Rigorous theses

Rigorous theses 15,500 records found  beginprevious15358 - 15367nextend  jump to record: Search took 0.01 seconds. 
The algal flora of Acadia National Park, Maine
VESELÁ, Jana
This study presents freshwater and brackish algal flora of Acadia National Park, Maine, U.S.A., a small park on the coast of New England. Prior to this study, there has been no examination conducted on freshwater and brackish algae restricted to the park boundaries. Over 200 samples, from 119 localities within the park, were collected and examined using standard microscopic techniques. A total of 160 genera of algae (from 12 algal phyla) were observed in the samples, including 140 new generic records for the park. Based on the similar studies, the high number of occurring algal genera in the park indicates an exceptionally high diversity for an area of this size.
Activation of protective cell-mediated immune response in gastric mucosa during Cryptosporidium muris infection and re-infection in immunocompetent mice
JALOVECKÁ, Marie
The differences between two isolates of Cryptosporidium muris (TS03 and CB03) in activation and development of cell-mediated immune response in stomach mucosa was observed during the primary infection and re-infection in immunocompetent mouse model. The development of the immune response was characterized by analysis of leukocyte infiltration into the gastric epithelium and cytokine production in ex vivo cultures of splenocytes.
"DNA" barcoding is of limited value for identifying adelgids (Hemiptera: Adelgidae) but supports traditional morphological taxonomy
VĚCHTOVÁ, Pavlína
The presented study deals with adelgids (Hemiptera: Adelgidae) identification based on the sequence divergence of part of mitochondrial cytochrome ?c oxidase I (COI) gene used for ?DNA barcoding?. Analysis evaluates the DNA barcoding ability to discriminate adelgids on the genera level and it supports species identification based on morphological taxonomy. However, it failed to recognize species within species complexes.
Experimental examination of EFL and MATX eukaryotic horizontal gene transfers: co-existence of mutually exclusive transcripts predates functional rescue
RŮŽIČKA, Petr
Many eukaryotic genes do not follow simple vertical inheritance. Elongation factor 1? (EF-1?) and methionine adenosyl transferase (MAT) are enzymes with complicated evolutionary histories and, interestingly, the two cases have several features in common. These essential enzymes occur as two relatively divergent paralogs (EF-1?/EFL, MAT/MATX) that have patchy distributions in eukaryotic lineages that are nearly mutually exclusive. To explain such distributions, we must invoke either multiple eukaryote-to-eukaryote horizontal gene transfers (HGTs) followed by functional replacement, or presence of both paralogs in the common ancestor followed by longterm co-existence and differential losses in various eukaryotic lineages. To understand the evolution of these paralogs, we have performed in vivo experiments in Trypanosoma brucei addressing the consequences of long-term co-expression and functional replacement. In the first experiment of its kind, we have demonstrated that EF-1? and MAT can be simultaneously expressed with EFL and MATX, respectively, without affecting the growth of the flagellates. After the endogenous MAT or EF-1? was down-regulated by RNA interference, MATX immediately substituted for its paralog, while EFL was not able to substitute for EF-1?, leading to mortality. We conclude that MATX is naturally capable of evolving patchy paralog distribution via HGTs and/or long term co-expression and differential losses. The capability of EFL to spread by HGT is lower and so the patchy distribution of EF-1?/EFL paralogs was probably shaped mainly by deep paralogy followed by long term co-existence and differential losses.
Populačně genetická struktura sysla obecného v České republice
ŘÍČANOVÁ, Štěpánka
The European ground squirrel is considered an endangered species with declining numbers throughout Europe. Here, we analysed European ground squirrels from six Czech and one Slovak localities using five microsatellite loci as genetic marker. The results show a strong genetic differentiation among the investigated populations (mean value of FST = 0.16) and high levels of inbreeding (values of FIS ranged from 0.34 to 0.90). One of the most important factors is the lack of migration due to the large distances between the populations and the presence of migration barriers. Based on the results obtained we recommend a few suggestions for a conservation management of this species.

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