Biology subjects

Masson, L.

Publications and source records attributed to Masson, L..

4 recordsLinked to original sources

bioRxiv2026

SEPALLATA MADS transcription factors act as key regulators in fertilization efficiency, ovule outer integument growth and mucilage secretory cell differentiation in Arabidopsis

In angiosperms, ovule development requires the activity of the C, D and E classes of MADS genes, which encode key transcriptional regulators of reproductive development. The SEPALLATA (SEP) MADS transcription factors (MTFs), which belong to the E class, act as organizing hubs of MADS heterotetrameric complexes and play an essential role in the development of flower organs. However, the role of the SEP genes in ovule and seed development has been difficult to determine due to redundancy in the subclade, the lack of observable phenotypes in single and double sep1 sep2 mutants and the homeotic conversion of the carpel into sepal or leaf in higher order sep mutants. Here, we engineered a version of SEP3 (SEP3{Delta}M) that encodes a protein lacking the DNA-binding MADS-domain but retains the oligomerization domains needed for MADS protein heterotetramerization. In vitro experiments demonstrated the ability of SEP3{Delta}M to interact with the C and D classes of MTF, reducing the capability of such MADS complex to efficiently bind DNA. sep3{Delta}M plants showed a delay in flower opening and organ maturation and a reduced fertility. The ovules exhibited reduced outer integument growth, and the few seeds that developed showed impaired mucilage secretion upon imbibition. RNA-seq analysis of sep3{Delta}M demonstrated misregulation of genes involved in outer integument and seed coat development. Taken together, these data indicate the key role of SEP3-containing MADS complexes in proper ovule outer integument growth and seed coat development.

plant biology↗

bioRxiv2026

Characterisation of vaginal Lactobacillus isolates from South African women towards the development of a biotherapeutic to optimise the vaginal microbiome

HIV remains among the worlds most serious healthcare challenges, with adolescent girls and young women in sub-Saharan Africa at particularly high risk of infection. Bacterial vaginosis (BV) is a key risk factor for HIV acquisition, however current treatment strategies are limited. Optimal vaginal Lactobacillus spp. protect against BV and HIV, largely through immunoregulatory and antimicrobial activities mediated in part by lactic acid. Towards the development of a Lactobacillus-containing live biotherapeutic for African women, we sampled 181 vaginal Lactobacillus isolates from 25 BV-negative South African women. Fifty isolates were selected for evaluation of inflammatory responses using vaginal epithelial cells, D- and L-lactate and lactic acid production and culture acidification. Aside from a single Lactobacillus salivarius strain, L. crispatus isolates acidified the culture media the most and produced the most D- and L-lactic acid. Inflammatory cytokine responses to Lactobacillus strains were variable, with L. crispatus eliciting the lowest levels of cytokine production. When all properties were evaluated collectively, L. crispatus strains exhibited the most desirable biotherapeutic characteristics. Whole genome sequence analysis of ten L. crispatus isolates showed that the majority were more closely related to one another than to isolates from other geographical regions. This supports the need for live biotherapeutics to be tailored for the population of intended use. No antimicrobial resistance elements were detected, while putative bacteriocins and intact prophage sequences were identified in all isolates. L. crispatus isolates displayed characteristics essential for optimal live biotherapeutic performance, however additional analysis is required to determine the functionality of identified putative prophages. ImportanceHIV is a leading cause of morbidity and mortality in sub-Saharan Africa, where adolescent girls and young women are three times more likely to acquire HIV than their male counterparts. A key risk factor for HIV is bacterial vaginosis (BV), a condition characterised by the loss of beneficial Lactobacillus species and increased abundance of non-optimal, inflammatory bacteria. Although BV affects approximately 25% of women in sub-Saharan Africa, effective therapeutics are lacking. Live biotherapeutics containing optimal Lactobacillus spp. represent a promising strategy to improve BV treatment outcomes and reduce HIV infection risk. We isolated 181 vaginal Lactobacillus spp. from 25 BV-negative South African women and characterized 50 selected isolates. This led to the identification of live biotherapeutic candidates for African women with distinct genomes compared to isolates from other geographical regions. This study contributes to current knowledge of the characteristics that should be considered when screening novel isolates for this purpose.

microbiology↗

bioRxiv2020

Microbial function and genital inflammation in young South African women at high risk of HIV infection

BackgroundFemale genital tract (FGT) inflammation is an important risk factor for HIV acquisition. The FGT microbiome is closely associated with inflammatory profile, however, the relative importance of microbial activities has not been established. Since proteins are key elements representing actual microbial functions, this study utilized metaproteomics to evaluate the relationship between FGT microbial function and inflammation in 113 young and adolescent South African women at high risk of HIV infection. Women were grouped as having low, medium or high FGT inflammation by K-means clustering according to pro-inflammatory cytokine concentrations. ResultsA total of 3,186 microbial and human proteins were identified in lateral vaginal wall swabs using liquid chromatography-tandem mass spectrometry, while 94 microbial taxa were included in the taxonomic analysis. Both metaproteomics and 16S rRNA gene sequencing analyses showed increased non-optimal bacteria and decreased lactobacilli in women with FGT inflammatory profiles. However, differences in the predicted relative abundance of most bacteria were observed between 16S rRNA gene sequencing and metaproteomics analyses. Bacterial protein functional annotations (gene ontology) predicted inflammatory cytokine profiles more accurately than bacterial relative abundance determined by 16S rRNA gene sequence analysis, as well as functional predictions based on 16S rRNA gene sequence data (p<0.0001). The majority of microbial biological processes were underrepresented in women with high inflammation compared to those with low inflammation, including a Lactobacillus-associated signature of reduced cell wall organization and peptidoglycan biosynthesis. This signature remained associated with high FGT inflammation in a subset of 74 women nine weeks later, was upheld after adjusting for Lactobacillus relative abundance, and was associated with in vitro inflammatory cytokine responses to Lactobacillus isolates from the same women. Reduced cell wall organization and peptidoglycan biosynthesis were also associated with high FGT inflammation in an independent sample of ten women. ConclusionsBoth the presence of specific microbial taxa in the FGT and their properties and activities are critical determinants of FGT inflammation. Our findings support those of previous studies suggesting that peptidoglycan is directly immunosuppressive, and identify a possible avenue for biotherapeutic development to reduce inflammation in the FGT. To facilitate further investigations of microbial activities, we have developed the FGT-METAP application that is available at (http://immunodb.org/FGTMetap/).

microbiology↗

bioRxiv2018

Nitrogen- and phosphorus-starved Triticum aestivum show distinct belowground microbiome profiles

Many plants have natural partnerships with microbes that can boost their nitrogen (N) and/or phosphorus (P) acquisition. To assess whether wheat may have undiscovered associations of these types, we tested if N/P-starved Triticum aestivum show microbiome profiles that are simultaneously different from those of N/P-amended plants and those of their own bulk soils. The bacterial and fungal communities of root, rhizosphere, and bulk soil samples from the Historical Dryland Plots (Lethbridge, Canada), which hold T. aestivum that is grown both under N/P fertilization and in conditions of extreme N/P-starvation, were taxonomically described and compared (bacterial 16S rRNA genes and fungal Internal Transcribed Spacers - ITS). As the list may include novel N- and/or P-providing wheat partners, we then identified all the operational taxonomic units (OTUs) that were proportionally enriched in one or more of the nutrient starvation- and plant-specific communities. These analyses revealed: a) distinct N-starvation root and rhizosphere bacterial communities that were proportionally enriched, among others, in OTUs belonging to families Enterobacteriaceae, Chitinophagaceae, Comamonadaceae, Caulobacteraceae, Cytophagaceae, Streptomycetaceae, b) distinct N-starvation root fungal communities that were proportionally enriched in OTUs belonging to taxa Lulworthia, Sordariomycetes, Apodus, Conocybe, Ascomycota, Crocicreas, c) a distinct P-starvation rhizosphere bacterial community that was proportionally enriched in an OTU belonging to genus Agrobacterium, and d) a distinct P-starvation root fungal community that was proportionally enriched in OTUs belonging to genera Parastagonospora and Phaeosphaeriopsis. Our study might have exposed wheat-microbe connections that can form the basis of novel complementary yield-boosting tools.

microbiology↗