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Speculative Evolution: Anatomical and Physiological Specifics of Organisms Inhabiting Super-Earths
Šefrna, Radek ; Toman, Jan (advisor) ; Petrásek, Tomáš (referee)
This thesis focuses on super-Earth-like planets, specifically addressing how a larger radius and gravitational attraction, sometimes associated with increased atmospheric density, could affect the direction of anagenesis if other parameters are kept at the terrestrial level. Firstly, super- Earth characteristics are described. Secondly, locomotion and its anatomical and physiological correlates are examined. It concludes that organisms living on the surface would have robust body structure and expects prevalence of the biosphere to exist in the air column on super- Earths with dense atmosphere with organisms resembling ocean life on Earth. Lastly, the thesis investigates life strategies and their potential dependencies on gravitational and surface characteristics, with an emphasis on energy acquisition methods, metabolism, and dispersion. With the existence of complex ecosystem reliant on photosynthesis, existence of ecological niches similar to the ones found on Earth is expected. That could lead to the genesis of symbioses, as they seem to be a universal feature of any biosphere. Due to its speculative nature, the thesis draws conclusions from studies on terrestrial organisms and their environment. It adheres to the phenomenon of convergent evolution to find possible analogies and show potential...
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Stress markers and methodologies for their measurement in selected model species
Langmajerová, Anna ; Nekovářová, Tereza (advisor) ; Petrásek, Tomáš (referee)
The stress response is a cascade of physiological and subsequently behavioural processes that enable the organism to cope with various stressful situations and influences (stressors). The manifestations of stress in different organisms are to some extent similar, but at the same time they may differ in intensity and manner. Stress can be measured using biological markers, which are objective and measurable and indicative of underlying biological processes. This bachelor thesis focus on stress markers and the methodology of their measurement. It also discusses specific types of stress markers in each model, for example, measurement of stress hormones (cortisol, corticosteroid), measurement of body temperature, blood pressure or heart rate, or behavioural performance. The thesis also focus on the issue of suitability and applicability of various methods of measuring and evaluating stress in individual models, depending on their accuracy and welfare of the animals during a given measurement, which may influence the test results. Keywords: animal model, behavior, biomarker, stress
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The effect of the molecular weight of poly(I:C) on the development and behavior of offspring in the maternal immune activation model
Cmarková, Nathalie ; Brožka, Hana (advisor) ; Petrásek, Tomáš (referee)
Maternal inflammation during pregnancy is associated with an increased risk of the development of psychiatric disorders in offspring, especially schizophrenia and autism. Prenatal treatment with poly(I:C), a viral mimetic, is a widely used model of maternal immune activation leading to developmental and behavioral alterations in offspring. However, results of studies are inconsistent possibly due to the differences in the molecular weight of used poly(I:C). In this thesis, the effect of different molecular weights of poly(I:C) was assessed. Pregnant Wistar rat females were treated by either high molecular weight (HMW) or low molecular weight (LMW) poly(I:C) on gestational day 14 to assess developmental and behavioral deficits relevant to schizophrenia and autism in offspring on postnatal day 12 and at three months. Prenatal exposition to the HMW poly(I:C) led to significantly reduced social behavior in the Homing test and a trend towards reduced USV vocalization in pups. The LMW pups showed significantly impaired negative geotaxis. In adulthood, the HMW and LMW offspring both exhibited significant social deficits and reduced anxiety. Anxiety was reduced mainly in the LMW group. This thesis revealed differences in behavioral outcomes between prenatal exposition to HMW and LMW poly(I:C). These...
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Differences in behavior and sociability depending on environmental enrichment in a rat model of autism
Tučková, Klára ; Petrásek, Tomáš (advisor) ; Svoboda, Jan (referee)
Autism spectrum disorders are among the most severe congenital neurodevelopmental disorders. Even though many known risk factors can induce ASD, the exact etiology is not known. This thesis focuses on different approaches to studying ASD in rodent models. The main goal of the experimental part of the thesis was to examine the manifestations of ASD in a rat genetic model of tuberous sclerosis (so-called Eker rat) and to determine the effect of different housing environments on autistic phenotype. The animals were studied for one year. We performed three series of behavioral tests at the age of 45, 90 and 365 days. Testing was focused on assessment of exploration, anxiety, and sociality. Our results showed that the activity in the open field was higher in young Eker rats. The anxiety displayed in the elevated plus maze was reduced in rats kept in an enriched environment. In social interaction, the enriched environment significantly increased self-grooming. We observed less complex self-grooming in Eker rats housed without environmental enrichment. Ultrasound communication varied significantly with age. We confirmed that the enriched environment had a significant effect on the behavior of rats, but we observed no strong differences in behavior caused by the Eker genotype. Key words: autism, Eker,...
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The role of ghrelin signalling in the neurobiological mechanisms of rewarding effects of cannabinoids and opioids
Charalambous, Chrysostomos ; Šustková, Magdaléna (advisor) ; Rudá, Jana (referee) ; Petrásek, Tomáš (referee)
Background: Ghrelin, an orexigenic appetite stimulating peptide, in addition to promoting energy balance, contributes to the rewarding effects associated with overeating. It also seems to play an important role in the rewarding/reinforcing effects of alcohol and addictive stimulants. The involvement of the ghrelin mechanisms in cannabinoid and opioid misuse and addiction have been under-researched. Aims: The principal aim of this research thesis was to investigate whether the pretreatment with the growth hormone secretagogue receptor 1A (GHS-R1A) antagonist (JMV2959) could reduce the cannabinoid receptor type 1 (CB1R) agonist WIN55,212-2-induced dopamine efflux in the nucleus accumbens shell (NACSh), which is considered a crucial trigger impulse of the addiction process. Also, test whether JMV2959 can influence the WIN55,212-2 and fentanyl-induced effects on the endocannabinoids N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG) and the gama-aminobutyric acid (GABA) content in the NACSh, and in extend, to specify the involvement of GHS-R1A located in the ventral tegmental area (VTA) and the NACSh in the observed accumbens changes. Furthermore, to test whether the JMV2959 pretreatment could reduce the cannabinoid [tetrahydrocannabinol (THC) and WIN55,212-2] induced behavioural...
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Ontogenesis of episodic memory in preschool children
Píšová, Martina ; Nekovářová, Tereza (advisor) ; Petrásek, Tomáš (referee)
Episodic memory enables us to remember and recall life events from the past. Episodic memory is a specific type of long-term declarative memory, which undergoes changes in ontogeny. To examinate of episodic memory, "episodic-like memory model", was developed. This model focuses on three basic components of episodic memory: "What happened", "Where did it happen" and "When did it happen". The aim of this diploma thesis is to develop and to validate of particular tests of episodic memory with consideration for their feasibility for preschool children. In order to study episodic memory we used an "episodic-like memory model" and experiments which focused on: children's verbal ability, differentiation of two perspectives during remembering of events and timing memories on an autobiographical axis. We aimed to inspect the effect of age on performance in these tests, possible links between performance in these experiments and the effect of level and the three components of episodic memory on number of errors made. In our dataset we found a significant effect of the age of children in Sentence repetition test and in test of Object collection in the virtual house, in the same test we found a effect of the level on number of errors. We also found a significant correlation between correct responses in verbal...
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Relative numerosity discrimination in primates
Moravcová, Anna ; Nekovářová, Tereza (advisor) ; Petrásek, Tomáš (referee)
This work is focused on numerical competence in primates specifically focusing on relative numerosity, one of the many aspects of these cognitive abilities. Relative numerosity is an ability to discriminate a larger quantity from a smaller amount or smaller quantity from a larger amount and could be classified as one of the easiest numerical competence. In this work I have summarized the present knowledge of numerical competences in primates, which have been so far studied only in a few species of primates, most of them was rhesus macaque (Macaca mulatta) and chimpanzee (Pan troglodytes). In the experimental part I focused on the research of relative numerosity in rhesus macaque (Macaca mulatta). The goal of my work was to find out whether macaques are able to solve the problem of relative abundance with different types of stimuli. Another goal was to find out whether they are able to generalize information about relative abundance and whether they can apply it for new design of the task. The results confirm that macaques possess the ability of relative numerosity and are able to abstract stimuli that are differing in their character. This proves that they are not learning to recognize a particular stimul, but are able to use this numerical skill on any type of stimul. I also found out that...
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Separation of hippocampal function in Morris water maze and in active place avoidance by alternance protocol
Vojtěchová, Iveta ; Petrásek, Tomáš (advisor) ; Hiadlovská, Zuzana (referee)
In this work, we examined the executive functions of the hippocampus at the behavioral level as a so-called behavioral separation in adult rats. We studied an impact of day-to-day alternation versus sequential learning (and the order of learning) of two spatial tasks (Morris Water Maze and Active Allothetic Place Avoidance) testing different hippocampal functions (experiment 1), or an impact of sequential versus alternating learning of one task (Active Allothetic Place Avoidance) in two different rooms (experiment 2), on performance. We found out that rats are able to learn both tasks as well as to discriminate between the two contexts regardless of the order or alternating of learning. Because such executive functions are impaired in human patients suffering from schizophrenia, we used this procedure also in the rat model of schizophrenia induced by acute intraperitoneal application of dizocilpine (MK-801), glutamate NMDA receptors antagonist, in the dose of 0.08 mg/kg. We failed to selectively disrupt the behavioral separation, however, we observed general learning deficit and hyperlocomotion regardless of the alternation in the Active Allothetic Place Avoidance task in these rats. The cognitive impairments in connection with learning after such low dose of MK-801 in this task have not yet been...
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Social behavior and communication in a laboratory rat and autism models
Tučková, Klára ; Petrásek, Tomáš (advisor) ; Pohanová, Petra (referee)
Social behavior of the brown rat as an animal living in a hierarchical collonies is very diverse and developed, which remains the same with the domestic laboratory rat. Rats communicate not only via odors, but also via various types of vocalizations, which express stress, pain or anxiety or on the other hand positive emotions and also communication during any social contact. Because of complex social behaviour and communication, rat is a suitable model organism for research of human mental disorders such as autism. This thesis gives an overview of natural social behaviour of rats, behavioural methods used for testing of animal models and describes selected rat models of autism induced through various types of interference (natural mutation, gene inactivation, virus infection and chemical disruption of brain development) and compares their impact at the level of rat behaviour. Key words Rat, social behaviour, communication, vocalization, experimantal tasks, model organism, autism, models of autism
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