No abstract available

[en] Highlights: • A NoLS in the N-terminus of SPIN1 mediates its nucleolar localization and function. • The H3R8me2a-recognizing capacity of SPIN1 is indispensable for its promotion of rRNA expression. • SPIN1 is involved the formation of SL1 complex on rDNA loci. Spindlin1 (SPIN1), a histone modification reader protein, was enriched in the cell nucleolus and facilitated rRNA expression. However, how SPIN1 localizes to the nucleolus and its functional role in rRNA gene expression remain unresolved. Here, we identified a nucleolar localization signal in the N-terminal region of SPIN1 that is essential for its enrichment and function in the nucleolus. We also discovered that, in addition to its H3K4me3 recognizing activity, the H3R8me2a-recognizing capacity of SPIN1 is also indispensable for stimulating rRNA expression. Chromatin immunoprecipitation results indicated that SPIN1 is required for the association or assembly of selective factor 1 (SL1) complex, probably facilitating the initiation of rDNA transcription through its H3 K4me3-R8me2a reader function.

[en] Full text: The numbers of X-chromatin body ('drumstick' appendages) in the interphase nuclei of three major breeds of Nigerian goats were studied. Each goat breed was derived from three different locations in the country based on the areas of its preponderance. Smears from buccal cavity and PMNS of each goat were developed using standard staining techniques. The mean values obtained per breed irrespective of sex were 1.92%, 1.65% and 1.60% for Sahel Goats (SG), Red Sokoto Goats (RSG) and West African Dwarf Goats (WADG), respectively. The mean value obtained for the bucks and does irrespective of breed were 0.13% and 3.07%, respectively. Those for males per breed were 0.15% for SG, 0.15% for RSG, and 0.10% for WADG and for does per breed were: 3.44% for SG, 3.10% for RSG and 2.67% for WADG. The results generally revealed that the frequency of 'drumstick' was statistically different (P < 0.05) between Bucks and Does; Bucks were statistically the same (P < 0.05) in 'drumstick' incidence, irrespective of breed and location, while the 'drumstick' incidence was statistically higher (P < 0.05) in Sahelian Does, followed by RS Does and least in WAD Does. This may account for higher prolificacy frequently observed in SG, followed by RSG. However, location exhibited an infinitesimal effect on the frequency of 'drumstick' within breeds, indicating that incidence of 'drumstick' is purely a genetic factor. (author)

[en] Fertilization and early embryogenesis has been studied in an aquatic heterosporic Fern: Marsilea vestita. The sperm penetration and the evolution of the male genetic material in the fermale nucleoplasm has been followed by autoradiographic techniques with the use of a specific DNA precursor. The male chromatin remains in a limited space of the female nucleoplasm and mixes gradualy during early embryogenesis. A very slow fusion has been found in the cells which will become the apical cells of each functional radicular, foliar and shoot meristems. Concerning the cytoplasmic organelles, the problem is still unresolved but the results obtained by high autoradiographic resolution show that the paternal organelles perhaps partially participate in the organisation of the embryo cytoplasmic genomes

[en] Highlights: • Basic cluster region (residues 295 to 313) in the MeCP2 binds to AT-rich DNA. • NMR relaxation data identified that IKKRKTRE is critical for binding. • Basic cluster peptide binds to the minor groove of DNA, similar to AT-hooks. MeCP2 is a chromatin associated protein which is highly expressed in brain and relevant with Rett syndrome (RTT). There are AT-hook motifs in MeCP2 which can bind with AT-rich DNA, suggesting a role in chromatin binding. Here, we report the identification and characterization of another AT-rich DNA binding motif (residues 295 to 313) from the C-terminal transcription repression domain of MeCP2 by nuclear magnetic resonance (NMR) and isothermal calorimetry (ITC). This motif shows a micromolar affinity to AT-rich DNA, and it binds to the minor groove of DNA like AT-hook motifs. Together with the previous studies, our results provide an insight into a critical role of this motif in chromatin structure and function.

[en] Highlights: • HOTTIP is required for activation of distal HOXA genes but its role is restricted by CTCF boundary. • HOTTIP and CTCF coordinate to specify the pattern of histone modifications on HOXA genes in foreskin fibroblasts. • HOTTIP RNA acts as a new interaction partner of CTCF. The spatiotemporal control of HOX gene expression is dependent on positional identity and often correlated to their genomic location within each loci. Maintenance of HOX expression patterns is under complex transcriptional and epigenetic regulation, which is not well understood. Here we demonstrate that HOTTIP, a lincRNA transcribed from the 5′ edge of the HOXA locus, physically associates with the CCCTC-binding factor (CTCF) that serves as an insulator by organizing HOXA cluster into disjoint domains, to cooperatively maintain the chromatin modifications of HOXA genes and thus coordinate the transcriptional activation of distal HOXA genes in human foreskin fibroblasts. Our results reveal the functional connection of HOTTIP and CTCF, and shed light on lincRNAs in gene activation and CTCF mediated chromatin organization.

[en] Chemical fixation is nearly indispensable in the biological sciences, especially in circumstances where cryo-fixation is not applicable. While universally employed for the preservation of cell organization, chemical fixatives often introduce artifacts that can confound identification of true structures. Since biological research is increasingly probing ever-finer details of the cellular architecture, it is critical to understand the nanoscale transformation of the cellular organization due to fixation both systematically and quantitatively. In this work, we employed Partial Wave Spectroscopic (PWS) Microscopy, a nanoscale sensitive and label-free live cell spectroscopic-imaging technique, to analyze the effects of the fixation process through three commonly used fixation protocols for cells in vitro. In each method investigated, we detected dramatic difference in both nuclear and cytoplasmic nanoarchitecture between live and fixed states. But significantly, despite the alterations in cellular nanoscale organizations after chemical fixation, the population differences in chromatin structure (e.g. induced by a specific chemotherapeutic agent) remains. In conclusion, we demonstrated that the nanoscale cellular arrangement observed in fixed cells was fundamentally divorced from that in live cells, thus the quantitative analysis is only meaningful on the population level. This finding highlights the importance of live cell imaging techniques with nanoscale sensitivity or cryo-fixation in the interrogation of cellular structure, to complement more traditional chemical fixation methods. - Highlights: • PWS was employed to monitor fixation process for the same cells in vitro. • Dramatic changes in cellular nanostructure were observed after fixation. • However, the population difference of chromatin structure remains after fixation.

[en] Transcriptionally active chromatin fibers were observed in chromosomes presenting the loops/scaffold configuration. The active fibers showed altered nucleosomes and presented multiforked aspects which led to the formation of ring complexes. The ribonucleoprotein transcripts (RNP) appeared as networks of 0.1 μm or multiples tandemly disposed along the fiber. It is suggested that the ring complexes belong to the human genome. The possibility that these circular structures come from a prokaryote is also considered. (author)

[en] Infantile hemangiomas are the most frequent vascular soft tissue lumps in the pediatric population. The clinical presentation and evolution of these lesions is characteristic, while the sonographic appearance is classic but not specific. This pictorial essay illustrates the different vascular soft tissue lumps on ultrasound that may mimic infantile hemangiomas. Awareness of these mimics is crucial to avoid misdiagnosis. Clinical and sonographic discriminators for each lesion are presented. (author)

No abstract available