A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2015. / Claudins are a family of proteins that are conserved amongst all vertebrates, they are integral in the formation and maintenance of the tight junctions between epithelial cells. Claudins are implicated in embryo morphogenesis, vertebrate evolution, solute movement, cell-cell adhesion, designation of cellular and tissue identity, and several diseases when mutated. Petromyzon marinus (the sea lamprey) is the most basal extant vertebrate and is a model organism in both developmental and evolutionary biology for this reason. In this study, the expression patterns and functions of novel claudin genes in P. marinus were examined with the aim of discovering more about the role of claudins in vertebrate evolution. Presumptive claudin genes in P. marinus were compared to all known claudins in the NCBI database. Primers were designed against all known P. marinus claudin genes and RT-PCR was performed in order to determine their expression levels at embryonic stages E8 to E18, as well as in adult eye, gill, heart, liver and skin tissues. Probes were designed against Claudin 1a, Claudin 9, Claudin 10 and Claudin 19b and RNA in situ hybridisation was performed on embryos at developmental stages E4 to E31 in order to determine their spatial expression patterns. Areas of common claudin gene expression appear to include the pharyngeal arches, otic placode, neural tube, notochord and ectoderm. Claudin 1a is uniquely expressed in the lamprey migrating neural crest. Morpholino-mediated gene knockouts were performed on P. marinus embryos and the loss of Claudin 19b appears to result in abnormal somite morphogenesis.

Lampreys are an important model for the study of early vertebrate development due to their unique evolutionary position as one of only two extant jawless vertebrates. In this study, 12 new putative Hox gene fragments were identified within the recently available Petromyzon marinus (sea lamprey) genome. These and the other previously-identified Hox genes were analyzed phylogenetically, which enabled the assignment of many of the new sequences to distinct paralogous gene clusters and showed distinctions between gnathostome and lamprey Hox sequences. An examination of Hox genes in other lamprey species was conducted using genomic PCR-based detection methods and identified 26 putative Hox gene homeobox fragments from multiple Hox genes across nine lamprey species. A study of Hox10 coding sequences in different lamprey species failed to find any correlation with variable numbers of trunk myomeres in lampreys, which suggests that other sequences or factors regulate the number of myomeres in different species.

The phylogeny of lampreys is controversial, because they possess few taxon-distinctive morphological characters. This is especially true of the relationships among the genus Lethenteron and the closely related genera Eudontomyzon and Lampetra. Thus, the first objective of this thesis was to use DNA sequences of the mitochondrial cytochrome b gene and two nuclear gene introns to infer the phylogeny among these three genera. I found that: 1) Lethenteron plus Eudontomyzon morii without Lethenteron ninae, Lethenteron zanandreai, and Lethenteron sp. S (a distinct cryptic species in the Lethenteron reissneri complex) was monophyletic; 2) Lampetra from the Pacific drainage of North America and Lampetra aepyptera should each be separated, as distinct genera, from Lampetra (including Lethenteron ninae and Lethenteron zanandreai) from the Atlantic drainage of Eurasia; and 3) the remaining Eudontomyzon and the Atlantic Lampetra clustered together in all analyses. The second objective of this thesis was to resolve the relationship among closely related Lethenteron species. Lampreys are either parasitic or non-parasitic, and each non-parasitic (satellite) species is believed to have been derived independently from the parasitic (stem) ancestor. In the phylogenetic analysis, the parasitic Arctic lamprey Lethenteron camtschaticum and its four satellite species were not reciprocally monophyletic. Since network methods are generally more useful for closely related haplotypes than bifurcating trees, a haplotype network of these five Lethenteron species was generated using the cytochrome b gene sequences; Lethenteron appendix showed haplotype frequency distribution differences but there was little support for recognizing the other four taxa as distinct species.

Lampreys are an important model for the study of early vertebrate development due to their unique evolutionary position as one of only two extant jawless vertebrates. In this study, 12 new putative Hox gene fragments were identified within the recently available Petromyzon marinus (sea lamprey) genome. These and the other previously-identified Hox genes were analyzed phylogenetically, which enabled the assignment of many of the new sequences to distinct paralogous gene clusters and showed distinctions between gnathostome and lamprey Hox sequences. An examination of Hox genes in other lamprey species was conducted using genomic PCR-based detection methods and identified 26 putative Hox gene homeobox fragments from multiple Hox genes across nine lamprey species. A study of Hox10 coding sequences in different lamprey species failed to find any correlation with variable numbers of trunk myomeres in lampreys, which suggests that other sequences or factors regulate the number of myomeres in different species.

Thesis (M.S.)--Michigan State University, Dept. of Fisheries and Wildlife, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 89-95). Also issued in print.

The analysis of the publicly available Hox gene sequences from the sea lamprey Petromyzon marinus provides evidence that the Hox clusters in lampreys and other vertebrate species arose from independent duplications. In particular, our analysis supports the hypothesis that the last common ancestor of agnathans and gnathostomes had only a single Hox cluster which was subsequently duplicated independently in the two lineages.

The river lamprey (Lampetra fluviatilis) was previously caught in large numbers in Europe when migrating up in the rivers during autumn for spawning the next spring. It was used as food and was also used as bait in cod fishing in the North Sea. Today the river lamprey has decreased in numbers over much of it’s distribution range, but in the Baltic Sea area, the population is still at a fairly good level, and fishing for lampreys as food (a tradition going back to at least the fifteenth century) is still going on in northern Swedish and Finnish rivers, as well as in coastal rivers in the southern Baltic Sea area. In this article the current situation as regards river lamprey fishing in Sweden, Finland, Latvia and, to some extent, Estonia, Lithuania and Poland is presented.

Bridging knowledge systems is a potential means of equitably and collaboratively working towards shared goals in aquatic ecosystems, such as the management of invasive species. Invasive species pose a significant threat to aquatic ecosystems, and one example of an invasive species with an established control program are sea lamprey (Petromyzon marinus) within the Laurentian Great Lakes. Sea lamprey management faces many challenges including climate change and the apparent declining social acceptance of control programs, especially amongst Indigenous communities in the region. Such challenges illustrate the need for sea lamprey management to better engage Indigenous Nations and knowledge systems. Etuaptmumk (Two-Eyed Seeing) is a Mi’kmaw concept that can facilitate knowledge bridging as it enables Indigenous and Western knowledge systems to work together in parallel on a shared issue. This thesis research uses social science and Indigenous methodologies to understand the Denny’s Dam rehabilitation (sea lamprey barrier) as a case study for relationship-building and knowledge coexistence between Indigenous and non-Indigenous parties in sea lamprey control. Virtual semi-structured interviews (n = 14) were conducted with key decision-makers and others involved in the Denny’s Dam rehabilitation. Results illustrated why and how a knowledge coexistence approach (e.g. Two-Eyed Seeing) could bridge knowledge systems to inform a shared decision-making process. Moreover, findings outline four main factors needed for relationship-building. This study provides practical guidance for practitioners and addresses a gap in the literature concerning Indigenous engagement in sea lamprey management and knowledge coexistence/Two-Eyed Seeing in aquatic invasive species management.

Ball State University LibrariesLibrary services and resources for knowledge buildingMasters ThesesThere is no abstract available for this thesis.

Thesis (Ph. D.)--University of Wisconsin, Madison, 2001. / Includes bibliographical references. Also available on the Internet.