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Weinrauch AM, Fehrmann F, Anderson WG. Sustained endocrine and exocrine function in the pancreas of the Pacific spiny dogfish post-feeding. FISH PHYSIOLOGY AND BIOCHEMISTRY 2022; 48:645-657. [PMID: 35411445 DOI: 10.1007/s10695-022-01070-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
Secretions of the exocrine pancreas contain digestive enzymes integral to the digestive process. The Pacific spiny dogfish (Squalus suckleyi) has a discrete pancreas, divided into two lobes termed the dorsal and ventral lobes. These lobes drain into the anterior intestine via a common duct to enable digestion. Previous studies have identified that the exocrine pancreas produces (co)lipases, chymotrypsin, carboxypeptidase, and low levels of chitinases; however, investigations into other digestive enzymes are limited. We detect the presence of lipase, trypsin, and carbohydrase and show that activities are equivalent between both lobes of the pancreas. Additionally, we sought to investigate the influence of a single feeding event (2% body weight ration of herring by gavage) on enzyme activities over an extended time course (0, 20, 48, 72, 168 h) post-feeding. The results indicate that there are no differences in pancreatic tissue digestive enzyme activities between fed or fasted states. Analysis of acinar cell circumference post-feeding demonstrates a significant increase at 20 and 48 h, that returns to fasting levels by 72 h. No significant changes were observed regarding whole-tissue insulin or glucagon mRNA abundance or with glucose transporter (glut) 1 or 3. Yet, a significant and transient decrease in glut4 and sodium glucose-linked transporter mRNA abundance was found at 48 h post-feeding. We propose that the constant enzyme activity across this relatively large organ, in combination with a relatively slow rate of digestion leads to an evenly distributed, sustained release of digestive enzymes regardless of digestive state.
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Affiliation(s)
- Alyssa M Weinrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
- Bamfield Marine Sciences Centre, Bamfield, BC, V0R 1B0, Canada.
| | - Frauke Fehrmann
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
- Bamfield Marine Sciences Centre, Bamfield, BC, V0R 1B0, Canada
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Eom J, Lauridsen H, Wood CM. Breathing versus feeding in the Pacific hagfish. J Exp Biol 2022; 225:274669. [PMID: 35262176 DOI: 10.1242/jeb.243989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 02/24/2022] [Indexed: 11/20/2022]
Abstract
Hagfish represent the oldest extant connection to the ancestral vertebrates, but their physiology is not well understood. Using behavioural (video), physiological (respirometry, flow measurements), classical morphological (dissection, silicone injection) and modern imaging approaches (micro-MRI, DICE micro-CT) we examined the interface between feeding and the unique breathing mechanism (nostril, high frequency velum, low frequency gill pouches (24) and pharyngo-cutaneous duct,PCD) in the Pacific hagfish, Eptatretus stoutii. A video tour via micro-MRI is presented through the breathing and feeding passages. We have reconciled earlier disagreement as to the position of the velum chamber, which powers inhalation through the nostril, placing it downstream of the merging point of food and water passages, such that the oronasal septum terminates at the anterior end of the velum chamber. When feeding occurs by engulfment of large chunks by the dental plates, food movement through the chamber may transiently interfere with breathing. Swallowing is accelerated by peristaltic body undulation involving the ventral musculature, and is complete within 5 sec. After a large meal (anchovy, 20% body mass), hagfish remain motionless, defecating bones and scales at 1.7 days and an intestinal peritrophic membrane at 5 days. O2 consumption rate approximately doubles within 1 h after feeding, remaining elevated through 12-24 h. This is achieved by combinations of elevated O2 utilization and ventilatory flow, the latter caused by varying increases in velar frequency and stroke volume. Additional imaging casts light on the reasons for the trend for greater O2 utilization by more posterior pouches and PCD in fasted hagfish.
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Affiliation(s)
- Junho Eom
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
| | - Henrik Lauridsen
- Department of Clinical Medicine, Aarhus University, Aarhus N, Denmark
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
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Weinrauch AM, Clifford AM, Folkerts EJ, Schaefer CM, Giacomin M, Goss GG. Molecular identification and post-prandial regulation of glucose carrier proteins in the hindgut of Pacific hagfish, Eptatretus stoutii. Am J Physiol Regul Integr Comp Physiol 2022; 322:R336-R345. [PMID: 35138949 DOI: 10.1152/ajpregu.00003.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hagfish are an excellent model species in which to draw inferences on the evolution of transport systems in early-vertebrates owing to their basal position in vertebrate phylogeny. Glucose is a ubiquitous cellular energy source that is transported into cells via two classes of carrier proteins: sodium-glucose linked transporters (Sglt; Slc5a) and glucose transporters (Glut; Slc2a). While previous pharmacological evidence has suggested the presence of both sodium-dependent and -independent transport mechanisms in the hagfish, the molecular identities were heretofore unconfirmed. We have identified and phylogenetically characterized both a Slc5a1-like and Slc2a-like gene in the Pacific hagfish (Eptatretus stoutii); the latter sharing common ancestry with other glucose-transporting isoforms of the Slc2a family. To assess the potential post-prandial regulation of these glucose transporters, we examined the abundance and localization of these transporters with qPCR and immunohistochemistry alongside functional studies using radiolabeled 14C-D-glucose. The effects of glucose- or insulin-injection on glucose transport rate and transporter expression were also examined to determine their potential role(s) in the regulation of intestinal glucose carrier proteins. Feeding prompted an increase in glucose uptake across the hindgut at both 0.5 mM (~84%) and 1 mM (~183%) concentrations. Concomitant increases were observed in hindgut Slc5a1 protein expression. These effects were not observed following either of glucose- or insulin-injection, indicating these post-prandial factors are not the driving force for transporter regulation over this timeframe. We conclude that Pacific hagfish utilize evolutionarily-conserved mechanisms of glucose uptake and so represent a useful model to understand early vertebrate evolution of glucose uptake and regulation.
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Affiliation(s)
- Alyssa M Weinrauch
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, BC, Canada
| | - Alexander M Clifford
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, BC, Canada.,Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, United States
| | - Erik J Folkerts
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Christina M Schaefer
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, BC, Canada
| | - Marina Giacomin
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, BC, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, BC, Canada
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Eom J, Wood CM. Understanding ventilation and oxygen uptake of Pacific hagfish (Eptatretus stoutii), with particular emphasis on responses to ammonia and interactions with other respiratory gases. J Comp Physiol B 2021; 191:255-271. [PMID: 33547930 DOI: 10.1007/s00360-020-01329-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/18/2020] [Accepted: 11/15/2020] [Indexed: 11/24/2022]
Abstract
The hagfishes are an ancient and evolutionarily important group, with breathing mechanisms and gills very different from those of other fishes. Hagfish inhale through a single nostril via a velum pump, and exhale through multiple separate gill pouches. We assessed respiratory performance in E. stoutii (31 ppt, 12 ºC, 50-120 g) by measuring total ventilatory flow ([Formula: see text]) at the nostril, velar (respiratory) frequency (fr), and inspired (PIO2) and expired (PEO2) oxygen tensions at all 12 gill pouch exits plus the pharyngo-cutaneous duct (PCD) on the left side, and calculated ventilatory stroke volume (S[Formula: see text]), % O2 utilization, and oxygen consumption (ṀO2). At rest under normoxia, spontaneous changes in [Formula: see text] ranged from apnea to > 400 ml kg-1 min-1, due to variations in both fr and S[Formula: see text]; "normal" [Formula: see text] averaged 137 ml kg-1 min-1, ṀO2 was 718 µmol kg-1 h-1, so the ventilatory convection requirement for O2 was about 11 L mmol-1. Relative to anterior gill pouches, lower PEO2 values (i.e. higher utilization) occurred in the more posterior pouches and PCD. Overall, O2 utilization was 34% and did not change during hyperventilation but increased to > 90% during hypoventilation. Environmental hypoxia (PIO2 ~ 8% air saturation, 1.67 kPa, 13 Torr) caused hyperventilation, but neither acute hyperoxia (PIO2 ~ 275% air saturation, 57.6 kPa, 430 Torr) nor hypercapnia (PICO2 ~ 1% CO2, 1.0 kPa, 7.5 Torr) significantly altered [Formula: see text]. ṀO2 decreased in hypoxia and increased in hyperoxia but did not change in hypercapnia. Acute exposure to high environmental ammonia (HEA, 10 mM NH4HCO3) caused an acute decrease in [Formula: see text], in contrast to the hyperventilation of long-term HEA exposure described in a previous study. The hypoventilatory response to HEA still occurred during hypoxia and hyperoxia, but was blunted during hypercapnia. Under all treatments, ṀO2 increased with increases in [Formula: see text]. Overall, there were lower convection requirements for O2 during hyperoxia, higher requirements during hypoxia and hypercapnia, but unchanged requirements during HEA. We conclude that this "primitive" fish operates a flexible respiratory system with considerable reserve capacity.
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Affiliation(s)
- Junho Eom
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada
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Weinrauch AM, Blewett TA, Glover CN, Goss GG. Acquisition of alanyl-alanine in an Agnathan: Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii. JOURNAL OF FISH BIOLOGY 2019; 95:1471-1479. [PMID: 31621087 DOI: 10.1111/jfb.14168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/15/2019] [Indexed: 06/10/2023]
Abstract
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 (Jmax -like) of 70 ± 3 nmol cm-2 h-1 and an affinity constant (Km -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 Km 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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Affiliation(s)
- Alyssa M Weinrauch
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
| | - Tamzin A Blewett
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
| | - Chris N Glover
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
- Faculty of Science and Technology and Athabasca River Basin Research Institute, Athabasca University, Athabasca, Alberta, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
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Glover CN, Weinrauch AM. The good, the bad and the slimy: experimental studies of hagfish digestive and nutritional physiology. ACTA ACUST UNITED AC 2019; 222:222/14/jeb190470. [PMID: 31308056 DOI: 10.1242/jeb.190470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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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Affiliation(s)
- Chris N Glover
- Athabasca River Basin Research Institute and Faculty of Science and Technology, Athabasca University, Athabasca, AB T9S 3A3, Canada .,Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Alyssa M Weinrauch
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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Weinrauch AM, Schaefer CM, Goss GG. Activity and post-prandial regulation of digestive enzyme activity along the Pacific hagfish (Eptatretus stoutii) alimentary canal. PLoS One 2019; 14:e0215027. [PMID: 30951564 PMCID: PMC6450612 DOI: 10.1371/journal.pone.0215027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/25/2019] [Indexed: 02/05/2023] Open
Abstract
Hagfishes are living representatives of the earliest-diverging vertebrates and are thus useful for the study of early vertebrate physiology. It has been previously postulated that digestive enzymes account for the majority of digestion because hagfish are agastric with notable zymogen granules in specialized cells of the hindgut. While the presence of some digestive enzymes (amylase, lipase and leucinaminopeptidase) have been confirmed with histochemistry, quantification of enzymatic activity is limited. This study sought to biochemically quantify the tissue activity of six digestive enzymes (α-amylase, maltase, lipase, trypsin, aminopeptidase and alkaline phosphatase) along the length of the Pacific hagfish (Eptatretus stoutii) alimentary canal. In addition, the effect of feeding on the rate of enzyme activity was examined. Overall, maltase and trypsin activities were unchanging with respect to location or feeding status, while the activities of α-amylase and alkaline phosphatase decreased substantially following feeding, but were consistent along the length. Lipase and aminopeptidase activities were elevated in the anterior region of the alimentary canal in comparison to the more posterior regions, but were not altered with feeding. This study indicates hagfish have an assortment of digestive enzymes that likely are the result of a varied diet. The differential expression of these enzymes along the tract and in regards to feeding may be indications of early compartmentalization of digestive function.
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Affiliation(s)
- Alyssa M. Weinrauch
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
- * E-mail:
| | - Christina M. Schaefer
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
| | - Greg G. Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
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Glover CN, Weinrauch AM, Bynevelt S, Bucking C. Feeding in Eptatretus cirrhatus: effects on metabolism, gut structure and digestive processes, and the influence of post-prandial dissolved oxygen availability. Comp Biochem Physiol A Mol Integr Physiol 2019; 229:52-59. [DOI: 10.1016/j.cbpa.2018.11.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/27/2018] [Accepted: 11/29/2018] [Indexed: 12/13/2022]
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