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Search Results: 1 - 10 of 20414 matches for " Fosca Pedini Pereira Leit "
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Sperm ultrastructure of Mytella (Bivalvia) populations from distinct habitats along the northern coast of S?o Paulo State, Brazil
Orlandi Introíni,Gisele; Martins Maester,Fernanda; Pedini Pereira Leit,Fosca; Recco-Pimentel,Shirlei Maria;
Biocell , 2010,
Abstract: ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. in the present work, spermatozoa of mussel specimens of the genus mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. the objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate mytella species. the specimens were from populations that live in intertidal zones on the southeast coast of brazil, either buried in muddy-sand sediment or anchored to rocky substrates. the acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. the sperm was of a primitive type. the spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. the data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as m. charruana. the presence of an axial rod in their sperm cells supports the inclusion of m. charruana in the subfamily mytilinae.
Sperm ultrastructure of Mytella (Bivalvia) populations from distinct habitats along the northern coast of S o Paulo State, Brazil
Gisele Orlandi Introíni,Fernanda Martins Maester,Fosca Pedini Pereira Leit,Shirlei Maria Recco-Pimentel
Biocell , 2010,
Abstract: Ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. In the present work, spermatozoa of mussel specimens of the genus Mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. The objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate Mytella species. The specimens were from populations that live in intertidal zones on the southeast coast of Brazil, either buried in muddy-sand sediment or anchored to rocky substrates. The acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. The sperm was of a primitive type. The spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. The data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as M. charruana. The presence of an axial rod in their sperm cells supports the inclusion of M. charruana in the subfamily Mytilinae.
Life Cycle Observations on Amphilocus neapolitanus (Della Valle, 1853) (Crustacea, Amphipoda) Associated with Sargassum cymosum C. Agardh, 1820 in Ubatuba, (SP), Brazil
Leite, Fosca Pedini Pereira;
Brazilian Archives of Biology and Technology , 2002, DOI: 10.1590/S1516-89132002000300014
Abstract: day and night densities, reproductive biology and life cycle of amphilocus neapolitanus (della valle, 1853), associated with sargassum cymosum c. agardh, 1820, were studied during 13 months. the density of juveniles, males and females was higher in night samples than in day samples. sex ratio was strongly favorable toward the females. ovigerous females were present in similar densities in both the periods while the non-ovigerous females were predominant at night. the egg number was not correlated with the size of the females. breeding occurred throughout the year.
Crescimento e reprodu??o de Hyale media Dana (Amphipoda, Gammaridae, Hyalidae) associada à Sargassum cymosum C. Agardh
Leite, Fosca Pedini Pereira;
Revista Brasileira de Zoologia , 1996, DOI: 10.1590/S0101-81751996000300008
Abstract: the post-marsupial growth, sexual differentiation, fecundity and reproductive biology of hyale media dana, 1853 living on sargassum cymosum c. agardh, 1820 are described. the growth was continuous througth 12 stages for males and 9 for females. the sexual differentiation occours at 2th or 3th moult and was demonstrated by the enlargment of the gnatopod ii propod. number of eggs increased with the female head length. observations of courtship behavior, incubation, moult processes, emergence of juveniles and brood caracteristics were made. the precopula courtship continued for two days, the eggs were incubated for six days and the juveniles, that stay until three days in the marsupium, moult every day.
Life Cycle Observations on Amphilocus neapolitanus (Della Valle, 1853) (Crustacea, Amphipoda) Associated with Sargassum cymosum C. Agardh, 1820 in Ubatuba, (SP), Brazil
Leite Fosca Pedini Pereira
Brazilian Archives of Biology and Technology , 2002,
Abstract: Day and night densities, reproductive biology and life cycle of Amphilocus neapolitanus (Della Valle, 1853), associated with Sargassum cymosum C. Agardh, 1820, were studied during 13 months. The density of juveniles, males and females was higher in night samples than in day samples. Sex ratio was strongly favorable toward the females. Ovigerous females were present in similar densities in both the periods while the non-ovigerous females were predominant at night. The egg number was not correlated with the size of the females. Breeding occurred throughout the year.
Temporal variation in Sargassum Biomass, Hypnea epiphytism and associated fauna
Leite, Fosca Pedini Pereira;Turra, Alexander;
Brazilian Archives of Biology and Technology , 2003, DOI: 10.1590/S1516-89132003000400021
Abstract: studies were carried out to investigate the temporal variation in sargassum biomass, hypnea epiphytism and associated fauna. there was a marked variation in the biomass of sargassum and hypnea among various sampling periods. low values for sargassum were recorded in august and november, while the lower value for hypnea biomass was recorded in august. an inverse relationship was found between sargassum biomass and the intensity of hypnea epiphytism. the density of the total fauna associated to sargassum showed a marked reduction in may. this variation was influenced by the variation patterns of the dominant faunistic groups (gastropoda, gammaridea, isopoda and caridea). significant positive relationships were found between the biomass of sargassum and sargassum+hypnea with the total density of all faunistic groups (per macroalgae biomass unit). however, the influence of hypnea epiphytism on the phytal organisms was not evidenced.
Distribui??o vertical e flutua??o sazonal da macrofauna vágil associada a Sargassum cymosum C. Agardh, na praia do Lázaro, Ubatuba, S?o Paulo, Brasil
Jacobucci, Giuliano Buzá;Leite, Fosca Pedini Pereira;
Revista Brasileira de Zoologia , 2002, DOI: 10.1590/S0101-81752002000500004
Abstract: seasonal fluctuations and depth distribution of the vagile macrofauna associated with sargassum cymosum at lazaro beach, ubatuba, s?o paulo state, were evaluated through density comparison of higher taxonomic groups among three depth intervals in four periods of the year. ten groups were identified and among them gammarid and caprellid amphipods were numerically dominant in all sampling periods and did not show any consistent zonation trend. gastropods, polychaetes and ophiuroids ocurred in lower densities and tended to dominate as depth increased, wet weight algae variation did not explain the observed spatial and temporal patterns. biotic interactions, recruitment and environmental parameters are probably involved in seasonal density variation of the faunal groups studied but it was evident that the depth gradient play an important role in vagile macrofauna vertical distribution.
Embryonic development and duration of incubation period of tropical intertidal hermit crabs (Decapoda, Anomura)
Turra, Alexander;Leite, Fosca Pedini Pereira;
Revista Brasileira de Zoologia , 2007, DOI: 10.1590/S0101-81752007000300020
Abstract: the description of the embryonic development of the hermit crabs clibanarius antillensis stimpson, 1859, c. sclopetarius (herbst, 1796), c. vittatus (bosc, 1802), and pagurus criniticornis (dana, 1852) and preliminary observations on the development of pagurus brevidactylus (stimpson, 1858) and paguristes tortugae schmitt, 1933 were done. the analysis of the external morphology of the embryos of the studied species allowed the identification of seven stages: stage 1, zygote and cleavage; stage 2, homogeneous mass (advanced cleavage and gastrulation); stage 3, initiation of the germinal disc (yolk-free area); stage 4, percentage of yolk-free area from 5% to 50-70%; stage 5, eye pigmentation (comma-shape) and heart beating; stage 6, percentage of yolk-free area from 70-80% to 95%) and eye development to a darkened irregularly-rounded shape; stage 7, zoea visible and hatching. despite all stages were recorded in all species, interespecific differences were recorded in relation to zygote size and embryo color; cleavage, absolute and relative developmental time, and moment eye pigmentation appeared. such morphological differences may be associated to variations in the yolk amount and composition and reveal different reproductive strategies at least between p. criniticornis and all studied species of clibanarius.
Temporal variation in Sargassum Biomass, Hypnea epiphytism and associated fauna
Leite Fosca Pedini Pereira,Turra Alexander
Brazilian Archives of Biology and Technology , 2003,
Abstract: Studies were carried out to investigate the temporal variation in Sargassum biomass, Hypnea epiphytism and associated fauna. There was a marked variation in the biomass of Sargassum and Hypnea among various sampling periods. Low values for Sargassum were recorded in August and November, while the lower value for Hypnea biomass was recorded in August. An inverse relationship was found between Sargassum biomass and the intensity of Hypnea epiphytism. The density of the total fauna associated to Sargassum showed a marked reduction in May. This variation was influenced by the variation patterns of the dominant faunistic groups (Gastropoda, Gammaridea, Isopoda and Caridea). Significant positive relationships were found between the biomass of Sargassum and Sargassum+Hypnea with the total density of all faunistic groups (per macroalgae biomass unit). However, the influence of Hypnea epiphytism on the phytal organisms was not evidenced.
Desenvolvimento morfológico e dos ovários de Kalliapseudes schubarti Ma?e-Garzon (Crustacea, Tanaidacea) do Canal de S?o Sebasti?o, S?o Paulo, Brasil
Leite, Fosca Pedini Pereira;Leite, Paulo Eduardo Pereira;
Revista Brasileira de Zoologia , 1997, DOI: 10.1590/S0101-81751997000300016
Abstract: the morphological stages of the kalliapseudes schubarti ma?e-garzon, 1949 females were easily determinated and they were similar, but the male stages show distint forms probably due to the ambient stimuli. the description of the male stages demonstrate that k. gianucai (bacescu, 1979) is another male stage of k. schubarti, probably a secondary copulatory stage. the morphology and development of the ovary is related both with the maturity and with the morphological modifications of females stages.
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