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Biocummunication and Bioluminescence of Lampyridae
Jiin-Ju Chang 1,2 and Fritz-Albert Popp1
1, International institute of Biophysics (IIB) Neuss Germany
2, Institute of Biophysics, Chinese Academy of Sciences, Beijing China
Since cell to cell communication by light was demonstrated by means of photon emission in Popp’s Lab. quite a lot of experimental work has been done including measurements by coincident counting system (CCS). Also in theoretical studies, Popp has advanced a new model of photon sucking to explain non-linear phenomena of photon emission from living systems including synchronous photon emission from Dinoflagellates when they got light connection.
Light emission from fireflies is a good example for studying light communication. It has been known for a long time that males of Lampyridae, commonly known as the fireflies, search females at night by emitting flashes of light in a species-specific pattern. The female beetles respond the flashes by flashing back in a species- specific time interval. However up to now it is not clear how the communication takes place and how they recognize each other. In order to understand this, some experiments have been performed by CCS system and PMS-1 in Neuss and by BPCL in Beijing. We have shown the preliminary results from CCS measurements during last conference. In the present paper we would like to show some other properties of light emission from fireflies including the frequency patterns of flashes from fireflies and the "phase shifts". From these results we could explain that the interference may play an important role in communication between the beetles of Lampyridae.
The beetles of Lampyridae used in this study were captured in Beijing Hunting Park. One night before transported, they were caught and kept in a dark room for about 12h. and transported to Neuss in Germany by air. For CCS and PMS-1 measurements, Photon emission were measured after being captured 32h to 72h. Others were measured immediately after being captured. Fourier analysis and correlation analysis were carried out by computer programs.
The typical light emission patterns of male and female beetles of Lampyridea are similar, they have two different phases which may correspond to two different states. Here they were called as the quasi-stationary state and the oscillation state. In the quasi-stationary state the beetles spontaneously emit light with low intensities but in the oscillation state they emit flashes of light in relatively high intensities and with a species-specific frequency pattern.
The results from CCS measurements have shown that the photon count statistics from Lampyridae follows Poisson distribution rather than geometrical distribution. After exposure of beetles to light, the "Delayed luminescence" does not follow exponential law but hyperbolic curve demonstrating that bioluminescence from fireflies may be triggered by their biophotons even though it contains chemical reaction.
Fourier analysis of light emission from male and female beetles shows that male and female beetles have a frequency band in which common species-specific frequencies are included. Depending on environmental conditions the beetles can change their frequency pattern a little bit. When males start flashing from the stationary phase, during the phase transition the first peak is different from the others. The first peak includes a time shift, which can work as the mechanism for phase shift in establishing destructive interference.
According to our observation, we conclude that interference may take place between fireflies. Since frequency distribution and phase shift are very important in establishing interference there is a possibility to use these two capacities. Therefore the whole picture of how the communication take place between fireflies seems like that after receiving signals of flashing light, with a time delay the beetles emit flashing light which consists of a frequency band in which the common frequencies are included. As the consequence destructive interference may take place which establishes a platform on these common frequencies but other frequencies of flashes still can be seen some times. This proposal was confirmed with the observation of frequency changes of light emission from fireflies. When the beetles were places together or when they see each other, their frequencies moved to lower bands and the higher ones disappeared.
Up to now it has been well documented that bioluminescence is due to oxidation of Luciferin, which exists nearly in all species of fireflies and operates under presentation of Luciferase with ATP and Mg. To explain light communication between fireflies Soucek et al proposed a response function model. Upon receiving a flash from male the female generates a neural response function which consists of a cycle including three phases of inhibition-excitation-inhibition. The female will answer and flash back only if the male's flash is received under accepting the excitation phase. Different species have identical duration and the interflash interval of male flashes and the time delay of female's response. However our experimental results show that light communication between fireflies is based on constructive and destructive interference.
There are some questions left, for instance, what is the characteristic of the light emission in the stationary state? How are the two phases of light emission related to each other?
