Muscle-specific growth hormone receptor (GHR) overexpression induces hyperplasia but not hypertrophy in transgenic zebrafish

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Role of different proteolytic pathways in degradation of muscle protein from streptozotocin-diabetic rats

In vitro rates of overall proteolysis and the activities of four different proteolytic pathways (lysosomal, Ca2+ dependent, ATP dependent, and ATP independent), as well as rates of protein synthesis, were measured in soleus and extensor digitorum longus (EDL) muscles from streptozotocin- diabetic rats. In the acute phase (1-3 days) of diabetes, there was an increase in overall proteolysis that coincided with an increased activity of the Ca2+-dependent pathway in both soleus and EDL and of the ATP-dependent pathway in EDL. After longer periods (5-10 days) of diabetes, the overall rate of protein degradation decreased and reached values similar to or even lower than those of controls as a result of a reduction in the activities of Ca2+-dependent and ATP-dependent pathways. No change was detected at any time interval in the activity of the intralysosomal proteolytic system in muscles from diabetic animals. Rates of protein synthesis were already reduced 24 h after diabetes induction and decreased further thereafter. Insulin treatment restored to normal the activities of the proteolytic pathways and rates of protein synthesis.

Proteomic View of the Venom from the Fire Ant Solenopsis invicta Buren

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of dietary protein level on the broiler chicken's response to methionine and betaine supplements

Two experiments were conducted to compare broiler chicken responses to methionine and betaine supplements when fed diets with low protein and relatively high metabolizable energy levels (17%, 3.3 kcal/g) or moderate protein and lower metabolizable energy levels (24%, 3.0 kcal/g), resulting in different levels of carcass fat. In Experiment 1, the basal diets were formulated with corn, soybean meal, poultry by-product meal, and poultry oil. In Experiment 2, glucose monohydrate was also added, so that identical amino acid profiles could be maintained in the 17 and 24% protein diets. On average, feeding the 17 vs. 24% protein diet decreased 21-d body weight gain by 20%, increased feed conversion ratio (FCR) by 13%, and increased abdominal fat pad weight by 104%. Methionine and betaine supplements improved the performance of chicks fed the 24% protein diet in both experiments, as indicated by body weight gain and FCR. Only supplementary methionine increased performance of chicks fed 17% protein diets, and then only in Experiment 2. Neither methionine nor betaine decreased abdominal fat pad size in either experiment. Methionine supplementation decreased relative liver size and increased breast muscle protein. Both methionine and betaine increased sample feather weight, but when expressed as a percentage of body weight, no significant differences were detected. It is concluded that increasing carcass fat by manipulating percentage dietary protein level or amino acid balance does not influence betaine's activity as a lipotropic agent.

Caracterização eletroforética de proteínas musculares de aves de interesse comercial

Pós-graduação em Medicina Veterinária - FMVZ

Selênio em tilápia do Nilo utilizando eletroforese em gel e espectrometria atômica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conditions affecting production of functional muscle recombinant alpha-tropomyosin in Saccharomyces cerevisiae

Yeasts are attractive hosts for heterologous protein production as they follow the general eukaryotic post-translational modification pattern. The well-known Saccharomyces cerevisiae has been used to produce a large variety of foreign proteins. The proper function of muscle tropomyosin depends on a specific modification at its N-terminus. Although tropomyosin has been produced in different expression systems, only the recombinant protein produced in the yeast Pichia pastoris has native-like functional properties. In this paper we describe the production of functional skeletal muscle tropomyosin in the yeast S. cerevisiae. The recombinant protein was produced in high amounts and production was strongly affected by genetic and environmental factors, including plasmid copy number, promoter strength, and growth media composition. (C) 2003 Elsevier B.V. (USA). All rights reserved.

Inflammation and apoptosis induced by mastoparan Polybia-MPII on skeletal muscle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Acute exercise reverses aged-induced impairments in insulin signaling in rodent skeletal muscle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Does alveolar soft-part sarcoma exhibit skeletal muscle differentiation? An immunocytochemical and biochemical study of myogenic regulatory protein expression

There has been persistent controversy regarding the nature of cell differentiation in alveolar soft-part sarcoma (ASPS) since its first description in 1952. Some studies suggest that ASPS might represent an unusual variant of skeletal muscle tumor, Given the availability of new monoclonal antibodies to probe for skeletal muscle differentiation and the rapid advance in immunocytochemical techniques for deparaffinized, formalin-fixed tissue sections, we wished to test the proposed hypothesis that ASPS might represent a new type of rhabdomyosarcoma Twelve archival samples of ASPS were retrieved, and we investigated the expression of two myogenic regulatory proteins, MyoD1 and myogenin, as rvell as other muscle-associated proteins, using sensitive immunocytochemical techniques. Despite the presence of desmin immunostaining in six ASPSs, no tumors were positive for either muscle actin or myoglobin Most importantly, no specimen showed nuclear expression of MyoD1 or myogenin, In 11 tumors, however, there was considerable granular immunostaining in the tumor cell cytoplasm with the anti-MyoD1 monoclonal antibody 5.8A, a phenomenon observed in various nonmuscle normal and neoplastic tissues with this antibody, To analyze the exact nature of immunostaining of MyoD1 and desmin in ASPS, biochemical analyses using available fresh frozen tumor tissue were performed, Although a 53-kDa band was noted with antidesmin antibody on Western blot analysis, no specific protein band that corresponds to the 45-kDa MyoD1 was detected with antibody 5.8A. These results confirm the presence of desmin in ASPS but argue against authentic expression of MyoD1, They also suggest that the cytoplasmic immunostaining observed with anti-MyoD1 antibody 5.8A most likely represents a nonspecific cross-reaction with an unknown cytoplasmic antigen, Considering the master role that MyoD1 and myogenin play in skeletal muscle commitment and differentiation and the lack of expression of these two proteins in ASPS as determined immunocytochemically and biochemically, we think that the histogenesis of ASPS remains unknown.

Guanidine Affects Differentially the Twitch Response of Diaphragm, Extensor Digitorum Longus and Soleus Nerve-Muscle Preparations of Mice

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Protein synthesis studies in skeletal muscle of aging rats. II. In vitro studies with 0.5M potassium chloride washed polyribosomes

To investigate further the age-related reduction in muscle protein synthesis activity found previously using a crude polyribosome/pH 5 system (Pluskal et al., 1984), a 0.5M KCl washing procedure was utilized to remove the nonribosomal factors from polyribosomes isolated from male Sprague-Dawley rats in the following age groups: young (1 to 2 months), mature (12 months), and aged (22 to 24 months). Using a common source of enriched elongation factor fraction from young animals, it was not possible to demonstrate any significant difference (p > .05) in protein synthesis between the 0.5M KCl-washed polyribosomes isolated from the various age groups. Using a cell-free system containing young salt washed polyribosomes stimulated by the addition of 0.5M KCl-wash fractions, however, it was shown that the mature and aged salt-wash fractions were less (p < .05) active than material from young animals. Thus, the observed decline in protein synthesis efficiency during aging may be attributed to a reduced capacity to promote initiation/elongation by the nonribosomal salt wash fractions of muscle polyribosomes.