Haywood Laughinghouse Iv

A toxic cyanobacterial bloom in an urban coastal lake, Rio Grande do Sul state, Southern Brazil

O numero de relatos de ocorrencias de floracoes de cianobacterias em todo o mundo vem aumentando consideravelmente e na maioria desses episodios, as toxinas dominantes sao as microcistinas. O presente estudo relata a ocorrencia de floracao na Lagoa do Violao, municipio de Torres, RS, em janeiro de 2005. As amostras coletadas em 13/01/2005 foram submetidas a estudos taxonomicos, toxicologicos e quimicos. O exame microscopico do fitoplancton mostrou a dominância das especies Microcystis protocystis e Sphaerocavum cf. brasiliense; foram observadas, tambem, Microcystis panniformis, Anabaena oumiana,Cylindrospermopsis raciborskii e Anabaenopsis elenkinii f. circularis. A toxicidade da floracao foi confirmada atraves de ensaio intraperitonial em camundongos e a analise quimica de extratos obtidos da biomassa liofilizada mostrou que a substância majoritaria era a anabaenopeptina F, seguida por anabaenopeptina B, microcistina-LR e microcistina-RR.

On the use of high‐throughput sequencing for the study of cyanobacterial diversity in Antarctic aquatic mats

The study of Antarctic cyanobacterial diversity has been mostly limited to morphological identification and traditional molecular techniques. High‐throughput sequencing (HTS) allows a much better understanding of microbial distribution in the environment, but its application is hampered by several methodological and analytical challenges. In this work, we explored the use of HTS as a tool for the study of cyanobacterial diversity in Antarctic aquatic mats. Our results highlight the importance of using artificial communities to validate the parameters of the bioinformatics procedure used to analyze natural communities, since pipeline‐dependent biases had a strong effect on the observed community structures. Analysis of microbial mats from five Antarctic lakes and an aquatic biofilm from the Sub‐Antarctic showed that HTS is a valuable tool for the assessment of cyanobacterial diversity. The majority of the operational taxonomic units retrieved were related to filamentous taxa such as Leptolyngbya and Phormidium, which are common genera in Antarctic lacustrine microbial mats. However, other phylotypes related to different taxa such as Geitlerinema, Pseudanabaena, Synechococcus, Chamaesiphon, Calothrix, and Coleodesmium were also found. Results revealed a much higher diversity than what had been reported using traditional methods and also highlighted remarkable differences between the cyanobacterial communities of the studied lakes. The aquatic biofilm from the Sub‐Antarctic had a distinct cyanobacterial community from the Antarctic lakes, which in turn displayed a salinity‐dependent community structure at the phylotype level.

Cephalothrix gen. nov. (Cyanobacteria): towards an intraspecific phylogenetic evaluation by multilocus analyses.

For more than a decade, the taxonomy of the Phormidiaceae has been problematic, since morphologically similar organisms represent phylogenetically distinct entities. Based on 16S rRNA gene sequence analyses, the polyphyletic genus Phormidium and other gas-vacuolated oscillatorioids appear scattered throughout the cyanobacterial tree of life. Recently, several studies have focused on understanding the oscillatorioid taxa at the generic level. At the specific level, few studies have characterized cyanobacterial strains using combined datasets (morphology, ultrastructure and molecular multilocus analyses). Using a multifaceted approach, we propose a new, well-defined genus, Cephalothrix gen. nov., by analysing seven filamentous strains that are morphologically intermediate between gas-vacuolated taxa and Phormidium. Furthermore, we characterize two novel species: Cephalothrix komarekiana sp. nov. (strains CCIBt 3277, CCIBt 3279, CCIBt 3523, CCALA 155, SAG 75.79 and UTEX 1580) and Cephalothrix lacustris sp. nov. (strain CCIBt 3261). The generic name and specific epithets are proposed under the provisions of the International Code of Nomenclature for Algae, Fungi, and Plants.

Variability of the chromosomal number and meiotic behavior in populations of Bidens pilosa L. (Asteraceae) from southern Brazil

Abstract Bidens pilosa is a medicinal species from the Asteraceae family, with a wide geographical distribution, found all over Brazil. There are no reports on chromosomal studies from the Brazilian South. Mitotic chromosomes, meiotic behavior, and pollen viability were studied in 6 populations of B. pilosa from Rio Grande do Sul State, Brazil, using conventional staining with acetic orcein 2%. The populations include cytotypes with a variable number of chromosomes: 2n=36, 2n=48 and 2n=54, indicating polyploidy and aneuploidy. The meiotic process was considered regular, even though irregular chromosomal pairing appeared, which is normal in cytotypes from a polyploid complex. The irregularities observed were mainly on univalent, trivalent, and tetravalent pairing associations. However, the pollen viability estimative was high.

Toxic Cyanobacteria in Svalbard: Chemical Diversity of Microcystins Detected Using a Liquid Chromatography Mass Spectrometry Precursor Ion Screening Method

Cyanobacteria synthesize a large variety of secondary metabolites including toxins. Microcystins (MCs) with hepato- and neurotoxic potential are well studied in bloom-forming planktonic species of temperate and tropical regions. Cyanobacterial biofilms thriving in the polar regions have recently emerged as a rich source for cyanobacterial secondary metabolites including previously undescribed congeners of microcystin. However, detection and detailed identification of these compounds is difficult due to unusual sample matrices and structural congeners produced. We here report a time-efficient liquid chromatography-mass spectrometry (LC-MS) precursor ion screening method that facilitates microcystin detection and identification. We applied this method to detect six different MC congeners in 8 out of 26 microbial mat samples of the Svalbard Archipelago in the Arctic. The congeners, of which [Asp3, ADMAdda5, Dhb7] MC-LR was most abundant, were similar to those reported in other polar habitats. Microcystins were also determined using an Adda-specific enzyme-linked immunosorbent assay (Adda-ELISA). Nostoc sp. was identified as a putative toxin producer using molecular methods that targeted 16S rRNA genes and genes involved in microcystin production. The mcy genes detected showed highest similarities to other Arctic or Antarctic sequences. The LC-MS precursor ion screening method could be useful for microcystin detection in unusual matrices such as benthic biofilms or lichen.