Search

This study evaluated the feasibility of using the Ribulose Bisphosphate Carboxylase Large subunit gene (rbcL) and the Internal Transcribed Spacers 1 and 2 of the nuclear rDNA (nuITS1 and nuITS2) markers for identifying a very diverse, albeit poorly known group, of green microalgae from neotropical inland waters. Fifty-one freshwater green microalgae strains isolated from Brazil, the largest biodiversity reservoir in the neotropics, were submitted to DNA barcoding. Currently available universal primers for ITS1-5.8S-ITS2 region amplification were sufficient to successfully amplify and sequence 47 (92%) of the samples. On the other hand, new sets of primers had to be designed for rbcL, which allowed 96% of the samples to be sequenced. Thirty-five percent of the strains could be unambiguously identified to the species level based either on nuITS1 or nuITS2 sequences' using barcode gap calculations. nuITS2 Compensatory Base Change (CBC) and ITS1-5.8S-ITS2 region phylogenetic analysis, together with morphological inspection, confirmed the identification accuracy. In contrast, only 6% of the strains could be assigned to the correct species based solely on rbcL sequences. In conclusion, the data presented here indicates that either nuITS1 or nuITS2 are useful markers for DNA barcoding of freshwater green microalgae, with advantage for nuITS2 due to the larger availability of analytical tools and reference barcodes deposited at databases for this marker.

Background The present work aimed to evaluate the antimycobacterial activity and cytotoxicity of Microcystis aeruginosa toxins, the MC-LR variant and purified extract of [D-Leu1] microcystin-LR. Methods The antimicrobial activity of M. aeruginosa extract and microcystin was evaluated by resazurin microtiter assay against Mycobacterium tuberculosis, M. terrae, M. chelonae and M. kansasii. The cytotoxicity assay was performed by trypan blue exclusion against the HTC cell line. Results Antimicrobial activity was observed in the hexanic extract of M. aeruginosa (RST 9501 strain) against M. tuberculosis, including sensitive and resistant strains with minimal inhibitory concentrations (MIC) between 1.93 μM and 0.06 μM. The high activity of M. aeruginosa hexanic extract could be attributed to the major presence of the toxins MC-LR and [D-Leu1] MC-LR that showed activity at MIC between 53 and 0.42 μM against tested mycobacterial strains. Even at the highest concentration tested, no toxicity of M. aeruginosa extracts was identified against HTC cells. Conclusions These preliminary results suggest that [D-Leu1] MC-LR is a promising candidate for the development of a new antimycobacterial agent.

O presente trabalho apresenta um diagnóstico dos poços tubulares profundos e da qualidade das águas subterrâneas do município de Concórdia, localizado na região meio-oeste de Santa Catarina, Brasil. Foram cadastrados 686 poços no município, distribuídos numa área de cerca de 800 Km². Destes, 511 poços estão em operação e 148 foram considerados secos ou desativados. Os resultados revelaram a existência de 98 poços na zona urbana e 579 no meio rural, sendo 304 de uso comunitário. As análises de parâmetros fisicoquímicos realizadas em amostras de água obtidas de 32 poços comunitários destinados exclusivamente para consumo humano apontam para a existência de problemas pontuais de qualidade. No entanto, a análise microbiológica aponta dados preocupantes, principalmente relacionadas à ocorrência de contaminação por coliformes, com presença de E. coli em 25% das amostras coletadas. Estas informações evidenciam a gravidade do cenário de contaminação das águas subterrâneas da região do município de Concórdia e constituem um importante subsídio na tomada de decisões para o planejamento e a execução dos programas de gestão integrada da água, visando a proteção e uso sustentável deste recurso.

Esse trabalho trata do diagnóstico dos poços tubulares profundos e da qualidade das águas subterrâneas na bacia do rio Jacutinga e Sub-Bacias Contíguas, localizada na região meio-oeste de Santa Catarina, Sul do Brasil. No território da bacia foram identificados 2.477 poços perfurados, distribuídos numa área de 2.170 Km². Destes, 1.531 poços estão em operação e 648 foram considerados secos. A análise das informações incluem, além da qualidade da água de 100 poços de uso comunitário, as características hidrodinâmicas, aspectos construtivos dos poços e uso da água. Foi observado um número expressivo de poços com a qualidade de água comprometida, principalmente do ponto de vista microbiológico. Essas informações constituem um importante subsídio na tomada de decisões para o planejamento e execução dos programas de gestão integrada da água, objetivando a proteção e uso sustentável deste recurso.

The concentration of microcystin (MC) in the Kucukcekmece Lagoon, Istanbul, Turkey, and the physicochemical and biological parameters of water quality were investigated from October 2000 to June 2003. Water samples were collected from surface waters at three sites. Most bloom samples were dominated by Microcystis aeruginosa. The major microcystin variants detected by HPLC-PDA were microcystin-YR and microcystin-LR. Microcystin concentration increased dramatically from early summer to early autumn and thereafter tended to decrease. The toxin concentration found in the filtered samples from surface waters varied between 0.06 and 24.2 g L-1 microcystin-LR equivalents. Each year extensive fish mortality was recorded between mid-June and early October, coinciding with heavy algal blooms. A comparison of the conditions associated with cyanotoxin episodes in 2000, 2001, and 2002 showed that the microcystin increase was related to temperature, high concentration of dissolved nutrients, high light intensity (PAR). The highest MC concentrations were recorded at temperatures between 24C and 28.5C. Field data showed that the highest MC concentration (>3 g L-1) and the highest cyanobacterial biomass (>30 mg L-1) corresponded to a total nitrogen:total phosphorus ratio greater than 7:1. The highest concentrations of M. aeruginosa biomass (173 mg L-1) and MC (24.2 g L-1 MC-LR equiv.) and the highest salinity (8.8%) were measured concurrently in the lagoon. To our knowledge, this is the first evidence of cyanobacterial toxins in the Kucukcekmece Lagoon. 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 277284, 2005. [ABSTRACT FROM AUTHOR]