A differential scanning calorimetric study of the binding of sulfate ion and of Cibacron blue F3GA to yeast phosphoglycerate kinase

In continuation of earlier work [Hu, C. Q., & Sturtevant, J.M. (1987) Biochemistry 26, 178-182], differential scanning calorimetry has been employed in a study of the effects on the thermal denaturation of yeast phosphoglycerate kinase of two inhibitors of the enzyme, sulfate ion and the dye Cibracron blue F3GA. Sulfate ion, as is usual with ligands that dissociate during unfolding of the host protein, raises t1/2, the temperature of half-completion of the denaturation, has only a modest effect, stemming from the enthalpy of dissociation of the ligand, on the enthalpy of denaturation, and has little or no effect on the heat capacity change resulting from denaturation. In sharp contrast, Cibacron blue F3GA lowers t1/2 and drastically decreases both the enthalpy and heat capacity changes due to denaturation. The DSC results with sulfate ion are consistent with previous kinetic data [Scopes, R. K. (1978) Eur. J. Biochem. 91, 119-129; Khamis, M. H., & Larsson-Raznikiewicz, M. (1981) Biochim. Biophys. Acta 657, 190-194], which indicate two binding sites for sulfate ion at one of which the ligand acts as a competitive inhibitor. The results with Cibacron blue F3GA indicate that the dye induces a major destabilizing structural change in the enzyme in addition to rendering it enzymically inactive.     

抗阿特拉津转基因大豆植株后代的遗传分析

本试验用阿特拉津溶液涂抹、荧光诱导动力学检测、分子杂交等方法对抗阿特拉津转基因大豆植株的后代进行了鉴定,在第二代及第三代中检测到了抗性基因的存在,表明从龙葵中得到的此抗阿特拉津 psbA 基因不仅能导人大豆叶绿体基因组中获得表达,而且可以遗传到后代。     

The effect of carbamylcholine on CFU-s differentiation

The proportion of spleen colony-forming units (CFU-s) killed by hydroxyurea was greatly increased after bone marrow cells (BMCs) from LACA mice were exposed to carbamylcholine (Cach; 1 X 10(-13) to 1 X 10(-9) in vitro and there was a marked change in the proportion of spleen colony types. Following treatment with Cach, granulocytic and mixed erythroid-type colonies increased from 20 to 26.3% and 16.1 to 29.6% in 9-day colonies and from 8.3 to 28.2% and 21.7 to 39.4% in 13-day colonies, respectively. Single cell suspensions of spleen colonies were made for granulocyte-macrophage progenitor (CFU-gm) and late erythroid progenitor (CFU-e) assays. The number of CFU-gm from Cach-treated BMC was about twice that from control BMC for both day 9 and day 13 groups; the number of CFU-e decreased relatively. The results suggest that cholinergic receptors on CFU-s may increase the tendency to differentiate into the granulocytic/monocytic line.     

Lectin bindings and diethylstilbestrol effects on the recognition of mullerian inhibiting substance (MIS) on chick mullerian ducts by MIS-antiserum

Summary A high intensity of lectin bindings was demonstrated on the epithelial cells and serosa cells of the regressing right Mullerian ducts (Mds) in the female chick embryos. The strong lectin bindings occurs on, or in the regressing Md cells along with marked surface MIS bindings at the age of day 13. However, at the age of days 5–7 1/2, bindings of lectins were weak. Neither Wheat-germ agglutinin (WGA) or Concanavalin A (Con-A) labelings before MIS-antiserum (MIS-Ab) incubation can block antibody recognitions to the antigens, including MIS and growth hormone at the age of day 13. Our previous studies indicated that after WGA labeling on the surfaces of Md epithelial cells prior to the incubation of MIS-Ab at day 10 did not prevent the recognition of MIS-Ab (Wang 1989). On the contrary, at day 7 1/2, the specific binding of MIS was eliminated after preincubations with lectins and prenatal diethylstilbestrol (DES) treatment at the age of day 5. It is suggested that DES provides a protection to the Mds from MIS-induced regression by preventing the MIS binding to its specific membrane receptors. An increase of extra- and intracellular glycoproteins or carbohydrates of regressing Md epithelial cells were suggested. Internalization of WGA but not MIS molecules was found in Md epithelial cells. The Golgi saccules were negative of lectin bindings.     

Phase I study of combination recombinant interleukin-2 and interferon gamma in patients with advanced malignancies

A phase I trial of interleukin-2 and interferon gamma combination treatment in patients with advanced malignancies was performed based on preclinical in vitro and in vivo data which demonstrated synergistic antitumor effect. The toxicities, immune parameters, and tumor responses are described. The clinical and biologic maximal tolerated doses were extrapolated from these data.     

Recombinational resolution in primate cells of two homologous human DNA segments with a gradient of sequence divergence.

Human alpha-thalassemia-2 genotype -alpha 4.2 is the result of meiotic recombination between two 1.3 kb long, homologous DNA segments, X(alpha 2) and X(alpha 1), located in the adult alpha globin locus. The two segments can also undergo intramolecular recombination on extrachromosomal vectors transfected into mitotically dividing primate cells (COS 7). The existence of a gradient of sequence divergence between X(alpha 2) and X(alpha 1) makes them an interesting system to study the relationship between efficiencies of homologous DNA recombination and the extent of dispersed and localized base mismatches. By partial restriction mapping and DNA sequencing of plasmids recombined in COS 7 cells and rescued from bacteria HB 101, we have determined the distribution of recombinational resolution sites along the two X blocks. Most, if not all, of the homologous recombination events between the two X blocks appear to be single crossing-over without efficient gene correction or repair of base mismatches. The distribution of the sites of recombinational resolution is inversely correlated with that of the gradient of sequence divergence, with only approximately 7% of the X recombinants resolved within the 3' third of the X blocks where two diverged Alu family repeats reside. The Alu sequence within which one of the X recombinants resolved is homologous to a previously characterized alpha thalassemia deletion point.