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101.
102.
103.
Metabotrophic glutamate receptors (mGluRs) modulate cellular activities involved in the processes of differentiation and degeneration.
In this study, we have analysed the expression pattern of group-I metabotropic glutamate receptor (mGlu-5) in cerebral cortex,
corpus striatum, brainstem and hippocampus of streptozotocin induced and insulin treated diabetic rats (D+I) as a function
of age. Also, the functional role of glutamate receptors in intra cellular calcium release from the pancreatic islets was
studied in vitro. The gene expression studies showed that mGlu-5 mRNA in the cerebral cortex increased siginficantly in 7 weeks old diabetic
rats whereas decreased expression was observed in brainstem, corpus striatum and hippocampus when compared to control. 90
weeks old diabetic rats showed decreased expression in cerebral cortex, corpus striatum and hippocampus whereas in brainstem
the expression increased significantly compared to their respective controls. In 7 weeks old D+I group, mGlu-5 mRNA expression
was significantly decreased in cerebral cortex and corpus striatum whereas the expression increased significantly in brainstem
and hippocampus. 90 weeks old D+I group showed an increased expression in cerebral cortex, while it was decreased significantly
in corpus striatum, brainstem and hippocampus compared to their respective controls. In vitro studies showed that glutamate at lower concentration (10-7 M) stimulated calcium release from the pancreatic islets. Our results suggest that mGlu-5 receptors have differential expression
in brain regions of diabetes and D+I groups as a function of age. This will have clinical significance in management of degeneration
in brain function and memory enhancement through glutamate receptors. Also, the regulatory role of glutamate receptors in
calcium release has immense therapeutic application in insulin secretion and function. 相似文献
104.
Background
Cancer of the oral tongue is the second most common cancer among males in various parts of India. Despite advances in diagnosis and treatment the failure rates in cancer of the oral tongue are high and survival poor. Majority of these failures occur in untreated neck. 相似文献105.
To identify and study genes essential for vertebrate retinal development, we are screening zebrafish embryos for mutations that disrupt retinal histogenesis. Key steps in retinogenesis include withdrawal from mitosis by multipotent neuroepithelial cells, specification to particular cell types, migration to the appropriate laminar positions, and molecular and morphological differentiation. In this study, we have identified two recessive mutations that affect the transition of proliferating neuroepithelial cells to postmitotic retinal cells. Both the perplexed and confused mutant phenotypes were initially detectable when the first retinal neuroepithelial cells began to leave the cell cycle. At this time, each mutant retina showed increased cell death and a lack of morphological differentiation. Cell death was found to be apoptotic in both perplexed and confused retinas based on TUNEL analysis and activation of caspase-3. TUNEL-phosphoRb-BrdU colocalization studies indicated that the perplexed mutation caused death in cells transitioning from a proliferative to postmitotic state. For the confused mutation, TUNEL-phosphoRb-BrdU analysis revealed that only a subset of postmitotic cells were induced to activate apoptosis. Mosaic analysis demonstrated that within the retina the perplexed mutation functions noncell-autonomously. Furthermore, whole lens or eye cup transplantations indicated that the retinal defect was intrinsic to the retina. Mosaic analysis with confused embryos showed this mutation acts cell-autonomously. From these studies, we conclude that the perplexed and confused genes are essential at distinct stages during the transition from proliferating to postmitotic cells within the zebrafish retina. 相似文献
106.
Lim JY Shin CS Chung EJ Kim JS Kim HU Oh SJ Choi WB Ryou CS Kim JB Kwon MS Chung TY Song SI Kim JK Nahm BH Hwang YS Eun MY Lee JS Cheong JJ Choi YD 《Molecules and cells》2000,10(4):399-404
Non-redundant expressed sequence tags (ESTs) were generated from six different organs at various developmental stages of Chinese cabbage, Brassica rapa L. ssp. pekinensis. Of the 1,295 ESTs, 915 (71%) showed significantly high homology in nucleotide or deduced amino acid sequences with other sequences deposited in databases, while 380 did not show similarity to any sequences. Briefly, 598 ESTs matched with proteins of identified biological function, 177 with hypothetical proteins or non-annotated Arabidopsis genome sequences, and 140 with other ESTs. About 82% of the top-scored matching sequences were from Arabidopsis or Brassica, but overall 558 (43%) ESTs matched with Arabidopsis ESTs at the nucleotide sequence level. This observation strongly supports the idea that gene-expression profiles of Chinese cabbage differ from that of Arabidopsis, despite their genome structures being similar to each other. Moreover, sequence analyses of 21 Brassica ESTs revealed that their primary structure is different from those of corresponding annotated sequences of Arabidopsis genes. Our data suggest that direct prediction of Brassica gene expression pattern based on the information from Arabidopsis genome research has some limitations. Thus, information obtained from the Brassica EST study is useful not only for understanding of unique developmental processes of the plant, but also for the study of Arabidopsis genome structure. 相似文献
107.
108.
Tonic GABAergic inhibition of taste-responsive neurons in the nucleus of the solitary tract 总被引:4,自引:1,他引:3
The effects of gamma-aminobutyric acid (GABA) and the GABAA receptor
antagonist bicuculline methiodide (BICM) on the activity of taste-
responsive neurons in the nucleus of the solitary tract (NST) were examined
electrophysiologically in urethane-anesthetized hamsters. Single neurons in
the NST were recorded extracellularly and drugs (21 nl) were microinjected
into the vicinity of the cell via a multibarrel pipette. The response of
each cell was recorded to lingual stimulation with 0.032 M NaCl, 0.032 M
sucrose, 0.0032 M citric acid and 0.032 M quinine hydrochloride (QHCl).
Forty-six neurons were tested for the effects of GABA; the activity of 29
cells (63%) was inhibited by 5 mM GABA. Whether activity was elicited in
these cells by repetitive anodal current stimulation (25 microA, 0.5 s, 0.1
Hz) of the tongue (n = 13 cells) or the cells were spontaneously active (n
= 13 cells), GABA produced a dose-dependent (1, 2 and 5 mM) decrement in
activity. Forty- seven NST neurons were tested for the effects of BICM on
their responses to chemical stimulation of the tongue; the responses of 28
cells (60%) were enhanced by 10 mM BICM. The gustatory responses of 26 of
these cells were tested with three concentrations (0.2, 2 and 10 mM) of
BICM, which produced a dose-dependent increase in both spontaneous activity
and taste-evoked responses. Nine of these neurons were sucrose- best, seven
were NaCl-best, eight were acid-best and two responded best to QHCl. The
responses to all four tastants were enhanced, with no difference among
neuron types. For 18 cells that were tested with two or more gustatory
stimuli, BICM increased their breadth of responsiveness to their two most
effective stimuli. These data show that approximately 60% of the
taste-responsive neurons in the rostral NST are inhibited by GABA and/or
subject to a tonic inhibitory influence, which is mediated by GABAA
receptors. The modulation of these cells by GABA provides a mechanism by
which the breadth of tuning of the cell can be sharpened. Modulation of
gustatory activity following a number of physiological changes could be
mediated by such a GABAergic circuit.
相似文献
109.
Molecular evolution of the Sex-Ratio inversion complex in Drosophila pseudoobscura: analysis of the Esterase-5 gene region 总被引:2,自引:0,他引:2
The Sex-Ratio chromosome in Drosophila pseudoobscura is subject to meiotic
drive. It is associated with a series of three nonoverlapping paracentric
inversions on the right arm of the X chromosome. The esterase-5 gene region
has been localized to section 23 within the subbasal inversion of the
Sex-Ratio inversion complex, making esterase- 5 a convenient locus for
molecular evolutionary analyses of the Sex- Ratio inversion complex and the
associated drive system. A 504-bp fragment of noncoding, intergenic DNA
from the esterase-5 gene region was amplified and sequenced from 14
Sex-Ratio and 14 Standard X chromosomes of D. pseudoobscura, and from 9 X
chromosomes of its two sibling species, Drosophila persimilis and
Drosophila miranda. There is extensive sequence differentiation between the
Sex-Ratio and Standard chromosomal types. The common Standard chromosome is
highly polymorphic, while, as expected from either the neutral mutation
theory or the selective sweep hypothesis, the rarer Sex-Ratio chromosome
has much less within-chromosome nucleotide polymorphism. We estimate that
the Standard and Sex-Ratio chromosomes in D. pseudoobscura diverged between
700,000 and 1.3 Mya, or at least 2 million generations ago. The clustering
of D. pseudoobscura Sex-Ratio chromosomes in a neighbor- joining phylogeny
indicates a fairly old, monophyletic origin in this species. It appears
from these data that Sex-Ratio genes were present prior to the divergence
of D. pseudoobscura and D. persimilis and that both the Standard and
Sex-Ratio chromosomes of D. persimilis were derived from the Standard
chromosome of D. pseudoobscura after the inversion events that isolated the
D. pseudoobscura Sex-Ratio chromosome.
相似文献
110.
Although it is now apparent that the intracellular pH may rise considerably above neutrality under physiological conditions, information on the effect of alkaline pH on microtubule assembly and disassembly is still quite fragmentay. We have studied the assembly/disassembly of bovine brain microtubule protein at alkaline pH in vitro. When microtubules are assembled to a new steady state at pH less than 7 and pH is then made more alkaline, they undergo a rapid disassembly to a new steady state. This disassembly is reversed by acidification. The degree of disassembly is determined largely by the pH- dependence of the critical concentration, which increases five to eight times, from pH 7 to 8. A fraction of assembly-incompetent tubulin is identified that increases with pH, but its incompetency is largely reversed with acidification. Measurements of microtubule lengths are used to indicate that disassembly occurs by uniform shortening of microtubules. A comparison of shortening by alkalinization with dilution suggests that the intrinsic rate of disassembly is accelerated by increasing pH. The capacity for initiating assembly is progressively lost with incubation at alkaline pH (although some protection is afforded by sulfhydryl-reducing agents). However, direct assembly from depolymerized mixtures is possible at least up to pH 8.3, and the steady state achieved at these alkaline pH values is stable. Such preparations are readily disassembled by cold and podophyllotoxin (PLN). Disassembly induced by PLN is also markedly enhanced at alkaline pH, suggesting a corresponding enhancement of “treadmilling.” The implications of physiological events leading to alkaline shifts of pH for microtubule assembly/disassembly are discussed, particularly in the light of recent hypotheses regarding treadmilling and its role in controlling the distribution of microtubules in vivo. 相似文献