Low-molecular-weight trypsin inhibitors of microbial origin

Three hundred actinomyces cultures newly isolated from the soil of different regions of the Soviet Union were tested for their ability to produce inhibitors of trypsin-like proteases. Seven previously not known to produce trypsin inhibitors (Streptomyces bikiniensis 17-5, S. sporoclivatus 28-1, S. filamentosus 32-11, S. diastatochromogenes 20-4, S. lavendulae 29-4, S. violacens 52-8, and Streptoverticillium cinnamoneum 36-8) were found to possess high antitrypsin activity. The morphological and cultural properties of the strains and the dynamics of inhibitor production were investigated. S. bikiniensis 17-5 was studied in greatest detail. Its culture filtrate contained several inhibitors for trypsin and one for chymotrypsin. A mixture of oligopeptides with Mr of 300-500 was obtained by the described procedure which included the adsorption of the culture fluid filtrate on charcoal followed by ion-exchange chromatography on CM-cellulose. Four trypsin inhibitors (Sb-IT1, Sb-IT2, Sb-IT3, and Sb-IT4) were isolated from the mixture in a highly purified state by reversed-phase high-performance liquid chromatography. Sb-IT2 has been recognized as formylhistidylvaline with an Mr of 282. No trypsin inhibitor of this structure has been described previously.     

Increased regularity of activity of cortical neurons in learning due to disinhibitory effect of reinforcement

This paper reviews the author's studies on neurophysiologic mechanisms of conditioned reflex learning. Electroencephalograms, evoked potentials, activity of neocortical and hippocampal neurons and the rabbits' behavior in the course of elaboration of defensive and inhibitory conditioned reflexes to light flashes have been recorded. Electric shock (ECS) applied to the paw served as reinforcement. The study demonstrated three types of reinforcement effect on the activity of cortical neurons: activating, disinhibitory, and inhibitory. EEG activation due to reinforcement is accompanied by a change in phasic cortical neuronal activity from chaotic or irregular, typical of rest or inhibition, to regular tonic discharges (in neocortex and hippocampus) and group discharges in the stress rhythm, 5-7 Hz in the hippocampus. Following a number of conditioning trials, the effect of reinforcement is simulated by the effect of a conditioned stimulus. With EEG activation and increased regularity in impulses, facilitation of motor reactions is observed.     

On neurotransmitter mechanisms of reinforcement and internal inhibition

Experiments reported in this study have been performed in order to investigate cholinergic and GABA-ergic neurotransmitter systems and substance P in the realization of internal inhibition and pain reinforcement. This was accomplished during the elaboration of inhibitory and defensive conditioned reflexes to light flashes in alert, nonimmobilized rabbits. Present results together with a review of past research indicate that the cholinergic system is directly involved in transmitting the effects of pain reinforcement to neocortical neurons. Substance P, a neuropeptide, reduces the background activity of neocortical and hippocampal neurons and the response of cortical neurons to pain and positive conditioned stimuli. The cholinergic system and substance P exert a modulating effect on the elaboration of internal inhibition. Phenybut, a GABA derivative capable of penetrating the blood-brain barrier, enhances inhibitory hyperpolarization in the cerebral cortex and improves discrimination between the inhibitory and reinforcing light flashes. It appears, therefore, that the GABA-ergic system plays a leading part in the elaboration of internal inhibition. Neuronal activity and slow potential changes in response to positive conditioned and pain stimuli occur in the same direction after administering the preparations, and the dynamics of these changes is different from that in responses to inhibitory stimuli. It may be supposed on these grounds that the neurotransmitter and neuromodulator systems studied possess a considerable degree of plasticity.     

Neurophysiologic mechanisms of internal inhibition

The experimental results obtained in the authors' laboratory as a result of multiple recording of slow biopotentials, the recording of neuronal activity and of mathematical modeling, are reviewed. The authors conclude that the elaboration of internal inhibition is followed, and determined to a great extent, by the restriction in conduction of excitations due to the increase of inhibitory hyperpolarization and discordance in the periodicity of slow potentials, reflecting oscillations in excitability of neuronal populations in the cortex and other brain structures.     

Comparative Characteristics of the Chemical Composition of Some Brown Algae from the White and Yellow Seas

Russian Journal of Bioorganic Chemistry - Brown algae represent a valuable source of various biologically active compounds. Their accumulation is influenced by many environmental factors. The...     

Role of selection and gene flow in population differentiation at the edge vs. interior of the species range differing in climatic conditions

Evaluating the relative importance of neutral and adaptive processes as determinants of population differentiation across environments is a central theme of evolutionary biology. We applied the Q_ST–F_ST comparison flanked by a direct test for local adaptation to infer the role of climate‐driven selection and gene flow in population differentiation of an annual grass Avena sterilis in two distinct parts of the species range, edge and interior, which represent two globally different climates, desert and Mediterranean. In a multiyear reciprocal transplant experiment, the plants of desert and Mediterranean origin demonstrated home advantage, and population differentiation in several phenotypic traits related to reproduction exceeded neutral predictions, as determined by comparisons of Q_ST values with theoretical F_ST distributions. Thus, variation in these traits likely resulted from local adaptation to desert and Mediterranean environments. The two separate common garden experiments conducted with different experimental design revealed that two population comparisons, in contrast to multi‐population comparisons, are likely to detect population differences in virtually every trait, but many of these differences reflect effects of local rather than regional environment. We detected a general reduction in neutral (SSR) genetic variation but not in adaptive quantitative trait variation in peripheral desert as compared with Mediterranean core populations. On the other hand, the molecular data indicated intensive gene flow from the Mediterranean core towards desert periphery. Although species range position in our study (edge vs. interior) was confounded with climate (desert vs. Mediterranean), the results suggest that the gene flow from the species core does not have negative consequences for either performance of the peripheral plants or their adaptive potential.     

Activity of the Enzymes of the Energy and Carbohydrate Metabolism in the Organs of the Three-Spined Stickleback <Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis> from Different Biotopes of the White Sea

The activity of the key enzymes of the energy and carbohydrate metabolism (cytochrome c oxidase, lactate dehydrogenase, aldolase, and glucose-6-phosphate dehydrogenase) have been studied in the three-spined stickleback Gasterosteus aculeatus spawning in different biotopes of the White Sea (Sel’dyanaya Bay, Sukhaya Salma Strait, and Kolyushkovaya Lagoon). It was found that individuals of stickleback from different spawning grounds differed mainly in the level of anaerobic metabolism and in the degree of utilization of carbohydrates during glycolysis. The results testify to the existence of adaptive mechanisms for the restructuring of the metabolic pathways of the energy metabolism depending on habitat conditions in different biotopes during the spawning period.     

Regional subdivision in wild barley allozyme variation: adaptive or neutral?

We examined the adaptive importance of allozyme variation in wild barley (Hordeum spontaneum). The test involved a nested sampling design with four population groups, each representing a different environment, and a comparison of observed allozyme variation with that expected under the assumption that allozymes are not neutral. Measurements of plant fitness in indigenous and alien environments in reciprocal introductions of seeds and seedlings in the four environments provided a guideline for the expected pattern of allozyme variation. The results showed considerable variation in both the degree of regional and population subdivision and the pattern of the subdivision among loci. The observed pattern of variation was ambiguous. Although two alleles exhibited a pattern of distribution that cannot be explained by genetic drift as a function of geographic distance, we failed to detect either a significant relationship between genetic distance and environmental similarity or any favored epistatic allele combinations across the four environments. Our results suggest that interpretation of allozyme variation in wild barley as adaptive and directly related to local environment still needs justification. Although we could not reject the null hypothesis, a proposed methodology seeking a concordance between observed and "adaptive" (i.e., expected under hypothesis that allozymes are not neutral) allozyme variation may prove to be effective in resolving the neutralist-selectionist debate when applied to other species.