Characterization of Recombinant His-Tag Protein Immobilized onto Functionalized Gold Nanoparticles

The recombinant polyhistidine-tagged hemoglobin I ((His)6-rHbI) from the bivalve Lucina pectinata is an ideal biocomponent for a hydrogen sulfide (H2S) biosensor due to its high affinity for H2S. In this work, we immobilized (His)6-rHbI over a surface modified with gold nanoparticles functionalized with 3-mercaptopropionic acid complexed with nickel ion. The attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the modified-gold electrode displays amide I and amide II bands characteristic of a primarily α-helix structure verifying the presence of (His)6-rHbI on the electrode surface. Also, X-ray photoelectron spectroscopy (XPS) results show a new peak after protein interaction corresponding to nitrogen and a calculated overlayer thickness of 5.3 nm. The functionality of the immobilized hemoprotein was established by direct current potential amperometry, using H2S as the analyte, validating its activity after immobilization. The current response to H2S concentrations was monitored over time giving a linear relationship from 30 to 700 nM with a corresponding sensitivity of 3.22 × 10−3 nA/nM. These results confirm that the analyzed gold nanostructured platform provides an efficient and strong link for polyhistidine-tag protein immobilization over gold and glassy carbon surfaces for a future biosensors development.

Characterization of Histone Genes from the Bivalve Lucina Pectinata

Lucina pectinata is a clam that lives in sulfide-rich environments and houses intracellular sulfide-oxidizing endosymbionts. To identify new Lucina pectinata proteins, we produced libraries for genome and transcriptome sequencing and assembled them de novo. We searched for histone-like sequences using the Lucina pectinata histone H3 partial nucleotide sequence against our previously described genome assembly to obtain the complete coding region and identify H3 coding sequences from mollusk sequences in Genbank. Solen marginatus histone nucleotide sequences were used as query sequences using the genome and transcriptome assemblies to identify the Lucina pectinata H1, H2A, H2B and H4 genes and mRNAs and obtained the complete coding regions of the five histone genes by RT-PCR combined with automated Sanger DNA sequencing. The amino acid sequence conservation between the Lucina pectinata and Solen marginatus histones was: 77%, 93%, 83%, 96% and 97% for H1, H2A, H2B, H3 and H4, respectively. As expected, the H3 and H4 proteins were the most conserved and the H1 proteins were most similar to H1′s from aquatic organisms like Crassostrea gigas, Aplysia californica, Mytilus trossulus and Biomphalaria glabrata. The Lucina pectinata draft genome and transcriptome assemblies, obtained by semiconductor sequencing, were adequate for identification of conserved proteins as evidenced by our results for the histone genes.

CALDO DE LAMBRETA: ETNOGRAFIA DOS SABERES DA TRADIÇÃO NA ATIVIDADE EXTRATIVISTA DAS COLETORAS DA LUCINA PECTINATA NA VILA DE GARAPUÁ, CAIRU - BA / LAMBRETA BROTH: ETHNOGRAPHY OF TRADITION KNOWLEDGE IN ACTIVITY OF GATHERERS OF LUCINA PECTINATA IN THE VILLAGE OF GARAPUÁ, CAIRU - BA

Este estudo visou conhecer a coleta de um molusco chamado de lambreta (Lucina pectinata) por marisqueiras na vila de Garapuá, Cairu, no Baixo Sul baiano, perpassando pelas artes de pesca, organização do trabalho, saúde ocupacional e as melhores condições de tempo e maré. Utilizou-se o método etnográfico com diários de campo, entrevistas e registro fotográfico. Os grupos de trabalho das marisqueiras são formados majoritariamente por mulheres que fazem rodízios na exploração dos mangues, em cinco jornadas semanais de quatro horas diárias de trabalho. Cada integrante obtém em torno de dez dúzias de lambreta por dia, vendidas a atravessadores a preços abaixo do valor de mercado. A coleta do animal – localizado através de um fio d’água subindo à superfície – é feita com a mão ou com o uso do facão e condicionada pelas fases da lua, pelo fluxo das marés e pelo caráter agreste do ecossistema manguezal. As coletoras levam consigo o samburá (um cesto para carregar peixe), alimentação, vestimenta e óleo diesel, usado como repelente. A diminuição dos estoques naturais de lambreta leva as marisqueiras a aumentar as horas de trabalho no mangue e as distâncias percorridas, assim como a desejarem abandonar a tradicional atividade, buscando outras fontes de renda, como o beneficiamento do camarão.ABSTRACTThis study aims to carry out the gathering by hand of a mollusc called ‘Lambreta’ (Lucina pectinata) by shellfish gatherers in the village of Garapuá, Cairu, in Southern Bahia, Brazil, including the fishing gear, work organization, occupational health and better weather and tide conditions. We used the ethnographic method with daily field diaries, interviews and photographic record. The working groups are composed mostly by women who take turns in the exploitation of mangroves, working five days a week, four hours a day. Each member collects around ten dozen lambretas per day, which are sold to middlemen below market prices. The molluscs gathering – identified by a trickle of water rising to the surface – is done by hand or using a machete and it is conditioned by moon phases, tidal streams and the wild features of the mangrove ecosystem. The collectors take with them the samburá (a kind of creel), food, clothing and diesel oil, used as insect repellent. The decline in natural stocks of lambreta forces collectors to increase their working hours in the mangroves and the distance traveled, as well as it makes them want to leave this traditional activity, and seek for other sources of income such as shrimp processing.

Morphological variations of the shell of the bivalve Lucina pectinata (Gmelin, 1791)

In Martinique, the species Lucina pectinata (Gmelin, 1791) is called "mud clam, white clam or mangrove clam" by bivalve fishermen depending on the harvesting environment. Indeed, the individuals collected have differences as regards the shape and colour of the shell. The hypothesis is that the shape of the shell of L. pectinata (P. pectinatus) shows significant variations from one population to another. This paper intends to verify this hypothesis by means of a simple morphometric study. The comparison of the shape of the shell of individuals from different populations was done based on samples taken at four different sites. The standard measurements (length (L), width or thickness (E - épaisseur) and height (H)) were taken and the morphometric indices (L/H; L/E; E/H) were established. These indices of shape differ significantly among the various populations. This intraspecific polymorphism of the shape of the shell of P. pectinatus could be related to the nature of the sediment (granulometry, density, hardness) and/or the predation. The shells are significantly more elongated in a loose muddy sediment than in a hard muddy sediment or one rich in clay. They are significantly more convex in brackish environments and this is probably due to the presence of more specialised predators or of more muddy sediments.

CARACTERIZAÇÃO FÍSICO-QUÍMICA E MICROBIOLÓGICA DA CARNE DO MOLUSCO BIVALVE SARNAMBI (Phacoides pectinitus) COLETADO NAS PRAIAS EM ALGODOAL E SALINÓPOLIS, NO PARÁ

O Sarnambí (Lucina pectinata) é um molusco muito encontrado em praias paraenses, e possui grande aceitabilidade por parte de seus consumidores. No entanto, poucas pesquisas foram realizadas visando conhecer suas caracterisiticas físico-quimicas e higiênico-sanitárias Assim, este trabalho objetivou avaliar as caracterisiticas físico-químicas e microbiologica da carne do sarnambí coletada na praia da Lua Cheia, localizada na Ilha de Algodoal (Amostra A) e praia do Paraíso na Vila de Cuiarana, município de Salinópolis (Amostras B), no Estado do Pará, e realizar um levantamento sobre o método de extração da carne deste molusco. Foram determinados os niveis de umidade, proteínas, lipídeos, colesterol, resíduo mineral fixo, carboidrato, valor calórico, pH, bases nitrogenadas voláteis totais, e minerais (ferro, cobre, magnésio, manganês, zinco e potássio) para a caracterização físico-química. As análises microbiologicas foram: contagem padrão de aeróbias mesófilas, contagem de fungos filamentosos e leveduras, Coliformes Totais e Termotolerantes, Staphylococcus aureus, pesquisa de Salmonella e Clostridim Sulfito Redutores. Os resultados das análises físico-química demonstraram que este alimento é considerado uma fonte expressiva de proteína, e baixos índices de lipídeos e valor calórico. Não houve contaminação por Staphylococcus aureus, Salmonella e Clostridium Sulfito Redutores em nenhuma das amostras avaliadas, o que garante dizer que as mesmas encontram-se dentro dos padrões de qualidade e de acordo com a legislação vigente. Entretanto, houve contaminação em todas as amostras avaliadas de bactérias aeróbias mesófilas, fungos filamentosos e leveduras, e Coliformes Totais e Termotolerantes, confirmando a falta de cuidados higiênico-sanitários dos manipuladores e dos utensílios envolvidos no beneficiamento do alimento.