RESUMO
Gastrin releasing peptide, the mammalian counterpart of the amphibian peptide, bombesin, has been increasingly implicated in regulating normal brain function as well as in the pathogenesis of psychiatric and/or neurodevelopmental disorders. We have previously shown that the neonatal blockade of the gastrin-releasing peptide receptor (GRPr) in rats produces long-lasting consequences during central nervous system development that are commonly observed in neurodevelopmental disorders such as autism spectrum disorders. The present investigation assessed in further detail, long-term behavioral effects of neonatal GRPr blockade. During postnatal days 1-10, male Wistar rat pups (n=5-10/litter) were injected (subcutaneously) with the GRPr antagonist, RC-3095 (1 mg/kg), or a vehicle (control), twice daily. Following the drug treatment regimen, several behaviors were assessed (starting on postnatal day 14) including specific social behaviors (namely, group huddling characteristics, social interaction, and social approach), restrictive/repetitive and stereotyped behaviors (y-maze, repetitive novel object contact task, observation for stereotypies) and anxiety/fear-related responses (open field, elevated plus maze and contextual fear conditioning). Rats treated neonatally with RC-3095 showed reduced sociability, restrictive interests, motor stereotypies and enhanced learned fear response compared to the controls (vehicle-treated rats). These behavioral abnormalities are consistent with those observed in autism spectrum disorders and provide further evidence that neonatal blockade of GRPr could potentially serve as a useful model to gain a better understanding of the underlying neurodevelopmental disruptions contributing to the expression of autism-relevant phenotypes.
Assuntos
Envelhecimento/efeitos dos fármacos , Medo/efeitos dos fármacos , Receptores da Bombesina/antagonistas & inibidores , Comportamento Social , Comportamento Estereotipado/efeitos dos fármacos , Envelhecimento/fisiologia , Animais , Animais Recém-Nascidos , Ansiedade/induzido quimicamente , Ansiedade/fisiopatologia , Peso Corporal/efeitos dos fármacos , Bombesina/análogos & derivados , Bombesina/farmacologia , Fármacos do Sistema Nervoso Central/farmacologia , Transtornos Globais do Desenvolvimento Infantil/fisiopatologia , Comportamento Exploratório/efeitos dos fármacos , Comportamento Exploratório/fisiologia , Medo/fisiologia , Masculino , Fragmentos de Peptídeos/farmacologia , Ratos , Ratos Wistar , Receptores da Bombesina/metabolismo , Comportamento Estereotipado/fisiologia , Fatores de TempoRESUMO
The sequence of a 281-kbp contig from the crenarchaeote Sulfolobus solfataricus P2 was determined and analysed. Notable features in this region include 29 ribosomal protein genes, 12 tRNA genes (four of which contain archaeal-type introns), operons encoding enzymes of histidine biosynthesis, pyrimidine biosynthesis, and arginine biosynthesis, an ATPase operon, numerous genes for enzymes of lipopolysaccharide biosynthesis, and six insertion sequences. The content and organization of this contig are compared with sequences from crenarchaeotes, euryarchaeotes, bacteria, and eukaryotes.
Assuntos
Genes Arqueais , Sulfolobus/genética , Sequência de Aminoácidos , Proteínas Arqueais/genética , Sequência de Bases , Clonagem Molecular , Replicação do DNA , DNA Arqueal/genética , Enzimas/genética , Regulação da Expressão Gênica em Archaea , Genoma Arqueal , Dados de Sequência Molecular , Mutagênese Insercional , Biossíntese de Proteínas , Proteínas Ribossômicas/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Especificidade da EspécieRESUMO
The expression of two heat-responsive cct (chaperonin-containing Tcp-1) genes from the archaeon Haloferax volcanii was investigated at the transcription level. The cct1 and cct2 genes, which encode proteins of 560 and 557 amino acids, respectively, were identified on cosmid clones of an H. volcanii genomic library and subsequently sequenced. The deduced amino acid sequences of these genes exhibited a high degree of similarity to other archaeal and eucaryal cct family members. Expression of the cct genes was characterized in detail for the purpose of developing a model for studying transcription regulation in the domain Archaea. Northern (RNA) analysis demonstrated that the cct mRNAs were maximally induced after heat shock from 37 to 55 degrees C and showed significant heat inducibility after 30 min at 60 degrees C. Transcription of cct mRNAs was also stimulated in response to dilute salt concentrations. Transcriptional analysis of cct promoter regions coupled to a yeast tRNA reporter gene demonstrated that 5' flanking sequences up to position -233 (cct1) and position -170 (cct2) were sufficient for promoting heat-induced transcription. Transcript analysis indicated that both basal transcription and stress-induced transcription of the H. volcanii cct genes were directed by a conserved archaeal consensus TATA motif (5'-TTTATA-3') centered at -25 relative to the mapped initiation site. Comparison of the cct promoter regions also revealed a striking degree of sequence conservation immediately 5' and 3' of the TATA element.
Assuntos
Proteínas Arqueais , Regulação da Expressão Gênica em Archaea , Haloferax/genética , Proteínas de Choque Térmico/genética , Chaperonas Moleculares/genética , Transcrição Gênica , Sequência de Aminoácidos , Sequência de Bases , Chaperonina com TCP-1 , Chaperoninas/química , Chaperoninas/genética , Clonagem Molecular , Sequência Conservada , Genes Arqueais , Genes Reporter , Haloferax/química , Proteínas de Choque Térmico/química , Temperatura Alta , Humanos , Chaperonas Moleculares/química , Dados de Sequência Molecular , Regiões Promotoras Genéticas , TATA BoxRESUMO
Anonymous probes from the genome of Halobacterium salinarium GRB and 12 gene probes were hybridized to the cosmid clones representing the chromosome and plasmids of Halobacterium salinarium GRB and Haloferax volcanii DS2. The order of and pairwise distances between 35 loci uniquely cross-hybridizing to both chromosomes were analyzed in a search for conservation. No conservation between the genomes could be detected at the 15-kbp resolution used in this study. We found distinct sets of low-copy-number repeated sequences in the chromosome and plasmids of Halobacterium salinarium GRB, indicating some degree of partitioning between these replicons. We propose alternative courses for the evolution of the haloarchaeal genome: (i) that the majority of genomic differences that exist between genera came about at the inception of this group or (ii) that the differences have accumulated over the lifetime of the lineage. The strengths and limitations of investigating these models through comparative genomic studies are discussed.
Assuntos
Rearranjo Gênico , Genoma Bacteriano , Halobacteriaceae/genética , Halobacterium/genética , Southern Blotting , Mapeamento Cromossômico , Cromossomos Bacterianos , Sondas de DNA , Sequências Repetitivas de Ácido NucleicoRESUMO
A major goal of comparative genomics is an understanding of the forces which control gene order. This assumes that gene order is important, a supposition backed by the existence of genomic colinearity between many related species. In the bacterial chromosome, a polarity in the order of genes has been suggested, influenced by distance and orientation relative to the origin of DNA replication. We propose a model of the bacterial chromosome in which gene order is maintained by the adaptation of gene expression to local superhelical context. This force acts not directly at the genomic level but rather at the local gene level. A full understanding of gene-order conservation must therefore come from the bottom up.
Assuntos
Evolução Biológica , Cromossomos Bacterianos , DNA Bacteriano/química , DNA Super-Helicoidal/química , Replicação do DNA , DNA Bacteriano/genética , DNA Super-Helicoidal/genética , Escherichia coli/genética , Expressão Gênica , Genoma Bacteriano , Origem de Replicação , Salmonella typhimurium/genéticaRESUMO
Through hybridization of available probes, we have added nine genes to the macrorestriction map of the Haloferax mediterranei chromosome and five genes to the contig map of Haloferax volcanii. Additionally, we hybridized 17 of the mapped cosmid clones from H. volcanii to the H. mediterranei genome. The resulting 35-point chromosomal comparison revealed only two inversions and a few translocations. Forces known to promote rearrangement, common in the haloarchaea, have been ineffective in changing global gene order throughout the nearly 10(7) years of these species' divergent evolution.
Assuntos
Variação Genética , Genoma Bacteriano , Halobacteriales/genética , Evolução Biológica , Inversão Cromossômica , Cosmídeos/genética , Rearranjo Gênico , Genes Bacterianos , Marcadores Genéticos , Biblioteca Genômica , Mapeamento por Restrição , Especificidade da Espécie , Translocação GenéticaRESUMO
We have constructed a complete, five-enzyme restriction map of the genome of the archaeon Halobacterium sp. GRB, based on a set of 84 overlapping cosmid clones. Fewer than 30 kbp, in three gaps, remain uncloned. The genome consists of five replicons: a chromosome (2038 kbp) and four plasmids (305, 90, 37, and 1.8 kbp). The genome of Halobacterium sp. GRB is similar in style to other halobacterial genomes by being partitioned among multiple replicons and by being mosaic in terms of nucleotide composition. It is unlike other halobacterial genomes, however, in lacking multicopy families of insertion sequences.
