The swimming of male gametes of brown algae is controlled by two heterokont flagella, regardless of reproductive system, but the patterns of flagellar movement can vary. We investigated sperm chemotaxis and phototaxis in four oogamous Australasian fucalean species. Sperm morphology was similar to that of male gametes of isogamous and anisogamous species but their chemotactic behaviours were much closer to those of other oogamous species than those of isogamous and anisogamous species. Moreover, unlike anisogamous species, sperm chemotaxis of the oogamous species, Hormosira banksii, was not inhibited by a phosphodiesterase inhibitor, theophylline, suggesting variability in regulatory mechanisms of sperm chemotaxis amongst brown algae. In our previous work, lower extracellular Ca²⁺, supernatant of female gametes and theophylline induced the reversal of phototactic signs in anisogamous male gametes. In contrast, lower extracellular Ca²⁺ and theophylline did not significantly affect phototaxis in sperm of the oogamous H. banksii. Moreover, high extracellular Ca²⁺ and supernatant of eggs disrupted the negative phototaxis but did not reverse their phototactic sign. These results suggest that the regulation of phototaxis also varies amongst brown algal gametes. Further investigation of brown algal species is warranted to assess the generality of these patterns of chemotaxis and phototaxis among anisogamous and oogamous gametes.

棕色藻雄性配子的游泳受两个异鞭毛鞭毛的控制，而与生殖系统无关，但鞭毛运动的方式可以变化。我们调查了四个卵形的澳大利亚富卡人物种的精子趋化性和趋光性。精子形态类似于同卵和异卵种类的雄配子，但是它们的趋化行为比同卵和异卵种类的趋化行为更接近于其他卵生种类。此外，与异性配种不同，卵类物种Hormosira bankii的精子趋化性不受磷酸二酯酶抑制剂茶碱的抑制，这表明褐藻中精子趋化性调节机制的差异。在我们之前的工作中，较低的细胞外Ca ²⁺雌配子和茶碱的上清液可诱导异配雄配子的光战术征象逆转。相比之下，降低外Ca ²⁺和茶碱没有显著影响趋光性的oogamous的精子H. banksii。此外，高的细胞外Ca ²⁺和卵的上清液破坏了负趋光性，但没有逆转其趋光性迹象。这些结果表明，趋光性的调节在褐藻配子之间也不同。有必要对棕色藻类物种进行进一步调查，以评估异配子和配子配子之间这些趋化性和趋光性模式的普遍性。