Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees

email Suzanne orcd idCopyright: © 2015 Williams et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Commentary: mechanistic considerations for associations between formaldehyde exposure and nasopharyngeal carcinoma

Occupational exposure to formaldehyde has been linked to nasopharyngeal carcinoma. To date, mechanistic explanations for this association have primarily focused on formaldehyde-induced cytotoxicity, regenerative hyperplasia and DNA damage. However, recent studies broaden the potential mechanisms as it is now well established that formaldehyde dehydrogenase, identical to S-nitrosoglutathione reductase, is an important mediator of cGMP-independent nitric oxide signaling pathways. We have previously described mechanisms by which formaldehyde can influence nitrosothiol homeostasis thereby leading to changes in pulmonary physiology. Considering evidences that nitrosothiols govern the Epstein-Barr virus infection cycle, and that the virus is strongly implicated in the etiology of nasopharyngeal carcinoma, studies are needed to examine the potential for formaldehyde to reactivate the Epstein-Barr virus as well as additively or synergistically interact with the virus to potentiate epithelial cell transformation

Allele-Independent Turnover of Human Leukocyte Antigen (HLA) Class Ia Molecules.

Major histocompatibility complex class I (MHCI) glycoproteins present cytosolic peptides to CD8+ T cells and regulate NK cell activity. Their heavy chains (HC) are expressed from up to three MHC gene loci (human leukocyte antigen [HLA]-A, -B, and -C in humans), whose extensive polymorphism maps predominantly to the antigen-binding groove, diversifying the bound peptide repertoire. Codominant expression of MHCI alleles is thus functionally critical, but how it is regulated is not fully understood. Here, we have examined the effect of polymorphism on the turnover rates of MHCI molecules in cell lines with functional MHCI peptide loading pathways and in monocyte-derived dendritic cells (MoDCs). Proteins were labeled biosynthetically with heavy water (2H2O), folded MHCI molecules immunoprecipitated, and tryptic digests analysed by mass spectrometry. MHCI-derived peptides were assigned to specific alleles and isotypes, and turnover rates quantified by 2H incorporation, after correcting for cell growth. MHCI turnover half-lives ranged from undetectable to a few hours, depending on cell type, activation state, donor, and MHCI isotype. However, in all settings, the turnover half-lives of alleles of the same isotype were similar. Thus, MHCI protein turnover rates appear to be allele-independent in normal human cells. We propose that this is an important feature enabling the normal function and codominant expression of MHCI alleles

Comparison of the structure and DNA-binding properties of the E2 proteins from an oncogenic and a non-oncogenic human papillomavirus

Human papillomaviruses (HPVs) that infect the genital tract can be divided into two groups: high-risk HPV types, such as HPV 16 and HPV 18, are associated with cancer, low-risk HPV types, such as HPV 6, are associated with benign warts. In both high-risk and low-risk HPV types, the papillomavirus E2 protein binds to four sites within the viral long control region (LCR) and regulates viral gene expression. Here, we present the crystal structure of the minimal DNA-binding domain (DBD) from the HPV 6 E2 protein. We show that the HPV 6 E2 DBD is structurally more similar to the HPV 18 and bovine papillomavirus type 1 (BPV1) E2 proteins than it is to the HPV 16 E2 protein. Using gel retardation assays, we show that the hierarchy of E2 sites within the HPV 16 and HPV 6 LCRs are different. However, despite these differences in structure and site preference, both the HPV 16 and 6 E2 DBDs recognise an extended version of the consensus E2 binding site derived from studies of the BPV1 E2 protein. In both cases, the preferred binding site is where the additional flanking base-pairs are in bold and N4 represents a four base-pair central spacer. Both of these HPV proteins bind preferentially to E2 sites that contain an A:T-rich central spacer. We show that the preference for an A:T-rich central spacer is due, at least in part, to the need to adopt a DNA conformation that facilitates protein contacts with the flanking base-pairs

Zooplankton-associated and free-living bacteria in the York River, Chesapeake Bay: comparison of seasonal variations and controlling factors

Trace caches deliver a high number of instructions per cycle to wide-issue superscalar processors. To overcome complex control flow, multiple branch predictors have to predict up to 3 conditional branches per cycle. These multiple branch predictors sometimes predict completely wrong paths of execution, degrading the average fetch bandwidth. This paper shows that such mispredictions can be detected by monitoring trace cache misses. Based on this observation, a new technique called trace substitution is introduced. On a trace cache miss, trace substitution overrides the predicted trace with a cached trace. If the substitution is correct, the fetch bandwidth increases. We show that trace substitution consistently improves the fetch bandwidth with 0.2 instructions per access. For inaccurate predictors, trace substitution can increase the fetch bandwidth with up to 2 instructions per access