Phylogeny and diversification history of the large Neotropical genus Philodendron (Araceae): Accelerated speciation in a lineage dominated by epiphytes.

PREMISE OF THE STUDY: Philodendron is a large genus of ~560 species and among the most conspicuous epiphytic components of Neotropical forests, yet its phylogenetic relationships, timing of divergence, and diversification history have remained unclear. We present a comprehensive phylogenetic study for Philodendron and investigate its diversification, including divergence-time estimates and diversification rate shift analyses. METHODS: We performed the largest phylogenetic reconstruction for Philodendron to date, including 125 taxa with a combined dataset of three plastid regions (petD, rpl16, and trnK/matK). We estimated divergence times using Bayesian evolutionary analysis sampling trees and inferred shifts in diversification rates using Bayesian analysis of macroevolutionary mixtures. KEY RESULTS: We found that Philodendron, its three subgenera, and the closely related genus Adelonema are monophyletic. Within Philodendron subgenus Philodendron, 12 statistically well-supported clades are recognized. The genus Philodendron originated ~25 mya and a diversification rate upshift was detected at the origin of subgenus Philodendron ~12 mya. CONCLUSIONS: Philodendron is a species-rich Neotropical lineage that diverged from Adelonema during the late Oligocene. Within Philodendron, the three subgenera currently accepted are recovered in two lineages: one contains the subgenera Meconostigma and Pteromischum and the other contains subgenus Philodendron. The lineage containing subgenera Meconostigma and Pteromischum underwent a consistent diversification rate. By contrast, a diversification rate upshift occurred within subgenus Philodendron ~12 mya. This diversification rate upshift is associated with the species radiation of the most speciose subgenus within Philodendron. The sections accepted within subgenus Philodendron are not congruent with the clades recovered. Instead, the clades are geographically defined.

Development of Nerve Fibre Diameter in Young Infants With Hirschsprung Disease.

OBJECTIVES: Finding thickened nerve fibres is one of the key elements in the diagnosis of Hirschsprung disease (HD); however, its value at different ages remains uncertain. Nerve fibre diameters <40 µm can be observed in infants younger than 8 weeks, despite the presence of HD. The aim of this study was to identify a change in maximum nerve fibre diameter in HD patients, measured before and after 8 weeks of age. METHODS: Nerve fibre diameter was retrospectively evaluated in tissue of 20 infants treated for definite HD. Rectal suction biopsies (RSBs) obtained within the first 8 weeks of life (T1) and resected bowel obtained during primary surgery at an average of 24.7 weeks (T2), were assessed. The 2 thickest nerve fibre diameter recordings at T1 and T2 were compared in each subject, to examine changes in nerve trunk diameter with increasing age. RESULTS: In 13 cases (65%), nerve fibre diameters were ≥40 µm at T1 and T2. Six subjects (30%) had nerve trunk diameters <40 µm at T1; however, they experienced diameter increases to ≥40 µm by T2. Thus, at T2, 19 subjects (95%) had diameter recordings ≥40 µm. Nerve fibre diameter in the remaining case (5%) stayed consistent at <40 µm at T1 and T2, despite the presence of HD. CONCLUSIONS: After the first 8 weeks of life, nerve fibre measurements appear to be associated with HD. Measuring the 2 thickest nerve fibres can support typical HD diagnosis criteria beyond 8 weeks of age, but is not superior to histopathological confirmation of aganglionosis.

Grayanotoxin I Intoxication in Pet Pigs.

Contaminated honey is a common cause of grayanotoxin intoxication in humans. Intoxication of animals, especially cattle, is usually due to ingestion of plants of the Ericaceae family, such as Rhododendron. Here, we report the ingestion of Pieris japonica as the cause of grayanotoxin I intoxication in 2 miniature pigs that were kept as pets. The pigs showed sudden onset of pale oral mucosa, tachycardia, tachypnea, hypersalivation, tremor, and ataxia that progressed to lateral recumbency. The pathological examination of one pig revealed no specific indications for intoxication except for the finding of plant material of Pieris japonica in the intestine. Grayanotoxin I was identified in the ingested plant, gastric content, blood, liver, bile, kidney, urine, lung, and skeletal muscle via HPLC-MS/MS. Grayanotoxin I should be considered as a differential etiological diagnosis in pigs with unspecific signs and discovery of ingested plant material as the only indication in the pathologic examination.

Liver parenchyma at the site of hypodense parafissural pseudolesion contains increased collagen.

PURPOSE: To identify a histological substrate explaining the hypodense pseudolesion in the liver at the right side of the falciform ligament and the correlation with CT radiodensity. MATERIALS AND METHODS: Tissue specimens were obtained from the right (pseudolesion) and left (control) side of the falciform ligament at the level of the left portal vein, in deceased adults during autopsy. Radiodensity was measured at the same locations at CT. Digital image analysis determined the amount of collagen and fat in histological sections, and the number of portal triads and central veins were counted. Glycogen content was visually assessed by the area percentage of the histological section. RESULTS: Specimens from 17 patients showed a 39% increase in collagen for the site of the pseudolesion compared to the contralateral side (p = 0.08). No significant differences were found for the amount of fat, glycogen, portal triads, or central veins. In one patient a pseudolesion was visible on CT, and this contained 52% more collagen than the control side. CONCLUSION: The pseudolesion at the right parafissural side in the liver contains more collagen compared to the control left side, while there is no difference in fat or glycogen content or number of portal and hepatic veins. Collagen may be the cause of the pseudolesion.

Predictive value of nerve trunk size in the neonate.

PURPOSE: The diagnosis of Hirschsprung's disease (HD) remains challenging. The identification of ganglion cells is difficult and acetycholine esterase (AChE) staining can be subject to a great variability, particularly in the neonatal period (<8 weeks). Nerve trunks greater than 40 µm are considered to be predictive for HD. The aim of this study was to evaluate the usefulness of measuring nerve trunk size in the newborn with HD. METHODS: Out of 292 biopsies 69 could be reanalyzed by three independent researchers. 40 µm was used as cutoff point for nerve trunk size. They were subdivided into three groups: (a) diagnosis of HD certain at the first biopsy, (b) no HD and (c) diagnosis of HD remains doubtful and re-biopsy taken. RESULTS: In 87 % of group A nerve trunk size was ≥ 40 µm (SD 13.8). In 84 % of group B trunk size was < 40 µm (SD 16.2). In group C only 60 % of the patients showed a positive correlation between final diagnosis and nerve trunk size. CONCLUSION: Using 40 µm as the cutoff point gave 13 % false-negative and 16 % false-positive cases. Measurement of the nerve trunk in the neonatal period does not seem to be a reliable method for detecting HD.

Conservation of epiphyte diversity in an Andean landscape transformed by human land use.

Epiphytes are diverse and important elements of tropical forests, but as canopy-dwelling organisms, they are highly vulnerable to deforestation. To assess the effect of deforestation on epiphyte diversity and the potential for epiphyte conservation in anthropogenically transformed habitats, we surveyed the epiphytic vegetation of an Ecuadorian cloud forest reserve and its surroundings. Our study was located on the western slopes of the Andes, a global center of biodiversity. We sampled vascular epiphytes of 110 study plots in a continuous primary forest; 14 primary forest fragments; isolated remnant trees in young, middle-aged, and old pastures; and young and old secondary forests. It is the first study to include all relevant types of habitat transformation at a single study site and to compare epiphyte diversity at different temporal stages of fragmentation. Epiphyte diversity was highest in continuous primary forest, followed by forest fragments and isolated remnant trees, and lowest in young secondary forests. Spatial parameters of habitat transformation, such as fragment area, distance to the continuous primary forest, or distance to the forest edge from inside the forest, had no significant effect on epiphyte diversity. Hence, the influence of dispersal limitations appeared to be negligible or appeared to operate only over very short distances, whereas microclimatic edge effects acted only in the case of completely isolated trees, but not in larger forest fragments. Epiphyte diversity increased considerably with age of secondary forests, but species assemblages on isolated remnant trees were impoverished distinctly with time since isolation. Thus, isolated trees may serve for recolonization of secondary forests, but only for a relatively short time. We therefore suggest that the conservation of even small patches of primary forest within agricultural landscape matrices is essential for the long-term maintenance of the high epiphyte diversity in tropical cloud forests.