Insights from Drosophila on Aß- and tau-induced mitochondrial dysfunction: mechanisms and tools.

Alzheimer's disease (AD) is the most prevalent neurodegenerative dementia in older adults worldwide. Sadly, there are no disease-modifying therapies available for treatment due to the multifactorial complexity of the disease. AD is pathologically characterized by extracellular deposition of amyloid beta (Aß) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau. Increasing evidence suggest that Aß also accumulates intracellularly, which may contribute to the pathological mitochondrial dysfunction observed in AD. According with the mitochondrial cascade hypothesis, mitochondrial dysfunction precedes clinical decline and thus targeting mitochondria may result in new therapeutic strategies. Unfortunately, the precise mechanisms connecting mitochondrial dysfunction with AD are largely unknown. In this review, we will discuss how the fruit fly Drosophila melanogaster is contributing to answer mechanistic questions in the field, from mitochondrial oxidative stress and calcium dysregulation to mitophagy and mitochondrial fusion and fission. In particular, we will highlight specific mitochondrial insults caused by Aß and tau in transgenic flies and will also discuss a variety of genetic tools and sensors available to study mitochondrial biology in this flexible organism. Areas of opportunity and future directions will be also considered.

Orchid Micropropagation Using Conventional Semi-Solid and Temporary Immersion Systems: A Review.

Orchids, with their astonishingly stunning flowers, dominate the international floricultural market. They are considered prized assets for commercial applications in pharmaceutical and floricultural industries as they possess high therapeutic properties and superior ornamental values. The alarming depletion of orchid resources due to excessive unregulated commercial collection and mass habitat destruction makes orchid conservation measures an extreme priority. Conventional propagation methods cannot produce adequate number of orchids, which would meet the requirement of these ornamental plants for commercial and conservational purposes. In vitro orchid propagation using semi-solid media offers an outstanding prospect of rapidly producing quality plants on a large scale. However, the semi-solid (SS) system has shortcomings with low multiplication rates and high production costs. Orchid micropropagation using a temporary immersion system (TIS) overcomes the limitations of the SS system by reducing production costs and making scaleup and full automation possible for mass plant production. The current review highlights different aspects of in vitro orchid propagation using SS and TIS and their benefits and drawbacks on rapid plant generation.

Neuronal role of taxi is imperative for flight in Drosophila melanogaster.

Extensive studies in Drosophila have led to the elucidation of the roles of many molecular players involved in the sensorimotor coordination of flight. However, the identification and characterisation of new players can add novel perspectives to the process. In this paper, we show that the extant mutant, jumper, is a hypermorphic allele of the taxi/delilah gene, which encodes a transcription factor. The defective flight of jumper flies results from the insertion of an I-element in the 5'-UTR of taxi gene, leading to an over-expression of the taxi. We also show that the molecular lesion responsible for the taxi1 allele results from a 25 bp deletion leading to a shift in the reading frame at the C-terminus of the taxi coding sequence. Thus, the last 20 residues are replaced by 32 disparate residues in taxi1. Both taxi1, a hypomorphic allele, and the CRISPR-Cas9 knock-out (taxiKO) null allele, show a defective flight phenotype. Electrophysiological studies show taxi hypermorphs, hypomorphs, and knock out flies show abnormal neuronal firing. We further show that neuronal-specific knock-down or over-expression of taxi cause a defect in the brain's inputs to the flight muscles, leading to reduced flight ability. Through transcriptomic analysis of the taxiKO fly head, we have identified several putative targets of Taxi that may play important roles in flight. In conclusion, from molecularly characterising jumper to establishing Taxi's role during Drosophila flight, our work shows that the forward genetics approach still can lead to the identification of novel molecular players required for neuronal transmission.