Henrichs Darren W, Sosik Heidi M, Olson Robert J, Campbell Lisa
Department of Biology, Texas A&M University, College Station, Texas 77843, USADepartment of Biology, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USADepartment of Oceanography and Department of Biology, Texas A&M University, College Station, Texas 77843, USA.
J Phycol. 2011 Apr;47(2):366-74. doi: 10.1111/j.1529-8817.2011.00960.x. Epub 2011 Mar 14.
Brachidinium capitatum F. J. R. Taylor, typically considered a rare oceanic dinoflagellate, and one which has not been cultured, was observed at elevated abundances (up to 65 cells · mL(-1) ) at a coastal station in the western Gulf of Mexico in the fall of 2007. Continuous data from the Imaging FlowCytobot (IFCB) provided cell images that documented the bloom during 3 weeks in early November. Guided by IFCB observations, field collection permitted phylogenetic analysis and evaluation of the relationship between Brachidinium and Karenia. Sequences from SSU, LSU, internal transcribed spacer (ITS), and cox1 regions for B. capitatum were compared with five other species of Karenia; all B. capitatum sequences were unique but supported its placement within the Kareniaceae. From a total of 71,487 images, data on the timing and frequency of dividing cells was also obtained for B. capitatum, allowing the rate of division for B. capitatum to be estimated. The maximum daily growth rate estimate was 0.22 d(-1) . Images showed a range in morphological variability, with the position of the four major processes highly variable. The combination of morphological features similar to the genus Karenia and a phylogenetic analysis placing B. capitatum in the Karenia clade leads us to propose moving the genus Brachidinium into the Kareniaceae. However, the lack of agreement among individual gene phylogenies suggests that the inclusion of different genes and more members of the genus Karenia are necessary before a final determination regarding the validity of the genus Brachidinium can be made.
头状短凯伦藻（Brachidinium capitatum），F. J. R. 泰勒，通常被认为是一种罕见的海洋甲藻，且尚未被成功培养，于2007年秋季在墨西哥湾西部的一个沿海站点被观测到丰度升高（高达65个细胞·毫升⁻¹）。成像流式细胞仪（IFCB）的连续数据提供了细胞图像，记录了11月初3周内的藻华情况。在IFCB观测的指导下，实地采集样本用于系统发育分析以及对头状短凯伦藻与凯伦藻属（Karenia）之间关系的评估。对头状短凯伦藻的小亚基核糖体RNA（SSU）、大亚基核糖体RNA（LSU）、内转录间隔区（ITS）和细胞色素氧化酶亚基1（cox1）区域的序列与凯伦藻属的其他五个物种进行了比较；所有头状短凯伦藻的序列都是独特的，但支持其在凯伦藻科（Kareniaceae）中的分类地位。从总共71487张图像中，还获得了头状短凯伦藻细胞分裂时间和频率的数据，从而能够估计头状短凯伦藻的分裂速率。最大日生长速率估计为0.22 d⁻¹。图像显示出形态变异性的范围，四个主要突起的位置高度可变。形态特征与凯伦藻属相似，以及系统发育分析将头状短凯伦藻置于凯伦藻进化枝中，这使我们建议将短凯伦藻属移入凯伦藻科。然而，单个基因系统发育之间缺乏一致性表明，在对头状短凯伦藻属的有效性做出最终决定之前，纳入不同基因和更多凯伦藻属成员是必要的。
