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A criação do devir: ética e ontogênese na filosofia de Gilbert Simondon / The creation of becoming: ethics and ontogenesis in the philosophy of Gilbert SimondonLucas Paolo Sanches Vilalta 08 December 2017 (has links)
O presente trabalho é uma leitura da relação entre a ontogênese e a ética na filosofia de Gilbert Simondon. Pretende-se mostrar como há uma relação de analogia e imbricação entre ética e ontogênese no pensamento do autor, estas correlações nos permitem apresentar a filosofia simondoniana como uma teoria metaestável que se constitui como permanentemente aberta às novas problemáticas do ser e ao devir do devir. Esta teoria, simultaneamente, ética e ontogenética é excedida em seus modos de captação dos processos de individuação por suas relações com a informação e com a dimensão pré-individual do ser. Apresentamos, em um segundo momento, como a ontogênese simondoniana nos permite pensar uma ética existente nas processualidades de todos os seres, do cristal aos seres humanos, das moléculas aos animais, e também dos objetos técnicos. Por fim, mostramos como Simondon constrói uma concepção singular de sujeito como ação autoproblematizante do ser que faz com que o indivíduo seja, ao mesmo tempo, mais-que-unidade e mais-que-identidade em relação a si mesmo. O sujeito simondoniano é capaz de captar a ética como sentido da ontogênese e agir politicamente apostando todos os possíveis em experiências de transformação de si. O sujeito, ao conjugar em si as dimensões pré-individual, individual e transindividual do ser, possui um devir que é, simultaneamente, individual e coletivo. Com estes desenvolvimentos, pretendemos apresentar como a filosofia de Simondon nos oferece contribuições muitos relevantes para pensarmos possíveis transformações espirituais e políticas para os modos de vida em nossa contemporaneidade. / This work aims to be an analysis of the relationship between ethics and ontogenesis in the Gilbert Simondons philosophy. It intends to show that there is an analogycal and inseparable relation between ethics and ontogenesis in his thought. These correlations allow us to show the Simondons philosophy as a metastable theory which creates itself as permanently open to new problematics of the being and to the becoming of becoming. This theory, at the same time, ethical and ontogenetical is always overpassed, in its means of apprehension of the individuation processes, by its relations with information and with the pré-individual dimension of the being. Secondly, we sustain that Simondons ontogenesis allow us to think about an ethics which exists in the being processuality, from crystal to human beings, from molecules to animals, and also in the technical objects processuality. Finally, we show that Simondon constructs a single notion of subject as selfproblematic action of the being that implicates an individual more-than-unity and, simultaneously, more-than-indentity regarding itself. The simondonean subject is able to apprehend ethics as the meaning of the ontogenesis and to act politically risking all the possibles to transform itself. The pre-individual, individual and transindividual dimensions of the being produce an becoming to the subject, which is both individual and collective. According to these arguments, we intend to conclude that the Simondons philosophy gives us very important contributions to think some spiritual and political changes in our contemporary way of life.
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Ontogenetic and Gender Dimensions in a Normative Study of the Dreams of CanadiansDale, Allyson January 2017 (has links)
The current dissertation examined gender, cultural, and ontogenetic dimensions in the dreams of Canadians. Normative studies in the United States, Europe, and other countries have documented normative data including gender differences and compared their findings to American data to investigate cultural differences. The purpose of the present study was to extend research of this nature by establishing normative data for Canadians. Furthermore, age differences in dreams have been mostly investigated for females, with only a few studies with males, and have used a variety of methodologies and age ranges. Another objective of this study was to document, for the first time, the ontogenetic pattern of the main dream content categories from adolescence to old age for males and females. The rigorous and detailed dream diary method was used to collect dreams which were analyzed using the Hall and Van de Castle method of content analysis.
The first paper consisted of two dreams each from 150 male and female young adult Canadians, ages 18-24, totaling 600 dream reports. Findings provided support for the threat simulation theory as there were more negative than positive themes overall. Furthermore, dream gender differences were consistent with those in waking and the similarity of Canadian and American culture was reflected in dream imagery, supporting the continuity hypothesis of dream formation.
The final two papers examined the ontogenetic patterns of dream content for females and males respectively. The second paper consisted of 75 females across 5 age groups from adolescence to old age (12-17, 18-24, 25-39, 40-64, and 65-85) and the third paper consisted of 50 males across the same age groups with the exception of 31 males in the oldest group (65-85). The ontogenetic patterns of dream content from adolescence to old age reflected waking developmental patterns as proposed by social theories, neurobiological research, and recognized features of aging, supporting the continuity hypothesis.
In terms of the theoretical implications, this work provides support for the hypothesis of the threat simulation theory pertaining to the prevalence of negative content in dreams. It also provides support for the continuity between waking and dreaming hypothesis of dream formation. Implications of these findings regarding our understanding of the sources of dream formation are described. Finally, limitations and future directions, for research examining the evolution of gender differences across the lifespan, are discussed.
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A Modular Gene Regulation Network Model of Artificial OntogenesisGHANEM, AMER 18 April 2008 (has links)
No description available.
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A representação social da teoria de Piaget no Brasil: implicações para as pesquisas acadêmicas / The social representation of Piaget\'s theory in Brazil: implications to the academic researchesMarçal, Vicente Eduardo Ribeiro 07 June 2019 (has links)
O objetivo desta Tese foi o de demonstrar que a Teoria do biólogo e epistemólogo suíço Jean Piaget foi vítima de sua própria Representação Social, (na acepção de Serge Moscovici, como explicitaremos já em nossa Introdução). Vítima no sentido de que suas descobertas na área da Biologia e sua criação no campo da construção de modelos formais na mesma ciência, feito inédito até então, caíram no ostracismo na História da ontogênese epigenética do ser humano, tanto nos aspectos biológicos, quanto na área da aquisição do conhecimento científico e lógico matemático. Esses fatos nos mostram Zelia Ramozzi-Chiarottino, (cuja análise e interpretação da Teoria de Jean Piaget constituir-se-á no referencial teórico desta Tese) ao lado de seus colaboradores, no artigo: Jean Piagets unrecognized epigenetic ontogenesis of the logical mathematical thought, (2017). Neste trabalho, restringimo-nos ao Brasil e à produção de Dissertações e Teses de Doutorado sobre a Teoria de Piaget e sua representação social, aqui realizadas nos últimos dez anos. Fizemos um levantamento das Dissertações e Teses a partir do Catálogo de Teses e Dissertações da CAPES. O método estatístico que utilizamos foi o do para analisar os dados coletados. Esta análise confirmou nossa conjectura / Our aim with this Ph.D Thesis was to demonstrate that the Theory of the swiss biologist and epistemologist Jean Piaget was victim of its own Social Representation (within the meaning of Serge Moscovici, as we will still explain in our Introduction). Victim in sense of that his findings in the field of Biology and his creation in the field of the construction of formal models in this same Science, unprecedent feat till then, have fallen in obscurity in the History of epigenetic ontogenesis of the human being, in both biologic and scientific aspects, in terms of the field of acquiring of scientific and logical mathematical knowledgement. These facts Zelia Ramozzi-Chiarottino (whose analysis and interpretation of Piagets Theory will be the theoretical framework of this Thesis) show us next to her co-workers, in the article: Jean Piagets unrecognized epigenetic ontogenesis of the logical mathematical thought, (2017). In the present work, we limited ourselves to Brazil, and to the production of Dissertations and Doctoral Theses on Piagets Theory and its Social Representation, produced here on the last ten years. We made a data survey on the Dissertations and Theses from the Catalogue of Theses and Dissertations from CAPES. Statistic method used was the to analyze the collected data. This analysis validated our conjecture
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Desenvolvimento foliar em Ruschioideae (Aizoaceae), com ênfase na formação e estrutura dos feixes vasculares periféricos / Leaf development in Ruschioideae (Aizoaceae), with emphasis in the formation and structure of peripheral vascular bundlesNunes, Aline Siqueira 22 August 2013 (has links)
Popularmente conhecidas como flowering stones ou ice plants, as plantas da família Aizoaceae (Caryophyllales) caracterizam-se por suas folhas suculentas morfologicamente diversas. Com centro de origem no sul da África, a maior parte das espécies pertence a subfamília Ruschioidaeae, com plantas de folhas dorsiventrais, cilíndricas e trígonas, sendo marcante a ocorrência de conação entre as bases de folhas opostas, e a presença de feixes vasculares periféricos, com xilema endoscópico. Nosso estudo mostra que a formação dos feixes vasculares periféricos é posterior ao estabelecimento da blastozona marginal, e que tecidos da face abaxial diferenciam-se no domínio adaxial da folha durante a histogênese da lâmina. Sugerimos que um mecanismo de abaxialização foliar esteja vinculado à formação da margem foliar de Aizoaceae. O xilema dos feixes vasculares periféricos é formado wide band tracheids - \"wbts\", um tipo especializado de elemento traqueal com acentuado espessamento da parede secundária. \"Wbts\" vinculam-se a órgãos suculentos e ocorrem somente em Aizoaceae, Anacampserotaceae e Cactaceae, tendo despertado interesse dos pesquisadores quanto à sua origem e função. A partir de análises comparativas de anatomia, ultraestrutura e de imunomarcação de pectina, concluímos que a definição de \"wbts\" deve ser mantida nas famílias, no entanto, destacamos a possível ocorrência de idioblastos traqueoidais na região de medular de algumas espécies. Este trabalho contribui no conhecimento da anatomia e ontogênese foliar de Aizoaceae, abrindo oportunidades de estudos sobre os mecanismos envolvidos no estabelecimento da dorsiventralidade em folhas de simetria radial. A análise comparativa de wide-band tracheids \"wbts\" em Aizoaceae, Anacampserotaceae e Cactaceae traz contribuições ao conhecimento sobre sua distribuição e características nos diferentes órgãos / Popularly known as flowering stones or ice plants, the species of Aizoaceae (Caryophyllales) are characterized by morphologically diverse succulent leaves. With center of origin in Southern Africa, most species are classified in the subfamily Ruschioidaeae, which present dorsiventral, cylindrical and three-angled leaved plants, being remarkable the occurrence of conation between the bases of opposite leaves, and the presence of peripheral vascular bundles with endoscopyc xylem. Our study shows that the formation of peripheral vascular bundles occurs after the marginal blastozone establishment, and abaxial tissues differentiate in the adaxial domain of the leaf, during blade histogenesis. We suggest that an abaxialization mechanism is involved in the formation of leaf margins in Aizoaceae. The xylem of peripheral vascular bundles is composed by wide band tracheids - wbts, a specialized type of cell that occurs only in Aizoaceae, Cactaceae Anacampserotaceae. The origin and function of this cell type has been the subject of study by some researchers. By means of comparative analysis of anatomy, ultrastructure and pectin immunolabeling, we conclude that the definition of \"wbts\" should be kept in the three families; however, we highlight the possibility of idioblasts tracheids in the some cases. This work contributes to the knowledge of leaf anatomy and ontogenesis in Aizoaceae, opening opportunities for studies on the mechanisms involved in the establishment of dorsiventrality in leaves with radial symmetry. A comparative analysis of wbts in Aizoaceae, Cactaceae Anacampserotaceae brings contributions to knowledge about their distribution and characteristics in different organs
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Crescimento e desenvolvimento de Physalis ixocarpa Brot. ex Hormen em diferentes condi??es de luminosidadeSilva, Natalina Souza 29 July 2016 (has links)
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Previous issue date: 2016-07-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The tomatillo center of origin is in Mexico, being the fifth most produced vegetable in the country mainly used in the preparation of traditional Mexican cultural dishes. The principal means of spreading species from the genus Physalis are seeds. Physalis is considered easy to grow because of the quantity of seeds the genus produces, and its high rates of germination. This study aimed to characterize the developmental cycle and compare the growth of tomatillo 'purple' in two light conditions. For this purpose, P. ixocarpa 'purple' was grown in PVC pots with four replications of 10 samples for each treatment, a total of 40 plants per treatment. Evaluation of the seedling emergence was held in a range of 7, 14 and 21 days after sowing. The analysis of other phenophases started up to 26 days after sowing, was maintained throughout the cycle, and held in 14 days intervals. The estimated physiological parameters are the content of chlorophyll a and b, and leaf carotenoids. The plasticity of the species in the study was assessed using growth analysis with the variables height, stem diameter, number of leaves, buds, flowers and fruits, and dry weight of plant growth. Analysis was performed with the variables height, stem diameter, number of leaves, buds, flowers, fruits, dry mass of plants and leaf anatomy. The means of the data were assessed using analysis of variance (ANOVA) and the student T-Test with a 5% significance level. In this study the parameters that were influenced by light were the emergence rate of seedlings, the content of photosynthetic pigments, leaf thickness, period required for the establishment of phenophases, dry weight, fruit production and seed vigor. Although the plants grown in direct sunlight have higher rates of growth, greater production of fruits and viable seeds were obtained in plants grown under shade. / O centro de origem de Physalis ixocarpa ? o M?xico, sendo a quinta hort?cola mais produzida no pa?s, usada principalmente na prepara??o de pratos tradicionais da cultura mexicana. A principal forma de propaga??o de esp?cies do g?nero Physalis ? a partir de sementes, sendo considerada de f?cil cultivo pela quantidade de sementes produzidas e pelas altas taxas de germinabilidade. O presente trabalho teve como objetivo caracterizar o ciclo de desenvolvimento e comparar o crescimento de Physalis ixocarpa Brot. ex Hormen bem como analisar os pigmentos cloroplast?dicos, anatomia foliar e germina??o de sementes oriundos dos frutos produzidos sob duas condi??es de luminosidade. Para tanto, realizou-se o cultivo de P. ixocarpa ?roxa? em vasos de PVC, sendo 4 repeti??es de 10 amostras para cada tratamento, perfazendo um total de 40 plantas por tratamento. As avalia??es de emerg?ncia de pl?ntulas foram realizadas em num intervalo de 7 dias ap?s a semeadura finalizando aos 21, as an?lises das demais fenofases iniciaram-se aos 26 dias ap?s a semeadura sendo mantida por todo ciclo e realizada em intervalo14 dias. O par?metro fisiol?gico avaliado foi o teor de clorofila a e b e caroten?ide de folhas expandidas. A aclimata??o da esp?cie em estudo foi avaliada atrav?s da an?lise de crescimento com as vari?veis: altura, di?metro do colo, n?mero de folhas, bot?es florais, flores e frutos e massa seca das plantas. Foi realizada an?lise de crescimento com as vari?veis: altura, di?metro do colo, n?mero de folhas, bot?es florais, flores, frutos, massa seca das plantas e a anatomia foliar. Os dados foram submetidos ao teste de m?dias com an?lise de vari?ncia seguida pelo Teste T-Student a 5% de signific?ncia. Nesse estudo os par?metros que mostraram-se influenciados pela luminosidade foram a taxa de emerg?ncia de pl?ntulas, os teores de pigmentos fotossint?ticos, espessura do limbo foliar, per?odo necess?rio para o estabelecimento das fenofases, massa seca, produ??o de frutos e vigor das sementes. Apesar das plantas cultivadas a pleno sol apresentarem maiores ?ndices de crescimento, a maior produ??o de frutos e sementes vi?veis foram obtidas em plantas cultivadas em ambiente sombreado.
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Ontogênese da região da axila foliar e filogenia molecular de Didiereaceae: a história de um caráter e suas implicações filogenéticas em Portulacineae / Axillary bud ontogenesis and molecular phylogeny of Didiereaceae: a character history and its phylogenetic implications in PortulacineaeOliveira Neto, Mario Albino de 29 April 2014 (has links)
Recentes análises filogenéticas, baseadas em dados moleculares, indicaram que Didiereaceae s.s. é filogeneticamente relacionada a gêneros tradicionalmente pertencentes à Portulacaceae s.l.. Sendo incluídos os gêneros Ceraria, Portulacaria e Calyptrotheca em Didiereaceae e essa dividida em três subfamílias: Didieroideae (11 espécies), Portulacarioideae (7 espécies) e Calyptrothecoideae (1espécie). Análises moleculares apresentaram alto suporte para o monofiletismo da família e circunscrição das três subfamílias, contudo, nenhuma dessas análises elucidou completamente as relações entre os gêneros. Com a expansão de sua circunscrição, a família se tornou mais heterogênea, surgindo assim, a necessidade da investigação de características para o estabelecimento de sinapomorfias ou para corroborar suas relações dentro de Portulacineae. Diante disso, o presente trabalho realizou análises de Inferência Bayesiana e Máxima Parcimônia para sete sequências diferentes do DNA do cloroplasto, trnA-trnB, trnL-trnF, trnT-trnL, trnS-trnG, trnQUUG-rps16, rps16 e rpl16, para todas as 19 espécies de Didiereaceae e investigou a ontogênese foliar e da região de sua axila para Didieroideae e Portulacarioideae. Os resultados das análises filogenéticas corroboraram o monofiletismo da família e de suas três subfamílias, além de elucidar as relações internas em Didieroideae e Portulacarioideae. Os dois gêneros de Portulacarioideae, Portulacaria e Ceraria, não são monofiléticos e as espécies de Ceraria foram transferidas para Portulacaria. Também foi caracterizado o desenvolvimento dos diferentes padrões de variações morfológicas da folha e das folhas modificadas em espinhos e profilos. A partir dos resultados do desenvolvimento e da filogenia molecular, foi feita uma análise de reconstrução da região da axila foliar para o ancestral de Didiereaceae, que indicou a presença de braquiblastos portadores de profilos na axila foliar do ancestral comum. Como consequência, foram estabelecidas homologias entre esses profilos e os profilos de Talinaceae e espinhos de Cactaceae / Recent phylogenetic analysis, based on molecular data, indicated that Didiereaceae s.s. is phylogenetic related to former Portulacaceae s.l. genera. The genera Ceraria, Portulacaria and Calyptrotheca were included in Didiereaceae and the family was divided in three subfamilies: Didieroideae (11 species), Portulacarioideae (7 species) and Calyptrothecoideae (1specie). Molecular analyses presented high statistical support to the monophyletism of the Didiereaceae and its division in three subfamilies, however, none of these analyses elucidated the relations among genera. With the expansion of its circumscription, the family became rather heterogenic, resulting in the need to investigate characteristics to the establishment of synapomorphies to the family or corroborate its relations inside Portulacineae. Therefore, we performed Bayesian Inference and Maximum Parsimony analyses for seven different chloroplast DNA regions, trnA-trnB, trnL-trnF, trnT-trnL, trnS-trnG, trnQUUG-rps16, rps16 and rpl16, for all 19 species of Didiereaceae and investigated the leaf and leaf axil region ontogenesis for Didieroideae and Portulacarioideae. Our analyses corroborated the monophyly of the Didiereaceae and of its three subfamilies and elucidated internal relationships between the Didieroideae and the Portulacarioideae. The two genera of the Portulacarioideae, Portulacaria and Ceraria, are not monophyletic and the 5 accepted species for Ceraria are transferred to Portulacaria. Also, the ontogenesis for different morphological patterns of leaf and spines and prophyll were characterized. Based on the ontogenetical results and the molecular phylogeny, was made the reconstruction to the ancestor character for the leaf axil of Didiereaceae. This analysis indicated the presence of brachyblasts bearing prophylls in the leaf axil of the common ancestor. As a consequence, homologies between these prophylls and Talinaceae prophylls and Cactaceae spines were established
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Naftos ir naftos ploviklio Simple Green bendras toksinis poveikis vaivorykštiniam upėtakiui ankstyvoje ontogenezėje / The toxic effects of crude oil combined with oil cleaner "simple green" on rainbow trout in ontogenesisRatkelytė, Eglė 08 September 2009 (has links)
NAFTOS IR NAFTOS PLOVIKLIO SIMPLE GREEN BENDRAS TOKSINIS POVEIKIS VAIVORYKŠTINIAM UPĖTAKIUI ANKSTYVOJE ONTOGENEZĖJE E. Ratkelytė Vilniaus universitetas Santrauka Tyrimai buvo atlikti su vaivorykštinio upėtakio (Oncorhynchus mykiss) ikrais (nuo „akutės“ stadijos) ir lervomis (nuo jų išsiritimo pradžios iki trynio maišelio rezorbcijos), veikiant juos 0,11, 0,22, 0,43, 0,87, 1,73, 3,46, 6,93 g/l naftos koncentracijomis į kiekvieną iš jų pridedant 0,5 g/l ploviklio Simple Green. Toksiškumo kriterijai buvo upėtakio ikrų ir lervų žuvimo procentas, ir tokie fiziologiniai rodikliai, kaip širdies (ŠD) bei kvėpavimo (KD) dažniai. Darbo tikslas buvo ištirti naftos ir naftos ploviklio Simple Green bendrą toksinį poveikį vaivorykštiniam upėtakiui (Oncorhynchus mykiss) ankstyvose jo vystymosi stadijose priklausomai nuo koncentracijos ir poveikio trukmės bei įvertinti ilgalaikio poveikio fiziologiniams rodikliams ypatumus. Apibendrinus gautus rezultatus galima teigti, kad vaivorykštinio upėtakio jautrumas naftos ir ploviklio Simple Green mišiniui priklauso nuo mišiniu veikiamos individo vystymosi stadijos, poveikio trukmės, ir naftos bei ploviklio koncentracijų santykio mišinyje. Nustatyta, kad jautriausios naftos poveikiui pasirodė lervutės ritimosi metu, mažiau jautrūs pasirodė embrionai ankstyvoje „akutės“ stadijoje. Palyginus gautus rezultatus su rezultatais gautais tiriant vien tik naftos poveikį vaivorykštiniam upėtakiui ankstyvoje ontogenezėje, matome, kad ploviklis Simple Green... [toliau žr. visą tekstą] / THE TOXIC EFFECT OF CRUDE OIL COMBINED WITH OIL CLEANER „SIMPLE GREEN“ ON RAINBOW TROUT IN EARLY ONTOGENESIS E. Ratkelytė Vilnius University Summary Long-term effects of crude oil combined with oil cleaner „Simple Green“ were evaluated in chronic toxicity tests by use of rainbow trout (Oncorhynchus mykiss) in early stages of development (embryos, larvae) as test-objects. The following toxicity criteria were studied for evaluation of toxic effects: mortality of embryos and larvae; physiological parameters (heart rate, ventilation frequency). The aim of the study was to investigate the overall effect of crude oil combined with oil cleaner „Simple Green“ on rainbow trout (Oncorhynchus mykiss) in early development stages (embryos, larvae) depending on oil concentration in the mixture and exposure duration and to evaluate the specificity of negative effects of mixture on physiological parameters of fish. It was determined that 0.87, 1.73, 3.46 and 6.93 g/l concentrations of crude oil combined with 0.5 g/l of “Simple Green” resulted in the significant increase in larvae mortality, but practically had no negative effect on embryos. Hatching was found to be the most sensitive stage of development, 1 day age larvae were less and embryos were the least sensitive to the toxic impact of mixture, respectively. It was estimated that 0.87+0.5, 1.73+0.5, 3.46+0.5 and 6.93+0.5 g/l concentrations of crude oil combined with oil cleaner „Simple Green“ disturbed the work of cardiorespiratory... [to full text]
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Ontogenetic changes in the visual system of the brown banded bamboo shark, Chiloscyllium punctatum (Elasmobranchii), with special reference to husbandry and breedingBlake Harahush Unknown Date (has links)
Developmental studies on elasmobranchs are challenging due to the difficulties in obtaining sufficient numbers of animals of different age cohorts. The brown banded bamboo shark, Chiloscyllium punctatum is a good model in this regard as it is abundant and readily available in the wild, is quick to mature, is frequently housed and bred in captivity and is a relatively small species of shark. Whilst there are important factors that must be considered when comparing the retinal development of animals raised in captivity to those caught from the wild, the use of C. punctatum represents an outstanding opportunity to study the development of the elasmobranch visual system from pre-hatching embryonic to adult life stages. In this study, the developing eye and retina of C. punctatum were studied using light and electron microscopy, electroretinography (ERG) and microspectrophotometry (MSP). To provide a source of early-stage animals, and to investigate the effects of environmental factors (such as temperature) on physical development, a captive breeding program was established at the University of Queensland. Sharks sourced from this facility were supplemented with animals bred at UnderWater World, Sea World and caught from the wild. Monitoring the fecundity, embryonic development, growth and viability of captive C. punctatum showed that females lay an average of 115.3 eggs, 38 of which were viable and 21.4% of which hatched. Embryos have an average gestation of 153 days post deposition (dpd; temp: 21 - 25º C) and embryonic growth is most rapid from 99 dpd until hatching. The eye of C. punctatum develops early in embryogenesis, with visible optic vesicles bulging at 27 dpd. Recent advances in fixation and processing techniques for transmission electron microscopy (TEM) have yielded improved levels of ultrastructural detail in a variety of tissue types. Consequently, in addition to conventional chemical fixation (CF) methods, the retina of C. punctatum was also processed using microwave chemical fixation (MCF) and high pressure freezing (HPF), and the resulting ultrastructure compared. Both MCF and HPF produced superior retinal ultrastructure compared to conventional CF, evidenced by higher resolution of ultrastructural detail and fewer artefacts. MCF provided the best, consistent ultrastrucutral results. By examining the time-course of retinal cell differentiation, it was found that ganglion and Müller cells are the first to differentiate, at approximately 81 dpd. The interneurons differentiate next, beginning with the amacrine cells (81 dpd), followed by the bipolar cells (101 dpd) and horizontal cells (124 dpd). The adult retina is duplex and rod and cone photoreceptors are differentiated and synaptic connections are formed by 124 dpd. Topographic analysis of retinal neuron sub-types reveals that C. punctatum undergoes rapid changes in ganglion cell distribution during embryogenesis. High levels of apoptosis, especially around the retinal periphery, result in relatively higher cell densities in the central retina, which progressively extend nasally and temporally to form a meridional band. C. punctatum develops a horizontal streak and shows only minor changes in topography during growth. Only basal levels of apoptosis are seen post-hatching. In the adult shark, the total ganglion cell number reaches 547,881. The mean and highest retinal ganglion cell densities reach a peak around hatching (3,228 cells mm-2 and 4,983 cells mm-2, respectively). Using measurements of lens focal length and ganglion cell density, the calculated maximum spatial resolving power (assuming a hexagonal mosaic) increases from 1.47 cycles degree-1 during embryogenesis to 4.29 cycles degree-1 in adults. The addition of a high ganglion cell density area within the visual streak and an increasing spatial resolving power over post-hatching development suggest an increased prey targeting and capture ability for this species. Using ERG, it is shown that C. punctatum becomes responsive to light at 127 dpd and light sensitivity peaks around the time of hatching, with a slight decrease post-hatching. C. punctatum maintains a flicker fusion frequency (FFF; an indicator for temporal resolution) at 7 - 22 Hz through juvenile stages), which is relatively low compared to other marine predators. ERG results suggest that this species is adapted to low light vision with low temporal resolution. The early differentiation, development and functionality of the visual system in C. punctatum allows for a period of synaptic maturation and potentially the ability of embryonic predator avoidance. The retina of C. punctatum contains a rod visual pigment with a wavelength of maximum absorbance (λmax) at 500 nm and cone visual pigment with a λmax at 532 nm; the max values of these pigments do not change during development. Rod and cone outer segments differentiate at 113 days post deposition (dpd), lengthen during embryogenesis and accumulate pigment throughout life. Although the photoreceptors develop and differentiate well in advance of hatching, there is considerable variation in outer segment length and pigment density during embryogenesis, which suggests that these cells are developing up until hatching. C. punctatum does not appear to have the potential for colour vision based on the lack of two cone photoreceptor types each containing a visual pigment maximally sensitive to different parts of the visual spectrum, but appears specialised for dim-light contrast vision.
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Placas maxilo-dentárias em Rincossauros Hyperodapedon Huxley, 1859. Histologia e morfogênese maxilo-dental: nova abordagem.Cabreira, Sérgio Furtado January 2004 (has links)
O estudo das estruturas da placas maxilo-dentárias dos rincossauros Hyperodapedon Huxley, 1859, do Triássico da Formação Santa Maria, em nova abordagem histológica e ontogênica resultou na identificação da natureza do esmalte aprismático verdadeiro, de variados elementos histológicos dentinários e osteológicos, e de um centro de ossificação periosteal primário. Também foram encontradas evidências histológicas dos mecanismos de fusionamento maxilo-dentinário e amelo-maxilar. Com estes elementos, inferimos os modelos de organogênese dental, da ontogênese maxilar e dos mecanismos de fusionamento maxilodental. Encontrou-se uma singular e raríssima coroa dental, imatura e ainda não erupcionada, na região posterior da placa dental e assim evidenciou-se a correta posição da margem odontogenicamente ativa. Adicionalmente inferiu-se a localização da posição da lâmina dentária embrionária. Constatou-se a não formação de alvéolos dentários, de cemento radicular e do espaço necessário à formação do ligamento periodontal e, assim, se deduziu a não formação do folículo dental embriônico. As presenças de especiais elementos anatômicos e histológicos nos tecidos ósseos periapicais evidenciam o crescimento radicular contínuo, enquanto a forma e o fusionamento radicular imediato depõe a favor de uma função dentária fisiológica diferenciada para as baterias dentárias maxilares dos Rincossauros do gênero Hyperodapedon. Os mecanismos que possibilitaram o controle embriônico para a deposição das lamelas de tecido ósseo coronal e seu preciso fusionamento sobre o esmalte dentário, declinam por modificações nas funções tardias do órgão reduzido do esmalte e pela presença de uma membrana oral com funções osteogênicas e também protetivas, situada nas porções posteriores da placa maxilo-dentária em desenvolvimento. Mudanças heterocrônicas no tempo de diferenciação das células da crista neural embriônica e em seus derivados, como a lâmina dentária e órgãos dentários embrionários ou correlacionadas com a organogênese das placas maxilo-dentárias e seus anexos periodontais, todos como condições plesiomórficas para Diápsidas Triássicos, poderiam ser as causas responsáveis pela origem e evolução deste estranho aparelho estomatognático nos clados de Hyperodapedon sp.. / The study of the maxillary tooth-plate of Hyperodapedon Huxley, 1859, rhynchosaurs of the Triassic from Santa Maria Formation, in a new histological and odontogenic researches, resulted in a identification the nature of the true non prismatic (aprismatic) enamel, of a variety of dental and osteological elements, and of one primary periosteal center of ossification. We found histological evidences of the maxillary-dentinary and maxillary-enamel attachment process, and with these elements we infer the patterns of dental organogenesis, maxillary ontogenesis, and the embryonic mechanisms of maxillarydental junction. We found one rare immature and unerupted dental crown in the posterior dental-plate and so we turn evident the correct position of the maxillary odontogenic active border, and additionally we determine the correct position of embryonic dental lamina. This work constates that the dental sockets, dental cement and periodontal space are absenting in Hyperodapedon sp. maxillary tooth-plate and thus we deduce the dental embryonic follicle non-formation. The presence of the anatomics and histological osteal elements of periapical’s zone evidences the continuous radicular growth, while the form and the immediate radicular fusioning witness favorably of physiologically different teeth function for the dental-plate battery in Hyperodapedon rhynchosaur’s genus. The mechanisms that permit the embryonic control at the deposition of lamellar osteal coronal tissues and their precise fusioning on the dental enamel, testified the modifications of the late functions of the reducted enamel organ and the presence of oral mucous covertures, with present’s osteogenic and protetive activities. These mucous covertures should be situated in the posterior region of the development of the maxillary tooth plates. Heterochronic changes in the timing of differentiation of the embryonic neural crests cells and on their derivers with the dental lamina and dental organs or correlationed with the ontogenesis of the maxillary tooth plates and periodontal annex’s, would be responsible for the origin and evolution of this stranger stomatognatic apparel in Hyperodapedon sp. clades. These changes reflect plesiomorphic condition in relation the others Triassic Diapsides.
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