Seed arrival in tropical forest tree fall gaps.

Tree deaths open gaps in closed-canopy forests, which allow light to reach the forest floor and promote seed germination and seedling establishment. Gap dependence of regeneration is an important axis of life history variation among forest plant species, and many studies have evaluated how plant species differ in seedling and sapling performance in gaps. However, relatively little is known about how seed arrival in gaps compares with seed arrival in the understory, even though seed dispersal by wind and animals is expected to be altered in gaps. We documented seed arrival for the first seven years after gap formation in the moist tropical forests of Barro Colorado Island (BCI), Panama, and evaluated how the amount and functional composition of arriving seeds compared with understory sites. On average, in the first three years after gap formation, 72% fewer seeds arrived in gaps than in the understory (207 vs. 740 seeds x m(-2) x yr(-1)). The reduction in number of arriving seeds fell disproportionately on animal-dispersed species, which suffered an 86% reduction in total seed number, while wind-dispersed species experienced only a 47% reduction, and explosively dispersed species showed increased seed numbers arriving. The increase in explosively dispersed seeds consisted entirely of the seeds of several shrub species, a result consistent with greater in situ seed production by explosively dispersed shrubs that survived gap formation or recruited immediately thereafter. Lianas did relatively better in seed arrival into gaps than did trees, suffering less of a reduction in seed arrival compared with understory sites. This result could in large part be explained by the greater predominance of wind dispersal among lianas: there were no significant differences between lianas and trees when controlling for dispersal syndromes. Our results show that seed arrival in gaps is very different from seed arrival in the understory in both total seeds arriving and functional composition. Differential seed arrival in gaps will help to maintain wind-dispersed, explosively dispersed, and possibly other understory species in the community of plants that regenerate in gaps.

Direct and indirect landscape effects on Quercus ilex regeneration in heterogeneous environments.

Understanding how plant-animal interactions shape plant regeneration is traditionally examined at local scales. In contrast, landscape ecologists working at regional scales often have to infer the mechanisms underlying vegetation patterns. In this study, we empirically explored how landscape attributes (patch connectivity, size, shape, irradiance, slope, and elevation) influence biotic interactions in 1- and 2-year seedlings and saplings of Quercus ilex. We combined field data and GIS-based information under a set of five connectivity scenarios, presuming low, intermediate, and long-distance seed dispersal. Our study emphasizes that landscape, apart from its direct effects on plants, plays a key, albeit indirect, role in plant demography through its effects on seed dispersers and predators. Moreover, the effects of landscape on recruitment differed between plant life stages. One-year seedlings and saplings appear to depend more on plant-animal interactions, while 2-year seedlings depend more on irradiance. Differences in patch connectivity resulted in direct and indirect effects on biotic interactions, which, in turn, produced contrasting positive and negative effects on regeneration at different stages of the life cycle. While jays and wild boars seem crucial to all life stages and most of the connectivity scenarios, rodents and herbivores affected only 1-year seedlings and saplings, respectively, and only a few of the connectivity scenarios. By simultaneously including an ensemble of explanatory factors, our study emphasizes that regeneration depends on a set of key drivers, both abiotic (i.e. irradiance) and biotic (i.e. jays and wild boars), whose effects are greatly modulated by landscape traits.

High diversity of rabies viruses associated with insectivorous bats in Argentina: presence of several independent enzootics.

BACKGROUND: Rabies is a fatal infection of the central nervous system primarily transmitted by rabid animal bites. Rabies virus (RABV) circulates through two different epidemiological cycles: terrestrial and aerial, where dogs, foxes or skunks and bats, respectively, act as the most relevant reservoirs and/or vectors. It is widely accepted that insectivorous bats are not important vectors of RABV in Argentina despite the great diversity of bat species and the extensive Argentinean territory. METHODS: We studied the positivity rate of RABV detection in different areas of the country, and the antigenic and genetic diversity of 99 rabies virus (RABV) strains obtained from 14 species of insectivorous bats collected in Argentina between 1991 and 2008. RESULTS: Based on the analysis of bats received for RABV analysis by the National Rabies system of surveillance, the positivity rate of RABV in insectivorous bats ranged from 3.1 to 5.4%, depending on the geographic location. The findings were distributed among an extensive area of the Argentinean territory. The 99 strains of insectivorous bat-related sequences were divided into six distinct lineages associated with Tadarida brasiliensis, Myotis spp, Eptesicus spp, Histiotus montanus, Lasiurus blosseviilli and Lasiurus cinereus. Comparison with RABV sequences obtained from insectivorous bats of the Americas revealed co-circulation of similar genetic variants in several countries. Finally, inter-species transmission, mostly related with Lasiurus species, was demonstrated in 11.8% of the samples. CONCLUSIONS: This study demonstrates the presence of several independent enzootics of rabies in insectivorous bats of Argentina. This information is relevant to identify potential areas at risk for human and animal infection.

Púrpura de Schõnlein- Henoch en adultos / Henoch-Schõnlein purpura in adults

La púrpura de Schõnlein-Henoch es una vasculitis sistémica mediada por inmunoglobulina A, caracterizada clínicamente por púrpura palpable, dolor abdominal, artralgias y hematuria o proteinuria en el laboratorio. La inmunofluorescencia directa de las lesiones cutáneas, así como la del riñón, revelan la presencia de depósitos perivasculares de este anticuerpo, dato de valor para confirmar el diagnóstico. Se presentan cinco pacientes adultos con PSH, insuficiencia renal aguda y neoplasias malignas en tres de ellos.

Henoch-Schönlein Purpura is a systemic vasculitis mediated by Ig A, clinically characterizedby non-thrombocytopenic palpable purpura, abdominal pain, arthritis and proteinuria orhematuria. Histologically, it is characterized by deposition of immunoglobulin A in the skinand kidneys, being these features essential for the diagnosis. We report five adult patientswith Henoch-Schönlein purpura with acute kidney failure, and malignant neoplasms onthree of them.

Púrpura de Sch§nlein- Henoch en adultos / Henoch-Sch§nlein purpura in adults

La púrpura de Sch§nlein-Henoch es una vasculitis sistémica mediada por inmunoglobulina A, caracterizada clínicamente por púrpura palpable, dolor abdominal, artralgias y hematuria o proteinuria en el laboratorio. La inmunofluorescencia directa de las lesiones cutáneas, así como la del riñón, revelan la presencia de depósitos perivasculares de este anticuerpo, dato de valor para confirmar el diagnóstico. Se presentan cinco pacientes adultos con PSH, insuficiencia renal aguda y neoplasias malignas en tres de ellos. (AU)

Henoch-Sch÷nlein Purpura is a systemic vasculitis mediated by Ig A, clinically characterizedby non-thrombocytopenic palpable purpura, abdominal pain, arthritis and proteinuria orhematuria. Histologically, it is characterized by deposition of immunoglobulin A in the skinand kidneys, being these features essential for the diagnosis. We report five adult patientswith Henoch-Sch÷nlein purpura with acute kidney failure, and malignant neoplasms onthree of them.(AU)

Effectiveness of rodents as local seed dispersers of Holm oaks.

In this study we assessed the effectiveness of rodents as dispersers of Quercus ilex in a patchy landscape in southeastern Spain. We experimentally followed the fates of 3,200 marked and weighed acorns from dispersal through the time of seedling emergence over three years. Rodents handled about 99% of acorns, and dispersed 67% and cached 7.4% of the dispersed acorns. Most caches were recovered and consumed, and only 1.3% of the original experimental acorns were found alive in caches the following spring. Dispersal distances were short (mean = 356.2 cm, median = 157 cm) and strongly right-skewed. Heavier acorns were dispersed further and were more likely to be cached and survive than lighter acorns. All caches were in litter or soil, and each contained a single acorn. Rodents moved acorns nonrandomly, mostly to oaks and pines. Most surviving acorns were either in oaks, a poor microhabitat for oak recruitment, or shrubs, a suitable microhabitat for oak recruitment. Our results suggest that rodents, by burying a relatively high proportion of acorns singly in shrubs and pines, act as moderately effective dispersers of Q. ilex. Nonetheless, this dispersal comes at a very heavy cost.