Biology subjects

Camacho, A.

Publications and source records attributed to Camacho, A..

10 recordsLinked to original sources

bioRxiv2025

Which are the most heat-tolerant animals? Insights from a Mediterranean lepismatid under thermal stress in the context of climate change

Measuring behavioural and physiological thermal limits is crucial to understanding how they interact with the environment under a climate change scenario. We experimentally assessed the effects of acclimation on sequentially measured voluntary (VTmax), critical (CTmax), and upper thermal limit (UTL) limits in the Mediterranean silverfish Sceletolepisma guadianicum. Individuals were acclimated for six days at either 25{degrees}C (n=32) or 35{degrees}C (n=29) and heated at [~]0.5{degrees}C min-1, and VTmax, CTmax, and lethal limits were recorded. S. guadianicum exhibited some of the highest thermal limits reported to date among terrestrial arthropods. VTmax showed limited (1.04 {degrees}C) but statistically detectable plasticity, increasing with high acclimation temperature and heating rate, whereas CTmax rate and lethal limits remained unchanged. We provide hypotheses explaining the co-ocurrence of exceptional heat tolerance levels together with their reduced plasticity in this and other extremely heat-tolerant species. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=124 SRC="FIGDIR/small/690525v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1f01660org.highwire.dtl.DTLVardef@14cfcb2org.highwire.dtl.DTLVardef@1621c39org.highwire.dtl.DTLVardef@2aec20_HPS_FORMAT_FIGEXP M_FIG C_FIG

zoology↗

bioRxiv2025

Affinity-based selection of anti-Feline Leukaemia Virus p27 monoclonal antibodies for efficient lateral flow assay development

Classic diagnostic modalities--including RT-PCR and proviral DNA PCR--present certain drawbacks, highlighting the need of alternative diagnostic techniques, such as lateral flow immunoassays (LFIA), valued for their rapidity and sensitivity. Said desirable features depend on the efficiency of the ternary interaction wherein the antigen bridges immobilized capture and labelled detection antibodies. However, the cost and the throughput of current screening methods, for finding monoclonal antibody (mAbs) pairs efficient at establishing this type of ternary interactions, remains as a universal bottleneck for LFIA development. Traditional sandwich enzyme-linked immunosorbent assays (ELISA), although extensively employed in mAb screening procedures, is burdened by its high consumption of labelled mAbs and the potential alteration of antigen conformation upon plate immobilization, often yielding suboptimal surrogates for native interactions within the final LFIA setup. In this study, we developed an orthogonal approach integrating ELISA and Spectral Shift (SST) that jointly enable the minimisation of reagent consumption (mAbs, antigens, labelling reagents) to comprehensively profile a panel of mAbs against a bona fide antigen of Feline Leukaemia Virus FeLV p27. This facilitated the quick selection of two low nanomolar mAbs with distinct epitope recognition, for which we validated a ternary complex formation in a LFIA prototype. This strategy enables advanced, resource-efficient LFIA development for FeLV and other critical antigens, such as H5 Avian Influenza Virus or African Swine Fever Virus, in addition to major human pathogens including Helicobacter pylori or Mpox Virus, facilitating sensitive diagnostics and streamlined quality control.

biophysics↗

bioRxiv2025

Development of Proton Density Fat Fraction Micro-MRI for Non-Invasive Quantitative Assessment of Bone Marrow Changes with Age and Radiation in Mouse Models

Background/ObjectivesBone marrow (BM) adipocytes are critical in progressing solid tumor metastases and hematological malignancies across pediatric to aging populations. Single-point biopsies remain the gold standard for monitoring BM diseases, including hematologic malignancies, but are limited in capturing the full complexity of loco-regional and global BM microenvironments. Non-invasive imaging techniques like Magnetic Resonance Imaging (MRI), could offer valuable alternatives for real-time evaluation of BM diseases in both preclinical translational and clinical studies. MethodsWe developed a preclinical proton density fat fraction (PDFF) MRI technique for quantitative BM composition assessment, focusing on fat fraction (FF) within mouse femurs. We validated this method using aging mice and young mice subjected to 10 Gy X-ray irradiation, compared with young unirradiated mice as controls. Water-fat phantoms (0% to 100% fat content) were used to optimize the imaging sequence, and immunohistochemical (IHC) staining with H&E validates equivalent adipose content in the femur BM regions. ResultsSignificant differences in FF were observed across age groups (p = 0.001 for histology and p = 0.0002 for PDFF) and between irradiated and control mice (p = 0.005 for histology and p = 0.002 for PDFF). A strong correlation (R2 [~] 0.84) between FF values from PDFF and histology validates the accuracy of the technique. ConclusionsThese findings demonstrate the potential of PDFF MRI as a non-invasive real-time imaging biomarker for quantifying BM fat fraction in preclinical mice model studies, particularly in evaluating the effects of aging, disease progression, and irradiation therapy in pediatric and translational oncology research.

biophysics↗

bioRxiv2024

Correlating Disordered Activation Domain Ensembles with Gene Expression Levels

Transcription factor proteins bind to specific DNA promoter sequences and initiate gene transcription. In eukaryotes, most transcription factors contain intrinsically disordered activation domains (ADs) that regulate their transcriptional activity. Like other disordered protein regions, ADs do not have a fixed three-dimensional structure and instead exist in an ensemble of conformations. Disordered ensembles contain sequence-encoded structural preferences which are often linked to their function. We hypothesize this link exists between the structural preferences of disordered AD ensembles and their ability to induce gene expression. To test this, we used FRET microscopy to measure the ensemble dimensions of two activation domains, HIF-1 and CITED2, in live cells, and correlate this structural information with transcriptional activity. We find that point mutations that expanded the HIF-1 ensemble increased transcriptional activity, while those that compacted it reduced activity. Conversely, CITED2 showed no correlation between ensemble dimensions and activity. Our results reveal a sequence-dependent relationship between AD ensemble dimensions and their transcriptional activity. WHY IT MATTERSTranscription factors have activation domains (ADs) that bind to coactivator complexes to initiate gene transcription. Despite their key role, a comprehensive understanding of what drives their transcriptional activity has remained elusive. Efforts to understand AD activity have largely focused on their amino acid composition. In recent years, it is increasingly realized that the structural ensembles of disordered proteins contain biases that dictate their structural properties. For ADs, ensemble structures remain poorly explored, especially in relation to their activity. Here we report a mutational study of two ADs, HIF-1 and CITED2, that examines how ensemble dimensions correlate with activity. Our findings suggest that ensemble dimensions may drive activity in some ADs, and that AD ensemble dimensions can be modulated not only through mutations, but also through changes in the cellular environment.

biophysics↗

bioRxiv2021

Does heat tolerance actually predict geographic thermal limits of animal species?

To understand species' climatic vulnerability, our measures of species thermal tolerance should predict their geographic thermal limits. Yet, this assumption is ungranted. We tested if animals' heat tolerance restrict the warmest temperatures they can live at (Tmax), distinguishing among species differently challenged by their thermal environment. For that, we compiled 2350 measurements of species heat tolerance indexes and corresponding Tmax, measured at different microhabitats. We show that reptiles, a flagship for climatic vulnerability studies, are particularly unbounded by their heat tolerance. Contrarily, tolerance restricted marine fish geography in a non-linear fashion which contrasts with terrestrial taxa. Behavioral tolerance indexes, widely used to predict vulnerability, predicted Tmax inconsistently across Tmax indexes, or were inversely related to it. Animals heat tolerance restricts geographic limits more strongly for more thermally challenged species. In turn, factors uncoupling heat tolerance and Tmax (plasticity, thermoregulation, adaptation) should be more important for less thermally challenged species. Significance StatementTo identify climatic vulnerability, heat tolerance indices need to predict species' thermal limits to geographic distribution. Yet, we show that heat tolerance predicts geographic limits quite heterogeneously, depending on taxa, the type of measure of heat tolerance and how challenged are species at their hottest known location. Particularly, reptiles, a flagship of vulnerability studies, were less bounded by tolerance than taxa regarded as more capable to evade high temperatures, due to their capacity to evaporate water, find refuge, or migrate (Ex. amphibians, arthropods, birds and mammals). Measures of species behavioral heat tolerance may still need to improve. Factors thought to uncouple thermal tolerance and geographic limits should be stronger for less thermally challenged species.

ecology↗

bioRxiv2021

Metacommunities from bacteria to birds: stronger environmental effects in Mediterranean than in tropical ponds.

The metacommunity concept provides a theoretical framework that aims at explaining organism distributions by a combination of environmental filtering, dispersal and drift. With the development of statistical tools to quantify and partially isolate the role of each of these processes, empirical metacommunity studies have multiplied worldwide. However, few works attempt a multi-taxon approach and even fewer compare two distant biogeographical regions using the same methodology. Under this framework, we tested the expectation that temperate (mediterranean-climate) pond metacommunities would be more influenced by environmental and spatial processes than tropical ones, because of stronger environmental gradients and greater isolation of waterbodies. We surveyed 30 tropical and 32 mediterranean temporary ponds from Costa Rica and Spain, respectively, and obtained data on 49 environmental variables (including limnological, hydrogeomorphological, biotic, climatic, and landscape variables). We characterized the biological communities of Bacteria and Archaea (from both the water column and the sediments), phytoplankton, zooplankton, benthic invertebrates, amphibians and birds, and estimated the relative role of space and environment on metacommunity organization for each group and region, by means of variation partitioning using Generalized Additive Models (GAMs). Environmental selection was important in both tropical and mediterranean ponds, but markedly stronger in the latter, probably due to their larger limnological heterogeneity. Spatialized environment and pure spatial effects were greater in the tropics, related to higher climatic heterogeneity and dispersal processes (e.g. restriction, surplus) acting at different scales. The variability between taxonomic groups in spatial and environmental contributions was very wide. Effects on passive and active dispersers were similar within regions but different across regions, with higher environmental effects in mediterranean active dispersers. The residual (unexplained) variation was larger in tropical pond metacommunities, suggesting a higher role for stochastic processes and/or effects of biotic interactions in the tropics. Overall, these results provide support, for a wide variety of organisms related to aquatic habitats, for the classical view of stronger abiotic niche constraints in temperate areas compared to the tropics.

ecology↗

bioRxiv2020

Integrative Responses of Leaf-Cutting Ants to Temperature Rises

Thermal variation has complex effects on organisms and they deal with it by combining behavioral and physiological thermal tolerance. However, we still do not understand well how these two types of traits relate to body condition (e.g. size, hydration) and environmental variables (e.g. relative humidity), some of which are typical aspects of thermal tolerance experiments (warming rates, start temperature). We explored these interactions using a set of experiments that sequentially measure behavioral (Voluntary Thermal Maxima) and physiological thermal tolerance (Critical Thermal Maxima) for individuals of Atta sexdens rubropilosa (Forel, 1908). We found non-linear effects of body size on behavioral thermal tolerance and refuted the traditional hypothesis that body size increases ants physiological thermal tolerance. Hydration state and humidity had complex effects on behavioral and physiological tolerance. However, both tolerance measures increased with heating rates and start temperature. Our work helps understanding how an ectotherm integrates stimuli affecting its thermal tolerance to decide which temperatures to avoid. We discuss implications for the ecology of ants, their labor division, and for their susceptibility to climate warming and drought. Summary StatementHere we show how internal (body size, hydration level) and external factors (heating rate, relative humidity) affect leaf-cutting ants behavioral and physiological responses to temperature rises.

physiology↗

bioRxiv2017

Assessing the performance of real-time epidemic forecasts

Real-time forecasts based on mathematical models can inform critical decision-making during infectious disease outbreaks. Yet, epidemic forecasts are rarely evaluated during or after the event, and there is little guidance on the best metrics for assessment. Here, we propose an evaluation approach that disentangles different components of forecasting ability using metrics that separately assess the calibration, sharpness and unbiasedness of forecasts. This makes it possible to assess not just how close a forecast was to reality but also how well uncertainty has been quantified. We used this approach to analyse the performance of weekly forecasts we generated in real time in Western Area, Sierra Leone, during the 2013-16 Ebola epidemic in West Africa. We investigated a range of forecast model variants based on the model fits generated at the time with a semi-mechanistic model, and found that good probabilistic calibration was achievable at short time horizons of one or two weeks ahead but models were increasingly inaccurate at longer forecasting horizons. This suggests that forecasts may have been of good enough quality to inform decision making requiring predictions a few weeks ahead of time but not longer, reflecting the high level of uncertainty in the processes driving the trajectory of the epidemic. Comparing forecasts based on the semi-mechanistic model to simpler null models showed that the best semi-mechanistic model variant performed better than the null models with respect to probabilistic calibration, and that this would have been identified from the earliest stages of the outbreak. As forecasts become a routine part of the toolkit in public health, standards for evaluation of performance will be important for assessing quality and improving credibility of mathematical models, and for elucidating difficulties and trade-offs when aiming to make the most useful and reliable forecasts.

epidemiology↗

bioRxiv2017

Fine Stratification Of Microbial Communities Through A Metagenomic Profile Of The Photic Zone

Most marine metagenomic studies of the marine photic zone analyze only samples taken at one or two depths. However, when the water column is stratified, physicochemical parameters change dramatically over relatively short depth intervals. We sampled the photic water column every 15m depth at a single point of an off-shore Mediterranean site during a period of strong stratification (early autumn) to evaluate the effects of small depth increases on the microbiome. Using genomic assembly and metagenomic read recruitment, we found major shifts in the community structure over small variations of depth, with most microbes showing a distribution limited to layers approximately 30 meters thick (stenobathic). Only some representatives of the SAR11 clade and the Sphingomonadaceae appeared to be eurybathic, spanning a greater range of depths. These results were confirmed by studying a single gene (rhodopsin) for which we also found narrow depth distributions. Our results highlight the importance of considering vertical distribution as a major element when analyzing the presence of marine clades and species or comparing the microbiome present at different locations.

microbiology↗

bioRxiv2017

Vaccination of health care workers to control Ebola virus disease

BackgroundHealth care workers (HCW) are at risk of infection during Ebola virus disease outbreaks and therefore may be targeted for vaccination before or during outbreaks. The effect of these strategies depends on the role of HCW in transmission which is understudied.\n\nMethodsTo evaluate the effect of HCW-targeted or community vaccination strategies, we used a transmission model to explore the relative contribution of HCW and the community to transmission. We calibrated the model to data from multiple Ebola outbreaks. We quantified the impact of ahead-of-time HCW-targeted strategies, and reactive HCW and community vaccination.\n\nResultsWe found that for some outbreaks (we call \"type 1\") HCW amplified transmission both to other HCW and the community, and in these outbreaks prophylactic vaccination of HCW decreased outbreak size. Reactive vaccination strategies had little effect because type 1 outbreaks ended quickly. However, in outbreaks with longer time courses (\"type 2 outbreaks\"), reactive community vaccination decreased the number of cases, with or without prophylactic HCW-targeted vaccination. For both outbreak types, we found that ahead-of-time HCW-targeted strategies had an impact at coverage of 30%.\n\nConclusionsThe optimal vaccine strategy depends on the dynamics of the outbreak and the impact of other interventions on transmission. Although we will not know the characteristics of a new outbreak, ahead-of-time HCW-targeted vaccination can decrease the total outbreak size, even at low vaccine coverage.\n\nsummaryTargeting health care workers for Ebola virus disease vaccination can decrease the size of outbreaks, and the number of health care workers infected. The impact of these strategies decrease depends on timing, coverage, and the dynamics of the outbreak.

epidemiology↗