Stimulation of myofibrillar synthesis by exercise is mediated by more efficient translation of mRNA.

Resistance exercises stimulate protein synthesis in human muscle, but the roles of changes in mRNA concentrations and changes in the efficiency of mRNA translation have not been defined. The present study was done to determine whether resistance exercise affects concentrations of total RNA, total mRNA, actin mRNA, or myosin heavy-chain mRNA (total and isoform specific). Eight subjects, 62-75 yr old, performed unilateral knee extensions at 80% of their one-repetition-maximum capacity on days 1, 3, and 6 of the study. On day 7, biopsies of exercised and nonexercised vastus lateralis muscles were obtained. Myofibrillar synthesis was determined by stable- isotope incorporation, and mRNA concentrations were determined by membrane hybridization and PCR-based methods. The exercise stimulated myofibrillar synthesis [30 +/- 6 (SE)%] without affecting RNA or mRNA concentrations. The effect of exercise on protein synthesis in individual subjects did not correlate with the effect on total RNA and mRNA concentrations. These data suggest that the stimulation of myofibrillar synthesis by resistance exercise is mediated by more efficient translation of mRNA.     

Circannual rhythm of food intake in spotted munia and its phase relationship with fattening and reproductive cycles

Summary The tropical spotted munia,Lonchura punctulata, exhibits a pronounced seasonality in reproduction, body weight and food intake. The body weight cycle parallels the reproductive cycle, whereas the food intake cycle is almost in antiphase to it. There is evidence that constant dietary restriction (50% of the maximum intake) causes dissociation of the body weight and reproductive cycles. Because of these relationships we performed experiments on the food intake cycle and its phase relationships with the reproductive and body weight cycles in birds held under constant light. The results indicate persistence of all three cycles. The phase relationships of these three parameters were almost normal, which may indicate that the endogenous oscillators for the cycles of reproduction, body weight and food intake are linked.     

A comparison of the radiation sensitivities of non-tumorigenic and tumorigenic human hybrid cell lines

The radiation sensitivities of two related non-tumorigenic and two related tumorigenic human hybrid cell lines (HeLa x skin fibroblast) have been studied. The data show that the transformation from the non-tumorigenic to the tumorigenic state, which is accompanied by the loss of skin fibroblast chromosomes 11 and 14, is not associated with any major changes in radiation sensitivity. The data do indicate, however, a trend toward a steeper and longer initial slope to the cell survival curve for the tumorigenic cell lines, along with a subsequent reduced ability to accumulate sublethal radiation injury at low doses. Both nontumorigenic and tumorigenic cell lines have the capability of repairing sublethal injury.     

Mousepox in inbred mice innately resistant or susceptible to lethal infection with ectromelia virus. II. Pathogenesis

The pathogenesis of mousepox due to infection with ectromelia virus strain NIH-79 was characterized in genetically susceptible (BALB/cAnNCr) and genetically resistant (C57BL/6NCr) mice. BALB/c mice inoculated subcutaneous (s.c.) or intranasally (i.n.) had high mortality. Most mice died within 7 days from severe necrosis of the spleen and liver. Necrotic foci in livers of BALB/c mice that survived beyond 7 days often were accompanied by mononuclear cell infiltrates and by hyperplasia of lymphoid tissues. C57BL/6 mice inoculated by either route remained asymptomatic and necrotic lesions were mild or absent, whereas focal non-suppurative hepatitis and lymphoid hyperplasia were prominent. Infectious virus and viral antigen were distributed widely in tissues of BALB/c mice, but had limited distribution in C57BL/6 mice. Both mouse strains had infection of the respiratory tract, genital tract, oral tissues and bone marrow, and BALB/c mice also had infection of the intestines. Both strains also developed serum antibody to vaccinia virus antigen after infection. The results show that ectromelia virus occurs in tissues conducive to mouse to mouse transmission and that the severity and character of mousepox lesions correlate directly with resistance and susceptibility to infection. They also support the concept that cellular immunity contributes to survival from infection.     

Development of an efficient two-element transposon tagging system in Arabidopsis thaliana

Summary Modified Ac and Ds elements, in combination with dominant markers (to facilitate monitoring of excision, reinsertion and segregation of the elements) were introduced into Arabidopsis thaliana ecotype Landsberg erecta. The frequencies of somatic and germinal transactivation of the Ds elements were monitored using a streptomycin resistance assay. Transactivation was significantly higher from a stable Ac (sAc) carrying a 537 by deletion of the CpG-rich 5 untranslated leader of the transposase mRNA than from a wild-type sAc. However, substitution of the central 1.77 kb of the transposase open reading frame (ORF) with a hygromycin resistance marker did not alter the excision frequency of a Ds element. -Glucuronidase (GUS) or iaaH markers were linked to the transposase source to allow the identification of plants in which the transposase source had segregated away from the transposed Ds element, eliminating the possibility of somatic or germinal re-activation. Segregation of the excision marker, Ds and sAc was monitored in the progeny of plants showing germinal excision of Ds. 29% of the plants inheriting the excision marker carried a transposed Ds element.     

Synthesis, antimicrobial, and antitumor activity of a series of palladium(II) mixed ligand complexes.

Mixed ligand complexes of cisdichloromethioninepalladium(II) with 2-mercaptopyrimidine and 2-aminopyrimidine were synthesized and characterized by elemental analysis, conductivity data, infrared, and 1H NMR and 13C NMR spectra. In these mixed ligand complexes methionine coordinates to palladium through amino nitrogen and sulphur, thus leaving a free carboxylic acid group. The pyrimidine ligand coordinates to metal ion through N3. Mixed ligand complexes of cisdichloroethioninepalladium(II) with cytosine and guanosine were synthesized and characterized earlier. All the above mixed ligand complexes were screened for antimicrobial activity against Vibrio parahaemolyticus, Pseudomonas aeruginosa, Proteus vulgaris, Escherichia coli, Shigella flexnerri, Salmonella typhii, Klebsella pneumoniae, and Vibrio cholerae. It was found that complexes [Pd(meth)Cl2]: [Pd(meth)(2merpy)Cl]Cl; [Pd(meth)(2ampy)Cl]Cl; [Pd(ethio)Cl2]; [Pd(ethio)(cyt)Cl]Cl; and [Pd(ethio)(guo)Cl]Cl showed broad spectrum antimicrobial activity against all the human pathogens tested, however [Pd(meth)(2merpy)Cl]Cl eliminated plasmid with 100% frequency. These complexes have also been screened in vitro for antitumor activity against Hela (Epidermoid Carcinoma Cervix) and CHO cell lines. An excellent correlation between the antitumor activity of Pd(II) complexes and their ability to cure plasmids exists.     

Response of blood glucose,hepatic glycogen and pancreatic islets to treatment of sulphydryl inhibitors inClarias batrachus L.

The correlative effects of the two sulphydryl inhibitors viz., the mono-and dithiol reagent, alloxan and cobalt chloride, were studied in the fresh water air breathing catfish,Clarias batrachus. Alloxan induced a typical mammalian-like triphasic response and necrobiotic changes in the islet Β-cells. Cobalt chloride elicited a discontinuous hyperglycemia with cytopathological changes in Β-cells following nearly the same sequence as those induced by alloxan. However, the α-cells of cobalt-treated fish showed, unlike those after alloxanization, specific degranulation, vacuolization and nuclear enlargement. The changes in the hepatic glycogen content of two experimental groups were observed to be equal. Both the drugs appeared to be detrimental to the normal islet function and were, thus, overtly or potentially diabetogenic agents to the fish. Part of this paper was presented at the Second Congress of the Federation of Asian and Oceanian Biochemists and the Golden Jubilee meeting of the Society of Biological Chemists (India), Bangalore, 14–18 Dec, 1980.     

Stereoselective chlorination of methyl β-lactoside with mesyl chloride in N,N-dimethylformamide

Treatment of methyl β-lactoside with mesyl chloride in N,N-dimethylformamide under a variety of conditions gave complex mixtures of chlorinated products, of which nine were isolated and characterised. Chlorination at a secondary position always occurred with inversion of configuration. When the reaction was conducted at 94° for 9 days, a mixture of the 3,3′,4′,6,6′-pentachloride, the 3,3′,6,6′- and 3,4′,6,6′-tetrachlorides, and the 3,6,6′- and 3′,6,6′-trichlorides was obtained together with the 3′,4′-epoxide of the 6,6′-dichloride, which was an artefact. Under milder conditions, the 6,6′-dichloride was encountered, together with methyl 6-chloro-6-deoxy-β-D-glucopyranoside which had arisen by hydrolysis of the interglycosidic bond. It is particularly noteworthy that displacement occurred at C-3′ of the lactoside, in spite of the vic-axial group at C-4′ which should hinder nucleophilic displacement at C-3′. The cause of this anomaly is discussed.