State dependence of arousal from torpor in brown long-eared bats (Plecotus auritus)

publishedVersio

Smoking and infertility: multivariable regression and Mendelian randomization analyses in the Norwegian Mother, Father and Child Cohort Study

Objective To investigate the association between smoking and infertility. Design Prospective study. Setting Nationwide cohort. Patients 28,606 women and 27,096 men with questionnaire and genotype information from the Norwegian Mother, Father, and Child Cohort Study. Intervention Self-reported information on smoking (having ever smoked [both sexes], age at initiation [women only], cessation [women only], and cigarettes/week in current smokers [both sexes]) was gathered. Genetically predetermined levels or likelihood of presenting these traits were estimated for Mendelian randomization. Main outcome measure Infertility (time-to-pregnancy ≥12 months). Results Having ever smoked was unrelated to infertility in women or men. Higher smoking intensity in women was associated with greater infertility odds (+1 standard deviation [SD, 48 cigarettes/week]: odds ratio [OR]crude, 1.19; 95% confidence interval [CI] 1.11–1.28; ORadjusted 1.12; 95% CI, 1.03–1.21), also after adjusting for the partner’s tobacco use. Later smoking initiation (+1 SD [3.2 years]: ORcrude, 0.94; 95% CI, 0.88–0.99; ORadjusted 0.89; 95% CI, 0.84–0.95) and smoking cessation (vs. not quitting: ORcrude, 0.83; 95% CI, 0.75–0.91; ORadjusted, 0.83; 95% CI, 0.75–0.93) were linked to decreased infertility in women. Nevertheless, Mendelian randomization results were not directionally consistent for smoking intensity and cessation and were estimated imprecisely in the 2-sample approach. In men, greater smoking intensity was not robustly associated with infertility in multivariable regression and Mendelian randomization. Conclusions We did not find robust evidence of an effect of smoking on infertility. This may be due to a true lack of effect, weak genetic instruments, or other kinds of confounding.publishedVersio

Variation in basal metabolic rate within bats of the family Vespertilionidae

Mange fysiologiske variabler, slik som metabolsk rate, varierer med klima og breddegrad. Det finnes imildertid lite informasjon om termoregulering i flaggermus ved høye breddegrader. Derfor undersøkte jeg de termoregulerende responsene til en populasjon med skjeggflaggermus (Myotis mystacinus) fra Glattnesefamilien nær denne artens nordre distribusjonsgrense. Oksygenopptaksraten (VO2) økte med synkende omgivelsestemperatur (Ta) under en temperaturgrense (TLC) på rundt 33.1°C, en TLC som er i samme område som for andre flaggermus. Termisk konduktivitet var lav sammenlignet med andre pattedyr, noe som indikerte at effektive mekanismer for varmeisolasjon har blitt utviklet. Et stort omfang av kuldeindusert metabolsk rate ble funnet vet 12°C, som kan bety at andre varmeproduserende eller energisparende mekanismer enn skjelving må finne sted ved temperaturer under dette, som for eksempel aktivitet eller torpor. Det ble målt en basal metabolsk rate (BMR) på 1.48 mL O2 g-1 h-1, som var 99% av det som var forventet for en glattneseflaggermus som veier 4.4 g, og 64% av det som var forventet for et pattedyr som veier 4.4 g. En lav BMR assosieres ofte med varme omgivelsestemperaturer, mens pattedyr som lever i kaldere omgivelser ofte har høye energikostnader som fører til en økning i BMR. Dette er mest tydelig i små pattedyr, slik som flaggermus, på grunn av deres høye volum-overflateforhold og dermed store varmetap, høy massespesifikk BMR og av den grunn store energikostnader. Flaggermus lever i ulike typer klima, alt fra tropiske til tempererte strøk, og variasjoner i omgivelsestemperatur kan dermed påvirke BMR hos flaggermus fra forskjellige områder. I denne studien utførte jeg en komparativ analyse for å forstå hvordan BMR varierer i glattneseflaggermus fra ulike klima. Min hypotese var at BMR ville være forskjellig mellom artene, og jeg antok at BMR ville være høyere i klima med kalde gjennomsnittstemperaturer sammenlignet med varmere klilma. Fra et systematisk litteratursøk hentet jeg mål på BMR (N = 47) fra 21 arter i Glattnesefamilien, som også inkluderte mine egne metabolske målinger av M. mystacinus i Norge. Det ble funnet en nedgang i gjennomsnittlig omgivelsestemperatur med økende breddegrad, men jeg fant ingen effekt av verken breddegrad eller omgivelsestempratur på BMR. Det er derfor fortsatt uvisst hvordan disse flaggermusene har tilpasset seg å leve i kalde omgivelser langt nord. I stedet for å regulere BMR, er det mulig at de uttrykker en hyppigere bruk av temporær heterotermi

Energetics of whiskered bats in comparison to other bats of the family Vespertilionidae

Bats inhabit a variety of climate types, ranging from tropical to temperate zones, and environmental differences may therefore affect the basal metabolic rate (BMR) of bats from different populations. In the present study, we provide novel data on the energetics of whiskered bats (Myotis mystacinus), which is the smallest species within Chiroptera measured to date. We investigated the thermoregulatory strategies of M. mystacinus close to the northern limits of this species’ distribution range and compared these data to other vespertilionid bats living in different climates. As mammals living in colder areas experience elevated thermoregulatory costs, often leading to an increase in BMR, we hypothesised that BMR of this northern population of whiskered bats would be higher than that of bats from climates with warm environmental temperatures. From a systematic literature search we obtained BMR estimates (N=47) from 24 species within Vespertilionidae. Our metabolic measurements of M. mystacinus in Norway (body mass of 4.4 g; BMR of 1.48 ml O2 g−1 h−1) were not different from other vespertilionid bats, based on the allometric equation obtained from the systematic literature search. Further, there was no effect of environmental temperature on BMR within Vespertilionidae. How these tiny bats adapt metabolically to high latitude living is thus still an open question. Bats do have a suite of physiological strategies used to cope with the varying climates which they inhabit, and one possible factor could be that instead of adjusting BMR they could express more torpor

Smoking and infertility: multivariable regression and Mendelian randomization analyses in the Norwegian Mother, Father and Child Cohort Study

Objective: To investigate the association between smoking and infertility. Design: Prospective study. Setting: Nationwide cohort. Patients: 28,606 women and 27,096 men with questionnaire and genotype information from the Norwegian Mother, Father, and Child Cohort Study. Intervention: Self-reported information on smoking (having ever smoked [both sexes], age at initiation [women only], cessation [women only], and cigarettes/week in current smokers [both sexes]) was gathered. Genetically predetermined levels or likelihood of presenting these traits were estimated for Mendelian randomization. Main outcome: measure Infertility (time-to-pregnancy ≥12 months). Results: Having ever smoked was unrelated to infertility in women or men. Higher smoking intensity in women was associated with greater infertility odds (+1 standard deviation [SD, 48 cigarettes/week]: odds ratio [OR]crude, 1.19; 95% confidence interval [CI] 1.11–1.28; ORadjusted 1.12; 95% CI, 1.03–1.21), also after adjusting for the partner’s tobacco use. Later smoking initiation (+1 SD [3.2 years]: ORcrude, 0.94; 95% CI, 0.88–0.99; ORadjusted 0.89; 95% CI, 0.84–0.95) and smoking cessation (vs. not quitting: ORcrude, 0.83; 95% CI, 0.75–0.91; ORadjusted, 0.83; 95% CI, 0.75–0.93) were linked to decreased infertility in women. Nevertheless, Mendelian randomization results were not directionally consistent for smoking intensity and cessation and were estimated imprecisely in the 2-sample approach. In men, greater smoking intensity was not robustly associated with infertility in multivariable regression and Mendelian randomization. Conclusions: We did not find robust evidence of an effect of smoking on infertility. This may be due to a true lack of effect, weak genetic instruments, or other kinds of confounding

Risk of cardiovascular disease in women and men with subfertility: the Trøndelag Health Study

Objective To investigate the association between subfertility and risk of cardiovascular disease (CVD) outcomes. Design Prospective study. Setting Population-based cohort. Patient(s) We studied 31,629 women and 17,630 men participating in the Trøndelag Health Study. Intervention(s) Self-reported subfertility. As men were not directly asked about fertility, male partners of female participants were identified through linkage to the Medical Birth Registry of Norway and assigned the fertility information obtained from their partners. Main Outcome Measure(s) The primary outcomes were stroke and coronary heart disease in women and men with and without a history of subfertility. The secondary outcomes were myocardial infarction and angina (subgroups of coronary heart disease) and any CVD (stroke or coronary heart disease). Information on CVD was available by linkage to hospital records. We used Cox proportional hazards models adjusted for age at participation in the Trøndelag Health Study (linear + squared), birth year, smoking history, cohabitation, and education. Cardiometabolic factors were assessed in separate models. Result(s) A total of 17% of women and 15% of men reported subfertility. In women, subfertility was modestly associated with an increased risk of stroke (age-adjusted hazard ratio [aaHR], 1.19; 95% confidence interval [CI], 1.02–1.39; adjusted hazard ratio [aHR]; 1.18; 95% CI, 1.01–1.37) and coronary heart disease (aaHR, 1.19; 95% CI, 1.06–1.33; aHR, 1.16; 95% CI, 1.03–1.30) compared with fertile women. In men, we observed a weak positive association for stroke (aaHR, 1.11; 95% CI, 0.91–1.34; aHR, 1.10; 95% CI, 0.91–1.33) and a weak inverse association for coronary heart disease (aaHR, 0.92; 95% CI, 0.81–1.05; aHR, 0.93; 95% CI, 0.81–1.06). Conclusion(s) We observed modestly increased risks of CVD outcomes in women and some weak associations in men, although with no strong statistical evidence on sex differences. We acknowledge that we were only able to include men linked to pregnancies ending at 12 completed gestational weeks or later, potentially resulting in selection bias and misclassification of history of subfertility in analyses of male partners. Despite the large sample size, our results indicate the need for larger studies to obtain precise results in both sexes and determine whether there are true sex differences