Histone H2B Ubiquitylation Is Not Required for Histone H3 Methylation at Lysine 4 in Tetrahymena

Ubiquitylation of histone H2B and/or a component of the system that ubiquitylates H2B is required for methylation of histone H3 at lysine 4 (H3K4) in yeasts and probably in humans. In this study, the single ubiquitylation site was mapped to conserved lysine 115 of the C-terminal region of histone H2B in the single-cell model organism Tetrahymena thermophila. In strains lacking H2B ubiquitylation, H3K4 methylation was not detectably affected. As in other organisms, the E2 ubiquitin-conjugating enzyme Ubc2 and the E3 ubiquitin ligase Bre1 were required for H2B ubiquitylation. However, neither enzyme was required for H3K4 methylation. These studies argue that, in T. thermophila, the histone ubiquitylation mechanism is not required for H3K4 methylation, demonstrating that different organisms can speak different languages in the “cross-talk” among post-translational modifications on different histones.     

Probing lethal damage expression in cytochalasin B-induced polykaryons by radiation quality

The polykaryon-forming unit (PFU) cell survival assay is based on the postirradiation flow cytometric analysis of the DNA content accumulated in high-ploidy cells (polykaryons) induced by the cytokinesis inhibitor cytochalasin B and can provide a meaningful measure of cell radiosensitivity. In this assay, cell survival is defined as the ability to form a polykaryon of a given ploidy after irradiation. The slope of the polykaryon dose response has been shown to be highly correlated with the initial slope of the clonogenic survival curves after gamma irradiation, which implies a common subset of lethal lesions. We reported previously on an apoptotic mode of cell death in the polykaryon system and on the heritability of small variations in polykaryon radioresponse. We now show that exposure of PFUs to a given dose of alpha particles results in a greater reduction in the proportion of cells able to reach at least 16C when compared to the same dose of low-LET radiation. This reduction is less than that observed in the low-dose (alpha term) region of the clonogenic curve. On the basis of published LET-dependent spectra of radiation-induced DNA damage, we suggest that this behavior reflects a differential expression of lethal damage that can be probed by varying the LET of the radiation and that base damages contributing additional complexity to clustered DNA lesions may be more deleterious in PFUs than in clonogens.     

Individual and multi-environment combined analyses identify QTLs for morphogenetic and reproductive development traits in white clover (Trifolium repens L.)

White clover (Trifolium repens L.) is a key component legume of temperate pasture agriculture and an important target for molecular marker-assisted plant breeding. A genetic map of white clover has been used to assess genetic control of agronomically important traits that vary in the F₂(I.4R×I.5J) mapping family. Phenotypic analysis was performed for a range of vegetative morphogenesis traits (such as leaf area, internode length, plant height and plant spread) and reproductive morphogenesis and development traits (such as flowering date, floral intensity and seed yield), with both spatial and temporal replication. A multi-environment combined analysis (combined analysis) has been performed for traits assessed across multiple experimental datasets in order to identify consistent genetic effects. Quantitative trait locus (QTLs) were detected for the majority of traits, and the locations and magnitudes of QTL effects were compared between individual and combined analyses. This molecular genetic dissection of agronomic traits in white clover provides the basis for equivalent studies in more complex populations, design of marker-assisted selection strategies and comparative genetics with model legume species. Selection for QTLs derived from the combined analysis will permit robust improvement of phenotypic traits over different environments.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Susceptibility of greater sage-grouse to experimental infection with West Nile virus

Populations of greater sage-grouse (Centrocercus urophasianus) have declined 45-80% in North America since 1950. Although much of this decline has been attributed to habitat loss, recent field studies have indicated that West Nile virus (WNV) has had a significant negative impact on local populations of grouse. We confirm the susceptibility of greater sage-grouse to WNV infection in laboratory experimental studies. Grouse were challenged by subcutaneous injection of WNV (10(3.2) plaque-forming units [PFUs]). All grouse died within 6 days of infection. The Kaplan-Meier estimate for 50% survival was 4.5 days. Mean peak viremia for nonvaccinated birds was 10(6.4) PFUs/ml (+/-10(0.2) PFUs/ml, standard error of the mean [SEM]). Virus was shed cloacally and orally. Four of the five vaccinated grouse died, but survival time was increased (50% survival=9.5 days), with 1 grouse surviving to the end-point of the experiment (14 days) with no signs of illness. Mean peak viremia for the vaccinated birds was 10(2.3) PFUs/ml (+/-10(0.6) PFUs/ml, SEM). Two birds cleared the virus from their blood before death or euthanasia. These data emphasize the high susceptibility of greater sage-grouse to infection with WNV.     

Evidence that protein length expansion and contraction is partly due to mutational events in premeiotic cells

Studies on the rate of evolution of proteins typically concentrate on rates of change of orthologous amino acids rather than on changes in size (i.e., generation of nonorthologous domains). Recent work has focused attention on Ser/Thr-rich regions in yeast as these tend to undergo size changes rapidly, with size polymorphisms commonly being found, especially in proteins with cell-surface localization. The underlying mechanism generating the indels is presently unclear though, due to a lack of correlation with the location of meiotic double-strand breaks, it has, by exclusion, been conjectured to be replication slippage. Here we provide new evidence to support this possibility. Notably, we show that Ser/Thr-rich repeat regions are more generally associated with the location of Mre11p in premeiotic cells. This is to be expected if the repeats were produced by mutational events in mitotic cells possibly through replication slippage.     

Antioxidant activity in vitro of the selenium-contained protein from the Se-enriched Bifidobacterium animalis 01

Several studies indicated that bifidobacteria possessed strong antioxidant activity. In present study, the antioxidant activities of Bifidobacterium animalis 01 proteins were evaluated using six assays, namely, linoleic acid preoxidation assay, erythrocyte hemolysis assay, 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, reducing power assay, hydroxyl (OH) and superoxide radicals (O₂^?) assays, in which the last two assays were measured by electron spin resonance (ESR). There were two kinds of B. animalis 01 proteins in this study, the regular B. animalis 01 protein (Pro-CK) and the B. animalis 01 selenium-contained protein (Pro-Se). Both Pro-CK and Pro-Se showed concentration dependent antioxidant activity in DPPH assay, reducing power assay and erythrocyte hemolysis assay. All results of six assays indicated that the antioxidant activity of the B. animalis 01 protein was improved remarkably after selenium was incorporated. The antioxidant activity of Pro-Se increased with the increase of selenium content in Pro-Se suggesting selenium played a positive role in enhancing the antioxidant activity of B. animalis 01 protein. Moreover, organic selenium was more effective than inorganic selenium on enhancing the hydroxyl radical scavenging ability of B. animalis 01 protein.     

Use of cervicovaginal fluid for the identification of biomarkers for pathologies of the female genital tract

Cervicovaginal fluid has an important function in the homeostasis and immunity of the lower female genital tract. Analysis of the cervicovaginal fluid proteome may therefore yield important information about the pathogenesis of numerous gynecological pathologies. Additionally, cervicovaginal fluid has great potential as a source of biomarkers for these conditions.