Spermiogenesis and spermatozoa ultrastructure in five species of the Curimatidae with some considerations on spermatozoal ultrastructure in the Characiformes

A espermiogênese nas espécies Steindachnerina insculpta, Cyphocharax gillii, C. modestus, C. spilotus e Potamorhina altamazonica de Curimatidae é caracterizada pelo desenvolvimento lateral do flagelo, rotação do núcleo, formação excêntrica da fossa nuclear e cromatina compactada em fibras espessas. Estes espermatozóides exibem uma cabeça esférica contendo um núcleo com cromatina altamente condensada em fibras espessas com pequenas áreas eletronlúcidas, e sem acrossoma. A fossa nuclear é do tipo moderado e excêntrico, penetrada pelo complexo centriolar. A peça média é pequena, tem muitas vesículas alongadas e um curto canal citoplasmático. Mitocôndrias podem ser alongadas, ramificadas ou em forma de C, e são separadas do segmento inicial do axonema pelo canal citoplasmático. O flagelo contém a estrutura clássica do axonema (9+2) e tem um compartimento membranoso na região inicial; não possui expansões laterais (fins). Somente pequenas diferenças foram observadas entre as espécies e gêneros analisados de Curimatidae. A espermiogênese e os espermatozóides de Curimatidae têm muitas das características encontradas em quase todas as outras espécies de Characiformes. Por outro lado, a presença de um compartimento membranoso na região inicial do flagelo dos curimatídeos, uma estrutura comum nos espermatozóides de muitos cipriniformes, é desconhecida em outros characiformes. Discute-se sobre a espermiogênese e espermatozóides de Characiformes.

Analysis of the synaptonemal complex of the nine-banded armadillo, Dasypus novemcinctus

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

Unique Derived Features in Spermiogenesis and Sperm Morphology Supporting a Close Relationship between the Species of Hollandichthys and Rachoviscus (Characiformes: Characidae)

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

Complex meiotic configuration of the holocentric chromosomes: the intriguing case of the scorpion Tityus bahiensis

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

Cytogenetic analyses of eight species in the genus Leptodactylus Fitzinger, 1843 (Amphibia, Anura, Leptodactylidae), including a new diploid number and a karyotype with multiple translocations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Artificial neural networks: A novel approach to analysing the nutritional ecology of a blowfly species, Chrysomya megacephala

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

Using network connectance and autonomy analyses to uncover patterns of photosynthetic responses in tropical woody species

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

Morphological patterns of extrafloral nectaries in woody plant species of the Brazilian cerrado

Extrafloral nectaries are nectar-secreting structures that are especially common among the woody flora of the Brazilian cerrado, a savanna-like vegetation. In this study, we provide morphological and anatomical descriptions of extrafloral nectaries (EFNs) occurring on vegetative and reproductive organs of several plant species from the cerrado, and discuss their function and ecological relevance. We describe the morphology and anatomy of EFNs of 40 species belonging to 15 woody families using scanning electron microscopy and light microscopy. We categorise EFNs following a structural-topographical classification, and characterise the vascularised and complex nectaries, amorphous nectaries and secretory trichomes. Fabaceae, Bignoniaceae, Malpighiaceae and Vochysiaceae were the plant families with the majority of species having EFNs. Ten species possess more than one morphotype of gland structure. Observations and experimental field studies in the cerrado support the anti-herbivore role of EFN-gathering ants in this habitat. Additional morphological studies of EFNs-bearing plants, including other growth forms (e.g. herbs and lianas), are being undertaken and will hopefully cast further light on the ecological relevance of these glands in the cerrado, especially with respect to their attractiveness to multiple visitors.

Functional and historical determinants of shape in the scapula of Xenarthran mammals: Evolution of a complex morphological structure

The mammalian scapula is a complex morphological structure, composed of two ossification plates that fuse into a single structure. Most studies on morphological differentiation in the scapula have considered it to be a simple, spatially integrated structure, primarily influenced by the important locomotor function presented by this element. We used recently developed geometric morphometric techniques to test and quantify functional and phylogenetic influences on scapular shape variation in fossil and extant xenarthran mammals. The order Xenarthra is well represented in the fossil record and presents a stable phylogenetic hypothesis for its genealogical history. In addition, its species present a large variety of locomotor habits. Our results show that approximately half of the shape variation in the scapula is due to phylogenetic heritage. This is contrary to the view that the scapula is influenced only by functional demands. There are large-scale shape transformations that provide biomechanical adaptation for the several habits (arboreality, terrestriality, and digging), and small scale-shape transformations (mostly related to the coracoid process) that are not influenced by function. A nonlinear relationship between morphometric and phylogenetic distances indicates the presence of a complex mixture of evolutionary processes acting on shape differentiation of the scapula. J. Morphol. 241,251-263, 1999. (C) 1999 Wiley-Liss, Inc.

Differential transcription of ribosomal cistrons denoting nucleolar dominance in hybrids of Drosophila mulleri and Drosophila navojoa (mulleri complex, Repleta group)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

DNA barcode discovers two cryptic species and two geographical radiations in the invasive drosophilid Zaprionus indianus

Comparing introduced to ancestral populations within a phylogeographical context is crucial in any study aiming to understand the ecological genetics of an invasive species. Zaprionus indianus is a cosmopolitan drosophilid that has recently succeeded to expand its geographical range upon three continents (Africa, Asia and the Americas). We studied the distribution of mitochondrial DNA (mtDNA) haplotypes for two genes (CO-I and CO-II) among 23 geographical populations. mtDNA revealed the presence of two well-supported phylogenetic lineages (phylads), with bootstrap value of 100%. Phylad I included three African populations, reinforcing the African-origin hypothesis of the species. Within phylad II, a distinct phylogeographical pattern was discovered: Atlantic populations (from the Americas and Madeira) were closer to the ancestral African populations than to Eastern ones (from Madagascar, Middle East and India). This means that during its passage from endemism to cosmopolitanism, Z. indianus exhibited two independent radiations, the older (the Eastern) to the East, and the younger (the Atlantic) to the West. Discriminant function analysis using 13 morphometrical characters was also able to discriminate between the two molecular phylads (93.34 +/- 1.67%), although detailed morphological analysis of male genitalia using scanning electron microscopy showed no significant differences. Finally, crossing experiments revealed the presence of reproductive barrier between populations from the two phylads, and further between populations within phylad I. Hence, a bona species status was assigned to two new, cryptic species: Zaprionus africanus and Zaprionus gabonicus, and both were encompassed along with Z. indianus and Zaprionus megalorchis into the indianus complex. The ecology of these two species reveals that they are forest dwellers, which explains their restricted endemic distribution, in contrast to their relative cosmopolitan Z. indianus, known to be a human-commensal. Our results reconfirm the great utility of mtDNA at both inter- and intraspecific analyses within the frame of an integrated taxonomical project.

Paracetamol degradation intermediates and toxicity during photo-Fenton treatment using different iron species

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

Cryptic species of Gryllus in the light of bioacoustic (Orthoptera: Gryllidae)

O gênero Gryllus destaca-se com um grande número de espécies descritas e representa um dos mais complexos gêneros na sistemática dos Orthoptera, caracterizado por um conjunto de espécies cosmopolitas e crípticas. Este trabalho compara os sons emitidos por espécimens de Gryllus coletados no campus da UNESP em Rio Claro (SP), bem como a morfologia e morfometria das pars stridens, com o objetivo de aplicar os resultados no reconhecimento de possíveis espécies crípticas e contribuir na discussão de processos de especiação. Três grupos de grilos foram discriminados por diferenças nas pars stridens e sons de chamado, caracterizados por diferentes ritmos, freqüências e composição das notas, indicando assim, a presença de três espécies no local analisado, morfologicamente pouco distintas. Diante dos resultados, sugere-se a utilização das características da pars stridens e do som de chamado como caracteres diagnósticos imprescindíveis na taxonomia dos Gryllus.

Surprising genomic diversity in the Neotropical fish Synbranchus marmoratus (Teleostei: Synbranchidae): how many species?

Os cromossomos e a variação de conteúdo de DNA nuclear foram estudados em sete amostras de Synbranchus marmoratus das bacias dos rios Paraguai e Paraná com o objetivo de avaliar se diferenças no cariótipo e no conteúdo de DNA nuclear poderiam fornecer informações para a caracterização de linhagens evolutivas independentes no gênero e para a elaboração de hipóteses evolutivas e biogeográficas. A ocorrência de diferentes cariótipos já foi descrita para essa espécie, entretanto, um novo citótipo foi encontrado no rio Miranda. O conteúdo de DNA nuclear mostrou uma ampla variação entre as amostras e indivíduos, com valores entre 5,2 a 9,1 pg de DNA/núcleo. Uma análise de variância confirmou a ocorrência de diferenças significativas entre as amostras. em uma série de análises, um padrão multimodal foi encontrado na distribuição do conteúdo de DNA nuclear, pelo qual várias unidades, mais ou menos discretas, foram identificadas. Combinando a fórmula cariotípica com o conteúdo de DNA nuclear, uma relação complexa entre os rios foi observada. Com base nos dados disponíveis, sugerimos que existem várias linhagens evolutivas independentes de Synbranchus marmoratus nos rios amostrados. Hipóteses biogeográficas são propostas e discutidas.

Fugitive species in a harlequin environment: Ants (Hymenoptera : Formicidae) and banana baits in the Amazon

A total of 9 ant species were sampled from four sites covering 2000 km in the Amazon Basin using banana fruit baits: two sites on the Jurua River, one site on the Xingu River and in a dry forest of eastern Amazon, Paragominas. Camponotus abdominalis was present in all sites, and Camponotus sericeiventris, Camponotus sp. and Crematogaster sp. were present in two sites. All other species were present in only one site. Paragominas had the highest species richness because of a higher number of site restricted species. However, Jaccard faunas similarities among sites were not significantly related with distance between sites. Mosaic diversity showed a relatively simple taxonomic composition. The strong differences of the fauna sampled at banana fruit baits from other reported Neotropical ant faunas suggests that the fauna represents widespread fugitive species in an apparently complex environment.