Poikilothermic Animals Research Articles

Entropy and Efficiency of Growth in Marine Fish Species of the Arctic

The mechanisms of the energy exchange processes in fish inhabiting high-latitude regions of Arctic were investigated on the basis of our native experimental data and literature knowledge. It is shown that energy consumption per unit of growth becomes more sparing when they grow slower (low specific growth rate). In this case, the growth process of fish at lower temperatures becomes more and more efficient, and they can grow with minimal energy expenditure. At low temperatures, internal processes slow down and waste accumulates more slowly, which leads to the release of less excess heat generated by metabolic processes and daily activities. In poikilothermic animals, this strategy of using low-entropic energy and "dumping" high-entropic heat at low temperatures is very effective.

Mild cold stress specifically disturbs clustering movement of DFCs and sequential organ left-right patterning in zebrafish.

In poikilothermic animals, the distinct acclimatization ability of different organs has been previously addressed, while the tissue-specific role of cold stress in early development is largely unknown. In this study, we discovered that despite its role in delaying embryonic development, mild cold stress (22°C) does not disturb multiple-organ progenitor specification, but does give rise to organ left-right (LR) patterning defects. Regarding the mechanism, the data showed that mild cold stress downregulated the expression of cell-adhesion genes cdh1 and cdh2 during gastrulation, especially in dorsal forerunner cells (DFCs), which partially disturbed the clustering movement of DFCs, Kupffer’s vesicle (KV) morphogenesis, and ciliogenesis. As a result, the defects of KV/cilia disrupted asymmetric nodal signaling and subsequent heart and liver LR patterning. In conclusion, our data novelly identified that, in early development, DFCs are more sensitive to mild cold stress, and mild cold stress repressed the expression of cell adhesion-related gene cdh1 and cdh2. This role partially disturbed the clustering movement of DFCs, which resulted in defective KV/cilia development and sequential organ LR patterning defects.

Regulatory Effect of Thyroxine on Calcium and Phosphorus Metabolism in Tissues of Common Indian Toad

Thyroxine (T4) plays a vital role in the metabolic processes of animals. It influences the storage and mobilisation of minerals and their utilisation according to the requirement of the body. It is also involved in the early development of vertebrates, especially in amphibian metamorphosis. It has shown anabolic and catabolic effects at a lower dose and higher dose, respectively. The present study aims to identify the role of thyroxine in regulating calcium and phosphorous metabolism in the blood, muscle and bone tissues of Bufo melanostictus. Toads of various sizes and different age groups were chosen, showing a positive correlation between body weight and snout to vent length, indicating overall continuous growth as observed for a large number of poikilothermic animals. As per an earlier report, thyroxine has been shown to have a direct catabolic effect on bone mineral homeostasis leading to an increase in bone mineral resorption and calcium loss through the kidney. Results of the present study indicate that thyroxine treatment in Bufo melanostictus caused depletion of calcium and phosphorous in muscle and bone, while their level increased in the serum at both doses (0.5 μg/gm and 2 μg/gm) during short term i.e. a one-day T4 treatment. Such results are very much consistent with many of the earlier obscurations that, T4 causes an increase in serum calcium and phosphorous levels, while their level in muscle and bone decreased. When the level of these two minerals falls in the serum due to any other condition, the bone resorption under the influence of thyroxine maintains the concentration in serum, consequently, there is a loss in bone density due to resorption and in muscle due to utilisation. However, if the exogenous supply is adequate, the loss caused as above is compensated for, in both bone and muscle.

国内の水産養殖における魚病対策と疫学研究の現状

To understand the biological characteristics of aquatic animals is required for a control of aquatic animal diseases. Aquatic animals including fish, crustacean and shellfish are poikilothermic animals and live in water, and these characteristics are quite different from that of terrestrial animals. Diagnosis and treatment in animals for aquaculture are curried out for whole animals in a facility/farm, but not for individuals except aquarium fish including koi that are much valuable. The purpose of the diagnosis is to identify the cause of death, and targets of the diagnosis are only exogenous diseases.

MODELING OF THE EXTREME INFLU-ENCE OF ENVIRONMENTAL FACTORS ON THE STABILITY OF POIKILOTHERMIC ANIMALS AND THE BASIC PRINCIPLES OF ITS INCREASE

The formulated principles of increasing the resistance of poikilothermic animals are justified. They allow the development of action plans for the sustainable management of fish species, including ways to rehabilitate and control the spread of pathogens. The results of the research are the scientific basis for creating stable communities and populations that allow assessing the impact of negative factors in environmental protection activities and increasing productivity in aquaculture.

Fluidity is the way to life: lipid phase separation in bacterial membranes.

A hallmark of biological membranes is the dynamic localization of lipids and proteins. Lipids respond to temperature reduction below a critical point with phase separation, and poikilothermic animals and also bacteria adapt their lipid content to prevent gel phase formation in membranes. In a new study, Gohrbandt etal (2022) show that reduced membrane fluidity in bacterial cells causes reversible phase separation without membrane rupture invivo, highlighting the physical robustness of biological membranes.

Assessment of Amphibians Vulnerability to Climate Change in China

Global climate change is considered to be one of the main threats to organisms. As poikilothermic animals, amphibians are in particular sensitive because they cannot adapt to the dramatic climate change through active physiological regulation. Using 104 representative species, the present study conducted an assessment of amphibians vulnerability to climate change in China through the combination of two approaches. Specifically, 18 vulnerability criteria belonging to five categories (i.e., thermal tolerance, individual reproductive, population diffusion and diversity, food and habitat, and climate conditions) were first selected and scored based on literatures and experts opinions. Species were then ranked into three levels of climate change vulnerability (i.e., high, moderate, and low) by calculating vulnerability scores and conducting natural breaks analyses, as well as performing a principal coordinate analysis (PCoA) andk-means cluster analyses, respectively. To integrate the two results, a matrix with the ranks from each result was developed to produce a final integrated list. Our results indicated that the 104 amphibian species were classified into three types by natural breaks, with 54 low vulnerable species, 41 moderately vulnerable species, and nine highly vulnerable species. Based on the results of PCoA andk-means cluster analyses, five species were highly vulnerable, 38 species were moderately vulnerable, and 61 species were low vulnerable. The combination of the two ranks suggested that 36 species such asHyla tsinlingensisandLiangshantriton taliangensiswere of low vulnerability, 54 species such asEchinotriton chinhaiensisandHynobius chinensiswere of moderate vulnerability, and 14 species such asIchthyophis kohtaoensisandZhangixalus prasinatuswere of high vulnerability. Overall, our results indicated that climate change could have strong potential effects on amphibians in China. And the highly vulnerable species such asIchthyophis kohtaoensis,Zhangixalus prasinatus, andTheloderma corticaleshould be the priority in future conservation activities.

How does temperature affect aggression during and after dominance hierarchy formation in Nile tilapia?

Social animals commonly establish dominance relationships by means of aggressive interaction, leading to hierarchical stability and priority of access to limited resources by high-ranked individuals. In poikilothermic animals, temperature is a major abiotic factor influencing social and non-social behaviors, including aggression. Here, we investigated the effect of cold temperature on aggression in dominance hierarchies of the commercially important tropical fish Nile tilapia (Oreochromis niloticus). Aggression components were examined in fish shoals during hierarchy formation (T1) and after hierarchy establishment (T2) under optimal (26 °C) or cold (14 °C) temperatures, and 24 h afterwards (T3) following gradual temperature increase (14–26 °C, IT treatment), decrease (26–14 °C, DT treatment) or constant optimal conditions (26 °C, CT control). During dominance hierarchy formation, fish in cold water showed reduced aggressive interactions involving lower-intensity behaviors whereas fish under warm temperature exhibited high aggression involving escalated fighting. Following temperature alterations, at T3, aggression levels increased in the IT groups, decreased in the DT groups and remained similarly high in the CT groups. However, despite the drop of temperature in the DT treatment, aggression level at T3 in cold temperature in this treatment was similar to that in the IT treatment and CT control in warm temperature. Likewise, despite the increase of temperature, aggression level in the IT treatment at T3 was lower than that observed under the same warm temperature conditions in the DT and CT groups. Our results demonstrate that in addition to the acute effect of the current temperature on aggression in dominance hierarchies, there is a significant carryover effect of prior thermal conditions under which dominance hierarchy has been formed. Thus, cold temperature can possibly be applied during hierarchy formation for mitigating adverse social effects arising from fish grouping under captive conditions.

ABIOTIC FACTORS INFLUENCES THE FORMATION OF RESISTANCE POIKILOTHERMIC ANIMALS

Dependences and regularities of the influence of abiotic factors on the formation of resistance of poikilother-mic animals on the model species Cyprinus carpio have been resistanced. A sharp decrease in the temperature of the aquatic environment leads to an increase in the level of cortisol in the blood serum of fish. A decrease in the amount of dissolved oxygen in the aquatic environment leads to an increase in cortisol levels. With an increase in the time spent in an anhydrous medium in the serum of Cyprinus carpio, the level of protein decreases, and the level of cortisol increases.

Surface Glucan Structures in Aeromonas spp.

Aeromonas spp. are generally found in aquatic environments, although they have also been isolated from both fresh and processed food. These Gram-negative, rod-shaped bacteria are mostly infective to poikilothermic animals, although they are also considered opportunistic pathogens of both aquatic and terrestrial homeotherms, and some species have been associated with gastrointestinal and extraintestinal septicemic infections in humans. Among the different pathogenic factors associated with virulence, several cell-surface glucans have been shown to contribute to colonization and survival of Aeromonas pathogenic strains, in different hosts. Lipopolysaccharide (LPS), capsule and α-glucan structures, for instance, have been shown to play important roles in bacterial–host interactions related to pathogenesis, such as adherence, biofilm formation, or immune evasion. In addition, glycosylation of both polar and lateral flagella has been shown to be mandatory for flagella production and motility in different Aeromonas strains, and has also been associated with increased bacterial adhesion, biofilm formation, and induction of the host proinflammatory response. The main aspects of these structures are covered in this review.

A Zebrafish Model of Neurotoxicity by Binge-Like Methamphetamine Exposure.

Hyperthermia is a common confounding factor for assessing the neurotoxic effects of methamphetamine (METH) in mammalian models. The development of new models of methamphetamine neurotoxicity using vertebrate poikilothermic animals should allow to overcome this problem. The aim of the present study was to develop a zebrafish model of neurotoxicity by binge-like methamphetamine exposure. After an initial testing at 20 and 40 mg/L for 48 h, the later METH concentration was selected for developing the model and the effects on the brain monoaminergic profile, locomotor, anxiety-like and social behaviors as well as on the expression of key genes of the catecholaminergic system were determined. A concentration- and time-dependent decrease in the brain levels of dopamine (DA), norepinephrine (NE) and serotonin (5-HT) was found in METH-exposed fish. A significant hyperactivity was found during the first hour of exposure, followed 3 h after by a positive geotaxis and negative scototaxis in the novel tank and in the light/dark paradigm, respectively. Moreover, the behavioral phenotype in the treated fish was consistent with social isolation. At transcriptional level, th1 and slc18a2 (vmat2) exhibited a significant increase after 3 h of exposure, whereas the expression of gfap, a marker of astroglial response to neuronal injury, was strongly increased after 48 h exposure. However, no evidences of oxidative stress were found in the brain of the treated fish. Altogether, this study demonstrates the suitability of the adult zebrafish as a model of METH-induced neurotoxicity and provides more information about the biochemical and behavioral consequences of METH abuse.

Allee effect in a manipulative parasite within poikilothermic host under temperature change.

Temperature and intraspecific competition are important factors influencing the growth of all organisms, including parasites. The temperature increase is suggested to stimulate the development of parasites within poikilothermic hosts. However, at high parasite densities, this effect could be diminished, due to stronger intraspecific competition. Our study, for the first time, addressed the joint effects of warming and parasite abundances on parasite growth in poikilothermic hosts. The growth of the common fish parasite larvae (trematode Diplostomum pseudospathaceum) within the rainbow trout at different infection intensities and temperatures (15°C and 18°C) was experimentally investigated. The results showed that temperature was positively correlated with both parasite infection success and growth rates. The growth rates increased much more compared to those in many free-living poikilothermic animals. Atypically for a majority of parasites, D. pseudospathaceum larvae grow faster when abundant (Allee effect). The possible causes for this phenomenon (manipulation cost sharing, etc.) are discussed in this study. Importantly, limited evidence of the interaction between temperature and population density was found. It is likely that temperature did not change the magnitude of the Allee effect but affected its timing. The impact of these effects is supposed to become more pronounced in freshwater ecosystems under current climate changes.

Effect of global climate change on the distribution of Anchomenus dorsalis (Coleoptera, Carabidae) in Europe

Shifts in the bioclimatic range of Anchomenus dorsalis – specialized entomophage – were modeled in the MaxEntsoftware package and are presented on habitat maps. For the prediction, we used two climatic scenarios – mild (RCP2.6) and extreme (RCP8.5). Under the considered scenarios, the further warming would lead to shift and extension of the range to the north, northeast and east and decrease in the number of populations in the southern regions of Europe. The most important bioclimatic indicators which describe the geographic distribution of A. dorsalis are mean annual air temperature, mean daily amplitude of temperature for each month, overall amount of precipitations in the coldest quarter of the year, minimum temperature of the coldest month, mean temperature of the warmest quarter of the year, and annual amount of precipitations. Global warming causes the bioclimatic range of A. dorsalis to shift northeast and east in intracontinental territories, and west and northwest on islands. This species of ground beetle is an important object in monitoring of the condition of natural and agrarian ecosystems, sensitive to the growing global climate changes.  Poikilothermic animals may suffer from overheating, and even if they live far in the northern hemisphere, the ability of their organism to withstand increase in the environmental temperature is limited. Mild winters (with higher temperatures) may increase the mortality of A. dorsalis by exhausting their energy reserves.

Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium Microcystis.

Cyanobacteria dominance and warming have been suggested to decrease the production of polyunsaturated fatty acids (PUFA) in freshwater ecosystems. Physiological adaptations of poikilothermic animals to higher temperatures may further decrease PUFA levels in aquatic food webs. We conducted diet manipulation experiments to investigate the combined effects of dietary PUFA and warming on the proportions of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) in Chironomus riparius. The experimental diet consisted of a nontoxic cyanobacterium Microcystis, which contained C20 PUFA: 20:3n-3, 20:4n-3, and 20:3n-6, but no EPA or ARA. Additionally, we used TetraMin® fish flakes as a control treatment. A temperature increase from 20 °C to 25 °C decreased the proportion of n-3 C20 PUFA and the n-3/n-6 ratio in Microcystis. Diet manipulation experiments indicated that Chironomus desaturated dietary C20 precursors to EPA and ARA, but warming decreased this bioconversion and resulted in lower levels of EPA and ARA in Chironomus. Warming did not alter the proportions of EPA and ARA in Chironomus larvae if these PUFA were readily available in the diet (TetraMin® control treatment). In conclusion, warming and cyanobacteria dominance may decrease the production and trophic transfer of physiologically important PUFA in freshwaters by (1) decreasing the n-3/n-6 ratio and the abundance of n-3 C20 precursors in Microcystis, and (2) decreasing the bioconversion of n-3 and n-6 C20 precursors to EPA and ARA in chironomids. These changes may have cascading effects throughout the food web and decrease the content of EPA in fish, potentially affecting its availability to humans.

Glycoproteins of Predicted Amphibian and Reptile Lyssaviruses Can Mediate Infection of Mammalian and Reptile Cells.

Lyssaviruses are neurotropic rhabdoviruses thought to be restricted to mammalian hosts, and to originate from bats. The identification of lyssavirus sequences from amphibians and reptiles by metatranscriptomics thus comes as a surprise and challenges the mammalian origin of lyssaviruses. The novel sequences of the proposed American tree frog lyssavirus (ATFLV) and anole lizard lyssavirus (ALLV) reveal substantial phylogenetic distances from each other and from bat lyssaviruses, with ATFLV being the most distant. As virus isolation has not been successful yet, we have here studied the functionality of the authentic ATFLV- and ALLV-encoded glycoproteins in the context of rabies virus pseudotype particles. Cryogenic electron microscopy uncovered the incorporation of the plasmid-encoded G proteins in viral envelopes. Infection experiments revealed the infectivity of ATFLV and ALLV G-coated RABV pp for a broad spectrum of cell lines from humans, bats, and reptiles, demonstrating membrane fusion activities. As presumed, ATFLV and ALLV G RABV pp escaped neutralization by human rabies immune sera. The present findings support the existence of contagious lyssaviruses in poikilothermic animals, and reveal a broad cell tropism in vitro, similar to that of the rabies virus.

Impact of habitation conditions on metabolism in the muscles, liver, and gonads of different sex and age groups of bream

Impact of the factors of the aquatic environment is an inevitable aspect of the life of fish as poikilothermic animals and provokes responses in their organisms. The study focused on determining peculiarities in the composition of the metabolic products in the tissues of different age and sex groups of common bream Abramis brama (L.) depending on the living conditions in the water reservoirs of the Upper Volga. The fish were captured in the fattening period in summer and autumn, measured, weighed, identifying sex, maturity stage of the gonads and age. In the muscles, liver and gonads of bream, we analyzed the contents of water, dry matter, lipids, protein, ash and carbohydrates using the standard techniques. The contents of biochemical components in the organism of bream were to a higher degree determined by the peculiarities of the living conditions rather than sex and age of the individuals. In the muscles and liver of bream living in the conditions of increased water temperature and low concentration of oxygen, the concentrations of protein and ash were lower. In the same tissues of bream from the water bodies with high concentrations of pollutants in the water and benthic deposits, we found increased fat content. The muscles of male bream contained less protein and more carbohydrates than females and juvenile individuals, and the muscles of juveniles had less fat. The environmental factors had greater influence on the content of the metabolic products in the liver of bream than sex, and only females had higher ash content than males. The testes had more fat and less protein than the ovaries. During the transition of the gonads from maturity stage II to III, the contents of dry matter and lipids in them decreased. We determined that the environmental factors have stronger impact on biochemical parameters in the tissues of bream than age, because we found no general age patterns in the dynamics of biochemical components, except the liver, in which the highest content of organic compounds was found in individuals aged 6 to 10 years. Water heated by the Hydro Power Plant positively influenced the young bream, as indicated by higher content of metabolic products in individuals aged 5+ than older groups and bream from the surveyed water bodies. Monitoring of the physiological condition of bream focusing on the contents of metabolic products in the tissues may provide necessary data for successful regulation of bream populations in the water reservoirs of the Upper Volga.

A nutritional strategy to promote gilthead seabream performance under low temperatures

Gilthead seabream (Sparus aurata) is vulnerable to low water temperature, which may occur in the Southern Europe and Mediterranean region during Winter. Fish are poikilothermic animals, therefore feed intake, digestion, metabolism and ultimately growth are affected by water temperature. This study aimed to evaluate growth performance, feed utilisation, nutrient apparent digestibility, and nitrogen losses to the environment in gilthead seabream juveniles reared under low temperature (~13 °C). Three isolipid and isoenergetic diets were formulated: a diet similar to a commercial feed (COM) that contained 44% crude protein and 27.5% fishmeal, and two experimental diets with a lower protein content of 42% (ECO and ECOSup). In both ECO diets fishmeal inclusion was reduced (10% in ECO and 7.5% in ECOSup diet) and 15% poultry meal was included. Additionally, the ECOSup diet was supplemented with a mix of feed additives intended to promote fish growth performance and feed intake. The ECO diets presented lower production costs than the COM diet, whilst incorporating more sustainable ingredients. Gilthead seabream juveniles (±154.5 g initial body weight) were randomly assigned to triplicate tanks and fed the diets for 84 days. Fish fed the ECOSup diet attained a similar final body weight than fish fed the COM diet, significantly higher than fish fed the ECO diet. ECOSup fed fish presented significantly higher hepatosomatic index than COM fed fish, most likely due to higher hepatic glycogen reserves. The viscerosomatic index of ECOSup fed fish were significantly lower compared to COM fed fish, which is a positive achievement from a consumer's point of view. ECOSup diet exhibited similar nutrient digestibility than the COM diet. Moreover, feeding fish with the ECO diets resulted in lower faecal nitrogen losses when compared to COM fed fish. The results suggest that feeding gilthead seabream with an eco-friendly diet with a mix of feed additives such as the ECOSup diet, promoted growth and minimised nitrogen losses to the environment. Nutritional strategies that ultimately promote feed intake and diet utilisation are valuable tools that may help conditioning fish to sustain growth even under low temperatures.

Coupling between fast and slow oscillator circuits in Cancer borealis is temperature-compensated.

Coupled oscillatory circuits are ubiquitous in nervous systems. Given that most biological processes are temperature-sensitive, it is remarkable that the neuronal circuits of poikilothermic animals can maintain coupling across a wide range of temperatures. Within the stomatogastric ganglion (STG) of the crab, Cancer borealis, the fast pyloric rhythm (~1 Hz) and the slow gastric mill rhythm (~0.1 Hz) are precisely coordinated at ~11°C such that there is an integer number of pyloric cycles per gastric mill cycle (integer coupling). Upon increasing temperature from 7°C to 23°C, both oscillators showed similar temperature-dependent increases in cycle frequency, and integer coupling between the circuits was conserved. Thus, although both rhythms show temperature-dependent changes in rhythm frequency, the processes that couple these circuits maintain their coordination over a wide range of temperatures. Such robustness to temperature changes could be part of a toolbox of processes that enables neural circuits to maintain function despite global perturbations.

Sarcocystis cristata sp. nov. (Apicomplexa, Sarcocystidae) in the imported great blue turaco Corythaeola cristata (Aves, Musophagidae)

BackgroundSpecies of Sarcocystis are parasitic protozoa in poikilothermic and homeothermic animals. Out of the 26 valid species in birds as intermediate hosts, none has been reported in those of the order Musophagiformes, such as the great blue turaco Corythaeola cristata (Vieillot, 1816), which is a bird endemic to Central and Western Africa. The examination of great blue turacos imported from the Central Africa Republic to Czech Republic allowed the morphological and molecular characterization of a new species of Sarcocystis.MethodsFour turacos imported from the Central Africa Republic to a private breeder (Czech Republic) underwent parasitological examination for the presence of sarcocysts through wet mounts of breast, heart and leg muscles. Found parasites were molecularly and histologically studied by four loci (18S rRNA, 28S rRNA, ITS1 and cox1) and haematoxylin and eosin staining, respectively.ResultsThree out of four examined birds harboured numerous sarcocysts in the breast and leg muscles. No macroscopic lesions where observed. Sarcocysts were microscopic, elongate and ribbon-shaped with a wall characterised by the presence of finger-shaped villar protrusions and filled with numerous elongate, banana-shaped bradyzoites, 11.87–14.84 × 2.05–2.92 µm in size. The new species was most closely related to Sarcocystisalbifronsi, Sarcocystisanasi, Sarcocystisatraii, Sarcocystischloropusae, Sarcocystisrileyi, Sarcocystiswenzeli and Sarcocystis sp. isolate from chicken in the four loci.ConclusionsTo our knowledge, this is the first species of Sarcocystis found in a musophagiform bird worldwide. Genetically, S. cristata sp. nov. represents a distinct species. Phylogenetic analyses are useful for predicting potential definitive hosts of the new Sarcocystis species.graphical

ESSENTIAL OILS AND THEIR COMPOSITIONS AS THE BASIS OF PREPARATIONS FOR INCLUSION IN THE METHOD OF INCREASING THE RESISTANCE OF POIKILOTHERMIC ANIMALS TO MICROORGANISMS OF THE GENUS AEROMONAS AND GENUS PROTEUS

In the course of studies, the antimicrobial activity of plant essential oils was assessed, the basic principles of de-velopment were determined and the compositions of compounds were proposed that can be used as a basis for prepara-tions for inclusion in the method of increasing the resistance of poikilothermic animals to microorganisms of the genus Aeromonas and the genus Proteus.