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"Marnewick, Michael"
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Are we sinking African cheetahs in India?
SIGNIFICANCE : The current initiative to export African cheetahs to India has a limited scientific basis, placing the Asian subspecies and the translocated animals at risk. There is no evidence that this will benefit African cheetah conservation. We call for a globally coordinated approach to cheetah conservation, based on sound science.
Journal Article
Anti-Tyrosinase and Radical Scavenging Activities of Selected Cassipourea Plants and Isolated 7-Methoxygeranin A: Traditional Use as Skin Lighteners
In rural areas of KwaZulu-Natal and Eastern Cape Provinces, South Africa, women have traditionally used bark extracts from
, and
for skin lightening and sun protection. This study investigates the anti-tyrosinase and antioxidant activities of methanolic bark extracts from these species, aiming to validate their traditional use and identify potential lead compounds for the treatment of skin hyperpigmentation.
Anti-tyrosinase activity was evaluated using half-maximal inhibitory concentration (IC
) values, and antioxidant capacity was measured through FRAP, DPPH, and TEAC assays. Polyphenol and flavanol contents were quantified using Folin-Ciocalteu method. Potential lead compounds were identified through molecular docking, pharmacokinetic analysis, and molecular dynamics (MD) simulations. Statistical analyses, including ANOVA and post-hoc tests, compared extract activities.
exhibited the most potent anti-tyrosinase activity (IC
: 37.10 µg/mL), though statistical differences among species were non-significant.
showed the highest polyphenol (143.68 mg GAE/g) and flavanol (14.67 mg QE/g) content, correlating with superior antioxidant activity (FRAP: 526.07 µmol AAE/g; DPPH: 390.26 µmol TE/g; TEAC: 596.98 µmol TE/g). The isolated compound 7-methoxygeranin A demonstrated lower anti-tyrosinase activity (IC
: 45.16 µg/mL) compared to
extract, suggesting the presence of more potent metabolites. Molecular docking and MD simulations identified emodin 6,8-dimethyl ether as a thermodynamically stable lead compound (binding free energy: -39.88 kcal/mol), interacting with key catalytic residues over 150 ns. The compound demonstrated prolonged residence at the active site of tyrosinase, indicating strong-binding stability.
While
demonstrated the strongest anti-tyrosinase activity, C. gummiflua showed the highest antioxidant potential. Emodin 6,8-dimethyl ether emerged as a promising candidate for skin-lightening applications, warranting further in vitro and in vivo validation. These findings support the traditional use of
species and highlight their potential for developing natural skin health products. Further studies are needed to explore the pharmacokinetics, safety, and efficacy of these compounds in clinical settings.
Journal Article
IMPACT OF STANDARD WORK FOR LEADERS ON REDUCING UNUSED EMPLOYEE CREATIVITY DURING LEAN IMPLEMENTATION
Organisations implement lean in production to improve continuously, but implementation may be unsuccessful due to ineffective leadership. Also, organisations have not eliminated the eighth lean waste - namely, the waste of unused employee creativity. The research investigated standard work for leaders in reducing unused employee creativity. The case study, conducted in an automobile manufacturer, indicated that worker ideas increased when employees were trained in lean, and when standard work for leaders was implemented. The research concluded that standard work for leaders reduces the waste of unused employee creativity, and suggests a lean implementation model that can be validated with further work.
Journal Article
Effects of habitat quality and access management on the density of a recovering grizzly bear population
1. Human activities have dramatic effects on the distribution and abundance of wildlife. Increased road densities and human presence in wilderness areas have elevated human-caused mortality of grizzly bears and reduced bears' use. Management agencies frequently attempt to reduce human-caused mortality by managing road density and thus human access, but the effectiveness of these actions is rarely assessed. 2. We combined systematic, DNA-based mark-recapture techniques with spatially explicit capture-recapture models to estimate population size of a threatened grizzly bear population (Kettle-Granby), following management actions to recover this population. We tested the effects of habitat and road density on grizzly bear population density. We tested both a linear and threshold-based road density metric and investigated the effect of current access management (closing roads to the public). 3. We documented an c. 50% increase in bear density since 1997 suggesting increased landscape and species conservation from management agencies played a significant role in that increase. However, bear density was lower where road denisities exceeded 0.6 km/km² and higher where motorised vehicle access had been restricted. The highest bear densities were in areas with large tracts of few or no roads and high habitat quality. Access management bolstered bear density in small areas by 27%. 4. Synthesis and applications. Our spatially explicit capture-recapture analysis demonstrates that population recovery is possible in a multi-use landscape when management actions target priority areas. We suggest that road density is a useful surrogate for the negative effects of human land use on grizzly bear populations, but spatial configuration of roads must still be considered. Reducing roads will increase grizzly bear density, but restricting vehicle access can also achieve this goal. We demonstrate that a policy target of reducing human access by managing road density below 0.6 km/km², while ensuring areas of high habitat quality have no roads, is a reasonable compromise between the need for road access and population recovery goals. Targeting closures to areas of highest habitat quality would benefit grizzly bear population recovery the most.
Journal Article
Tracking data from nine free-roaming Cheetahs (Acinonyx jubatus) collared in the Thabazimbi area, Limpopo Province, South Africa
In partnership with the University of Pretoria, the Endangered Wildlife Trust’s Carnivore Conservation Programme collared six male and three female free-roaming Cheetahs ( Acinonyx jubatus ) in the Thabazimbi area in Limpopo Province, South Africa. This study was undertaken to determine the spatial ecology of free-roaming Cheetahs that occur outside of formal protected areas on private ranchland, where they frequently come into conflict with, and are sometimes killed by, private landowners. The data were collected between September 2003 and November 2008, resulting in a total of 3165 location points (65 points from VHF collars and 3100 from GPS collars) for nine individual Cheetahs. This dataset provides distribution information about this Vulnerable species occurring outside of protected areas within South Africa. The dataset has been published to the Global Biodiversity Information Facility (www.GBIF.org) and provides the largest dataset on Cheetahs thus far, and, although it is spatially limited to a relatively small region on the African continent, it is the first study of its kind within South Africa. Also of significance is that the fate of 6 of the 9 collared Cheetahs is known, all except one of which died of anthropogenic causes.
Journal Article
Survival of Cheetahs Relocated from Ranchland to Fenced Protected Areas in South Africa
This chapter contains sections titled:
Summary
Introduction
Methods
Results
General discussion
Acknowledgements
Notes
References
Book Chapter