. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PADDLE CILIA ARE ARTIFACTS 471. Figure 3. Scanning electron micrographs of velar cilia in Lyrodus pedicellatus larvae. A, C. Isosmotic fixative containing 50% seawater (Method 3). No paddle cilia are present. B, D. Hypotonic fixative of Campos and Mann (1988) (Method 1). Paddle cilia are present. Scale bars: A-C, 10 ^m; D, 1 ftm. reported that swelling of isolated sucrose-treated cilia of Tetrahymena begins first at the tip, and progressively spreads to the base, indicating a "proximal-distal reduc- tion in the strength
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PADDLE CILIA ARE ARTIFACTS 471. Figure 3. Scanning electron micrographs of velar cilia in Lyrodus pedicellatus larvae. A, C. Isosmotic fixative containing 50% seawater (Method 3). No paddle cilia are present. B, D. Hypotonic fixative of Campos and Mann (1988) (Method 1). Paddle cilia are present. Scale bars: A-C, 10 ^m; D, 1 ftm. reported that swelling of isolated sucrose-treated cilia of Tetrahymena begins first at the tip, and progressively spreads to the base, indicating a "proximal-distal reduc- tion in the strength of connections between the axoneme and the membrane" (Pitelka and Child, 1964, p. 149). Various types of bridges linking the ciliary or flagellar membrane to the outer doublet microtubules have re- cently been studied biochemically and by electron mi- croscopy (Dentler, 1981). A new mutant of Chlamydom- onas reinhardtii with disc-shaped flagellar tips (loop-1) similar in appearance to paddle cilia has recently been isolated, indicating a possible genetic defect in the binding between the axoneme and flagellar membrane (Nakamura etai, 1990). It is commonly observed that paddle cilia and discocilia are limited in distribution within a given specimen; certain ciliary bands or body regions exhibit modified cilia, whereas other types of cilia in the same animal appear normal (Dilly, 1977a, b; Ehlers and Ehlers, 1978; Heimler, 1978; Arnold and Williams-Arnold, 1980; Bone et ai. 1982; Matera and Davis, 1982; Pfannenstiel, 1982; Cam- pos and Mann, 1988; our results). This restricted distri- bution of paddle cilia and discocilia has been used to argue against their artifactual nature, on the grounds that arti- factual production should effect all cilia uniformly (Bergquist et ai, 1977; Matera and Davis, 1982; Campos and Mann, 1988). However, Matera and Davis (1982) admitted that, "at the very least, these findings imply some unique properties of the tips of paddle cilia
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
