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In recent decades, Aeromonas hydrophila has emerged as a foodborne bacterial pathogen of public health concern, especially as it exhibits resistance to the major chemical sanitizers commonly used in the food industry. Meanwhile, this pathogen may be spread from diseased fish flesh through the contamination of equipment contact surfaces during food processing, thus posing a food safety risk. Thise determined the susceptibility profiles of retail fish-borne A. hydrophila isolates to 24 common antibiotics and five major sanitizers used in the food industry. The polymerase chain reaction technique was used to confirm all A. hydrophila isolates to the species level, and the agar diffusion method was applied to determine the antimicrobial susceptibility profiles. All isolates were confirmed to be A. hydrophila species. This bacterium was observed to have resistance to multiple antibiotics, with the highest resistance index being for those of the beta-lactam class. Additionally, the isolates showed high resistance to four of the five chemical sanitizers tested, with the highest resistance rate being toward sodium hypochlorite. The results suggested that A. hydrophila isolates with multiple resistance to the antimicrobials and main sanitizers used in the food industry can be found in retail fish sold in the Cuiabá region of Mato Grosso, Brazil. RESUMO: Aeromonas hydrophila emergiu nas últimas décadas como um patógeno humano relevante. O fato desse patógeno alimentar emergente apresentar resistência antimicrobiana é um desafio considerável para as Agências de Saúde devido à resistência desta espécie aos principais sanitizantes químicos comumente utilizados na indústria alimentícia em que representa um risco à segurança dos alimentos, uma vez que pode contribuir para a disseminação desta bactéria na carne de peixes e levar à contaminação da superfície de contato dos equipamentos durante o processamento dos alimentos. Este estudo teve como objetivo determinar os padrões de suscetibilidade de isolados de A. hydrophila de peixes comercializados no varejo a 24 antibióticos comuns e cinco principais sanitizantes utilizados nas indústrias alimentícias. Neste estudo, todos os isolados de A. hydrophila foram confirmados em nível de espécie pela técnica de Reação em Cadeia da Polimerase (PCR). A técnica de difusão em ágar foi utilizada para determinar o perfil de suscetibilidade antimicrobiana frente aos 24 antibióticos testados e para avaliar a suscetibilidade aos principais sanitizantes utilizados na indústria alimentícia. A partir dos resultados, todos os isolados foram confirmados como sendo da espécie A. hydrophila pela técnica de PCR molecular. Observou-se A. hydrophila com perfil de resistência a múltiplos antibióticos, em que os da classe dos Beta-Lactâmicos foram os antimicrobianos com maior índice de resistência. Além disso, a suscetibilidade aos sanitizantes apresentou alta resistência em quatro dos cinco sanitizantes testados, sendo o hipoclorito de sódio foi o sanitizante químico com maior índice de resistência entre os isolados deste estudo. Os resultados sugerem que isolados de A. hydrophila com perfil de resistência a antimicrobianos e aos principais sanitizantes utilizados na indústria alimentícia podem ser encontrados em peixes comercializados no varejo da região de Cuiabá/Mato Grosso.

Scientific investigation of disease vectors is indispensable for knowledge of its Ecology, as they affect the health of human population. In this work, we present the results of the distribution and abundance of Aedes aegypti and Ae. albopictus in Massairo Okamura and Mãe Bonifácia state parks, Cuiabá-Mato Grosso, Brazil, to understand how changes in the rainy season interfere with their proliferation in natural wild areas located in urban regions. The focus was to investigate the coexistence of these species in the capture sites. The collections were carried out in eight campaigns within a period of 11 months of the year 2019, through ovitraps, with a total of 10 traps for each park. The results of the variables abundance (n) and relative humidity (%) were analyzed by the Statistic 7.0 program using factorial ANOVA. The 7117 quantified larvae produced 1462 adults for the two parks, with significant variability in mean abundance values between months and between sampling points. The record of the co-occurrence of Ae. aegypti and Ae. albopictus resulted in their coexistence and use of similar breeding sites under advantageous conditions for their colonization. The results presented showed that the parks have vulnerabilities in relation to the proliferation of vectors, and the environments must go through constant epidemiological surveillance. Faced with a serious situation in relation to arboviruses, it is essential to adopt strategies with greater investments in adequate methods, which provide sustainability to the actions established by surveillance networks.

The outbreak of arbovirus vectors may result from a combination of human population growth, urbanization in tropical areas and a large expansion of the geographic distribution of Aedes aegypti. The objective of this research was to identify the populations of this vector in urban areas of four municipalities in the Baixada Cuiabana, using ovitraps, captured between October 2015 and November 2016. The electrophoresis technique was used, which aims to investigate the expression of esterase in biological samples in different environments. Esterases, such as carboxylesterase and cholinesterase, are involved in the development of resistance to chemical compounds in several insects, including the genus Aedes. The staining intensity of the gels was classified as "expressed bands", with weaker staining; and "overexpressed bands", with a darker color, indicative of the stronger presence of esterases. The analyses by the Mann-Whitney test of the Ae. aegypti population showed variability in esterase expression patterns with time, seasons and sites, which may undergo selection pressures related to the rainfall regime. An important factor that represented a higher frequency of isoenzyme overexpression was the beginning of the rains, in November/2016. Variations in the expression of bands between individuals of a population and between populations within the same species in different periods and places were conclusive of the vector populations as polymorphic. El brote del vector de arbovirus puede resultar de una combinación de crecimiento de la población humana, urbanización en áreas tropicales y una gran expansión de la distribución geográfica de Aedes aegypti. El objetivo de esta investigación fue identificar las poblaciones de este vector en áreas urbanas de cuatro municipios de la Baixada Cuiabana, utilizando ovitrampas, capturadas entre octubre de 2015 y noviembre de 2016. Se utilizó la técnica de electroforesis, que tiene como objetivo investigar la expresión de esterasa en muestras biológicas. Las esterasas, como la carboxilesterasa y la colinesterasa, están involucradas en el desarrollo de resistencia a compuestos químicos en varios insectos, incluido el género Aedes. La intensidad de tinción de los geles se clasificó como "bandas expresadas", con tinción más débil; y "bandas sobreexpresadas", con un color más oscuro, indicativo de la presencia más fuerte de esterasas. Los análisis de prueba de Mann-Whitney de la población de Ae aegypti mostraron variabilidad en los patrones de expresión de esterasa a lo largo del tiempo, las estaciones y los lugares, que pueden sufrir presiones de selección relacionadas con el régimen de lluvias. Un factor importante que representó una mayor frecuencia de sobreexpresión de isoenzimas fue el inicio de las lluvias, en noviembre / 2016. Las variaciones en la expresión de bandas entre individuos de una población y entre poblaciones dentro de la misma especie en diferentes períodos y ubicaciones fueron concluyentes para las poblaciones de vectores como polimórficos. O surto de vetores de arbovírus pode resultar de uma combinação de crescimento da população humana, urbanização em áreas tropicais e uma grande expansão da distribuição geográfica do Aedes aegypti. O objetivo desta pesquisa foi identificar as populações desse vetor em áreas urbanas de quatro municípios da Baixada Cuiabana, por meio de ovitrampas, capturadas entre outubro de 2015 e novembro de 2016. Foi utilizada a técnica de eletroforese, que visa investigar a expressão da esterase em amostras biológicas nos distintos ambientes. Esterases, como a carboxilesterase e a colinesterase, estão envolvidas no desenvolvimento de resistência a compostos químicos em diversos insetos, incluindo o gênero Aedes. A intensidade da coloração dos géis foi classificada como "bandas expressas", com coloração mais fraca; e "bandas superexpressas", com uma cor mais escura, indicativa da presença mais forte de esterases. As análises pelo teste de Mann-Whitney da população de Ae. aegypti mostraram variabilidade nos padrões de expressão da esterase com o tempo, estações e locais, que podem sofrer pressões de seleção relacionadas ao regime de chuvas. Um fator importante que representou maior frequência de superexpressão de isoenzimas foi o início das chuvas, em novembro/2016. As variações na expressão de bandas entre indivíduos de uma população e entre populações dentro da mesma espécie em diferentes períodos e locais foram conclusivas para as populações dos vetores como polimórficas.

Freshwater catfishes from the genus

Aedes aegypti mosquito has spread throughout the tropical and subtropical world and is currently the primary species responsible for transmitting dengue, urban yellow fever, Chikungunya, and Zika virus. This study aimed to investigate the inter- and intrapopulational genetic variability of Aedes aegypti through mitochondrial DNA, COI, ND4, and ND5 molecular markers in four municipalities in Mato Grosso. We used the Geneious software to build dendrograms for differentiating populations from each municipality. The interpopulational genetic distance obtained from sequence analysis showed a difference within populations through groups' formation in the ordering. Besides, we identified a difference in the interindividual genetic distance values, notably for the ND5 gene from the populations captured in the four municipalities. We recorded the smallest interindividual genetic distance within populations for populations from Chapada dos Guimarães. Extrinsic factors, including breeding habitat removal, can contribute to decreasing variability. Consequently, the dendrogram showed some similarities. Ovitrap monitoring, vector elimination, and genetic flow investigation stimulate actions to prevent transmitted diseases and support essential effective measures to control and fight Ae. aegypti.

The aim of this paper was to present the second case of B chromosomes in Auchenipteridae (Trachelyopterus sp.), and to test the hypothesis that the B chromosomes of this species and Parauchenipterus galeatus might have a common origin, since these two species have phylogenetic proximity. Both species have 58 chromosomes in the A complement, heterochromatin preferentially located at terminal region of the most of chromosomes, simple Ag-NORs located at the short arm of a subtelocentric pair, which was confirmed by hybridization with 18S rDNA, two submetacentric pairs carrying 5S rDNA sites, and presence of B chromosomes. The B chromosomes of the two species are small, metacentric, and almost totally heterochromatic, with variation of number intra and interindividual. In addition, for the first time in fish, the telomeric sequence [TTAGGG]n was dispersed along the B chromosomes (both species). The [GATA]n microsatellite were scattered in all chromosomes of the A complement and absent in the B chromosomes, in both species. These aspects confirm the phylogenetic proximity between the genus Parauchenipterus and Trachelyopterus, and they suggest the hypothesis that the B chromosomes of the two species might have common origin, previous to the diversification of these genera.

The secondary presentation of pollen consists of a foral mechanism where the presentation of pollen occurs in other foral structures in addition to the anther, in order to increase the precision of the dispersion of the pollen by the vectors. This study aims to describe the temporal dynamics of secondary pollen presentation, and morphological and morphometric characteristics in stages of pre- anthesis and anthesis in genotypes of fve natural Heliconia psittacorum populations. For the study of foral morphometry traits of length of the fower, stamen, stigma and height of flament insertion in the petal in bud and fower were measured. The foral morphology of pre-anthesis buds and fowers in anthesis, the presence or absence of characteristics such as herkogamy, region of flament insertion in the petal, region of stylar hairs, and of secondary pollen deposition were evaluated. Treatments of controlled pollinations, self-pollination, geitonogamy, cross-pollination, natural pollination and growth to pollen tube were sampled. Floral herkogamy and pollen transfer to the adhered hairs in the stylar region were clearly observed during anthesis, constituting the frst record of occurrence of secondary pollen presentation in Heliconiaceae. Pollen tube growth was inhibited in the stigmatic, style and basal regions of the pistil. Natural fruiting produced little or no fruit. The positioning of the stamens above the stigma, pollen viability and stigma receptivity during anthesis of H. psittacorum fowers may favor self-pollination. The stylar hairs observed in all H. psittacorum populations’ help in the retention of pollen grains. The low fruiting rate in controlled and natural pollinations suggest that the main propagation form of H. psittacorum in the study areas is based on asexual reproduction.

The karyotypes and other chromosomal markers of 4 catfish species, namely Lasiancistrus schomburgkii, Lasiancistrus sp., Araichthysloro, and Megalancistrus sp., members of a taxonomically complex and speciose tribe of catfishes Ancistrini, Hypostominae, were examined using conventional (Giemsa staining, Ag-NOR, and C-banding) and molecular cytogenetic protocols (FISH) and DNA barcoding. In L. schomburgkii, Lasiancistrus sp., and A.loro a diploid number 2n = 54 was observed, with karyotypes composed of 28m + 16sm + 10st, 36m + 12sm + 6st chromosomes, while Megalancistrus sp. had 2n = 52, with the karyotype composed of 28m + 16sm + 8st chromosomes. The Ag-NOR phenotypes were simple in all 4 species, which was confirmed by FISH with an 18S rDNA probe. However, the positive 5S rDNA sites varied among species: 2 chromosome pairs in L. schomburgkii, Lasiancistrus sp., and A. loro, and only 1 pair in Megalancistrus sp. The blocks of constitutive heterochromatin were poorly visible in the pericentromeric and telomeric regions of most chromosomes of the examined species by C-banding. The genetic distance analysis, based on mtDNA COI gene sequences (DNA barcoding), confirmed the species as 4 taxonomic units. Ours and other published data indicate that karyotype differentiation among Ancistrini is complex and divergent and indicates the occurrence of common chromosomal rearrangements, such as pericentric inversions conserving the diploid number, and other rearrangements that are more frequent in some genera, such as centric fusions in Ancistrus.

Made available in DSpace on 2019-10-06T15:40:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-05-19 Although several species of Ancistrus have been described from the Amazon and Paraguay river basins in the states of Amazonas and Mato Grosso, Brazil, the taxonomic status of most specimens from these regions remains doubtful. In the present work, cytogenetic and molecular data were used to discriminate and isolate unexpected Ancistrus lineages from the Amazon and Paraguay basins. For that, it was used DNA barcoding based on mitochondrial Cytochrome Oxidase Subunit I (COI) gene and cytogenic data to perform such molecular discrimination. The analyzed sequences had 669 bp, of which 171 bp were conserved and 491 bp were variable. The Neighbor-joining and Bayesian analysis revealed 21 distinct groups in topology. The genetic distances within each group was 0.4%, 21 times smaller than the mean distance observed among groups, which was 8.4%. These values showed seven distinct lineages of Ancistrus from the studied points of the Amazon basin and eight lineages from the Paraguay basin points. Our results illustrate the efficiency of this technique for the discrimination of the Ancistrus lineages once it indicates the occurrence of cryptic species in these regions, which cannot yet be identified either with just chromosomal or morphological analyzes. Institute of Biosciences São Paulo State University (Unesp) Mato Grosso Federal Institute (IFMT) Institute of Biosciences Mato Grosso Federal University Department of Biology Center for Research in Limnology Ichthyology and Aquaculture (Nupélia) Maringá State University Institute of Biosciences São Paulo State University (Unesp)

Although several species of

Os transgênicos são organismos que tiveram uma sequência de DNA de outro organismo inserido em seu genoma a fim de adquirir certas características comuns a estes. Eles podem ser utilizados na produção de animais ou vegetais. O cultivo e comercialização de transgênicos no Brasil, apesar de ser liberada pela CTNBio, gera posicionamentos contrários, evocando-se o Princípio da Precaução. Neste contexto, este estudo teve como objetivo conhecer a percepção de universitários dos cursos de Tecnologia em Gestão Ambiental e Engenharia de Alimentos sobre os transgênicos no Campus Cuiabá - Bela Vista do IFMT. A pesquisa foi realizada por aplicação de questionário aos universitários dos referidos cursos em 2012. Os pesquisados demonstraram ter conhecimento sobre o assunto, mas são conservadores quanto ao consumo de alimentos transgênicos. Eles revelaram que as principais fontes de informação são as mídias (impressa, TV e internet), seguidas pelas instituições de ensino. Embora, a maior fonte de informação tenha sido os veículos de informação, os pesquisados disseram que essas informações são menos confiáveis do que as oriundas das instituições de ensino. Este fato revela a responsabilidade das instituições de ensino de esclarecer a sociedade sobre temas polêmicos como os transgênicos.

The present study was stimulated by the growing demand for healthy food and the technology available for the detection and identification of microbial organisms in fishery products. Molecular tools were used to identify the bacterial community and detect the presence of pathogenic species in samples of farmed and wild-caught fish. Samples of muscle tissue were obtained from the local market in Cuiabá, Mato Grosso, Brazil. The 16S rDNA gene was used to detect 11 bacterial genera: Enterobacter (29.29%), Aeromonas (24.24%), Pseudomonnas (17.17%), Enterococcus (10.10%), Acinetobacter (6.06%), Citrobacter (4.04%), Bacillus (3.03%), Klebsiella and Lactococcus (2.02%), and Clostridium and Lysinibacillus (1.01%). High percentages of deleterious bacteria were recorded. Species-specific primers were used to detect the presence of Escherichia coli (35.71%), Staphylococcus aureus (12.5%), and Salmonella (7.14%), although Shigella was absent. These concentrations exceeded the limits established by the currently public health legislation. The molecular techniques used in the present study provide an alternative approach for the reliable diagnosis of contamination, which can be used on a large scale.

Astyanax is one of the most abundant and diverse taxa of fishes in the Neotropical region. In order to increase the amount of cytogenetic information for Astyanax as well as to exhibit data to subsidize future taxonomic studies, this work analyzed three species of Astyanax: two species are cryptic, and are here reported to live in syntopy (A. abramis and A. lacustris); the first karyotype description for A. pirapuan is also presented. Cytogenetic analyzes reveal a diploid number of 2n=50 chromosomes for three species, yet with differences in their karyotype morphology. The physical mapping of 18S rDNA showed up to thirteen sites in A. pirapuan and two in A. abramis and A. lacustris. The physical mapping of 5S rDNA has proven to be an effective marker for the characterization of species of Astyanax studied in this work. RESUMO Astyanax é um dos táxons mais representados e diversos na região Neotropical. Com o intuito de aumentar as informações citogenéticas para Astyanax e apresentar dados que possam subsidiar estudos taxonômicos futuros, este trabalho traz uma análise citogenética de três espécies de Astyanax: duas espécies consideradas crípticas, aqui reportadas em sintopia (A. abramis e A. lacustris) e a primeira descrição cariotípica de A. pirapuan. As análises citogenéticas revelaram 2n=50 cromossomos para as três espécies, com diferença na morfologia cariotípica de cada uma. Foram observados apenas dois sítios de rDNA 18S em A. abramis e A. lacustris e até 13 para A. pirapuan. O mapeamento físico do rDNA 5S se mostrou como um marcador efetivo para a caracterização das espécies de Astyanax abordadas neste estudo.

Ancistrus is one of the most diverse genera in the Ancistrini tribe, with 64 nominal species. The group is characterized by high cytogenetic variability; the diploid number of chromosomes ranges from 2n = 34 to 2n = 54. Ancistrus is widely distributed in the basins of the Uruguay, Paraguay, and Amazonian rivers; the latter two regions show the greatest diversity of Ancistrus species and karyotypes. Despite these characteristics, the group includes species for which taxonomic identification is difficult, and phylogenetic relationships and phylogeographic patterns, especially in the Paraguay and Amazon basins, have not yet been revealed. In this study, we determined the phylogenetic and phylogeographic relationships among the Ancistrus lineages in these regions. In particular, 93 concatenated sequences of mitochondrial ATPase 6/8 and COI as well as nuclear Rag2 were used for a phylogenetic analysis, and ATPase 6/8 were used for a phylogeographic analysis. The topology generated by the Bayesian method included three distinct clades subdivided into 21 groups. The clades indicated a monophyletic relationship among the lineages from the Amazon and Paraguay basins. The 21 groups had a high average genetic distance (8.4%) and were structured genetically. In the haplotype network, eight large groups were observed, seven belonging to the Paraguay basin and one corresponding to the Amazon basin, and no haplotypes were shared between the two basins. These results indicate that Ancistrus lineages form a monophyletic unit in the Paraguay and Amazon basins, and these lineages have a high level of divergence and genetic isolation. These results corroborate the existence of cryptic species in the region and emphasize the need for a taxonomic revision of the genus in these basins.

Made available in DSpace on 2022-04-28T19:05:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 The Tc1 mariner element is widely distributed among organisms and have been already described in different species of fish. The genus Ancistrus (Kner, 1854) has 68 nominal species and is part of an interesting taxonomic and cytogenetic group, as well as presenting a variation of chromosome number, ranging from 2n=34 to 54 chromosomes, and the existence of simple and multiple sex chromosome system and the occurrence of chromosomal polymorphisms involving chromosomes that carry the nucleolus organizer region. In this study, a repetitive element by restriction enzyme, from Ancistrus sp.1 Flecha was isolated, which showed similarity with a transposable element Tc1-mariner. Its chromosomal location is distributed in heterochromatic regions and along the chromosomal arms of all specimens covered in this study, confirming the pattern dispersed of this element found in other studies carried out with other species. Thus, this result reinforces the hypothesis that the sequence AnDraI is really a dispersed element isolated. As this isolated sequence showed the same pattern in all species which have different sex chromosomes systems, including in all sex chromosomes, we could know that it is not involved in sex chromosome differentiation. Laboratório de Citogenética Animal Universidade Estadual Paulista 'Júlio de Mesquita Filho' Campus de Rio Claro, Av 24A, 1515 Jardim Bela Vista Instituto Federal de Ciências e Tecnologia do Mato Grosso Campus de Cuiabá Instituto de Biociências UFMT Universidade Federal de Mato Grosso Laboratório de Citogenética Animal Universidade Estadual Paulista 'Júlio de Mesquita Filho' Campus de Rio Claro, Av 24A, 1515 Jardim Bela Vista

The aim of the present study to determine the proximate composition (moisture, ashes, proteins and lipids), fatty acid profiles, cholesterol concentrations of five species of pacu-pevas from the Cuiaba river and the rivers of the Alto Paraguai basin in the Pantanal region of the state of Mato Grosso. My. paraguayensis and My. orbignyanum were found to contain significantly higher fractions of protein (19.79% and 20.16%, respectively; p

Cytogenetic analyses were carried out in 117 specimens of seven species of the genus Ancistrus from three hydrographic in Mato Grosso State: Paraguay, Araguaia-Tocantins and Amazon basins. Conventional cytogenetic techniques were used to obtain mitotic chromosomes. C-banding was performed to detect heterochromatic regions and silver nitrate staining was used to identify nucleolar organizer regions (Ag-NORs). The counted and paired chromosomes revealed diploid numbers ranging from 2n = 40 to 2n = 54 with karyotype formulae varying from FN = 80 to FN = 86. Single marks in distinct chromosomes identified the nucleolar organizer regions. The constitutive heterochromatin was scarce in the diploid number from 2n = 50 to 2n = 54 and conspicuous blocks were observed in a single species with 2n = 40 chromosomes. These data corroborate the hypotheses of reduction of diploid number in species with derived features such as presence of sex chromosomes and polymorphisms, besides allowing inferences about the evolutionary mechanisms and the ancestor karyotype that favored the diversification of this important genus in the tribe Ancistrini. Foram realizadas análises citogenéticas de 117 espécimes do gênero Ancistrus de três bacias hidrográficas do estado de Mato Grosso: Paraguai, Araguaia-Tocantins e Amazônica, utilizando as técnicas de citogenética convencional para obtenção de cromossomos mitóticos, visualização de regiões heterocromáticas e regiões organizadoras de nucléolos. Os cromossomos pareados revelaram uma variação no número diploide de 2n = 40 a 2n = 54 e número fundamental de NF = 80 a NF = 86. As regiões organizadoras de nucléolos foram evidenciadas em um único par de cromossomos para todas as espécies e a heterocromatina é escassa nas espécies com números diploides elevados (2n = 50 a 2n = 54). Os blocos heterocromáticos mais evidentes foram observados nos pares portadores das AgRONs e em cromossomos da espécie com 2n = 40. Estes dados contribuem para a hipótese de redução do número diploide nas espécies que apresentam polimorfismos cromossômicos e cromossomos sexuais, além de contribuir para inferências sobre os mecanismos de evolução cariotípica que favoreceu a diversificação do gênero Ancistrus, o mais representativo na tribo Ancistrini.

The Tc1 mariner element is widely distributed among organisms and have been already described in different species of fish. The genus Ancistrus (Kner, 1854) has 68 nominal species and is part of an interesting taxonomic and cytogenetic group, as well as presenting a variation of chromosome number, ranging from 2n=34 to 54 chromosomes, and the existence of simple and multiple sex chromosome system and the occurrence of chromosomal polymorphisms involving chromosomes that carry the nucleolus organizer region. In this study, a repetitive element by restriction enzyme, from Ancistrus sp.1 “Flecha” was isolated, which showed similarity with a transposable element Tc1-mariner. Its chromosomal location is distributed in heterochromatic regions and along the chromosomal arms of all specimens covered in this study, confirming the pattern dispersed of this element found in other studies carried out with other species. Thus, this result reinforces the hypothesis that the sequence AnDraI is really a dispersed element isolated. As this isolated sequence showed the same pattern in all species which have different sex chromosomes systems, including in all sex chromosomes, we could know that it is not involved in sex chromosome differentiation.

We investigated the chromosomal distribution of 18S ribosomal DNA (rDNA) in different populations of 11 species of Hypostomus collected in important Brazilian basins, namely South Atlantic, Upper Parana, and Paraguay applying the fluorescence in situ hybridization (FISH). Hypostomus cochliodon, Hypostomus commersoni, Hypostomus hermanni, Hypostomus regani, Hypostomus albopunctatus, Hypostomus paulinus, Hypostomus aff. paulinus, Hypostomus iheringii, and Hypostomus mutucae presented multiple 18S rDNA sites while Hypostomus strigaticeps and Hypostomus nigromaculatus exhibited a single pair of chromosomes with 18S rDNA sites. The studied species presented variations in the number and position of these sites. The results accomplished were similar to those obtained by the analysis of AgNORs, revealing the same interspecific variability. Each species exhibited distinctive patterns of AgNOR and 18S rDNA distribution, which can be considered cytogenetic markers in each species of the genus and help improve the discussions on the phylogeny of the group.

O gênero Ancistrus apresenta uma grande variação cariotípica, tanto em relação ao número diplóide que varia de 2n=42 a 2n=54, quanto em relação a morfologia dos cromossomos. O grupo também é caracterizado por apresentar heteromorfismo no tamanho da região organizadora de nucléolo (NOR), bem como grandes segmentos heterocromáticos evidenciados pelo bandamento C, o que faz com que o gênero se torne um importante modelo para o estudo de sequências repetitivas. O rDNA 5S é uma sequência importante para o genoma uma vez que é essencial para a síntese proteica, e também está relacionada com regiões frágeis no genoma (hotspots) em alguns organismos, podendo dessa forma atuar como marcador molecular de processos de rearranjos cromossômicos. Tendo isso em vista o presente trabalho teve como objetivo isolar sequências de rDNA 5S e realizar o mapeamento destes segmentos nos cromossomos de uma espécie de Ancistrus sp. proveniente do Córrego Tamanduá, Bacia do Rio Paraguai, com número diplóide 2n=42 cromossomos. Os fragmentos de rDNA 5S foram amplificados via PCR, e como resultado foram observadas duas bandas, uma de aproximadamente 300 e outra de 100 pares de base. As bandas de menor tamanho foram extraídas do gel, clonadas e utilizadas separadamente como sondas na técnica de FISH. Foram observados grandes blocos de marcação em três cromossomos submetacêntricos distintos, sendo duas delas localizadas nos braços longos e uma nos braços curtos. A presença dessas grandes marcações em cromossomos distintos pode estar indicando uma possível associação da sequência do rDNA 5S com outros elementos de repetição nessa espécie, o que resulta no grande acúmulo deste segmento nos cromossomos estudados. Para melhor compreensão da organização destas sequências no genoma desta espécie, são necessários mais estudos em outras populações, bem como o sequenciamento do fragmento isolado, o que será feito na próxima etapa do trabalho.Apoio financeiro: FAPESP

Four populations of Ancistrus cf. dubius (Loricariidae, Ancistrinae) were analyzed cytogenetically. They were from different rivers and creeks of the Pantanal Basin, in the state of Mato Grosso, Br...

Populations of seven Ancistrus species were analyzed from streams and rivers of three hydrographic Brazilian basins. All populations showed different diploid numbers (2n), fundamental numbers (FNs), and karyotypes. Some representatives of Loricariidae have 2n = 54 chromosomes, which is very likely an ancestral cytotaxonomic characteristic, but many other representatives show extensive karyotype diversification. In the Ancistrus species studied, extensive karyotypic differentiation, which is generally associated with chromosome number reduction and rearrangement of the ribosomal RNA gene (rDNA) sites, was verified. Chromosomal locations of 18S and 5S rDNA were jointly detected using fluorescence in situ hybridization (FISH). In all the Ancistrus species analyzed, 18S rDNA sites were detected only on one chromosome pair, though this differed among species. 5S rDNA was located on 1–3 chromosome pairs either separately or in synteny with 18S rDNA in four of the seven species/populations. Hence the karyotype differentiation in Ancistrus species could be associated with a morphological speciation process, suggesting that chromosome fusions, inversions, deletions, duplications, and heterochromatination could contribute to the karyotype evolution of these neotropical armored catfishes.

Cytogenetic and FISH analyses were performed in 30 Ancistrus cuiabae specimens from a bay near the town of Poconé, in the Pantanal of Mato Grosso, Brazil. The observed diploid number was 2n = 34 chromosomes for both sexes and three distinct katyotypic formulae were found, namely cytotype A (20m, 8sm, 6st, Fundamental Number/FN = 68; 6 males and 11 females), cytotype B (19m, 8sm, 6st, 1a, FN = 67; 8 males and 4 females) and cytotype C (18m, 8sm, 6st, 2a, FN = 66; a single male). NORs's analyses showed that these regions were located in distinct sites on the NOR-bearing chromosome pair, according to cytotypes. Thus, in cytotype A, NORs were located in the terminal region of the short arm of the second metacentric chromosome pair; in cytotype B, they were detected in the short arm of the metacentric chromosome and interstitially on the acrocentric chromosome and, in cytotype C, NORs were observed in the interstitial region of the acrocentric chromosome pair. C-positive heterochromatic bands were adjacent to the rDNA sites in the corresponding chromosomes. Thus, the chromosomal polymorphism of A. cuiabae was probably originated through a pericentric inversion in chromosome pair nº 2 involving the NOR sites, which represents a novelty in the Ancistrini tribe. The results also broaden the knowledge of the chromosomal evolution in Ancistrus, the most derived genus of the Ancistrini tribe. Foram analisados, com técnicas convencionais de citogenética e FISH, 30 exemplares da espécie Ancistrus cuiabae da baía Arrombado, próximo a Poconé, Pantanal do Mato Grosso. Foram observadas metáfases com número diploide 2n = 34 cromossomos para ambos os sexos e três fórmulas cariotípicas distintas, aqui denominadas de citótipo A, verificado em 06 machos e 11 fêmeas (20m, 8sm, 6st, Número Fundamental, NF = 68); citótipo B, em 08 machos e 04 fêmeas (19m, 8sm, 6st, 1a, NF = 67) e citótipo C em apenas 01 macho (18m, 8sm, 6st, 2a, NF = 66). As NORs confirmaram os distintos citótipos verificados, além de evidenciar que os cromossomos portadores de rDNA são os que representam o polimorfismo na espécie Ancistrus cuiabae. No citótipo A, as NORs foram verificadas na região terminal do braço curto do segundo par de cromossomos metacêntricos; no citótipo B, foram evidenciadas no segundo par, heteromórfico, no braço curto do cromossomo metacêntrico e intersticial no seu homólogo acrocêntrico; no citótipo C as NORs foram observadas na região intersticial num par de cromossomos acrocêntricos. A análise da heterocromatina constitutiva evidenciou blocos discretos adjacentes ao rDNA no segundo par de cromossomos de ambos os citótipos. Uma provável inversão pericêntrica é a hipótese proposta para a origem deste polimorfismo na espécie Ancistrus cuiabae. Estes resultados ampliam o conhecimento sobre o gênero Ancistrus, o mais derivado da tribo, contribuem para o conhecimento sobre este grupo de peixes e para inferir sobre a evolução cromossômica dos Ancistrini