Conjugation of Paramecium tetraurelia cells: selective wheat germ agglutinin binding, reversible local trichocyst detachment and secretory function repair
Conjugation of Paramecium tetraurelia cells: selective wheat germ agglutinin binding, reversible local trichocyst detachment and secretory function repair
复制标题
四尿草履虫细胞的接合：选择性麦芽凝集素结合、可逆性局部毛囊脱离和分泌功能修复
DOI：
--
复制
发表时间：
1949
期刊：
影响因子：
--
通讯作者：
H. Fell
中科院分区：
文献类型：
--
作者：
A. Hughes;H. Fell
纤毛原生动物的接合涉及精确定义的阶段。草履虫中发生：（1）纤毛接触的形成； (2) 纤毛局部丧失，前腹侧体细胞膜之间形成狭窄接触；其次（3）形成小的细胞质桥（仅允许分子成分的交换）； (4) 它们的增大使细胞能够交换微核。这项工作集中于 P. tetraurelia 细胞的阶段 (2) 和 (3)。我们主要使用分泌突变体 nd6 和 tl（偶尔使用 nd9-28°C 和 7 S（野生型）细胞）分析了接合过程中的凝集素结合； （tl是无毛囊突变体，nd菌株是非放电突变体）。我们最重要的发现是：早期接触位点（阶段（2））可以用麦芽凝集素-异硫氰酸荧光素标记；只有早期阶段 (2) 可以通过过量的 WGA 来逆转；未发现伴刀豆球蛋白 A-异硫氰酸荧光素的选择性标记（在其他纤毛虫物种中常见）； WGA 结合位点很可能涉及 GlcNAc 残基。如前所述，毛囊在阶段 (2)/(3) 中从接触部位消失。然后我们更详细地分析了这个过程。三毛囊从细胞膜局部脱离（不转移至其他接合体）并在接合后重新插入。从我们用 nd6 / tl 缀合物获得的数据可以得出结论，三囊虫（特别是其中包含的分泌型凝集素或糖蛋白）不能在缀合过程中发挥调节作用，因为缀合先于分泌功能修复。我们还提供了 tl 细胞在 nd 突变中修复分泌功能的证据（尽管 tl 细胞缺乏任何可识别的“胞吐装置”）。 nd6 细胞比 nd9-28°C 更难“治愈”。 “治愈效果”似乎来自接合区。这可能表明主要在阶段（3）中发生了可扩散的“固化因子”交换。最后，我们表明，nd 细胞的分泌功能修复诱导“融合玫瑰花结”的组装，即毛囊释放位点野生型超微结构的形成，其程度与 nd 细胞功能修复的程度大致相同（通过响应两种不同触发剂的毛囊释放来观察）。注：*本文谨献给 Hellmuth Sitte 教授 60 岁生日
Conjugation of ciliated protozoa involves precisely defined stages. In Paramecium there occur: (1) the formation of ciliary contacts; (2) local loss of cilia and formation of narrow contacts between anterioventral somatic cell membranes; followed by (3) formation of small cytoplasmic bridges (which allow for the exchange of molecular components only); before (4) their enlargement enables the cells to exchange micronuclei. This work concentrates on stages (2) and (3) in P. tetraurelia cells. We analysed lectin binding during conjugation, using mainly secretory mutants nd6 and tl (occasionally nd9-28°C and 7 S (wild-type) cells); ( tl is a trichocyst-free mutant, nd strains are non-discharge mutations). Our most essential findings are: already early contact sites (stage (2)) can be labelled with wheat germ agglutinin-fluorescein isothiocyanate; only early stages (2) can be reversed with an excess of WGA; no selective labelling was found with concanavalin A-fluorescein isothiocyanate (commonly observed with other ciliate species); WGA binding sites most probably involve GlcNAc residues. As known before, trichocysts disappear from contact sites in stages (2)/(3). We then analysed this process in more detail. Trichocysts are locally detached from the cell membrane (without transfer to the other conjugant) and re-inserted after conjugation. From our data obtained with nd6 / tl conjugants one can conclude that trichocysts (in particular secretory lectins or glycoproteins contained in them) cannot play a regulatory role in the conjugation process, since conjugation precedes secretory function repair. We also present evidence for a secretory function repair in nd mutations by tl cells (though tl cells are devoid of any recognizable ‘exocytotic apparatus’). nd6 cells are more difficult to ‘cure’ than nd9-28°C . The ‘curing effect’ seems to emanate from the conjugation zone. This might indicate the occurrence of diffusible ‘curing factors’ exchanged mainly in stage (3). Finally, we show that secretory function repair in nd cells induces the assembly of ‘fusion rosettes’, i.e. the formation of the wild-type ultrastructure of the trichocyst release sites, to about the same extent as nd cells are functionally repaired (visualized by the release of trichocysts in response to two different trigger agents). Note: *This paper is dedicated to Professor Hellmuth Sitte on the occasion of his 60th birthday