http://hdl.handle.net/10204/890 2013-05-19T12:15:34Z 2013-05-19T12:15:34Z Sanyika, TW Stafford, W Cowan, DA http://hdl.handle.net/10204/6697 2013-04-18T21:55:13Z 2012-08-01T00:00:00Z

Title: The soil and plant determinants of community structures of the dominant actinobacteria in Marion Island terrestrial habitats, Sub-Antarctica Authors: Sanyika, TW; Stafford, W; Cowan, DA Abstract: Marion Island is a Sub-Antarctic island made up of distinct ecological habitats based on soil physiochemical, plant cover and physical characteristics. The microbial diversity and ecological determinants in this harsh Sub-Antarctic environment are largely uncharacterized. Actinobacteria have diverse ecological functions related to soil and plant functioning. This study was aimed at characterizing the diversity and community structures of the dominant actinobacteria in the distinct habitats and to identify their determinant soil and plant characteristics. Using the 16S rRNA gene, the denaturing gradient gel electrophoresis patterns and clone library diversity were correlated with the soil and plant characteristics. Multivariate statistical methods were also used to identify determinant soil and plant characteristics. Salinity and pH were the most important soil determinants, and a number of important site-specific plant species may have been important. The Coastal Fellfield Habitat was dominated by sequences of the suborders Micrococcineae (44%) and Propionibacterineae (18%), with salinity identified as the principal determinant. The Cotula Herbfield Habitat was dominated by Frankineae (37%) and Streptosporangineae (38%), which were correlated with organic nutrient concentrations. The Wet Mire Habitat was dominated by Acidimicrobineae (61%), with moisture and organic carbon content as principal components. Culture-dependent studies were complementary to culture-independent studies with the majority of actinobacteria isolated not identified in 16S rRNA gene clone libraries. This study demonstrates how the soil physiochemical characteristics and plant species independently determine the community structures of the dominant actinobacteria in distinct ecological habitats. These factors subsequently influence their ecological adaptation, roles and functions. Description: Copyright: 2012 Springer Verlag. This is an ABSTRACT ONLY. The definitive version is published in Polar Biology, vol. 35(8), pp 1129-1141

2012-08-01T00:00:00Z Mngenge, NA Nelufule, NN Nelwamondo, FV Msimang, M http://hdl.handle.net/10204/6693 2013-04-18T21:55:14Z 2012-11-01T00:00:00Z

Title: Fingerprint pores extractor Authors: Mngenge, NA; Nelufule, NN; Nelwamondo, FV; Msimang, M Abstract: Automatic Fingerprint Recognition Systems (AFRSs) rely on minutiae position and orientation within the fingerprint image for matching. Minutiae information is highly accurate provided that the fingerprint image matched is of high quality. However, this is not always the case because of diseases and hash working conditions that affect fingerprints. In order to maintain high level of security independent of varying fingerprint image quality research suggests the use of other fingerprint features to compliment minutiae. These are things like ridge contours, sweat pores, dots, and incipient ridges. Sweat pores have been proven as one of the most distinctive among these feature. Thus in order to improve accuracy of AFRSs pores can be fused with minutiae or used alone. Sweat pores have been less utilized in the past due to constraints imposed by fingerprint scanning devices and resolution standards. Recently, progress has been made on both scanning devices and resolution standards to support the use of pores in AFRSs. However, very few techniques exist for extracting, matching and fusing them with minutiae. Matching and fusion can only be possible if pores are available. Some techniques have been proposed to reliable extract pores. However, existing techniques can only work on one resolution i.e. an algorithm proposed and tested on 500dpi cannot work on 1000dpi without minor modifications because pores size change if resolution changes. In addition, existing pore extraction techniques are computationally expensive. In this paper an algorithm to extract feature level 3 (pores) is proposed. The algorithm uses Laplacian of Gaussian (LoG) in Fourier domain in order to reduce computation. The performance of the proposed algorithm is tested on two distinct databases with different resolutions in order to validate its accuracy. The accuracy of the proposed algorithm is further measured using false detection rate (FDR) and true detection rate (TDR). Results show that FDR ranges from 10-35% while TDR ranges from 65-90%. Description: 2012 National Conference on Computing and Communication Systems, Durgapur, West Bengal, India, 21- 22 November 2012. To be published in IEEE Xplore

2012-11-01T00:00:00Z Rossouw, CL Chetty, A Moolman, FS Birkholtz, L-M Hoppe, H Mancama, DT http://hdl.handle.net/10204/6406 2012-12-11T21:55:26Z 2012-08-01T00:00:00Z

Title: Thermo-Responsive non-woven scaffolds for ‘‘smart’’ 3D cell culture Authors: Rossouw, CL; Chetty, A; Moolman, FS; Birkholtz, L-M; Hoppe, H; Mancama, DT Abstract: The thermo-responsive polymer poly(Nisopropylacrylamide) has received widespread attention for its in vitro application in the non-invasive, nondestructive release of adherent cells on two dimensional surfaces. In this study, 3D non-woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (PET), and nylon that had been grafted with PNIPAAm were tested for their ability to support the proliferation and subsequent thermal release of HC04 and HepG2 hepatocytes. Hepatocyte viability and proliferation were estimated using the Alamar Blue assay and Hoechst 33258 total DNA quantification. The assays revealed that the pure and grafted non-woven scaffolds maintained the hepatocytes within the matrix and promoted 3D proliferation comparable to that of the commercially available AlgimatrixTM alginate scaffold. Albumin production and selected cytochrome P450 genes expression was found to be superior in cells growing on pure and grafted non-woven PP scaffolds as compared to cells grown as a 2D monolayer. Two scaffolds, namely, PP-g-PNIPAAm-A and PP-g-PNIPAAm-B were identified as having far superior thermal release capabilities; releasing the majority of the cells from the matrices within 2 h. This is the first report for the development of 3D non-woven, thermoresponsive scaffolds able to release cells from the matrix without the use of any enzymatic assistance or scaffold degradation. Description: Copyright: 2012 Wiley-Blackwell. This is an ABSTRACT ONLY.The definitive version is published in the Journal of Biotechnology & Bioengineering, Vol. 109(8), pp 2147-2158

2012-08-01T00:00:00Z Woodborne, S Huchzermeyer, D Govender, D Pienaar, D Hall, G Myburgh, J Deacon, A Venter, J Lubcke, N http://hdl.handle.net/10204/6247 2012-11-04T21:55:22Z 2012-10-01T00:00:00Z

Title: Ecosystem change and the Olifants River crocodile mass mortality events Authors: Woodborne, S; Huchzermeyer, D; Govender, D; Pienaar, D; Hall, G; Myburgh, J; Deacon, A; Venter, J; Lubcke, N Abstract: Nile crocodile (Crocodilus niloticus) mass mortality events in the Olifants River between the Letaba River confluence in South Africa and Lake Massingir in Mozambique have been attributed to pansteatitis: a disease that affects fat depots of the animals. The disease is also found in sharptooth catfish (Clarias gariepinus) in the same area, and the cause of the disease is attributed to pollution. Although the Olifants River Valley is polluted, the impact of interventions such as dam construction on biodiversity receives little attention. We show that the onset of the pansteatitis epidemic in crocodiles and sharp tooth catfish at the Olifants/Letaba confluence coincided with back-flooding of Lake Massingir that changed the Olifants River from a rock and sand substrate river to a clay substrate lake. Isotopic analysis shows that sharptooth catfish shifted from a predominantly vegetarian to a piscivorous diet that is highly correlated with pansteatitis prevalence, and crocodiles and tiger fish (Hydrocynus vittatus) show coincident trophic level increases. The evidence suggests that the ecosystem change altered the structure of the lotic foodweb and that an exotic or extralimital fish has invaded the confluence and is the vector of the pansteatitis epidemic. The invasive fish species is yet to be identified. The pansteatitis epidemic is an unintended ecological consequence of damming this river. Description: Copyright: 2012 Woodborne et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits restricted use, distribution, and reproduction in any medium, provided the original author and sources are credited.

2012-10-01T00:00:00Z