Late Replication Domains in Polytene and Non-Polytene Cells of Drosophila melanogaster

In D. melanogaster polytene chromosomes, intercalary heterochromatin (IH) appears as large dense bands scattered in euchromatin and comprises clusters of repressed genes. IH displays distinctly low gene density, indicative of their particular regulation. Genes embedded in IH replicate late in the S phase and become underreplicated. We asked whether localization and organization of these late-replicating domains is conserved in a distinct cell type. Using published comprehensive genome-wide chromatin annotation datasets (modENCODE and others), we compared IH organization in salivary gland cells and in a Kc cell line. We first established the borders of 60 IH regions on a molecular map, these regions containing underreplicated material and encompassing ∼12% of Drosophila genome. We showed that in Kc cells repressed chromatin constituted 97% of the sequences that corresponded to IH bands. This chromatin is depleted for ORC-2 binding and largely replicates late. Differences in replication timing between the cell types analyzed are local and affect only sub-regions but never whole IH bands. As a rule such differentially replicating sub-regions display open chromatin organization, which apparently results from cell-type specific gene expression of underlying genes. We conclude that repressed chromatin organization of IH is generally conserved in polytene and non-polytene cells. Yet, IH domains do not function as transcription- and replication-regulatory units, because differences in transcription and replication between cell types are not domain-wide, rather they are restricted to small “islands” embedded in these domains. IH regions can thus be defined as a special class of domains with low gene density, which have narrow temporal expression patterns, and so displaying relatively conserved organization

The State of Specific Immunity to Measles and Rubella Virus in Newborns and their mothers

Objective: evaluate the passive specific immunity to measles and rubella in newborns and their mothers. Materials and metods: a study was made by the ELISA of the state of specific immunity to measles and rubella in 226 puerperas aged 15 to 44 without taking into account the vaccination status and their newborns in maternity hospitals in Moscow and Moscow Region. Results - the seropositive of measles proportion - 73.9 ± 2.9%, the rubella - 84.5 ± 2.4%. Comparison of the results of the study of immunity to rubella in puerperas and newborns with the results of previous years did not reveal any significant differences. The results of the examination of 226 newborns for the presence of antibodies to the rubella virus showed that the proportion of seropositive measles to the virus turned out to be 177 (78.3 ± 2.7%) children, rubella - 83.6 ± 2.4%, comparable to results of a survey of their mothers. Conclusion: high level of protection of the puerperas and their newborns from these infections. However, the organization and carrying out of vaccinations requires increased attention and control, since only high and timely coverage with vaccinations will prevent the increase in the incidence of infection when meeting with the pathogen of infection, including children of the first year of life