Growth of the axons in organotypic culture of the spinal cord

Peculiarities of the axons growth in the culture of 14-day old chick embryo spinal cord after 24, 48 hr, 3, 5 and 7 days in the Maximov's chamber were observed. For the stimulation of axon growth the spinal cord was cultivated simultaneously with the explants of the muscle tissue and in the medium after the addition of supernatant of the somatic muscle. It has been demonstrated that the growth of the axons stimulated with the muscle explants or muscle supernatant takes place through the growth cones, while in the absence of growth stimulation effect glial cells can take part in the axons growth. It is supposed that the glial cells are capable of playing the role of the cells, which direct axons growth in the absence of influence of specific target factor.     

The effect of various forms of thrombin on nonspecific high molecular weight substrates

The ability of native alpha- and non-coagulating gamma-thrombin to catalyze the hydrolysis of nonspecific high molecular weight substrates was studied using chymotrypsinogen and the oxidized insulin B-chain as substrates. The effect of thrombin on chymotrypsinogen was estimated by the appearance of caseinolytic activity measured by the increase in the number of terminal NH2-groups in the 2,4,6-trinitrobenzol sulfonic acid reaction. The same reaction was used to study the hydrolysis of insulin by thrombin. It was found that the destruction of the additional center necessary for fibrinogen proteolysis during the alpha-thrombin conversion to the gamma-form did not affect the enzyme ability to hydrolyze nonspecific protein substrates. It was assumed that the low efficiency of non-physiological high molecular weight substrate hydrolysis by thrombin is due to the lack of specific remote interactions in the regulatory site outside the enzyme active center.     

Effect of starvation and diabetes on the activity of the eukaryotic initiation factor eIF-2 in rat skeletal muscle

The ability of the initiation factor eIF-2 in skeletal muscle extracts to form ternary initiation complexes ([Met-tRNA(f).eIF-2.GDP]) is decreased by either starvation or diabetes. These conditions also impair the ability of muscle extracts to dissociate [eIF-2.GDP], suggesting inhibition of the guanine nucleotide exchange reaction essential for eIF-2 recycling. We could not, however, detect any change in the phosphorylation state of the alpha subunit of eIF-2. This suggests that eIF-2 activity may be regulated in this system by a mechanism not involving its phosphorylation.     

NMR study of 13CO2 incorporation into short-chain fatty acids by pig large-intestinal flora

The nuclear magnetic resonance technique was used to study carbon dioxide reduction by the pig large-intestinal flora. Washed bacterial cell suspensions were incubated for 6 and 15 h under 13CO2 and H2 as the gas phase and with a buffer containing NaH13CO3 and cellobiose and amino acids (casein hydrolysate) as substrates. Methane was produced in all incubation media. Significant amounts of single- as well as multiple-labelled acetate and butyrate were formed, demonstrating synthesis of acetate from H2 + CO2. Propionate was labelled mainly on the carboxyl group, which was attributed to an enzymatic exchange of the carboxyl group of propionate with 13CO2. These results indicate that the reduction of CO2 to acetate may be an important pathway for microbial production of acetate in the pig large intestine even in the presence of methanogenesis.     

Tryptophan 2,3-dioxygenase activity in turkey poults infected with Bordetella avium

1. Liver tryptophan 2,3-dioxygenase (TPO) activity was depressed significantly by the Bordetella avium infection localized in the trachea of the turkey poult. 2. Tryptophan, given orally, induced a significant increase in TPO activity in both control and infected poults. 3. Hydrocortisone induced TPO activity in the turkey in a dose dependent manner.     

Phylogenetic comparisons of the branched-chain alpha-ketoacid dehydrogenase complex

1. Antibodies against the E1b and E2b components of bovine branched-chain alpha-ketoacid (BCKA) dehydrogenase (BCKAD) complex completely inhibited BCKA oxidation in mammalian and avian mitochondria. BCKA oxidation by salmonid mitochondria was less affected and the enzyme from Pseudomonas putida was unaffected. 2. In rodents, anti-E1b E2b IgG inhibited oxidation of all three BCKA in a similar dose-dependent manner: oxidation of alpha-ketobutyrate and alpha-keto-y-methiolbutyrate was also partially inhibited. 3. Except for the salmonid BCKAD, a similar Mr for the E2b and E1b alpha proteins was observed in these species. 4. After digestion with V-8 protease similar immunoreactive peptides were observed for the human and rodent complex.