Tissue-specific transcription patterns are preserved throughout cell divisions to maintain lineage fidelity. We investigated whether transcription factor GATA1 plays a role in transmitting ...hematopoietic gene expression programs through mitosis when transcription is transiently silenced. Live-cell imaging revealed that a fraction of GATA1 is retained focally within mitotic chromatin. ChIP-seq of highly purified mitotic cells uncovered that key hematopoietic regulatory genes are occupied by GATA1 in mitosis. The GATA1 coregulators FOG1 and TAL1 dissociate from mitotic chromatin, suggesting that GATA1 functions as platform for their postmitotic recruitment. Mitotic GATA1 target genes tend to reactivate more rapidly upon entry into G1 than genes from which GATA1 dissociates. Mitosis-specific destruction of GATA1 delays reactivation selectively of genes that retain GATA1 during mitosis. These studies suggest a requirement of mitotic “bookmarking” by GATA1 for the faithful propagation of cell-type-specific transcription programs through cell division.
Display omitted
► GATA1 remains focally bound to chromatin during mitosis ► Mitotic GATA1 sites mark key hematopoietic transcription factor genes ► Mitotic retention of GATA1 is required for normal transcription reactivation ► Mitotic retention of GATA1 is required for repression of immature cell markers
Retention of GATA1 on a subset of its target genes during mitosis is required for their timely reactivation. These targets include hematopoiesis-specific regulators, suggesting that mitotic occupancy of genes encoding regulatory factors might contribute to preserving cell-type-specific transcriptional programs throughout the cell cycle.
A 19-year-old girl with a short stature and presenting low intelligence quotient, illegible speech, and a greatly distended abdomen was seen at the gynecological outpatient department. She underwent ...investigation and was found to have large abdominopelvic multicystic ovaries with no malignant features and CA125 levels within the normal range for premenopausal women. Her thyroid-stimulating hormone (TSH) was markedly elevated. She received a diagnosis of untreated severe hypothyroidism with benign giant ovarian cysts, posing a grave risk of cyst rupture and imminent complications. The parents were counseled, and they accepted the risk, agreeing to conservative therapy. Levothyroxine replacement therapy was initiated, and after one month, her TSH levels normalized. Follow-up ultrasonography after one month of her therapy revealed a marked decrease in ovarian cyst size. Thyroid replacement therapy was continued, and at the end of three months, the cysts disappeared, and the ovaries, much smaller, showed polycystic ovarian morphology. Careful analysis of clinical signs, investigations, and appropriate therapy helped avoid unnecessary surgery.
FleN, a P loop ATPase is vital for maintaining a monotrichous phenotype in Pseudomonas aeruginosa. FleN exhibits antagonistic activity against FleQ, the master transcriptional regulator of flagellar ...genes. Crystal structures of FleN in the apo form (1.66 Å) and in complex with β,γ-imidoadenosine 5′-triphosphate (1.55 Å) reveal that it undergoes drastic conformational changes on ATP binding to attain a structure capable of dimerization. Mutations of the residues that stabilize the binding of ATP were defective in their ability to dimerize and do not inhibit ATP hydrolysis by FleQ. Conversely, the catalytic mutant of FleN, was an efficient inhibitor. These observations posit that the dimer is the functional form of FleN and it is nucleotide binding and not hydrolysis by FleN that is necessary to exert an antagonistic effect against FleQ. Our study shows that ATP-induced dimerization may be a strategy to achieve reversible inhibition of FleQ to fine-tune the function of this activator to an optimal level.
Display omitted
•FleN, a P loop ATPase, inhibits ATP hydrolysis by the transcription regulator FleQ•ATP binding by FleN elicits conformational changes that enable formation of a dimer•Nucleotide binding is necessary and sufficient for antiactivator function of FleN•Reversible dimerization of FleN regulates FleQ and ensures monoflagellate status
FleN is an antiactivator of FleQ, a global transcriptional regulator of flagellar and biofilm genes in Pseudomonas aeruginosa. It inhibits ATP hydrolysis by FleQ. Chanchal et al. show that FleN undergoes structural remodeling on ATP binding and that the ATPase activity of FleN is not essential for its antiactivator function. Reversible dimerization allows FleN to fine-tune the active cellular concentration of FleQ rather than exert a binary on/off effect and this ensures formation of a single flagellum.
The prediction and realization of topological insulators have sparked great interest in experimental approaches to the classification of materials1–3. The phase transition between non-trivial and ...trivial topological states is important, not only for basic materials science but also for next-generation technology, such as dissipation-free electronics4. It is therefore crucial to develop advanced probes that are suitable for a wide range of samples and environments. Here we demonstrate that circularly polarized laser-field-driven high-harmonic generation is distinctly sensitive to the non-trivial and trivial topological phases in the prototypical three-dimensional topological insulator bismuth selenide5. The phase transition is chemically initiated by reducing the spin–orbit interaction strength through the substitution of bismuth with indium atoms6,7. We find strikingly different high-harmonic responses of trivial and non-trivial topological surface states that manifest themselves as a conversion efficiency and elliptical dichroism that depend both on the driving laser ellipticity and the crystal orientation. The origins of the anomalous high-harmonic response are corroborated by calculations using the semiconductor optical Bloch equations with pairs of surface and bulk bands. As a purely optical approach, this method offers sensitivity to the electronic structure of the material, including its nonlinear response, and is compatible with a wide range of samples and sample environments.Researchers demonstrate a method based on circularly polarized laser-field-driven high-harmonic generation for probing non-trivial and trivial topological phases in a three-dimensional topological insulator.
Background: Leiomyomata causing symptoms have a deleterious effect on the health of women during reproductive age. Mifepristone, a progesterone antagonist was studied for reduction of symptoms in ...leiomyomata in perimenopausal women. Material and Methods: Mifepristone was adminstered to 7 women aged 47-50 years. Another 3 women less than 47 years were taken up for comparison of benefit of Mifepristone on leiomyomata related symptoms. Mifepristone was given in a stepwise declining dose for a period of 9 months to 1 year . The treatment was begun with 25 mg and the dose was reduced every 3 months. Every 3 months, the size of myomas, bleeding pattern, location of myomas, endometrial thickness, haemoglobin, and any side effects were all recorded. Results: There was considerable amelioration in the symptoms in both premenopausal as well as perimenopausal women, while mifepristone was continued. The reduction in myoma size was found to be statistically significant. After stoppage of drug in women aged 40-45 years, i.e. premenopausal group, the symptoms returned. However, in perimenopausal women, in 6 out of 7 women the symtoms abated completely and they had a smooth transition to menopause. Conclusion: Mifepristone is a very promising drug for conservative management of leiomyomata, especially in perimenopausal age (47years or more), where hysterectomy was averted in all 7 women.
Background: Chickpea (C. arietinum L.) ranks third in food legume crop production in the world. However, drought poses a serious threat to chickpea production, and development of drought-resistant ...varieties is a necessity. Unfortunately, cultivated chickpea has a high morphological but narrow genetic diversity, and understanding the genetic processes of this plant is hindered by the fact that the chickpea genome has not yet been sequenced and its EST resources are limited. In this study, two chickpea varieties having contrasting levels of drought-tolerance were analyzed for differences in transcript profiling during drought stress treatment by withdrawal of irrigation at different time points. Transcript profiles of ESTs derived from subtractive cDNA libraries constructed with RNA from whole seedlings of both varieties were analyzed at different stages of stress treatment. Results: A series of comparisons of transcript abundance between two varieties at different time points were made. 319 unique ESTs available from different libraries were categorized into eleven clusters according to their comparative expression profiles. Expression analysis revealed that 70% of the ESTs were more than two fold abundant in the tolerant cultivar at any point of the stress treatment of which expression of 33% ESTs were more than two fold high even under the control condition. 53 ESTs that displayed very high fold relative expression in the tolerant variety were screened for further analysis. These ESTs were clustered in four groups according to their expression patterns. Conclusions: Annotation of the highly expressed ESTs in the tolerant cultivar predicted that most of them encoded proteins involved in cellular organization, protein metabolism, signal transduction, and transcription. Results from this study may help in targeting useful genes for improving drought tolerance in chickpea.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Quantum anomalous Hall effect (QAHE) can only be realized at extremely low temperatures in magnetically doped topological insulators (TIs) due to limitations inherent with the doping process. In an ...effort to boost the quantization temperature of QAHE, the magnetic proximity effect in magnetic insulator/TI heterostructures has been extensively investigated. However, the observed anomalous Hall resistance has never been more than several ohms, presumably owing to the interfacial disorders caused by the structural and chemical mismatch. Here, we show that, by growing (Bi x Sb1–x )2Te3 (BST) thin films on structurally and chemically well-matched, ferromagnetic-insulating CrGeTe3 (CGT) substrates, the proximity-induced anomalous Hall resistance can be enhanced by more than an order of magnitude. This sheds light on the importance of structural and chemical matches for magnetic insulator/TI proximity systems.
AbstractA set D of vertices in a connected graph G is said to be an independent 2-point set dominating set (or in short i-2psd set) of G if D is an independent set and for every non-empty subset ...Formula: see text there exists a non-empty subset Formula: see text having at most 2 vertices such that the induced subgraph Formula: see text is connected. We call a graph to be an i-2psd graph if it possesses an i-2psd set. In this article, we explore i-2psd graphs. We first provide complete structural characterization of separable i-2psd graphs and thereafter, in our quest to characterize i-2psd blocks, we characterize hexagon-free bipartite i-2psd blocks and exhibit a family of non-bipartite i-2psd blocks.
PDF
