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Anurans are famous for having evolved a highly simplified skull through bone loss and fusion events. Nevertheless, their skeleton displays a rich morphological diversity associated with adaptations to diverse lifestyles and ecological niches. Here, we report larval skull ossification in the Andean toad Rhinella spinulosa (Bufonidae), and compare it to the phylogenetically distant genetic model organism Xenopus tropicalis (Pipidae). We find that the ossification timing of most skull bones is conserved between both species, except for the prootic and the angulosplenial that ossify at much later stages in R. spinulosa than X. tropicalis. We propose that a delayed lower jaw ossification in R. spinulosa is tightly related to the more extensive metamorphosis process observed in this species where the ventrally oriented mouth opening shifts anteriorly. We also report two conspicuous notches in the R. spinulosa frontoparietal bone mineralization front which are absent in X. tropicalis, and presumably represent evolutionary remnants of the coronal suture that separates the frontal and parietal bones in most vertebrates. As such notches have not been overtly reported in the literature, we examined the X. tropicalis sibling species Xenopus laevis, and were able to identify similar, albeit transient, indentations in the forming frontoparietal bone, suggesting that vestigial coronal sutures might exist in more frog species than anticipated. Taken together, we show that R. spinulosa represents an ideal organism to study heterochronic shifts and the mechanisms underlying cranial suture loss which drove anuran skull simplification., (© 2024 Wiley Periodicals LLC.)

Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD + ; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis . Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation.

The heterotrimeric G protein family plays essential roles during a varied array of cellular events; thus, its deregulation can seriously alter signaling events and the overall state of the cell. Heterotrimeric G-proteins have three subunits (α, β, γ) and are subdivided into four families, Gαi, Gα12/13, Gαq, and Gαs. These proteins cycle between an inactive Gα-GDP state and active Gα-GTP state, triggered canonically by the G-protein coupled receptor (GPCR) and by other accessory proteins receptors independent also known as AGS (Activators of G-protein Signaling). In this review, we summarize research data specific for the Gαi family. This family has the largest number of individual members, including Gαi1, Gαi2, Gαi3, Gαo, Gαt, Gαg, and Gαz, and constitutes the majority of G proteins α subunits expressed in a tissue or cell. Gαi was initially described by its inhibitory function on adenylyl cyclase activity, decreasing cAMP levels. Interestingly, today Gi family G-protein have been reported to be importantly involved in the immune system function. Here, we discuss the impact of Gαi on non-canonical effector proteins, such as c-Src, ERK1/2, phospholipase-C (PLC), and proteins from the Rho GTPase family members, all of them essential signaling pathways regulating a wide range of physiological processes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Villaseca, Romero, Ruiz, Pérez, Leal, Tovar and Torrejón.)

The neurulation process is regulated by a large amount of genetic and environmental factors that determine the establishment, folding, and fusion of the neural plate to form the neural tube, which develops into the main structure of the central nervous system. A recently described factor involved in this process is glutamate. Through NMDA ionotropic receptor, glutamate modifies intracellular Ca 2+ dynamics allowing the oriented cell migration and proliferation, essentials processes in neurulation. Glutamate synthesis depends on the mitochondrial enzyme known as glutaminase 1 (GLS1) that is widely expressed in brain and kidney. The participation of GLS 1 in prenatal neurogenic processes and in the adult brain has been experimentally established, however, its participation in early stages of embryonic development has not been described. The present investigation describes for the first time the presence and functionality of GLS1 in Xenopus laevis embryos during neurulation. Although protein expression levels remains constant, the catalytic activity of GLS1 increases significantly (~66%) between early (stage 12) and middle to late (stages 14-19) neurulation process. Additionally, the use of 6-diazo-5-oxo-L-norleucine (L-DON, competitive inhibitor of glutamine-depend enzymes), reduced significantly the GLS1 specific activity during neurulation (~36%) and induce the occurrence of neural tube defects involving its possible participation in the neural tube closure in Xenopus laevis embryos., (Copyright © 2020 Benavides-Rivas, Tovar, Zúñiga, Pinto-Borguero, Retamal, Yévenes, Moraga-Cid, Fuentealba, Guzmán, Coddou, Bascuñán-Godoy and Castro.)

This paper examined the association between individual and local level factors and the number of antenatal care visits completed by women in Colombia using data from the 2010 Colombian Demographic and Health Survey and multilevel logistic regression models. Our findings suggest that, in addition to maternal socioeconomic status, contextual factors influence whether pregnant women complete the minimum recommended number of antenatal care visits. These factors include: level of women's autonomy in the community, regional inequalities and access barriers caused by distance (OR = 0.057), costs of services (OR = 0.035), and/or a lack of confidence in doctors (OR = 0.036). Our results highlight the existence of inequalities in access to antenatal care and the importance of considering the local context in the design of effective maternal care policies in Colombia. Furthermore, our findings regarding individual factors corroborate the evidence from other countries and offer new insights into the association between local level factors and number of antenatal care visits.

The purpose of this study was to assess the prevalence of, and the factors associated with HIV testing and pre- and post-test counselling (PPTC) in Colombia. Cross-sectional data from the National Health Survey carried out during 2007 were analysed. Data were gathered from records of 29,760 individuals between the ages of 18 and 69 from the main regions of the country. Only 19.7% of the sample had taken an HIV test. Men, people with no education, those not affiliated with the health-care system, residents of rural areas and those aged older than 65 were less likely to have been tested for HIV; 42% of those tested did not receive pre-test counselling and 56.9% received no report of the results. Considering the low prevalence of HIV testing among the Colombian population, it is necessary to design and apply guidelines for HIV screening in all health-care settings and to conduct targeted testing in high-risk sub-populations. A national norm of PPTC in those who undergo HIV testing should be examined.