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Aging plays a crucial role in the mechanisms of the impacts of genetic and environmental factors on blood pressure and serum lipids. However, to our knowledge, how the influence of genetic and environmental factors on the correlation between blood pressure and serum lipids changes with age remains to be determined. In this study, data from the Chinese National Twin Registry (CNTR) were used. Resting blood pressure, including systolic and diastolic blood pressure (SBP and DBP), and fasting serum lipids, including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TGs) were measured in 2378 participants (1189 twin pairs). Univariate and bivariate structural equation models examined the genetic and environmental influences on blood pressure and serum lipids among three age groups. All phenotypes showed moderate to high heritability (0.37–0.59) and moderate unique environmental variance (0.30–0.44). The heritability of all phenotypes showed a decreasing trend with age. Among all phenotypes, SBP and DBP showed a significant monotonic decreasing trend. For phenotype-phenotype pairs, the phenotypic correlation (Rph) of each pair ranged from −0.04 to 0.23, and the additive genetic correlation (Ra) ranged from 0.00 to 0.36. For TC&SBP, TC&DBP, TG&SBP and TGs&DBP, both the Rph and Ra declined with age, and the Ra difference between the young group and the older adult group is statistically significant (p < .05). The unique environmental correlation (Re) of each pair did not follow any pattern with age and remained relatively stable with age. In summary, we observed that the heritability of blood pressure was affected by age. Moreover, blood pressure and serum lipids shared common genetic backgrounds, and age had an impact on the phenotypic correlation and genetic correlations.
The Przewalski's gazelle (Procapra przewalskii) is critically endangered and has experienced significant decline in population numbers in the past, and now survives in four isolated populations: the Bird Island, Hudong-Ketu, Yuanzhe and Shadao-Gahai populations. To understand better the effect of habitat fragmentation and geographical isolation on gene flow and genetic variation, and uncover genetic units for conservation, we examined the hypervariable region (420 bp) of the mitochondrial DNA control region of 29 Przewalski's gazelles from four localities distributed throughout their present geographical range. Phylogenetic analysis consistently revealed four distinct mtDNA lineages within Przewalski's gazelle, with each lineage restricted to a single geographical location. The study revealed a marked divergence of lineages from the Bird Island population relative to other populations, which corresponds to the geographical association. The nucleotide diversity within populations was very low (less than 0.004). The value of Nm was less than 0.3 individuals per generation, indicating low gene flow between populations. It was suggested that the Yuanzhe, Hudong-Ketu and Shadao-Gahai populations be managed as a conservation unit because of their genetic and geographical closeness.
The partial mitochondrial 12S rRNA and 16S rRNA gene sequences (440 bp and 590 bp or so, respectively were determined of the Przewalski's gazelle Procapra przewalskii, Mongolian gazelle P. gutturosa, Tibetan gazelle P. picticaudata, goitered gazelle Gazella gutturosa, saiga Saiga tatarica, Tibetan antelope Pantholops hodgsoni, and thar Hemitragus jemlahicus. The average sequence divergence for all the species studied when both rRNA genes were combined was 8.4% (±0.7%), and the divergence values ranged from 0.5% to 13.3%. The average sequence divergence values for 16S rRNA gene and for 12S rRNA gene were 9.9% (±1.1%) and 6.3% (±1.1%), respectively. The sequence divergences among species of Procapra for 16S rRNA gene and for 12S rRNA gene were 1.4%(±0.5%) and 1.1% (±0.6%), respectively. Our phylogenetic analysis revealed the monophyly of the genus Procapra and that Przewalski's gazelle is more closely related to the Mongolian gazelle than to the Tibetan gazelle. We also found that the genus Procapra is closely related to Antilopini. We argued that the critically endangered Przewalski's gazelle should be treated as a species, not a subspecies of the Tibetan gazelle, which clearly warrants more attention from conservationists.
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