PubMed · 13734306
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P PERET. 1961. [Adaptometry and glaucoma].. https://pubmed.ncbi.nlm.nih.gov/13734306/
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Understanding the genetic bases and modes of adaptation to current climatic conditions is essential to accurately predict responses to future environmental change. We conducted a genome-wide scan to identify climate-adaptive genetic loci and pathways in the plant Arabidopsis thaliana. Amino acid-changing variants were significantly enriched among the loci strongly correlated with climate, suggesting that our scan effectively detects adaptive alleles. Moreover, from our results, we successfully predicted relative fitness among a set of geographically diverse A. thaliana accessions when grown together in a common environment. Our results provide a set of candidates for dissecting the molecular bases of climate adaptations, as well as insights about the prevalence of selective sweeps, which has implications for predicting the rate of adaptation.
Ouabain, a cardiac glycoside and inhibitor of Na(+), K(+)-ATPase, is now believed to be a steroid hormone in mammals, involved in blood pressure and volume regulation and possibly acting as a natriuretic hormone. We have identified ouabain-like immunoreactivity in the plasma and tissues of a euryhaline teleost, the tilapia (Oreochromis mossambicus), by means of solid-phase extraction followed by a specific radioimmunoassay. Plasma concentrations of immunoreactive ouabain were 5-20pg/ml. Ouabain immunoreactivity was detected in all the tissues examined, with highest concentrations in the head kidney followed by intestine and body kidney. When the fish in fresh water were transferred to seawater, plasma osmolality increased significantly after 2, 4, 8, and 24h. Significant increases were observed in plasma ouabain immunoreactivity after 4 and 24h, and a significant correlation was seen between ouabain immunoreactivity and plasma osmolality. There was also a significant correlation between the plasma osmolality and cortisol concentrations. Upon transfer from seawater to fresh water, significant increases were seen in plasma cortisol after 4 and 8h and in immunoreactive ouabain after 4h. When the correlation was analyzed using all the data obtained during the two transfer experiments, plasma ouabain immunoreactivity and cortisol were significantly correlated with plasma osmolality, whereas there was a significant negative correlation between plasma prolactin and osmolality. A significant positive correlation was also seen between plasma cortisol and ouabain immunoreactivity. These results suggest that immunoreactive ouabain may be involved, together with cortisol, in the maintenance of hydromineral balance in the tilapia.
Acute mountain sickness (AMS) commonly occurs at altitudes exceeding 2000-2500 m and usually resolves after acclimatization induced by a few days of chronic residence at the same altitude. Increased ventilation and diuresis may contribute to the reduction in AMS with altitude acclimatization. The aim of the present study was to examine the effects of intermittent altitude exposures (IAE), in combination with rest and exercise training, on the incidence and severity of AMS, resting ventilation and 24-h urine volume at 4300 m. Six lowlanders (age, 23 +/- 2 years; body weight, 77 +/- 6 kg; values are means +/- S.E.M.) completed an Environmental Symptoms Questionnaire (ESQ) and Lake Louise AMS Scoring System (LLS), a resting end-tidal partial pressure of CO2 ( PETCO2) test and a 24-h urine volume collection at sea level (SL) and during a 30 h exposure to 4300 m altitude-equivalent (barometric pressure=446 mmHg) once before (PreIAE) and once after (PostIAE) a 3-week period of IAE (4 h.day(-1), 5 days.week(-1), 4300 m). The previously validated factor score, AMS cerebral score, was calculated from the ESQ and the self-report score was calculated from the LLS at 24 h of altitude exposure to assess the incidence and severity of AMS. During each IAE, three subjects cycled for 45-60 min.day(-1) at 60-70% of maximal O2 uptake (VO2 max) and three subjects rested. Cycle training during each IAE did not affect any of the measured variables, so data from all six subjects were combined. The results showed that the incidence of AMS (%), determined from both the ESQ and LLS, increased (P<0.05) from SL (0 +/- 0) to PreIAE (50 +/- 22) at 24 h of altitude exposure and decreased (P<0.05) from PreIAE to PostIAE (0 +/- 0). The severity of AMS (i.e. AMS cerebral symptom and LLS self-report scores) increased (P<0.05) from SL (0.02 +/- 0.02 and 0.17 +/- 0.17 respectively) to PreIAE (0.49 +/- 0.18 and 4.17 +/- 0.94 respectively) at 24 h of altitude exposure, and decreased (P<0.05) from PreIAE to PostIAE (0.03 +/- 0.02 and 0.83 +/- 0.31 respectively). Resting PETCO2 (mmHg) decreased (i.e. increase in ventilation; P<0.05) from SL (38 +/- 1) to PreIAE (32 +/- 1) at 24 h of altitude exposure and decreased further (P<0.05) from PreIAE to PostIAE (28 +/- 1). In addition, 24-h urine volumes were similar at SL, PreIAE and PostIAE. In conclusion, our findings suggest that 3 weeks of IAE provide an effective alternative to chronic altitude residence for increasing resting ventilation and reducing the incidence and severity of AMS.