Los hallazgos recientes muestran que el calentamiento global puede causar la extinción y el cambi... more Los hallazgos recientes muestran que el calentamiento global puede causar la extinción y el cambio en la distribución espacial de diversas especies de reptiles. Se ha propuesto, que en respuesta, los lacertilios podrían migrar en un gradiente altitudinal, pero no se considera a la hipóxia (escasez de oxígeno) como un factor que podría limitar la migración. Aquí discutimos las posibles adecuaciones en ciertas características morfo-fisiológicas que podrían permitir a los ectotermos migrar sobre un gradiente altitudinal aún con los efectos negativos de la hipóxia. Con esto podemos comenzar a estudiar a profundidad la vulnerabilidad de los ectotermos ante el calentamiento global que depende no solo de su biología térmica, sino también de su fisiología.
Body temperature is important in determining individual performance in ectotherms such as lizards... more Body temperature is important in determining individual performance in ectotherms such as lizards. Environmental temperature decreases with increasing altitude, but nevertheless many lizards inhabit high-altitude environments. The ‘thermal melanism hypothesis’ proposes that a dark dorsal coloration enables darker individuals to heat up faster because they absorb more solar radiation and thus being darker may be advantageous in cold habitats. The aim of the present study is to evaluate how heating rate, cooling rate and net heat gain vary with body size and dorsal skin coloration in Sceloporus grammicus lizards along an altitudinal gradient. We measured these traits multiple times in the same individuals with a radiation heat source and spectrophotometry under laboratory conditions. Our results showed that S. grammicus lizards are smaller and darker at high elevations than at low elevations. In addition, the smallest and darkest lizards showed the greatest heating rate and net heat g...
High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. O... more High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. One common mechanism is through increased values of blood traits such as erythrocyte count, hematocrit, and hemoglobin concentration. However, a positive relationship between altitude and blood traits is not observed in all high-altitude systems. To understand how organisms adapt to high altitudes, it is important to document physiological patterns related to hypoxia gradients from a greater variety of species. Here, we present an extensive hematological description for three populations of Sceloporus grammicus living at 2,500, 3,400, and 4,300 m. We did not find a linear increase with altitude for any of the blood traits we measured. Instead, we found nonlinear relationships between altitude and the blood traits erythrocyte number, erythrocyte size, hematocrit, and hemoglobin concentration. Erythrocyte number and hematocrit leveled off as altitude increased, whereas hemoglobin concentration and erythrocyte size were highest at intermediate altitude. Additionally, lizards from our three study populations are similar in blood pH, serum electrolytes, glucose, and lactate. Given that the highest-altitude population did not show the highest levels of the variables we measured, we suggest these lizards may be using different adaptations to cope with hypoxia than lizards at low or intermediate altitudes. We discuss future directions that research could take to investigate such potential adaptations.
La incontinencia urinaria es definida por la International Continence Society como la queja ante ... more La incontinencia urinaria es definida por la International Continence Society como la queja ante cualquier salida involuntaria de orina. Se calcula que en el mundo alrededor del 30% de mujeres mayores de 60 años la padecen. En México no se han realizado estudios sistemáticos sobre la prevalencia de la incontinencia urinaria, pero se estima que entre el 15 y el 30% de mujeres mayores de 60 años la padecen. En el tratamiento de esta patología es importante conocer el sustrato anatómico y fisiológico de los procesos expulsivos femeninos contenidos en la región pélvica. En la presente revisión se describe los principales factores que desencadenan la incontinencia urinaria, los tratamientos para su control y la importancia de generar modelos animales que permitan conocer los factores asociados a su desarrollo.
The collared peccary (Pecari tajacu) is an ungulate animal and little is known about its reproduc... more The collared peccary (Pecari tajacu) is an ungulate animal and little is known about its reproductive physiology. In this work, an anatomic description of the urogenital apparatus (ua) was performed. Eight female and five male collar peccaries were anesthetized and perfused with McKormik solution. The ua was dissected out and its structures were further described. The ua of the collared peccary was found to be typical of mammals and it shared many features with the ua of the pig. Thus far,this is the first report to describe structures such as the urogenital sinus, vestibular glands and vulva-associated striated muscle in females. It is also the first description of the male ua of the collared peccary in which several exclusive characteristics were found.
This study examined changes in certain hematological parameters in a reptilian model naturally ex... more This study examined changes in certain hematological parameters in a reptilian model naturally exposed to altitude-associated hypoxia. Four populations of the Mexican lizard Sceloporus torquatus Wiegmann, 1828 (Wiegmann’s Torquate Lizard) from different altitudes were sampled to evaluate erythrocyte count (Erc), hematocrit (Hct), mean corpuscular hemoglobin concentration (MCHC), and erythrocyte size (Ers). Blood was also assayed to determine hemoglobin ([Hb]), glucose, lactate, and electrolyte concentrations. Erc was performed using a Neubauer hemocytometer. Hct was calculated as percentage of packed cell volume by centrifuging blood samples. [Hb] was determined using a Bausch and Lomb Spectronic colorimeter. MCHC was calculated with the formula 100 × [Hb]/Hct. Ers was calculated from blood smear microphotographs analyzed with the Sigma Scan Pro software. Values of serum electrolytes (sodium (Na+), potassium (K+), and calcium (Ca2+)), pH, glucose, and lactate from blood samples were...
Temporal and coordinated activation of pelvic- (pubococcygeous) and perineal- (bulbospongiosus an... more Temporal and coordinated activation of pelvic- (pubococcygeous) and perineal- (bulbospongiosus and ischiocavernosus) striated muscles occurs during micturition in female rabbits. We have hypothesized that the coordinated activation of pelvic and perineal muscles is modified during the micturition of young multiparous rabbits. Young virgin and multiparous female chinchilla rabbits were used to simultaneously record cystometrograms and electromyograms of the pubococcygeous, ischocavernosus, and bulbospongiosus muscles. Bladder function was assessed using standard urodynamic variables. The temporal coordination of pelvic- and perineal-striated muscle activity was changed in multiparous rabbits. The cystometrogram recordings were different than those obtained from virgin rabbits, as seen in alterations of the threshold volume, the residual volume, the voiding duration, and the maximum pressure. In rabbits, we find that multiparity causes uncoordinated activity of pubococcygeous, ischiocavernosus, and bulbospongiosus muscles and modifies the urodynamics.
To determine the motor basis of urine expulsion the activity of the pelvic (pubococcygeus) and pe... more To determine the motor basis of urine expulsion the activity of the pelvic (pubococcygeus) and perineal (bulbospongiosus and ischiocavernosus) muscles was recorded during micturition in anesthetized female rabbits. Virgin female chinchilla rabbits were used for simultaneously recording cystometrograms and electromyograms of the pubococcygeus, ischiocavernosus and bulbospongiosus muscles. The particular contribution of each muscle during micturition was analyzed in another set of experiments in which each was inactivated by bilateral lidocaine injection. Bladder function was assessed using standard urodynamic parameters. Cystometrography showed that micturition comprises 2 phases, that is storage and voiding phases. During the latter phase no high frequency oscillations were recorded. On simultaneous electromyography recordings a temporal, coordinated activation of pelvic (pubococcygeus) and perineal (bulbospongiosus and ischiocavernosus) muscles was observed. During specific blockade of each muscle some modifications in urodynamic parameters were found. Our findings indicate a specific role for the pelvic and perineal muscles during feminine micturition.
ABSTRACT Small or isolated populations are highly susceptible to stochastic events. They are pron... more ABSTRACT Small or isolated populations are highly susceptible to stochastic events. They are prone and vulnerable to random demographic or environmental fluctuations that could lead to extinction due to the loss of alleles through genetic drift and increased inbreeding. We studied Ambystoma leorae an endemic and critically threatened species. We analyzed the genetic diversity and structure, effective population size, presence of bottlenecks and inbreeding coefficient of 96 individuals based on nine microsatellite loci. We found high levels of genetic diversity expressed as heterozygosity (Ho = 0.804, He = 0.613, He* = 0.626 and HNei = 0.622). The population presents few alleles (4–9 per locus) and genotypes (3–14 per locus) compared with other mole salamanders species. We identified three genetically differentiated subpopulations with a significant level of genetic structure (FST = 0.021, RST = 0.044 y Dest = 0.010, 95 % CI). We also detected a reduction signal in population size and evidence of a genetic bottleneck (M = 0.367). The effective population size is small (Ne = 45.2), but similar to another mole salamanders with restricted distributions or with recently fragmented habitat. The inbreeding coefficient levels detected are low (FIS = −0.619–0.102) as is gene flow. Despite, high levels of genetic diversity A. leorae is critically endangered because it is a small isolated population.
The composition and energetic content of puma (Puma concolor) diet in Sierra Nanchititla Natural ... more The composition and energetic content of puma (Puma concolor) diet in Sierra Nanchititla Natural Reserve (SNNR), Mexico, were determined. We collected 183 scats, where 27 components were identified by occurrence (88.07% mammals). The puma's diet was mainly composed of armadillo (Dasypus novemcinctus, 40.33%), white-nosed coati (Nasua narica, 11.93%) and white-tailed deer (Odocoileus virginianus, 6.17%). Energetic analysis of prey indicates that the puma prefers those with higher energetic content (kcal/kg). The prey with the most energetic contribution is armadillo (2398.70 kcal/kg), followed by white-nosed coati (2225.25 kcal/kg) and finally white-tailed deer (2165.52 kcal/kg). The differences in energetic content between prey species were statistically significant. The number of individuals killed/year on average to support a puma was 51 armadillos, 16 white-tailed deer and 7 white-nosed coatis. The results indicate a greater consumption of prey that provide more kilocalories ...
Los hallazgos recientes muestran que el calentamiento global puede causar la extinción y el cambi... more Los hallazgos recientes muestran que el calentamiento global puede causar la extinción y el cambio en la distribución espacial de diversas especies de reptiles. Se ha propuesto, que en respuesta, los lacertilios podrían migrar en un gradiente altitudinal, pero no se considera a la hipóxia (escasez de oxígeno) como un factor que podría limitar la migración. Aquí discutimos las posibles adecuaciones en ciertas características morfo-fisiológicas que podrían permitir a los ectotermos migrar sobre un gradiente altitudinal aún con los efectos negativos de la hipóxia. Con esto podemos comenzar a estudiar a profundidad la vulnerabilidad de los ectotermos ante el calentamiento global que depende no solo de su biología térmica, sino también de su fisiología.
Body temperature is important in determining individual performance in ectotherms such as lizards... more Body temperature is important in determining individual performance in ectotherms such as lizards. Environmental temperature decreases with increasing altitude, but nevertheless many lizards inhabit high-altitude environments. The ‘thermal melanism hypothesis’ proposes that a dark dorsal coloration enables darker individuals to heat up faster because they absorb more solar radiation and thus being darker may be advantageous in cold habitats. The aim of the present study is to evaluate how heating rate, cooling rate and net heat gain vary with body size and dorsal skin coloration in Sceloporus grammicus lizards along an altitudinal gradient. We measured these traits multiple times in the same individuals with a radiation heat source and spectrophotometry under laboratory conditions. Our results showed that S. grammicus lizards are smaller and darker at high elevations than at low elevations. In addition, the smallest and darkest lizards showed the greatest heating rate and net heat g...
High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. O... more High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. One common mechanism is through increased values of blood traits such as erythrocyte count, hematocrit, and hemoglobin concentration. However, a positive relationship between altitude and blood traits is not observed in all high-altitude systems. To understand how organisms adapt to high altitudes, it is important to document physiological patterns related to hypoxia gradients from a greater variety of species. Here, we present an extensive hematological description for three populations of Sceloporus grammicus living at 2,500, 3,400, and 4,300 m. We did not find a linear increase with altitude for any of the blood traits we measured. Instead, we found nonlinear relationships between altitude and the blood traits erythrocyte number, erythrocyte size, hematocrit, and hemoglobin concentration. Erythrocyte number and hematocrit leveled off as altitude increased, whereas hemoglobin concentration and erythrocyte size were highest at intermediate altitude. Additionally, lizards from our three study populations are similar in blood pH, serum electrolytes, glucose, and lactate. Given that the highest-altitude population did not show the highest levels of the variables we measured, we suggest these lizards may be using different adaptations to cope with hypoxia than lizards at low or intermediate altitudes. We discuss future directions that research could take to investigate such potential adaptations.
La incontinencia urinaria es definida por la International Continence Society como la queja ante ... more La incontinencia urinaria es definida por la International Continence Society como la queja ante cualquier salida involuntaria de orina. Se calcula que en el mundo alrededor del 30% de mujeres mayores de 60 años la padecen. En México no se han realizado estudios sistemáticos sobre la prevalencia de la incontinencia urinaria, pero se estima que entre el 15 y el 30% de mujeres mayores de 60 años la padecen. En el tratamiento de esta patología es importante conocer el sustrato anatómico y fisiológico de los procesos expulsivos femeninos contenidos en la región pélvica. En la presente revisión se describe los principales factores que desencadenan la incontinencia urinaria, los tratamientos para su control y la importancia de generar modelos animales que permitan conocer los factores asociados a su desarrollo.
The collared peccary (Pecari tajacu) is an ungulate animal and little is known about its reproduc... more The collared peccary (Pecari tajacu) is an ungulate animal and little is known about its reproductive physiology. In this work, an anatomic description of the urogenital apparatus (ua) was performed. Eight female and five male collar peccaries were anesthetized and perfused with McKormik solution. The ua was dissected out and its structures were further described. The ua of the collared peccary was found to be typical of mammals and it shared many features with the ua of the pig. Thus far,this is the first report to describe structures such as the urogenital sinus, vestibular glands and vulva-associated striated muscle in females. It is also the first description of the male ua of the collared peccary in which several exclusive characteristics were found.
This study examined changes in certain hematological parameters in a reptilian model naturally ex... more This study examined changes in certain hematological parameters in a reptilian model naturally exposed to altitude-associated hypoxia. Four populations of the Mexican lizard Sceloporus torquatus Wiegmann, 1828 (Wiegmann’s Torquate Lizard) from different altitudes were sampled to evaluate erythrocyte count (Erc), hematocrit (Hct), mean corpuscular hemoglobin concentration (MCHC), and erythrocyte size (Ers). Blood was also assayed to determine hemoglobin ([Hb]), glucose, lactate, and electrolyte concentrations. Erc was performed using a Neubauer hemocytometer. Hct was calculated as percentage of packed cell volume by centrifuging blood samples. [Hb] was determined using a Bausch and Lomb Spectronic colorimeter. MCHC was calculated with the formula 100 × [Hb]/Hct. Ers was calculated from blood smear microphotographs analyzed with the Sigma Scan Pro software. Values of serum electrolytes (sodium (Na+), potassium (K+), and calcium (Ca2+)), pH, glucose, and lactate from blood samples were...
Temporal and coordinated activation of pelvic- (pubococcygeous) and perineal- (bulbospongiosus an... more Temporal and coordinated activation of pelvic- (pubococcygeous) and perineal- (bulbospongiosus and ischiocavernosus) striated muscles occurs during micturition in female rabbits. We have hypothesized that the coordinated activation of pelvic and perineal muscles is modified during the micturition of young multiparous rabbits. Young virgin and multiparous female chinchilla rabbits were used to simultaneously record cystometrograms and electromyograms of the pubococcygeous, ischocavernosus, and bulbospongiosus muscles. Bladder function was assessed using standard urodynamic variables. The temporal coordination of pelvic- and perineal-striated muscle activity was changed in multiparous rabbits. The cystometrogram recordings were different than those obtained from virgin rabbits, as seen in alterations of the threshold volume, the residual volume, the voiding duration, and the maximum pressure. In rabbits, we find that multiparity causes uncoordinated activity of pubococcygeous, ischiocavernosus, and bulbospongiosus muscles and modifies the urodynamics.
To determine the motor basis of urine expulsion the activity of the pelvic (pubococcygeus) and pe... more To determine the motor basis of urine expulsion the activity of the pelvic (pubococcygeus) and perineal (bulbospongiosus and ischiocavernosus) muscles was recorded during micturition in anesthetized female rabbits. Virgin female chinchilla rabbits were used for simultaneously recording cystometrograms and electromyograms of the pubococcygeus, ischiocavernosus and bulbospongiosus muscles. The particular contribution of each muscle during micturition was analyzed in another set of experiments in which each was inactivated by bilateral lidocaine injection. Bladder function was assessed using standard urodynamic parameters. Cystometrography showed that micturition comprises 2 phases, that is storage and voiding phases. During the latter phase no high frequency oscillations were recorded. On simultaneous electromyography recordings a temporal, coordinated activation of pelvic (pubococcygeus) and perineal (bulbospongiosus and ischiocavernosus) muscles was observed. During specific blockade of each muscle some modifications in urodynamic parameters were found. Our findings indicate a specific role for the pelvic and perineal muscles during feminine micturition.
ABSTRACT Small or isolated populations are highly susceptible to stochastic events. They are pron... more ABSTRACT Small or isolated populations are highly susceptible to stochastic events. They are prone and vulnerable to random demographic or environmental fluctuations that could lead to extinction due to the loss of alleles through genetic drift and increased inbreeding. We studied Ambystoma leorae an endemic and critically threatened species. We analyzed the genetic diversity and structure, effective population size, presence of bottlenecks and inbreeding coefficient of 96 individuals based on nine microsatellite loci. We found high levels of genetic diversity expressed as heterozygosity (Ho = 0.804, He = 0.613, He* = 0.626 and HNei = 0.622). The population presents few alleles (4–9 per locus) and genotypes (3–14 per locus) compared with other mole salamanders species. We identified three genetically differentiated subpopulations with a significant level of genetic structure (FST = 0.021, RST = 0.044 y Dest = 0.010, 95 % CI). We also detected a reduction signal in population size and evidence of a genetic bottleneck (M = 0.367). The effective population size is small (Ne = 45.2), but similar to another mole salamanders with restricted distributions or with recently fragmented habitat. The inbreeding coefficient levels detected are low (FIS = −0.619–0.102) as is gene flow. Despite, high levels of genetic diversity A. leorae is critically endangered because it is a small isolated population.
The composition and energetic content of puma (Puma concolor) diet in Sierra Nanchititla Natural ... more The composition and energetic content of puma (Puma concolor) diet in Sierra Nanchititla Natural Reserve (SNNR), Mexico, were determined. We collected 183 scats, where 27 components were identified by occurrence (88.07% mammals). The puma's diet was mainly composed of armadillo (Dasypus novemcinctus, 40.33%), white-nosed coati (Nasua narica, 11.93%) and white-tailed deer (Odocoileus virginianus, 6.17%). Energetic analysis of prey indicates that the puma prefers those with higher energetic content (kcal/kg). The prey with the most energetic contribution is armadillo (2398.70 kcal/kg), followed by white-nosed coati (2225.25 kcal/kg) and finally white-tailed deer (2165.52 kcal/kg). The differences in energetic content between prey species were statistically significant. The number of individuals killed/year on average to support a puma was 51 armadillos, 16 white-tailed deer and 7 white-nosed coatis. The results indicate a greater consumption of prey that provide more kilocalories ...
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