Boa constrictor attack and successful group defence in moustached tamarins, Saguinus mystax.
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Aggression↗
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White-faced Capuchins cooperate to rescue a groupmate from a boa constrictor.
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Aggression↗
Fatal attack of a Boa constrictor on a bearded saki (Chiropotes satanas utahicki).
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Animals↗
Tribute to Ismar Boas (1858-1938).
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Animals↗
Adenovirus hepatitis in a boa constrictor (Boa constrictor).
A boa constrictor was submitted for postmortem evaluation. At necropsy, there were no substantial lesions except in the liver. Light microscopy revealed severe multifocal to coalescing coagulative necrotic hepatitis, with basophilic and eosinophilic intranuclear inclusions in hepatocytes within the necrotic foci. The histopathological findings suggested a viral hepatitis. An adenoviral infection was diagnosed by means of transmission electronic microscopy and in situ hybridization techniques.
Adenoviridae↗
Immunohistochemical staining of chlamydial antigen in emerald tree boas (Corallus caninus).
Of 120 privately owned captive-bred and wild-collected emerald tree boas (ETBs) (Corallus caninus), 97 died or were euthanatized. Eighteen snakes were necropsied, and tissues were collected from all major organs and processed for light microscopy. Histologic examination demonstrated histiocytic granulomas in the small intestine, heart, and esophageal tonsils of one ETB, small intestine of a second ETB, and in an esophageal tonsil of a third ETB. Within the center of these granulomas, small, basophilic, punctate organisms were demonstrated using hematoxylin and eosin staining. Transmission electron microscopic examination of an intestinal granuloma demonstrated developmental stages of organisms consistent with members of the family Chlamydiaceae. An immunoperoxidase staining technique and 2 different commercially available monoclonal antibodies against chlamydial lipopolysaccharide antigen was used to identify chlamydial antigen in these lesions. Liver of a puff adder (Bitis arietans) with previously reported systemic chlamydiosis served as the positive control. Both monoclonal antibodies stained antigen in these granulomas. Additionally, macrophages within aggregates of lymphoplasmacytic cells in the colon, small intestine, and esophageal tonsils of 3 other ETBs contained antigen. Although both antibodies labeled antigen in serial sections of tissue, a difference in staining intensity was noted.
Animals↗
Identification of Chlamydophila pneumoniae in an emerald tree boa, Corallus caninus.
Tissues were evaluated from emerald tree boas, Corallus caninus, from a collection in which chlamydiosis was diagnosed. To determine the strain of chlamydia infecting these snakes, tissue samples from 5 frozen snakes were tested by a quantitative TaqMan polymerase chain reaction (PCR) test and a PCR sequence analysis test. Of the 22 samples tested, 9 were categorized as either positive or weakly positive with the TaqMan test, and 6 yielded an amplicon using a serial PCR test that amplified a portion of the 23S ribosomal RNA gene. A PCR product suitable for sequencing was obtained from the heart of one of the snakes. Sequence analysis showed that the snake had been infected with Chlamydophila pneumoniae. These findings show that C. pneumoniae can infect emerald tree boas, broadening the range of reptiles known to be infected by this primarily human pathogen.
Animals↗
Gastric function and its contribution to the postprandial metabolic response of the Burmese python Python molurus.
The large intact prey ingested by Burmese pythons require considerable processing by the stomach before passage into the small intestine. To investigate the function and cost of gastric digestion and its contribution to postprandial metabolic response for the Burmese python, I examined the rate of gastric digestion, the postprandial profile of gastric pH and the effects of decreasing gastric workload on the metabolic cost of digestion, referred to as specific dynamic action (SDA). Ingested meal mass (equivalent to 25% of snake body mass) was reduced by 18% within 1 day postfeeding, by which time intragastric pH had decreased from 7.5 to 2. Gastric pH was maintained at 1.5 for the next 5-7 days, after which it returned to 7.5. The SDA generated by digesting an intact rat meal was reduced by 9.1%, 26.0%, 56.5% and 66.8%, respectively, when pythons were fed steak, ground rat, liquid diet or ground rat directly infused into the small intestine. The production of HCl and enzymes and other gastric functions represent an estimated 55% of the python's SDA generated from the digestion of an intact rodent meal. Additional contributors to SDA include protein synthesis (estimated 26%), gastrointestinal upregulation (estimated 5%) and the activities of the pancreas, gallbladder, liver, kidneys and intestines during digestion (estimated 14%). Operating on a 'pay before pumping' principle, pythons must expend endogenous energy in order to initiate acid production and other digestive processes before ingested nutrients can be absorbed and channeled into metabolic pathways.
Animals↗
Ventricular haemodynamics in Python molurus: separation of pulmonary and systemic pressures.
Vascular pressure separation by virtue of a two-chambered ventricle evolved independently in mammals and birds from a reptilian ancestor with a single ventricle, and allowed for high systemic perfusion pressure while protecting the lungs from oedema. Within non-crocodilian reptiles, ventricular pressure separation has only been observed in varanid lizards and has been regarded as a unique adaptation to an active predatory life style and high metabolic rate. The systemic and pulmonary sides of the ventricle in Python molurus are well separated by the muscular ridge, and a previous study using in situ perfusion of the heart revealed a remarkable flow separation and showed that the systemic side can sustain higher output pressures than the pulmonary side. Here we extend these observations by showing that systemic blood pressure P(sys) exceeded pulmonary pressure P(pul) almost seven times (75.7+/-4.2 versus 11.6+/-1.1 cm H(2)O). The large pressure difference between the systemic and pulmonary circulation persisted when P(sys) was altered by infusion of sodium nitroprusside or phenylephrine. Intraventricular pressures, measured in anaesthetised snakes, showed an overlap in the pressure profile between the pulmonary side of the ventricle (cavum pulmonale) and the pulmonary artery, while the higher pressure in the systemic side of the ventricle (cavum arteriosum) overlapped with the pressure in the right aortic arch. This verifies that the pressure differences originate within the ventricle, indicating that the large muscular ridge separates the ventricle during cardiac contraction.
Animals↗
Ventilatory compensation of the alkaline tide during digestion in the snake Boa constrictor.
The increased metabolic rate during digestion is associated with changes in arterial acid-base parameters that are caused by gastric acid secretion (the 'alkaline tide'). Net transfer of HCl to the stomach lumen causes an increase in plasma HCO3- levels, but arterial pH does not change because of a ventilatory compensation that counters the metabolic alkalosis. It seems, therefore, that ventilation is controlled to preserve pH and not PCO2 during the postprandial period. To investigate this possibility, we determined arterial acid-base parameters and the metabolic response to digestion in the snake Boa constrictor, where gastric acid secretion was inhibited pharmacologically by oral administration of omeprazole. The increase in oxygen consumption of omeprazole-treated snakes after ingestion of 30% of their own body mass was quantitatively similar to the response in untreated snakes, although the peak of the metabolic response occurred later (36 h versus 24 h). Untreated control animals exhibited a large increase in arterial plasma HCO3- concentration of approximately 12 mmol l(-1), but arterial pH only increased by 0.12 pH units because of a simultaneous increase in arterial PCO2 by about 10 mmHg. Omeprazole virtually abolished the changes in arterial pH and plasma HCO3- concentration during digestion and there was no increase in arterial PCO2. The increased arterial PCO2 during digestion is not caused, therefore, by the increased metabolism during digestion or a lower ventilatory responsiveness to ventilatory stimuli during a presumably relaxed state in digestion. Furthermore, the constant arterial PCO2, in the absence of an alkaline tide, of omeprazole-treated snakes strongly suggests that pH rather than PCO2 normally affects chemoreceptor activity and ventilatory drive.
Acid-Base Equilibrium↗
Patterns of blood flow during the postprandial response in ball pythons, Python regius.
We present evidence supporting the hypothesis that postprandial upregulation of the size of the small intestine and the liver is caused by an increased blood flow volume to the organs. The postprandial response of ball pythons was characterized by measurements of oxygen consumption, organ size changes and histological evaluation of the mucosal epithelium and liver parenchyme. Synchronized with these changes in measurements were changes in the patterns of blood flow volume to small intestine and liver. A correlation analysis of organ size change and blood flow volume showed a significant nonlinear relationship, which explained about 50% of the overall variances in organ size (small intestine, liver). Histological analysis indicated that incorporation of lipid droplets in enterocytes and in hepatocytes contributes to an increase of absorptive surface magnification (in small intestine) and hepatocyte size (in liver). Collectively, these data support the concept that in the ball python, postprandial upregulation of organ size does not reflect new mitotic activity, but rather results from increased blood volume in the intestinal villi and incorporation of lipid droplets into enterocytes and hepatocytes, respectively.
Analysis of Variance↗
The role of the sarcoplasmic reticulum in the generation of high heart rates and blood pressures in reptiles.
The functional significance of the sarcoplasmic reticulum (SR) in the generation of high heart rates and blood pressures was investigated in four species of reptile; the turtle, Trachemys scripta; the python, Python regius, the tegu lizard, Tupinanvis merianae, and the varanid lizard, Varanus exanthematicus. Force-frequency trials and imposed pauses were performed on ventricular and atrial tissue from each species with and without the SR inhibitor ryanodine, and in the absence and presence of adrenaline. In all species, an imposed pause of 1 or 5 min caused a post-rest decay of force, and a negative force-frequency response was observed in all species within their in vivo frequency range of heart rates. These relationships were not affected by either ryanodine or adrenaline. In ventricular strips from varanid lizards and pythons, ryanodine caused significant reductions in twitch force within their physiologically relevant frequency range. In atrial tissue from the tegu and varanid lizards, SR inhibition reduced twitch force across the whole of their physiological frequency range. In contrast, in the more sedentary species, the turtle and the python, SR inhibition only decreased twitch force at stimulation frequencies above maximal in vivo heart rates. Adrenaline caused an increase in twitch force in all species studied. In ventricular tissue, this positive inotropic effect was sufficient to overcome the negative effects of ryanodine. In atrial tissue however, adrenaline could only ameliorate the negative effects of ryanodine at the lower pacing frequencies. Our results indicate that reptiles recruit Ca2+ from the SR for force development in a frequency and tissue dependent manner. This is discussed in the context of the development of high reptilian heart rates and blood pressures.
Animals↗
Adaptive regulation of digestive performance in the genus Python.
The adaptive interplay between feeding habits and digestive physiology is demonstrated by the Burmese python, which in response to feeding infrequently has evolved the capacity to widely regulate gastrointestinal performance with feeding and fasting. To explore the generality of this physiological trait among pythons, we compared the postprandial responses of metabolism and both intestinal morphology and function among five members of the genus Python: P. brongersmai, P. molurus, P. regius, P. reticulatus and P. sebae. These infrequently feeding pythons inhabit Africa, southeast Asia and Indonesia and vary in body shape from short and stout (P. brongersmai) to long and slender (P. reticulatus). Following the consumption of rodent meals equaling 25% of snake body mass, metabolic rates of pythons peaked at 1.5 days at levels 9.9- to 14.5-fold of standard metabolic rates before returning to prefeeding rates by day 6-8. Specific dynamic action of these meals (317-347 kJ) did not differ among species and equaled 23-27% of the ingested energy. For each species, feeding triggered significant upregulation of intestinal nutrient transport and aminopeptidase-N activity. Concurrently, intestinal mass doubled on average for the five species, in part due to an 85% increase in mucosal thickness, itself a product of 27-59% increases in enterocyte volume. The integrative response of intestinal functional upregulation and tissue hypertrophy enables each of these five python species, regardless of body shape, to modulate intestinal performance to meet the demands of their large infrequent meals.
Adaptation, Physiological↗
Adaptive responses to feeding in Burmese pythons: pay before pumping.
Burmese pythons normally consume large meals after long intervals. We measured gut contents, O2 consumption rates, small intestinal brush-border uptake rates of amino acids and glucose, organ masses and blood chemistry in pythons during the 30 days following ingestion of meals equivalent to 25% of their body mass. Within 1-3 days after ingestion, O2 consumption rates, intestinal nutrient uptake rates and uptake capacities peaked at 17, 6-26 and 11-24 times fasting levels, respectively. Small intestinal mass doubled, and other organs also increased in mass. Changes in blood chemistry included a 78% decline in PO2 and a large 'alkaline tide' associated with gastric acid section (i.e. a rise in blood pH and HCO3- concentrations and a fall in Cl- concentration). All of these values returned to fasting levels by the time of defecation at 8-14 days. The response of O2 consumption (referred to as specific dynamic action, SDA) is the largest, and the upregulation of intestinal nutrient transporters the second largest, response reported for any vertebrate upon feeding. The SDA is a large as the factorial rise in O2 consumption measured in mammalian sprinters and is sustained for much longer. The extra energy expended for digestion is equivalent to 32% of the meal's energy yield, with much of it being measured before the prey energy was absorbed.
Adaptation, Physiological↗
Ventilatory and cardiovascular responses of a python (Python molurus) to exercise and digestion.
To investigate the potential limiting steps of peak metabolic rates, we examined gas exchange rates ( vdot (O2), vdot (CO2)), respiratory exchange ratio (RER), breathing frequency, tidal volume, minute ventilation volume (V.e) as well as the heart rate, systemic blood flow and stroke volume of Burmese pythons (Python molurus) while fasting at rest, exercising, digesting and exercising while digesting. All measured variables increased significantly during exercise (crawling at 0.4 km h(-)(1) and at vdot (O2max)), highlighted by a 17-fold increase in vdot (CO2) and a 24-fold increase in V.e. During the digestion of a meal equivalent to 25 % of the snake's body mass, pythons responded with increases in vdot (O2) and heart rate similar to those experienced during exercise, along with a 4.5-fold increase in systemic blood flow. Interestingly, pythons hyperventilated while exercising, whereas they hypoventilated during digestion. The combined demands of exercise and digestion resulted in significantly higher vdot (O2), vdot (CO2), breathing frequency and heart rate than during either exercise or digestion alone. Evidently, the capacities of the ventilatory and cardiovascular systems to transport oxygen to locomotor muscles are not a limiting factor in the attainment of peak metabolic rates during exercise in pythons
Animals↗
Structural flexibility of the intestine of Burmese python in response to feeding.
The small intestine of Burmese pythons, Python molurus bivittatus, undergoes a remarkable size increase shortly after feeding. We studied the dynamics, reversibility and repeatability of organ size changes using noninvasive imaging techniques. We employed light and electron microscopy, flow cytometry and immunohistology to study the cytological mechanisms that drive the size changes of the small intestine. Within 2 days of feeding, the size of the small intestine increased to up to three times the fasting value. The size changes were fully reversible and could be elicited repeatedly by feeding. These enormous size changes were possible because the mucosal epithelium of the small intestine is a transitional epithelium that allows for considerable size changes without cell proliferation. Histological evidence suggested that a fluid pressure-pump system (lymphatic, blood pressure) was the driving force that inflated the intestinal villi. The rates of cell proliferation were not elevated immediately after feeding but peaked 1 week later when small intestine size was already declining. In contrast to the current paradigm, we suggest that the small intestine is not part of the previously proposed 'pay-before-pumping' model. Instead, the size of the python's small intestine may be upregulated without major metabolic investment. It can occur even if the individual is energetically exhausted. An evolutionary perspective of the transitional epithelium mechanism suggests superior functionality compared with the pay-before-pumping model because it allows for long periods of fasting and depletion of energy reserves, while still enabling the snake to digest prey and absorb nutrients.
Animals↗
Increased blood oxygen affinity during digestion in the snake Python molurus.
Many snakes exhibit large increases in metabolic rate during digestion that place extensive demands on efficient oxygen transport. In the present study, we describe blood oxygen affinity following three weeks of fasting and 48 h after feeding in the Burmese python (Python molurus). We also report simultaneous measurements of arterial blood gases and haematological parameters. Arterial blood was obtained from chronically implanted catheters, and blood oxygen-dissociation curves were constructed from oxygen content measurements at known oxygen partial pressure (P(O(2))) values at 2% and 5% CO(2). Arterial pH remained constant at approximately 7.6 after feeding, but digestion was associated with an approximately 6 mmol l(-1) increase in [HCO(3)(-)], while CO(2) partial pressure (P(CO(2))) increased from 2.21+/-0.13 kPa in fasted animals to 2.89+/-0.17 kPa at 48 h after feeding. Blood oxygen affinity in vivo was predicted on the basis of pH in vivo and the blood oxygen-dissociation curves obtained in vitro. The blood oxygen affinity in vivo increased during digestion, with P(50) values decreasing from 4.58+/-0.11 kPa to 3.53+/-0.24 kPa. This increase was associated with a significant decrease in the red blood cell [NTP]/[Hb(4)] ratio (relationship between the concentrations of organic phosphates and total haemoglobin) and a significant decrease in mean cellular haemoglobin content, which is indicative of swelling of the red blood cells. Our data for blood oxygen affinity and arterial oxygen levels, together with previously published values of oxygen uptake and blood flows, allow for a quantitative evaluation of oxygen transport during digestion. This analysis shows that a large part of the increased metabolism during digestion is supported by an increased venous extraction, while arterial P(O(2)) (Pa(O(2))) and haemoglobin saturation do not vary with digestive status. Thus, we predict that venous P(O(2)) (Pv(O(2))) is reduced from a fasting value of 5.2 kPa to 1.6 kPa during digestion.
Animals↗
Amebiasis in four ball pythons, Python reginus.
Between September 13th and November 18th in 1999, four ball pythons, Python reginus kept in the same display, showed anorexia and died one after another. At necropsy, all four snakes had severe hemorrhagic colitis. Microscopically, all snakes had severe necrotizing hemorrhagic colitis, in association with ameba-like protozoa. Some of the protozoa had macrophage-like morphology and others formed protozoal cysts with thickened walls. These protozoa were distributed throughout the wall in the large intestine. Based on the pathological findings, these snakes were infested with a member of Entamoeba sp., presumably with infection by Entamoeba invadens, the most prevalent type of reptilian amoebae.
Animals↗