1,721,012 research outputs found
The Histidinol Phosphate Phosphatase Involved in Histidine Biosynthetic Pathway Is Encoded by SCO5208 (hisN) in Streptomyces coelicolor A3(2)
No full textThrough the screening of a Streptomyces coelicolor
genomic library, carried out in a histidinol
phosphate phosphatase (HolPase) deficient strain,
SCO5208 was identified as the last unknown gene involved
in histidine biosynthesis. SCO5208 is a phosphatase, and it
can restore the growth in minimal medium in this HolPase
deficient strain when cloned in a high or low copy number
vector. Moreover, it shares sequence homology with other
HolPases recently identified in Actinobacteria. During this
work a second phosphatase, SCO2771, sharing no homologies
with SCO5208 and all so far described phosphatases
was identified. It can complement HolPase activity mutation
only at high copy number. Sequence analysis of
SCO5208 and SCO2771, amplified from the HolPase
mutant strain, revealed that SCO5208 shows a mutation in
a conserved amino acid, whereas SCO2771 does not show
any mutation. All these results show that S. coelicolor
SCO5208, recently renamed hisN, is the HolPase involved
in histidine biosynthesi
Oocyte aging: looking beyond chromosome segregation errors
No full textThe age‐associated decline in female fertility is largely ascribable to a decrease in oocyte quality. This phenomenon is multifaceted and influenced by numerous interconnected maternal and environmental factors. An increase in the rate of meiotic errors is the major cause of the decline in oocyte developmental competence. However, abnormalities in the ooplasm accumulating with age — including altered metabolism, organelle dysfunction, and aberrant gene regulation — progressively undermine oocyte quality. Stockpiling of maternal macromolecules during folliculogenesis is crucial, as oocyte competence to achieve maturation, fertilization, and the earliest phases of embryo development occur in absence of transcription. At the same time, crucial remodeling of oocyte epigenetics during oogenesis is potentially exposed to interfering factors, such as assisted reproduction technologies (ARTs) or environmental changes, whose impact may be enhanced by reproductive aging. As the effects of maternal aging on molecular mechanisms governing the function of the human oocyte remain poorly understood, studies in animal models are essential to deepen current understanding, with translational implications for human ARTs. The present mini review aims at offering an updated and consistent view of cytoplasmic alterations occurring in oocytes during aging, focusing particularly on gene and epigenetic regulation. Appreciation of these mechanisms could inspire solutions to mitigate/control the phenomenon, and thus benefit modern ARTs
Meiotic spindle imaging in human oocytes frozen with a slow freezing procedure involving high sucrose concentration
No full text
The subcortical maternal complex: Emerging roles and novel perspectives
No full textSince its recent discovery, the subcortical maternal complex (SCMC) is emerging as a maternally inherited and crucial biological structure for the initial stages of embryogenesis in mammals. Uniquely expressed in oocytes and preimplantation embryos, where it localizes to the cell subcortex, this multiprotein complex is essential for early embryo development in the mouse and is functionally conserved across mammalian species, including humans. The complex has been linked to key processes leading the transition from oocyte to embryo, including meiotic spindle formation and positioning, regulation of translation, organelle redistribution, and epigenetic reprogramming. Yet, the underlying molecular mechanisms for these diverse functions are just beginning to be understood, hindered by unresolved interplay of SCMC components and variations in early lethal phenotypes. Here we review recent advances confirming involvement of the SCMC in human infertility, revealing an unexpected relationship with offspring health. Moreover, SCMC organization is being further revealed in terms of novel components and interactions with additional cell constituents. Collectively, this evidence prompts new avenues of investigation into possible roles during the process of oogenesis and the regulation of maternal transcript turnover during the oocyte to embryo transition
Sperm DNA fragmentation: paternal effect on early post-implantation embryo development in ART.
No full text
- …
