Anatomy of the Pacific hagfish (Eptatretus stoutii)

Weinrauch, Alyssa M.; Edwards, Scott A.; Goss, Gregory G.

doi:10.1201/b18935-2

Cited by 9 publications

(12 citation statements)

References 64 publications

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“…The variable timespan between meals, compounded with the relatively simple digestive tract, highlights the necessity for maximal nutrient absorption when a meal becomes available. Specifically, the tract begins with the pharyngocutaneous duct; a relatively thin structure comprising mucous cells, epithelial cells, acidophilic secretory granules and undifferentiated cells (Adam, ; Weinrauch et al ., ). The cellular composition indicates a role for lubrication to aid in the progression of the food bolus down the tract.…”

Section: Discussionmentioning

confidence: 97%

“…The straight, uncoiled hindgut is quite distinct with zig‐zag folds that are retained during intestinal distention. Digestion is accomplished using zymogen granules, released from distinct cells of the hindgut and absorption occurs across the apical brush border of the columnar cells (Adam, ; Weinrauch et al ., , ,c). The morphological data suggest hagfishes have a hindgut lacking regional functional specialisation, that would permit maximal nutrient uptake following a binge.…”

Section: Discussionmentioning

confidence: 99%

“…The hindgut was separated into 2–4 cm sections and tied into sacs as described previously (Glover et al ., ). Of note, uptake in the pharyngocutaneous duct was not conducted owing to its small, fragile nature and the conglomeration of mucous cells, as opposed to brush border absorptive cells (Weinrauch et al ., ). Briefly, one end of the intestinal segment was tied off with suture silk and a flared piece of PE‐90 tubing was inserted into the opposing end and subsequently secured with suture.…”

Section: Methodsmentioning

confidence: 97%

“…Indeed, hagfish are capable of acquiring nutrients across multiple epithelia including the skin and gills, much like soft‐bodied marine invertebrates (Glover et al ., ). Although these animals are agastric and have a primitive digestive system consisting of a straight, undifferentiated hindgut (Adam, ; Weinrauch et al ., ), nutrient transport mechanisms appear to be highly conserved relative to those of later‐diverging vertebrates (Glover et al ., , ; Schultz et al ., ; Weinrauch et al ., ; Young et al ., ). These animals are therefore ideally suited for studies aiming to understand the evolution of early vertebrate nutrient transport systems.…”

Section: Introductionmentioning

confidence: 99%

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Acquisition of alanyl‐alanine in an Agnathan: Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii

Weinrauch

Blewett

Glover

et al. 2019

Journal of Fish Biology

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This study used 3 H-L -alanyl-L -alanine to demonstrate dipeptide uptake using in vitro gut sacs prepared from the hindgut of the Pacific hagfish Eptatretus stoutii.Concentration-dependent kinetic analysis resulted in a sigmoidal distribution with a maximal (± SE) uptake rate (J max -like) of 70 ± 3 nmol cm −2 h −1 and an affinity constant (K m -like) of 1072 ± 81 μM. Addition of high alanine concentrations to transport assays did not change dipeptide transport rates, indicating that hydrolysis of the dipeptide in mucosal solutions and subsequent uptake via apical amino acid transporters was not occurring, which was further supported by a K m distinct from that of amino acid transport. Transport occurred independent of mucosal pH, but uptake was reduced by 42% in low mucosal sodium. This may implicate cooperation between peptide transporters and sodium-proton exchangers, previously demonstrated in several mammalian and teleost species. Finally, apical L -alanyl-L -alanine uptake rates (i.e., mucosal disappearance) were significantly increased following a meal, demonstrating regulation of uptake. Overall, this examination of dipeptide acquisition in the earliest extant Agnathan suggests evolutionarily conserved mechanisms of transport between hagfish and later-diverging vertebrates such as teleosts and mammals.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Acquisition of alanyl‐alanine in an Agnathan: Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii

Weinrauch

Blewett

Glover

et al. 2019

Journal of Fish Biology

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“…As the extracellular fluid osmolality of hagfish matches that of their environment, net ion and water fluxes are minimised. This reduces the need to utilise the integument as a barrier, leading to an epidermal structure that favours exchange over protection, and ultimately results in a permeable skin surface capable of acquiring nutrients (Weinrauch et al, 2016;Glover et al, 2017). By contrast, osmoregulating animals (see Glossary) rely on minimal exchange of ions and water across their epidermal epithelia to reduce the costs of regulation.…”

Section: Introductionmentioning

confidence: 99%

The good, the bad and the slimy: experimental studies of hagfish digestive and nutritional physiology

Glover

Weinrauch

2019

Journal of Experimental Biology

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The hagfishes provide valuable insight into the physiology of feeding, digestion and nutrient absorption by virtue of unusual and unique features of their biology. For example, members of this group undergo long periods of fasting, and are the only vertebrates known to absorb organic nutrients across their epidermal surface. Such properties engender significant attention from researchers interested in feeding and feeding-related processes; however, the practical realities of employing the hagfish as an experimental organism can be challenging. Many of the key tools of the experimental biologist are compromised by a species that does not readily feed in captivity, is difficult to instrument and which produces copious quantities of slime. This Commentary provides critical insight into the key aspects of hagfish feeding and digestive processes, and highlights the pitfalls of this group as experimental organisms. We also suggest key research gaps that, if filled, will lead to better understanding of hagfishes, and we consider how this group may advance our knowledge of feeding, digestion and nutrient absorption processes.

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Comparison of vertebrate skin structure at class level: A review

Akat

Yenmiş

Pombal

et al. 2022

The Anatomical Record

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The skin is a barrier between the internal and external environment of an organism. Depending on the species, it participates in multiple functions. The skin is the organ that holds the body together, covers and protects it, and provides communication with its environment. It is also the body's primary line of defense, especially for anamniotes. All vertebrates have multilayered skin composed of three main layers: the epidermis, the dermis, and the hypodermis. The vital mission of the integument in aquatic vertebrates is mucus secretion. Cornification began in apmhibians, improved in reptilians, and endured in avian and mammalian epidermis. The feather, the most ostentatious and functional structure of avian skin, evolved in the Mesozoic period. After the extinction of the dinosaurs, birds continued to diversify, followed by the enlargement, expansion, and diversification of mammals, which brings us to the most complicated skin organization of mammals with differing glands, cells, physiological pathways, and the evolution of hair. Throughout these radical changes, some features were preserved among classes such as basic dermal structure, pigment cell types, basic coloration genetics, and similar sensory features, which enable us to track the evolutionary path. The structural and physiological properties of the skin in all classes of vertebrates are presented. The purpose of this review is to go all the way back to the agnathans and follow the path step by step up to mammals to provide a comparative large and updated survey about vertebrate skin in terms of morphology, physiology, genetics, ecology, and immunology.

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Anatomy of the Pacific hagfish (Eptatretus stoutii)

Cited by 9 publications

References 64 publications

Acquisition of alanyl‐alanine in an Agnathan: Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii

Acquisition of alanyl‐alanine in an Agnathan: Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii

The good, the bad and the slimy: experimental studies of hagfish digestive and nutritional physiology

Comparison of vertebrate skin structure at class level: A review

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