Istmocele y fertilidad: revisión de la literatura a propósito de un caso / Isthmocele and fertility: A case report and review of the literature

Una de las complicaciones que puede derivarse de una cesárea es el istmocele. En muchos casos este será asintomático y puede pasar desapercibido, pero en ocasiones da lugar a sintomatología, como por ejemplo sangrado uterino anómalo, infertilidad secundaria, o bien problemas en un futuro embarazo, como acretismo placentario o rotura uterina. Existe a día de hoy mucha controversia sobre el diagnóstico de esta entidad y su posible tratamiento. La motivación de este estudio es presentar una breve revisión de la literatura a raíz de un caso clínico sobre una paciente con istmocele e infertilidad secundaria.(AU)

One of the complications that can result from a caesarean section is isthmocele. In many cases, it will be asymptomatic and can go unnoticed, but sometimes it leads to symptoms such as abnormal uterine bleeding, secondary infertility, or problems in a future pregnancy such as placental accreta or uterine rupture. There is currently much controversy about the diagnosis of this entity and its possible treatment. The aim of the present study is to present a brief review of the literature based on a case report of a patient with isthmocele and secondary infertility.(AU)

[SARS-CoV-2 pandemic and assisted reproduction]. / Pandemia del SARS-CoV-2 y reproducción asistida.

The pandemic caused by the new SARS-CoV-2 virus has led to a process of adaptation to the new situation by society as a whole and, therefore, by assisted reproduction centres. After the acute phase of the health crisis, when activity was drastically reduced, cycles have resumed, guided by the recommendations of scientific societies.In this article, a review is presented of all the published information regarding the virus and the reproductive system, pointing out the presence of angiotensin-converting enzyme 2 (ACE2) in the female and male reproductive system, at the testicular, ovarian, endometrial and embryonic levels. In addition, a comparative analysis is carried out between the recommendations of the scientific societies regarding the screening of infection, performance standards, and general laboratory measurements.

Compartmentalization of the cell cortex by septins is required for maintenance of cell polarity in yeast.

Formation and maintenance of specialized plasma membrane domains are crucial for many biological processes, such as cell polarization and signaling. During isotropic bud growth, the yeast cell periphery is divided into two domains: the bud surface, an active site of exocytosis and growth, and the relatively quiescent surface of the mother cell. We found that cells lacking septins at the bud neck failed to maintain the exocytosis and morphogenesis factors Spa2, Sec3, Sec5, and Myo2 in the bud during isotropic growth. Furthermore, we found that septins were required for proper regulation of actin patch stability; septin-defective cells permitted to enter isotropic growth lost actin and growth polarity. We propose that septins maintain cell polarity by specifying a boundary between cortical domains.

Polarized growth controls cell shape and bipolar bud site selection in Saccharomyces cerevisiae.

We examined the relationship between polarized growth and division site selection, two fundamental processes important for proper development of eukaryotes. Diploid Saccharomyces cerevisiae cells exhibit an ellipsoidal shape and a specific division pattern (a bipolar budding pattern). We found that the polarity genes SPA2, PEA2, BUD6, and BNI1 participate in a crucial step of bud morphogenesis, apical growth. Deleting these genes results in round cells and diminishes bud elongation in mutants that exhibit pronounced apical growth. Examination of distribution of the polarized secretion marker Sec4 demonstrates that spa2Delta, pea2Delta, bud6Delta, and bni1Delta mutants fail to concentrate Sec4 at the bud tip during apical growth and at the division site during repolarization just prior to cytokinesis. Moreover, cell surface expansion is not confined to the distal tip of the bud in these mutants. In addition, we found that the p21-activated kinase homologue Ste20 is also important for both apical growth and bipolar bud site selection. We further examined how the duration of polarized growth affects bipolar bud site selection by using mutations in cell cycle regulators that control the timing of growth phases. The grr1Delta mutation enhances apical growth by stabilizing G(1) cyclins and increases the distal-pole budding in diploids. Prolonging polarized growth phases by disrupting the G(2)/M cyclin gene CLB2 enhances the accuracy of bud site selection in wild-type, spa2Delta, and ste20Delta cells, whereas shortening the polarized growth phases by deleting SWE1 decreases the fidelity of bipolar budding. This study reports the identification of components required for apical growth and demonstrates the critical role of polarized growth in bipolar bud site selection. We propose that apical growth and repolarization at the site of cytokinesis are crucial for establishing spatial cues used by diploid yeast cells to position division planes.

Regulation of cytokinesis by the Elm1 protein kinase in Saccharomyces cerevisiae.

A Saccharomyces cerevisiae mutant unable to grow in a cdc28-1N background was isolated and shown to be affected in the ELM1 gene. Elm1 is a protein kinase, thought to be a negative regulator of pseudo-hyphal growth. We show that Cdc11, one of the septins, is delocalised in the mutant, indicating that septin localisation is partly controlled by Elm1. Moreover, we show that cytokinesis is delayed in an elm1delta mutant. Elm1 levels peak at the end of the cell cycle and Elm1 is localised at the bud neck in a septin-dependent fashion from bud emergence until the completion of anaphase, at about the time of cell division. Genetic and biochemical evidence suggest that Elm1 and the three other septin-localised protein kinases, Hsl1, Gin4 and Kcc4, work in parallel pathways to regulate septin behaviour and cytokinesis. In addition, the elm1delta;) morphological defects can be suppressed by deletion of the SWE1 gene, but not the cytokinesis defect nor the septin mislocalisation. Our results indicate that cytokinesis in budding yeast is regulated by Elm1.

Nim1-related kinases coordinate cell cycle progression with the organization of the peripheral cytoskeleton in yeast.

The mechanisms that couple cell cycle progression with the organization of the peripheral cytoskeleton are poorly understood. In Saccharomyces cerevisiae, the Swe1 protein has been shown previously to phosphorylate and inactivate the cyclin-dependent kinase, Cdc28, thereby delaying the onset of mitosis. The nim1-related protein kinase, Hsl1, induces entry into mitosis by negatively regulating Swe1. We have found that Hsl1 physically associates with the septin cytoskeleton in vivo and that Hsl1 kinase activity depends on proper septin function. Genetic analysis indicates that two additional Hsl1-related kinases, Kcc4 and Gin4, act redundantly with Hsl1 to regulate Swe1. Kcc4, like Hsl1 and Gin4, was found to localize to the bud neck in a septin-dependent fashion. Interestingly, hsl1 kcc4 gin4 triple mutants develop a cellular morphology extremely similar to that of septin mutants. Consistent with the idea that Hsl1, Kcc4, and Gin4 link entry into mitosis to proper septin organization, we find that septin mutants incubated at the restrictive temperature trigger a Swe1-dependent mitotic delay that is necessary to maintain cell viability. These results reveal for the first time how cells monitor the organization of their cytoskeleton and demonstrate the existence of a cell cycle checkpoint that responds to defects in the peripheral cytoskeleton. Moreover, Hsl1, Kcc4, and Gin4 have homologs in higher eukaryotes, suggesting that the regulation of Swe1/Wee1 by this class of kinases is highly conserved.

G1 cyclin turnover and nutrient uptake are controlled by a common pathway in yeast.

Entry into a new cell cycle is triggered by environmental signals at a point called Start in G1 phase. A key regulator of this transition step in yeast is the CDC28 kinase together with its short-lived regulatory subunits called G1-cyclins or CLN proteins. To identify genes involved in G1-cyclin degradation, we employed a genetic screen by selecting for stable CLN1-beta-galactosidase fusion proteins. Surprisingly, one group of mutants was found to be allelic to GRR1, a gene previously described to be involved in glucose uptake, glucose repression, and divalent cation transport. In grr1 mutants, both CLN1 and CLN2 cyclins are significantly stabilized. A suppressor analysis indicated that G1-cyclin stabilization in grr1 was not a consequence of the nutrient uptake defect. This suggests that the GRR1 gene product is part of a common regulatory pathway linking two functions important for cell growth, nutrient uptake, and G1 cyclin-controlled cell division.

[G1 cyclin degradation and cell differentiation in Saccharomyces cerevisiae]. / Dégradation des cyclines G1 et différenciation cellulaire chez Saccharomyces cerevisiae.

The baker's yeast Saccharomyces cerevisiae can undergo pseudohyphal differentiation upon limited starvation for nitrogen. This differentiation is characterized by a hyperpolarized cell growth that gives rise to elongated cells. These elongated cells can form chains that penetrate an agar surface. The study of the grr1 mutant, affected in the degradation of the G1 cyclins, showed that the stabilization of Cln1 and Cln2 leads to a similar hyperpolarized cell growth. We suggest that G1 cyclin stability is a key element controlling cellular morphogenesis. Examination of G1 cyclin turnover during pseudohyphal growth strongly supports this hypothesis. Saccharomyces cerevisiae is thus an interesting model for studying the interconnections between cell cycle control and cellular differentiation.