922 resultados para Rare fishes


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We describe a unique case of anorectal malformation (ARM) with a non-terminal colovesical fistula. While some aspects are similar to the congenital pouch colon (CPC), the differences make it a distinct form.

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Case: A 11 yo girl with Marfan syndrome was referred to cardiac MR (CMR) to measure the size of her thoracic aorta. She had a typical phenotype with arachnodactyly, abnormally long arms, and was tall and slim (156 cm, 28 kg, body mass index 11,5 kg/m2). She complained of no symptoms. Cardiac auscultation revealed a prominent mid-systolic click and an end-systolic murmur at the apex. A recent echocardiogram showed a moderately dilated left ventricle with normal function and a mitral valve prolapse with moderate mitral valve regurgitation. CMR showed a dilatation of the aortic root (38 mm, Z-score 8.9) and a severe prolapse of the mitral valve with regurgitation. The ventricular cavity was moderately dilated (116 ml/m2) and its contraction was hyperdynamic (stroke volume (SV): 97 ml; LVEF 72%, with the LV volumes measured by modified Simpson method from the apex to the mitral annulus). In this patient however, the mitral prolapse was characterized by a severe backward movement of the valve toward the left atrium (LA) in systole and the dyskinetic movement of the atrioventricular plane caused a ventricularisation of a part of the LA in systole (Figure). This resulted in a significant reduction of LVEF: more than ¼ of the apparent SV was displaced backwards into the ventricularized LA volume, reducing the effective LVEF to 51% (effective SV 69ml). Moreover, by flow measurement, the SV across the ascending aorta was 30 ml (cardiac index 2.0 l/min/m2) allowing the calculation of a regurgitant fraction across the mitral valve of 56%, which was diagnostic for a severe mitral valve insufficiency. Conclusion: This case illustrates the phenomenon of a ventricularisation of the LA where the severe prolapse gives the illusion of a higher attachement of the mitral leaflets within the atrial wall. Besides the severe mitral regurgitation, this paradoxical backwards movement of the valve causes an intraventricular unloading during systole reducing the apparent LVEF of 72% to an effective LVEF of only 51%. In addition, forward flow fraction is only 22% after accounting for the regurgitant volume, as well. This combined involvement of the mitral valve could explain the discrepancy between a low output state and an apparently hyperdynamic LV contraction. Due to its ability to precisely measure flows and volumes, CMR is particularly suited to detect this phenomenon and to quantify its impact on the LV pump function.

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We report the case of a 53 year old patient who was admitted with polyuria, polydipsia associated with fatigue, depression and sexual dysfunction. Central diabetes insipidus with hypogonadotrophic hypogonadism was diagnosed by a water restriction test and different static and dynamic hormonal dosages. Nodular thickening of the pituitary stalk was noted on the MRI and the biopsy permitted a histological diagnosis of infundibulitis.

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The genetic aetiology of congenital hypopituitarism (CH) is not entirely elucidated. FGFR1 and PROKR2 loss-of-function mutations are classically involved in hypogonadotrophic hypogonadism (HH), however, due to the clinical and genetic overlap of HH and CH; these genes may also be involved in the pathogenesis of CH. Using a candidate gene approach, we screened 156 Brazilian patients with combined pituitary hormone deficiencies (CPHD) for loss-of-function mutations in FGFR1 and PROKR2. We identified three FGFR1 variants (p.Arg448Trp, p.Ser107Leu and p.Pro772Ser) in four unrelated patients (two males) and two PROKR2 variants (p.Arg85Cys and p.Arg248Glu) in two unrelated female patients. Five of the six patients harbouring the variants had a first-degree relative that was an unaffected carrier of it. Results of functional studies indicated that the new FGFR1 variant p.Arg448Trp is a loss-of-function variant, while p.Ser107Leu and p.Pro772Ser present signalling activity similar to the wild-type form. Regarding PROKR2 variants, results from previous functional studies indicated that p.Arg85Cys moderately compromises receptor signalling through both MAPK and Ca(2) (+) pathways while p.Arg248Glu decreases calcium mobilization but has normal MAPK activity. The presence of loss-of-function variants of FGFR1 and PROKR2 in our patients with CPHD is indicative of an adjuvant and/or modifier effect of these rare variants on the phenotype. The presence of the same variants in unaffected relatives implies that they cannot solely cause the phenotype. Other associated genetic and/or environmental modifiers may play a role in the aetiology of this condition.

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Abstract The present report describes a case where typical findings of traumatic glenohumeral interposition of rotator cuff stumps were surgically confirmed. This condition is a rare complication of shoulder trauma. Generally, it occurs in high-energy trauma, frequently in association with glenohumeral joint dislocation. Radiography demonstrated increased joint space, internal rotation of the humerus and coracoid process fracture. In addition to the mentioned findings, magnetic resonance imaging showed massive rotator cuff tear with interposition of the supraspinatus, infraspinatus and subscapularis stumps within the glenohumeral joint. Surgical treatment was performed confirming the injury and the rotator cuff stumps interposition. It is important that radiologists and orthopedic surgeons become familiar with this entity which, because of its rarity, might be neglected in cases of shoulder trauma.

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Nota breu de fauna sobre les noves introduccions i el poblament actual de peixos a l’estany de Banyoles

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Gustaf (Gösta) Sundman (1854-1914) tuli tunnetuksi korkeatasoisten luonnontieteellisten kuvateosten kuvittajana. Finlands fiskar –teos ilmestyi kahtenatoista vihkona 1883-1893, upeat, metallihohtoiset kalojen kuvat irrallisina tauluina. Kalateokset tekstit ovat eläintieteen professori O. M. Reuterin ja eläintieteellisen museon amanuenssin A. J. Melan laatimia.

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Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the topdown effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire.We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore ecosystem structure and function.

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We experimentally examined the predator-prey relationships between juvenile spotted sorubim Pseudoplastystoma corruscans and young-of-the-year invasive and native fish species of the Paraná River basin, Brazil. Three invasive (peacock bass Cichla piquiti, Nile tilapia Oreochromis niloticus, and channel catfish Ictalurus punctatus) and two native (yellowtail tetra Astyanax altiparanae and streaked prochilod Prochilodus lineatus) fish species were offered as prey to P. corruscans in 300 L aquaria with three habitat complexity treatments (0%, 50% and 100% structure-covered). Prey survival was variable through time and among species (C. piquiti < O. niloticus < A. altiparanae < P. lineatus < I. punctatus), depending largely on species-specific prey behavior but also on prey size and morphological defenses. Habitat complexity did not directly affect P. corruscans piscivory but some prey species changed their microhabitat use and shoaling behavior among habitat treatments in predator’s presence. Pseudoplatystoma corruscans preyed preferentially on smaller individuals of those invasive species with weak morphological defensive features that persisted in a non-shoaling behavior. Overall, our results contrast with those in a companion experiment using a diurnal predator, suggesting that nocturnal piscivores preferentially prey on different (rather diurnal) fish species and are less affected by habitat complexity. Our findings suggest that recovering the native populations of P. corruscans might help controling some fish species introduced to the Paraná River basin, particularly C. piquiti and O. niloticus, whose parental care is expected to be weak or null at night

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Genetic diversity is one of the levels of biodiversity that the World Conservation Union (IUCN) has recognized as being important to preserve. This is because genetic diversity is fundamental to the future evolution and to the adaptive flexibility of a species to respond to the inherently dynamic nature of the natural world. Therefore, the key to maintaining biodiversity and healthy ecosystems is to identify, monitor and maintain locally-adapted populations, along with their unique gene pools, upon which future adaptation depends. Thus, conservation genetics deals with the genetic factors that affect extinction risk and the genetic management regimes required to minimize the risk. The conservation of exploited species, such as salmonid fishes, is particularly challenging due to the conflicts between different interest groups. In this thesis, I conduct a series of conservation genetic studies on primarily Finnish populations of two salmonid fish species (European grayling, Thymallus thymallus, and lake-run brown trout, Salmo trutta) which are popular recreational game fishes in Finland. The general aim of these studies was to apply and develop population genetic approaches to assist conservation and sustainable harvest of these populations. The approaches applied included: i) the characterization of population genetic structure at national and local scales; ii) the identification of management units and the prioritization of populations for conservation based on evolutionary forces shaping indigenous gene pools; iii) the detection of population declines and the testing of the assumptions underlying these tests; and iv) the evaluation of the contribution of natural populations to a mixed stock fishery. Based on microsatellite analyses, clear genetic structuring of exploited Finnish grayling and brown trout populations was detected at both national and local scales. Finnish grayling were clustered into three genetically distinct groups, corresponding to northern, Baltic and south-eastern geographic areas of Finland. The genetic differentiation among and within population groups of grayling ranged from moderate to high levels. Such strong genetic structuring combined with low genetic diversity strongly indicates that genetic drift plays a major role in the evolution of grayling populations. Further analyses of European grayling covering the majority of the species’ distribution range indicated a strong global footprint of population decline. Using a coalescent approach the beginning of population reduction was dated back to 1 000-10 000 years ago (ca. 200-2 000 generations). Forward simulations demonstrated that the bottleneck footprints measured using the M ratio can persist within small populations much longer than previously anticipated in the face of low levels of gene flow. In contrast to the M ratio, two alternative methods for genetic bottleneck detection identified recent bottlenecks in six grayling populations that warrant future monitoring. Consistent with the predominant role of random genetic drift, the effective population size (Ne) estimates of all grayling populations were very low with the majority of Ne estimates below 50. Taken together, highly structured local populations, limited gene flow and the small Ne of grayling populations indicates that grayling populations are vulnerable to overexploitation and, hence, monitoring and careful management using the precautionary principles is required not only in Finland but throughout Europe. Population genetic analyses of lake-run brown trout populations in the Inari basin (northernmost Finland) revealed hierarchical population structure where individual populations were clustered into three population groups largely corresponding to different geographic regions of the basin. Similar to my earlier work with European grayling, the genetic differentiation among and within population groups of lake-run brown trout was relatively high. Such strong differentiation indicated that the power to determine the relative contribution of populations in mixed fisheries should be relatively high. Consistent with these expectations, high accuracy and precision in mixed stock analysis (MSA) simulations were observed. Application of MSA to indigenous fish caught in the Inari basin identified altogether twelve populations that contributed significantly to mixed stock fisheries with the Ivalojoki river system being the major contributor (70%) to the total catch. When the contribution of wild trout populations to the fisheries was evaluated regionally, geographically nearby populations were the main contributors to the local catches. MSA also revealed a clear separation between the lower and upper reaches of Ivalojoki river system – in contrast to lower reaches of the Ivalojoki river that contributed considerably to the catch, populations from the upper reaches of the Ivalojoki river system (>140 km from the river mouth) did not contribute significantly to the fishery. This could be related to the available habitat size but also associated with a resident type life history and increased cost of migration. The studies in my thesis highlight the importance of dense sampling and wide population coverage at the scale being studied and also demonstrate the importance of critical evaluation of the underlying assumptions of the population genetic models and methods used. These results have important implications for conservation and sustainable fisheries management of Finnish populations of European grayling and brown trout in the Inari basin.

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Na viagem efetuada à volta do mundo pela U. S. Exploring Expedition mais conhecida pelo nome de Expedição Wilkes e durante o período em que a mesma operava no Atlântico Ocidental, foram visitadas as regiões do Rio de Janeiro e da Patagônia. Por ocasião da festa comemorativa do centenário da The American Philosophical Society, de Filadélfia, ocorrida a 23 de Fevereiro de 1930, o autor teve a oportunidade de apresentar uma nota prévia da qual constava uma lista de peixes capturados durante o cruzeiro da Expedição. Teve, então, o ensejo de examinar o diário redigido pelo Dr. Charles Pickering, botânico da Expedição, nele encontrando anotações valiosas para a História Natural, considerada em seu sentido amplo, detalhes a respeito das localidades percorridas e relações extensas de animais e plantas, além de diversos representantes pertencentes a outros grupos. Sob o ponto de vista histórico, os comentários aí constantes são de importância significativa. Em muitos casos, essas apreciações fornecem base sólida para a efetivação de estudos faunísticos, de caráter comparativo, muito instrutivos e úteis. O autor examinou a coleção de peixes da Expedição Wilkes que se encontra no Museu Nacional dos Estados Unidos, em Washington, acervo esse gentilmente posto à sua disposição para estudo. Dessa maneira, no presente trabalho, fornece matéria de amplo interesse histórico, visando com isso lançar alguma luz sobre a imensa fauna do Brasil e da Argentina. Baseando-se nos dados fornecidos por Pickering, o autor divulga dados curiosos a respeito da baía do Rio de Janeiro e adjacências, no ano de 1838. Segue-se uma lista contendo a diagnose de 82 espécimes de água doce, salobra e salgada, estudados e comparados com outros de várias procedências. Referindo-se ao Rio Negro, descreve o autor o aspeto da região patagônica, durante certo período de 1839, fazendo comentários a respeito de 7 espécies de peixes nela, encontradas.