Zinc-induced interactions of the metal-binding domain of beta-amyloid with nucleic acids and glycosaminoglycans

Zinc ions form complexes with β-amyloid peptides and play an important role in Alzheimer’s disease pathogenesis. It has been demonstrated by turbidimetry and correlation spectroscopy that synthetic peptide Aβ16 representing the metal-binding domain of β-amyloid is able to interact with nucleic acids, chondroitin polysulfate, and dextran sulfates in the presence of zinc ions. The amino acid D7H substitution enhanced the peptide binding to polyanions, whereas the H6R and H6A-H13A substitutions abolished this interaction. It is suggested that the metal-binding domain may serve as a zinc-dependent site of β-amyloid interaction with biological polyanions including DNA, RNA, and glycosaminoglycans.     

Genetic diversity of rodent species sold in South African pet shops

Murid rodents are considered globally important invasive species, yet they are still sold in the pet trade. Little is known about the genetic diversity of traded rodents, and many species are incorrectly identified in the pet trade. We used mitochondrial gene regions to assess the taxonomy and genetic diversity of 149 rodents sold in pet shops across eight South African provinces. We identified a total of 112 specimens as Mus musculus, while 31 were Rattus norvegicus, and six were identified as the southern African endemic, southern multimammate mouse Mastomys coucha. Phylogenetic analyses revealed that the three species were monophyletic. Mus musculus and R. norvegicus showed higher levels of genetic diversity, with 19 unique mtDNA haplotypes recovered for M. musculus and eight haplotypes for R. norvegicus. KwaZulu-Natal, Western Cape and Gauteng Provinces had the most unique haplotypes than other provinces. Our findings showed that non-native species are widely distributed in the South African pet trade industry, while M. coucha was not widely traded, although recorded in three provinces. This suggests that most provinces comply with the trade regulations on native species, but the threat of invasive rodents to South Africa's unique biodiversity is highlighted.     

DNA-led rediscovery of the giant sable antelope in Angola

The giant sable antelope (Hippotragus niger variani), unique to Angola, was feared extinct after almost three decades of civil war. Comparisons of mitochondrial DNA sequences derived from dung samples recently collected in the field and from old museum specimens of certain provenance provide the first documented evidence to date that this enigmatic antelope has survived. Its DNA-led rediscovery in the former combat zone was subsequently confirmed by photographic evidence. The Angolan isolate constitutes a distinct monophyletic group that shows a dramatic population decline from historic levels. It represents a diagnosable conservation unit which is characterised by unique cranial morphological features (Blaine 1922 1922:317–339), a highly restricted range, and the presence of fixed genetic differences in all of its common relatives.