Regulation of Membrane Flexibility in Human Erythrocytes.

We have used spin-labels to detect prostaglandin E induced changes in erythrocyte membranes. The observed changes in spin-label resonance spectra can be mimicked in erythrocyte ghosts by loading them with cAMP or cGMP. These changes can also be observed by adding either of these cyclic nucleotides to intact cells. This entry of cyclic nucleotides into intact cells is blocked by an inhibitor of the anion channel. We suggest that the observed changes in paramagnetic resonance spectra are due to changes in lipid "fluidity" that are brought about by changes in the biochemical state of membrane-associated proteins (such as spectrin) and in the direct or indirect biophysical interactions of these proteins with membrane lipids.     

Effects of change in Gx and Gy in humans on volume-homeostatic mechanisms

Fluid homeostasis was studied in male subjects undergoing changes in gravitational stress by postural changes. Left atrial diameter, blood pressure, and blood and urine were studied. The results of this study indicated that changes in transverse gravitational stimuli affect circulatory, endocrine, and renal systems.     

Plasma levels of catechols during reflexive changes in sympathetic nerve activity

Relationships between changes in levels of catechols and directly recorded sympathetic nerve activity were examined using simultaneous measurements of renal sympathetic nerve activity and arterial and renal venous concentrations of norepinephrine (NE), dihydroxyphenylalanine (dopa), and dihydroxyphenylglycol (DHPG) during reflexive alterations in renal sympathetic nerve activity in anesthetized, adrenal-demedullated rats. Nitroprusside infusion increased renal sympathetic nerve activity by 90%, arterial levels of dopa by 96%, NE by 326%, and DHPG by 141%. Phenylephrine infusion increased arterial DHPG levels by 81% and decreased renal sympathetic nerve activity by 37% and NE levels by 26%; arterial dopa levels were unchanged. Ganglionic blockade by chlorisondamine (with concomitant phenylephrine infusion to maintain MAP) decreased renal sympathetic nerve activity by 65% and NE concentrations by 37%; arterial dopa concentrations were unchanged, and DHPG concentrations increased by 60%. Proportionate responses of arterial levels of NE were strongly related to proportionate changes in renal sympathetic nerve activity. Clearance of DHPG from arterial plasma was prolonged by phenylephrine-induced hypertension and by nitroprusside-induced hypotension. The results suggest that changes in arterial NE levels reflect changes in sympathetic activity; changes in dopa levels reflect changes in catecholamine biosynthesis; and changes in DHPG levels depend on reuptake of released NE and on hemodynamic factors affecting DHPG clearance.     

Effects of anaerobic and aerobic exercises in athletes on the variation of the parameters of oxygen transport systems in different seasons of the year

Observations of the changes in the functional states of athletes of two specializations (wrestlers and skiers) carried out for four years are summarized. The effects of seasonal changes superimposed on adaptive changes caused by training are analyzed. Changes in the erythron reflecting the modulating effect of seasonal environmental changes on the state of the blood system have been found.     

Changes in the histostructure of functional activity of the immunocompetent organs in damaged portal blood supply of the liver

In CBA mice calibrated stenosis of the portal vein was produced. Liver and immunocompetent organs were morphologically analyzed. The total number of hemopoietic stem cells in the bone marrow was estimated by the colony-forming cells and in the spleen after immunization with sheep red cells by the plaque forming method. It is established that stenosis of the portal vein (on the average by 45% and 58%) produced the histostructural changes in the liver and in the immunocompetent organs. Expression of morphological changes depended on the time elapsed after operation and the degree of the portal vein stenosis. These changes were the most pronounced on the 16-17th day when stenosis of the portal vein was 58%. The character of the changes in the number of the hemopoietic stem cells in the bone marrow and in that of antibody-forming cells in the spleen depended on the degree of the liver damage. These changes increased with the degree of the liver histostructure damage. The maximal liver damage was accompanied by a decrease of these indices.     

Light-induced Changes in the Conformation and Configuration of the Thylakoid Membrane of Ulva and Porphyra Chloroplasts in Vivo

The ultrastructural basis of light-induced transmission and light scattering changes of thalli of Ulva and Porphyra were investigated by high resolution electron microscopy and microdensitometry. The results show that upon illumination of dark thalli (a) a reduction in thickness of thylakoid membranes (conformational change), (b) a more regular ordering, and (c) flattening of the thylakoids (configurational changes) have occurred. An explanation for the observed conformational and configurational changes was proposed in terms of correlated changes in ionic environment and osmotic properties of chloroplasts in vivo which are initiated by photosynthetic reactions.     

Rhythmical changes in the division and degradation of symbiotic algae in hermatypic corals

Three types of rhythmical changes in division and degradation (digestion) have been found and described in the symbiotic zooxanthellae of the scleractinian coral Seriatopora caliendrum and in the colonial hydroid Myllepora intricata collected at the reef of Sesoko Island (Okinawa, Japan). The first type of changes reported for S. caliendrum is daily variation of the intensity of these two processes peaking at night. The second type of rhythm changes described in S. caliendrum and M. intricata is opposing variations of cell division and degradation levels with a period of three days. The rhythm is disturbed by sudden weather changes or by variations in light. Rhythmical alterations of zooxanthella proliferation and degradation of the third type found in S. caliendrum have a period of 5–6 days and are connected with oppositely directed changes as well as with alterations of the second type. The rhythm of such alterations is not disturbed by abrupt weather changes. All three types of rhythmical changes in zooxanthellae division and digestion observed in hermatypic coral are supposed to be directed to the regulation of the population density of zooxanthellae in organism tissues.     

Role of corticofugal feedback in hearing

The auditory system consists of the ascending and descending (corticofugal) systems. The corticofugal system forms multiple feedback loops. Repetitive acoustic or auditory cortical electric stimulation activates the cortical neural net and the corticofugal system and evokes cortical plastic changes as well as subcortical plastic changes. These changes are short-term and are specific to the properties of the acoustic stimulus or electrically stimulated cortical neurons. These plastic changes are modulated by the neuromodulatory system. When the acoustic stimulus becomes behaviorally relevant to the animal through auditory fear conditioning or when the cortical electric stimulation is paired with an electric stimulation of the cholinergic basal forebrain, the cortical plastic changes become larger and long-term, whereas the subcortical changes stay short-term, although they also become larger. Acetylcholine plays an essential role in augmenting the plastic changes and in producing long-term cortical changes. The corticofugal system has multiple functions. One of the most important functions is the improvement and adjustment (reorganization) of subcortical auditory signal processing for cortical signal processing.     

Seasonal changes in the amount of carbohydrate and crude protein in the rhizome ofMiscanthus sacchariflorus

In the herbaceous perennials, seasonal changes in the amount of reserve substances play an important role in the production processes of whole plants. Mutohet al. (1968) indirectly estimated the amount of reserve substances stored in the rhizome ofMiscanthus sacchariflorus by measuring the bulk density of the rhizome, and found aarked seasonal changes. In the present study seasonal changes in the carbohydrate and crude protein content of the rhizome were determined and the results obtained were compared with the changes in the total amount of reserve substances estimated by means of changes in the bulk density. A good parallel seasonal relationship was confirmed between the amount of consumable carbohydrate determined chemically and the quantity of reserve substances estimated from the changes in bulk density. The total yields of carbohydrate and crude protein were ca. 75% of the available reserve substances estimated from the changes of bulk density for the old rhizomes and ca. 65% for the new rhizomes in the middle of December.     

The molecular basis of insecticide resistance in mosquitoes

Insecticide resistance is an inherited characteristic involving changes in one or more insect gene. The molecular basis of these changes are only now being fully determined, aided by the availability of the Drosophila melanogaster and Anopheles gambiae genome sequences. This paper reviews what is currently known about insecticide resistance conferred by metabolic or target site changes in mosquitoes.     

Activation of reparative processes by phospholipid preparation in the affected organs and tissues in neonathal enteropathology of calves

The peculiarities of dynamics of quantitative changes of some classes of lipid and phospholipid spectra of blood plasma of calves recovered after dyspepsia were studied. Obtained reliable changes of the blood plasma lipidogrammas testify to development of dyslipidemia. It is characterized by hypercholesterolemia and hypertriacylglycerolemia of recovered 30 days old calves 3 weeks after diseases symptoms past. These changes give evidence concerning deficiency of phosphatides choline fraction - main structural components of cell membranes. It was established that changes of lipid and phospholipid spectra of blood plasma caused by enteropathology can be corrected by the inclusion of reparative therapy preparations to dyspepsia treatment plan in particular--experimental phospholipid containing a drug, which is prepared on the basis of milk phospholipids--its natural source for newborn calves.     

A spectrum of pleiotropic consequences in development due to changes in a regulatory pathway

Regulatory evolution has frequently been proposed as the primary mechanism driving morphological evolution. This is because regulatory changes may be less likely to cause deleterious pleiotropic effects than changes in protein structure, and consequently have a higher likelihood to be beneficial. We examined the potential for mutations in trans acting regulatory elements to drive phenotypic change, and the predictability of such change. We approach these questions by the study of the phenotypic scope and size of controlled alteration in the developmental network of the bacterium Myxococcus xanthus. We perturbed the expression of a key regulatory gene (fruA) by constructing independent in-frame deletions of four trans acting regulatory loci that modify its expression. While mutants retained developmental capability, the deletions caused changes in the expression of fruA and a dramatic shortening of time required for completion of development. We found phenotypic changes in the majority of traits measured, indicating pleiotropic effects of changes in regulation. The magnitude of the change for different traits was variable but the extent of differences between the mutants and parental type were consistent with changes in fruA expression. We conclude that changes in the expression of essential regulatory regions of developmental networks may simultaneously lead to modest as well as dramatic morphological changes upon which selection may subsequently act.     

Transient nature of Toxoplasma gondii-induced behavioral changes in mice

Many parasites induce specific changes in host behavior that promote the transmission of their infective stages between hosts. Toxoplasmosis in rodents is known to be accompanied by specific behavioral changes (shift in activity level, learning capacity, and novelty discrimination) that can theoretically increase the chance of infected animals being eaten by the definitive host, the cat. However, toxoplasmosis is also accompanied by many pathological symptoms. It is not known whether the behavioral changes are products of manipulation activity of the parasite or only nonspecific by-products of pathological symptoms of toxoplasmosis. Here, we compared the dynamics of development of behavioral and pathological changes in Toxoplasma gondii-infected mice. The results showed that the maximum reduction of mouse activity corresponded with the peak of pathological symptoms, and also that maximum increase of reaction times corresponded with the peak of development of tissue cysts in the brains of infected mice. Behavioral changes were only transient and disappeared before the 12th wk postinoculation. The results suggest that the behavioral changes in infected mice reported by many authors and observed in our experiments could be nonspecific by-products of pathological symptoms of toxoplasmosis rather than specific products of manipulation activity by the parasite.     

Changes in the albumin content of mouse hepatocytes in vitro

Using the immunoenzyme method followed by the cytophotometrical analysis the dynamics of albumin content changes in isolated mouse hepatocytes in culture was studied. The data obtained point to cyclic changes of the albumin content in the liver cells with the 1 hour periodicity similar to the changes in the rate of protein synthesis revealed for the same cells.     

Involvement of interferon in virus-induced lymphopenia

Intraperitoneal injection of vesicular stomatitis virus (VSV) into mice causes marked and rapid changes in leukocyte distribution. The virus induces an increase in peripheral blood (PB) granulocytes and an extensive decrease in the lymphocyte count which reaches a nadir of less than 10% of preinfection values, 12 hr after virus inoculation. In the lymph nodes and spleen extensive lymphocyte translocation and granulocyte infiltration are observed. Most changes abate 48 hr following virus inoculation. Injection of poly(rI):(rC) causes similar changes to those observed with VSV. The lymphocyte changes observed after injection of VSV or poly(rI):(rC) coincide with high levels of Interferon (IFN) in the serum. We have examined the effects of anti-IFN antibody on those changes and investigated whether they can be mimicked by injecting IFN. Our findings suggest that the IFN induced by VSV or poly(rI):(rC), rather than those agents themselves, causes the observed lymphopenia as well as some of the changes observed in the spleen. On the other hand, the effects of VSV on granulocyte localization do not appear to be mediated by IFN.     

Hematologic and various immunologic parameters of the body response in experimental epileptogenesis

The aim of present study was to reveal the figures that show the organism reactivity at various stages of the amygdala kindling. We found that a completed kindling formed by stimulation of the piriform cortex, is accompanied by systemic changes in white and red blood. First stages of kindling during the cortical nucleus stimulation are characterised by reactive changes of erythrocytes and thrombocytes suggesting that changes occur in the homeostasis. We discuss possible mechanisms of these changes.     

Changes in DNA conformation induced by gamma irradiation in the presence of copper

Gamma irradiation of DNA solutions containing copper causes changes in DNA conformation in oligonucleotides and in natural and synthetic DNAs. Diagnostic for these conformational changes is a ubiquitous 187-nm peak in the circular dichroism (CD) difference spectrum that has been predicted for a transformation from a right-handed to a left-handed helical DNA conformation. Changes in CD are correlated with changes in the UV spectrum. Reduction of DNA-bound Cu(II) to Cu(I) with ascorbic acid produces similar changes in CD spectra. These changes can be produced by the peroxy radical anion (O2*-) and the OH radical in the presence of copper. O2*- is approximately twice as efficient as *OH in initiating these changes in natural DNA. The changes in DNA conformation induced by ionizing radiation are remarkable in that they are dependent on the copper-ion concentration in a highly nonlinear manner at low copper concentrations and are not observed in the absence of copper ions. Possible implications of our results for radiobiological and oxidative damage in the cell nucleus are discussed.     

Biological activity of thiophosphamide-alkylated DNA in the transformation system of Bacillus subtilis

DNA treated with thiophosphamide was studied for changes in its biological activity in transformation system of Bac. subtilis. DNA alkylation by this three-functional alkylating agent is shown to be followed by the reduction of transforming activity, changes in the competitive ability as well as by a decrease of the cotransfer coefficient for linked markers of transforming DNA. The observed changes in the transforming and cotransforming activities may be explained by variations in the DNA structure.     

Histopathological changes of some organs in the course of experimental Salmonella agona infection of rabbits.

Organ changes evoked by infection with Salmonella agona were evaluated in 30 rabbits. Pathological changes were found not only in the intestines but also in the liver, lungs, spleen, kidney and suprarenal glands. The changes were different from those induced by other serotypes of Salmonella.