Biology subjects

Virgilio, A.

Publications and source records attributed to Virgilio, A..

3 recordsLinked to original sources

bioRxiv2025

Apurinic/apyrimidinic endodeoxyribonuclease 1 contributes to the repair of damaged intercalated-motif of telomeric sequences

Apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) is a key enzyme in the Base Excision Repair pathway, responsible for processing abasic (AP-) sites. Recent studies revealed that APE1 participates in repairing DNA secondary structures as G-quadruplexes (G4). Telomeres, stabilized by shelterin proteins, are rich in G4, where APE1 binds and repairs AP-sites to maintain their integrity. The complementary cytosine-rich strand forms another structure, the i-motif (iM), essential for telomere maintenance, though its repair mechanism remains unclear. Herein we investigate APE1 binding and processing capabilities toward native and damaged telomeric iM, bearing AP-sites in different positions. Using biochemical and biophysical assays, we found that APE1 binds the telomeric iM-sequence and that its cleavage efficiency depends on AP-site position within iM. Proximity Ligation Assay analysis, in HeLa and U2OS cells, highlighted a novel interaction between APE1 and PCBP1, a well-known iM-folding modulator. PCBP1 binds iM with higher affinity than APE1 and inhibits its cleavage activity on damaged iM. Immunofluorescence and Telomere Restriction Fragment analyses showed that depletion of APE1 or PCBP1 impairs their interaction with the shelterin components, affecting telomere length. These results connect APE1 canonical DNA repair activity with the maintenance of non-canonical DNA secondary structures in telomeres, through its interaction with PCBP1. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/694817v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1962c63org.highwire.dtl.DTLVardef@3c3f60org.highwire.dtl.DTLVardef@164d78borg.highwire.dtl.DTLVardef@1831aae_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

Resolving the Foliar Calcium Mobility Paradox: Enhancing Foliar Calcium Transport in Tomato Using Osmotic Regulators

Highlight- In vivo XRF measurements in the petiole confirmed Sr transport to distal tomato tissues. - XRF imaging revealed the distribution of Sr in tomato fruits following foliar application. - Foliar formulations supplemented with osmotic regulators improved Sr absorption and translocation. - Sucrose enhanced both short- and long-distance transport of Sr to tomato fruits. - Sucrose significantly enhanced Sr{superscript 2} accumulation in seeds and the apical mesocarp, the regions most affected by Ca deficiency symptoms The study demonstrates a novel approach for enhancing phloem transport to fruit of foliar-applied Ca Calcium (Ca) deficiency can impair fruit development even under optimal soil Ca levels due to its transpiration-dependent transport. Reduced fruit transpiration may limit Ca delivery to fruits, leading to lower Ca content in the fruit and diminished quality. Foliar application of Ca offers a potential strategy to mitigate these effects; however, its low mobility in the phloem often limits treatment efficacy. To address this, we employed X-ray fluorescence spectroscopy (XRF) to investigate the penetration and transport of foliar-applied Ca, using strontium (Sr) as a physiological tracer. Additionally, we evaluated the influence of osmotic regulators, sucrose, mannitol, glycerol, and potassium, on Ca transport. Results showed that Sr was effectively translocated to distal tissues. While potassium and mannitol had no significant impact on transport kinetics, sucrose and glycerol enhanced Sr movement. XRF imaging of leaf tissue revealed that Sr was primarily transported through the apoplast toward the leaf margin. Moreover, foliar application of Sr combined with sucrose significantly increased Sr accumulation in seeds and in the apical portion of tomato fruits. These findings suggest that, contrary to the common assumption of limited foliar Ca mobility, sucrose, can acts as an effective osmotic regulator, enhancing both short-range movement within leaf tissue and long-distance translocation to fruit.

plant biology↗

bioRxiv2025

Storage protein biosynthesis is affected by ionome composition in soybean (Glycine max (L.) Merrill) seeds

Soybean seeds are a significant source of protein for human and animal nutrition, primarily due to seed storage proteins (SSPs) from the albumin and globulin families, which are predominantly located in protein storage vacuoles within cotyledon cells. This study characterised the dynamics of protein and mineral nutrient accumulation in four soybean genotypes with contrasting protein content--two transgenic (tg1 and tg2) and two conventional (ct1 and ct2)--from the beginning of seed filling (R5.5) through to maturity (R8) under field conditions. Profiles of globulin SSPs (glycinin and {beta}-conglycinin), as well as the protein and elemental distribution in mature seed cotyledons were examined. Results revealed that genotypes with higher protein content showed increased S and Zn concentrations and a higher glycinin:{beta}-conglycinin ratio. Subcellular analyses further indicated co-localisation of proteins and Zn within cotyledon cells. Our findings reveal a complex association between S and Zn accumulation and SSPs biosynthesis, indicating that their availability can limit the SSP content. HIGHLIGHTSoybean seed genotypes containing higher sulphur (S) and zinc (Zn) content in the cotyledonary cells exhibit a distinct storage proteins profile by increasing the abundance of sulphur-amino acids rich globulins.

plant biology↗