. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 60 M. AOK1 ET Figure 6. Portion of the thoracic tunic of Clavelina nuniala viewed with Nomarski optics showing the distribution of cells in the tunic (A); a tunic cell of type I (B); tunic cells of type II (C); and a tunic cell of type III (D). 1952). According to Nicol (I960), the luminescence of Pyrosoma apparently differed from that of luminous bacteria because it was intermittent, excitable by tactile, electrical, and photic stimuli, and quenchable by illumi- nation. However, bacteria-like bodies packed in the lu- m
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 60 M. AOK1 ET Figure 6. Portion of the thoracic tunic of Clavelina nuniala viewed with Nomarski optics showing the distribution of cells in the tunic (A); a tunic cell of type I (B); tunic cells of type II (C); and a tunic cell of type III (D). 1952). According to Nicol (I960), the luminescence of Pyrosoma apparently differed from that of luminous bacteria because it was intermittent, excitable by tactile, electrical, and photic stimuli, and quenchable by illumi- nation. However, bacteria-like bodies packed in the lu- minous organ have been observed (Mackie and Bone, 1978), and bacterial luciferase has been found in it (Leis- man el ai, 1980; Nealson and Hastings. 1980). The lu- minescence of Pyrosoma may be controlled by the pack- aging of bacterial symbionts within the host cells (Mackie and Bone, 1978; Anctil, 1979: Nealson and Hastings. 1979, 1980). On the other hand, in the larvaceans, oikopleurids pos- sessing oral glands produce endogenous light upon me- chanical stimulation (Fredriksson and Olsson, 1981; Gait el a'., 1985). In Oikopleura dioica and O. labrado- riensis, light was produced from 1-2 /urn clusters of fluo- rescent granules (Sykes, 1980; Gait and Sykes, 1983). However, the light emitting mechanism in larvaceans is unknown (Gait and Sykes, 1983) and bacterial luciferase has not been found (Gait, 1978; Hastings, 1983). The re- lationship between the luminescent mechanisms ofC/a- velina and larvaceans is unknown, although they share the characteristics that light can be evoked from a point- source by mechanical stimulation. The mechanism of luminescence in Clavelina is prob- ably caused by an intrinsic mechanism. The apparently continuous luminescence was found to be the result of successive flashes of point sources of light. Furthermore, the emission of light could be caused by various modes of stimulation such as mechanical stimulation, increase of extracellular K+ ions, an
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