass under normal conditions. Alternatively, under ultraviolet-B, the additional inhibitor of NOS and NO donor appeared to compromise the effects of ultraviolet-B on glucanase activity and leaf biomass, making the relationship between NOS activity and glucanase activity negatively correlated. This suggests that the changes of NOS activity showed a positive correlation to glucanase activity and leaf biomass in the absence of ultraviolet-B, but a negative correlation to ultraviolet-B irradiation and NO donor treatment alone. It is assumed that exo- and endogenous NO is responsible for the up-regulation of regular growth and development without ultraviolet-B. Under UV-B radiation, however, it might function as a signaling molecule of ultraviolet-B inhibiting leaf growth of maize seedlings to carry out stress-signaling transduction.     

Separation of epithelial cells from suspensions of cells from the hamster parotid gland in an isokinetic density gradient of Ficoll in tissue culture medium.

Epithelial cells were separated from suspensions of hamster parotid cells by velocity sedimentation in an isokinetic gradient and by isopycnic sedimentation. Epithelial cells were 48.1 ± 18.0% of the cells in the starting sample suspensions of cells from the disaggregated hamster parotid glands. The purest gradient fractions following velocity sedimentation in a previously described isokinetic gradient contained 98.8 ± 1.8% epithelial cells. The purest fractions obtained from isopycnic sedimentation contained 99.9 ± 0.2% epithelial cells. Purification of parotid epithelial cells by velocity sedimentation in the isokinetic gradient seems preferable to purification using isopycnic centrifugation because a larger proportion of the epithelial cells are obtained in the zone of the gradient which contains highly purified epithelial cells and because velocity sedimentation requires lower centrifugal forces for a shorter period of time.     

Phosphatidylinositol exchange protein. Effects of membrane structure on activity and evidence for a ping-pong mechanism.

Phosphatidylinositol exchange protein, purified from bovine cerebral cortex, catalyzes the transfer of phosphatidylinositol and, to a lesser extent, phosphatidylcholine between rat liver microsomes and egg phosphatidylcholine liposomes. Transfer activity is sensitive to pH, temperature, and the method of liposome preparation. Variation of the phospholipid composition of the liposomes produces vesicles for which the apparent Michaelis constant decreases with increasing molar proportions of phosphatidylinositol. Interaction of exchange protein with liposomes containing radioactively labeled phosphatidylcholine allows the isolation of a phospholipid-protein complex; dissociation of this complex occurs upon subsequent interaction with unlabeled liposomes. Changes in the concentration of the two membrane species, microsomes and liposomes, yield results which are interpreted in terms of a ping-pong kinetic mechanism for the protein-catalyzed, intermembrane transfer of phospholipids.     

优质甘薯种质福薯1号鉴定及利用研究

福薯1号是福建省农业科学院作物研究所以广薯62为母本,A48、福薯26等8个品种为父本计划集团杂交获得的优质甘薯种质。该种质作为亲本材料具有开花习性好、结实率高的特点,杂交获得的后代品系具有入选率高、食味品质好、商品品质优、抗病性强等特点,利用福薯1号为母本已选育出3个品种通过国家甘薯品种鉴定或福建省审定。     

The Psychology Underlying the Art Activity Program

The author investigates the condition of a public school's arts education program under the No Child Left Behind (NCLB) Act and obtains teachers' perspectives on their experiences under the federal policy. The author used qualitative and quantitative approaches to conduct a case study of an Ohio public school district. The data collected revealed changes in the arts education curriculum, particularly in music. Teacher interviews provided the context in which the changes occurred and a more accurate representation of the decrease in arts learning opportunities and the challenges that exist for arts education funding under NCLB. The information illustrated how administrative decisions made to improve test scores and accommodate policies mandated by NCLB threatened arts education.