Genetic regulation of life span, metabolism, and body weight in Pohn, a new wild-derived mouse strain

Genealogical analysis of European bison population revealed a growing up population despite very low genetic diversity

In 1919, the European bison population became extinct in the wild. The rescue of the lowland subspecies and the whole species was achieved mainly thanks to individuals from the Białowieża Forest (Polish-Belarusian border). There are currently two breeding lines—the lowland (purebred B. b. Bonasus) founded by 7 individuals and the lowland-Caucasian (hybrids of B. b. Bonasus and B. b. caucasicus) founded by 12 individuals. This genealogical study was conducted on 15,071 individuals recorded in the pedigree book between 1881 and 2020. Its objective was to determine the level of genetic variability and inbreeding almost 100 years after the rescue measures were initiated. The completeness of the pedigree of the reference population was 77% in the fifth generation backwards. A maximum of 23 generations can be traced back in the pedigree. The average inbreeding coefficient and the mean average relatedness of the reference population were very high, about 17% and 16% respectively. No significant amount of new inbreeding was discovered. The reference population has lost 9.11% of the total genetic diversity compared to the population of founders. A male of the Caucasian subspecies Kaukasus was discovered among the ancestors of the lowland lineage reference population. The effective population size calculated based on the increase in inbreeding was 23.93 individuals, based on complete generations equivalent it was 16.1 individuals. Wright’s F-statistics showed very small differences in genotypic frequencies between individuals within the two lineages in the reference population (FIS = 0.10), between individuals and the total population (FIT = 0.04) and low differentiation between lineages (FST = 0.06). The population of the European bison from the Białowieża Forest is generally very uniform but still shows good fitness.

Genetic cartography of longevity in humans and mice: Current landscape and horizons

Aging is a complex and highly variable process. Heritability of longevity among humans and other species is low, and this finding has given rise to the idea that it may be futile to search for DNA variants that modulate aging. We argue that the problem in mapping longevity genes is mainly one of low power and the genetic and environmental complexity of aging. In this review we highlight progress made in mapping genes and molecular networks associated with longevity, paying special attention to work in mice and humans. We summarize 40 years of linkage studies using murine cohorts and 15 years of studies in human populations that have exploited candidate gene and genome-wide association methods. A small but growing number of gene variants contribute to known longevity mechanisms, but a much larger set have unknown functions. We outline these and other challenges and suggest some possible solutions, including more intense collaboration between research communities that use model organisms and human cohorts. Once hundreds of gene variants have been linked to differences in longevity in mammals, it will become feasible to systematically explore gene-by-environmental interactions, dissect mechanisms with more assurance, and evaluate the roles of epistasis and epigenetics in aging. A deeper understanding of complex networks-genetic, cellular, physiological, and social-should position us well to improve healthspan.

Burly1 is a mouse QTL for lean body mass that maps to a 0.8-Mb region of chromosome 2

To fine map a mouse QTL for lean body mass (Burly1), we used information from intercross, backcross, consomic, and congenic mice derived from the C57BL/6ByJ (host) and 129P3/J (donor) strains. The results from these mapping populations were concordant and showed that Burly1 is located between 151.9 and 152.7 Mb (rs33197365 to rs3700604) on mouse chromosome 2. The congenic region harboring Burly1 contains 26 protein-coding genes, 11 noncoding RNA elements (e.g., lncRNA), and 4 pseudogenes, with 1949 predicted functional variants. Of the protein-coding genes, 7 have missense variants, including genes that may contribute to lean body weight, such as Angpt41, Slc52c3, and Rem1. Lean body mass was increased by the B6-derived variant relative to the 129-derived allele. Burly1 influenced lean body weight at all ages but not food intake or locomotor activity. However, congenic mice with the B6 allele produced more heat per kilogram of lean body weight than did controls, pointing to a genotype effect on lean mass metabolism. These results show the value of integrating information from several mapping populations to refine the map location of body composition QTLs and to identify a short list of candidate genes.

The development and biological characteristics of a novel potentially radioresistant inbred mouse strain

The growth of biomedical research over the previous decades has been accompanied by an increase in the number, complexity and diversity of experimental animals developed as research tools, and inbred mice are some of the most widely used. However, thus far, no inbred mice have exhibited strong radioresistance for use in radiation‑damage research. To develop a radioresistant mouse model, a female Japanese outbreeding strain ICR/JCL mouse was mated with a male Chinese inbred strain 615 mouse. From the F1 generation, the mouse line was maintained by brother‑to‑sister mating. A novel mouse strain was established over >20 continuous generations and designated the Institute of Radiation Medicine-2 (IRM-2) mouse. The biological characteristics, genetic characteristics and susceptibility to radiation of these mice were determined. The IRM‑2 mice inherited traits from the parents, including strong reproductive capacity, stable physiological and biochemical indices and few differences among individuals. According to the genetic results, the IRM‑2 mice exhibited homozygosity, isogenicity and consistency, in agreement with international standards for inbred strains. Radiosensitivity studies have previously suggested that the lethal dose (LD)50 values for IRM‑2 mice were 7.17 Gy (male) and 7.5 Gy (female), resulting in a dose reduction factor value of 1.39 (male) and 1.37 (female). The mortality of IRM‑2 mice irradiated with 8 Gy total body irradiation was 15% at day 9 and 90% at day 15 after radiation. The number of nucleated cells in bone marrow, DNA content and colony‑forming unit‑spleen counts in IRM‑2 mice after exposure to γ‑ray irradiation were markedly higher than the corresponding values for the parental strains, suggesting that the IRM‑2 mice exhibit high resistance to ionizing radiation. Thus, it is suggested that this novel inbred mouse strain may be developed as an animal model of radioresistance for future use in radiation research.

CETP polymorphisms confer genetic contribution to centenarians of Hainan, south of China

OBJECTIVE

In this paper, we will discuss if the CETP polymorphism contributes to the centenarians in Hainan island.

METHODS

We tested the TaqIB and I405V polymorphisms of CETP gene among 276 centenarians and 301 matched healthy individuals by AS-PCR and analyzed the data with SPSS software package (Version 19.0).

RESULTS

Our data indicated that allele B1 and V have the significant differences between centenarians and healthy control groups with P < 0.001. Further analysis implied that genotypes B1B1 (P < 0.001, OR = 0.148, 95% CI = 0.095-0.230) and VV (P < 0.001 and OR = 0.353, 95% CI = 0.237-0.525) were significantly different between centenarians and matched controls. The combination of B and V, such as B1B1-II (P < 0.001, OR = 0.128, 95% CI = 0.049-0.329), B1B1-IV (P < 0.001, OR = 0.115, 95% CI = 0.056-0.237), B1B2-VV (P < 0.05, OR = 0.534, 95% CI = 0.310-0.920), and B2B2-VV (P < 0.001, OR = 0.198, 95% CI = 0.086-0.453) have significant differences between centenarians and matched healthy individuals from Hainan.

CONCLUSION

Our results implied that allele B1B1 and VV, as well as the combination B1B1-II, B1B1-IV, B1B2-VV and B2B2-VV may contribute to the longevity in centenarians of Hainan, south of China.

Heritability of in vitro phenotypes exhibited by murine adipose-derived stromal cells

Adipose-derived stromal cells (ADSCs) exhibit significant potential as therapeutic agents to promote tissue regeneration. Success of ADSC-based therapies is dependent upon efficient cell expansion in vitro as well as postinjection survival in the caustic milieu of damaged tissue. Genetic background regulates ADSC proliferative capacity and stress resistance, but the extent of the genetic effect size is not completely defined. The present study aimed to quantify phenotypic ranges and heritability of in vitro ADSC characteristics. ADSCs were isolated from mice representing 16 genetically diverse inbred mouse strains, including 12 classical inbred strains and four wild-derived strains. Cells were grown in vitro, and proliferative capacity and oxidative stress resistance were assessed. The fold change for ADSC growth ranged from 0.87 (BALB/cByJ) to 23.60 (POHN/DehJ), relative to original seeding density. The heritability of proliferative capacity was estimated to be 0.6462 (p = 9.967 × 10(-15)), and this phenotype was not associated with other ADSC traits. Cell viability following H2O2 treatment ranged from 39.81 % (CAST/EiJ) to 91.60 % (DBA/2 J), and the heritability of this phenotype was calculated as 0.6146 (p = 1.22 × 10(-12)). Relationships between cell viability and weight of the donor fat pad were also discovered. Donor genetic background is a major determinant of in vitro ADSC phenotypes. This study supports the development of forward genetics strategies to identify genes that underlie ADSC phenotypic diversity, which will inform efforts to improve cell-based therapies.

Comparative cellular biogerontology: Where do we stand?

Due to the extreme variation in life spans among species, using a comparative approach to address fundamental questions about the aging process has much to offer. For example, maximum life span can vary by as much as several orders of magnitude among taxa. In recent years, using primary cell lines cultured from species with disparate life spans and aging rates has gained considerable momentum as a means to dissect the mechanisms underlying the variation in aging rates among animals. In this review, we reiterate the strengths of comparative cellular biogerontology, as well as provide a survey of the current state of the field. By and large this work sprang from early studies using cell lines derived from long-lived mutant mice. Specifically, they suggested that an enhanced resistance to cellular stress was strongly associated with increased longevity of select laboratory models. Since then, we and others have shown that the degree of stress resistance and species longevity is also correlated among cell lines derived from free-living populations of both mammals and birds, and more recent studies have begun to reveal the biochemical and physiological underpinnings to these differences. The continued study of cultured cell lines from vertebrates with disparate life spans is likely to provide considerable insight toward unifying mechanisms of longevity assurance.

The MNS16A polymorphism in the TERT gene in peri-centenarians from the Han Chinese population

MNS16A, a variable number of tandem repeats polymorphism in the TERT gene, has been suggested to regulate telomerase activity. As telomerase activity has been reported to be related to life-span, we hypothesized that this polymorphism might affect human longevity by controlling the length of the telomere. To test this hypothesis, we collected 446 unrelated pericentenarian individuals (age[Symbol: see text]90, mean 94.45±3.45 years) and 332 normal controls (age 22-53, mean 35.0±12.0 years) from Dujiangyan, Sichuan, China. We typed the MNS16A polymorphism in both groups, and compared the allele and genotype frequencies between the peri-centenarian and control groups using the chi-squared test. There was no significant difference between the peri-centenarian and control groups. Thus, the MNS16A polymorphism in TERT might not influence human life-span, at least in the Han Chinese population studied here.

Lifespan modulation in mice and the confounding effects of genetic background

We are currently in the midst of a revolution in ageing research, with several dietary, genetic and pharmacological interventions now known to modulate ageing in model organisms. Excitingly, these interventions also appear to have beneficial effects on late-life health. For example, dietary restriction (DR) has been shown to slow the incidence of age-associated cardiovascular disease, metabolic disease, cancer and brain ageing in non-human primates and has been shown to improve a range of health indices in humans. While the idea that DR's ability to extend lifespan is often thought of as being universal, studies in a range of organisms, including yeast, mice and monkeys, suggest that this may not actually be the case. The precise reasons underlying these differential effects of DR on lifespan are currently unclear, but genetic background may be an important factor in how an individual responds to DR. Similarly, recent findings also suggest that the responsiveness of mice to specific genetic or pharmacological interventions that modulate ageing may again be influenced by genetic background. Consequently, while there is a clear driver to develop interventions to improve late-life health and vitality, understanding precisely how these act in response to particular genotypes is critical if we are to translate these findings to humans. We will consider of the role of genetic background in the efficacy of various lifespan interventions and discuss potential routes of utilising genetic heterogeneity to further understand how particular interventions modulate lifespan and healthspan.