Phylogenetic degrees for claw trees

Group-based models appear in algebraic statistics as mathematical models coming from evolutionary biology, respectively the study of mutations of organisms. Both theoretically and in terms of applications, we are interested in determining the algebraic degrees of the phylogenetic varieties coming from these models. These algebraic degrees are called phylogenetic degrees. In this paper, we compute the phylogenetic degree of the variety $X_{G, n}$ with $G\in\{\mathbb{Z}_2,\mathbb{Z}_2\times\mathbb{Z}_2, \mathbb{Z}_3\}$ and any $n$-claw tree. As these varieties are toric, computing their phylogenetic degree relies on computing the volume of their associated polytopes $P_{G,n}$. We apply combinatorial methods and we give concrete formulas for them

Classification of normal phylogenetic varieties for tripods

We provide a complete classification of normal phylogenetic varieties coming from tripods, and more generally, from trivalent trees. Let $G$ be an abelian group. We prove that the group-based phylogenetic variety $X_{G,\mathcal{T}}$, for any trivalent tree $\mathcal{T}$, is projectively normal if and only if $G\in \{\mathbb{Z}_2, \mathbb{Z}_3, \mathbb{Z}_2\times\mathbb{Z}_2, \mathbb{Z}_4, \mathbb{Z}_5, \mathbb{Z}_7\}$

The effect of prefrontal and posterior parietal lesion on behavior in behavioral tests of spatial cognition

Vliv léze prefrontální a posteriorní parietální kůry na chování v testech prostorové kognice V této práci jsme testovali vliv léze prefrontální kůry a vliv léze posteriorní parietální kůry na chování a navigaci potkana. Mediální prefrontální kůra je dávána do souvislosti s pracovní pamětí, behaviorální flexibilitou a kódováním prostorového cíle. Potkany jsme testovali v kolotočovém bludišti na přeučování pozice zakázaného sektoru a následně jsme je testovali v úloze vyhýbání se rámci arény za tmy. Zjistili jsme, že potkani s lézí mediální prefrontální kůry v testu na přeučování zhoršeni nebyli, byli ale zhoršeni v samotném učení úlohy. V testu na rámec arény se nelišili od kontrol. Posteriorní parietální kůra hraje roli v procesech pozornosti a podílí se na zpracování prostorové informace a dlouhodobé paměti. Potkany s bilaterální lézí posteriorní parietální kůry jsme testovali řadou testů na kolotočové aréně (přeučování, dvojité vyhýbání) a v Morrisově vodním bludišti (klasická verze se vzdálenými orientačními body a modifikovaná verze s orientačními body uvnitř arény). Potkani s lézí posteriorní parietální kůry byli v úlohách na kolotočovém bludišti zhoršeni při přeučování na rámec arény. Tento trend se potvrdil i v úloze dvojitého vyhýbání, kdy měli více vstupů do sektoru definovaného rámcem...The effect of prefrontal and posterior parietal lesion on behavior in behavioral tests of spatial cognition In this thesis we examined the effect of prefrontal and posterior parietal cortex lesions on rat behavior. Medial prefrontal cortex is involved in working memory, behavioral flexibility and coding of spatial goals. Rats were tested in carousel maze in room frame reversal task and consequently in arena frame task on dark arena. We observed, that the lesion of medial prefrontal cortex did not disrupt the reversal learning task, but the rats were impaired in initial learning of the task. No difference was found in arena frame task. Posterior parietal cortex has a role in attention processes and takes part in processing spatial information and long term memory. Rats with bilateral lesion of posterior parietal cortex were tested in battery of tests on carousel maze (reversal learning, double avoidance) and in Morris water maze (distal landmark version and modified version with intramaze landmarks). Lesioned animals were impaired in carousel maze task in reversal learning of room frame represetation. This effect was confirmed in double avoidance task, where lesioned animals had more entrances into room frame than the controls. In Morris water maze task, lesioned animals were impaired in intramaze...Katedra fyziologieDepartment of PhysiologyPřírodovědecká fakultaFaculty of Scienc

Vliv stresu na regulaci a regeneraci glukokortikoidů u zvířecích modelů lišících se odpovědí osy hypothalamus-hypofýza-nadledviny

Mozek aktivuje stresovou odpověď v situacích, kdy je nebo se zdá být ohrožena homeostáza. Informace o stresu jsou vedeny z mozku dvěma hlavními větvemi; sympatoadrenálním systémem a osou hypothalamus-hypofýza-nadledviny (HPA), které aktivují neurální, humorální a imunitní dráhy, určené pro zvládání stresových situací. Protože se jedná o velmi účinný mechanismus, musí být stresová odpověď přesně řízena. HPA osa je regulována zpětnovazebným systémem, kdy její konečný produkt, kortikosteron u laboratorních potkanů a myší, tlumí její aktivitu. Efekt kortikosteronu nezávisí pouze na jeho koncentraci, ale také na lokálním metabolismu glukokortikoidů katalyzovaném enzymem 11β-hydroxysteroiddehydrogenázou 1 (kódovanou genem Hsd11b1), který obnovuje kortikosteron z 11-dehydrokortikosteronu uvnitř buňky; nebo de novo syntézou glukokortikoidů. V naší práci jsme se zaměřili na zkoumání stresové odpovědi u pokusných zvířat lišících se reaktivitou HPA osy ((potkani kmene Fischer 344 (F344) proti potkanům kmene Lewis (LEW) a bezmikrobní (GF) myši proti myším bez specifického patogenu (SPF)), se zaměřením na regulaci stresové odpovědi, regeneraci glukokortikoidů a vliv mikrobioty. Zjistili jsme, že stres moduluje lokální regeneraci glukokortikoidů v limbických oblastech zapojených do řízení HPA osy, ale nemá vliv v...Stress reaction is usually activated by the brain, when homeostasis is or perceived to be threatened. The stress signals are transmitted from the brain by two main branches; the sympathoadrenomedullary and the hypothalamo-pituitary-adrenal (HPA) axes and employ neural, humoral and immune pathways to cope with the stressor. Because of its potency, the stress reaction has to be precisely regulated. The HPA axis is regulated by feedback loops where its end product, corticosterone in laboratory rat and mouse, inhibits its activity. The effect of corticosterone does not depend only on the concentration of corticosterone but also on local metabolism of glucocorticoids via oxo-reduction catalyzed by the enzyme 11β -hydroxysteroid dehydrogenase 1 (encoded by the Hsd11b1 gene), which intracellularly regenerates active corticosterone from inactive 11-dehydrocorticosterone, or by extra-adrenal de novo steroidogenesis of glucocorticoids. We focused on analysis of stress response in experimental animals differing in HPA axis responsivity (Fischer 344 rats (F344) vs. Lewis rats (LEW) and germ-free (GF) vs. specific pathogen free mice (SPF)) with special emphasis on regulation of stress response, glucocorticoid regeneration and influence of gut microbiota. We found that stress modulated local regeneration of...Department of PhysiologyKatedra fyziologieFaculty of SciencePřírodovědecká fakult

Strength values of shoulder internal and external rotators in junior tennis players

Character of modern tennis game in the last decade has become significantly more dynamic, fast and powerful, which brings high strain to joint and muscular system. The aim of this research was to establish strength level of external and internal shoulder rotators, and to compare the competitive tennis players group of boys (TEN, n=10, aged 12-14 years) and boys who did not perform any sport activity at competitive level (CS, n=10, aged 12-14 years) as well as to assess lateral differences in both groups. Using isokinetic dynamometry method (Humac Norm CSMI Stoughton, MA, USA), we tested strength level of external and internal shoulder rotators (180°/s, 300°/s). The TEN and CS group are comparable from the aspects of age, body height and body weight. Comparison of isokinetic strength values in TEN and CS groups proved significantly higher strength level of external and internal rotators in both (dominant and non-dominant) extremities for the TEN group. The lateral difference assessment proved the insignificant difference in external and significant difference in internal rotators in the TEN group, and the insignificant difference in both the external and internal rotators in the CS group. A lower strength level was found in the internal rotators in comparison with the external rotators in both groups (for both the dominant and non-dominant extremity), whereas in the TEN group lower differences between the external and internal rotators of the dominant extremity were proved. Although researches on adult highly skilled tennis players refer to a higher strength level of the upper extremity internal rotators, this fact has not been pronounced in the TEN group. An ideal external/internal rotators̕ ratio in adult players is considered within the interval of 66 75%. Significantly higher values obtained in the TEN group might be attributed to lower age and also lower performance level. It can be said that the level of isokinetic strength in the TEN the group is significantly higher than in the CS group, due to the influence of long-term game and training load