Coral Uptake of Inorganic Phosphorus and Nitrogen Negatively Affected by Simultaneous Changes in Temperature and pH

The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i) at three pHT conditions (8.1, 7.8, and 7.5) and normal temperature (26°C), ii) at three temperature conditions (26°, 29°C, and 33°C) and normal pHT (8.1), and iii) at three pHT conditions (8.1, 7.8, and 7.5) and elevated temperature (33°C). After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pHT 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C) alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C) and low pHT (7.5) resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pHT = 8.1). These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification

Cdna Cloning of a Rat Small-Intestinal Na+/so42- Cotransporter

We have isolated a cDNA (ileal NaSi-1) from rat small intestine by homology screening with a cDNA (renal NaSi-1) encoding rat kidney cortex Na+-SO42- cotransport. Ileal NaSi-1 cRNA specifically stimulates Na+-dependent SO42- uptake in a time- and dose-depen dent manner in Xenopus laevis oocytes, with kinetic parameters almost identical to those of the renal NaSi-1. Ileal NaSi-1 cDNA contains 2722 base pairs (bp), almost 500bp more than the renal NaSi-1 cDNA; however, it encodes a protein of 595 amino acids identical to the renal NaSi-1 protein. Northern blot analysis shows strong signals in rat lower small intestine and kidney cortex (2.9 x 10(3) and 2.3 x 10(3) bases), with the ileal NaSi-1 corresponding to the longer transcript. We conclude that we have identified a rat ileal cDNA that encodes a membrane protein most likely involved in brush-border Na+-SO42- cotransport. It differs to the renal NaSi-1 only in the length of the 3' untranslated region, suggesting that the major difference lies in the differential use of polyadenylation signal

Expression of Rat Ileal Na+-Sulfate Cotransport in Xenopus-Laevis Oocytes - Functional-Characterization

Small-intestinal sulphate absorption is a Na+-dependent process having its highest rate in the ileum; it involves brush-border membrane Na+-sulphate cotransport. Injection of rat ileal mRNA into Xenopus laevis oocytes induced Na+-dependent sulphate uptake in a dose-dependent manner, with no apparent effect on Na+-independent sulphate uptake. For mRNA-induced transport, the apparent K-m value for sulphate interaction was 0.6 +/- 0.2 mM and that for sodium interaction was 25 +/- 2 mM (Hill coefficient: 2.3 +/- 0.3). mRNA-induced transport, was inhibited by thiosulphate, but not by phosphate or 4,4,'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS). Using a rat renal Nac-sulphate cotransporter cDNA as a probe [NaSi-1; Markovich et al. (1993) Proc Natl Acad Sci USA 90:8073 - 8077], the highest hybridization signals (2.3 kb and 2.9 kb) were obtained in size fractions showing the highest expression of Na+-dependent sulphate transport in oocytes. Hybrid depletion experiments using antisense oligonucleotides (from the NaSi-1 cDNA sequence), provided further evidence that rat small-intestinal (ileal) Na+-sulphate cotransport is closely related to rat proximal-tubular brush-border membrane Na+-sulphate cotranspor

Utilidad de la distancia recorrida en una prueba de ejercicio incremental como predictor de morbilidad postoperatoria en la resección del cáncer de pulmón. Abordaje multidisciplinar: cirugía torácica – anestesiología

[ES] El cáncer de pulmón no microcítico es hoy en día la primera causa de mortalidad por enfermedad neoplásica en hombres.[EN] The non-small cell lung cancer is now the leading cause of death from malignant disease in men