Homeothermic Animals Research Articles

The northernmost record of a blood-sucking ectoparasite, Lipoptena fortisetosa Maa (Diptera: Hippoboscidae), in Estonia.

BackgroundDeer keds are obligatory haematophagous parasites of large homeothermic animals, particularly cervids. Two of the five known species occurring in Europe—Lipoptena cervi (Linnaeus) and L. fortisetosa Maa—are known to have a relatively wide distribution. Lipoptena fortisetosa is considered to have been introduced into Europe with sika deer from the Eastern Palaearctic and is continuously expanding its range. Little is known about the medical importance of deer keds, but they can cause hair loss in cervids and are suspected to be vectors of several diseases.New informationDetails of the distribution of Lipoptena fortisetosa in Europe, including its northernmost record, are provided. This species has been shown to have a viable population in Southern Estonia. Furthermore, the differences from allied L. cervi are discussed, based on morphological and molecular characters.

The Intensity of Free Radical Processes on Rat Liver Mitochondria under Moderate Hypothermia of Various Duration

Moderate artificial hypothermia is widely used in clinical practice to protect organs from the effects of ischemia (reperfusion), trauma, and hypoxia. However, a decrease in the body temperature of homeothermic animals induces oxidative stress, the severity of which may depend on the time of exposure to the cold factor. Since mitochondria play a key role in the generation of reactive oxygen species, we studied the dependence of the intensity of free radical processes in rat liver mitochondria on the duration of moderate hypothermia (30°C). It turned out that short-term (30 min) hypothermia activates the processes of lipid peroxidation (POL), while the concentration of lipid hydroperoxides, Schiff bases, and malondialdehyde significantly increases. Prolongation of hypothermia to 1 h reduces the content of many lipid peroxidation products, and their normalization is observed with 3-h hypothermia. Short-term hypothermia and its prolongation up to 1 h is accompanied by oxidative destruction of mitochondrial proteins, which is manifested in a decrease in the content of sulfhydryl groups in them and an increase in carbonyl groups. At the same time, 3-h hypothermia contributes to the normalization of the studied markers of protein oxidative modification. The dynamics of changes in the levels of sulfhydryl and carbonyl groups in the mitochondrial matrix proteins is more pronounced in comparison with membrane proteins. The study of the spectral characteristics of mitochondrial membrane proteins showed a decrease in the intensity of their fluorescence at the initial stages of hypothermia. Tryptophan residues localized at the periphery make the main contribution to it. Prolongation of hypothermia up to 3 h contributes to restoration of fluorescence parameters to the control level. The data obtained in the analysis of the second derivative fluorescence spectra indicate changes in the spatial configuration of membrane proteins.

Cooling requirements fueled the collapse of a desert bird community from climate change

Climate change threatens global biodiversity by increasing extinction risk, yet few studies have uncovered a physiological basis of climate-driven species declines. Maintaining a stable body temperature is a fundamental requirement for homeothermic animals, and water is a vital resource that facilitates thermoregulation through evaporative cooling, especially in hot environments. Here, we explore the potential for thermoregulatory costs to underlie the community collapse of birds in the Mojave Desert over the past century in response to climate change. The probability of persistence was lowest for species occupying the warmest and driest sites, which imposed the greatest cooling costs. We developed a general model of heat flux to evaluate whether water requirements for evaporative cooling contributed to species' declines by simulating thermoregulatory costs in the Mojave Desert for 50 bird species representing the range of observed declines. Bird species' declines were positively associated with climate-driven increases in water requirements for evaporative cooling and exacerbated by large body size, especially for species with animal-based diets. Species exhibiting reductions in body size across their range saved up to 14% in cooling costs and experienced less decline than species without size reductions, suggesting total cooling costs as a mechanism underlying Bergmann's rule. Reductions in body size, however, are unlikely to offset the 50 to 78% increase in cooling costs threatening desert birds from future climate change. As climate change spreads warm, dry conditions across the planet, water requirements are increasingly likely to drive population declines, providing a physiological basis for climate-driven extinctions.

Вивчення захисної дії синтетичного нейропептиду даларгіну в умовах холодового стресу

The effect of the neuropeptide dalargin, which is a synthetic analogue of leu-enkephalins, on the negative processes caused by cold stress, which occur when artificial hypothermia is used in vivo, was studyd. It was shown that dalargin prevents the development of apoptotic processes in the cells of homeothermic animals after cold stress, which manifested itself in a decrease in the degree of DNA fragmentation. In the kidneys and liver of experimental animals subjected to cooling, this attribute of apoptosis and cell necrosis was not detected, and in the intestinal mucosa and spleen the level of DNA fragmentation as a result of cold stress is statistically significant. The preliminary injection of dalargin to rats reduces the degree of DNA fragmentation to values that occurred in animals that were not exposed to cold stress. It is also shown that dalargin prevents the development of adrenal hypertrophy in experimental animals, reduces the degree of involution of the thymus and spleen, and reduces the severity of cold stress-induced ulcerogenesis. The simultaneous injection to animals of an opiate receptor antagonist naloxone eliminated the protective effect of an opiate receptor agonist dalargin.Probl Cryobiol Cryomed 2019; 29(3): 246–254.

Cell thermoregulation and origin of homeothermic animals

Temperature has a fundamental influence in all chemical and biochemical reactions. It influences reaction rates, equilibrium amounts, viscosity, solubility, molecular arrangements and numeric other parameters. Temperature is important for all physiological processes. Maintaining the relative constancy of the internal temperature (temperature homeostasis) is a necessary condition for normal life. Some living beings maintain temperature homeostasis in the body due to external sources of energy (poikilothermy), others due to the energy of food consumption (homeothermy). However, it is unknown the origin of homeothermic organisms. Despite the fundamental similarity of the mechanisms of the central organ-based physiological thermoregulation, even among the higher vertebrates exists poikilothermy and homeothermy animals. It is assumed that homeothermy is not the result of the evolution of physiological mechanisms of thermoregulation. Homeothermy is the result of the evolution of non-coding DNAs in the genome, some of which formed the so-called chromosomal heterochromatin regions (HRs). Chromosomal HRs constitutes the material basis of cell thermoregulation, which is responsible for the removal of excess thermal energy from the nucleus into the cytoplasm. Homeothermic organisms, unlike poikilotherms capable of faster and more efficient leveling of temperature difference between the nucleus and the cytoplasm with all the ensuing consequences.

Effect of Different Breeding Densities and Inclusion of Soybean Oil on Performance, Carcass Trait and Heat Loss in Meat Quails

Quails are homeothermic animals, in countries with a tropical climate, such as Brazil, birds face great difficulties in controlling body temperature inside the sheds. Several practices are being studied in order to keep these animals within the thermal comfort zone, and thus, to minimize the effects of thermal stress, partial substitution of carbohydrates by oils and changes in density are some of them. The objective of this study was to evaluate the different breeding densities and inclusion levels of soybean oil in performance, carcass characteristics and heat loss in quail. 450 quails, seven days old, distributed in a completely randomized design in a 3 × 2 factorial scheme, two densities (215.6 cm2 bird-1 and 188.6 cm2 bird-1) and three inclusion levels of soybean oil (0, 2, 4%) were used, totaling six treatments with five replicates each. The heat loss by radiation was estimated with the aid of infrared thermography. The results showed that there was an effect of the density on feed consumption, which was lower for birds raised in the density of 188.6 cm2 bird-1 (783.78 g of feed), but without its effect on weight gain and food conversion. No effect of inclusion levels of soybean oil was observed on any performance variables. There was no statistical difference (P > 0.05) between treatments for any variables of carcass yield and parts, and heat loss by radiation analyzed. Therefore, it is concluded that soybean oil inclusion levels do not affect the performance and yield of quails, nor do they influence the loss of heat throughout the life cycle of these animals. The birds raised in the density of 188.6 cm2 bird-1 obtained the lowest average dietary intake, with no impact on weight gain and feed conversion, allowing the creation of a greater number of birds per box.

Mixed Toxoplasma gondii infection and new genotypes in feral cats of Quintana Roo, México

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii that infects homeothermic animals, including humans. To date, as many as 287 genotypes have been described worldwide. Genetic characterization of the parasite is crucial because the parasite type can determine the presentation and severity of toxoplasmosis. Previously, we reported that the Yucatán Peninsula has a frequency of infection of over 70% in humans and other animals; moreover, there are seven species of felids, including domestic cats; thus, we hypothesized that this might be a region with a high diversity of the parasite. Nevertheless, no genotyping of this protozoan has been performed in this region. Thus, the aim of this study was to genotype T. gondii from naturally infected feral cats of Quintana Roo, within the Yucatán Peninsula, and to describe its genetic variability. Eleven feral cats were captured and bled to obtain the buffy coat; then, they were euthanized to collect target organs or tissues to extract DNA. Samples were processed by PCR for diagnosis, and ten polymorphic markers were genotyped by PCR-RFLP. Atypical GRA6 gene products were cloned and sequenced. Ten of the eleven cats were PCR positive for toxoplasmosis in blood; of these, seven had mixed infections. Also, two isolates were obtained from the heart and diaphragm of two animals. At least 23 different genotypes were detected, from which 18 are new worldwide. From the atypical GRA6 gene cloning and sequencing analysis, a mixed infection was discovered, due to one strain identical to GT1 and another to VAND. In conclusion, T. gondii genetic diversity in the region is high and different from that in other regions, with new genotypes exclusive to México and some others shared with USA and South America.

Clinical Toxoplasmosis in Dogs and Cats: An Update.

Toxoplasmosis is caused by the globally distributed protozoan parasite Toxoplasma gondii (phylum Apicomplexa); the disease can be clinically important for almost all homeothermic animals, including birds and humans. Toxoplasmosis course involves general clinical signs, such as fever, anorexia, or dyspnea, and more specific signs with neural, respiratory, cutaneous, or ocular involvement. Because of the wide range of clinical signs, the diagnosis in domestic and pet animals can be complicated. Hence, this review aims to provide a comprehensive analysis of some scarcely discussed aspects of toxoplasmosis, such as ocular and cutaneous manifestations, congenital infections, influence of T. gondii genotype on clinical toxoplasmosis, and recent findings regarding differential diagnosis. This review could be of special interest to clinicians and researchers.

Serological study on toxoplasmosis in the Haliti-Paresí community of the Utiariti indigenous territory, Campo Novo do Parecis, Mato Grosso, Brazil

Toxoplasma gondii is the etiological agent of toxoplasmosis, a widespread zoonosis that affects several homeothermic animals, including humans. This disease causes serious health problems, such that 10% of infected individuals develop clinical manifestations. Some studies on indigenous human populations have indicated variations in seroprevalence from 10.6% to 80.4% in such populations in different regions of Brazil and in other countries like Venezuela and Malaysia. To date, there have been no studies regarding the prevalence of anti-T. gondii antibodies in Haliti-Paresí Indians living in Campo Novo do Parecis, Mato Grosso, Brazil. Our objective here was to determine the frequency of occurrence of antibodies against this protozoon in nine Haliti-Paresí villages by correlating seroprevalence with locations and variables. Serodiagnoses were made using the indirect immunofluorescence antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) in the Laboratory for Toxoplasmosis and Other Protozoan Diseases of IOC/Fiocruz. It was considered that samples tested positive for T. gondii infection if IgG/IgM antibodies against this protozoon were detected through serodiagnosis using either IFAT or ELISA. Among the 293 samples analyzed, 66.9% presented anti-T. gondii IgG and 3.4% presented anti-T. gondii IgM. It was observed that there were no statistically significant differences in frequency of antibody occurrence among infected individuals, based on sex, schooling or occupation/activities. However, there were statistical differences based on age and villages. The prevalence observed in this study is in agreement with values found in other studies on indigenous populations in Latin America. Like among other such populations, the Haliti-Paresí villages are located close to forests and the individuals have domestic cats as pets, are involved in hunting and farming and consume water directly from water accumulation sources. These factors might cause exposure to T. gondii tissue cysts and oocysts.

Cassowary casques act as thermal windows

Many ideas have been put forward for the adaptive value of the cassowary casque; and yet, its purpose remains speculative. Homeothermic animals elevate body temperature through metabolic heat production. Heat gain must be offset by heat loss to maintain internal temperatures within a range for optimal performance. Living in a tropical climate, cassowaries, being large bodied, dark feathered birds, are under thermal pressure to offload heat. We tested the original hypothesis that the casque acts as a thermal window. With infrared thermographic analyses of living cassowaries over an expansive range of ambient temperatures, we provide evidence that the casque acts as a thermal radiator, offloading heat at high temperatures and restricting heat loss at low temperatures. Interestingly, at intermediate temperatures, the casque appears thermally heterogeneous, with the posterior of the casque heating up before the front half. These findings might have implications for the function of similar structures in avian and non-avian dinosaurs.

The frontier of adipocyte biology, cold environment induces thermogenic genes via epigenomic switch.

Epigenome, a record of the chemical changes to the DNA and histone proteins of an organism, is dynamically altered by environmental conditions and thus contributes to an adaptive mechanism for the given environmental stress. Among them, the cold environment is life-threatening to homeothermic animals. To combat, they induce thermogenic gene expression such as Ucp1 against cold stress. We recently revealed dual roles for the histone demethylase JMJD1A as a mediator of both acute and chronic thermogenic responses to cold stress, in two distinct thermogenic tissues, and through two distinct molecular mechanisms.

Core body temperature, energy expenditure, and epinephrine during fasting, eucaloric feeding, and overfeeding in healthy adult men: evidence for a ceiling effect for human thermogenic response to diet

BackgroundIn homeothermic animals, approximately 50% of daily energy expenditure (EE) is spent to maintain a consistent core body temperature (CBT). In humans, little is known about CBT responses to feeding and overfeeding and their relationship to diet-related changes in EE. ObjectiveTo study the effects of feeding and overfeeding on CBT and its association with diet-induced thermogenesis (DIT). DesignFifty-three healthy men with normal glucose regulation and a wide range of body composition (mean ± SD, body fat: 25 ± 8%, range: 7–43%) had 24-h EE assessed during fasting in a whole-room indirect calorimeter with concomitant CBT measurement by ingestible capsules and 24-h urinary collection for catecholamine measurements. Changes in 24-h EE (DIT) and CBT compared to fasting were assessed during three normal-protein (20%) diets using a cross-over design: one eucaloric diet (EBL, 50% carbohydrate, n = 37) and two overfeeding diets with 200% energy requirements: a high-fat (FNP, 60% fat, n = 25) and a high-carbohydrate (CNP; 75% carbohydrate, n = 24) diet. ResultsThe average 24-h CBT (avgCBT) during fasting was 36.81 ± 0.14 °C (inter-individual CV = 0.4%) and positively correlated with 24-h urinary epinephrine (r = 0.61, p < 0.001), but not with body composition measures (p > 0.05). AvgCBT increased during EBL (Δ = 0.06 ± 0.11 °C, p = 0.002), FNP (Δ = 0.13 ± 0.14 °C, p < 0.001), and CNP (Δ = 0.19 ± 0.13 °C, p < 0.001) and associated with increased DIT during EBL (r = 0.43, p = 0.01, β = 31 kcal/day/0.1 °C) and FNP (r = 0.60, p = 0.002, β = 43 kcal/day/0.1 °C), but not CNP (p = 0.47). A ceiling effect for the increase in CBT, but not in DIT, was observed during feeding and, particularly, overfeeding. ConclusionsCBT increases with feeding and is moderately associated with DIT to a different degree depending on the macronutrient composition of the overfeeding diet. There is a ceiling effect such that individuals with a higher CBT during fasting have limited capacity to increase CBT with feeding. Because of body thermoregulatory mechanisms that maintain a constant CBT, these results indicate that CBT has a limited role in the inter-individual variability in DIT.

Fasting enhances cold resistance in fish through stimulating lipid catabolism and autophagy.

In a cold environment, mammals increase their food intake while fish decrease or stop feeding. However, the physiological value of fasting during cold resistance in fish is currently unknown. Fasting for more than 48 h enhanced acute cold resistance in zebrafish, which correlated with lipid catabolism and cell damage attenuation. Lipid catabolism and autophagy were necessary for cold resistance in fish and the inhibition of mitochondrial fatty acid β-oxidation or autophagy weakened the fasting-induced cold resistance. Repression of mechanistic target of rapamycin (mTOR) signalling pathway by rapamycin largely mimicked the beneficial effects of fasting in promoting cold resistance, suggesting mTOR signalling may be involved in the fasting-induced cold resistance in fish. Our study demonstrates that fasting may be a protective strategy for fish to survive under cold stress. In cold environments, most homeothermic animals increase their food intake to supply more energy to maintain body temperature, whereas most poikilothermic animals such as fishes decrease or even stop feeding under cold stress. However, the physiological value of fasting during cold resistance in poikilotherms has not been explained. Here, we show that moderate fasting largely enhanced cold resistance in fish. By using pharmacological (fenofibrate, mildronate, chloroquine and rapamycin) and nutritional approaches (fatty acids diets and amino acids diets) in wild-type or specific gene knock-out zebrafish models (carnitine palmitoyltransferase-1b-deficient strain, CPT1b-/- , or autophagy-related protein 12-deficient strain, ATG12-/- ), we verified that fasting-stimulated lipid catabolism and autophagy played essential roles in the improved cold resistance. Moreover, suppression of the mechanistic target of rapamycin (mTOR) pathway by using rapamycin mostly mimicked the beneficial effects of fasting in promoting cold resistance as either the physiological phenotype or transcriptomic pattern. However, these beneficial effects were largely reduced when the mTOR pathway was activated through high dietary leucine supplementation. We conclude that fasting helps fish to resist cold stress by modulating lipid catabolism and autophagy, which correlates with the mTOR signalling pathway. Therefore, fasting can act as a protective strategy of fish in resisting coldness.

Prevalence of Toxoplasma gondii infections in swine of non-tecnified rearing farms of the northeastern region of the state of São Paulo, Brazil and associated risk factors

Toxoplasmosis is a zoonosis present worldwide. Its protozoal aethiological agent, Toxoplasma gondii, has the ability to infect several homeothermic animals and mainly human beings. The consumption of raw or undercooked meat products containing T. gondii cysts, consumption of vegetables without washing and using non-treated water are risk factors associated to the occurrence of human toxoplasmosis. Furthermore, raw or undercooked pork is an important infection source of T. gondii to humans. Due to the importance of toxoplamosis in public health, this study focused on establish the prevalence of the disease in non-technified swine herds in the northeastern region of the State of São Paulo, Brazil, using Modified Agglutination Test (MAT) and the Indirect Immunofluorescence Assay (IFA) and the risk factors for its occurrence. In addition, the agreement among both diagnostic tests was evaluated. A low prevalence of toxoplasmosis was found at animal level (7.02%). The Fisher's exact test detected correlation between positive cases with the presence of food garden in the farm (p = 0.01) and the use of non-treated water to irrigate the food garden (p = 0.005). The agreement among tests was considered moderate (Kappa index = 0.5). The results show that toxoplasmosis is a risk for humans who consume under cooked pork meat in this region and an acceptable agreement between MAT and IFA tests.

Pupillary stress index: A new thermal comfort index for crossbred goats

ABSTRACT Goats are homeothermic animals considered as rustic from the bioclimatic point of view, but the reduction of their productive efficiency may occur in unfavorable thermal conditions. The present study was carried out to evaluate pupil dilation as an indicator of thermal stress in Boer crossbred goats maintained under controlled environmental conditions. Six male crossbred goats of the Boer breed were distributed in a completely randomized design submitted to temperatures of 26, 29 and 33 °C. The pupillary dilation and pupillary temperature, respiratory frequency, heart rate, surface and rectal temperatures were monitored. The significant increase in physiological responses occurred in response to the increase in air temperature. An increase of pupillary dilation was observed in the animals with the elevation of the air temperature, with an increase of 26.96 mm2 in pupillary area when comparing the temperatures 26 and 33 °C, and it was possible to establish a correlation between air temperature and pupillary diameter increase, named pupillary stress ratio (PSR).

Kinetic and Thermodynamic Characteristics of Lactate Dehydrogenase in Skeletal Muscles of Homeo- and Heterothermic Animals at Low Body Temperatures

Kinetic and thermodynamic characteristics of lactate dehydrogenase (LDG) in skeletal muscles were analyzed in homeothermic animals (rats) under deep (20°C) artificial hypothermia and in heterothermic animals (ground squirrels) under natural hypothermia (hibernation). It was found that, despite different etiology of hypothermic states, changes in some LDG parameters both in homeo- and heterothermic animals at low body temperatures are unidirectional: the catalytic efficiency decreases, the optimum point on the concentration curve shifts towards higher concentrations, efficient activation energies and Ki values increase. At the same time, multidirectional changes in LDG Vmax and KM values as well as the degree of their manifestation in rats versus ground squirrels at low body temperatures indicate that the mechanisms, which regulate activity of this enzyme in animals with diverse strategies of thermal adaptation, are quite different.

Exposure to hot and cold environments increases noradrenaline release in the bed nucleus of the stria terminalis in rats.

AimsThermoregulatory responses in homeothermic animals, including humans, are classified into involuntary autonomous and voluntary behavioral thermoregulatory responses. Although behavioral thermoregulatory responses are probably driven by positive (pleasant) and/or negative (unpleasant) emotions, the neuronal mechanisms underlying the induction of negative emotions by hot and cold environments remain poorly understood. The bed nucleus of the stria terminalis is a brain region implicated in stress responses and negative emotions, such as fear, anxiety, and aversion. Various stimuli that cause negative emotions, such as immobilization stress, fox odor, gastric distension, and inflammatory pain, increase noradrenaline release in the rat bed nucleus of the stria terminalis, especially in the ventral bed nucleus of the stria terminalis. It has been reported that the negative emotional component of pain is mediated by noradrenergic neurotransmission in the ventral bed nucleus of the stria terminalis. However, the role of intra‐ventral bed nucleus of the stria terminalis noradrenergic neurotransmission in the induction of negative emotion by exposure to hot and cold environments remains to be elucidated. For the first step to address this issue, the effects of hot and cold environments on noradrenaline release in the ventral bed nucleus of the stria terminalis were examined.MethodsIn vivo microdialysis analyses in unanesthetized, freely moving male Sprague‐Dawley rats were performed to examine hot and cold environments‐induced noradrenaline release in the ventral bed nucleus of the stria terminalis.ResultsExposure to hot (38°C) and cold (8°C) environments significantly increased noradrenaline release in the ventral bed nucleus of the stria terminalis.ConclusionsThe results suggest that exposure to hot and cold environments enhances noradrenergic neurotransmission in the ventral bed nucleus of the stria terminalis, which may induce negative emotion, and thereby drive avoidance behaviors, that is, escape from hot and cold environments.

Effect of Temperature on Metabolism and Lifespan in Several Homeothermic Animals

The effects of various parameters on metabolism was analyzed in several homeothermic animals, including mammals, passerine birds, and humans. A Boltzmann equation was obtained for the basal metabolic rate, with the activation energy coinciding in magnitude with the energy of enzymatic cleavage of macroergic P–O bonds in adenosine triphosphate acid molecules. A dependence was obtained to relate the lifespan with the body temperature, body mass, basal metabolic rate, and Rubner’s constant.

Does Basal Metabolism Set the Limit for Metabolic Downregulation during Torpor?

The evolution of endothermic thermoregulation is rooted in the processes involving high metabolism, which allows the maintenance of high and stable body temperatures (Tb). In turn, selection for high endothermic metabolism correlates with increased size of metabolically active organs and thus with high basal metabolic rate (BMR). Endothermic animals are characterized by an MR several times that of similar-sized ectotherms. However, many small mammals are temporally heterothermic and are able to temporally decrease Tb and MR by entering daily torpor or hibernation. Both BMR and minimum MR during torpor (TMRmin) likely result from oxidative respiration in mitochondria of the same tissues. It should be expected that these two MRs are positively correlated, suggesting that the evolution of endothermy and higher BMR set the limit for the ability to reduce MR while entering torpor. Using published data for 96 mammal species, we tested the hypothesis that, among heterothermic mammals, the processes leading to the evolution of higher BMR limit the ability to downregulate metabolism during torpor. We found that body mass (mb)-adjusted BMR was positively correlated with mb- and Tb-adjusted TMRmin, in a phylogenetically corrected analysis. Phylogenetic path modeling indicated that the mechanisms underlying the evolutionary increase of BMR in endotherms most likely constrain their ability to reduce MR during torpor. Given that heterothermy is considered an ancestral state in mammals, these results suggest an increase in BMR during the evolution of endothermy in homeothermic animals, which leads to the loss of their ability to enter torpor.

Poikilothermic Animals as a Previously Unrecognized Source of Fecal Indicator Bacteria in a Backwater Ecosystem of a Large River.

Quantitative information regarding the presence of Escherichia coli, intestinal enterococci, and Clostridium perfringens in poikilotherms is notably scarce. Therefore, this study was designed to allow a systematic comparison of the occurrence of these standard fecal indicator bacteria (SFIB) in the excreta of wild homeothermic (ruminants, boars, carnivores, and birds) and poikilothermic (earthworms, gastropods, frogs, and fish) animals inhabiting an alluvial backwater area in eastern Austria. With the exception of earthworms, the average concentrations of E. coli and enterococci in the excreta of poikilotherms were equal to or only slightly lower than those observed in homeothermic excreta and were 1 to 4 orders of magnitude higher than the levels observed in the ambient soils and sediments. Enterococci reached extraordinarily high concentrations in gastropods. Additional estimates of the daily excreted SFIB (E. coli and enterococcus) loads (DESL) further supported the importance of poikilotherms as potential pollution sources. The newly established DESL metric also allowed comparison to the standing stock of SFIB in the sediment and soil of the investigated area. In agreement with its biological characteristics, the highest concentrations of C. perfringens were observed in carnivores. In conclusion, the long-standing hypothesis that only humans and homeothermic animals are primary sources of SFIB is challenged by the results of this study. It may be necessary to extend the fecal indicator concept by additionally considering poikilotherms as potential important primary habitats of SFIB. Further studies in other geographical areas are needed to evaluate the general significance of our results. We hypothesize that the importance of poikilotherms as sources of SFIB is strongly correlated with the ambient temperature and would therefore be of increased significance in subtropical and tropical habitats and water resources.IMPORTANCE The current fecal indicator concept is based on the assumption that the standard fecal indicator bacteria (SFIB) Escherichia coli, intestinal enterococci, and Clostridium perfringens multiply significantly only in the guts of humans and other homeothermic animals and can therefore indicate fecal pollution and the potential presence of pathogens from those groups. The findings of the present study showed that SFIB can also occur in high concentrations in poikilothermic animals (i.e., animals with body temperatures that vary with the ambient environmental temperature, such as fish, frogs, and snails) in an alluvial backwater area in a temperate region, indicating that a reconsideration of this long-standing indicator paradigm is needed. This study suggests that poikilotherms must be considered to be potential primary sources of SFIB in future studies.