The role of olfaction throughout juvenile development: Functional adaptations in elasmobranchs

Seven elasmobranch species, a group known for their highly‐developed sense of smell, were examined for developmental changes in the number of olfactory lamellae, the size of the surface area of the sensory olfactory epithelium and the mass of both the olfactory rosettes (primary input to the CNS), and the olfactory bulbs. Within each species, juveniles possessed miniature versions of the adult olfactory organs, visually not distinguishable from these and without any obvious structural differences (e.g., with respect to the number of lamellae and the extent of secondary folding) between differently sized individuals. The size of the olfactory organs was positively correlated with body length and body mass, although few species showed proportional size scaling. In Aetobatus narinari and Aptychotrema rostrata, olfactory structures increased in proportion to body size. With respect to the growth of the olfactory bulb, all species showed allometric but not proportional growth. Olfaction may be of particular importance to juveniles in general, which are often subjected to heavy predation rates and fierce inter/intraspecific competition. Accordingly, it would be advantageous to possess a fully functional olfactory system early on in development. Slow growth rates of olfactory structures could then be attributed to a greater reliance on other sensory systems with increasing age or simply be regarded as maintaining an already optimized olfactory system. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Comparative phylogeography and population structure of European Betula species, with particular focus on B. pendula and B. pubescens

Aim  To compare the population genetic structures of the haplotype-sharing species Betula pendula and B. pubescens and to draw phylogeographic inferences using chloroplast DNA markers. In particular, we tested whether B. pendula and B. pubescens exhibited the same or different phylogeographic structures.
Location  Western Europe and Russia.
Methods  In this study we used both chloroplast DNA polymerase chain reaction-restriction fragment length polymorphism and microsatellites to genotype B. pendula , B. pubescens and, to a limited extent, B. nana , in 53 populations across Eurasia. A spatial amova ( samova ) was used to identify major clusters within each species.
Results  The low level of phylogeographic structure previously observed in B. pendula was confirmed, and the samova analysis retrieved only two major clusters. In contrast, seven clusters were observed in B. pubescens , although the overall level of population differentiation was similar to that of B. pendula .
Main conclusions  We detected a difference in the population genetic structure between the two species, despite extensive haplotype sharing. It is difficult to ascribe this finding to a single factor, but divergence in ecology between the two species may provide part of the explanation. For both species, the contribution of southern western populations to the recolonization after the Last Glacial Maximum seems to have been limited, and eastern and western European populations apparently had different histories.     

Living in fast‐flowing water: Morphology of the gastromyzophorous tadpole of the bufonid Rhinella quechua (R. veraguensis group)

We describe the bufonid gastromyzophorous tadpoles of Rhinella quechua from montane forest streams in Bolivia. Specimens were cleared and stained, and the external morphology, buccopharyngeal structures, and the musculoskeletal system were studied. These tadpoles show a combination of some traits common in Rhinella larvae (e.g., emarginate oral disc with large ventral gap in the marginal papillae, labial tooth row formula 2/3, prenarial ridge, two infralabial papillae, quadratoorbital commissure present, larval otic process absent, mm. mandibulolabialis superior, interhyoideus posterior, and diaphragmatopraecordialis absent, m. subarcualis rectus I composed of three slips), some traits apparently exclusive for the described species of the R. veraguensis group (e.g., second anterior labial tooth row complete, lingual papillae absent, adrostral cartilages present), and some traits that are shared with other gastromyzophorous tadpoles (e.g., enlarged oral disc, short and wide articular process of the palatoquadrate, several muscles inserting on the abdominal sucker). In the context of the substantial taxonomic and nomenclatural changes that the former genus Bufo has undergone, and despite the conspicuous morphological differences related to the presence of an abdominal sucker, the larval morphology of R. quechua supports including it in the genus Rhinella and placing it close to species of the R. veraguensis assemblage. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

Anchored and soluble gangliosides contribute to myelosupportivity of stromal cells

Stroma-mediated myelopoiesis depends upon growth factors and an appropriate intercellular microenvironment. Previous studies have demonstrated that gangliosides, produced by hepatic stromal cell types, are required for optimal myelosupportive function. Here, we compared the mielossuportive functions of a bone marrow stroma (S17) and skin fibroblasts (SF) regarding their ganglioside pattern of synthesis and shedding. The survival and proliferation of a myeloid precursor cell (FDC-P1) were used as reporter. Although the ganglioside synthesis of the two stromal cells was similar, their relative content and shedding were distinct. The ganglioside requirement for mielossuportive function was confirmed by the decreased proliferation of FDC-P1 cells in ganglioside synthesis-inhibited cultures and in presence of an antibody to GM3 ganglioside. The distinct mielossuportive activities of the S17 and SF stromata may be related to differences on plasma membrane ganglioside concentrations or to differences on the gangliosides shed and their subsequent uptake by myeloid cells, specially, GM3 ganglioside.     

Modifying Post-Operative Medical Care after EBV Implant May Reduce Pneumothorax Incidence

ObjectiveEndoscopic lung volume reduction (ELVR) with valves has been shown to improve COPD patients with severe emphysema. However, a major complication is pneumothoraces, occurring typically soon after valve implantation, with severe consequences if not managed promptly. Based on the knowledge that strain activity is related to a higher risk of pneumothoraces, we asked whether modifying post-operative medical care with the inclusion of strict short-term limitation of strain activity is associated with a lower incidence of pneumothorax.MethodsSeventy-two (72) emphysematous patients without collateral ventilation were treated with bronchial valves and included in the study. Thirty-two (32) patients received standard post-implantation medical management (Standard Medical Care (SMC)), and 40 patients received a modified medical care that included an additional bed rest for 48 hours and cough suppression, as needed (Modified Medical Care (MMC)).ResultsThe baseline characteristics were similar for the two groups, except there were more males in the SMC cohort. Overall, ten pneumothoraces occurred up to four days after ELVR, eight pneumothoraces in the SMC, and only two in the MMC cohorts (p=0.02). Complicated pneumothoraces and pneumothoraces after upper lobe treatment were significantly lower in MMC (p=0.02). Major clinical outcomes showed no significant differences between the two cohorts.ConclusionsIn conclusion, modifying post-operative medical care to include bed rest for 48 hours after ELVR and cough suppression, if needed, might reduce the incidence of pneumothoraces. Prospective randomized studies with larger numbers of well-matched patients are needed to confirm the data.     

THE DETERMINATION OF GENETIC COVARIANCES AND PREDICTION OF EVOLUTIONARY TRAJECTORIES BASED ON A GENETIC CORRELATION MATRIX

There is much interest in measuring selection, quantifying evolutionary constraints, and predicting evolutionary trajectories in natural populations. For these studies, genetic (co)variances among fitness traits play a central role. We explore the conditions that determine the sign of genetic covariances and demonstrate a critical role of selection in shaping genetic covariances. In addition, we show that genetic covariance matrices rather than genetic correlation matrices should be characterized and studied in order to infer genetic basis of population differentiation and/or to predict evolutionary trajectories.     

Dispersal of Amazonian Trees: Hydrochory in Swartzia polyphylla1

Hydrochory was investigated in the seeds of the Amazonian floodplain tree, Swartzia polyphylla, in which pods open on the tree to release one large seed. Seeds collected from beach drift along the Rio Negro showed a high percentage of floaters (82%). Yet most seeds sank following collection from: adult trees (89%), unflooded ground under adults (96%), and flooded ground under adults (86%). The specific gravity of the seeds was near that of water, 1.04 ± 0.03 for sinkers and 0.98 ± 0.02 for floaters. The ability to float was correlated directly with the volume of the air pocket between the two cotyledons, which varied from 5.6 to 20.5 percent of the total seed volume. In a long-term floatation test lasting 81 days, 45 percent of the seeds never floated, 33 percent always floated, and 22 percent first sank for one week and then floated for at least one month. Seeds that never floated eventually rotted, but not until days 63-73. Seeds that were floating at day 81, regardless of how long they had been floating, were placed on moistened filter paper for 18 days during which time 36 percent germinated, 45 percent rotted, and 19 percent did neither but remained viable. These results suggest that S. polyphylla achieves dimorphism in flotation of its seeds, some sinking and some floating, by producing seeds of continuous variation in specific gravity around a mean close to 1.00. Seeds that float can be dispersed long distances along river margins, while those that sink may be moved only marginally from the parent tree.