The "unusual" reproduction of planktic foraminifera: an asexual reproductive phase of Neogloboquadrina pachyderma (Ehrenberg)
The "unusual" reproduction of planktic foraminifera: an asexual reproductive phase of Neogloboquadrina pachyderma (Ehrenberg)
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浮游有孔虫的“不寻常”繁殖：Neogloboquadrina pachyderma (Ehrenberg) 的无性繁殖阶段
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发表时间：
2006
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通讯作者：
M. Tsuchiya
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作者：
K. Kimoto;M. Tsuchiya
Neogloboquadrina pachyderma 是生活在世界海洋温带至亚极地水域的浮游有孔虫之一，广泛应用于高纬度古环境分析。然而，它们的生命周期和繁殖行为还没有得到足够的了解。在这里，我们展示了培养中浮游有孔虫 [Neogloboquadrina pachyderma (Ehrenberg) 右盘绕形式] 无性繁殖的第一个例子。 2003年3月，利用浮游生物拖曳，从日本邮岛和北海道之间的津轻海峡（北纬41°28.8’，东经141°14.2’，水温：4.7°C）的地表水中采集了26个用于培养实验的活体厚皮猪笼草标本。采集一周后，一只厚皮猪笼草在培养物中释放出大量双球形体。船只。所有被释放的个体都由两个房间组成，并且形状一致。此外，我们还可以看到其中流动的细胞质，以及从球形壳中伸出的似乎是根足的东西。我们将这些后代置于不同的温度下，并成功在 4.7 °C 和 8 °C 下培育了 6 个样本。特别是，尽管亲本壳具有右卷曲形态类型，但所有这些后代都发展出了左卷曲形态类型。此外，三个成熟的后代产生了配子。这些配子的 SSU rDNA 被归类为厚皮猪笼草 (N. pachyderma (sin.)) 基因型。因此，厚皮猪笼草可能具有交替的有性和无性繁殖阶段，并表现出两个卷曲方向。我们的研究结果表明，我们必须重新考虑厚皮猪笼草盘绕变异作为古气候指标的系统发育和形态学用途。 Anuár io do Inst i tu to de Geociências UFRJ ISSN 0101-9759 Vol. 1 29 1 / 2006 页。第461章
Neogloboquadrina pachyderma, one of the planktonic foraminifera that lives in temperate to subpolar waterin the world ocean is widely used in high-latitude paleoenvironmental analyses. However, their life cycles and reproductive behavior are not understood sufficiently well. Here we present the first example of asexual reproduction in a planktonic foraminifer [Neogloboquadrina pachyderma (Ehrenberg) right-coiling form] in culture. Twenty six specimens of living N. pachyderma for cultural experiments were collected from surface water in the Tsugaru Strait, between mailand Japan and Hokkaido (lat 41°28.8’N, long 141°14.2’E, water temperature: 4.7°C) using plankton tow on Mar. 2003. One week after from collecting, one N. pachyderma released a lot of bispherical bodies in the culture vessel. All released individuals consisted of two chambers and were uniform in shape. Moreover, we could see streaming cytoplasm in them and what appeared to be rhizopodia protruding from their spherical shells. We kept these offsprings in different temperatures and succeeded in growing six specimens at 4.7 °C and 8 °C. Particularly, in spite of the right-coiling morphotype of the parental shell, all these offsprings developed the left-coiling morphotype. Moreover, three matured offsprings produced gametes. The SSU rDNAs of these gamonts were classified as N. pachyderma (sin.) genotype. Thus, N. pachyderma may have alternating sexual and asexual reproductive phases and exhibit both coiling directions. Our findings suggest we must reconsider the phylogenetic and morphologic uses of both N. pachyderma coiling variations as paleoclimate proxies. Anuár io do Inst i tu to de Geociências UFRJ ISSN 0101-9759 Vol. 29 1 / 2006 p. 461