Assessment of chromatin status (SCSA) in epididymal and ejaculated sperm in Iberian red deer, ram and domestic dog

Abnormal chromatin condensation is not detected using classical techniques for sperm analysis. SCSA has demonstrated its usefulness in sperm chromatin analysis in several species (human, bull, stallion and boar). In this work, we studied sperm samples from red deer, ram and dog to analyze the differentiation of chromatin structure applying SCSA in epididymal and ejaculated spermatozoa. Epididymal samples were obtained from the caput, corpus and cauda by means of cuts, and ejaculated ones were obtained by electroejaculation (deer), artificial vagina (ram) and digital manipulation (dog). SCSA results suggested different critical points in sperm maturation (spermatozoa with loose chromatin to more condensed chromatin) among species: from corpus to cauda in ram and from caput to corpus in deer and dog. Moreover, we also detected differences in ruminants and dog, reflected in the appearance of SCSA plots. Indeed, ram and deer samples rendered two peaks within the sperm main population (sperm with condensed chromatin), whereas only one was detected in dog. Although some differences were observed between cauda and ejaculated samples, SCSA parameters indicated good chromatin condensation, making these samples suitable for germplasm banking. Some species-dependent modifications in the analysis of the results may be necessary to take full advantage of its analytical power.     

Some like it cold: Temperature‐dependent habitat selection by narwhals

The narwhal (Monodon monoceros) is a high‐Arctic species inhabiting areas that are experiencing increases in sea temperatures, which together with reduction in sea ice are expected to modify the niches of several Arctic marine apex predators. The Scoresby Sound fjord complex in East Greenland is the summer residence for an isolated population of narwhals. The movements of 12 whales instrumented with Fastloc‐GPS transmitters were studied during summer in Scoresby Sound and at their offshore winter ground in 2017–2019. An additional four narwhals provided detailed hydrographic profiles on both summer and winter grounds. Data on diving of the whales were obtained from 20 satellite‐linked time‐depth recorders and 16 Acousonde? recorders that also provided information on the temperature and depth of buzzes. In summer, the foraging whales targeted depths between 300 and 850 m where the preferred areas visited by the whales had temperatures ranging between 0.6 and 1.5°C (mean = 1.1°C, SD = 0.22). The highest probability of buzzing activity during summer was at a temperature of 0.7°C and at depths > 300 m. The whales targeted similar depths at their offshore winter ground where the temperature was slightly higher (range: 0.7–1.7°C, mean = 1.3°C, SD = 0.29). Both the probability of buzzing events and the spatial distribution of the whales in both seasons demonstrated a preferential selection of cold water. This was particularly pronounced in winter where cold coastal water was selected and warm Atlantic water farther offshore was avoided. It is unknown if the small temperature niche of whales while feeding is because prey is concentrated at these temperature gradients and is easier to capture at low temperatures, or because there are limitations in the thermoregulation of the whales. In any case, the small niche requirements together with their strong site fidelity emphasize the sensitivity of narwhals to changes in the thermal characteristics of their habitats.     

Viral miRNAs exploiting the endosomal-exosomal pathway for intercellular cross-talk and immune evasion

The class of persistent gamma-herpesviruses has developed a variety of strategies that exploit host-cell regulatory pathways to ensure a long-lasting, well-balanced infection of their host. However when these pathways are deregulated, an otherwise harmless infection can lead to disease including cancer. We recently demonstrated that the human herpes virus 4 (HHV4) also known as Epstein-Barr virus (EBV), encodes for small regulatory non-coding microRNAs (miRNAs) that can be transferred from an infected cell to uninfected neighboring cells. Upon arrival these miRNAs are functional in the recipient cell, in that they are able to down regulate specific target genes. These secreted miRNAs are transported to recipient cells via small nano-sized vesicles (known as exosomes) that are of endosomal origin, formed as intraluminal vesicles (ILV) inside multivesicular bodies (MVB). One question that needs to be addressed is how viral miRNAs are sorted into these exosomes. Mature miRNAs, including those of viral origin, are loaded into RNA-induced silencing complexes (RISC) for gene silencing via blocking mRNA translation and/or initiating mRNA decay. Recent insights indicate that cytoplasmic RNA granules rich in RISC complexes are closely associated with endosomes. In fact, selective components of RISC, including GW182 and Argonaut proteins, miRNAs and mRNAs are present in exosomes. Thus miRNA function, mRNA stability and exosome-mediated intercellular communication converge at the level of endosomes. Since endosomes can be considered as key intracellular cross-roads that regulate communication of cells with their exterior, including neighboring cells, it is perhaps not surprising that viruses have found means to exploit this pathway to their benefit. Little is known however, how and if (micro) RNA species are specifically sorted into ILVs and what (micro)RNA-binding proteins are involved. Here we discuss recent developments relating to intracellular trafficking and function of miRNA-containing protein complexes that EBV may exploit for promoting or restricting miRNAs sorting into exosomes for intercellular regulatory functions. This article is part of a Special Issue entitled: MicroRNAs in viral gene regulation.     

Development of a Screening Tool for Sleep Disordered Breathing in Children Using the Phone Oximeter?

Background

Sleep disordered breathing (SDB) can lead to daytime sleepiness, growth failure and developmental delay in children. Polysomnography (PSG), the gold standard to diagnose SDB, is a highly resource-intensive test, confined to the sleep laboratory.

Aim

To combine the blood oxygen saturation (SpO₂) characterization and cardiac modulation, quantified by pulse rate variability (PRV), to identify children with SDB using the Phone Oximeter, a device integrating a pulse oximeter with a smartphone.

Methods

Following ethics approval and informed consent, 160 children referred to British Columbia Children''s Hospital for overnight PSG were recruited. A second pulse oximeter sensor applied to the finger adjacent to the one used for standard PSG was attached to the Phone Oximeter to record overnight pulse oximetry (SpO₂ and photoplethysmogram (PPG)) alongside the PSG.

Results

We studied 146 children through the analysis of the SpO₂ pattern, and PRV as an estimate of heart rate variability calculated from the PPG. SpO₂ variability and SpO₂ spectral power at low frequency, was significantly higher in children with SDB due to the modulation provoked by airway obstruction during sleep (p-value ). PRV analysis reflected a significant augmentation of sympathetic activity provoked by intermittent hypoxia in SDB children. A linear classifier was trained with the most discriminating features to identify children with SDB. The classifier was validated with internal and external cross-validation, providing a high negative predictive value (92.6%) and a good balance between sensitivity (88.4%) and specificity (83.6%). Combining SpO₂ and PRV analysis improved the classification performance, providing an area under the receiver operating characteristic curve of 88%, beyond the 82% achieved using SpO₂ analysis alone.

Conclusions

These results demonstrate that the implementation of this algorithm in the Phone Oximeter will provide an improved portable, at-home screening tool, with the capability of monitoring patients over multiple nights.     

Effect of semen collection method (artificial vagina vs. electroejaculation), extender and centrifugation on post-thaw sperm quality of Blanca-Celtibérica buck ejaculates

The aim of this study was to evaluate the effect of semen collection method (artificial vagina compared to electroejaculation), season in which the semen was collected (breeding season compared to non-breeding season), freezing extender (Biladyl(?), Andromed(?) and skim milk based extender) and pre-treatment procedure (washing compared to non-washing) on post-thaw semen quality in buck. Ejaculates from seven bucks of the Blanca-Celtibérica breed were collected by artificial vagina and electroejaculation during the breeding (July to December) and non-breeding season (January to June). Samples were split in two aliquots and one of them was washed. Three freezing extenders were evaluated on washing and non-washing sperm samples. Ejaculates collected by artificial vagina had a greater sperm quality after thawing, with greater values (P≤0.05) for SM (sperm motility), NAR (acrosome intact), YO-PRO-1-/PI- (intact spermatozoa), and Mitotracker+/YO-PRO-1- (spermatozoa with active mitochondria) and lower % DFI (DNA fragmentation index). Thawed sperm samples which were collected during the breeding season had greater values (P≤0.05) for NAR, intact spermatozoa and spermatozoa with active mitochondria, than those semen samples obtained during the non-breeding season. Semen freezing with Biladyl(?) and Andromed(?) resulted in a greater sperm quality (P≤0.05) after thawing in relation to milk-based extender. Washing procedure had no effect on sperm parameters assessed at thawing. Results from the present study suggest that the success of semen cryopreservation in Blanca-Celtibérica goat depends on semen collection method and season, as well as on the extender used. Thus, the post-thaw sperm quality will be greater (P≤0.05) when samples are collected by artificial vagina during the breeding season and when Biladyl(?) or Andromed(?) are used as freezing extenders.     

Chloroquine-induced QTc prolongation in COVID-19 patients

In the battle against the SARS-CoV‑2 pandemic, chloroquine has emerged as a new potential therapeutic option for the treatment of infected patie     

Effect of guanidine and arginine on protein–ligand interactions in multimodal cation‐exchange chromatography

The addition of fluid phase modifiers provides significant opportunities for increasing the selectivity of multimodal chromatography. In order to optimize this selectivity, it is important to understand the fundamental interactions between proteins and these modifiers. To this end, molecular dynamics (MD) simulations were first performed to study the interactions of guanidine and arginine with three proteins. The simulation results showed that both guanidine and arginine interacted primarily with the negatively charged regions on the proteins and that these regions could be readily predicted using electrostatic potential maps. Protein surface characterization was then carried out using computationally efficient coarse‐grained techniques for a broader set of proteins which exhibited interesting chromatographic retention behavior upon the addition of these modifiers. It was shown that proteins exhibiting an increased retention in the presence of guanidine possessed hydrophobic regions adjacent to negatively charged regions on their surfaces. In contrast, proteins which exhibited a decreased binding in the presence of guanidine did not have hydrophobic regions adjacent to negatively charged patches. These results indicated that the effect of guanidine could be described as a combination of competitive binding, charge neutralization and increased hydrophobic interactions for certain proteins. In contrast, arginine resulted in a significant decrease in protein retention times primarily due to competition for the resin and steric effects, with minimal accompanying increase in hydrophobic interactions. The approach presented in this paper which employs MD simulations to guide the application of coarse‐grained approaches is expected to be extremely useful for methods development in downstream bioprocesses. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:435–447, 2017     

Effect of egg yolk, cryoprotectant, and various sugars on semen cryopreservation in endangered Cuvier's gazelle (Gazella cuvieri)

Cryopreservation of spermatozoa from endangered species is a valuable tool for genetic management. Previous studies showed the feasibility of cryopreservation of spermatozoa from various endangered gazelles but have also revealed difficulties with available protocols for semen freezing in Cuvier's gazelle (Gazella cuvieri). Experiments were carried out to investigate the effect of (a) 5% or 20% egg yolk or 4% or 6% glycerol, and (b) addition of sugars (glucose, fructose, lactose and raffinose) on cryopreservation using a Tes-Tris-based diluent (TEST). A diluent containing 13.5% raffinose, 5% or 20% egg yolk, and 6% glycerol (REYG) was also evaluated. Semen was obtained by electroejaculation from 22 G. cuvieri males. Diluted samples were loaded into 0.25 ml straws, cooled to 5 °C over 1.5 h (−0.16 °C/min), equilibrated at that temperature for 2 h, frozen in nitrogen vapours for 10 min and plunged into liquid nitrogen. Subsamples were assessed for motility and acrosome integrity upon collection, after refrigeration–equilibration, after freezing and thawing, and 2 h after thawing. Use of TEST with 20% egg yolk or with 4% glycerol led to worse motility preservation, whereas TEST with 5% egg yolk and 6% glycerol led to better results. Addition of fructose, lactose or raffinose to TEST resulted in similar or worse preservation of motility than inclusion of glucose. On the other hand, use of a raffinose-based medium with 20% egg yolk and 6% glycerol (REYG) afforded better preservation of motility than use of TEST. With REYG, 20% egg yolk was better than 5% egg yolk for motility preservation. Differences were noted between males in their responses to cryopreservation when using different egg yolk or glycerol concentrations. Moreover, spermatozoa from most males exhibited better cryopreservation with REYG although some were better cryopreserved in TEST. The raffinose-based diluent thus represents an improvement over previous results but more work is needed to better characterize cryopreservation conditions for future routine banking of Cuvier's gazelle spermatozoa.     

Temperature dependence of the solubility of non-polar gases in water

An explanation is provided for the experimentally observed temperature dependence of the solubility and the solubility minimum of non-polar gases in water. The influence of solute size and solute-water attractive interactions on the solubility minimum temperature is investigated. The transfer of a non-polar solute from the ideal gas into water is divided into two steps: formation of a cavity in water with the size and shape of the solute and insertion of the solute in this cavity which is equivalent to 'turning on' solute-water attractive interactions. This two step process divides the excess chemical potential of the non-polar solute in water into repulsive and attractive contributions, respectively. The reversible work for cavity formation is modeled using an information theory model of hydrophobic hydration. Attractive contributions are calculated by modeling the water structure in the vicinity of non-polar solutes. These models make a direct connection between microscopic quantities and macroscopic observables. Moreover, they provide an understanding of the peculiar temperature dependences of the hydration thermodynamics from properties of pure water; specifically, bulk water density and the water oxygen-oxygen radial distribution function.     

Sperm cryopreservation in three species of endangered gazelles (Gazella cuvieri,G. dama mhorr,and G. dorcas neglecta)

Long-term storage of semen by cryopreservation, with high recovery rates on thawing, is essential for the establishment of genetic resource banks of endangered species. The purpose of the present study was to evaluate various diluents for the cryopreservation of spermatozoa from three species of gazelles (genus Gazella) in a captive breeding program. The diluents compared were Tes (N-tris(hydroxymethyl)methyl-2 aminoethane sulfonic acid)-Tris with 5% egg yolk and 6% glycerol (TEST) and Triladyl, yolk-citrate, Tris-trehalose, and Tris-lactose-all of them with 20% egg yolk and 6% (Triladyl) or 8% glycerol. Semen was obtained by electroejaculation from 12 G. cuvieri, 12 G. dama, and 13 G. dorcas males. Samples with less than 50% motile sperm, positive endosmosis, or acrosome integrity were not used. Diluted samples were loaded into 0.25-ml straws, cooled slowly to 5 degrees C over 1.5 h (-0.16 degrees C/min), equilibrated at that temperature for 2 h, frozen in nitrogen vapors for 10 min, and plunged into liquid nitrogen. Subsamples were assessed fresh, after refrigeration-equilibration, after freezing and thawing, and 2 h after thawing. Differences were seen between diluents, with best overall recovery rates after freezing and thawing found with Triladyl, TEST, and Tris-trehalose in G. cuvieri, TEST in G. dama, and Triladyl and TEST in G. dorcas. Differences were observed between species in the ability to withstand freezing and thawing, with best results seen in G. dorcas, intermediate results in G. dama, and worst results in G. cuvieri. These differences were inversely related to the average values of inbreeding of these populations. The underlying mechanism responsible for these differences may be a differential resistance to osmotic shock.