Effects of Intraluminal Pressure on Motility in the Crop and Gizzard of the Earthworm, <i>Lumbricus terrestris</i>
Notice bibliographique
Résumé
The present study was designed to examine motility in the isolated earthworm gut. The physiological significance of, environmental stimuli that trigger, and cellular and molecular basis of gut motility in this species are unclear. Earthworms (Canadian Nightcrawlers) were obtained from a local fishing bait supplier. Worms were kept at 4 °C until the day of study. Worms were housed in worm bedding until 2–7 days prior to experimentation, at which time they were transferred into a petri dish lined with a water‐moistened paper towel to allow the gut to be partially emptied. On the day of study, worms were anesthetized by placing them in a beaker containing 200 ml of tap water and 1–2 Alka‐Seltzer tablets. Anesthetized worms were dissected, and the crop and gizzard was removed en bloc, cleaned of adhering septal and connective tissue, and transferred to a tissue bath containing worm saline at room temperature (~20 °C). The gut preparation was cannulated at both ends using 20G stainless steel hypodermic tubing. The lumen was filled with worm saline. The distal cannula was connected to a pressure transducer and closed by a stopcock. The proximal cannula was connected to a 30 ml syringe filled with worm saline that was open to atmospheric pressure. The height of the syringe could be raised and lowered to control intraluminal pressure. The preparation was equilibrated at ambient pressure for approximately 30 minutes. Following equilibration, intraluminal pressure was elevated incrementally every 5–10 minutes. A camera placed above the tissue bath recorded video (30 frames per second) during each pressure maneuver. The video was analyzed off line using a custom spatiotemporal mapping algorithm to assess luminal diameter. We found that the gut exhibited very low amplitude (<1 mmHg) pressure fluctuations at ambient pressure, and these pressure fluctuations were associated with waves of constriction/dilation in the gut lumen. Raising intraluminal pressure slightly from 0 to 2 mmHg induced a robust motor response such that the organ first passively dilated in response to the increase in intraluminal pressure, and then both gut regions constricted by up to 30%. The constrictions were followed by dilations, and this pattern continued, such that motility appeared as phasic waves of constriction/dilation. These robust phasic motor patterns were associated with large amplitude (20 mmHg) pressure pulsations. Larger motor events were in phase with larger pressure pulsations, and smaller motor events occurred in phase with smaller pressure pulsations. At higher intraluminal pressures (10 mmHg), the gut passively dilated, and motor events ceased, while intraluminal pressure passively tracked the applied hydrostatic pressure with no further pressure pulsations. Thus, we conclude that the earthworm crop/gizzard exhibits a robust mechanical response that is triggered by distention of the organ wall occurring with elevated intraluminal pressure. This response is likely to be of physiological significance, and may underlie peristalsis and propulsion of luminal contents in this species. The cellular and chemical basis of this response is not known. Support or Funding Information Support provided by Med Associates and Catamount Research and Development. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».