RESUMO
Latitude-correlated polymorphisms can be due to either selection-driven evolution or gene flow. To discriminate between them, we propose an approach that studies subpopulations springing from a single population that have lived for generations at different latitudes and have had a low genetic admixture. These requirements are fulfilled to a large extent by Ashkenazi and Sephardi Jews. The original population lived at a latitude of 35 degrees N, where the Sephardis still live. The Ashkenazis, however, moved to a latitude of 50 degrees N, starting about 10 centuries ago. The present study examines 3 latitude-correlated polymorphisms: PGP, PGM1, and AHSG. We found that PGP*2 and AHSG*2 alleles most likely underwent selection-driven evolution, but that PGM1*ts allele was not similarly affected. Since temperature might have been considered a reasonable selective factor, we also studied a population living at >800 m above sea level from Aosta Valley (Italy).
Assuntos
Proteínas Sanguíneas/genética , Emigração e Imigração/estatística & dados numéricos , Frequência do Gene/genética , Geografia , Judeus/genética , Fosfoglucomutase/genética , Monoéster Fosfórico Hidrolases/genética , Polimorfismo Genético/genética , Seleção Genética , Altitude , Análise Discriminante , Emigração e Imigração/tendências , Haplótipos , Humanos , Itália , Fenótipo , Temperatura , alfa-2-Glicoproteína-HSRESUMO
We analyzed male meiosis in mutants of the chickadee (chic) locus, a Drosophila melanogaster gene that encodes profilin, a low molecular weight actin-binding protein that modulates F-actin polymerization. These mutants are severely defective in meiotic cytokinesis. During ana-telophase of both meiotic divisions, they exhibit a central spindle less dense than wild type; certain chic allelic combinations cause almost complete disappearance of the central spindle. Moreover, chic mutant spermatocytes fail to form an actomyosin contractile ring. To further investigate the relationships between the central spindle and the contractile ring, we examined meiosis in the cytokinesis-defective mutants KLP3A and diaphanous and in testes treated with cytochalasin B. In all cases, we found that the central spindle and the contractile ring in meiotic ana-telophases were simultaneously absent. Together, these results suggest a cooperative interaction between elements of the actin-based contractile ring and the central spindle microtubules: When one of these structures is disrupted, the proper assembly of the other is also affected. In addition to effects on the central spindle and the cytokinetic apparatus, we observed another consequence of chic mutations: A large fraction of chic spermatocytes exhibit abnormal positioning and delayed migration of asters to the cell poles. A similar phenotype was seen in testes treated with cytochalasin B and has been noted previously in mutants at the twinstar locus, a gene that encodes a Drosophila member of the cofilin/ADF family of actin-severing proteins. These observations all indicate that proper actin assembly is necessary for centrosome separation and migration.
Assuntos
Divisão Celular/fisiologia , Centrossomo/metabolismo , Proteínas Contráteis/metabolismo , Proteínas de Drosophila , Fuso Acromático/metabolismo , Actinas/metabolismo , Anáfase/fisiologia , Animais , Sequência de Bases , Drosophila melanogaster/fisiologia , Epistasia Genética , Genes de Insetos/genética , Masculino , Meiose/fisiologia , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/fisiologia , Microtúbulos/metabolismo , Dados de Sequência Molecular , Mutação/genética , Mutação/fisiologia , Profilinas , Espermatogênese/fisiologia , Telófase/fisiologia , Fatores de TempoRESUMO
The mouse HTF9 locus contains two genes that are bidirectionally transcribed with opposite polarity from a shared CpG-rich island. Both genes were previously shown to be expressed in a housekeeping fashion in mouse. We have now determined the molecular organization of the genes over 12 kb surrounding the island. In addition, we show that the HTF9 locus resides in the proximal region of mouse chromosome 16. We have sequenced the cDNAs corresponding to both divergent transcripts. Both genes appear to code for novel proteins that are structurally unrelated to each other. Finally, we show that both genes are highly conserved and efficiently expressed in human cells.
Assuntos
Homologia de Genes/genética , Proteínas Nucleares , Regiões Promotoras Genéticas/genética , Sequências Repetitivas de Ácido Nucleico/genética , Proteína ran de Ligação ao GTP , Sequência de Aminoácidos , Animais , Sequência de Bases , Southern Blotting , Cruzamentos Genéticos , Éxons/genética , Expressão Gênica/fisiologia , Variação Genética/genética , Humanos , Íntrons/genética , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Proteínas/genética , Proteínas de Ligação a RNAAssuntos
Células/enzimologia , Metilases de Modificação do DNA/metabolismo , Fosfatos de Dinucleosídeos/metabolismo , Células Eucarióticas/enzimologia , Cromossomo X/metabolismo , Composição de Bases , Clonagem Molecular , DNA/análise , DNA/metabolismo , Enzimas de Restrição do DNA , Feminino , Humanos , MetilaçãoRESUMO
In the present paper we report on new data of the frequency of common and rare variants in the Italian population for ADA, AK-1, 6-PGD, EsA, EsB, EsD, PGM-1, PGM-2, SOD-A, AcP, GPT, and PGI. Moreover we present a comprehensive review of the available data on the electrophoretic variants of red cell enzymes in Italians. We find a considerable degree of genetic heterogeneity between the various populations living in the Peninsula and between the population of the Peninsula and of Sardinia. We also find that the estimates of the average heterozygosity are considerably smaller for the population of Sardinia as compared to Peninsula and Sicily. Finally, we report on the occurrence of several uncommon enzyme variants, which overall frequency is very similar to previously reported estimates for North European populations (Harris et al. 1974).
Assuntos
Enzimas/genética , Eritrócitos/enzimologia , Variação Genética , Genética Populacional , Fosfatase Ácida/genética , Adenilato Quinase/genética , Alanina Transaminase/genética , Aminoidrolases/genética , Esterases/genética , Frequência do Gene , Triagem de Portadores Genéticos , Glucose-6-Fosfato Isomerase/genética , Humanos , Itália , Fosfoglucomutase/genética , Fosfogluconato Desidrogenase/genética , Superóxido Dismutase/genéticaRESUMO
On a sample of the population of mixed African ancestry living in Bluefields, Nicaragua, the pattern of migration and the distribution of red cell and serum genetic markers have been studied. It is concluded that, in spite of a considerable level of internal and external migration, a distinctive genetic structure is maintained by the population. Moreover, a strongly negative assortative mating can be observed between people inhabiting the western and eastern areas of Nicaragua. It is estimated that most, if not all, of the genetic pool of the population is accounted for by a process of admixture between African and Indian peoples.
Assuntos
População Negra/genética , Marcadores Genéticos/análise , Genética Populacional , Migrantes , Antropologia Cultural , Demografia , Enzimas/análise , Enzimas/genética , Feminino , Frequência do Gene , Humanos , Masculino , Nicarágua , Fenótipo , Polimorfismo Genético , Estados UnidosRESUMO
Blood group systems ABO, RH, MNS, KEL, FY, LU and P, red cell enzymes ACP1, PGM1, PGM2, ADA, DIA and PHI, serum markers GC, HP, IGHG1, IGHG3 and IGK were examined in about 900 individuals sampled in 11 Sardinian isolates. The genetic differentiation turned out to be relatively high and the relevance of selected and neutral genes has been evaluated.
Assuntos
Antígenos de Grupos Sanguíneos/genética , Heterozigoto , Polimorfismo Genético , Adolescente , Alelos , Feminino , Frequência do Gene , Marcadores Genéticos , Humanos , Itália , Masculino , LinhagemRESUMO
The electrophoretic polymorphism of the PGP locus has been studied in about 1,700 Italians. The sample consisted of individuals from Viareggio (North-Central Italy), Rome (Central Italy) and Cagliari (Sardinia, Southern Italy). Comparison among the three groups showed a high degree of heterogeneity. The Sardinian sample was well differentiated from the other two concerning the frequencies of both the PGP3 and of PGP2 alleles. The frequency of the PGP1 allele varied from 0.900 (Viareggio) to 0.987 (Cagliari). The gene frequencies, together with those available for other European populations were plotted against the latitudes of the different localities sampled and fitted to a North-South cline.
Assuntos
Monoéster Fosfórico Hidrolases/genética , Clima , Eritrócitos/enzimologia , Frequência do Gene , Humanos , Polimorfismo GenéticoRESUMO
The effect of 6-propyl-2-thiouracil (PTU), and 1-methyl-2-mercaptoimidazole (MMI) on thyroglobulin (Tg) biosynthesis has been studied in vivo and in vitro. In vivo experiments were performed in rats treated for 20 days with PTU or MMI, analyzing soluble and particulate, cold and 125I-labelled, Tg. Thyroglobulin biosynthesis was also investigated by in vitro experiments, incubating thyroid tissue with labelled amino acid and carbohydrate in the presence of antithyroid compounds. It has been found that in vivo antithyroid agents decrease the amount of soluble Tg and increase the proportion of particulate Tg. Tg from treated animals is poorly iodinated being mainly represented by its 12S subunit. In vitro studies demonstrate that PTU and MMI inhibit Tg biosynthesis which is impaired in the polypeptide synthesis as well as in carbohydrate chains addition. Thus the inhibition of the hormonogenetic processes induced by antithyroid treatment leading to a depressed iodinating activity also appears to be related to a significant impairment of the production of the Tg molecule, the specific iodine acceptor.
