337 research outputs found
Ladislav Hanus: Slovak statehood
No full textTitle: Slovenská štátnosť (Slovak statehood) Originally published: Kultúra, no. 1 (1941), pp. 11–17. Language: Slovak The excerpts used are from Rudolf Chmel, ed., Slovenská otázka v 20. storočí (Bratislava: Kalligram 1997), pp. 296–303. About the author Ladislav Hanus [1907, Liptovský Mikuláš (Hun. Liptószentmiklós) – 1994, Ružomberok]: philosopher, priest, translator, and historian of culture. He studied at the theological faculty in Spišská Kapitula (Hun. Szepeshely, Ger. Zipser Kapitol) a..
On genomic coding theory
No full textThis paper gives a brief overview of several applications from the emerging interdisciplinary field of genomic coding theory that aims at applying concepts and techniques from the field of coding theory to problems from the field of molecular biology. This is motivated by the high precision and robustness found in genomic processes in addition to the increase in the availability of genomic data for a wide range of species. The considered applications include source coding for DNA classification, channel coding for modelling gene expression with emphasis on the process of translation, existence of error correcting codes in the DNA and channel coding structure in the genetic code. Example results are presented that demonstrate the relevance of the proposed approaches and open questions are formulated to suggest future research work. Copyright © 2007 John Wiley and Sons, Ltd.BATTAIL G, 2006, INTRO BIOSEMIOTICS; BLANCHETTE M, 2003, P 7 ANN INT C RES CO, P57, DOI 10.1145-640075.640082; Chen X, 2002, BIOINFORMATICS, V18, P1696, DOI 10.1093-bioinformatics-18.12.1696; DAWY Z, 2005, P IEEE ICC 2005 MAY; Freeland SJ, 2003, ORIGINS LIFE EVOL B, V33, P457, DOI 10.1023-A:1025771327614; GOLDMAN N, 1994, MOL BIOL EVOL, V11, P725; HANUS P, 2005, P GERM C BIOINF OCT; Hayes B, 1998, AM SCI, V86, P8, DOI 10.1511-1998.17.3338; Li M, 2001, BIOINFORMATICS, V17, P149, DOI 10.1093-bioinformatics-17.2.149; Liebovitch LS, 1996, BIOPHYS J, V71, P1539; Mac Donaill DA, 2003, ORIGINS LIFE EVOL B, V33, P433; Margulies EH, 2003, GENOME RES, V13, P2507, DOI 10.1101-gr.1602203; MAY E, 2004, J FRANKLIN I, V34, P89; Rosen GL, 2006, IEEE ENG MED BIOL, V25, P62, DOI 10.1109-MEMB.2006.1578665; Siepel A, 2005, GENOME RES, V15, P1034, DOI 10.1101-gr.3715005; STEITZ JA, 1975, P NATL ACAD SCI USA, V72, P4734, DOI 10.1073-pnas.72.12.4734; TAFT RG, 2004, QBIOGN0401020; Yockey HP, 1992, INFORM THEORY MOL BI53
A Hierarchy of Semantics for Normal Constraint Logic Programs
No full text. The different properties characterizing the operational behavior of logic programs can be organized in a hierarchy of fixpoint semantics related by Galois insertions, having the least Herbrand model as most abstract semantics, and the SLD operational semantics as most concrete semantics. The choice of a semantics in the hierarchy allows to model precisely the program properties of interest while getting rid of useless details of too concrete semantics, which is crucial for the development of efficient program analysis tools. The aim of this paper is to push forward these methods by making them apply to normal (constraint) logic programs, that is full first-order (non Horn) programs. The fixpoint semantics defined by the first author for the rule of constructive negation by pruning is at the center of the hierarchy developed in this paper. We show that that semantics can be obtained by concretization of Kunen's semantics defined as a fixpoint, taken as the most abstract semantics of t..
Application of RNA interference to studies on biology of termites
No full textThe RNA interference (RNAi) mechanism can be used to reduce the expression of a selected gene in an organism. This method, discovered in 1998, has become the "gold standard" in basic biological research with overlaps to applied research and gene therapy in human medicine. For many reasons, RNAi is a suitable tool for the studies on biology of insects. RNAi is endowed with high sequence specificity, low costs, and easy application also in non-model species. Termites (Isoptera) are very sensitive to RNAi and this method is widely used to understand their physiology and ontogeny. The use of RNAi also has a potential in applied termite research and a significant number of publications have focused on the development of RNAi techniques as non-chemical pesticides against economically important termite species. This bachelor thesis aims to give a broad overview of the existing research on termites that uses the RNAi method
Ontogeny of exaggerated structures in dung beetles (Coleoptera: Scarabaeinae)
No full textE n g l i s h a b s t r a c t Horns of scarab beetles represent a secondary sexual characters present mostly in males, to whom they serve as weapons in combats over the acces to females. In many species, two discrete male forms occur, "horned" and "hornless", which employ different reproductive strategies. Adult body size and horn morphology are determined by nutritional conditions encountered by larvae during their development. Switching between developmental pathways is accomplished by circulating levels of juvenile hormone (JH) which reflect body size, and genetically determined threshold of sensitivity to it. When body size is larger then threshold, horn growth occur, whereas if it's not, a brief pulse of ecdysone reprogramme the development and hornless adult emerge. Reprogramming the development encompass modifications of the insulin receptor pathway as well as changes in exact domains of genes expression envolved in specifying the proximodistal axis of the developing horn. Development of horns is morphologically reminiscent that of other insect appendages, with which it shares the expression of genes wingless, decapentaplegic, Distal-less, dachshund, homothorax, aristaless and EGFR, parts of gene regulatory network ensuring origin of the outgrowth of the cuticle. Some of them are expressed through..
Cell senescence with a focus on telomerase theory
No full textCell senescence is an irreversible state in which the cell cycle ends. The cell remains metabolically active, but its physiological functions are limited. Cell cycle arrest is a response to the action of a number of factors, most of which affect the secondary structure of DNA in various ways and cause damage to it. Other initiators of cell entry into the senescent state are oncogenes and chemotherapeutics. One of the best studied factors, which is also in a way the "fairest", is the shortening of the telomere. Telomeres are non-coding regions of DNA at the chromosome ends that shorten slightly with each division of the cell. If the cell does not have mechanisms to compensate for this loss, the Hayflick limit is reached after a certain time. In general, senescence can be considered as a protective mechanism to prevent DNA damage pathologies. However, the presence of senescent cells in tissues is often ambivalent, accumulates with age, and can cause many degenerative diseases. The senescent phenotype includes a wide range of signs such as changes in cell size and shape, increased granularity, or altered range of expressed genes. A significant phenomenon of senescent cells is the secretion of biologically active factors contributing to physiological or pathological changes in the organism. Key words:...Buněčná senescence je ireversibilní stav, při kterém dochází k ukončení buněčného cyklu. Buňka zůstává metabolicky aktivní, ale její fyziologické funkce jsou omezeny. Zastavení buněčného cyklu je odpovědí na činnost řady faktorů, z nichž většina různým způsobem zasahuje sekundární strukturu DNA a způsobuje její poškození. Dalšími iniciátory vstupu buňky do senescentního stavu bývají onkogeny a chemoterapeutika. Jedním z nejlépe prostudovaných faktorů, který je zároveň svým způsobem "nejspravedlivější", je zkracování telomer. Telomery jsou nekódující oblasti DNA na chromozomových koncích, které se s každým dělením buňky o kousek zkrátí. Pokud buňka nemá mechanismy vyrovnávající tuto ztrátu, dojde po určité době k dosažení Hayflickova limitu. Obecně se dá senescence považovat za ochranný mechanismus zabraňující vzniku patologií na základě poškození DNA Přítomnost senescentních buněk v tkáních je však často ambivalentní, s věkem se hromadí a mohou být příčinou mnoha degenerativních onemocnění. Senescentní fenotyp zahrnuje široké spektrum projevů jako například změny velikosti a tvaru buňky, zvýšenou granularitu či pozměněnou škálu exprimovaných genů. Výrazným jevem senescentních buněk je sekrece biologicky aktivních faktorů přispívajících k fyziologickým či patologickým změnám v organismu. Klíčová...Department of Cell BiologyKatedra buněčné biologiePřírodovědecká fakultaFaculty of Scienc
The role of juvenile hormone in ontogeny of burying beetles (Coleoptera: Silphidae)
No full textBurying beetles play an important role in ecosystems by removal of cadavers of small vertebrates. By competing other necrophagous insects and micro-organisms, they may contribute to reducing health risks. They are also interesting for their complex parental care of offspring. This paper describes the role of the juvenile hormone in the life history of burying beetles, breeding and parental care in particular
Evolution, Function and Chemical Diversity of Queen Pheromones in Social Insects
No full textSocieties of eusocial insects are probably the most complex biological systems. Repeated independent evolution of eusocial organization in multiple insect lineages has typically led to an unprecedented ecological success of these insects. However, beside coordinated work activities and altruism, the eusocial societies are also characterized by a potential for conflict over reproduction, leading to the evolution of mechanisms that prevent this conflict and ensure the colony homeostasis. Though it has long been known that this role is mediated by Queen Pheromones, there is still an important knowledge gap between our understanding of the biological role of Queen Pheromones and their chemical identity, biosynthesis and perception. Although the first Queen Pheromone has been identified in the early 1960s, more intensive research in this area is the matter of the last decade. The best known Queen Pheromone is that of the honey bee, contrasting with the knowledge on other social Hymenoptera and termites. Elucidating the chemical nature of Queen Pheromones could help to a better understanding of the evolution of social insects, their life cycle and community organization. This thesis summarizes the knowledge about the evolution and chemistry of Queen Pheromones in social insects
Reproductive strategy of the termite Silvestritermes minutus and its consequences for the life history and ecological succes
No full textMixed reproductive strategies are unique modes of reproduction, in which the organisms alternate sexual and asexual offspring production to benefit from both processes. In termites, such a strategy was first described in 2009 and dubbed Asexual Queen Succession (AQS). Reproduction in most termite species is based on a presence of one pair of long-lived reproductives, the primary king and queen, producing in a lifelong strict monogamy all other colony members using classical sexual processes. In a few rare species, the primary queen has been observed to be replaced at some stage of colony development by a harem of neotenic queens. These arise from unfertilized eggs via thelytokous parthenogenesis and reproduce with the founding king. While the workers, soldiers and winged dispersing reproductives remain to be produced sexually, new generations of parthenogenetic neotenic queens appear in the colony to supplement the harem. As long as the founding king is alive, the genetic constitution of most offspring remains identical as if the founding queen would still be alive, while the overall fecundity of the colony increases thanks to the large number of queens. At the same time, the continuous renewal of the harem by new parthenogens offers a virtually unlimited lifespan extension to the colony. In my..
Nest-mate recognition in termites
No full textDepartment of ZoologyKatedra zoologieFaculty of SciencePřírodovědecká fakult
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