Biology subjects

Dallas, J. W.

Publications and source records attributed to Dallas, J. W..

4 recordsLinked to original sources

bioRxiv2024

Absolute abundance unveils Basidiobolus as a cross-domain bridge indirectly bolstering gut microbiome homeostasis

The host microbiome is integral to metabolism, immune function, and resilience against pathogens. However, reliance on relative abundance (RA) to estimate host-associated microbiomes introduces compositional biases, while limited tools for absolute abundance (AA) quantification hinder broader applications. To address these challenges, we developed DspikeIn (https://github.com/mghotbi/DspikeIn), an R package paired with a versatile wet-lab methodology for AA quantification. Using RA and AA to compare core microbiome distributions across herpetofauna orders and their natural histories revealed starkly distinct results, driven by aggregate effects, including inherited compositional biases in RA and additional multifactorial influences. Focusing on two closely related Desmognathus species demonstrated that AA quantification enhanced resolution in differential abundance analyses and minimized false discovery rates (FDR) when identifying enriched taxa in their gut microbiomes. Keystone taxa identified through network associations also differed between RA and AA data. For example, Lactococcus and Cetobacterium were core members in Anura and Caudata, while Basidiobolus and Mortierella were core to Chelonia and Squamata, facilitating host adaptation to diverse environments, insights undetectable with RA data. AA-based network analysis further revealed that removing the Basidiobolus subnetwork increased negative interactions, highlighting its role in promoting gut homeostasis through cross-domain connectivity. Despite low redundancy, the Basidiobolus node exhibited high betweenness, efficiency, and degree, serving as a critical bridge linking disconnected nodes or modules and indirectly supporting microbiome stability, consistent with Burts structural hole theory. DspikeIn represents a transformative tool for microbiome research, enabling the transition from RA to AA quantification and delivering more accurate, consistent, and comparable results across studies. Graphical abstract DspikeIn cheatsheet O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=156 SRC="FIGDIR/small/630554v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@150900forg.highwire.dtl.DTLVardef@21cd90org.highwire.dtl.DTLVardef@13ead1borg.highwire.dtl.DTLVardef@1d6fa84_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Isolation of Plastic Digesting Microbes from the Gastrointestinal Tract of Tenebrio Molitor

Plastics, particularly polystyrene (PS) and polyethylene (PE), are pervasive in ecosystems and degrade slowly, leading to the formation of microplastics and nanoplastics, which pose environmental and health risks. The gut microbiota of Tenebrio molitor larvae (mealworms) can degrade plastics, making them a potential model for studying microbial plastic digestion. This study investigated how rearing T. molitor on PS-or PE-supplemented diets over three generations affected gut microbiota composition and plastic degradation. Larvae were reared on wheat bran (control), PS, or PE diets, and microbial communities from their guts were cultured to assess plastic metabolism. Results showed that the PE-supplemented diet enhanced bacterial plastic degradation, while the PS-supplemented diet did not lead to similar improvements. Microbes from PE-fed larvae exhibited increased plastic metabolic activity compared to controls, and several bacterial strains with plastic-degrading capabilities were identified. However, microbial digestion of PS was less efficient, and potential dysbiosis due to the presence of Dickeya phage in PS-fed larvae may have influenced the results. Further research is needed to clarify the mechanisms driving microbial plastic digestion and to determine the applicability of these findings to environmental plastic remediation, particularly for micro- and nanoplastics.

microbiology↗

bioRxiv2023

Heat Tolerance is Affected by the Gut Microbiota in a Vertebrate Ectotherm

The gut microbiota is known to influence and have regulatory effects in diverse physiological functions of host animals, but only recently has the relationship between host thermal biology and gut microbiota been explored. Here, we examined how early-life manipulations of the gut microbiota in larval amphibians influenced their critical thermal maximum (CTmax) at different acclimation temperatures. We removed the resident microbiome on the outside of wild-caught wood frog (Lithobates sylvaticus) egg masses via an antibiotic wash, and then either maintained eggs without a microbiota or inoculated eggs with pond water or the intestinal microbiota of another species, green frogs (L. clamitans), that have a wider thermal tolerance. We predicted that this cross-species transplant would improve the CTmax of the recipient wood frog larvae relative to the other treatments. In line with this prediction, green frog-recipient larvae had the highest CTmax while those with no inoculum had the lowest CTmax. Both the microbiome treatment and acclimation temperature significantly influenced the larval gut microbiota communities and alpha diversity indices. Green frog inoculated larvae were enriched in Rikenellaceae relative to the other treatments, which produce short-chain fatty acids and could contribute to greater energy availability and enhanced heat tolerance. Larvae that received no inoculation had higher relative abundances of potentially pathogenic Aeromonas spp., which negatively affects host health and performance. Our results are the first to show that cross-species gut microbiota transplants alter heat tolerance in a predictive manner. This finding has repercussions for the conservation of species that are threatened by climate change and demonstrates a need to further explore the mechanisms by which the gut microbiota modulates host thermal tolerance.

zoology↗

bioRxiv2022

Heat Hardening of a Larval Amphibian is Dependent on Acclimation Period and Temperature

The thermal tolerance-plasticity trade-off hypothesis states that acclimation to warmer environments increases basal thermal tolerance in ectotherms but reduces plasticity in coping with acute thermal stress characterized as heat hardening. We examined the potential trade-off between basal heat tolerance and hardening plasticity, measured as critical thermal maximum (CTmax) of a larval amphibian, Lithobates sylvaticus, in response to differing acclimation temperatures (15{degrees} and 25{degrees}C) and periods (3 or 7 days). A hardening treatment applied 2 hours before CTmax assays induced pronounced plastic hardening responses in the cool, 15{degrees}C treatment after 7 days of acclimation, compared to controls. Warm acclimated larvae at 25{degrees}C, by contrast, exhibited minor hardening responses, but significantly increased basal thermal tolerance. These results support the trade-off hypothesis and fill a knowledge gap in larval amphibian thermal plasticity. Elevated environmental temperatures induce acclimation in heat tolerance yet constrains ectotherm capacity to cope with further acute thermal stress. Summary StatementA larval amphibian follows the trade-off hypothesis such that the group with the highest basal heat tolerance displays the lowest hardening response and vice-versa.

physiology↗