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Evaluation of algorithms used to order markers on genetic maps

MOLLINARI, M.; MARGARIDO, G. R. A.; VENCOVSKY, R.; GARCIA, A. A. F.
Fonte: NATURE PUBLISHING GROUP Publicador: NATURE PUBLISHING GROUP
Tipo: Artigo de Revista Científica
ENG
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When building genetic maps, it is necessary to choose from several marker ordering algorithms and criteria, and the choice is not always simple. In this study, we evaluate the efficiency of algorithms try (TRY), seriation (SER), rapid chain delineation (RCD), recombination counting and ordering (RECORD) and unidirectional growth (UG), as well as the criteria PARF (product of adjacent recombination fractions), SARF (sum of adjacent recombination fractions), SALOD (sum of adjacent LOD scores) and LHMC (likelihood through hidden Markov chains), used with the RIPPLE algorithm for error verification, in the construction of genetic linkage maps. A linkage map of a hypothetical diploid and monoecious plant species was simulated containing one linkage group and 21 markers with fixed distance of 3 cM between them. In all, 700 F(2) populations were randomly simulated with and 400 individuals with different combinations of dominant and co-dominant markers, as well as 10 and 20% of missing data. The simulations showed that, in the presence of co-dominant markers only, any combination of algorithm and criteria may be used, even for a reduced population size. In the case of a smaller proportion of dominant markers, any of the algorithms and criteria (except SALOD) investigated may be used. In the presence of high proportions of dominant markers and smaller samples (around 100)...

Understanding the genetic diversity, spatial genetic structure and mating system at the hierarchical levels of fruits and individuals of a continuous Theobroma cacao population from the Brazilian Amazon

SILVA, C. R. S.; ALBUQUERQUE, P. S. B.; ERVEDOSA, F. R.; MOTA, J. W. S.; FIGUEIRA, A.; SEBBENN, A. M.
Fonte: NATURE PUBLISHING GROUP Publicador: NATURE PUBLISHING GROUP
Tipo: Artigo de Revista Científica
ENG
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Understanding the mating patterns of populations of tree species is a key component of ex situ genetic conservation. In this study, we analysed the genetic diversity, spatial genetic structure (SGS) and mating system at the hierarchical levels of fruits and individuals as well as pollen dispersal patterns in a continuous population of Theobroma cacao in Para State, Brazil. A total of 156 individuals in a 0.56 ha plot were mapped and genotyped for nine microsatellite loci. For the mating system analyses, 50 seeds were collected from nine seed trees by sampling five fruits per tree (10 seeds per fruit). Among the 156 individuals, 127 had unique multilocus genotypes, and the remaining were clones. The population was spatially aggregated; it demonstrated a significant SGS up to 15m that could be attributed primarily to the presence of clones. However, the short seed dispersal distance also contributed to this pattern. Population matings occurred mainly via outcrossing, but selfing was observed in some seed trees, which indicated the presence of individual variation for self-incompatibility. The matings were also correlated, especially within ((r) over cap (p(m)) = 0.607) rather than among the fruits ((r) over cap (p(m)) = 0.099), which suggested that a small number of pollen donors fertilised each fruit. The paternity analysis suggested a high proportion of pollen migration (61.3%)...

Independent fusions and recent origins of sex chromosomes in the evolution and diversification of glass knife fishes (Eigenmannia)

HENNING, F.; MOYSES, C. B.; CALCAGNOTTO, D.; MEYER, A.; ALMEIDA-TOLEDO, L. F. de
Fonte: NATURE PUBLISHING GROUP Publicador: NATURE PUBLISHING GROUP
Tipo: Artigo de Revista Científica
ENG
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The genus Eigenmannia comprises several species groups that display a surprising variety of diploid chromosome numbers and sex-determining systems. In this study, hypotheses regarding phylogenetic relationships and karyotype evolution were investigated using a combination of molecular and cytogenetic methods. Phylogenetic relationships were analyzed for 11 cytotypes based on sequences from five mitochondrial DNA regions. Parsimony-based character mapping of sex chromosomes confirms previous suggestions of multiple origins of sex chromosomes. Molecular cytogenetic analyses involved chromosome painting using probes derived from whole sex chromosomes from two taxa that were hybridized to metaphases of their respective sister cytotypes. These analyses showed that a multiple XY system evolved recently (<7 mya) by fusion. Furthermore, one of the chromosomes that fused to form the neo-Y chromosome is fused independently to another chromosome in the sister cytotype. This may constitute an efficient post-mating barrier and might imply a direct function of sex chromosomes in the speciation processes in Eigenmannia. The other chromosomal sex-determination system investigated is shown to have differentiated by an accumulation of heterochromatin on the X chromosome. This has occurred in the past 0.6 my...

Prevalence of heredity in children born with cleft lip and palate

Von Kostrisch, Lilian Maria; Beluci, Marli Luiz; Medeiros, Maria Natália Leite de; Trettene, Armando dos Santos; Silva, Andressa Sharllene Carneiro da; Trindade Junior, Alceu Sergio; Trindade, Inge Elly Kiemle
Fonte: Universidade de São Paulo, Hospital de Reabilitação de Anomalias Craniofaciais; Bauru Publicador: Universidade de São Paulo, Hospital de Reabilitação de Anomalias Craniofaciais; Bauru
Tipo: Conferência ou Objeto de Conferência
ENG
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Background and purpose: The incidence of heredity as a factor for the occurrence of cleft lip and palate is remarkable, as shown by the high number affected relatives. Therefore, this study investigates the prevalence of heredity on children aged 0 to 3, born with cleft lip and palate, cared for in HRAC. Methods: This is a descriptive, quantitative and retrospective study involving 325 children born with cleft lip and palate, as well as with associated anomalies. Results: Out of the 325 children, 106 (49.23%) had at least one family member who was also born with cleft lip and palate. The greatest incidence of heredity happened among cousins, this relationship being present in 70 cases (21.54%), followed by maternal/paternal uncles (29 cases - 8.92%), parents (14 cases - 4.31%), brothers (7 cases - 2.15%), grandparents (4 cases - 1.23%) and great-grandparents (4 cases - 1.23%). Regarding the type of cleft lip and palate, the most common were cleft palate (105 cases - 32.3%), left unilateral cleft lip and palate (75 cases - 23.07%), bilateral cleft lip and palate (65 cases - 20%) and left unilateral cleft lip (36 cases - 11.07%). Also, Pierre Robin Sequence had its greatest incidence in association with cleft palate on the first child. Conclusions: A positive relationship was found regarding the occurrence of cleft lip and palate among the relatives of the children included in the sample. We emphasize the importance of providing adequate orientation to families...

Desenvolvimento de marcador molecular para resistência a Tobacco mosaic virus e herança da resistência a Meloidogyne incognita raça 3 em tabaco; Development of molecular marker for resistance to Tobacco mosaic virus and heredity of resistance to Meloidogyne incognita race 3 in tobacco

Dalla Valle, Raphaelle Komatsu
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/09/2008 PT
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Este projeto objetivou desenvolver um marcador molecular ligado ao gene de resistência a Tobacco mosaic virus (TMV), em vista da necessidade de aprimorar os métodos de melhoramento de plantas para atender crescentes demandas de produtividade. O outro objetivo deste trabalho foi a avaliação de uma população segregante F2 e de retrocruzamento (RC1F1) a Meloidogyne incognita raça 3, oriunda do cruzamento das cultivares comerciais Coker 176 (C176) e Coker 371 Gold (C371G). Para o desenvolvimento do marcador ligado ao gene de resistência a TMV, o gene N, foram desenvolvidos iniciadores específicos para regiões conservadas (TIR, NBS e LRR) deste gene com base em sua seqüência. Estes iniciadores foram utilizados para amplificar um marcador cuja ligação ao referido gene foi confirmada em 200 indivíduos de população segregante F2 oriunda do cruzamento entre uma linhagem resistente (Coker176) e outra suscetível ao vírus (Kentucky326). A proporção entre o número de plantas resistentes e suscetíveis (154:46) não diferiu estatisticamente daquela esperada no caso de segregação de um gene dominante de resistência, que seria de 3:1. Os resultados indicaram que o marcador e o gene estão proximamente ligados segundo taxa de recombinação...

Análise Bayesiana de ensaios fatoriais 2k usando os princípios dos efeitos esparsos, da hierarquia e da hereditariedade; Bayesian analysis of 2k factorial designs using the sparse eects, hierarchy and heredity principles

Biz, Guilherme
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/01/2010 PT
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No Planejamento de experimentos para o ajuste de modelos polinomiais envolvendo k fatores principais e respectivas interações, e bastante comum a utilização dos fatoriais 2k, 3k ou frações dos mesmos. Para as analises dos resultados desses experimentos, freqüentemente se considera o princípio da hereditariedade, ou seja, uma vez constatada uma interação significativa entre fatores, os fatores que aparecem nesta interação e respectivas interações devem também estar presentes no modelo. Neste trabalho, esse princípio e incorporado diretamente a priori, para um método de seleção de variáveis Bayesiana, seguindo as idéias propostas por Chipman, Hamada e Wu (1997), porem com uma alteração dos valores sugeridos pelos autores para os hiperparâmetros. Essa alteração, proposta neste trabalho, promove uma melhoria considerável na metodologia original. A metodologia e então ilustrada por meio da analise dos resultados de um experimento fatorial para a elaboração de biofilmes de amido originado da ervilha.; In experimental planning for adjustment of polynomials models involving k main factors and their interactions, it is frequent to adopt the 2k, 3k designs or its fractions. Furthermore, it is not unusual, when analysing the results of such experiments...

Os estudos de Avery, Macleod e Mccarty e a idéia do DNA como responsável pela hereditariedade: interpretações historiográficas e apontamentos para o ensino de biologia

Batisteti, Caroline Belotto
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: x, 104 f. : il. + anexo
POR
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Educação para a Ciência - FC; Um dos momentos históricos interessantes no estabelecimento da Biologia Molecular diz respeito às pesquisas realizadas por Avery, MacLeod e McCarty, que indicaram que a natureza química do princípio transformante bacteriano era o DNA. A nosso ver, esse episódio pode ser explorado do ponto de vista histórico, e assim fornecer elementos relevantes para o Ensino de Ciências. Em relação à perspectiva histórica, embora os estudos de Avery e colaboradores sejam atualmente considerados referência no estabelecimento de relações entre DNA e hereditariedade, há na literatura apontamentos sobre a provável não aceitação imediata desses pela comunidade científica da época (1944). Assim, o objetivo da presente pesquisa foi investigar, por meio da análise de fontes primárias, como artigos, documentos e correspondências que envolvem Avery e colaboradores, os motivos para a resistência inicial aos resultados de seus trabalhos. Dentre as razões levantadas, podemos mencionar dúvidas de cunho técnico, que indicavam a presença de proteínas nos preparados utilizados por Avery e colaboradores, a suposta timidez de Avery e a idéia de sua proposta ter sido cientificamente prematura. Outra razão...

Reflexões sobre normalidade e desvio social

Miskolci, Richard
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Artigo de Revista Científica
POR
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O texto expõe como se instituiu uma das oposições fundamentais na organização de nossa sociedade. A partir da reconstrução histórica do processo de normalização chegamos ao movimento sócio-científico da Eugenia e a poderosa teoria da hereditariedade sob o qual ela se assentava. A categoria social dos anormais é analisada como produto de discursos e práticas sociais, portanto, historicamente. Por fim, apresentamos algumas considerações sobre a polaridade normalidade e patologia na sociedade contemporânea e a persistência de teorias que visam naturalizar diferenças individuais e desigualdades sociais.; The article shows how our society has created one of the oppositions that structures it. It starts with a historic reconstruction of the normalization process to introduce the powerful social-scientific movement of Eugenics and the heredity theory behind it. We analyze the social category of the abnormal as a product of discourses and social practices, in short, historically. The article also presents few considerations about the polarity normality and pathology in contemporary society. The focus is on the persistence of the theories that naturalize individual differences and social disparities.

An approach for understanding the heredity of two quality traits (head color and tightness) in globe artichoke (Cynara scolymus L.)

Cravero,Vanina Pamela; Picardi,Liliana Amelia; Cointry,Enrique Luis
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2005 EN
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The inheritance of head color and tightness in globe artichoke was studied utilizing crosses between inbreed lines and between clones and self-pollinated clones from different genetic origins. These genetic materials were sowed in a completely randomized design with 20 plants per plot and genotype. Globe artichoke heads were classified into three colors (purple-green, purple and green) and three head tightness types (compact, fairly compact and soft) and the segregating ratios for these traits tested in each offspring using the chi-square test. Crosses between green and purple inbreed lines produced only purple-green heads but F2 generation segregated at a purple-green:purple:green ratio of 9:3:4. The self-pollinated compact head clones produced a compact head:fairly compact head:soft head ratio of 12:3:1. The remaining crosses between lines and among clones and backcrosses verified these ratios. These results suggest that two loci with a simple recessive epistasis are involved in the inheritance of head color and that two loci with simple dominant epistasis are involved in the expression of the different head tightness types. The inheritance models proposed here could be helpful in predicting the appearance of artichoke heads if breeders need to obtain hybrid seeds for a desirable phenotype.

Prolonged exclusive breast feeding and heredity as determinants in infantile atopy.

Savilahti, E; Tainio, V M; Salmenperä, L; Siimes, M A; Perheentupa, J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1987 EN
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We followed 183 infants for two years, 31 of whom were breast fed less than three and a half months (median 70 days; short breast feeding group) and a further 31 of whom were exclusively breast fed for more than nine months (long breast feeding group). We assessed heredity for atopy, number of infections, and duration of breast feeding as determinants of atopy. During the first year of life 14 infants has signs of atopy. During the second year parents reported signs of atopy in a further 31. Heredity was the only significant predictor of atopy. Atopy was seen in 33% of infants with a positive heredity and in 16% without family history for atopy. The duration of breast feeding affected the incidence of atopy only among the infants without family history for atopy: fewer in the short breast feeding group (1/18) had atopy than in the long breast feeding group (5/13). Duration of breast feeding did not associate with incidence of respiratory infections. Diarrhoea was more common in the short breast feeding group than in the long breast feeding group during the first year of life. We conclude that prolonging exclusive breast feeding from the median of 70 days to nine months did not contribute to the prevention of infantile atopy and respiratory tract infections.

Influence of atopic heredity on IL-4-, IL-12- and IFN-γ-producing cells in in vitro activated cord blood mononuclear cells

Gabrielsson, S; Söderlund, A; Nilsson, C; Lilja, G; Nordlund, M; Troye-Blomberg, M
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /12/2001 EN
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Several reports have claimed that there is a greater risk for a child with an atopic mother to develop allergy as compared to a child with an atopic father. This suggests that the fetal environment during pregnancy might be of importance for the development of atopic disease. Both proliferative and cytokine responses have been detected in cord blood mononuclear cells (CBMC) after stimulation with allergens, suggesting allergen priming already in utero. The aim of this study was to investigate whether the atopic status of the mother influences cytokine production by CBMC. We compared interleukin (IL)-4, IL-12 and interferon (IFN)-γ-producing CBMC from children with double atopic heredity (dh), maternal atopic heredity only (mh) or no atopic heredity (nh). CBMC were stimulated in vitro with allergens (birch, ovalbumin and cat), phytohaemagglutinin (PHA) or purified protein derivative (PPD) and cytokine-producing cells were measured by the enzyme-linked immunospot assay. In response to PHA, the frequency of IL-4-producing cells, as well as the ratio of IL-4/IFN-γ-producing cells, were significantly higher in the dh group compared to the nh group. High numbers of IL-12-producing cells in response to allergens were detected, significantly highest in the nh group...

Synthetic genetic polymers capable of heredity and evolution

Pinheiro, Vitor B.; Taylor, Alexander I.; Cozens, Christopher; Abramov, Mikhail; Renders, Marleen; Zhang, Su; Chaput, John C.; Wengel, Jesper; Peak-Chew, Sew-Yeu; McLaughlin, Stephen H.; Herdewijn, Piet; Holliger, Philipp
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 20/04/2012 EN
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Genetic information storage and processing rely on just two polymers, DNA and RNA. Whether their role reflects evolutionary history or fundamental functional constraints is unknown. Using polymerase evolution and design, we show that genetic information can be stored in and recovered from six alternative genetic polymers (XNAs) based on simple nucleic acid architectures not found in nature. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and for folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage.

Kinetic Origin of Heredity in a Replicating System with a Catalytic Network

Kaneko, K.
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Publicado em /12/2002 EN
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The origin of heredity is studied as a recursive state in a replicatingprotocell consisting of many molecule species in mutually catalyzingreaction networks. Protocells divide when the number of molecules, increasing due to replication, exceeds a certain threshold. We study how the chemicals in a catalytic network can form recursive production states in the presence of errors in the replication process. Depending on the balance between the total number of molecules in a cell and the number of molecule species, we have found three phases; a phase without a recursive production state, a phase with itinerancy over a few recursive states, and a phase with fixedrecursive production states. Heredity is realized in the latter two phaseswhere molecule species that are population-wise in the minority are preserved and control the phenotype of the cell. It is shown that evolvability is realized in the itinerancy phase, where a change in the number of minority molecules controls a change of the chemical state.

The Association of Beliefs About Heredity with Preventive and Interpersonal Behaviors in Communities Affected by Podoconiosis in Rural Ethiopia

Ayode, Desta; McBride, Colleen M.; de Heer, Hendrik; Watanabe, Emi; Gebreyesus, Tsega; Tadele, Getnet; Tora, Abebayehu; Davey, Gail
Fonte: The American Society of Tropical Medicine and Hygiene Publicador: The American Society of Tropical Medicine and Hygiene
Tipo: Artigo de Revista Científica
Publicado em 03/10/2012 EN
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Little is known about how beliefs about heredity as a cause of health conditions might influence preventive and interpersonal behaviors among those individuals with low genetic and health literacy. We explored causal beliefs about podoconiosis, a neglected tropical disease (NTD) endemic in Ethiopia. Podoconiosis clusters in families but can be prevented if individuals at genetically high risk wear shoes consistently. Adults (N = 242) from four rural Ethiopian communities participated in qualitative assessments of beliefs about the causes of podoconiosis. Heredity was commonly mentioned, with heredity being perceived as (1) the sole cause of podoconiosis, (2) not a causal factor, or (3) one of multiple causes. These beliefs influenced the perceived controllability of podoconiosis and in turn, whether individuals endorsed preventive and interpersonal stigmatizing behaviors. Culturally informed education programs that increase the perceived controllability of stigmatized hereditary health conditions like podoconiosis have promise for increasing preventive behaviors and reducing interpersonal stigma.

RNA–Mediated Epigenetic Heredity Requires the Cytosine Methyltransferase Dnmt2

Kiani, Jafar; Grandjean, Valérie; Liebers, Reinhard; Tuorto, Francesca; Ghanbarian, Hossein; Lyko, Frank; Cuzin, François; Rassoulzadegan, Minoo
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
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RNA–mediated transmission of phenotypes is an important way to explain non-Mendelian heredity. We have previously shown that small non-coding RNAs can induce hereditary epigenetic variations in mice and act as the transgenerational signalling molecules. Two prominent examples for these paramutations include the epigenetic modulation of the Kit gene, resulting in altered fur coloration, and the modulation of the Sox9 gene, resulting in an overgrowth phenotype. We now report that expression of the Dnmt2 RNA methyltransferase is required for the establishment and hereditary maintenance of both paramutations. Our data show that the Kit paramutant phenotype was not transmitted to the progeny of Dnmt2−/− mice and that the Sox9 paramutation was also not established in Dnmt2−/− embryos. Similarly, RNA from Dnmt2-negative Kit heterozygotes did not induce the paramutant phenotype when microinjected into Dnmt2-deficient fertilized eggs and microinjection of the miR-124 microRNA failed to induce the characteristic giant phenotype. In agreement with an RNA–mediated mechanism of inheritance, no change was observed in the DNA methylation profiles of the Kit locus between the wild-type and paramutant mice. RNA bisulfite sequencing confirmed Dnmt2-dependent tRNA methylation in mouse sperm and also indicated Dnmt2-dependent cytosine methylation in Kit RNA in paramutant embryos. Together...

The role of heredity in pterygium development

Anguria, Peter; Kitinya, James; Ntuli, Sam; Carmichael, Trevor
Fonte: International Journal of Ophthalmology Press Publicador: International Journal of Ophthalmology Press
Tipo: Artigo de Revista Científica
Publicado em 18/06/2014 EN
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Several risk factors, which include heredity, ultra-violet (UV) light and chronic inflammation, contribute to pterygium development. However, there is no report integrating these factors in the pathogenesis of pterygium. The aim of this review is to describe the connection between heredity, UV, and inflammation in pterygium development. Existing reports indicate that sunlight exposure is the main factor in pterygium occurrence by inducing growth factor production or chronic inflammation or DNA damage. Heredity may be a factor. Our studies on factors in pterygium occurrence and recurrence identify that heredity is crucial for pterygium to develop, and that sunlight is only a trigger, and that chronic inflammation promotes pterygium enlargement. We propose that genetic factors may interfere with the control of fibrovascular proliferation while UV light or (sunlight) most likely only triggers pterygium development by inducing growth factors which promote vibrant fibrovascular proliferation in predisposed individuals. It also just triggers inflammation and collagenolysis, which may be promoters of the enlargement of the fibrovascular mass. Pterygium probably occurs in the presence of exuberant collagen production and profuse neovascularisation.

Epigenetic heredity of human height

Simeone, Pasquale; Alberti, Saverio
Fonte: Wiley Periodicals, Inc. Publicador: Wiley Periodicals, Inc.
Tipo: Artigo de Revista Científica
Publicado em 24/06/2014 EN
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Genome‐wide SNP analyses have identified genomic variants associated with adult human height. However, these only explain a fraction of human height variation, suggesting that significant information might have been systematically missed by SNP sequencing analysis. A candidate for such non‐SNP‐linked information is DNA methylation. Regulation by DNA methylation requires the presence of CpG islands in the promoter region of candidate genes. Seventy two of 87 (82.8%), height‐associated genes were indeed found to contain CpG islands upstream of the transcription start site (USC CpG island searcher; validation: UCSC Genome Browser), which were shown to correlate with gene regulation. Consistent with this, DNA hypermethylation modules were detected in 42 height‐associated genes, versus 1.5% of control genes (P = 8.0199e−17), as were dynamic methylation changes and gene imprinting. Epigenetic heredity thus appears to be a determinant of adult human height. Major findings in mouse models and in human genetic diseases support this model. Modulation of DNA methylation are candidate to mediate environmental influence on epigenetic traits. This may help to explain progressive height changes over multiple generations, through trans‐generational heredity of progressive DNA methylation patterns.

STUDIES ON THE RELATION BETWEEN TUMOR SUSCEPTIBILITY AND HEREDITY : II. THE INCIDENCE OF TAR TUMORS IN STRAINS OF MICE HAVING A DIFFERING INCIDENCE OF SPONTANEOUS GROWTHS.

Lynch, Clara J.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 30/11/1925 EN
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1. Two strains of mice, one with a high, the other with a comparatively low incidence of spontaneous tumors of the mammary gland, when painted between the shoulders with coal tar extract developed tar tumors with about practically identical frequency. Possibly this result was to have been expected. If tumors of certain organs or tissues are specific in heredity, a conception for which there is some evidence, then assuredly a high degree of incidence for one tissue, as for example the mammary gland, does not necessarily mean a high incidence for another tissue, such as the skin, when subjected to tarring. To test the influence of heredity on the response of the skin to tar painting it would be best to employ strains of animals exhibiting differences in the incidence of spontaneous cancer of the skin. Unfortunately no such material was available. We can state on the basis of our experiments only that no hereditary differences in the response of the skin to tar painting were demonstrable in two strains of mice manifesting markedly different percentage incidences for spontaneous mammary growths. It is possible, of course, that the natural differences in the two strains may have been wiped out by the tar treatment. Such a view is suggested by the result of other work in this laboratory which has shown that tar painting increases markedly the incidence of tumors of the lung and destroys the resistance to transplantable tumors (unpublished work). 2. Mice from which spontaneous mammary tumors had been removed were treated with tar. The percentage incidence of the resulting tar tumors was similar to that met with in the controls...

On S.N. Bernstein's derivation of Mendel's Law and 'rediscovery' of the Hardy-Weinberg distribution

Stark,Alan; Seneta,Eugene
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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Around 1923 the soon-to-be famous Soviet mathematician and probabilist Sergei N. Bernstein started to construct an axiomatic foundation of a theory of heredity. He began from the premise of stationarity (constancy of type proportions) from the first generation of offspring. This led him to derive the Mendelian coefficients of heredity. It appears that he had no direct influence on the subsequent development of population genetics. A basic assumption of Bernstein was that parents coupled randomly to produce offspring. This paper shows that a simple model of non-random mating, which nevertheless embodies a feature of the Hardy-Weinberg Law, can produce Mendelian coefficients of heredity while maintaining the population distribution. How W. Johannsen's monograph influenced Bernstein is discussed.

Kinetic Origin of Heredity in a Replicating System with a Catalytic Network

Kaneko, Kunihiko
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/03/2002
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The origin of heredity is studied as a recursive state in a replicating proto-cell consisting of many molecule species in mutually catalyzing reaction networks. Protocells divide when the number of molecules, increasing due to replication, exceeds a certain threshold. We study how the chemicals in a catalytic network can form recursive production states in the presence of errors in the replication process. Depending on the balance between the total number of molecules in a cell and the number of molecule species, we have found three phases; a phase without a recursive production state, a phase with itinerancy over a few recursive states, and a phase with fixed recursive production states. Heredity is realized in the latter two phases where molecule species that are population-wise in the minority are preserved and control the phenotype of the cell. It is shown that evolvability is realized in the itinerancy phase, where a change in the number of minority molecules controls a change of the chemical state.; Comment: 15 pages, to appear in J Biol. Phys