Feeding in a calcareous sponge: Particle uptake by pseudopodia
Feeding in a calcareous sponge: Particle uptake by pseudopodia
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DOI：
10.2307/4134590
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发表时间：
2006-10-01
影响因子：
1.6
通讯作者：
Eerkes-Medrano, Dafne I.
中科院分区：
文献类型：
--
作者：
Leys, Sally P.;Eerkes-Medrano, Dafne I.
海绵被认为是滤食动物，就像它们最近的原生生物亲戚，领鞭毛虫一样。特化的“筛”细胞（后囊细胞）顶端有一个紧密排列的棒状微绒毛环，围绕着一个长鞭毛。鞭毛的跳动被认为是通过这个项圈吸引水，但项圈上的颗粒是如何被带到细胞表面的尚不清楚。我们已经研究了后鼻孔细胞和引入的颗粒之间发生的相互作用，在大饲养室的一个syconoid钙质海绵。在所有的颗粒中，只有0.1 μ m的乳胶微球粘附在大量的衣领微绒毛，但这些甚至更多的choanocyte表面。很少有大颗粒（0.5和1.0 μ m珠和细菌）接触的衣领微绒毛，大多数被吞噬的lamellipodia在侧或顶端的细胞表面，和团块的颗粒被吞噬的伪足延伸几微米的细胞表面。虽然延伸的choanocyte顶端表面长达16 μ m的发现，大多数是4 μ m长，两倍的衣领微绒毛的高度。这些观察结果提供了不同的观点，海绵颗粒吸收，并建议，至少在syconoid海绵，颗粒的吸收是不太依赖于严格的筛选功能的衣领微绒毛。
Sponges are considered to be filter feeders like their nearest protistan relatives, the choanoflagellates. Specialized "sieve" cells (choanocytes) have an apical collar of tightly spaced, rodlike microvilli that surround a long flagellum. The beat of the flagellum is believed to draw water through this collar, but how particles caught on the collar are brought to the cell surface is unknown. We have studied the interactions that occur between choanocytes and introduced particles in the large feeding chambers of a syconoid calcareous sponge. Of all particles, only 0.1-mu m latex microspheres adhered to the collar microvilli in large numbers, but these were even more numerous on the choanocyte surface. Few large particles (0.5- and 1.0-mu m beads and bacteria) contacted the collar microvilli; most were phagocytosed by lamellipodia at the lateral or apical cell surface, and clumps of particles were engulfed by pseudopodial extensions several micrometers from the cell surface. Although extensions of the choanocyte apical surface up to 16 mu m long were found, most were 4 mu m long, twice the height of the collar microvilli. These observations offer a different view of particle uptake in sponges, and suggest that, at least in syconoid sponges, uptake of particles is less dependent on the strictly sieving function of the collar microvilli.