Neuronal membrane dynamics as fine regulator of sphingolipid composition

Sphingolipid metabolism is an intricate network of several interdependent and co-regulated pathways. In addition to the mainstream biosynthetic and catabolic pathways, several processes, even if less important in contributing to the final tissue sphingolipid composition from the quantitative point of view, might become relevant when sphingolipid metabolism is for any reason dysregulated and concur to the onset of neuronal pathologies. The main subcellular sites involved in the mainstream metabolic pathway are represented by the Golgi apparatus (for the biosynthesis) and by the lysosomes (for catabolism). On the other hand, the minor collateral pathways are associated with the plasma membrane and membranes of other organelles, and likely play important roles in the local regulation of membrane dynamics and contribute to maintain a perfect membrane organization functional to the physiology of the cell. In this review, we will consider few aspects of the sphingolipid metabolic pathway depending by the dynamic of the membranes that seems to become relevant in neurodegenerative diseases.     

Effects of the <Emphasis Type="Italic">Papaya meleira virus</Emphasis> on papaya latex structure and composition

Spontaneous latex exudation is the main symptom of papaya sticky (meleira) disease caused by the Papaya meleira virus (PMeV), a double-stranded RNA (dsRNA) virus. This paper describes different effects of PMeV on papaya latex. Latex samples were subjected to different histochemical tests to evaluate their chemical composition. Additionally, the integrity of the latex particles was assessed by transmission and scanning electron microscopy analysis. Biochemical and micro- and macro-element measurements were performed. PMeV dsRNA extraction was performed to evaluate the interaction of the virus with the latex particles. Sticky diseased latex was positive for alkaloid biosynthesis and showed an accumulation of calcium oxalate crystals. PMeV also increased H₂O₂ synthesis within sticky diseased laticifers. The protein, sugar and water levels were altered, probably due to chemical changes. The morphology of the latex particles was further altered; PMeV particles seemed to be bound to the latex particles. The alkaloid and H₂O₂ biosynthesis in the papaya laticifers indicate a papaya defense response against PMeV. However, such efforts failed, as the virus affected the plant latex. The effects described here suggest some advantages of the infection process, including facilitating the movement of the virus within the papaya plant.     

Ending AIDS as a public health threat by 2030: Time to reset targets for 2025

Paul De Lay and co-authors introduce a Collection on the design of targets for ending the AIDS epidemic.     

Structural analysis of subterranean organs in Zingiberaceae

Xylem structural characteristics are rarely used to separate tribes. This study aims to characterize the morphology of subterranean organs and determine both the occurrence and distribution of the vessel elements in ten species, belonging to Alpinieae and Zingibereae tribes. Species were from protected areas in the Brazilian Atlantic Rain Forest or from private cultivation areas. Roots and rhizomes processing followed both light and scanning electron microscopy procedures. According to morphological and anatomical characteristics, Euclidean distances among taxa were calculated, resulting in a dendrogram based on the unweighted pair group method with arithmetic mean (UPGMA) clustering. Despite our results indicating a similarity among all the species studied, they could be segregated by using qualitative and special metabolites characters in both the rhizome and the root. Vessel elements were found to be confined to the roots, presenting several basal characters in most of species, except for Alpinia purpurata and Etlingera species.     

Hyperepilithics—An overlooked life form of vascular plants on tropical vertical rock walls

Vascular epiphytes are a characteristic life form in many tropical regions and often occur growing on bare rocks. South America has the highest diversity. Here, we describe a neglected life form: hyperepilithics adapted and restricted to growing on vertical (inclination above 70°) and bare rock walls without having roots intruding the substrate. Hyperepilithics are in particular present on Brazilian inselbergs and dominated by highly specialized Bromeliaceae, mainly of the genera Stigmatodon, Tillandsia and Alcantarea, whereas Orchidaceae surprisingly has a low representation. An overview of this habitat, the life form hyperepilithics and a comparison with similar paleotropical habitats (mainly inselbergs in Western/Eastern Africa and India) are provided. Attention is drawn to hyperepilithics as a most promising and not yet exploited source for a sustainable urban ‘vertical gardening’, for example in tropical megacities.