CARACTERIZAÇÃO CITOGENÉTICA DE UMA ESPÉCIE DE Spatuloricaria (SILURIFORMES, LORICARIIDAE) DO RIO XINGU, (PARÁ, AMAZÔNIA, BRASIL)

Genus Spatuloricaria (Loricariinae, Loricariidae) comprises 12 species which are not very precisely characterized, because morphological data are incipient and no karyotype information is available. In this work, was made the first cytogenetic characterization of a Spatuloricaria species of the Xingu River. Chromosomes were analyzed with conventional staining techniques, C banding, CMA3, DAPI, fluorescent in situ hybridization (FISH) with telomeric probes and rDNA18S. The results show that Spatuloricaria sp. has 2n=66 (6st/7sm/4m/16a) and a fundamental number (FN) of 92. The C-banding pattern revealed a distribution of heterochromatin in the centromeric and pericentromeric regions of the chromosomes and on the short arm of pair 15, coinciding with the DAPI labeling. FISH with rDNA 18S probes painted the terminal portion of chromosome pair eigth, corresponding to the CMA3 labeling, and a heteromorphism between the genomic blocks of this region was observed. The data obtained shall serve as cytotaxonomic markers for a better understanding of this group and its relationships within family Loricariidae, allowing inferences about the chromosomal evolution of the genus and its relations with other loricarids.Keywords: Loricariinae; cytotaxonomy; FISH; rDNA and telomeric probes.O gênero Spatuloricaria (Loricariinae, Loricariidae) compreende 12 espécies com caracterização pouco precisa, com dados morfológicos insipientes e nenhuma informação cariotípica disponível. Neste trabalho foi feita a primeira caracterização citogenética de uma espécie de Spatuloricaria do rio Xingu, utilizando técnicas de coloração convencional, bandeamento C, CMA3, DAPI, hibridização in situ fluorescente (FISH) com sondas teloméricas e DNAr18S. Os resultados mostram que Spatuloricaria sp. apresenta 2n=66 (6st+7sm+4m+16a) e número fundamental (NF) 92. A heterocromatina constitutiva (HC) está presente nas regiões centroméricas e pericentroméricas dos cromossomos e no braço curto do par 15, coincidindo com as marcações de DAPI. A FISH com sondas de DNAr 18S marcou o par cromossômico oito em sua porção terminal correspondente à marcação de CMA3, sendo observado heteromorfismo de tamanho dessa região. Não foram observadas sequências teloméricas intersticiais. Estes dados poderão servir como marcadores citotaxonômicos para a melhor compreensão do grupo e suas relações dentro da família Loricariidae, permitindo traçar inferências sobre a evolução cromossômica do gênero e suas relações com outros loricarídeos.Palavras-chave: Loricariinae, citotaxonomia, FISH, sondas DNAr, sequências teloméricas

Glycerol and Catalysis by Waste/Low-Cost Materials—A Review

The growing global demand for renewable energy sources can be reached using biofuels such as biodiesel, for example. The most used route to produce biodiesel is the transesterification reaction of oils or fats with short-chain alcohols, generating fatty acid esters (biodiesel) and a very important by-product, glycerol (Gly). Gly is widely used in different sectors of the industry, and in order to add value to this by-product, heterogeneous catalysis becomes a relevant tool, whether to transform glycerol into other chemical products of interest or even use it in the production of catalysts. Among the several studies found in the literature, the use of low-cost materials and/or wastes from the most diverse activities to prepare active catalytic materials for the transformation of Gly has been increasingly reported due to its valuable advantages, especially related to the cost of raw materials and environmental aspects. Thus, this brief review article presents the relationship between catalysis, low-cost materials, waste, and glycerol, through different studies that show glycerol being transformed through reactions catalyzed by materials produced from low-cost sources/waste or with the glycerol itself used as a catalyst

Zeolites: A Theoretical and Practical Approach with Uses in (Bio)Chemical Processes

This review provides a state-of-the-art summary of distributed zeolite technology, as well as identifying strategies to further promote the absorption of these materials in various areas of study. Zeolites are materials that can be synthesized or found in natural rock deposits a with a basic composition consisting in Al, Si, and O. Zeolite’s consideration as a future material is due to many facile synthesis methods to obtain different structures with variations in pore size, surface area, pore volume and physical properties. These methods are developed using the control of relevant synthesis parameters that influences structure formation, such as crystallization temperature, time of aging and/or crystallization, stoichiometric relationships between components of synthesis gel, pH of the medium, and in some cases the type of structure-directing agent. Each method will lead to geometric changes in the framework formation, making possible the formation of typical chemical bonds that are the fingerprint of any zeolitic structure (O-Si-O and Al-O-Si), forming typical acid sites that give specificity in zeolite and allows it to act as a nanoreactor. The specificity is a characteristic that in some cases depends on selectivity, a fundamental property derived of the porosity, mostly in processes that occur inside the zeolite. In processes outside the structure, the surface area is the main factor influencing this property. Moreover, there are many natural sources with adequate chemical composition to be used as precursors. Some of these sources are waste, minimizing the deposition of potential hazardous materials that can be recalcitrant pollutants depending on the environment. Besides its uses as a catalyst, zeolite serves as a support for many bioprocesses; therefore, this review aims to explain relevant aspects in chemical nature, physical properties, main methods of synthesis, main precursors used for synthesis, and relevant applications of zeolites in chemical catalysis and biological processes

Karyotype diversity and chromosomal organization of repetitive DNA in Tityus obscurus (Scorpiones, Buthidae)

Abstract Background Holocentric chromosomes occur in approximately 750 species of eukaryotes. Among them, the genus Tityus (Scorpiones, Buthidae) has a labile karyotype that shows complex multivalent associations during male meiosis. Thus, taking advantage of the excellent model provided by the Buthidae scorpions, here we analyzed the chromosomal distribution of several repetitive DNA classes on the holocentric chromosomes of different populations of the species Tityus obscurus Gervais, 1843, highlighting their involvement in the karyotypic differences found among them. Results This species shows inter- and intrapopulational karyotype variation, with seven distinct cytotypes: A (2n = 16), B (2n = 14), C (2n = 13), D (2n = 13), E (2n = 12), F (2n = 12) and G (2n = 11). Furthermore, exhibits achiasmatic male meiosis and lacks heteromorphic sex chromosomes. Trivalent and quadrivalent meiotic associations were found in some cytotypes. In them, 45S rDNAs were found in the terminal portions of two pairs, while TTAGG repeats were found only at the end of the chromosomes. In the cytotype A (2n = 16), the U2 snRNA gene mapped to pair 1, while the H3 histone cluster and C 0 t-1 DNA fraction was terminally distributed on all pairs. Mariner transposons were found throughout the chromosomes, with the exception of one individual of cytotype A (2n = 16), in which it was concentrated in heterochromatic regions. Conclusions Chromosomal variability found in T. obscurus are due to rearrangements of the type fusion/fission and reciprocal translocations in heterozygous. These karyotype differences follow a geographical pattern and may be contributing to reproductive isolation between populations analyzed. Our results also demonstrate high mobility of histone H3 genes. In contrast, other multigene families (45S rDNA and U2 snRNA) have conserved distribution among individuals. The accumulation of repetitive sequences in distal regions of T. obscurus chromosomes, suggests that end of chromosome are not covered by the kinetochore

Physical mapping of repetitive DNA suggests 2n reduction in Amazon turtles Podocnemis (Testudines: Podocnemididae).

Cytogenetic studies show that there is great karyotypic diversity in order Testudines (2n = 26-68), and that this may be mainly attributed to the presence/absence of microchromosomes. Members of the Podocnemididae family have the smallest diploid numbers of this order (2n = 26-28), which may be a derived condition of the group. Diverse studies suggest that repetitive-DNA-rich sites generally act as hotspots for double-strand breaks and chromosomal reorganization. In this context, we used fluorescent in situ hybridization (FISH) to map telomeric sequences (TTAGGG)n, 45S rDNA, and the genes encoding histones H1 and H3 in two species of genus Podocnemis. We also observed conservation of the 45S rDNA and H1 histone sequences (probable case of conserved synteny), but multiple conserved and non-conserved clusters of H3 genes, which colocalized with the interstitial telomeric sequences in the Podocnemis genome. Our results suggest that fusions have occurred between macro and microchromosomes or between microchromosomes, leading to the observed reduction in diploid number in the family Podocnemididae

Establishment and Characterization of a Primary Fibroblast Cell Culture from the Amazonian Manatee (<i>Trichechus inunguis</i>)

The vulnerable status of the Amazon manatee, Trichechus inunguis, indicates the need to seek measures to guarantee its conservation. In this context, the cultivation of cells in vitro is a strategy that should at least guarantee the preservation of their genetic material. Thus, we established for the first time a primary culture of Amazonian manatee fibroblasts (TINsf) from a skin biopsy of a young male. Karyotypic analysis of the 3rd, 7th, and 12th passages confirmed the taxonomic identity of the species T. inunguis (2n = 56/NF = 92) and indicated that this culture presents genomic stability. Gene and protein expression of vimentin at the 13th passage show the predominant presence of fibroblasts in TINsf. To test the cell line’s responsiveness to materials and demonstrate a possible application of this culture, it was exposed to andiroba seed oil (ASO), and its viability and proliferative capacity were evaluated. ASO demonstrated toxic effects at the highest concentrations and longest exposure times tested, reproducing results observed in human cultures, indicating the applicability of TINsf in toxicological and biotechnological studies. After cryopreservation, the TINsf line maintained its proliferative potential, indicating the establishment of a new culture available for future studies

Kinetic Activity of Chromosomes and Expression of Recombination Genes in Achiasmatic Meiosis of Tityus (Archaeotityus) Scorpions

Several species of Tityus (Scorpiones, Buthidae) present multi-chromosomal meiotic associations and failures in the synaptic process, originated from reciprocal translocations. Holocentric chromosomes and achiasmatic meiosis in males are present in all members of this genus. In the present study, we investigated synapse dynamics, transcriptional silencing by &gamma;H2AX, and meiotic microtubule association in bivalents and a quadrivalent of the scorpion Tityus maranhensis. Additionally, we performed RT-PCR to verify the expression of mismatch repair enzymes involved in crossing-over formation in Tityus silvestris gonads. The quadrivalent association in T. maranhensis showed delay in the synaptic process and long asynaptic regions during pachytene. In this species, &gamma;H2AX was recorded only at the chromosome ends during early stages of prophase I; in metaphase I, bivalents and quadrivalents of T. maranhensis exhibited binding to microtubules along their entire length, while in metaphase II/anaphase II transition, spindle fibers interacted only with telomeric regions. Regarding T. silvestris, genes involved in the recombination process were transcribed in ovaries, testes and embryos, without significant difference between these tissues. The expression of these genes during T. silvestris achiasmatic meiosis is discussed in the present study. The absence of meiotic inactivation by &gamma;H2AX and holo/telokinetic behavior of the chromosomes are important factors for the maintenance of the quadrivalent in T. maranhensis and the normal continuation of the meiotic cycle in this species

Double FISH with telomeric (TTAGGG)n probes and 45S rDNA.

<p>Telomeric (TTAGGG)n probes (in green) show the interstitial telomeric sequences in the pairs 1–5, 7 and 13, and in a single chromosome of the pair 6, and 45S rDNA (in red) in the proximal region of the short arm of the pair 1, adjacent to the interstitial telomeric sequences in (a) <i>P</i>. <i>expansa</i> and (b) <i>P</i>. <i>unifilis</i>. Scale bar = 10μm.</p