Historical and contemporary determinants of global phylogenetic structure in tropical reef fish faunas

Identifying the main determinants of tropical marine biodiversity is essential for devising appropriate conservation measures mitigating the ongoing degradation of coral reef habitats. Based on a gridded distribution database and phylogenetic information, we compared the phylogenetic structure of assemblages for three tropical reef fish families (Labridae: wrasses, Pomacentridae: damselfishes and Chaetodontidae: butterflyfishes) using the net relatedness (NRI) and nearest taxon (NTI) indices. We then related these indices to contemporary and historical environmental conditions of coral reefs using spatial regression analyses. Higher levels of phylogenetic clustering were found for fish assemblages in the Indo‐Australian Archipelago (IAA), and more particularly when considering the NTI index. The phylogenetic structure of the Pomacentridae, and to a lower extent of the Chaeotodontidae and Labridae, was primarily associated with the location of refugia during the Quaternary period. Phylogenetic clustering in the IAA may partly result from vicariance events associated with coral reef fragmentation during the glacial periods of the Quaternary. Variation in the patterns among fish families further suggest that dispersal abilities may have interacted with past habitat availability in shaping the phylogenetic structure of tropical reef fish assemblages.     

Phylogeography of the Endangered Franciscana Dolphin: Timing and Geological Setting of the Evolution of Populations

Pontoporia blainvillei (Gervais & d’Orbigny, 1844), the franciscana dolphin, is the most endangered small cetacean in the Western South Atlantic. It is an endemic species with a coastal and estuarine distribution that has been divided into four Franciscana Management Areas (FMAs). We used the mitochondrial DNA control region to conduct a phylogeographic analysis to evaluate the population structure of the franciscana and the influence of paleoceanographic events on its biogeographic history. We found nine populations along the entire distribution (Φ_ST?=?0.41, Φ_CT?=?0.38, p?<?10^–5), with estimated migration rates resulting in less than one female per generation. Populations from FMAIII and FMAIV in the south (including the Río de La Plata Estuary) showed higher long-term migration rates and effective population sizes than northern populations. The phylogeographic analysis supports the franciscana origin in the Río de La Plata Estuary, with further dispersal south and northwards. The first lineage split happened around 2.5 Ma, with lineage radiation throughout the Pleistocene until recent fragmentation events shaped current-day populations. We suggest that Pleistocene glaciations influenced the dispersion and population structure of the franciscana. Specifically, that the shift of the Brazil-Malvinas Confluence drove the dispersion northwards. Then, low sea-level periods caused either the isolation in estuarine refugia or local extinctions, followed by re-colonizations.

     

Changes in serum markers indicative of health effects in vineyard workers following exposure to the fungicide mancozeb: an Italian study

The aim of this study was to investigate the health effects induced by exposure to the fungicide mancozeb in Italian vineyard workers. Ninety-three Italian subjects entered the study - 48 vine-growers intermittently exposed to mancozeb and 45 healthy controls. The subjects were investigated three times: before the seasonal application of pesticides (T0), 30 days after the beginning of the application period (T30), and 45 days after T0 (T45). At T0 the comparison between agricultural workers and controls showed a higher prevalence of cold or flu symptoms, a statistically significant lower percentage of monocytes, higher absolute count of T lymphocytes, CD4 and natural killer cells, and lower plasma levels of IgA and IgM in workers. Such differences were not confirmed at T30 and T45. In fact at T30 in exposed workers, besides a significant increase of urinary ethylenethiourea, confirming mancozeb exposure, T lymphocytes, CD4 and natural killer cells, IgA and IgM returned to values comparable to those observed in controls. Moreover, no other differences in clinical signs, haematological, and immune parameters, such as the immune functional capability evaluated as a response to hepatitis B vaccination, was observed. Altogether the differences between exposed and controls were not consistently correlated to any clinical impairment and suggest that the seasonal application of mancozeb does not pose a significant health risk to exposed subjects.     

G-quadruplex-induced instability during leading-strand replication

G-quadruplexes are four-stranded nucleic acid structures whose biological functions remain poorly understood. In the yeast S. cerevisiae, we report that G-quadruplexes form and, if not properly processed, pose a specific challenge to replication. We show that the G-quadruplex-prone CEB1 tandem array is tolerated when inserted near ARS305 replication origin in wild-type cells but is very frequently destabilized upon treatment with the potent Phen-DC(3) G-quadruplex ligand, or in the absence of the G-quadruplex-unwinding Pif1 helicase, only when the G-rich strand is the template of leading-strand replication. The orientation-dependent instability is associated with the formation of Rad51-Rad52-dependent X-shaped intermediates during replication detected by two-dimensional (2D) gels, and relies on the presence of intact G-quadruplex motifs in CEB1 and on the activity of ARS305. The asymmetrical behaviour of G-quadruplex prone sequences during replication has implications for their evolutionary dynamics within genomes, including the maintenance of G-rich telomeres.     

Application of gas chromatography-mass spectrometry for the determination of urinary ethylenethiourea in humans

Ethylenethiourea (ETU) is a major metabolite of ethylenebisdithiocarbamate pesticides: a sensitive and specific assay for its determination in human urine is proposed below. ETU is extracted on a diatomaceous earth column using dichloromethane and derivatized with the mixture of N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide and tert-butyldimethyilsilyl chloride. The derivative is analyzed using GC/MS in the EI/SIM mode. The whole procedure is carried out in the presence of ethylenethiourea-d(4) as internal standard. The analytical features of the method are: high specificity, >90% recovery, range of linearity 0-200 microg/L, within- and between-run precision as coefficient of variation, <17 and <20%, respectively, limit of quantification 2 microg/L. In specimens stored in the dark at -20 degrees C ETU is stable for at least 6 months. The procedure was successfully applied to the biological monitoring of vineyard workers exposed to EBDTC and of a matched group of subjects from the general population.     

Biological monitoring of pesticide exposure: a review of analytical methods

A wide range of studies concerned with analytical methods for biological monitoring of exposure to pesticides is reviewed. All phases of analytical procedures are assessed, including sampling and storage, sample preparation and analysis, and validation of methods. Most of the studies aimed at measuring metabolites or unchanged compounds in urine and/or blood as biological indicators of exposure or dose. Biological indicators of effect, such as cholinesterase, are also evaluated. The principal groups of pesticides are considered: organophosphorus pesticides, carbamate pesticides, organochlorine pesticides, pyrethroid pesticides, herbicides, fungicides and other compounds. Choice of the method for biological monitoring of exposure depends on the study population: a detection limit of 1 microg/l or less is required for the general population; higher values are adequate for occupationally exposed subjects. Interpretation of results is also discussed. Since biological indices of exposure are only available for a few compounds, biological reference values, established for the general population, may be used for comparison with levels of professionally exposed subjects.