Pyrosequencing reveals highly diverse and species-specific microbial communities in sponges from the Red Sea

Marine sponges are associated with a remarkable array of microorganisms. Using a tag pyrosequencing technology, this study was the first to investigate in depth the microbial communities associated with three Red Sea sponges, Hyrtios erectus, Stylissa carteri and Xestospongia testudinaria. We revealed highly diverse sponge-associated bacterial communities with up to 1000 microbial operational taxonomic units (OTUs) and richness estimates of up to 2000 species. Altogether, 26 bacterial phyla were detected from the Red Sea sponges, 11 of which were absent from the surrounding sea water and 4 were recorded in sponges for the first time. Up to 100 OTUs with richness estimates of up to 300 archaeal species were revealed from a single sponge species. This is by far the highest archaeal diversity ever recorded for sponges. A non-negligible proportion of unclassified reads was observed in sponges. Our results demonstrated that the sponge-associated microbial communities remained highly consistent in the same sponge species from different locations, although they varied at different degrees among different sponge species. A significant proportion of the tag sequences from the sponges could be assigned to one of the sponge-specific clusters previously defined. In addition, the sponge-associated microbial communities were consistently divergent from those present in the surrounding sea water. Our results suggest that the Red Sea sponges possess highly sponge-specific or even sponge-species-specific microbial communities that are resistant to environmental disturbance, and much of their microbial diversity remains to be explored.     

Time of day affects heart rate recovery and variability after maximal exercise in pre-hypertensive men

ABSTRACT

Previous literature suggests that human behaviour and physiology are somehow altered by the moon-cycle, with particular emphasis on poorer sleep quality and increased aggressive behaviour during full moon. The latter variables can negatively impact athletes’ recovery and increase the likelihood of injury resulting from collision with another athlete. Therefore, the current study aimed to investigate the association between the lunar cycle and injury risk in professional football players (soccer). We monitored injuries and player exposure in the premier professional league in Qatar during four consecutive seasons (2013–2014 through 2016–2017). Acute (sudden-onset traumatic) injuries (n = 1184; 587 from contact with another player and 597 without player contact) recorded during matches and training were classified according to the lunar cycle characteristics on the date of injury: (i) moon illumination, (ii) lunar distance from earth and (iii) tidal coefficient, acquired from the lunar calendar and tide tables. We used a Poisson regression model to examine the relationship between injury risk and lunar cycle characteristics. We did not detect any association between injury risk and moon illumination, earth-to-moon distance or tidal coefficient, not for all acute injuries, nor for contact and non-contact injuries when examined separately. The findings suggest that the full moon or new moon or the gravitational pull have no effect on football injuries. Thus, organisers need not consult moon or tide tables when planning future event schedules.     

Differentiation of serum-free embryoid bodies from human induced pluripotent stem cells into networks

Three-dimensional aggregation cultures allow for complex development of differentiated human induced pluripotent stem cells. However, this approach is not easily amenable to live-cell imaging and electrophysiological applications due to the thickness and the geometry of the tissue. Here, we present an improvement on the traditional aggregation method by combining the use of cell culture inserts with serum-free embryoid bodies (SFEBs). The use of this technique allows the structures to maintain their three-dimensional structure while thinning substantially. We demonstrate that this technique can be used for electrophysiological recodings as well as live-cell calcium imaging combined with electrical stimulation, akin to organotypic slice preparations. This provides an important experimental tool that can be used to bridge 3-D structures with traditional monolayer approaches used in stem cell applications.     

Molecular features of neural stem cells enable their enrichment using pharmacological inhibitors of survival‐promoting kinases

Isolating a pure population of neural stem cells (NSCs) has been difficult since no exclusive surface markers have been identified for panning or FACS purification. Moreover, additional refinements for maintaining NSCs in culture are required, since NSCs generate a variety of neural precursors (NPs) as they proliferate. Here, we demonstrate that post‐natal rat NPs express low levels of pro‐apoptotic molecules and resist phosphatidylinositol 3′OH kinase and extracellular regulated kinase 1/2 inhibition as compared to late oligodendrocyte progenitors. Furthermore, maintaining subventricular zone precursors in LY294002 and PD98059, inhibitors of PI3K and ERK1/2 signaling, eliminated lineage‐restricted precursors as revealed by enrichment for Nestin⁺/SOX‐2⁺ cells. The cells that survived formed neurospheres and 89% of these neurospheres were tripotential, generating neurons, astrocytes, and oligodendrocytes. Without this enrichment step, less than 50% of the NPs were Nestin⁺/SOX‐2⁺ and 42% of the neurospheres were tripotential. In addition, neurospheres enriched using this procedure produced 3‐times more secondary neurospheres, supporting the conclusion that this procedure enriches for NSCs. A number of genes that enhance survival were more highly expressed in neurospheres compared to late oligodendrocyte progenitors. Altogether, these studies demonstrate that primitive neural precursors can be enriched using a relatively simple and inexpensive means that will facilitate cell replacement strategies using stem cells as well as other studies whose goal is to reveal the fundamental properties of primitive neural precursors.

     

Reactive Oxygen Species Mediated Bacterial Biofilm Inhibition via Zinc Oxide Nanoparticles and Their Statistical Determination

The formation of bacterial biofilm is a major challenge in clinical applications. The main aim of this study is to describe the synthesis, characterization and biocidal potential of zinc oxide nanoparticles (NPs) against bacterial strain Pseudomonas aeruginosa. These nanoparticles were synthesized via soft chemical solution process in a very short time and their structural properties have been investigated in detail by using X-ray diffraction and transmission electron microscopy measurements. In this work, the potential of synthesized ZnO-NPs (∼10–15 nm) has been assessed in-vitro inhibition of bacteria and the formation of their biofilms was observed using the tissue culture plate assays. The crystal violet staining on biofilm formation and its optical density revealed the effect on biofilm inhibition. The NPs at a concentration of 100 µg/mL significantly inhibited the growth of bacteria and biofilm formation. The biofilm inhibition by ZnO-NPs was also confirmed via bio-transmission electron microscopy (Bio-TEM). The Bio-TEM analysis of ZnO-NPs treated bacteria confirmed the deformation and damage of cells. The bacterial growth in presence of NPs concluded the bactericidal ability of NPs in a concentration dependent manner. It has been speculated that the antibacterial activity of NPs as a surface coating material, could be a feasible approach for controlling the pathogens. Additionally, the obtained bacterial solution data is also in agreement with the results from statistical analytical methods.     

Lipoteichoic Acid from Staphylococcus aureus Induces Lung Endothelial Cell Barrier Dysfunction: Role of Reactive Oxygen and Nitrogen Species

Tunneled central venous catheters (TCVCs) are used for dialysis access in 82% of new hemodialysis patients and are rapidly colonized with Gram-positive organism (e.g. Staphylococcus aureus) biofilm, a source of recurrent infections and chronic inflammation. Lipoteichoic acid (LTA), a cell wall ribitol polymer from Gram-positive organisms, mediates inflammation through the Toll-like receptor 2 (TLR2). The effect of LTA on lung endothelial permeability is not known. We tested the hypothesis that LTA from Staphylococcus aureus induces alterations in the permeability of pulmonary microvessel endothelial monolayers (PMEM) that result from activation of TLR2 and are mediated by reactive oxygen/nitrogen species (RONS). The permeability of PMEM was assessed by the clearance rate of Evans blue-labeled albumin, the activation of the TLR2 pathway was assessed by Western blot, and the generation of RONS was measured by the fluorescence of oxidized dihydroethidium and a dichlorofluorescein derivative. Treatment with LTA or the TLR2 agonist Pam₍₃₎CSK₍₄₎ induced significant increases in albumin permeability, IκBα phosphorylation, IRAK1 degradation, RONS generation, and endothelial nitric oxide synthase (eNOS) activation (as measured by the p-eNOS^ser1177:p-eNOS^thr495 ratio). The effects on permeability and RONS were effectively prevented by co-administration of the superoxide scavenger Tiron, the peroxynitrite scavenger Urate, or the eNOS inhibitor L-NAME and these effects as well as eNOS activation were reduced or prevented by pretreatment with an IRAK1/4 inhibitor. The results indicate that the activation of TLR2 and the generation of ROS/RNS mediates LTA-induced barrier dysfunction in PMEM.     

Recessive <Emphasis Type="Italic">VARS2</Emphasis> mutation underlies a novel syndrome with epilepsy,mental retardation,short stature,growth hormone deficiency,and hypogonadism

Background

Most mitochondrial and cytoplasmic aminoacyl-tRNA synthetases (aaRSs) are encoded by nuclear genes. Syndromic disorders resulting from mutation of aaRSs genes display significant phenotypic heterogeneity. We expand aaRSs-related phenotypes through characterization of the clinical and molecular basis of a novel autosomal-recessive syndrome manifesting severe mental retardation, ataxia, speech impairment, epilepsy, short stature, microcephaly, hypogonadism, and growth hormone deficiency.

Results

A G>A variant in exon 29 of VARS2 (c.3650G>A) (NM_006295) was identified in the index case. This homozygous variant was confirmed by Sanger sequencing and segregated with disease in the family studied. The c.3650G>A change results in alteration of arginine to histidine at residue 1217 (R1217H) of the mature protein and is predicted to be pathogenic.

Conclusions

These findings contribute to a growing list of aaRSs disorders, broadens the spectrum of phenotypes attributable to VARS2 mutations, and provides new insight into genotype-phenotype correlations among the mitochondrial synthetase genes.