The gut epithelium from feeding to fasting in the predatory soil mite Pergamasus longicornis (Mesostigmata: Parasitidae): one tissue, two roles
Bibliographic record
Abstract
A review of acarine gut physiology based on published narratives dispersed over the historical international literature is given. Then, in an experimental study of the free-living predatory soil mite Pergamasus longicornis (Berlese), quantitative micro-anatomical changes in the gut epithelium are critically assessed from a temporal series of histological sections during and after feeding on larval dipteran prey. An argued functional synthesis based upon comparative kinetics is offered for verification in other mesostigmatids. Mid- and hind-gut epithelia cell types interconvert in a rational way dependent upon the physical consequences of ingestion, absorption and egestion. The fasted transitional pseudo-stratified epithelium rapidly becomes first squamous on prey ingestion (by stretching), then columnar during digestion before confirmed partial disintegration (gut 'lumenation') during egestion back to a pseudo-stratified state. Exponential processes within the mid- and endodermic hind-gut exhibit 'stiff' dynamics. Cells expand rapidly ([Formula: see text] 22.9-49.5 min) and vacuolate quickly ([Formula: see text] 1.1 h). Cells shrink very slowly ([Formula: see text] 4.9 days) and devacuolate gently ([Formula: see text] 1.0-1.7 days). Egestive cellular degeneration has an initial [Formula: see text] 7.7 h. Digestion appears to be triggered by maximum gut expansion-estimated at 10 min post start of feeding. Synchrony with changes in gut lumen contents suggests common changes in physiological function over time for the cells as a whole tightly-coupled epithelium. Distinct in architecture as a tissue over time the various constituent cell types appear functionally the same. Functional phases are: early fluid transportation (0-1 h) and extracellular activity (10-90 min); through rising food absorption (10 min to [Formula: see text] day); to slow intracellular meal processing and degenerative egestive waste material production (1 to [Formula: see text] days) much as in ticks. The same epithelium is both absorptive and degenerative in role. The switch in predominant physiology begins 4 h after the start of feeding. Two separate pulses of clavate cells appear to be a mechanism to facilitate transport by increasing epithelial surface area in contact with the lumen. Free-floating cells may augment early extracellular lumenal digestion. Possible evidence for salivary enzyme alkaline-related extra-corporeal digestion was found. Giant mycetome-like cells were found embedded in the mid-gut wall. Anteriorly, the mid-gut behaves like a temporally expendable food processing tissue and minor long-term resistive store. Posteriorly the mid-gut behaves like a major assimilative/catabolic tissue and 'last-out' food depot (i.e., a 'hepatopancreas' function) allowing the mite to resist starvation for up to 3.5 weeks after a single meal. A 'conveyor-belt' wave of physiology (i.e., feeding and digestion, then egestion and excretion) sweeps posteriorly but not necessarily pygidially over time. Assimilation efficiency is estimated at 82%. The total feeding cycle time histologically from a single meal allowing for the bulk of intracellular digestion and egestive release is not 52.5 h but of the order of 6 days ([Formula: see text] total gut emptyings per day), plus typically a further 3 days for subsequent excretion to occur. Final complete gut system clearance in this cryptozooid may take much longer ([Formula: see text] days). A common physiology across the anactinotrichid acarines is proposed. A look to the future of this field is included.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".