Further studies on mevalonate phosphorylation in neonatal chick brain

Mevalonate phosphorylation was studied in neonatal chick brain. Formation of phosphorylated derivatives of mevalonic acid increased with the pH in the range assayed (5.5–9.5). Phosphomevalonate kinase was completely inactivated after treatment at 50°C for 5–10 min, whereas mevalonate kinase was found to retain its activity under the same conditions. Exposure to 65°C for 5 min resulted in the inactivation of mevalonate kinase. Both mevalonate-activating enzymes from chick brain were located primarily in the soluble fraction. The amounts of phosphomevalonic acid and pyrophosphomevalonic acid did not show a significant diurnal variation to suggest the presence of a circadian rhythm in either kinase. Cholesterol feeding and fasting had no effect on mevalonate phosphorylation by neonatal chick brain.     

Activity of some enzymes of energy metabolism during denervation and reflex atrophy in rat slow and fast muscles

The loss of muscle weight in the soleus (SOL) and extensor digitorum longus (EDL) muscles was compared after denervation and in the course of reflex muscle atrophy induced by unilateral fracture of metatarsal bones of the paw and local injection of 0.02 ml turpentine oil subcutaneously. This so-called reflex atrophy is significantly greater after 3 days than that after denervation. Seven days after the nociceptive stimulus, reflex and denervation atrophy are grossly similar in both muscles. This also applies in case that the nociceptive stimulus had been repeated on the third day. The EDL:SOL enzyme activities of energy supply metabolism reflect the differences between a glycolytic-aerobic (EDL) and predominantly aerobic type (SOL) of muscle. No consistent changes were found in either type of atrophy after 3 days. In 7 days' denervation, the activity of hydroxyacetyl-CoA-dehydrogenase (HOADH) and citrate synthase (CS) was decreased in the SOL, while glycerolphosphate:NAD dehydrogenase (GPDH) was enhanced. In the EDL, the activity of triosephosphate dehydrogenase (TPDH), GPDH, malate dehydrogenase (MDH), CS and HOADH was decreased. Acid phosphatase (AcP) was greatly increased in both muscles. Seven days after application of the nociceptive stimulus, all enzyme activities were altered in a grossly analogous manner as after denervation.     

Genes involved in the activation of the bithorax complex ofDrosophila

Summary We have studied the genetic properties and developmental effects of several mutations, in eight different loci, which alter the specification of embryonic segments. All of the changes are related to the transformations caused by mutants of the bithorax complex.Several properties: the interactions of these mutants with different mutants of the bithorax complex, the interactions between themselves, the effect of changing dosages of their wildtype alleles and their response to ether induction of phenocopies permit one to distinguish between those mutations which affect activation of the bithorax genes in early embryogenesis and those which affect expression of the bithorax genes during development. This paper deals mainly with the Rg-bx locus and its interactions with other loci which affect segment specification.In particular two loci show genetic and developmental characteristics which seem to conform to those expected for a repressor coding gene (Polycomb) and for an inducer synthesizing gene (Rg-bx) active in a negative control system of the genes in the bithorax complex. A model for the interaction of the wildtype products of these genes to determine the segmental characteristics of both the thorax and abdomen is proposed.     

The role ofH-2 regions in overcoming tissue incompatibility

Neonatal transplantation tolerance to the products of theH-2 ^b complex was induced in B10.A (H-2 ^a ) mice. On the basis of the survival of skin allografts it was found that antigens determined by theD region of theH-2 ^b complex (of the B10.A(2R) strain) were most easily overcome and that tolerance to the products of theD end of theH-2 complex (of the B10.A(4R) strain) was also easy to induce. The antigens produced by theK end ofH-2 (of the B10.A(5R) and B10.A(3R) strains) represented a stronger incompatibility barrier and a difference in the entireH-2 ^b complex caused strongest resistance to tolerance induction. When tolerance to the products of the entireH-2 ^b complex was induced in newborn B10.A mice, and the neonatally treated animals were grafted simultaneously with five different grafts, those disparate at theK end ofH-2 and in the entireH-2 region were rejected in some animals, while the grafts disparate at theD end of H-2 remained intact in the same mice. No dependence on theI-J subregion was observed in this system. Furthermore, tolerance was more easily inducible in male than in female B10.A mice.     

A method for the estimation of amino acid radioactivity in biological samples

A method for quantitative estimation of total radioactivity present in the free amino acid fraction of tissue samples has been described. Samples deproteinized with cold acetone were extracted, in acidic medium, with ethyl (peroxide free); after centrifugation, the aqueous phase was used for amino acid derivatization at 40°C for 15 h with 1-flouro-2,4-dinitrobenzene in bicarbonate-buffered medium. Aliquots of the derivatized samples were acidified and extracted twice again with ethyl ether. The combined organic phases were placed in glass scintilation vials, dried, and used for the determination of its radiactivity, corresponding to the radioactivity present in the free amino acid fraction of the sample. Deproteinized samples of rat blood plasma, as well as hen egg white and yolk were tested after addition of known quantities of ¹⁴C-labelled amino acids or glucose, for validation of the method. No glucose radioactivity was found in any of the extracted samples. All radioactivity added to the samples in the form of ¹⁴C-labelled alanine, glutamic acid, leucine and phenylalanine was quantitatively recovered in the derivatized fraction; only a fraction of arginine radioactivity was recovered.     

Rhodotorula matritense sp. nov., isolated from powdered red pepper (Capsicum frutescens L.)

A new species of Rhodotorula Harrison was recovered in May 1978 from Spanish powdered red pepper (Capsicum frutescens L.) in Madrid, Spain. It could not be identified with any hitherto described species of yeast and it was assigned to the genus Rhodotorula Harrison as representative of a new species on the bases of both its morphological and physiological characteristics, for which the name of Rhodotorula matritense is proposed.     

A reliable and sensitive method for the simultaneous determination of dopamine, noradrenaline, 5-hydroxytryptamine and 5-hydroxy-indolacetic acid in small brain samples

A sensitive and reliable fluorometric method for the simultaneous determination of dopamine, noradrenaline, 5-hydroxytryptamine and 5-hydroxy-indol acetic acid in small samples of brain tissues is described. The procedure is based on solvent extraction; catecholamines are oxidized by the Chang's method and 5-hydroxytryptamine and 5-hydroxy-indol acetic acid determined by reaction with o-phthalaldehyde, alpha-methyl-p-tyrosine causes a negligible interference with the procedure. Results of determination of these amines in different brain areas are reported.