Dataset Information

Mitochondrial DNA variation in the Viking age population of Norway.

ABSTRACT: The medieval Norsemen or Vikings had an important biological and cultural impact on many parts of Europe through raids, colonization and trade, from about AD 793 to 1066. To help understand the genetic affinities of the ancient Norsemen, and their genetic contribution to the gene pool of other Europeans, we analysed DNA markers in Late Iron Age skeletal remains from Norway. DNA was extracted from 80 individuals, and mitochondrial DNA polymorphisms were detected by next-generation sequencing. The sequences of 45 ancient Norwegians were verified as genuine through the identification of damage patterns characteristic of ancient DNA. The ancient Norwegians were genetically similar to previously analysed ancient Icelanders, and to present-day Shetland and Orkney Islanders, Norwegians, Swedes, Scots, English, German and French. The Viking Age population had higher frequencies of K*, U*, V* and I* haplogroups than their modern counterparts, but a lower proportion of T* and H* haplogroups. Three individuals carried haplotypes that are rare in Norway today (U5b1b1, Hg A* and an uncommon variant of H*). Our combined analyses indicate that Norse women were important agents in the overseas expansion and settlement of the Vikings, and that women from the Orkneys and Western Isles contributed to the colonization of Iceland.

SUBMITTER: Krzewinska M

PROVIDER: S-EPMC4275891 | biostudies-other | 2015 Jan

REPOSITORIES: biostudies-other

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Mitochondrial DNA variation in the Viking age population of Norway.

Krzewińska Maja M Bjørnstad Gro G Skoglund Pontus P Olason Pall Isolfur PI Bill Jan J Götherström Anders A Hagelberg Erika E

Philosophical transactions of the Royal Society of London. Series B, Biological sciences 20150101 1660

The medieval Norsemen or Vikings had an important biological and cultural impact on many parts of Europe through raids, colonization and trade, from about AD 793 to 1066. To help understand the genetic affinities of the ancient Norsemen, and their genetic contribution to the gene pool of other Europeans, we analysed DNA markers in Late Iron Age skeletal remains from Norway. DNA was extracted from 80 individuals, and mitochondrial DNA polymorphisms were detected by next-generation sequencing. The ...[more]

PMID: 25487335

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Project description:Mitochondria play a central role in energy homeostasis and act as regulatory checkpoints for downstream metabolic responses and cell senescence processes during an entire life span. Acute or chronic environmental toxicant exposures have shown deleterious organ-specific human health issues at various life stages. Since mitochondria are a prime target for ensuing cellular bioenergetics responses and senescence, it is essential to understand mitochondrial bioenergetic responses in different organs over multiple life stages. Therefore, in the present study, we evaluated mitochondrial bioenergetic parameters in the liver, lung, and heart in four diverse age groups (young: 1 month; adult: 4 months; middle-aged: 12 months; old-aged: 24 month) using male Brown Norway rats as a model of aging (n?=?5 sample size/organ/age group) and compared them with our previously published results on brain. Real-time mitochondrial bioenergetic parameters (i.e., State III, State IV, and State V) were measured using the Seahorse Extracellular Flux Analyzer. Additionally, mitochondrial enzyme pyruvate dehydrogenase complex (PDHC), Complex I, Complex II, and Complex IV activities were measured using Synergy HT plate reader. Our results indicated that nearly in all parameters, significant age- and organ-specific interactions were observed. We observed age-specific declines in State III (i.e., ATP synthesis rate) responses in both the heart and lung, where opposite was observed in the liver as age advances. Across the age, the heart has highest enzyme activities than the liver and lung. Interestingly, heart and liver mitochondrial bioenergetic rates and enzyme activities remain higher than the lung, which specifies their higher metabolic capabilities than the lung. Amongst all, bioenergetic rates and enzyme activities in the lung remain lowest suggesting the lung may display higher vulnerability and lower resilience to environmental toxicants during aging than other organs tested here. Overall, these age- and organ-specific findings may facilitate a more contextualized understanding of mitochondrial bioenergetic outcomes when considering the interactions of age-related sensitivities with exposure to chemical stressors from the environment.

Project description:Study questionHave mean age at menarche or mean age at natural menopause changed from the 1939 birth cohort to the 1964 birth cohort?Summary answerWe estimated a minor decrease in mean age at menarche and an increase by nearly 3 years in mean age at natural menopause.What is known alreadyIn the Western world, age at menarche decreased across birth cohorts from the early 1800s until the 1950s. Whether mean age at menarche has continued to decrease in birth cohorts after the 1950s remains uncertain. It is also uncertain whether mean age at natural menopause has changed across birth cohorts.Study design, size, durationWe performed a retrospective population study of 312 656 women who were born in Norway during the years 1936-1964.Participants/materials, setting, methodsThe data were obtained by two self-administered questionnaires from women who participated in the Norwegian breast cancer screening program (BreastScreen Norway) during the years 2006-2014. We used flexible parametric survival models with restricted cubic splines to estimate mean age at menarche, mean age at menopause and mean number of years between menarche and menopause according to the women's year of birth. The women who were still having menstrual periods contributed with follow-up time until the time of data collection, and the women who had reported surgical removal of the uterus and/or both ovaries prior to natural menopause contributed with follow-up time until the time of surgery.Main results and the role of chanceThe mean age at menarche was 13.42 years (95% CI: 13.40-13.44 years) among women born during 1936-1939, and it was 13.24 years (95% CI: 13.22-13.25 years) among women born during 1960-1964. The mean age at natural menopause increased from 50.31 years (95% CI: 50.25-50.37 years) among women born during 1936-1939 to 52.73 years (95% CI: 52.64-52.82 years) among women born during 1960-1964. The mean number of years between menarche and menopause increased from 36.83 years (95% CI: 36.77-36.89 years) to 40.22 years (95% CI: 40.11-40.34 years).Limitations, reasons for cautionInformation about age at menarche and age at menopause was based on self-reports.Wider implications of the findingsLate menopause is associated with increased risk of breast cancer but also with increased life expectancy. Thus, higher mean age at menopause may partly explain the increase in breast cancer incidence after menopause and the increase in life expectancy in recent time. Also, a longer interval between menarche and menopause could suggest that the number of years of female fecundity has increased.Study funding/competing interest(s)This work was funded by the South-Eastern Norway Regional Health Authority [grant number 2016112 to M.S.G.] and by the Norwegian Cancer Society [grant number 6863294-2015 to E.K.B.]. The authors declare no conflicts of interest.

Dataset Information

Mitochondrial DNA variation in the Viking age population of Norway.

Publications

Mitochondrial DNA variation in the Viking age population of Norway.

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