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Results for “Factor For Inversion Stimulation Protein”

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PubMed2026

The Absence of E. coli Nucleoid-Associated Protein FIS at Low Temperature Leads to an Adaptation Response That Causes a Shift Towards Genome Compaction in Small Rods.

In contrast to the rod shape at 37°C, the morphology of Escherichia coli cells at temperatures just above the minimum temperature of growth is small rods. A study was initiated to determine the requirement of nucleoid-associated protein FIS for growth and genome compaction in the small rods at low temperature. Growth and nucleoid staining analyses revealed that the fis null mutant displayed decreased growth and initially formed filaments containing decondensed nucleoids at 12°C, indicating that FIS facilitates production of small rods with condensed nucleoids at low temperature. However, characterized by biphasic growth at low temperature, the fis null mutant exhibited increased growth, cell division, and nucleoid condensation following an acclimation phase. Therefore, the absence of FIS with nucleoid decondensation leads to an adaptation mechanism, termed FIS Null Adaptation Response, that causes a shift towards nucleoid condensation resulting in genome compaction in small rods. Furthermore, overproduction of the HsIVU protease suppressed the cold-sensitive phenotypes of the fis null mutant indicating that degradation of a natural substrate of the protease alleviates the requirement of FIS at low temperature. In addition, null mutations of genes encoding natural substrates of HsIVU (exoribonuclease RNAse R, and cell division inhibitor SulA) were identified as extragenic suppressors of the fis null mutation.

Escherichia coli↗

PubMed1977

Effect of medium composition on protein degradation and DNA synthesis in rat embryo fibroblasts.

Fibroblasts in medium deficient in serum, amino acids, phosphate, or glucose stop synthesizing DNA and increase the rate of degradation of their long-lived cellular proteins approximately 2-fold. There is no difference in the rate of degradation of short-lived proteins under these conditions. Insulin, dexamethasone, and fibroblast growth factor act synergistically to inhibit protein degradation and to stimulate thymidine incorporation to about the same extent as serum. When the medium content in serum or fibroblast growth factor is varied over a wide range, there is a close, inverse correlation between the rate of protein degradation and the extent of thymidine incorporation. When serum is added to cells that have been deprived of serum, the inhibition of protein degradation is immediate whereas the enhanced rate of protein degradation in serum-free medium is attained within 1 hr after serum removal. A 30-min exposure to serum followed by incubation in serum-free medium was as effective as continuous exposure to serum in stimulating thymidine incorporation after 8-24 hr.

Animals↗

PubMed1977

Differential requirements for polypeptide chain initiation complex formation at the three bacteriophage R17 initiator regions.

The initiation specificity of washed E. coli ribosomes in the presence and absence of purified initiation factors and/or S1 protein has been examined in protection experiments using 32P-labelled R17 RNA. We find that the three bacteriophage initiator regions do not exhibit equal requirements for either of these components during initiation complex formation. Specifically, both factors and S1 stimulate ribosome binding to the beginnings of the coat and replicase cistrons to a greater extent than they promote recognition of the A protein initiation site. The differential effects are therefore inversely correlated with the degree of mRNA-16S rRNA complementarity exhibited by the three initiator regions. We also observe that S1 suppresses ribosome binding to spurious sites in the R17 RNA.

Bacterial Proteins↗

PubMed1976

The effect of dibutyryl cyclic adenosine-3'-5'-monophosphate on protein secretion from the rat exocrine pancreas in vitro.

1 The mechanism by which dibutyryl cyclic adenosine-3'-5'-monophosphate (dibutyryl cyclic AMP) potentiates the secretory effect of carbachol in rat exocrine pancreas was investigated. 2 Dibutyryl cyclic AMP potentiated the secretory effect of carbachol only at carbachol concentrations greater than or equal to 10(-7) mol/l; was independent of carbachol at concentrations greater than 10(-7) mol/l and was inversely proportional to extracellular [Ca2+]. 3 Carbachol increased and dibutyryl cyclic AMP reduced the rate of 45Ca efflux from the tissue. 4 A-23187 stimulated 3H-protein release in the presence of Ca2+ and this effect was potentiated by dibutyryl cyclic AMP; the degree of potentiation was inversely proportional to extracellular [Ca2+]. At 10(-3) mol/l [Ca2+] the potentiation occurred only at ionophore concentrations less than or equal to 10(-6) mol/litre. 5 These results support the hypothesis that dibutyryl cyclic AMP potentiates the effect of secretagogues in rat exocrine pancreas by maintaining an elevated intracellular calcium concentration. It does so by inhibiting Ca2+ efflux. The results also suggest that the limiting factor in carbachol-stimulated secretion, at all concentrations of carbachol, is intracellular [Ca2+].

Animals↗

PubMed1977

Cyclic AMP and adenyl cyclase in brain tumors.

Some of the regulatory mechanisms of cyclic adenosine monophosphate (AMP) production in human brain tumors were investigated by assessing both cyclic AMP levels and adenyl cyclase activity. A large disparity was found between the levels of cyclic AMP of normal brain and brain-tumor tissue. Cyclic AMP levels were much lower in brain tumors (25.8 pmoles (picomoles)/mg protein) than in normal brain (98.8 pmoles/mg protein). These studies also show that the abnormally low levels of cyclic AMP in tumors parallel those of adenyl cyclase. The mean adenyl cyclase activity of brain tissue was found to be 111.0 pmoles of cyclic AMP/min/mg protein, while that of the tumor was only 23.0 pmoles/min/mg protein. Levels of cyclic AMP and adenyl cyclase activity were inversely related to the degree of malignancy. Attempts to stimulate adenyl cyclase in homogenates of human brain and brain tumors resulted in a similar response in both tissues. Norepinephrone was the most effective stimulant and produced a two- to threefold increase in cyclic AMP production, while histamine had no effect. It is concluded that one of the factors governing tumor growth may be a defect in the adenyl cyclase system.

Adenylyl Cyclases↗

PubMed1978

The effect of the extent of hydrolysis in casein on its specific dynamic action in the rat.

1. Adult female rats given a diet containing 200 g casein/kg showed an increase in heat production which reached a maximum in 10--20 min after completion of food intake. 2. Replacement of casein in the diet by enzymic hydrolysates of casein of different extents of hydrolysis (pepsin for 1 or 3 h and pancreatin for 6, 12 or 24 h) resulted in a decrease in metabolic rate (stimulation) in the rat, reaching a maximum of 61.8% of the control value (non-hydrolysed casein). 3. The specific dynamic action of casein and casein hydrolysate was inversely proportional to the amount of amino-nitrogen released. 4. On the basis of the experimental findings it may be concluded that the synthesis and secretion of digestive enzymes were the main causes of the increase in metabolic rate after protein ingestion.

Animals↗

PubMed1977

Effect of infection on food intake and the nutritional state: perspectives as viewed from the village.

Data from a prospective study of a Guatemalan village population revealed an exceedingly high force of infection which may effect nutrition and growth from gestation onward. Maternal morbidity was higher and fetal antigenic stimulation was more frequent than in industrial societies. Infection of the young child was a common occurrence and although a great many infections were silent, morbidity rates were extremely high, particularly during the protracted weaning period (6 to 24 months). Infectious disease was found to be an important cause of weight loss, arrest in height, and impaired physical growth. Also, it was a common precipitating factor of severe malnutrition and death. Analysis of the dietary data of fully weaned children did not reveal a deficit in protein intake. Most children, however, had very low calorie intakes. Infectious disease was a common cause of anorexia and of marked reduction in calorie intake, followed by weight loss and impaired physical growth. A strong inverse correlation was detected between infectious disease and calorie intake in the 2nd year of life, when children were being weaned. Infection is the most important isolated factor in the causation of malnutrition in the village. A reorientation of health and nutrition policies seems in line in view of failures of food supplementation programs, particularly with protein, in many parts of the world.

Breast Feeding↗

PubMed1979

Intestinal calcium-binding protein and calcium absorption in cortisol-treated chicks: effects of vitamin D3 and 1,25-dihydroxyvitamin D3.

Vitamin D3 in rachitic chicks stimulates calcium absorption and induces the synthesis of two pools of intestinal calcium-binding protein (CaBP), one soluble and the other membrane bound. Cortisol acetate caused a decrease in calcium absorption which was accompanied by a decrease in soluble CaBP. Cortisol was similarly effective in 1,25-dihydroxyvitamin D3-dosed chicks, suggesting that the glucocorticoid effect was not entirely due to the defective synthesis of this metabolite. Ca absorption was directly correlated with soluble CaBP and alkaline phosphatase and inversely related to the ratio of bound to soluble CaBP. It was further observed that the slope of the Ca absorption vs. soluble CaBP regression line was greater in chicks given 1,25-dihyroxyvitamin D3 compared to those given vitamin D3, and this is interpreted to mean that another factor or condition, in addition to assayed concentrations of soluble CaBP, determines the degree of calcium absorption.

Alkaline Phosphatase↗

PubMed2025

Mendelian randomization reveals causal relationships between cytokines and male reproductive diseases.

This study aims to explore the causal links between cytokines and four male reproductive disorders, namely abnormal spermatozoa (AS), male infertility, erectile dysfunction (ED), and hyperplasia of prostate (HP), employing a two-sample Mendelian randomization (MR) approach. Genetic associations with male reproductive diseases were derived from the IEU OpenGWAS project, with cytokine data from two GWASs focused on the human proteome and cytokines. Estimations were derived using inverse variance weighting, MR-Egger regression, weighted median, weighted model, and simple mode. Furthermore, the robustness of the findings was evaluated through Cochran's Q-test, MR-Egger regression, and leave-one-out sensitivity analysis. Fifteen unique cytokines were identified as having causal relationships with the risk of four male reproductive disorders. Specifically, for AS, interleukin-22 (IL-22), IL-12, and macrophage migration inhibitory factor were negatively correlated with AS, while tumor necrosis factor β levels were positively correlated with AS. In the context of male infertility, IL-2 receptor antagonist levels, IL-34, and granulocyte-colony stimulating factor levels were positively linked to male infertility, whereas IL-21 showed a negative relationship. Regarding ED, IL-19, IL-1β, and eotaxin levels were negatively associated with ED risk, while macrophage inflammatory protein 1β (MIP-1β) levels and interferon gamma-induced protein 10 levels were positively associated. As for HP, stromal-cell-derived factor 1α levels and MIP-1α levels revealed negative associations with HP. In conclusion, this MR analysis revealed that several cytokines were causally associated with male reproductive diseases and could be valuable in offering new insights for further mechanistic and clinical investigations of cytokines-associated male reproductive diseases.

Male↗

PubMed1976

Demonstration of the existence of a single morphological type of gonadotrophic cell in Ellobius lutescens (Microtinae) by an ultrastructural analysis of their development under various physiological and experimental conditions.

Ultrastructural studies of pituitaries from Ellobius lutescens (immature males and females, adult hypogonadic males, and virgin and pregnant females) show that the gonadotrophic cells are characterized by a lamellar or vacuolar rough endoplasmic reticulum (RER), a spirally-arranged Golgi apparatus, elongated mitochondria and secretory granules of variable density and size (150-500 mmu). Ultrastructural differences between gonadotrophic cells previously determined by light microscopy correspond to changes in the development of the protein synthetic apparatus and in the intensity of hormonal discharge. Type 2 gonadotrophs always appear to be more active than type 1 gonadotrophs. After castration, all gonadotrophic cells develop into the same form of "castration cell", although type 1 gonadotrophs change more slowly than type 2 cells. Treatment with testosterone induces an inverse development of the gonadotrophic cells which take on the appearance of resting cells similar to those found in immature animals, where the two cell types are also identical. Thus, only one morphological type of gonadotrophic cell can be identified in Ellobius lutescens. Moreover, the gonadotrophic cells of the hypogonadic adult male have the same appearnance as those of the female two months after castration, whic proves that the negative feedback mechanism which regulates gonadtrophic function is defective in adult male Ellobius lutescens.

Animals↗

PubMed1976

Hair.

The psychologic importance of hair to man is in inverse ratio to its physical function. Except for scalp hair and desultory areas of sexual hair, most of man's hair follicles are vestigial. Three problems of hair growth remain to be solved: (1) how the intermittent activity of hair follicles in both animals and man is controlled; (2) how the male hormone alters the hair cycle in human skin; and (3) why larger hairs are produced by testosterone in some areas of the body when in some individuals the hair follicles in the scalp regress. Studies in which skin grafts from rats of different ages were exchanged showed that hair follicles are innately programmed but can be slowly influenced by systemic factors. Steroid hormones, especially estrogens, slow down the moult cycle whereas thyroid hormones accelerate it. What establishes the innate rhythm remains problematical. The fact that plucking out the club hair initiates activity in resting follicles has been explained by the hypothesis that the mitotic inhibitor which accumulates during anagen is normally used up or dispersed during telogen or by wounding. However, contrary to this theory, follicular activity is not prolonged by epilation during anagen. Moreover, if rats are epilated within one or two days of eruption, only club hairs are removed since forceps cannot grasp the tips of the new hairs. Such epilation does not affect the anagen in progress, but remarkedly enough the subsequent resting phase is shortened. Both sexual hair and male-pattern baldness depend on androgenic hormones. Target organs of testosterone convert the hormone to active metabolites, chiefly 5alpha-dihydrotestosterone. In skin, however, 5alpha-dihydrotestosterone may not be the only active tissue androgen. The major metabolite of testosterone incubated with hair roots in androstenedione, and hirsute women without other obvious endocrine abnormality sometimes excrete high levels of androstanediol. Both steroids stimulated the sebaceous glands of hypophysectomized-castrated rats, which, however, showed only a limited response to testosterone. The androgenic steroids, the enzymes that convert them to their active metabolites, and the proteins that bind them are undoubtedly very important to the problems of the growth of sexual hair and male-pattern baldness.

Alopecia↗

PubMed1979

Evidence for the involvement of lutropin-independent RNA synthesis in Leydig cell steroidogenesis.

The effect of incubating purified Leydig cells in Eagle's medium and the subsequent effect of the RNA synthesis inhibitors, actinomycin D and cordycepin, on lutropin-stimulated testosterone synthesis have been investigated. The inhibiting effect was found to be inversely related to the time of preincubation; with cells preincubated for 0, 1, 2 and 3 h with Eagle's medium only, followed by 2-h incubation with lutropin with and without actinomycin D, testosterone synthesis was inhibited by 37 +/- 4, 31 +/- 3, 18 +/- 4 and 14 +/- 3% respectively (means +/- s.e.m., n = 5). In cells that had been preincubated for 3 h there was no significant effect of actinomycin D on testosterone synthesis during the first hour of incubation with lutropin. Thereafter the inhibition increased with time reaching a maximum of 30% after 5 h. The effects of preincubation were not due to endogenous lutropin in the Leydig cells because cells isolated from hypophysectomized rats gave similar results. The inhibition of [3H]uridine incorporation into the Leydig cell RNA was 80 +/- 1% with 8 microgram/ml actinomycin D. Increasing the concentration of this inhibitor to 80 microgram/ml did not significantly increase the inhibition of [3H]uridine incorporation or lutropin-stimulated steroidogenesis in preincubated and non-preincubated cells. With cordycepin the inhibition of both RNA synthesis and lutropin-stimulated testosterone synthesis in non-preincubated cells were the same; with 25.1--251 microgram/ml approx. 30--70% resp. With preincubated cells (3 h), 0--50% inhibition of testosterone synthesis was obtained respectively. The inhibitory effect of actinomycin D oimilar to that obtained with lutropin. These observations suggest that during preincubation and independently of lutropin, synthesis of intermediates, including RNAs required for stimulation of steroidogenesis, takes place and that subsequent stimulation of steroidogenesis by lutropin occurs without further de novo RNA synthesis. These results provide evidence for a permissive role of specific RNA and protein synthesis in the action of lutropin on testosterone synthesis in the Leydig cell.

Animals↗