Occurrence of different Lantana camara varieties across four South African provinces and their susceptibility to a biotype of the gall-forming mite Aceria lantanae

A biotype of the flower-galling mite, Aceria lantanae (Cook) (Trombidiformes: Eriophyidae) collected in Florida (U.S.A.) was released in South Africa in 2007 against Lantana camara L. (Verbenaceae) but has displayed patchy establishment. The occurrence of different L. camara varieties and their susceptibility to A. lantanae were assessed across four provinces with dense infestations. Surveys were undertaken at 113 sites during the mite’s peak infestation period (April–May) in 2013–2015. The occurrence of 13 recorded L. camara varieties differed substantially across and within these provinces. Overall, five varieties accounted for 7–45% of the sampled plants at 9–51% of the surveyed sites. The remaining eight varieties accounted for <1–4% of the plants at 2–9% of the sites. The establishment and impact of A. lantanae differed significantly between L. camara varieties. The mite established best on three varieties (163 LP, 021 WP and 015 OR), with 60–90% of plants infested. Reduced establishments were observed on seven varieties, with 18–50% of plants infested, while no establishment was recorded on three varieties. Where established, A. lantanae inflicted considerable levels of damage (i.e. 51–75% of buds infested) on the most widespread and abundant L. camara variety (163 LP) and on one less common variety (021 WP). Two uncommon varieties (015 OR, 021 P) suffered moderate levels of damage with the remainder suffering only trivial levels. The mite’s impact in South Africa could be improved by complementing the established biotype with others from Central and South America that are better matched with the poorly attacked L. camara varieties.     

Pre-release evaluation of absolute spillover impact risk of Physonota maculiventris (Chrysomelidae: Cassidinae) on non-target plant species Helianthus annuus (Asteraceae) and Zea mays (Poaceae) in South Africa

The tortoise beetle, Physonota maculiventris (Coleoptera: Chrysomelidae), a candidate biological control agent of Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) was screened for spillover risks on non-target plant species in South Africa. Studies were conducted to measure the absolute feeding damage and reproductive performance of P. maculiventris on non-target plant species, Helianthus annuus L. (Asteraceae) and Zea mays L. (Poaceae). The influence of spillover on generational build-up performance on the non-target plant species was also investigated. Adult female beetles were switched from T. diversifolia at 14 (actively feeding colony) or 24 (gravid colony) days to the non-target species. Likewise, as a backup or control, female beetles were exposed to H. annuus in a no-choice situation and switched to T. diversifolia and Z. mays. Feeding damage, adult longevity and egg production of P. maculiventris were significantly lower on H. annuus, compared to those metrics on T. diversifolia. Gravid P. maculiventris adults switched from T. diversifolia on the 14th day after emergence laid a few egg batches on the leaf surfaces of Z. mays, but no signs of feeding were observed. Furthermore, the population of P. maculiventris significantly increased by 11.7 fold (26.8–312.5 adults) between the first (F1) and second (F2) generations on T. diversifolia, while on the non-target, H. annuus, it decreased from 6.3 to zero (0). The study concludes that P. maculiventris will sustain its populations entirely on the target, T. diversifolia population stands associated with or without H. annuus and Z. mays cultivations at different scales in South Africa.     

Persistence of ecologically similar fungi in a restricted floral niche

Fungi in the genera Knoxdaviesia and Sporothrix dominate fungal communities within Protea flowerheads and seed cones (infructescences). Despite apparently similar ecologies, they show strong host recurrence and often occupy the same individual infructescence. Differences in host chemistry explain their host consistency, but the factors that allow co-occupancy of multiple species within individual infructescences are unknown. Sporothrix splendens and K. proteae often grow on different senescent tissue types within infructescences of their P. repens host, indicating that substrate-related differences aid their co-occupancy. Sporothrix phasma and K. capensis grow on the same tissues of P. neriifolia suggesting neutral competitive abilities. Here we test the hypothesis that differences in host-tissues dictate competitive abilities of these fungi and explain their co-occupancy of this spatially restricted niche. Media were prepared from infructescence bases, bracts, seeds, or pollen presenters of P. neriifolia and P. repens. As expected, K. capensis was unable to grow on seeds whilst S. phasma could. As hypothesised, K. capensis and S. phasma had equal competitive abilities on pollen presenters, appearing to explain their co-occupancy of this resource. Growth of K. proteae was significantly enhanced on pollen presenters while that of S. splendens was the same as the control. Knoxdavesia proteae grew significantly faster than S. splendens on all tissue types. Despite this, S. splendens was a superior competitor on all tissue types. For K. proteae to co-occupy infructescences with S. splendens for extended periods, it likely needs to colonize pollen presenters before the arrival of S. splendens.

     

Caffeine induces hyperacetylation of histones at the MEF2 site on the Glut4 promoter and increases MEF2A binding to the site via a CaMK-dependent mechanism

This study was conducted to explore the mechanism by which caffeine increases GLUT4 expression in C(2)C(12) myotubes. Myoblasts were differentiated in DMEM containing 2% horse serum for 13 days and the resultant myotubes exposed to 10 mM caffeine in the presence or absence of 25 microM KN93 or 10 mM dantrolene for 2 h. After the treatment, cells were kept in serum-free medium and harvested between 0 and 6 h later, depending on the assay. Chromatin immunoprecipitation (ChIP) assays revealed that caffeine treatment caused hyperacetylation of histone H3 at the myocyte enhancer factor 2 (MEF2) site on the Glut4 promoter (P < 0.05) and increased the amount of MEF2A that was bound to this site approximately 2.2-fold (P < 0.05) 4 h posttreatment compared with controls. These increases were accompanied by an approximately 1.8-fold rise (P < 0.05 vs. control) in GLUT4 mRNA content at 6 h post-caffeine treatment. Both immunoblot and immunocytochemical analyses showed reduced nuclear content of histone deacetylase-5 in caffeine-treated myotubes compared with controls at 0-2 h posttreatment. Inclusion of 10 mM dantrolene in the medium to prevent the increase in cytosolic Ca(2+), or 25 microM KN93 to inhibit Ca(2+)/calmodulin-dependent protein kinase (CaMK II), attenuated all the above caffeine-induced changes. These data indicate that caffeine increases GLUT4 expression by acetylating the MEF2 site to increase MEF2A binding via a mechanism that involves CaMK II.     

Evaluation of the Influence of thiosemicarbazone–triazole hybrids on genes implicated in lipid oxidation and accumulation as potential anti-obesity agents

A series of thiosemicarbazone–triazole hybrids 1a–h are efficiently synthesised and evaluated for their influence on the expression of genes, cpt-1, acc-1 and pgc-1, which are essential in lipid metabolism. The test results show that hybrids 1c and 1g exhibited relatively high influence on the expression of cpt-1 and pgc-1 and suppression of acc-1 as desired.