Newsletter No. 384

No. 384, 4.10.2011 5 校 園 消 息 CAMPUS NEWS 蟹不可以貌相 • From Hermit to King W hen you are enjoying a delicious meal of Alaskan or Japanese king crabs, you probably are not aware of the fact that what you are eating, scientifically speaking, are not really ‘crabs’, in the same way as are the Chinese mitten crab, the common mud crab and other swimming crabs.  Prof. Chu Ka-hou, director of the School of Life Sciences and Simon F.S. Li Marine Science Laboratory, worked in collaboration with his PhD student Dr. Tsang Ling- ming, Prof. Chan Tin-yam from Taiwan Ocean University, and Dr. Shane Ahyong from the Australian Museum in Sydney. They confirmed that king crabs are actually close relatives of hermit crabs, and belong to a group known as the anomurans, a group of crustaceans including hermit crabs and other forms that have a crab-like (such as the king crabs and porcelain crabs) or lobster-like (called squat lobsters) appearance. Compared to true crabs, the last pair of legs of anomurans is very small and their tails are often folded under the body. Their study based on new evidence from DNA analysis shows that the tiny hermit crab, which generally weighs less than a quarter of a pound, is the ancestor of not only the king crab, a creature that may weigh more than 18 pounds with a limb span reaching six feet, but also that of almost all other anomurans.   Professor Chu said, ‘We got this interesting result by DNA sequence analysis of nuclear protein-coding gene markers we newly developed for the crustaceans. The crab-like and squat lobster forms evolved more than once from their hermit crab ancestors.  This fact shows that the body plan of the hermit crab is highly flexible and parallel evolution to crab-like forms is common in this group.’  Parallel evolution refers to the independent evolution of similar characteristics, in this case the different crab- like forms from hermit crabs.  Moreover, the true crabs and crab-like anomurans are also examples of parallel evolution. This example also shows that similarity in appearances between animals can be a deceptive indicator of relatedness. This study has just been published in Systematic Biology , the top journal in the field of evolutionary biology, in August 2011.  朱嘉濠教授（左）及曾令銘博士展示皇帝蟹與寄居蟹在體積上的巨大差別 Prof. Chu Ka-hou (left) and Dr. Tsang Ling-ming show the dramatic difference in size between the king crab and the hermit crab 大 家在大快朵頤，品嚐美味的阿拉 斯加蟹或日本皇帝蟹時，大概不曾 察覺自己所吃的其實不是真正的「蟹」。生 命科學學院及李福善海洋科學研究中心 院長朱嘉濠教授，聯同其博士學生曾令 銘博士、台灣海洋大學陳天任教授，以及 悉尼澳洲博物館的Dr. Shane Ahyong， 根據DNA排序分析證實，皇帝蟹其實是 寄居蟹的近親，屬異尾類動物，而不同於 大閘蟹、青蟹和花蟹等螃蟹。相較於真正 的螃蟹，異尾類動物的最後一對腳非常 細小，而尾巴通常捲曲於身體之下。寄居 蟹和一些外形與蟹和龍蝦相似的甲殼動 物，如皇帝蟹、瓷蟹及鎧甲蝦，均屬於異 尾類動物。 朱教授等人的研究顯示，體重一般少於 四分之一磅的寄居蟹，不單是重量可逾 十八磅、兩腳張開距離可長達六呎的皇帝蟹的祖先，更幾 乎是所有異尾類的祖先。朱教授稱：「這個有趣的結果，是 透過我們最近為甲殼類動物所特別研發的新細胞核蛋白 質編碼基因標記的DNA排序分析所發現。蟹狀及鎧甲蝦 形態的動物是由寄居蟹的祖先多次進化而成，顯示寄居蟹 的身體構造非常靈活多變，牠們平行演化至不同的蟹狀形 態是很普遍的。」 平行演化是指相近特徵的個別演化，例如寄居蟹可進化成 不同的蟹狀形態，而真正的蟹和蟹狀的異尾類亦是平行演 化的例子。因此，動物外表相似並不一定代表它們有密切 關係。這項研究剛於8月在進化生物學權威期刊─《系統 生物學》上發表。 何永成教授（ 中 ）於加拿大艾伯塔大學取得學士學位後，赴美國紐約州立大學水牛城分校 攻讀碩士和博士。畢業後於原校及猶他大學接受博士後訓練，之後任職猶他大學人類毒理 學中心，直至1992年。何教授其後回港，1994年加入中大擔任講師。他的實驗室主要研究 肝腫瘤形成，以中草藥治療肝癌，以及以蛋白質作為肝臟毒性的生物標記。 Prof. Ho Wing-shing ( centre ) received his BSc from the University of Alberta, and completed his MA and PhD studies at The State University of New York at Buffalo. After post-doctoral training at SUNYAB and the University of Utah, he joined the Center for Human Toxicology at the University of Utah, where he remained until 1992. He moved back to HK and became a lecturer at CUHK in 1994. His research laboratory focuses on liver carcinogenesis, its treatment with herbal medicines and proteins as biomarkers for liver toxicity. 藝 文 風 景 A TOUCH OF CLASS 《臨時政府》 水墨設色紙本，96 x 127 cm，2011 方蘇，1974年畢業於中大經濟系，崇基學院校友，少時師從嶺南派大師趙少昂。原從事新聞工 作，後專注繪畫藝術。其水墨創作多以社會民生為題材，畫風獨特。 The Provisional Government Ink and colour on paper, 96 x 127 cm, 2011 An alumnus of Chung Chi College, Fong So studied economics at CUHK and graduated in 1974. He learned painting from Chao Shao-an, the master of the Lingnan School of painting. Fong is a journalist-turned painter, who uses social issues and lives of ordinary people as the theme of his paintings. In Plain View