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SIRT6, a member of the sirtuin protein family, is recognized as a tumor suppressor. This study investigates the evolutionary history of the SIRT gene family and examines the selective pressures shaping their functional divergence. Insights into the evolution of these genes may enhance our understanding of their roles in disease pathology. Seventy-three amino acid sequences and full-length mRNA sequences from 22 vertebrate species and one invertebrate were retrieved from public databases. Phylogenetic relationships among the seven SIRT gene family members were reconstructed using Bayesian inference. Codon-based models were applied to detect site-specific positive selection, and likelihood ratio tests (LRTs) were used to compare model fits. Positively selected sites were identified using Bayesian empirical Bayes (BEB) methods. Phylogenetic analysis revealed that the seven SIRT gene family members in vertebrates originated from gene duplication events. Asymmetric evolutionary rates and natural selection were identified as the primary drivers of SIRT gene divergence. Eleven positively selected sites (23I, 310 S, 311I, 313 A, 316 K, 320 C, 321 A, 322Q, 323 H, 327E, 328P) were identified with high confidence (posterior probability ≥ 99%), suggesting critical roles in functional divergence. The evolution of the SIRT gene family is characterized by gene duplication and natural selection. The reconstructed phylogenetic tree elucidates the relationships among the seven members, with SIRT6 emerging as a key evolutionary node. Positively selected sites identified in this study may represent mutation hotspots, providing potential targets for future cancer therapy research. [ABSTRACT FROM AUTHOR]

Abstract Calamansi or Philippine lime (Citrofortunella macrocarpa) is an important crop for local economic in Hainan Island. There is no study about Calamansi germplasm evaluation and cultivar development. In this study, Calamansi data were collected from 151 of Calamansi seedling trees, and 37 phenotypic traits were analyzed to investigate their genetic diversities. The cluster analysis and principal component analysis were conducted aiming to provide a theoretical basis for the Calamansi genetic improvement. The results of the diversity analysis revealed: (1) the diversity indexes for qualitative traits were ranged from 0.46–1.39, and the traits with the highest genetic diversity level were fruit shaped and pulp colored (H′ > 1.20); and the diversity indexes for quantitative traits ranged from 0.67–2.10, with the exception of a lower in fruit juice rate (1.08) and lower in number of petals (0.67). (2) The clustering analysis of phenotypic traits have arranged the samples into 4 categories: the first group characterized by fewer flesh Segment number per fruit (SNF) and more Oil cell number (OCN); the second group had 7 samples, all characterized with larger Crown breadth (CB), higher Yield per tree (YPT), the lager leaf, the higher Ascorbic acid (AA), and less Seed number per fruit (SNPF); the third group had 25 samples characterized by smaller Tree foot diameter (TFD),smaller Fruit shape index (FSI) and higher Total soluble solids (TSS) contain; the fourth group had 87 samples, they were characterized by shorter Petiole length (PEL), larger fruit, higher Juice ratio (JR), multiple Stamen number (SN) and longer Pistil length (PIL). (3) The principal component analysis showed the values of the first 9 major components characteristic vectors were all greater than 3, the cumulative contribution rate reach 72.20%, including the traits of single fruit weight, fruit diameter, tree height, tree canopy width etc. Finally, based on the comprehensive main component value of all samples, the Calamansi individuals with higher testing scores were selected for further observation. This study concludes that Calamansi seedling populations in the Hainan Island holds great genetic diversity in varies traits, and can be useful for the Calamansi variety improvements.

In order to define the effects of fruit crop load on the distribution and utilization of carbon and nitrogen in dwarf apple trees, we conducted three crop load levels (High-crop load, 6 fruits per trunk cross-sectional area (cm 2 , TCA)), Medium-crop load (4 fruits cm -2 TCA), Low-crop load (2 fruits cm -2 TCA)) in 2014 and 2015. The results indicated that the 15 N derived from fertilizer (Ndff) values of fruits decreased with the reduction of crop load, but the Ndff values of annual branches, leaves and roots increased. The plant 15 N-urea utilization rates on Medium and Low-crop load were 1.12-1.35 times higher than the High-crop load. With the reduction of crop load, the distribution rate of 13 C and 15 N in fruits was gradually reduced, but in contrast, the distribution of 13 C and 15 N gradually increased in annual branches, leaves and roots. Compared with High-crop load, the Medium and Low-crop load significantly improved fruit quality p < 0.05. Hence, controlling fruit load effectively regulated the distribution of carbon and nitrogen in plants, improved the nitrogen utilization rate and fruit quality. The appropriate crop load level for mature M.26 interstocks apple orchards was deemed to be 4.0 fruits cm -2 TCA.