Telocytes and stem cells in limbus and uvea of mouse eye

The potential of stem cell (SC) therapies for eye diseases is well‐recognized. However, the results remain only encouraging as little is known about the mechanisms responsible for eye renewal, regeneration and/or repair. Therefore, it is critical to gain knowledge about the specific tissue environment (niches) where the stem/progenitor cells reside in eye. A new type of interstitial cell–telocyte (TC) ( www.telocytes.com ) was recently identified by electron microscopy (EM). TCs have very long (tens of micrometres) and thin (below 200 nm) prolongations named telopodes (Tp) that form heterocellular networks in which SCs are embedded. We found TCs by EM and electron tomography in sclera, limbus and uvea of the mouse eye. Furthermore, EM showed that SCs were present in the anterior layer of the iris and limbus. Adhaerens and gap junctions were found to connect TCs within a network in uvea and sclera. Nanocontacts (electron‐dense structures) were observed between TCs and other cells: SCs, melanocytes, nerve endings and macrophages. These intercellular ‘feet’ bridged the intercellular clefts (about 10 nm wide). Moreover, exosomes (extracellular vesicles with a diameter up to 100 nm) were delivered by TCs to other cells of the iris stroma. The ultrastructural nanocontacts of TCs with SCs and the TCs paracrine influence via exosomes in the epithelial and stromal SC niches suggest an important participation of TCs in eye regeneration.     

Diversity and distribution of amphibians in Romania

Nineteen species of amphibians inhabit Romania, 9 of which reach their range limit on this territory. Based on published occurrence reports, museum collections and our own data we compiled a national database of amphibian occurrences. We georeferenced 26779 amphibian species occurrences, and performed an analysis of their spatial patterns, checking for hotspots and patterns of species richness. The results of spatial statistic analyses supported the idea of a biased sampling for Romania, with clear hotspots of increased sampling efforts. The sampling effort is biased towards species with high detectability, protected areas, and large cities. Future sampling efforts should be focused mostly on species with a high rarity score in order to accurately map their range. Our results are an important step in achieving the long-term goals of increasing the efficiency of conservation efforts and evaluating the species range shifts under climate change scenarios.     

Underestimated ranges and overlooked refuges from amphibian chytridiomycosis

Aim

Accurately documenting and predicting declines and shifts in species’ distributions is fundamental for implementing effective conservation strategies and directing future research; species distribution models (SDM) have become a powerful tool for such work. Nevertheless, much of the data used to create these models are opportunistic and often violate some of their basic assumptions. We use amphibian declines and extinctions linked to the fungus Batrachochytrium dendrobatidis (Bd) to examine how sampling biases in data collection can affect what we know of this disease and its effect on amphibians in the wild.

Location

Queensland, Australia.

Methods

We developed a distribution model for Bd incorporating known locality records for Bd and a subset of climatic variables that should correctly characterize its distribution. We tested this (original) model with additional surveys, recorded new Bd observations in novel environments and reran the distribution model. We then investigated the difference between the original and new models, and used frog abundance and infection status data from two of these new localities to look at the susceptibility of the torrent frog Litoria nannotis to chytridiomycosis.

Results

While largely correct, the original SDM underestimated the distribution of Bd; sampling in ‘unsuitable’ drier environments discovered abundant populations of susceptible frogs with pathogen prevalences of up to 100%. The validation surveys further uncovered a new population of the frog Litoria lorica coexisting with the pathogen; this species was previously believed to be an extinct rain forest endemic.

Main conclusion

Our results indicate that SDMs constructed using opportunistically collected data can be biased if species are not at equilibrium with their environment or because environmental gradients have not been adequately sampled. For disease ecology, the better estimations of pathogen distribution may lead to the discovery of new populations persisting at the edge of their range, which has important implications for the conservation of species threatened by chytridiomycosis.

     

Vaccine-related mumps infections in Thailand and the identification of a novel mutation in the mumps fusion protein

An outbreak of nine cases of mumps was reported from a total of 97 vaccinated nursing students at two medical colleges in Thailand in 2010, 16–26 days after administration of MMR vaccine containing the L-Zagreb mumps strain. Symptoms ranged in severity from fever and parotid swelling to orchitis. Clinical samples were obtained from seven patients and three were suitable for further study.Sequencing confirmed that the SH gene of the mumps virus in the unpassaged clinical specimens was identical to the L-Zagreb SH gene in the vaccine. Further analysis of the viral genome identified nucleotide position 5170 as a novel mutation which corresponds to an amino acid change in the fusion protein.This study provides another virologically confirmed example of mumps resulting from the L-Zagreb vaccine strain.     

Reconstruction of Microbial Haplotypes by Integration of Statistical and Physical Linkage in Scaffolding

DNA sequencing technologies provide unprecedented opportunities to analyze within-host evolution of microorganism populations. Often, within-host populations are analyzed via pooled sequencing of the population, which contains multiple individuals or “haplotypes.” However, current next-generation sequencing instruments, in conjunction with single-molecule barcoded linked-reads, cannot distinguish long haplotypes directly. Computational reconstruction of haplotypes from pooled sequencing has been attempted in virology, bacterial genomics, metagenomics, and human genetics, using algorithms based on either cross-host genetic sharing or within-host genomic reads. Here, we describe PoolHapX, a flexible computational approach that integrates information from both genetic sharing and genomic sequencing. We demonstrated that PoolHapX outperforms state-of-the-art tools tailored to specific organismal systems, and is robust to within-host evolution. Importantly, together with barcoded linked-reads, PoolHapX can infer whole-chromosome-scale haplotypes from 50 pools each containing 12 different haplotypes. By analyzing real data, we uncovered dynamic variations in the evolutionary processes of within-patient HIV populations previously unobserved in single position-based analysis.     

Role of emergent and submerged vegetation and algal communities on nutrient retention and management in a subtropical urban stormwater treatment wetland

A 4.6-ha urban stormwater treatment wetland complex in southwest Florida has been investigated for several years to understand its nutrient retention dynamics. This study investigates the role of aquatic vegetation, both submerged vegetation (such as benthic macrophytic and algal communities) and emergent plant communities, on changes in nutrient fluxes through the wetlands. Gross and net primary productivity of water column communities and net primary productivity of emergent macrophytes were used to estimate nutrient fluxes through vegetation in these wetlands using biannual biomass, nutrient concentrations of plant material, and areal coverage data. Emergent macrophyte net primary productivity was estimated as the difference between the increase of productivity during the wet season and the loss during the dry season which, in turn, suggested approximately 0.11g-N m^??2 y^??1 and 0.09g-P m^??2 yr^??2 being removed, primarily from the soil, by emergent vegetation. Water column primary productivity accounted for a much larger flux of nutrients with approximately 39.6g-N m^??2 yr^??1 and 2.4g-P m^??2 yr^??1 retained in algal communities. These fluxes, combined with measurements in parallel studies, allowed us to develop preliminary nutrient budgets for these wetlands and identify gaps, or missing fluxes, in our models for these wetlands. The results further validated previous findings that suggested that there are large inputs of nitrogen (up to 62.3g-N m^??2 yr^??1) that are not accounted for by the pumped inflow. Additionally, management suggestions are provided to improve water quality by identifying vegetative species that are most effective at retaining nutrients.