PO <sub>2</sub> Profiles in the Retina of the Hemoglobin‐less Icefishes
Notice bibliographique
Résumé
The retina of vertebrates has one of the highest O 2 demands and requires a constant O 2 supply. Four general types of retinal circulations have been described for O 2 delivery in extant vertebrates: 1) sole reliance on the choriocapillaris; 2) capillaries penetrating the retina; 3) capillarization of the inner side of the retina; and 4) O 2 secretion. Oxygen secretion is based on acid secretion into the blood resulting in a potent unloading of O 2 from so‐called Root effect hemoglobins (Hb), which is augmented by venous to arterial O 2 diffusion in a vascular rete lining the back side of the retina. This choroid rete mirabile (CRM) allows O 2 delivery at super‐atmospheric pressure in the avascular retina of some fishes that have the thickest retinae and some of the largest eyes (relative to body size) of all extant vertebrates. The suborder Notothenioidei, which consists of Antarctic and sub‐Antarctic fishes, provides a model system to unravel how the interactions between Hb function and retinal vascularity evolved to produce modern fish eyes. While several phyletically basal notothenioids have been shown to display similar ocular arrangements as in other Perciform species containing a CRM, more phyletically derived notothenioids have highly reduced CRM or have lost it completely. Of particular interest are the species of the family Channichthyidae, icefishes, that are unique among adult vertebrates in possessing pale white blood containing only few vestigial immature erythrocytes and no Hb. Without Hb, O 2 secretion is not functional, and icefishes have been demonstrated to possess heavily increased pre‐retinal capillarization most probably to maintain retinal oxygenation and preserve large eyes and thick retinae. However, whether available O 2 at different retinal levels actually follows the degree of vascularization has not been tested. Using thin O 2 sensors, we measured profiles of partial pressure of O 2 (PO 2 ) in the retina of six species of icefishes, two species of related, but red‐blooded dragonfishes (Bathydraconidae), and four species of more distantly related notothens (Nototheniidae). Arterial PO 2 was statistically significantly higher in icefishes than in notothens [t‐test; p = 0.0066 (n = 3); P a O 2 = 16.64 ± 3.84 kPa in Chaenocephalus aceratus ; P a O 2 = 4.42 ± 1.40 kPa in Notothenia coriiceps ]. In general, pre‐retinal PO 2 was high in icefishes (19.20 ± 6.35 kPa in C. aceratus ), approaching the theoretical O 2 solubility limit without O 2 secretion. The PO 2 level decreased towards the outer portion of the retina, but with a small peak on the choroid side of the retina, possibly due to a vestigial choriocapillaris. In notothens displaying Root effect, pre‐retinal PO 2 was slightly lower (12.07 ± 5.12 kPa in N. coriiceps ) but increased to a super‐atmospheric level on the outer portion of the retina (52.25 ± 32.46 kPa in N. coriiceps ). Our results demonstrate that retinal PO 2 is dictated by vascularization in the Hb‐deprived icefishes, leading to a unique reversal in the retinal oxygen profile. Support or Funding Information US National Science Foundation grant PLR‐1444167 Carlsberg Foundation Velux Foundations 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 distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 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 | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 tête enseignante, 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 ».