Thesis (Ph.D. (Biochemistry)) - Rhodes University, 2007.

The extant coelacanths have a close resemblance to the coelacanth fossil records dating back to 230mya. Like their predecessors, the extant coelacanths inhabit rocky caves at a depth of 100-300m below sea level. In the Comoros, the water temperature at these depths is estimated to fluctuate between 14-20°C. High-level adaptation to these environment and lack of competition are thought to have led to the morphological uniformity and slow change throughout the history of the coelacanths. Under stress conditions, proteins unfold or misfold leading to the formation of aggregates. Molecular chaperones facilitate the correct folding of other proteins so that they can attain a stable tertiary structure. In addition, molecular chaperones aid the refolding of denatured proteins and the degradation of terminally misfolded protein after cellular stress. Heat shock proteins form one of the major classes of molecular chaperones. Here we show that, despite high-level adaptation to a unique habitat and slow change, the genome of the coelacanth encodes the major and highly conserved molecular chaperone, Hsp70. Latimeria menadoensis and Latimeria chalumnae contain intronless hsp70 genes encoding Hsp70 proteins archetypal of known Hsp70s. Based on the coelacanth codon usage, we have shown that bacterial protein expression systems, particularly Escherichia coli, may not be appropriate for the overproduction of coelacanth Hsp70s and coelacanth proteins in general. Also interesting, was the discovery that like the rat Hsc70, the L. menadoensis Hsp70 could not reverse thermal sensitivity in a temperate sensitive E. coli DnaK mutant strain, BB2362. We also report the successful isolation of a 1.2 kb region of L. menadoensis hsp70 upstream regulatory region. This region contain three putative heat shock elements, a TATA- box and two CAAT-boxes. This regulatory region resembled the Xenopus, mouse, and particularly tilapia hsp70 promoters, all of which have been shown to drive the expression of reporter genes in a heat dependent manner. Taken together, this data is the first to strongly suggest an inducible Hsp70-base cytoprotection mechanism in the coelacanth. It further provides basis to formulate testable predictions about the regulation, structure and function of Hsp70s in the living fossil, Latimeria.

Videography is a valuable tool in biological and ecological studies. Using video footage obtained during previous coelacanth surveys, this thesis investigated coelacanths and their associated habitats in the submarine canyons of iSimangaliso Wetland Park, South Africa. This thesis aimed to (1) describe the biological habitats within the submarine canyons, (2) determine coelacanth distribution within these habitats, and (3) assess the use of computer-aided identification to successfully identify individual coelacanths. Seven different habitat types were noted with the most distinctive being the canyon margins that consisted of dense agglomerations of gorgonians, wire and whip corals, and sponges. Results suggested that although substratum type has a great influence on invertebrate community structure in the canyons, depth is the principal factor. Coelacanths were associated with cave habitats within the steep rocky canyon walls. Habitat analyses allowed predictive classification tree models to be constructed. Depth, underlying percentage of rock, and percentage cover of gorgonians and sponges were the most important variables for determining coelacanth presence and absence. The overall correct classification rate for the model was estimated at 96.6%, correctly predicting coelacanth absence (> 99%) better than presence (60%). Because coelacanths have a unique spot pattern it was possible to quickly and accurately identify specific individuals photographically using computer-aided identification software. Without any manual intervention by an operator the software accurately identified between 56 and 92% of the individuals. Identification success increased to 100% if the operator could also manually select from other potential matching photographs. It was also shown that fish exhibiting a yaw angle not exceeding 60° could be accurately identified in photographs. Each of the sections presented in this thesis represent a possible step towards analysing coelacanth-related habitats, locating and then analysing new habitats. Steps include first locating a population and then performing a habitat analysis. Coelacanth location within the different habitats can then be determined allowing the development of predictive models to potentially identify possible locations of new populations. The final step is to identify individual fish within the population for assessing demographic parameters and population monitoring.

No description available.

The African Coelacanth Ecosystem Programme (ACEP) was established in 2002 after the discovery of a colony of coelacanths off the Maputaland coast at Sodwana Bay, KwaZulu Natal. The environmental education and awareness sub-programme developed learning support materials (LSM's) for use in schools and the materials were disseminated annually through teacher education workshops. This study aimed to uncover the use of these LSM's in the rural schools of Maputaland. The active learning framework was used to analyse the materials. Collectively, the ACEP materials cover a range of active learning aspects; however alignment with the curriculum has resulted in an increased focus on experiments, accompanied by a loss of environmental content and a narrowing scope for active environmental learning. Workshop questionnaires and four school case studies revealed the patterns of practice of use of materials in schools. The stated use of materials by teachers is not fully realized in the actual classroom practice which centres on learning content and concept definitions. There is no culture of use of materials in the schools following the annual introduction of ACEP materials. It was also found that the marine and coastal knowledge holding power is outside the realm of the teachers' practice and control. The findings of this study come at a time when there is uncertainty over the future of South African education and the curriculum. This research may inform the environmental education and coastal and marine education field as to their role in education and more specifically the development of learning support materials.