Differences in Muscle and Adipose Tissue Gene Expression and Cardio-Metabolic Risk Factors in the Members of Physical Activity Discordant Twin Pairs

High physical activity/aerobic fitness predicts low morbidity and mortality. Our aim was to identify the most up-regulated gene sets related to long-term physical activity vs. inactivity in skeletal muscle and adipose tissues and to obtain further information about their link with cardio-metabolic risk factors. We studied ten same-sex twin pairs (age range 50–74 years) who had been discordant for leisure-time physical activity for 30 years. The examinations included biopsies from m. vastus lateralis and abdominal subcutaneous adipose tissue. RNA was analyzed with the genome-wide Illumina Human WG-6 v3.0 Expression BeadChip. For pathway analysis we used Gene Set Enrichment Analysis utilizing active vs. inactive co-twin gene expression ratios. Our findings showed that among the physically active members of twin pairs, as compared to their inactive co-twins, gene expression in the muscle tissue samples was chronically up-regulated for the central pathways related to energy metabolism, including oxidative phosphorylation, lipid metabolism and supportive metabolic pathways. Up-regulation of these pathways was associated in particular with aerobic fitness and high HDL cholesterol levels. In fat tissue we found physical activity-associated increases in the expression of polyunsaturated fatty acid metabolism and branched-chain amino acid degradation gene sets both of which associated with decreased ‘high-risk’ ectopic body fat and plasma glucose levels. Consistent with other findings, plasma lipidomics analysis showed up-regulation of the triacylglycerols containing the polyunsaturated fatty acids. Our findings identified skeletal muscle and fat tissue pathways which are associated with the long-term physical activity and reduced cardio-metabolic disease risk, including increased aerobic fitness. In particular, improved skeletal muscle oxidative energy and lipid metabolism as well as changes in adipocyte function and redistribution of body fat are associated with reduced cardio-metabolic risk.     

Responses of stoats and least weasels to fluctuating food abundances: is the low phase of the vole cycle due to mustelid predation?

Summary We studied responses of stoats and least weasels to fluctuating vole abundances during seven winters in western Finland. Density indices of mustelids were derived from snow-tracking, diet composition from scat samples, and vole abundances from snap-trapping. Predation rate was estimated by the ratio of voles to mustelids and by the vole kill rate by predators (density of predator x percentage of voles in the diet). We tested the following four predictions of the hypothesis that small mustelids cause the low phase of the microtine cycle. (1) The densities of predators should lag well behind the prey abundances, as time lags tend to have destabilizing effects. The densities of stoats fluctuated in accordance with the vole abundances, whereas the spring densities of least weasels tracked the vole abundances with a half-year lag and the autumn densities with a 1-year lag. (2) Predators should not shift to alternative prey with declining vole densities. The yearly proportion of Microtus voles (the staple prey) in the diet of stoats varied widely (range 16–82%) and was positively correlated with the winter abundance of these voles. In contrast, the same proportion in the food of least weasels was independent of the vole abundance. (3) The ratio of voles to small mustelids should be smallest in poor vole years and largest in good ones. This was also observed. (4) Vole densities from autumn to spring should decrease more in those winters when vole kill rates are high than when they are low. The data on least weasels agreed with this prediction. Our results from least weasels were consistent with the predictions of the hypothesis, but stoats behaved like semi-generalist predators. Accordingly, declines and lows in the microtine cycle may be due to least weasel predation, but other extrinsic factors may also contribute to crashes.     

Visual behaviour and the structure of dark and light-adapted larval and adult eyes of the New Zealand glowworm Arachnocampa luminosa (Mycetophilidae: Diptera)

Both larval and adult New Zealand cave glowworms exhibit reactions to light; their photoreceptors must, therefore, be regarded as functional. The two principal stemmata of the larva possess large biconvex lenses and voluminous rhabdoms. Approximately 12 retinula cells are present. In light-adapted larvae the diameter of the rhabdom is 8 μm and that of an individual microvillus is 49.5 nm. Dark-adapted eyes have rhabdoms that measure 14 μm in cross section and microvilli with an average diameter of 54 nm. The compound eye of the adult comprises approximately 750 ommatidia, each with a facet diameter of 27–28 μm. A facet is surrounded by 1–6 interommatidial hairs which are up to 30 μm long. The interommatidial angle is 5.5°. Cones, consisting of 4 crystalline cone cells, are of the ‘acone’ type. Pigment granules in the primary pigment cells are twice as large as those of the retinula cells which measure 0.6–0.75 μm in diameter. The rhabdom is basically of the dipteran type, i.e. six open peripheral rhabdomeres surround 2 central rhabdomers arranged in a tandem position. The microvilli of cells 1–6 and cell 8 have diameters ranging from 68 to 73 nm, but those of the distally-located central rhabdomere 7 are 20% larger. This is irrespective of whether the eye is dark or light-adapted. In the latter the cones are long and narrow, the screening pigment granules closely surround the rhabdomeres, and the rhabdom is less voluminous than that of the dark-adapted eye.     

Specific interaction between human parechovirus nonstructural 2A protein and viral RNA

The functional properties of the nonstructural 2A protein are variable among different picornaviruses. The 2A protein of the human parechovirus 1 (HPEV1) has been shown to lack the proteolytic activity found in many other picornaviruses, but no particular function has been identified for HPEV1 2A. To obtain information about the role of HPEV1 2A in the viral life cycle, the protein was expressed in Escherichia coli. A polyclonal antibody was then raised against the protein and employed to investigate its subcellular localization in the infected cells by immunofluorescence microscopy. Typically, a diffuse cytoplasmic staining pattern, concentrated to the perinuclear area, was observed in the infected cells. However, at late stages of infection some infected cells also exhibited diffuse nuclear staining. Viral RNA, visualized by fluorescent in situ hybridization, partly colocalized with 2A in the perinuclear region. Three experimental approaches including Northwestern blot, UV cross-linking, and gel retardation demonstrated that 2A possesses RNA binding activity. Competition experiments with various single-stranded RNA molecules addressed the specificity of 2A binding. These studies revealed that the 2A protein bound RNA corresponding to the 3'-untranslated region (UTR) of the viral genome with highest affinity. At the N- and C-terminal ends of the protein, two regions, necessary for RNA binding, were identified by mutagenesis. In addition, we demonstrated that 2A has affinity to double-stranded RNA containing 3'UTR(+)-3'UTR(-). In conclusion, our experiments showed that HPEV1 2A binds to viral 3'UTR RNA, a feature that could be important for the function of the protein during HPEV1 replication.     

Does lignin modification affect feeding preference or growth performance of insect herbivores in transgenic silver birch (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth)?

Transgenic silver birch (Betula pendula Roth) lines were produced in order to modify lignin biosynthesis. These lines carry COMT (caffeate/5-hydroxyferulate O-methyltransferase) gene from Populus tremuloides driven by constitutive promoter 35S CaMV (cauliflower mosaic virus) or UbB1 (ubiquitin promoter from sunflower). The decreased syringyl/guaiacyl (S/G) ratio was found in stem and leaf lignin of 35S CaMV-PtCOMT transgenic silver birch lines when compared to non-transformed control or UbB1–PtCOMT lines. In controlled feeding experiments the leaves of transgenic birch lines as well as controls were fed to insect herbivores common in boreal environment, i.e., larvae of Aethalura punctulata, Cleora cinctaria and Trichopteryx carpinata (Lepidoptera: Geometridae) as well as the adults of birch leaf-feeding beetles Agelastica alni (Coleoptera: Chrysomelidae) and Phyllobius spp. (Coleoptera: Curculionidae). The feeding preferences of these herbivores differed in some cases among the tested birch lines, but these differences could not be directly associated to lignin modification. They could as well be explained by other characteristics of leaves, either natural or caused by transgene site effects. Growth performance of lepidopteran larvae fed on transgenic or control leaves did not differ significantly.     

Potato Glycoalkaloids: A Burden or a Blessing?

Steroidal glycoalkaloids (SGAs) are produced following the general steroid biosynthesis pathway, starting from acetyl-coenzyme A and followed by the intermediates mevalonic acid, squalene, cycloartenol, and cholesterol. α-Chaconine and α-solanine are the main SGAs of the cultivated potato (Solanum tuberosum), whereas many other SGAs are known in the wild potato species. Low concentrations of SGAs improve the taste of potato, but concentrations greater than 200 mg/kg can have toxic effects on animals and humans. SGAs have antimicrobial activity and confer resistance to some insects, but many such pests of potato are not greatly affected. Certain environmental conditions and wounding enhance SGA accumulation in tubers in the field and storage. Low production of SGAs is a dominant character inherited in a relatively simple manner and can be selected for in potato-breeding programs, whereas the use of wild potato germplasm tends to increase the SGA accumulation in the breeding lines. Further efforts are likely to be directed toward the reduction of the SGA content in the edible potato products through breeding and biotechnological methodologies, whereas potato genotypes with high SGA production may be developed for use in the pharmaceutical industry.     

Why does herbivore sex matter? Sexual differences in utilization of Fucus vesiculosus by the isopod Idotea baltica

Optimal feeding is often constrained by predation avoidance, which may direct feeding to take place on more sheltered, but less profitable, parts of the habitat. Though constrained, feeding preferences and/or digestive capabilities should co-evolve with the energetic and nutritional needs of the animal. These needs, as well as risk taking for these goals, may differ between the sexes. We studied sexual differences in the utilization of the brown alga Fucus vesiculosus by the marine isopod Idotea baltica . In a feeding preference test with small pieces of alga both sexes prefer the apical, newly grown parts to the basal parts. However, males show stronger preference than females. When isopods are reared on the apical or basal part of the alga alone, sexes grow differently on these parts. Females gain weight equally well and their intermolt duration is the same on both parts of the alga, while males perform clearly worse on the basal than on the apical part. Despite the better quality of the apical parts of the alga, in a grazing experiment in a "semi-natural" environment with whole bushes of F. vesiculosus also the basal parts are consumed, and even preferred over apical parts by females. We suggest that feeding preferences are subordinate to microhabitat choice, and therefore predation avoidance constrains optimal feeding. We hypothesize that the better ability of females than that of males to utilize the basal parts of the alga for growth is a co-adaptation to their risk-averse general reproductive strategy. We discuss the sexual differences in host plant utilization in the context of reproductive strategies of the sexes, especially different risk sensitivity of foraging, and its potential consequences on plant-herbivore interaction.     

The genomic footprint of climate adaptation in Chironomus riparius

The gradual heterogeneity of climatic factors poses varying selection pressures across geographic distances that leave signatures of clinal variation in the genome. Separating signatures of clinal adaptation from signatures of other evolutionary forces, such as demographic processes, genetic drift and adaptation, to nonclinal conditions of the immediate local environment is a major challenge. Here, we examine climate adaptation in five natural populations of the harlequin fly Chironomus riparius sampled along a climatic gradient across Europe. Our study integrates experimental data, individual genome resequencing, Pool‐Seq data and population genetic modelling. Common‐garden experiments revealed significantly different population growth rates at test temperatures corresponding to the population origin along the climate gradient, suggesting thermal adaptation on the phenotypic level. Based on a population genomic analysis, we derived empirical estimates of historical demography and migration. We used an F_ST outlier approach to infer positive selection across the climate gradient, in combination with an environmental association analysis. In total, we identified 162 candidate genes as genomic basis of climate adaptation. Enriched functions among these candidate genes involved the apoptotic process and molecular response to heat, as well as functions identified in studies of climate adaptation in other insects. Our results show that local climate conditions impose strong selection pressures and lead to genomic adaptation despite strong gene flow. Moreover, these results imply that selection to different climatic conditions seems to converge on a functional level, at least between different insect species.     

Role of cytosolic free calcium and phospholipase C in leukotriene-B4-stimulated secretion in human neutrophils. Comparison with the chemotactic peptide formyl-methionyl-leucyl-phenylalanine

Various leukotriene analogues were tested for their capacity to raise the cytosolic free calcium concentration, [Ca2+]i, and to stimulate exocytosis in human neutrophils. Their order of potency for both parameters was LTB4 greater than the stereochemical isomer of LTB4, (5S, 12S)-LTB4 much much greater than the sulphidopeptides LTD4, LTC4. The correlation between [Ca2+]i and secretion indicates that an increase of [Ca2+]i above a threshold level of about 300 nM is necessary for stimulating secretion with LTB4. This threshold is about an order of magnitude higher than that required for the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe). The increase in [Ca2+]i elicited by LTB4 was unaffected by increasing cellular cAMP, while secretion was completely inhibited. These results indicate, that similar to fMet-Leu-Phe, leukotrienes generate other signals in addition to [Ca2+]i elevations. Contrary to previous claims, leukotrienes stimulate polyphosphoinositide hydrolysis, as indicated by the increase in [3H]inositol trisphosphate, InsP3, observed upon stimulation of myo[3H]inositol-labelled neutrophils with LTB4 or (5S, 12S)-LTB4. The two InsP3 isomers [Ins(1,4,5)P3 and Ins(1,3,4P3] were separated by high-pressure liquid chromatographed and, as reported for other cell types, the formation of Ins(1,4,5)P3 precedes that of Ins(1,3,4)P3. Maximal stimulatory doses of LTB4 or (5S, 12S)-LTB4 produce about 50% the amount of InsP3 generated by equimolar concentrations of fMet-Leu-Phe. The present observations suggest that, though the transmembrane signalling systems activated by LTB4 and fMet-Leu-Phe are the same, the different efficacy of these two agonists at stimulating neutrophil functions is due, at least in part, to a different degree of activation of phospholipase C.