79 resultados para Development in PNG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Tendo por base os novos conhecimentos oriundos de recentes estudos com Perciformes marinho, a origem e o desenvolvimento dos oócitos no Ostariophysi Gymnotus sylvius são aqui descritos. da mesma maneira que ocorre nos Perciformes, em Gymnotus sylvius as oogônias são encontradas no epitélio germinativo que margeia as lamelas ovígeras. No início da foliculogênese, a proliferação das oogônias e sua entrada em meiose dão origem a ninhos de células germinativas que se projetam em direção ao estroma ovariano, a partir do epitélio germinativo. Os ninhos e o epitélio germinativo são suportados pela mesma membrana basal que os separa do estroma. Coincidindo com a paralisação da meiose os oócitos, presentes nos ninhos, são separados uns dos outros por processos citoplasmáticos das células pré-foliculares. As células pré-foliculares derivam do epitélio germinativo sendo, portanto, inicialmente células epiteliais. Durante a foliculogênese, ao mesmo tempo em que envolvem os oócitos individualizando-os, as células pré-foliculares sintetizam a membrana basal ao seu redor. Os oócitos entram em crescimento primário ainda dentro dos ninhos. Ao término da foliculogênese, o oócito e as células foliculares que compõem o folículo são circundados pela membrana basal. O folículo permanece conectado ao epitélio germinativo uma vez que ambos compartilham uma porção comum da membrana basal. Células oriundas do estroma circundam o folículo ovariano exceto na região de compartilhamento da membrana basal formando a teca. O folículo, a membrana basal e a teca formam o complexo folicular. O desenvolvimento do oócito ocorre dentro do complexo folicular e compreende os estágios de crescimento primário e secundário, maturação e ovulação. Os alvéolos corticais surgem no ooplasma momentos antes do início do crescimento secundário ou estágio vitelogênico que tem início com a deposição de vitelo, progride até o oócito esteja completamente desenvolvido e o ooplasma preenchido pelos glóbulos de vitelo. A maturação é caracterizada pela migração do núcleo ou vesícula germinativa, pela quebra da vesícula germinativa, ou seja, pela fragmentação do envoltório nuclear e, retomada da meiose. Na ovulação o ovo é liberado do complexo folicular para o lúmen ovariano. em comparação com os Perciformes marinhos com ovos pelágicos, o desenvolvimento oocitário em Gymnotus sylvius tem menos etapas dentro dos estágios de desenvolvimento, sendo as duas mais notáveis delas as ausências da formação das gotas de lipídio durante os crescimentos primário e secundário (e a consequente fusão das gotas para formar um único glóbulo de lipídio durante a maturação) e, a hidrólise do vitelo antecedendo a ovulação.
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Exposure of 1, 4, 7 & 10 day-old virgin queens of Apis mellifera Linne 1758 for 1 min to CO2 accelerated their ovarian development, having a similar effect as mating on the initial formation of the ovarian follicles. In 3 day-old queens the exposure to CO2 enhanced the initial stage of germ cell differentiation into oocytes and nurse cells in the ovarioles, a developmental stage only seen in 5 day-old untreated virgin queens, the age at which they are ready to mate. In 10 day-old untreated virgin queens, some regions of the ovarioles presented tissue disorganization and many cells with pycnotic nuclei. However, narcotized virgin queens of the same age did not present such ovary degeneration. Conversely, they showed nitid follicle formation, arising in the ovarioles' initial differentiation between nurse and oocytic chambers, although still without vitellogenesis. The accelerative effect of CO2 is limited to the ages near to those proper for mating, since 15 and 18 day-old treated virgin queens presented ovaries with extensive regions of high tissue disorganization and a great number of cells with pycnotic nuclei. According to the results, the narcosis presented three levels of effect on the ovary of honeybee virgin queens: 1) accelerated the germ cell differentiation, 2) preserved the tissue integrity even after the queen mating period and 3) stimulated the initial differentiation of a vitellarium. This later condition was only seen in untreated queens after mating. All these effects are not maintained if the queen is kept virgin beyond 15 days old.
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A biometric study of caste development was carried out using Nasutitermes sp., by measuring the height, width, and length of the head, the length and width of the pronotum and mesonotum, and the length of the posterior tibia. These measurements were taken on 200 individuals, including larvae, nymphs, workers, pre-soldiers and soldiers. For instar separation, it was verified that the Principal Component Analysis (P.C.A.) was the most efficient methodology. Results of this analysis showed that Nasutitermes coxipoensis follows the general pattern of development presented by other Nasutitermes.
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Caste determination in Trigona spinipes Fabricius (Hymenoptera, Apidae, Meliponini) is trophogenic. Larvae that eat about 360 mu l of food become queens, while those who consume 36 mu l develop into workers. We studied the effect of larval nutrition on the number and length of ovarioles and on ovarian development in fifth instar larvae, white eyed, pink eyed and black-eyed pupae as well as newly emerged adults. All larvae have four ovarioles per ovary, while in queen pupae this number ranged from 8 to 15. Cyst formation, the cell death and other characteristics of ovary morphogenesis were the same regardless of the quantity of food consumed. These results are discussed in relation to caste differentiation in other bees.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Bromeliaceae possess several features of pollen and anther wall development that are plesiomorphic for Poales, consistent with their putatively basal or near-basal placement in this order. For example, successive microsporogenesis and the monocotyledonous type of anther wall formation are both plesiomorphic features that occur commonly in other Poales, with a few notable exceptions, notably the simultaneous type of microsporogenesis in Rapateaceae. The intermediate type of tapetum development in Bromeliaceae was probably derived secondarily from a secretory type, which occurs in most other Poales except Typhaceae.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The Malpighian tubules of Aedes aegypti showed significant differences in their diameters between male and female larvae, male and female pupae, male larvae and male adults and male pupae and male adults. in every case, female values were greater than in males. Measurements of mean nuclear areas of the principal and stellate cells from Malpighian tubules, taken in males and females during development, showed that this parameter in both types of cell was significantly greater in females than in male larvae, pupae and adult stages. In males, significant differences between developmental stages were observed only in comparison with the nuclear area of larvae and adults in the principal cells, but in females, every comparison between stages showed significant differences except between pupae and adults in stellate cells. The frequency distribution of nuclear area values, in development, for male stellate and principal cells, were mostly concentrated in the first seven classes among the 30 classes considered in every stage, while for females, the frequency dropped drastically in the same classes from larvae to pupae and adults, moving to classes of higher values. Considering the importance of Malpighian tubules in insect physiology, the meaning of the differences detected are discussed on the basis of different metabolic levels, between sexes and developmental stages.
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Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the brain and spinal cord that is mediated by CD4+ T lymphocytes specific to myelin components. In this study we compared development of EAE in Lewis rats from two colonies, one kept in pathogen-free conditions (CEMIB colony) and the other (Botucatu colony) kept in a conventional animal facility. Female Lewis rats were immunized with 100 µl of an emulsion containing 50 µg of myelin, associated with incomplete Freund's adjuvant plus Mycobacterium butyricum. Animals were daily evaluated for clinical score and weight. CEMIB colony presented high EAE incidence with clinical scores that varied from three to four along with significant weight losses. A variable disease incidence was observed in the Botucatu colony with clinical scores not higher than one and no weight loss. Immunological and histopathological characteristics were also compared after 20 days of immunization. Significant amounts of IFN-gamma, TNF-alpha and IL-10 were induced by myelin in cultures from CEMIB animals but not from the Botucatu colony. Significantly higher levels of anti-myelin IgG1 were detected in the CEMIB colony. Clear histopathological differences were also found. Cervical spinal cord sections from CEMIB animals showed typical perivascular inflammatory foci whereas samples from the Botucatu colony showed a scanty inflammatory infiltration. Helminths were found in animals from Botucatu colony but not, as expected, in the CEMIB pathogen-free animals. As the animals maintained in a conventional animal facility developed a very discrete clinical, and histopathological EAE in comparison to the rats kept in pathogen-free conditions, we believe that environmental factors such as intestinal parasites could underlie this resistance to EAE development, supporting the applicability of the hygiene hypothesis to EAE.
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Os parasitas do gênero Schistosoma situam-se entre os primeiros metazoários que desenvolveram sexos separados, determinado cromossomicamente no ovo fertilizado. Apesar da ocorrência de cromossomos sexuais específicos, as fêmeas de Schistosoma não atingem a maturidade somática e sexual sem a presença dos machos. Na verdade, um dos aspectos mais controversos e, ao mesmo tempo, mais fascinantes, envolvendo o desenvolvimento sexual das fêmeas está em se desvendar a natureza do estímulo que controla e mantém tal processo. Muito embora a natureza do estímulo (físico ou químico) seja motivo de controvérsia, concordam os mais diferentes autores que o acasalamento é um requisito indispensável para que ocorra a maturação e migração das fêmeas para o sítio definitivo de permanência no sistema vascular do hospedeiro vertebrado. Admite-se, ainda, que o estímulo não é espécie-específico e, em alguns casos, nem mesmo gênero-específico. Não obstante a existência de um número considerável de artigos dedicados ao tema, não há um consenso sobre o processo (ou processos) que controla(m) o encontro de machos e fêmeas no sistema circulatório do hospedeiro vertebrado, bem como está por ser determinada a natureza do estímulo, oriundo dos machos, que controla e mantém o desenvolvimento somático e sexual das fêmeas. Ao longo dos anos os machos de Schistosoma têm sido considerados, por vezes pejorativamente, os irmãos, os músculos ou o fígado das fêmeas. em síntese, resta saber se a natureza do estímulo responsável pelo desenvolvimento das fêmas envolve a transferência de hormônios, nutrientes, a mera estimulação tátil ou a combinação de dois ou mais desses fatores
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)