Chloroplast migration in Halimeda species from the Great Barrier Reef

A series of experiments examining the migration of chloroplasts in a number of Halimeda species (Halimeda distorta, Halimeda hederacea, Halimeda opuntia, Halimeda spp., Halimeda tuna)Time-lapse photography was used to record the change in colour from dark-green to almost white condition. The surface area of growing segments on the time-lapse films was measured using a computer interface with the video frames.Halimeda spp. (collected from Cockle Bay, Magnetic Island) was used in laboratory experiments (conducted at AIMS) and was also studied in conjunction with Halimeda hederacea and Halimeda opuntia at Davies Reef.Spectrophotometry of acetone extracts was used to determine the chlorophyll a and b contents of freeze-dried Halimeda. A LICOR LI 3000 area meter with a LI 3050 conveyor system measured surface areas of segments and also the segments from branches used to measure photosynthesis and respiration rates which were placed in an adjacent tank. Pigment content and oxygen metabolism are expressed per unit area of segment.The effects of temperature (5 degree increments between 15 and 30°C) were examined in laboratory experiments on Halimeda distorta and Halimeda tuna.The effect of circadian rhythms was examined in a further laboratory experiment on Halimeda distorta.
To better understand paling patterns in Halimeda species.

本系列实验旨在探究多种仙掌藻属（Halimeda）物种——包括扭曲仙掌藻（Halimeda distorta）、常春藤仙掌藻（Halimeda hederacea）、团扇仙掌藻（Halimeda opuntia）、未定种仙掌藻（Halimeda spp.）以及金枪鱼仙掌藻（Halimeda tuna）——中的叶绿体迁移现象。研究采用延时摄影技术，记录样本从深绿色转变为近乎白色的色泽变化过程。通过搭载视频帧分析功能的计算机界面，对延时摄影胶片中生长段的表面积进行定量测量。本实验使用采集自磁岛（Magnetic Island）贝壳湾（Cockle Bay）的未定种仙掌藻（Halimeda spp.），于澳大利亚海洋科学研究所（AIMS）开展室内实验；同时结合常春藤仙掌藻与团扇仙掌藻，在戴维斯礁（Davies Reef）开展原位观测研究。采用丙酮提取物分光光度法，测定冻干仙掌藻样本的叶绿素a与叶绿素b含量。使用LICOR LI 3000面积仪搭配LI 3050输送系统，测量藻段表面积；同时对置于相邻培养缸中、用于测定光合与呼吸速率的分枝藻段同步开展表面积测量。色素含量与氧代谢速率均以单位藻段面积为基准进行归一化表达。针对扭曲仙掌藻与金枪鱼仙掌藻的室内实验，探究了温度梯度（15~30℃间以5℃为增量）对其的影响。另有针对扭曲仙掌藻的室内实验，探究了昼夜节律对其的影响。本研究旨在更深入地阐明仙掌藻属物种的色泽褪白模式。