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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoamine oxidase (MAO) activity was studied in whole brain, hypothalamus, adrenals and liver of developing rats subjected to disturbed feeding patterns or undernutrition for 3 weeks. The rats were divided into six groups: (1) normally fed controls; (2) rats starved for 24 h, fed for the following 8 h and killed after the last starvation period (PAS); (3) same treatment as in (2) but killed after the last feeding period (PAF); (4) rats starved for 16 h, fed for the following 8 h at a constant schedule, and killed after the last starvation period (PS); (5) same treatment as in (4) but killed after the last feeding period (PF), and (6) undernourished (U). Alteration of the feeding time resulted in significant decreases of MAO activity in the brain and the adrenal gland whereas the hypothalamus and the liver showed a slight increase in activity in the PAS group. In PS rats, MAO activity increased in the brain, adrenals and hypothalamus; in PF rats, the effects of the treatment were inverse. Both in the PS and PF rats, hepatic MAO activity was strongly decreased when assayed with kynuramine. In U rats, hepatic MAO activity was highly increased when assayed with kynuramine but the other tissues responded differently. The adrenaline and noradrenaline stocks of the adrenal gland were markedly increased in all the treated groups; the maximum increase in noradrenaline was observed in the PS rats. The results suggest that any disturbance in the feeding pattern affects the MAO activity in the central and peripheral regions of the young rat during postnatal development. The developing rat seems to get accustomed to new alimentary rhythms, and normal monoaminergic function is rapidly restored when the rat is given a compensatory diet. Increased adrenal catecholamines after a disturbance in the feeding patterns seem to be a response to stress.
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PMID:Maintenance of central and peripheral monoamine oxidase activity in developing rats subjected to disturbed alimentary rhythms and undernutrition. 47 1

The histology and ultrastructure of the rat gastric mucosa were investigated during 168 hours of starvation. An increased desquamation of individual foveolar cells was found. In the preserved cells of the foveolae, the content of the PAS positive mucosubstances did not change during starvation, and no changes took place in the appearance and in the amount of the mucous granules at the electron microscopic investigation. The number of lipid droplets increased in the mucous foveolar cells within 24 and 48 hours. During starvation the mitochondria (mainly in the parietal cells) were enlarged and contained rare mitochondrial cristae. Some mitochondria were distintegrated and removed by lysosomes. The number of lysosomes (mainly cytosergresomes) was markedly increased n parietal cells. A collapse of the intracellular canaliculi occurred as well as a narrowing in the tubulovesicular profiles. In chief cells the profiles of the granular endoplasmic reticulum and Golgi apparatus were reduced. It was shown that the ultrastructural changes induced by starvation can be interpreted functionally in changed histochemical parameters of the gastric mucosa.
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PMID:Influence of starving on the rat gastric mucosa -- light and electron microscopical findings. 59 Apr 16

Electron-microscopic, histochemical and endocrinologic study of aldehyde-fuchsin-positive (Gomori-positive; GP) grains of rat brain periventricular glia (GP glia) was carried out. GP structures appear as a population of osmiophilic particles, which is heterogeneous in both shape and size. Laminar structures interspersed with fine granular material were seen in the GP granules. No activity of the lysosomal and mitochondrial enzymes could be observed. The reaction for peroxidase was also negative. The GP material was stained with PAS and Ziehl-Nielsen. There are apparently no lipoid inclusions in the GP grains. The primary red-orange fluorescence distinguishes the GP glia from other structures in the rat brain. So GP grains are a specific cytoplasmic formation having some similarity to lipofuscin. There was a considerable decrease in GP grains after administration of estradiol in ovariectomized rats and also in pregnant rats. Dopamine administration and starvation caused some reduction in GP grains. In the rat hypothalamus, distribution of the main mass of GP glia corresponds with the so-called hypophysiotropic area. The possible participation of GP glia in the neuroendocrinological process is discussed.
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PMID:Studies on the structure and function of Gomori-positive glial cells in the rat hypothalamus. 97 91

To study the physiological role of skeletal muscle glycogen in starved animals, effects of starvation on glycogen and glycogen phosphorylase (EC 2.4.1.1.) activity were studied in muscle fibers (morphologic study) and in whole muscles (biochemical study) of the rectus femoris muscle of mouse. Glycogen content in the liver of the starved animals was also measured. PAS reaction, strong in muscle fibers of fed animals, became weak predominantly in type IIB fibers after 2 days and almost disappeared after 4 days of starvation. Glycogen particles, numerous in the sarcoplasm between myofibrils of muscle fibers, decreased markedly predominantly in type IIB fibers after 2 days and almost disappeared after 4 days. Phosphorylase a activity, undetected in fibers of fed mice, appeared weak in type IIB fibers and very weak in type IIA fibers after 2 days and became moderate in type IIB fibers and weak in type IIA fibers after 4 days. Muscle glycogen content did not differ by 16 hours from the values of corresponding fed animals. However, liver glycogen content had already decreased after 8 hours and markedly so after 12 hours. The results support our hypothesis-"skeletal muscle glycogen is used for maintaining the blood glucose level in starved mice" (Hirose et al.: Anat. Rec., 216:133-138, 1986)-and show that type IIB fibers play a main role in maintaining the glucose level and that muscle glycogen is utilized after depletion of liver glycogen.
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PMID:Physiological role of skeletal muscle glycogen in starved mice. 363 41

Growth-limiting stresses in bacteria induce the general stress response to protect the cells against future stresses. Energy stress caused by starvation conditions in Bacillus subtilis is transmitted to the sigma(B) transcription factor by stress-response regulators. RsbP, a positive regulator, is a phosphatase containing a PAS (Per-ARNT-Sim) domain and requires catalytic function of a putative alpha/beta hydrolase, RsbQ, to be activated. These two proteins have been found to interact with each other. We determined the crystal structures of RsbQ in native and inhibitor-bound forms to investigate why RsbP requires RsbQ. These structures confirm that RsbQ belongs to the alpha/beta hydrolase superfamily. Since the catalytic triad is buried inside the molecule due to the closed conformation, the active site is constructed as a hydrophobic cavity that is nearly isolated from the solvent. This suggests that RsbQ has specificity for a hydrophobic small compound rather than a macromolecule such as RsbP. Moreover, structural comparison with other alpha/beta hydrolases demonstrates that a unique loop region of RsbQ is a likely candidate for the interaction site with RsbP, and the interaction might be responsible for product release by operating the hydrophobic gate equipped between the cavity and the solvent. Our results support the possibility that RsbQ provides a cofactor molecule for the mature functionality of RsbP.
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PMID:Crystal structures of RsbQ, a stress-response regulator in Bacillus subtilis. 1563 89

Autophagy is a catabolic multitask transport route that takes place in all eukaryotic cells. During starvation, cytoplasmic components are randomly sequestered into huge double-membrane vesicles called autophagosomes and delivered into the lysosome/vacuole where they are destroyed. Cells are able to modulate autophagy in response to their needs, and under certain circumstances, cargoes such as aberrant protein aggregates, organelles and bacteria can be selectively and exclusively incorporated into autophagosomes. In the yeast Saccharomyces cerevisiae, for example, double-membrane vesicles are used to transport the Ape1 protease into the vacuole, or for the elimination of superfluous peroxisomes. In the present study we reveal that in this organism, actin plays a role in these two types of selective autophagy but not in the nonselective, bulk process. In particular, we show that precursor Ape1 is not correctly recruited to the PAS, the putative site of double-membrane vesicle biogenesis, and superfluous peroxisomes are not degraded in a conditional actin mutant. These phenomena correlate with a defect in Atg9 trafficking from the mitochondria to the PAS.
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PMID:The actin cytoskeleton is required for selective types of autophagy, but not nonspecific autophagy, in the yeast Saccharomyces cerevisiae. 1622 87

The general stress regulon of Bacillus subtilis is induced by activation of the sigma(B) transcription factor. sigma(B) activation occurs when one of two phosphatases responds to physical or nutritional stress to activate a positive sigma(B) regulator by dephosphorylation. The signal that triggers the nutritional stress phosphatase (RsbP) is unknown; however, RsbP activation occurs under culture conditions (glucose/phosphate starvation, azide or decoyinine treatment) that reduce the cell's levels of ATP and/or GTP. Variances in nucleotide levels in these instances may be coincidental rather than causal. RsbP carries a domain (PAS) that in some regulatory systems can respond directly to changes in electron transport, proton motive force, or redox potential, changes that typically precede shifts in high-energy nucleotide levels. The current work uses Bacillus subtilis with mutations in the oxidative phosphorylation and purine nucleotide biosynthetic pathways in conjunction with metabolic inhibitors to better define the inducing signal for RsbP activation. The data argue that a drop in ATP, rather than changes in GTP, proton motive force, or redox state, is the key to triggering sigma(B) activation.
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PMID:Contributions of ATP, GTP, and redox state to nutritional stress activation of the Bacillus subtilis sigmaB transcription factor. 1626 79

The Tor kinases regulate responses to nutrients and control cell growth. Unlike most organisms that only contain one Tor protein, Saccharomyces cerevisiae expresses two, Tor1 and Tor2, which are thought to share all of the rapamycin-sensitive functions attributable to Tor signaling. Here we conducted a genetic screen that defined the global TOR1 synthetic fitness or lethal interaction gene network. This screen identified mutations in distinctive functional categories that impaired vacuolar function, including components of the EGO/Gse and PAS complexes that reduce fitness. In addition, tor1 is lethal in combination with mutations in class C Vps complex components. We find that Tor1 does not regulate the known function of the class C Vps complex in protein sorting. Instead class C vps mutants fail to recover from rapamycin-induced growth arrest or to survive nitrogen starvation and have low levels of amino acids. Remarkably, addition of glutamate or glutamine restores viability to a tor1 pep3 mutant strain. We conclude that Tor1 is more effective than Tor2 at providing rapamycin-sensitive Tor signaling under conditions of amino acid limitation, and that an intact class C Vps complex is required to mediate intracellular amino acid homeostasis for efficient Tor signaling.
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PMID:Efficient Tor signaling requires a functional class C Vps protein complex in Saccharomyces cerevisiae. 1756 46

Sensor histidine kinases are widely used by bacteria to detect and respond to environmental signals. In Bacillus subtilis, KinA is a major kinase providing phosphate input to the phosphorelay that activates the sporulation pathway upon starvation via the phosphorylated Spo0A transcription factor. KinA contains three PAS domains in its amino-terminal sensor domain, which appear to be involved in the sensing of an unidentified sporulation signal(s) produced upon starvation. Prior biochemical studies have suggested that KinA forms a homodimer as a functional enzyme and that the most amino-terminal PAS domain (PAS-A) plays an important role in sensing the signal(s) to activate an ATP-dependent autophosphorylation reaction to a histidine residue. To analyze the structure and function of the kinase in vivo, we have used a strain in which the synthesis of KinA is under the control of an isopropyl-beta-d-thiogalactopyranoside (IPTG)-inducible promoter. In vivo functional studies in combination with domain-based deletion analysis show that the cytosolic KinA forms a homo-oligomer as an active form under both nutrient-rich and nutrient-depleted conditions via its amino- and carboxyl-terminal domains independently. Furthermore, we found that a mutant in which the PAS-A domain was deleted was still able to induce sporulation at a wild-type level irrespective of nutrient availability, suggesting that PAS-BC domains are sufficient to maintain the kinase activity. Based on these results, we propose that the primary role of the amino-terminal sensor domain is to form a stable complex as a functional kinase, but possibly not for the binding of an unidentified sporulation signal(s).
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PMID:In vivo domain-based functional analysis of the major sporulation sensor kinase, KinA, in Bacillus subtilis. 1956 Nov 31

The sigma(B)-dependent general stress response in the common soil bacterium Bacillus subtilis can be elicited by a range of stress factors, such as starvation or an ethanol, salt, or heat shock, via a complex upstream signaling cascade. Additionally, sigma(B) can be activated by blue light via the phototropin homologue YtvA, a component of the environmental branch of the signaling cascade. Here we use a reporter-gene fusion to show that sigma(B) can also be activated by red light via the energy branch of its upstream signaling cascade. Deletion mutagenesis and homologous overproduction experiments indicate that the RsbP protein (composed of an N-terminal Per-ARNT-Sim [PAS] domain and a C-terminal PP2C-type phosphatase domain) is involved in the red light response. This second light input pathway functions complementarily to YtvA; it shows broader spectral sensitivity but requires higher light intensities. These results are confirmed by transcriptome analyses, which show that both light effects result in upregulation of the sigma(B) regulon, with minimal activation of other responses.
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PMID:Red light activates the sigmaB-mediated general stress response of Bacillus subtilis via the energy branch of the upstream signaling cascade. 1994 97


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