5-Methylcytosine and 5-Hydroxymethylcytosine Spatiotemporal Profiles in the Mouse Zygote

Background: In the mouse zygote, DNA methylation patterns are heavily modified, and differ between the maternal and paternal pronucleus. Demethylation of the paternal genome has been described as an active and replication-independent process, although the mechanisms responsible for it remain elusive. Recently, 5-hydroxymethylcytosine has been suggested as an intermediate in this demethylation. Methodology/principal findings: In this study, we quantified DNA methylation and hydroxymethylation in both pronuclei of the mouse zygote during the replication period and we examined their patterns on the pericentric heterochromatin using 3D immuno-FISH. Our results demonstrate that 5-methylcytosine and 5-hydroxymethylcytosine localizations on the pericentric sequences are not complementary; indeed we observe no enrichment of either marks on some regions and an enrichment of both on others. In addition, we show that DNA demethylation continues during DNA replication, and is inhibited by aphidicolin. Finally, we observe notable differences in the kinetics of demethylation and hydroxymethylation; in particular, a peak of 5-hydroxymethylcytosine, unrelated to any change in 5-methylcytosine level, is observed after completion of replication. Conclusion/significance: Together our results support the already proposed hypothesis that 5-hydroxymethylcytosine is not a simple intermediate in an active demethylation process and could play a role of its own during early development

Sexually-Transmitted Disease in a Sub-Tropical Eucalypt Beetle: Infection of the Fittest?

The ecology of sexually-transmitted diseases (STDs) is topical in scientific research, and their demography and epidemiology differ from those of classical pathogens and parasites. Transmission of STDs is generally density-independent, occurs via the "fittest" individuals in a population (or, at least, those that achieve the most matings), and reflects differential mating success. STDs can therefore have a major influence on the evolution of host mating systems. We studied the epidemiology of a recently described STD of a chrysomelid beetle in applied and theoretical contexts, exploring the virulence, intensity and prevalence of infection, and using our results to test ecological predictions. Chrysophtharta cloelia is infected with a sexually-transmitted mite (the STD), Parobia captivus. Infection rate over three beetle generations (7 months) was determined and the STD’s effects on fertility, fecundity, longevity, mating success and overwintering survival was measured. Throughout the season around 40% of beetles were infected, with approximately one quarter of such hosts carrying infective life stages of the STD at any one time. Infection by P. captivus significantly decreased overwintering survival, but did not impact on other fitness parameters measured, including mate acceptance. However, more female beetles were infected than male beetles, while within both sexes larger beetles were more likely to be infected. Our results concur with theoretical predictions that STDs may be selected for low virulence and low detectability, while the observation of female bias in infection supports hypotheses regarding variable mating success and mating skews, which we discuss

Transforming growth factor-beta 1, macrophage inflammatory protein-1 alpha, and interleukin-8 gene expression is lower in stimulated human neonatal compared with adult mononuclear cells

Abstract Hematopoiesis is developmentally immature in the newborn compared with the adult. Diminished gene expression of several positive hematopoietic regulators has been observed in activated cord compared with adult peripheral blood mononuclear cells (MNC; Cairo et al. Pediatr Res, 30:362, 1991 and Cairo et al, Pediatr Res, 31:574, 1992). However, altered expression of negative hematopoietic regulators during states of increased demand may also contribute to the pathogenesis of newborn dyshematopoiesis. To test this hypothesis, we measured protein levels of transforming growth factor-beta 1 (TGF-beta 1) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) in the conditioned media of human umbilical cord and adult MNC using specific enzyme-linked immunosorbent assays. There was significantly less TGF-beta 1 in culture supernatants of cord versus adult MNC after 24, 72, and 120 hours of stimulation (P &lt; .05), and significantly less MIP-1 alpha in cord versus adult supernatants after 72 hours and 120 hours of stimulation (P &lt; .01). We then examined the mRNA expression of the negative regulators TGF-beta 1, MIP-1 alpha, and interleukin-8 (IL-8) in cord and adult MNC using Northern blot hybridization followed by quantitative densitometry. Cord MNC expressed significantly less TGF- beta 1 mRNA than adult MNC 6 hours and 72 hours after stimulation (P &lt; .001). Cord MNC expressed significantly less MIP-1 alpha mRNA than adult MNC 6 hours (P &lt; .01), 24 hours (P &lt; .001), and 72 hours after stimulation (P &lt; .001). Cord MNC also expressed significantly less IL-8 mRNA than adult MNC 6 hours after stimulation (P &lt; .001). Therefore, decreased mRNA accumulation appears to coincide with reduced cytokine expression in the activated cord MNC. There were no significant differences in the transcription rates determined by nuclear run-on assay of either the TGF-beta 1 or MIP-1 alpha gene in cord versus adult MNC after 6 hours of stimulation, suggesting that the reduced TGF-beta 1 and MIP-1 alpha mRNA in activated cord MNC may be secondary to alteration in posttranscriptional regulation. The present results, together with those of our previous studies, suggest that the altered expression of both positive and negative hematopoietic regulators may be involved in the immaturity of host defense in human neonates.</jats:p

Transforming growth factor-beta 1, macrophage inflammatory protein-1 alpha, and interleukin-8 gene expression is lower in stimulated human neonatal compared with adult mononuclear cells

Hematopoiesis is developmentally immature in the newborn compared with the adult. Diminished gene expression of several positive hematopoietic regulators has been observed in activated cord compared with adult peripheral blood mononuclear cells (MNC; Cairo et al. Pediatr Res, 30:362, 1991 and Cairo et al, Pediatr Res, 31:574, 1992). However, altered expression of negative hematopoietic regulators during states of increased demand may also contribute to the pathogenesis of newborn dyshematopoiesis. To test this hypothesis, we measured protein levels of transforming growth factor-beta 1 (TGF-beta 1) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) in the conditioned media of human umbilical cord and adult MNC using specific enzyme-linked immunosorbent assays. There was significantly less TGF-beta 1 in culture supernatants of cord versus adult MNC after 24, 72, and 120 hours of stimulation (P &lt; .05), and significantly less MIP-1 alpha in cord versus adult supernatants after 72 hours and 120 hours of stimulation (P &lt; .01). We then examined the mRNA expression of the negative regulators TGF-beta 1, MIP-1 alpha, and interleukin-8 (IL-8) in cord and adult MNC using Northern blot hybridization followed by quantitative densitometry. Cord MNC expressed significantly less TGF- beta 1 mRNA than adult MNC 6 hours and 72 hours after stimulation (P &lt; .001). Cord MNC expressed significantly less MIP-1 alpha mRNA than adult MNC 6 hours (P &lt; .01), 24 hours (P &lt; .001), and 72 hours after stimulation (P &lt; .001). Cord MNC also expressed significantly less IL-8 mRNA than adult MNC 6 hours after stimulation (P &lt; .001). Therefore, decreased mRNA accumulation appears to coincide with reduced cytokine expression in the activated cord MNC. There were no significant differences in the transcription rates determined by nuclear run-on assay of either the TGF-beta 1 or MIP-1 alpha gene in cord versus adult MNC after 6 hours of stimulation, suggesting that the reduced TGF-beta 1 and MIP-1 alpha mRNA in activated cord MNC may be secondary to alteration in posttranscriptional regulation. The present results, together with those of our previous studies, suggest that the altered expression of both positive and negative hematopoietic regulators may be involved in the immaturity of host defense in human neonates.</jats:p