Eveningness has the increased odds for spinal diseases but the decreased odds for articular diseases with prospective hospital treatments

Eveningness has been associated with multiple health risks, including articular and spinal diseases. Here, we analyzed if higher risks for articular and spinal diseases among Evening-types are also seen as increased treatments severe enough to require hospitalization. Our sample consists of 5696 Finnish adults from the general population with information on treatments during 1987–2010 based on the national hospital discharge register (HILMO). Their chronotype was assessed as part of the national health examination study (FINRISK) in 2007. From 2007 to 2010, the risk for dorsopathies was significantly higher (OR = 1.8, p < 0.05) but that for arthropathies was significantly lower (OR = 0.5, p < 0.05) for Evening-types than for Morning-types, after controlling for a range of potential confounding factors. Based on the clinical diagnoses assessed during hospital treatment, our study demonstrates that the eveningness associates significantly with the increased odds for dorsopathies.     

Giants invading the tropics: the oriental vessel fern, Angiopteris evecta (Marattiaceae)

The Oriental vessel fern, Angiopteris evecta (G.Forst.) Hoffm. (Marattiaceae), has its native range in the South Pacific. This species has been introduced into other localities since the 18th century and is now listed as an invasive species in several regions (Jamaica, Hawaii and Costa Rica). The purpose of our study is (1) to trace the distributional history of the species, and (2) to model its potential future range based on climatic conditions. The native range and the history of introduction are based on the existing literature and on 158 specimens from 15 herbaria, together with field observations. As there are taxonomic problems surrounding A. evecta, we limited our analysis to samples from the Pacific, most closely resembling the type from Tahiti. We modelled the potential range using GARP species distribution modelling with basic climatic variables, elevation, and location in relation to the coast. Analysis of past records shows that the species is able to colonise new ecosystems with relative ease. The modelling reveals that the species could be cultivated over a much wider range than where it currently is grown. The escape of cultivated plants into nature is probably due to distance from natural areas and is limited by local ecological factors, such as soil conditions or competitors. The predicted distribution in Asia and Madagascar is similar to the native distribution of the entire genus Angiopteris. It can therefore be assumed that most Angiopteris species have similar climatic preferences, and the absence of A. evecta in this predicted region may be due to dispersal limitation. In the Americas there is no native Angiopteris, but our climatic model predicts a vast potential habitat in tropical America; an invasion of A. evecta should be anticipated here in localities where the species is cultivated. Vessel ferns are known to alter the natural environment, which may reduce local biodiversity. Since A. evecta is not yet widely cultivated, it is advisable to restrict the trade and spread of the species and to discourage its cultivation as an ornamental. The global climate data available for modelling is however not detailed enough to predict the spread of A. evecta on a local or regional scale.     

Genome-wide analysis of single nucleotide polymorphisms uncovers population structure in Northern Europe

Background

Genome-wide data provide a powerful tool for inferring patterns of genetic variation and structure of human populations.

Principal Findings

In this study, we analysed almost 250,000 SNPs from a total of 945 samples from Eastern and Western Finland, Sweden, Northern Germany and Great Britain complemented with HapMap data. Small but statistically significant differences were observed between the European populations (F_ST = 0.0040, p<10⁻⁴), also between Eastern and Western Finland (F_ST = 0.0032, p<10⁻³). The latter indicated the existence of a relatively strong autosomal substructure within the country, similar to that observed earlier with smaller numbers of markers. The Germans and British were less differentiated than the Swedes, Western Finns and especially the Eastern Finns who also showed other signs of genetic drift. This is likely caused by the later founding of the northern populations, together with subsequent founder and bottleneck effects, and a smaller population size. Furthermore, our data suggest a small eastern contribution among the Finns, consistent with the historical and linguistic background of the population.

Significance

Our results warn against a priori assumptions of homogeneity among Finns and other seemingly isolated populations. Thus, in association studies in such populations, additional caution for population structure may be necessary. Our results illustrate that population history is often important for patterns of genetic variation, and that the analysis of hundreds of thousands of SNPs provides high resolution also for population genetics.     

Developmental changes in regulation of mitochondrial respiration by ADP and creatine in rat heart in vivo

In saponin-skinned muscle fibers from adult rat heart and m. soleus the apparent affinity of the mitochondrial oxidative phosphorylation system for ADP (K_m = 200-400 M) is much lower than in isolated mitochondria (K_m = 10-20 M). This suggests a limited permeability of the outer mitochondrial membrane (OMM) to adenine nucleotides in slow-twitch muscle cells. We have studied the postnatal changes in the affinity of mitochondrial respiration for ADP, in relation to morphological alterations and expression of mitochondrial creatine kinase (mi-CK) in rat heart in vivo. Analysis of respiration of skinned fibers revealed a gradual decrease in the apparent affinity of mitochondria to ADP throughout 6 weeks post partum that indicates the development of mechanism which increasingly limits the access of ADP to mitochondria. The expression of mi-CK started between the 1st and 2nd weeks and reached the adult levels after 6 weeks. This process was associated with increases in creatine-activated respiration and affinity of oxidative phosphorylation to ADP thus reflecting the progressive coupling of mi-CK to adenine nucleotide translocase. Laser confocal microscopy revealed significant changes in rearrangement of mitochondria in cardiac cells: while the mitochondria of variable shape and size appeared to be random-clustered in the cardiomyocytes of 1 day old rat, they formed a fine network between the myofibrils by the age of 3 weeks. These results allow to conclude that in early period of development, i.e. within 2-3 weeks, the diffusion of ADP to mitochondria becomes progressively restricted, that appears to be related to significant structural rearrangements such as formation of the mitochondrial network. Later (after 3 weeks) the control shifts to mi-CK, which by coupling to adenine nucleotide translocase, allows to maximally activate the processes of oxidative phosphorylation despite limited access of ADP through the OMM.     

High levels of multiple paternity in Littorina saxatilis: hedging the bets?

The mating system of a species can have great effects on its genetic structure and evolution. We studied the extent of multiple paternity in a gastropod with internal fertilization, the intertidal snail Littorina saxatilis. Paternal genotype reconstruction based on microsatellite markers was performed on the offspring of wild, naturally fertilized females from 2 populations. The numbers of males contributing to the offspring per female were among the highest detected in invertebrates so far, with the exception of social insects. No reproductive skew in favor of males that were genetically more distant from the females was detected, and the pattern of fertilization appeared random. The result fits a hypothesis of indiscriminate mating, with genetic bet hedging as the most likely explanation. Bet hedging may have evolved as a form of inbreeding avoidance, if the snails are not able to recognize relatives. However, nutritional benefits from sperm or sexual conflict with males are additional possibilities that remain to be assessed in this species. Whatever the causes, such high levels of multiple paternity are remarkable and are likely to have a large impact on population structure and dynamics in a species in which migration between populations is spurious.     

Intrinsic post‐ejaculation sperm ageing does not affect offspring fitness in Atlantic salmon

Post‐meiotic sperm ageing, both before ejaculation and after ejaculation, has been shown to negatively affect offspring fitness by lowering the rate of embryonic development, reducing embryonic viability and decreasing offspring condition. These negative effects are thought to be caused by intrinsic factors such as oxidative stress and ATP depletion or extrinsic factors such as temperature and osmosis. Effects of post‐ejaculation sperm ageing on offspring fitness have so far almost exclusively been tested in internal fertilizers. Here, we tested whether intrinsic post‐ejaculation sperm ageing affects offspring performance in an external fertilizer, the Atlantic salmon Salmo salar. We performed in vitro fertilizations with a split‐clutch design where sperm were subjected to four post‐ejaculation ageing treatments. We varied the duration between sperm activation and fertilization while minimizing extrinsic stress factors and tested how this affected offspring fitness. We found no evidence for an effect of our treatments on embryo survival, hatching time, larval standard length, early larval survival or larval growth rate, indicating that intrinsic post‐ejaculation sperm ageing may not occur in Atlantic salmon. One reason may be the short life span of salmon sperm after ejaculation. Whether our findings are true in other external fertilizers with extended sperm activity remains to be tested.     

Maternal genetic legacy of the eastern Adriatic island of Krk--an interplay of evolutionary forces and island's historical events in shaping the genetic structure of contemporary island population

This study presents genetic diversity and structure of contemporary Krk islanders revealed by high-resolution mitochondrial DNA analysis on a sample of 132 unrelated autochthonous adults from seven different settlements and regions of the island. Relatively high level of haplogroup and haplotype diversity in the overall island sample is an indicator of numerous migrations and gene flows throughout the history. Expectedly, the results show the highest frequency of haplogroup H (33.3%), yet this value is much lower compared to different Croatian and other European mainland populations. An interesting finding refers to highly elevated frequencies of some haplogroups, otherwise rare in Croatia and most of the Europe, such as I (11.3%) and W (7.6%) in Krk population, especially pronounced in some settlements. At the level of settlements, many of the major European haplogroups were found to be absent from their mtDNA gene pools, whereas several others show a pronounced deviation from an average. Overall, our results suggest a tangled interplay of different evolutionary forces, such as founder effects and a few strong bottlenecks, presumably due to epidemics, which have occurred in various periods of the island's history. Cultural customs, such as frequent endogamy in some regions of the island during past centuries, have additionally shaped its genetic structure into the observed present-day diversity patterns.