Browsing by Subject "Molecular Biology"

Now showing 1 - 4 of 4
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    Evolutionary analysis and functional characterization of the forkhead transcription factor FoxG1
    (2006) Bredenkamp, Nicholas; Illing, Nicola
    Forhead box G1 (FoxG1) is a winged-helix transcription factor that plays a crucial role in the development of the telecephalon, the most rostral region of the brain Here, FoxG1 acts as a transcriptional repressor and maintains the population of cortical progenitor cells by promoting their proliferation and inhibiting differrentiation. Vertebrate FoxG1 orthologs have highly conserved DNA-binding and corbosy-terminal domains that have functional roles. Conversely, no functional role has yet been assigned to the N-terminal domain which shows a high degree of variability across vertebrates, with a remarkable stretch of consecutive histidine, proline and glutamine (HPQ) residues in the mammalian orthologs. In this study it was tested whether differences in FoxG1 sequence amongst vertebrates might account for the increased cortex size of mammals compared to non-mammals. Furthermore, changes in the sub-cellular localization of FoxG1 in response to fibroblast growth factor 2 (FGF-2) were investigated in a neural precursor cell line.
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    An investigation of the region of DNA required for Streptocymes Penemafaciens plasmid pSPN1 replication
    (1991) Smith, Anthony; Thomson, Jennifer Ann
    Plasmid pSPNl is a 26.5kb cryptic plasmid, originally isolated from Streptomyces penemafaciens ATCC 31599. A 12.5kb BglII fragment of pSPNl was cloned into the vector pLR2, and this conferred on pLR2 which lacks a Streptomyces origin of replication, the ability to replicate in a number of Streptomyces species. A vector pBlue was constructed by inserting a streptomycin resistance gene from plasmid pIJ4642 into the ampicillin resistance gene of the vector Bluescript. The resistance gene was able to function in both E.coli and Streptomyces species and thus pBlue could serve as a vector for shortening and sequencing in E. coli as well as a origin-probe vector in Streptomyces. The origin-containing BglII fragment of pSPNl was cloned into pBlue to create pFull, which was able to be selected for and replicate in Streptomyces. The conditions affecting selection of pFull in Streptomyces were investigated and optimized. The copy number of pFull was found to be 0.2 per chromosome. Attempts were made to clone origin-containing fragments smaller than the 12.5kb BglII fragment. Initially a Sau3A partial library was made of the origin-containing fragment, this however did not produce any replicating plasmids. As an alternative approach, pFull was extensively mapped and a series of deletion derivatives were constructed. The derivatives were tested for the ability to replicate in Streptomyces. Judging from the deletions that were and were not able to replicate it is apparent that at least 5.5kb of DNA is required for pFull and hence for pSPNl to replicate.
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    Open Access
    Limbs gone batty : the role of the anterior-posterior patterning signal, Sonic Hedgehog, in the development of the unique bat limb
    (2007) Hockman, Dorit; Illing, Nicola; Jacobs, David S
    The unique skeletal structure of the bat forelimb and hindlimb provides a new and exciting model for the field of evolutionary developmental biology, which seeks to reveal the molecular mechanisms behind vertebrate limb diversity. The digits of the bat forelimb, excluding the thumb, are considerably elongated and webbed. The hindlimb digits are free of webbing and are of uniform length, lacking the asymmetrical patterning of the forelimb. In this study, gene expression analysis has revealed that changes in the spatial and temporal expression patterns of the anteriorposterior patterning signal, Sonic hedgehog (Shh), and its downstream target, Patched 1 (PtcJ), have contributed to the development of the unique bat limb. The embryonic development of Miniopterus natalensis (Miniopteridae) is described for the first time and the expression patterns of Shh and PtcJ in the developing limbs of this species are compared to those in Carollia perspicillata (Phyllostomidae) and the mouse. Early in bat limb development (stage 14), Shh expression in the ZPA appears to be anteriorly expanded when compared to the mouse. This observation is in line with the reported expansion of Fgf8 expression in the AER (Cretekos et al. 2007) and reveals that an enhancement of the Shh-Fgf positive feedback loop may be responsible for the initial posterior expansion of the bat forelimb. Later in development (stage 16) Shh and PtcJ acquire a novel domain of expression within the interdigital tissue of both the bat forelimb and hindlimb. These expression patterns parallel the reported up-regulation of Fgf8, Gremlin and Bmp2 in the interdigital tissue of C. perspicillata (Weatherbee et al. 2006) and support the hypothesis that the Shh-Fgfpositive feedback loop is re-initiated in the interdigital tissue of the bat limbs. The cell survival and proliferation signals provided by the Shh-Fgf signalling loop most likely contribute to the lengthening of the posterior forelimb digits, the survival of the tissue between the forelimb digits and the extension of digits 1 and 5 of the hindlimb to the same length of the remaining digits. The novel Shh and PtcJ expression patterns were observed in both M natalensis and C. perspicillata, supporting the monophyly of the chiropteran sub-order, Verspertilioniformes.
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    Peripheral blood mononuclear cells as non-invasive diagnostic indicators of stress-associated neural states
    (2008) Van Heerden, Johannes Hendrik; Illing, Nicola; Stein, Dan
    Researchers have demonstrated the ability to predict psychopathological states from human peripheral immune tissure transcriptional profiles, using microarrays. Although evidence in support of such an approach as a viable diagnostic avenue within psychiatric settings is accumulating, it remains to be demonstrated, in an animal model, that transcriptional changes in peripheral tissue targets are paralleled by specific gene expression changes in neural tissues.