# 灰藻[编辑]

| 灰藻 |
| --- |
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| *Glaucocystis* sp.
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| 科学分类  |
| 域： | 真核域 Eukaryota |
| 演化支： | 多貌生物 Diaphoretickes |
| 演化支： | CAM  |
| 演化支： | 原始质体生物 Archaeplastida |
| 门： | **灰藻门 Glaucophyta** Skuja 1948 |
| 纲
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| * 灰藻纲 Glaucocystophyceae Schaffner 1922
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| 異名
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| * Glaucocystophyta Kies & Kremer, 1986
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**灰藻**（英語：glaucophyte或grey algae）也称**灰胞藻**（glaucocystophyte或glaucocystid），是**灰藻门**（学名：Glaucophyta或Glaucocystophyta）下的真核生物的统称，是原始质体生物中的一个较小众的单细胞淡水藻类演化支，具有独特的肽聚糖外膜包裹的色素体（质体）。灰藻是一个单系群，目前已知的物種數量相當稀少，約為 14 至 26 種，且主要分布於池塘、沼澤等淡水環境以及较潮湿的土壤中。

灰藻很可能是原始质体生物的基群，因为其叶绿体保留了許多与藍綠菌相似的祖先特徵，比如完全依赖无性繁殖，且没有已知的次生内共生现象。其姐妹群是两个更繁盛且更为人熟知的大类群——红藻类（包括红藻、玫瑰胞藻和皮胆虫）和绿色质体生物（包括所有的绿藻和陆地植物），其中红藻和绿藻都广泛有被其它原生生物胞吞后形成次生藻类的演化现象。对灰藻的研究有助于揭示叶绿体、绿藻和红藻的演化历史，因此备受生物学界关注。

## 特征

灰藻的质体也称为蓝小体（cyanelles）或灰质体（cyanoplasts），与其他植物的质体不同，灰藻的质体被肽聚糖包被，证明其曾与蓝藻内共生，从而获得质体。這種保有肽聚糖層的色素體在真核生物中極為罕見，是支持色素體源自藍綠菌內共生的關鍵證據之一。灰藻的色素體中還具有藻膽體（phycobilisomes），其主要由藍藻素（phycocyanin）和藻紅素（allophycocyanin）構成，用於捕捉不同波長的光能。這些特徵使灰藻在光合作用機制上與紅藻相似，但與綠色植物有所不同。灰藻含有叶绿素a，与紅藻和蓝藻一样通过藻胆体（Phycobilisome）接收光合作用所需要的阳光，这一结构中含有大量绿色植物已喪失的藻膽蛋白。灰藻的另一項特色是其碳固定过程在细胞质基质中进行，同样与红藻类似而与绿色植物的不同。這種保有肽聚糖層的色素體在真核生物中極為罕見，是支持色素體源自藍綠菌內共生的關鍵證據之一。

灰藻含有線粒體，其具有平滑的嵴，以没有中心粒的方式行有丝分裂。能运动的状态下的灰藻具有不等长的两根鞭毛。

## 繁殖

灰藻行开放式有丝分裂，以及通过产生游动孢子或非运动的似亲孢子来进行无性繁殖。例如，Cyanophora paradoxa 通過縱向分裂產生兩個子細胞，每個子細胞含有一個藍色素體。Glaucocystis 屬的物種則以產生自孢子的方式繁殖。迄今為止，尚未发现灰藻能够进行有性生殖的证据。

## 系统发育与分类

### 外类群

灰藻的近缘类群有红藻、皮胆虫、绿色植物和隐藻，这些类群间的系统发育关系尚不明晰，不同研究组的研究结果多有不同。

| 湯瑪斯·卡弗利爾-史密斯研究组
 | 帕特里克 J. 基林研究组
 | 阿拉斯泰尔 G. B. 辛普森研究组
 | Fabien Burki研究组
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皮胆虫

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红藻

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绿色植物

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灰藻

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隐藻

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皮胆虫

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红藻

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隐藻

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灰藻

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绿色植物

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皮胆虫

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红藻

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灰藻

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绿色植物

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隐藻

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灰藻

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绿色植物

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隐藻

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皮胆虫

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红藻

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### 内类群

根据目前的研究，灰藻的内部系统发育关系如下。

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| **灰藻 Glaucocystophyceae** |

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| 蓝载藻科 Cyanophoraceae
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蓝载藻属 *Cyanophora* |
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| 灰黏毛藻科 Gloeochaetaceae
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蓝褶藻属 *Cyanoptyche* |
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灰黏毛藻属 *Gloeochaete* |
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| 灰藻科 Glaucocystidaceae
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|  | *Glaucocystopsis* |
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灰藻属 *Glaucocystis* |
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### 分类表

灰藻在历史上曾被视为绿藻纲绿球藻目Oocystaceae科的一个子类群，但目前被视为与绿藻独立的植物类群。

目前已有13种灰藻被发现，但没有一种是广布种，其被置于五个属中，其分类表如下：

* 灰藻门 **Phylum Glaucophyta** Skuja 1948
	+ 灰藻纲 **Class Glaucocystophyceae** Schaffner 1922 [Cyanophorophyceae]
		- 蓝载藻目 **Order Cyanophorales** Kies & Kramer 1986
			* 蓝载藻科 **Family Cyanophoraceae** Kies & Kramer 1986
				+ Genus ?*Peliaina* Pascher 1929
					- *Peliaina cyanea* Pascher 1929
				+ Genus ?*Strobilomonas* Schiller 1954
					- *Strobilomonas cyaneus* Schiller 1954
				+ 蓝载藻属 Genus *Cyanophora* Korshikov 1924 （能够运动，缺乏细胞壁）
					- *C. tetracyanea* Korshikov 1941
					- *C. biloba* Kugrens et al. 1999
					- *C. sudae* Takahashi & Nozaki 2014
					- *C. paradoxa* Korshikov 1924
					- *C. kugrensii* Takahashi & Nozaki 2014
					- *C. cuspidata* Takahashi & Nozaki 2014
		- 灰黏毛藻目 **Order Gloeochaetales** Kies & Kremer 1986
			* 灰黏毛藻科 **Family Gloeochaetaceae** Bohlin 1901 ex Skuja 1954
				+ 蓝褶藻属 Genus *Cyanoptyche* Pascher 1929 （最缺乏研究的属)
					- 蓝褶藻属 *Cyanoptyche gloeocystis* Pascher 1929
				+ 灰黏毛藻属 Genus *Gloeochaete* von Lagerheim 1883 [*Schrammia* Dangeard 1889 non Britton & Rose 1930 non Guppy 1895; *Cyanochaete* Gobi 1916] （具有可运动和不可运动的阶段，细胞壁似乎不是由纤维素组成）
					- *G. protogenita* Kutzing
					- *G. wittrockiana* von Lagerheim 1883
		- 灰藻目 **Order Glaucocystales** Bessey 1907
			* 灰藻科 **Family Glaucocystidaceae** Bohlin 1901 ex West 1904
				+ Genus *Glaucocystopsis* Bourrelly 1961
					- *Glaucocystopsis africana* Bourrelly 1961
				+ 灰藻属 Genus *Glaucocystis* Itzigsohn 1868 （不能运动，但鞭毛作为痕迹器官保留了下来，具有纤维素的细胞壁。）
					- *G. bullosa* (Kützing 1836) Wille 1919
					- *G. caucasica* Tarnogradskii 1957
					- *G. cingulata* Bohlin 1897
					- *G. duplex* Prescott 1944
					- *G. molochinearum* Geitler
					- *G. simplex* Tarnogradskii 1959
					- *G. nostochinearum* Itzigsohn 1868 ex Rabenh. 1935
					- *G. geitleri* Pringsheim 1958 ex Takahashi & Nozaki 2016
					- *G. incrassata* (Lemmermann 1908) Takahashi & Nozaki 2016
					- *G. miyajii* Takahashi & Nozaki 2016
					- *G. bhattacharyae* Takahashi & Nozaki 2016
					- *G. oocystiformis* Prescott 1944

## 参考资料