Unlocking the Nexus of Sirtuins: A Comprehensive Review of Their Role in Skeletal Muscle Metabolism, Development, and Disorders.

The sirtuins constitute a group of histone deacetylases reliant on NAD+ for their activity that have gained recognition for their critical roles as regulators of numerous biological processes. These enzymes have various functions in skeletal muscle biology, including development, metabolism, and the body's response to disease. This comprehensive review seeks to clarify sirtuins' complex role in skeletal muscle metabolism, including glucose uptake, fatty acid oxidation, mitochondrial dynamics, autophagy regulation, and exercise adaptations. It also examines their critical roles in developing skeletal muscle, including myogenesis, the determination of muscle fiber type, regeneration, and hypertrophic responses. Moreover, it sheds light on the therapeutic potential of sirtuins by examining their impact on a range of skeletal muscle disorders. By integrating findings from various studies, this review outlines the context of sirtuin-mediated regulation in skeletal muscle, highlighting their importance and possible consequences for health and disease.

Bacteroidales reduces growth rate through serum metabolites and cytokines in Chinese Ningdu yellow chickens.

Increasing evidence has indicated that the gut microbiome plays an important role in chicken growth traits. However, the cecal microbial taxa associated with the growth rates of the Chinese Ningdu yellow chickens are unknown. In this study, shotgun metagenomic sequencing was used to identify cecal bacterial species associated with the growth rate of the Chinese Ningdu yellow chickens. We found that nine cecal bacterial species differed significantly between high and low growth rate chickens, including three species (Succinatimonas hippei, Phocaeicola massiliensis, and Parabacteroides sp. ZJ-118) that were significantly enriched in high growth rate chickens. We identified six Bacteroidales that were significantly enriched in low growth rate chickens, including Barnesiella sp. An22, Barnesiella sp. ET7, and Bacteroidales bacterium which were key biomarkers in differentiating high and low growth rate chickens and were associated with alterations in the functional taxa of the cecal microbiome. Untargeted serum metabolome analysis revealed that 8 metabolites showing distinct enrichment patterns between high and low growth rate chickens, including triacetate lactone and N-acetyl-a-neuraminic acid, which were at higher concentrations in low growth rate chickens and were positively and significantly correlated with Barnesiella sp. An22, Barnesiella sp. ET7, and Bacteroidales bacterium. Furthermore, the results suggest that serum cytokines, such as IL-5, may reduce growth rate and are related to changes in serum metabolites and gut microbes (e.g., Barnesiella sp. An22 and Barnesiella sp. ET7). These results provide important insights into the effects of the cecal microbiome, serum metabolism and cytokines in Ningdu yellow chickens.

Base composition is the primary factor responsible for the variation of amino acid usage in zebra finch (Taeniopygia guttata).

In the present study, we carried out an examination of the amino acid usage in the zebra finch (Taeniopygia guttata) proteome. We found that tRNA abundance, base composition, hydrophobicity and aromaticity, protein second structure, cysteine residue (Cys) content and protein molecular weight had significant impact on the amino acid usage of the zebra finch. The above factors explained the total variability of 22.85%, 25.37%, 10.91%, 5.06%, 4.21%, and 3.14%, respectively. Altogether, approximately 70% of the total variability in zebra finch could be explained by such factors. Comparison of the amino acid usage between zebra finch, chicken (Gallus gallus) and human (Homo sapiens) suggested that the average frequency of various amino acid usage is generally consistent among them. Correspondence analysis indicated that base composition was the primary factor affecting the amino acid usage in zebra finch. This trend was different from chicken, but similar to human. Other factors affecting the amino acid usage in zebra finch, such as isochore structure, protein second structure, Cys frequency and protein molecular weight also showed the similar trends with human. We do not know whether the similar amino acid usage trend between human and zebra finch is related to the distinctive neural and behavioral traits, but it is worth studying in depth.

Hydrophobicity and aromaticity are primary factors shaping variation in amino acid usage of chicken proteome.

Amino acids are utilized with different frequencies both among species and among genes within the same genome. Up to date, no study on the amino acid usage pattern of chicken has been performed. In the present study, we carried out a systematic examination of the amino acid usage in the chicken proteome. Our data indicated that the relative amino acid usage is positively correlated with the tRNA gene copy number. GC contents, including GC1, GC2, GC3, GC content of CDS and GC content of the introns, were correlated with the most of the amino acid usage, especially for GC rich and GC poor amino acids, however, multiple linear regression analyses indicated that only approximately 10-40% variation of amino acid usage can be explained by GC content for GC rich and GC poor amino acids. For other intermediate GC content amino acids, only approximately 10% variation can be explained. Correspondence analyses demonstrated that the main factors responsible for the variation of amino acid usage in chicken are hydrophobicity, aromaticity and genomic GC content. Gene expression level also influenced the amino acid usage significantly. We argued that the amino acid usage of chicken proteome likely reflects a balance or near balance between the action of selection, mutation, and genetic drift.

Mutation bias is the driving force of codon usage in the Gallus gallus genome.

Synonymous codons are used with different frequencies both among species and among genes within the same genome and are controlled by neutral processes (such as mutation and drift) as well as by selection. Up to now, a systematic examination of the codon usage for the chicken genome has not been performed. Here, we carried out a whole genome analysis of the chicken genome by the use of the relative synonymous codon usage (RSCU) method and identified 11 putative optimal codons, all of them ending with uracil (U), which is significantly departing from the pattern observed in other eukaryotes. Optimal codons in the chicken genome are most likely the ones corresponding to highly expressed transfer RNA (tRNAs) or tRNA gene copy numbers in the cell. Codon bias, measured as the frequency of optimal codons (Fop), is negatively correlated with the G + C content, recombination rate, but positively correlated with gene expression, protein length, gene length and intron length. The positive correlation between codon bias and protein, gene and intron length is quite different from other multi-cellular organism, as this trend has been only found in unicellular organisms. Our data displayed that regional G + C content explains a large proportion of the variance of codon bias in chicken. Stepwise selection model analyses indicate that G + C content of coding sequence is the most important factor for codon bias. It appears that variation in the G + C content of CDSs accounts for over 60% of the variation of codon bias. This study suggests that both mutation bias and selection contribute to codon bias. However, mutation bias is the driving force of the codon usage in the Gallus gallus genome. Our data also provide evidence that the negative correlation between codon bias and recombination rates in G. gallus is determined mostly by recombination-dependent mutational patterns.