Wingless-type mouse mammary tumor virus integration site (WNT) signaling molecules are locally secreted glycoproteins that play important role in regulation of ovarian follicle maturation and steroid ...production. Components of the WNT signaling pathway have been demonstrated to impact reproductive functions, including embryonic development of the sex organs and regulation of follicle maturation controlling steroidogenesis in the postnatal ovary. Emerging evidence underscores the complexity of WNT signaling molecules in regulation of dynamic changes that occur in the ovary during the reproductive cycle. While disruption in the WNT signaling cascade has been recognized to have deleterious consequences to normal sexual development, more recent studies are beginning to highlight the importance of these molecules in adult ovarian function related to follicle development, corpus luteum formation, steroid production and fertility. Hormonal regulation of WNT genes and expression of members of the WNT signaling network, including WNT ligands, frizzled receptors, and downstream signaling components that are expressed in the postnatal ovary at distinct stages of the estrous cycle suggest a crucial role in normal ovarian function. Similarly, FSH stimulation of T-cell factor-dependent gene expression requires input from β-catenin, a lynchpin molecule in canonical WNT signaling, further indicating β-catenin participation in regulation of follicle maturation. This review will focus on the multiple functions of WNT signaling in folliculogenesis in the adult ovary.
This paper analyzes the historical evolution of the Venezuelan Electricity Sector (VES) from the 1940s to the present. The objective is to identify the causes that have led to the current chaotic ...situation in power supply and propose corrective measures. This analysis is conducted within the framework of the literature on energy governance and extractivism in Latin America (LA). The VES has been conditioned upon the general objectives of energy policy in Venezuela. What has been called extractivism in the 20th century has been prolonged with the neo-extractivism of the 21st century. The country's oil revenues allowed for a highly interventionist energy governance policy, which was implemented hierarchically without the participation of VES stakeholders. On the other hand, the lack of market mechanisms and company financing schemes have led to inefficiencies in the operations of the sector. Finally, the lack of stable regulation, political uncertainty, and the absence of control mechanisms have contributed to the collapse. Due to the importance of electricity for the stability of Venezuela, it is necessary to propose a new and more participative energy governance strategy which also entails to rethink the VES structure and regulation.
•Political decisions have excessively influenced economic decisions.•The financing model has generated inefficient company behavior.•It is necessary to carry out a total or partial unbubdling of supply activities.•Governance must be more participatory and transparent.
Polycomb repressive complex 2 (PRC2) is a histone methyltransferase that is localized to thousands of mammalian genes. Though important to human disease and as a drug target, how PRC2 is recruited ...remains unclear. One model invokes cis-regulatory RNA. Herein, we biochemically and functionally probe PRC2’s recognition of RNA using the X-inactivation model. We observe surprisingly high discriminatory capabilities. While SUZ12 and JARID2 subunits can bind RNA, EZH2 has highest affinity and is somewhat promiscuous. EED regulates the affinity of EZH2 for RNA, lending greater specificity to PRC2-RNA interactions. Intriguingly, while RNA is crucial for targeting, RNA inhibits EZH2’s catalytic activity. JARID2 weakens PRC2’s binding to RNA and relieves catalytic inhibition. We propose that RNA guides PRC2 to its target but inhibits its enzymatic activity until PRC2 associates with JARID2 on chromatin. Our study provides a molecular view of regulatory interactions between RNA and PRC2 at the chromatin interface.
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•PRC2 binds RNA selectively with high specificity•EZH2 is somewhat promiscuous, and EED lends specificity to PRC2-RNA interactions•RNA inhibits PRC2’s histone methyltransferase activity•JARID2 attenuates RNA binding and relieves inhibition of methylation
PRC2 methylates histone H3 at thousands of sites in the genome, but how it is targeted remains unknown. Cifuentes-Rojas et al. show that RNA plays dual positive-negative roles in this process, first targeting PRC2 to specific sites but also inhibiting its methyltransferase activity until JARID2 relieves the inhibition by dissociating RNA from PRC2.
Melatonin, a molecule first discovered in animal tissues, plays an important role in multiple physiological responses as a possible plant master regulator. It mediates responses to different types of ...stress, both biotic and abiotic. Melatonin reduces the negative effects associated with stressors, improving the plant response by increasing plant stress tolerance. When plants respond to stress situations, they use up a large amount of plant resources through a set of perfectly synchronized actions. Responses mediated by melatonin use the plant’s hormones to, after adequate modulation, counteract and overcome the negative action of the stressor. In this paper, we review melatonin–plant hormone relationships. Factors that trigger the stress response and the central role of melatonin are analysed. An extensive analysis of current studies shows that melatonin modulates the metabolism of plant hormones (biosynthesis and catabolism), the rise or fall in their endogenous levels, the regulation of signalling elements and how melatonin affects the final response of auxin, gibberellins, cytokinins, abscisic acid, ethylene, salicylic acid, jasmonates, brassinosteroids, polyamines and strigolactones. Lastly, a general overview of melatonin’s actions and its regulatory role at a global level is provided and proposals for future research are made.
Melatonin in plants regulates the levels of plant hormones through the up‐ or down‐expression of biosynthesis and catabolic genes and signaling elements.
Plant melatonin appears to be a multi-regulatory molecule, similar to those observed in animals, with many specific functions in plant physiology. In recent years, the number of studies on melatonin ...in plants has increased significantly. One of the most studied actions of melatonin in plants is its effect on biotic and abiotic stress, such as that produced by drought, extreme temperatures, salinity, chemical pollution and UV radiation, among others.
This review looks at studies in which some aspects of the relationship between melatonin and the plant hormones auxin, cytokinin, gibberellins, abscisic acid, ethylene, jasmonic acid and salicylic acid are presented. The effects that some melatonin treatments have on endogenous plant hormone levels, their related genes (biosynthesis, catabolism, receptors and transcription factors) and the physiological actions induced by melatonin, mainly in stress conditions, are discussed.
Melatonin is an important modulator of gene expression related to plant hormones, e.g. in auxin carrier proteins, as well as in metabolism of indole-3-acetic acid (IAA), gibberellins, cytokinins, abscisic acid and ethylene. Most of the studies performed have dealt with the auxin-like activity of melatonin which, in a similar way to IAA, is able to induce growth in shoots and roots and stimulate root generation, giving rise to new lateral and adventitious roots. Melatonin is also able to delay senescence, protecting photosynthetic systems and related sub-cellular structures and processes. Also, its role in fruit ripening and post-harvest processes as a gene regulator of ethylene-related factors is relevant. Another decisive aspect is its role in the pathogen-plant interaction. Melatonin appears to act as a key molecule in the plant immune response, together with other well-known molecules such as nitric oxide and hormones, such as jasmonic acid and salicylic acid. In this sense, the discovery of elevated levels of melatonin in endophytic organisms associated with plants has thrown light on a possible novel form of communication between beneficial endophytes and host plants via melatonin.
Environmental stress is increasing worldwide, yet we lack a clear picture of how stress disrupts the stability of microbial communities and the ecosystem services they provide. Here, we present the ...first evidence that naturally-occurring microbiomes display network properties characteristic of unstable communities when under persistent stress. By assessing changes in diversity and structure of soil microbiomes along 40 replicate stress gradients (elevation/water availability gradients) in the Florida scrub ecosystem, we show that: (1) prokaryotic and fungal diversity decline in high stress, and (2) two network properties of stable microbial communities-modularity and negative:positive cohesion-have a clear negative relationship with environmental stress, explaining 51-78% of their variation. Interestingly, pathogenic taxa/functional guilds decreased in relative abundance along the stress gradient, while oligotrophs and mutualists increased, suggesting that the shift in negative:positive cohesion could result from decreasing negative:positive biotic interactions consistent with the predictions of the Stress Gradient Hypothesis. Given the crucial role microbiomes play in ecosystem functions, our results suggest that, by limiting the compartmentalization of microbial associations and creating communities dominated by positive associations, increasing stress in the Anthropocene could destabilize microbiomes and undermine their ecosystem services.
This work assesses the vertical accuracy of eight Digital Surface Models (DSMs) currently available for Mexico (LiDAR, ALOS AW3D30 V2 and V3, ASTER GDEM V2 and V3, SRTM, NASADEM and Mexico's ...Continuous Elevation Model (CEM)). The AW3D30, ASTER GDEM, SRTM and NASADEM DSMs cover nearly the entire globe and can be downloaded at no cost, while the LiDAR and CEM DSMs are distributed by Mexico's Institute of Geography and Statistics (INEGI). The accuracy of these DSMs is assessed by considering: 1) benchmarks as reference data at the national level, and 2) LiDAR DSM as reference data on six different zones with variability in slope, vegetation cover and elevation. Using geodetic benchmarks as reference elevation on those areas covered by LiDAR (ALiDAR=370,200 km2, nbench=24,175), it was found that LiDAR has the best vertical accuracy of all DSMs considered (MAELiDAR = 1.96), which is why it was used as reference elevation to develop seven DEMs of Difference (DoDs) with the remainder DSMs. Using ncells = 350 × 106 for the aforementioned comparisons, it was found that the vertical accuracy of AW3D30 V2 and V3 is similar (MAE=2.5 m), followed by NASADEM, SRTM, CEM, ASTER GDEM3 and ASTER GDEM 2, with MAE values of 3.1, 3.8, 4.6, 6.0 and 7.2 m respectively. The previously mentioned values vary according to slope and slope orientation (i.e. aspect): for flat areas (slope≤5∘), the NASADEM exhibits the lowest MAE (with MAE values of 1.6 for slope≤1∘ and MAE = 2.0 m when 1∘<slope≤5∘), whereas MAEAW3D30V3=1.9 and 2.2 m for the previously mentioned slopes. With the use of radial boxplots developed on slope groups of 5∘, it was found that both MAE and bias are increasingly affected by aspect as slope increases on all the DSMs. In the case of both AW3D30 DSMs, on flat terrain a difference of only 0.1 m in bias (i.e. median of differences with respect to LiDAR) is found between SE and NW slopes; however, this difference increases according to slope: 0.6 m for 5∘<slope≤10∘, 1.2 m for 10∘<slope≤15∘, and 1.9 m for 15∘<slope≤20∘. Through the analyses undertaken, it is shown that slope—and not vegetation cover—is the factor that has the largest impact on the error of DSMs, and that the effect of aspect on error increases as terrain steepens. This work shows that all DSMs present errors and that an adequate accuracy assessment of DSMs needs to consider the spatial distribution of GCPs, Difference of DSMs (DoDs) and derivatives of DSMs (i.e., slope and aspect) as the use of DoDs provide information on DSM errors (i.e. interpolation artefacts) that can not be assessed through the use of geodetic benchmarks and because DSM errors depend on both slope and aspect.
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Fluorescence in situ hybridization (FISH) has become a powerful technique for prognostic assessment in multiple myeloma (MM). However, the existence of associations between cytogenetic abnormalities ...compels us to re-assess the value of each abnormality. A total of 260 patients with MM at the time of diagnosis, enrolled in the GEM-2000 Spanish transplant protocol, have been analyzed by FISH in order to ascertain the independent influence on myeloma prognosis of IGH translocations, as well as RB and P53 deletions. Survival analyses showed that patients with t(4;14), RB or P53 deletions had a significantly shorter survival than patients without these abnormalities. However, patients with RB deletions without other abnormalities in FISH analysis, displayed a similar outcome to those patients without genetic changes by FISH (46 vs 54 months, P=0.3). In the multivariate analysis the presence of t(4;14), RB deletion associated with other abnormalities, age >60 years, high proportion of S-phase cells and advanced stage of the disease according to the International Staging System retained their independent prognostic influence. In summary, RB deletion as a sole abnormality does not lead to a shortening in the survival of MM patients, whereas t(4;14) confers the worst prognosis in MM patients treated with high-dose chemotherapy.
Ion stopping in warm dense matter is a process of fundamental importance for the understanding of the properties of dense plasmas, the realization and the interpretation of experiments involving ...ion-beam-heated warm dense matter samples, and for inertial confinement fusion research. The theoretical description of the ion stopping power in warm dense matter is difficult notably due to electron coupling and degeneracy, and measurements are still largely missing. In particular, the low-velocity stopping range, that features the largest modelling uncertainties, remains virtually unexplored. Here, we report proton energy-loss measurements in warm dense plasma at unprecedented low projectile velocities. Our energy-loss data, combined with a precise target characterization based on plasma-emission measurements using two independent spectroscopy diagnostics, demonstrate a significant deviation of the stopping power from classical models in this regime. In particular, we show that our results are in closest agreement with recent first-principles simulations based on time-dependent density functional theory.
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