Differential expression patterns of myogenic regulatory factors in the postnatal longissimus dorsi muscle of Jeju Native Pig and Berkshire breeds along with their co-expression with Pax7

BACKGROUND: Myogenic regulatory factors (MRFs) such as MyoD, Myf6 and Myf5 play a vital role in the growth and development of muscles. Jeju Native Pig (JNP) is the top ranker in Korea amongst the indigenous livestock reared for meat purpose. Few studies covering transcript abundance of the MRFs and related to their co-expression with Pax7 in JNP have been conducted. Despite having better quality pork, JNP does not have a comparative growth rate with respect to western breeds. Therefore, the present study was designed with the objective to study the relative transcript levels of MRFs in the postnatal myogenesis of longissimus dorsi muscles in JNP and Berkshire breeds. RESULTS: Relative transcript levels were analyzed by qRT-PCR and blot expression analysis through Western blotting. Immunocytochemistry was performed to analyze their expressions at cellular levels. ToppCluster aided in the analysis of gene ontology of biological processes. The quantitative transcript levels of MyoD and Pax7 were significantly (P < 0.05) higher in Berkshire than in JNP. Myotube formation was observed under the co-expression of MyoD and Pax7. ToppCluster helped in the understanding of the linking of biological processes of the MRFs with the different signaling pathways. MyBPH had significantly (P < 0.05) high transcript levels during the chosen age groups in JNP than Berkshire. CONCLUSIONS: The current study can be helpful in understanding the genetic basis for myogenesis in postnatal stage. Moreover, it can act as stepping stone for the identification of marker genes related to body growth and meat quality in JNP.

Influência de fatores abióticos sob miogênese de peixes teleósteos / Abiotic influence in myogenesis of teleost fishes / Influencia abiótica en la miogénesis de peces teleósteos

Resumo Os peixes teleósteos são organismos que, geralmente, apresentam limite de crescimento indeterminado e estão presentes em diferentes biomas com diversas características ambientais. Os teleósteos possuem até 80% de sua composição corporal formado por tecido muscular, composto por fibras musculares e células satélites indiferenciadas, formando um tecido muscular complexo cuja forma é muito variada em função das espécies que compõem este grupo de animais. Um ponto importante a ser considerado é que o crescimento muscular dos peixes é influenciado pelas condições ambientais em que estão inseridos. Esta influência ocorre à nível molecular afetando a transcrição e funcionalidade de diferentes transcritos relacionados à miogênese em diferentes fases do desenvolvimento dos peixes. Esta revisão tem o objetivo de discutir alguns dos pontos chave sobre a influência dos fatores ambientais sobre o desenvolvimento e crescimento muscular dos peixes.

Abstract Teleost fish are organisms that generally show an indeterminate growth limit and are present in different biomes with different environmental conditions. Approximately up to 80% of the body composition of fish is formed by muscle tissue. Muscle tissue is composed of muscle fibers and undifferentiated satellite cells, forming a complex tissue that shows a widely varied shape depending on the species which form this group of animals. An important point to be considered is that the muscle growth of the fish is influenced by the environmental conditions in which they are inserted. This influence occurs at the molecular level, affecting the transcription and functionality of different transcripts related to myogenesis at different stages of fish development. This review aims to discuss some of the key aspects about the influence of environmental factors on the development and muscle growth of teleost fish.

Resumen Los peces teleósteos son organismos que generalmente tienen un límite de crecimiento indeterminado y están presentes en diferentes biomas con diferentes características ambientales. Los teleósteos poseen hasta el 80% de su composición corporal compuesta de tejido muscular, compuesto por fibras musculares y células satélite indiferenciadas, formando un tejido muscular complejo cuya forma es muy variada dependiendo de las especies que componen este grupo de animales. Un punto importante por considerar es que el crecimiento muscular de los peces está influenciado por las condiciones ambientales en que están inseridos. Esta influencia ocurre a nivel molecular, afectando la transcripción y la funcionalidad de diferentes transcripciones relacionadas con la miogénesis en diferentes etapas del desarrollo de los peces. Esta revisión tiene como objetivo discutir algunos de los puntos clave sobre la influencia de los factores ambientales en el desarrollo y el crecimiento muscular de los peces.

Mitochondrial dysfunction reduces the activity of KIR2.1 K⁺ channel in myoblasts via impaired oxidative phosphorylation

Myoblast fusion depends on mitochondrial integrity and intracellular Ca²⁺ signaling regulated by various ion channels. In this study, we investigated the ionic currents associated with [Ca²⁺]i regulation in normal and mitochondrial DNA-depleted (ρ0) L6 myoblasts. The ρ0 myoblasts showed impaired myotube formation. The inwardly rectifying K⁺ current (I(Kir)) was largely decreased with reduced expression of KIR2.1, whereas the voltage-operated Ca²⁺ channel and Ca²⁺-activated K⁺ channel currents were intact. Sustained inhibition of mitochondrial electron transport by antimycin A treatment (24 h) also decreased the I(Kir). The ρ0 myoblasts showed depolarized resting membrane potential and higher basal [Ca²⁺]ᵢ. Our results demonstrated the specific downregulation of I(Kir) by dysfunctional mitochondria. The resultant depolarization and altered Ca²⁺ signaling might be associated with impaired myoblast fusion in ρ0 myoblasts.

The expression of gene ANKRD1 correlates with hypoxia status in muscle biopsies of treatment-näive adult dermatomyositis / A expressão do gene ankrd1 correlaciona-se com o status de biópsias musculares em adultos portadores de dermatomiosite sem exposição prévia a tratamento

OBJECTIVES. The ANKRD1 gene codes for the ankyrin repeat domain containing protein 1 and has an important role in myogenesis and possibly also in angiogenesis. Microvasculopathy is a cornerstone and an early pathological marker of change in dermatomyositis, leading to hypoxia and muscle perifascicular atrophy. These alterations could upregulate genes involved in myogenesis and angiogenesis such as ANKRD1. Therefore, we analyzed ANKRD1 expression in muscle biopsies of dermatomyositis and correlated with other hypoxia parameters and with histological changes. METHODS. Total RNA was extracted from frozen muscle biopsies samples of 29 dermatomyositis patients. A control group consisted of 20 muscle biopsies from adult patients with non-inflammatory myopathy diseases. The gene coding for hypoxia-inducible factor 1, alpha subunit (HIF1A), was analyzed to estimate the degree of hypoxia. ANKRD1 and HIF1A transcript expression levels were determined by quantitative real time PCR. RESULTS. Significantly higher ANKRD1 and HIF1A expression levels were observed in dermatomyositis relative to the control group (P<0.001, both genes). In addition, ANKRD1 and HIF1A were coexpressed (r=0.703, P=0.001) and their expression levels correlated positively to perifascicular atrophy (r=0.420, P=0.023 and r=0.404, P=0.030, respectively). CONCLUSIONS. Our results demonstrate ANKRD1 overexpression in dermatomyositis correlated to HIF1A expression and perifascicular atrophy. ANKRD1 involvement in myogenesis and angiogenesis mechanisms indicates that further investigation is worthwhile.

OBJETIVOS: ANKRD1 codifica "ankyrin repeat domain containing protein 1" e tem um papel importante na miogênese e possivelmente também na angiogênese. Microvasculopatia é considerada como um ponto central e uma alteração patológica precoce na dermatomiosite (DM), levando à hipóxia e à atrofia perifascicular muscular. Estas alterações poderiam estimular genes envolvidos na miogênese e angiogênese como ANKRD1. Portanto, analisamos a expressão de ANKRD1 em biópsias musculares de DM e correlacionamos com outros parâmetros de hipóxia e alterações histológicas. MÉTODOS: O RNA total foi extraído de biópsias de músculos congelados de 29 pacientes com DM. Como grupo controle, foram usadas 20 biópsias de músculo de pacientes adultos com miopatia não-inflamatória. O gene que codifica a subunidade alfa do fator 1 induzido por hipóxia (HIF1A) foi analisado para estimar o grau de hipóxia. Os níveis de expressão dos transcritos ANKRD1 e HIF1A foram determinados por PCR quantitativa em tempo real. RESULTADOS: Níveis aumentados de expressões de ANKRD1 e HIF1A foram observados em DM quando comparados ao grupo controle (P<0,001, ambos os genes). Além disso, ANKRD1 e HIF1A apresentaram coexpressão (r=0,703, P=0,001) e seus níveis de expressão correlacionaram-se também positivamente com atrofia perifascicular (r=0,420, P=0,023 e r=0,404, P=0,030, respectivamente). CONCLUSÕES: Nossos resultados demonstraram aumento de expressão de ANKRD1 na DM, que correlacionou com a expressão de HIF1A e atrofia perifascicular. Investigações adicionais do envolvimento de ANKRD1 no mecanismo de miogênese e angiogênese devem ser realizadas.

The evolution of the denervated gastrocnemii and it's miR-206 and myoD expression during skeletal muscle atrophy in rats / 中华显微外科杂志

Objective To investigate the expression pattern of skeletal muscle specific miR-206,myogenesis related myoD which change with time in dcnervated muscle atrophy rats.Methods From June,2015 to January,2016,40 SPF sprague-dawley rats were equally classified into 5 groups randomly according to standard settled before,5 groups were separately defined as denervated 0d group,denervated 1d group,denervated 7d group,denervated 14d group,and denervated 28d group.Each group contained 8 rats.The rats atrophy models were established by cutting sciatic never on left side.According to the different denervated time,the gastrocnemii on both sides were obtained under anesthesia,respectively.The wet weight ratio of two compared gastrocnemii were measured,and the gastrocnemii transection was observed by HE stain,measured the expression of myoD protein by western blot,obtained the expression of miR-206,myoD mRNA by qPCR.Results According to our study on rats denervated atrophy models,the wet ratio of compared gastrocnemius would decrease rapidly,by HE stain,decease of cross sectional area in muscle fiber was observed as well as degeneration.Collagen fibers hyperplasia appeared and increased with time change.Wet ratio and transaction aera ratio of group Od,1d,7d,14d,28d were 0.99±0.04,0.92±0.07,0.68±0.11,0.39±0.06,0.27±0.07 and 0.99±0.02,0.96±0.04,0.51±0.09,0.34±0.08,0.23±０.03 respectively,difference between experimental groups and control group were statistically significant (P＜ 0.05),the differences between each experimental groups were also statistically significant (P＜ 0.05).After qPCR test of miR-206,myoD mRNA expression,it was found that their expression patterns were similar,miR-206,myoD mRNA increased at first and would reach the expression peak at the 7 th day,after that their contents decreased but still higher at the 14th day when compared with that at the 1 st day.Their expression of group 0d,1 d,7d,14d,28d were 0.24±0.06,0.34±0.04,0.68±0.04,0.49± 0.07,0.25±0.03 and 0.41 ±0.06,0.49±0.09,0.93±0.06,0.66±0.03,0.39±0.04,respectively.All experimental groups were statistically significant different when compared with 0d group except 1d group (P＜ 0.05),the differences between each experimental groups were also statistically significant(P＜ 0.05).The protein expression of myoD was also measured by western blot test,which showed nearly the same expression pattern as the mRNA expression pattern.After injury,the protein expression increased and reached the expression peak at the 7th day.The relative expression of myoD of group 0d,1d,7d,14d,28d measured by grey ratio were 1.03±0.05,1.06±0.06,1.42±0.10,0.66±0.13,0.24±0.07,respectively.The difference between experimental groups and control group were statistically significant (P ＜ 0.05),the differences between each experimental groups were statistically significant (P ＜ 0.05) as well.Conclusion The degree of muscle denervation atrophy was related to the denervated duration in rats.The expression regulation of miR-206 and myoD in gastrocnemius was similar during the muscle denervation atrophy,which suggesting having internal relationship between miR-206 and myoD.

Histamine H3 receptor inhibited electrically evoked cytoplasmic calcium in differentiated skeletal C2C12 myoblasts / 中国病理生理杂志

AIM:To explore the expression and possible function of histamine H3 receptor (H3R) in striated myogenesis and the differentiated C2C12 cells.METHODS: H3R and myogenesis late marker myosin heavy chain (MHC) were detected at mRNA and protein levels during C2C12 myogenesis.H3R antagonist ciproxifan was added and the expression of the myogenesis early marker desmin, intermediate markers myogenin and MHC was detected.Differentia-ted myoblasts were loaded with Fluo-4 calcium indicator dye and the effect of R-( a)-methylhistamine ( RMeHA) on the cy-toplasmic calcium concentration was determined under the 200 mA electrical stimulation.RESULTS: The expression of H3R and MHC was increased during myogenesis.Ciproxifan incubation had no influence on the 3 striated myogenesis mar-kers (P>0.05).In C2C12 myoblasts, RMeHA (10 nmol/L~100 μmol/L) effectively diminished cytoplasmic calcium peak when the cells were electrically paced (P<0.05).The best inhibitory effect of RMeHA was observed at dose of 100 nM for 10 min and 20 min, which was higher than that for 5 min (P<0.05).CONCLUSION: H3R might have little effect on the myogenic differentiation, but diminishes cytoplasmic calcium peak of the differentiated myoblasts under electri-cal stimulation.

Expressions of histamine receptors in pediatric mid-urethral striated muscles and mouse striated myogenesis / 中华实用儿科临床杂志

Objective To explore the expressions of histamine receptor subtypes (H1, H2, H3, H4 receptor) in children's mid-urethral striated muscles and during mouse C2C12 striated myogenesis.Methods Children's mid-urethral striated muscle samples were paraffin embedded and tissue sections were made, then immunohistochemical staining was used to check H1, H2, H3, H4 receptors.C2C12 myogenesis was induced, the early differentiation early markers of desmin, middle marker of myogenin, late marker of myosin heavy chain and histamine 4 receptor subtype mRNA were checked by quantitative real-time polymerase chain reaction.Immunofluorescence staining was done to check 3 differentiation markers and histamine H3 receptor protein.Results During myogenesis, the expression of desmin mRNA in the differentiation of 2,4,6 days were 12,68,60 times as many as that of the undifferentiated myoblasts;the expression of myogenin mRNA in the differentiation of 2,4,6 days were 631,1 408,914 times as many as that of the undifferentiated myoblasts;the expression of myosin heavy chain mRNA in the differentiation of 2,4,6 days were 7 718,9 448,286 288 times as many as that of the undifferentiated myoblasts.The expression level of H1 receptor mRNA in the differentiation of 6 days was about 25％ to undifferentiated cells;the expression of H2 receptor mRNA in undifferentiated cells and differentiated cells groups had no significant difference (F =1.47, P ＞ 0.05);the expression of H3 receptor mRNA in the differentiation of 2,4,6 days was 28,103,198 times to undifferentiated cells;H4 receptor mRNA was not detected.In immunofluorescence staining, H3 receptor protein staining intensity increased with the differentiation.Immunohistochemistry of pediatric urethral striated staining indicated that H1, H2, H3 receptor staining was positive,H1 receptor showed strong positive staining, H3 receptor moderate positive staining,and H2 receptor showed weak positive staining.Conclusions Histamine receptor subtypes of H1 receptor, H2 receptor and H3 receptor were found during mouse striated myogenesis and in the children's mid-urethral striated muscles.The increasing expression of H3R with myogenesis might indicate it plays a role in mature striated muscle cells.

Endothelial Dysfunction and Cardiovascular Disease: Critical Target for Cell-Based Therapies.

This review briefly summarizes how cell-based therapeutic interventions are being developed and applied to treat endothelial dysfunction (ED) as a critical clinical target. ED directly contributes to the onset and prognosis for all of the major forms of cardiovascular diseases, including atherosclerosis, pulmonary artery hypertension, peripheral hypertension, stroke, myocardial infarction and congestive heart failure. Current pharmacological therapies used to treat ED are discussed and compared with newer strategies employing endothelial progenitor cells (EPCs) and other stem cells for tissue repair/regeneration therapies. Cell-based therapies to treat ED are still largely experimental but they are emerging in the clinic and represent a promising avenue for new interventional options to combat cardiovascular disease and improve patient outcomes.

Cardioimplante autólogo de células madre de médula ósea en territorios miocárdicos necróticos / Cardiac implant autologous bone marrow stem cells in necrotic myocardial territories / Implante de células-tronco cardíacas autólogas da medula óssea em áreas de necrose miocárdica

Introducción. El concepto clásico de que el corazón era un órgano no regenerativo ha cambiado en la actualidad, por el de ser un órgano en regeneración continua, constituyendo una evidencia sólida de que el tejido cardíaco se encuentra en un proceso continuo de crecimiento, muerte y renovación. Material y método. Se protocolizaron doce pacientes desde el 29 de Mayo de 2004 al 30 de Agosto de 2007. Se excluyeron cinco y de los 7 restantes, cinco fueron evaluados. Se extrajeron por punción de la cresta ilíaca de cada paciente en condiciones estériles 60 cm³ de médula ósea, y se obtuvieron por sedimentación células madre que se identificaron por inmunomarcación con anticuerpo monoclonal anti-CD34 en citómetro de flujo.La evaluación de la viabilidad miocárdica pre y post implante se realizó con PET-FDG. Finalizadas las anastomosis, se implantaron las células madre directamente por punción en territorios no viables. Resultados. Se expresan como porcentajes (variables categóricas) y como media con su desvío estándar (variables continuas). Para evaluar significancia en el cambio de la fracción de eyección se utilizó el test de Wilcoxon. Se consideró significativa una p<0,05. De los 15 segmentos no viables, se implantaron 11 (73%) y se recuperaron 4 (36,36%). La fracción de eyección de ventrículo izquierdo media evaluada por SPECT gatillado fue del 30,2±4,9% en el pre procedimiento y del 34,8±9,5% en el post procedimiento, la mejoría fue de 4,6 puntos (p=0,34), el 60% de los pacientes mejoraron. Conclusiones. Hay una relación entre la concentración de CD34+ (que fue baja: 0,76% de media) y la viabilidad miocárdica. La aparición de viabilidad miocárdica en el 36,36% de los segmentos implantados fue el hallazgo más importante. El método demostró ser seguro, efectivo y reproducible. La utilización de PET-FDG en todos los pacientes para evaluación de viabilidad pre y post implante como método gold standard fue evidencia de regeneración tisular.

Introduction. Currently, the classical concept that the heart was a non-regenerative organ has changed, by being an organ in continuous regeneration constitute strong evidence that cardiac tissue is in a continuous process of growth, death and renewal. Materials and methods. Twelve patients were protocolized from May 29, 2004 to August 30, 2007. We excluded five. Of the 7 remaining, five were evaluated by puncturing of the iliac crest from each patient under sterile conditions 60 cm³ extracted bone marrow and stem cells were obtained by sedimentation and identified by immunostaining with anti-CD34 monoclonal antibody in the flow cytometer. The assessment of myocardial viability before and after implantation was performed with PET-FDG. After the completion anastomosis, the stem cells were implanted directly by puncture nonviable territories. Results. They are expressed as percentages (categorical variables) and as mean with standard deviation (continuous variables). To assess significance in changing ejection fraction was used the Wilcoxon test. Was considered significant at p <0.05. We implanted 11 (73%) of the 15 segments non-viable were recovered 4 (36.36%). The ejection fraction of the left ventricle assessed by SPECT triggered average was 30.2 ± 4.9% in the pre procedure and 34.8 ± 9.5% in the post process, the improvement was 4.6 points (p=0.34), 60% of the patients improved. Conclusions. There is a relationship between the concentration of CD34 + (which was low 0.76% on average) and myocardial viability. The appearance of myocardial viability in 36.36% of the implanted segments was the most important finding. The method proved to be safe, effective and reproducible. The use of PET-FDG in all patients for viability assessment before and after implantation as gold standard method was evidence of tissue regeneration.

Introdução.O conceito clássico que o coração era um órgão não regenerativo mudou agora, por ser um órgão em regeneração contínua constituem fortes provas de que o tecido cardíaco é um processo contínuo de crescimento, morte e renovação. Material e método.Doze pacientes foram incluídos em um protocolo de pesquisa a partir de 29 de Maio de 2004 a 30 de Agosto de 2007. Cinco excluídos. Dos restantes sete, cinco foram avaliados por punção da crista ilíaca do paciente em condições estéreis, foram obtidos 60 cm³ de medula óssea. As células-tronco foram recolhidos por sedimentação e identificados por imunomarcação com o anticorpo monoclonal anti-CD34 no citómetro de fluxo. A avaliação da viabilidade miocárdica antes e após a implantação foi realizada com PET- FDG. Após o término das anastomoses, as células-tronco foram implantadas diretamente por punção em territórios não viáveis. Resultados. Eles são expressos como porcentagens (variáveis categóricas) e média com desvio padrão (variáveis contínuas). Para avaliar a importância na mudança de fração de ejeção foi utilizado o teste de Wilcoxon. Considerou-se significante p<0,05. Dos 15 segmentos não viáveis,foram implantados 11 (73%) e quatro (36,36%) foram recuperados. A fração de ejeção do ventrículo esquerdo avaliada pelo SPECT foi de 30,2±4,9% na fase pré e de 34,8±9,5% no processo de pós, a melhoria foi de 4,6 pontos (p=0,34), 60% dos pacientes melhoraram. Conclusões. Existe uma relação entre a concentração de células CD34+ (baixa: 0,76 %, em média) e a viabilidade do miocárdio. A incidência da viabilidade do miocárdio em 36,36% dos segmentos implantados foi o achado mais importante. O método demonstrou ser seguro, eficaz e reprodutível. O uso de PET-FDG em todos os pacientes para avaliação de viabilidade, antes e depois da implantação como método padrão-ouro, foi evidência de regeneração de tecidos.

Diferenciación en cardiomiocitos a partir de células madre embrionarias humanas / Differentiation of Human Embryonic Stem Cells into Cardiomyocytes

Introducción Las células madre son motivo de intensa investigación debido a la posibilidad de su utilización en el tratamiento de numerosas enfermedades, en particular las cardiovasculares. La diferenciación de células madre embrionarias humanas en cardiomiocitos se ha realizado exitosamente in vitro. Se han establecido métodos de cultivo y diferenciación, señales involucradas en la cardiogénesis y los cardiomiocitos generados se han utilizado en modelos de regeneración miocárdica. Sin embargo, aún quedan muchos interrogantes que se están investigando activamente. Objetivo Desarrollar una metodología que permita el cultivo de células embrionarias y su diferenciación en cardiomiocitos. Material y métodos Se utilizaron cuatro líneas de células madre embrionarias humanas. Se cultivaron y diferenciaron a través de los métodos publicados previamente en la bibliografía. El estado indiferenciado y la diferenciación en cardiomiocitos se verificaron por medio de inmunomarcación fluorescente y RT-PCR. Resultados La metodología utilizada permitió cultivar las células y mantenerlas en estado indiferenciado. Aunque con eficacia dispar, se logró la diferenciación en cardiomiocitos de las cuatro líneas celulares utilizadas. La confirmación se realizó por medio de la expresión de factores de transcripción miocárdicos y proteínas estructurales cardíacas. Conclusiones El cultivo y la diferenciación de células madre embrionarias humanas fue posible en nuestro sistema. Estos resultados preliminares nos impulsan a continuar y a desarrollar nuestros métodos con células pluripotentes inducidas.

Background The role of stem cells in the treatment of several conditions, especially heart diseases, is under permanent investigation. Human embryonic stem cells have been successfully differentiated in vitro into cardiomyocytes. Methods of cell culture and cardiomyocyte differentiation are well established; signals regulating cardiogenesis have been identified and the cardiomyocytes generated have been used in models of myocardial regeneration. However, several questions still remain and are currently under active investigation. Objective To develop a culture system that is suitable for the induction of embryonic stem cells to cardiomyocyte differentiation. Material and Methods Four human embryonic stem cell lines were used. The cells were cultured and differentiation was induced using methods previously described. The presence of cells in an undifferentiated state and cardiomyocyte differentiation was detected by immunohistochemical studies (fluorescent staining) and RT-PCR. Results The methodology used allowed stem cells growth in the culture, and maintained them in an undifferentiated state. Cardiomyocyte differentiation was achieved in the four cell lines used, yet with uneven efficacy. This was confirmed by the expression of myocardial transcription factors and heart structural proteins. Conclusions Our system allowed human embryonic stem cell growth and differentiation in the culture. These preliminary results encourage us to continue developing our methods with induced pluripotent stem cells.

Análise filogenética do gene da miogenina / Phylogenetic analysis of the myogenin gene

Estudou-se a filogenia do gene da miogenina, um membro da família MyoD, reguladora da miogênese, que ocorre durante o desenvolvimento embrionário, e sua história evolutiva em espécies domésticas que apresentem seqüências de DNA depositadas no Genbank, comparando-se o índice de substituição de nucleotídeos não-sinônimos pelo índice de substituição sinônima. Valores maiores do que um (1) indicaram que o gene sofreu mudanças que tornaram o organismo mais adaptado ao ambiente. As árvores filogenéticas foram obtidas por máxima verossimilhança, e os índices de substituição sinônima e não-sinônima foram analisadas pelo método de parcimônia. Os resultados indicaram que, provavelmente, o gene sofreu evolução adaptativa no grupo Ruminantia, Bos taurus e Ovis aries, depois que essas espécies divergiram do ancestral comum. Para as outras espécies analisadas, o gene parece ter evoluído de modo conservativo.

The myogenin gene, a member of the MyoD gene family, is a regulator of the myogenesis that takes place during the embryonic development. The objective of this study was to perform a phylogenic analysis of the myogenin gene to study its evolutionary history in the domestic species that have the sequencing data deposited in the Genbank. One common method to detect a gene evolution is made by comparing the ratio of nonsynonymous nucleotide substitution by the ratio of synonymous substitutions. Values greater than one (1) means that the gene has gone through changes that made the organism more adapted to the environment. The phylogenetic trees were obtained by maximum likelihood and the synonymous and nonsynonymous substitution rates were analyzed by the parsimony method. The results point out that probably the gene suffered an adaptive evolution in the Ruminantia group, Bos Taurus and Ovis aries, after these species diverged from their common ancestral. In the other species, the gene seems to be evolved in a conservative way.