秀麗隱桿線蟲作為理想的多細胞模式生物，其特點包含易於觀察的透明身軀、體型小不占空間、生長周期短、實驗室環境易繁殖及基因體定序完全。在雌雄同體的線蟲體內含302個神經元，使其能在應對外在環境變化時做出適當的反應。針對外在環境的變化，線蟲會有不同的反應，例如化趨性、電趨性及磁趨性等等。藉由了解行為模式改變，能辨別對於該環境的喜好與厭惡情形。近年來，線蟲被廣泛應用於不同領域，如神經退化疾病、癌症、環境毒物學、藥物應用、睡眠研究等等。
線蟲具有高度發展的化學感測系統並利用趨向性反應達到如尋找食物、避開有害的環境、正常生長及交配的目的。現今許多的動物能經由嗅覺的方式得知人體存在疾病的徵兆，如不同類型的癌症、糖尿病、消化道疾病等等。本研究以癌症為主，在癌細胞分裂生長過程中會釋出代謝物質於體液或是組織器官內，代謝物質作為生物標記物的一種，提供人們發現癌症存在的蛛絲馬跡，以提升癌症早期篩檢的重要性。
此研究使用解剖顯微鏡觀察N2野生表型線蟲在滴有癌細胞代謝上清液的生長培養基其化學趨向性(Chemotactic Index)的表現。以四種同為低糖培養基(LG-DMEM)中生長的癌細胞，分別為膀胱癌細胞株(T24)、肝癌細胞株(Huh-7)、人類骨肉瘤癌細胞株(U2OS)及子宮頸癌細胞(SiHa)。藉由了解癌細胞的上清液對線蟲的影響，得出不同種癌細胞經在訓練前、後與不同種癌細胞之間的趨化指數差異。透過古典制約(Classical Conditioning)的概念，應用於線蟲的長短期訓練，利用短期的訓練為期一小時(young adult stage)及長期的訓練為期六小時(young adult stage)，加強甚至逆轉線蟲對於癌細胞上清液的選擇。在結果顯示出，並非所有的癌細胞上清液對於線蟲都是呈現正向的吸引力，可見不
 
是所有癌細胞上清液都能藉由條件訓練來提升辨識能力。從線蟲尚未進行訓練的結果中得出四種癌細胞株上清液給予線蟲的吸引力排序且根據排序能解釋大部份訓練後組別的結果。因此找出合適的癌細胞種類來進行訓練及比較是至關重要的。此外，在正常肝細胞與肝癌細胞的組別中，結果顯示肝癌細胞上清液對於線蟲在訓練的前後都是有顯著吸引力的。
此研究的新穎之處在於能藉由線蟲對於癌細胞代謝出的氣味有化學趨向性的反應，並藉由條件訓練達到行為上的強化。未來期望以生物感測器的優勢應用於癌症預篩檢的判斷。

The nematodes Caenorhabditis (C.) elegans is an ideal multicellular model organism that features transparent body, small body size (~1 mm), short life cycles, ease of laboratory cultivation, and fully sequenced genomes. With a primitive neuronal network containing 302 neurons in hermaphrodites, the worms are capable of performing various responses to the changing in external environments. Under the external stimuli, they will have some action like chemotaxis, electrotaxis, magnetotaxis, and so on. By finding out the changing behavioral responses of the worms that people can know whether the worms are appealed to or repelled the environments. In recent years, C. elegans are widely used in numerous research fields, such as neurodegenerative disorder, cancer, environmental toxicology, drug application, sleep study, and so on.
C. elegans has a highly developed chemosensation system, called chemotaxis, to seek food, avoid noxious environments, develop appropriately and mate. Nowadays, many animals are employed for the scent detection of disease symptoms, such as types of cancers, diabetes, gastrointestinal tract diseases, and so on. The research focuses on cancer topic. Metabolites as a sort of biomarkers that will be secreted out by the cancer cells into the body fluid, tissues, or organs while the cancer cells start to grow and cleavage. The phenomenon provides people a clue to figure out the existence of cancers and elevates the importance of prescreening.
In this study, we use a wild-type strain (N2) and observe its chemotactic performance by stereo microscope on the nematode growth media (NGM) with drops of cancer supernatant. Four different human cancer cell lines cultured in low glucose DMEM (LG-DMEM) were selected for the preliminary evaluation, including T24 (bladder cancer), Huh-7 (liver cancer), U2OS (Osteosarcoma cancer), and SiHa (cervical cancer). Classical conditioning as the concept is applied to short-term and long-term training. The choices to the cancer cell supernatant of the worms can be either enhanced or reversed with the short-term (young adult stage) for 1 h and long-term (young adult stage) for 6 h training. The results show that not all cancer supernatants will attract the worms positively. Through the naïve assay, the attraction ability of cancer media to C. elegans has concluded and proved that the results of short-term training are based on it in most of the groups. Therefore, it is critical to find out suitable cancer cell line medium to condition the worms and well-trained methods make C. elegans possess the ability to distinguish cancers. Besides, the result indicated that the Huh7 medium had significant attraction to the untrained/trained worms in the normal-cancer cell medium group.
The novelty of the research is that C. elegans with the gifted capability are employed for sensing the cancer cell metabolites smell and respond to the smell. We can achieve behavioral enhancement of the worms to distinguish the cancer cell line media by classical conditioning. Biosensors take advantage of C. elegans to do cancer prescreening.

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