Histone 3 lysine 9 acetylation is a biomarker of the effects of culture on zygotes

Acetylation of histone proteins is a major determinant of chromatin structure and function. Fertilisation triggers a round of chromatin remodelling that prepares the genome for the first round of transcription from the new embryonic genome. In this study we confirm that fertilisation leads to a marked progressive increase in the level of histone 3 lysine 9 acetylation in both the paternally and maternally derived genomes. The culture of zygotes in simple defined media caused a marked increase in the global level of acetylation and this affected the male pronucleus more than the female. The culture created a marked asymmetry in staining between the two pronuclei that was not readily detected in zygotes collected directly from the reproductive tract and was ameliorated to some extent by optimized culture media. The increased acetylation caused by culture resulted in increased transcription of Hspa1b, a marker of embryonic genome activation. Pharmacological analyses showed the hyperacetylation of H3K9 and the increased expression of Hspa1b caused by culture were due to the altered net activity of a range of histone acetylases and deacetylases. The marked hyperacetylation of histone 3 lysine 9 caused by culture of zygotes may serve as an early biomarker for the effects of culture on the normal function of the embryo. The results also provide further evidence for an effect of the stresses associated with assisted reproductive technologies on the normal patterns of epigenetic reprogramming in the early embryo.

Gating strategy for immunophenotyping of leukemia and lymphoma

Clinical specimens of blood, bone marrow, lymph node, extranodal tissue, and body fluid were collected from 67 cases of hematologic neoplasms (including chronic lymphoid leukemias, T- and B-cell lymphomas, and acute lymphoblastic and myelogenous leukemias) for comparison between the right-angle light scatter (RALS)/CD45 and the forward-angle light scatter (FALS)/RALS gating combinations. One to three diagnostic markers were selected from each case, yielding 124 paired results for comparison. We found that the percentage of tumor cell isolation and the total cell count in the tumor cell gate were higher in RALS/CD45 than in FALS/RALS. When 20% was used as a cutoff point, 30 markers in FALS/RALS failed to identify the tumor population, while only 3 markers in RALS/CD45 failed to do so. The discriminative factor in the RALS/CD45 gating was mainly the CD45 intensity, whereas all cases except 3 showed low RALS. Although T-cell neoplasms showed a higher proportion of high CD45 intensity, other groups shared similar ranges of CD45 intensity, which is therefore of limited value for differential diagnosis. The RALS/CD45 combination produces higher recovery and purity for tumor cell isolation than the FALS/RALS combination and should replace the latter for routine immunophenotyping of lymphoma and leukemia.