In silico hybridization enables transcriptomic illumination of the nature and evolution of Myxozoa
Bibliographic record
Abstract
BACKGROUND: The Myxozoa, a group of oligocellular, obligate endoparasites, has long been poorly understood in an evolutionary context. Recent genome-level sequencing techniques such as RNA-seq have generated large amounts of myxozoan sequence data, providing valuable insight into their evolutionary history. However, sequences from host tissue contamination are present in next-generation sequencing reactions of myxozoan tissue, and differentiating between the two has been inadequately addressed. In order to shed light on the genetic underpinnings of myxozoan biology, assembled contigs generated from these studies that derived from the myxozoan must be decoupled from transcripts derived from host tissue and other contamination. This study describes a pipeline for categorization of transcripts asmyxozoan based on similarity searching with known host and parasite sequences, explores the extent to which host contamination is present in previously existing myxozoan datasets, and implements this pipeline on a newly sequenced transcriptome of Myxobolus pendula, a parasite of the common creek chub gill arch. METHODS: The insilico hybridization pipeline uses iterative BLAST searching and database-driven e-value comparison to categorize transcripts as deriving from host, parasite, or other contamination. Functional genetic analysis of M. pendula was conducted using further BLAST searching, Hidden Markov Modeling, and sequence alignment and phylogenetic reconstruction. RESULTS: Three RNA libraries of encysted M. pendula plasmodia were sequenced and subjected to the method. Nearly half of the final set of contiguous assembly sequences (47.3 %) was identified as putative myxozoan transcripts. Putative contamination was also identified in at least 1/3(rd) of previously published myxozoan transcripts. The set of M. pendula transcripts was mined for a range of biologically insightful genes, including taxonomically restricted nematocyst structural proteins and nematocyst proteins identified through mass tandem spectrometry of other cnidarians. Several novel findings emerged, including a fourth myxozoan minicollagen gene, putative myxozoan toxin proteins,and extracellular matrix glycoproteins. CONCLUSIONS: This study serves as a model for the handling of next-generation myxozoan sequence. The need for careful categorization was demonstrated in both previous and new sets of myxozoan sequences. The final set of confidently assigned myxozoan transcripts can be mined for any biologically relevant gene or gene family without spurious misidentification of host contamination as a myxozoan homolog. As exemplified by M. pendula, the repertoire of myxozoan polar capsules may be more complex than previously thought, with an additional minicollagen homolog and putative expression of toxin proteins.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".