Biology subjects

Loi, P.

Publications and source records attributed to Loi, P..

4 recordsLinked to original sources

bioRxiv2025

Protamine sequence determines species-specific nuclear shape and histone retention

Nuclear shape observed after the forced expression of mouse or human Protamine 1 (PRM1) in fibroblasts led us to propose the hypothesis that PRM1 sequence plays an important role in imposing the overall shape of the protaminized nucleus. Comparison of mouse and human PRM1 sequence pointed to cysteines 15 and 29 as potential critical residues in the mouse PRM1 sequence inducing the characteristic mouse "hooked" nuclear sperm shape. To explore this idea, mice with mutations in PRM1 Cys15 and Cys29 were generated. These mice remained fertile with no significant changes in sperm count or protamine expression levels. However, modifications in sperm head shape were observed. Transmission electron microscopy revealed disrupted chromatin condensation in mutant sperm, with several morphological changes and a remarkable increase in histone retention. Overall, the findings suggest that species-specific PRM1 cysteine residue positions are crucial for nuclear shape determination and histone retention in spermatozoa.

developmental biology↗

bioRxiv2025

TGF-β3 Promotes Trophoblast Development via ACSS2-Dependent Permissive Lipid Metabolism

Transforming growth factor-beta (TGF-{beta}) supports the in vitro maintenance of embryonic and trophoblast stem cells. Here, we demonstrated that, in a sheep embryo model, the transition from morula to blastocyst is positively regulated by TGF-{beta}3, primarily through its promotion of trophoblast development. Our results indicate that morulae treated with TGF-{beta}3 develop at a higher rate into blastocysts, characterized by an expanded trophoblast layer marked by CDX-2 expression. In blastocysts, TGF-{beta}3 mediates transcriptional activation of genes involved in cell adhesion and lipid metabolism pathways, leading to remarkable in vitro outgrowth expansion and a substantial increase in trophoblast lipid droplet content. Functional analysis reveal that the positive effects of TGF-{beta}3 are mitigated by inhibition of Acetyl-CoA Synthetase Short-Chain Family Member 2 (ACSS2), a key enzyme upregulated by TGF-{beta}3 and a promoter of de novo lipgenensis. These findings suggest that TGF-{beta}3 modulates lipid metabolism during blastocyst formation and may play a potential role in regulating implantation and placental development.

developmental biology↗

bioRxiv2024

Fertility Preservation of Vacuum-Dried Ram Spermatozoa Stored for Four Years at Room Temperature

Dry storage at room temperature (RT) could simplify spermatozoa banking. Here, we explored DNA stability and in vitro and in vivo development of embryos derived from vacuum-dried encapsulated (VDE) ram spermatozoa stored for four years or after accelerated aging. While some genomic damage was detected at time 0, DNA fragmentation increased from 3.32{+/-}3% (time 0) to 37.64{+/-}4% (4 years). A decrease in blastocyst rate was observed after four years of storage and 6.7 years of simulated storage (10.2% and 9% versus 13.16% at time 0). Embryo quality, assessed based on Cdx2 and Inf-{tau} gene expression, declined over time. Only two of the 23 embryos transferred into synchronized ewes were implanted but were lost by day 40. In conclusion, dry spermatozoa generated blastocysts after four years of RT storage, but their post-implantation development was impaired. Optimization of the water extraction and storage conditions could better preserve the spermatozoas DNA integrity, resulting in improved embryo quality, compatible with development to term.

physiology↗

bioRxiv2019

Late Embryogenesis Abundant (LEA) proteins confer water stress tolerance to mammalian somatic cells

Late Embryogenesis Abundant (LEA) proteins are commonly found in organisms capable of undergoing reversible dehydration - \"anhydrobiosis\". Here, we have produced three LEA proteins: pTag-RAB17-GFP-N, Zea mays dehydrin-1dhn, expressed in the nucleo-cytoplasm; pTag-WCOR410-RFP, Tricum aestivum cold acclimation protein WCOR410, binding to cellular membranes, and pTag-LEA-BFP, Artemia franciscana LEA protein group 3 that targets the mitochondria. Somatic cells transfected with three LEA proteins were subjected to desiccation under controlled conditions, followed by rehydration, viability assessment and membrane/mitochondria functional tests were performed. Results shown that LEA protect cells from desiccation injury. Cells expressed all LEA proteins shown very high percentage of viable cells (58%) after four hour of desiccation compare to un-transfected cells (1% cell alive). Plasmalemma, cytoskeleton and mitochondria appeared unaffected in LEA-expressing cells, confirming their protective action during the entire desiccation and rehydration process. Here, we show that natural xeroprotectants (LEA proteins) transiently expressed in somatic cells confer them desiccation tolerance.

cell biology↗