Bruce L. Tufts

The structure and function of carbonic anhydrase isozymes in the respiratory system of vertebrates

Carbonic anhydrase is a ubiquitous metalloenzyme that catalyzes the reversible hydration/dehydration of carbon dioxide. To date, 16 different CA isozymes have been identified in mammals, and several novel isozymes have also been identified in non-mammalian vertebrates. These isozymes are involved in many physiological processes; however, one of the most important roles is facilitating the transport and subsequent excretion of carbon dioxide. As such, CA isozymes are found at virtually every step of the process, including the metabolic site of CO(2) production (muscle), the circulating red blood cells, and the primary respiratory surface (gills/lungs). This review will examine the structural characteristics that are integral to CAs participation in respiration, as well as highlight the specific roles and tissues that the different CA isozymes are involved in.

Effects of Catch-and-Release Angling on Nesting Male Smallmouth Bass

Abstract We assessed the effects of angling stress on nesting male smallmouth bass Micropterus dolomieu from two lakes in southeastern Ontario. In the first portion of the study, adult male smallmouth bass were hooked and then played either briefly (<20 s) or to exhaustion (2 min). White muscle acid–base and metabolite status were used as indicators of the extent of the physiological disturbance in these fish. Angling of smallmouth bass resulted in decreases in muscle pH and energy reserves for burst activity (phosphocreatine and adenosine triphosphate), as well as increases in muscle lactate, metabolic protons (▵H+), and partial pressure of carbon dioxide (Pco2). The physiological disturbance was most severe in smallmouth bass played to exhaustion. In the second portion of the study, other adult male smallmouth bass were hooked and played as described above. Fish played to exhaustion took four times longer to return to their nests than did fish played briefly. As a result, offspring in the nests of fish ...

Physiological Significance of the Weigh-In during Live-Release Angling Tournaments for Largemouth Bass

Abstract In the current study, we simulated different components of a live-release angling tournament (angling, live-well confinement, and weigh-in) to determine the relative physiological significance of these tournament components for largemouth bass Micropterus salmoides. Our results indicated that depletions of white muscle energy stores and accumulations of muscle lactate (i.e., a large metabolic disturbance) are the most important consequences of live-release angling tournaments for largemouth bass. This study also showed that there are two distinct components of a live-release tournament that cause a metabolic disturbance in largemouth bass: angling and the weigh-in. While the physiological consequences of angling are already well understood, this is the first study to show that the weigh-in portion of a live-release tournament also causes a large anaerobic disturbance in largemouth bass. In our simulation, the weigh-in resulted in a 75% decrease in white muscle phosphocreatine, a 46% decrease in A...

Physiology and Survival of Wild Atlantic Salmon following Angling in Warm Summer Waters

Abstract Atlantic salmon Salmo salar, returning to freshwater to spawn, were angled and then terminally sampled to test the hypothesis that angling during warmer summer months (water temperatures of 20 ± 2°C) increases the magnitude of physiological disturbances in the white muscle. Angling immediately reduced white muscle ATP and phosphocreatine stores, but these high-energy phosphates were replenished within 2–4 h. Intramuscular glycogen stores were nearly depleted after angling, but unlike the response by salmon angled in the fall at 6°C, there was no glycogen resynthesis during the 4-h recovery period. Marked increases in white muscle lactate and the postexercise metabolic proton load (▵H+ m ) accompanied glycogen depletion. The time course of lactate elimination and ▵H+ m correction, however, was much slower than previously observed in fall-angled salmon. Finally, considerable delayed postangling mortality (40%) was observed in a subgroup of Atlantic salmon that were angled at 22°C. We conclude that ...

Physiological Changes in Largemouth Bass Caused by Live-Release Angling Tournaments in Southeastern Ontario

Abstract Several largemouth bass Micropterus salmoides tournaments in Ontario were visited in the summers of 1999 and 2000 to examine the physiological changes that occur in largemouth bass as a result of tournament procedures. Physiological variables were compared among tournament-caught largemouth bass, resting laboratory controls, and angled controls. The plasma cortisol and glucose concentrations and plasma osmolarity in tournament-caught largemouth bass sampled within 5 min following the weigh-in were significantly greater than those in both control groups. Tournament-caught fish also exhibited ionic disturbances that involved increases in plasma sodium and potassium concentrations, but there were no significant changes in the levels of plasma chloride. Large changes in the metabolic status of largemouth bass sampled following the weigh-in included major reductions in the muscle energy stores phosphocreatine, adenosine triphosphate, and glycogen and large increases in muscle and plasma lactate concen...

Influence of bioenergetic stress on heat shock protein gene expression in nucleated red blood cells of fish

The physiological and biochemical signals that induce stress protein (HSP) synthesis remain conjectural. In this study, we used the nucleated red blood cells from rainbow trout, Oncorhynchus mykiss, to address the interaction between energy status and HSP gene expression. Heat shock (25°C) did not significantly affect ATP levels but resulted in an increase in HSP70 mRNA. Hypoxia alone did not induce HSPtranscription in these cells despite a significant depression in ATP. Inhibition of oxidative phosphorylation with azide, in the absence of thermal stress, decreased ATP by 56% and increased lactate production by 62% but did not induce HSP gene transcription. Inhibition of oxidative phosphorylation and glycolysis with azide and iodoacetic acid respectively, decreased ATP by 79% and prevented lactate production, but did not induce either HSP70 or HSP30 gene transcription in these cells. This study demonstrates that a reduction in the cellular energy status will not induce stress protein gene transcription in rainbow trout red blood cells and may, in fact, limit induction during extreme metabolic inhibition.

Injury and Mortality Induced by Four Hook Types on Bluegill and Pumpkinseed

Abstract Tackle manufacturers have responded to concerns regarding hooking injury and mortality by attempting to design and market hooks that are less damaging to fish (e.g., circle hooks). To date, studies investigating circle hooks have been primarily restricted to large marine species. We compared the injury and short-term (72-h) mortality of bluegills Lepomis macrochirus and pumpkinseeds L. gibbosus angled using number-6 circle hooks and three other conventional hook types (aberdeen, wide-gap, and baitholder) across three water temperatures (18, 22, and 26°C). Unlike other hook types, circle hooks were never lodged in the gullet, but they were frequently lodged in the eye. Some fish captured on conventional hooks were hooked deeply in the gullet, necessitating line cutting for release. Incidences of bleeding were low using all hook types, and when not lodged in the gullet, all hooks were generally easy to remove. Anatomical hooking locations differed among small ( 145-mm) bluegills...

The distribution of carbonic anhydrase type I and II isozymes in lamprey and trout : possible co-evolution with erythrocyte chloride/bicarbonate exchange

The subcellular distribution and kinetic properties of carbonic anhydrase were examined in red blood cells and gills of the lamprey, Petromyzon marinus, a primitive agnathan, and rainbow trout, Oncorhynchus mykiss, a modern teleost, in relation to the evolution of rapid Cl−/HCO3−exchange in the membrane of red blood cells. In the lamprey, which either lacks or has minimal red cell Cl−/HCO3−exchange, there has been no compensatory incorporation of carbonic anhydrase into the membrane fraction of either the red cell or the gill. Carbonic anhydrase activity in red cells is exclusively cytoplasmic, and the single isozyme displays kinetic properties typical of the type I, slow turnover, isozyme. In the red blood cells of the trout, however, which possess high amounts of the band-3 Cl−/HCO3−exchange protein, the single carbonic anhydrase isozyme appears to be kinetically similar to the type II, fast turnover, isozyme. It thus appears that the type I isozyme present in the red blood cells of primitive aquatic vertebrates was replaced in modern teleosts by the kinetically more efficient type II isozyme only after the incorporation and expression of a significant amount of the band-3 exchange protein in the membrane of the red cell.

Cytoplasmic carbonic anhydrase isozymes in rainbow trout Oncorhynchus mykiss: comparative physiology and molecular evolution.

SUMMARY It is well established that the gills of teleost fish contain substantial levels of cytoplasmic carbonic anhydrase (CA), but it is unclear which CA isozyme(s) might be responsible for this activity. The objective of the current study was to determine if branchial CA activity in rainbow trout was the result of a general cytoplasmic CA isozyme, with kinetic properties, tissue distribution and physiological functions distinct from those of the red blood cell (rbc)-specific CA isozyme. Isolation and sequencing of a second trout cytoplasmic CA yielded a 780 bp coding region that was 76% identical with the trout rbc CA (TCAb), although the active sites differed by only 1 amino acid. Interestingly, phylogenetic analyses did not group these two isozymes closely together, suggesting that more fish species may have multiple cytoplasmic CA isozymes. In contrast to TCAb, the second cytoplasmic CA isozyme had a wide tissue distribution with high expression in the gills and brain, and lower expression in many tissues, including the red blood cells. Thus, unlike TCAb, the second isozyme lacks tissue specificity and may be expressed in the cytoplasm of all cells. For this reason, it is referred to hereafter as TCAc (trout cytoplasmic CA). The inhibitor properties of both cytoplasmic isozymes were similar (Ki acetazolamide 1.21±0.18 nmol l-1 and 1.34±0.10 nmol l-1 for TCAc and TCAb, respectively). However, the turnover of TCAb was over three times greater than that of TCAc (30.3±5.83 vs 8.90±1.95 e4 s-1, respectively), indicating that the rbc-specific CA isoform was significantly faster than the general cytoplasmic isoform. Induction of anaemia revealed differential expression of the two isozymes in the red blood cell; whereas TCAc mRNA expression was unaffected, TCAb mRNA expression was significantly increased by 30- to 60-fold in anaemic trout.

Incidence and Physiological Consequences of Decompression in Smallmouth Bass after Live-Release Angling Tournaments

Abstract Decompression can be an important problem for fish that are rapidly brought to the surface. The main objectives of this study were to (1) examine the incidence of external signs of decompression in smallmouth bass Micropterus dolomieu after live-release angling tournaments on lakes with different depths, (2) determine the physiological changes in smallmouth bass that exhibit external decompression signs, and (3) identify the best methodological approaches for evaluating this type of disturbance. Our results indicate that decompression does not cause problems for smallmouth bass when tournaments are held on relatively shallow lakes. However, when tournament anglers have access to deep water (>5 m), significant numbers of smallmouth bass may exhibit decompression signs after these events. Decompression signs include swim bladder overinflation, increased plasma lactate, and increased activity of tissue enzymes in plasma. Tournament-caught smallmouth bass exhibiting external signs of decompression al...