Comparison of anatomical features in the three Syzygium species

This study was conducted to provide foundational anatomical information of three infrequently used wood species growing in tropical areas. Three species of the genus Syzygium, namely the clove tree, kupa, and spicate eugenia, were selected. The representative anatomical features of these species were classified using the International Association of Wood Anatomists (IAWA) anatomical feature list. The representative anatomical features of the clove tree included the distribution of small vessels with tangential diameters of approximately 60 µm in cross-surface, a dense spacing of vessels, the axial parenchyma in narrow bands or lines up to three cells wide, and the body ray cells procumbent with over four rows of upright and/or square marginal cells. The kupa showed axial parenchyma confluent and the body ray cells were procumbent with over four rows of upright and/or square marginal cells. In the spicate eugenia, the axial parenchyma was diffused in aggregate with exclusively uniseriate rays and the body ray cells were procumbent with one row of upright and/or square marginal cells. These three species were easily identified by optical microscopy via the anatomical features of the woods.

Wood and bark anatomy of South African Picrodendraceae with systematic and ecological implications

Wood and bark structure of Androstachys johnsonii and Hyaenanche globosa (Picrodendraceae) is described. Two species share simple perforation plates, minute to small intervessel pits, and nonseptate fibres; these traits also reported in other Picrodendraceae. Androstachys is distinctive in having scanty paratracheal axial parenchyma and uniseriate rays with vessel-ray pits restricted to marginal cells. Bordered pits on fibre walls is an ancestral condition for the African Picrodendraceae. High vessel frequency and vessel grouping in Androstachys can be adaptive for semi-arid climate with wet summer. Both genera share the subepidermal phellogen initiation and the presence of thick-walled fibers and sclereids in secondary phloem. In Hyaenanche, the bark is dilated by stretching and divisions of parenchyma cells with formation of pseudocortex. Androstachys shows no ray dilatation, but sclerification of its parenchyma can make substantial contribution in bark expansion. Abundant trichomes on epidermis of young shoots of Androstachys are presumably involved in the water uptake from mists.

Effect of SOD2 methylation on mitochondrial DNA4834-bp deletion mutation in marginal cells under oxidative stress

Presbycusis, or age-related hearing loss, is a prevalent disease that severely affects the physical and mental health of the elderly. Oxidative stress and mitochondrial (mt)DNA deletion mutation are considered as major factors in the pathophysiology of age-related hearing loss. The 4977-bp deletion in human mtDNA (common deletion, corresponding to the 4834-bp mtDNA deletion in rats) is suggested to be closely associated with the pathogenesis of age-related hearing loss. Superoxide dismutase 2 (SOD2), an isoform of SOD that is exclusively expressed in the intracellular mitochondrial matrix, plays a crucial role in oxidative resistance against mitochondrial superoxide. Previous research has shown that methylation of the promoter region of the SOD2 gene decreased the expression of SOD2 in marginal cells (MCs) extracted from the inner ear of rats subjected to D-galactose-induced mtDNA4834 deletion. However, the relationship between SOD2 methylation and mtDNA4834 deletion under oxidative stress remains to be elucidated. Herein, an oxidative damage model was established in the extracted MCs using hydrogen peroxide (H2O2), which increased the methylation level of SOD2 and the copy number of mtDNA4834 mutation in MCs. Decreasing the methylation level of SOD2 using 5-azacytidine, a DNA methylation inhibitor, reduced oxidative stress and the copy number of mtDNA4834 mutation and inhibited H2O2-induced apoptosis. The present work demonstrates that decreasing the methylation of SOD2 suppresses the mtDNA4834 deletion in MCs under oxidative stress and provides potential insights to the intervention therapy of aging-related hearing loss.

Updated taxonomy of Lactifluus section Luteoli: L. russulisporus from Australia and L. caliendrifer from Thailand

Lactifluusrussulisporus Dierickx & De Crop and Lactifluuscaliendrifer Froyen & De Crop are described from eucalypt forests in Queensland, Australia and different forest types in Thailand, respectively. Both species have recently been published on Index Fungorum and fit morphologically and molecularly in L.sect.Luteoli, a section within L.subg.Gymnocarpi that encompasses species with alboochraceous basidiomes, white latex that stains brown and typical capitate elements in the pileipellis and/or marginal cells.

The Marginal Cells of the Caenorhabditis elegans Pharynx Scavenge Cholesterol and Other Hydrophobic Small Molecules

The nematode worm Caenorhabditis elegans is a bacterivore filter feeder. Through the contraction of the worm’s pharynx, a bacterial suspension is sucked into the pharynx’s lumen. Excess liquid is then shunted out of the buccal cavity through ancillary channels that are made from specialized pharyngeal cells called marginal cells. Through the characterization of our library of worm-bioactive small molecules (a.k.a. wactives), we found that more than one third of wactives visibly accumulate inside of the marginal cells as crystals or globular spheres. Wactives that visibly accumulate are typically more hydrophobic than those that do not. To understand why wactives accumulate specifically in marginal cells, we performed a forward genetic screen for mutants that resist the lethality associated with one crystallizing wactive. We identified a presumptive sphingomyelin-synthesis pathway that is necessary for crystal and sphere accumulation. Sphingomyelin is a phospholipid that is enriched in the outer leaflet of the plasma membranes of most metazoans. We find that the predicted terminal enzyme of this pathway, sphingomyelin synthase 5 (SMS-5), is expressed in the pharynx, contributes to sphingomyelin abundance, and that its expression in marginal cells is sufficient for wactive accumulation. We also find that the expression of SMS-5 in the marginal cells is necessary for the proper absorption of exogenous cholesterol, without which C. elegans cannot develop. We conclude that the sphingomyelin-rich plasma membrane of the marginal cells acts as a sink to scavenge important hydrophobic nutrients from the filtered liquid that might otherwise be shunted back into the environment.One sentence summaryThe anterior pharynx of C. elegans is a Sink for Hydrophobic Small Molecules