A biomechanical model of swallowing for understanding the influence of saliva and food bolus viscosity on flavor release

After swallowing a liquid or a semi-liquid food product, a thin film responsible for the dynamic profile of aroma release coats the pharyngeal mucosa. The objective of the present article was to understand and quantify physical mechanisms explaining pharyngeal mucosa coating. An elastohydrodynamic model of swallowing was developed for Newtonian liquids that focused on the most occluded region of the pharyngeal peristaltic wave. The model took lubrication by saliva film and mucosa deformability into account. Food bolus flow rate and generated load were predicted as functions of three dimensionless variables: the dimensionless saliva flow rate, the viscosity ratio between saliva and the food bolus, and the elasticity number. Considering physiological conditions, the results were applied to predict aroma release kinetics.Two sets of conditions were distinguished. The first one was obtained when the saliva film is thin, in which case food bolus viscosity has a strong impact on mucosa coating and on flavor release. More importantly, we demonstrated the existence of a second set of conditions. It was obtained when the saliva film is thick and the food bolus coating the mucosa is very diluted by saliva during the swallowing process and the impact of its viscosity on flavor release is weak. This last phenomenon explains physically in vivo observations for Newtonian food products found in the literature. Moreover, in this case, the predicted thickness of the mix of food bolus with saliva coating the mucosa is approximately of 20 μm; value in agreement with orders of magnitude found in the literature.     

EWI‐2wint promotes CD81 clustering that abrogates Hepatitis C Virus entry

CD81 is a major receptor for Hepatitis C Virus (HCV). It belongs to the tetraspanin family whose members form dynamic clusters with numerous partner proteins and with one another, forming tetraspanin‐enriched areas in the plasma membrane. In our study, we combined single‐molecule microscopy and biochemistry experiments to investigate the clustering and membrane behaviour of CD81 in the context of cells expressing EWI‐2wint, a natural inhibitor of HCV entry. Interestingly, we found that EWI‐2wint reduces the global diffusion of CD81 molecules due to a decrease of the diffusion rate of mobile CD81molecules and an increase in the proportion of confined molecules. Indeed, we demonstrated that EWI‐2wint promotes CD81 clustering and confinement in CD81‐enriched areas. In addition, we showed that EWI‐2wint influences the colocalization of CD81 with Claudin‐1 – a co‐receptor required for HCV entry. Together, our results indicate that a change in membrane partitioning of CD81 occurs in the presence of EWI‐2wint. This study gives new insights on the mechanism by which HCV enters into its target cells, namely by exploiting the dynamic properties of CD81.     

Serrated Pathway Adenocarcinomas: Molecular and Immunohistochemical Insights into Their Recognition

Introduction

Colorectal adenocarcinomas (CRC) developed through serrated pathway seem to present particular behavior compared with the non-serrated ones, but recognition of them is difficult to do. The aim of our paper was to establish some criteria to facilitate their identification.

Materials and Methods

In 170 consecutive CRCs, we performed immunohistochemical staining with Cytokeratin 7 (CK7) and Cytokeratin 20 (CK20) and also with p53 and MLH-1. At the same time, we analyzed BRAF and K-ras mutations and the microsatellite status of CRC.

Results

26.47% of cases expressed CK7, and 16.47% were CK20-negative. Diffuse positivity for CK7 was associated in the proximal colon with CK20 negativity or weak positivity, BRAF mutations, lack of K-ras mutations, and p53 and MLH-1 negativity. All these cases were microsatellite-unstable and were diagnosed in stage II. Those cases from the distal colon and rectum that expressed CK7 were K-ras-mutated and had low p53 index and MLH-1 positivity, independent of the CK20 expression.

Conclusions

CK7, associated with MLH-1 and p53 expression, and also with the microsatellite status, BRAF and K-ras pattern, might be used to identify the CRC potentially going through serrated pathway. The serrated pathway adenocarcinomas of the proximal colon that do not display the morphological features of this pattern are more frequent CK7+/p53−/MLH-1−/BRAF-mutated/K-ras-wt/MSI cases, but those located in the distal colorectal segments seem to be CK7+/CK20+/p53−/MLH-1+/BRAF wt/K-ras-mutated/MSS cases.     

Romanian Maize (Zea mays) Inbred Lines as a Source of Genetic Diversity in SE Europe,and Their Potential in Future Breeding Efforts

Maize has always been under constant human selection ever since it had been domesticated. Intensive breeding programs that resulted in the massive use of hybrids nowadays have started in the 60s. That brought significant yield increases but reduced the genetic diversity at the same time. Consequently, breeders and researchers alike turned their attention to national germplasm collections established decades ago in many countries, as they may hold allelic variations that could prove useful for future improvements. These collections are mainly composed of inbred lines originating from well-adapted local open pollinated varieties. However, there is an overall lack of data in the literature about the genetic diversity of maize in SE Europe, and its potential for future breeding efforts. There are no data, whatsoever, on the nutritional quality of the grain, primarily dictated by the zein proteins. We therefore sought to use the Romanian maize germplasm as an entry point in understanding the molecular make-up of maize in this part of Europe. By using 80 SSR markers, evenly spread throughout the genome, on 82 inbred lines from various parts of the country, we were able to decipher population structure and the existing relationships between those and the eight international standards used, including the reference sequenced genome B73. Corroborating molecular data with a standardized morphological, physiological, and biochemical characterization of all 90 inbred lines, this is the first comprehensive such study on the existing SE European maize germplasm. The inbred lines we present here are an important addition to the ever-shrinking gene pool that the breeding programs are faced-with, because of the allelic richness they hold. They may serve as parental lines in crosses that will lead to new hybrids, characterized by a high level of heterosis, nationwide and beyond, due to their existing relationship with the international germplasm.     

A multiscale dynamic model of DNA supercoil relaxation by topoisomerase IB

In this study, we report what we believe to be the first multiscale simulation of the dynamic relaxation of DNA supercoils by human topoisomerase IB (topo IB). We leverage our previous molecular dynamics calculations of the free energy landscape describing the interaction between a short DNA fragment and topo IB. Herein, this landscape is used to prescribe boundary conditions for a computational, elastodynamic continuum rod model of a long length of supercoiled DNA. The rod model, which accounts for the nonlinear bending, twisting, and electrostatic interaction of the (negatively charged) DNA backbone, is extended to include the hydrodynamic drag induced by the surrounding physiological buffer. Simulations for a 200-bp-long DNA supercoil in complex with topo IB reveal a relaxation timescale of ∼0.1–1.0 μs. The relaxation follows a sequence of cascading reductions in the supercoil linking number (Lk), twist (Tw), and writhe (Wr) that follow companion cascading reductions in the supercoil elastic and electrostatic energies. The novel (to our knowledge) multiscale modeling method may enable simulations of the entire experimental setup that measures DNA supercoiling and relaxation via single molecule magnetic trapping.     

Effect of organic carbon,C:N ratio and light on the growth and lipid productivity of microalgae/cyanobacteria coculture

Current culture methods based on monocultures under phototrophic regimes are prone to contamination, predation, and collapse. Native cultures of multiple species are adapted to the local conditions and are more robust against contamination and predation. Growth, lipid and biomass productivity of a Louisiana native coculture of microalgae (Chlorella vulgaris) and cyanobacteria (Leptolyngbya sp.) in heterotrophic and mixotrophic regimes were investigated. Dextrose and sodium acetate at C:N ratios of 15:1 and 30:1 under heterotrophic (dark) and mixotrophic (400 μmol m^?2 s^?1) regimes were compared with autotrophic controls. The carbon source and C:N ratio impacted growth and biomass productivity. Mixotrophic cultures with sodium acetate (C:N 15:1) resulted in the highest mean biomass productivity (156 g m^?3 d^?1) and neutral lipid productivity (24.07 g m^?3 d^?1). The maximum net specific growth rate (U) was higher (0.97 d^?1) in mixotrophic cultures with dextrose (C:N 15:1) but could not be sustained resulting in lower total biomass than in mixotrophic cultures with acetate (C:N 15:1), with a U of 0.67 d^?1. The ability of the Louisiana coculture to use organic carbon for biomass and lipid production makes it a viable feedstock for biofuels and bioproducts.     

<Emphasis Type="Italic">Zittelina massei</Emphasis> n. sp., a new dasycladacean alga from the Lower Cretaceous strata of Pădurea Craiului (Apuseni Mountains,Romania)

A new taxon has been found in the Upper Aptian (Clansayesian)-Albian limestones of Pădurea Craiului (Northern Apuseni Mountains). It is the second representative of the genus Zittelina identified in deposits older than the Cenozoic. This new species differs from Z. hispanica—described from Hauterivian deposits—for its axial cavity is narrower (with proportionally longer laterals and a lower d/D ratio) and the median part of the laterals are fused in verticillar planes. It also shows general features that distinguish it from related taxa in Cenozoic strata.     

Flea burden and its influence on nest selection and use in Dryomys nitedula Pallas, 1778

Since dormice usually use natural tree hollows or artificial nest boxes as nest sites and these nests are reused from 1 year to another, the present study investigated how the parasite loads from old nests affected the behaviour of the forest dormouse Dryomys nitedula Pallas, 1778. Dormice were subjected to three different experiments: 1. They were given the choice of a nest box infected with ectoparasites and a new unused nest box; 2. Dormice were given the choice of a treated (uninfected) previously used nest boxes and previously used nest box that was infected; and 3. Using infrared motion sensor cameras, we tested weather they preferred to avoid nest boxes when only infected nests were available. The results revealed that the females with pups are pickier when choosing the nursery site. These preferred empty nest boxes or nest boxes with treated nests instead of the infested ones. However, non-breeding adults and sub-adults showed indifference to the flea infestation of the nest.     

XRCC3 Thr241Met polymorphism and risk of acute myeloid leukemia in a Romanian population

Background

DNA repair systems have a critical role in maintaining the genome integrity and stability. DNA repair gene polymorphisms may influence the capacity to repair DNA damage, and thus lead to an increased cancer susceptibility. X-ray repair cross-complementing groups 3 (XRCC3), a DNA repair gene, may be involved in acute myeloid leukemia susceptibility. The objective of the current study was to investigate the association of Thr241Met polymorphism of XRCC3 gene with the risk of acute myeloid leukemia (AML).

Methods

This study included 78 AML patients and 121 healthy individuals without cancer. We used polymerase chain reaction-restriction fragment length polymorphism assay to determine XRCC3 genotypes.

Results

The XRCC3 variant genotype (Thr/Met+Met/Met) was more frequent in AML patients than in healthy controls (OR = 2.76, 95% CI: 1.52-4.98, P = 0.001). Our study revealed a statistically significant association between variant genotype (Thr/Met+Met/Met) and AML de novo compared to secondary AML (P = 0.007). No significant associations were found between any genotype and age at diagnosis, number of white blood cells and subtype of AML. Overall survival of patients with Thr/Thr genotype was better than those of variant Thr/Met and Met/Met genotypes.

Conclusions

Our findings indicate that the XRCC3 Thr241Met polymorphism may be a genetic risk factor for AML, particularly in male patients with de novo AML from the central part of Romania.     

Genetic engineering of Plum pox virus resistance: ‘HoneySweet’ plum—from concept to product

Sharka disease, caused by Plum pox virus (PPV) was first recorded in Bulgaria during the early twentieth century and since that first report, the disease has progressively spread throughout Europe and more recently to Asia, Africa, North and South America. Few PPV resistance genes have been found to naturally occur in Prunus and this has led to the investigation of biotech approaches to the development of resistance through genetic engineering (GE). A notable example of the utility of this approach is ‘HoneySweet’ plum. PPV protection in this case is based on RNA interference (RNAi) and resistance has been shown to be highly effective, stable, durable, and heritable as a dominant trait. Extensive testing and risk assessment of ‘HoneySweet’ in laboratory, greenhouse and in the field for over 20 years has demonstrated not only the effectiveness but also the safety of the technology. ‘HoneySweet’ has been cleared for cultivation in the USA. By the appropriate regulatory agencies. The development and regulatory approval of ‘HoneySweet’ demonstrate the ability of RNAi technology to contribute to the sustainability of stone fruit production in regions impacted by PPV. Although it has taken almost 100 years since the identification of sharka, we are now able to effectively protect stone fruit species against this disease through the application of GE.