35 research outputs found
Comparative analysis of sex chromosomes in Leporinus species (Teleostei, Characiformes) using chromosome painting.
BACKGROUND: The Leporinus genus, belonging to the Anostomidae family, is an interesting model for studies of sex chromosome evolution in fish, particularly because of the presence of heteromorphic sex chromosomes only in some species of the genus. In this study we used W chromosome-derived probes in a series of cross species chromosome painting experiments to try to understand events of sex chromosome evolution in this family. RESULTS: W chromosome painting probes from Leporinus elongatus, L. macrocephalus and L. obtusidens were hybridized to each others chromosomes. The results showed signals along their W chromosomes and the use of L. elongatus W probe against L. macrocephalus and L. obtusidens also showed signals over the Z chromosome. No signals were observed when the later aforementioned probe was used in hybridization procedures against other four Anostomidae species without sex chromosomes. CONCLUSIONS: Our results demonstrate a common origin of sex chromosomes in L. elongatus, L. macrocephalus and L. obtusidens but suggest that the L. elongatus chromosome system is at a different evolutionary stage. The absence of signals in the species without differentiated sex chromosomes does not exclude the possibility of cryptic sex chromosomes, but they must contain other Leporinus W sequences than those described here.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Cytogenetic characterization of Ameivula ocellifera (Spix, 1825) (Squamata, Teiidae) from the brazilian northeast
Ameivula is as a new genus of Teiidae family that emerged after extensive revision of species that comprised the former complex of species called Cnemidophorus group. Its species has a wide distribution from the northeast of Brazil to northern Argentina. Cytogenetic studies in the Teiidae family have shown that karyotypical data are important tools in phylogenetic and systematic studies within this group allowing to determine the position of species in the family. Thus, this study aimed to describe the karyotype of Ameivula ocellifera (Spix, 1825) from Picos, Piauí state in the Brazilian Northeast. Specimens were collected from August 2014 to October 2015 using interception traps and pitfalls, mounted randomly along the Caatinga area. The animals were collected and transported to Federal Institute of Piauí, campus Picos, where was carried out all laboratory procedures. Individuals analyzed showed a diploid number of 2n = 50 for both sexes, with karyotype composed by 30 macrochromosomes and 20 microchromosomes of telocentric and subtelocentric types. There were no heteromorphic sex chromosomes in the studied specimens. C-band technique evidenced the heterochromatic blocks in pericentromeric and telomeric regions of chromosomes. The nucleolar organizing regions appeared as a simple unit located at the terminal portion of the long arm of chromosomal pair number 5. The chromosomal characteristics of A. ocellifera analyzed do not show divergences regarding individuals from other regions. However, the nucleolar organizing regions seems to be a good chromosomal marker that permits to distinguish the species already studied
Cytogenetic analysis of Rhinella jimi (Stevaux, 2002) (Anura, Bufonidae) from northeastern Brazil
In this work we analyzed the karyotype of Rhinella jimi (Stevaux, 2002) (Anura, Bufonidae) from Picos (Piauí) in Northeastern Brazil. The chromosomes were examined using classical cytogenetic approaches (Giemsa, C-banding, and Ag-NOR staining). This species has 2n = 22 chromosomes, all metacentric or submetacentric. Heterochromatic segments were visualized at the centromeric region and the nucleolus organizer regions (NOR) were restricted to terminal regions of the short arms in pair 7. There was no evidence of heteromorphic sex chromosomes.
The chromosomal analysis of R. jimi allowed us to identify a karyotype that is similar to many other species of Rhinella, in which the diploid number remains unchanged and without evidences of structural rearrangements.Asociación Herpetológica Argentin
AUTONOMIC MODULATION AND FUNCTIONAL CAPACITY IN DIABETES MELLITUS TYPE 1 AND 2 SUBJECTS
Objetivos: avaliar a variabilidade da frequência cardíaca (VFC) durante testes autonômicos cardiovasculares e a capacidade funcional de indivíduos com DM tipos 1 e 2. Método: foram avaliados 15 indivíduos com DM e 12 indivíduos saudáveis, durante a realização de testes autonômicos cardiovasculares de manobra de acentuação da arritmia sinusal respiratória (ASR), handgrip e valsalva. Além disso, foi aplicado o teste submáximo de Paschoal para avaliação da capacidade funcional. Durante a realização dos testes autonômicos foi coletada a variabilidade da frequência cardíaca (VFC), por meio do registro dos intervalos RR, considerando-se os índices no domínio do tempo (RMSSD e pNN50) e da freqüência, como baixa e alta freqüência (BF e AF) e a relação entre os mesmos (BF/AF). Além da análise da VFC, foi registrado a distância percorrida durante o Teste de Paschoal e a glicemia capilar Resultados: Os valores referentes à glicemia foram significativamente maiores (p < 0,05) no grupo DM1 e DM2 comparados aos controles. Os valores de pNN50 para o DM1, em todos os testes realizados, foram menores em relação ao CDM1. Nenhuma diferença estatística foi encontrada quando comparados DM2 com o CDM2. A distância percorrida no teste de Paschoal foi similar entre os grupos de indivíduos com DM e seus respectivos controles. Conclusão: A variável pNN50 foi menor nos indivíduos com DM1, sugerindo redução da atividade parassimpática nesses indivíduos, porém sem alteração da capacidade funcional, avaliada pelo teste de Paschoal quando comparados ao grupo controle. Objectives: Evaluation of heart rate variability (HRV) during cardiovascular autonomic tests and functional capacity of patients with type 1 and type 2 DM.Methods: Fifteen individuals with DM and twelve healthy ones were evaluated during cardiovascular autonomic tests of maneuver enhancement of respiratory sinus arrhythmia (RSA), handgrip and Valsalva. In addition, the Paschoal test was applied to evaluate submaximal functional capacity. During the tests, autonomic heart rate variability (HRV) was collected by recording the RR intervals, considering the rates in the time domain (RMSSD and pNN50) and frequency domain, as low and high frequency (LF and HF) and the relationship between them (LF / HF). Besides the analysis of HRV and capillary glucose, the distance traveled during Paschoal test was also recorded. Results: The values related to blood glucose levels were significantly higher (p <0.05) in DM1 and DM2 groups compared to controls. PNN50 values for DM1 in all tests were lower compared to CDM1. No statistical difference was found when compared DM2 with CDM2. The distance of Paschoal test was similar between groups of individuals with diabetes and their respective controls. Conclusion: The variable pNN50 was lower in individuals with DM1, suggesting reduced of the parasympathetic activity in these individuals, but no change in functional capacity, as measured by Paschoal test when compared to the control group
RIQUEZA E DISTRIBUIÇÃO DE MACRÓFITAS AQUÁTICAS NO RIO GUARIBAS, PICOS, PIAUÍ
As macrófitas aquáticas desempenham importantes funções no ambiente aquático, contribuindo para a estruturação ambiental e para o equilíbrio biológico. O presente estudo teve como objetivo conhecer a riqueza biológica e a distribuição de macrófitas aquáticas no rio Guaribas, município de Picos, Piauí, corpo d’água do semiárido fortemente alterado por ações antrópicas. Para isso, amostras foram coletadas mensalmente em cinco estações no trecho urbano do referido rio, no período de setembro/2018 a fevereiro/2019. Para a coleta dos vegetais utilizou-se um quadrante com lados de 25 cm (0,0625 m2). O material foi conduzido para o Laboratório de Botânica da Universidade Federal do Piauí, campus de Picos, onde foi lavado, separado e identificado. Foram listadas 24 espécies distribuídas em 13 famílias botânicas, entre as quais foram mais representativas: Poaceae (5), Cyperaceae (3), Fabaceae (3), Araceae (2), Convolvulaceae (2) e Polygonaceae (2). As formas biológicas mais comuns foram as anfíbias e emergentes, anfíbias e as flutuantes livres. A maior riqueza florística ocorreu nos meses de fevereiro e setembro com 18 e 16 espécies, respectivamente. Conclui-se que a diversidade de macrófitas aquáticas do rio Guaribas sofreu influência dos fatores ambientais e antrópicos sendo favorecida pelo evento de chuvas, sucessão de espécies e eutrofização do corpo d’água.RICHNESS AND DISTRIBUTION OF AQUATIC MACROPHYTES SPECIES IN THE GUARIBAS RIVER, PICOS, PIAUÍ STATEABSTRACTAquatic macrophytes play important roles in the aquatic environment, contributing to environmental structuring and biological balance. The present study had as objective to know how environmental factors interfere in the biological richness and in the distribution of aquatic macrophytes in theGuaribas river, water body of the semiarid strongly altered by anthropic actions, municipality of Picos, Piauí. For that, samples were collected monthly in five stations in the urban section of the referred river, from September / 2018 to February / 2019. For the sampling of vegetables, a quadrant with sides of 25 cm (0.0625 m2) was used. The material was taken to the Botany Laboratory ofthe Federal University of Piauí, Picos campus, where it was washed, separated and identified. 24 species were listed, distributed in 13 botanical families, among which were most representative: Poaceae (5), Cyperaceae (3), Fabaceae (3), Araceae (2), Convolvulaceae (2) and Polygonaceae (2). The most common biological forms were amphibians and emergent, amphibious and free floating.The greatest floristic richness occurred in the months of February and September with 18 and 16 species, respectively. It is concluded that the diversity of aquatic macrophytes in the Guaribas River was influenced by environmental and anthropic factors, being favored by the event of rains, succession of species and eutrophication of the water body.
Cytogenetic study in the Brazilian semiarid lizard Tropidurus hispidus (Squamata, Tropiduridae)
Different classes of repetitive DNA sequences are found in eukaryotes, often composing substantial portions of the genome, associated with their important role in the structural and functional genome organization. In this work, we mapped repetitive DNA sequences (18S rDNA, microsatellites and telomeric motifs) in the karyotype of Tropidurus hispidus, a species of lizard from the Brazilian semiarid region. We found a diploid number of 2n = 36 (6 pairs of biarmed macrochromosomes and 12 pairs of microchromosomes). The 18S rDNA clusters were localized at the subterminal region of the long arm of pair 2. The telomeric probes produced signals at terminal, interstitial and centromeric positions of some chromosome pairs, which might indicate the occurrence of chromosomal rearrangements via chromosome fusions. Microsatellite sequences were found in at least two distinct patterns - clustered in the telomeric/pericentromeric regions or observed as scattered signals in the chromosomes. This study represents an initial step to explore the evolutionary dynamics of repetitive sequences in the Tropidurus genus and considering the scarcity of data concerning the chromosomal mapping of repetitive sequences in Tropiduridae species, it reinforces the importance of integrating other methodologies, including the isolation and physical mapping of different repetitive DNA sequences, contributing to understanding the patterns of karyotypic evolution in lizards.Asociación Herpetológica Argentin
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In
the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost