Home Sweet Home: Epigenetic Paths of Stem Cells In and Out of Their Niche

Adult stem cells reside in niches, which control their long-term ability to selfrenew and produce the differentiated cell lineages necessary to regenerate and repair their tissues. Following injury, culture or transplantation, stem cells outside their niche often acquire broader plasticity in fates. In my graduate work, I showed that super-enhancers underlie the identity, lineage commitment and plasticity of adult stem cells in vivo. My chosen model is the hair follicle, where its stem cells (HFSCs), niche and master regulators are well-characterized. By mapping global chromatin domains of HFSCs in their native niche, and of committed progenitors, I discovered that super-enhancers and their dense clusters (‘epicenters’) of transcription factor binding sites change dramatically upon lineage progression. New fate is acquired by decommissioning old and establishing new super-enhancers, an auto-regulatory process that abates one master regulator subset while enhancing another. I showed that epicenters dictate tissue-specific and lineagespecific reporter expression in vivo, yielding powerful genetic tools to drive unprecedented lineage-specificity. Exploiting the ability to culture and transplant HFSCs, I found that intriguingly, when outside their niche and faced with a new environment, HFSCs dynamically remodel super-enhancers, including those driving master identity genes. In vitro, new super-enhancers emerge which drive genes induced upon woundhealing in vivo. Cultured HFSCs adapt to this perceived wounding state by activating different epicenters within the super-enhancers of key SC-identity genes. Probing mechanism, I identified SOX9 as the crucial chromatin regulator of super-enhancers. While high levels maintain HFSC fate and absence results in alternative fates, low levels, e.g. during wound-repair, early lineage progression or culturing, permit fate plasticity. I showed that ectopically expressing SOX9 in epidermis activates polycomb-repressed super-enhancers of HFSC determinants, while sustaining SOX9 in the hair lineage prevents the super-enhancer lineage switch. Cultured HFSCs silence other superenhancer- driven determinants, but retain low SOX9, endowing them with the plasticity to make both SOX9-negative epidermis and SOX9-positive HFs upon engraftment. Together, my findings expose super-enhancers as dynamic and dense transcription factor binding platforms which are exquisitely sensitive to master regulators. Furthermore, by harboring distinct epicenters, super-enhancers possess the ability to adjust reversibly to microenvironmental cues that transiently change transcriptional landscapes. In a second line of research, I focused on functional analyses to uncover the role of superenhancer regulated, putative stemness genes. I found that NFI transcription factors (NFIB and NFIX) act redundantly in mouse skin to maintain the undifferentiated state of progenitors in hair follicles, sebaceous glands and sweat glands. Combining gene expression and chromatin profiling, I discovered that NOTCH signaling, known to drive terminal differentiation in epidermis, is ectopically induced in NFI-deficient HFSCs. These findings provide novel insights into how progenitor status in maintained by a family of transcription factors ubiquitiously active in skin appendages

Within- and between individual variability of personality characteristics and physical exercise

Using two independent samples, the study investigated links of within- and between-individual variability in personality states in three personality domains—Neuroticism, Extraversion, and Conscientiousness—with physical activity. Activity was defined as self-reported quantity of exercising or walking/cycling. More physical activity was associated with people reporting higher levels of Extraversion and Conscientiousness than they usually did, with the associations clearly replicating across samples and generalizing to all items of these domains. This pattern tended to reflect associations at the level of between-individual differences. When the three domains simultaneously predicted activity, within-individual variance in Neuroticism also emerged as a positive predictor, whereas between-individual level associations waned. The findings are consistent with within-individual differences in personality ratings reflecting meaningful, context-relevant variability

Frontline over ivory tower: key competencies in community-based curricula

Background: The Royal College of Physicians and Surgeons of Canada mandates that community experiences be incorporated into medicine-based specialties.  Presently there is wide variability in community endocrine experiences across Canadian training programs.  This is complicated by the paucity of literature providing guidance on what constitutes a ‘community’ rotation.Method: A modified Delphi technique was used to determine the CanMEDS competencies best taught in a community endocrinology curriculum. The Delphi technique is a qualitative-research method that uses a series of questionnaires sent to a group of experts with controlled feedback provided by the researchers after each survey round.  The experts in this study included endocrinology program directors, community endocrinologists, endocrinology residents and recent endocrinology graduates.Results: Thirty four out of 44 competencies rated by the panel were deemed suitable for a community curriculum.  The experts considered the “Manager” role best taught in the community, while they considered the community least suitable to learn the “Medical Expert” competency.Conclusions: To our knowledge, this is the first time the content of a community-based subspecialty curriculum was determined using the Delphi process in Canada.  These findings suggest that community settings have potential to fill in gaps in residency training in regards to the CanMEDS Manager role.  The results will aid program directors in designing competency-based community endocrinology rotations and competency-based community rotations in other medical subspecialty programs

Elektrokemijsko određivanje metalotioneina kod domaće peradi

Metallothionein (MT) belongs to group of intracellular, low-molecular and cysteine-rich proteins with a molecular weight from 6 to 10 kDa. Owing to their high affinity to heavy metals (Zn, Cd, As, etc.) their main role is homeostatic control and detoxification of metal ions in an organism. In the present work we aimed at suggesting and utilizing electroanalytical techniques to determine content of MT in the blood serum of domestic fowls. Electrochemical measurements were performed with an AUTOLAB Analyser connected to VA-Stand 663, using a standard cell with three electrodes. Particularly, MT was detected by adsorptive transfer stripping technique in connection with differential pulse voltammetry. The detection limit of MT was estimated down to 100 fM (standards only) or down to 100 pM measured in the presence of blood serum. The average content of MT was 21.3 µM. The MT level in hens was about 25 % higher than in cocks. This phenomenon can be related to higher demands on the content of this protein in hens due the requirement for ion transport to form eggshell.Metalotionein (MT) pripada grupi intracelularnih proteina male molekularne mase bogatih cisteinom, s molekularnom masom od 6 do 10 kDa. Zbog njihovog afiniteta prema teškim metalima (Zn, Cd, As, itd.) njihova glavna uloga je homeostatska kontrola i detoksifikacija iona metala u organizmu. U ovom radu predlažu se elektroanalitičke tehnike za određivanje sadržaja MT u krvnom serumu domaće peradi. Elektrokemijska mjerenja izvršena su uređajem AUTOLAB Analyser povezanim s VA-Stand 663, koristeći standardnu ćeliju s tri elektrode. Osim toga MT je određivan tehnikom adsorptivnog transfera, povezanoj s voltmetrijom diferencijalnog pulsa. Granica detekcije MT je procjenjivana do 100 fM (samo standardi) ili do 100 pM, mjereno u prisutnosti krvnog seruma. Prosječni sadržaj MT bio je 21.3 µM. Razina MT kod kokoši bila je otprilike 25% viša nego kod pijetlova. Ta pojava može se objasniti većom potrebom za ovim proteinom kod kokoši zbog transporta iona prilikom stvaranja ljuske jajeta

Bone Density Variation in Rattails (Macrouridae,Gadiformes): Buoyancy, Depth, Body Size, and Feeding

A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Extreme abiotic factors in deep-sea environments, such as near-freezing temperatures, low light, and high hydrostatic pressure, drive the evolution of adaptations that allow organisms to survive under these conditions. Pelagic and benthopelagic fishes that have invaded the deep sea face physiological challenges from increased compression of gasses at depth, which limits the use of gas cavities as a buoyancy aid. One adaptation observed in deep-sea fishes to increase buoyancy is a decrease of high-density tissues. In this study, we analyze mineralization of high-density skeletal tissue in rattails (family Macrouridae), a group of widespread benthopelagic fishes that occur from surface waters to greater than 7000 m depth. We test the hypothesis that rattail species decrease bone density with increasing habitat depth as an adaptation to maintaining buoyancy while living under high hydrostatic pressures. We performed micro-computed tomography (micro-CT) scans on 15 species and 20 specimens of rattails and included two standards of known hydroxyapatite concentration (phantoms) to approximate voxel brightness to bone density. Bone density was compared across four bones (eleventh vertebra, lower jaw, pelvic girdle, and first dorsal-fin pterygiophore). On average, the lower jaw was significantly denser than the other bones. We found no correlation between bone density and depth or between bone density and phylogenetic relationships. Instead, we observed that bone density increases with increasing specimen length within and between species. This study adds to the growing body of work that suggests bone density can increase with growth in fishes, and that bone density does not vary in a straightforward way with depth

Preparation and Properties of Various Magnetic Nanoparticles

The fabrications of iron oxides nanoparticles using co-precipitation and gadolinium nanoparticles using water in oil microemulsion method are reported in this paper. Results of detailed phase analysis by XRD and Mössbauer spectroscopy are discussed. XRD analysis revealed that the crystallite size (mean coherence length) of iron oxides (mainly γ-Fe2O3) in the Fe2O3 sample was 30 nm, while in Fe2O3/SiO2 where the ε-Fe2O3 phase dominated it was only 14 nm. Gd/SiO2 nanoparticles were found to be completely amorphous, according to XRD. The samples showed various shapes of hysteresis loops and different coercivities. Differences in the saturation magnetization (MS) correspond to the chemical and phase composition of the sample materials. However, we observed that MS was not reached in the case of Fe2O3/SiO2, while for Gd/SiO2 sample the MS value was extremely low. Therefore we conclude that only unmodified Fe2O3 nanoparticles are suitable for intended biosensing application in vitro (e.g. detection of viral nucleic acids) and the phase purification of this sample for this purpose is not necessary