Rhabditis sp. SB347 virgin females, mated females and hermaphrodites attraction to supernatant of males

Data from Figure 3a. To quantify the degree of attraction of worms to conditioned medium produced by different sexes, we used chemotaxis assays. Conditioned medium (henceforth referred to as ‘supernatant’) was generated by placing 5-10 worms in 100 µL of M9 buffer for 12 h at room temperature. The supernatant was stored in 10 µL aliquots at -20 °C until required. The assay was performed either on a microscope slide with a layer of 1.5% agar placed on top of an empty plate, or on a 6 cm NGM plate. 3 µL of supernatant was added on one side of the slide and 3 cm apart from the control drop that just contained M9. 15 young-adults were placed on the midline between the spots. After 30 min, worms were scored on the basis of their location. The values for the chemotaxis index (CI) were calculated with at least ten replicates for each condition. To calculate the CI, the number of worms attracted to the test spot were subtracted by the number of worms in the control spot, and divided by the total number of males assayed. A CI of one indicates that all worms are attracted to the chemical in the test spot, whereas a CI close to zero indicates no attraction. ‘Mated females’ were generated by placing single virgin females in contact with 4-5 males for 6 h.

本数据来自图3a。为量化蠕虫对不同性别个体所产生的条件培养基的趋化程度，本研究采用趋化性实验（chemotaxis assays）开展检测。本实验中的条件培养基（以下简称“上清液”）制备方法为：将5~10条蠕虫置于100微升M9缓冲液中，于室温下静置12小时。制备得到的上清液以10微升为单位分装，于-20℃条件下保存待用。趋化性实验可通过两种方式开展：其一为在空培养皿上铺有1.5%琼脂层的载玻片上进行，其二为在直径6厘米的NGM平板（NGM plate）上进行。在载玻片的一侧滴加3微升上清液，与仅含M9缓冲液的对照液滴相距3厘米。将15条青年成虫置于两个液滴之间的中线位置。30分钟后，根据蠕虫所在位置进行计数统计。各实验条件下均至少设置10次重复，以此计算趋化指数（chemotaxis index, CI）。其计算公式为：被试验液滴吸引的蠕虫数量减去对照液滴中的蠕虫数量，再除以受试雄性蠕虫的总数量。当CI值为1时，代表所有蠕虫均被试验液滴中的化学物质吸引；而当CI值趋近于0时，则代表无趋化吸引现象。“交配后雌性”的制备方式为：将单只处女雌性与4~5只雄性共同培养6小时。