Acoustical beam patterns for emission from several different bats are calculated assuming a piston source in an infinite baffle, both as single and as double emitters. The calculated beam patterns agree well enough with experimental values available in the literature to justify the assumptions used. For those bats which possess no facial appendages to serve as a baffle, the simple acoustical model does not work, as anticipated. The calculated beam patterns are for fixed frequencies in the examples used; however, some aspects of frequency modulated beams are briefly discussed.
Electrical signals have been detected in response to light excitation of the fungus Phycomyces blakesleeanus. These signals are related to the wavelength and intensity of the stimulus and the growth stage of the fungus. A relationship between the signals and the possible photoreceptor-pigment system is explored.The fungus Phycomyces blakesleeanus sporangiophore de-velops in stages designated as I through IVb. These growth stages are related to the elongation of the sporangiophore and to the development of the sporangium. The sporangiophore is a single cell that can grow to centimeters in length. The growth zone, from 0.1 to just beyond 2 mm below the sporangium, is indicated as the sensory region (6). Sensitivity of the sporangiophore to a variety of physical stimuli has been documented, and the most extensively studied response is the phototropic response (3). To date no specific photoreceptor structure has been identified and it is still inconclusive whether the photoreceptor molecule is a flavin or carotenoid (7, 10). Detection of electrical signals from the sporangiophore in response to light excitation has not been reported despite efforts to obtain such data. We have now detected electrical signals upon light excitation and would like to report these experimental results. MATERIALS AND METHODSThe experimental apparatus consisted of a two-chambered plastic well across which the sporangiophore was placed after it had been plucked and its base had been crushed. The sporangiophore made contact with the same solution in each chamber, 10 mm KCl, 12% sucrose. These chambers were connected to Ag-AgCl electrodes by agar-KCl bridges. The well (including the amplifier) was housed in a light-tight copper box, with a 2-cm hole and sliding cover to admit light. The One or more negative going spikes occurred on an average of 2.5 min after exposure to the microflash source. These spikes reached amplitudes of 8 to 20 mv and durations at about 0.5 sec (Fig. lb). They have been observed to occur only in stage I in response to the microflash and in response to monochromatic light of 420 nm with reduced amplitude. Using a series of Corning filter combinations with the microflash, 420 nm was seen to be effective in producing repeated spiking. No spiking could be observed above 537 nm, and spiking occurred only occasionally between 442 and 537 nm.As the sporangiophore matures through stages II to IVb, the complexity and type of the observed electrical response appears to change. Although the receptor potential is seen for all stages studied, the sporadic early receptor potential and the spike response is not seen in these later stages. This bears a relationship to the pigment system of Phycomyces. Orientation of the photopigment molecule is related to the early receptor potential observed in photoreceptors and plants (2,9). Experiments have shown that rod crystals, having a vertical orientation, can be observed in Phycomyces sporangiophore under polarized light (7, 10). These crystals appear to be aligned in the growth...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.