Comparison between the effects of diallyl tetrasulfide on human retina pigment epithelial cells (ARPE-19) and HCT116 cells

Background

Diallyl mono- and polysulfanes from garlic are known to induce an adaptive cell response and the formation of antioxidants in cancer cells. In the case of a severe ER stress and a failure in the response, cancer cells eventually go into apoptosis. Only little is known about the response of normal cells upon treatment.

Methods

Normal ARPE-19 cells were treated with diallyl tetrasulfide to study their cellular response and the results were compared with those of HCT116 cancer cells. Cell viability was checked by an MTT assay and cytofluorimetry. The formation of superoxide radicals, H₂O₂ and thiols were determined and proteins involved in the ER stress response were also detected by Western blot analysis.

Results

We found that diallyl tetrasulfide induced reactive oxygen species (ROS) in normal cells similar to cancer cells in a time (0 to 60 min) and dose dependent manner (0 to 50 μM). The level of heme oxigenase-1 (HO-1) was up-regulated in both cell types. Initially, we found a decrease in the total thiol level in both cell types but in contrast to cancer cells, normal cells recovered from the decrease in the total thiol concentration within 60 min of treatment.

Conclusions

The recovery of the thiol concentration in normal cells treated with diallyl tetrasulfide seems to be responsible for the failure to induce the ER stress signalling pathway and finally apoptosis in normal cells.

General Significance

The difference in the recovery of the thiol status might be an explanation for the anti-carcinogenic effects of garlic compounds.     

Diversity and evolution of a trait mediating ant–plant interactions: insights from extrafloral nectaries in Senna (Leguminosae)

Background and Aims

Plants display a wide range of traits that allow them to use animals for vital tasks. To attract and reward aggressive ants that protect developing leaves and flowers from consumers, many plants bear extrafloral nectaries (EFNs). EFNs are exceptionally diverse in morphology and locations on a plant. In this study the evolution of EFN diversity is explored by focusing on the legume genus Senna, in which EFNs underwent remarkable morphological diversification and occur in over 80 % of the approx. 350 species.

Methods

EFN diversity in location, morphology and plant ontogeny was characterized in wild and cultivated plants, using scanning electron microscopy and microtome sectioning. From these data EFN evolution was reconstructed in a phylogenetic framework comprising 83 Senna species.

Key Results

Two distinct kinds of EFNs exist in two unrelated clades within Senna. ‘Individualized’ EFNs (iEFNs), located on the compound leaves and sometimes at the base of pedicels, display a conspicuous, gland-like nectary structure, are highly diverse in shape and characterize the species-rich EFN clade. Previously overlooked ‘non-individualized’ EFNs (non-iEFNs) embedded within stipules, bracts, and sepals are cryptic and may represent a new synapomorphy for clade II. Leaves bear EFNs consistently throughout plant ontogeny. In one species, however, early seedlings develop iEFNs between the first pair of leaflets, but later leaves produce them at the leaf base. This ontogenetic shift reflects our inferred diversification history of iEFN location: ancestral leaves bore EFNs between the first pair of leaflets, while leaves derived from them bore EFNs either between multiple pairs of leaflets or at the leaf base.

Conclusions

EFNs are more diverse than previously thought. EFN-bearing plant parts provide different opportunities for EFN presentation (i.e. location) and individualization (i.e. morphology), with implications for EFN morphological evolution, EFN–ant protective mutualisms and the evolutionary role of EFNs in plant diversification.     

Novel PTEN germline mutation in a family with mild phenotype: Difficulties in genetic counseling

PTEN gene (phosphatase and tensin homolog deleted on chromosome ten, MIM 601628) is a tumor suppressor gene implicated in PTEN hamartoma tumor syndromes (PHTS) including Cowden syndrome, Bannayan–Riley–Ruvalcaba syndrome and Proteus-like syndrome. PTEN mutations have been more recently reported in children with macrocephaly and autism spectrum disorders or mental retardation, without other symptoms of PHTS. Although tumor risk has not been evaluated in these patients and their relatives, the same surveillance as for Cowden syndrome is usually proposed. We report a family including patients carrying a novel PTEN mutation and presenting with a mild phenotype consisting of macrocephaly, hypotonia during the first year of life and mild learning disabilities, without autistic features. None of these patients exhibited PTHS-related symptoms such as tumors, lipomas, vascular malformations or pigmented macules of the glans penis. This report raises the question of extending the indications of PTEN mutation screening to familial macrocephaly with learning disabilities. Detection of a mutation in this family led to difficult questions about surveillance, genetic counseling and familial information since the mother declined tumor screening and disclosure of genetic risk information to at-risk relatives.     

A methodology for evaluating biocide release rate,surface roughness and leach layer formation in a TBT-free,self-polishing antifouling coating

Abstract

Due to the forthcoming IMO ban on the use of tributyltin (TBT) antifouling paints, a new generation of TBT-free coatings has been developed that typically contain cuprous oxide and an organic co-biocide. Accurate and reproducible test methods are needed to evaluate the performance and environmental impact of these new coatings. This study investigated a methodology for evaluating TBT-free, AF coatings containing cuprous oxide. A commercially available AF coating underwent rotary immersion testing at 0, 0.51 and 2.05 m s^?1. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis were used to assess leach layer formation, percentage cuprous oxide by weight and particle size distribution (PSD). Biocide release rates and surface roughness were also measured. An increase in rotary speed caused a spike in Cu²⁺ release rate after which the release rate stabilised to previous levels. An increase in leach layer thickness was also observed after the rotary speed increase. A model is suggested to account for the observations.     

Amphibians and squamates from the middle Eocene of Namibia,with comments on pre-Miocene anurans from Africa

Three middle Eocene localities (Silica North, Silica South, Black Crow) recently discovered in Namibia have produced terrestrial faunas that rank among the few known from the period of insulation of Africa (Aptian-early Miocene). Collectively, the three localities have yielded anuran amphibians (one pipid frog, the earliest assemblage [three taxa] of ranoid frogs in Africa, one indeterminate family) and squamate reptiles (an amphisbaenian ‘lizard’, a snake that likely represents a colubroid, and two indeterminate ‘lizards’). These Eocene faunas suggest that ranoids, colubroids and African pipids are autochthonous to Africa. However, whereas pipids are vicariants inherited from West Gondwana, ranoids and colubroids (if really autochthonous) originated in Africa from unknown stems. Silica North and Silica South correspond to aquatic environments, permanent fresh water being present in the first locality; the environment of Black Crow was drier.     

Zinc accumulation patterns in four Anthyllis vulneraria subspecies supplemented with mineral nitrogen or grown in the presence of their symbiotic bacteria

Aims

This work examines Zn accumulation in four Anthyllis vulneraria subspecies supplemented with mineral nitrogen or grown in the presence of their symbiotic bacteria.

Methods

Anthyllis vulneraria subspecies were grown hydroponically in the presence of high levels of ZnSO₄. The plants were either grown in symbiosis with one of two non-metallicolous or metallicolous Mesorhizobium inoculants or in the presence of KNO₃.

Results

When exposed to 1,000 μM Zn, shoot and root biomass of three out of our four Anthyllis subspecies cultivated with NO₃ dropped significantly by about 24–28 %; carpatica, the fourth subspecies, was not affected. Subspecies carpatica Zn tolerance was confirmed when in symbiosis with the metallicolous strain. In the presence of 1,000 μM Zn, the different Anthyllis subspecies concentrated more Zn in their roots than in their shoots and only subsp. carpatica accumulated a significant amount of Zn in its shoots. The most remarkable feature was the drastic decrease in Zn concentration in both roots (up to 2.5–3 fold) and shoots (2.6-fold) of subsp. carpatica exposed to 1,000 μM Zn and nodulated whatever the Mesorhizobium strain used, compared to the N-grown plants.

Conclusions

Our results bring new perspectives as regards phytostabilization, with the potential use of a rhizobium-inoculated leguminous subspecies displaying unusual Zn tolerance.     

High gene flow in two thrips‐pollinated South‐East Asian pioneer trees: genetic diversity and population structure of Macaranga hypoleuca and M. beccariana (Euphorbiaceae)

As a result of intensive exploitation, disturbed forests now dominate large areas of lowland tropical rainforest in South‐East Asia. The genus Macaranga comprises some of the most important pioneer tree species of the region, among them M. beccariana and M. hypoleuca, two closely related obligate ant‐plants pollinated by thrips. We used nuclear and plastid DNA markers to address questions of genetic diversity and population structure. Twelve plastid haplotypes were detected among 281 samples, three of which were shared between the two study species. Hybrids between the two species appear to be rare. Overall, genetic diversity in both species was moderate to high, with low levels of population differentiation, consistent with other tropical pioneer trees. Genetic structure was generally more pronounced in plastid than in nuclear data, indicating that gene flow via pollen may be more efficient than via seeds. Thrips apparently also serve as efficient pollinators over long distances, perhaps through a combination of passive dispersal by wind and active search for inflorescences in the target area. Our results indicate that M. beccariana and M. hypoleuca populations from recently disturbed habitats do not yet suffer from reduced genetic diversity or increased inbreeding. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 606–621.