Biology subjects

Vicente, J. R.

Publications and source records attributed to Vicente, J. R..

3 recordsLinked to original sources

bioRxiv2022

Multiscale mapping of in vivo 3D epidermal melanin distribution of human skin using a fast large-area multiphoton exoscope (FLAME)

Melanin plays a significant role in the regulation of epidermal homeostasis and photoprotection of human skin. The assessment of its epidermal distribution and overall content is of great interest due to its involvement in a wide range of physiological and pathological skin processes. Among several spectroscopic and optical imaging methods that have been reported for non-invasive quantification of melanin in human skin, the approach based on the detection of two-photon excited fluorescence lifetime distinguishes itself by enabling selective detection of melanin with sub-cellular resolution, thus facilitating its quantification while also resolving its depth-profile. A key limitation of prior studies on the melanin assessment based on this approach is their inability to account for the skin heterogeneity due to the reduced field of view of the images, which results in high dispersion of the measurement values. Pigmentation in both normal and pathological human skin is highly heterogeneous and its macroscopic quantification is critical for reliable measurements of the epidermal melanin distribution and for capturing melanin-related sensitive dynamic changes as a response to treatment. In this work, we employ a fast large-area multiphoton exoscope (FLAME), recently developed by our group for clinical skin imaging, that has the ability to evaluate the 3D distribution of epidermal melanin content in vivo macroscopically (millimeter scale) with microscopic resolution (sub-micron) and rapid acquisition rates (minutes). We demonstrate significant enhancement in the reliability of the melanin density and distribution measurements across Fitzpatrick skin types I to V by capturing the intra-subject pigmentation heterogeneity enabled by the large volumetric sampling. We also demonstrate the potential of this approach to provide consistent measurement results when imaging the same skin area at different times. These advances are critical for clinical and research applications related to monitoring pigment modulation as a response to therapies against pigmentary skin disorders, skin aging, as well as skin cancers.

bioengineering↗

bioRxiv2021

Policy-relevant indicators for invasive alien species assessment and reporting

Invasive alien species are repeatedly shown to be amongst the top threats to biodiversity globally. Robust indicators for measuring the status and trends of biological invasions are lacking, but essential for monitoring biological invasions and the effectiveness of interventions. Here, we formulate and demonstrate three such indicators that capture the key dimensions of species invasions, each a significant and necessary advance to inform invasive alien species policy targets: 1) Rate of Invasive Alien Species Spread, which provides modelled rates of ongoing introductions of species based on invasion discovery and reporting. 2) Impact Risk, that estimates invasive alien species impacts on the environment in space and time and provides a basis for nationally targeted prioritization of where best to invest in management efforts. 3) Status Information on invasive alien species, that tracks improvement in the essential dimensions of information needed to guide relevant policy and data collection and in support of assessing invasive alien species spread and impact. We show how proximal, model-informed status and trend indicators on invasive alien species can provide more effective global (and national) reporting on biological invasions, and how countries can contribute to supporting these indicators.

ecology↗

bioRxiv2019

A CyclinB2-Cas9 fusion promotes the homology-directed repair of double-strand breaks

The discovery of clustered regularly interspaced palindromic repeats (CRISPR), a defense system against viruses found in bacteria, launched a new era in gene targeting. The key feature of this technique is the guiding of the endonuclease Cas9 by single guide RNAs (sgRNA) to specific sequences, where a DNA lesion is introduced to trigger DNA repair. The CRISPR/Cas9 system may be extremely relevant for gene therapy, but the technique needs improvement to become a safe and fully effective tool. The Cas9-induced double-strand break (DSB) is repaired by one of two pathways, the error-prone Non-homologous end joining (NHEJ) or the high-fidelity Homology Direct Repair (HDR). Shifting the repair of the DSB to HDR is challenging, given the efficiency of NHEJ. Here we describe an engineered protein approach to increase knock-in efficiency by promoting the relative increase in Cas9 activity in G2, the phase of the cell cycle where HDR is more active. Cas9 was fused to the degradation domain of proteins known to be degraded in G1. The activity of two chimeric proteins, Geminin-Cas9 and CyclinB2-Cas9, is demonstrated, as well as their cell-cycle-dependent degradation. The chimeras shifted the repair of the DSBs to the HDR repair pathway compared to the commonly used Cas9. The application of cell cycle specific degradation tags could pave the way for more efficient and secure gene editing applications of the CRISPR/Cas9 system.

molecular biology↗