沙蟋飞行肌中保幼激素滴度的昼夜节律

Diurnal rhythm of JH titers in the flight muscle tissues of the sand field cricket, Gryllus firmus (Orthoptera: Gryllidae)

沙蟋Gryllusfirmus是一种翅多型性的昆虫,是研究种内迁飞和生殖调控的模式生物。本研究应用高效液相色谱仪(HPLC)、气相色谱-质谱联用仪(GC-MS)对沙蟋长翅(有飞行能力)和短翅(无飞行能力)雌虫飞行肌内保幼激素(juvenile hormone,JH)和脂肪酸进行了定性定量分析。结果表明:在温度28℃,光周期16L∶8D条件下,第5和第7日龄的沙蟋长翅雌虫飞行肌中JH的滴度具有明显的昼夜节律,在飞行前(即关灯前)4h,JH的滴度分别由386.52±68.40ng/g和630.36±37.26ng/g增加至1327.53±277.98ng/g和1685.77±143.95ng/g,与短翅型SW相比分别增加了约3.4倍与2.7倍(P<0.05)。而相同日龄的短翅雌虫及第1日龄的两型雌虫均无明显的节律变化。进一步在第5和7日龄的长翅雌虫中发现了一个16C的脂肪酸——14-甲基十五烷酸,也具有节律变化且与JH节律出现的时间相吻合,而在无飞行能力的沙蟋中没有发现这种现象。实验还证明JH滴度的增加和节律不是由飞行肌的重量或者飞行肌重量比的变化所致。这些发现有助于探讨和了解保幼激素对飞行调控的内在机理。

The sand field cricket, Gryllus firmus, is a wing-polymorphic insect, a model insect for studying fitness of reproduction and dispersal within species. In this study, we qualitatively and quantitatively analyzed titers of juvenile hormone （JH） and fatty acids in flight muscles between the long wing and the short wing （SW, flightless） females by high performance liquid chromatography （HPLC） and gas chromatography-mass spectrometry （GC-MS）. The results showed that JH titers at 4 h before flight on day 5 and 7 of LW（f） morph exhibited a daily rhythm with about 3.4- and 2.7-fold increases, respectively （P0.05） compared with those in SW morph, that is, from 386.52±68.40 ng/g to 1 327.53±277.98 ng/g on day 5 and from 630.36±37.26 ng/g to 1 685.77±143.95 ng/g on day 7, respectively. By contrast, there was no significant daily variation of JH titers on day 5 and 7 of SW morph, and day 1 of both morphs. Further, the 14-methyl-pentadecanoic acid, a C16 fatty acid, was also found to exhibit a daily rhythm on the day 5 and 7 of the LW（f） morph with temporal consistency with the JH peak, which did not occur in the flightless morph. The experiments also prove that the daily rhythm of JH titers is not due to the variation in flight muscle mass or the ratio of flight muscle mass. These results help us to understand the relationship between JH titer and flight behavior.