Codependency of H2B monoubiquitination and nucleosome reassembly on Chd1

Monoubiquitination of histone H2B on Lys 123 (H2BK123ub) is a transient histone modification considered to be essential for establishing H3K4 and H3K79 trimethylation by Set1/COMPASS and Dot1, respectively. Here, we identified Chd1 as a factor that is required for the maintenance of high levels of H2B monoubiquitination, but not for H3K4 and H3K79 trimethylation. Loss of Chd1 results in a substantial loss of H2BK123ub levels with little to no effect on the genome-wide pattern of H3K4 and H3K79 trimethylation. Our data show that nucleosomal occupancy is reduced in gene bodies in both chd1Δ and, as has been shown, K123A mutant backgrounds. We also demonstrated that Chd1's function in maintaining H2BK123ub levels is conserved from yeast to humans. Our study provides evidence that only small levels of H2BK123ub are necessary for full levels of H3K4 and H3K79 trimethylation in vivo and points to a possible role for Chd1 in positively regulating gene expression through promoting nucleosome reassembly coupled with H2B monoubiquitination.     

Gay and Bisexual Men’s Views on Rapid Self-Testing for HIV

Thirty-one gay and bisexual men were interviewed on the acceptability, potential use, benefits and limitations of rapid self-testing for HIV in Australia. The majority of men supported the introduction of rapid self-testing, and would be likely to, or would use the tests for home use. However, most reported they would use them for interim testing and not to replace conventional blood testing at health services as they could not detect other sexually transmitted infections or provide the professional expertise and support provided at health services.     

Identification of very early lymphoid precursors in bone marrow and their regulation by estrogen

Estrogen is a negative regulator of lymphopoiesis and provides an experimental tool for probing relationships between lymphocyte precursors and stem cells. We found that expression of lymphocyte-associated genes and immunoglobulin (Ig) gene rearrangement occurred before CD45R acquisition. Lymphoid-restricted progenitors that were Lin(-)IL-7R alpha(+)c-kit(lo)TdT(+) (lineage marker(-), interleukin receptor 7 alpha(+), c-kit(lo) and terminal deoxynucleotidyl transferase(+)) were selectively depleted in estrogen-treated mice; within a less differentiated Lin-c-kit(hi) fraction, functional precursors of B and T, but not myeloid, cells were also selectively depleted. TdT and an Ig heavy chain transgene were detected within a hormone-regulated Lin(-)c-kit(hi)Sca-1(+)CD27(+)Flk-2(+)IL-7R alpha(-) subset of this multipotential progenitor population. Identification of these extremely early lymphoid precursors should facilitate investigation of the molecular mechanisms that control lineage-fate decisions in hematopoiesis.     

Sequences and replication of genomes of the archaeal rudiviruses SIRV1 and SIRV2: relationships to the archaeal lipothrixvirus SIFV and some eukaryal viruses

The double-stranded DNA genomes of the viruses SIRV1 and SIRV2, which infect the extremely thermophilic archaeon Sulfolobus and belong to the family Rudiviridae, were sequenced. They are linear, covalently closed at the ends, and 32,312 and 35,502 bp long, respectively, with an A+T content of 75%. The genomes of SIRV1 and SIRV2 carry inverted terminal repeats of 2029 and 1628 bp, respectively, which contain multiple direct repeats. SIRV1 and SIRV2 genomes contain 45 and 54 ORFs, respectively, of which 44 are homologous to one another. Their predicted functions include a DNA polymerase, a Holliday junction resolvase, and a dUTPase. The genomes consist of blocks with well-conserved sequences separated by nonconserved sequences. Recombination, gene duplication, horizontal gene transfer, and substitution of viral genes by homologous host genes have contributed to their evolution. The finding of head-to-head and tail-to-tail linked replicative intermediates suggests that the linear genomes replicate by the same mechanism as the similarly organized linear genomes of the eukaryal poxviruses, African swine fever virus and Chlorella viruses. SIRV1 and SIRV2 both contain motifs that resemble the binding sites for Holliday junction resolvases of eukaryal viruses and may use common mechanisms for resolution of replicative intermediates. The results suggest a common origin of the replication machineries of the archaeal rudiviruses and the above-mentioned eukaryal viruses. About 1/3 of the ORFs of each rudivirus have homologs in the Sulfolobus virus SIFV of the family Lipothrixviridae, indicating that the two viral families form a superfamily. The finding of inverted repeats of at least 0.8 kb at the termini of the linear genome of SIFV supports this inference.     

Strong Signature of Natural Selection within an FHIT Intron Implicated in Prostate Cancer Risk

Previously, a candidate gene linkage approach on brother pairs affected with prostate cancer identified a locus of prostate cancer susceptibility at D3S1234 within the fragile histidine triad gene (FHIT), a tumor suppressor that induces apoptosis. Subsequent association tests on 16 SNPs spanning approximately 381 kb surrounding D3S1234 in Americans of European descent revealed significant evidence of association for a single SNP within intron 5 of FHIT. In the current study, re-sequencing and genotyping within a 28.5 kb region surrounding this SNP further delineated the association with prostate cancer risk to a 15 kb region. Multiple SNPs in sequences under evolutionary constraint within intron 5 of FHIT defined several related haplotypes with an increased risk of prostate cancer in European-Americans. Strong associations were detected for a risk haplotype defined by SNPs 138543, 142413, and 152494 in all cases (Pearson's χ²=12.34, df 1, P=0.00045) and for the homozygous risk haplotype defined by SNPs 144716, 142413, and 148444 in cases that shared 2 alleles identical by descent with their affected brothers (Pearson's χ²=11.50, df 1, P=0.00070). In addition to highly conserved sequences encompassing SNPs 148444 and 152413, population studies revealed strong signatures of natural selection for a 1 kb window covering the SNP 144716 in two human populations, the European American (π=0.0072, Tajima's D=3.31, 14 SNPs) and the Japanese (π=0.0049, Fay & Wu's H=8.05, 14 SNPs), as well as in chimpanzees (Fay & Wu's H=8.62, 12 SNPs). These results strongly support the involvement of the FHIT intronic region in an increased risk of prostate cancer.     

Comparison of carbon fibre and aluminium materials in the construction of ultralight wheelchairs

Abstract

Carbon fibre-reinforced polymers have been used in the sporting goods industry for decades, and wheelchairs have incorporated the material since the late 1980s. There is no independently collected data available on carbon fibre-reinforced polymer wheelchairs’ performance on the ANSI/RESNA testing standards, however. This study evaluated three full carbon fibre wheelchair specimens to determine their performance versus similar wheelchairs. Testing determined that while the frames survived more testing cycles than any other wheelchair, the casters and rear tires failed similarly to other devices. Overall, due to the purchase cost, the cost benefit of the tested wheelchair model was similar to aluminium wheelchairs.

• Implications for rehabilitation

• Carbon fibre wheelchair construction is a viable alternative to aluminium, titanium, or steel construction, and decreasing costs will continue to improve the benefits of carbon fibre over these models

• Carbon fibre wheelchair found to be more durable than aluminium models, but are also much more expensive. The additional cost may be justified for some users that need the increased durability, however

• Increased durability will reduce the number of repairs and warranty claims, potentially reducing the burden on a wheelchair user, and also improving their ability to travel and participate in their community

• The low weight of carbon fibre wheelchairs may increase the mobility of some users by allowing them to transfer more easily into and out of vehicles and manoeuvre throughout the environment

     

Influenza virus-infected dendritic cells stimulate strong proliferative and cytolytic responses from human CD8+ T cells.

Antigen-specific, CD8+, cytolytic T lymphocytes (CTLs) could potentially provide resistance to several infectious and malignant diseases. However, the cellular requirements for the generation of specific CTLs in human lymphocyte cultures are not well defined, and repetitive stimulation with antigen is often required. We find that strong CD8+ CTL responses to influenza virus can be generated from freshly isolated blood T cells, as long as dendritic cells are used as antigen presenting cells (APCs). Small numbers of dendritic cells (APC:T cell ratio of 1:50-1:100) induce these CTL responses from most donors in 7 d of culture, but monocytes are weak or inactive. Whereas both dendritic cells and monocytes are infected with influenza virus, the former serve as effective APCs for the induction of CD8+ T cells while the latter act as targets for the CTLs that are induced. The strong CD8+ response to influenza virus-infected dendritic cells is accompanied by extensive proliferation of the CD8+ T cells, but the response can develop in the apparent absence of CD4+ helpers or exogenous lymphokines. CD4+ influenza virus-specific CTLs can also be induced by dendritic cells, but the cultures initially must be depleted of CD8+ cells. These findings should make it possible to use dendritic cells to generate human, antigen-specific, CD8+ CTLs to other targets. The results illustrate the principle that efficient T cell-mediated responses develop in two stages: an afferent limb in which dendritic cells are specialized APCs and an efferent limb in which the primed T cells carry out an immune response to many types of presenting cells.     

Mass spectrometry analysis of urine and catheter of a patient with purple urinary bag syndrome

INTRODUCTION: Purple urinary bag syndrome (PUBS) is considered to be a benign condition observed in the urinary catheter and bag in some catheterized patients with urinary tract infections. This syndrome is usually reported to occur in alkaline urine. CASE REPORT: We report of a catheterized patient with PUBS and slightly acidic urine (pH 6-6.5). A novel analysis method was developed using high pressure liquid chromatography and mass spectrometry (HPLC/MS) to detect compounds that are thought to be associated with PUBS. Urine, urinary sediment, and the plastic collection system were assayed and quantitated using these methods. The potential toxicity of one of these compounds, indoxyl sulfate, is discussed. CONCLUSIONS: The presence of PUBS in a catheterized patient with slightly acidic urine is reported. A novel method for the analysis of chemical components of PUBS and the first direct confirmation of the presence of indigo in the urine sediment and collecting system are described.