Browsing by Author "Curry, Lyle"

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    Characterization of transcripts expressed from the Meis2 locus in the Natal Long-fingered bat (Miniopterus natalensis)
    (2014) Curry, Lyle; Illing, Nicola; Jacobs, David S
    The Myeloid ecotropic insertion site 2 (Meis2) gene is an important transcriptional regulator involved in the pattering of the limb during vertebrate development. In the forelimbs (wings) of bats the expression Meis2 was shown to be differentially expressed when compared to mice forelimbs. Meis2 was found to be present in the interdigital webbing of the autopod (hand) of the developing bat forelimb. In both the mouse and the bat, two separate transcripts were discovered to be expressed from the 3’and 5’ region of the Meis2 locus. The 3’ transcripts corresponded to annotated Meis2 mRNA transcripts, the 5’ transcript corresponded to an mRNA transcript that did not code for any known protein. The 5’ transcript was thought to be a long non-coding RNA and was termed lncMeis2. In this study Random Amplification of cDNA Ends (RACE) analysis was used to identify the RNA transcripts expressed from the Meis2 locus and to verify the presence of lncMeis2. RACE was performed on the heads and forelimbs of the Natal Long-fingered bat (Miniopterus natalensis) and the mouse (Mus musculus) and the products sequenced and aligned to the mouse genome for verification.
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    Open Access
    The evaluation of tests for the identification of semen
    (2016) Curry, Lyle; Heathfield, Laura
    The identification of bodily fluids for forensic purposes is typically classified as either presumptive or confirmatory. Presumptive tests (PT) are conducted first to screen for certain compounds which are relatively specific to particular fluids. Confirmatory tests are used to confirm the identity of a body fluid. Semen is one of the most common bodily fluids encountered in sexual assault cases and contains high concentrations of the acid phosphatase (AP) enzyme. The brentamine FB reagent reacts with the AP that is present in semen, and turns purple. If the colour change is observed within a specific time threshold, it is considered presumptively positive for semen. Cut-off time varies considerably between forensic laboratories, but in South Africa, the cut-off time is defined as 65 seconds. Additionally, semen may be considered to be from human origin if it reacts within 50 seconds. These cut off times have been arbitrarily defined, and there is little research in a local context to substantiate or inform the threshold time for the brentamine FB test for semen. Therefore this study assessed the sensitivity, specificity and kinetics of the brentamine FB test on semen from South African male volunteers (n=15), canines (n=2) and various fruit extracts and compared these results to purified human AP. Each semen sample was subjected to the PT in an indirect and direct method, and these tests were performed both on fresh and aged samples. The majority of fruit extracts yielded a distinctly different colour change compared to the purple that was produced from semen except for mushroom which also turned purple. Absorbance spectroscopy was used to determine the rate of the reaction at 525 nm. There were no significant differences between the rate of reaction for fresh and aged samples using both direct and indirect testing.
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    Open Access
    The evaluation of the specificity of the Acid Phosphatase test to identify semen
    (2018) Conrad, Robyn; Heathfield, Laura; Curry, Lyle
    The burden of sexual assault cases in South Africa is exceptionally high, and analysis of biological material in these cases may provide evidence towards a criminal investigation. These analyses include the identification of biological material to: (i) presumptively identify if semen may be present in order to guide downstream DNA profiling analysis to identify the alleged assailant; and (ii) confirm if semen was indeed present to provide evidence of ejaculation. The presumptive test used to detect the possible presence of semen is the Brentamine Fast Blue (FB) test, which detects the presence of acid phosphatase (AP) by a colour change reaction. AP is an enzyme which is present in human semen in high concentrations, but is also found in animal semen at lower concentrations. The current methods of presumptive testing cannot differentiate between animal and human semen. The specificity of the Brentamine FB test was therefore explored in this study, by subjecting semen from humans (n = 16), dogs (n = 13), horses (n = 5), ostriches (n = 9), and rams (n = 13) to this test; and measuring the enzyme kinetics using a novel method: UV-Vis spectrophotometry. Reaction kinetics showed a significant difference in the AP activity between humans and each of the four different animal species in this study (p < 0.001). Confirmatory testing was also performed using microscopy and morphological differences were seen between human and animal spermatozoa, with significant differences between human, ram, ostrich and dog semen (p < 0.05) but not horse semen (p > 0.05). This study demonstrates that enzyme kinetics holds potential to increase the specificity of presumptive testing for human semen, which could possibly be supplemented with microscopy-based confirmatory testing. These results are of value to forensic scientists who may be faced with questions regarding semen specificity in casework. Further, the baseline of semen morphometric dimensions generated for each species’ can aid in forensic investigations for comparison with evidential samples.