Length‐weight relationships of four fish species from the continental shelf of Yucatán (SW Gulf of México)

This paper presents length‐weight relationships (LWR) for four fish species from the continental shelf of Yucatán, at the Sonda de Campeche (southwestern Gulf of México). Samples were taken using shrimp trawl nets (5.71 cm squared mesh size in the cod‐end) in the mid‐summer of 2016. All LWRs were significant with r² values ranged from .946 to .994 and the values of exponent b, estimated using simple linear least squares of log‐transformed weight and length data, ranged from 2.54 to 3.10 (p < .001).     

Long‐term in situ persistence of biodiversity in tropical sky islands revealed by landscape genomics

Tropical mountains are areas of high species richness and endemism. Two historical phenomena may have contributed to this: (i) fragmentation and isolation of habitats may have promoted the genetic differentiation of populations and increased the possibility of allopatric divergence and speciation and (ii) the mountain areas may have allowed long‐term population persistence during global climate fluctuations. These two phenomena have been studied using either species occurrence data or estimating species divergence times. However, only few studies have used intraspecific genetic data to analyse the mechanisms by which endemism may emerge at the microevolutionary scale. Here, we use landscape analysis of genomic SNP data sampled from two high‐elevation plant species from an archipelago of tropical sky islands (the Trans‐Mexican Volcanic Belt) to test for population genetic differentiation, synchronous demographic changes and habitat persistence. We show that genetic differentiation can be explained by the degree of glacial habitat connectivity among mountains and that mountains have facilitated the persistence of populations throughout glacial/interglacial cycles. Our results support the ongoing role of tropical mountains as cradles for biodiversity by uncovering cryptic differentiation and limits to gene flow.     

Preprocessing of 2-Dimensional Gel Electrophoresis Images Applied to Proteomic Analysis: A Review

Various methods and specialized software programs are available for processing twodimensional gel electrophoresis(2-DGE)images.However,due to the anomalies present in these images,a reliable,automated,and highly reproducible system for 2-DGE image analysis has still not been achieved.The most common anomalies found in 2-DGE images include vertical and horizontal streaking,fuzzy spots,and background noise,which greatly complicate computational analysis.In this paper,we review the preprocessing techniques applied to 2-DGE images for noise reduction,intensity normalization,and background correction.We also present a quantitative comparison of non-linear?ltering techniques applied to synthetic gel images,through analyzing the performance of the?lters under speci?c conditions.Synthetic proteins were modeled into a two-dimensional Gaussian distribution with adjustable parameters for changing the size,intensity,and degradation.Three types of noise were added to the images:Gaussian,Rayleigh,and exponential,with signal-to-noise ratios(SNRs)ranging 8–20 decibels(d B).We compared the performanceof wavelet,contourlet,total variation(TV),and wavelet-total variation(WTTV)techniques using parameters SNR and spot ef?ciency.In terms of spot ef?ciency,contourlet and TV were more sensitive to noise than wavelet and WTTV.Wavelet worked the best for images with SNR ranging 10–20 d B,whereas WTTV performed better with high noise levels.Wavelet also presented the best performance with any level of Gaussian noise and low levels(20–14 d B)of Rayleigh and exponential noise in terms of SNR.Finally,the performance of the non-linear?ltering techniques was evaluated using a real 2-DGE image with previously identi?ed proteins marked.Wavelet achieved the best detection rate for the real image.     

Differential effects of FXR or TGR5 activation in cholangiocarcinoma progression

Background and aims

Cholangiocarcinoma (CCA) is an aggressive tumor type affecting cholangiocytes. CCAs frequently arise under certain cholestatic liver conditions. Intrahepatic accumulation of bile acids may facilitate cocarcinogenic effects by triggering an inflammatory response and cholangiocyte proliferation. Here, the role of bile acid receptors FXR and TGR5 in CCA progression was evaluated.

Rodents and insectivores from the late Miocene of Romerales (Fortuna Basin,Southern Spain)

Abstract

The Neogene Fortuna Basin (Murcia Region, SE Spain) is rich in microvertebrate sites. Its continental sections include localities extended from the middle Turolian (MN12) to the early Ruscinian (MN14). However, there are few works dealing with the taxonomy of these fossil assemblages. In this paper we provide a complete taxonomic study of the rodents and insectivores from three levels (ROM-2B, ROM-2C and ROM-3A) within the Romerales section. We infer a late Turolian age (late Messinian) for these levels, among which the richest and most diverse level is ROM-C, including at least 11 different taxa. In addition, the paleoecological analysis of these fossil assemblages suggests the dominance of open herbaceous meadows under temperate climate during the formation of these sites, with a slight decrease in temperature and humidity from ROM-2B to ROM-2C.     

Different protein kinase C isoforms are present in the yeast and mycelium forms of Sporothrix schenckii

Protein kinase C (PKC) plays an important role in the control of proliferation and differentiation of a wide range of cell types, and fungi are no exception. Previous results reported by us on the effects of the phorbol ester, 12-myristate-13-acetate phorbol (PMA) and other PKC effector molecules, on dimorphism in Sporothrix schenckii suggested the presence of this enzyme in the fungus and its involvement in the control of morphogenetic transitions. The work summarized here confirms the presence of PKC in yeast and mycelium extracts of S. schenckii. Different isoforms of this enzyme were found to be present in the yeast and mycelium forms of the fungus and were identified by Western blot analysis using affinity purified anti-PKC isoforms specific antibodies: the γ and ζ isoforms were detected in both the yeast and mycelium forms of the fungus, while the β isoform was only detected in the yeast form. The presence of PKC was confirmed biochemically by measuring total enzyme activity in both forms of the fungus. No significant differences were observed for the PKC activity level recorded for both the mycelium and yeast forms of the fungus (p ≤ 0.05). These data confirm the presence of PKC activity in Sporothrix schenckii and constitutes the first evidence concerning the differential expression of PKC isoforms in the mycelium and yeast forms of a dimorphic fungus, supporting the possible involvement of this important signal transduction enzyme in the control of morphogenesis in this fungus. This revised version was published online in June 2006 with corrections to the Cover Date.     

Unusual records of deepwater teleosteans trawled off the western coast of Mexico

The first records of three midwater species for the Mexican ichthyofauna (Holtbyrnia laticauda, Brama dussumieri and Cubiceps baxteri), caught off the coast of Baja California, Mexico, in mid 2014, are reported. As far as is known, they are the first verified specimens, geo‐referenced and catalogued in a reference fish collection for the west coast of Mexico. The species' known distributions were extended northward in the eastern Pacific Ocean, ranging from 3495 to 8300 km.     

Attenuation of apoptotic DNA fragmentation by amiloride

Amiloride is a K⁺-sparing diuretic that effectively inhibits the Na⁺/H⁺ transporter in the plasma membrane of most mammalian cells. We have examined the effects of amiloride on the progression of apoptosis in HL-60 cells induced by camptothecin (CAM), cycloheximide (CHX), and 20 Gy gamma irradiation. Spectrofluorometric measurements on cell populations showed an inhibition of Na⁺/H⁺ transporter activity and a corresponding decrease in intracellular pH following treatment with amiloride alone, or in combination with the apoptosis-inducing agents. Flow cytometric cell cycle analysis, in combination with DNA strand break analysis, indicated that amiloride diminished endonuclease-mediated degradation of nuclear chromatin 3 h following treatment with CAM or CHX, and prevented degradation for 3 h following gamma radiation treatment. Apoptosis-associated DNA degradation was significantly greater for all three agents in the absence of amiloride. Protection from radiation-induced apoptosis was transient, since apoptotic subpopulations were observed, but still at a decreased level, 5 h following irradiation. Amiloride was as effective as zinc, an inhibitor of Ca²⁺/Mg²⁺-dependent endonucleases, in reducing or delaying the onset of endonuclease activity. Data presented show that effects of amiloride on membrane Na⁺/H⁺ transporter activity and intracellular pH can potentially affect apoptotic signaling cascades, leading to a retardation in the rate of progression to an apoptotic cell death. Results also point to the involvement of intracellular pH and Ca²⁺ in the regulation of apoptotic endonuclease activity, and the need for a functional Na⁺/H⁺ exchanger for the induction of apoptosis. J. Cell. Physiol. 175:59–67, 1998. © 1998 Wiley-Liss, Inc.