Anine Jordaan

Interactions of the antimicrobial peptide nisin Z with conventional antibiotics and the use of nanostructured lipid carriers to enhance antimicrobial activity

Antimicrobial resistance is an imminent threat to the effective prevention and treatment of bacterial infections and alternative antimicrobial strategies are desperately needed. Antimicrobial peptides (AMPs) may be promising alternatives to current antibiotics or act as adjuvants to enhance antibiotic potency. Additionally, the use of biodegradable lipid nanoparticles can enhance the antibacterial activity of antibiotics and antimicrobial peptides. In this study, the interaction of the AMPs, nisin Z and melittin, with conventional antibiotics was investigated on Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli. The effectiveness of nanostructured lipid carriers (NLCs) for the entrapment of nisin Z was also evaluated. Findings revealed that nisin Z exhibited additive interactions with numerous conventional antibiotics. Notable synergism was observed for novobiocin-nisin Z combinations. The addition of the non-antibiotic adjuvant EDTA significantly improved the antimicrobial activity of free nisin Z towards E.coli. NLCs containing nisin Z were effective against Gram-positive species at physiological pH, with an increase in effectiveness in the presence of EDTA. Results indicate that nisin Z may be advantageous as an adjuvant in antimicrobial chemotherapy, while contributing in the battle against antibiotic resistance. NLCs have the potential to enhance the antibacterial activity of nisin Z towards Gram-positive bacterial species associated with skin infections.

In vitro permeation of platinum and rhodium through Caucasian skin

During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace.

Comparative cellular responses in susceptible and resistant soybean cultivars infected by Meloidogyne incognita

Meloidogyne incognita, a predominant nematode parasite of soybean in South Africa, increasingly threatens production of the crop as it is expanding to maize-producing areas infected by this nematode. The parasitic relationship between M. incognita and soybean were compared on a susceptible and a resistant cultivar in terms of nematode penetration, development, reproduction and fecundity as well as histopathology studies. Second-stage juveniles (J2) of M. incognita were inoculated on roots of a resistant (LS5995) and a susceptible (Prima2000) cultivar in three concurrent but separate glasshouse trials. For pre-infectional studies, root systems of plants were harvested 2, 4, 10, 16 and 20 DAI. Sampling times for the post-infectional experiment were 4, 10, 20 and 30 DAI, whilst those for the histopathology experiment were 2, 4, 10, 20 and 30 DAI. J2 penetrated roots of both cultivars in comparable numbers 2 DAI but vermiform J2 numbers were significantly lower in roots of LS5995 at 4, 16 and 20 DAI. Final (Pf) J2 population density (vermiform plus swollen individuals) in roots of Prima2000 was significantly higher at all sampling times than those in roots of LS5995. Development of M. incognita J2 to third- (J3) and fourth-stage juveniles (J4) was significantly affected by cultivar susceptibility and time, being slower in LS5995. Development of J2 to J3 and J4 or into mature females was also consistently slower in LS5995 for the duration of this experiment. Adult females in roots of Prima2000 produced significantly more (98%) eggs per egg mass and also maintained significantly more egg and J2 numbers (98.5%) per root system 30 DAI than those in roots of LS5995. Histopathological observations showed that J2 penetrated roots of both soybean cultivars and migrated intercellularly to undifferentiated provascular tissue 2 and 4 DAI, with pronounced cellular changes taking place. A hypersensitive reaction was observed 2 DAI in roots of the resistant cultivar. From 10 to 30 DAI giant cell formation in the differentiated vascular tissue in the roots of LS5995 differed substantially from those in roots of Prima2000. Giant cells that developed in roots of the LS5995 were smaller and fewer compared to those in Prima2000. Giant cells in roots of LS5995 also contained empty as well as sub-optimal giant cells with thicker cell walls than those reported for resistant soybean cultivars in earlier studies. The induction, development and maintenance of giant cells in LS5995 proved to be typically retarded.

Hairy stalagmites, a new biogenic root speleothem from Botswana

(Hill & Forti, 1997). Today, it’s generally accepted that plants (mainly roots) can passively advance the development of speleothems by enhancing capillary migration of water to structures where evaporation occurs (Forti, 2001). Also, it has recently been shown that microbial communities can actively influence the genesis and development of certain subaqueous and/ or vadose speleothems (Melim et al., 2001; Barton & Northup, 2007; Dodge-Wan & Deng Hui Min, 2013). Roots are the single portion of a tree which may somehow contribute towards speleothem development, however, it is presumably rare in deeper parts of caves since roots generally do not reach depths greater than several metres. Nevertheless, the morphological effects induced by roots over speleothems are evident. The surfaces of roots that enter cave voids may serve as pathways for the flow of seeping water and, if environmental conditions are favourable, the precipitation of CaCO3 (calcium carbonate). This mechanism causes the development of peculiar stalactites and columns with a tilted and

Whey Protein/Polysaccharide-Stabilized Oil Powders for Topical Application—Release and Transdermal Delivery of Salicylic Acid from Oil Powders Compared to Redispersed Powders

Oil-in-water (o/w) emulsions are commonly converted into solid-like powders in order to improve their physical and chemical stabilities. The aim of this study was to investigate whether whey protein/polysaccharide-stabilized o/w emulsions could be converted into stable oil powders by means of freeze-drying. Moreover, during this study, the effects of pH and polymer type on release and trans(dermal) delivery of salicylic acid, a model drug, from these oil powders were investigated and compared to those of the respective template emulsions and redispersed oil powders. Physical characterization of the various formulations was performed, such as droplet size analysis and oil leakage, and relationships drawn with regards to release and trans(dermal) delivery. The experimental outcomes revealed that the oil powders could be redispersed in water without changing the release characteristics of salicylic acid. pH and polymer type affected the release of salicylic acid from the oil powders, template emulsions, and redispersed powders similarly. Contrary, the transdermal delivery from the oil powders and from their respective redispersed oil powders was differently affected by pH and polymer type. It was hypothesized that the release had been influenced by the electrostatic interactions between salicylic acid and emulsifiers, whereas the transdermal performance could have been determined by the particle or aggregate sizes of the formulations.

Ultrastructural Comparison of Hepatozoon ixoxo and Hepatozoon theileri (Adeleorina: Hepatozoidae), Parasitising South African Anurans.

To date, only two haemogregarine parasite species have been described from South African anurans: Hepatozoon ixoxo, infecting toads of the genus Sclerophrys (syn. Amietophrynus); and Hepatozoon theileri, parasitising the common river frog, Amietia quecketti. Both species have been characterised using limited morphology, and molecular data from PCR amplified fragments of the 18S rRNA gene. However, no ultrastructural work has been performed thus far. The aim of this study was to add descriptive information on the two species by studying their ultrastructural morphology. Mature gamont stages, common in the peripheral blood of infected frogs, were examined by transmission electron microscopy. Results indicate that H. ixoxo and H. theileri share typical apicomplexan characteristics, but differ markedly in their external cellular structure. Hepatozoon ixoxo is an encapsulated parasite presenting a prominent cap at the truncate pole, and shows no visible modifications to the host cell membrane. In comparison, H. theileri does not present a capsule or cap, and produces marked morphological changes to its host cell. Scanning electron microscopy was performed to further examine the cytopathological effects of H. theileri, and results revealed small, knob‐like protrusions on the erythrocyte surface, as well as notable distortion of the overall shape of the host cell.

The family Lohmanniidae (Acari, Oribatida) II: two new Oribatid mites, Meristacarus perikopesis sp. n. from Costa Rica and Torpacarus eidikoterai sp. n. from Kenya

Abstract Two very particular new species of the family Lohmanniidae were studied and described using optical and Scanning Electron Microscopy (SEM). Meristacarus perikopesis sp. n. displays complex cuticular microsculpture with cross-shaped grooves and pusticulate porose areas; ten transversal bands, with reticulate-foveate microsculpture; S4, S5, S7, S10 not crossing medial notogastral plane, amongst other characters. Torpacarus eidikoterai sp. n. with: prodorsum - rostrum weakly bilobate with small central structure and CSO present. Six transversal depressions present, transversal bands absent; but six transversal depressions present, none of the depressions crossing medial notogastral plane.

Revision of the family Carabodidae (Acari: Oribatida) XV. Costacarabodes turrialbai gen. nov., sp. nov. and Tuberocepheus kompsosis sp. nov from Costa Rica

ABSTRACT Costacarabodes turrialbai gen. nov., sp. nov. and Tuberocepheus kompsosis sp. nov. from Costa Rica are described using optical and scanning electron microscopy. Costacarabodes turrialbai gen. nov., sp. nov. is a new genus with particular characteristics: prodorsum with elevated interlamellar process divided by a deep depression; interlamellar, lamellar, and rostral setae very different in shape and size; eight pairs of notogastral setae; notogaster incompletely surrounded by circumgastric depression interrupting posterior notogastral zone; pedotectum I as normal extending lamina; pedotectum II reduced or absent; tutorium small, aligned dentitions present in inferior zone; epimeral zone with depressions; conspicuous longitudinal medial epimeral depression, demarcated by semicircular cuticular thickening; epimeral formulae 1-1-3-3; epimeral setae 3b, 3c parallel to each other; articulation of genu-tibia III and IV each with dorsal socket. T. kompsosis sp. nov. is differentiated from T. longus by pusticulate microsculture on ventral zone, humeral apophysis; lateral lamellar zone and epimeral zone; reticulate-foveate microsculpture on area of posterior prodorsal depression; punctate microsculpture on subcapitular zone; simple, setae with small dentitions: notogastral, rostral, interlamellar setae; simples basally inflated a sub-capitular setae; elevated interlamellar process with depressed central area, defining two triangular to polyhedral structures; polyhedral notogastral anterior depression well defined, with posterolateral cuticular ridges; three central notogastral promontories, of which two round to ovoid, and one semicircular; with lateral pairs of promontories (first pair large, oval; second pair medium sized, ovoid). Lateral prodorsum with anterior tutorial depression, well-developed posterior tutorial depression; anal plate with rounded depression anterior to sharp tip. http://www.zoobank.org/urn:lsid:zoobank.org:pub:4555F169-871C-4921-8710-A3DF8EF32AEE

Synthesis and characterisation of silver nanoparticles using leaf extract of Artemisia afra and their in vitro antimicrobial and antioxidant activities

In this study, the conversion of silver ions into ∼30.74 nm sized silver nanoparticles (AgNPs) was achieved in 30 min at a reaction temperature of 80-90°C in aqueous leaf extract of Artemisia afra. The synthesised AgNPs showed surface plasmon resonance in the range of 423-438 nm. Spherical and face-centred cubic nanoparticles were confirmed by transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis, respectively. Fourier transform infra-red (FTIR) results indicated that the obtained nanoparticles were stabilised and capped through the carbonyl and carboxylate ion groups possibly from flavonoids, terpenoids, phenolics and esters content of the extracts. In addition, the AgNPs were assessed for their biological potentials against some microbes and, also, their free radical scavenging ability was established. The AgNPs exhibited interesting antimicrobial and antioxidant properties better than the aqueous extract of A. afra.

Pollen morphology and folding of Prototulbaghia Vosa (Amaryllidaceae), South Africa

Abstract Prototulbaghia is a genus within the Tulbaghieae in subfamily Allioideae (Amaryllidaceae) and comprises two species restricted to the northeastern escarpment of South Africa. The pollen morphology of these species is studied with the use of scanning electron and transmission electron microscopy. The pollen is compared with that of representatives from the sister genus Tulbaghia (Tulbaghia simmleri and Tulbaghia violacea) and sister tribe Leucocoryneae (Nothoscordum borbonicum). The pollen morphology of Prototulbaghia differs from other members of the Allioideae in both the shape of the pollen grains and the ornamentation of the sulcus membrane. The pollen grains of both Prototulbaghia species are oblate-spheroidal with a reticulate surface ornamentation, the sulcus membrane contains sexine elements (pila), and the wall is thick. Dehydrated grains of both Prototulbaghia species are also triangular in shape after folding due to the length of the sulcus and the thickening of sexine elements in the centre thereof. This type of folding is proposed as a taxonomic character to distinguish the dehydrated pollen grains of this genus from pollen grains of other members of the Allioideae.