Comparison of Genomes of the Hepadnaviridae Family

Background: The Hepadnaviridae family is composed of small hepatotropic DNA viruses, divided into two main genera: Avihepadnavirus, which infects birds;and Orthohepadnavirus, which infects mammals. The human hepatitis B virus (HBV) is a member of the latter family and contains a relaxed circular double-stranded DNA genome of approximately 3 kb, and the objective of this study is to evaluate the genetic diversity of the genome of the Hepadnaviridae family. Materials and Methods: For this study, we evaluated the 26 NCBI reference sequences of the Hepadnaviridae family. Result: The two main genera, Avihepadnavirus and Orthohepadnavirus, show low similarity between them. The Orthohepadnavirus, to which HBV belongs, has two important hosts, monkeys and bats, while the genus, which infects humans, has greater diversity but is similar to the viruses that infect monkeys. The Paraepadnavirus isolated from the white sucker fish and the Herpetohepadnavirus from the Tibetan frog showed strong similarity with the Avihepadnavirus found in birds. The Metahepadnavirus isolated from the bluegill fish was the Hepadnaviridae which had the greatest difference, with less than 20% similarity using CLC Sequence Viewer. Conclusion: The Hepadnaviridae genomic replication cycle involves a late reverse transcriptase (RT) step. This polymerase, however, does not have proofreading activity, resulting in genetic variability in the Hepadnaviridae family.

Multiscalar Geomorphometric Generalization for Soil-Landscape Modeling by Random Forest: A Case Study in the Eastern Amazon

Multiscalar topography influence on soil distribution has a complex pattern that is related to overlay of pedological processes which occurred at different times, and these driving forces are correlated with many geomorphologic scales. In this sense, the present study tested the hypothesis whether multiscale geomorphometric generalized covariables can improve pedometric modeling. To achieve this goal, this case study applied the Random Forest algorithm to a multiscale geomorphometric database to predict soil surface attributes. The study area is in phanerozoic sedimentary basins, in the Alter do Chão geological formation, Eastern Amazon, Brazil. The multiscale geomorphometric generalization was applied at general and specific geomorphometric covariables, producing groups for each scale combination. The modeling was run using Random Forest for A-horizon thickness, pH, silt and sand content. For model evaluation, visual analysis of digital maps, metrics of forest structures and effect of variables on prediction were used. For evaluation of soil textural classifications, the confusion matrix with a Kappa index, and the user’s and producer’s accuracies were employed. The geomorphometry generalization tends to smooth curvatures and produces identifiable geomorphic representations at sub-watershed and watershed levels. The forest structures and effect of variables on prediction are in agreement with pedological knowledge. The multiscale geomorphometric generalized covariables improved accuracy metrics of soil surface texture classification, with the Kappa Index going from 43% to 62%. Therefore, it can be argued that topography influences soil distribution at combined coarser spatial scales and is able to predict soil particle size contents in the studied watershed. Future development of the multiscale geomorphometric generalization framework could include generalization methods concerning preservation of features, landform classification adaptable at multiple scales.

考虑车辆周转的铁路动态货运服务网络设计优化模型及其分支-定价-切割算法

研究考虑车辆周转的铁路动态货运服务网络设计问题,目标是在合理设计铁路运输服务网络的基础上提高车辆利用率。将传统的离散时空网络拓展为考虑车辆周转的超级网络,构建混合整数规划模型,同时考虑列车开行时段、编组内容、空车调配、车辆归属、运输服务水平等约束。基于模型的NP-Hard特性,给出一种分支-定价-切割算法,通过在模型中添加Benders割的方法调整可行域,通过列生成方法避免网络规模较大导致可选径路数量过多的问题,该算法可保证模型收敛至最优解。算例证明了模型和算法的有效性,通过灵敏度分析验证可用车辆数量对于空车调配方案的影响。

The Potential of Activated Carbon in the Treatment of Water for Human Consumption, a Study of the State of the Art and Its Techniques Used for Its Development

This review article addresses the use of biological activated carbon in water treatment and its techniques for its development, with the premise of analyzing the potential of Activated Carbon (AC) in the treatment of water for human consumption. For this end, it aims to identify the techniques used for the production of AC, use and its benefits, production from vegetable waste for water treatment. Activated carbon has the ability to selectively collect gases, liquids and impurities inside its pores, which is the reason it is widely used in filtration systems and for that the treatment of water, the coal fulfills the function of adsorbent, retaining in its pores certain types of impurities: large particles that cause undesirable color, taste or odor in the water. In the treatment of effluents, coal is used for clarification, deodorization and purification of effluents.

Neotropical electric fishes(Gymnotiformes)as model organisms for bioassays

Electric fishes(Gymnotiformes)inhabit Central and South America and form a relatively large group with more than 200 species.Besides a taxonomic challenge due to their still unresolved systematic,wide distribution and the variety of habitats they occupy,these fishes have been intensively studied due to their peculiar use of bioelectricity for electrolocation and communication.Conventional analysis of cells,tissues and organs have been complemented with the studies on the electric organ discharges of these fishes.This review compiles the results of 13 bioassays developed during the last 50 years,which used the quickness,low costs and functionality of the bioelectric data collection of Gymnotiformes to evaluate the effects of environmental contaminants and neuroactive drugs.

The differential genetic signatures related to climatic landscapes for jaguars and pumas on a continental scale

Modern and paleoclimate changes may have altered species dynamics by shifting species’niche suitability over space and time.We analyze whether the current genetic structure and isolation of the two large American felids,jaguar(Panthera onca)and puma(Puma concolor),are mediated by changes in climatic suitability and connection routes over modern and paleoclimatic landscapes.We estimate species distribution under 5 climatic landscapes(modern,Holocene,last maximum glaciations[LMG],average suitability,and climatic instability)and correlate them with individuals’genetic isolation through causal modeling on a resemblance matrix.Both species exhibit genetic isolation patterns correlated with LMG climatic suitability,suggesting that these areas may have worked as“allele refuges.”However,the jaguar showed higher vulnerability to climate changes,responding to modern climatic suitability and connection routes,whereas the puma showed a continuous and gradual transition of genetic variation.Despite differential responsiveness to climate change,both species are subjected to the climatic effects on genetic configuration,which may make them susceptible to future climatic changes,since these are progressing faster and with higher intensity than changes in the paleoclimate.Thus,the effects of climatic changes should be considered in the design of conservation strategies to ensure evolutionary and demographic processes mediated by gene flow for both species.