Multi-Photon Laser Ablation of Cytoplasmic Microtubule Organizing Centers in Mouse Oocytes.

The fidelity of oocyte meiosis is critical for generating developmentally competent euploid eggs. In mammals, the oocyte undergoes a lengthy arrest at prophase I of the first meiotic division. After puberty and upon meiotic resumption, the nuclear membrane disassembles (nuclear envelope breakdown), and the spindle is assembled mainly at the oocyte center. Initial central spindle positioning is essential to protect against abnormal kinetochore-microtubule (MT) attachments and aneuploidy. The centrally positioned spindle migrates in a time-sensitive manner toward the cortex, and this is a necessary process to extrude a tiny polar body. In mitotic cells, spindle positioning relies on the interaction between centrosome-mediated astral MTs and the cell cortex. On the contrary, mouse oocytes lack classic centrosomes and, instead, contain numerous acentriolar MT organizing centers (MTOCs). At the metaphase I stage, mouse oocytes have two different sets of MTOCs: (1) MTOCs that are clustered and sorted to assemble spindle poles (polar MTOCs), and (2) metaphase cytoplasmic MTOCs (mcMTOCs) that remain in the cytoplasm and do not contribute directly to spindle formation but play a crucial role in regulating spindle positioning and timely spindle migration. Here, a multi-photon laser ablation method is described to selectively deplete endogenously labeled mcMTOCs in oocytes collected from Cep192-eGfp reporter mice. This method contributes to the understanding of the molecular mechanisms underlying spindle positioning and migration in mammalian oocytes.

Hipercetonemia: bioquímica de la producción de ácidos grasos volátiles y su metabolismo hepático / Hyperketonemia: Biochemistry of volatile fatty acid production and its hepatic metabolism

RESUMEN La hipercetonemia o cetosis bovina es un desorden metabólico, que se caracteriza por el incremento patológico de cuerpos cetónicos (beta-hidroxibutirato (βHB), Acetoacetato (AcAc) y acetona) y ocurre en el periparto de vacas de leche. El origen primario de la enfermedad es el balance energético negativo (BEN), que puede ser desencadenado por el incremento excesivo de los requerimientos energéticos o la presentación de enfermedades posparto, resultando en la presentación de signos clínicos o disminución de la producción de leche. El objetivo de esta revisión consiste en describir, mediante un modelo, los procesos bioquímicos del rumen y los mecanismos fisiopatológicos, involucrados con incremento excesivo de los cuerpos cetónicos. En resumen, se realizó un modelo fisiológico uniendo literatura fragmentada, sobre la relación entre la función ruminal, hepática y la inducción de lipolisis e incremento de la actividad de Carnitil-Palmitoil transferasa-1 (CPT-1), cuyo resultado puede ser la producción excesiva de Acetil-CoA que, junto con la falta de propionato y oxalacetato (precursores de gluconeogénesis y ciclo de Krebs), dan lugar a la producción patológica de acetoacetato y beta-hidroxibutirato.

ABSTRACT Bovine hyperketonemia or ketosis is a metabolic disorder characterized by high levels of ketone bodies (beta-hydroxybutyrate (βHB), Acetoacetate (AcAc), and acetone) in periparturient dairy cows. A Negative Energy Balance (NEB) is identified as the primary cause of the disease, which is triggered by the excessive increase of energy requirements or the presence of postpartum diseases, resulting in the appearance of clinical signs or decreased milk production. The purpose of this review is to describe the rumen's biochemical Process and the physiopathological mechanisms involved in the excessive production of ketone bodies. After conducting a literature review, a physiological model was carried out in order to understand the relationship between the rumen and liver functions with lipolysis induction and increased CPT-1 activity. The above may result in the overproduction of Acetyl-CoA, which together, with the lack of propionate and oxaloacetate (gluconeogenesis and Krebs cycle precursors), leads to the pathological production of acetoacetate and beta-hydroxybutyrate.