Mantel test in population genetics

The comparison of genetic divergence or genetic distances, estimated by pairwise F_ST and related statistics, with geographical distances by Mantel test is one of the most popular approaches to evaluate spatial processes driving population structure. There have been, however, recent criticisms and discussions on the statistical performance of the Mantel test. Simultaneously, alternative frameworks for data analyses are being proposed. Here, we review the Mantel test and its variations, including Mantel correlograms and partial correlations and regressions. For illustrative purposes, we studied spatial genetic divergence among 25 populations of Dipteryx alata (“Baru”), a tree species endemic to the Cerrado, the Brazilian savannas, based on 8 microsatellite loci. We also applied alternative methods to analyze spatial patterns in this dataset, especially a multivariate generalization of Spatial Eigenfunction Analysis based on redundancy analysis. The different approaches resulted in similar estimates of the magnitude of spatial structure in the genetic data. Furthermore, the results were expected based on previous knowledge of the ecological and evolutionary processes underlying genetic variation in this species. Our review shows that a careful application and interpretation of Mantel tests, especially Mantel correlograms, can overcome some potential statistical problems and provide a simple and useful tool for multivariate analysis of spatial patterns of genetic divergence.     

Detection of Oseltamivir-Resistant Pandemic Influenza A(H1N1)pdm2009 in Brazil: Can Community Transmission Be Ruled Out?

Although surveillance efforts that monitor the emergence of drug-resistant strains of influenza are critical, systematic analysis is overlooked in most developing countries. We report on the occurrence of strains of pandemic influenza A(H1N1)pdm09 with resistance and decreased susceptibility to oseltamivir (OST) in Brazil in 2009, 2011 and 2012. We found 7 mutant viruses, 2 with the mutation S247N and other 5 with the mutation H275Y. Most of these viruses were from samples concentrated in the southern region of Brazil. Some of these resistant viruses were detected prior to the initiation of OST treatment, suggesting that community transmission of mutant viruses may exist. Moreover, we show that one of these OST-resistant (H275Y) strains of A(H1N1)pdm09 was discovered in the tri-border region between Brazil, Argentina and Paraguay, highlighting that this strain could also be found in other Latin American countries. Our findings reinforce the importance of enhanced antiviral resistance surveillance in Brazil and in other Latin American countries to confirm or rule out the community transmission of OST-resistant strains of A(H1N1)pdm09.     

Alcohol Impairs Predation Risk Response and Communication in Zebrafish

The effects of ethanol exposure on Danio rerio have been studied from the perspectives of developmental biology and behavior. However, little is known about the effects of ethanol on the prey-predator relationship and chemical communication of predation risk. Here, we showed that visual contact with a predator triggers stress axis activation in zebrafish. We also observed a typical stress response in zebrafish receiving water from these conspecifics, indicating that these fish chemically communicate predation risk. Our work is the first to demonstrate how alcohol effects this prey-predator interaction. We showed for the first time that alcohol exposure completely blocks stress axis activation in both fish seeing the predator and in fish that come in indirect contact with a predator by receiving water from these conspecifics. Together with other research results and with the translational relevance of this fish species, our data points to zebrafish as a promising animal model to study human alcoholism.     

Long-term chromium picolinate supplementation improves colostrum profile of Santa Ines ewe

Biological Trace Element Research - Chromium (Cr) is a micromineral that is involved in the metabolism of carbohydrates, lipids, ammonia, and nucleic acids; thus, its supplementation can influence...     

Relationship between epipelon,epiphyton and phytoplankton in two limnological phases in a shallow tropical reservoir with high Nymphaea coverage

Macrophytes and phytoplankton are recognized as having roles in determining alternative stable states in shallow lakes and reservoirs, while the role of periphyton has been poorly investigated. Temporal and spatial variation of phytoplankton, epipelon and epiphyton was examined in a shallow reservoir with high abundance of aquatic macrophytes. The relationships between algae communities and abiotic factors, macrophyte coverage and zooplankton density were also analyzed. Monthly sampling was performed in three zones of the depth gradient of the reservoir. Two phases of algal dominance were found: a phytoplankton phase and epipelon phase. The phase of phytoplankton dominance was characterized by high macrophyte coverage. Rotifera was the dominant zooplankton group in all the zones. Flagellate algae were dominant in phytoplankton, epipelon and epiphyton. Macrophyte coverage was found to be a predictor for algal biomass. Changes in biomass and species composition were associated with macrophyte cover variation, mainly the Nymphaea. In addition to the abiotic factors, the macrophyte coverage was a determining factor for changes to the algal community, contributing to the alternation between dominance phases of phytoplankton and epipelon. The macrophyte–phytoplankton–periphyton relationship needs to be further known in shallow reservoirs, especially the role of epipelon as an alternate stable state.

     

Macrelmis pubescens (Grouvelle, 1889) – redescription of the species,designation of a lectotype and description of its larva (Coleoptera: Elmidae)

The adult of Macrelmis pubescens (Grouvelle, 1889) is redescribed, illustrated, a lectotype designated, and new locality information provided. The lectotype is housed in the Grouvelle’s collection in the Muséum national d’Histoire naturelle, Paris, France. The larva of M. pubescens is described, illustrated and compared with the known larvae of the genus. A diagnosis for Macrelmis Motschulsky, 1860 larvae is provided.     

Characterization of Neutrophilic Fe(II)-Oxidizing Bacteria Isolated from the Rhizosphere of Wetland Plants and Description of Ferritrophicum radicicola gen. nov. sp. nov., and Sideroxydans paludicola sp. nov.

Iron deposits (Fe plaque) on wetland plant roots contain abundant microbial populations, including Fe(II)-oxidizing bacteria (FeOB) that have not been cultured previously. In this study, 4 strains of Fe plaque-associated FeOB were isolated from 4 species of wetland plants. All 4 isolates grew in tight association with Fe-oxides, but did not form any identifiable Fe-oxide structures. All strains were obligate lithotrophic Fe(II)-oxidizers that were microaerobic, and were unable to use other inorganic or organic energy sources. One strain, BrT, was shown to fix ¹⁴ CO ₂ at a rate consistent with its requirement for total cell carbon. The doubling times for the strains varied between 9.5 and 15.8 hours. The fatty acid methyl ester (FAME) profiles of 2 strains, BrT and CCJ, revealed that 16:0, 15:1 isoG, and 14:0 were dominant fatty acids. Phylogenetic analysis of the 16S rRNA gene indicated that all the strains were Betaproteobacteria. Two of the strains, BrT and Br-1 belong to a new species, Sideroxydans paludicola; a third strain, LD-1, is related to Sideroxydans lithotrophicus, a recently described species of FeOB. The fourth isolate, Ferritrophicum radicicola, represented a new genus in a new order of Betaproteobacteria, the Ferritrophicales. There are no other cultured isolates in this order. A small subunit rRNA gene-based, cultivation-independent analysis of Typha latifolia collected from a wetland revealed terminal restriction fragment profiles (tRFLP) consistent with the presence of these bacteria in the rhizosphere. These novel organisms likely play an important role in Fe(II) oxidation kinetics and Fe cycling within many terrestrial and freshwater environments.     

Numerical and structural chromosome variation in the swarm-founding wasp Metapolybia decorata Gribodo 1896 (Hymenoptera, Vespidae)

The Neotropical Polistinae wasps are diverse in taxonomy, social behavior, and nesting founding characteristics. Although some species in this group have been used as models for studies on wasp’s biology, they are poorly known in terms of cytogenetics. Here we reported an intraspecific numerical-structural chromosome variation in the swarm-founding wasp Metapolybia decorata from the Brazilian Atlantic Rainforest using conventional and molecular cytogenetic techniques. The observed structural chromosome change involved a telomeric fusion that resulted in a chromosome number range of 2n = 34–36. The origin and geographic distribution of the variant chromosome forms as well as their frequency and maintenance in the studied populations are discussed. In addition, we reported a novel and geographically restricted deletion in the fused chromosomes indicating that the species is undergoing a continued process of karyotype evolution leading to fused chromosome stabilization by elimination of inactive centromeric sequences. Evidence of differences in the telomeric sequences of this wasp was also found by in situ hybridization using the motif (T₂AG₂)₇ as probe.