Helical Coiled Nucleosome Chromosome Architectures during Cell Cycle Progression.

Recent studies showed an interphase chromosome architecture, --- a specific coiled nucleosome structure, --- derived from cryo-preserved EM tomograms, and dispersed throughout the nucleus. The images were computationally processed to fill in the missing wedges of data caused by incomplete tomographic tilts. The resulting structures increased z-resolution enabling an extension of the proposed architecture to that of mitotic chromosomes. Here we provide additional insights and details into the coiled nucleosome chromosome architectures. We build on the defined chromosomes time-dependent structures in an effort to probe their dynamics. Variants of the coiled chromosome structures, possibly further defining specific regions, are discussed. We propose, based on generalized specific uncoiling of mitotic chromosomes in telophase, large-scale re-organization of interphase chromosomes. Chromosome territories, organized as micron-sized small patches, are constructed, satisfying complex volume considerations. Finally, we unveiled the structures of replicated coiled chromosomes, still attached to centromeres, as part of chromosome architecture. Significance Statement: This study places all 46 sequenced human chromosomes, --- correctly filled with nucleosomes and in micron sized chromosome territories - into 10micron (average sized) nuclei. The chromosome architecture used a helical nucleosome coiled structure discerned from cryo-EM tomography, as was recently published ( https://doi.org/10.1073/pnas.2119101119 ). This chromosome architecture was further modeled to dynamic structures, structure variations and chromosome replication centromere complications. Finally, this chromosome architecture was modified to allow seamless transition through the cell cycle.

A proposed unified interphase nucleus chromosome structure: Preliminary preponderance of evidence.

Cryoelectron tomography of the cell nucleus using scanning transmission electron microscopy and deconvolution processing technology has highlighted a large-scale, 100- to 300-nm interphase chromosome structure, which is present throughout the nucleus. This study further documents and analyzes these chromosome structures. The paper is divided into four parts: 1) evidence (preliminary) for a unified interphase chromosome structure; 2) a proposed unified interphase chromosome architecture; 3) organization as chromosome territories (e.g., fitting the 46 human chromosomes into a 10-µm-diameter nucleus); and 4) structure unification into a polytene chromosome architecture and lampbrush chromosomes. Finally, the paper concludes with a living light microscopy cell study showing that the G1 nucleus contains very similar structures throughout. The main finding is that this chromosome structure appears to coil the 11-nm nucleosome fiber into a defined hollow structure, analogous to a Slinky helical spring [https://en.wikipedia.org/wiki/Slinky; motif used in Bowerman et al., eLife 10, e65587 (2021)]. This Slinky architecture can be used to build chromosome territories, extended to the polytene chromosome structure, as well as to the structure of lampbrush chromosomes.

A proposed unified mitotic chromosome architecture.

A molecular architecture is proposed for a representative mitotic chromosome, human chromosome 10. This architecture is built on an interphase chromosome structure based on cryo-electron microscopy (cryo-EM) cellular tomography [J. Sedat et al., Proc. Natl. Acad. Sci. U.S.A., in press], thus unifying chromosome structure throughout the complete mitotic cycle. The basic organizational principle for mitotic chromosomes is specific coiling of the 11-nm nucleosome fiber into large scale, ∼200-nm interphase structures, a Slinky [https://en.wikipedia.org/wiki/Slinky; motif cited in S. Bowerman et al., eLife 10, e65587 (2021)], then further modified with subsequent additional coiling for the final mitotic chromosome structure. The final mitotic chromosome architecture accounts for the dimensional values as well as the well-known cytological configurations. In addition, proof is experimentally provided by digital PCR technology that G1 T cell nuclei are diploid with one DNA molecule per chromosome. Many nucleosome linker DNA sequences, the promotors and enhancers, are suggestive of optimal exposure on the surfaces of the large-scale coils.

How do they feel? Patients' perspectives on draping and dignity in a physiotherapy outpatient setting: A pilot study.

BACKGROUND: Research to date has focused on dignity within the hospital rather than outpatient settings which is likely to raise different issues from the patients' perspective. PURPOSE: To investigate patients' views relating to draping and dignity and their choice of dressing options in the physiotherapy outpatient setting. METHOD: A custom-designed questionnaire was developed including feedback from a focus group of 10 individuals attending a physiotherapy outpatient clinic. The final version of the questionnaire comprised 14 items covering issues regarding privacy, draping, respect and communication. Patients attending outpatient physiotherapy for musculoskeletal treatment were invited to complete the questionnaire which was administered over a period of seven weeks. RESULTS: Of the 31 respondents completing the questionnaire (n = 23 females, n = 8 males), the majority of males (87.5% n = 7) felt very confident removing their clothing whereas 26.1% of females (n = 6) reported feeling confident when asked to remove their clothing. Female respondents also considered the gender of their physiotherapist (87% n = 21) as well as physical privacy (73.9% n = 17) to be important factors related to patient dignity. All male respondents (100%) expressed a preference for exposing the bare back whereas the females expressed mixed dressing preferences. The preferred dressing option for the lower body for both males and female respondent was sport shorts (87.5% n = 7; 81.8% n = 18 respectively). CONCLUSION: The patients' perspective of dignity and draping in a physiotherapy musculoskeletal settings is seen in terms of physical space, the provision of a range of draping options in conjunction with clear communication by their physiotherapist.