Papel de las hormonas progesterona, estradiol y oxitocina en la función del miometrio durante el embarazo y el trabajo de parto / Role of progesterone, estradiol and oxytocin hormones in myometrial function during pregnancy and labor

Resumen El trabajo de parto es la transición de un estado de inactividad y relajación muscular a un estado de excitación, en el cual la capa muscular del útero (miometrio) realiza crecientes contracciones coordinadas para llevar a cabo la expulsión del feto y la placenta. Durante el inicio del trabajo de parto, el miometrio experimenta una serie de cambios fisiológicos, bioquímicos y moleculares, pasando de un estado de quiescencia a un fenotipo contráctil que inducirá el parto. En parte, esto es provocado por la acción de las hormonas progesterona, estradiol y oxitocina. En general, la progesterona mantiene la quiescencia del miometrio durante el embarazo al inhibir la expresión de moléculas proinflamatorias y proteínas asociadas a la contracción, mientras que al término del embarazo, el estradiol induce la expresión de dichas moléculas. Por su parte, la oxitocina induce un aumento en la concentración de calcio intracelular para llevar a cabo las contracciones de los miocitos uterinos. El objetivo del presente trabajo es presentar un resumen acerca de los mecanismos moleculares involucrados en la regulación de la actividad de las células miometriales por medio de las hormonas progesterona, estradiol y oxitocina, así como discutir las perspectivas de esta interesante área de investigación.

Abstract Labor is the transition from a state of inactivity and muscle relaxation to a state of muscle excitation, in which the muscular layer of the uterus (myometrium) performs increasingly coordinated contractions to deliver the fetus and expel the placenta. During the onset of labor, the myometrium undergoes a series of physiological, biochemical, and molecular changes, allowing the tissue to transition from a quiescent state to a contractile phenotype that will support labor. This is partly caused by the action of the hormones progesterone, estradiol, and oxytocin. In general, progesterone maintains the quiescence of the myometrium during pregnancy by decreasing the expression of proinflammatory molecules and contraction-associated proteins. In contrast, at the end of pregnancy, estradiol induces the expression of these molecules. For its part, oxytocin induces an increase in intracellular calcium concentration to carry out the contractions of uterine myocytes. The objective of this review is to present a summary of the molecular mechanisms involved in regulating myometrial cell activity through the hormones progesterone, estradiol and oxytocin, as well as to discuss the perspectives of this exciting area of research.

BBX24 Interacts with JAZ3 to Promote Growth by Reducing DELLA Activity in Shade Avoidance.

Shade avoidance syndrome (SAS) is a strategy of major adaptive significance and typically includes elongation of the stem and petiole, leaf hyponasty, reduced branching and phototropic orientation of the plant shoot toward canopy gaps. Both cryptochrome 1 and phytochrome B (phyB) are the major photoreceptors that sense the reduction in the blue light fluence rate and the low red:far-red ratio, respectively, and both light signals are associated with plant density and the resource reallocation when SAS responses are triggered. The B-box (BBX)-containing zinc finger transcription factor BBX24 has been implicated in the SAS as a regulator of DELLA activity, but this interaction does not explain all the observed BBX24-dependent regulation in shade light. Here, through a combination of transcriptional meta-analysis and large-scale identification of BBX24-interacting transcription factors, we found that JAZ3, a jasmonic acid signaling component, is a direct target of BBX24. Furthermore, we demonstrated that joint loss of BBX24 and JAZ3 function causes insensitivity to DELLA accumulation, and the defective shade-induced elongation in this mutant is rescued by loss of DELLA or phyB function. Therefore, we propose that JAZ3 is part of the regulatory network that controls the plant growth in response to shade, through a mechanism in which BBX24 and JAZ3 jointly regulate DELLA activity. Our results provide new insights into the participation of BBX24 and JA signaling in the hypocotyl shade avoidance response in Arabidopsis.

Population genetics of wild and captive Trachemysvenusta (Gray, 1856) (Reptilia: Emydidae) in the Usumacinta river basin in Mexico.

The Mesoamerican slider Trachemysvenusta is endemic to Central America and Southern Mexico. Several human-mediated disturbances, including habitat degradation and illegal hunting for food, have impacted its populations along the Usumacinta river basin. The extent to which these disturbances have affected the genetic diversity and population structure of T. venusta inhabiting the basin remains unresolved. To this end, we analyzed eight microsatellite markers in five wild populations of T. venusta from the middle and lower reaches of the basin as well as one captive population. Our results show high levels of genetic diversity for all analyzed populations, low F ST values, high gene flow and no genetic structure, indicating an absence of genetic differentiation across sites and, thus, a single panmictic population for the basin. Evidence of a genetic bottleneck was observed in two of the wild populations (and the captive one), indicating some impact from disturbances, whether from poaching or habitat fragmentation, despite the seemingly high connectivity of most populations. Results are discussed in terms of the relative importance of genetic parameters for the conservation of T. venusta, particularly in light of the importance of demographic stochasticity in local conditions undergoing rapid changes.