RESUMEN
Oocyte maturation and preimplantation embryo development are critical to successful pregnancy outcomes and the correct establishment and maintenance of genomic imprinting. Thanks to novel technologies and omics studies in human patients and mouse models, the importance of the proteins associated with the cytoplasmic lattices (CPLs), highly abundant structures found in the cytoplasm of mammalian oocytes and preimplantation embryos, in the maternal to zygotic transition is becoming increasingly evident. This review highlights the recent discoveries on the role of these proteins in protein storage and other oocyte cytoplasmic processes, epigenetic reprogramming, and zygotic genome activation (ZGA). A better comprehension of these events may significantly improve clinical diagnosis and pave the way for targeted interventions aiming to correct or mitigate female fertility issues and genomic imprinting disorders.
RESUMEN
Maternal inactivation of genes encoding components of the subcortical maternal complex (SCMC) and its associated member, PADI6, generally results in early embryo lethality. In humans, SCMC gene variants were found in the healthy mothers of children affected by multilocus imprinting disturbances (MLID). However, how the SCMC controls the DNA methylation required to regulate imprinting remains poorly defined. We generated a mouse line carrying a Padi6 missense variant that was identified in a family with Beckwith-Wiedemann syndrome and MLID. If homozygous in female mice, this variant resulted in interruption of embryo development at the two-cell stage. Single-cell multiomic analyses demonstrated defective maturation of Padi6 mutant oocytes and incomplete DNA demethylation, down-regulation of zygotic genome activation (ZGA) genes, up-regulation of maternal decay genes, and developmental delay in two-cell embryos developing from Padi6 mutant oocytes but little effect on genomic imprinting. Western blotting and immunofluorescence analyses showed reduced levels of UHRF1 in oocytes and abnormal localization of DNMT1 and UHRF1 in both oocytes and zygotes. Treatment with 5-azacytidine reverted DNA hypermethylation but did not rescue the developmental arrest of mutant embryos. Taken together, this study demonstrates that PADI6 controls both nuclear and cytoplasmic oocyte processes that are necessary for preimplantation epigenetic reprogramming and ZGA.
Asunto(s)
Oocitos , Cigoto , Animales , Niño , Femenino , Humanos , Ratones , Proteínas Potenciadoras de Unión a CCAAT/genética , Citoplasma/genética , Citoplasma/metabolismo , Metilación de ADN/genética , Desarrollo Embrionario/genética , Impresión Genómica/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Herein we report a significant, valuable extension of a recently implemented pyrrole benzannulation methodology that, employing versatile nitrodienes from our lab as useful C4 building blocks, led to indole derivatives characterized by unusual patterns of substitution. The 6-nitro-7-arylindoles resulting from suitably derivatized, non-symmetric dienes are of foreseeable synthetic interest in search for new polyheterocyclic systems. As an example, pyrrolocarbazoles with a rarely reported ring fusion were synthesized with the classical Cadogan protocol. Furthermore, the proven easy reducibility of the nitro group to amine will surely open the way to further interesting elaborations.
Asunto(s)
Carbazoles/química , Indoles/química , Pirroles/química , Carbazoles/síntesis química , Indoles/síntesis química , Estructura Molecular , Pirroles/síntesis químicaRESUMEN
Indole-tethered ynones form an intramolecular electron donor-acceptor complex that can undergo visible-light-induced charge transfer to promote thiyl radical generation from thiols. This initiates a novel radical chain sequence, based on dearomatising spirocyclisation with concomitant C-S bond formation. Sulfur-containing spirocycles are formed in high yields using this simple and mild synthetic protocol, in which neither transition metal catalysts nor photocatalysts are required. The proposed mechanism is supported by various mechanistic studies, and the unusual radical initiation mode represents only the second report of the use of an intramolecular electron donor-acceptor complex in synthesis.
RESUMEN
Evaluating plant community response to atmospheric CO2 rise is critical to predicting ecosystem level change. Freshwater lakes offer a model system for examining CO2 effects as submersed macrophyte species differ greatly in their growth responses to CO2 enrichment, and free CO2 concentrations among these habitats show a wide range of natural, spatial variation. We determined free CO2 concentrations in the water column and sediment porewater in littoral zones with pH < 6.0 in Adirondack Mountain (New York, USA) lakes, and derived a community CO2 responsiveness index (CCRI) based on quantitative sampling of 15 submersed macrophyte communities coupled with greenhouse-derived growth responses to CO2 enrichment of constituent species to test two hypotheses: (1) CCRI, which is higher for communities dominated by species with greater growth responses to CO2 enrichment, is positively correlated to free [CO2 ] in the water column, and (2) in natural communities, the percent of sediment CO2 -using species, which are relatively unresponsive to CO2 enrichment, is negatively correlated to free [CO2 ]. A significant positive correlation (P = 0.003) between our physiologically based CCRI and the concentration of free CO2 in the water column supported our primary hypothesis that sites with higher levels of free CO2 are dominated by species with greater growth responses to CO2 enrichment. Our CCRI is also highly significantly correlated (P < 0.001) to the first axis scores for the same vegetation data from polar ordination. Finally, the relative importance of species that use sediment CO2 as a photosynthetic carbon source is significantly negatively correlated (P = 0.029) with the concentration of free CO2 in the water column. Our results indicate that natural variations in CO2 levels are important determinants of submersed macrophyte community composition. Further, we demonstrate the utility of a physiologically-based index of community composition, our CCRI, as an ecologically valid measure of community response to CO2 .
Asunto(s)
Dióxido de Carbono/análisis , Ecosistema , Lagos/química , Plantas , Ecología , New YorkRESUMEN
Young pigs represent an excellent model of youth to assess potentials of dietary factors for improving bone structure and function. We conducted 2 experiments to determine whether adding microbial phytase (2,000 U/kg, OptiPhos, JBS United) and Sr (50 mg/kg, SrCO3 Alfa Aesar) into a P-adequate diet further improved bone strength of young pigs. In Expt. 1, 24 gilts (8.6 +/- 0.1 kg body wt) were divided into 2 groups (n = 12), and fed a corn-soybean-meal basal diet (BD, 0.33% available P) or BD + phytase for 6 wk. In Expt. 2, 32 pigs (11.4 +/- 0.2 kg) were divided into 4 groups (n = 8), and fed BD, BD + phytase, BD + Sr, or BD + phytase and Sr for 5 wk. Both supplemental phytase and Sr enhanced (P < 0.05) breaking strengths (11-20%), mineral content (6-15%), and mineral density (6-11%) of metatarsals and femurs. Supplemental phytase also resulted in larger total bone areas (P < 0.05) and a larger cross-sectional area of femur (P = 0.06). Concentrations of Sr were elevated 4-fold (P < 0.001) in both bones by Sr, and moderately increased (P = 0.05-0.07) in metatarsal by phytase. In conclusion, supplemental phytase at 2000 U/kg of P-adequate diets enhanced bone mechanical function of weanling pigs by modulating both geometrical and chemical properties of bone. The similar benefit of supplemental Sr was mainly due to an effect on bone chemical properties.
Asunto(s)
6-Fitasa/metabolismo , Densidad Ósea/efectos de los fármacos , Escherichia coli/enzimología , Fósforo Dietético/farmacología , Estroncio/farmacología , Porcinos/crecimiento & desarrollo , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Suplementos DietéticosRESUMEN
We used immunohistochemical techniques and confocal microscopy to study the morphometry of myelinated nerve endings in glabrous and hairy skin. A total of 30 healthy volunteers took part in this study designed to assess the possibility of obtaining reliable information on myelinated fibers using samples of hairy skin and to determine whether differences exist between myelinated terminations from different sites. We obtained consistent information on cutaneous myelinated terminations using hairy as well as glabrous skin samples. Myelinated endings from hairy and glabrous skin differ in density and distribution. However, from a comparison of our findings with data from nerve biopsy studies, we conclude that all cutaneous myelinated terminations are thinner terminal branches of large myelinated A beta fibers, whereas cutaneous terminations of small myelinated A delta fibers lose their myelin before entering the dermis and become indistinguishable from C-fiber terminations. The classic criteria, based on fiber size, used to distinguish myelinated fiber subgroups in sensory nerves are therefore not suitable for identifying myelinated terminations in the skin.