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

Published data on adsorption and condensation of amino acids, purine and pyrimidine bases, sugars, nucleosides, and nucleotides are analyzed in connection with Bernal's hypothesis that clays and other minerals may have provided the most likely surface for adsorption and condensation of these molecules in prebiotic times. Using surface concentration and reaction rate as the main criteria for the feasibility of condensation reactions, four types of prebiotic environments were analyzed: (1) an ocean-sediment system, (2) a dehydrated lagoon bed produced by evaporation, (3) the surface of a frozen sediment, and (4) a fluctuating system where hydration (rainstorms, tidal variations, flooding) and dehysration (evaporation) take place in a cyclic manner. With the possible exception of nucleotides, low adsorption of organomonomers on sediment surfaces of a prebiotic ocean (pH 8) is expected, and significant condensation is considered unlikely. In dehydrated and frozen systems, high surface concentrations are probable and condensation is more likely. In fluctuating environments, condensation rates will be enhanced and the size distribution of the oligomers formed during dehydration may be influenced by a "redistribution mechanism" in which adsorbed oligomers and monomers are desorbed and redistributed on the solid surface during the next hydration-dehydration cycle.
J Mol Evol 1976 Dec 30
PMID:The possible role of solid surface area in condensation reactions during chemical evolution: reevaluation. 1 25

Cardiac conducting fibers were selected from two dogs defined as A and B. The specimens differed in the reaction of their electron dense granules, commonly referred to as glycogen, to the treatment en bloc with uranyl acetate. Material was fixed in glutaraldehyde and OsO4. Blocks were processed either conventionally or immersed in uranyl acetate before dehydration. Sections were examined unsatined, stained with U and/or Pb or with a histochemical technique (PA-TSC-SP) specific for glycogen. Electron dense granules have affinity to Os, U and Pb which suggests ionic reactions specific for protein but improbable for glycogen. Large granules in A turned into pale ghosts and small granules in B disappeared after treatment en bloc with uranyl acetate. PA-TSC-SP in conventional samples showed glycogen particles arranged into aggregates corresponding in size to the electron dense granules. Treatment en bloc slightly affected glycogen aggregates in A and resulted in a formation of large clumps of glycogen particles in B. It was concluded that the electron dense granules represented protein bound to glycogen in the organelles called glycosomes. Acidic action of uranyl acetate removed protein from glycosomes. The degree of this removal depended on the amount of protein present in glycosomes in the moment of fixation.
Virchows Arch B Cell Pathol Incl Mol Pathol 1979 Jun 29
PMID:Glycosomes (protein-glycogen complex) in the canine heart. Ultrastructure, histochemistry and changes induced by acidic treatment. 9 43

In isolated photosynthetic reaction centres of Rps. spheroides and chromatophores R. rubrum the spectral position of the longest wavelength absorption band of P870, effectiveness of electron removal from the photochemical pair (P870 -- primary electron acceptor, A1) and the rate constant for recombination of photooxidized P870 with photoreduced A1 undergo marked and fully reversible changes over the temperature interval from +20 to -70 degrees. Dehydration of the samples has the effect similar to that induced by temperature lowering. The data suggest that the spectral position of the main maximum of pigment complex P870 absorption band may be regarded as a sensitive inner probe of the structure-functional state of the investigated preparations.
Mol Biol (Mosk)
PMID:[Spectral position of the principal absorption band of pigment complex P870 and the kinetics of photo-induced oxidoreductions in the reaction centers and chromatophores of purple bacteria with preparations at different temperatures and having different degrees of hydration]. 10 46

1. The effects of streptozotocin-diabetes on the local and general responses to a 4 h period of bilateral hind-limb ischaemia in the rat have been investigated. The rats were injured 48 h after the intravenous injection of the streptozotocin. 2. Less fluid was lost from the circulation into the injured limbs after injury in the diabetic rats and this was directly related to the severity of the diabetes, but could not be explained by dehydration. However, when the diabetic and nondiabetic injured rats were considered together there was significant negative correlation between either plasma osmolality or plasma glucose concentration and water content in the injured hind limb. 3. The relationship between plasma glucose concentration and plasma osmolality was changed by injury such that, particularly in the injured diabetic rats, plasma osmolality at a given glucose concentration was higher than that predicted from the relationship betweeen these variables in the uninjured rat.
Clin Sci Mol Med 1978 Apr
PMID:Effect of streptozotocin-diabetes on the local and general responses to injury in the rat. 63 75

Optical and thermochemical properties of E. coli DNA molecules are compared in solutions containing poly(ethyleneglycol) (PEG) in concentrations at which compactization is not yet observed. It is shown that under conditions preceding DNA compactization (CPEG less than 60 mg/ml) changes in CD spectra occur which suggest that the secondary structure of some DNA fragments is altered. These changes of the secondary structure result from dehydration of DNA molecules in PEG-containing solutions. Electron micrographs of DNA molecules obtained under conditions preceding compactization suggest that under these conditions linear DNA molecules may form "four-stranded" fragments as well as double-stranded "loops".
Mol Biol (Mosk)
PMID:[DNA compact form. VI. Changes of DNA secondary structure under conditions preceding its compaction in a solution]. 80 73

1. The intrarenal role of angiotensin II in controlling sodium excretion was examined in anaesthetized, dehydrated dogs by infusing the angiotensin II antagonist Sar1-Ile8-angiotensin II directly into the renal artery. Comparisons were made with dehydrated dogs receiving only sodium chloride solution intrarenally. 2. Intrarenal angiotensin II blockade resulted in significant increases in urinary sodium excretion and urine flow rate. 3. The results indicate that during the high-renin state of dehydration endogenous angiotensin II has intrarenal effects which lead to salt and water retention.
Clin Sci Mol Med 1977 May
PMID:Intrarenal role of angiotensin II in controlling sodium excretion during dehydration in dogs. 86 48

DNA-dependent heat effects accompanying mixing of water-salt (0.3 M NaCl) solutions of PEG and DNA within the range of PEG 10-50 mg/ml at 25 degrees C were determined by the method of difference microcalorimetry. It was found that, unlike optical and hydrodynamical methods, microcalorimetry makes it possible to detect some changes of the DNA-PEG system preceding formation of compact particles of DNA. In the studied range of DNA concentrations (up to 50 X 10(-3) MG/ML) the specific DNA-dependent heat effect is essentially independent of DNA concentration. It is negative and its absolute value increases from 0 to 5 cal/g of DNA in the PEG concentration range from 0 to 35-40 mg/ml after that the rate of its increase raises greatly and at PEG concentration of 50 mg/ml it is equal to 35 cal/g of DNA. It is suggested that the studied DNA dependent heat effects at low concentrations of PEG (less than 40 mg/ml) are caused by dehydration of DNA preceding its compactization.
Mol Biol (Mosk)
PMID:[The compact form of DNA in solution. V. The heat effect preceding compactization of double-chained DNA in PEG containing water-salt solutions]. 94 May 53

1. Rabbit antisera against arginine-vasopressin (AVP) were evaluated for sensitivity and specificity in a radioimmunoassay based on the extraction of AVP from plasma and urine on to Florisil. 2. Comparison of the immunoreactivity of AVP with analogues showed that one antiserum (R2) reacted principally with the hexapeptide ring and another (R4) bound to the tripeptide tail and was reactive with some reduction and hydrolytic products of the native peptide. 3. The minimum amount of AVP measurable in the radioimmunoassay was 1 pg. The extraction of AVP from plasma and urine gave a recovery of 93 per cent (sd 5 per cent). A plasma sample repeatedly assayed with R2 gave a value of 1.4 ng/1 (sd 0.2, n=12). 4. The antiserum specific for the hexapeptide ring (R2) showed that in normal subjects AVP concentration ranged from 3.2 +/- 2.52 ng/1 after dehydration to 0.16 +/- 0.1 ng/1 after water loading.
Clin Sci Mol Med 1976 Dec
PMID:The specificity of antisera for the radioimmunoassay of arginine-vasopressin in human plasma and urine during water loading and dehydration. 107 Apr 18

1. The rate of renal excretion of arginine-vasopressin was determined during unrestricted fluid intake for 24 h and in response to fluid deprivation for 18 h in nine young men with very mild essential hypertension and compared with that in sixteen normotensive men of similar age. 2. Despite an equivalent osmolar stimulus, excretion of arginine-vasopressin was significantly greater in the reference group than in the reference group. This difference increased progressively with increasing dehydration. 3. We suggest that these findings are mainly due to an increased rate of secretion of arginine-vasopressin in response to mild hydropenia in hypertensive patients and that a moderate increase of release of arginine-vasopressin during periods of fluid deprivation may exert vascular effects and thus influence the perpetuation of hypertension.
Clin Sci Mol Med Suppl 1976 Dec
PMID:Increased renal excretion of arginine-vasopressin during mild hydropenia in young men with mild essential benign hypertension. 107 11

1. The vasopressin mRNA in the adult male rat hypothalamus is modulated in two distinct ways by a dehydration stimulus. In addition to the well-established increase in transcript abundance, it has recently been demonstrated that the vasopressin mRNA poly(A) tail increases in length. 2. We have studied the ontogeny of poly(A) tail length modulation in neonates in response to milk deprivation and found that poly(A) tail length changes are age dependent. In neonates older than 12 days of age, the vasopressin mRNA poly(A) tail length increased with milk deprivation and this effect became more marked in older animals. However, in rats 5 to 9 days old, milk deprivation resulted in a detectable though not significant decrease in vasopressin mRNA poly(A) tail length. 3. As milk deprivation is a combination of dehydration and starvation, we investigated the effect of the latter stimulus in more mature animals. We found that starvation modifies the length of the vasopressin mRNA poly(A) tail in a manner opposite that due to dehydration. 4. Our data indicate a novel mode of regulation of the vasopressin mRNA, namely, poly(A) tail shortening. This system provides a model for future studies concerning the adaptive role of poly(A) tail length modulation in response to physiological stimuli.
Cell Mol Neurobiol 1992 Dec
PMID:Decrease in hypothalamic vasopressin mRNA poly(A) tail length following physiological stimulation. 136 91


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