Comprehensive Expression of Wnt Signaling Pathway Genes during Development and Maturation of the Mouse Cochlea

Background

In the inner ear Wnt signaling is necessary for proliferation, cell fate determination, growth of the cochlear duct, polarized orientation of stereociliary bundles, differentiation of the periotic mesenchyme, and homeostasis of the stria vascularis. In neonatal tissue Wnt signaling can drive proliferation of cells in the sensory region, suggesting that Wnt signaling could be used to regenerate the sensory epithelium in the damaged adult inner ear. Manipulation of Wnt signaling for regeneration will require an understanding of the dynamics of Wnt pathway gene expression in the ear. We present a comprehensive screen for 84 Wnt signaling related genes across four developmental and postnatal time points.

Results

We identified 72 Wnt related genes expressed in the inner ear on embryonic day (E) 12.5, postnatal day (P) 0, P6 and P30. These genes included secreted Wnts, Wnt antagonists, intracellular components of canonical signaling and components of non-canonical signaling/planar cell polarity.

Conclusion

A large number of Wnt signaling molecules were dynamically expressed during cochlear development and in the early postnatal period, suggesting complex regulation of Wnt transduction. The data revealed several potential key regulators for further study.     

Spouse-to-Spouse Transmission and Evolution of Hypervariable Region 1 and 5’ Untranslated Region of Hepatitis C Virus Analyzed by Next-Generation Sequencing

Hepatitis C virus (HCV) transmission between spouses remains poorly characterized, largely due to the limited availability of samples from the early stage of infection, as well as methodological constraints. A fifty-eight year-old male developed acute hepatitis C infection and his 53-year old spouse has been HCV-positive for over 10 years. Serum samples were collected from both at the time of acute hepatitis C diagnosis in male (baseline) and then at 9 and 13 months. Hypervariable region 1 (HVR1) and 5’ untranslated region (5’UTR) sequences were amplified and subjected to next generation sequencing (NGS) using a pyrosequencing platform. Genetic variants were inferred by Shorah reconstruction method and compared by phylogenetic and sequence diversity analysis. As the sequencing error of the procedure was previously determined to be ≤ 1.5%, the analysis was conducted with and without the 1.5% cut-off with regard to the frequency of variants. No identical HVR1 variants were identified in spouses at baseline and follow-up samples regardless whether the cut-off was applied or not. However, there was high similarity (98.3%) between a minor baseline donor variant (1.7% frequency) and the most abundant baseline recipient variant (62.5% frequency). Furthermore, donor and recipient strains clustered together when compared to 10 control subjects from the same area and infected with the same HCV subtype. There was an increase in HVR1 complexity (number of genetic variants) over time in both spouses. In contrast, the 5''UTR region was stable and of low complexity throughout the study. In conclusion, intrafamilial HCV transmission may be established by a very minor variant and investigation of this phenomenon requires high-sensitivity assays, such as NGS.     

The lack of vertical migration in Daphnia: the effect of homogenously distributed food

Neither Daphnia hyalina, Daphnia cristata, nor Daphnia cucullata vertically migrated in Lake Mikoajskie and Lake Majcz. We suggest that even under strong fish predation pressure there is no reason to migrate when seston is relatively homogenously distributed throughout the water column.     

COLONY AND HABITAT SELECTION OF SIX KELP GULL LARUS DOMINICANUS COLONIES IN SOUTH AFRICA

Kelp Gulls nested in six colonies on rocky islands, sand and rock cliffs, sand dunes and on a sand, gravel island in a salt lake. The colony sites selected were different from the surrounding areas and were generally inaccessible to ground predators. Kelp Gulls nested in a wide variety of habitats. Within colonies, the gulls did not nest randomly with respect to habitats but preferred to nest on flat, stable areas with some cover (either rocks or vegetation). They generally avoided heavily vegetated areas, areas devoid of vegetation and areas with steep slopes. Their specific habitat choices relate to predation and cannibalism pressures. Intermediate cover provides adequate protection for chicks while allowing for increased visibility and open escape routes for parents. Nearest neighbour distances were similar among colonies and habitats, indicating strong social attraction.     

Structure of the plantar sweat glands of the Bank vole Clethrionomys glareolus

The plantar pads of the hind feet of 15 male and female, young and old Clethrionomys glareolus (Rodentia–family Muridae) were examined for the presence of tubular glands. Groups of eight or nine coiled glands were found in all of the 11 plantar pads. The secretory portion of the gland lies deep in the fatty hypodermis and communicates with the plantar surface by a coiled duct whose lining cells merge with those of the stratum basale of the undersurface of the foot. Groups of shallow depressions mark the site of the duct openings. They are not associated with any hairs.
Although light microscopy shows only one cell type, electron microscopy reveals two morphologically different cell types. Neither conform directly to the light and dark secretory cells of the human sweat glands although similarities exist. Myoepithelial cells surround the secretory cells, but do not appear to be present around the duct cells.     

Accumulation of phenolics and growth rate of barley seedlings (Hordeum vulgare L.)

Accumulation of phenolics in barley seedlings was examined in relation to elongation; the seedlings were cultivated at 5 °C or 26 °C in light or in darkness. It was found that a higher accumulation of phenolics (mainly saponarin) was accompanied by slower elongation. This relation was repeatedly observed regardless of whether growth retardation or stimulation was obtained by light and temperature conditions of growth or treatment with CCO orp-fluorophenylalanine (p-FPA), respectively. It is proposed that PAL and peroxidase activities are responsible for maintaining the level of phenolics in seedlings. These enzyme activities are differently influenced by temperature conditions of growth. It is also suggested that accumulation of saponarin may lead to slowing down the growth by stimulating IAA oxidase and lowering the auxin level in the tissues. Thus, phenolics may belong to the factors through which environmental conditions influence elongation of seedlings.     

Convenient Sampling of Air Bacteria in Operating Rooms

A convenient arrangement for sampling air bacteria in operating rooms with a slit sampler (the Fort Detrick sampler) is described. Its purpose is to contribute as far as possible to the convenience of the surgical staff and thereby to the safety of the patient. It has the advantages of recording minute-to-minute changes in bacterial air count; it is unobtrusive and yet can be continually observed by a technician; it is not noisy and avoids the dangers of explosion and static electricity; it is inexpensive, and parts are easily replaced; and finally it provides a means of keeping permanent photographic records of bacterial counts. Results of a preliminary trial of this method appeared to be satisfactory.     

The quantitative basis for the redistribution of immobile bacterial lipoproteins to division septa

The spatial localisation of proteins is critical for most cellular function. In bacteria, this is typically achieved through capture by established landmark proteins. However, this requires that the protein is diffusive on the appropriate timescale. It is therefore unknown how the localisation of effectively immobile proteins is achieved. Here, we investigate the localisation to the division site of the slowly diffusing lipoprotein Pal, which anchors the outer membrane to the cell wall of Gram-negative bacteria. While the proton motive force-linked TolQRAB system is known to be required for this repositioning, the underlying mechanism is unresolved, especially given the very low mobility of Pal. We present a quantitative, mathematical model for Pal relocalisation in which dissociation of TolB-Pal complexes, powered by the proton motive force across the inner membrane, leads to the net transport of Pal along the outer membrane and its deposition at the division septum. We fit the model to experimental measurements of protein mobility and successfully test its predictions experimentally against mutant phenotypes. Our model not only explains a key aspect of cell division in Gram-negative bacteria, but also presents a physical mechanism for the transport of low-mobility proteins that may be applicable to multi-membrane organelles, such as mitochondria and chloroplasts.