Turnover of cyclic adenosine-5'-monophosphate is elevated in skeletal muscle of vitamin E-deficient rabbits.

Two sets of experiments were performed to investigate the nonantioxidant functions of alpha-tocopherol. Eighteen rabbits in the first set and 48 rabbits in the second set were equally divided into three groups. The first group received a basal tocopherol-deficient diet supplemented with all-rac-alpha-tocopherol for 3 wk and the second group was fed the basal diet. The third group received vitamin E supplementation for 1 wk after 2 wk of consuming a tocopherol-deficient diet. In the first set of animals, skeletal muscle concentration, metabolism and turnover of various adenine nucleotides were measured by incubating the muscles of the three groups with [8-3H]adenine. The second set of experiments investigated in vivo concentration of various adenine nucleotides before incubation with radioactive substrate and quantity of newly formed adenine nucleotides after incubation with four different specific radioactive substrates: [8-14C]ATP; [8-14C]cAMP; [8-14C]5'AMP and [8-14C]adenosine. The results expressed per milligram of DNA were compared between the tocopherol-supplemented and tocopherol-deficient rabbits. Cyclic-AMP concentration (measured after a 2-h incubation with [8-3H]adenine) was lower and 5'-AMP concentration was very high in the tocopherol-deficient rabbits. The results of incorporation studies indicated that the turnover of ATP + ADP, cAMP, 5'-AMP and adenosine was higher in the tocopherol-deficient rabbits. Administration of tocopherol to tocopherol-deficient rabbits restored the turnover of cAMP to nearly normal values. These observations provided new insights concerning nonantioxidant functions of alpha-tocopherol.

Biochemical changes in progressive muscular dystrophy, XVI. Effect of glutamic acid, aspartic acid and glycine on the amino acid content of skeletal muscle of dystrophic mice.

The effect of exogenous administration of glutamic acid (GL), aspartic acid (A) and glycine (G) on individual amino acids in the free amino acid pool was studied in skeletal muscles of 60- to 70-day-old normal (N) and dystrophic (D) mice. Both N and D mice received either 0.25 ml of saline (S) or 250 mg/kg weight of GL, A or G in 0.25 ml S subcutaneously for 13 days. GL, A, G or S did not cause any significant changes in the body and skeletal muscle weights of either group. Most of the individual amino acids were increased in skeletal muscles of GL-treated mice and were decreased in A- or G-treated animals compared to S administration in the N group. The picture was more dramatic in the D group: GL-induced amino acid elevations were more pronounced than the values of N- or S-treated D controls. A and G elicited amino acid increases in D mice compared to their S-treated counterparts. Most of the individual amino acids in skeletal of the D group were decreased relative to N mice after S, GL or A administration. This was evident when the D/N ratio was calculated for S, GL and A. The situation was very different after G administration since of the individual amino acids were augmented in the skeletal muscle of D mice compared to N animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical changes in progressive muscular dystrophy. XV. Distribution of radioactive glutamate and proximate composition of various components of skeletal muscle and liver in vitamin E-deficient dystrophic rabbits and 129/ReJ (dy/dy) mice.

The proximate composition of skeletal muscle and liver and the incorporation of radioactive glutamate into their various components were investigated in vitamin E-deficient rabbits and genetically dystrophic (dy/dy) mice during various stages of the disease. Total fat content in skeletal muscle was decreased in the early phase and increased in the terminal stage of both types of dystrophy. This component altered only in the liver of dystrophic mice, showing a reduction in the mild stage but returning later to normal values. Carbohydrate content was diminished in the skeletal muscle of both species at each stage of the disease. In the liver, however, it was elevated considerably in vitamin E-deficient rabbits, but was depressed in dystrophic mice. Protein content was decreased in the skeletal muscle of both dystrophic models. Similar results were obtained for amino acids, except that they were increased in the terminal stages of nutritional dystrophy. Analogous values were recorded for hepatic amino acids in nutritionally-induced and hereditary dystrophy (in rabbits and mice respectively). Incorporation of C14-glutamate into various components of skeletal muscle and liver in both models revealed divergent responses, depending upon the nature of the dystrophy, and the component in which incorporation was measured. These data indicate a rapid turnover of C14-glutamate in the skeletal muscle and liver of vitamin E-deficient and genetically dystrophic animals. Also, it is clear that the changes in the various components of skeletal muscle and liver, as well as the pattern of C14-glutamate incorporation, are different in the two types of dystrophy.

Biochemical changes in progressive muscular dystrophy. XIV. Skeletal muscle myosin mRNA translatability in dystrophic mice.

Variations in the content and translatability of the poly(A)+ RNA and mRNA molecules coding for myosin (M) were studied in the hind leg muscles of genetically dystrophic mice. The poly(A)+ RNA content of total skeletal muscle failed to increase normally during progression of the disease. M mRNA, isolated from dystrophic normally during progression of the disease. M mRNA, isolated from dystrophic murine muscle poly(A)+ RNA, was mostly found to be associated with the 26S RNA species. The translation of M mRNA in an in vitro heterologous wheat germ system was lower at 8 and 16 weeks in the dystrophic group as compared with the controls. Analysis of the translation products via sodium dodecyl sulfate-polyacrylamide gel electrophoresis, autoradiography, and densitometric autoradiographic tracing demonstrated the gradual disappearance of a protein band corresponding to M, the major component of skeletal muscle. cDNA was synthesized, using M mRNA that was isolated and purified from normal and dystrophic mouse muscle as a template. Total radioactivity was measured in some cDNA fractions produced from normal and dystrophic mouse muscle, while other fractions were utilized for separation and sizing of cDNA by disc gel electrophoresis. The cDNA from normal muscle was hybridized with M mRNA from normal and 16-week-old dystrophic mouse muscles. The cDNA probe, hybridization experiments, and studies involving the content and synthesis of M mRNA suggest that murine muscular dystrophy elicited a shorter species of mRNA or shorter sequences of the same species of mRNA coding for M. Not all poly(A)+ mRNA sequences coding for M, found in control mice, were present in their dystrophic counterparts.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphoid organ mRNA translatability in rats: effect of protein energy undernutrition in early life.

Synthesis of mRNA was studied in the spleen and thymus of rats that had been exposed to undernutrition early in life. To achieve this objective, lactating females were separated into two groups 1 wk after they gave birth to offspring. These control and experimental dams suckled 8-11 and 13-16 pups, respectively, for a period of 2 wk. The young of both groups were then killed, and their thymus and spleen were isolated. Polyadenylated RNA (poly A+ RNA) was fractionated by affinity chromatography on an oligo-dT-cellulose column. Poly A+ RNA content as well as the percentage of poly A+ RNA in relation to total RNA were both lower in the undernourished pups than in the controls. Analysis of the in vitro translation product primed by poly A+ RNA of the thymus and spleen revealed a rise in [35S]methionine incorporation in the undernourished offspring, the increase being greater in the thymus than in the spleen. Sodium dodecyl sulfate polyacrylamide-gel electrophoresis, autoradiography and densitometric autoradiographic tracings confirmed these findings and demonstrated that proteins were synthesized at a higher level in the spleen and thymus of the undernourished rats than in the controls. These results show that undernutrition early in life could modulate the metabolism of mRNA and, consequently, protein synthesis in the lymphoid organs of rats. Furthermore, the data suggest that cell-mediated immunity as well as humoral immunity are both deranged in protein energy undernutrition.

Nucleic acid and protein metabolism in undernutrition and protein deficiency.

This review discusses the metabolism of nucleic acids and proteins in various models of undernutrition in female rats and their neonatal and 21-day-old progeny. Based on the observations noted in our laboratories and those of other investigators, it is concluded that body and organ weights as well as various parameters of cellular growth (DNA, RNA, proteins, amino acids and total nucleotides) fail to increase normally in dietary-insulted animals. Protein and RNA synthesis demonstrate variable responses, leading to the speculation that modulation of mRNA metabolism and of protein synthesis occurs in dietary-restricted rats. These findings are also confirmed by the organ weight to DNA ratios. It is further noted that, despite the increases in protein and RNA synthesis in certain organs, protein and RNA register below-normal values, indicating that their degradation is much faster than their formation. This postulate is supported: by the enhanced activities of acid cathepsin (a protein-degrading enzyme) and of RNAse A (a RNA-degrading enzyme); by the elevated concentrations of circulating amino acids and total nucleotides; as well as by the accelerated excretion of nitrogenous compounds in the urine and feces of dietary-restricted animals. Modifications of RNA turnover are also evident in the tRNA and soluble RNA fractions of the liver of dietary-insulted rats. Studies on brain mRNA translatability have revealed: that food deprivation elicits a shorter species of pre-mRNA via a reduced polynucleotide elongation rate; that not all poly A+ RNA sequences present in control rats occur in dietary-restricted animals; and that the translatability of polymerase II is far lower in dietary-insulted rats. Other investigations on the translatability of liver, brain, kidney, spleen and thymus mRNA have demonstrated changes in mRNA via altered protein synthesis in various organs of dietary-restricted rats. Generation studies have shown that adaptation prevails in the first, second and third generation offspring of dietary-insulted rats, after which all parameters decline in fourth and fifth generation offspring. By reducing the litter size and exchanging the pups of control and dietary-restricted rats during the lactation period, partial restoration of the cellular growth of different organs is effected with the exception of the brain, in which damage is irreversible.

Brain mRNA translatability in rats: changes during long-term dietary restriction in the developmental period of life.

We studied the effects of graded dietary restriction on the amount and translatability of messenger RNA (mRNA) molecule coding for brain proteins during the developmental period of life. Control experiments were performed on newborn, 1-, 3-, 6- and 27-week-old rats, whereas the dietary restriction studies, involving 10, 30 or 50% food deprivation, were conducted on weanling rats for periods of 3 or 24 weeks. Graded dietary restriction for 3 or 24 weeks caused a progressive reduction of the amount and translatability of mRNA in the rat brain. Complementary DNA (cDNA) probe and hybridization studies with [3H]cDNA revealed that food deprivation elicited a shorter species of mRNA or shorter sequences of the same species of mRNA coding for brain proteins and that not all polyadenylates mRNA [poly(A)+ mRNA] sequences found in control rats were present in the dietary-restricted animals. Furthermore, it appeared that food deprivation produced a shorter species of pre-mRNA via decreased polynucleotide elongation. The mRNA content of 27-week-old rat brains increased 12.5 times in comparison to newborns, representing an augmentation that was progressive and related to the developmental period of life of the animals. The translatability of mRNA was enhanced in the brain of 3-week-old rats, as compared to 1-week-old pups, and did not show any change thereafter. From these studies, it can be concluded that graded dietary restriction considerably modified the metabolism of mRNA in the rat brain, whereas minor alterations occurred during the developmental period of life in control animals.

Metamorphic changes in the hindgut of Sarcophaga ruficornis with special reference to the development of rectal pads.

In Sarcophaga ruficornis, during normal metamorphosis the larval hindgut epithelium degenerates and the imaginal hindgut epithelium is formed from the proliferation and differentiation of the cells of the posterior imaginal ring. The newly formed hindgut becomes slightly dilated posteriorly to form the rectal pouch. At four places in this pouch, the epithelium becomes thick and forms the primordia of the rectal pads. The cells in the primordia begin to divide and project into the lumen of the pouch and later form the cortex cells of the rectal pads. The cavity of the primordia becomes filled with blood cells and fibrous material, which give rise to the medulla of the rectal pads.

Metabolism of adenine nucleotides, nucleic acids and proteins in the liver, brain and kidney of 21-day-old progeny of undernourished female rats.

The metabolism of adenine nucleotides, nucleic acids, and proteins was investigated and compared in the liver, brain, and kidney of the 21-day-old progeny of rats which were well fed (control group) or undernourished during their whole lifetime (experimental group). The in vivo content of various nucleotides (ATP-ADP, cAMP, 5'AMP, and adenosine), the incorporation of radioactive precursor into various nucleotide fractions, and the specific activity of various nucleotides increased considerably in the liver, brain, and kidney of the progeny in the experimental group. Nucleic acid and protein content failed to increase normally in these organs of the progeny in the experimental group. The synthesis of DNA and RNA increased in the liver, brain, and kidney of experimental group progeny. These results suggest that maternal dietary restriction prolonged or blocked the G and S phase of the cell cycle in the liver, brain, and kidney of the progeny of dietary restricted rats.

Mitosis in the haemocytes of Sarcophaga ruficornis (Diptera).

Among the haemocytes of Sarcophaga ruficornis, only the prohaemocytes divide. Injection of phytohaemagglutinin-P induces 100% prohaemocytes to undergo mitosis but does not induce mitosis in other cells. Mitotic stages other than the prophase are apparently very short lived.

Juvenile hormone: effects on a higher dipteran.

Injection of dl-juvenile hormone or C(17) methyl ester into Sarcophaga bullata larvae prevents puparium formation or arrests development at about the 3rd day of pupal-adult development. Topical application to the abdomens of young pupae results in the secretion of a second pupal cuticle. This is the first reported morphogenetic effect of juvenile hormone on a fly.