199 research outputs found
Abstracts
No full textAbstracts included:P. J. Conrad. Metabolism of Arbutin by Selected Fungi.J. F. Schafer and H. L. Shands. Inheritance of Resistance of Barley to Covered Smut.J. F. Schafer, M. A. Ehrlich and H. G. Ehrlich. Ultrastructural Studies of Puccinia graminis Infection of Wheat Possessing Sr 11 Resistance.S. N. Postlethwait. A Developmental Study of the Maize Mutant Silkless (sk).S. N. Postlethwait and R. Mills. The Photographing of Serial Microscope Sections on 16 mm Movie Film.J. S. Coartney, W. R. Eisinger and D. J. Morre. An Analysis of Calcium-induced Inhibition of Cell Expansion.D. J. Morre, S. Kampmeyer and D. Hall. Preliminary Evidence for Secretion of Cell Dispersing Enzymes during Bean Petiole Abscission.D. Trumbull, S. Grove, D. J. Morre and S. Kampmeyer. Ultrastructural Changes during Secretion of a Polygalacturonase by the Fungus Fusarium moniliforme.W. L. Biehn. Physiology of Resistance of Glycine and Phaseolus Species to Fungi.
Molecular pedomorphism underlies craniofacial skeletal evolution in Antarctic notothenioid fishes
No full textAbstract Background Pedomorphism is the retention of ancestrally juvenile traits by adults in a descendant taxon. Despite its importance for evolutionary change, there are few examples of a molecular basis for this phenomenon. Notothenioids represent one of the best described species flocks among marine fishes, but their diversity is currently threatened by the rapidly changing Antarctic climate. Notothenioid evolutionary history is characterized by parallel radiations from a benthic ancestor to pelagic predators, which was accompanied by the appearance of several pedomorphic traits, including the reduction of skeletal mineralization that resulted in increased buoyancy. Results We compared craniofacial skeletal development in two pelagic notothenioids, Chaenocephalus aceratus and Pleuragramma antarcticum, to that in a benthic species, Notothenia coriiceps, and two outgroups, the threespine stickleback and the zebrafish. Relative to these other species, pelagic notothenioids exhibited a delay in pharyngeal bone development, which was associated with discrete heterochronic shifts in skeletal gene expression that were consistent with persistence of the chondrogenic program and a delay in the osteogenic program during larval development. Morphological analysis also revealed a bias toward the development of anterior and ventral elements of the notothenioid pharyngeal skeleton relative to dorsal and posterior elements. Conclusions Our data support the hypothesis that early shifts in the relative timing of craniofacial skeletal gene expression may have had a significant impact on the adaptive radiation of Antarctic notothenioids into pelagic habitats.</p
Different populations of the Antarctic notothen fish Trematomus scotti differ in key life history traits
No full textAntarctic notothenioid fish form an adaptive radiation that diversified in the Southern Ocean over the past 10 million years. The biology and life history of about a third of notothenioids have been studied, however, most frequently from a single location. Because species distributions can be discontinuous and depend on environmental conditions, local populations might differ substantially both genetically and phenotypically from distant conspecifics. Among notothenioids, the 15 Trematomus species diversified to occupy environments ranging from subsurface cryopelagic habitats to the deep sea and many Trematomus species likely have circumpolar distributions. Here, we analyzed life history traits of the notothen Trematomus scotti from two distinct geographic areas: Andvord Bay, a fjord on the Western Antarctic Peninsula, and the Weddell Sea at the edge of pack ice zones. These two populations inhabit drastically different areas with important differences in environmental conditions driven by latitude, temperature and ice cover, thus enabling the study of the effects of the environment on life history traits. We first found no evidence for substantial genetic heterogeneity based on the mitochondrial marker mt-co1. Fish in Andvord Bay, however, grew faster and reached longer sizes than congeners in the Weddell Sea. Furthermore, females in Andvord Bay had higher fecundity but produced smaller eggs compared to females in the Weddell Sea. Thus, these two populations of T. scotti displayed distinct life histories likely in response to local environmental conditions. Local life history traits such as these are crucial to consider to evaluate the vulnerability of a species to environmental change
Tubo gástrico isoperistáltico como tratamento paliativo do câncer esofágico irressecável.
No full textTrabalho de Conclusão de Curso - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Departamento de Clínica Cirúrgica, Curso de Medicina, Florianópolis, 199
Sex Differentiation and Long-Distance Gene Flow in the Elusive Antarctic Fish Aethotaxis mitopteryx
No full textUnderstanding population connectivity in the marine realm is crucial for conserving biodiversity, managing fisheries, and predicting species responses to environmental change. This is particularly important in Antarctic waters, where unique evolutionary histories and extreme conditions shape marine biodiversity. The longfin icedevil Aethotaxis mitopteryx is an elusive notothenioid fish endemic to Antarctic waters. To explore population connectivity in A. mitopteryx, we used RAD-seq to investigate the genetic differentiation of two populations, one from the Eastern Weddell Sea and the other from the Eastern Antarctic Peninsula, two regions of ecological relevance greatly impacted by climate change. Despite spatial separation, analyses revealed no significant genetic differentiation between the two populations, suggesting extensive gene flow. A pronounced genetic distinction was, however, observed between males and females. This differentiation was largely localized to a specific chromosome, implying a genetic sex determination system with males being the heterogametic sex. These findings contribute novel insights into the genetic structure of A. mitopteryx populations and expand our understanding of genetic mechanisms in Antarctic fish. This study provides a foundation for further investigations into the evolutionary and ecological implications of sex chromosome differentiation in extreme environments
Hormonal regulation of synthesis of yolk proteins and a larval serum protein (LSP2) in Drosophila
No full textApplication of a Combined Active Control and Fault Detection Scheme to an Active Composite Flexible Structure.
No full textIn this paper, the problem of increasing reliability of active control procedure is considered. Indeed, a design method of rejection perturbation in presence of potentially faults, on a flexible structure with integrated piezo-ceramics, is presented. The piezo-ceramics are used as actuators and sensors. A single unit based solution, which handles both control action and fault diagnosis is proposed. The algorithm uses H∞ optimization techniques. A full order model of the structure is first obtained via both finite-element (FE) approach and identification procedure. This model is then reduced in order to be used in our robust approach. By a suitable choice of weightings functions, the provided method is able to reject disturbance robustly and to estimate occurred faults. The case of sensors and actuators faults is discussed. The choice of weightings for diagnosis and control systems is also tackled. Finally, the effectiveness of this integrated method is confirmed by both simulation and experimental results
Complementary expression of the meiotic recombination marker <i>sycp3</i> and <i>cyp26a1</i> in developing gonads.
No full text<p>In bipotential gonads at 20 dpf (A,B: n=8), germ cells expressed the meiotic recombination marker <i>sycp3</i> (black arrowhead in A) in a non-overlapping pattern with <i>cyp26a1</i> expression, which was mostly restricted to the dorsal part of the gonad (revealing that <i>sycp3-</i>expressing cells did not express <i>cyp26a1</i> (red arrowhead in B). Expression of the meiotic marker <i>sycp3</i> was detected in bipotential gonads of all animals analyzed (A, n=8) suggesting that some germ cells entered meiosis in all juveniles regardless of their definitive sex. In differentiating testes at 26 dpf (C,D: n=2) and 29 dpf (G, H: n=2), islands of germ cells that expressed <i>sycp3</i> (black arrowheads in C, G) were found in an area in which RA was likely not degraded due to lack of <i>cyp26a1</i> expression (red arrowheads in D,H). In contrast, in differentiating ovaries at 26 dpf (E, F: n=2) and 29 dpf (I, J: n=2), <i>sycp3</i> was expressed in small germ cells (black arrowheads in E, I) that did not express <i>cyp26a1</i> (red arrowheads in F, J). The expression of <i>cyp26a1</i> was restricted to the ooplasm of oocytes that reached diplotene stage and entered in meiotic arrest (F,J). Scale bar: 0.1mm.</p
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