A diverse assemblage of exquisitely-preserved fossil animals and plants were collected from Sawmill Sink blue hole in Abaco, Bahamas. More than 40 species have been identified including extinct tortoise, an extant crocodile, and birds that no longer live in The Bahamas. This study addresses the mechanisms that preserve fossils in blue holes and discusses paleoecological implications from faunal diversity and sediment composition. Blue holes are waterilled caves with surface openings that may trap animals and surface-driven vegetation. In Sawmill Sink the talus cone within the halocline acts as a substrate on which organics collect that drive microbe ecology. Their byproducts, hydrogen sulfide and anoxia, inhibit biological destruction and delay necrolysis. Low tidal flow and quiescent water conditions further enhance stability of the depositional environment. In addition, subaerial conditions during glacial lowstands allowed owls to roost; their deposits formed a rich assemblage of small fossil vertebrates.

This thesis is a study of vertebrate distribution in relation to certain habitats in cetral Kane County, Utah. Four areas were trapped, two in a sagebrush community and two in a grassland community. Oryzopsis hymenoides (Roem & Shult.) Ricker, Hilaria jamesii (Torr) Benth., Ephedra torreyana S. Watts and Guttierrezia sarothrae (Purah.) Britt and Rusby, were the dominant plants in the grassland community. The dominant plants in the sagebrush community were Artemisia tridentata Nutt., and Hilaria jamesii (Torr.) Benth. Dipodomys ordii cupidineus Goldman was the most common mammal trapped in both communities. Peromyscus maniculatus sonoriensis (LeConte) was trapped most often in the sagebrush community, but rarely taken in the grassland community. Reithrodontomys megalotis megalotis (Baird), was trapped most often in the grassland and only rarely in the sagebrush community. This cricetid seemed restricted to a habitat that offered a large amount of shrub and grass cover. Perognathus parvus trumbullensis Benson, seemed to be restricted to the sagebrush community. This was the only species that was not trapped in the grassland community. Perognathus longimembris arizonensis Goldman, on the other hand seemed to be restricted in central Kane County to the grassland community, because it was the only mammal that was not caught in the sagebrush community. Perognathus formosus domisaxensis Cookrum, appears to be the ecological equivalent on the Cockscomb Ridge of P. parvus in the sagebrush community and P. longimembris in the grasslands. From the data collected, Onychomys leucogaster melanophrys Merriam, appeared to be limited in distribution to the number of available invertebrates near the trapping transect. Most of the mammals that were trapped on the west side of the ridge, in the sagebrush community, appeared to be darker in color than those from the east side of the ridge. Thomomys umbrinus howelli exhibited a greater color contrast between the two communities than any other species. Closer examination of the skulls of these mammals revealed a difference in the width of the basioccipital between those caught on the west side of the ridge and those caught on the east side. The range of Crotalus viridis lutosus Klauber was extended east from the Cockscomb Ridge to the Paria Plateau. The range of Eutamias dorsalis utahensis Merriam was extended south past Catstairs Canyon.

Comparisons among model organisms make clear that, despite the fundamental importance of recombination in sexually-reproducing species, the mechanisms by which it is directed to the genome can vary markedly. Notably, in mice and humans, recombination almost exclusively occurs where the protein PRDM9 binds DNA. In such species, fine-scale recombination rates along the genome are rapidly evolving, as shifts in PRDM9 binding affinity remodel the landscape. In other species such as birds or canids, PRDM9 has been lost and recombination occurs preferentially at promoter-like features, leading to the conservation of recombination rates over large evolutionary distances. Increased recombination near promoters is also seen in human and mouse knockouts for PRDM9, indicating that this mechanism is normally out-competed by PRDM9 binding. The rapid evolution of complete orthologs of PRDM9 in non-mammalian vertebrates suggests that the protein may play a similar role in directing recombination outside of mammals. In chapter 2 of this work, we test this hypothesis by focusing on the corn snake Pantherophis guttatus, a representative vertebrate species with a single, complete PRDM9 ortholog that is rapidly evolving. We improved the assembly and annotation of the corn snake reference genome and resequenced 24 unrelated corn snake samples to high coverage in order to infer historical recombination rates across the genome from patterns of linkage disequilibrium. We find evidence for elevated recombination around computationally predicted PRDM9 binding sites but, surprisingly, also near promoter features. To verify these findings, we resequenced two pedigrees, identified the PRDM9 alleles segregating in the families and called crossover events that occurred in the parents. This analysis confirmed that crossover events overlap both PRDM9 binding sites and promoter features more than expected by chance. Thus, unlike in mammalian species that rely on PRDM9, in corn snakes there appears to be a mixed use of PRDM9 binding sites and promoter like features, and we find evidence that the relative importance of these features differs between macro- and microchomosomes. We hypothesize that the dual usage of these features reflects a tug of war between PRDM9 and promoter features, whose strength in snakes and possibly other vertebrates has been shifted by changes to a gene that reads the histone modifications made by PRDM9, and likely other genes. In chapter 3, I discuss how follow-up experiments based on these observations could help answer long-standing questions related to the conditions under which PRDM9-directed recombination localization is favorable. Beyond the specific results, this work illustrates how the study of non-model organisms can inform our understanding of basic genetic mechanisms.

No description available.

Thesis (MsCMedSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The gastrointestinal morphology and the distribution of the different types of mucin secreting goblet cells were investigated in three mammalian insectivorous species, namely A. spinosissimus, C. cyanea and A. hottentotus. The aim of the study was to provide a comprehensive morphological comparison between the different species. Another aim was to illustrate and compare the distribution of mucins (neutral, sulfo- and sialomucins) in the gastrointestinal tracts (GITs) of these species, in order to better understand the quality of the biofilm in the GIT. Mucins secreted onto the surface of the GIT have an effect on the colonisation of microflora in the mucosal layer, constructing a biofilm which protects the GIT surface from opportunistic pathogens. The shape, proportional length, and proportional surface areas of the different gastrointestinal regions were recorded and compared in the three species. Histochemical staining methods were used to detect and to distinguish between neutral, sulfo- and sialomucins. The number of goblet cells in the GIT containing each of the above mucins in the epithelium lining the surface or crypts was quantified, and the data expressed as the number of neutral, sulfo- or sialomucin containing goblet cells per mm2 of the surface or crypt epithelium. In all three species the stomach was uncompartmentalised. The internal aspect of the stomach in A. spinosissimus was hemi-glandular, containing stratified squamous epithelium in the fundus, with glandular epithelium in the body and pyloric region. However, C. cyanea and A. hottentotus had wholly glandular stomachs. A. spinosissimus was the only species studied that had a caecum which demonstrated transverse mucosal folds and V-shaped mucosal folds in the proximal colon. Both C. cyanea and A. hottentotus had villi up to the distal part of the GIT. Longitudinal mucosal folds were present in the distal colon. The GITs of both C. cyanea and A. hottentotus showed little morphological differentiation namely a simple, glandular stomach and the lack of a caecum. Mixed (neutral and acid) mucins and mixed acid (sulfo- and sialomucins) mucin secreting goblet cells were prominent mucin cell types in all three mammalian insectivorous species. Despite these general similarities, marked differences were observed in the qualitative expression and distribution of the three types of mucins throughout the GIT. The overall similarity between the three insectivores and other distantly related mammalian species suggests that mixed mucin secreting goblet cell types are prominent contributors to the maintenance of the intestinal biofilm in the majority of mammals, irrespective of their diet or taxonomy. / AFRIKAANSE OPSOMMING: Die bestudering van die morfologie van die spysverteringskanaal (SVK) en die verspreiding van die verskillende musien produserende bekerselle was in drie insek-etende soogdier spesies uitgevoer, naamlik in A. spinosissimus, C. cyanea en A. hottentotus. Die doel van die studie was om „n omvattende morfologiese vergelyking te maak tussen die drie spesies, sowel as om die verspreiding van die verskillende musiene te beskryf in die SVK. Kennis van die verspreiding van die verskillende tipes musiene (neutral, sulfaat en nie-sulfaat bevattende musiene) kan moontlik inligting verskaf aangaande die kwaliteit van die biofilm in the SVK. Die laasgenoemde musiene wat gesekreteer word op die oppervlak van die SVK, bepaal die kolonisasie van die mikroflora in die mukosale laag wat „n biofilm vorm en die SVK beskerm teen patogene. Die vorm, proportionele lengte en proportionele oppervlaks areas van die verskillende SVK gebiede is opgeteken, waarna dit vergelyk is tussen die drie insektivore spesies. Histochemiese kleurings tegnieke is gebruik om die musiene waar te neem en om te onderskei tussen die neutraal, sulfaat en nie-sulfaat bevattende musiene. Die aantal beker selle wat elk van die bogenoemde musiene bevat het, is getel in die oppervlaks epiteel- en kript areas van die SVK. Hierdie data is weergegee as die aantal neutraal, sulfaat en nie-sulfaat bevattende beker selle per oppervlaks epiteel- of kript area (mm2). Die vorm van die maag in al drie spesies was eenvoudig en nie gekompartementaliseer nie. Die interne aspek van die maag in A. spinosissimus het meerlagige plaveisel epiteel in die fundus gehad en klieragtige epiteel in die liggaam en pilorus gedeeltes. Daarbenewens het C. cyanea en A. hottentotus slegs klieragtige epiteel in die maag gehad. A. spinosissimus was die enigste spesie in hierdie studie wat „n sekum gehad het met dwars voue, asook V-vormige mukosale voue in die proksimale kolon. Beide C. cyanea en A. hottentotus het villi tot in die distale gedeelte van die SVK gehad. Longitudinale mukosale voue was teenwoordig in die distale gedeelte van die kolon. Die SVK van beide C. cyanea en A. hottentotus het min morfologiese differensiasie getoon deurdat die spesies „n eenvoudige, klieragtige maag gehad het en geen sekum nie. Gemenge (neutral en suur) musiene asook gemengde suur (sulfaat en nie-sulfaat bevattende) musiene was die dominante musien tipes in the SVK van al drie insek-etende soogdier spesies. Ten spyte van die algemene ooreenkomste, was daar merkwaardige verskille in die getalle en verspreiding van die verskillende musiene in die SVK. Die algemene ooreenkomste tussen die drie insektivore soogdier spesies met soogdiere van ander families, stel voor dat die gemende musien sekreterende beker selle „n prominente bydrae maak tot die onderhoud van die biofilm in the SVK in die meerderheid van soogdiere, ongeag van hul dieet of spesie klassifikasie.

This is an investigation of new vertebrate fossil material from the Late Devonian locality of Ivanovka, Uryup River, Siberia. This bone bed material, circa 375 million years in age, represents a unique opportunity to fill a gap in our understanding of Late Devonian diversity, biogeography, and vertebrate evolution: Siberia, at the time, was an independent continent, and yet its fauna remains virtually unknown in comparison with the other paleocontinents, Euramerica and Gondwana. Using synchrotron microtomographic scanning, a non-destructive technique that has never, to our knowledge, been applied to bone bed material, we obtained 3D image stacks that were then modelled to yield triangle meshes representing the bones in three dimensions. These meshes could then be identified, described, and interpreted. Many of the discovered bones belong to the poorly known genus Megistolepis Obruchev 1955, potentially allowing a radical increase in knowledge regarding this taxon. Other material includes lungfish and possible fragments of limbed tetrapods, though the evidence of the latter is scarce. A discussion of the advantages and disadvantages of synchrotron microtomography for the study of bone bed material concludes the paper.

No description available.

The genus Blastocystis has recently attracted the attention of scientists, especially parasitologists. Similarly to the related opalines and proteromonads, Blastocystis is anaerobic and lives endobiotically in the intestine of various animals. This organism is also often found in humans, where it is associated with irritable bowel syndrome, though its pathogenic potential remains uncertain. The genus Blastocystis is remarkable for its rich genetic diversity. The taxonomy of Blastocystis is inconsistent and problematic. The strains isolated from homoiothermic vertebrates are divided into 17 subtypes, while strains from poikilotherms are either classified as separate species or are not considered in taxonomic studies at all. The aim of the study was to further examine the genetic diversity of the genus Blastocystis. We determined SSU rDNA sequences of 38 strains isolated from poikilothermic vertebrates and arthropods. The results of our phylogenetic analysis showed that Blastocystis is considerably diverse in these hosts, and we defined 21 new subtypes. The total number of known subtypes of Blastocystis has thus increased to 38. We also examined light-microscopical morphology of some strains. Most of the newly defined subtypes show identical morphology, ST20 (Blastocystis geocheloni) is an exception,...

TITLE: Manufacturing taxidermy mounts and their use as teaching aids AUTHOR: Jana Mazalová DEPARTMENT: Department of Biology and Environmental Studies SUPERVISOR: RNDr. Jan Řezníček PhD. ABSTRAKT: The main subject of this thesis is focused on preparation of taxidermal mounts with use of mammal bones and skins and their use as teaching aids. The target group are school children both of elementary and secondary schools. The thesis describes methods of bone preservation and cleaning, skin tanning and preparation of taxidermal mounts. I deal in it also with preparation of large vertebrates' skulls and preparation of taxidermal mounts. The procedures are described in details and the following chapters include photos of dissections made by me. Preparation of 4 bird and 6 mammal species is described. For each description, search of recent literature and PowerPoint presentation is included. KEYWORDS: preparation, taxidermal mounts, skin, vertebrates' skulls

This works main topic is raising vertebrates at school. It includes their problems and benefits. Its aim is to create a clear text offering information to people interested in this activity. The questionnaire method was used to find experiences of teachers from both the Czech Republic and abroad (Norway, Poland, Spain). The result of the research is a survey, which offers a survey of the experiences and views of respondents. Key words: breeding, school, vertebrates, Norway, Poland, Spain, Czech Republic