The combined impact of metabolic gene polymorphisms on elite endurance athlete status and related phenotypes

Endurance performance is a complex phenotype subject to the influence of both environmental and genetic factors. Although the last decade has seen a variety of specific genetic factors proposed, many in metabolic pathways, each is likely to make a limited contribution to an ‘elite’ phenotype: it seems more likely that such status depends on the simultaneous presence of multiple such variants. The aim of the study was to investigate individually and in combination the association of common metabolic gene polymorphisms with endurance athlete status, the proportion of slow-twitch muscle fibers and maximal oxygen consumption. A total of 1,423 Russian athletes and 1,132 controls were genotyped for 15 gene polymorphisms, of which most were previously reported to be associated with athlete status or related intermediate phenotypes. Muscle fiber composition of m. vastus lateralis in 45 healthy men was determined by immunohistochemistry. Maximal oxygen consumption of 50 male rowers of national competitive standard was determined during an incremental test to exhaustion on a rowing ergometer. Ten ‘endurance alleles’ (NFATC4 Gly160, PPARA rs4253778 G, PPARD rs2016520 C, PPARGC1A Gly482, PPARGC1B 203Pro, PPP3R1 promoter 5I, TFAM 12Thr, UCP2 55Val, UCP3 rs1800849 T and VEGFA rs2010963 C) were first identified showing discrete associations with elite endurance athlete status. Next, to assess the combined impact of all 10 gene polymorphisms, all athletes were classified according to the number of ‘endurance’ alleles they possessed. The proportion of subjects with a high (≥9) number of ‘endurance’ alleles was greater in the best endurance athletes compared with controls (85.7 vs. 37.8%, P = 7.6 × 10^?6). The number of ‘endurance’ alleles was shown to be positively correlated (r = 0.50; P = 4.0 × 10^?4) with the proportion of fatigue-resistant slow-twitch fibers, and with maximal oxygen consumption (r = 0.46; P = 7.0 × 10^?4). These data suggest that the likelihood of becoming an elite endurance athlete depends on the carriage of a high number of endurance-related alleles.     

Diversity and Persistence of Ectomycorrhizal Fungi and Their Effect on Nursery-Inoculated Pinus pinaster in a Post-fire Plantation in Northern Portugal

Ectomycorrhizal fungi (ECMF) play an important role in forest ecosystems, often mitigating stress factors and increasing seedling performance. The aim of this study was to investigate the effects of a nursery inoculation on Pinus pinaster growth and on the fungal communities established when reforesting burned areas. Inoculated P. pinaster saplings showed 1.5-fold higher stem height than the non-inoculated controls after a 5 year growth period, suggesting that fungal inoculation could potentiate tree growth in the field. Ordination analysis revealed the presence of different ECMF communities on both plots. Among the nursery-inoculated fungi, Laccaria sp., Rhizopogon sp., Suillus bovinus and Pisolithus sp. were detected on inoculated Pinus saplings on both sampling periods, indicating that they persisted after field establishment. Other fungi were also detected in the inoculated plants. Phialocephala sp. was found on the first assessment, while Terfezia sp. was detected on both sampling periods. Laccaria sp. and Rhizopogon sp. were identified in the control saplings, belonging however to different species than those found in the inoculated plot. Inocybe sp., Thelephora sp. and Paxillus involutus were present on both sampling periods in the non-inoculated plots. The results suggest that ECMF inoculation at nursery stage can benefit plant growth after transplantation to a post-fire site and that the inoculated fungi can persist in the field. This approach has great potential as a biotechnological tool to aid in the reforestation of burned areas.     

The N-terminal domains of myosin binding protein C can bind polymorphically to F-actin

The regulation of vertebrate striated muscle contraction involves a number of different molecules, including the thin-filament accessory proteins tropomyosin and troponin that provide Ca²⁺-dependent regulation by controlling access to myosin binding sites on actin. Cardiac myosin binding protein C (cMyBP-C) appears to modulate this Ca²⁺-dependent regulation and has attracted increasing interest due to links with inherited cardiac diseases. A number of single amino acid mutations linked to clinical diseases occur in the N-terminal region of cMyBP-C, including domains C0 and C1, which previously have been shown to bind to F-actin. This N-terminal region also has been shown to both inhibit and activate actomyosin interactions in vitro. Using electron microscopy and three-dimensional reconstruction, we show that C0 and C1 can each bind to the same two distinctly different positions on F-actin. One position aligns well with the previously reported binding site that clashes with the binding of myosin to actin, but would force tropomyosin into an “on” position that exposes myosin binding sites along the filament. The second position identified here would not interfere with either myosin binding or tropomyosin positioning. It thus appears that the ability to bind to at least two distinctly different positions on F-actin, as observed for tropomyosin, may be more common than previously considered for other actin binding proteins. These observations help to explain many of the seemingly contradictory results obtained with cMyBP-C and show how cMyBP-C can provide an additional layer of regulation to actin-myosin interactions. They also suggest a redundancy of C0 and C1 that may explain the absence of C0 in skeletal muscle.     

Patterns of selection on Plasmodium falciparum erythrocyte‐binding antigens after the colonization of the New World

Pathogens, which have recently colonized a new host species or new populations of the same host, are interesting models for understanding how populations may evolve in response to novel environments. During its colonization of South America from Africa, Plasmodium falciparum, the main agent of malaria, has been exposed to new conditions in distinctive new human populations (Amerindian and populations of mixed origins) that likely exerted new selective pressures on the parasite's genome. Among the genes that might have experienced strong selective pressures in response to these environmental changes, the eba genes (erythrocyte‐binding antigens genes), which are involved in the invasion of the human red blood cells, constitute good candidates. In this study, we analysed, in South America, the polymorphism of three eba genes (eba‐140, eba‐175, eba‐181) and compared it to the polymorphism observed in African populations. The aim was to determine whether these genes faced selective pressures in South America distinct from what they experienced in Africa. Patterns of genetic variability of these genes were compared to the patterns observed at two housekeeping genes (adsl and serca) and 272 SNPs to separate adaptive effects from demographic effects. We show that, conversely to Africa, eba‐140 seemed to be under stronger diversifying selection in South America than eba‐175. In contrast, eba‐181 did not show any sign of departure from neutrality. These changes in the patterns of selection on the eba genes could be the consequence of changes in the host immune response, the host receptor polymorphisms and/or the ability of the parasite to silence or express differentially its invasion proteins.     

Lead exposure on critical days of fetal life affects fertility in the female mouse

Female mice were exposed to lead in utero by intravenous injection of lead chloride into the mothers at different stages of pregnancy. At a mature age the mice exposed as fetuses (F1 generation) conceived at a normal rate, but the litter size and fetal survival varied significantly. Small litters and increased numbers of fetal deaths were observed in mice exposed to lead on day 8 of intrauterine life. The live fetuses in this group were normal with respect to weight and morphological appearance. Serum levels of estradiol and progesterone, measured on day 17 of pregnancy, did not differ significantly between F1 mice of a control, unexposed group and of the group exposed to lead on day 8 of intrauterine life. Ovarian follicle counts revealed a significantly smaller number of primordial follicles in the latter group. It is suggested that the exposure to lead at a time of early organogenesis caused the observed fertility decrease by interfering with the development of the female germ cells.     

Gonadotrophin-releasing hormone treatment for induction of follicular maturation and ovulation in amenorrhoeic women with anorexia nervosa.

Follicular maturation and ovulation can be induced in amenorrhoeic women with anorexia nervosa by long-term treatment with 500 mug of luteinizing hormone releasing hormone (LH-RH) every eight hours. In some women, however, treatment with LH-RH alone results in ovulatory menstrual cycles with indications of luteal phase insufficiency. Human chorionic gonadotrophin (HCG) was therefore given with LH-RH during three treatment cycles. This resulted in ovulation and normal corpus-luteum function, as shown by the occurrence of a single pregnancy in the only involuntarily sterile patient. During the prolonged LH-RH treatment the LH response to LH-RH increased in parallel with the increased oestrogen secretion while the follicle-stimulating hormone response to LH-RH decreased. These changes in the pituitary responsiveness to LH-RH may result from modulating effects on the pituitary by the sex steroids.     

Regulation of macrophage physiology by L-arginine: role of the oxidative L-arginine deiminase pathway

The L-arginine content of the extracellular fluid in sites of predominant macrophage infiltration is reduced below plasma levels due to the activity of macrophage-derived arginase. Investigation of the effects of altered L-arginine availability on macrophage physiology reveals that culture of rat peritoneal macrophages in media containing L-arginine in the concentrations present in inflammatory lesions (less than 0.1 mM) enhances activation-associated functions. In contrast, culture in the higher L-arginine concentrations found in standard tissue culture media (0.4 to 1.2 mM) suppresses most macrophage functions (superoxide production, phagocytosis, and protein synthesis). An exception is the tumor cytotoxicity of Corynebacterium parvum-elicited macrophages which is enhanced by culture in supraphysiologic concentrations of L-arginine. Work reported here investigated the mechanisms for these L-arginine-dependent effects and, more specifically, the role of the recently described oxidative L-arginine deiminase pathway in the regulation of macrophage physiology. Overnight culture of resident or C. parvum-elicited peritoneal macrophages in media containing increasing concentrations of L-arginine (6 microM to 1 mM) resulted in: inhibition of electron transport chain activity (resident and C. parvum-elicited macrophages), increased lactate production (resident macrophages), and decreased ATP content (resident and C. parvum-elicited macrophages). In line with these findings, viability was markedly decreased after 2 days of culture when the initial L-arginine concentration was greater than or equal to 0.1 mM. As shown before, increasing media concentrations of L-arginine were associated with suppression of superoxide production and cytotoxicity in resident macrophages, and with reduced superoxide production and increased cytotoxicity in C. parvum-elicited macrophages. All L-arginine-dependent metabolic and functional alterations, as well as the loss of viability, were prevented by NG-monomethyl-L-arginine, a specific inhibitor of the oxidative L-arginine deiminase pathway. These results demonstrate that flux of L-arginine through the oxidative L-arginine deiminase pathway results in the inhibition of oxidative metabolism in rat macrophages. This metabolic inhibition may, through alterations in the macrophage high energy phosphate stores, mediate the suppression of cell functions and result ultimately in cell death.     

Recombinant production and solution structure of lipid transfer protein from lentil Lens culinaris

Lipid transfer protein, designated as Lc-LTP2, was isolated from seeds of the lentil Lens culinaris. The protein has molecular mass 9282.7 Da, consists of 93 amino acid residues including 8 cysteines forming 4 disulfide bonds. Lc-LTP2 and its stable isotope labeled analogues were overexpressed in Escherichia coli and purified. Antimicrobial activity of the recombinant protein was examined, and its spatial structure was studied by NMR spectroscopy. The polypeptide chain of Lc-LTP2 forms four α-helices (Cys4-Leu18, Pro26-Ala37, Thr42-Ala56, Thr64-Lys73) and a long C-terminal tail without regular secondary structure. Side chains of the hydrophobic residues form a relatively large internal tunnel-like lipid-binding cavity (van der Waals volume comes up to ∼600 Å³). The side-chains of Arg45, Pro79, and Tyr80 are located near an assumed mouth of the cavity. Titration with dimyristoyl phosphatidylglycerol (DMPG) revealed formation of the Lc-LTP2/lipid non-covalent complex accompanied by rearrangements in the protein spatial structure and expansion of the internal cavity. The resultant Lc-LTP2/DMPG complex demonstrates limited lifetime and dissociates within tens of hours.