Nonlesions, misdiagnoses, missed diagnoses, and other interpretive challenges in fish histopathology studies: a guide for investigators, authors, reviewers, and readers.

Differentiating salient histopathologic changes from normal anatomic features or tissue artifacts can be decidedly challenging, especially for the novice fish pathologist. As a consequence, findings of questionable accuracy may be reported inadvertently, and the potential negative impacts of publishing inaccurate histopathologic interpretations are not always fully appreciated. The objectives of this article are to illustrate a number of specific morphologic findings in commonly examined fish tissues (e.g., gills, liver, kidney, and gonads) that are frequently either misdiagnosed or underdiagnosed, and to address related issues involving the interpretation of histopathologic data. To enhance the utility of this article as a guide, photomicrographs of normal and abnormal specimens are presented. General recommendations for generating and publishing results from histopathology studies are additionally provided. It is hoped that the furnished information will be a useful resource for manuscript generation, by helping authors, reviewers, and readers to critically assess fish histopathologic data.

Historia de un hecho regional canónico : el paso de los Andes

Desde el concepto de canon como el modelo impuesto por un grupo de poder, el presente trabajo analiza la canonización de la figura sanmartiniana en el cruce de los Andes, según relatos de autores de la clase dirigente. En los cuales se compara este personaje con Napoleón, Aníbal, Alejandro Magno y otras significativas figuras de la tradición occidental. Tres narraciones edifican la imagen de un héroe romántico, luchador a favor de la libertad y protector de los pueblos que libera. San Martín como paladín democrático frente a la tiranía despótica de los españoles, aparece en el relato de Gerónimo Espejo “El paso de los Andes". Este rico trabajo de prolijo historiador pondera la hazaña por sobre las de Napoleón y Aníbal. Bartolomé Mitre en su “Historia de San Martín", enfoca al héroe como paladín de unidad americana en la causa de la independencia, con una maestría superior a los cruces clásicos de Napoleón y Aníbal, parangonándolo con el de Bolívar en los Andes ecuatorianos. Ricardo Rojas en El santo de la espada fabrica una imagen religiosa de San Martín y lo iguala a héroes cristianos como Parsifal, Lohengrin y el Cid Campeador. El parangón con Napoleón. Aníbal y Alejandro Magno, se ve apoyado por la iconografía argentina de la época. La estatua más popular de San Martín repite la pose del retrato de Napoleón por David. Este, a su vez, está inspirado en mayólicas de Alejandro que lo representan en similar postura. Así, la imagen del héroe argentino en su cruce de los Andes se inserta con éxito en la tradición occidental.

Seed Dispersal Spectrum of Woody Species in South Ecuadorian Dry Forests: Environmental Correlates and the Effect of Considering Species Abundance

This study examines the seed dispersal spectrum of the tropical dry forests of Southern Ecuador, in an effort to contribute to the knowledge of the complex dynamics of tropical dry forests. Seed dispersal spectrum was described for a total number of 160 species. Relationships of dispersal syndromes with plant growth form and climatic seasonality were explored. For a subset of 97 species, we determined whether dispersal spectrum changes when species abundance, in addition to species number, is taken into account. The same subset was used to relate dispersal syndromes with the environmental conditions. Zoochorous species dominated in the studied community. When considering the individual abundance of each species, however, anemochory was the prevalent dispersal syndrome. We found a significant difference in the frequency of dispersal syndromes among plant growth forms, with epizoochory only occurring in shrub species. The dispersal spectrum was dependent on climatic seasonality. The largest proportion of anemochorous species fructified during the dry season, while zoochorous diaspores dominated during the rainy season. A fourth-corner analysis indicated that the seed dispersal spectrum of Southern Ecuador dry forests is controlled by environmental conditions such as annual precipitation, annual temperature range or topography. Our results suggest that spatio-temporal changes in the environmental conditions may affect important ecological processes for dispersal. Thus, the predominance of one syndrome or another may depend on the spatial variation of environmental conditions.

Climate and grazing control nurse effects in an Ecuadorian dry shrubby community

Positive plant interactions have strong effects on plant diversity at several spatial scales, expanding species distribution under stressful conditions. We evaluated the joint effect of climate and grazing on the nurse effect of Croton wagneri, by monitoring several community attributes at two spatial scales: microhabitat and plant community. Two very close locations that only differed in grazing intensity were surveyed in an Ecuadorian dry scrub ecosystem. At each location, two 30 × 30-m plots were established at four altitudinal levels (1500, 2630, 1959 and 2100 m asl) and 40 microsites were surveyed in each plot. Croton wagneri acted as community hubs, increasing species richness and plant cover at both scales. Beneath nurses mean richness and cover values were 3.4 and 21.9%, and in open areas 2.3 and 4.5%, respectively. Magnitude of nurse effect was dependent on climate and grazing conditions. In ungrazed locations, cover increased and diversity reduced with altitude, while grazed locations showed the opposite trend. In ungrazed plots the interactions shifted from positive to negative with altitude, in grazed locations interactions remained positive. We conclude that the nurse effect is a key mechanism regulating community properties not only at microsite but also at the entire community scale.

Fauna hawaiiensis; being the land-fauna of the Hawaiian islands. by various authors, 1899-1913.

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Fauna hawaiiensis; being the land-fauna of the Hawaiian islands. by various authors, 1899-1913.

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Fauna hawaiiensis; being the land-fauna of the Hawaiian islands. by various authors, 1899-1913.

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Life-like forms in meteorites and the problems of environmental control on the morphology of fossil and recent protobionta / consulting editor, Bartholomew Nagy ; conference chairman, J. Joseph Lynch ; authors, E. Anders [et al.]

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