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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study investigates growth and the induction of progesterone-receptor synthesis in the immature (day 20--23) rat uterus after injection of different doses of 5 alpha-dihydrotestosterone (DHT) and testosterone (T) in long- and short acting injection vehicles. Moderate doses of T (300 microgram/day in saline for 3 days) elicit uterine growth (ca. 250% of control) that is abolished by concomitant injections of antiandrogen (1 mg flutamide/day or 8 mg DIMP/day) but is unaffected by injections of antiestrogens (60 microgram CI-628 or U11,100A/day). Uterine growth evoked by 17 beta-estradiol (3 microgram/day for 3 days) is, however, only antagonized with the antiestrogens but not antiandrogens. Experiments employing whole uteri in vitro indicate that the specific nuclear uptake of 10(-8) M [3H]T is markedly inhibited by the antiandrogens DIMP, flutamide, and the hydroxylated flutamide metabolite (LACT) [LACT greater than DIMP greater than FLUT] while the antiestrogens CI-628 and U11,100A are ineffective. In contrast, the specific nuclear uptake of 10(-8) M [3H]-estradiol is inhibited by only the antiestrogens and not antiandrogens. When very high (5 or 10 mg) doses of DHT Are administered in an oil-containing injection vehicle, nuclear translocation and cytoplasmic depletion of the estrogen receptor does occur and a uterotrophic response is elicited which is resistant to antagonism by antiandrogen. Likewise, the DHT-stimulated increase in progesterone-receptor content is not decreased by concomitant antiandrogen. Similar 5 or 10 mg doses of DHT, administered in a water-soluble dimethylsulfoxide vehicle, show little estrogen-receptor movement and the DHT-induced uterine growth and induction of progesterone-receptor synthesis is almost completely eliminated with antiandrogen. Regardless of the degree of uterine growth stimulation, however, the androgens are poor stimulators of uterine progesterone-receptor synthesis compared with estradiol. These results indicate that androgens may interact with both the androgen- and estrogen-receptor systems in the uterus in inducing uterine growth and that the nature of the cellular mechanism, i.e., whether the androgen- and/or estrogen-receptor system is involved, is dependent critically upon the in vivo dose of androgen and the mode of hormone administration.
Mol Cell Endocrinol 1979 Aug
PMID:Androgen-uterine interactions: an assessment of androgen interaction with the testosterone- and estrogen-receptor systems and stimulation of uterine growth and progesterone-receptor synthesis. 49 51

Different physico-chemical methods (CD, ORD, small-angle X-ray diffraction, etc) were used for investigating the properties of the DNA compact particles formed in PEG-containing water-salt solutions. It has been shown that small-angle reflection, characteristic of the DNA compact particles, changes from 36.8 A (CPEG = 140 mg/ml) to 25 A (CPEG = 300 mg/ml). The maximal optical activity (the intense negative CD-band and optical rotation [alpha] = 60 000 degrees) are inherent properties of the DNA compact particles formed at CPEG 120--180 mg/ml. The high optical activity points to the twist of DNA chromophores through the DNA molecule resulting in a long-rang pitch (P approximately 2000A). Such macroscopic superhelical structure (diameter 40--30 A) is due to conformational distortion of the DNA double-helix with alternating "left" and "right" orientation of chromophoes. Disappearance of conformation distortion is accompanied by disappearance of the high optical activity of the DNA compact particles and results in a small-angle reflection of 25 A. Taking into account the reasons of formation of the optically-active DNA compact particles conditions are suggested to conserve high optical activity at CPEG equal to 400 mg/ml.
Mol Biol (Mosk)
PMID:[Correlation between conformation distortion of the DNA sugar-phosphate backbone and high optical activity of its compact form]. 50 60

A method, using albumin-pyrene complexes, has been developed for labeling, in a controlled manner, crab leg nerves whose excitability was preserved. The excimer-to-monomer fluorescence intensity ratio of pyrene, embedded in nerve membrane lipids and in their crude lipid extracts, is a fluidity parameter which displayed the following features with temperatures. a--a temperature-dependent increase of fluidity b--three breaks (6 degrees, 19 degrees and 37 degrees C) in the physiological medium c--In Ca++-depleted sea water, the 37 degrees characteristic temperature vanished. These breaks may reflect some lateral phase separations of the lipid components of nerve membranes. The calcium dependent temperature break may involve a segregation of acidic phospholipids while the other two breaks (6 degrees and 19 degrees C) may be due to neutral lipids phase separation. The relationship of these findings to nerve function is discussed.
Mol Cell Biochem 1979 Nov 01
PMID:Temperature dependence of the fluorescence of pyrene labeled crab nerve membranes. 51 67

A laboratory study of the interaction of H2O frost with samples of the minerals olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3 at -11 degrees C to -22 degrees C revealed that an acidic oxidant was produced. Exposure of the frost-treated minerals to liquie H2O produced a sudden drop in pH and resulted in the production of copious O2(g) (as much as approximately 10(20) molecules g-1). Exposure of frost-treated samples to 5 ml of 0.1M HCOONa solution resulted in the rapid oxidation of up to 43% of the formate to CO2(g). These reactions were qualitatively similar to the chemical activity observed during the active cycles of the Viking lander Gas Exchange and Labeled Release Biology experiments. Attempts to identify the oxidant by chemical indicators were inconclusive, but they tentatively suggested that chemisorbed hydrogen peroxide may have formed. The formation of chemisorbed peroxide could be explained as a byproduct of the chemical reduction of the mineral. The following model was proposed. H+ was incorporated into the mineral from surface frost. This would have left behind a residual of excess OH-(ads) (relative to surface H+). Electrons were then stripped from the surface OH-(ads) (due to the large repulsive potential between neighboring OH-(ads)) and incorporated into the crystal to restore charge balance and produce a chemical reduction of the mineral. The resultant surface hydroxyl radicals could then have combined to form the more stable chemisorbed hydrogen peroxide species. While the chemisorbed peroxide should be relatively stable at low temperatures, it should tend to decay to O(ads)+ H2O(g) at higher temperatures with an activation energy of greater than or approximately 34 kcal mole-1. This is consistent with the long-term storage and sterilization behavior of the Viking soil oxidants. It is possible that as little as 0.1--1% frost-weathered material in the martian soil could have produced the unusual chemical activity that occurred during the Viking Gas Exchange and Labeled Release experiments.
J Mol Evol 1979 Dec
PMID:Frost-weathering on Mars: experimental evidence for peroxide formation. 52 48

Physical and chemical considerations permit the division of the near-surface regolith on Mars into at least six zones of distinct microenvironments. The zones are euphotic, duricrust/peds, tempofrost, permafrost, endolithic, and interfacial/transitional. Microenvironments vary significantly in temperature extremes, mean temperature, salt content, relative pressure of water vapor, UV and visible light irradiance, and exposure to ionizing radiation events (100 Mrad) and oxidative molecular species. From what is known of the chemistry of the atmosphere and regolith fines (soil), limits upon the aqueous chemistry of soil pastes may be estimated. Heat of wetting could reach 45 cal/g dry soil; initial pH is indeterminate between 1 and 10; ionic strength and salinity are predicted to be extremely high; freezing point depression is inadequate to provide quantities of liquid water except in special cases. The prospects for biotic survival are grim by terrestrial standards, but the extremes of biological resiliency are inaccessible to evaluation. Second-generation in situ experiments which will better define Martian microenvironments are clearly possible. Antarctic dry valleys are approximations to Martian conditions, but deviate significantly by at least half-a-dozen criteria.
J Mol Evol 1979 Dec
PMID:Chemical and physical microenvironments at the Viking landing sites. 52 49

The results of the Viking Biology experiments are best explained by non-biological phenomena: The interaction of the reagents with the materials comprising the regolith. Conditions of water activity, temperature, availability of carbon sources and others in most regions of the planet are too extreme for survival and growth of any known Earth microorganisms. Although the possibility persists that some very unusual form of life is somewhere on that planet the evidence is best interpreted as negative. Even though there is no evidence for current life on Mars, whether or not life ever originated there is not known.
J Mol Evol 1979 Dec
PMID:The Viking Mission: implications for life on Mars. 52 54

One of the scientific objectives of the Viking Mission to Mars was to accomplish an analysis of water in the Martian regolith. The analytical scheme originally envisioned was severely compromised in the latter stages of the Lander instrument package design. Nevertheless, a crude soil water analysis was accomplished. Samples from each of the two widely separated sites yielded roughly 1 to 3% water by weight when heated successively to several temperatures up to 500 degrees C. A significant portion of this water was released in the 200 degrees to 350 degrees C interval indicating the presence of mineral hydrates of relatively low thermal stability, a finding in keeping with the low temperatures generally prevailing on Mars. The presence of a duricrust at one of the Lander sites is taken as possible evidence for the presence of hygroscopic minerals on Mars. The demonstrated presence of atmospheric water vapor and thermodynamic calculations lead to the belief that adsorbed water could provide a relatively favorable environment for endolithic organisms on Mars similar to types recently discovered in the dry antarctic deserts.
J Mol Evol 1979 Dec
PMID:The analysis of water in the Martian regolith. 52 56

The origin of the channels on Mars has been a subject of intense interest since they were first recognized on early Mariner 9 images (Driscoll, 1972; Masursky, 1973). Their presence on the planet, and their striking resemblance to terrestrial flood channels related to glacial outbursts or to dendritic river systems has suggested to most investigators (Baker, 1974, 1977; Nummedal, 1978; Carr, 1979; Masursky et al., 1977) that they were formed by running water. Because life as we know it is dependent on water, the discovery by the 'Mariner cameras', of watercut channels and volcanoes as a source for water, and water ice in the residual north polar cap by Viking, has reaffirmed the choice of Mars as the best target for the search for extraterrestrial life.
J Mol Evol 1979 Dec
PMID:Martian channels and the search for extraterrestrial life. 52 57

The gas chromatograph mass spectrometer instrument of the Viking mission has demonstrated the absence of organic compounds in the immediate surface layer of the two landing sites. The demonstration of the successful operation of the instrument (comparison of ground-based test data with those obtained during interplanetary flight and the data from the surface of the planet) and its limitations (e.g., the detection of highly cross-linked polymers or polymeric carbon suboxide) are reviewed. The measurements for bound water are based on indirect data, the detectability of evolved carbon dioxide and ammonia is poor, and oxygen, liberated from the soil samples, can not be detected.
J Mol Evol 1979 Dec
PMID:The implications and limitations of the findings of the Viking organic analysis experiment. 52 60

A facility was established for long-duration ultraviolet (UV) radiation exposure of natural and synthetic materials in order to test hypotheses concerning Martian soil chemistry observed by the Viking Mars landers. The system utilized a 2500 watt xenon lamp as the radiation source, with the beam passing through a heat-dissipating water filter before impinging upon an exposure chamber containing the samples to be irradiated. The chamber was designed to allow for continuous tumbling of the samples, maintenance of temperatures below 0 degrees C during exposure, and monitoring of beam intensity. The facility also provided for sample preparation under a variety of atmospheric conditions, in addition to the Mars nominal. As many as 33 sealed sample ampules have been irradiated in a single exposure. Over 100 samples have been irradiated for approximately 100 to 700 h. The facility has performed well in providing continuous UV irradiation of multiple samples for long periods of time under simulated Mars atmospheric and thermal conditions.
J Mol Evol 1979 Dec
PMID:Mars ultraviolet simulation facility. 52 61


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