Ontogeny-Driven rDNA Rearrangement, Methylation, and Transcription, and Paternal Influence

Gene rearrangement occurs during development in some cell types and this genome dynamics is modulated by intrinsic and extrinsic factors, including growth stimulants and nutrients. This raises a possibility that such structural change in the genome and its subsequent epigenetic modifications may also take place during mammalian ontogeny, a process undergoing finely orchestrated cell division and differentiation. We tested this hypothesis by comparing single nucleotide polymorphism-defined haplotype frequencies and DNA methylation of the rDNA multicopy gene between two mouse ontogenic stages and among three adult tissues of individual mice. Possible influences to the genetic and epigenetic dynamics by paternal exposures were also examined for Cr(III) and acid saline extrinsic factors. Variables derived from litters, individuals, and duplicate assays in large mouse populations were examined using linear mixed-effects model. We report here that active rDNA rearrangement, represented by changes of haplotype frequencies, arises during ontogenic progression from day 8 embryos to 6-week adult mice as well as in different tissue lineages and is modifiable by paternal exposures. The rDNA methylation levels were also altered in concordance with this ontogenic progression and were associated with rDNA haplotypes. Sperm showed highest level of methylation, followed by lungs and livers, and preferentially selected haplotypes that are positively associated with methylation. Livers, maintaining lower levels of rDNA methylation compared with lungs, expressed more rRNA transcript. In vitro transcription demonstrated haplotype-dependent rRNA expression. Thus, the genome is also dynamic during mammalian ontogeny and its rearrangement may trigger epigenetic changes and subsequent transcriptional controls, that are further influenced by paternal exposures

Serum S100A6 Concentration Predicts Peritoneal Tumor Burden in Mice with Epithelial Ovarian Cancer and Is Associated with Advanced Stage in Patients

BACKGROUND:Ovarian cancer is the 5th leading cause of cancer related deaths in women. Five-year survival rates for early stage disease are greater than 94%, however most women are diagnosed in advanced stage with 5 year survival less than 28%. Improved means for early detection and reliable patient monitoring are needed to increase survival. METHODOLOGY AND PRINCIPAL FINDINGS:Applying mass spectrometry-based proteomics, we sought to elucidate an unanswered biomarker research question regarding ability to determine tumor burden detectable by an ovarian cancer biomarker protein emanating directly from the tumor cells. Since aggressive serous epithelial ovarian cancers account for most mortality, a xenograft model using human SKOV-3 serous ovarian cancer cells was established to model progression to disseminated carcinomatosis. Using a method for low molecular weight protein enrichment, followed by liquid chromatography and mass spectrometry analysis, a human-specific peptide sequence of S100A6 was identified in sera from mice with advanced-stage experimental ovarian carcinoma. S100A6 expression was documented in cancer xenografts as well as from ovarian cancer patient tissues. Longitudinal study revealed that serum S100A6 concentration is directly related to tumor burden predictions from an inverse regression calibration analysis of data obtained from a detergent-supplemented antigen capture immunoassay and whole-animal bioluminescent optical imaging. The result from the animal model was confirmed in human clinical material as S100A6 was found to be significantly elevated in the sera from women with advanced stage ovarian cancer compared to those with early stage disease. CONCLUSIONS:S100A6 is expressed in ovarian and other cancer tissues, but has not been documented previously in ovarian cancer disease sera. S100A6 is found in serum in concentrations that correlate with experimental tumor burden and with clinical disease stage. The data signify that S100A6 may prove useful in detecting and/or monitoring ovarian cancer, when used in concert with other biomarkers

Elaboración de biofertilizante a base de Rhizobium spp. en campo zacatecano

Los biofertilizantes son preparados de microorganismos aplicados al suelo y/o planta con el fin de sustituir parcial o totalmente la fertilización sintética, así como disminuir la contaminación generada por los agroquímicos (Armenta, García et al. 2010). Desde un punto de vista ecológico los fijadores del nitrógeno más importantes son aquellos que fijan en asociación con una planta, porque el Nitrógeno fijado es suministrado precisamente donde se necesita: pegado a las raíces de la planta (Postgate, 1981)

Pharmacological Analysis of Drosophila melanogaster γ-Secretase with Respect to Differential Proteolysis of Notch and APP

The γ-secretase aspartyl protease is responsible for the cleavage of numerous type I integral membrane proteins, including amyloid precursor protein (APP) and Notch. APP cleavage contributes to the generation of toxic amyloid β peptides in Alzheimer's disease, whereas cleavage of the Notch receptor is required for normal physiological signaling between differentiating cells. Mutagenesis studies as well as in vivo analyses of Notch and APP activity in the presence of pharmacological inhibitors indicate that these substrates can be differentially modulated by inhibition of mammalian γ-secretase, although some biochemical studies instead show nearly identical dose-response inhibitor effects on Notch and APP cleavages. Here, we examine the dose-response effects of several inhibitors on Notch and APP in Drosophila melanogaster cells, which possess a homogeneous form of γ-secretase. Four different inhibitors that target different domains of γ-secretase exhibit similar dose-response effects for both substrates, including rank order of inhibitor potencies and effective concentration ranges. For two inhibitors, modest differences in inhibitor dose responses toward Notch and APP were detected, suggesting that inhibitors might be identified that possess some discrimination in their ability to target alternative γ-secretase substrates. These findings also indicate that despite an overall conservation in inhibitor potencies toward different γ-secretase substrates, quantitative differences might exist that could be relevant for the development of therapeutically valuable substrate-specific inhibitors

Detection of S100A6 in serum over time from mice with OVCA, in association with estimated peritoneal cavity tumor burden.

<p>(A) Photon flux measurements obtained from mice harboring defined numbers of bioluminescent SKOV-3-Luc cells within the peritoneal cavity. Regression analysis was performed on (log₁₀) photon output vs. (log₁₀) numbers of inoculated cells to produce a standard calibration curve using an inverse prediction equation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007670#s4" target="_blank">Materials and Methods</a>). This was used to predict tumor burden from photon flux measurements (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007670#pone-0007670-g006" target="_blank">figure 6C</a>). (B) Comparisons of serum S100A6 in tumor-bearing (T, closed circles) and saline-inoculated control mice (SC, open circles). Serum S100A6 concentrations, tested as individual specimens from multiple mice by ECLISA (plotted as individual values with horizontal line at median value), were significantly different between T vs. SC at each of three times tested post inoculation, 9 days (p = 0.015), 15 days (p = 0.036), and 21 days (p = 0.0031) (Wilcoxon Rank Sum test). (C) Correlation between estimate of tumor burden in OVCA carcinomatosis and concentration of serum S100A6, as measured by ECLISA from tumor-bearing mice (r = 0.79, p<0.0001).</p

Reverse phase protein micorarray data obtained from the analysis of diagnostic sera from women with OVCA.

<p>Scatterplot displays relative intensity of serum S100A6 values for women with early stage (open circles, n = 23) and advanced stage (closed circles, n = 43) OVCA. The early stage disease group includes 2 tumors diagnosed as borderline OVCA. The means of the relative intensity values of the analyte concentrations shown (horizontal lines) are significantly different for the two groups (p = 0.031, two-sample t-test), and depict relatively greater mean S100A6 concentration in sera of advanced stage patients.</p

Experimental strategy to use MS discovery proteomics in low molecular weight (LMW) serum fraction from a mouse model of human ovarian cancer.

<p>To determine whether cancer-derived proteins have candidate biomarker potential, (A) a bioluminescent xenograft model, (B) ECLISA, (C) Western blot, and (D) OVCA tissue array immunohistochemistry (IHC) are utilized. This was followed up for S100A6 by analysis of human patient sera.</p