RESUMO
mHR23B encodes one of the two mammalian homologs of Saccharomyces cerevisiae RAD23, a ubiquitin-like fusion protein involved in nucleotide excision repair (NER). Part of mHR23B is complexed with the XPC protein, and this heterodimer functions as the main damage detector and initiator of global genome NER. While XPC defects exist in humans and mice, mutations for mHR23A and mHR23B are not known. Here, we present a mouse model for mHR23B. Unlike XPC-deficient cells, mHR23B(-/-) mouse embryonic fibroblasts are not UV sensitive and retain the repair characteristics of wild-type cells. In agreement with the results of in vitro repair studies, this indicates that mHR23A can functionally replace mHR23B in NER. Unexpectedly, mHR23B(-/-) mice show impaired embryonic development and a high rate (90%) of intrauterine or neonatal death. Surviving animals display a variety of abnormalities, including retarded growth, facial dysmorphology, and male sterility. Such abnormalities are not observed in XPC and other NER-deficient mouse mutants and point to a separate function of mHR23B in development. This function may involve regulation of protein stability via the ubiquitin/proteasome pathway and is not or only in part compensated for by mHR23A.
Assuntos
Reparo do DNA , Proteínas de Ligação a DNA/genética , Desenvolvimento Embrionário e Fetal , Proteínas Fúngicas/genética , Infertilidade Masculina/genética , Proteínas de Saccharomyces cerevisiae , Animais , Peso Corporal , Linhagem Celular , Sobrevivência Celular , Anormalidades Craniofaciais/embriologia , Anormalidades Craniofaciais/genética , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/fisiologia , Relação Dose-Resposta à Radiação , Olho/patologia , Feminino , Fertilidade , Fibroblastos/fisiologia , Fibroblastos/efeitos da radiação , Proteínas Fúngicas/química , Proteínas Fúngicas/fisiologia , Marcação de Genes , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Tamanho do Órgão , Placenta/patologia , Espermatogênese , Testículo/patologia , Testículo/fisiologia , Testículo/fisiopatologia , Raios UltravioletaRESUMO
BACKGROUND: The insufflation of cold gas during laparoscopic surgery exposes patients to the risk for hypothermia. The objectives of this study were to investigate whether heating or humidification of insufflation gas could prevent peroperative hypothermia in a rat model, and to assess whether the peritoneum was affected by heating or humidification of the insufflation gas. METHODS: Rats were exposed to insufflation with either cold, dry carbon dioxide CO2 (group I); cold, humidified CO2 (group II); warm, dry CO2 (group III); or warm, humidified CO2 (group IV); another group underwent gasless laparoscopy (group V). Core temperature and intraperitoneal temperature were registered in all animals during 120 minutes. Specimens of the parietal peritoneum were taken directly after desufflation and 2 and 24 hours after the procedure. All specimens were analyzed with scanning electron microscopy (SEM). RESULTS: During the 120-minute study period, core temperature and intraperitoneal temperature were significantly reduced in groups I, II, and III. In the animals that underwent warm, humidified insufflation (group IV) and the gasless controls (group V), intraoperative hypothermia did not develop. At SEM, retraction and bulging of mesothelial cells and exposure of the basal lamina were seen in the four insufflation groups (groups I-IV) and also in the gasless controls (group V). CONCLUSION: Insufflation with cold, dry CO2 may lower the body temperature during laparoscopic surgery. Hypothermia can be prevented by both heating and humidifying the insufflation gas. Changes of the peritoneal surface occur after CO2 insufflation, despite heating or humidifying, and also after gasless surgery.
Assuntos
Dióxido de Carbono , Hipotermia/prevenção & controle , Complicações Intraoperatórias/prevenção & controle , Pneumotórax Artificial/métodos , Animais , Temperatura Corporal , Umidade , Masculino , Microscopia Eletrônica de Varredura , Peritônio/fisiologia , Peritônio/ultraestrutura , Pneumotórax Artificial/efeitos adversos , Distribuição Aleatória , Ratos , Ratos Endogâmicos BN , TemperaturaRESUMO
This paper describes the design and functioning of a low-cost computerized system for monitoring the voluntary activity of mice in running wheels. The required software is written in Turbo Pascal(r) and provided via the Internet (http://www.eur.nl/fgg/ch1/rodent.html). The system accommodates the simultaneous monitoring of 20 animals over a virtually unlimited period. Two applications of the system are presented; one monitors the circadian rhythm of mice, and the other tests muscle strength and endurance.
RESUMO
The presence of porcine endogenous retroviruses presents a potential risk of transmission of infectious diseases (xenozoonosis) if tissues and organs from genetically modified pigs are to be used in xenotransplantation. Here, we report that intracellular expression of a llama single-domain antibody against p15, the matrix domain protein of the porcine endogenous retrovirus Gag polyprotein, blocks retrovirus production, providing the possibility of eliminating the risk of infection in xenotransplantation.
Assuntos
Anticorpos Antivirais/fisiologia , Retrovirus Endógenos/fisiologia , Produtos do Gene gag/antagonistas & inibidores , Infecções por Retroviridae/prevenção & controle , Suínos/virologia , Transplante Heterólogo/efeitos adversos , Proteínas da Matriz Viral/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Afinidade de Anticorpos , Mapeamento de Epitopos , Produtos do Gene gag/imunologia , Humanos , Soros Imunes/imunologia , Cadeias Pesadas de Imunoglobulinas/fisiologia , Região Variável de Imunoglobulina/fisiologia , Dados de Sequência Molecular , Proteínas da Matriz Viral/imunologia , Replicação ViralRESUMO
Plasma phospholipid transfer protein (PLTP) is thought to be involved in the remodeling of high density lipoproteins (HDL), which are atheroprotective. It is also involved in the metabolism of very low density lipoproteins (VLDL). Hence, PLTP is thought to be an important factor in lipoprotein metabolism and the development of atherosclerosis. We have overexpressed PLTP in mice heterozygous for the low density lipoprotein (LDL) receptor, a model for atherosclerosis. We show that increased PLTP activity results in a dose-dependent decrease in HDL, and a moderate stimulation of VLDL secretion (=1.5-fold). The mice were given a high fat, high cholesterol diet, which resulted in hypercholesterolemia in all animals. HDL concentrations were dramatically reduced in PLTP-overexpressing animals when compared with LDL receptor controls, whereas VLDL + LDL cholesterol levels were identical. Susceptibility to atherosclerosis was increased in a PLTP dose-responsive manner. We conclude that PLTP increases susceptibility to atherosclerosis by lowering HDL concentrations, and therefore we suggest that an increase in PLTP is a novel, long term risk factor for atherosclerosis in humans.
Assuntos
Arteriosclerose/sangue , Proteínas de Transporte/sangue , Proteínas de Membrana/sangue , Proteínas de Transferência de Fosfolipídeos , Animais , HDL-Colesterol/sangue , VLDL-Colesterol/sangue , VLDL-Colesterol/metabolismo , Dieta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fatores de RiscoRESUMO
Mice homozygous for the autosomal recessive mutation claw paw (clp) are characterized by limb posture abnormalities and congenital hypomyelination, with delayed onset of myelination of the peripheral nervous system but not the central nervous system. Although this combination of limb and peripheral nerve abnormalities in clp/clp mice might suggest a common neurogenic origin of the syndrome, it is not clear whether the clp gene acts primarily in the neurone, the Schwann cell or both. In the work described here, we address this question of cell autonomy of the clp mutation through reciprocal nerve grafting experiments between wild-type and clp/clp animals. Our results demonstrate that the clp mutation affects the Schwann cell compartment and possibly also the neuronal compartment. These data suggest that the clp gene product is expressed in Schwann cells as well as neurones and is likely to be involved in direct axon--Schwann cell interactions. Within the Schwann cell, clp affects a myelin-related signaling pathway that regulates periaxin and Krox-20 expression, but not Oct-6.
Assuntos
Mutação , Células de Schwann/patologia , Animais , Axônios/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteína 2 de Resposta de Crescimento Precoce , Regulação da Expressão Gênica no Desenvolvimento , Casco e Garras/anormalidades , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Bainha de Mielina/metabolismo , Regeneração Nervosa/genética , Condução Nervosa/genética , Proteínas de Transporte de Cátions Orgânicos/genética , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Células de Schwann/metabolismo , Nervo Isquiático/lesões , Nervo Isquiático/patologia , Nervo Isquiático/fisiologia , Nervo Isquiático/transplante , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , TransplantesRESUMO
Numerous murine models of polycystic kidney disease (PKD) have been described. While mouse models are particularly well suited for investigating the molecular pathogenesis of PKD, rats are well established as an experimental model of renal physiologic processes. Han:SPRD-CY: rats have been proposed as a model for human autosomal dominant PKD. A new spontaneous rat mutation, designated wpk, has now been identified. In the mutants, the renal cystic phenotype resembles human autosomal recessive PKD (ARPKD). This study was designed to characterize the clinical and histopathologic features of wpk/wpk mutants and to map the wpk locus. Homozygous mutants developed nephromegaly, hypertension, proteinuria, impaired urine-concentrating capacity, and uremia, resulting in death at 4 wk of age. Early cysts were present in the nephrogenic zone at embryonic day 19. These were localized, by specific staining and electron microscopy, to differentiated proximal tubules, thick limbs, distal tubules, and collecting ducts. In later stages, the cysts were largely confined to collecting ducts. Although the renal histopathologic features are strikingly similar to those of human ARPKD, wpk/wpk mutants exhibited no evidence of biliary tract abnormalities. The wpk locus maps just proximal to the CY: locus on rat chromosome 5, and complementation studies demonstrated that these loci are not allelic. It is concluded that the clinical and renal histopathologic features of this new rat model strongly resemble those of human ARPKD. Although homology mapping indicates that rat wpk and human ARPKD involve distinct genes, this new rat mutation provides an excellent experimental model to study the molecular pathogenesis and renal pathophysiologic features of recessive PKD.