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Biased associations have been a challenge in the development of classifiers for detecting toxic language, hindering both fairness and accuracy. As potential solutions, we investigate recently introduced debiasing methods for text classification datasets and models, as applied to toxic language detection. Our focus is on lexical (e.g., swear words, slurs, identity mentions) and dialectal markers (specifically African American English). Our comprehensive experiments establish that existing methods are limited in their ability to prevent biased behavior in current toxicity detectors. We then propose an automatic, dialect-aware data correction method, as a proof-of-concept. Despite the use of synthetic labels, this method reduces dialectal associations with toxicity. Overall, our findings show that debiasing a model trained on biased toxic language data is not as effective as simply relabeling the data to remove existing biases.more » « less
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Abstract The
Microcystis mobilome is a well-known but understudied component of this bloom-forming cyanobacterium. Through genomic and transcriptomic comparisons, we found five families of transposases that altered the expression of genes in the well-studied toxigenic type-strain,Microcystis aeruginosa PCC 7086, and a non-toxigenic genetic mutant,Microcystis aeruginosa PCC 7806 ΔmcyB . Since its creation in 1997, the ΔmcyB strain has been used in comparative physiology studies against the wildtype strain by research labs throughout the world. Some differences in gene expression between what were thought to be otherwise genetically identical strains have appeared due to insertion events in both intra- and intergenic regions. In our ΔmcyB isolate, a sulfate transporter gene cluster (sbp-cysTWA ) showed differential expression from the wildtype, which may have been caused by the insertion of a miniature inverted repeat transposable element (MITE) in the sulfate-binding protein gene (sbp ). Differences in growth in sulfate-limited media also were also observed between the two isolates. This paper highlights howMicrocystis strains continue to “evolve” in lab conditions and illustrates the importance of insertion sequences / transposable elements in shaping genomic and physiological differences betweenMicrocystis strains thought otherwise identical. This study forces the necessity of knowing the complete genetic background of isolates in comparative physiological experiments, to facilitate the correct conclusions (and caveats) from experiments. -
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Abstract Early detection of predators is critical to the survival of all living organisms. For phytoplankton, recognition and response to chemical cues from predators, as evidence of predation risk, are particularly crucial. The phytoplankton
Alexandrium minutum upregulates its toxicity when exposed to copepodamides, a suite of compounds released by copepod predators. However, howA. minutum perceives these predatory cues and what metabolic pathways are involved in initiating toxin induction remains unknown. In this study, liquid chromatography‐mass spectrometry and NMR‐based metabolomics uncovered subtle physiological responses ofA. minutum to copepodamides, including altered regulation of branched‐chain amino acid biosynthesis and potential enhancement of butanoate metabolism and arginine biosynthesis. While we have yet to identify a chemoreceptor directly activated by copepod cues, based on the results of inhibition experiments, detection of copepodamides appears to disrupt the activity of serine/threonine phosphatases leading to increased jasmonic acid biosynthesis and signaling, which leads to amplified gonyautoxin biosynthesis inA. minutum . This study is an important step toward a better understanding of chemosensory ecology of predator–prey interactions in phytoplankton.
