Mechanophysical stimulations of mucin secretion in cultures of nasal epithelial cells

Nasal epithelial cells secret mucins and are exposed in vivo to airflow-induced mechanophysical stresses, including wall shear stress (WSS), temperature, and humidity. In this work, human nasal epithelial cells cultured under air-liquid interface conditions were subjected to fields of airflow-induced oscillatory WSS at different temperature and humidity conditions. Changes in mucin secretion due to WSS were measured and the role of the cytoskeleton in mucin secretion was explored. Mucin secretion significantly increased in response to WSS in a magnitude-dependent manner with respect to static cultures and independently of the airflow temperature and humidity. In static cultures, mucin secretion decreased at high humidity with or without elevation of the temperature with respect to cultures at a comfortable climate. In cultures exposed to WSS, mucin secretion increased at high temperature with respect to cultures at comfortable climate conditions. The polymerization of actin microfilaments was shown to increase mucin secretion under WSS, whereas the dynamics of microtubule polymerization did not affect secretion. In conclusion, the data in this study show that mucin secretion is sensitive to oscillatory WSS as well as high temperature and humidity conditions.     

Mycorrhizal association between the desert truffle Terfezia boudieri and Helianthemum sessiliflorum alters plant physiology and fitness to arid conditions

The host plant Helianthemum sessiliflorum was inoculated with the mycorrhizal desert truffle Terfezia boudieri Chatin, and the subsequent effects of the ectomycorrhizal relationship on host physiology were determined. Diurnal measurements revealed that mycorrhizal (M) plants had higher rates of photosynthesis (35%), transpiration (18%), and night respiration (49%) than non-mycorrhizal (NM) plants. Consequently, M plants exhibited higher biomass accumulation, higher shoot-to-root ratios, and improved water use efficiency compared to NM plants. Total chlorophyll content was higher in M plants, and the ratio between chlorophyll a to chlorophyll b was altered in M plants. The increase in chlorophyll b content was significantly higher than the increase in chlorophyll a content (2.58- and 1.52-fold, respectively) compared to control. Calculation of the photosynthetic activation energy indicated lower energy requirements for CO₂ assimilation in M plants than in NM plants (48.62 and 61.56 kJ mol⁻¹, respectively). Continuous measurements of CO₂ exchange and transpiration in M plants versus NM plants provided a complete picture of the daily physiological differences brought on by the ectomycorrhizal relationships. The enhanced competence of M plants to withstand the harsh environmental conditions of the desert is discussed in view of the mycorrhizal-derived alterations in host physiology.     

Guiding protein docking with geometric and evolutionary information

Structural modeling of molecular assemblies promises to improve our understanding of molecular interactions and biological function. Even when focusing on modeling structures of protein dimers from knowledge of monomeric native structure, docking two rigid structures onto one another entails exploring a large configurational space. This paper presents a novel approach for docking protein molecules and elucidating native-like configurations of protein dimers. The approach makes use of geometric hashing to focus the docking of monomeric units on geometrically complementary regions through rigid-body transformations. This geometry-based approach improves the feasibility of searching the combined configurational space. The search space is narrowed even further by focusing the sought rigid-body transformations around molecular surface regions composed of amino acids with high evolutionary conservation. This condition is based on recent findings, where analysis of protein assemblies reveals that many functional interfaces are significantly conserved throughout evolution. Different search procedures are employed in this work to search the resulting narrowed configurational space. A proof-of-concept energy-guided probabilistic search procedure is also presented. Results are shown on a broad list of 18 protein dimers and additionally compared with data reported by other labs. Our analysis shows that focusing the search around evolutionary-conserved interfaces results in lower lRMSDs.     

Promoting organ donation registration with the priority incentive: Israeli transplantation surgeons' and other medical practitioners' views and ethical concerns

Because the number of organs available for transplantation does not meet the needs of potential recipients, some have proposed that a potentially effective way to increase registration is to offer a self-benefit incentive that grants a 'preferred status' or some degree of prioritization to those who register as potential donors, in case they might need organs. This proposal has elicited an ethical debate on the appropriateness of such a benefit in the context of a life-saving medical procedure. In this paper we review arguments and ethical concerns raised by scholars, and studies of views of members of the public regarding the prioritization incentive system. We also report on our study of the views of those involved in organ transplant and of other medical professionals in Israel, as over half a decade ago Israel implemented a prioritization incentive system. Bioethicists propose that key stakeholders' views can provide additional arguments and perspectives on controversial issues. Proponents justify the prioritization incentive drawing mainly on arguments related to its potential effectiveness, reciprocity and fairness. Opponents point to the fact that registering is not binding and not an actual donation, and raise concerns regarding equity, autonomy and gaming the system. Ethical concerns raised by the practitioners in the study were examined in light of scholars' arguments and actual registration and donation data. Practitioners involved in transplantation raised ethical concerns corresponding to those raised by scholars as well as additional concerns. They also challenged proponents' assumptions regarding the utility of the incentive system from their own experience and argued that proponents obscure the meaning of reciprocity.