Whole-Genome Sequencing of Two Moroccan Mycobacterium tuberculosis Strains.

Mycobacterium tuberculosis is known to cause pulmonary and extrapulmonary tuberculosis. In Morocco, the spread of multidrug-resistant (MDR) tuberculosis (TB) has become a major challenge. Here, we announce the draft genome sequences of two Mycobacterium tuberculosis strains, MTB1 and MTB2, isolated from patients with pulmonary tuberculosis in Morocco, to describe variants associated with drug resistance.

Annotated Whole-Genome Shotgun Sequence of Multidrug-Resistant Mycobacterium tuberculosis MTB13_M Isolated from Morocco.

Here, we describe the annotated genome sequence of Mycobacterium tuberculosis MTB13_M. The organism was isolated from a sputum sample in Morocco.

Determination of NH4+/NH3 fluxes across apical membrane of macula densa cells: a quantitative analysis.

Luminal addition of 20 mM NH4+ produced a rapid acidification of rabbit macula densa (MD) cells from 7.50 +/- 0.06 to 6.91 +/- 0.05 at an initial rate of 0.071 +/- 0.008 pH unit/s. In the luminal presence of 5 microM bumetanide, 5 mM Ba2+ or both, the acidification rate was reduced by 57%, 35% and 93% of control levels. In contrast, intracellular pH (pHi) recovery after removing luminal NH4+ was unaffected by bumetanide and Ba2+ but was sensitive to 1 mM luminal amiloride (71% inhibition). The bumetanide-sensitive acidification rate represents most certainly the NH4+ flux mediated by the apical Na+:K+ (NH4+):2Cl- cotransporter, but the Ba(2+)-sensitive portion does not seem to be associated with the apical K+ channels previously characterized by us. The effects of NH4+ entry across the apical membrane were simulated using a simple model involving five adjustable parameters: apical and basolateral permeabilities for NH4+ and NH3 and a parameter describing a pH-regulating mechanism. The model shows that the apical membrane of MD cells is much more permeable to NH3 than it is to NH4+ and, under control conditions, the apical NH4+ flux appears surprisingly high (11-20 mM/s) and challenges the notion that MD cells present a low intensity of ionic transport.

Transport and regulatory properties of the apical Na-K-2Cl cotransporter of macula densa cells.

NH+4/NH3 fluxes were used to probe apical Na-K-2Cl transport activity of macula densa (MD) cells from rabbit kidney. In the presence of 25 mM NaCl and 5 mM Ba2+, addition of 20 mM NH+4 to the lumen produced a profound intracellular acidification, and approximately 80% of the initial acidification rate was bumetanide sensitive. The NH+4-induced acidification rate was dependent on luminal Cl- and Na+ with apparent affinities of 17 +/- 4 mM (Hill number 1.45) and 1.0 +/- 0.3 mM, respectively. In the presence of saturating luminal NaCl concentration ([NaCl]L), blockade of basolateral Cl- efflux with 10 microM 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) reduced the NH+4-induced acidification rate by 51 +/- 6% (P > 0.01, n = 5). Under similar conditions, dibutyryl-cAMP (DBcAMP) + forskolin increased the NH+4-induced acidification rate by 27%, whereas it produced no detectable effect at low luminal NaCl concentration. Most of the observed DBcAMP + forskolin effect was probably due to the stimulation of the basolateral Cl- conductance, since, in the presence of basolateral NPPB, this activation was changed to a 17.1% and 16.6% inhibition of the NH+4-induced acidification rate observed at high or low [NaCl]L, respectively. We conclude that the cotransporter found in MD cells displays, with respect to other Na-K-2Cl cotransporters, a relatively high affinity for luminal Na+ and luminal Cl- and can be specifically inhibited by increases in intracellular Cl- and cAMP concentrations.

[The effect of glucocorticoids on the diluting capacity of the kidney of a desert rodent: Gerbillus campestris]. / Effet des glucocorticoïdes sur la capacité de dilution du rein chez un rongeur désertique: Gerbillus campestris.

The ability to excrete a water load was studied in Wistar rats and in gerbils (Gerbillus campestris). The rat excreted the entire water load in less than 2 h whereas Gerbillus campestris excreted less than 60% of the water load in 4 h. The gerbils which had received a dose of 15 micrograms/100 g body weight dexamethasone improved their rate of excretion which attained 92 +/- 6% in 2 h 30 min. The antidiuretic hormone (ADH) measured by radioimmunoassay at the time of maximum diuresis was undetectable in rats; in contrast, in gerbils the level of ADH remained relatively high (55.4 +/- 6.7 pg/ml). We conclude that the partial inability of the gerbil's kidney to excrete a water load is due to a high ADH level and probably to a low concentration of glucocorticoids.