果蠅與老化相關的表徵

The Aging Related Phenotype in Drosophila

陳怡妤(I-Yu Chen)

指導教授 ： 高智飛

國立交通大學/生物科技學院/生物科技學系暨研究所/碩士(2020年)

摘要

老化的速率受到環境因子與基因的影響，可能直接影響壽命，或是再間接透過生理的改變影響壽命的長短。時常被忽略的環境因子——個體密度，是我們這次研究的重點。從實驗過程中意外得知獨居可使果蠅的壽命延長，為了更加了解獨居對果蠅壽命延長的機制，我們先給予果蠅不同長短的獨居時間，發現並不需要一生都在獨居的空間下才能延長壽命，只要獨居的時間夠長便可有顯著的效果。接著，便是了解果蠅延長壽命的最佳獨居時間點，在果蠅中年的以後才開始獨居的延壽的效果是最好的。為了瞭解獨居果蠅能夠延長壽命是在生理上受到什麼樣的改變，我們對於獨居與群居的果蠅做Next Generation Sequencing (NGS)，並對基因作許多不同的分析，結果也確實在獨居與群居果蠅當中找尋到許多已知與老化及延壽相關的基因，無論從壽命表徵的結果或是基因分析的結果都更加確定獨居果蠅的延長壽命的事實。已知的研究也指出不具嗅覺或是其他感官接受器的果蠅的抗壓性增強，並且延長了壽命。不接收其他個體所傳遞的訊息，這是否就是獨居果蠅能夠延長壽命的原因呢？為了瞭解感官對於果蠅壽命的影響，我們給予果蠅一對一的社交對象，並剔除其嗅覺或味覺，觀察失去這些感官的果蠅是否會有類似獨居的效果，結果與我們所預想的不同，但也發現雄雌的感官對於壽命有不太一樣的效果。為了更清楚果蠅與不同對象社交的狀態，給予果蠅不同性別的一對一社交環境。如同以往的研究，與不同性別的互動會造成果蠅的壽命下降。
論文的第二部分實驗是觀察老化中行為的部分，前面我們提及老化會牽涉到的因素，也會反映在行為上面。研究指出不同年齡會依據不同的身體狀況影響口味的變化，我們的實驗結果也觀察到果蠅會因為年齡及性別而有攝食行為改變，結合已知果蠅可以利用偵測食物所含的熱量，我們進行更多的測試。根據研究，果蠅應該是比較偏好熱量高的食物，我們利用不同甜度與熱量的糖類比較年輕與中年果蠅在攝食行為上的改變。確實在許多糖類的結果中，中年果蠅這樣的能力有下降的趨勢，在這次實驗我們還加入「不進食」這個分類，我們觀察到許多中年果蠅在經過12小時的飢餓後，在實驗中給予食物竟然還是選擇不進食，比起選擇錯誤的果蠅，不進食的果蠅可能是能力更加下降，也明顯地觀察到中年果蠅不進食的比例高出許多。最後，為了得知果蠅選擇食物所牽涉的感官，嗅覺是否也是果蠅選擇食物的依據？我們用Or83b(-/-)的果蠅來做甜味與苦味的選擇，以及對熱量含量的分析，結果雌性果蠅在對熱量的偏好比較依賴嗅覺。

關鍵字

果蠅 ； 老化

並列摘要

Aging rate is affected by environment factors and factors. Environment factors and factors might directly control the lifespan of animals, or through physiological changes. Population density, an environment factor that is much less studied is a major emphasis in this project. Surprisingly, from our results, we discovered that the flies showed prolonged lifespan in the solitary environment, which we called it “solitary effect”. To understand the mechanism of solitary effects, we gave the flies living in solitary condition with a different time period. Then we found out that the flies can prolong lifespan even if they are not solitary the whole lifespan, enough solitary time was sufficient to prolong lifespan. Further, we revealed the best age of social isolation, which leads the longest life expectancy. The best timing of solitary for prolonging lifespan is during midlife of Drosophila. To understand what physiological changes occurred during social isolation, we used the Next Generation Sequencing (NGS) to profile the differential gene expression patterns in single-housed and group-housing flies. Expression results were further analyzed by GO classifications and KEGG pathway analysis to identify genes related to solitary effects. These results made us more certain that solitary effects could prolong the lifespan of Drosophila. Earlier studies have indicated that flies without olfactory sensor other perceptions show higher pressure resistance, tolerance, as well as longer lifespan. To understand how important perception is in social interaction of Drosophila, we gave the wide-type, gustatory mutant, or olfactory mutant flies a one-to-one interaction, and observed whether the flies without these conceptions will show similar effects to solitary. The results were not consistent with our expectation, however we realized the importance of perception could be distinguished from the lifespan of male and female flies. To clearly realize the mode flies’ interaction with different individuals, we gave the flies a one-to-one interaction condition. Similar to previous studies, the flies which interacted with different genders had shorter lifespan.
In part 2, we focused on the feeding behaviors of aging flies. Aging will change many things in animals, including epigenetics and gene expressions. Behavior change is also a part of aging-related changes. Researchers speculate that taste will be altered by distinct physiological conditions, our experimental results suggested flies’ feeding behavior changes were associated with aging and genders. Moreover, earlier studies have shown flies have nutrition-detecting ability. In this project, we like to know if the ability is changed during aging. We gave the young and aged flies several sugars containing selected amounts of calories and different levels of sweetness to compare the feeding behavior change with aging. Our results showed the nutrition-detecting ability in aged flies was progressively declined. Finally, to know whether olfactory inputs are essential for food choice, we used Or83b(-/-) flies to performed the feeding assays. Our results indicated that female flies require more olfactory information in calories-detecting behaviors.

並列關鍵字

Drosophila ； Aging

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