Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 21
Filter
1.
J Neurosci ; 19(22): 10176-83, 1999 Nov 15.
Article in English | MEDLINE | ID: mdl-10559425

ABSTRACT

The suprachiasmatic nucleus (SCN) is a mammalian central circadian pacemaker. This nucleus develops in the last stage of fetal life and matures to make strong synaptic connections within 2 weeks of postnatal life to establish strong oscillation characteristics. To identify factors that initiate the circadian oscillation, we applied a differential display PCR method to developing SCN, and isolated a gene with seven zinc-finger motifs, Lot1, which encodes a gene that appeared at a very high level in the SCN during the early postnatal days. Lot1 mRNA first appeared at postnatal day 1 (P1) at a very high level, and the signal in the SCN continued to be very high until P10 and thereafter rapidly decreased until P20 and was expressed at a very faint level during adulthood. Lot1 mRNA expression was observed only in neurons of the dorsomedial SCN throughout the course of development. During the developmental stage, Lot1 mRNA expression shows a circadian rhythm with a peak in the day time and a trough at night time in both light-dark and constant dark conditions. These observations imply that Lot1 is the first identified putative transcription factor expressed only in the period of active synaptogenesis in the SCN, where Lot1 might play a role in establishing autonomous oscillation.


Subject(s)
Aging/physiology , Embryonic and Fetal Development , Gene Expression Regulation, Developmental , Suprachiasmatic Nucleus/physiology , Transcription Factors/genetics , Amino Acid Sequence , Animals , Antisense Elements (Genetics) , Circadian Rhythm , Molecular Sequence Data , Oscillometry , Polymerase Chain Reaction , RNA, Messenger/genetics , Rats , Rats, Wistar , Suprachiasmatic Nucleus/embryology , Suprachiasmatic Nucleus/growth & development , Transcription Factors/chemistry , Transcription, Genetic , Zinc Fingers
2.
Brain Res Mol Brain Res ; 48(1): 159-63, 1997 Aug.
Article in English | MEDLINE | ID: mdl-9379838

ABSTRACT

The suprachiasmatic nucleus (SCN), a circadian oscillator, contains various peptides arranged in the compartment-specific manner. Somatostatin (SS) and substance P (SP), a peptide derived from preprotachykinin A (PPT-A), are expressed in neurons in the intermediate zone, a narrow area between the major dorsomedial and ventrolateral subdivisions. In the present study, we examined the possibility of co-localization of SS and SP in the SCN by a double-labeling in situ hybridization method using 35S-labeled and digoxigenin-labeled cRNA probes. In the SCN, most of preprosomatostatin (PPSS) mRNA-containing neurons expressed PPT-A mRNA (86%) and, in turn, almost all preprotachykinin A (PPT-A) mRNA-expressing neurons expressed PPSS mRNA signals (97%). Both PPSS and PPT-A mRNAs were also detected in the cerebral cortex and the caudate-putamen, however, their co-existence was extremely rare (< 4%) in these regions. Since the pharmacological effects of SS and SP are similar to that of the light pulses exposed on animals under constant darkness, the co-release of peptides might be an important process for entraining the circadian clock in the SCN.


Subject(s)
Neurons/metabolism , Protein Precursors/biosynthesis , RNA, Messenger/analysis , Somatostatin/biosynthesis , Suprachiasmatic Nucleus/metabolism , Tachykinins/biosynthesis , Transcription, Genetic , Animals , Caudate Nucleus/metabolism , Cerebral Cortex/metabolism , In Situ Hybridization , Male , Neurons/cytology , Organ Specificity , Putamen/metabolism , Rats , Rats, Wistar , Substance P/biosynthesis , Suprachiasmatic Nucleus/cytology
3.
FEMS Microbiol Lett ; 108(2): 243-5, 1993 Apr 01.
Article in English | MEDLINE | ID: mdl-8486249

ABSTRACT

The ubiquinone (coenzyme Q) systems of eleven strains of Coccidioides immitis were determined by high performance liquid chromatography (HPLC). The ubiquinone profile of the fungi was shown to be homogeneous: in all of the strains, ubiquinone-10 (Q-10) was demonstrated to be the major component, with Q-9 as a minor component. The results imply that the ubiquinone system may serve as an additional phenotypic criterion for identifying the fungus.


Subject(s)
Coccidioides/chemistry , Coccidioides/classification , Ubiquinone/chemistry , Coccidioidomycosis/microbiology , Humans
4.
FEMS Immunol Med Microbiol ; 16(1): 39-43, 1996 Nov.
Article in English | MEDLINE | ID: mdl-8954351

ABSTRACT

The ubiquinone (coenzyme Q) systems of 14 species of Cladosporium were determined. The genus was divided into two groups based on the distribution of the major ubiquinones, Q-10 and Q-10(H2). The group containing Q-10 consisted of six species, four of which were human pathogens, whereas the group containing Q-10(H2) consisted of eight plant pathogenic and/or saprophytic species. The results presented here agree with phylogenetic and physiological studies which have shown that the human-pathogenic species of Cladosporium represent a homogeneous, cohesive group.


Subject(s)
Cladosporium/chemistry , Cladosporium/classification , Ubiquinone/analysis , Ubiquinone/classification , Phylogeny
5.
Brain Res Dev Brain Res ; 127(1): 81-6, 2001 Mar 29.
Article in English | MEDLINE | ID: mdl-11287068

ABSTRACT

The suprachiasmatic nucleus (SCN), a central circadian oscillator of mammals, contains various peptides arranged in the compartment specific manner. In the present study, we examined a distinct population of neurons in the central part of the SCN. In situ hybridization histochemistry has demonstrated that these neurons coexpressed both preprosomatostatin (PPSS) and preprotachykinin A (PPT-A) mRNAs, but the developmental expression profiles were different among two. PPSS mRNA first appeared in the SCN at postnatal day 1(P1). The intensity and number of PPSS mRNA signals increased and peaked at P7-P14 and gradually decreased as to adult age (P56). However, PPT-A mRNA-positive appeared late at P7, and gradually increased up to P56. These findings suggest that neurons encoding both the PPSS and PPTA genes first express PPSS and then express PPT-A at a later stage of maturation.


Subject(s)
Gene Expression Regulation, Developmental , Protein Precursors/genetics , Somatostatin/genetics , Suprachiasmatic Nucleus/embryology , Suprachiasmatic Nucleus/physiology , Tachykinins/genetics , Animals , Circadian Rhythm/physiology , Female , In Situ Hybridization , Pregnancy , RNA, Messenger/analysis , Rats , Rats, Wistar
6.
Neurosci Lett ; 222(2): 99-102, 1997 Jan 31.
Article in English | MEDLINE | ID: mdl-9111738

ABSTRACT

Age-related decreases in circadian oscillating activity are speculated to be one of the causes of psychiatric symptoms. To explore the effects of aging on vasoactive intestinal peptide (VIP) synthesis in the suprachiasmatic nucleus (SCN), we investigated the changes in VIP mRNA levels in aged rats compared with young-adult rats under a light/dark cycle using in situ hybridization combined with microcomputer-based imaging analysis. In the young-adult rats, total signals of VIP mRNA in the light-phase showed a significant decrease compared with those on the dark-phase. The VIP signal level in the aged rats was markedly lower than that in young-adults in both light and dark phases. Moreover, in the aged rats, there were no significant differences in VIP mRNA level between the light and dark phases. These results suggest that gene expression of VIP neurons, a main component of the circadian oscillating system, becomes disturbed in the aged rat brain.


Subject(s)
Aging/physiology , Circadian Rhythm/physiology , Suprachiasmatic Nucleus/physiology , Vasoactive Intestinal Peptide/genetics , Animals , Darkness , Gene Expression Regulation/physiology , In Situ Hybridization , Lighting , Male , RNA, Messenger/metabolism , Rats , Rats, Wistar , Suprachiasmatic Nucleus/chemistry
8.
Appl Microbiol ; 20(3): 452-4, 1970 Sep.
Article in English | MEDLINE | ID: mdl-5485726

ABSTRACT

A simple thin-layer chromatography-fluorodensitometric method for quantitative analysis of ochratoxin A was developed. This method proved to be of use in investigating the production of the toxin and the nutritional factors affecting the toxin production by two strains of Aspergillus ochraceus isolated from moldy rice in Japan. These fungi produced large amounts of ochratoxin A in a nutrient solution containing 1% l-phenylalanine and 2% yeast extract.


Subject(s)
Aspergillus/metabolism , Mycotoxins/metabolism , Oryza , Aspergillus/drug effects , Chromatography, Thin Layer , Densitometry , Fluorometry , Japan , Phenylalanine/pharmacology
9.
Appl Environ Microbiol ; 48(5): 1001-3, 1984 Nov.
Article in English | MEDLINE | ID: mdl-6508300

ABSTRACT

The inhibitory effects of sterigmatocystin, O-methylsterigmatocystin, and 5,6-dimethoxysterigmatocystin on the ATP synthesis system in mitochondria were compared with that of aflatoxin B1, which disturbs the respiratory chain in mitochondria. Sterigmatocystin and 5,6-dimethoxysterigmatocystin were found to uncouple the oxidative phosphorylation process without causing depression of state 3 respiration. O-Methylsterigmatocystin did not exhibit uncoupling activity at the limited concentrations tested (due to its low solubility in an aqueous system). These compounds, as well as aflatoxin B1, elicited neither pseudo-energized nor energized swelling of mitochondria and did not inhibit Ca2+-induced swelling of mitochondria.


Subject(s)
Adenosine Triphosphate/biosynthesis , Mitochondria, Liver/metabolism , Mycotoxins/pharmacology , Sterigmatocystin/pharmacology , Xanthenes/pharmacology , Animals , Calcium/pharmacology , In Vitro Techniques , Mitochondria, Liver/drug effects , Oxidative Phosphorylation/drug effects , Rats , Sterigmatocystin/analogs & derivatives
10.
Appl Environ Microbiol ; 47(3): 481-3, 1984 Mar.
Article in English | MEDLINE | ID: mdl-6712217

ABSTRACT

Averufin and averufin dimethylether from Aspergillus versicolor were examined for their uncoupling effects on oxidative phosphorylation in isolated rat liver mitochondria to get insight into the mode of toxic action of averufin. Averufin uncoupled oxidative phosphorylation, causing 50% uncoupling at about 1.5 microM with respect to the decrease in P/O ratio. Averufin dimethylether did not uncouple but inhibited state 3 respiration of mitochondria, which was not released by either 2,4-dinitrophenol or averufin.


Subject(s)
Anthraquinones/pharmacology , Mitochondria, Liver/drug effects , Uncoupling Agents/pharmacology , Animals , Mitochondria, Liver/metabolism , Oxidative Phosphorylation/drug effects , Rats
11.
Appl Environ Microbiol ; 46(4): 793-6, 1983 Oct.
Article in English | MEDLINE | ID: mdl-6227285

ABSTRACT

The in vitro biological activity of secalonic acid D, a mycotoxin from Aspergillus ochraceus, was studied to assess its cytotoxicity for isolated rat liver mitochondria. Secalonic acid D uncoupled the oxidative phosphorylation of mitochondria and caused a mild inhibition of state 3 respiration. Secalonic acid D weakly enhanced latent ATPase activity in mitochondria but suppressed 2,4-dinitrophenol-stimulated ATPase activity. Secalonic acid D did not induce pseudoenergized swelling of mitochondria and markedly inhibited the Ca2+-induced swelling of mitochondria in KCl isotonic solution.


Subject(s)
Mitochondria, Liver/drug effects , Xanthenes/toxicity , Xanthones , Adenosine Triphosphatases/antagonists & inhibitors , Animals , Calcium/pharmacology , In Vitro Techniques , Mitochondria, Liver/metabolism , Mitochondrial Swelling/drug effects , Oxidative Phosphorylation/drug effects , Rats
12.
Genes Cells ; 3(3): 167-76, 1998 Mar.
Article in English | MEDLINE | ID: mdl-9619629

ABSTRACT

BACKGROUND: In mammals, two possible clock genes (Clock, Per1) have very recently been reported. mPer1 (the first identified mouse period gene), in particular, shows a circadian expression in suprachiasmatic nuclei (SCN), the mammalian circadian centre. However, only mPer1 and Clock as clock components may not be sufficient to understand all the events in circadian oscillation and entrainment. RESULTS: A mammalian period complementary DNA, mPer2, has been isolated from the mouse brain. The amino acid sequence of mPer2 is similar to mPer1 and Drosophila Period (dPer), indicating that mPer2 is a member of the family which contains mPer1, itself a homologue of dPer. mPer2 mRNA is predominantly expressed in SCN. A robust circadian rhythmic expression in the SCN supports the view that mPer2 is a clock gene. mPer2 is strongly expressed at the subjective afternoon in constant darkness, distinct from a morning-phase clock mPer1. Our precise quantitative in situ hybridizations have revealed that the peak expression of mPer2 transcripts is delayed by 8 h in LD (light-dark) or 4 h in DD (dark-dark) conditions when compared to mPer1. A short brief light exposure at the early subjective night, prompting a phase-shift in locomotor rhythms, induces a transient increase of mPer2 transcripts with delayed onset, as compared to mPer1 mRNA induction. Furthermore, mPer2 is co-expressed with mPer1 in single SCN cells. CONCLUSIONS: Mammalian period genes show molecular heterogeneity, each of which is composed of a different oscillator, and may serve to establish stable circadian rhythms in mammalian oscillating cells.


Subject(s)
Circadian Rhythm/genetics , Gene Expression Regulation , Nuclear Proteins/genetics , Suprachiasmatic Nucleus/metabolism , Amino Acid Sequence , Animals , Cell Cycle Proteins , Cloning, Molecular , Humans , Male , Mice , Mice, Inbred BALB C , Molecular Sequence Data , Multigene Family , Neurons/metabolism , Nuclear Proteins/biosynthesis , Nuclear Proteins/metabolism , Period Circadian Proteins , RNA, Messenger/biosynthesis , Transcription Factors , Transcription, Genetic
13.
EMBO J ; 17(16): 4753-9, 1998 Aug 17.
Article in English | MEDLINE | ID: mdl-9707434

ABSTRACT

A new member of the mammalian period gene family, mPer3, was isolated and its expression pattern characterized in the mouse brain. Like mPer1, mPer2 and Drosophila period, mPer3 has a dimerization PAS domain and a cytoplasmic localization domain. mPer3 transcripts showed a clear circadian rhythm in the suprachiasmatic nucleus (SCN). Expression of mPer3 was not induced by exposure to light at any phase of the clock, distinguishing this gene from mPer1 and mPer2. Cycling expression of mPer3 was also found outside the SCN in the organum vasculosum lamina terminalis (OVLT), a potentially key region regulating rhythmic gonadotropin production and pyrogen-induced febrile phenomena. Thus, mPer3 may contribute to pacemaker functions both inside and outside the SCN.


Subject(s)
Circadian Rhythm , Diencephalon/metabolism , Light , Nuclear Proteins/genetics , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , DNA, Complementary , Male , Mice , Mice, Inbred BALB C , Molecular Sequence Data , Period Circadian Proteins , RNA, Messenger/genetics , Sequence Homology, Amino Acid , Transcription Factors
SELECTION OF CITATIONS
SEARCH DETAIL