The importance of stem cell engineering in head and neck oncology

Head and neck squamous cell carcinoma is the sixth leading cause of cancer worldwide. The most common risk factors are carcinogens (tobacco, alcohol), and infection of the human papilloma virus. Surgery is still considered as the treatment of choice in case of head and neck cancer, followed by a reconstructive surgery to enhance the quality of life in the patients. However, the widespread use of artificial implants does not provide appropriate physiological activities and often cannot act as a long-term solution for the patients. Here we review the applicability of multiple stem cell types for tissue engineering of cartilage, trachea, vocal folds and nerves for head and neck injuries. The ability of the cells to self-renew and maintain their pluripotency state makes them an attractive tool in tissue engineering.     

Macroevolution of perfume signalling in orchid bees

Theory predicts that both stabilising selection and diversifying selection jointly contribute to the evolution of sexual signalling traits by (1) maintaining the integrity of communication signals within species and (2) promoting the diversification of traits among lineages. However, for many important signalling traits, little is known about whether these dynamics translate into predictable macroevolutionary signatures. Here, we test for macroevolutionary patterns consistent with sexual signalling theory in the perfume signals of neotropical orchid bees, a group well studied for their chemical sexual communication. Our results revealed both high species‐specificity and elevated rates of evolution in perfume signals compared to nonsignalling traits. Perfume complexity was correlated with the number of congeners in a species’ range, suggesting that perfume evolution may be tied to the remarkably high number of orchid bee species coexisting together in some neotropical communities. Finally, sister‐pair comparisons were consistent with both rapid divergence at speciation and character displacement upon secondary contact. Together, our results provide new insight into the macroevolution of sexual signalling in insects.     

Structures of single‐layer β‐sheet proteins evolved from β‐hairpin repeats

Free‐standing single‐layer β‐sheets are extremely rare in naturally occurring proteins, even though β‐sheet motifs are ubiquitous. Here we report the crystal structures of three homologous, single‐layer, anti‐parallel β‐sheet proteins, comprised of three or four twisted β‐hairpin repeats. The structures reveal that, in addition to the hydrogen bond network characteristic of β‐sheets, additional hydrophobic interactions mediated by small clusters of residues adjacent to the turns likely play a significant role in the structural stability and compensate for the lack of a compact hydrophobic core. These structures enabled identification of a family of secreted proteins that are broadly distributed in bacteria from the human gut microbiome and are putatively involved in the metabolism of complex carbohydrates. A conserved surface patch, rich in solvent‐exposed tyrosine residues, was identified on the concave surface of the β‐sheet. These new modular single‐layer β‐sheet proteins may serve as a new model system for studying folding and design of β‐rich proteins.     

Levels of Essential and Xenobiotic Elements and Their Relationships in Milk Available on the Slovak Market with the Estimation of Consumer Exposure

Biological Trace Element Research - The monitoring of various elements in the cow milk is important in the agricultural sector. The goal of this study was to determine the concentrations of calcium...     

Behaviors of Naïve vs. Pheromone-Exposed Leafroller Moths in Plumes from High-Dosage Pheromone Dispensers in a Sustained-Flight Wind Tunnel: Implications for Mating Disruption of These Species

Brief exposures of male Choristoneura rosaceana and Argyrotaenia velutinana to the plumes generated by lures releasing 3-component pheromone blends specifically tuned for each species or by commercially distributed Isomate OBLR/PLR Plus pheromone rope dispensers induced markedly different subsequent behavioral responses to pheromone. A greater proportion of C. rosaceana males took flight and successfully oriented toward lures 24 h after preexposure to a lure, a rope, or the lure–rope combination in a sustained-flight wind tunnel compared to naïve moths. Flights were also longer for preexposed than naïve moths. Preexposed male C. rosaceana were not more likely to fly toward ropes 24 h after preexposure. By contrast, fewer male A. velutinana oriented to lures 24 h after preexposure than did naïve moths. Those preexposed A. velutinana successfully locking onto plumes from lures flew for significantly shorter intervals than did unexposed moths. Electroantennograms revealed no changes at the periphery 15 min and 24 h after preexposure. For A. velutinana, the long-lasting effect was decreased attraction to a lure and increased attraction to a rope. For C. rosaceana, pheromone preexposure increased responsiveness to its authentic blend. This behavioral evidence is sufficient to explain why sexual communication of C. rosaceana is more difficult to disrupt than that of A. velutinana. Furthermore, it suggests a more complete blend of pheromone may be necessary to disrupt the former species but not the latter when using rope dispensers.     

The interplay of fold recognition and experimental structure determination in structural genomics

Achieving the goals of structural genomics initiatives depends on the outcomes of two groups of factors: the number and distribution of experimentally determined protein structures, and our ability to assign novel proteins to known structures (fold recognition) and use them to build models (modeling). The quality of the tools used for fold recognition defines the scope of experimental effort - the more distant the templates that can be recognized, the smaller the number of proteins that have to be solved. Recent improvements in fold recognition may have suggested that the goals of structural genomics initiatives are getting closer. However, problems that surfaced during the first few years of active work have put many of the early estimates in doubt and new ones are still slow in coming.