Effect of prolactin and glucocorticoids on P-enolpyruvate carboxykinase activity in liver and mammary gland from diabetic and lactating rats

Summary The administration of 2 bromo--ergocryptine, to reduce serum prolactin decreased the activity of cytosolic P-enolpyruvatc carboxykinase (GTP) (EC4.1.1.32) about 50% in both liver and mammary gland of lactating animals. Adrenalectomy had similar effects to those of bromo-a-ergocryptine. In contrast, there was a 50% increase in enzyme activity in the mammary gland of diabetic, lactating rats and a 10-fold increase in liver as compared with normal rats. P-enolpyruvate carboxykinase activity in mammary gland as liver is coordinately regulated by prolactin, glucocorticoids and insulin.     

Screening of plasmids in non-pathogenic corynebacteria

Abstract A screening of plasmids in 25 nonpathogenic coryneform bacteria was carried out. 11 Strains showed at least one plasmid, ranging in size from 4.2 to 55 kb. These plasmids did not encode bacteriocin production or resistance to a number of antibiotics or to ions such as arsenite, mercury(II) and cobalt(II). A detailed study of plasmid pBL100 from Brevibacterium linens is presented. pBL100 has a size of 7.75 kb, and contains single sites for the endonucleases: Hin dIII; Pst I, Bgl II, Eco RI and Bam HI. B. linens is easily and efficiently transformed with vectors derived from pBL1 isolated from Brevibacterium lactofermentum .     

Immunoelectrophoretic approach to the metabolic regulation of glutamine synthetase in Rhodopseudomonas capsulata E1F1: role of glutamine

Anti-glutamine synthetase serum was raised in rabbits by injecting purified glutamine synthetase (GS) of the phototrophic bacterium Rhodopseudomonas capsulata E1F1. The antibodies were purified to monospecificity by immunoaffinity chromatography in GS-sepharose gel. These anti-GS antibodies were used to measure the antigen levels in crude extracts from bacteria, grown phototrophically with dinitrogen, nitrate, nitrite, ammonia, glutamate, glutamine or alanine as nitrogen sources. The amount of GS detected by rocket immunoelectrophoresis was proportional to Mn²⁺-dependent transferase activity measured in the crude extracts. Addition of GS inhibitor l-methionine-d,l-sulfoximine (MSX) to the actively growing cells promoted increased antigen levels, that were not found in the presence of glutamine or chloramphenicol. The ammonia-induced decrease in GS relative levels was reverted by MSX. GS levels remained constant when phototrophically growing cells were kept in the dark.Abbreviations GS glutamine synthetase - MOPS 2-(N-morpholine) propane sulfonate - MSX l-methionine-d,l-sulfoximine     

Action ofN-methyl-N′-nitro-N-nitrosoguanidine inRhizobium trifolii

Rhizobium trifolii was highly resistant to the lethal effect ofN-methyl-N-nitro-N-nitrosoguanidine (MNNG), but it was sensitive to the mutagenic action of this chemical. A concentration of 500g/ml yields a survival of between 1% and 10%, which allows us to obtain a higher number of mutants than lower concentrations that yield higher survival rates. Lethal damage produced by nitrosoguanidine was repaired, and repair is inhibited by acriflavine.     

Monoclonal antibodies to rabbit skeletal muscle protein phosphatases C-I and C-II

Rabbit skeletal muscle protein phosphatases C-I and C-II have been previously isolated as two proteins of Mr = approximately 35,000. Both enzymes display broad substrate specificities but have distinct enzymatic properties in regard to their susceptibility to heat-stable protein inhibitor-2 and their response to divalent cations. Monoclonal antibodies against both protein phosphatase C-I and C-II were produced by fusion of spleen cells of immunized BALB/c mice with SP2/0-Ag14 mouse myeloma cells. The products of the hybrid cells were screened by solid phase radioimmunoassay for the production of antibodies to protein phosphatase C-I and C-II. Positive cells were cloned and injected into mice to produce ascitic fluids. Ten monoclonal antibodies against phosphatase C-I and eight monoclonal antibodies against phosphatase C-II were obtained. These antibodies were characterized with regard to their relative binding affinities to the two protein phosphatases and their abilities to inhibit the phosphorylase phosphatase activities of the two enzymes. All ten of the phosphatase C-I monoclonal antibodies inhibited the phosphorylase phosphatase activity of phosphatase C-I, and three of these also inhibited phosphatase C-II. Only one of the eight antibodies to phosphatase C-II was inhibitory and inhibited the activities of both phosphatase C-I and C-II. Examination of the binding of these monoclonal antibodies by a solid phase radioimmunoassay showed that eight of the ten phosphatase C-I antibodies cross-reacted with phosphatase C-II, while all eight of the phosphatase C-II antibodies cross-reacted with phosphatase C-I. These findings show that phosphatases C-I and C-II possess common antigenic determinant(s) and may, therefore, be structurally related proteins.     

Reactions of sugar nitro-alkenes with acetoacetic esters

3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-1-nitro-d-gluco-hept-1-enitol reacts with methyl acetoacetate in an unusual Michael reaction, giving the normal adduct (6), and a bicyclic derivative (9) that arises from quasi-dimerization of the former when a high concentration of the base is used. Acetylation of compound 9 gives the hydroxylamine O-acetate (10).From the reactions of 3,4,5,6,7-penta-O-acetyl-1,2-dideoxy-1-nitro-d-galacto-hept-1-enitol with ethyl and tert-butyl acetoacetate, the normal adducts (7 and 8) were isolated. The structures of compounds 6 to 10 were established on the basis of their spectral properties (u.v., i.r., mass, and ¹H- and ¹³C-n.m.r.)