Biomedical subjects

B Bagatto

Publications and source records attributed to B Bagatto.

5 recordsLinked to original sources

PubMed2001

Effects of temperature and aquatic P(O2) on the physiology and behaviour of Apalone ferox and Chrysemys picta.

Softshell turtles overwinter in the same bodies of water as some emydids, but their reduced shell and increased non-pulmonary gas exchange may contribute to a different mechanism of overwintering. The dynamics of bimodal respiration, diving behaviour and blood acid-base status in Apalone ferox and Chrysemys picta were investigated under two different temperatures combined with three different aquatic P(O2) levels. Both species obtained oxygen through pulmonary and non-pulmonary routes. Apalone ferox obtained more oxygen through non-pulmonary routes and increased its non-pulmonary V(O2) in response to both higher aquatic P(O2) and lower temperatures. Both species increased pulmonary V(O2) in response to higher temperatures. As a consequence of the greater reliance of A. ferox on pulmonary V(O2), warmer temperatures caused plasma P(CO2) and [HCO(3)(-1)] values to increase significantly compared with C. picta. Apalone ferox, which is efficient at bimodal respiration, displayed a high degree of plasticity with respect to both its respiratory and acid-base profiles, behaving more like an aquatic air-breathing fish in bimodal respiration at low temperature and more like a terrestrial air-breather at high temperature. Chrysemys picta, which is poor at bimodal respiration, was highly dependent on aerial gas exchange at both temperatures. Aquatic P(O2) did not change any of the behavioural variables measured. At warm temperatures, A. ferox met O(2) demands by increasing the rate of lung ventilation, which resulted in a significantly greater number of breathing bouts per hour and breaths per emersion period. However, the number of breaths per bout was not affected by temperature. As temperatures decreased, A. ferox utilized its non-pulmonary respiration ability and significantly increased its dive duration. Apalone ferox became less active at colder temperatures by significantly increasing the duration of inactive periods (from 4 to 18 min) and by significantly decreasing the frequency of activity bursts. Chrysemys picta also met the higher gas-exchange demands associated with increased temperature by increasing the rate of lung ventilation; however, this increase was not as large as that measured in A. ferox. Chrysemys picta displayed multiple rhythmic breaths per bout. These results indicate that, unlike aquatic P(O2), temperature is an important factor in the regulation of diving and ventilatory behaviour in turtles. The species responded to temperature in dissimilar ways because of differences in their bimodal respiration ability.

Acid-Base Equilibrium↗

PubMed2001

Growth and metabolism of larval zebrafish: effects of swim training.

Larval zebrafish (Danio rerio) of three different age classes ('yolk-sac' larvae, 96 h; 'swim-up' larvae, 9 days old; and 'free-swimming' larvae, 21 days old) were trained for 2, 6 and 11 days, respectively, to swim at 0 body lengths per second (BL s(-1)), 2 BL s(-1) and 5 BL s(-1). Survival was significantly diminished in larvae trained at 5 BL s(-1) compared to controls (0 BL s(-1)). Although training produced no significant differences in mass and length, the youngest larvae absorbed their yolk at a faster rate during training. Routine oxygen consumption ((MO(2)r)) and mass-specific routine oxygen consumption ((MO(2)r,m)) were not significantly affected by chronic training in the yolk-sac larvae and swim-up larvae. However, trained free-swimming larvae had a significantly higher (MO(2)r) (after 11 days of training) and (MO(2)r,m) (after 8 and 11 days of training) compared to control larvae. Trained free-swimming larvae consumed significantly less oxygen during swimming compared to control larvae, as measured by closed-system respirometry. Trained yolk-sac larvae exposed to increasing hypoxia levels were more effective O(2) regulators. Additionally, training enhanced survival during exposure to extreme hypoxia in all age groups. Thus, physiological acclimation to chronic swimming occurs in the earliest stages of life in the zebrafish.

Adaptation, Physiological↗

PubMed2000

Bimodal respiration and ventilatory behavior in two species of central American turtles: effects of forced submergence.

Respiratory gas exchange in both air and water was measured at rest and during recovery from forced submergence in the giant Mexican musk turtle (Staurotypus triporcatus) and the white-lipped mud turtle (Kinosternon leucostomum). Diving and ventilatory behavior were also measured in unrestrained animals of each species. Despite large differences in cutaneous surface area, both species exhibited an aquatic V(O(2)) and V(CO(2)) of approximately 16 and 45%, respectively, with the remainder explained by aerial gas exchange. Aquatic V(O(2)) and V(CO(2)) did not significantly change during forced submergence or during the recovery period. Aerial V(O(2)) and V(CO(2)), however, profoundly increased after forced submergence in both species and were not significantly different from resting values until approximately 60 min following the treatment. At rest, K. leucostomum took significantly more breaths per breathing bout than S. triporcatus. This inherent ventilation pattern in each species remained unaltered following forced submergence. Cutaneous surface area, therefore, remains a minor component for these two species which rely heavily on pulmonary gas exchange to recover from forced submergence.

Animals↗

PubMed2000

Physiological variability in neonatal armadillo quadruplets: within- and between-litter differences.

The role of genetics on neonatal physiological variability was examined in the nine-banded armadillo (Dasypus novemcinctus). Since armadillos give birth to only monozygous quadruplets, the genetic variation within litters is essentially zero. Quadruplets born in captivity were isolated and weighed within 8 h of birth. Oxygen consumption (V.(O2)) was measured in resting neonates by flow-through respirometry, heart rate obtained from an electrocardiogram and ventilation was measured by impedance techniques. Following the measurements, neonates were returned to the mother. Measurements were repeated at 4 and 8 days after birth. Mean heart rate significantly increased from 132 beats min(-1) on the day of birth to 169 beats min(-1) on day 8. Mean ventilation rate significantly decreased from 81 breaths min(-1) on the day of birth to 54 breaths min(-1) on day 8. During this same developmental period, mean mass significantly increased from 100 g to 129 g, and mean mass-specific oxygen consumption significantly decreased from 32.2 ml O(2)kg(-1)min(-1) to 28.6 ml O(2)kg(-1) min(-1). For all variables measured, within-litter variability was always significantly less than between-litter variability, confirming a 'sibling effect' that we attribute to the genetic components determining physiological characters.

Aging↗

PubMed1999

Exercise and forced submergence in the pond slider (Trachemys scripta) and softshell turtle (Apalone ferox): influence on bimodal gas exchange, diving behaviour and blood acid-base status

The dynamics of bimodal respiration, diving behaviour and blood acid-base status in the softshell turtle Trachemys scripta and the pond slider Apalone ferox were investigated at rest and under conditions of stress induced by exercise and forced submergence. During periods of forced submergence, only A. ferox doubled its aquatic gas exchange rate. Both A. ferox and T. scripta increased their aerial gas exchange profoundly following exercise and forced submergence, a pattern indicative of increased anaerobic respiration. Emersion duration increased significantly in A. ferox following forced submergence, and mean apnoeic time decreased significantly in A. ferox following exercise, indicating that a larger proportion of time at the surface was spent ventilating. Also, A. ferox maintained a one-breath breathing bout regardless of treatment. Submergence produced a respiratory acidosis in the plasma of approximately 0.2 pH units in magnitude in T. scripta and a mixed respiratory/metabolic acidosis of 0.4 pH units in A. ferox. Exercise induced an acidosis of 0.2 pH units of primarily metabolic origin in both species. Intra-erythrocyte pH was also reduced in both species in response to submergence and exercise. Both intracellular and extracellular acidoses were more severe and longer lasting in A. ferox after each treatment. Plasma [HCO3-] decreased by 25 % in both species following exercise, but only in A. ferox following submergence. Plasma lactate concentrations increased by equal amounts in each species following exercise; however, they returned to resting concentrations sooner in T. scripta than in A. ferox. A. ferox had significantly higher lactate levels than T. scripta following forced submergence as well as a slower recovery time. A. ferox, which is normally a good bimodal gas exchanger at rest, utilizes aerial respiration to a greater extent when under respiratory and/or metabolic stress. T. scripta, although almost entirely dependent on aerial respiration, is physiologically better able to deal with the respiratory and metabolic stresses associated with both forced submergence and exercise.

Journal Article↗