Alzheimer's disease (AD) is the most widespread neurodegenerative disorder worldwide. Its pathogenesis involves two hallmarks: aggregation of amyloid beta (Aβ) and occurrence of neurofibrillary tangles (NFTs). The mechanism behind the disease is still unknown. This has prompted the use of animal models to mirror the disease. The fruit fly, Drosophila melanogaster has garnered considerable attention as an organism to recapitulate human disorders. With the ability to monopolise a multitude of traditional and novel genetic tools, Drosophila is ideal for studying not only cellular aspects but also physiological and behavioural traits of human neurodegenerative diseases. Here, we discuss the use of the Drosophila model in understanding AD pathology and the insights gained in discovering drug therapies for AD.

Aims: Rhodotorula sp. (USM-PSY62) is a psychrophilic yeast isolated from Antarctic sea ice that grows optimally at 15°C. The inevitable global warming poses many challenges to the microbial community in Antarctica. Therefore, this studywas conceptualized to observe how USM-PSY62 adapted to fluctuations in temperature. Methodology and results : Rhodotorula sp. (USM-PSY62) was grown in YPD broth until the mid-log phase. Then, the culture was transferred to four different temperatures, specifically at 0 °C, 5 °C, 15 °C and 21 °C for 24 h. Then, the RNA was extracted, sequenced and analysed. During cold adaptation, an elevated transcription of the CorA magnesium transporter gene in USM-PSY62 indicated a higher requirement for magnesium ions to gain additional enzyme cofactors or maintain cytoplasmic fluidity. The HepA homologue coding for DNA/RNA helicase was also over-expressed with log fold change 2.89 in cold conditions possibly to reorganize secondary structures of DNA and RNA. An up-regulation of the catalase gene was also observed, reflecting an increment in the concentration of reactive oxygen species and fluctuations in the associated antioxidant system. The YOP1 gene, which encodes a membrane protein associated with protein transport and membrane traffic, was the most down-regulated, with log2 fold change values of -6.93 lower under cold shock conditions. The genes responsible for the structural maintenance of chromosome (SMC) have a -8.80 in expression log2 fold change, indicating the gene was down-regulated when the temperature was shifted to 0 °C. Upon cold shock, the gene for heat shock factor protein 1 (HSF1) was also down-regulated with a log2 fold change value of - 5.86. Hsf1 is a transcriptional regulator which regulates the heat shock responses. Conclusion, significance and impact of study: In conclusion, the transcriptomic responses demonstrated by Rhodotorula sp. USM-PSY62 characterized critical physiological and biochemical compensatory mechanisms especially cellular processes and signalling, information storage and processing, and metabolism to survive at low and high temperatures. This study provides valuable data for industry, especially in the usage of molecular chaperones.