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Acceleration of puparium formation in Sarcophaga argyrostoma by electrical stimulation or scorpion venom
J. Insect Physiol., 1970, Vol.
16, pp. 1549 to 15.54. Pergamon Press.
ACCELERATION
OF PUPARIUM FORMATION
SARCOPHAGA BY ELECTRICAL
IN
ARGYROSTOMA
STIMULATION
G. FRAENKEL* Department
Primed in Great Britain
OR SCORPION VENOM
and E. ZLOTKIN
of Entomology and Venomous Animals, The Hebrew University, Jerusalem, Israel (Received 12 September 1969 ; revised 13 February
1970)
of the fly Sarcophaga argyrostoma were injected with the venom of a scorpion or a reduviid bug, or with ecdysone, or stimulated with electrical current, at an age of approximately 1, 2, or 3 days before puparium formation. The effect of all these treatments was to accelerate greatly the onset of this event, except with the reduviid venom, which caused an appreciable delay. It is concluded that the stimulating or inhibiting effects of these agents is more on the level of neuroendocrine activity than that of a direct action on ecdysone release from the prothoracic glands. Abstract-Larvae
INTRODUCTION
A HORMONALcontrol of puparium formation in flies was demonstrated long ago by FRAENKEL (1935). According to current views this event is dependent on a primary process of secretion of a brain (‘activating’) hormone from the median neurosecretory cells of the brain which stimulates the release of ecdysone from the lateral regions of the ring gland (GERSCH, 1962). The basic similarity of the neurosecretory cells and neurones or brain cells was emphasized by HANSTR~M (1953) through a detailed comparative study of the anatomy and histology of the nervous system in both invertebrates and vertebrates. On the basis of this view we assumed that a treatment which stimulates the nervous system might also accelerate processes depending on neurosecretion, such as puparium formation in flies. In this work larvae of the blowfly Sa~co#zaga argyrostoma R.-D. (= S. falculata Pand.) were subjected to two neuro-stimulatory treatments, one electrical and the other chemical-the application of scorpion venom, and their effects on the time of puparium formation compared. MATERIALS
AND METHODS
of Sarcophaga argyrostoma were bred on beef meat and subjected to the following treatments at different periods after completion of feeding. (a) Injection of 0.1 pg of lyophilized electrically milked venom of the yellow scorpion, Leiurus quimpestriutus, dissolved in distilled water. (b) Injection of 2 ~1 of a saturated Larvae
* Visiting Professor at the Hebrew University while this work was performed. Permanent address: Department of Entomology, University of Illinois, Urbana. 1549
1550
G. FRAENKEL AND E. ZLOTKIN
solution of ecdysone (Hofmaru-Laroche) in distilled water. (c) Injection of 1.0 tzg of freshly milked venom of the bug H&r&ius sp. (Reduviidae) dissolved in distilled water. (d) Injection of distilled water. (e) Electrical stimulation by exposing the larvae on a grid loaded with an electrical current of 20 V during 40 to 60 min. In addition, the treatments with scorpion venom and electricity were also applied to hind parts of larvae which had been ligatured 36 to 48 hr before puparium formation. Untreated larvae served as controls. The injections, throughout in amounts of 2-O &larva, were made with a syringe S l/4 LT and a Micrometric Buret (Micrometric Instrument Co., Cleveland, Ohio), using a No. 30 hypodermic needle. The larvae were injected ventrally into the posterior region without prior immobilization. The device for electrical stimulation consisted of two insulated electric wires (one for phase and the other for 0) with a cross-section of O-45 mms which were pierced by insect pins (No. 3) spaced in intervals of 2.4 mm in the manner and arrangement shown in Fig. 1. The effective area of stimulation, approximately 3.5 x 7 cm, was surrounded by a cellophane strip, 3 cm high, to keep in the larvae. 70 mm r
Entomological pins OS electrodes
p o
FIG.1. Diagram of the device for the electrical stimulation of fly larvae. Explanation in text.
The whole was mounted on a cork plate. Electrical current of 50 cycles and 20 V was regulated through a Powerstat (type 216, S.E. Co., Bristol, Connecticut). The larvae were stimulated while moving over the pins, thus closing the current through their bodies. Twenty-five to 30 larvae were used for each experiment, except for the untreated controls and those injected with the bug venom (40 larvae). One to three larvae died in each treatment. After treatment the larvae were kept at 25 of:2X!, and the numbers of puparia formed recorded at suitable intervals. RESULTS
The results are shown in Table 1 and are expressed in terms of the period of time after the treatment when 50 per cent of the larvae had formed puparia. This criterion was chosen since, as seen in Fig. 2, the curves of puparium formation have a sigmoid shape typical for biological processes, with the steepest and most sensitive region around the 50 per cent level. For the purpose of comparison the
ACCELERATION OF PUPARIUMFORMATION IN SARCOPHAGA
1551
ARGYROSTOMA
rate of acceleration or retardation in puparium formation is expressed as a percentage of the value obtained with the untreated controls. TABLE ~-THE
EFFECTOF DIFFERENTTREATMENTS ON THE TIME OF PUPARIUMFORMATION OF LARVAEOF Sarcophaga argyrostoma Time (hr) when 50% had formed puparia after different treatments Approximate age of larvae prior to puparium formation (days)
No. of experiment cu. cu. cu. cu. cu. cu. cu. cu.
1 1 1 2 2 2 2 3
(crop (crop (crop (crop (crop (crop (crop (crop
minute) minute) minute) small) small) small) small) small)
Untreated
Distilled water injected
Scorpion venom injected
Electrical stimulation
Ecdysone injected
Reduviid bug venom injected
Hr
%*
Hr
%*
Hr
%*
Hr
%*
Hr
%*
Hr
%*
35 25 29 49 43 48 43 76
100 100 100 100 100 100 100 100
30 23 27 43 32 43 40 67
85 92 93 87 74 89 93 88
57 20 17 68 __---
21 18
60 72
-
-
37 21
75 48
29 _
59 _
<18t _
<36f _
62 _
213 -
33 68 __----
27
56
-
-
73
43
56
58
76
70 -
163 -
56
* Period to puparium formation as a percentage of the untreated controls. t Probably cu. 12 hr (25%), judging by the appearance of the puparium at the time of inspection.
Fig. 2 represents in detail the results obtained in two sets of the experiments, one (Exp. 4 of Table 1) depicting the effects of scorpion venom, electrical stimulation, and ecdysone on larvae treated about 2 days before puparium formation, and the other (Exp. 3) showing the effect of the venom from the reduviid bug on larvae treated about 1 day before this event. Distilled water alone had an accelerating effect of about 10 per cent at all ages of the larvae (87.6 + 6.2 per cent of the time required for pupa&m formation by the untreated controls). A considerably higher acceleration, with the effects varying in different experiments, was achieved with the scorpion venom (64.8 f 9.6 per cent of time of controls). Electrical stimulation had an even more pronounced effect on the larvae treated 2 and 3 days before puparium formation, which occurred about 1 day earlier than in the untreated controls. But in the older larvae treated about 1 day before puparium formation the effect was of a similar order to that of the It had a scorpion venom. Ecdysone was tested in only two sets of experiments. dramatic effect in larvae injected 2 days before they would have normally formed puparia. After only 18 hr they were all puparia which had already considerably tanned. On the basis of the depth of tanning an average period to puparium formation of about 12 hr was estimated. In that case this period would have been less than 25 per cent that of the controls. The ecdysone must have acted almost
1552
G. FRAENKEL
AND
E. ZLOTKIN
immediately after injection. When ecdysone was injected into much younger larvae which would have normally formed puparia 3 days later, this process was advanced by about 20 hr. But electrical stimulation at that age had a much more dramatic effect than ecdysone, which was exactly the reverse of what happened in the older larvae.
Time,
hr
FIG. 2. Graphical representation of the effect of various treatments on the onset of
puparium formation in Treated Exp. 3. Treated cu. 2 days before water; 0, reduviid bug
larvae of Surcophuga argyrostoma. (See also Table 1) cu. 1 day before puparium formation. Exp. 4. - - - puparium formation. n , Untreated control; 0, distilled venom 0, scorpion venom; 0, ecdysone; A, electrical stimulation 20 V/60 min.
When the two treatments with scorpion venom or electrical stimulation were applied to the bind parts of larvae ligatured 36 to 48 hr before puparium formation there was no visible response. Both treated and untreated specimens failed to form puparia. In contrast to the above treatments, the application of venom of the bug Holotrichius sp. caused a delay in puparium formation, amounting to 213 per cent of the untreated controls in the older, and 163 per cent in the younger larvae. DISCUSSION
The excitatory effect of scorpion venom on nerves (ADAM et al., 1966) and muscles (ADAM and WEISS, 1959) is well known. Its general depolarizing effect is attributed to an increase in sodium permeability of the excitable membranes. At the neuromuscular junction scorpion venom has an excitatory and blocking activity through a presynaptic effect (PARNASand RUSSELL, 1967), possibly by causing an
ACCELERATION OF PUPARIUMFORMATION IN SARCOPHAGA
ARGYROSTOMA
1553
increase in the release of transmitter substance by the presynaptic nerve terminals (BRAZIL, 1966). We have also observed that the injection of higher doses of the yellow scorpion venom (above 0.3 pg/larva) into fly larvae causes an immediate muscular contraction which may endure for several hours, while the application of the venom of the reduviid bug, Holotrichizr, causes a relaxation expressed in an immobilization. These phenomena may represent antithetical neurotoxic effects of an excitatory or depressing nature. Thus, an excitatory venom causes an acceleration of puparium formation and a relaxating venom delay. The accelerating effect of electrical stimulation is even more striking since it is compared to the untreated control, while in the case of injections the puncture by itself has already a slight accelerating effect. Such an effect was not unexpected since it was shown by ROUBAUD (1922) and VARLEY and BUTLER (1933) that diapausing larvae of LuciZiu sericata and Lipara lucens could be induced to form puparia by a puncture. The fact that electrical stimulation or venom application was ineffective when applied to a ligatured hind part suggests that these stimuli do not act in a hormonomimetic pattern by substituting for the true hormone but act via the neurosecretoryendocrine system which is located in the anterior part. It was recently shown (CELESTE-HENRIQUES et al., 1968) that scorpion venom has a stimulatory effect on endocrine secretion in a mammal, causing a depletion of the adrenal catecholamines. It is apparent from these results that ecdysone acts more strikingly when applied closer to the natural time of puparium formation, when the target organs may be more receptive. It is noteworthy in this connexion that puparium formation in Calliphora erythroc+hala is preceded by a dramatic rise in the ecdysone titre (SHAAYA and KARLSON, 1965). On the other hand, the rate of acceleration caused by scorpion venom or electrical stimulation is rather independent of the age of the test larvae. This might suggest that the stimulatory effects of these agents could be more on the level of a neuroendocrine activity than directly on the prothoracic glands to release ecdysone. These agents then presumably would stimulate the release of the ‘activating’ hormone which, in turn, mobilizes the prothoracic glands This accelerating effect is fundamentally different from that of another accelerator of puparium formation of the nature of a neuroendocrine recently described by ZDARJJKand FRAENKEL (1969) which acts shortly before this event at a time when ecdysone is already present in the haemolymph. Acknowledgements-The authors wish to thank Professor A. SHULOVof this department for his support and Mr. P. AMITAI for designing the device for electrical stimulation. This investigation was in part supported by U.S. Public Health Service Research Career Award 5-K06-GM-l&495 made to G. F.
REFERENCES K. R. and WEISS C. (1959) Actions of scorpion venom on skeletal muscle. BY. J_ Pharmac. 14, 334-339. ADAMK. R., SCHMIDTH., STAMPFLIR., and WEISS C. (1966) The effect of scorpion venom on single myelinated nerve fibres of the frog. BY. J. Pharmac. 26, 666-677.
ADAM
1554
G. FRAENKELAND E.
ZLOTKIN
BRAZIL0. V. (1966) Some aspects of the pharmacology of the venoms of African scorpions. Mem Inst. Butantan. Sims. Int. 33, 603-614. CELBSTE-HENRIQUESM., GAZZINELLIG., DINIZ C. R., and GOMEZM. V. (1968) Effect of the venom of the scorpion Tityus serrulatus on adrenal gland catecholamines. Toxicon 5, 175-179. FRAENKELG. (1935) A hormone causing pupation in the blowfly Calliphora erythrocephala. PYOC. R. Sot. (B) 118, 1-12. GERSCH M. (1962) The activation hormone of the metamorphosis of insects. Gen. camp. Endocr. (Suppl.) 1, 322-329. HANSTR~MB. (1953) Neurosecretory pathways in the head of crustaceans, insects and vertebrates. Nature, Land. 171, 72-73. PARNASI. and RUSSELLF. E. (1967) Effects of venoms on nerve, muscle and neuromuscular junction. In Animal Toxins (Ed. by RUSSELLF. E. and SAUNDERS P. R.), pp. 401-415 Pergamon Press, Oxford. ROUBAUDE. (1922) Etudes sur le sommeil d’hiver prC-imaginal des muscides, les cycles d’asthenie, l’athermobiose reactivante specifique. Bull. Biol. Fr. Belg. 56, 455-544. SHAAYAE. and KARLSONP. (1965) Der Ecdysontiter w&rend der Insektenentwicklung-II. Die postembryonale Entwickhrng der Schmeissfliege Calliphora erythrocephala Meig. J. Insect Physiol. 11, 65-69. VARLEY G. C. and BUTLER C. G. (1933) The acceleration of development of insects by parasitism. Parasitology 25, 263-268. ZDAREKJ. and FRAENKELG. (1969) Correlated effects of ecdysone and neurosecretion on puparium formation (pupariation) of flies. Proc. nut. Acad. Sci. 64, 565-572.
16, pp. 1549 to 15.54. Pergamon Press.
ACCELERATION
OF PUPARIUM FORMATION
SARCOPHAGA BY ELECTRICAL
IN
ARGYROSTOMA
STIMULATION
G. FRAENKEL* Department
Primed in Great Britain
OR SCORPION VENOM
and E. ZLOTKIN
of Entomology and Venomous Animals, The Hebrew University, Jerusalem, Israel (Received 12 September 1969 ; revised 13 February
1970)
of the fly Sarcophaga argyrostoma were injected with the venom of a scorpion or a reduviid bug, or with ecdysone, or stimulated with electrical current, at an age of approximately 1, 2, or 3 days before puparium formation. The effect of all these treatments was to accelerate greatly the onset of this event, except with the reduviid venom, which caused an appreciable delay. It is concluded that the stimulating or inhibiting effects of these agents is more on the level of neuroendocrine activity than that of a direct action on ecdysone release from the prothoracic glands. Abstract-Larvae
INTRODUCTION
A HORMONALcontrol of puparium formation in flies was demonstrated long ago by FRAENKEL (1935). According to current views this event is dependent on a primary process of secretion of a brain (‘activating’) hormone from the median neurosecretory cells of the brain which stimulates the release of ecdysone from the lateral regions of the ring gland (GERSCH, 1962). The basic similarity of the neurosecretory cells and neurones or brain cells was emphasized by HANSTR~M (1953) through a detailed comparative study of the anatomy and histology of the nervous system in both invertebrates and vertebrates. On the basis of this view we assumed that a treatment which stimulates the nervous system might also accelerate processes depending on neurosecretion, such as puparium formation in flies. In this work larvae of the blowfly Sa~co#zaga argyrostoma R.-D. (= S. falculata Pand.) were subjected to two neuro-stimulatory treatments, one electrical and the other chemical-the application of scorpion venom, and their effects on the time of puparium formation compared. MATERIALS
AND METHODS
of Sarcophaga argyrostoma were bred on beef meat and subjected to the following treatments at different periods after completion of feeding. (a) Injection of 0.1 pg of lyophilized electrically milked venom of the yellow scorpion, Leiurus quimpestriutus, dissolved in distilled water. (b) Injection of 2 ~1 of a saturated Larvae
* Visiting Professor at the Hebrew University while this work was performed. Permanent address: Department of Entomology, University of Illinois, Urbana. 1549
1550
G. FRAENKEL AND E. ZLOTKIN
solution of ecdysone (Hofmaru-Laroche) in distilled water. (c) Injection of 1.0 tzg of freshly milked venom of the bug H&r&ius sp. (Reduviidae) dissolved in distilled water. (d) Injection of distilled water. (e) Electrical stimulation by exposing the larvae on a grid loaded with an electrical current of 20 V during 40 to 60 min. In addition, the treatments with scorpion venom and electricity were also applied to hind parts of larvae which had been ligatured 36 to 48 hr before puparium formation. Untreated larvae served as controls. The injections, throughout in amounts of 2-O &larva, were made with a syringe S l/4 LT and a Micrometric Buret (Micrometric Instrument Co., Cleveland, Ohio), using a No. 30 hypodermic needle. The larvae were injected ventrally into the posterior region without prior immobilization. The device for electrical stimulation consisted of two insulated electric wires (one for phase and the other for 0) with a cross-section of O-45 mms which were pierced by insect pins (No. 3) spaced in intervals of 2.4 mm in the manner and arrangement shown in Fig. 1. The effective area of stimulation, approximately 3.5 x 7 cm, was surrounded by a cellophane strip, 3 cm high, to keep in the larvae. 70 mm r
Entomological pins OS electrodes
p o
FIG.1. Diagram of the device for the electrical stimulation of fly larvae. Explanation in text.
The whole was mounted on a cork plate. Electrical current of 50 cycles and 20 V was regulated through a Powerstat (type 216, S.E. Co., Bristol, Connecticut). The larvae were stimulated while moving over the pins, thus closing the current through their bodies. Twenty-five to 30 larvae were used for each experiment, except for the untreated controls and those injected with the bug venom (40 larvae). One to three larvae died in each treatment. After treatment the larvae were kept at 25 of:2X!, and the numbers of puparia formed recorded at suitable intervals. RESULTS
The results are shown in Table 1 and are expressed in terms of the period of time after the treatment when 50 per cent of the larvae had formed puparia. This criterion was chosen since, as seen in Fig. 2, the curves of puparium formation have a sigmoid shape typical for biological processes, with the steepest and most sensitive region around the 50 per cent level. For the purpose of comparison the
ACCELERATION OF PUPARIUMFORMATION IN SARCOPHAGA
1551
ARGYROSTOMA
rate of acceleration or retardation in puparium formation is expressed as a percentage of the value obtained with the untreated controls. TABLE ~-THE
EFFECTOF DIFFERENTTREATMENTS ON THE TIME OF PUPARIUMFORMATION OF LARVAEOF Sarcophaga argyrostoma Time (hr) when 50% had formed puparia after different treatments Approximate age of larvae prior to puparium formation (days)
No. of experiment cu. cu. cu. cu. cu. cu. cu. cu.
1 1 1 2 2 2 2 3
(crop (crop (crop (crop (crop (crop (crop (crop
minute) minute) minute) small) small) small) small) small)
Untreated
Distilled water injected
Scorpion venom injected
Electrical stimulation
Ecdysone injected
Reduviid bug venom injected
Hr
%*
Hr
%*
Hr
%*
Hr
%*
Hr
%*
Hr
%*
35 25 29 49 43 48 43 76
100 100 100 100 100 100 100 100
30 23 27 43 32 43 40 67
85 92 93 87 74 89 93 88
57 20 17 68 __---
21 18
60 72
-
-
37 21
75 48
29 _
59 _
<18t _
<36f _
62 _
213 -
33 68 __----
27
56
-
-
73
43
56
58
76
70 -
163 -
56
* Period to puparium formation as a percentage of the untreated controls. t Probably cu. 12 hr (25%), judging by the appearance of the puparium at the time of inspection.
Fig. 2 represents in detail the results obtained in two sets of the experiments, one (Exp. 4 of Table 1) depicting the effects of scorpion venom, electrical stimulation, and ecdysone on larvae treated about 2 days before puparium formation, and the other (Exp. 3) showing the effect of the venom from the reduviid bug on larvae treated about 1 day before this event. Distilled water alone had an accelerating effect of about 10 per cent at all ages of the larvae (87.6 + 6.2 per cent of the time required for pupa&m formation by the untreated controls). A considerably higher acceleration, with the effects varying in different experiments, was achieved with the scorpion venom (64.8 f 9.6 per cent of time of controls). Electrical stimulation had an even more pronounced effect on the larvae treated 2 and 3 days before puparium formation, which occurred about 1 day earlier than in the untreated controls. But in the older larvae treated about 1 day before puparium formation the effect was of a similar order to that of the It had a scorpion venom. Ecdysone was tested in only two sets of experiments. dramatic effect in larvae injected 2 days before they would have normally formed puparia. After only 18 hr they were all puparia which had already considerably tanned. On the basis of the depth of tanning an average period to puparium formation of about 12 hr was estimated. In that case this period would have been less than 25 per cent that of the controls. The ecdysone must have acted almost
1552
G. FRAENKEL
AND
E. ZLOTKIN
immediately after injection. When ecdysone was injected into much younger larvae which would have normally formed puparia 3 days later, this process was advanced by about 20 hr. But electrical stimulation at that age had a much more dramatic effect than ecdysone, which was exactly the reverse of what happened in the older larvae.
Time,
hr
FIG. 2. Graphical representation of the effect of various treatments on the onset of
puparium formation in Treated Exp. 3. Treated cu. 2 days before water; 0, reduviid bug
larvae of Surcophuga argyrostoma. (See also Table 1) cu. 1 day before puparium formation. Exp. 4. - - - puparium formation. n , Untreated control; 0, distilled venom 0, scorpion venom; 0, ecdysone; A, electrical stimulation 20 V/60 min.
When the two treatments with scorpion venom or electrical stimulation were applied to the bind parts of larvae ligatured 36 to 48 hr before puparium formation there was no visible response. Both treated and untreated specimens failed to form puparia. In contrast to the above treatments, the application of venom of the bug Holotrichius sp. caused a delay in puparium formation, amounting to 213 per cent of the untreated controls in the older, and 163 per cent in the younger larvae. DISCUSSION
The excitatory effect of scorpion venom on nerves (ADAM et al., 1966) and muscles (ADAM and WEISS, 1959) is well known. Its general depolarizing effect is attributed to an increase in sodium permeability of the excitable membranes. At the neuromuscular junction scorpion venom has an excitatory and blocking activity through a presynaptic effect (PARNASand RUSSELL, 1967), possibly by causing an
ACCELERATION OF PUPARIUMFORMATION IN SARCOPHAGA
ARGYROSTOMA
1553
increase in the release of transmitter substance by the presynaptic nerve terminals (BRAZIL, 1966). We have also observed that the injection of higher doses of the yellow scorpion venom (above 0.3 pg/larva) into fly larvae causes an immediate muscular contraction which may endure for several hours, while the application of the venom of the reduviid bug, Holotrichizr, causes a relaxation expressed in an immobilization. These phenomena may represent antithetical neurotoxic effects of an excitatory or depressing nature. Thus, an excitatory venom causes an acceleration of puparium formation and a relaxating venom delay. The accelerating effect of electrical stimulation is even more striking since it is compared to the untreated control, while in the case of injections the puncture by itself has already a slight accelerating effect. Such an effect was not unexpected since it was shown by ROUBAUD (1922) and VARLEY and BUTLER (1933) that diapausing larvae of LuciZiu sericata and Lipara lucens could be induced to form puparia by a puncture. The fact that electrical stimulation or venom application was ineffective when applied to a ligatured hind part suggests that these stimuli do not act in a hormonomimetic pattern by substituting for the true hormone but act via the neurosecretoryendocrine system which is located in the anterior part. It was recently shown (CELESTE-HENRIQUES et al., 1968) that scorpion venom has a stimulatory effect on endocrine secretion in a mammal, causing a depletion of the adrenal catecholamines. It is apparent from these results that ecdysone acts more strikingly when applied closer to the natural time of puparium formation, when the target organs may be more receptive. It is noteworthy in this connexion that puparium formation in Calliphora erythroc+hala is preceded by a dramatic rise in the ecdysone titre (SHAAYA and KARLSON, 1965). On the other hand, the rate of acceleration caused by scorpion venom or electrical stimulation is rather independent of the age of the test larvae. This might suggest that the stimulatory effects of these agents could be more on the level of a neuroendocrine activity than directly on the prothoracic glands to release ecdysone. These agents then presumably would stimulate the release of the ‘activating’ hormone which, in turn, mobilizes the prothoracic glands This accelerating effect is fundamentally different from that of another accelerator of puparium formation of the nature of a neuroendocrine recently described by ZDARJJKand FRAENKEL (1969) which acts shortly before this event at a time when ecdysone is already present in the haemolymph. Acknowledgements-The authors wish to thank Professor A. SHULOVof this department for his support and Mr. P. AMITAI for designing the device for electrical stimulation. This investigation was in part supported by U.S. Public Health Service Research Career Award 5-K06-GM-l&495 made to G. F.
REFERENCES K. R. and WEISS C. (1959) Actions of scorpion venom on skeletal muscle. BY. J_ Pharmac. 14, 334-339. ADAMK. R., SCHMIDTH., STAMPFLIR., and WEISS C. (1966) The effect of scorpion venom on single myelinated nerve fibres of the frog. BY. J. Pharmac. 26, 666-677.
ADAM
1554
G. FRAENKELAND E.
ZLOTKIN
BRAZIL0. V. (1966) Some aspects of the pharmacology of the venoms of African scorpions. Mem Inst. Butantan. Sims. Int. 33, 603-614. CELBSTE-HENRIQUESM., GAZZINELLIG., DINIZ C. R., and GOMEZM. V. (1968) Effect of the venom of the scorpion Tityus serrulatus on adrenal gland catecholamines. Toxicon 5, 175-179. FRAENKELG. (1935) A hormone causing pupation in the blowfly Calliphora erythrocephala. PYOC. R. Sot. (B) 118, 1-12. GERSCH M. (1962) The activation hormone of the metamorphosis of insects. Gen. camp. Endocr. (Suppl.) 1, 322-329. HANSTR~MB. (1953) Neurosecretory pathways in the head of crustaceans, insects and vertebrates. Nature, Land. 171, 72-73. PARNASI. and RUSSELLF. E. (1967) Effects of venoms on nerve, muscle and neuromuscular junction. In Animal Toxins (Ed. by RUSSELLF. E. and SAUNDERS P. R.), pp. 401-415 Pergamon Press, Oxford. ROUBAUDE. (1922) Etudes sur le sommeil d’hiver prC-imaginal des muscides, les cycles d’asthenie, l’athermobiose reactivante specifique. Bull. Biol. Fr. Belg. 56, 455-544. SHAAYAE. and KARLSONP. (1965) Der Ecdysontiter w&rend der Insektenentwicklung-II. Die postembryonale Entwickhrng der Schmeissfliege Calliphora erythrocephala Meig. J. Insect Physiol. 11, 65-69. VARLEY G. C. and BUTLER C. G. (1933) The acceleration of development of insects by parasitism. Parasitology 25, 263-268. ZDAREKJ. and FRAENKELG. (1969) Correlated effects of ecdysone and neurosecretion on puparium formation (pupariation) of flies. Proc. nut. Acad. Sci. 64, 565-572.