Research Methods in Life Sciences Commons^™

Phylogenetic Evidence From Freshwater Crayfishes That Cave Adaptation Is Not An Evolutionary Dead-End., David B Stern, Jesse Breinholt, Carlos Pedraza-Lara, Marilú López-Mejía, Christopher L Owen, Heather Bracken-Grissom, James W Fetzner, Keith A Crandall

Computational Biology Institute

Caves are perceived as isolated, extreme habitats with a uniquely specialized biota, which long ago led to the idea that caves are "evolutionary dead-ends." This implies that cave-adapted taxa may be doomed for extinction before they can diversify or transition to a more stable state. However, this hypothesis has not been explicitly tested in a phylogenetic framework with multiple independently evolved cave-dwelling groups. Here, we use the freshwater crayfish, a group with dozens of cave-dwelling species in multiple lineages, as a system to test this hypothesis. We consider historical patterns of lineage diversification and habitat transition as well as current …

Transcriptomic Differentiation Underlying Marine‐To‐Freshwater Transitions In The South American Silversides Odontesthes Argentinensis And O. Bonariensis (Atheriniformes), Lily Hughes, Gustavo Somoza, Bryan Nguyen, James Bernot, Mariano Gonzalez-Castro, Juan Martin Diaz De Astarloa, Guillermo Orti

Computational Biology Institute

Salinity gradients are critical habitat determinants for freshwater organisms. Silverside fishes in the genus Odontesthes have recently and repeatedly transitioned from marine to freshwater habitats, overcoming a strong ecological barrier. Genomic and transcriptomic changes involved in this kind of transition are only known for a few model species. We present new data and analyses of gene expression and microbiome composition in the gills of two closely related silverside species, marine O. argentinensis and freshwater O. bonariensis and find more than three thousand transcripts differentially expressed, with osmoregulatory/ion transport genes and immune genes showing very different expression patterns across species. Interspecific …

Rnaseq Analysis Of The Drosophila Response To The Entomopathogenic Nematode Steinernema., Shruti Yadav, Sean Daugherty, Amol Carl Shetty, Ioannis Eleftherianos

Computational Biology Institute

Drosophila melanogaster is an outstanding model to study the molecular and functional basis of host-pathogen interactions. Currently, our knowledge of microbial infections in D. melanogaster is well understood; however, the response of flies to nematode infections is still in its infancy. Here, we have used the potent parasitic nematode Steinernema carpocapsae, which lives in mutualism with its endosymbiotic bacteria Xenorhabdus nematophila, to examine the transcriptomic basis of the interaction between D. melanogaster and entomopathogenic nematodes. We have employed next-generation RNA sequencing (RNAseq) to investigate the transcriptomic profile of D. melanogaster larvae in response to infection by S. carpocapsae symbiotic (carrying …

Estimation Of The True Evolutionary Distance Under The Fragile Breakage Model., Nikita Alexeev, Max A Alekseyev

Computational Biology Institute

BACKGROUND: The ability to estimate the evolutionary distance between extant genomes plays a crucial role in many phylogenomic studies. Often such estimation is based on the parsimony assumption, implying that the distance between two genomes can be estimated as the rearrangement distance equal the minimal number of genome rearrangements required to transform one genome into the other. However, in reality the parsimony assumption may not always hold, emphasizing the need for estimation that does not rely on the rearrangement distance. The distance that accounts for the actual (rather than minimal) number of rearrangements between two genomes is often referred to …

Transcriptomic Effects Of Dispersed Oil In A Non-Model Decapod Crustacean, Hernan Vazquez-Miranda, Brent Thoma, Juliet Wong, Darryl Felder, Keith A. Crandall, Heather Bracken-Grissom

Computational Biology Institute

Background. Oil spills are major environmental disasters. Dispersants help control spills, as they emulsify oil into droplets to speed bioremediation. Although dispersant toxicity is controversial, the genetic consequences and damages of dispersed oil exposure are poorly understood. We used RNA-seq to measure gene expression of flatback mudcrabs (Eurypanopeus depressus, Decapoda, Brachyura, Panopeidae) exposed to dispersed oil.

Methods. Our experimental design included two control types, oil-only, and oil-dispersant treatments with three replicates each. We prepared 100 base pair-ended libraries from total RNA and sequenced them in one Illumina HiSeq2000 lane. We assembled a reference transcriptome with all replicates per treatment, …

The Temporal Dynamics Of The Tracheal Microbiome In Tracheostomised Patients With And Without Lower Respiratory Infections., Marcos Pérez-Losada, Robert J Graham, Madeline Coquillette, Amenah Jafarey, Eduardo Castro-Nallar, Manuel Aira, Robert J Freishtat, Jonathan M Mansbach

Computational Biology Institute

Background: Airway microbiota dynamics during lower respiratory infection (LRI) are still poorly understood due, in part, to insufficient longitudinal studies and lack of uncontaminated lower airways samples. Furthermore, the similarity between upper and lower airway microbiomes is still under debate. Here we compare the diversity and temporal dynamics of microbiotas directly sampled from the trachea via tracheostomy in patients with (YLRI) and without (NLRI) lower respiratory infections. Methods: We prospectively collected 127 tracheal aspirates across four consecutive meteorological seasons (quarters) from 40 patients, of whom 20 developed LRIs and 20 remained healthy. All aspirates were collected when patients had no …