Indian Journal of Pure & Applied Physics
Vol. 39, December 200 I , pp. 825-828
Bioluminescence of fireflies and evaluation of firefly pulses in
light of oscillatory chemical reactions*
J Saikia, R Changmai & G D Baruah
Laboratory of Non-linear Optics and Laser, Department of Physics, Dibrugarh University, Dibrugarh 786 004
Received 24 July 200 I : revised 8 October 200 I ; accepted I0 October 2001
The bioluminescence spect ra of few species tiretlies [species: Photinus pyralis, coleoptera: Lampyridae: Ph engodes
lactlcoJlis, lampryndae and Photuns pennsylvamca, Lampyndae] have been photographed in the wavelength range 5000 _
6700 A . The mtens1ty d1stnbut10ns of the spectra have be~n mvest1gated. The sca nning of the indi vidual firefly pulses have
been recorded and 11 IS s~own that the mten s1ty pattern of the pulses exhibit the oscillatory behaviour in chemical reaction
ms1de the metabolism of hrefly. The nature of relaxation oscillation is also exa mined in the firetly emi ss ion .
1 Introduction
The emission of light by natural means is of
considerab le
interest
to
biophysicists
and
biochemists due to the complicated reactions
involved . Electro-optical physicists have noted an
analogy between the in vivo emission of ma le
fireflies and laser light 1• The spectral distribution of
firefly light and the chemistry of firefly have been
investigated earlier2· 5• Earlier it was a view that was
generally accepted that the spectrum of a firefly is
continuous in nature with a single peak. This view
was also supported by the time resolved
spectrometrY'. But the work of Baruah and
coworkers 7·x indicate conclusively that distinct
groups of bands do exist in the spectrum of firetlies .
Observations on numerous specimens of fireflies
have established the fact that the emitted light
ranges in colour from green to yellow. But visual
observations do not exactly indicate the nature of
the bioluminescence spectrum . Fireflies do emit a
significant percentage of colours in longer and as
well as in the shorter wavelength side, which are not
readily observable to the naked eye under usual
conditions. Another important feature of the firefly
emission is the oscillatory nature of its pulses. A
detailed study of the pulses is expected to throw the
much-needed light on the nature of the chemical
reaction inside the metabolism of firetly. In the
present work the authors describe the in vivo
bioluminescence spectra of a large number of
*Paper presented at NCOMF 2000: Indian School of Min es .
Dhanbad 826 004
specimens belonging to three different species. The
pulses originating form an individual specimen of
firefly have been investigated.
2 Experimental Details
The bioluminescence spectra for three differe nt
species of fireflies (species A : Photinus pyralis.
Coleoptera: Lampyridae, Species B: Phengodes
lacticollis , Lampyridae and Species C : Ph oruris
pennsylvanica, Lampyridae) were photographed on
a g lass spectrograph with a slit width of 100 J..l.. Th e
experiments were conducted during early even in" to
midnight hours, local time, using fireflies colle;ted
just prior to the experiment. A single firetl y was
held immobile inside a cotton plug with its light
organ positioned towards the slit. An exposure time
for one and half hour was sufficient to record the
spectra on ORWO Panchromatic film of speed 400
ASA. The intensity di stributions of the spectra were
measured on densitometer (AIMIL). Fig. 1 shows
the spectra of the three main species of firefli es
under investigation and Fig. 2 is the intensity profil e
of the spectra as measured on a densitometer. Some
50 common specimens have been selected in thi s
way and their photographic records have been mad e.
The firefly pulses for a longer interval of time can
be investigated with the help of an experimental
arrangement as described below. The specimen of
firefly is kept immobilized by encapsulating it with
a thm cotton-wool plug. The light-emitting organ is
placed near the slit of a dark chamber. The light is
INDIAN J PURE & APPL PHYS , VOL 39,DECEMBER 2001
826
allowed to fall on a photomultiplier tube (Model ,
I I 00, Indotherm Institute, Bombay) and is fed to a
recorder (B-5000, Omniscribe recorder, Hou ston
Instrument series). The pul ses are recorded with the
help of chart moving with 25 em a minute. The
record has been made for three different conditions,
that is using a red filter, green filter and without
using any filters. A part of the record is shown in
Fig. 3. In Fi g. 4 the oscillation pattern of a firefly
pulses has been shown until it dies down naturally.
The authors have recorded the oscillation pattern s
for 30 specimens.
" .-:(
o<t,
::X
()
'-"'
"""'
r-
chemical oscillators~- • As may be inferred form
Fig. 4, there is an increase in intensity of the second
oscillating group (consisting of about I 0 pul ses) and
after that the osci llations grad ually di e down
indicating some sort of damping being in troduced in
the experimental system.
15
a
0
Fig. 2 - Densitometer traci ng of th e bioluminescence spectra
•A
a
--· B
c
8
'""
N
Fig. I -Bioluminescence spectra of three species of fireflies
photographs on a glass spectrograph
~ r-~~----------------------------~
·c:I
..cS
~
....
>
c
.!!
c
c
3 Results and Discussion
As may be inferred form Fig. 3 the intensity of a
pul se at first increases, reaches a max imum after
three pulses and then decreases again . The pattern of
inten sity of the pulses in an average group of I 0
pulses seem to be quite regular and indicates some
sort of oscillatory behaviour in chemical reaction
inside the metabolism. It is worthwhile to note th at
c hemical reactions can oscillate spontaneously and
during the last 20 years significant works have been
carried out on such experimental systems known as
18
24
3
36
Time [Sec]
Fig. 3 - Time resolved pulses of a firetly : (a) without tiller. (h)
with green filter and (c) with red filter
•
SAIKIA et a /.:BIOLUMINESCENCE OF FIREFLI ES
.
-~
c
!!
c
6
18
12
30
24
36
42
48
Ttme ( Sec)
Fig.4- A typical time resolved pulses of a firefly indi cation the osci ll atin g nature
,~-------,--------~
'9
·a
+-.• ·7
c
~·6
.a
~·5
.....
>'4
~·3
c
~·2
-.,
o
·1 ·a ·g 1
Time (set=)
·1 ·2 ·3 ·4 •5
·s
Fig.S - Characteristic pulse of a fireriy
The nature of the pu lses has been obse rved tn
al m ost a ll the firefly spec ime ns being investigated
in the work. The considerations set forth indicate
that o ne of the most strikin g c haracteristics of firefly
emission is its oscillatory nature. Th e osc illating
chem ical react ion s~ a nd the so-called BZ reacti ons.
as it came to be called , is considered as a good
model for compl ex systems. The mechanism s of
c hemi cal osc illati o ns can be very compl ex. The BZ
reaction itself is thought to in volve more th a n 20
e le mentary ste ps but as m a ny of the m came to
eq uilibrium rapidly, these a ll ow the kinetic to be
reduced to few steps o nl y. The e mi ss ion o f fire fl y is
recogni zed as due to a chemica l reaction which
lead s to a release of e ne rgy due to an oxidation
process . The e nzymes th at produce li g ht a re ca ll ed
luc iferase and the substrate luc ife rins. It is a ls o
believed that the fire tl y tl as h is triggered off by a
nerve impul se delive red to the lumin escence g land .
The reacti o n is singu la r in that o ne quantum of li g ht
is produced fo r each mo lecu le of luc ifer in ox id ized .
The mechani sm of chemi ca l osci ll at ions in firefly is
yet to be fully estab li shed. But it is reasonabl e to
believe th at reactions s imil ar to BZ reactions exist
inside the firetly metaho li sm.
As shown in Figs 3 and 4 the phenomenon of
re laxat ion oscillation is a lso striking ly demons'trated
in the bioluminescence pulses of fi re tlies. One of
the characteristic features of the pu lse is tha t th e
growth of intensity is very fast as compared to the
decay. Fig. 5 indicates a pulse fitted with the he lp of
a computer. The type of decay c urve shown here
may be con veni e ntl y represe nted by an eq uation of
the type I = /0 exp (- yl), w he re / 0 is the intens ity in it s
maximum position and y is the decay constant . The
sali e nt feature of all the firetly pulse is that the
inte nsity a lways grows from a non-zero valu e. In
contrast to the decay c urve the g rowt h is very fast.
Earl ier workers have est im ated thi s growth to be in
the order of microsecond s 2 • The growth and decay
of a typical firefly pulse is in fact analogous to the
828
INDIAN 1 PURE & APPL PHYS , VOL 39, DECEMB ER 200 1
phenomena like the charge and discharge of a
cond enser, firing of a rocket durin g its initi a l peri od
or a neuron pul se.
The evaluat ion of th e in vtvo bi o luminescence
spectra of the species of firetlies unde r
consideration shows some gene ra l agreement with
earlier in vivo measurements 2-<', but indicate few
disagree ments. The asymmetri c nature of the
intensity profi le is fo und to be present in a ll the
measurements. But the peak wavelengt hs of the
spectra were determined at different values by
different workers . The differences may be attributed
to the differences in measu re ment technique.
Tab le I shows the spectra l range of three differe nt
speci es of fireflies.
Tab le I Species
<Al
A
B
c
5000-6750
5190-6550
5200-6750
Maxima
I
5650
5650
5860
Acknowledgement
The authors are grateful to Prof R K Garti a of
the Department of Phys ics, Manip ur Univers ity,
Manipur, for a ll owi ng use of the fac iliti es in
conn ecti on with the scannin g of the fire tl y light
pulses.
References
Spectral characteristics of the in vivo
biolu minescence of fire fli es
Wavelength
range
soon shift to a new steady state; indeed , oscillati ons
in the concentration of intrace llul ar c hem ical species
may occur. There is a trul y remark ab le range of
speed of bi oc he mi ca l reacti ons vary in g from
diffusion-controlled reactions to th e li ght activated
prim ary reacti ons of photosynthesis in the pi cosecond time ran ge. Fin a ll y, there is a comp lex ity of
the chemica l pathways, many of which re main to be
e luc idated .
(A)
EW HM
II
6350
6130
6450
<Al
<Al
800
880
1350
700
480
590
Bradley D J. First European electro-optic 111arket and tech
conference, Geneva (North -Holl and. Amsterdam), 1972. p.
198.
2-h
From Table I and a lso from Fig. I tt ts apparent
that the spectra of firefly consists of two di stinct
max ima or band s. Thi s is contrary to the earli er
belief that fire fl y spectra are continu ous and do not
possess any di screte structure . The lon g wavelength
syste m of band is weak as compared to the short
wave length system. At thi s stage it is also difficult
to identify the origi n of the di screte st ructure in the
spectra or to make any correl ati on with the
osc illatory chemical reacti on. However, a prope r
interpretation of the spectra w ill throw the muc hneeded li ght on the nature of the osc ill atory reacti on
itself.
4 Conclusion
In the present study, the authors have used the
techniques
to
ana lyze
the
spectroscopic
bioluminescence emission of fireflies. The spectra
presumably show di screte structure and it may be
consi dered as important from the point of view of
ce ll-biology. In the present work , the time-reso lved
scan ning of firefly pulses has been considered as the
manifestation of chemi ca l oscill ators . It mu st be
noted that there is an inherent in stab ility of li g ht
processes . The authors are dea lin g wi th a variety of
steady states, each of which may be transitory and
2
Seli ga r H H & Martini R A. in Physiology of C11rre11t
tapics, Vol. IV, e nd , A C Glass (Academic Press. New
York ), 1968 , p. 263.
3
Whit e E H. Rapaport E & Hopki ns T A. Bioorga11ic
biochem , Vol. I. (Academic Press. ew York) . 197 1. p. 92 .
4
Corn ier M J. Lee J & Wampl er J E. Adv Rev Biochem. 44
( 1975) 255.
5
Lee J, in Science of ph oto-biologr. (Ed) K C Smith.
(Plen um Press. New York), 1977. p. 371.
6
Berry J D. Hei tman J M & Lane C R. 1 Appl Phys. 50
( 1979) 7 18 L
7
Baruah R K & Baruah G D. lndia11 1 Phr.1. 65B ( 199 1)
3~.
.
8
Bora L & Baruah G D. Indian 1 Phys. 658 ( 1991 ) 551 .
9
Stroga tz S H. in Non-linear dynamics cmd chaos (with
application to physics. biology a11d engineaing) (AddisonWes ley. Readin g. Massac hu setts. Ta ipei). 1994, p. 254.
I0
Kaga n M L, Keple r T B & Epstei n I R. Natu re. 349 ( 1991 )
506.
II
Rabai G , Orban M & Eps tein I R. 1 Phys Chem . 96 ( 1992)
5414.
12
Zh abotin sky A M, Buchholtz F. Ki yatkin A & Eps tein I R.
1 Phys Chem , 97 ( 1993) 7578.
13
Epstein I R & Showalter K, J Phys Chem , I00 ( 1996 )
13 132.
14
Dolnik M , Gard ner T S. Epstein I R & Collins J J. Phy.1·
Rev Lei/, 82 ( 1999) 15 82.
15
Orban M, Kurin -Csorge i K. Raba i G & Epstein I R. Cht' lll
Eng Sci, 55 (2000) 267.