Neurodegeneration in a novel invertebrate model system: Failed microtubule-mediated cell adhesion and unraveling of macroglia.

Neurodegenerative diseases are among the main causes of death in the United States, leading to irreversible disintegration of neurons. Despite intense international research efforts, cellular mechanisms that initiate neurodegeneration remain elusive, thus inhibiting the development of effective preventative and early onset medical treatment. To identify underlying cellular mechanisms that initiate neuron degeneration, it is critical to identify histological and cellular hallmarks that can be linked to underlying biochemical processes. Due to the poor tissue preservation of degenerating mammalian brain tissue, our knowledge regarding histopathological hallmarks of early to late degenerative stages is only fragmentary. Here, we introduce a novel model organism to study histological hallmarks of neurodegeneration, the spider Cupiennius salei. We utilized toluidine blue-stained 0.9-µm serial semithin and 50-nm ultrathin sections of young and old spider nervous tissue. Our findings suggest that the initial stages of neurodegeneration in spiders may be triggered by (1) dissociation of neuron- and glia-derived microtubules, and (2) the weakening of microtubule-associated desmosomal junctions that lead to the unraveling of neuron-insulating macroglia, compromising the structural integrity of affected neurons. The involvement of macroglia in the disposal of neuronal debris described here-although different in the proposed transport mechanisms-shows resemblance to the mammalian glymphatic system. We propose that this model system is highly suitable to investigate invertebrate neurodegenerative processes from early onset to scar formation and that this knowledge may be useful for the study of neurodegeneration in mammalian tissue.

Extension of Drosophila lifespan by Rosa damascena associated with an increased sensitivity to heat.

Rosa damascena, or Damask rose, is a rose hybrid commonly harvested for rose oil used in perfumery and for rose water used to flavor food. The petal extract of R. damascena was recently found to decrease Drosophila melanogaster mortality without impairing reproductive fitness or metabolic rate. Here, we report that R. damascena extended both mean and maximum lifespan of the fly. The extract also protected against oxidative stress in flies, predominantly in females. However, it did not alter mitochondrial respiration or content, superoxide production, or the major antioxidant defenses, superoxide dismutase and catalase. The extract increased survival in both sexes when exposed to reduced iron, though surprisingly, it sensitized both sexes to heat stress (survival at 37°C), and appeared to down-regulate the major heat shock protein HSP70 and the small mitochondrial heat shock protein HSP22, at 25°C and after heat shock (4 h at 37°C). We hypothesize that R. damascena extends lifespan by protecting against iron, which concomitantly leads to decreased HSP expression and compromising heat tolerance.