Drosophila dyskerin is required for somatic stem cell homeostasis

Drosophila represents an excellent model to dissect the roles played by the evolutionary conserved family of eukaryotic dyskerins. These multifunctional proteins are involved in the formation of H/ ACA snoRNP and telomerase complexes, both involved in essential cellular tasks. Since fly telomere integrity is guaranteed by a different mechanism, we used this organism to investigate the specific role played by dyskerin in somatic stem cell maintenance. To this aim, we focussed on Drosophila midgut, a hierarchically organized and well characterized model for stemness analysis. Surprisingly, the ubiquitous loss of the protein uniquely affects the formation of the larval stem cell niches, without altering other midgut cell types. The number of adult midgut precursor stem cells is dramatically reduced, and this effect is not caused by premature differentiation and is cell-autonomous. Moreover, a few dispersed precursors found in the depleted midguts can maintain stem identity and the ability to divide asymmetrically, nor show cell-growth defects or undergo apoptosis. Instead, their loss is mainly specifically dependent on defective amplification. These studies establish a strict link between dyskerin and somatic stem cell maintenance in a telomerase-lacking organism, indicating that loss of stemness can be regarded as a conserved, telomerase-independent effect of dyskerin dysfunction

ROMP of norbornene and oxanorbornene derivatives with pendant fluorophore carbazole and coumarin groups

A series of new (oxa)norbornene dicarboximide monomers, decorated with carbazole and coumarin as pendant fluorophore groups, were synthesized and characterized. Their behaviour in ring-opening metathesis polymerization (ROMP) was explored in the presence of commercial Grubbs' third generation catalyst G3 and cis -selective catalyst GZ. Norbornene dicarboximide (NDI) monomers were successfully polymerized by both the catalysts, while oxanorbornene dicarboximide (ONDI) analogues showed scarce reactivity toward polymerization promoted by GZ. The nature of the spacer (ethylene orp-xylene) between the NDI unit and the chromophore seems to not affect the outcome of the polymerization. Moving from G3 to GZ, it was possible to synthetize NDI- based polymers with cis-olefin content increasing from 47 to 89%, depending on the nature of the pendant fluorophore group. The obtained polymers showed photoluminescence in solution and solid state owing to the carbazole or coumarin fragment, regardless of the nature of the spacer and cis-olefin amount. Interestingly, a significant excimer emission due to the overlap of carbazole groups was observed for a carbazole-functionalized polymer film, as a result of the combined effect of two factors, the stiffness of the spacer (p-xylene) linking the NDI moiety to the fluorophore and the high stereoregularity degree (83% cis) of the main chain

Spectroscopic data of norbornene and oxanorbornene dicarboximides functionalized with carbazole and coumarin groups

This article describes data related to the research paper entitled "ROMP of norbornene and oxanorbornene derivatives with pendant fluorophore carbazole and coumarin groups" [1]. Six novel norbornene and oxanorbornene dicarboximides derivatives functionalized with carbazole or coumarin moieties, are synthesized and investigated in the preparation of fluorescent polymers by Ring-Opening Metathesis Polymerization (ROMP). Herein, we report on the characterization of all these compounds by 1D and 2D Nuclear Magnetic Resonance (NMR), UV-Visible and fluorescence spectroscopy. The characterization data include information obtained from H-1, C-13, Homonuclear Correlation Spectroscopy (H-1-H-1 COSY) and Heteronuclear Single Quantum Coherence (H-1-C-13 HSQC). The absorbence and fluorescence spectra for all these compounds are given. This work provides useful characterization data for the design of new norbornene and oxanorbornene-based monomers with fluorescent carbazole and coumarin groups, which can be employed for the synthesis of functional materials via ROMP. (C) 2022 The Authors. Published by Elsevier Inc

Polyethylenes and Polystyrenes with Carbazole Fluorescent Tags

The increasingly intense consumption of plastics and, above all, their improper disposal in the environment are causing serious environmental concerns. Great efforts have been made for the development of new methods aimed at facilitating and speeding up the identification and sorting of different materials in the plastic recycling process. In this field, new strategies based on fluorescent tagging have been developed. This work concerns the synthesis and characterization of new fluorescent copolymers of polyethylene (PE) and polystyrene (PS), which are among the most produced and consumed plastic materials. The synthesized copolymers are potentially suitable for use as fluorescent markers of PE and PS. Ethylene-co-N-pentenyl carbazole (P(E-co-PK)) and styrene-co-4-(N-carbazolyl)methyl styrene (P(S-co-SK)) copolymers were prepared by Ziegler–Natta and free radical polymerization, respectively. If excited at 300 nm, both P(E-co-PK)s and P(S-co-SK)s give fluorescence emissions resulting in them being optically active. Moreover, due to the low amount of fluorescent units, they show chemico-physical properties such as those of their corresponding homopolymers (PE and PS). P(E-co-PK)s and P(S-co-SK)s have been also tested as fluorescent markers of PE and PS. The experimental results demonstrate that from PE/P(E-co-PK) and PS/P(S-co-SK) blends prepared using only 1% by weight of fluorescent copolymer, distinguishable fluorescent emissions can be still detected

Randomized trial of HTK versus warm blood cardioplegia for right ventricular protection in mitral surgery

OBJECTIVES: To clarify the reliability of the one-shot histidine-tryptophane-ketoglutarate (HTK) cardioplegia for right ventricular (RV) myocardial protection during mitral surgery, in patients with or without pre-operative RV dysfunction. DESIGN: Sixty patients undergoing isolated mitral surgery were randomized to myocardial protection with either one-shot HTK or intermittent warm blood cardioplegia (WBC). The RV function was assessed by echocardiography and hemodynamic assessment. Pre-operative tricuspid annular plane systolic excursion (TAPSE), an index of RV systolic function was used to dichotomize groups into patients having impaired (TAPSE < 15) or preserved (TAPSE 65 15) RV function. RESULTS: There were no significant intergroup differences in the post-operative indexes of RV function in cases with TAPSE 65 15. In patients having TAPSE < 15 we observed statistically worse RV ejection fraction (RVEF, 15% \ub1 2% vs. 24% \ub1 3%), end-diastolic volume (RVEDV, 188 mL \ub1 20 vs. 179 mL \ub1 14) and fractional area change (RVFAC, 21% \ub1 6% vs. 30% \ub1 3%) after use of the HTK solution versus patients who received the WBC. These differences were associated with longer mechanical ventilation and ICU times in patients with impaired RV function and receiving HTK cardioplegia. In a substudy ten patients with TAPSE < 15 received intra-operative topical myocardial cooling in addition to HTK. The addition of topical cooling to HTK cardioplegia yielded statistically significant amelioration in post-operative RV function compared with patients who received the HTK solution without topical cooling (RVEF: 23% \ub1 3% vs. 15% \ub1 2%; RVEDV: 180 mL \ub1 9 vs. 188 mL \ub1 18; RVFAC: 8.5% \ub1 1% vs. 6% \ub1 2%). CONCLUSIONS: The one shot HTK solution offers inferior RV protection compared with WBC, mainly in patients with depressed pre-operative RV function. When adopting HTK cardioplegia the addition of topical cooling is strongly advise