Biology subjects

Marquina, D.

Publications and source records attributed to Marquina, D..

9 recordsLinked to original sources

bioRxiv2026

Colonization resistance against Clostridioides difficile is a graded, microbiota-intrinsic property of healthy human gut communities

Fecal microbiota transplantation cures approximately 90% of recurrent Clostridioides difficile infection, yet it remains unknown whether all healthy donor microbiota confer equivalent protection. We colonized germ-free C57BL/6 mice with stool microbiota from 30 healthy human donors and challenged them with C. difficile in the absence of antibiotic pretreatment. Donor microbiota conferred a spectrum of colonization resistance phenotypes: Resistant (no detectable colonization or toxin), Carrier (asymptomatic colonization with detectable toxin), Symptomatic (non-lethal diarrheal illness), and Susceptible (lethal infection). Of these, 8 conferred Resistant phenotypes, 12 Carrier, 6 mixed Resistant-Carrier outcomes, and 4 Symptomatic or Susceptible phenotypes. While 16S rRNA gene sequencing of donor stool did not distinguish phenotypes across any diversity or compositional metric tested, humanized mouse microbiomes exhibited clear phenotype-dependent differences after engraftment. Richness (observed amplicon sequence variants, Chao1) and diversity (Shannon and Faith's phylogenetic diversity) declined progressively from Resistant to Susceptible phenotypes, although substantial overlap was observed between groups. Differential abundance analysis identified taxa depleted across non-resistant phenotypes, including Lachnospiraceae taxa such as Hungatella and Sellimonas, and Bacteroides intestinalis. Shotgun metagenomics confirmed these associations and revealed coordinated depletion of biosynthetic and carbohydrate metabolism pathways in non-resistant phenotypes, consistent with broad loss of community metabolic capacity rather than loss of a single dominant function. These findings demonstrate colonization resistance is a graded, microbiota-associated ecological property, evident after host engraftment rather than being a binary trait encoded in donor stool. This has implications for donor screening in fecal microbiota transplantation and the rational design of microbiome-based therapeutics.

microbiology↗

bioRxiv2025

Factors Influencing Emerald Ash Borer Ecological Interactions

Emerald ash borer beetles (Agrilus planipennis) in North America are a destructive invasive species that increase tree mortality continent-wide, resulting in major ecological and economic impacts. Trees that are infested experience mortality rates which can exceed 99%, disrupting ecological communities and threatening the $218 billion forestry industry in North America. Given the ecological and economic impact of these pests, we seek to identify biological interactions and gain a better understanding of what ecological factors might influence these relationships. We use DNA metabarcoding from multiple markers to analyze the fungal, parasitic, plant, and microbial interactions of these beetles, and assess the relative importance of life stage (e.g., larvae, pupae, and adults), collection location, habitat, and date on the detection of ecological interactions. We detected 30 different taxonomic orders including 29 order-level interactions in larva1-stage individuals (3 animal, 17 bacteria, and 9 fungi), 64 in larva2-stage individuals (8 animal, 24 bacteria, and 32 fungi), 10 in larva3-stage individuals (2 animal, 3 bacteria, and 5 fungi), 74 in the pupae (5 animal, 31 bacteria, and 38 fungi), and 82 in the adult beetles (4 animal, 48 bacteria, 29 fungi, and 1 parasitic alveolate). These detections include several likely agents of biocontrol including the known commercially available Beauveria fungus, and several potential parasites including Wolbachia and ichneumonid wasps. A random forest model suggests the detection of interactions is best predicted by collection date and life stage, with interactions more likely to be detected in pupal samples which may be the ideal target for future analysis, where cost and time constraints prevent the more thorough analysis of all life stages.

ecology↗

bioRxiv2024

Subpopulation-specific gene expression in Lachancea thermotolerans uncovers distinct metabolic adaptations to wine fermentation

Gene expression is the first step in translating genetic information into quantifiable traits. This study analysed gene expression in 23 strains across six subpopulations of Lachancea thermotolerans, shaped by anthropization, under winemaking conditions to understand the impact of adaptation on transcriptomic profiles and fermentative performance, particularly regarding lactic acid production. By sequencing mRNA during exponential growth and fermentation in synthetic grape must, we identified unique expression patterns linked to the strains originated from wine-related environments. Global expression analysis revealed that anthropized subpopulations, particularly Europe/Domestic-2 and Europe-Mix, exhibited distinct gene expression profiles related to fermentation processes such as glycolysis and pyruvate metabolism. These processes were differentially expressed, along with other important biological processes during fermentation, such as nitrogen and fatty acid metabolism. This study highlights that anthropization has driven metabolic specialization in L. thermotolerans, enhancing traits like lactic acid production, which is a trait of interest in modern winemaking. Correlation analysis further linked lactic acid dehydrogenase genes with key metabolic pathways, indicating adaptive gene expression regulation. Additionally, differences in other metabolites of oenological interest as glycerol or aroma compounds production are highlighted. Here, we provide insights into the evolutionary processes shaping the transcriptomic diversity of L. thermotolerans, emphasizing the impact of winemaking environments on driving specific metabolic adaptations, including lactic acid production. Understanding the gene expression differences linked to lactic acid production could allow a more rational address of biological acidification while optimizing yeast-specific nutritional requirements during fermentation. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/611386v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@9a7879org.highwire.dtl.DTLVardef@15b8282org.highwire.dtl.DTLVardef@d52aa1org.highwire.dtl.DTLVardef@e1c2eb_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Whole-genome sequencing and phenotyping reveal specific adaptations of Lachancea thermotolerans to the winemaking environment

Adaptation to the environment plays an essential role in yeast evolution as a consequence of selective pressures. Lachancea thermotolerans, a yeast related to the fermentative process and one of the current trends in wine technology research, has undergone an anthropization process that has led to a strong differentiation both from a genomic and phenomic perspective. Using whole-genome sequencing, we have investigated the genomic diversity of 145 L. thermotolerans strains, identifying six well-defined groups primarily delineated by their ecological origin and exhibiting high levels of genetic diversity. Anthropized strains showed lower genetic diversity due to the purifying selection imposed by the winemaking environment. Strong evidence of anthropization and adaptation to the wine environment through modification of gene content was also found. Differences in genes involved in the assimilation of alternative carbon and nitrogen sources, such as the MAL1 and DAL5 genes, which confer greater fitness in the winemaking environment, were observed. Additionally, we found that phenotypic traits considered domestication hallmarks are present in anthropized strains. Among these, increased fitness in the presence of ethanol and sulphites, assimilation of non-fermentable carbon sources such as glycerol, and lower levels of residual fructose under fermentative conditions highlight. We hypothesize that lactic acid production by wine-related strains is an anthropization signature consequence of the adaption of early Crabtree-positive yeasts to the fermentative environment. Overall, the results of this work provide valuable insight into the anthropization process in L. thermotolerans and demonstrate how fermentation environments give rise to similar adaptations in different yeast species.

microbiology↗

bioRxiv2022

Multilocus typing of Lachancea thermotolerans for wine fermentation monitoring

Climate change is causing a lack of acidity during winemaking and oenologists use several solutions to cope with such a problem. Lachancea thermotolerans, which has the potential to tolerate the harsh physicochemical conditions of wine, has emerged as a promising alternative for pH management during winemaking and, currently, it is the most valuable yeast used for acidity control in wine. In this work an amenable method for L. thermotolerans genotyping based on a multiplexed microsatellite amplification in 6 different loci was developed. This specific and sensitive method was used to distinguish between 103 collection strains obtained from different geographical and isolation sources, and then challenged against a 429 L. thermotolerans isolates from several wineries and harvests. The procedure was also tested for fermentation monitoring and strain implantation. The procedure was conceived to simplify the methodology available for L. thermotolerans genotyping, making it easy for applying in wine-related laboratories. This method can be applied to distinguish between L. thermotolerans strains in selection programs and to follow implantation of inoculated strains during winemaking with optimal results.

microbiology↗

bioRxiv2020

A rapid urban biodiversity blitz using aquatic environmental DNA

Background As global biodiversity declines, there’s an increasing need to create an educated and engaged society. Having people from all ages participate in measuring biodiversity where they live helps to create awareness. Recently, the use of environmental DNA (eDNA) for biodiversity surveys has gained momentum. Here, we test whether sampling eDNA and metabarcoding can be used for rapid urban biodiversity surveys for educational purposes.Materials & Methods We sampled 2×1 L of water from each of 15 locations in the city of Trondheim, Norway, including a variety of freshwater, marine and brackish habitats. DNA was extracted, amplified in triplicate for the COI gene and sequenced. The obtained data were analysed on the novel mBRAVE platform, an online open access software and computing resource.Results The water samples were collected in two days by two people and the lab analysis was completed in five days by one person. Overall, we detected the presence of 501 taxa identified as belonging to 435 species, representing 90 orders and 18 phyla. On average, only 5.4% of the taxa were shared among six replicates per site. Based on the observed diversity, three distinct clusters were detected and related to geographic distribution of sites. There were some taxa shared between the habitats, with a substantial presence of terrestrial biota.Discussion Our results match expected patterns of biodiversity in the landscape and show that with minimal sampling effort, hundreds of species can be detected. Thus, using eDNA analysis of water is promising for rapid biodiversity surveys, and it is likely that more detailed results could be obtained by optimising field and lab methods for particular groups of interest. We recommend that rapid eDNA surveys, with openly available services and softwares, can be used to raise awareness in the importance of biodiversity.Competing Interest StatementThe authors have declared no competing interest.View Full Text

scientific communication and education↗

bioRxiv2020

The effect of ethanol concentration on the preservation of insects for biodiversity studies

1. Traditionally, insects collected for scientific purposes have been dried and pinned, or preserved in 70 % ethanol. Both methods preserve taxonomically informative exoskeletal structures well but are suboptimal for preserving DNA. Highly concentrated ethanol (95 - 100 %), preferred as a DNA preservative, has generally been assumed to make specimens brittle and prone to breaking. However, systematic studies on the correlation between ethanol concentration and specimen preservation are lacking. 2. We tested how preservative ethanol concentration in combination with different sample handling regimes affect the integrity of seven insect species representing four orders, and differing substantially in the level of sclerotization. After preservation and treatments (various levels of disturbance), we counted the number of appendages (legs, wings, antennae, heads) that specimens had lost. Additionally, we assessed the preservation of DNA after long-term storage by comparing the ratio of PCR amplicon copy numbers to an added artificial standard. 3. We found that high ethanol concentrations indeed induce brittleness in insects. However, the magnitude and nature of the effect varied strikingly among species. In general, ethanol concentrations at or above 90 % made the insects more brittle, but for species with robust, thicker exoskeletons, this did not translate to an increased loss of appendages. Neither freezing nor drying the insects after immersion in ethanol had a negative effect on the retention of appendages. We also found that DNA preserves less well at lower ethanol concentrations when stored at room temperature for an extended period. However, the magnitude of the effect varies among species; the concentrations at which the number of COI amplicon copies relative to the standard was significantly decreased compared to 95 % ethanol ranged from 90 % to as low as 50 %. 4. While higher ethanol concentrations positively affect long-term DNA preservation, there is a clear trade-off between preserving insects for morphological examination and genetic analysis. The optimal ethanol concentration for the latter is detrimental for the former, and vice versa. These trade-offs need to be considered in large insect biodiversity surveys and other projects aiming to combine molecular work with traditional morphology-based characterization of collected specimens.

ecology↗

bioRxiv2019

Establishing insect community composition using metabarcoding of soil samples, and preservative ethanol and homogenate from Malaise trap catches: surprising inconsistencies between methods.

DNA metabarcoding allows the analysis of insect communities faster and more efficiently than ever before. However, metabarcoding can be conducted through several alternative approaches, and the consistency of results across methods has rarely been studied. We compare the results obtained by DNA metabarcoding of the same communities using two different markers - COI and 16S - and three different sampling methods - homogenized Malaise trap samples (homogenate), preservative ethanol from the same samples, and soil samples. Our results indicate that COI and 16S offer partly complementary information on Malaise trap samples, with each marker detecting a significant number of species not detected by the other. Different sampling methods offer highly divergent estimates of community composition. The community recovered from preservative ethanol of Malaise trap samples is quite distinct from that recovered from homogenate. Small and weakly sclerotized insects tend to be overrepresented in ethanol, with some exceptions that could be related to taxon-specific traits. For soil samples, highly degenerate COI primers pick up large amounts of non-target DNA and only 16S provides adequate analyses of insect diversity. However, even with 16S, very little overlap in MOTU content was found between the trap and the soil samples. Our results demonstrate that no metabarcoding approach is all-comprehensive in itself. For instance, DNA extraction from preservative ethanol is not a valid replacement for destructive bulk extraction but a complement. In future metabarcoding studies, both should ideally be used together to achieve comprehensive representation of the target community.

ecology↗

bioRxiv2018

New mitochondrial primers for metabarcoding of insects, designed and evaluated using in silico methods

Insect metabarcoding has been mainly based on PCR amplification of short fragments within the barcoding region of the gene COI. However, because of the variability of this gene, it has been difficult to design good universal PCR primers. Most primers used today are associated with gaps in the taxonomic coverage or amplification biases that make the results less reliable and impede the detection of species that are present in the sample. We identify new primers for insect metabarcoding using computational approaches (ECOPRIMERS and DEGEPRIME) applied to the most comprehensive reference databases of mitochondrial genomes of Hexapoda assembled to date. New primers are evaluated in silico against previously published primers in terms of taxonomic coverage and resolution of the corresponding amplicons. For the latter criterion, we propose a new index, exclusive taxonomic resolution, which is a more biologically meaningful measure than the standard index used today. Our results show that the best markers are found in the ribosomal RNA genes (12S and 16S); they resolve about 90% of the genetically distinct species in the reference database. Some markers in protein-coding genes provide similar performance but only at much higher levels of primer degeneracy. Combining two of the best individual markers improves the effective taxonomic resolution with up to 10%. The resolution is strongly dependent on insect taxon: COI primers detect 40% of Hymenoptera, while 12S primers detect 12% of Collembola. Our results indicate that amplicon-based metabarcoding of insect samples can be improved by choosing other primers than those commonly used today.

bioinformatics↗