Kinetic model of the effect of dehydration on electron transfer from membrane-bound cytochrome c to the photosynthetic reaction center

Amplitude characteristics and kinetics of laser-induced oxidation of high-potential cytochrome CH by a photosynthetic reaction center (RC) were investigated in Ectothiorhodospira shaposhnikovii chromatophore preparations of various humidity. It is shown that the diminuition of the amount of oxidized cytochrome and the decrease of the rate of the reaction on lowering the preparation humidity can be explained in terms of the concept of conformation-controlled electron transfer within the CH-RC complex. A model is suggested which predicts that the reversible transition of the complex from one conformational state which allows electron transfer ("contact" state) to the other in which the transfer is impossible ("non-contact" state) is the result of drying (or low temperature) induced changes in the electron tunnelling path in the region of "contact" of the cytochrome CH and RC protein globules.     

Neuronal reactions in the dorsolateral pontine area during the immobility response in rats

Reactions of 277 neurones located in the brain pons dorsolateral portion were analised in staying awake and narcotized rats during immobility reflex, induced by the skin constriction on the neck dorsal surface. Got excited: fast adaptive tactile neurons (n = 32), interneurons (n = 42), and cells forming monosynaptic inputs to the parts of medulla oblongata, which inhibit the movements (n = 10). Were inhibited: somatosensory (n = 42), nociceptive (n = 24) and nonidentificated (n = 14) neurons. In some neurons charge characteristics were stable or slightly modified, namely: respiratory neurons (n = 16), cell group, having stable background firing (n = 72) and stimulating antidromically spontaneously silent ponto-medullar neurons (n = 22).     

Paradoxical vagal effects on the cardiac rhythm in cats

In anaesthetised cats, an increase in the vagal burst rate resulted in a paradoxical decrease of vagal bradycardia. This seems to be due to a shift of the vagal stimulus position towards early phase of cardiac cycle. The mechanism of this paradoxical effect depends on the magnitude of vagal chronotropic effect upon the time of vagal stimulus delivery within cardiac cycle.     

Neurochemical analysis of the amygdala basolateral nucleus of rats during anxiety tests

Chlordiazepoxid, phenibut, indoter, campiron, campironin, when administered into the amygdala, improve the anxiety condition of rats in avoidance tests and resemble by their effects dophamine, GABA, or serotonin. Observed differences in the anxiolytic effects between anxiosedative and anxioselective agents seem to be due to an unequal contribution of the monoamin- and aminoacidotergic transmitters into the mechanisms of heteromodal aversive anxiety genesis in the basolateral area of the amygdalar complex.     

Effects of delta-sleep-inducing peptide during ischemic injury of the rat brain

An anti-ischemic effect of the delta-sleep-inducing peptide (DSIP) was found in rats. The DSIP effect was more obvious than that of the MK-801. The data obtained is discussed considering a possible use of the DSIP for brain stroke prophylaxis.     

Gas exchange and oxygen transport during long term hypothermia following a hypothermal apnea in rats

The data obtained show that, at the initial stages of hypothermia, a decrease in the oxygen consumption and carbon dioxide production, cardiac output, and heart rate occurred in accordance with the temperature coefficient. Suppression of the tissue gas exchange was unrelated to disorders in the lung gas exchange but determined rather by a progressing weakening of heart activity, decrease in the cardiac output, and increase in the general vascular peripheral resistance.     

The induction of allophanate lyase during the vegetative cell cycle in light-synchronized cultures of Chlamydomonas reinhardi.

Allophanate lyase can be induced by urea or acetamide 20-40-fold within 4 h in NH4 + -deprived cultures of Chlamydomonas reinhardi. In light-synchronized cultures, allophanate lyase induction appeared to be limited to the light phase of the cell cycle, provided that culture samples were induced under ongoing illumination conditions (i.e. light induction of light phase cells and dark induction of dark phase cells). However, when culture samples were induced under constant light conditions this cell cycle pattern was abolished. Light was found to be required for allophanate lyase induction and this was shown to be due, in part, to the light requirement for inducer uptake. The relationship between allophanate lyase induction and gametogenesis is discussed.