Genetic variability of Brazilian strains of the Microcystis aeruginosa complex (Cyanobacteria/Cyanophyceae) using the phycocyanin intergenic spacer and flanking regions (cpcBA)

The genetic and morphological variability among 15 Brazilian strains of Microcystis aeruginosa (Kütz.) Kütz. collected from four locations was examined and compared with several reference strains of M. aeruginosa, M. viridis (A. Br.) Lemm. and M. wesenbergii (Kom.) Kom. in Kondr. Brazilian strains were classified by morphological features and by comparison of the nucleotide sequences of the cpcBA intergenic spacer and flanking regions. Our results indicate that Brazilian strains classified as M. aeruginosa are phylogenetically diverse compared with reference strains of M. aeruginosa and that the current taxonomy underestimates genetic diversity within M. aeruginosa. The data also demonstrate that morphological criteria alone are inadequate to characterize Microcystis species. Although colonial characters were shown to vary considerably in culture, some genetic lineages demonstrated consistent cellular diameter ranges, indicating that cell size has value as a taxonomic character. The detection of six M. aeruginosa genotypes in a single water body indicates that morphological approaches can also seriously underestimate the diversity of Microcystis bloom populations.

Molecular analysis of the rDNA ITS-1 intergenic spacer in Drosophila mulleri, D-arizonae, and their hybrids

We analyzed the ITS-1 spacer region of the rDNA in Drosophila mulleri and D. arizonae, two sibling species belonging to the mulleri complex (repleta group) and in hybrids obtained in both cross directions. In spite of several previous studies showing the incompatibility of crosses involving D. arizonae females and D. mulleri males, we were able to obtain hybrids in this direction. Complete ITS-1 region was amplified using primers with homology at the 3'-end of the 18S rDNA and the 5'-end of the 5.8S rDNA genes. Our data demonstrated that D. mulleri and D. arizonae can be differentiated as they present a difference in length for the ITS-1 region. The amplified fragment for this region in D. mulleri has a length of 600 bp, whereas in D. arizonae this fragment is about 500 bp. It was also observed that male and female hybrids obtained in both cross directions present two amplified fragments, confirming the location of the ribosomal cistrons in the X chromosomes and microchromosomes of both parental species.

Ribosomal DNA ITS-1 intergenic spacer polymorphism in triatomines (Triatominae, Heteroptera)

The length polymorphism of ribosomal DNA ITS-1 intergenic spacer was analyzed in eight species of triatomines belonging to Triatoma, Rhodnius, and Panstrongylus genera. The analyzed species were Rhodnius domesticus, R. neivai, R. robustus, Triatoma brasiliensis, T. infestans, T. vitticeps, Panstrongylus megistus, and P. herreri. These insects are vectors of Chagas' disease, one of the most prominent public health problems among South American countries. This work allowed the differentiation between species of the Triatomini and Rhodniini tribes through the analysis of ITS-1 length polymorphism by PCR and RFLP techniques. The species of the Triatoma and Panstrongylus genera presented an amplified ITS-1 fragment between 600 and 1000 bp, whereas Rhodnius presented a less variable ITS-1 length fragment, around 300 bp, which could reflect the monophyletic origin of the Rhodniini tribe. Species belonging to this genus were further differentiated by RFLP with HaeIII and AluI endonucleases. Our results corroborate the hypothesis of polyphyletic origin in this group of insects and contribute to knowledge about evolutionary relationships in triatomines.

Análise filogenética de linhagens de Xylella fastidiosa de diferentes hospedeiros baseada na sequencia da região intergênica 16S-23S rDNA

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Differentiation of Acidithiobacillus ferrooxidans and A-thiooxidans strains based on 16S-23S rDNA spacer polymorphism analysis

Restriction fragment length polymorphism (RFLP) and sequence analyses of the PCR-amplified 16S-23S rDNA intergenic spacer (ITS) were used for differentiating Acidithiobacillus thiooxidans strains from other related acidithiobacilli, including A. ferrooxidans and A. caldus. RFLP fingerprints obtained with AluI, DdeI, HaeIII, HinfI and MspI enabled the differentiation of all Acidithiobacillus reference strains into species groups. The A. thiooxidans strains investigated (metal mine isolates) yielded identical RFLP patterns to the A. thiooxidans type strain (ATCC 19377(T)), except for strain DAMS, which had a distinct pattern for all enzymes tested. Fourteen A. ferrooxidans mine strains were assigned to 3 RFLP groups, the majority of which were grouped with A. ferrooxidans ATCC 23270(T). The spacer region of one representative strain from each of the RFLP groups obtained was subjected to sequence analysis, in addition to eleven additional A. thiooxidans strains isolated from sediment and water samples, and A. caldus DSM 8584(T). The tRNA(IIe) and tRNA(Ala) genes, present in all strains analyzed, showed high sequence similarity. Phylogenetic analysis of the ITS sequences differentiated all three Acidithiobacillus species. Inter- and infraspecific genetic variations detected were mainly due to the size and sequence polymorphism of the ITS3 region. Mantel tests showed no significant correlation between ITS sequence similarity and the geographical origin of strains. The results showed that the 16S-23S rDNA spacer region is a useful target for the development of molecular-based methods aimed at the detection, rapid differentiation and identification of acidithiobacilli. (C) 2004 Elsevier SAS. All rights reserved.

PHYLOGENETIC STUDY OF GEITLERINEMA AND MICROCYSTIS ( CYANOBACTERIA) USING PC-IGS AND 16S-23S ITS AS MARKERS: INVESTIGATION OF HORIZONTAL GENE TRANSFER

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análises isoenzimáticas, moleculares e ultraestruturais em camarões dulcícolas do gênero Macrobrachium

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aplicação de DNA Barcode na identificação de espécies dos gêneros Senna, Lantana e Casearia

Pós-graduação em Biotecnologia - IQ

Phylogeography of Batrachospermum macrosporum (Batrachospermales, Rhodophyta) from North and South America

Phylogeographic trends in Batrachospermum macrosporum Mont. were investigated using the mitochondrial intergenic spacer between the cytochrome oxidase subunit 2 and 3 genes (cox2-3). A total of 11 stream segments were sampled with seven in the coastal plain of North America and four in tropical areas of South America. Fifteen thalli were sampled from seven streams, 14 thalli from two streams, and eight thalli from two streams. There were 16 haplotypes detected using 149 individuals. of the eight haplotypes from locations in North America, all were 334 base pairs (bp) in length, and of those from South America, five were 344 bp, and three were 348 bp. Two individual networks were produced: one for the haplotypes from North America and another for those from South America, and these could not be joined due to the large number of base pair differences. This split between haplotypes from North and South America was confirmed with sequence data of the rbcL gene. There was very little genetic variation among the haplotypes from the North American locations, leading us to hypothesize that these are fairly recent colonization events along the coastal plain. In contrast, there was high variation among haplotypes from South America, and it would appear that the Amazon serves as a center of diversity. We detected considerable variation in haplotypes among streams, but frequently, a single haplotype in an individual stream segment, which is consistent with data from previous studies of other batrachospermalean taxa, may suggest a single colonization event per stream.

Biofilm microbial communities of denture stomatitis

Introduction: Denture stomatitis is a common lesion that affects denture wearers. Its multifactorial etiology seems to depend on a complex and poorly characterized biofilm. The purpose of this study was to assess the composition of the microbial biofilm obtained from complete denture wearers with and without denture stomatitis using culture-independent methods.Methods: Samples were collected from healthy denture wearers and from patients with denture stomatitis. Libraries comprising about 600 cloned 16S ribosomal DNA (rDNA) bacterial sequences and 192 cloned eukaryotic internal transcribed spacer (ITS) region sequences, obtained by polymerase chain reactions, were analyzed.Results: The partial 16S rDNA sequences revealed a total of 82 bacterial species identified in healthy subjects and patients with denture stomatitis. Twenty-seven bacterial species were detected in both biofilms, 29 species were exclusively present in patients with denture stomatitis, and 26 were found only in healthy subjects. Analysis of the ITS region revealed the presence of Candida sp. in both biofilms.Conclusion: The results revealed the extent of the microbial flora, suggesting the existence of distinct biofilms in healthy subjects and in patients with denture stomatitis.

Reproductive ecology of the freshwater red alga Batrachospermum delicatulum (Batrachospermales, Rhodophyta) in three tropical streams

Batrachospermum delicatulum specimens from three stream segments were analyzed from a tropical region in south-eastern Brazil (20°18′- 20°49′S, 49°13′-49°46′W). Physical and chemical parameters and the spatial placement of thalli were investigated along with the reproductive characteristics of the gametophytic phase. Sequence data of the cox 2-3 spacer region was also utilized to evaluate genetic variation in individuals within and among stream segments. Gametophyte occurred under relatively diverse environmental conditions, whereas thalli abundance was weakly or not correlated to environmental variables within the stream segments. All specimens examined were dioecious. The ratio of male/female plants was relatively low (0.5 to 1.3) and male plants tended to occur as clumps (two or three plants together). High reproductive success was observed, as indicated by the occurrence of 100% fertilized (carposporophytic) female plants. This is similar to previous reports for this and other dioecious species, which is remarkable considering the relatively low proportion of male/female plants. Results support the two hypotheses to explain the high reproductive success in dioecious species. The occurrence of male plants in clumps was evidence for a strict spatial relationship (i.e. male plants located in upstream position of female plants in order to release spermatia, which would be carried by eddies through female plants). In contrast, the occurrence of male and female plants adjacent to each other allowed outcrossing among neighboring plants with intermingled male and female branches, which seemed more applicable to some situations (low turbulence habitats). The cox 2-3 spacer region from the 18 individuals sequenced was 376 bp and the DNA sequence was identical with no base pair substitutions. Likewise, a previous study of another Batrachospermum species showed that the same haplotypes were present in all stream segments from the same drainage basin, even though the stream segments were a considerable distance apart. Short distance dispersal either by small birds or waterway connectivity might explain these findings.

Nuclear mitochondrial-like sequences in ants: Evidence from Atta cephalotes (Formicidae: Attini)

Nuclear mitochondrial-like sequences (numts) are copies of mitochondrial DNA that have migrated to the genomic DNA. We present the first characterization of numts in ants, these numts being homologues to a mitochondrial DNA fragment containing loci the 3′ portion of the cytochrome oxidase I gene, an intergenic spacer, the tRNA leucine gene and the 5′ portion of the cytochrome oxidase II gene. All 67 specimens of Atta cephalotes (Hymenoptera: Formicidae: Attini) investigated had these homologues, which are within two monophyletic groups that we called numt1 and numt2. Numt1 and numt2 sequences are less variable than mitochondrial sequences and released from the severe purifying selection constraining the evolution of mitochondrial genes. Their formation probably involved bottlenecks related to two distinct transfer events of ancient and fast evolving mitochondrial DNA fragments to comparative slowly evolving nuclear DNA regions. © 2007 The Authors.

Intraspecific variation and emendation of Hannaella kunmingensis

In order to investigate the intraspecific variability in Hannaella kunmingensis, 11 isolates, including the type strain, were analyzed for their morphological and biochemical traits. The combined internal transcribed spacer region (ITS), D1/D2 domains of the large subunit rDNA (LSU), and cytochrome b gene were examined using phylogenetic and parsimony network analyses. Our investigations revealed differences in colony morphology as well as differences in 31 out of 64 phenotypic characteristics examined, including growth in lactose, vitamin free medium, xylitol, L-arabinitol, and nitrite. Growth in the presence of 0. 1 % cycloheximide was also highlighted in H. kunmingensis. All the 11 strains were conspecific in the LSU; however, variations of about 2. 5 % were found in the ITS while isolate CBS 8356 exhibited a 27. 3 % divergence from the other strains in the cytochrome b gene. Parsimony network analysis revealed the existence of three haplotypes among the H. kunmingensis strains studied but excluded CBS 8356 from the network connecting these haplotypes. This study contributes to the knowledge of the intraspecific diversity of H. kunmingensis. To accommodate such intraspecific variations, an emendation of the species diagnosis is proposed. © 2012 German Mycological Society and Springer.

Filogeografia de duas espécies de Rhodophyta da ordem Batrachospermales no Brasil

Pós-graduação em Microbiologia - IBILCE

Avaliação da agressividade e caracterização genética de linhagens de Ralstonia Solanacearum isoladas de diferentes plantas hospedeiras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)