Biology subjects

Lobo, R.

Publications and source records attributed to Lobo, R..

6 recordsLinked to original sources

bioRxiv2025

Low nucleus to cytoplasmic ratio compromises cytokinesis, genome stability and development in haploid embryonic cells

Mammalian species exist as diploid organisms, with only gametes existing as stable, nonproliferating haploids. Haploid mammalian pluripotent stem cells, in all derived species to date - mouse, human and rat - undergo spontaneous diploidization. Here, we investigated the mechanisms affecting the stability of the haploid state using the mouse and human embryo, as well as a human embryonic stem cells. We demonstrate that diploidization occurs early in preimplantation development and is often unproductive, with haploid embryos exhibiting decreased developmental potential. Haploid embryos show increased chromosome segregation errors at the first mitosis, failure to align chromosomes on the metaphase plate in the second mitosis. Delayed mitotic progression and failure to form a central spindle and a midbody are followed by cytokinesis failure, diploidization, increased DNA damage marked by {gamma}H2AX and RPA32 foci, and low developmental potential. By increasing the nucleo-cytoplasmic ratio in diploids, or reducing this ratio in haploids, these phenotypes can be induced in diploids or reduced in haploids. Changing ploidy alone from haploid to diploid without also adjusting nucleo-cytoplasmic ratio does not improve mitotic phenotypes and developmental outcomes. Thus, the most upstream driver responsible for the instability of the haploid state is a stage- specific ratio of nucleus to cell size.

cell biology↗

bioRxiv2022

Polyethylene valorization by combined chemical catalysis with bioconversion by plastic-enriched microbial consortia

There are few reports of microbial deconstruction or functionalization of the recalcitrant backbone of polyolefins. However, microbes can utilize polyolefin deconstruction products, including n-alkanes. Here, we combined chemical catalysis with bioconversion to valorize polyethylene (PE) deconstruction products. High-density PE (HDPE) was deconstructed via hydrogenolysis over a ruthenium on carbon catalyst. The resulting n-alkane mixture (C4-C35) was utilized as a feedstock for microbial consortia derived from soil from local recycling plants. We found two consortia that utilized the PE-deconstruction product mix as a sole carbon source. We adapted the consortia on a commercially-available n-alkane mix to reduce the number of species present and enrich for enhanced alkane utilization. Both resulting enriched consortia utilized the PE-deconstruction product mix more effectively than the original (parent) consortia. The predominant metabolite produced by both enriched consortia was a C16-C16 wax ester. Wax esters have considerable industrial value, with the longer chain lengths (C32-C36) having the highest value. We identified two Rhodococcus aetherivorans strains that grow well on C24, indicating this species is important for the functionalization of long-chain alkanes. This work demonstrates that enriched consortia from plastic-enriched environments can be combined with chemical catalysis to valorize polyethylene. SynopsisChemical catalysis can be used to deconstruct polyethylene waste material to produce a mixture of alkanes. Enriched environmental microbial consortia can valorize these polyethylene deconstruction products via functionalization that preserves the alkane chain length thus minimizing CO2 production.

bioengineering↗

bioRxiv2022

The regulatory landscapes of human ovarian ageing

Summary paragraphThe ovary is the first organ to age in the human body, affecting both fertility and overall health in women1-8. However, the biological mechanisms underlying human ovarian ageing remain poorly understood. Here we performed single-nuclei multi-omics analysis of young and reproductively aged human ovaries to understand the molecular and cellular basis of ovarian ageing in humans. Our analysis reveals coordinated changes in transcriptomic output and chromatin accessibility across cell types during ageing, including elevated mTOR and MAPK signaling, decreased activity of the oxidative phosphorylation and DNA damage repair pathways, and an increased signature of cellular senescence. By constructing cell type-specific regulatory networks, we uncover enhanced activity of the transcription factor CEBPD across cell types in the aged ovary, with a corresponding significant loss of activity of most cell identity-associated transcription factors. Moreover, by performing integrative analyses of our single-nuclei multi-omics data with common genetic variants associated with age at natural menopause (ANM) from genome-wide association studies, we demonstrate a global impact of functional variants on changes in gene regulatory networks across ovarian cell types. Finally, we nominate about a dozen of functional non-coding variants, their target genes and cell types and regulatory mechanisms that underlie genetic association with ANM. This work provides a comprehensive multimodal landscape of human ovarian ageing and mechanistic insights into inherited variation of ANM.

genomics↗

bioRxiv2022

Evaluation of the antimicrobial, anti-adhesion, anti-biofilm and cell proliferation assay of a de-novo goji berry extract against periodontal pathogens: a comparative in-vitro study

Lycium barbarum, commonly known as goji berry, Chinese berry, or Tibetian berry, is emerging as a popular "superfood" with anti-inflammatory and antioxidant properties. Goji berry is being used for the treatment of various cancers, gastrointestional disorders, stroke, diabetes, Alzheimers disease, and glaucoma. However, its use for management of oral inflammatory diseases has not been explored. Therefore, the present study aims to evaluate the antimicrobial, anti-adhesion, and anti-biofilm, and cytotoxic properties of an ethanolic extract of Lycium barbarum (LBE) against oral and periodontal pathogens. The antimicrobial properties of LBE against five microorganisms were tested and compared against Chlorhexidine and doxycycline along with cytotoxicity and cell viability on the gingival fibroblast and modified keratinocyte cell lines. The anti-adhesion and anti-biofilm properties of LBE against Porphyromonas gingivalis, at its minimal bactericidal value, were evaluated. The antimicrobial, anti-adhesion and antibiofilm properties of LBE were found to be comparable to chlorhexidine but less than that of doxycycline. The LBE extract was also compactible to gingival fibroblast tissues and oral keratinocytes at 1 mg/ml. The results proved that goji berry is as effective as chlorhexidine and can be used as a promising natural herb for the management of inflammatory diseases of oral cavity.

microbiology↗

bioRxiv2021

Sesamol and its derivative investigated as antiandrogen - A potential prevention to prostate cancer in rats

Androgen signaling is essential for the development of prostate cancer (PCa) initiated from prostatic basal cells with collocation of androgen receptor gene mutations. Phytoestrogens, the naturally occurring compounds are AR antagonist. These compounds downregulate prostate-specific antigen (PSA) expression and cell proliferation. Thus, this gives a track to research these compounds as a possible treatment for PCa. In this work, STITCH and molecular docking predict the conformation of ligands inside the suitable target binding site. Therefore, a study was planned to know the interactions among SM and its derivatives with AR. It was further, evaluated for in vitro evaluation on LNCaP, PC-3, and DU-145 using MTT studies. The two lead compounds shortlisted from MTT studies were further analyzed for androgen-regulated genes by using RT-PCR, western blot studies and an animal model of prostate cancer. We found that SM and its derivative (3-MA) may prevent the development of PCa by androgen pathway.

cancer biology↗

bioRxiv2020

Reading frame restoration at the EYS locus, and allele-specific chromosome removal after Cas9 cleavage in human embryos

The correction of disease-causing mutations in human embryos could reduce the burden of inherited genetic disorders in the fetus and newborn, and improve the efficiency of fertility treatments for couples with disease-causing mutations in lieu of embryo selection. Here we evaluate the repair outcomes of a Cas9-induced double-strand break (DSB) introduced on the paternal chromosome at the EYS locus, which carries a frame-shift mutation causing blindness. We show that the most common repair outcome is microhomology-mediated end joining, which occurs during the first cell cycle in the zygote, leading to embryos with non-mosaic restoration of the reading frame. However, about half of the breaks remain unrepaired, resulting in an undetectable paternal allele and, upon entry into mitosis, loss of one or both chromosomal arms. Thus, Cas9 allows for the modification of chromosomal content in human embryos in a targeted manner, which may be useful for the prevention of trisomies. HighlightsO_LICas9-mediated DSB induction and repair by end joining occurs within hours C_LIO_LIEnd joining provides an efficient way to restore reading frames without mosaicism C_LIO_LIUnrepaired DSBs persist through mitosis and result in frequent chromosome loss C_LI

genetics↗