Weight–length relationships for 38 fish species of Barra de Navidad coastal lagoon,Jalisco, Mexico

Weight–length relationships are reported for 38 species of teleost fish belonging to 20 families. Data were collected on a regular basis from February 2011 to January 2012 in the Barra de Navidad coastal lagoon, Jalisco, Mexico. Several different types of sampling gear were used to obtain a broad range of fish lengths. These are the first records in FishBase regarding weight–lengths for eight of the species.     

Uncovering species boundaries in the Neotropical ant complex Ectatomma ruidum (Ectatomminae) under the presence of nuclear mitochondrial paralogues

Nuclear mitochondrial (mt) paralogues (numts) are non‐functional fragments of mtDNA integrated into the nuclear genome that can overestimate the number of species in analyses based on mtDNA sequences. As numts have relatively slow mutation rates, they can pass undetected by conventional procedures such as inspecting for internal stop codons, indels or apparent polymorphism in chromatograms. Species boundaries based on mtDNA markers therefore require a thorough assessment of numts, especially in insects, where this phenomenon appears to be relatively frequent. Ectatomma ruidum is a widely distributed Neotropical ant species that is distributed from northern Mexico to northern Brazil. Previous behavioural and molecular evidence suggests that this species actually represents a composite taxon. Here we assessed the species boundaries in E. ruidum based on two mt (COI, cyt b) and one nuclear (H3) marker, as well as on external morphology. Ancient and recent mt paralogues were detected in several specimens, although pre‐PCR dilution of DNA template helped to recover most of the mt orthologues. Based on the congruence found between our species delineation obtained from the mt genealogies and the discriminated morphospecies, we propose that E. ruidum is actually composed of at least three species. Two of these species have a wide geographical distribution in the Neotropics, whereas the remaining one was restricted to localities situated near the Pacific coast in south‐east Mexico. We also found extensive intra‐ and interspecific variation in the barcoding locus. Moreover, the nuclear evidence suggests the existence of hybrids between two of these species in Oaxaca, south‐east Mexico. This study agrees with previous studies of other closely related animal taxa, which have revealed a complex evolutionary history and overlooked species diversity in the latter region.     

Sex differences in antipredator tail-waving displays of the diurnal yellow-headed gecko Gonatodes albogularis from tropical forests of Colombia

Many vertebrate species show display behaviors when predators are in their vicinity. Some of these displays may inform the predator of the improbability of capturing the prey (i.e., pursuit-deterrent displays) and are potentially advantageous to both predator and prey. Here we present data on a tail display performed by Gonatodes albogularis, a diurnal tropical gecko. We performed transect surveys in three habitats near Bogotá in Colombia. Geckos detected during transects were approached by the observer in a standardized way, and details of their tail-waving displays were recorded. In control recordings animals were watched from a distant site without approaching them. Results showed sexual differences in tail-waving display: when approached by the observer, males performed this behavior more frequently than females. We found no significant differences between males and females in flight-initiation distances and height above the substratum when they were initially located. Results also showed that males displayed more frequently when approached than when the simulated predator remained stationary. We interpret these results as evidence that the display functions as a pursuit-deterrent signal to potential predators. However, as some tail displays were performed in the presence of conspecifics, the display may also have a social function.     

Capsid protein of eastern equine encephalitis virus inhibits host cell gene expression

Eastern equine encephalitis virus (EEEV) causes sporadic but often severe cases of human and equine neurological disease in North America. To determine how EEEV may evade innate immune responses, we screened individual EEEV proteins for the ability to rescue the growth of a Newcastle disease virus expressing green fluorescent protein (NDV-GFP) from the antiviral effects of interferon (IFN). Only expression of the EEEV capsid facilitated NDV-GFP replication. Inhibition of the antiviral effects of IFN by the capsid appears to occur through a general inhibition of cellular gene expression. For example, the capsid inhibited the expression of several reporter genes under the control of RNA polymerase II promoters. In contrast, capsid did not inhibit expression from a T7 RNA polymerase promoter construct, suggesting that the inhibition of gene expression is specific and is not a simple manifestation of toxicity. The inhibition correlated both with capsid-induced phosphorylation of eukaryotic initiation factor 2 alpha and with capsid-mediated inhibition of cellular mRNA accumulation. Mapping analysis identified the N terminus as the region important for the inhibition of host gene expression, suggesting that this inhibition is independent of capsid protease activity. Finally, when cell lines containing EEEV replicons encoding capsid were selected, replicons consistently acquired mutations that deleted all or part of the capsid, for example, amino acids 18 to 135. Given that the amino terminus of the capsid is required to inhibit host cell gene expression, these data suggest that capsid expression from the replicons is ultimately toxic to host cells, presumably because of its ability to inhibit gene expression.     

N-glycans on Nipah virus fusion protein protect against neutralization but reduce membrane fusion and viral entry

Nipah virus (NiV) is a deadly emerging paramyxovirus. The NiV attachment (NiV-G) and fusion (NiV-F) envelope glycoproteins mediate both syncytium formation and viral entry. Specific N-glycans on paramyxovirus fusion proteins are generally required for proper conformational integrity and biological function. However, removal of individual N-glycans on NiV-F had little negative effect on processing or fusogenicity and has even resulted in slightly increased fusogenicity. Here, we report that in both syncytium formation and viral entry assays, removal of multiple N-glycans on NiV-F resulted in marked increases in fusogenicity (>5-fold) but also resulted in increased sensitivity to neutralization by NiV-F-specific antisera. The mechanism underlying the hyperfusogenicity of these NiV-F N-glycan mutants is likely due to more-robust six-helix bundle formation, as these mutants showed increased fusion kinetics and were more resistant to neutralization by a fusion-inhibitory reagent based on the C-terminal heptad repeat region of NiV-F. Finally, we demonstrate that the fusogenicities of the NiV-F N-glycan mutants were inversely correlated with the relative avidities of NiV-F's interactions with NiV-G, providing support for the attachment protein "displacement" model of paramyxovirus fusion. Our results indicate that N-glycans on NiV-F protect NiV from antibody neutralization, suggest that this "shielding" role comes together with limiting cell-cell fusion and viral entry efficiencies, and point to the mechanisms underlying the hyperfusogenicity of these N-glycan mutants. These features underscore the varied roles that N-glycans on NiV-F play in the pathobiology of NiV entry but also shed light on the general mechanisms of paramyxovirus fusion with host cells.     

Phenotypic and genotypic profile of clinical and animal multidrug‐resistant Salmonella enterica isolates from Mexico

Aims

The objective of this study was to obtain a phenotypic and genotypic profile of Salmonella enterica including multidrug‐resistant (MDR) isolates from food‐producing animals and clinical isolates, as well as their genetic relatedness in two different States of Mexico (Jalisco and State of Mexico).

Methods and Results

A total of 243 isolates were evaluated in terms of antimicrobial resistance (AMR) and related genes through a disk diffusion method and PCR respectively; we found 16 MDR isolates, all of them harbouring the bla_CMY gene but not qnr genes, these isolates represent less than 10% of the collection. The pulsed‐field gel electrophoresis revealed a higher genotypic similitude within isolates of State of Mexico than Jalisco.

Conclusions

A low percentage of Salmonella isolates were resistant to relevant antibiotics in human health, nevertheless, the AMR and involved genes were similar despite the different serovars and origin of the isolates.

Significance and Impact of the Study

This investigation provided an insight of the current status of AMR of Salmonella isolates in two States of Mexico and pinpoint the genes involved in AMR and their epidemiological relationship, the information could help to determine an adequate therapy in human and veterinary medicine.     

Individual N-Glycans Added at Intervals along the Stalk of the Nipah Virus G Protein Prevent Fusion but Do Not Block the Interaction with the Homologous F Protein

The promotion of membrane fusion by most paramyxoviruses requires an interaction between the viral attachment and fusion (F) proteins to enable receptor binding by the former to trigger the activation of the latter for fusion. Numerous studies demonstrate that the F-interactive sites on the Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) and measles virus (MV) hemagglutinin (H) proteins reside entirely within the stalk regions of those proteins. Indeed, stalk residues of NDV HN and MV H that likely mediate the F interaction have been identified. However, despite extensive efforts, the F-interactive site(s) on the Nipah virus (NiV) G attachment glycoprotein has not been identified. In this study, we have introduced individual N-linked glycosylation sites at several positions spaced at intervals along the stalk of the NiV G protein. Five of the seven introduced sites are utilized as established by a retardation of electrophoretic mobility. Despite surface expression, ephrinB2 binding, and oligomerization comparable to those of the wild-type protein, four of the five added N-glycans completely eliminate the ability of the G protein to complement the homologous F protein in the promotion of fusion. The most membrane-proximal added N-glycan reduces fusion by 80%. However, unlike similar NDV HN and MV H mutants, the NiV G glycosylation stalk mutants retain the ability to bind F, indicating that the fusion deficiency of these mutants is not due to prevention of the G-F interaction. These findings suggest that the G-F interaction is not mediated entirely by the stalk domain of G and may be more complex than that of HN/H-F.     

The impact of roads on the avifauna of páramo grasslands in Cajas National Park,Ecuador

National parks are an important tool for conserving biodiversity, particularly in areas of high biodiversity and endemism such as the tropical Andes. However, national parks often face a variety of stressors related to recreation, road construction and illegal extraction of natural resources. Unfortunately, the influence of these stressors for biodiversity is rarely well documented. Cajas National Park in Ecuador is no exception. Despite being traversed by the Cuenca-Molleturo-Naranjal road, effects of the road construction on biodiversity have not been determined. We therefore assessed the influence of road proximity on bird species richness and abundance as well as composition of bird habitat groups in Cajas National Park using transect walks at 25 m and 250 m distance to the road (overall 18 transects, each 1 km length). In total, we recorded 1110 individuals of 28 páramo bird species. Overall species richness did not differ between transects near and far from the road. Nevertheless, the average abundance of shrubby páramo species was significantly higher far from the road than near the road (Far = 36, Near = 25). Moreover, we found a tendency towards differences in the composition of bird habitat groups between transects near and far from the road. One aspect potentially driving the observed patterns was the increasing proportion of planted non-native woody tree species within páramo grassland near the road, which may have caused reduced abundances of shrubby páramo bird species there. While roads represented a clear impact on the composition of bird species in the páramo, the major effect seems to be driven by the introduction of non-native plant species along the roadside. In order to reduce the impact of roads to a minimum, we suggest that park managers should control the introduction of such plant species.     

Evagination and infectivity of Taenia crassiceps cysticerci in experimental animals

Cysticerci of Taenia crassiceps reproduce asexually by exogenous budding in the rodent intermediate host, and can experimentally develop to the adult stage within the small intestine of golden hamsters. In the present study, we report the loss of cysticercus infectivity for hamsters after maintaining the strain for 4 yr by consecutive peritoneal passage in mice. Larval infectivity was restored after a cysticercus from the WFU strain developed into a gravid tapeworm after being passaged through a dog. The eggs of this tapeworm were infective for mice, which subsequently developed cysticerci with renewed capability for infecting experimental hamsters. An in vitro evagination assay was also conducted using eleventh-generation WFU strain cysticerci, as well as second- and fourth-generation dog-derived cysticerci. Significantly higher (P < 0.0001) evagination was observed for 5-mo-old dog-derived and WFU infrapopulations when compared with respective evagination values for 9- and 12-mo-old infrapopulations. The extent of evagination was linked to the capacity of cysticerci to infect hamsters, so that greater evagination resulted in a higher infectivity for hamsters and vice versa.     

50 years of the Revista de Biologia Tropical: its contribution to the development of the Geo-Paleontology

The geosciences contribution along the 50 years of the Revista de Biología Tropical had been scarcity and episodic. Until now there are 2374 papers but only 21 (0.88%) have some relation with geological sciences. It's possible to recognize two periods with geological contributions, one between 1963 and 1978. It's appropriate to underline the importance of the biologist L. D. Gómez with his contributions about Costa Rican Paleobotanic in this period. The other period includes from 1988 to the present, and it's typified by an increase of biologist and geologist participation in different topics regarding with geosciences. Foreign and national researches are in the same ratio and belong from several countries like Costa Rica, México and Dominican Republic. The subjects are concerning mainly about fossil taxonomy (Paleontology: 81%), only 19% are related with geological topics. Such distribution could be explained because the affinity between the fossil studies and the biological sciences.