Insights into the origin and distribution of biodiversity in the Brazilian Atlantic forest hot spot: a statistical phylogeographic study using a low-dispersal organism.

The relative importance of the processes that generate and maintain biodiversity is a major and controversial topic in evolutionary biology with large implications for conservation management. The Atlantic Forest of Brazil, one of the world's richest biodiversity hot spots, is severely damaged by human activities. To formulate an efficient conservation policy, a good understanding of spatial and temporal biodiversity patterns and their underlying evolutionary mechanisms is required. With this aim, we performed a comprehensive phylogeographic study using a low-dispersal organism, the land planarian species Cephaloflexa bergi (Platyhelminthes, Tricladida). Analysing multi-locus DNA sequence variation under the Approximate Bayesian Computation framework, we evaluated two scenarios proposed to explain the diversity of Southern Atlantic Forest (SAF) region. We found that most sampled localities harbour high levels of genetic diversity, with lineages sharing common ancestors that predate the Pleistocene. Remarkably, we detected the molecular hallmark of the isolation-by-distance effect and little evidence of a recent colonization of SAF localities; nevertheless, some populations might result from very recent secondary contacts. We conclude that extant SAF biodiversity originated and has been shaped by complex interactions between ancient geological events and more recent evolutionary processes, whereas Pleistocene climate changes had a minor influence in generating present-day diversity. We also demonstrate that land planarians are an advantageous biological model for making phylogeographic and, particularly, fine-scale evolutionary inferences, and propose appropriate conservation policies.

Land planarians (Platyhelminthes) as a model organism for fine-scale phylogeographic studies: understanding patterns of biodiversity in the Brazilian Atlantic Forest hotspot.

The Brazilian Atlantic Forest is one of the richest biodiversity hotspots of the world. Paleoclimatic models have predicted two large stability regions in its northern and central parts, whereas southern regions might have suffered strong instability during Pleistocene glaciations. Molecular phylogeographic and endemism studies show, nevertheless, contradictory results: although some results validate these predictions, other data suggest that paleoclimatic models fail to predict stable rainforest areas in the south. Most studies, however, have surveyed species with relatively high dispersal rates whereas taxa with lower dispersion capabilities should be better predictors of habitat stability. Here, we have used two land planarian species as model organisms to analyse the patterns and levels of nucleotide diversity on a locality within the Southern Atlantic Forest. We find that both species harbour high levels of genetic variability without exhibiting the molecular footprint of recent colonization or population expansions, suggesting a long-term stability scenario. The results reflect, therefore, that paleoclimatic models may fail to detect refugia in the Southern Atlantic Forest, and that model organisms with low dispersal capability can improve the resolution of these models.

Health effects associated with Madrid air pollution levels.

The purpose of this study was to determine the relationship between the pollution levels recorded in Madrid and the number of hospital admissions made on the grounds of respiratory disorders.

Neonatal hypothyroxinemia: effects of iodine intake and premature birth.

We have investigated the effects of iodine (I) intake on urinary I excretion in preterm (PT) babies up to 2 months after birth and its effect on serum T4, free T4 (FT4), T3, TSH, and thyroglobulin (Tg) levels compared to those in term (T) newborns. Very premature and very sick infants were in negative I balance for the first weeks after birth. Later, these same infants, as well as the other PT and T newborns, were in positive balance; 75- 80% of the ingested I was not accounted for in the urine. The urinary I levels of PT and T neonates cannot be equated to their I intakes. T4, FT4, and T3 levels in PT and T neonates increased with postmenstrual age, whereas Tg decreased and TSH did not change. Serum FT4, T3, Tg, and TSH levels in PT neonates were affected negatively, independently from age, by a low I intake. PT birth also affected T4, FT4, and Tg negatively, independently from I intake and postmenstrual age, for at least 6-8 weeks after birth. Care should be taken to avoid I deficiency in PT neonates. However, even when I intake is adequate, PT newborns are hypothyroxinemic compared to T babies during an important period of brain development. This suggests the possible convenience of interventions that might mimic the intrauterine hormone environment and accelerate maturation.

B and C types natriuretic peptides modify norepinephrine uptake and release in the rat adrenal medulla.

We have previously reported that atrial natriuretic factor (ANF) modulates adrenomedullar norepinephrine (NE) metabolism. On this basis, the aim of the present work was to study the effects of B and C types natriuretic peptides (BNP and CNP) on the uptake, intracellular distribution and release of 3H-NE. Experiments were carried out in rat adrenal medulla slices incubated "in vitro." Results showed that 100 nM of both, CNP and BNP, enhanced total and neuronal NE uptake. Both peptides (100 nM) caused a rapid increase in NE uptake during the first minute, which was sustained for 60 min. NE intracellular distribution was only modified by CNP (100 nM), which increased the granular fraction and decreased the cytosolic pool. On the other hand, spontaneous as well as evoked (KCl) NE release, was decreased by BNP and CNP (50 and 100 nM for spontaneous release and 1, 10, 50 and 100 nM for evoked output). The present results suggest that BNP and CNP may regulate catecholamine secretion and modulate adrenomedullary biological actions mediated by catecholamines, such as blood arterial pressure, smooth muscle tone, and metabolic activities.

B and C types natriuretic peptides modulate norepinephrine uptake and release in the rat hypothalamus.

We previously reported that atrial natriuretic factor (ANF) regulates catecholamine metabolism in the central nervous system. ANF, B and C types natriuretic peptides (BNP and CNP) also play a regulatory role in body fluid homeostasis, cardiovascular activity and hormonal and neuro-hormonal secretions. The aim of the present work was to investigate BNP and CNP effects on the uptake and release of norepinephrine (NE) in rat hypothalamic slices incubated in vitro. Results showed that BNP (100 nM) and CNP (1, 10 and 100 nM) enhanced total and neuronal [3H]NE uptake but did not modify non-neuronal uptake. BNP (100 nM) and CNP (1 nM) caused a rapid increase in NE uptake (1 min), which was sustained for 60 min. BNP (100 nM) did not modify the intracellular distribution of NE; however, 1 nM CNP increased the granular store and decreased the cytosolic pool of NE. BNP (100 nM) and CNP (1, 10 and 100 nM), diminished spontaneous NE release. In addition, BNP (1, 10, 100 nM) and CNP (1, 10 and 100 pM, as well as 1, 10 and 100 nM) reduced NE output induced by 25 mM KCl. These results suggest that BNP and CNP may be involved in the regulation of several central as well as peripheral physiological functions through the modulation of noradrenergic neurotransmission at the presynaptic neuronal level. Present results provide evidence to consider CNP as the brain natriuretic peptide since physiological concentrations of this peptide (pM) diminished NE evoked release.

Iodine content of infant formulas and iodine intake of premature babies: high risk of iodine deficiency.

As part of a study of thyroid function in premature babies, the iodine content of their mothers' breast milk, that of 32 formulas from different brands used in Spain, and that of 127 formulas used in other countries was determined. Breast milk contained more iodine--mean (SEM) 10 (1) microgram/dl--than most of the formulas, especially those for premature babies. Iodine intakes were therefore below the recommended daily amount (RDA) for newborns: babies of 27-30 weeks' gestational age took 3.1 (1.1) micrograms/day at 5 days of age and 29.8 (2.7) micrograms by 2 months of age. This problem is not exclusive to Spanish premature babies as the iodine content of many of the formulas on sale in other countries was also inadequate. It is concluded that preterm infants who are formula fed are at high risk of iodine deficiency.

Enantioselective S-oxygenation of para-methoxyphenyl-1,3-dithiolane by various tissue preparations: effect of estradiol.

Liver, kidney, and lung microsomes prepared from nonpretreated female Sprague-Dawley rats catalyze the NADPH- and oxygen-dependent S-oxygenation of para-methoxyphenyl-1,3-dithiolane. Studies on the biochemical mechanism of dithiolane S-oxygenation in liver, kidney, and lung microsomes suggest that this reaction is catalyzed in a diastereoselective and enantioselective fashion by the flavin-containing monooxygenase and, to a lesser extent, the cytochromes P-450. This conclusion is based on results examining the effects of selective cytochrome P-450 inhibitors and positive effectors, microsome heat-inactivation treatment, and alternate substrates for the flavin-containing monooxygenase. Liver and kidney microsomes prepared from ovarectomized female rats tended to have decreased S-oxygenase activity, compared with nonpretreated female rats, whereas ovarectomized rats pretreated with estradiol had markedly lower S-oxygenase activity. In contrast, lung microsomal S-oxygenase activity, which is low in pulmonary microsomes from nonpretreated female rats, increases 2-4-fold after ovariectomization and estradiol pretreatment. In female Sprague-Dawley rats, estradiol pretreatment is mainly responsible for the large decrease (or increase) in S-oxygenase activity observed in the tissues examined, although it is unlikely that estradiol alone controls flavin-containing monooxygenase S-oxygenase activity.