SIZE-REDUCTION, REPRODUCTIVE STRATEGY AND THE LIFE-CYCLE OF A CENTRIC DIATOM
SIZE-REDUCTION, REPRODUCTIVE STRATEGY AND THE LIFE-CYCLE OF A CENTRIC DIATOM
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DOI：
10.1098/rstb.1992.0056
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发表时间：
1992-05-29
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影响因子：
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通讯作者：
JEWSON, DH
中科院分区：
文献类型：
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作者：
JEWSON, DH
研究了亚北极Aulacoseira subarctica（O.穆勒）霍沃斯在内伊湖，北方爱尔兰，描述。在春季，每毫升的细胞数可达17000个。大多数细胞在硅限制后沉积到底部，并在夏季进入休眠状态。秋季的接种物部分来自重悬，存活的细胞（0.5-5%）在整个冬季继续生长，每一到两周加倍。种群经历了一个与有性生殖有关的规模缩小和再生周期。配子仅在较窄的细胞（直径3.8-7.4 μ m）中产生，通常是在低光照条件（表面辐照度100-150 μ E m-2 s-1）引起的生长中断之后，但营养物质的可用性，特别是二氧化硅和氮，也很重要。即使是最高密度的子实体（20 ml-1）也只占总细胞的一小部分（0.16%）。大小再生导致初始细胞的直径（14.8 +/- 2 μ m）约为亲本的三倍。较大的亲本细胞通常产生较大的原始细胞。随后，细胞分裂导致种群直径的减小，因为新的瓣膜被放置在环带下面。减少是最大的较宽的细胞（0.32 μ m每分裂），并逐渐减少细胞变得越来越窄。偶尔大的减少，高达1 μ m，遵循环境压力的时期。通过将这些结果与相关个体沿着细丝的细胞大小（宽度、长度和体积）变化的研究相结合，可以解释在将麦克唐纳-辉瑞假说应用于自然种群时存在的困难。 从理论上讲，L. Neagh可能会持续100次分裂或15年，但实际上，细胞在4-6年内达到性诱导的大小。这种差异是因为环境因素（如沉积、再悬浮、寄生等）在尺寸选择性方面也很重要。 这些因素的相互作用，加上低频率的间歇性有性生殖，导致了相对稳定的种群大小分布，其中总是有一些细胞在可以诱导性分化的大小范围内。总的来说。结果表明，为了充分了解硅藻种群动态，重要的是要量化整个生命周期的事件。
The life cycle of Aulacoseira subarctica (O. Muller) Haworth in Lough Neagh, Northern Ireland, is described. Cell numbers can reach up to 17 000 per millilitre in spring. Most cells sediment to the bottom after silica limitation and go into a resting state during summer. The inoculum in autumn partly comes from resuspension, with the surviving cells (0.5-5%) continuing to grow through the winter, doubling every one to two weeks. The population goes through a size reduction and regeneration cycle linked to sexual reproduction. Gametes are only produced in narrower cells (3.8-7.4-mu-m diameter), usually after interruptions in growth caused by low light conditions (surface irradiance 100-150-mu-E m-2 s-1), but availability of nutrients, especially silica and nitrogen, is also important. Even the highest densities of auxospores (20 ml-1) represent only a small proportion of the total cells present (0.16%). Size regeneration results in initial cells with diameters (14.8 +/- 2-mu-m) about three times those of the parent. Larger parent cells usually give rise to larger initial cells. Subsequently, cell division leads to a decrease in population diameter, because of the way new valves are laid down below the girdle bands. Reductions are largest in broader cells (0.32-mu-m per division) and gradually decrease as cells get narrower. Occasionally large reductions, up to 1-mu-m, follow periods of environmental stress. By combining these results with studies of changes in cell size (width, length and volume) in related individuals along filaments, it was possible to explain there have been difficulties in applying the MacDonald-Pfitzer hypothesis to natural populations. Theoretically, the life cycle in L. Neagh might extend over 100 divisions or 15 years but, in practice, cells reach a sexually inducible size in 4-6 years. The discrepancy is because environmental factors (e.g. sedimentation, resuspension, parasitism, etc.) are also important in size selectivity. The interaction of these factors, combined with intermittent sexual reproduction at low frequencies, results in a relatively stable population size distribution, where there are always Some cells in the size range in which sexual differentiation can be induced. Overall. the results demonstrate, that for a full understanding of diatom population dynamics, it is important to quantify events over complete life cycles.