Contribution of telomerase RNA retrotranscription to DNA double-strand break repair during mammalian genome evolution

A comparative analysis of two primate and two rodent genomes suggests that telomerase was utilized, in some instances, for the repair of DNA double-strand breaks during mammalian evolution

Shorter Survival of SDF1-3′A/3′A Homozygotes Linked to CD4+ T Cell Decrease in Advanced Human Immunodeficiency Virus Type 1 Infection

The SDF-1 3′A allelic polymorphism has been reported to influence either positively or negatively the progression of human immunodeficiency virus type 1 (HIV-1) disease. Therefore, the SDF-1 genotype of 729 HIV-1-infected individuals pooled from 3 distinct cohorts was determined. A statistically nonsignificant association between the SDF1-3′A/3′A genotype and accelerated disease progression was evident among seroconverters (n = 319), but a striking correlation of decreased survival after either diagnosis of AIDS according to the 1993 definition or loss of CD4+ T cell counts <200 was observed. The relative hazards for SDF1-3′A/3′A homozygotes, compared with heterozygotes and wild-type homozygotes were 2.16 (P = .0047), for time from diagnosis according to the 1993 Centers for Disease Control and Prevention AIDS case definition (AIDS-'93) to death, and 3.43 (P = .0001), for time from CD4+ T cells <200 to death. Because no difference in survival was observed after diagnosis according to AIDS-'87, the association of the SDF1-3′A/3′A genotype with the accelerated progression of late-stage HIV-1 disease appears to be explained for the most part by the loss of CD4+ T lymphocyte

Fatality rate and predictors of mortality in an Italian cohort of hospitalized COVID-19 patients

Clinical features and natural history of coronavirus disease 2019 (COVID-19) differ widely among different countries and during different phases of the pandemia. Here, we aimed to evaluate the case fatality rate (CFR) and to identify predictors of mortality in a cohort of COVID-19 patients admitted to three hospitals of Northern Italy between March 1 and April 28, 2020. All these patients had a confirmed diagnosis of SARS-CoV-2 infection by molecular methods. During the study period 504/1697 patients died; thus, overall CFR was 29.7%. We looked for predictors of mortality in a subgroup of 486 patients (239 males, 59%; median age 71 years) for whom sufficient clinical data were available at data cut-off. Among the demographic and clinical variables considered, age, a diagnosis of cancer, obesity and current smoking independently predicted mortality. When laboratory data were added to the model in a further subgroup of patients, age, the diagnosis of cancer, and the baseline PaO2/FiO2 ratio were identified as independent predictors of mortality. In conclusion, the CFR of hospitalized patients in Northern Italy during the ascending phase of the COVID-19 pandemic approached 30%. The identification of mortality predictors might contribute to better stratification of individual patient risk

Early-life telomere dynamics differ between the sexes and predict growth in the barn swallow (Hirundo rustica)

Telomeres are conserved DNA-protein structures at the termini of eukaryotic chromosomes which contribute to maintenance of genome integrity, and their shortening leads to cell senescence, with negative consequences for organismal functions. Because telomere erosion is influenced by extrinsic and endogenous factors, telomere dynamics may provide a mechanistic basis for evolutionary and physiological trade-offs. Yet, knowledge of fundamental aspects of telomere biology under natural selection regimes, including sex- and context-dependent variation in early-life, and the covariation between telomere dynamics and growth, is scant. In this study of barn swallows (Hirundo rustica) we investigated the sex-dependent telomere erosion during nestling period, and the covariation between relative telomere length and body and plumage growth. Finally, we tested whether any covariation between growth traits and relative telomere length depends on the social environment, as influenced by sibling sex ratio. Relative telomere length declined on average over the period of nestling maximal growth rate (between 7 and 16 days of age) and differently covaried with initial relative telomere length in either sex. The frequency distribution of changes in relative telomere length was bimodal, with most nestlings decreasing and some increasing relative telomere length, but none of the offspring traits predicted the a posteriori identified group to which individual nestlings belonged. Tail and wing length increased with relative telomere length, but more steeply in males than females, and this relationship held both at the within- and among-broods levels. Moreover, the increase in plumage phenotypic values was steeper when the sex ratio of an individual's siblings was female-biased. Our study provides evidence for telomere shortening during early life according to subtly different dynamics in either sex. Furthermore, it shows that the positive covariation between growth and relative telomere length depends on sex as well as social environment, in terms of sibling sex ratio

Insertion of telomerase RNA retrotranscripts at DNA double-strand break sites during mammalian genome evolution.

This is an open access article distributed under the terms of the Creative Commons Attribution Licens

Data from: Brood size, telomere length, and parent-offspring color signaling in barn swallows

Trade-offs select for optimal allocation of resources among competing functions. Parents are selected to maximize production of viable offspring by balancing between progeny number and “quality.” Telomeres are nucleoproteins, at the ends of eukaryotic chromosomes, that shorten when cells divide. Because shortening below a certain threshold depresses organismal functioning and rate of shortening depends on environmental conditions, telomeres are good candidates as mediators of trade-offs. We altered brood size of barn swallow Hirundo rustica and found that brood enlargement caused a reduction in relative telomere length (RTL). Reliable signals of offspring quality should evolve that mediate adaptive parental care allocation. Because nestlings with darker coloration receive more care, we analyzed the covariation between RTL and coloration and found that RTL increased with plumage darkness, both within and between broods. Hence, we provide unprecedented evidence that signals relevant to parent-offspring communication reflect telomere length and thus offspring reproductive value

Relative telomere length (T/S ratio) of male and female barn swallow nestlings 16 days after hatching in relation to relative telomere length 7 days after hatching.

<p>The slope of the relationship for females (n = 29) was significantly larger than for males (n = 30).</p

Length of the wing chord (upper panel) or tail length (lower panel) at age 16 days in relation to relative telomere length (T/S ratio) on the same day.

<p>For wing length, the relationship was significantly positive for both males (n = 31) and females (n = 29), but was steeper in males. For tail length, the relationship for males (n = 31) was significantly positive and significantly steeper than in females (n = 29).</p

Repeated-measures LMM analysis of relative telomere length at day 7 or 16 after hatching in relation to sex and brood size.

<p>Brood and nestling identity were included as a random effects. Two separate models both including sex and age, and also brood size or sibling sex ratio, respectively (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142530#sec006" target="_blank">Statistical analyses</a>) did not disclose significant interaction effects. The effect of age was significant also after excluding the effect of sibling sex ratio. The analysis is based on 119 relative TL estimates from 60 nestlings, because the datum for one nestling at age 7 was missing.</p><p>Repeated-measures LMM analysis of relative telomere length at day 7 or 16 after hatching in relation to sex and brood size.</p