Sex allocation theory applied to hermaphrodites assumes that there is a trade off between the alloca- tion of resources to male and female functions, within a fixed reproductive resource budget. Charnov＇s classic res...Sex allocation theory applied to hermaphrodites assumes that there is a trade off between the alloca- tion of resources to male and female functions, within a fixed reproductive resource budget. Charnov＇s classic resource allocation model predicts a more female-biased sex allocation when competition among different sperm donors is low due to diminishing fitness returns for male investment. By manipulating the social group size, one automatically changes the population density at which individ- uals live. Increasing population density may affect reproductive allocation, leading to resource compe- tition and/or to increased concentration of harmful metabolites. This could lead to an over- or under- estimation of the individual adjustment of sex allocation responses to mating opportunities. In this article, we tested the effects of density and social group size separately on female investment and body growth （considered as proxy of the overall energy budget） in the simultaneously hermaphroditic polychaete worm Ophryotrocha diadema. We manipulated social group size （i.e., monogamous and promiscuous regimes） and density （i.e., 4 levels） using a full-factorial design, to identify the underlying factor affecting female allocation （in terms of egg production） and body growth. In contrast to findings of previous experiments, we found that an increase in population density reduced body growth and egg production of hermaphrodites irrespective of social group size. We advance the hypothesis that the increase of catabolites and oxygen consumption in high-density conditions reduces the overall resource budget and this could obscure group size effects on female fecundity.展开更多
In mammalian skeletal muscle there are four carboxylases involved in several biochemical processes like gluconeogenesis, tricarboxylic acid cycle anaplerosis, metabolism of fatty acids and metabolism of various amino ...In mammalian skeletal muscle there are four carboxylases involved in several biochemical processes like gluconeogenesis, tricarboxylic acid cycle anaplerosis, metabolism of fatty acids and metabolism of various amino acids. It has been shown that biotin deficiency reduces body weight at the expense of muscular mass. When necessary, the liver uses skeletal muscle protein to provide glucose and amino acids to organs in need of such compounds. In this paper we analyzed carboxylase specific activities in hind limb skeletal muscle of 3 weeks old BALB/c male mice, at 0, 1, 4, 7, and 14 days of a specific diet with different biotin concentrations. Biotin was used at 0.0, 1.8 or 98.2 mg per kg of food;and was referred to as biotin deficient, sufficient and supplemented, respectively. Water and food supply and consumption by the three groups of mice were the same. Therefore, the observed effects were directly related to biotin ingestion. The body weight of biotin supplemented mice was the same as the body weight of mice in the biotin sufficient group, while biotin deficiency caused body weight reduction after 7 days of biotin depletion. We found that the total protein concentration in the vastus lateralis muscle is associated with the biotin content in the diet. After 7 days, the muscle total protein content was lower in mice of the biotin deficient group while it was higher in the mice from the biotin supplemented group展开更多
Signal transducer and activator of transcription 5b（STAT5b） has been identified as a key downstream mediator of growth hormone（GH） signaling in somatic growth of mammalian. However, the corresponding homologue gen...Signal transducer and activator of transcription 5b（STAT5b） has been identified as a key downstream mediator of growth hormone（GH） signaling in somatic growth of mammalian. However, the corresponding homologue gene of Stat5b is unknown in fish species. In this study, we generated loss-offunction mutants in stat5.1 and stat5.2, two stat5 homologues existing in zebrafish. In stat5.1-deficient zebrafish, a significant reduction of body length and body weight was detected in the embryos/larvae and adults compared with the wild-type control fish, and sexual size dimorphism in adult zebrafish was also eliminated. However, the stat5.2-deficient zebrafish displayed a normal developmental phenotype during all lifespan. Chromatin immunoprecipitation combined with deep sequencing（Ch IP-seq） method was adopted to further investigate the potential transcriptional targets of Stat5 protein and cast much light upon the biological function of Stat5. We identified more than 800 genes as transcriptional targets of Stat5 during zebrafish embryogenesis. KEGG analysis indicated that the Stat5 target gene network is predominantly linked to the metabolic pathways, neuroactive ligand-receptor interaction and JAK-STAT signaling pathways. Further validation studies suggested that Stat5.1 protein could directly regulate the expression of gh1, and stat5.1-mutated zebrafish showed a reduction of gh1 mRNA level. In the present study, stat5.1 was revealed as the corresponding homologue gene of Stat5b in fish species. Additionally,we found a novel molecular interaction between Stat5.1/Stat5b and GH, and unraveled a positive feedback loop Stat5.1-GH-Stat5.1 which is necessary for somatic growth and body development in zebrafish.展开更多
文摘Sex allocation theory applied to hermaphrodites assumes that there is a trade off between the alloca- tion of resources to male and female functions, within a fixed reproductive resource budget. Charnov＇s classic resource allocation model predicts a more female-biased sex allocation when competition among different sperm donors is low due to diminishing fitness returns for male investment. By manipulating the social group size, one automatically changes the population density at which individ- uals live. Increasing population density may affect reproductive allocation, leading to resource compe- tition and/or to increased concentration of harmful metabolites. This could lead to an over- or under- estimation of the individual adjustment of sex allocation responses to mating opportunities. In this article, we tested the effects of density and social group size separately on female investment and body growth （considered as proxy of the overall energy budget） in the simultaneously hermaphroditic polychaete worm Ophryotrocha diadema. We manipulated social group size （i.e., monogamous and promiscuous regimes） and density （i.e., 4 levels） using a full-factorial design, to identify the underlying factor affecting female allocation （in terms of egg production） and body growth. In contrast to findings of previous experiments, we found that an increase in population density reduced body growth and egg production of hermaphrodites irrespective of social group size. We advance the hypothesis that the increase of catabolites and oxygen consumption in high-density conditions reduces the overall resource budget and this could obscure group size effects on female fecundity.
基金supported by a grant from the Direccion General de Asuntos del Personal Academico(DGAPA),Universidad Nacional Autonoma de Mexico(PAPIIT IN215311).MA P MdeO was fellow of DGAPA.
文摘In mammalian skeletal muscle there are four carboxylases involved in several biochemical processes like gluconeogenesis, tricarboxylic acid cycle anaplerosis, metabolism of fatty acids and metabolism of various amino acids. It has been shown that biotin deficiency reduces body weight at the expense of muscular mass. When necessary, the liver uses skeletal muscle protein to provide glucose and amino acids to organs in need of such compounds. In this paper we analyzed carboxylase specific activities in hind limb skeletal muscle of 3 weeks old BALB/c male mice, at 0, 1, 4, 7, and 14 days of a specific diet with different biotin concentrations. Biotin was used at 0.0, 1.8 or 98.2 mg per kg of food;and was referred to as biotin deficient, sufficient and supplemented, respectively. Water and food supply and consumption by the three groups of mice were the same. Therefore, the observed effects were directly related to biotin ingestion. The body weight of biotin supplemented mice was the same as the body weight of mice in the biotin sufficient group, while biotin deficiency caused body weight reduction after 7 days of biotin depletion. We found that the total protein concentration in the vastus lateralis muscle is associated with the biotin content in the diet. After 7 days, the muscle total protein content was lower in mice of the biotin deficient group while it was higher in the mice from the biotin supplemented group
基金supported by the Fundamental Research Funds for the Central Universities(2662017PY013 and 2662015PY101)the Autonomous Project of State Key Laboratory of Freshwater Ecology and Biotechnology(2011FBZ22)the Autonomous Projects of the Institute of Hydrobiology,Chinese Academy of Sciences(Y25A17 and Y45A171301)
文摘Signal transducer and activator of transcription 5b（STAT5b） has been identified as a key downstream mediator of growth hormone（GH） signaling in somatic growth of mammalian. However, the corresponding homologue gene of Stat5b is unknown in fish species. In this study, we generated loss-offunction mutants in stat5.1 and stat5.2, two stat5 homologues existing in zebrafish. In stat5.1-deficient zebrafish, a significant reduction of body length and body weight was detected in the embryos/larvae and adults compared with the wild-type control fish, and sexual size dimorphism in adult zebrafish was also eliminated. However, the stat5.2-deficient zebrafish displayed a normal developmental phenotype during all lifespan. Chromatin immunoprecipitation combined with deep sequencing（Ch IP-seq） method was adopted to further investigate the potential transcriptional targets of Stat5 protein and cast much light upon the biological function of Stat5. We identified more than 800 genes as transcriptional targets of Stat5 during zebrafish embryogenesis. KEGG analysis indicated that the Stat5 target gene network is predominantly linked to the metabolic pathways, neuroactive ligand-receptor interaction and JAK-STAT signaling pathways. Further validation studies suggested that Stat5.1 protein could directly regulate the expression of gh1, and stat5.1-mutated zebrafish showed a reduction of gh1 mRNA level. In the present study, stat5.1 was revealed as the corresponding homologue gene of Stat5b in fish species. Additionally,we found a novel molecular interaction between Stat5.1/Stat5b and GH, and unraveled a positive feedback loop Stat5.1-GH-Stat5.1 which is necessary for somatic growth and body development in zebrafish.
