Zoology最新文献

Bioenergetics and biothermodynamics are valuable tools in research on growth and metabolic processes of a wide range of organisms, including viruses, bacteria, fungi, algae and plants, as is shown by the many publications on this topic in the literature. These studies provide insight into growth and metabolism of individual species, as well as interactions between species, like the virus-host interaction (infection) and virus-virus interaction (competition). However, this approach has not yet been applied to animal species. The universality of biothermodynamics and bioenergetics provides a good motive to apply them in analysis of animals. In this research, we made a bioenergetic, biothermodynamic and kinetic characterization for the first time for an animal species – Anguilla anguilla L. (European eel). We made a comparative analysis on yellow (young adult) and silver (mature adult) phases. Metabolic processes were modeled as chemical reactions with characteristic thermodynamic properties: enthalpy, entropy and Gibbs energy. Moreover, Gibbs energy explained growth rates, through phenomenological equations. This analysis of animal metabolism and growth explained metabolic properties of yellow and silver A. anguilla, including the bioenergetic aspect of life history. Moreover, we compared thermodynamic properties of A. anguilla with those of its main macromolecular components and other organisms. The thermodynamic properties were explained by the structural properties of organisms. This research extends the bioenergetic and biothermodynamic approaches to zoology, which should allow analysis of the energetic aspect of animal metabolic processes, interactions with their environment and interactions with other organisms. Furthermore, it connects the macroscopic perspective of zoology with the microscopic perspectives of biochemistry, bioenergetics and biothermodynamics. This will provide a basis for development of mechanistic models of animal growth and metabolism.

The kidneys of male Squamata have an important reproductive function as some portions of the nephron may undergo hypertrophy, characterizing the sexual segment of the kidney (SSK). Although its function is still not completely understood, it is believed that the secretions produced by the SSK may act in the maintenance of spermatozoa. In this study, we investigated the reproductive biology of males of Notomabuya frenata based on the seasonal variation of the SSK. We performed macroscopic and microscopic evaluations of the male reproductive tract of museum specimens to characterize the SSK cycle. The nephron portion in which hypertrophy was observed was the collecting duct with secretory granules accumulation in the apical portion. SSK hypertrophy was observed in all seasons, with the tubule diameter in autumn differing from spring and the epithelium height showing no variation. Alcian Blue reacted positively to acid mucopolysaccharides in all seasons. Periodic acid–Schiff’s reacted positively to neutral mucopolysaccharides in all seasons, except autumn. Both stains reacted only in the collecting duct. In addition, spermatozoa were found in the lumen of the SSK of one specimen examined. Cycle of the SSK varied seasonally as does the chemical composition of the secretions produced by the collecting duct. The reflux of spermatozoa into SSK may indicate that (1) these secretions act in sperm maintenance, and (2) possibly there is communication between the seminal and urinary ducts.

Ladybirds (Coccinellidae) use toxic compounds, mostly alkaloids in their haemolymph, for defence against predators and other enemies. The toxicity of ladybirds to predators cannot be directly assessed because predators show avoidance reactions without ingesting the beetles. The alkaloid of ladybird Harmonia axyridis showed wide range toxicity to diverse non-target organisms. Thus, we used a quick, inexpensive and easy-to-perform method using bioassays on water flea Daphnia magna for comparative quantification of the toxicity (LD₅₀) of whole body extracts from several species of ladybirds that differ in their warning colouration. Alien invasive aposematic polymorphic ladybird H. axyridis was more toxic than all the other species examined: aposematic Adalia bipunctata > cryptic Cynegetis impunctata > aposematic Coccinella septempunctata > slightly aposematic Calvia quatuordecimguttata. Three month old adults of H. axyridis were 3.8 times more toxic than two week and one month old adults. The two most common colour morphs (non-melanic novemdecimsignata and melanic spectabilis) did not differ in their toxicity. High toxicity of H. axyridis as compared to all other species examined may contribute to the invasiveness of this species.

Fishes are generally considered to be fully aquatic, but some voluntarily strand themselves on land to escape poor water conditions, predators, or to exploit terrestrial niches. The tail-flip jump is a method of terrestrial locomotion performed by small fishes without apparent morphological specialization, but few studies have investigated the role the caudal fin has on the tail-flip jump. We hypothesized that fish with larger caudal fins would perform shorter individual tail-flip jumps and not be able to sustain jumping in extended terrestrial excursions. Zebrafish (Danio rerio) are an excellent model to investigate this because these fish perform the tail-flip jump and some strains have been selectively bred in the pet trade industry for larger fins. In this study, wildtype and longfin zebrafish were compared because of the larger caudal fins of the longfin zebrafish. Individuals of each strain performed three consecutive jump trials with 48 h between each trial: kinematic, voluntary, and exhaustion. The kinematic trial used a high-speed camera to measure kinematic variables of individual jumps. The voluntary trial recorded each fish’s voluntary response to stranding for three minutes. The exhaustion trial recorded the fish’s response to be constantly elicited to jump until exhaustion was reached. Despite differences in caudal fin area, there were no differences in the kinematic characteristics of individual jump performances, including jump distance. However, wildtype zebrafish performed more jumps, jumped more than they flopped, and moved a greater total distance in both voluntary and exhaustion trials despite moving for similar durations and reaching exhaustion at similar times. These findings imply that larger fins do not affect a fish’s ability to perform individual tail-flip jumps but does cause fish to employ different behavioral strategies when stranded for longer durations on land.

Spiders, assigned to macroconcentrators of heavy metals, are particularly threatened by the toxic effects of these chemicals. Until now, it has not been specified to what extent metals alter the processes proceeding in silk glands and if such changes could consequently influence the chemical and structural properties of the spun web threads. In the present study selected biological properties of Steatoda grossa (Theridiidae) silk yarn after nutritional exposure to copper at sublethal doses (0.234 mM CuSO4) were assessed. It was determined both changes in ultrastructure of ampullate glands and hunting web’s architecture as well the cytotoxic effect in model cells (fibroblasts: line ATCC® CCL–1 NCTC clone 929), that were in contact with the analyzed biomaterial. The exposure of spiders to copper caused the occurrence of apoptotic cells in the ampullate glands as well as a significant reduction in the diameter of single fibers in double and multiple connection complexes as compared with control. At both 24 and 72 h of incubation, intensification of apoptotic and necrotic processes was observed in the fibroblast cultures that were remaining in indirect contact with the webs produced by copper–contaminated individuals. In the case of fibroblasts in direct contact with silk from the copper group, a clear cytotoxic effect resulting in an increased frequency of necrosis was observed after 72 h of incubation. The results indicated that copper may change the biological properties of spider silk and compromise its biomaterial properties.

Pygidial glands are a common feature of all adephagans and their products play an important role in defense against predators. The morphology of the pygidial glands and the chemistry of their secretion were studied for the first time in two species of tiger beetles – Cicindela (Cicindela) sylvicola Dejean, 1822 and Cylindera (Cylindera) germanica (Linnaeus, 1758). The glands were examined by both bright-field microscopy and nonlinear microscopy. All morphological structures of the glands were measured and described in detail. The structures mentioned were compared with those of related taxa. The secretion extracts from the pygidial glands of the investigated taxa contained a total of 24 compounds, which were detected by gas chromatography-mass spectrometry (GC-MS). The secretion mixture of C. (C.) germanica was more complex (21 chemicals) than that of C. (C.) sylvicola (11 ones). Benzaldehyde was present in both secretion samples. Hydrocarbons were the most abundant group of secretory compounds. The purpose of the compounds, their distribution within the subfamily Cicindelinae and their effects on the ecology of the group were discussed.

Birds living at high latitudes perceive the photoperiod through deep-brain photoreceptors (DBP) located in deep-brain neurons. During long photoperiods the information transmitted by these photoreceptors increases the activity of the hypothalamic-pituitary-gonadal (HPG) axis, leading to gonadal development. The presence of photopigments such as VA-Opsin, Opn4, Opn5 and Opn2 in brain areas implicated in reproductive behaviors has been firmly established in several avian species with seasonal breeding, whereas their existence in opportunistic breeding birds remains unconfirmed. The Eared Dove is an urban and peri-urban dove that breeds throughout the year. Males of this species do not exhibit the typical gonadal regression/recrudescence cycle, thus posing the question of what occurs upstream of the HPG axis. We addressed this issue by first studying the presence of diverse opsins located in DBP in the brains of Eared Dove males and whether these photopigments changed their expression throughout the year. We carried out an immunohistochemistry analysis on three different opsins: Opn2 (rhodopsin), Opn3 and Opn5. Our results demonstrate the discrete neuroanatomical distribution of these opsins in the brain of Eared Dove males and strongly indicate different seasonal expressions. In the anterior region of the hypothalamus, Opn2-positive cells were detected throughout the year. By contrast, Opn5 was found to be strongly and seasonally expressed during winter in the anterior and the hypothalamic region. Opn3 was also found to be significantly and seasonally expressed during winter in the hypothalamic region. We thus demonstrate for the first time that males of the Eared Dove, have three different deep-brain opsin-expressing photoreceptors with differential location/distribution in the anterior and hypothalamic region and differential seasonality. The persistence of Opn2 and the strong seasonal expression of nonvisual photopigments Opn3 and Opn5 in two areas of the avian brain, which are associated with reproduction, could be the primary distinction between seasonal and opportunistic breeders.

Otoliths are small calcium carbonate structures found in the inner ear of fish and they, as one of important information carriers, are applied in diverse ecological fields. Otoliths are usually photographed and used to explore many unsolved biological and ecological questions. However, many anomalies may occur in the large volume of otolith image data due to natural or artificial consequences, which brings a huge bias to the aimed study and even misleading results. In this study, we first propose a specific definition of otolith anomalies and provide a dataset of otolith anomalies with Electrona carlsbergi, one of the most abundant species of lanternfishes, as the study subject. We modify a multiresolution knowledge distillation neural network model, the state-of-the-art anomaly detection model to a multiresolution knowledge distillation network model with asymmetric inputs, which uses grayscale maps to align the features of color maps in the feature space, to help improve otolith anomalies detection. Our fine-tuned anomaly detection network obtains a better anomaly identification performance with a Receiving Operating Characteristic Area Under the Curve value of 0.9843. Our result shown that multiresolution knowledge distillation networks can efficiently identify abnormal otolith image sample, which is of great importance for conducting otolith-based science.

The integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the epithelium, muscles, and elements of connective and nerve tissue. The integument acts as a physical barrier between the external environment and the internal environment that serves to protect and maintain the body of the animal. The body of nudibranch mollusks undergo significant changes during ontogenesis, with the subepidermal space changing as the mollusk grows. As the extracellular subepidermal matrix is modified, the number of collagen fibers increases, muscles and nerves develop, and calcite spicules appear and grow. Yet, specific knowledge pertaining to the transformation of the epithelium is absent. In the present work, the ontogenetic dynamics of the surface epithelium of nudibranch mollusks are traced for the first time using Onchidoris muricata (O. F. Müller, 1776) during the postlarval stages of development. Ontogenetic changes in the epithelium of O. muricata were studied using a complex set of morphological methods. According to our data, the degree of modification to the epithelium in ontogenesis depends on individual body parts and is not consistent throughout. First x-cells were recognized as the probable precursors to sclerocytes.

Reproduction in female mammals is characterized by major changes in steroid hormone concentrations, which can be linked to fluctuations in energy expenditure (EE). Estradiol and cortisol can increase EE and metabolic rates (MRs), but knowledge on MR changes during the estrous cycle and gestation is scarce for many species. This also applies to the domestic guinea pig, a species exhibiting an exceptional estrous cycle among rodents. In this study, MRs were measured through oxygen (O₂) consumption in female guinea pigs during different reproductive stages. Mean O₂ consumption over 2.5 h, resting metabolic rate (RMR, lowest and most stable O₂ consumption over 3 min), body mass, fecal estrogen and progesterone, and saliva cortisol concentrations were measured in twelve female guinea pigs in a repeated measurements design during diestrus, estrus, and the second trimester of gestation. In estrus, body mass was significantly lower and estrogen and cortisol concentrations were significantly higher compared to diestrus and gestation. Mean O₂ consumption and RMR both were significantly increased in estrus compared to diestrus. Additionally, a positive effect of body mass on MRs detected during diestrus and gestation was not found during estrus. Mean O₂ consumption was also higher during gestation compared to diestrus, and a significant increase in cortisol concentrations during the 2.5-h MR measurement was recorded. The results indicate that estrus in guinea pigs is energetically demanding, which probably reflects catabolic effects of estrogens and cortisol that uncoupled MRs from body mass. Knowledge on the energetic requirements associated with different reproductive stages is important for future physiological and behavioral studies on female guinea pigs.