Jacopo Mortola | McGill University (original) (raw)

Papers by Jacopo Mortola

Research paper thumbnail of The cooling time of fertile chicken eggs at different stages of incubation

Journal of Thermal Biology, 2016

We asked whether or not the thermal characteristics of fertile avian eggs changed throughout incu... more We asked whether or not the thermal characteristics of fertile avian eggs changed throughout incubation. The cooling and warming times, expressed by the time constant τ of the egg temperature response to a rapid change in ambient temperature, were measured in fertile chicken eggs at early (E7), intermediate (E11) and late (E20) stages of embryonic development. Same measurements were conducted on eggs emptied of their content and refilled with water by various amounts. The results indicated that (1) the τ of a freshly laid egg was ~50 min; (2) τ decreased linearly with the drop in egg water volume; (3) the dry eggshell had almost no thermal resistance but its wet inner membrane contributed about one-third to the stability of egg temperature; (4) the egg constituents (yolk, albumen and embryonic tissues) and the chorioallantoic circulation had no measurable effect on τ; (5) the presence of an air pocket equivalent in volume to the air cell of fertile eggs reduced τ by about 3 min (E7), 5 min (E11) and 11 min (E20). Hence, in response to warming the egg τ at E20 was slightly shorter than at E7. In response to cooling, the egg τ at E20 was similar to, or longer than, E7 because embryonic thermogenesis (evaluated by measurements of oxygen consumption during cold) offset the reduction in τ introduced by the air cell. In conclusion, until the onset of thermogenesis the thermal behavior of a fertile egg is closely approximated by that of a water-filled egg with an air volume equivalent to the air cell. It is possible to estimate the cooling τ of avian eggs of different species from their weight and incubation time.

Research paper thumbnail of Lung viscoelasticity: implications on breathing and forced expiration

Clinical Pulmonary Medicine, 2013

Research paper thumbnail of Normoxic and hypoxic breathing pattern in the newborn grey seal

Canadian Journal of Zoology, 1989

Research paper thumbnail of Pulmonary Adaptation to Sustained Changes in Metabolic Rate

Lung Biology in Health and Disease, 2004

Research paper thumbnail of Light-dark differences in the effects of ambient temperature on gaseous metabolism in newborn rats

Journal of applied physiology (Bethesda, Md. : 1985), 2000

Body temperature (T(b)) of rat pups (7-9 days old) raised under a 12:12-h light-dark (L-D) regime... more Body temperature (T(b)) of rat pups (7-9 days old) raised under a 12:12-h light-dark (L-D) regimen (L: 0700-1900, D: 1900-0700) was consistently higher in D than in L by approximately 1.1 degrees C. We tested the hypothesis that the L-D differences in T(b) were accompanied by differences in the set point of thermoregulation. Measurements were performed on rat pups at 7-9 days after birth. O(2) consumption (VO(2)) and CO(2) production (VCO(2)) were measured with an open-flow method during air breathing, as ambient temperature (T(a)) was decreased from 40 to 15 degrees C at the constant rate of 0.5 degrees C/min. At T(a) >/=33 degrees C, VO(2) was not significantly different between L and D, whereas VCO(2) was higher in L, suggesting a greater ventilation. Over the 33 to 15 degrees C range the VO(2) values in D exceeded those in L by approximately 30%. Specifically, the difference was contributed by differences in thermogenesis at T(a) = 30 to 20 degrees C. As T(a) was decreased, t...

Research paper thumbnail of Organ growth in chicken embryos during hypoxia: Implications on organ “sparing” and “catch-up growth”

Respiratory Physiology Neurobiology, Nov 15, 2007

Research paper thumbnail of On the barometric method for measurements of ventilation, and its use in small animals

Canadian Journal of Physiology and Pharmacology, Feb 13, 2011

Research paper thumbnail of Effects of Changes in Ambient Temperature on the Hering-Bre??er Reflex of the Conscious Newborn Rat

Pediat Res, 1999

We questioned to what extent changes in temperature could affect the newborn's ventilator... more We questioned to what extent changes in temperature could affect the newborn's ventilatory inhibition provoked by lung inflation, or Hering-Breüer (HB) inflation reflex. Conscious newborn rats (3-4 d old) were studied in a double chamber airflow plethysmograph at ambient temperatures of 32 degrees C (slightly below their thermoneutrality), 24 degrees C (cold), and 36 degrees C (warm). At these ambient temperatures, the corresponding body temperatures averaged 35.4, 31.0, and 37 degrees C. The HB reflex was triggered by negative body surface pressures of 5 or 10 cm H2O, and quantified as the duration of the expiratory time during the maintained inflation, either in absolute values or in relation to the control expiratory time. In cold the HB reflex decreased to 80%, and in warm it increased to 150%, of the values measured at 32 degrees C. Oxygen consumption, measured by an open flow system, averaged 59, 47, and 29 mL x kg(-1) x min(-1) at, respectively, 24, 32, and 36 degrees C. In cold, the ventilatory response to hypoxia (10% O2) was almost absent, that to hypercapnia (5% CO2) was greater, and that to hypoxia and hypercapnia combined was less than in warm. We conclude that in newborn rats the strength of the vagal inhibition on breathing, evaluated in the form of the HB reflex, is sensitive to temperature, becoming stronger as temperature increases. One contributing factor is the temperature-induced change in metabolic rate, whereas the role of temperature-induced changes in ventilatory chemosensitivity is variable. The strong temperature-dependency of the neonatal HB reflex implies that in newborns exposed to a warm environment breathing is more susceptible to inhibitory inputs.

Research paper thumbnail of Brown adipose tissue and its uncoupling protein in chronically hypoxic rats

Clinical Science, Nov 1, 1997

1. Hypoxia is known to decrease thermogenesis. We set out to determine whether this is accompanie... more 1. Hypoxia is known to decrease thermogenesis. We set out to determine whether this is accompanied by alterations in the brown adipose tissue, which is a major source of non-shivering thermogenesis. 2. Measurements were performed on 25- and 64-day-old rats, after 4 days of hypoxia (10% inspired O2), and on approximately 3.5-month-old rats in hypobaric hypoxia since birth, at an ambient temperature of 25 degrees C. 3. All hypoxic rats had higher haematocrit and lower body mass than corresponding controls. 4. In the 25-day-old rats, hypoxia had minimal and non significant effects on brown adipose tissue mass, proteins and DNA concentration. The content of the mitochondrial uncoupling protein thermogenin, evaluated by immunoblot after electrophoretic separation, relative to the cytoskeleton actin (UCP/Act), was not significantly altered. 5. In 25-day-old rats exposed for 4 days to cold (ambient temperature = 7-9 degrees C), brown adipose tissue was hyperplastic, with increased UCP/Act; hypoxia did not appreciably alter the response to cold. 6. In the 2-month-old rats, after 4 days of hypoxia UCP/Act was reduced to about 40% of control. 7. In the 3.5-month-old rats maintained in hypoxia since birth, brown adipose tissue mass was reduced in proportion to body mass, with little effect on total proteins and DNA; UCP/Act was decreased to about 50% of control. 8. We conclude that chronic hypoxia had a minimal effect on brown adipose tissue total proteins and DNA content. However, the uncoupling protein content can be greatly reduced, depending upon age and duration of hypoxia.

Research paper thumbnail of Effect of 2,4-dinitrophenol on the hypometabolic response to hypoxia of conscious adult rats

Journal of Applied Physiology, Aug 1, 1997

Research paper thumbnail of Light-dark differences in the effects of ambient temperature on gaseous metabolism in newborn rats

Journal of Applied Physiology, May 1, 2000

Research paper thumbnail of Thermogenic and Vocalization Responses to Cold in the Chicken Hatchling During Normoxia and Hypoxia

Behavioral Neuroscience, Feb 1, 2011

Research paper thumbnail of Thermogenesis in newborn rats after prenatal or postnatal hypoxia

Journal of Applied Physiology, Jul 1, 1998

Research paper thumbnail of Monitoring breathing in avian embryos and hatchlings by the barometric technique

Respiratory Physiology Neurobiology, Nov 15, 2007

Research paper thumbnail of Interaction between metabolism and ventilation: effects of respiratory gases and temperature

Lung Biology in Health and Disease, 1995

... Función respiratoria. ; Intercambio gaseoso. ; Control respiratorio. ; Metabolismo. ; Explora... more ... Función respiratoria. ; Intercambio gaseoso. ; Control respiratorio. ; Metabolismo. ; Exploración. ; Fisiología. ; Hombre. ; Oxígeno. ; Aparato respiratorio. ; Localisation / Location. INIST-CNRS, Cote INIST : 19715, 35400004163615.0230. Nº notice refdoc (ud4) : 4264376. ...

Research paper thumbnail of Hypoxia and circadian patterns

Respiratory Physiology Neurobiology, Sep 30, 2007

Research paper thumbnail of Effects of hypoxia and hypercapnia on the Hering-Breuer reflex on the conscious newborn rat

Journal of Applied Physiology, 1995

We asked whether hypoxia and hypercapnia, singly or combined, affect the lung volume-dependent ve... more We asked whether hypoxia and hypercapnia, singly or combined, affect the lung volume-dependent ventilatory inhibition [Hering-Breuer (HB) reflex] in newborn rats. Conscious rats 2, 5, and 8 days old were breathing in a flow plethysmograph. Mean lung volume was increased by applying a negative body surface pressure of 6 or 12 cmH2O. HB reflex was quantified as the inhibitory ratio (IR) of the apnea during the inflation expiratory time (TEinfl) to the control expiratory time (TEc), i.e., IR = TEinfl/TEc. In normoxia-normocapnia (control), IR with 6 cmH2O was approximately 8-12 at all ages and approximately doubled with inflation at 12 cmH2O. In hypoxia (HPX; 10% O2) or hypercapnia (HPCN; 3% CO2), IR decreased at 8 days, whereas it did not differ from the control value at 2 and 5 days. In HPX + HPCN, IR decreased at all ages. In HPX (at both 6- and 12-cmH2O inflations), in HPCN (6 cmH2O), or in HPX + HPCN (6 and 12 cmH2O), IR decreased significantly more at 8 days than at 2 days. Metabolic rate, simultaneously measured, decreased during HPX or HPX + HPCN by a similar amount at all ages. The ventilatory response to HPX or to HPCN was significantly more pronounced at 8 days than at 2 days. We conclude that, during the early postnatal development of the rat, HPX or HPCN, singly or combined, reduces the HB reflex inhibition in the oldest pups, with minimal or no effects in the youngest. These developmental differences cannot be explained by differences in metabolic drive on ventilation but are contributed to by differences in chemosensitivity.

Research paper thumbnail of Development of the chick embryo: effects of eggs mass

Respiration Physiology, 1988

Research paper thumbnail of Thermographic analysis of the radiant heat of chicken and duck eggs in relation to the embryo's oxygen consumption

Journal of Thermal Biology, Jan 9, 2015

We measured the metabolic component of heat (Hmet) of avian eggs by thermography.In the first hal... more We measured the metabolic component of heat (Hmet) of avian eggs by thermography.In the first half of incubation Hmet was not significant.Later in incubation Hmet was significant and correlated with the embryos VO2.Thermography can verify the progression of embryo's incubation and estimate its VO2.In eggs, the metabolic activities of the developing embryo produce heat (H) that is dissipated in various forms, including radiation. Given that much of the total heat radiated by an egg (Htot) is heat acquired passively, we asked whether it was possible to detect the fraction produced metabolically (Hmetab) and the extent of its correlation with the embryo's metabolic rate. In chicken and duck eggs at various incubation ages, under standardized experimental conditions of heat conduction and convection, Hmetab was measured by thermography as the difference in Htot between fertile and sterile eggs. Then, Hmetab was correlated to the embryo's oxygen consumption (V̇O2), measured by an open-circuit methodology. Heat loss by water evaporation was found to be less than 3% of the total. During the first half of incubation Hmetab was too small to be significantly separated from Htot. In the second half of incubation Hmetab was significant, represented 30–50% of the total energy consumed and correlated linearly with V̇O2 for a good fraction of incubation. We conclude that under standardized conditions of heat conduction and convection, in the second half of incubation thermography offers a simple tool not only to verify the progression of the embryo's incubation but also to estimate its metabolic rate.

Research paper thumbnail of AN INTEGRATIVE APPROACH TO ANIMAL LIFE: Comparative Developmental Physiology - Contributions, Tools, and Trends

Journal of Experimental Biology, Feb 1, 2007

Research paper thumbnail of The cooling time of fertile chicken eggs at different stages of incubation

Journal of Thermal Biology, 2016

We asked whether or not the thermal characteristics of fertile avian eggs changed throughout incu... more We asked whether or not the thermal characteristics of fertile avian eggs changed throughout incubation. The cooling and warming times, expressed by the time constant τ of the egg temperature response to a rapid change in ambient temperature, were measured in fertile chicken eggs at early (E7), intermediate (E11) and late (E20) stages of embryonic development. Same measurements were conducted on eggs emptied of their content and refilled with water by various amounts. The results indicated that (1) the τ of a freshly laid egg was ~50 min; (2) τ decreased linearly with the drop in egg water volume; (3) the dry eggshell had almost no thermal resistance but its wet inner membrane contributed about one-third to the stability of egg temperature; (4) the egg constituents (yolk, albumen and embryonic tissues) and the chorioallantoic circulation had no measurable effect on τ; (5) the presence of an air pocket equivalent in volume to the air cell of fertile eggs reduced τ by about 3 min (E7), 5 min (E11) and 11 min (E20). Hence, in response to warming the egg τ at E20 was slightly shorter than at E7. In response to cooling, the egg τ at E20 was similar to, or longer than, E7 because embryonic thermogenesis (evaluated by measurements of oxygen consumption during cold) offset the reduction in τ introduced by the air cell. In conclusion, until the onset of thermogenesis the thermal behavior of a fertile egg is closely approximated by that of a water-filled egg with an air volume equivalent to the air cell. It is possible to estimate the cooling τ of avian eggs of different species from their weight and incubation time.

Research paper thumbnail of Lung viscoelasticity: implications on breathing and forced expiration

Clinical Pulmonary Medicine, 2013

Research paper thumbnail of Normoxic and hypoxic breathing pattern in the newborn grey seal

Canadian Journal of Zoology, 1989

Research paper thumbnail of Pulmonary Adaptation to Sustained Changes in Metabolic Rate

Lung Biology in Health and Disease, 2004

Research paper thumbnail of Light-dark differences in the effects of ambient temperature on gaseous metabolism in newborn rats

Journal of applied physiology (Bethesda, Md. : 1985), 2000

Body temperature (T(b)) of rat pups (7-9 days old) raised under a 12:12-h light-dark (L-D) regime... more Body temperature (T(b)) of rat pups (7-9 days old) raised under a 12:12-h light-dark (L-D) regimen (L: 0700-1900, D: 1900-0700) was consistently higher in D than in L by approximately 1.1 degrees C. We tested the hypothesis that the L-D differences in T(b) were accompanied by differences in the set point of thermoregulation. Measurements were performed on rat pups at 7-9 days after birth. O(2) consumption (VO(2)) and CO(2) production (VCO(2)) were measured with an open-flow method during air breathing, as ambient temperature (T(a)) was decreased from 40 to 15 degrees C at the constant rate of 0.5 degrees C/min. At T(a) >/=33 degrees C, VO(2) was not significantly different between L and D, whereas VCO(2) was higher in L, suggesting a greater ventilation. Over the 33 to 15 degrees C range the VO(2) values in D exceeded those in L by approximately 30%. Specifically, the difference was contributed by differences in thermogenesis at T(a) = 30 to 20 degrees C. As T(a) was decreased, t...

Research paper thumbnail of Organ growth in chicken embryos during hypoxia: Implications on organ “sparing” and “catch-up growth”

Respiratory Physiology Neurobiology, Nov 15, 2007

Research paper thumbnail of On the barometric method for measurements of ventilation, and its use in small animals

Canadian Journal of Physiology and Pharmacology, Feb 13, 2011

Research paper thumbnail of Effects of Changes in Ambient Temperature on the Hering-Bre??er Reflex of the Conscious Newborn Rat

Pediat Res, 1999

We questioned to what extent changes in temperature could affect the newborn's ventilator... more We questioned to what extent changes in temperature could affect the newborn's ventilatory inhibition provoked by lung inflation, or Hering-Breüer (HB) inflation reflex. Conscious newborn rats (3-4 d old) were studied in a double chamber airflow plethysmograph at ambient temperatures of 32 degrees C (slightly below their thermoneutrality), 24 degrees C (cold), and 36 degrees C (warm). At these ambient temperatures, the corresponding body temperatures averaged 35.4, 31.0, and 37 degrees C. The HB reflex was triggered by negative body surface pressures of 5 or 10 cm H2O, and quantified as the duration of the expiratory time during the maintained inflation, either in absolute values or in relation to the control expiratory time. In cold the HB reflex decreased to 80%, and in warm it increased to 150%, of the values measured at 32 degrees C. Oxygen consumption, measured by an open flow system, averaged 59, 47, and 29 mL x kg(-1) x min(-1) at, respectively, 24, 32, and 36 degrees C. In cold, the ventilatory response to hypoxia (10% O2) was almost absent, that to hypercapnia (5% CO2) was greater, and that to hypoxia and hypercapnia combined was less than in warm. We conclude that in newborn rats the strength of the vagal inhibition on breathing, evaluated in the form of the HB reflex, is sensitive to temperature, becoming stronger as temperature increases. One contributing factor is the temperature-induced change in metabolic rate, whereas the role of temperature-induced changes in ventilatory chemosensitivity is variable. The strong temperature-dependency of the neonatal HB reflex implies that in newborns exposed to a warm environment breathing is more susceptible to inhibitory inputs.

Research paper thumbnail of Brown adipose tissue and its uncoupling protein in chronically hypoxic rats

Clinical Science, Nov 1, 1997

1. Hypoxia is known to decrease thermogenesis. We set out to determine whether this is accompanie... more 1. Hypoxia is known to decrease thermogenesis. We set out to determine whether this is accompanied by alterations in the brown adipose tissue, which is a major source of non-shivering thermogenesis. 2. Measurements were performed on 25- and 64-day-old rats, after 4 days of hypoxia (10% inspired O2), and on approximately 3.5-month-old rats in hypobaric hypoxia since birth, at an ambient temperature of 25 degrees C. 3. All hypoxic rats had higher haematocrit and lower body mass than corresponding controls. 4. In the 25-day-old rats, hypoxia had minimal and non significant effects on brown adipose tissue mass, proteins and DNA concentration. The content of the mitochondrial uncoupling protein thermogenin, evaluated by immunoblot after electrophoretic separation, relative to the cytoskeleton actin (UCP/Act), was not significantly altered. 5. In 25-day-old rats exposed for 4 days to cold (ambient temperature = 7-9 degrees C), brown adipose tissue was hyperplastic, with increased UCP/Act; hypoxia did not appreciably alter the response to cold. 6. In the 2-month-old rats, after 4 days of hypoxia UCP/Act was reduced to about 40% of control. 7. In the 3.5-month-old rats maintained in hypoxia since birth, brown adipose tissue mass was reduced in proportion to body mass, with little effect on total proteins and DNA; UCP/Act was decreased to about 50% of control. 8. We conclude that chronic hypoxia had a minimal effect on brown adipose tissue total proteins and DNA content. However, the uncoupling protein content can be greatly reduced, depending upon age and duration of hypoxia.

Research paper thumbnail of Effect of 2,4-dinitrophenol on the hypometabolic response to hypoxia of conscious adult rats

Journal of Applied Physiology, Aug 1, 1997

Research paper thumbnail of Light-dark differences in the effects of ambient temperature on gaseous metabolism in newborn rats

Journal of Applied Physiology, May 1, 2000

Research paper thumbnail of Thermogenic and Vocalization Responses to Cold in the Chicken Hatchling During Normoxia and Hypoxia

Behavioral Neuroscience, Feb 1, 2011

Research paper thumbnail of Thermogenesis in newborn rats after prenatal or postnatal hypoxia

Journal of Applied Physiology, Jul 1, 1998

Research paper thumbnail of Monitoring breathing in avian embryos and hatchlings by the barometric technique

Respiratory Physiology Neurobiology, Nov 15, 2007

Research paper thumbnail of Interaction between metabolism and ventilation: effects of respiratory gases and temperature

Lung Biology in Health and Disease, 1995

... Función respiratoria. ; Intercambio gaseoso. ; Control respiratorio. ; Metabolismo. ; Explora... more ... Función respiratoria. ; Intercambio gaseoso. ; Control respiratorio. ; Metabolismo. ; Exploración. ; Fisiología. ; Hombre. ; Oxígeno. ; Aparato respiratorio. ; Localisation / Location. INIST-CNRS, Cote INIST : 19715, 35400004163615.0230. Nº notice refdoc (ud4) : 4264376. ...

Research paper thumbnail of Hypoxia and circadian patterns

Respiratory Physiology Neurobiology, Sep 30, 2007

Research paper thumbnail of Effects of hypoxia and hypercapnia on the Hering-Breuer reflex on the conscious newborn rat

Journal of Applied Physiology, 1995

We asked whether hypoxia and hypercapnia, singly or combined, affect the lung volume-dependent ve... more We asked whether hypoxia and hypercapnia, singly or combined, affect the lung volume-dependent ventilatory inhibition [Hering-Breuer (HB) reflex] in newborn rats. Conscious rats 2, 5, and 8 days old were breathing in a flow plethysmograph. Mean lung volume was increased by applying a negative body surface pressure of 6 or 12 cmH2O. HB reflex was quantified as the inhibitory ratio (IR) of the apnea during the inflation expiratory time (TEinfl) to the control expiratory time (TEc), i.e., IR = TEinfl/TEc. In normoxia-normocapnia (control), IR with 6 cmH2O was approximately 8-12 at all ages and approximately doubled with inflation at 12 cmH2O. In hypoxia (HPX; 10% O2) or hypercapnia (HPCN; 3% CO2), IR decreased at 8 days, whereas it did not differ from the control value at 2 and 5 days. In HPX + HPCN, IR decreased at all ages. In HPX (at both 6- and 12-cmH2O inflations), in HPCN (6 cmH2O), or in HPX + HPCN (6 and 12 cmH2O), IR decreased significantly more at 8 days than at 2 days. Metabolic rate, simultaneously measured, decreased during HPX or HPX + HPCN by a similar amount at all ages. The ventilatory response to HPX or to HPCN was significantly more pronounced at 8 days than at 2 days. We conclude that, during the early postnatal development of the rat, HPX or HPCN, singly or combined, reduces the HB reflex inhibition in the oldest pups, with minimal or no effects in the youngest. These developmental differences cannot be explained by differences in metabolic drive on ventilation but are contributed to by differences in chemosensitivity.

Research paper thumbnail of Development of the chick embryo: effects of eggs mass

Respiration Physiology, 1988

Research paper thumbnail of Thermographic analysis of the radiant heat of chicken and duck eggs in relation to the embryo's oxygen consumption

Journal of Thermal Biology, Jan 9, 2015

We measured the metabolic component of heat (Hmet) of avian eggs by thermography.In the first hal... more We measured the metabolic component of heat (Hmet) of avian eggs by thermography.In the first half of incubation Hmet was not significant.Later in incubation Hmet was significant and correlated with the embryos VO2.Thermography can verify the progression of embryo's incubation and estimate its VO2.In eggs, the metabolic activities of the developing embryo produce heat (H) that is dissipated in various forms, including radiation. Given that much of the total heat radiated by an egg (Htot) is heat acquired passively, we asked whether it was possible to detect the fraction produced metabolically (Hmetab) and the extent of its correlation with the embryo's metabolic rate. In chicken and duck eggs at various incubation ages, under standardized experimental conditions of heat conduction and convection, Hmetab was measured by thermography as the difference in Htot between fertile and sterile eggs. Then, Hmetab was correlated to the embryo's oxygen consumption (V̇O2), measured by an open-circuit methodology. Heat loss by water evaporation was found to be less than 3% of the total. During the first half of incubation Hmetab was too small to be significantly separated from Htot. In the second half of incubation Hmetab was significant, represented 30–50% of the total energy consumed and correlated linearly with V̇O2 for a good fraction of incubation. We conclude that under standardized conditions of heat conduction and convection, in the second half of incubation thermography offers a simple tool not only to verify the progression of the embryo's incubation but also to estimate its metabolic rate.

Research paper thumbnail of AN INTEGRATIVE APPROACH TO ANIMAL LIFE: Comparative Developmental Physiology - Contributions, Tools, and Trends

Journal of Experimental Biology, Feb 1, 2007