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1.
Poult Sci ; 98(8): 3268-3277, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31041445

RESUMO

Broiler chicks in the immediate posthatch handling period are exposed to thermal stress, with potentially harmful consequences for muscle growth and structure (e.g., less protein and more fat deposition). We addressed the effects of broiler chicks' exposure to various ambient temperatures during the first 13 D posthatch on their performance, as well as on muscle development and structure, up to day 35. Body weight and pectoralis muscle growth were lower throughout the entire period in the high-heat-exposed chicks (39°C, Hot) and to a lesser extent in the mild-heat-exposed chicks (35°C, Hot Mild) than in the Control chicks that were raised under a commercial protocol. In the cold-exposed chicks (29oC, Cold), BW and pectoralis muscle absolute growth were similar to the Control group throughout the entire period. The lower body and muscle growth in the Hot and Hot Mild groups were reflected in a lower number of myonuclei expressing proliferating cell nuclear cell in pectoralis major muscle cross sections sampled on day 8, in the distribution of myofibers as the experiment progressed, and in mean myofiber diameter on day 35, whereas in the Cold group, these numbers exceeded that of the Control group. However, TUNEL assay revealed similar cell survival in all groups. Hematoxylin-eosin and Oil red O staining revealed the highest fat deposition in the pectoralis muscle derived from the Hot group, whereas lower fat deposition was observed in the Control Cold group. These results were corroborated by immunostaining for CCAAT/enhancer binding protein ß in the pectoralis muscle, the levels of which were significantly higher in the Hot and Hot Mild groups on day 35 than in the Control group. Similar results were observed with Sirius red staining for collagen content in the pectoralis muscle. Together, the results imply long-term effects of chronic heat stress vs. cold stress in the early posthatch period on the broiler's body and muscle growth in general and myodegeneration of the pectoralis muscle in particular.


Assuntos
Galinhas/crescimento & desenvolvimento , Resposta ao Choque Frio/fisiologia , Resposta ao Choque Térmico/fisiologia , Músculos Peitorais/crescimento & desenvolvimento , Animais , Animais Recém-Nascidos/fisiologia , Peso Corporal , Galinhas/fisiologia , Temperatura Baixa/efeitos adversos , Colágeno/análise , Temperatura Alta/efeitos adversos , Masculino , Desenvolvimento Muscular/fisiologia , Miofibrilas , Músculos Peitorais/química , Estresse Fisiológico
2.
Poult Sci ; 96(8): 2877-2888, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28444312

RESUMO

Heat or cold stress, can disrupt well-being and physiological responses in birds. This study aimed to elucidate the effects of continuous heat exposure in the first 2 wk of age on muscle development in broilers, with an emphasis on the pectoralis muscle satellite cell population. Chicks were reared for 13 d under either commercial conditions or a temperature regime that was 5°C higher. Body and muscle weights, as well as absolute muscle growth were lower in heat-exposed chicks from d 6 onward. The number of satellite cells derived from the experimental chicks was higher in the heat-treated group on d 3 but lower on d 8 and 13 compared to controls. This was reflected in a lower number of myonuclei expressing proliferating nuclear cell antigen in cross sections of pectoralis major muscle sampled on d 8. However, a TUNEL assay revealed similar cell survival in both groups. Mean myofiber diameter and distribution were lower in muscle sections sampled on d 8 and 13 in heat-treated versus control group, suggesting that the lower muscle growth is due to changes in muscle hypertrophy. Oil-Red O staining showed a higher number of satellite cells with lipids in the heat-treated compared to the control group on these days. Moreover, lipid deposition was observed in pectoralis muscle cross sections derived from the heat-treated chicks on d 13, whereas the controls barely exhibited any lipid staining. The gene and protein expression levels of CCAAT/enhancer binding protein ß in pectoralis muscle from the heat-treated group were significantly higher on d 13 than in controls, while myogenin levels were similar. The results suggest high sensitivity of muscle progenitor cells in the early posthatch period at a time when they are highly active, to chronic heat exposure, leading to impaired myogenicity of the satellite cells and increased fat deposition.


Assuntos
Galinhas/crescimento & desenvolvimento , Temperatura Alta/efeitos adversos , Desenvolvimento Muscular , Músculos Peitorais/crescimento & desenvolvimento , Células Satélites de Músculo Esquelético/metabolismo , Animais , Masculino , Distribuição Aleatória , Estresse Fisiológico , Fatores de Tempo
3.
Poult Sci ; 94(10): 2528-36, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26316337

RESUMO

Thermal manipulation (TM) of 39.5°C applied during mid-embryogenesis (embryonic d 7 to 16) has been proven to promote muscle development and enhance muscle growth and meat production in meat-type chickens. This study aimed to elucidate the cellular basis for this effect. Continuous TM or intermittent TM (for 12 h/d) increased myoblast proliferation manifested by higher (25 to 48%) myoblast number in the pectoral muscles during embryonic development but also during the first week posthatch. Proliferation ability of the pectoral-muscle-derived myoblasts in vitro was significantly higher in the TM treatments until embryonic d 15 (intermittent TM) or 13 (continuous TM) compared to that of controls, suggesting increased myogenic progeny reservoir in the muscle. However, the proliferation ability of myoblasts was lower in the TM treatments vs. control during the last days of incubation. This coincided with higher levels of myogenin expression in the muscle, indicating enhanced cell differentiation in the TM muscle. A similar pattern was observed posthatch: Myoblast proliferation was significantly higher in the TM chicks relative to controls during the peak of posthatch cell proliferation until d 6, followed by lower cell number 2 wk posthatch as myoblast number sharply decreases. Higher myogenin expression was observed in the TM chicks on d 6. This resulted in increased muscle growth, manifested by significantly higher relative weight of breast muscle in the embryo and posthatch. It can be concluded that temperature elevation during mid-term embryogenesis promotes myoblast proliferation, thus increasing myogenic progeny reservoir in the muscle, resulting in enhanced muscle growth in the embryo and posthatch.


Assuntos
Galinhas/fisiologia , Desenvolvimento Muscular , Mioblastos/metabolismo , Músculos Peitorais/crescimento & desenvolvimento , Animais , Proliferação de Células , Embrião de Galinha/crescimento & desenvolvimento , Temperatura Alta , Distribuição Aleatória
4.
J Appl Physiol (1985) ; 106(1): 233-40, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19023019

RESUMO

We investigated the cellular and molecular bases for the promotion of muscle development and growth by temperature manipulations (TMs) during late-term chick embryogenesis. We show that incubation at 39.5 degrees C (increase of 1.7 degrees C from normal conditions) from embryonic days 16 to 18 (E16 to E18) for 3 or 6 h daily increased diameter of myofibers as of day 13 of age and enhanced absolute muscle growth relative to controls, until day 35 of age. TMs had immediate (E17) and later (up to 2 wk posthatch) effects in elevating muscle cell proliferation relative to controls. This was indicated by higher DNA incorporation of thymidine and a higher number of cells expressing PCNA in intact muscle, accompanied by higher Pax7 levels, all reflecting a higher number of myogenic cells, and suggesting that the increased hypertrophy can be attributed to a higher reservoir of myogenic progeny cells produced in response to the TM. IGF-I levels were higher in the TM groups than in controls, implying a mechanism by which heat manipulations in chicks affect muscle development, with locally secreted IGF-I playing a major role. Whereas hypertrophy was similar in both TM groups, cell proliferation and Pax7 levels were more robust in the 6-h muscle, mainly posthatch, suggesting a differential effect of various TM periods on cell reservoir vs. hypertrophy and a high sensitivity of myoblasts to relatively small changes in heat duration with respect to these processes, which is manifested in the short and long term.


Assuntos
Proliferação de Células , Temperatura Alta , Desenvolvimento Muscular , Mioblastos/patologia , Músculos Peitorais/embriologia , Animais , Tamanho Celular , Embrião de Galinha , Replicação do DNA , Hipertrofia , Fator de Crescimento Insulin-Like I/metabolismo , Mioblastos/metabolismo , Fator de Transcrição PAX7/metabolismo , Músculos Peitorais/metabolismo , Músculos Peitorais/patologia , Antígeno Nuclear de Célula em Proliferação/metabolismo , Fatores de Tempo
5.
Am J Physiol Regul Integr Comp Physiol ; 290(4): R1062-70, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16269574

RESUMO

Our previous studies demonstrated that illumination of chicken embryos with monochromatic green light results in enhanced body and muscle weight at later posthatch stages. In the present study, we investigated the cellular and molecular basis of this phenomenon. First, we showed that on day 6 posthatch, myofibers were more uniform in the in ovo illuminated group than in the control group incubated in the dark, with respect to the number of myofibers displaying diameter values within the range of the mean value. Second, we tested the hypothesis that in ovo illumination causes an increase in the number of myoblasts; this in turn can promote posthatch muscle growth. Indeed, a significant increase in the number of skeletal muscle cells isolated from pectoralis muscle was observed in the in ovo illuminated group on days 1 and 3 posthatch relative to the control group. This increased cell number was accompanied by higher expression levels of Pax7 and myogenin proteins on posthatch days 1 and 3, respectively. A parallel analysis of proliferating cells in the intact muscle further demonstrated a significant increase in the number of cells positive for proliferating cell nuclear antigen in muscle from the in ovo illuminated group. Third, we demonstrated that the transition from fetal- to adult-type myoblasts, normally occurring in late stages of chicken embryogenesis, is initiated earlier in embryos subjected to in ovo green-light illumination. We suggest that the stimulatory effect of in ovo illumination on posthatch muscle growth is the result of enhanced proliferation and differentiation of adult myoblasts and myofiber synchronization.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Fibras Musculares Esqueléticas/química , Músculo Esquelético/embriologia , Estimulação Luminosa , Animais , Anticorpos Monoclonais/imunologia , Biomarcadores , Proliferação de Células , Embrião de Galinha , Galinhas , Luz , Células Musculares/fisiologia , Desenvolvimento Muscular , Músculo Esquelético/metabolismo , Mioblastos/metabolismo , Miogenina/metabolismo , Miosinas/metabolismo , Fator de Transcrição PAX7/metabolismo
6.
Dev Dyn ; 231(3): 489-502, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15390217

RESUMO

The paired-box transcription factor Pax7 plays a critical role in the specification of satellite cells in mouse skeletal muscle. In the present study, the position and number of Pax7-expressing cells found in muscles of growing and adult chickens confirm the presence of this protein in avian satellite cells. The expression pattern of Pax7 protein, along with the muscle regulatory proteins MyoD and myogenin, was additionally elucidated in myogenic cultures and in whole muscle from posthatch chickens. In cultures progressing from proliferation to differentiation, the expression of Pax7 in MyoD+ cells declined as the cells began expressing myogenin, suggesting Pax7 as an early marker for proliferating myoblasts. At all time points, some Pax7+ cells were negative for MyoD, resembling the reserve cell phenotype. Clonal analysis of muscle cell preparations demonstrated that single progenitors can give rise to both differentiating and reserve cells. In muscle tissues, Pax7 protein expression was the strongest by 1 day posthatch, declining on days 3 and 6 to a similar level. In contrast, myogenin expression peaked on day 3 and then dramatically declined. This finding was accompanied by a robust growth in fiber diameter between day 3 and 6. The distinctions in Pax7 and myogenin expression patterns, both in culture and in vivo, indicate that while some of the myoblasts differentiate and fuse into myofibers during early stages of posthatch growth, others retain their reserve cell capacity.


Assuntos
Diferenciação Celular , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Homeodomínio/metabolismo , Desenvolvimento Muscular , Células Satélites de Músculo Esquelético/metabolismo , Animais , Animais Recém-Nascidos , Anticorpos Monoclonais/imunologia , Biomarcadores , Divisão Celular , Linhagem da Célula , Células Cultivadas , Galinhas , Células Clonais , Técnica Direta de Fluorescência para Anticorpo , Proteínas de Homeodomínio/imunologia , Imuno-Histoquímica , Modelos Biológicos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/imunologia , Fibras Musculares Esqueléticas/fisiologia , Proteína MyoD/imunologia , Proteína MyoD/metabolismo , Mioblastos/metabolismo , Miogenina/imunologia , Miogenina/metabolismo , Fator de Transcrição PAX7 , Células Satélites de Músculo Esquelético/citologia , Fatores de Tempo
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