Les acides gras (AGs) sont des molécules nécessaires pour la survie des êtres vivants car ils participent à de nombreuses voies métaboliques et constituent un réservoir énergétique important. Malgré le lien établi entre les AGs et certaines maladies humaines (cancers, obésité, maladies cardiovasculaires), les mécanismes sous-jacents à la perception de ces composés ont été, jusqu’à présent, très peu explorés, en particulier chez les invertébrés. C'est l’une des raisons pour lesquelles, nous avons étudié, lors de notre thèse, la perception des AGs à longue chaine (C14:0, C16:0, C18:0, C18:1, C18:2, C18:3), en utilisant l’espèce modèle Drosophila melanogaster. Nous avons aussi tenté de caractériser quelques facteurs biologiques sous-jacents à la modulation de cette réponse. Nos observations comportementales, effectuées sur des individus ou des groupes issus des deux lignées sauvages Dijon2000 (Di2) et Canton-S, ont permis de démontrer que les larves étaient capables de distinguer ces AGs. En particulier, nous avons observé que les larves sont attirées par les AGs insaturés et fortement repoussées et/ou stressés par les AGs saturés. Ces derniers déclenchent d’ailleurs une forte réaction comportementale chez les groupes de larves qui montrent un phénomène durable d’agrégation. Une autre raison pour effectuer cette étude vient de la proximité structurale des AGs et des hydrocarbures cuticulaires qui servent de phéromones sexuelles chez les adultes. Ainsi, nous avons testé la réponse de mutants pour les gènes desat1 et CheB42a, qui sont impliqués dans la perception et/ou la discrimination de ces phéromones. Les larves mutantes desat1 ne montrent pas de comportement d’agrégation, ce qui suggère une altération de leur perception ou de leur réaction sur les AGs saturés. Nous avons ciblé des perturbations de desat1 dans divers tissus en combinant différentes lignées pilotes (correspondant aux différentes régions régulatrices de desat1) avec un transgène exprimant l’ARN interférent de desat1. Nous avons découvert qu’une région régulatrice ciblant l’ARN interférent dans une partie du cerveau perturbe la réponse aux AGs saturés, ce qui est cohérent avec le résultat précédent. Les larves portant le transgène CheB42a-Gal4 montrent des défauts plus subtils et néanmoins une répulsion moins forte vis-à-vis des AGs saturés. Nous avons tiré profit du temps court de génération de la drosophile pour réaliser deux expériences de sélection sur la lignée Di2, pendant environ 50 générations. Dans un premier temps, nous avons sélectionné, génération après génération, les larves montrant des réponses atténuées envers le C18:0, et nous avons observé, après 20 générations, une plus faible tendance à éviter cet AG. Dans un deuxième temps, nous avons élevé la lignée Di2 sur un milieu appauvri en AGs et nous avons noté que les larves ainsi élevées perçoivent anormalement le C18:3. Afin de vérifier si la préférence envers les AGs pouvait changer au cours de la vie, nous avons testé la réponse des adultes. Un test réalisé dans un olfactomètre, et visant à mesurer la réponse olfactive, montre que les adultes sont repoussés par le C18:3, et indifférents au C18:0. Un test de réponse gustative (répression de l’extension du proboscis) montre que les AGs insaturés répriment plus fortement la réponse que les AGs saturés. En conclusion, au cours de notre thèse, nous avons pu démontrer que les préférences envers les AGs saturés et insaturés varient au cours de la vie de la drosophile, peut-être en relation avec leurs besoins nutritifs. Les AGs semblent être perçus par olfaction, gustation, et peut être par mécanosensation. / Fatty-acids (FAs) are crucial for animal survival and reproduction since these molecules are involved in many metabolic pathways and constitute a substantial store of energy. Despite the strong relationship established between excessive FA consumption and severe human etiologies (obesity, cancer, vascular diseases), our knowledge of the mechanisms underlying FA perception and preference is limited particularly in invertebrates. This is one of the reasons why we decided to investigate, during our PhD thesis, the perception of long-chain FAs (C14:0, C16:0, C18:0, C18:1, C18:2, C18:3), using the model species Drosophila melanogaster. We have also attempted to characterize some of the biological factors involved in the modulation of this response. Our behavioral tests, carried both on individuals and groups of the two wild-type strains Dijon2000 (Di2) and Canton-S, revealed that larvae are able to distinguish these FAs. More precisely, we observed that larvae are attracted by unsaturated FAs and strongly repulsed and/or stressed by saturated FAs. The latter compounds also induce a strong behavioral reaction in groups of larvae resulting into a long-lasting aggregation figure. Another reason to study FAs is their structural proximity with cuticular hydrocarbons which act as sex pheromones in adults. Therefore, we measured the behavioral response of mutants for the desat1 and CheB42a genes, both of which are involved in the perception and/or discrimination of these pheromones. The fact that mutant desat1 larvae do not show aggregation behavior suggests that they have an abnormal perception or reaction to saturated FAs. We then targeted genetic alteration of desat1 using drivers (made with different regulatory regions of desat1) combined with a transgene carrying the interferential RNA of desat1. When targeting a specific brain region, we found that larvae do not properly react to C18:0. This result is coherent with the defect described above. On the other hand, larvae carrying the CheB42a-Gal4 transgene exhibit more subtle defects including a slightly altered reaction to saturated FAs. We also took advantage of the short generation time of D. melanogaster to perform two selection experiments using the parental Di2 strain during 50 generations. First, we selected, generation after generation, larvae showing decreased aversive response to C18:0, and we observed, after 20 generations, a weaker tendency to avoid this FA. Second, we maintained the Di2 strain on a food with a poor FA content, and we noted that resulting larvae show an altered response to C18:3. To check whether FA preference could change during life time, we also measured adult behavior. A first test performed in a olfactometer to assess olfactory response, revealed that flies are repulsed by C18:3, but are indifferent to C18:0. A second test assessing adult gustatory response (with the repression of the proboscis extension reflex) showed that unsaturated FAs repress behavior more strongly than saturated FAs. In summary, during our PhD thesis, we have shown that FA preference can change during the life of D. melanogaster, maybe in relation with different nutritional requirements. FAs seem to be perceived by olfaction, taste and maybe mechanosensation.

The global stressors of ocean warming and acidification, as well as local stressors such as eutrophication, overfishing, and coastal construction, have all contributed to the severe decline in coral populations worldwide. Recovery of coral reefs depends partly on recruitment, which relies on the response of larvae to settlement cues indicative of habitat quality; however, it remains unclear whether recruitment in disturbed areas will be compromised. Specifically, as reefs become more disturbed and dominated by macroalgae, it is important to understand larval behavior in response to changes in habitat quality. In this study, we first assessed the settlement success of newly released Agaricia agariciteslarvae in response to several settlement cues, including temperature and water movement. Then, to test the Desperate Larva Hypothesis, the ability of larvae of different ages (0-7 days) to settle and discriminate between inducing and inhibitory settlement cues was assessed. Newly released larvae displayed a stronger preference for settling on crustose coralline algae (93%) than on ceramic plates in macroalgae- (30%) or conspecific-treated seawater (5%), or filtered seawater (13%) (control). Older larvae became progressively less discriminatory of settlement cues, settling even in response to inhibitory cues. This confirms that, although the absence of good settlement cues initially deters settlement, larvae become desperate as they become older and settle even on unfavorable substrates, thus contributing to recruitment in poor quality habitats.

Made available in DSpace on 2017-07-25T19:29:56Z (GMT). No. of bitstreams: 1 Paulo Gallo.pdf: 1634093 bytes, checksum: f84f8b79e7d1355234216b134966f01a (MD5) Previous issue date: 2012-11-13 / The presence of Diabrotica speciosa larvae causes damage to corn root system and reduction in grain yield, mainly in second season crops. Applying insecticide in the seed furrow can be effective, but this assumes a form of preventive control and implies higher production costs and environmental impact. We evaluated the efficacy of genotypes AG7000RW and DKB330RW (Cry3Bb1) and their isolines to reduce the damage caused by D. speciosa larvae to corn root system, the efficacy of the insecticide fipronil applied in the furrow, and the effect of the interaction of both treatments on the yield of maize hybrids, as well as the planting date when the most severe damage occurs. The efficacy experiment was carried out in Itaberá, SP, in no-till planting system after oat crop. The damage to the roots was evaluated 52 days after emergence, using a visual score according to its intensity. Stalk lodging was determined by counting the plants leaning more than 25º in relation to its own axis at harvest. Genotypes AG7000 and DKB330 with no insecticide application presented damage and the resulting scores were 1.62 and 1.85, whereas the scores of their Bt isolines were 0.25 and 0.24, respectively. Genotypes AG7000 and AG700RW had the highest percentage of matter and amount of dry root in relation to DKB330 and DKB330RW, regardless of insecticide application. Stalk lodging of 46.7% found in non-Bt genotype DKB330 with no insecticide application reflected negatively on the yield of this treatment. In contrast, with insecticide application, stalk lodging ranged from 0.2% to 2.2% between genotypes, not influencing their yield. Cry3Bb1 protein was effective in reducing the damage to the root regardless of the genotype tested. Genotypes with high yield potential and lower root mass may present higher yield response when protected by the toxin or insecticide in the presence of a large larval population. In the 2010/2011 season, we assessed the damage in non-Bt corn root at four planting dates in Itaberá (10/14, 11/3, 11/25, and 12/20) and three in Castro, PR (9/29, 10/21, and 11/11). In the following season, 2011/2012, we evaluated six planting dates in Itaberá (9/21, 10/18, 11/21, 12/28, 1/30, and 2/20) and four in Castro (9/20, 10/10, 10/30, and 11/20). We observed that, from the second planting date on, the root damage reached scores over 3.0 and remained above 4.0 in all other planting dates in Itaberá in both seasons. In Castro, only the seeding performed in 11/20/2011 reached a score above 3.0. The use of protection in corn root, by applying insecticide or toxin, presented a greater response in sowing carried out from October on in the region of Itaberá. / A presença de larva de Diabrotica speciosa danifica o sistema radicular do milho e causa redução na produtividade de grãos, principalmente nas lavouras de segunda safra. A aplicação de inseticida no sulco de semeadura pode ser eficaz, porém, esta forma de controle assume caráter preventivo e implica maior custo de produção e impacto ambiental. Avaliaram-se a eficácia dos genótipos AG7000RW e DKB330RW (Cry3Bb1) e de suas isolíneas na redução do dano da larva de D. speciosa na raiz do milho, a eficácia do inseticida fipronil aplicado no sulco de semeadura e o efeito da interação de ambos os tratamentos sobre a produtividade dos genóti os de milho, bem como a época de semeadura em que ocorre maior dano da larva. O experimento de eficácia foi instalado em Itaberá, SP, na safra 2011/2012, sob sistema de plantio direto na palha após cultura de aveia. Os danos nas raízes foram avaliados aos 52 dias após a emergência, atribuindo-se nota visual de acordo com sua intensidade. O acamamento foi determinado contando-se as plantas com inclinação maior que 25º em relação ao próprio eixo no momento da colheita. Os genótipos AG7000 e DKB330 sem inseticida apresentaram dano, e as notas resultantes foram 1,62 e 1,85, enquanto as notas de suas isolíneas Bt foram 0,25 e 0,24, respectivamente. Os genótipos AG7000 e AG700RW obtiveram os maiores percentuais de matéria e quantidade de massa seca na raiz em relação a DKB330 e DKB330RW, independentemente da aplicação do inseticida. O acamamento de 46,7% encontrado para o genótipo DKB330 sem aplicação de inseticida refletiu negativamente na produtividade deste tratamento. Por outro lado, com a aplicação de inseticida, o acamamento variou de 0,2% a 2,2% entre os genótipos, não influenciando sua produtividade. A proteína Cry3Bb1 foi eficaz na redução dos danos na raiz independentemente do genótipo testado. Genótipos com alto potencial produtivo e com menor massa de raiz podem apresentar maior resposta de produtividade quando protegidos com a toxina ou o inseticida na presença de alta população de larvas. Na safra 2010/2011, avaliaram-se os danos na raiz do milho não Bt em quatro épocas de semeadura em Itaberá (14/10, 3/11, 25/11 e 20/12) e três em Castro, PR (29/9, 21/10 e 11/11). Na safra seguinte, de 2011/2012, avaliaram-se seis épocas em Itaberá (21/9, 18/10, 21/11, 28/12, 30/1 e 20/2) e quatro em Castro (20/9, 10/10, 30/10 e 20/11). Constatou-se que, a partir da segunda época, os danos na raiz atingiram nota superior a 3,0 e permaneceram acima de 4,0 em todas as demais épocas de semeadura em Itaberá, nas duas safras avaliadas. Em Castro, apenas a semeadura de 20/11/2011 atingiu nota superior a 3,0. A utilização da proteção na raiz do milho, pela utilização de inseticida ou toxina, apresentou maior resposta nas semeaduras realizadas a partir do mês de outubro na região de Itaberá.

The purpose of the thesis is to explore the role of BMP signaling in developing vertebrate midbrain. BMP signaling plays important roles in various tissues and stages of neural development to regulate cell fate, proliferation, differentiation, morphogenesis and more. We observed that several major BMPs are expressed not only at the roof plate but also the floor plate of the midbrain. This has led us to ask the role of BMP signaling in dorsal and ventral midbrain patterning. Despite ventral experiments, we found that BMP signaling does not regulate ventral cell fate specification in the midbrain. Instead BMPs profoundly influence the shape and early morphogenesis of the midbrain neural plate as it closes into a neural tube. During neural tube closure, one of the early events occurring at the ventral midline is median hinge point (MHP) formation. Failure to form MHP leads to neural tube closure defects, the 2nd most common birth defects in humans. However, the molecular mechanisms underlying MHP formation are not well known. We found that the lowest BMP signaling occurs at the MHP during early neurulation and BMP blockade is necessary and sufficient for MHP formation. Interestingly, we also demonstrated that BMP blockade directs MHP formation by regulating the apicobasal polarity pathway and this regulation may be mediated by biochemical interactions between pSMAD5 and the apical protein, PAR3. Additionally, our time-lapse data suggest that BMP blockade slows cell cycle progression by increasing duration of G1 to S transition and S phase which leads cell nuclei stay at the basal location longer. This mimics basal nuclear migration seen at the MHP where low BMP signaling occurs. Thus, we conclude that BMP signaling regulates neural tube closure via the apicobasal polarity pathway and in a cell cycle dependent manner at the ventral midline. We observed that BMP signaling is necessary and sufficient for the dorsal cell fate specification in a context-dependent manner and ventral BMP signaling affects dorsal cell fates. Taken together, we propose the idea that BMP signaling has distinct roles in different contexts. BMPs regulate tissue morphogenesis in the ventral midbrain and dorsally cell fate specification. / text

Orientador: Marcos Gomes Nogueira / Banca: Antonio Leão Castilho / Banca: Eliana Aparecida Passareli / Resumo: O mexilhão-dourado (Limnoperna fortunei) é um bivalve de água doce pertencente à família Mytilidae. Originário de rios e arroios da China e do sudeste asiático, a espécie foi introduzida acidentalmente na América do Sul em 1991, no estuário do rio da Prata, provavelmente através de água de lastro. A partir disso, dispersou-se para os rios Paraguai, Uruguai e Paraná, principais canais de drenagem da bacia do Prata. Devido ao seu grande potencial reprodutivo, crescimento rápido e capacidade de formar aglomerados populacionais em curto espaço de tempo, L. fortunei causa grandes alterações ecológicas e econômicas, como a obstrução nas canalizações e entradas de água de usinas hidrelétricas e redes de tratamento de água. O presente estudo teve como objetivo avaliar a distribuição de L. fortunei nos principais corpos d'água formadores da Bacia do rio da Prata, bem como a possível influência das condições ambientais sobre as densidades populacionais. Os dados foram obtidos a partir de amostragens realizadas em janeiro/fevereiro e junho/julho de 2010, com coletas complementares em junho de 2013 e fevereiro de 2014. Foram empregados arrastos verticais com rede cônica de 68 μm de abertura de malha para coleta das larvas e simultaneamente determinadas as variáveis limnológicas (temperatura, transparência, turbidez, pH, condutividade e oxigênio dissolvido). Conclui-se que o processo de dispersão da espécie se deu de uma forma muita rápida, uma vez que a sua chegada ao continente ocorreu há apenas duas décadas e atualmente encontra-se amplamente distribuída por toda a bacia (aproximadamente 15 graus de latitude e extensão linear de 1700 km). Isto se explica devido a elevada capacidade de dispersão intrínseca da espécie (larvas planctônicas livre-natantes), incrustação em embarcações e ampla tolerância aos fatores ambientais. Picos máximos de densidade, cerca de 60.000 ind.m-3, foram encontrados nos... / Abstract: The golden mussel (Limnoperna fortunei) is a freshwater bivalve belonging to Mytilidae family. Originally from rivers and streams of China and Southeast Asia, the species was accidentally introduced in South America in 1991, in the River the la Plata estuary, probably through ballast water. From there, it dispersed to the rivers Paraguay, Uruguay and Paraná, major drainage channels of the basin. Due to its great reproductive potential, rapid growth and ability to form settlements in short time, L. fortunei cause major ecological and economic changes, such as blockage of the drainage system and water intakes of power plants and water treatment networks. This study aimed to evaluate the distribution of L. fortunei in the main water bodies of the River de la Plata Basin, as well as the possible influence of environmental conditions on the population densities. Data were obtained from samples taken in January/February and June/July 2010, with additional sampling in June 2013 and February 2014. Vertical hauls were employed with conical network of 68 μm mesh size to collect the larvae and the limnological variables (temperature, transparency, turbidity, pH, conductivity and dissolved oxygen) were simultaneously determined. It is concluded that the species dispersion process was very fast, since their arrival in the continent occurred just two decades ago and presently it is widely distributed throughout the basin (approximately 15 degrees latitude and a linear extension of 1700 km). This is explained by the high intrinsic dispersal ability of the species (free planktonic larvae), boat incrustation and broad tolerance to environmental factors. Maximum density peaks, about 60,000 ind. m-3, were found in the lower reaches of the basin, the River de la Plata ((URU/ARG), where the species was introduced. However, we refutes the hypothesis that there is a decreasing gradient of abundance in the south-north direction. Correlation analyzes indicate ... / Mestre

Les CPGs (Central Pattern Generators) sont des circuits neuronaux capables de générer de façon autonome des comportements rythmiques essentiels à la vie tels que la respiration ou la locomotion. Chez la larve de Drosophile, le CPG locomoteur est composé de motoneurones (MNs) et d’une grande diversité d’interneurones (INs). Combien d’entre eux sont nécessaires pour former une CPG fonctionnel et comment ils interagissent reste un mystère. Au cours de mon doctorat, j’ai étudié une population neuronale restreinte caractérisée par son expression du facteur de transcription (FT) de la famille des Maf, Traffic Jam (TJ). En utilisant une technique d’intersection génétique et grâce à une lignée TJ-Flp générée au cours de mon doctorat, j’ai démontré pour la première fois que différentes sous-populations de neurones TJ+ ont des fonctions distinctes dans le comportement locomoteur de la larve de Drosophile. Au travers de cette sous-division fonctionnelle, j’ai finalement identifié 3 neurones TJ+ per+ GABAergic par segment qui régulent la vitesse de locomotion des larves. Une caractérisation moléculaire poussée de ces cellules a permis de confirmer qu’elles appartiennent au groupe connu des « midline cells », et plus particulièrement des mnb progeny, dont la fonction était jusqu’à maintenant inconnue. Par ailleurs, le code combinatoire de FTs trouvé chez ces mnb progeny rappelle celui exprimé par les V2b, une population d’interneurones qui régulerait également la vitesse de locomotion chez les vertébrés. Ces similarités entre mnb progeny et V2b laissent à penser que cette population de neurones pourrait être conservée au cours de l’évolution. En outre, des résultats préliminaires suggèrent que les interneurones TJ+ ont également un rôle chez la mouche adulte. / CPGs (Central Pattern Generators) are neural networks able to autonomously generate essential rhythmic behaviours such as walking or breathing. In Drosophila larvae, the locomotor CPG is made up of motoneurons (MNs) and a huge variety of interneurons (INs). How many are actually necessary to constitute a functional CPG and how they interact is not known. During the course of this PhD, I studied a discrete neuronal population singled out by its expression of the Maf transcription factor (TF) Traffic Jam (TJ). Thanks to an intersectional genetics approach and a TJ-Flp line generated during my PhD, I showed for the first time that TJ+ neurons subpopulations have distinct functions in Drosophila larva locomotion. Functional subdivision of TJ+ population eventually led to the identification of 3 TJ+ per+ GABAergic neurons that regulate the speed of locomotion. Thorough molecular characterization of this population permitted to identify them as mnb progeny neurons, a well studied subgroup of midline cells whose function had never been described before. The TF combinatorial code expressed by these cells is highly reminiscent of the one found in V2b INs, a population in vertebrates thought to regulate the speed of locomotion as well in vertebrates; this opens the possibility of a functional conservation across evolution. Preliminary results furthermore suggest that TJ+ INs would have functional roles in the adult fly.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Agrarias / Made available in DSpace on 2012-10-16T07:01:25Z (GMT). No. of bitstreams: 0 / Exemplares de Nodipecten nodosus foram coletados nas imediações da Ilha do Arvoredo (SC) e transportados para o Laboratório de Cultivo de Moluscos Marinhos (UFSC), onde foram utilizados para a manutenção de reprodutores, bem como os métodos empregados na indução à desova, larvicultura e cultivo pós-larval. Obteve-se a liberação de gametas viáveis e êxito na fecundação e no cultivo larval. Descreve-se o desenvolvimento de caracteres morfológicos externos, bem como as percentagens de sobrevivência das larvas cultivadas. Larvas véliger de charneira reta foram observadas 22 horas após a fecundação. Aos 7 dias o umbo começava a se destacar da linha de charneira. Decorridos 11 dias da fecundação, umbo mascarava completamente a linha de charneira na maioria das larvas. Aos 14 dias eram observadas larvas pedivéliger apresentando mancha ocular conspícua e pé ativo. Registrou-se o assentamento e metamorfose de larvas sobre substratos artificiais (Netlon e policarbonato). Os primeiros organismos fixados apresentando dissoconcha conspícua foram observados no 19o dia após a fecundação. Um lote de organismos foi cultivado em laboratório até 52 dias após a fecundação, quando estes atingiram um comprimento médio de 1,1 mm. Outro lote de organismos foi transplantado para o ambiente natural 33 dias após a fecundação, os quais atingiram após 38 dias de cultivo neste ambiente um comprimento médio de 5,16 mm. Com o presente trabalho registro-se, pela primeira vez para Nodipecten nodosus, a produção experimental de sementes sob condições de laboratório.

Made available in DSpace on 2015-10-06T13:03:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-08. Added 1 bitstream(s) on 2015-10-06T13:18:35Z : No. of bitstreams: 1 000849888.pdf: 959403 bytes, checksum: e9f8b03a191fa7e4bdb809755968d258 (MD5) / Organização dos Estados Americanos (OEA) / O mexilhão-dourado (Limnoperna fortunei) é um bivalve de água doce pertencente à família Mytilidae. Originário de rios e arroios da China e do sudeste asiático, a espécie foi introduzida acidentalmente na América do Sul em 1991, no estuário do rio da Prata, provavelmente através de água de lastro. A partir disso, dispersou-se para os rios Paraguai, Uruguai e Paraná, principais canais de drenagem da bacia do Prata. Devido ao seu grande potencial reprodutivo, crescimento rápido e capacidade de formar aglomerados populacionais em curto espaço de tempo, L. fortunei causa grandes alterações ecológicas e econômicas, como a obstrução nas canalizações e entradas de água de usinas hidrelétricas e redes de tratamento de água. O presente estudo teve como objetivo avaliar a distribuição de L. fortunei nos principais corpos d'água formadores da Bacia do rio da Prata, bem como a possível influência das condições ambientais sobre as densidades populacionais. Os dados foram obtidos a partir de amostragens realizadas em janeiro/fevereiro e junho/julho de 2010, com coletas complementares em junho de 2013 e fevereiro de 2014. Foram empregados arrastos verticais com rede cônica de 68 μm de abertura de malha para coleta das larvas e simultaneamente determinadas as variáveis limnológicas (temperatura, transparência, turbidez, pH, condutividade e oxigênio dissolvido). Conclui-se que o processo de dispersão da espécie se deu de uma forma muita rápida, uma vez que a sua chegada ao continente ocorreu há apenas duas décadas e atualmente encontra-se amplamente distribuída por toda a bacia (aproximadamente 15 graus de latitude e extensão linear de 1700 km). Isto se explica devido a elevada capacidade de dispersão intrínseca da espécie (larvas planctônicas livre-natantes), incrustação em embarcações e ampla tolerância aos fatores ambientais. Picos máximos de densidade, cerca de 60.000 ind.m-3, foram encontrados nos... / The golden mussel (Limnoperna fortunei) is a freshwater bivalve belonging to Mytilidae family. Originally from rivers and streams of China and Southeast Asia, the species was accidentally introduced in South America in 1991, in the River the la Plata estuary, probably through ballast water. From there, it dispersed to the rivers Paraguay, Uruguay and Paraná, major drainage channels of the basin. Due to its great reproductive potential, rapid growth and ability to form settlements in short time, L. fortunei cause major ecological and economic changes, such as blockage of the drainage system and water intakes of power plants and water treatment networks. This study aimed to evaluate the distribution of L. fortunei in the main water bodies of the River de la Plata Basin, as well as the possible influence of environmental conditions on the population densities. Data were obtained from samples taken in January/February and June/July 2010, with additional sampling in June 2013 and February 2014. Vertical hauls were employed with conical network of 68 μm mesh size to collect the larvae and the limnological variables (temperature, transparency, turbidity, pH, conductivity and dissolved oxygen) were simultaneously determined. It is concluded that the species dispersion process was very fast, since their arrival in the continent occurred just two decades ago and presently it is widely distributed throughout the basin (approximately 15 degrees latitude and a linear extension of 1700 km). This is explained by the high intrinsic dispersal ability of the species (free planktonic larvae), boat incrustation and broad tolerance to environmental factors. Maximum density peaks, about 60,000 ind. m-3, were found in the lower reaches of the basin, the River de la Plata ((URU/ARG), where the species was introduced. However, we refutes the hypothesis that there is a decreasing gradient of abundance in the south-north direction. Correlation analyzes indicate ...

Recent advances in the field of host immunity against parasitic nematodes have revealed the importance of macrophages in trapping tissue migratory larvae. Protective immune mechanisms against the rodent hookworm Nippostrongylus brasiliensis (Nb) are mediated, at least in part, by IL-4-activated macrophages that bind and trap larvae in the lung. However, it is still not clear how host macrophages recognize the parasite. An in vitro co-culture system of bone marrow-derived macrophages and Nb infective larvae was utilized to screen for the possible ligand-receptor pair involved in macrophage attack of larvae. Competitive binding assays revealed an important role for β-glucan recognition in the process. We further identified a role for CD11b and the non-classical pattern recognition receptor ephrin-A2 (EphA2), but not the highly expressed β-glucan dectin-1 receptor, in this process of recognition. This work raises the possibility that parasitic nematodes synthesize β-glucans and it identifies CD11b and ephrin-A2 as important pattern recognition receptors involved in the host recognition of these evolutionary old pathogens. To our knowledge, this is the first time that EphA2 has been implicated in immune responses to a helminth.

Ultradiluição (UHD) é o efeito de uma solução, diluída acima do número de Avogrado, que na dependência da sua dinamização (diluição com sucussão) induz um efeito celular supressivo ou estimulante, com conseqüente obtenção de uma curva dose-efeito oscilatória. Por outro lado, a 3,3,5 Triiodo-L-Tironina (T3) é o hormônio mais importante na indução e manutenção das mudanças metamórficas dos girinos, nelas incluídas a absorção da cauda. O presente estudo, cego e randomizado, tem como objetivo comprovar que o T3 5.10-24M (10ª cH) altera a apoptose induzida pelo T3 100 nM na cauda de girinos de Rana catesbeiana, in vitro. Foram distribuídos 60 explantes em três grupos: Grupo A: sem o estímulo do T3 em dose farmacológica e em UHD; Grupo B (teste): sob a ação de T3 100 nM e T3 10ª cH (5.10-24 M); Grupo C (controle): sob a ação do T3 100 nM e etanol 70% sem sucussão. A análise estatística da área dos explantes, no primeiro e ultimo dia do experimento, e do índice apoptótico foi realizado através do teste t Student e foi considerado estatisticamente significante quando p<0,05. Embora sem diferenças significativas na área dos explantes do grupo teste e no grupo controle, um maior e significante índice apoptótico foi identificado nos explantes do grupo teste. Este resultado confirma que o T3 na 10ª cH altera a ação do T3 em dose farmacológica. Futuros experimentos serão realizados, com diferentes dinamizações, com o objetivo da parametrização da curva dose-efeito / Ultra High Dilution (UHD) is the effect of a solution, beyond the Avogadro limits, that in the dependence of the applied dinamization (dilution with succussion) elicits a suppressive or a stimulant effect on a living cell, with a consequent generation of an oscillatory dose-effect curve. The entire process of anuran amphibian metamorphosis is under thyroid hormones control, included the complete resorption of the tadpole tail. A random and blind study was performed, with the intent to prove that T3 5.10-24 M (10ª cH) modifies the apoptosis induction of T3 100 nM in Rana catesbeiana tadpoles tail tips, in vitro. 60 Explants were distributed in three ways: Group A: without T3 action, at pharmacological and UHD dose; Group B (test): under the action of T3 100 nM and treated with T3 10ª cH (UHD); Group C (control): under the action of T3 100 nM and treated with ethanol 70% unsuccussed. In order to identify significant differences in the area of the remainder explants, at the first and final day of the experiment, and in the apoptotic index we used a student t-test. Although we didnt find statistical difference in macroscopic tadpoles tail tips area from test and control groups, a high and significant (p<0,05) index of apoptosis in histology was found in explants of test group. This data confirms that T3 10 cH modifies the effect of T3 at pharmacological dose. More studies will be necessary, using different dinamizations, to the parameterization of the dose-effect curve proceeding from these experiments