Genetic structure of drone congregation areas of Africanized honeybees in southern Brazil

As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European

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Os fatores moleculares que determinam o sexo e as castas de Apis Mellifera, e a expansão de famílias gênicas observadas no genoma deste inseto social são as questões que nos motivam neste estudo. A partir de sequências genéticas disponíveis na rede e de informações na literatura, objetivamos identificar genes e processos biológicos que participam da determinação do sexo e casta e famílias multigênicas relacionadas à evolução da eusocialidade nestas abelhasnot availabl

Critical analysis of the forecasting of mechanical behavior of rockfill by laboratory scale modeling

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2019.Este trabalho aborda o efeito de escala de ensaios em laboratório na previsão de parâmetros mecânicos de enrocamentos. Para isso, recorreu-se a uma ampla revisão bibliográfica, a criação de um banco de dados do comportamento mecânico de enrocamentos e a um extenso programa de ensaios com o intuito de estabelecer uma metodologia que permitisse prever o comportamento de enrocamentos em escala de campo a partir de ensaios em modelo reduzido em laboratório. Foram realizados ensaios para individualizar os parâmetros mais representativos da rocha, da partícula e do enrocamento. A campanha de ensaios demonstrou a influência do tamanho dos equipamentos, escala dos equipamentos vs. escala das partículas, na resposta mecânica de enrocamentos. Ficou demonstrado ainda que ensaios em escala de laboratório não conseguem representar fielmente os parâmetros mecânicos dos enrocamentos em escala de campo, mas que a definição prévia da combinação de três fatores, sendo eles o diâmetro máximo das partículas, a densidade relativa e a forma da distribuição granulométrica, permite extrapolar os parâmetros definidos em laboratório para uma escala de campo. Nos ensaios, foram utilizadas rochas de diferentes mineralogias, representando enrocamentos de barragens construídas no Brasil, contudo, o granito da barragem de Serra da Mesa foi adotado como material piloto devido a homogeneidade de suas características física, química, mecânica e da sua baixa perda de resistência quando saturado. Os parâmetros obtidos dos ensaios em escala de laboratório com o granito da barragem de Serra da Mesa foram extrapolados para a escala do enrocamento de campo e confrontados com os parâmetros obtidos da retro-análise da instrumentação. Verificou-se uma boa aderência entre os referidos parâmetros, comprovando a eficácia do procedimento de extrapolação proposto.This work deals with the scale effect of laboratory tests in predicting mechanical parameters of rockfill. For this, a wide bibliographic review was used, the creation of a database of the mechanical behavior of rockfills and an extensive program of tests to establish a methodology that could predict the behavior of field-scale rockfills from tests in reduced model in laboratory scale. Tests were carried out to identify the most representative rock, particle and rockfill parameters. The test campaign showed the influence of the size of the equipment, the scale of the equipment vs. scale of the particles, in the mechanical response of rockfills. It has also been shown that laboratory-scale tests fail to accurately represent the mechanical parameters of field-scale rockfills, but rather that the prior definition of the combination of three factors, such as maximum particle diameter, relative density, and shape of the distribution, allows the extrapolation of parameters defined in the laboratory to a field scale. In the tests, rocks of different mineralogies were used, representing rockfills constructed in Brazil, however, granite from the Serra da Mesa dam was adopted as a pilot material due to the homogeneity of its physical, chemical and mechanical characteristics and its low resistance loss when saturated. The parameters obtained from the laboratory scale tests with the granite from the Serra da Mesa dam were extrapolated to the field rockfill scale and compared to the parameters obtained from the instrumentation retro-analysis. There was a good adhesion between these parameters, proving the effectiveness of the proposed extrapolation method. Finally, a roadmap for investigation, design and constructive monitoring of rockfill embankments was proposed, establishing a rational method to obtain parameters of these structures

Validation of reference genes for gene expression studies in the honey bee, Apis mellifera, by quantitative real-time RT-PCR

For obtaining accurate and reliable gene expression results it is essential that quantitative real-time RT-PCR (qRT-PCR) data are normalized with appropriate reference genes. The current exponential increase in postgenomic studies on the honey bee, Apis mellifera, makes the standardization of qRT-PCR results an important task for ongoing community efforts. For this aim we selected four candidate reference genes (actin, ribosomal protein 49, elongation factor 1-alpha, tbp-association factor) and used three software-based approaches (geNorm, BestKeeper and NormFinder) to evaluate the suitability of these genes as endogenous controls. Their expression was examined during honey bee development, in different tissues, and after juvenile hormone exposure. Furthermore, the importance of choosing an appropriate reference gene was investigated for two developmentally regulated target genes. The results led us to consider all four candidate genes as suitable genes for normalization in A. mellifera. However, each condition evaluated in this study revealed a specific set of genes as the most appropriated ones

Validation of reference genes for gene expression studies in the honey bee, Apis mellifera, by quantitative real-time RT-PCR

For obtaining accurate and reliable gene expression results it is essential that quantitative real-time RT-PCR (qRT-PCR) data are normalized with appropriate reference genes. The current exponential increase in postgenomic studies on the honey bee, Apis mellifera, makes the standardization of qRT-PCR results an important task for ongoing community efforts. For this aim we selected four candidate reference genes (actin, ribosomal protein 49, elongation factor 1-alpha, tbp-association factor) and used three software-based approaches (geNorm, BestKeeper and NormFinder) to evaluate the suitability of these genes as endogenous controls. Their expression was examined during honey bee development, in different tissues, and after juvenile hormone exposure. Furthermore, the importance of choosing an appropriate reference gene was investigated for two developmentally regulated target genes. The results led us to consider all four candidate genes as suitable genes for normalization in A. mellifera. However, each condition evaluated in this study revealed a specific set of genes as the most appropriated ones

Use of machine learning as a tool for determining fire management units in the brazilian atlantic forest

Abstract Geoprocessing techniques are generally applied in natural disaster risk management due to their ability to integrate and visualize different sets of geographic data. The objective of this study was to evaluate the capacity of classification and regression tree (CART) to assess fire risk. MCD45A1 product of the burnt area, relative to a 16-year period (2000-2015) was used to obtain a fire occurrence map, from center points of the raster, using a kernel density approach. The resulting map was then used as a response variable for CART analysis with fire influence variables used as predictors. A total of 12 predictors were determined from several databases, including environmental, physical, and socioeconomic aspects. Rules generated by the regression process allowed to of define different risk levels, expressed in 35 management units, and used to produce a fire prediction map. Results of the regression process (r = 0.94 and r² = 0.88) demonstrate the capability of the CART algorithm in highlighting hierarchical relationships among predictors, while the model’s easy interpretability provides a solid basis for decision making. This methodology can be expanded in other environmental risk analysis studies and applied to any area of the globe on a regional scale

Genes involved in thoracic exoskeleton formation during the pupal-to-adult molt in a social insect model, Apis mellifera

Background: The insect exoskeleton provides shape, waterproofing, and locomotion via attached somatic muscles. The exoskeleton is renewed during molting, a process regulated by ecdysteroid hormones. The holometabolous pupa transforms into an adult during the imaginal molt, when the epidermis synthe3sizes the definitive exoskeleton that then differentiates progressively. An important issue in insect development concerns how the exoskeletal regions are constructed to provide their morphological, physiological and mechanical functions. We used whole-genome oligonucleotide microarrays to screen for genes involved in exoskeletal formation in the honeybee thoracic dorsum. Our analysis included three sampling times during the pupal-to-adult molt, i.e., before, during and after the ecdysteroid-induced apolysis that triggers synthesis of the adult exoskeleton.Results: Gene ontology annotation based on orthologous relationships with Drosophila melanogaster genes placed the honeybee differentially expressed genes (DEGs) into distinct categories of Biological Process and Molecular Function, depending on developmental time, revealing the functional elements required for adult exoskeleton formation. Of the 1,253 unique DEGs, 547 were upregulated in the thoracic dorsum after apolysis, suggesting induction by the ecdysteroid pulse. The upregulated gene set included 20 of the 47 cuticular protein (CP) genes that were previously identified in the honeybee genome, and three novel putative CP genes that do not belong to a known CP family. In situ hybridization showed that two of the novel genes were abundantly expressed in the epidermis during adult exoskeleton formation, strongly implicating them as genuine CP genes. Conserved sequence motifs identified the CP genes as members of the CPR, Tweedle, Apidermin, CPF, CPLCP1 and Analogous-to-Peritrophins families. Furthermore, 28 of the 36 muscle-related DEGs were upregulated during the de novo formation of striated fibers attached to the exoskeleton. A search for cis-regulatory motifs in the 5′-untranslated region of the DEGs revealed potential binding sites for known transcription factors. Construction of a regulatory network showed that various upregulated CP- and muscle-related genes (15 and 21 genes, respectively) share common elements, suggesting co-regulation during thoracic exoskeleton formation.Conclusions: These findings help reveal molecular aspects of rigid thoracic exoskeleton formation during the ecdysteroid-coordinated pupal-to-adult molt in the honeybee

Rapid regulation of microRNA following induction of long-term potentiation in vivo.

Coordinated regulation of gene expression is essential for consolidation of the memory mechanism, long-term potentiation (LTP). Triggering LTP by N-methyl-D-aspartate receptor (NMDAR) activation rapidly activates constitutive and inducible transcription factors that promote expression of genes responsible for LTP maintenance. As microRNA (miRNA) coordinate expression of related genes, we hypothesise that miRNA contribute to the LTP-induced gene response. MiRNA function primarily as negative regulators of gene expression. As LTP promotes a generalised rapid up-regulation of gene expression, we predicted a complementary rapid down-regulation of miRNA. Accordingly, we carried out global miRNA expression profiling in rat dentate gyrus 20 min post-LTP induction in vivo. Consistent with our hypothesis, we found a large number of differentially expressed miRNA, the majority down-regulated. Detailed analysis of miR-34a-5p and miR-132-3p revealed this down-regulation was transient and NMDAR-dependent, whereby block of NMDARs released an activity-associated inhibitory mechanism. Furthermore, down-regulation of mature miR-34a-5p and miR-132-3p occurred solely by post-transcriptional mechanisms, despite up-regulation of the pri-miR-132 transcript. To understand how down-regulation of miR-34a-5p and miR-132-3p intersects with the molecular events occurring following LTP, we used bioinformatics to identify potential targets. Previously validated targets included the key LTP-regulated genes Arc and glutamate receptor subunits. Predicted targets included the LTP-linked kinase, Mapk1, and neuropil-associated transcripts Hn1 and Klhl11, which were validated using luciferase reporter assays. Furthermore, p42-Mapk1 levels were up-regulated following LTP. Together, these data support the interpretation that miRNA, in particular miR-34a-5p and miR-132-3p, make a surprisingly rapid contribution to synaptic plasticity via dis-inhibition of translation of key plasticity-related molecules