Structural Analysis of a Trimer of β2-Microgloblin Fragment by Molecular Dynamics Simulations

A peptide ${\beta }_2$-${\text{m}}_{21?31}$, which is a fragment from residue 21 to residue 31 of ${\beta }_2$-microgloblin, is experimentally known to self-assemble and form amyloid fibrils. In order to understand the mechanism of amyloid fibril formations, we applied the replica-exchange molecular dynamics method to the system consisting of three fragments of ${\beta }_2$-${\text{m}}_{21?31}$. From the analyses on the temperature dependence, we found that there is a clear phase transition temperature in which the peptides aggregate with each other. Moreover, we found by the free energy analyses that there are two major stable states: One of them is like amyloid fibrils and the other is amorphous aggregates.     

Penicillium rubens germination on desiccated and nutrient-depleted conditions depends on the water activity during sporogenesis

Fungal growth often appears in a surrounding where water and nutrients are scarce. The impact of this environment during sporogenesis on subsequent growth is often neglected.This study investigates the effect of water availability during sporogenesis on subsequent early growth. Therefore, a carbon-depleted substrate was constructed. Humidity is then the only parameter of interest. The water conditions during sporogenesis, and during subsequent growth, were varied. This is a stressing environment: no carbon source is present, and water provided solely via the vapour.The lag time, $t_l$, and initial growth rate, ${\mu }_{fp}$, of the germ tubes were monitored.The effect of $a_w$ history on germination and initial growth depends on the $RH$ of the environment. Only at low $RH$ do spores produced at low $a_w$ have a smaller $t_l$ and higher ${\mu }_{fp}$ compared to those grown at high $a_w$. This result was remarkably pronounced when the substrate was also made hydrophobic: growth only occurred when spores were developed at low $a_w$ and placed in high $RH$.Spores grown on lowered $a_w$ attract more water. It is hypothesized that this attraction affects subsequent growth behaviour, and is the reason why growth on hydrophobic glass only prevails in the condition of high $RH$ and lowered $a_w$ history.We demonstrate the influence of cultivation conditions on germination, which becomes more pronounced in a more desiccated environment.     

The mechanisms and process of acephate degradation by hydroxyl radical and hydrated electron

The degradation process of acephate in aqueous solution with OH and ${\text{e}}_{\text{aq}}^{?}$ produced by ⁶⁰Co-γ irradiation and electron pulse radiolysis was studied in the present paper. In the aqueous solution, acephate reacted with ${\text{e}}_{\text{aq}}^{?}$ and transformed to transient species which can absorb weakly in the wavelength range of 300–400?nm and decay very fast. According to the decay of hydrated electron, the reaction rate constant of ${\text{e}}_{\text{aq}}^{?}$ and acephate is (3.51?±?0.076)?×?10⁹?dm³·mol^?1·s^?1. The transient species produced in the reaction of OH and acephate do not distinctly absorb the light in the wavelength range of 300–700?nm, so the decay and kinetics of the transient species cannot determinedirectly. The competing reaction of KSCN oracephate with OH were studied to obtain the reaction rate constant of OH and acephate, which is (9.1?±?0.11)?×?10⁸?dm³·mol^?1·s^?1. Although acetylamide and inorganic ions were determined in the products of the reaction of acephate with OH or ${\text{e}}_{\text{aq}}^{?}$, the concentration of inorganic ions in the products of the reaction of acephate with OH is higher than that in the product of the reaction of acephate with ${\text{e}}_{\text{aq}}^{?}$. Moreover, there were sulfide in the products of the reaction of acephatewith ${\text{e}}_{\text{aq}}^{?}$. The degradation pathways of acephate by OH and ${\text{e}}_{\text{aq}}^{?}$ were also proposed based on the products from GC-MS.     

Protein crystal’s shape and polymorphism prediction within the limits resulting from the exploration of the Miyazawa–Jernigan matrix

A computer study of the prediction of the protein crystal’s shape and polymorphism of crystal’s structures within the limits resulting from the exploration of the Miyazawa–Jernigan matrix is presented. In this study, a coarse-graining procedure was applied to prepare a two-dimensional growth unit, where instead of full atom representation of the protein a two-type (hydrophobic–hydrophilic, HP) aminoacidal representation was used. The interaction energies between hydrophobic ($E_{\text{HH}}$) aminoacids were chosen from the well-known HP-type models ($E_{\text{HH}}\in [-4\text{,}-3\text{,}-2.3\text{,}-1]$), whereas interaction energies between hydrophobic and hydrophilic aminoacids ($E_{\text{HP}}$) as well as interaction energies between hydrophilic aminoacids ($E_{\text{PP}}$) were chosen from the range: $<-1\text{,}1>$, but not all values from this range fulfiled limitations resulting from the exploration of the Miyazawa–Jernigan matrix. Exploring every positively vetted combinations of energy interactions a polymorphism of the unit cell was observed what led to the fact that different final crystal’s shapes were obtained.     

Sleep Apnea Detection from Single-Lead ECG Using Features Based on ECG-Derived Respiration (EDR) Signals

Background and objective

One of the important applications of non-invasive respiration monitoring using ECG signal is the detection of obstructive sleep apnea (OSA). ECG-derived respiratory (EDR) signals, contribute to useful information about apnea occurrence. In this paper, two EDR extraction methods are proposed, and their application in automatic OSA detection using single-lead ECG is investigated.