A qualitative analysis of a model for the transmission of varicella-zoster virus

Varicella-zoster virus (VZV) is a herpesvirus which is the known agent for causing varicella (chickenpox) in its initial manifestation and zoster (shingles) in a reactivated state. The standard SEIR compartmental model is modified to include the cycle of shingles acquisition, recovery, and possible reacquisition. The basic reproduction number R(0) shows the influence of the zoster cycle and how shingles can be important in maintaining VZV in populations. The model has the typical threshold behavior in the sense that when R(0)1, the virus persists over time and so chickenpox and shingles remain endemic.     

Permanent spore dyads are not ‘a thing of the past’: on their occurrence in the liverwort Haplomitrium (Haplomitriopsida)

The liverwort Haplomitrium gibbsiae is shown to regularly produce spores released in the form of permanent dyad pairs. Developmental studies indicate that the dyads are produced via a unique half‐lobed configuration of the developing sporocyte. Many fossil cryptophytes of Siluro‐Devonian age, which are clearly embryophytes based on their morphology, contain permanent spore dyads in their sporangia, but this is the first demonstration of their occurrence in a living plant, a species belonging to Haplomitriopsida, which resolves in a clade that is considered to be sister to all remaining liverworts. Dispersed spore‐like dyads are found in the rock record as far back as the mid‐Cambrian, but most researchers still regard the first occurrence of isomorphic, tetrahedral tetrads in the mid‐Ordovician as the benchmark age for the origin of land plants. Regardless of the geological antiquity of the embryophytes, it appears that H. gibbsiae has retained a non‐simultaneous form of sporogenesis that may ultimately be traced to a charophytic origin. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 658–669.     

Hon-yaku: a biology-driven Bayesian methodology for identifying translation initiation sites in prokaryotes

Background  

Computational prediction methods are currently used to identify genes in prokaryote genomes. However, identification of the correct translation initiation sites remains a difficult task. Accurate translation initiation sites (TISs) are important not only for the annotation of unknown proteins but also for the prediction of operons, promoters, and small non-coding RNA genes, as this typically makes use of the intergenic distance. A further problem is that most existing methods are optimized for Escherichia coli data sets; applying these methods to newly sequenced bacterial genomes may not result in an equivalent level of accuracy.     

Conserving large populations of lions – the argument for fences has holes

Packer et al. reported that fenced lion populations attain densities closer to carrying capacity than unfenced populations. However, fenced populations are often maintained above carrying capacity, and most are small. Many more lions are conserved per dollar invested in unfenced ecosystems, which avoid the ecological and economic costs of fencing.     

The glycosphingolipidoses-from disease to basic principles of metabolism.

The glycosphingolipidoses are a set of diseases that are caused by defects in the lysosomal degradation of glycolipids derived from the plasma membrane. By investigating the molecular bases of the diseases, basic principles of storage disease pathology and of membrane digestion were discovered. The generation of mouse models has facilitated the development of new and promising therapeutic strategies for these diseases, most of which are not treatable at present. Lately, the discovery of the importance of glycosphingolipid metabolism for skin development has opened a new and interesting field.     

Complete analysis of the glycosylation and disulfide bond pattern of human beta-hexosaminidase B by MALDI-MS.

beta-hexosaminidase B is an enzyme that is involved in the degradation of glycolipids and glycans in the lysosome. Mutation in the HEXB gene lead to Sandhoff disease, a glycolipid storage disorder characterized by severe neurodegeneration. So far, little structural information on the protein is available. Here, the complete analysis of the disulfide bond pattern of the protein is described for the first time. Additionally, the structures of the N-glycans are analyzed for the native human protein and for recombinant protein expressed in SF21 cells. For the analysis of the disulfide bond structure, the protein was proteolytically digested and the resulting peptides were analyzed by MALDI-MS. The analysis revealed three disulfide bonds (C91-C137; C309-C360; C534-C551) and a free cysteine (C487). The analysis of the N-glycosylation was performed by tryptic digestion of the protein, isolation of glycopeptides by lectin chromatography and mass measurement before and after enzymatic deglycosylation. Carbohydrate structures were calculated from the mass difference between glycosylated and deglycosylated peptide. For beta-hexosaminidase B from human placenta, four N-glycans were identified and analyzed, whereas the recombinant protein expressed in SF21 cells carried only three glycans. In both cases the glycosylation belongs to the mannose-core- or high-mannose-type, and some carbohydrate structures are fucosylated.     

Closed loop television tracking of beating heart cells in vitro

The motion of beating heart cells in vitro has been used as a sensitive indicator of the presence of drugs. The combination of closed loop television video tracking and latex microspheres placed on the cells as markers results in an improved measurement of cell motion. Latex microspheres, 5.2 micrometers, are allowed to settle onto beating myocardial heart cells in vitro, where they move in concert with the cell motion. These microspheres, when viewed by televised transmission microscopy with normal optics, present high contrast circular targets that are excellent for closed loop television video tracking techniques. With video tracking, an analog voltage is generated proportional to the horizontal center of intensity of the target being tracked. This signal represents the location of a video demodulator gate that is maintained centered over the video target by feedback control.     

Non-synonymous polymorphisms in the P2RX 4 are related to bone mineral density and osteoporosis risk in a cohort of Dutch fracture patients

In the present study we investigated whether single nucleotide polymorphisms (SNPs) in the P2RX₄, which alter the P2X₄R function, are associated with the development of osteoporosis and whether an interaction between the P2X₄R and P2X₇R confer a synergistic effect of these two receptors on osteoporosis risk. Patients with fracture (690 females and 231 males, aged ≥50 years) were genotyped for three non-synonymous P2X₄R SNPs. Bone mineral density (BMD) was measured at the total hip, lumbar spine, and femoral neck. Subject carrying the variant allele of the Tyr315Cys polymorphism showed a 2.68-fold (95 % CI, 1.20–6.02) higher risk of osteoporosis compared with wild-type subject. Furthermore, significant lower lumbar spine BMD values were observed in subjects carrying the Cys315 allele as compared with wild-type (0.85 ± 0.17 and 0.93 ± 0.17 g/cm², respectively; p < 0.001). Assuming a recessive model, carriers of the variant allele of the Ser242Gly polymorphism showed increased BMD values at the lumbar spine compare to wild-type subject (1.11 ± 0.35 and 0.92 ± 0.17 g/cm², respectively; p = 0.0045). This is the first study demonstrating an association of non-synonymous polymorphisms in the P2RX₄ and the risk of osteoporosis, suggesting a role of the P2X₄R in the regulation of bone mass.

Electronic supplementary material

The online version of this article (doi:10.1007/s11302-012-9337-0) contains supplementary material, which is available to authorized users.