Homoiothermic Animals Research Articles

CALCIUM-ACCUMULATING ABILITY OF RAT LIVER MITOCHONDRIA DURING HYPOTHERMIA OF VARIOUS DURATIONS

Calcium is one of the most important intracellular messengers that regulate physiological and biochemical processes in the cell. Mitochondria are able to deposit calcium ions and are involved in the regulation of the calcium signal. Hypothermic conditions in homoiothermic animals can lead to disruption of this important function of mitochondria and pathological consequences. The aim of this study is to study the effects of moderate (30°C) hypothermia of varying duration on the calcium-accumulating capacity of rat liver mitochondria. The experiments were carried out on male rats Wistar. Hypothermia was induced by external cooling of the animals in Plexiglas chambers with a jacket through which cold water circulated. Mitochondria were isolated from the liver of decapitated rats by differential centrifugation. The calcium-accumulating capacity of mitochondria was assessed by the kinetics of calcium-induced swelling of mitochondria and their calcium capacity. A study of the kinetics of calcium-induced swelling of mitochondria showed that during short-term moderate (30°C) hypothermia, the rate of swelling of mitochondria decreases, prolongation of hypothermia to 1 h contributes to a further decrease in the swelling rate, and to 3 h, its normalization. A positive correlation was found between the rate of calcium-induced swelling and the calcium capacity of mitochondria (r = 0.79). Thus, with prolonged exposure to the cold factor in rats, a number of compensatory-adaptive reactions are activated. The decrease in the rate of Ca2+ – induced swelling and calcium capacity of mitochondria at the initial stages of hypothermia may be associated with the formation of mitochondrial pores and is reversible.

Seroprevalence and risk factors of Toxoplasma gondii infection in domestic raccoon dogs in four provinces in northern China

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that can infect almost all homoiothermal animals, including domestic raccoon dogs (Nyctereutes procyonoides). However, related reports on T. gondii infection in domestic raccoon dogs were limited in China. Therefore, a serological investigation was undertaken to investigate the seroprevalence and risk factors for T. gondii infection in domestic raccoon dogs. A total of 962 serum samples were collected from Jilin, Liaoning, Heilongjiang and Hebei provinces, northern China between April 2016 and November 2017, and were detected by the indirect hemagglutination test (IHA). The seroprevalence of T. gondii infection was 7.28% in the overall surveyed raccoon dogs by IHA, which was different among the four provinces ranging from 6.54% to 7.57%. The seroprevalence of T. gondii infection in male and female raccoon dogs was 6.62% and 7.79%, respectively. Based on statistical analysis, age was regarded as an important risk factor for T. gondii infection in raccoon dogs in this study (P < 0.05). This study reported the seroprevalence and risk factors of T. gondii infection in domestic raccoon dogs in northern China, which provided essential data for prevention and control of T. gondii infection in raccoon dogs in Jilin province, Liaoning province, Heilongjiang province and Hebei province.

Functionally significant low-temperature structural alterations in mitochondrial membranes of homoiothermic animals

This work is focused on the physicochemical nature and functional meaning of structural alterations in mitochondrial membranes. These alterations are observed at subnormal temperatures for homeothermic animals. Using pyrene as a fluorescent probe, some structural transitions in annular lipids were detected at 19 and 25°C, which are identified as the pre-transition and main phase transition temperatures. The observed changes are consistent with abrupt alterations in the efficiency of tryptophan fluorescence quenching by pyrene that occur at the same temperatures. The data imply considerable changes in the protein–lipid contact area. The effects are observed under low-amplitude mitochondrial swelling in media with lowered tonicity. Since the transition of the phosphorylating system into the supercomplex state has been previously shown under these conditions, it allows us to assume a relationship between the observed membrane structural alterations and the supercomplex formation. Measurements of the respiration rate in mitochondria in a hypoosmotic medium show that the activation energy of the rate-limiting step in the process of ATP synthesis changes abruptly at the temperature of the phase transition of annular lipids (25°C). Analysis of the literature data indicates that a similar abnormal low-temperature abrupt change in activation energy in the reaction of ATP synthesis around 25°C is observed for a variety of animal species. Hence, the low-temperature structural alterations in membranes of warm-blooded animals should have general biological importance. A comparison of the results obtained in our study and the literature data led, therefore, to a qualitative description of the physiochemical nature of the observed membrane alterations. Similar to the membrane-raft model, a model of supercomplex formation in mitochondria is proposed.

Intra-specific Body Size Variation of Ground Beetles (Сoleoptera: Сarabidae) in Latitudinal Gradient

Background. Large-scale patterns of body size variation have occupied biologists for over a century, yet the causes of some of these patterns remain elusive. Bergmann’s rule is a classical eco-geographic rule that relates body size of homoiothermal animals with environmental temperature (or latitude). Contemporary data indicate that latitudinal clines in body size, predicted by Bergmann’s rule also exist in ectothermic organisms and in some groups appear to be fairly common. Despite plenty of data from literature on latitudinal intraspecific body size variation in insects are scarce and in Ground Beetles are absent at all. The aim of this research was to: (i) model the effect of the region of habitation into the body size variation in widespread carabid species; (ii) describe body size variation of mentioned species in latitudinal gradient. Materials and methods. The design of our study was organized as follows: (1) we study the intraspecific variation of body size in carabids, bearing in mind that closely related species could act very differently, each individual species following or countering Bergmann's Rule in its own way; (2) in all studied species the same six traits were measured; (3) we used linear models to isolate concretely latitude effects (but not another environmental factors) to traits variation; (4) beetles were sampled in the same space over the vast regions covering their ranges. Six carabid species from different regions of Russia were analyzed. Linear models were applied to quantify contribution of region’s latitude where beetles had been sampled into that variation. We applied voice-counting method to reveal trends of traits size variation in latitude gradient and relative warp analysis (a principal component analysis of the weight matrix) when analyzing effect of latitude on body shape shifts in studied species of carabids. Results. Different traits of certain species varied in differing ways under the influence of the same environmental factor. Contribution of latitude into the traits variation was not similar in studied species. The compiled data over the all six traits variation in latitude gradient in each species showed that C. granulatus followed Bergmann's rule, P. cupreus – converse Bergmann's rule, in C. cancellatus, C. hortensis and P. melanarius the number of cases which followed direct Bergmann's clines, converse ones and non-significant shifts were equal, P. niger - didn't show any clines at all. Nevertheless the separate analysis of the only elytra length variation showed that in three Carabus species and P. niger elytra length decreased towards the high latitudes, P. melanarius demonstrated saw-tooth elytra length variation in latitude gradient and Poec. cupreus – the counter-gradient one. Conclusion . Explanation that takes into account the natural history, climatic correlations and sexual size dimorphism is needed to assess the observed contrasting geographic patterns and differences between species, morphometric traits and sexes, since size clines (e.g. Bergmannian clines) may obey to multiple selection pressures that are not only dependent on temperature constraints but also on other climatic and biotic factors that could influence body size. Key words: carabids, environmental factors, voice-counting method, converse Bergman clines, saw-tooth variation, counter-gradient variation, linear models.

Temperature imbalance and fever

The ability to have a body temperature that is independent of environment temperature is evolutionary acquisition. Thanks to him, organisms can control the intensity of metabolism to increase body temperature. Homoiothermic animals can maintain an optimum body temperature via the heat transfer into the environment. An optimal level of temperature is necessary for activity of most enzymes, the implementation of metabolic reactions in cells. The viscosity of blood and extracellular fluids, the surface tension of the surfactant, swelling colloids of the interstitial space depend on the temperature inside. The excitation of cells, muscle contraction, secretion, absorption, locomotor activity and phagocytic properties of neutrophils also depend on the temperature of the tissues. Fever is pathological process a temporary increasing of body temperature for homoiothermal animals and humans. The process starts due to cytokines exogenous and endogenous origin. Cytokines rebuild the system of thermoregulation. Fever is protective response to damaged but may be redundant. Tachycardia at a fever promotes arrhythmias and may be complicated by the development of acute heart failure. Critical temperature decrease with profuse sweating can cause collapse. Fever in pregnant women in the early stages of placentation provokes violations and defects of the neural tube of the embryo. Fever leads to accumulation of ketonic substances in the blood due to incomplete lipolysis. Ketoacidosis with fever in young patients is the cause of hyperthermic convulsions. The negative effects of fever forced to resort to antipyretic therapy and measures to increase heat dissipation.

Erythrocytes of hetero- and homoiothermic animals under natural and artificial hypothermia

Using low-angle light scattering technique, the features of erythrocyte transformation dynamics (osmotic fragility, the hemolysis level and ratio of different cell forms determined by the spherical index) were revealed in hetero- (golden hamsters Mesocricetus auratus) and homoiothermic (white rats Rattus norvegicus) animals under natural (hibernation) and artificial (suspended animation) hypometabolic states, craniocerebral and immersion hypothermia. In control, golden hamsters exhibited higher levels of erythrocyte osmotic fragility and hemolysis than rats, with transformed erythrocytes (especially stomatocytes) being prevalent. Under artificial hypothermia, regardless of the way of its attaining, depth and duration, the changes were observed that were similar in their directionality but dissimilar in the degree of manifestation: increased osmotic fragility and hemolysis, reduced portion of discocytes (particularly sharp in golden hamsters under suspended animation), increased number of transformed erythrocytes. In contrast, under hibernation the osmotic fragility, hemolysis and number of stomatocytes decreased, the portion of discocytes increased, while the number of prehemolytic forms (spherocytes) also increased. In 24 h, both the osmotic fragility (stronger in hamsters after suspended animation) and the level of hemolysis (particularly after immersion hypothermia) decreased, the portion of discocytes recovered (even exceeding the control level in hamsters after suspended animation and in rats after immersion hypothermia), spherocytes were not detectable in hamsters but elevated in rats. It is likely that the qualitative changes in the erythrocyte population towards its homogeneity detected 24 hours after hypothermia may be mediated not only by the elimination of old and defective cells, erythropoiesis activation and production of high-resistant erythrocytes but also by the fine membrane-stabilizing mechanisms.

The fatty acid composition of phospholipids and absorption spectra of lipid extracts from lamprey, frog, and rat erythrocytes

The work studies the content and fatty acid composition of phospholipids as well as the absorption spectra of lipid extracts from red blood cells of poikilothermal and homoiothermal animals at different evolutionary levels. The objects of study include two poikilothermal species, the river lamprey (Lampetra fluviatilis) that uses oxygen dissolved in water, and the common frog (Rana temporaria) that consumes oxygen both from water and from air. A homoithermal animal is the white rat (Rattus rattus) that inhabits the terrestrial-aerial environment. The animals are studied in winter and spring. The phospholipid content in lamprey blood plasma is found to be twice higher than that in its erythrocytes. In the frog and the rat, the ratio is reverse. Determination of the fatty acid lipid composition of red blood cell phospholipids suggests that membranes in the lamprey are denser than in the frog. As for the fatty acids in the erythrocyte fraction of rat blood, they appear to be less diverse, with a double prevalence of saturated acids over unsaturated ones and devoid of long chain (C22) ω3 fatty acids. All of this results in a lower degree of unsaturation and a denser packing of fatty acids in the membrane structures of rat erythrocytes. The mechanism of reversible binding of O2 molecules to hemoglobin in erythrocytes is discussed. Presumably, the mechanism of interaction between molecules of O2 and molecules of water prevents the exchange interaction of electrons of the hemoglobin iron atoms with an oxygen molecule. This is confirmed by our obtained absorption spectra, which show that in the lipid extract almost totally devoid of water the heme isolated from erythrocytes is converted to hemin.

Effects of Pharmacological Activation of TRPM8 Ion Channels on the Thermoregulatory Responses during Warming

Preliminary non-thermal activation of cold-sensitive TRPM8 ion channel facilitates initiation of the heat-defense responses in homoiothermal animals by decreasing temperature threshold of the vasodilatory response. TRPM8 activation leads to earlier heat-initiated increase in oxygen consumption, but reduces its magnitude. Warming inhibits the lipolytic effect of menthol activation of TRPM8 observed under thermoneutral conditions. Thus, modulation of the skin temperature afferent signal by ion channel agonist TRPM8 changes not only cold-defense, but also heat-defense responses of the body.

Substrate-inhibitory analysis of monoamine oxidase from hepatopancreas of the octopus Bathypolypus arcticus

Study of the substrate-inhibitory specificity of mitochondrial monoamine oxidase (MAO) of hepatopancreas of the octopus Bathypolypus arcticus revealed distinctive peculiarities of catalytic properties of this enzyme. The studied enzyme, on one hand, like the classic MAO of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, beta-phenylethylamine, while, on the other hand, deaminates histamine and does not deaminate putrescine--classic substrates of diamine oxidase (DAO). Results of the substrate-inhibitory analysis with use of chlorgiline and deprenyl are indirect proofs of the existence in the octopus hepatopancreas of one molecular MAO form. Semicarbazide and pyronine G turned out to be weak irreversible inhibitors, four derivatives of acridine--irreversible inhibitors of the intermediate effectiveness with respect to the octopus hepatopancreas MAO; specificity of action of inhibitors at deamination of different substrates was equal.

Physiological effects of hypoxia in developing and adult honeybees Apis mellifera L.

The effect of hypoxia on activity of metabolism was studied in developing and adult honeybees. The feedback was established between the O2 deficit in the gas medium and its consumption by honeybees. An elevation of temperature within the limits of vital diapason for development of honeybees activated O2 consumption regardless of the hypoxia level. A prolonged action of hypoxia on the O2 physiological state was revealed. There was shown the existence of convergent similarity between the effect of O2 deficit on honeybees and on homoiothermal animals.

Catalytic characteristics of monoamine oxidase of whitefish Coregonus lavaretus ludoga

Study of substrate-inhibitory specificity of liver mitochondrial monoamine oxidase (MAO) of sexually mature individuals of the whitefish Coregonus lavaretus ludoga P. from the Ladoga Lake has revealed distinguished peculiarities of catalytical properties of this enzyme. The studied MAO, on one hand, like the classical enzyme of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, and beta-phenylalanine, but, on the other hand, to deaminate histamine, the classic substrate of diamine oxidase. The found equal activity and sorptional ability of the enzyme toward six studied substrates including histamine, as well as results of the substrate-inhibitory analysis with use of specific inhibitors--deprenyl and chlorgilin--indicate homogeneity of the enzyme. The detected for the first time among the fish MAO wide substrate specificity and an unusually low sensitivity to both studied acetylene inhibitors does not allow ascribing unanimously the studied enzyme to the known MAO forms of organs and tissues of homoiothermal organisms. Apparently, the revealed enzyme form of poikilothermal organism is not the true MAO, but performs a large amine oxidase function.

Dissecting the key residues crucial for the species-specific thermostability of muscle-type creatine kinase

Species-specific protein thermal stability is closely correlated to the living conditions of the organism, especially to its body temperature. In this research, human and zebrafish muscle-type creatine kinases (MMCKs) were taken as model proteins to investigate the molecular adaptation of proteins in poikilothermal and homoiothermal animals. Both the optimal temperature for catalysis and the thermal stability of human MMCK was much higher than those of zebrafish MMCK. Sequence alignment identified 9 amino acid variations conserved in either the teleost MMCKs or the mammal and electric ray MMCKs. Bidirectional mutations were performed to find the residues with beneficial mutations. The results showed that two residues close to the dimer interface of MMCK, the 46th and 146th residue, were crucial for species-specific thermal stability.

Peculiarities of synaptic vesicle recycling in frog and mouse motor nerve terminals

Using electrophysiology and fluorescence microscopy (dye FM1-43), comparative study of neurotransmitter secretion, synaptic vesicle exo-endocytosis, and recycling has been carried out in frog and mouse motor nerve terminals during a long strong stimulation (3 min; 20 imp/s). The obtained data have revealed three synaptic vesicle pools and two recycling ways existing on motor nerve terminals. The strong stimulation induced consecutive depletion of readily releasable, mobilized, and reserve vesicle pools of frog nerve terminals. The exocytosis rate exceeded the endocytosis rate; predominant was the slow synaptic vesicle recycling that replenished the reserve pool. In mouse nerve endings, vesicles of the readily releasable and mobilized pools were only exocytosed, the pools being replenished by fast recycling. At the same time, exo- and endocytosis occurred nearly in parallel and vesicles of the reserve pool did not participate in the neurotransmitter secretion. In is suggested that evolution of motor nerve terminals was directed to a decrease of the vesicle pool size, economic spending, and effective reuse of synaptic vesicles. This is achieved by an increase of endocytosis and recycling rates. These features can provide a long maintenance of a quite level of neurotransmitter secretion in nerve terminals of homoiothermal animals to preserve reliability of synaptic transmission during the high-frequency activity.

Diencephalo-telencephalic changes of tyrosine hydroxylase in rats and grass frogs after sleep deprivation

Based on sleep deprivation-produced changes of electrographic parameters of the wakefulness-sleep cycle (WSC) in rats and frogs (Rana temporaria), dynamics of activity of tyrosine hydroxylase, the key enzyme of dopamine synthesis, was studied immunohistochemically in substantia nigra and nigrostriatal pathway in rats and in striatum, paraventricular organ, and extrahypothalamic pathways in frogs. Changes in dynamics of tyrosine hydroxylase in rats and in frogs are revealed after the 6-h sleep deprivation and after 2 h of postdeprivation sleep. This allows determining the degree of participation of corticostriatal neuroregulatory and hypothalamo-pituitary neurosecretory systems and their role in regulation of WSC. Possible evolutionary peculiarities of morphofunctional differences in homoiothermal and poikilothermal animals are discussed.

Peculiarities of Ca2+-regulation of functional activity of myocardium of frog Rana temporaria

To elucidate role of intra- and extracellular Ca2+ in regulation of rhythm and strength of frog heart contractions, there were studied ECC and isometric contraction of myocardium preparations in response to verapamil, adrenaline, and blockers of alpha- and beta-adrenoreceptors. It has been shown that after an intramuscular injection of verapamil (6 mg/kg), bradycardia develops, the heart rate (HR) decreasing by 50-70 %. Further, the cardiac arrest occurred; however, administration to the animals of adrenaline (100 mg/kg) restored the cardiac rhythm for a short while. After an intramuscular injection of adrenaline at doses of 0.1-10 mg/kg, no essential changes were observed in the potential action amplitude and HR; an increase of the administered adrenalin concentration to 100 mg/kg was not accompanied by the cardiac rhythm stimulation, as this takes place in homoiothermal animals and human; on the contrary, an essential HR deceleration was revealed. Phentolamine (5 mg/kg) gradually decelerated HR rhythm by 32-45 %. The potential amplitude changed insignificantly. A subsequent intracardiac injection of adrenaline (100 mg/kg) on the background of block of alpha-adrenoreceptors produced acceleration of the rhythm (by 13-21%) and fall of the electrogram amplitude. These results can indicate that in the frog heart, phentolamine interacts predominanty with alpha-adrenoreceptors. An intracardiac administration of propranolol (1 mg/kg) to frogs promoted inhibition of beta-adrenergic receptors and produced a gradual cardiac rhythm deceleration. In experiments on assessment of verapamil effect on the character of contractions this preparation at a concentration of 150 microM was established to produce a significant dosedependent decrease of the contraction strength. A rise of verapamil concentration in the sample to 200 microM led to a decrease of the amplitude, on average, by 68-70 % and in individual preparations -- by 80-85 %; however, administration into the sample of adrenaline (10 microM) restored the cardiac contraction strength. Adrenaline (1 nM--100 microM) increased markedly the contraction amplitude. Phentolamine (10 microM) did not inhibit transmission of contractile signal to cardiomyocytes; this was manifested in that the contraction amplitude after addition of adrenaline (10 microM) into the sample was approximately the same as in the sample containing no phentolamine. Propranolol (10 microM) eliminated the stimulatory action of adrenaline (10 microM). The results of these experiments indicate that in the frog ventricular cardiomyocytes the main adrenaline acceptors are beta-adrenoreceptors.

Peculiarities of digestive function of proteinases in invertebrates—Inhabitants of cold seas

Digestive proteinases of various taxa of invertebrates of the boreal seas have been studied: crustaceans Paralithodes camtchaticus, Pandalus borealis; molluscs Chlamys islandicus, Buccinum undatum, Serripes groenlandicus, and echinoderms Strongylocentrotus droebachiensis, Cucumaria frondosa, Asterias rubens, and Crossaster papposus. The presence of two proteolytic activity peaks in the acidic (pH 2.5–3.5) and lower alkaline ranges (pH 7.5–8.5) and a similar proteinase spectrum have been revealed in digestive organs of the studied animals. The proteolytic activity in digestive organs of the Barents Sea invertebrates exceeds significantly that of terrestrial homoiothermal animals, which seems to be an extensive compensation for poor differentiation of the digestive system and for low substrate specificity of the enzymes as well as for cold conditions of the habitat. The principal qualitative difference between vertebrates and invertebrates consists in that the latter have no pepsin activity, but do have the cathepsin activity that is absent in vertebrate digestive organs. Contribution to the acid proteolysis is made by lysosomal cathepsins, rather than by pepsins. Activity in the alkaline and neutral pH ranges is provided by serine proteinases. In digestive cavities of invertebrates, hydrolysis of proteins and mechanical processing of food occur only in the lower alkaline pH range, whereas acid proteolysis has intracellular lysosomal localization.

Content of the main lipid components in blood serum lipoproteins of human and of some animal species

Using precipitation method, low-density (LDL) and high-density (HDL2 and HDL3) lipoproteins were isolated from blood serum of human (donors, patients with ischemic heart) diseases--IHD, with bronchial asthma--BA, with chronic obstructive bronchitis--COB), of mammals predisposed (pig, rabbit) and resistant (rat, mink, Arctic fox) to atherosclerosis, of birds (hen, pigeon), of bony fish (trout, white-fish, pike-perch, pike, bream, burbot), and of cartilaginous fish (sturgeon, white sturgeon). From each lipoprotein group, lipids were extracted, separated by thin-layer chromatography, and analyzed quantitatively by the spectrophotometric method. In phosphatidylcholine and HDL2 cholesterol esters, bound fatty acids (FA) were determined by the method of gas-liquid chromatography. The main amount of total cholesterol has been established to be concentrated in human LDL, especially in the cases of IHD, and in LDL in mammals predisposed to atherosclerosis. In mammals resistant to atherosclerosis and in fish the almost entire cholesterol was revealed in HDL. The phospholipid content in HDL was lower in patients with pathologies and in mammals predisposed to atherosclerosis, while the highest content--in fish and mammals resistant to atherosclerosis. In homoiothermal animals and in human the main FA amount in HDL was represented by the omega6-series. Acids of the omega3-series amounted to a negligible percentage, especially in IHD. On the contrary, the HDL FA composition of poikilothermal animals (fish) had a very high content of polyunsaturated FA of the omega3-series. A conclusion is made that composition of lipid components in animal lipoproteins by the example of several studied species and of human has a non-stable character and is submitted to changes. Their most pronounced modifications with a negative trend took place in human LDL and HDL in IHD.

Trichinella papuae and Trichinella zimbabwensis induce infection in experimentally infected varans, caimans, pythons and turtles.

The discovery of Trichinella zimbabwensis in farm crocodiles of Zimbabwe has opened up a new frontier in the epidemiology of the Trichinella genus. The objective of the present study was to investigate the infectivity of encapsulated species (T. spiralis, T. nativa, T. britovi, T. murrelli and T. nelsoni) and non-encapsulated species (T. pseudospiralis, T. papuae and T. zimbabwensis) in caimans (Caiman crocodilus), varans (Varanus exanthematicus), pythons (Python molurus bivittatus) and turtles (Pelomedusa subrufa) raised at their natural temperature range (26-32 degrees C). Mice and chickens were used as controls. At 6 days post-infection (p.i.), adult worms were detected in the small intestine of reptiles infected with T. papuae and T. zimbabwensis, of chickens infected with T. pseudospiralis and of mice infected with all encapsulated and non-encapsulated species. At 60 days p.i., T. papuae and T. zimbabwensis adult worms were collected from the intestine of varans and caimans and larvae from muscles of the four reptile species, T. pseudospiralis larvae from muscles of chickens, and larvae of all Trichinella species from mouse muscles. The highest reproductive capacity index of both T. papuae and T. zimbabwensis was observed in varans. The results show that T. papuae and T. zimbabwensis are able to complete their entire life-cycle in both poikilothermic and homoiothermic animals.

A new view on the role of phospholipids fatty acids: Possibility of electric charge transfer in the membrane monolayer

The fatty acid composition of phospholipids of subcellular fractions that are both generators and consumers of energy, mitochondria, synaptosomes, and myelin, has been studied in the brain and liver of several representatives of poikilothermal and homoiothermal vertebrates. The terrestrial poikilothermal animals have been shown to be close to homoiothermal animals by the main characteristics of membranes of the subcellular fractions, such as the content of saturated acids, the unsaturation index, and the ω3/ω6 acid ratio, but differ essentially from aquatic poikilotherms. The conclusion is made that the similarity in the fatty acid characteristics of the terrestrial poikilothermal and homoiothermal vertebrate membranes is due to their inhabitation in the oxygen-rich environment, while differences in intensity of the oxygen consumption are due to their different body temperatures. The models of structure of an arbitrary fragment of the lipid component of the studied trout membranes are presented, which illustrate a concept of a new functional role of fatty acids as participants of the electron transfer chain in the membrane.

Urease-positive thermophilic strains of Campylobacter isolated from seagulls (Larus spp.).

Three strains of urease-positive thermophilic Campylobacter (UPTC), designated A1, A2 and A3, were identified by biochemical characterization after isolation from faeces of seagulls in Northern Ireland in 1996. The biochemical characteristics of the strains were identical to those of strains described previously. Analysis by pulsed-field gel electrophoresis (PFGE) after separate digestion with ApaI and SmaI demonstrated that the respective PFGE profiles were indistinguishable. The PFGE analysis also suggested that the genomes were approximately 1810 kb in length. This is the first example of the isolation of UPTC from flying homoiothermal animals, i.e. from seagulls (Larus spp.).