Diversidad genética de materiales nativos de aguacate guatemalteco a través del marcador molecular AFLP / Genetic diversity of native Guatemalan avocado through AFLP molecular marker

El aguacate es un cultivo de consumo a nivel mundial, y según teorías recientes, se sugiere a la región de la Sierra Nevada, en California, como centro de origen y, a Guatemala, como uno de los principales centros de domesticación. Mediante caracterizaciones morfológicas se ha reportado una alta diversidad genética en el país, pero debido al comportamiento de polinización cruzada e hibridaciones interraciales, no se ha podido detallar el estado genético actual de la especie. Sin embargo, los marcadores moleculares son útiles para este tipo de estudios al enfocarse en las diferencias a nivel del ADN. Este estudio analizó la diversidad genética del aguacate nativo guatemalteco de siete poblaciones geográficas con el marcador molecular AFLP. Los datos de estructura poblacional mostraron un alto grado de diversidad a nivel de individuos (Ht = 0.1933, Hw = 0.1872) y baja diferenciación entre poblaciones (Hb = 0.0061). Los resultados sugieren una alta tasa de migración que influye directamente en el grado de mezcla genética de los materiales analizados. El bajo índice de estructura poblacional apunta a un alto flujo genético entre las poblaciones, por lo que la especie no presenta mayor riesgo ante la deriva genética, minimizándose el riesgo de pérdida de alelos por fijación. Se sugiere el resguardado del recurso fitogénetico total y no únicamente de materiales promisorios, evitando así el riesgo de erosión genética de la especie y garantizando la permanencia de la diversidad genética, la cual será la base de futuros programas de mejoramiento.

Avocado is one of the most widely consumed crops worldwide and according to new theories, the Sierra Nevada region in California is suggested as the center of origin and Guatemala as one of the main domestication cen-ters. Through morphological characterizations, a high genetic diversity has been reported in the country, but due to the behavior of cross pollination and interracial hybridizations, it has not been possible to detail the current genetic status of the species. Molecular markers are useful for this type of study by focusing on differences at DNA level. This study analyzed the genetic diversity of the native Guatemalan avocado from seven geographic populations with AFLP molecular marker. Population structure data showed a high degree of diversity at the individual level (Ht = 0.1933, Hw = 0.1872) and low differentiation between populations (Hb = 0.0061). The results suggest a high rate of migration that directly influences the degree of genetic mixing of the analyzed materials. The low index of population structure points to a high genetic flow between populations, so that the species does not present a greater risk due to genetic drift, minimizing the risk of loss of alleles due to fixation. The protection of the total genetic resource is suggested, and not only of promising materials, thus avoiding the risk of genetic erosion of the species and guaranteeing the permanence of genetic diversity, which will be the basis of future breeding programs.

Phenotypic and genotypic analyses of an attenuated porcine reproductive and respiratory syndrome virus strain after serial passages in cultured porcine alveolar macrophages

The porcine reproductive and respiratory syndrome virus (PRRSV) is a globally ubiquitous swine viral pathogen that causes major economic losses worldwide. We previously reported an over-attenuated phenotype of cell-adapted PRRSV strain CA-2-P100 in vivo. In the present study, CA-2-P100 was serially propagated in cultured porcine alveolar macrophage (PAM) cells for up to 20 passages to obtain the derivative strain CA-2-MP120. Animal inoculation studies revealed that both CA-2-P100 and CA-2-MP120 had decreased virulence, eliciting weight gains, body temperatures, and histopathologic lesions similar to those in the negative control group. However, compared to CA-2-P100 infection, CA-2-MP120 yielded consistently higher viremia kinetics and enhanced antibody responses in pigs. All pigs inoculated with CA-2-MP120 developed viremia and seroconverted to PRRSV. During 20 passages in PAM cells, CA-2-MP120 acquired 15 amino acid changes that were mostly distributed in nsp2 and minor structural protein-coding regions. Among these changes, 6 mutations represented reversions to the sequences of the reference CA-2 and parental CA-2-P20 strains. These genetic drifts may be hypothetical molecular markers associated with PRRSV macrophage tropism and virulence. Our results indicate that the PAM-passaged CA-2-MP120 strain is a potential candidate for developing a live, attenuated PRRSV vaccine.

Selective intra-dinucleotide interactions and periodicities of bases separated by K sites: a new vision and tool for phylogeny analyses

Direct tests of the random or non-random distribution of nucleotides on genomes have been devised to test the hypothesis of neutral, nearly-neutral or selective evolution. These tests are based on the direct base distribution and are independent of the functional (coding or non-coding) or structural (repeated or unique sequences) properties of the DNA. The first approach described the longitudinal distribution of bases in tandem repeats under the Bose-Einstein statistics. A huge deviation from randomness was found. A second approach was the study of the base distribution within dinucleotides whose bases were separated by 0, 1, 2... K nucleotides. Again an enormous difference from the random distribution was found with significances out of tables and programs. These test values were periodical and included the 16 dinucleotides. For example a high ¨positive¨ (more observed than expected dinucleotides) value, found in dinucleotides whose bases were separated by (3K + 2) sites, was preceded by two smaller ¨negative¨ (less observed than expected dinucleotides) values, whose bases were separated by (3K) or (3K + 1) sites. We examined mtDNAs, prokaryote genomes and some eukaryote chromosomes and found that the significant non-random interactions and periodicities were present up to 1000 or more sites of base separation and in human chromosome 21 until separations of more than 10 millions sites. Each nucleotide has its own significant value of its distance to neutrality; this yields 16 hierarchical significances. A three dimensional table with the number of sites of separation between the bases and the 16 significances (the third dimension is the dinucleotide, individual or taxon involved) gives directly an evolutionary state of the analyzed genome that can be used to obtain phylogenies. An example is provided.

Aplicación de la genética de poblaciones en el ámbito de la medicina / Application of population genetics in the field of medicine

Las poblaciones humanas obedecen a los mismos supuestos evolutivos que el resto de los organismos, aunque mezclados con elementos sociales y culturales que pueden promover la expresión de ciertas enfermedades en grupos étnicos específicos, causadas principalmente por la frecuente endogamia. En este trabajo se analiza el principio de Hardy-Weinberg desde un enfoque médico, social y biológico, para entender los procesos evolutivos que dan lugar a las enfermedades autosómicas recesivas. A manera de conclusión se puede señalar que la incidencia de estas enfermedades está inversamente relacionada con los niveles de la variabilidad genética en las poblaciones, variabilidad que depende de eventos de colonización, recolonización y migración, así como de convenciones sociales como el racismo, la estratificación social y la segregación.

Human populations follow the same evolutionary principles as other organisms, although mixed with social and cultural elements, which can result in a high prevalence of certain diseases within specific ethnic groups. In this work, the Hardy-Weinberg principle is analyzed from a medical, social and biological viewpoint to understand the evolutionary processes of autosomal recessive diseases. It can be concluded that the incidence of these diseases is inversely related to the levels of genetic variability within populations, which depends on colonization, recolonization and migration events, as well as on social conventions such as racism, social stratification and segregation.

Molecular investigation of banana shrimp [P. merguiensis] populations from Persian Gulf and Oman sea using microsatellite markers

Molecular investigation of important commercial shrimp species is one of the main goals to find out the pure populations and brood stocking of marine resources. The purpose of the present study was to study the population of P. merguiensis and determining the extent of genetic diversity of this species. Samples were collected from three major distribution areas in the Persian Gulf and Oman Sea. Molecular investigation was carried out using microsatellite markers. Only five out of the eight primers of P. merguiensis produced good amplified PCR products with fixed annealing temperature. The rest of the primers were either not easily amplified or produced nonspecific bands. Seven alleles were found to be unique to each of the three populations of P.merguiensis. Occurrences of heterozygosity deficiency were found at most loci. These heterozygosity deficiencies in observed heterozygosity in comparison to expected heterozygosity may be due to inbreeding, genetic drift and consequences of illegal overharvesting of P. merguiensis in the studied areas as well. Deviation from Hardy-Weinberg Equilibrium in both studied species was significant in most microsatellite loci [p<0.001]. We observed deviation from HWE in most loci with hetrozygosity deficits. The genetic variation results showed that the pairwise Fst values were significant between studied populations. The assignment test revealed high gene flow between Hormoz and Jask and restricted genetic flow between Guatr and Hormoz populations. It seems that the changes in immigration patterns of populations between Hormoz, Jask and Guatr areas depend on the influence of Persian Gulf currents or the life cycle of P. merguiensis in studied areas. Alternatively, the presence of ecological barriers such as mangrove forests may result in restricted genetic flow between Guatr and both Hormoz and Jask populations

Oral epithelial stem cells in tissue maintenance and disease: the first steps in a long journey / 国际口腔科学杂志·英文版

The identification and characterization of stem cells is a major focus of developmental biology and regenerative medicine. The advent of genetic inducible fate mapping techniques has made it possible to precisely label specific cell populations and to follow their progeny over time. When combined with advanced mathematical and statistical methods, stem cell division dynamics can be studied in new and exciting ways. Despite advances in a number of tissues, relatively little attention has been paid to stem cells in the oral epithelium. This review will focus on current knowledge about adult oral epithelial stem cells, paradigms in other epithelial stem cell systems that could facilitate new discoveries in this area and the potential roles of epithelial stem cells in oral disease.

Foundational errors in the Neutral and Nearly-Neutral theories of evolution in relation to the Synthetic Theory: Is a new evolutionary paradigm necessary?

The Neutral Theory of Evolution (NTE) proposes mutation and random genetic drift as the most important evolutionary factors. The most conspicuous feature of evolution is the genomic stability during paleontological eras and lack of variation among taxa; 98% or more of nucleotide sites are monomorphic within a species. NTE explains this homology by random fixation of neutral bases and negative selection (purifying selection) that does not contribute either to evolution or polymorphisms. Purifying selection is insufficient to account for this evolutionary feature and the Nearly-Neutral Theory of Evolution (N-NTE) included negative selection with coefficients as low as mutation rate. These NTE and N-NTE propositions are thermodynamically (tendency to random distributions, second law), biotically (recurrent mutation), logically and mathematically (resilient equilibria instead of fixation by drift) untenable. Recurrent forward and backward mutation and random fluctuations of base frequencies alone in a site make life organization and fixations impossible. Drift is not a directional evolutionary factor, but a directional tendency of matter-energy processes (second law) which threatens the biotic organization. Drift cannot drive evolution. In a site, the mutation rates among bases and selection coefficients determine the resilient equilibrium frequency of bases that genetic drift cannot change. The expected neutral random interaction among nucleotides is zero; however, huge interactions and periodicities were found between bases of dinucleotides separated by 1, 2... and more than 1,000 sites. Every base is co-adapted with the whole genome. Neutralists found that neutral evolution is independent of population size (N); thus neutral evolution should be independent of drift, because drift effect is dependent upon N. Also, chromosome size and shape as well as protein size are far from random.

Genotypes and evolution characteristics of three patients with poor response to initial treatment of Lamivudine and Adefovir dipivoxil for hepatitis / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To understand the genotype characteristics and its evolution of patients with poor response to initial combined treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B.</p><p><b>METHODS</b>We detected the HBV genotypes of three patients-S1, S2, S3, who with poor response to initial treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B over 12 months by the application of cloning and sequencing method at the time point of baseline,4 weeks after treatment, 12 weeks, 24 weeks, 48 weeks, 60 weeks. 25 clones were randomly selected to identify and sequence at each time point.</p><p><b>RESULTS</b>The total number of clones from 3 patients with poor response to initial combined treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B at each time point was 398. About patient S1 at baseline, genotype C accounting for 8.3%, genotype B, for 91.7%, so genotype B was in dominant (22/24). But genotype C has gradually developed to 100% after treatment for 60 weeks. About patient S2 and S3, genotype B was the only type at baseline. However type B has gradually "drift" to type C during treatment. When treatment for 60 weeks, type C has taken the absolute advantage 75% for S2, and 100% for S3.</p><p><b>CONCLUSIONS</b>The cloning and sequencing can represent the overall genotype level better. HBV genotype has performed the evolution trend that genotype has drifted from B to C during long-term drug pressure, which is the main reason for poor response to initial combined treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B.</p>

Heterogeneous periodicity of drosophila mtDNA: new refutations of neutral and nearly neutral evolution

We found a consistent 3-site periodicity of the X²9 values for the heterogeneity of the distribution of the second base in relation to the first base of dinucleotides separated by 0 (contiguous), 1, 2, 3 ... 17 (K) nucleotide sites in Drosophila mtDNA. Triplets of X²9 values were found where the first was over 300 and the second and third ranged between 37 and 114 (previous studies). In this study, the periodicity was significant until separation of 2011K, and a structure of deviations from randomness among dinucleotides was found. The most deviant dinucleotides were G-G, G-C and C-G for the first, second and third element of the triplet, respectively. In these three cases there were more dinucleotides observed than expected. This inter-bases correlation and periodicity may be related to the tertiary structure of circular DNA, like that of prokaryotes and mitochondria, to protect and preserve it. The mtDNA with 19.517 bp was divided into four equal segments of 4.879 bp. The fourth sub-segment presented a very low proportion of G and C, the internucleotide interaction was weaker in this sub-segment and no periodicity was found. The maintenance of this mtDNA structure and organization for millions of generations, in spite of a high recurrent mutation rate, does not support the notion of neutralism or near neutralism. The high level of internucleotide interaction and periodicity indicate that every nucleotide is co-adapted with the residual genome.

Internucleotide correlations and nucleotide periodicity in Drosophila mtDNA: New evidence for panselective evolution

Analysis for the homogeneity of the distribution of the second base of dinucleotides in relation to the first, whose bases are separated by 0, 1, 2,... 21 nucleotide sites, was performed with the VIH-1 genome (cDNA), the Drosophila mtDNA, the Drosophila Torso gene and the human p-globin gene. These four DNA segments showed highly significant heterogeneities of base distributions that cannot be accounted for by neutral or nearly neutral evolution or by the "neighbor influence" of nucleotides on mutation rates. High correlations are found in the bases of dinucleotides separated by 0, 1 and more number of sites. A periodicity of three consecutive significance values (measured by the x²9) was found only in Drosophila mtDNA. This periodicity may be due to an unknown structure or organization of mtDNA. This non-random distribution of the two bases of dinucleotides widespread throughout these DNA segments is rather compatible with panselective evolution and generalized internucleotide co-adaptation.

Dermatoglyphic traits of six Chibcha-speaking Amerindians of Costa Rica, and an assessment of the genetic affinities among populations

Dermatoglyphic traits have been used to evaluate population structure and microdifferentiation in several populations. For Chibcha-speaking groups of Lower Central America there are few dermatoglyphic studies, but extensive linguistic, anthropological and genetic data support their historical, cultural and biological relationships. The main objectives of this study were to describe new dermatoglyphic data for six Chibcha- speaking Amerindians of Costa Rica, and to assess the relationships between these and other Amerindian and Eskimo groups, at different levels of population differentiation by means of multivariate analyses of quantitative traits. Sexual (2 =227.22, df=33, p<0.01),, and bimanual (2 =554.45, df=33, p<0.01) differences were both significant for the overall population, as has been reported previously. Remarkably, higher frequencies of arches, lower frequencies of whorls and lower means of total ridge counts were observed in the tribes analyzed compared with other American indians. At the lowest level of population differentiation, two Cabecar subpopulations (Aatlantic and Chirripo) were compared and no significant differences were found (FF=0.001, p=0.72),, suggesting that dermatoglyphic variation might not reflect known genetic divergence at this level of association. Comparisons within the Chibchan dataset using Principal Components Analysis (PPCA) placed the Huetar and the Cabecar in close proximity, and separated the Guatuso and the Guaymi. Additionally, the Chibchan tribes, although showing nearer proximity to Non-Andean South American groups, can be separated from other Amerindian and Eskimo populations, confirming previous results based on extensive genetic surveys and linguistic analyses that have demonstrated the existence of a Chibchan cluster within a larger South American phylogenetic group. The results obtained support the use of dermatoglyphics to assess interpopulation affinities, even at the level of tribes. Rev. Biol. Trop. 57 (SSuppl. 1): 357-369. Epub 2009 November 30.

Los dermatoglifos se han utilizado para evaluar la estructura poblacional y microdiferenciación de varias poblaciones. Para los grupos chibcha de Baja Centroamérica hay pocos estudios sobre dermatoglifos pero los datos lingüísticos, antropológicos y genéticos muestran la existencia de relaciones históricas, culturales y biológicas. Los objetivos del presente estudio fueron describir nuevos datos de dermatoglifos para seis tribus amerindias chibcha de Costa Rica y evaluar las relaciones entre estas y otros grupos amerindios y esquimales, a diferentes niveles de diferenciación poblacional por medio de análisis multivariados. Se encontraron diferencias significativas entre ambos sexos (2=27.22, df=3, p<0.01) y ambas manos (2=54.45, df=3, p<0.01), similar a lo descrito para otras poblaciones. Las tribus estudiadas se caracterizan por presentar alta frecuencia de arcos, baja frecuencia de verticilos y bajo conteo total de líneas. Al nivel más bajo de diferenciación poblacional, se compararon dos subpoblaciones cabécar (Atlántico y Chirripo) y no se encontraron diferencias significativas (F=0.001, p=0.72) lo cual sugiere que los dermatoglifos no permiten discriminar entre grupos a este nivel. Las comparaciones entre las tribus chibcha estudiadas por medio de análisis de componentes principales (PCA) ubican a los huetar cercanos a los cabécar; mientras que los guatuso y guaymí aparecen como grupos más aislados. Adicionalmente, el grupo chibcha, aunque muestra mayor afinidad con poblaciones suramericanas, puede separarse de otras tribus amerindias y esquimales, confirmando los resultados de estudios genéticos y lingüísticos que han colocado a los chibchas dentro del un grupo filogenético mayor formado por tribus amerindias de Suramerica. Dichos resultados confirman el valor de las características dermatoglíficas para evaluar las afinidades interpoblacionales aún a nivel de tribus.

Variabilidad genética de poblaciones de Triatoma flavida (Hemiptera: Reduviidae) en la península de Guanahacabibes / Genetic variability of Triatoma flavida (Hemiptera: Reduviidae) in Guanahacabibes

La enfermedad de Chagas es una enfermedad transmitida por triatomineos. Triatoma flavida es una especie selvática autóctona de Cuba, que presumiblemente es atraída a las casas por la luz, de las especies encontradas en Cuba es la más abundante. Se investigó la variabilidad genética intrapoblacional e interpoblacional de ejemplares de T. flavida colectados en la región occidental de Cuba, utilizando la técnica del ADN polimórfico amplificado al azar, con la determinación ademßs de posibles relaciones genéticas entre las poblaciones. Un total de 10 cebadores al azar (OPA-1 al 10) fueron usados para evaluar la variabilidad genética dentro de una población y entre 9 poblaciones diferentes de T. flavida, mediante la técnica de ADN polimórfico amplificado al azar. Además, se evaluó la diversidad genética entre individuos salvajes y de la primera generación (F1) obtenidos en el laboratorio, así como entre los diferentes estadios de esta especie. No se detectaron diferencias en los patrones de amplificación del ADN entre los individuos silvestres y de la F1; al igual que entre los diferentes estadios de esta especie. Se encontró homogeneidad genética dentro de la población estudiada y una variabilidad genética baja entre las diferentes poblaciones de T. flavida. Se obtuvieron 2 grupos bien definidos según el análisis del ADN polimórfico amplificado al azar, mostrando concordancia con el origen geográfico, en las poblaciones capturadas en áreas del occidente y el oriente de Guanahacabibes, Pinar del Río. Entre estas poblaciones se encontró una pequeña diferenciación genética (Fst 0,030) y tasas de migración (N> 1) que revelan flujo genético y homogeneidad genética. Los resultados presentados en este estudio establecen una aproximación a la estructura genética de T. flavida. La homogeneidad genética encontrada entre los individuos silvestres de T. flavida constituye un aspecto importante para la implementación de las políticas de control de este vector.

Chagas disease is a Triatomineos-borne disease. Triatoma flavida is an indigenous Cuban species, presumably attracted to houses by light and it is the most abundant species in the country. The intrapopulatinal and interpopulational genetic variability of T. flavida collected in the western region, using the Random Amplified Polymorphic DNA (RAPD) technique, thus determining possible genetic relationships among the populations. A total of ten random primers (OPA-1 at the 10) were used to evaluate the genetic variability in one population and among 9 populations of T. flavida using the RAPD technique. We also evaluate the genetic diversity among wild individuals and their first generation (F1) obtained in the laboratory as well as different stages of this species. Differences were not detected in the amplification patterns among the wild individuals and the F1. The same results were achieved among different life cycles of this species. Genetic homogeneity of the studied population and low genetic variability among different T. flavida populations were observed. Two well-defined groups were obtained according to random amplified polymorphic DNA data; they matched with the geographical origin in the populations captured in areas from east and west of Guanahacabibes, Pinar del Río. Among these populations, small genetic differentiation (Fst 0,030) was found as well as migration rates (N> 1), which reveals the gene flow and genetic homogeneity. The results of this study constitute an approach to the genetic structure of T. flavida. The genetic homogeneity between wild individuals of T. flavida represents an important item for the implementation of the vector control programs.

Epidemiological and molecular characterization of seasonal influenza A/H3N2 viruses circulating in Shenzhen, 2005 - 2007 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To determine the epidemiological characteristics of seasonal influenza in Shenzhen from 2005 to 2007 and the molecular variation of HA1 domain of influenza H3N2 viruses.</p><p><b>METHODS</b>The consultation rate for influenza-like illness (ILI) were calculated weekly for indicating the influenza activities (the Shenzhen Influenza Surveillance System mainly consisted of 16 institutions with 9 hospitals, 6 districts and one municipal centers of disease control and prevention). Pharyngeal swabs from the cases of ILI, which were collected during 2005 to 2007 from the city-wide and quality-controlled surveillance network, were used to propagate the viruses. The HA1 region of the influenza A/H3N2 viruses were detected by RT-PCR and sequenced subsequently. The analyses of pairwise amino acid variations, genetic clustering and phylogenetics was performed.</p><p><b>RESULTS</b>The activity levels of influenza showed certain changes during each year from 2005 to 2007, and there were summer peaks from May to July in 2006 and 2007. The positive rates of influenza virus were 4.78% (114/2385), 5.77% (212/3674) and 12.12% (343/2831) from 2005 to 2007 respectively. The weekly isolating rates changed accordingly with the trend of the percentages of ILI. The proportions of influenza H3N2 virus were 25.46% (28/114) and 2.83% (6/212) in 2005 and in 2006 respectively, but the proportion increased to 62.68% (215/343), which indicated that H3N2 virus became the predominant strain in 2007. Phylogenetic clustering analysis of influenza H3N2 virus revealed that there were 5 clades. The viruses which were isolated in 2005 contained in the clade I and II, the viruses in 2006 were comprised in clade III, and clade IV and V included the viruses isolated in 2007. Although the stem of cladogram developed with one accord of the time isolated viruses, the viruses which were similar to vaccine strains had circulated in Shenzhen before a given strain was determined as vaccine strain by WHO. It was also noticed that more amino acid changes at antigenic sites, especially at sites A and B in the H3N2 viruses, were found in 2007 than that in 2005 and in 2006. But the sequences at the receptor-binding sites and disulphide bond sites were conserved and no new circulating strain for genetic reassortment had been found in the period.</p><p><b>CONCLUSION</b>Shenzhen might be one of areas where the ongoing genetic drift of influenza H3N2 viruses appeared earlier in China. The changes of influenza H3N2 virus showed the active status in the population. The results suggested that monitoring seasonal influenza viruses by sequence analysis could provide important and timely information on the appearance of strains with epidemiologic significance.</p>

Comparação de metodologias de seleção sob oscilação genética / Comparison of selection methodologies under genetic drift

Determinou-se o número adequado de repetições na comparação de métodos de seleção tradicionais e associados a marcadores moleculares, com diferentes tamanhos efetivos e sob diferentes sistemas de acasalamento dos reprodutores selecionados, usando simulação com o programa GENESYS. Para comparar os diferentes métodos de seleção utilizaram-se populações com tamanhos efetivos de 18,18 (TE1) e de 66,66 (TE2) e uma, 10 e 30 repetições por geração, avaliando-se os valores fenotípicos médios. Para as situações com apenas uma repetição, os resultados apresentaram incoerências, independentemente do tamanho efetivo (TE1 ou TE2) ou do sistema de acasalamento (RAA - reprodutores acasalados aleatoriamente, EIC - exclusão de irmãos completos ou EICMI - exclusão de irmãos completos e meio-irmãos). Observou-se que a oscilação genética influencia o ganho genético, principalmente, em populações com pequeno tamanho efetivo e que um valor mínimo de 10 repetições por geração é necessário para assegurar a consistência dos resultados obtidos pelos métodos de seleção.

This work was carried out to determine the required number of replicates for comparison of conventional and molecular marker-associated selection methods in distinct effective population sizes and different mating systems, by simulations using the software GENESYS. Effective populational size of 18.18 (ES1) and 66.66 (ES2), and one, 10, and 30 replicates per generation were used to compare the different selection methods, based on mean phenotypic values. Incongruences results were observed when a single replicate was considered independently of effective size (ES1or ES2) and the mating system (random mating; exclusion of full-sibs or exclusion of both full and half-sibs). Genetic oscillation influenced the genetic gain, mainly in populations of small effective size. Furthermore, at least 10 replicates per generation were required to obtain sound consistent results for both selection methods.

Complementarity-determining region 3 analysis of T cell receptor beta chain variable region in peripheral blood mononuclear cells cultured with interleukin-2 / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the drift of the complementarity-determining region 3 (CDR3) of T cell receptor beta (TCRbeta) chain variable region in T cells of healthy volunteers cultured with interleukin-2 (IL-2).</p><p><b>METHODS</b>T cells were isolated from the peripheral blood and cultured in vitro in the presence of IL-2. The non-specific killing effect of the cells was analyzed by LDH releasing assay, and the distribution of TCRbeta chain CDR3 in healthy volunteers by immunoscope spectratyping method to evaluate the clonality of the T cells.</p><p><b>RESULTS</b>The results showed Gaussian distribution of TCR Vbeta gene CDR3 in healthy volunteers. The T cell cultured with IL-2, however, displayed some anomalous and oligoclonal expansion in different TCR Vbeta families without killing effect against nasophargngal carcinoma cell line CNE2.</p><p><b>CONCLUSION</b>IL-2 may affect TCRbeta chain CDR3 distribution in T cells cultured in vitro.</p>

Genetic analysis on HA1 and NA regions of influenza virus subtype A3 isolates of Zhejiang province during 1998-2005 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the relationship between influenza epidemic and genetic characteristic on HA and NA regions of influenza virus subtype A3 isolates of Zhejiang province in the recent years.</p><p><b>METHODS</b>RNA of 25 influenza virus subtype A3 isolates, circulated in Zhejiang province during 1998 to 2005, was extracted. HA1 and NA regions were amplified and sequenced. All the sequence data were analyzed using BioEdit.</p><p><b>RESULTS</b>HA1 and NA regions of all the isolates belonged to 987nt and 1362nt, encoding protein of 329 and 454 amino acids respectively. Isolates shared amino acid homology of 90.9%-99.3% and 95.2%-99.5% on HA1 and NA regions, while divergence on HA1 was greater than that on NA region. During a period of 8 years, 30 amino acids on HA1 region were substituted and 14 of which refer to 4 antigenic determinant sites. Meanwhile,21 amino acids on NA region were substituted and 5 of which referred to 3 antigenic determinant sites. Significant divergences, both in HA1 and NA, were observed among isolates in 1998 and 2002, showing that they belonged to absolutely different branches. Additionally, influenza virus subtype A3 isolates identified in recent years, with 11 N-linked glyeosylation sites in HA1 region, had 5 sites more than early A/Aichi/2/68 strain. Since 1998,3 sites had been inserted in epidemic strains, indicating the accelerated trend of glyeosylation sites were increasing.</p><p><b>CONCLUSION</b>There is a correlation between antigenic drift of influenza virus subtype A3 and the two epidemics in Zhejiang province in 1998 and 2002.</p>

Structure and genetic variability in Nellore (Bos indicus) cattle by pedigree analysis

Parameters based on the probability of gene origin were used to describe the genetic variability in strains of Nellore and polled Nellore (Bos indicus) cattle that participated in the Program for Genetic Improvement of the Nellore Breed (Programa de Melhoramento Genético da Raça Nelore). The effective number of founders was 87.2 for Nellore and 107.9 for polled Nellore, while the number of ancestors was 59.8 for Nellore and 61.5 for polled Nellore and the remaining genomes were 39.4 for Nellore and 34.5 for polled Nellore cattle. The results indicate an intense use (by artificial insemination) of some sires and the absence of subdivisions in the population. The family structure in the two breeds was mainly caused by the genetic contribution of the same sires and only mating preferences for descendants of some founders are recorded in either breed. The results suggest that genetic variability needs monitoring in order to avoid the compromise of genetic improvement in economically important traits in the breeding program.

Molecular biological characteristics and genetic significance of Yersinia pestis in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the molecular biological characteristics in order to analyse the genetic background of Yersinia pestis in China.</p><p><b>METHODS</b>Primary datum on ribotyping, pulsed field gene electrophoresis (PFGE), random amplified polymorphic DNA (RAPD) and insertion sequence (IS) of Yersinia pestis were used and under cluster analysis. Genetic interval and various methods of recognized molecular feature between different strains were evaluated.</p><p><b>RESULTS</b>Ribotypes the PFGE types seemed to be corresponding. Stains from Microtus fuscus and area in Tibet Zhongba belonged to 7 copy rRNA gene and the genetic interval were the far more with 6 copy rRNA gene stains, and not definite with RAPD, but with many exceptions. The genetic interval between strains were showed by resemble value.</p><p><b>CONCLUSION</b>Yersinia pestis in China had its own manifold, particular molecular biological characteristics due to natural barriers, geographical complex, circumstances in Tianshan Mountains and Gandise Mountains areas. Yersinia pestis were limited to separateness, evoluted only in certain areas to form a great many gene types.</p>

Genetic analysis of Yersinia pestis strains isolated in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>The strains of Yersinia pestis isolated in different period and different natural foci in China were analyzed.</p><p><b>METHODS</b>Traditional and molecular biological methods were used. Rhamnose fermentation, rRNA gene copy number, nitrite reduction, and the glycerol fermentation were important characters for typing, and pulse field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) profile could reflect the genetic distance between the strains.</p><p><b>RESULTS</b>The strains could be divided into 15 genetic types by those 6 characters with each of them covered an isolated geographical territories.</p><p><b>CONCLUSION</b>The characters of strains were described; the genetic relationship of different types, their evolution, and the forming and shift of plague natural foci were analyzed.</p>

Pterin & DHPR measurement and DNA analysis in Korean PKU patients

Phenylketonuria is metabolic disorder that results from a deficiency of the hepatic phenylalanine hydroxylase. But among patients with hyperphenylalaninemia, the defect resides in one of the enzymes necessary for production or recycling of tetrahydrobiopterin (BH4). The reduction of BH4 affects not only phenylalanine metabolism but also formation of the tyrosine related neurotransmitter, dopamin and tryptophan related neurotransmitter, serotonin. Administration of L-dopa and 5-hydroxytriptophan seems to be the most effective treatment and may prevent irreversible neurologic damage if started early in life in hyperphenylalaninemia due to deficiency of cofactor BH4. Therefore, all patients with PKU and hyperphenylalaninemia should be tested for BH4 deficiency as early as passible. So we measured reduced forms of biopterin in urines of 19 phenylketonuria patients by Funkushima and Nixon method and 13 of PKU patients measured dihydropterin reductase (DHPR) in white blood cells by modified Narisawa method. We could not find abnormal pterin patterns of cofactor BH4 and normal value of DHPR. All Korean 19 PKU children were classic PKU. A missense mutation has been identified in the phenylalanine hydroxylase (PAH) gene of 16 Koran PKU patients. 5 mutations (IVS4, Y204 C, R243Q, Y356 X, R413 P) have been identified. The frequency of these mutations was found to be 50% of PKU alleles. The IVS4 mutation had a high frequency in Korea and southern China, due to the result of the founder effect and genetic drift. the R413 P mutation, which may have originated in the regions surrounding the Baikal, expanded to northen China and Japan. We were not able to find Caucasian mutations in Korean ptiets. PKU mutations occured after racial divergence between Caucasian and Mongoloids. We observed that PKU patients with Y 204 C and R413 P mutations showed mild mild clinical phenotype but IVS4 mutation had severe mental retardation. the establishment of genotype will therefore aid in the prediction of clinical phenotypes in patients with this disease. So, pterin and DHPR measurement and DNA analsis will be useful for prognosis and proper treatment of PKU patients.