共查询到20条相似文献,搜索用时 15 毫秒
1.
C. R. Franchina 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(2):111-119
I recorded the electric organ discharges (EODs) of 331 immature Brachyhypopomus pinnicaudatus 6–88 mm long. Larvae produced head-positive pulses 1.3 ms long at 7 mm (6 days) and added a second, small head-negative phase
at 12 mm. Both phases shortened duration and increased amplitude during growth. Relative to the whole EOD, the negative phase
increased duration until 22 mm and amplitude until 37 mm. Fish above 37 mm produced a “symmetric” EOD like that of adult females.
I stained cleared fish with Sudan black, or fluorescently labeled serial sections with anti-desmin (electric organ) or anti-myosin
(muscle). From day 6 onward, a single electric organ was found at the ventral margin of the hypaxial muscle. Electrocytes
were initially cylindrical, overlapping, and stalk-less, but later shortened along the rostrocaudal axis, separated into rows,
and formed caudal stalks. This differentiation started in the posterior electric organ in 12-mm fish and was complete in the
anterior region of fish with “symmetric” EODs. The lack of a distinct “larval” electric organ in this pulse-type species weakens
the hypothesis that all gymnotiforms develop both a temporary (larval) and a permanent (adult) electric organ.
Accepted: 1 March 1997 相似文献
2.
A. Silva L. Quintana M. Galeano P. Errandonea O. Macadar 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,185(2):187-197
The mechanisms that trigger the onset of the breeding season depend on geographical latitude. At the edge of Gymnotiform
distribution in America, variations in day length and water temperature are likely cues to initiate breeding. In this study
we aim to clarify the role of temperature and the interaction between temperature and hormonal state upon electric organ discharge
waveform. In breeding ponds, we measured naturally occurring changes of water temperature and of electric organ discharge
waveform during two 48-h periods in a sample of identified mature males and females of Brachyhypopomus pinnicaudatus. Water temperature, day-night cycle, and sexual maturity each modified electric organ discharge waveform. Temperature sensitivity
was also evaluated in the laboratory in adult sexually-differentiated individuals, adult non-differentiated fish, juveniles,
and testosterone-treated fish. Our data strongly suggest an interaction between the effects of temperature and steroid hormones
upon electric organ discharge waveform. High temperature (30 °C) induced a significant decay of head negative phase amplitude
in temperature-sensitive fish. This sensitivity was observed in physiological conditions that coincide with low levels of
steroid hormones: juveniles and adult fish kept in captivity at 20–21 °C. Conversely, temperature resistance was observed
in mature fish in the breeding habitat and was induced by testosterone treatment and by captivity at 27–28 °C.
Accepted: 23 May 1999 相似文献
3.
Alberto Capurro Khashayar Pakdaman Rossana Perrone Omar Macadar 《Biological cybernetics》1999,80(4):269-283
The electric fish Gymnotus carapo emits brief (4 ms) electric pulses separated by much longer intervals of high regularity (coefficient of variation 0.01–0.02).
Two main changes in the firing patterns of electric organ discharge were observed when two fish were placed together. (1)
All fish pairs showed an increase in the frequency difference between the two fish, in comparison with the value observed
in isolated fish, prior to the interaction. This change increased the number of beats per second between both discharge trains,
i.e., the number of times per second that the higher rate discharge sweeps the lower rate one when displayed on an oscilloscope.
(2) When the sweeping velocity fell below 2–3 sweeps/s, transient frequency increases were also observed in the electric organ
discharge of the higher rate fish when they were about to discharge simultaneously. The contribution to jamming avoidance
of these two changes was analyzed by comparing recordings of behavioral interactions with simulations produced by a computational
model. The jamming effect of the firing of a conspecific located in the same tank was evaluated by counting the number of
coincidences between both trains (occurrence of discharges of the two fish within 2 ms of one another). The number of coincidences
was evaluated as a function of the sweeping velocity in both simulations (with and without transient frequency increases)
and real fish. As the sweeping velocity increased, single coincidences increased slightly in simulations without transient
frequency increases, whereas the successive coincidences (coincidences repeated in successive discharges) decreased abruptly.
The simulation including transient frequency increases eliminated the successive coincidences and decreased the single ones.
Only when the sweeping velocity was less than 2–3 sweeps/s, did transient frequency increases improve the coincidence-avoiding
performance of the simulation. The number of coincidences observed in natural behavioral interactions for the different sweeping
velocities coincided with the distributions obtained with the simulations. As successive coincidences are known to be more
detrimental for electrolocation than single ones, the increase in the sweeping velocity may be considered a jamming avoidance
strategy in Gymnotus carapo, in addition to the already described transient frequency increases.
Received: 2 June 1998 / Accepted in revised form: 18 November 1998 相似文献
4.
G. von der Emde 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(2):217-224
Weakly electric fish can detect nearby objects and analyse their electric properties during active electrolocation. Four
individuals of the South American gymnotiform fish Eigenmannia sp., which emits a continuous wave-type electric signal, were tested for their ability to detect capacitive properties of
objects and discriminate them from resistive properties. For individual fish, capacitive values of objects had to be greater
than 0.22–1.7 nF (`lower threshold') and smaller than 120–680 nF (`upper threshold') in order to be detected. The capacitive
values of natural objects fall well within this detection range. All fish trained could discriminate unequivocally between
capacitive and resistive object properties. Thus, fish perceive capacitive properties as a separate object quality. The effects
of different types of objects on the locally occurring electric signals which stimulate electroreceptors during electrolocation
were examined. Purely resistive objects altered mainly local electric organ discharge (EOD) amplitude, but capacitive objects
with values between about 0.5 and 600 nF changed the timing of certain EOD parameters (phase-shift) and EOD waveform. A mechanism
for capacitance detection in wave-type electric fish based on time measurements is proposed and compared with the capacitance
detection mechanism in mormyrid pulse-type fish, which is based on waveform measurements.
Accepted: 31 July 1997 相似文献
5.
C. J. H. Wong 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(1):81-93
The functional role of the basal forebrain and preoptic regions in modulating the normally regular electric organ discharge
was determined by focal brain stimulation in the weakly electric fish, Eigenmannia. The rostral preoptic area, which is connected with the diencephalic prepacemaker nucleus, was examined physiologically by
electrical stimulation in a curarized fish. Electrical stimulation of the most rostral region of the preoptic area with trains
of relatively low intensity current elicits discrete bursts of electric organ discharge interruptions in contrast to other
forebrain loci. These responses were observed primarily as after-responses following the termination of the stimulus train
and were relatively immune to variations in the stimulus parameters. As the duration and rate of these preoptic-evoked bursts
of electric organ discharge interruptions (approximately 100 ms at 2 per s) are similar to duration and rate of natural interruptions,
it is proposed that these bursts might be precursors to natural interruptions. These data suggest that the preoptic area,
consistent with its role in controlling reproductive behaviors in vertebrates, may be influencing the occurrence of electric
organ discharge courtship signals by either direct actions on the prepacemaker nucleus or through other regions that are connected
with the diencephalic prepacemaker nucleus.
Accepted: 16 October 1999 相似文献
6.
7.
M. E. Nelson Z. Xu J. R. Payne 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(5):532-544
The first stage of information processing in the electrosensory system involves the encoding of local changes in transdermal
potential into trains of action potentials in primary electrosensory afferent nerve fibers. To develop a quantitative model
of this encoding process for P-type (probability-coding) afferent fibers in the weakly electric fish Apteronotus leptorhynchus, we recorded single unit activity from electrosensory afferent axons in the posterior branch of the anterior lateral line
nerve and analyzed responses to electronically generated sinusoidal amplitude modulations of the local transdermal potential.
Over a range of AM frequencies from 0.1 to 200 Hz, the modulation transfer function of P-type afferents is high-pass in character,
with a gain that increases monotonically up to AM frequencies of 100 Hz where it begins to roll off, and a phase advance with
a range of 15–60 degrees. Based on quantitative analysis of the observed gain and phase characteristics, we present a computationally
efficient model of P-type afferent response dynamics which accurately characterizes changes in afferent firing rate in response
to amplitude modulations of the fish's own electric organ discharge over a wide range of AM frequencies relevant to active
electrolocation.
Accepted: 14 June 1997 相似文献
8.
9.
G. von der Emde H. Bleckmann 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(5):511-524
Electroreceptive afferents from A- and B-electroreceptor cells of mormyromasts and Knollenorgans were tested for their sensitivity
to different stimulus waveforms in the weakly electric fish Gnathonemus petersii. Both A- and B-mormyromast cells had their lowest sensitivity to a waveform similar to the self-generated electric organ
discharge (EOD) (around 0° phase-shift). Highest sensitivities, i.e. lowest response thresholds, in both A- and B-cells were
measured at phase shifts of +135°. Thus, both cell types were inversely waveform tuned. The sensitivity of B-cells increased
sharply with increasing waveform distortions. Their tuning curves had a sharp minimum of sensitivity at +7° phase shift. A-cells
had a much broader waveform tuning with a plateau level of low sensitivity from +24° to −15°. Across a 360° cycle of phase-shifts,
the range of thresholds was 16 dB for individual B-cells and 4.5 dB for individual A-cells. Knollenorgan afferents were tuned
to 0° phase-shifted EODs and had a dynamic range of 12 dB. Lowest sensitivities were measured at a phase shift of +165°. Experiments
with computer-generated stimuli revealed that the strong sensitivity of mormyromast B-cells of EOD waveform distortions cannot
be attributed to any of the seven waveform parameters tested. In addition, EOD stimuli must have the correct duration for
B-cells to respond to waveform distortions. Thus, waveform tuning appears to be based on the specific combination of several
waveform parameters that occur only with natural EODs.
Accepted: 28 April 1997 相似文献
10.
Capurro A Longtin A Bagarinao E Sato S Macadar O Pakdaman K 《Biological cybernetics》2001,84(4):309-321
We recorded the electric organ discharges of resting Gymnotus carapo specimens. We analyzed the time series formed by the sequence of interdischarge intervals. Nonlinear prediction, false nearest
neighbor analyses, and comparison between the performance of nonlinear and linear autoregressive models fitted to the data
indicated that nonlinear correlations between intervals were absent, or were present to a minor extent only. Following these
analyses, we showed that linear autoregressive models with combined Gaussian and shot noise reproduced the variability and
correlations of the resting discharge pattern. We discuss the implications of our findings for the mechanisms underlying the
timing of electric organ discharge generation. We also argue that autoregressive models can be used to evaluate the changes
arising during a wide variety of behaviors, such as the modification in the discharge intervals during interaction between
fish pairs.
Received: 14 March 2000 / Accepted in revised form: 9 October 2000 相似文献
11.
K. D. Dunlap P. Thomas H. H. Zakon 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,183(1):77-86
Gymnotiform electric fish emit an electric organ discharge that, in several species, is sexually dimorphic and functions
in gender recognition. In addition, some species produce frequency modulations of the electric organ discharge, known as chirps,
that are displayed during aggression and courtship. We report that two congeneric species (Apteronotus leptorhynchus and A. albifrons) differ in the expression of sexual dimorphism in these signals. In A. leptorhynchus, males chirp more than females, but in A. albifrons chirping is monomorphic. The gonadosomatic index and plasma levels of 11-ketotestosterone were equivalent in both species,
suggesting that they were in similar reproductive condition. Corresponding to this difference in dimorphism, A. leptorhynchus increases chirping in response to androgens, but chirping in A. albifrons is insensitive to implants of testosterone, dihydrotestosterone or 11-ketotestosterone. Species also differ in the sexual
dimorphism and androgen sensitivity of electric organ discharge frequency. In A. leptorhynchus, males discharge at higher frequencies than females, and androgens increase electric organ discharge frequency. In A.␣albifrons, males discharge at lower frequencies than females, and androgens decrease electric organ discharge frequency. Thus, in both
chirping and electric organ discharge frequency, evolutionary changes in the presence or direction of sexual dimorphism have
been accompanied and perhaps caused by changes in the androgen regulation of the electric organ discharge.
Accepted: 18 February 1998 相似文献
12.
Mary Hagedorn Catherine Carr 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1985,156(4):511-523
Summary
Hypopomus occidentalis is a weakly electric Gymnotiform fish with a pulse-type electric organ discharge (EOD).Hypopomus used in this study were taken from one of the northernmost boundaries of this species, the Atlantic drainage of Panama where the animals breed at the beginning of the dry season (December). In normal breeding populations,Hypopomus occidentalis exhibit a sexual dimorphism in EOD and morphology. Mature males are large with a broad tail and have an EOD characterized by a low peak power frequency. Females and immature males are smaller, having a slender tail and EODs with higher peak power frequencies (Fig. 1). This study describes differences in the EOD and electric organ morphology between breeding field populations of male and femaleHypopomus. Changes in physiology, morphology and EOD shape which may accompany this seasonal change were examined in steroid injected fish, using standard histological and physiological techniques.A group of females were injected with hormones (5-dihydrotestosterone (DHT), estrogen or saline) to assess changes in their morphology and EOD. Animals treated with DHT developed characteristics which mimicked the sexually dimorphic characteristics of a male, while the other groups did not (see Fig. 5). Tissue from the tails of breeding males and females, and females treated with DHT, were sampled to measure the size of the electrocytes in the tail. The broader tail of males and DHT-females is composed of large electrocytes, whereas the slender tail of normal females is composed of smaller electrocytes. Therefore, the increase in the tail width in the female DHT group is caused by an enlargement of the electrocytes in this area.Intracellular recordings from the electrocytes of saline and DHT injected females show a difference in the responses of the rostral faces of the electrocytes from the two groups, which reflect the differences in their EODs. Saline-treated animals had symmetrical EODs (the first and second phase of the EOD were equal in duration and amplitude), while the physiological responses from each face of the electrocytes yielded responses that were similarly equal in duration and amplitude. DHT-treated animals had asymmetrical EODs (the first phase of the EOD was similar to that of saline treated fish and larger in amplitude and shorter in duration than the second phase) and the physiological responses of the electrocytes reflected this asymmetry. The differential recordings across the caudal face were similar to those from saline treated fish, while the responses from the rostral face were longer in duration and smaller in amplitude.These data suggest that the effects of androgens underlie the changes in single electrocytes which produce the sexually dimorphic signals and morphology present in natural breeding populations ofHypopomus occidentalis. 相似文献
13.
P. K. Stoddard B. Rasnow C. Assad 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,184(6):609-630
We measured and mapped the electric fields produced by three species of neotropical electric fish of the genus Brachyhypopomus (Gymnotiformes, Rham phichthyoidea, Hypopomidae), formerly Hypopomus. These species produce biphasic pulsed discharges from myogenic electric organs. Spatio-temporal false-color maps of the
electric organ discharges measured on the skin show that the electric field is not a simple dipole in Brachyhypopomus. Instead, the dipole center moves rostro-caudally during the 1st phase (P1) of the electric organ discharge, and is stationary
during the 2nd phase (P2). Except at the head and tip of tail, electric field lines rotate in the lateral and dorso-ventral
planes. Rostro-caudal differences in field amplitude, field lines, and spatial stability suggest that different parts of the
electric organ have undergone selection for different functions; the rostral portions seem specialized for electrosensory
processing, whereas the caudal portions show adaptations for d.c. signal balancing and mate attraction as well. Computer animations
of the electric field images described in this paper are available on web sites http://www.bbb.caltech.edu/ElectricFish or http://www.fiu.edu/∼stoddard/electricfish.html.
Accepted: 22 September 1998 相似文献
14.
Using the voltage/current clamp technique in the whole-cell configuration, we studied the role of the highly tetraethylammonium
(TEA) -sensitive component of integral potassium current in the generation of high-frequency tonic impulsation by rat retinal
ganglion cells (RGCs). Application of 0.5 mM TEA led to a decrease in the frequency of evoked tonic impulsation by RGCs by
63% (from 55 ± 10 sec–1 in the control to 26 ± 5 sec–1 in the presence of the blocker; n = 11). In this case, the duration of single action potentials at the level of 50% their amplitude increased by 64% (from
1.1 ± 0.1 to 1.8 ± 0.1 msec; n = 11), the rate of repolarization decreased by 54% (from −101 ± 9 to −46 ± 5 mV/msec; n = 11), and the amplitude of afterhyperpolarization dropped by 62% (from −16 ± 2 to −6 ± 2 mV; n = 11). Upon the action of 0.5 mM TEA, the amplitude of the integral potassium current in RGCs decreased; the current component
sensitive to the above blocker was equal to 0.41 ± 0.05 nA (n = 6), while the respective value in the control was 1.62 ± 0.14 nA (n = 12). Thus, a moderate (on average, by 25%) decrease in the amplitude of the above potassium current significantly influenced
the characteristics of impulse activity generated by RGCs. The TEA-sensitive component of the current was similar to the Kv3.1/Kv3.2
potassium current described earlier. The obtained data are indicative of the key role of the highly TEA-sensitive component
of the potassium current (passed probably via Kv3.1/Kv3 channels) in high-frequency tonic activity generated by RGCs. 相似文献
15.
Weakly electric fish generate an electric field around their body by electric organ discharge (EOD). By measuring the modulation
of the electric field produced by an object in the field these fish are able to accurately locate an object. Theoretical and
experimental studies have focused on the amplitude modulations of EODs produced by resistive objects. However, little is known
about the phase modulations produced by objects with complex impedance. The fish must be able to detect changes in object
impedance to discriminate between food and nonfood objects. To investigate the features of electric images produced by objects
with complex impedance, we developed a model that can be used to map the electric field around the fish body. The present
model allows us to calculate the spatial distribution of the amplitude and phase shift in an electric image. This is the first
study to investigate the changes in amplitude and phase shift of electric images induced by objects with complex impedance
in wave-type fish. Using the model, we show that the amplitude of the electric image exhibits a sigmoidal change as the capacitance
and resistance of an object are increased. Similarly, the phase shift exhibits a significant change within the object capacitance
range of 0.1–100 nF. We also show that the spatial distribution of the amplitude and phase shifts of the electric image resembles
a “Mexican hat” in shape for varying object distances and sizes. The spatial distribution of the phase shift and the amplitude
was dependent on the object distance and size. Changes in the skin capacitance were associated with a tradeoff relationship
between the magnitude of the amplitude and phase shift of the electric image. The specific range of skin capacitance (1–100 nF)
allows the receptor afferents to extract object features that are relevant to electrolocation. These results provide a useful
basis for the study of the neural mechanisms by which weakly electric fish recognize object features such as distance, size,
and impedance. 相似文献
16.
A. Falconi D. Lorenzo S. Curti F. R. Morales M. Borde 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(2):143-151
The present study was designed to examine the synaptic events in neurons of the pacemaker nucleus of Gymnotus carapo during the increase in rate of the electric organ discharge following activation of Mauthner cells. Pacemaker and relay cells
were investigated using intracellular recordings which were performed under two different conditions: (1) with the pacemaker
nucleus spontaneously discharging and (2) after its activity was abolished by anesthesia. Mauthner axon activation induced
an increase in the rate of pacemaker cell discharges. This response was accompanied by an increase in the slope of the pacemaker
potential (up to 110%) and a depolarization of these cells. The discharges of relay cells followed one to one those of pacemaker
cells. In contrast to that observed in pacemaker cells, only brief depolarizing antidromic effects could be evoked in relay
cells after Mauthner axon activation. In quiescent pacemaker cells, Mauthner cell activation induced a prolonged (up to 500 ms)
depolarizing potential with an average amplitude of 1.92 ± 0.82 mV; its latency was 4.43 ± 1.14 ms. Our data indicate that,
within the pacemaker nucleus, the population of pacemaker cells is the only target for Mauthner cell-evoked, short-latency
excitatory synaptic actions.
Accepted: 1 March 1997 相似文献
17.
G. K. H. Zupanc R. F. Sîrbulescu A. Nichols I. Ilies 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2006,192(2):159-173
The weakly electric fish Apteronotus leptorhynchus produces wave-like electric organ discharges distinguished by a high degree of regularity. Transient amplitude and frequency
modulations (“chirps”) can be evoked in males by stimulation with the electric field of a conspecific. During these interactions,
the males examined in this study produced six types of chirps, including two novel ones. Stimulation of a test fish with a
conspecific at various distances showed that two electrically interacting fish must be within 10 cm of each other to evoke
chirping behavior in the neighboring fish. The chirp rate of all but one chirp type elicited by the neighboring fish was found
to be negatively correlated with the absolute value of the frequency difference between the two interacting fish, but independent
of the sign of this difference. Correlation analysis of the instantaneous rates of chirp occurrence revealed two modes of
interactions characterized by reciprocal stimulation and reciprocal inhibition. Further analysis of the temporal relationship
between the chirps generated by the two fish during electric interactions showed that the chirps generated by one individual
follow the chirps of the other with a short latency of approximately 500–1000 ms. We hypothesize that this “echo response”
serves a communicatory function. 相似文献
18.
Sat Gavassa James P. Roach Philip K. Stoddard 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2013,199(5):375-384
In animal communication, the social context that elicits particular dynamic changes in the signal can provide indirect clues to signal function. Female presence should increase the expression of male signal traits relevant for mate-choice, while male presence should promote the enhancement of traits involved in male-male competition. The electric fish Brachyhypopomus gauderio produces a biphasic electric pulse for electrolocation and communication. Pulse amplitude predicts the signaler’s body size while pulse duration predicts circulating androgen levels. Males enhance pulse amplitude and duration when the numbers of males and females increase simultaneously. Here we tested the relative effects of female presence and male presence on male signal enhancement, and whether the size of the male competitor affected this enhancement. We found that male presence drives the enhancement of both pulse amplitude and second phase duration, independently of the size of the male competitor. Female presence induces the enhancement of pulse duration, but not pulse amplitude. These data suggest that males probably attend to information about a competitor’s body size coded by pulse amplitude and attend to aggressiveness coded by a competitor’s pulse duration, both potential predictors of fight outcome. Females may be primarily concerned about information on reproductive condition coded by pulse duration. 相似文献
19.
Many species of electric fish show diurnal or socially elicited variation in electric organ discharge amplitude. In Sternopygus macrurus, activation of protein kinase A by 8-bromo-cAMP increases electrocyte sodium current magnitude. To determine whether the behavioral plasticity in electric organ discharge amplitude is controlled by electrocyte biophysical properties, we examined whether the effects of phosphorylation on ion currents in the electric organ translate directly into electric organ discharge changes. We injected the electric organ of restrained fish with 8-bromo-cAMP and monitored the electric organ discharge. The effect of protein kinase A activation on electrocyte action potentials was examined in isolated electric organ using two-electrode current clamp. Electric organ discharge and action potential amplitude and pulse duration increased in response to 8-bromo-cAMP. Pulse and action potential duration both increased by about 25%. However, the increase in electric organ discharge amplitude (approximately 400%) was several-fold greater than the action potential amplitude increase (approximately 40%). Resting membrane resistance decreased in electrocytes exposed to 8-bromo-cAMP. We propose that in the Thevenin equivalent circuit of the electric organ a moderate increase in action potential amplitude combined with a decrease in internal resistance produces a greater voltage drop across the external resistance (the water around the fish), accounting for the large increase in the externally recorded electric organ discharge. 相似文献
20.
Growth hormone (GH) enhances the growth rate of aquacultured fish and shellfish, but it is difficult to extract native GH
from fish pituitary glands. However, fish recombinant GH (rGH) can be efficiently synthesized by Escherichia coli cells, although it exists in denatured form in inclusion bodies (IB). We studied the solubilization of IB and the renaturation
of rGH to help facilitate the production of a large amount of biologically active rGH. A 100-ml sample of rGH-producing E. coli produced 73.43 ± 5.47 mg IB (dry weight, n = 3) after 20 h induction by 1 mM isopropyl β-o-thiogalactopyranoside. Interestingly, if the bacteria were induced by 0.1 mM β-lactose, 95.3 ± 3.43 mg of IB was obtained.
The optimal conditions for denaturation and renaturation of rGH were when IB were solubilized in 6 M guanidine hydrochloride
and then dialysed against pH 10 dialysis buffer (50 mM ammonium bicarbonate and 2 mM EDTA) containing 100 mM l-arginine, 2 mM oxidized glutathione and 2 mM reduced glutathione for 24 h at 4 °C in a volume ratio of 3 to 500. At least
20% of the denaturated rGH in IB was renatured. Juvenile black sea bream injected with 0.05 μg/g resultant rGH once every
2 weeks exhibited significant increases (P < 0.05) in weight gain (84%) relative to fish in the control group over a 16-week period. This process is an economical and
effective way to obtain an active form of rGH biosynthesized by a prokaryotic system.
Received: 18 November 1996 / Received revision: 5 March 1997 / Accepted: 7 March 1997 相似文献