Erratum

1971 ◽  
Vol 54 (1) ◽  
pp. 1-1
Author(s):  
GENTLE M. J.
Keyword(s):  
Colour Change ◽  
Nervous Control ◽  
Phoxinus Phoxinus

The central nervous control of colour change in the minnow (Phoxinus phoxinus L.) Discussion, line 4: Delete ‘unlike the fish used by the Dijkgraaf’

The Central Nervous Control of Colour Change in the Minnow (Phoxinus Phoxinus L.)

1971 ◽  
Vol 54 (1) ◽  
pp. 83-91
Author(s):  
MICHAEL J. GENTLE
Keyword(s):  
Optic Nerve ◽  
Optic Tectum ◽  
Posterior Part ◽  
Colour Change ◽  
Complete Removal ◽  
The Other ◽  
Nervous Control ◽  
Phoxinus Phoxinus ◽  
External Conditions

1. The colour of the minnow Phoxinus phoxinus L. and its ability to undergo colour change were studied after partial and complete blinding. The blinding was accomplished either by section of the optic nerve or by tectal ablation. 2. Following bilateral section of the optic nerve the blinded minnows darken. After the initial darkening, half of the fish pale and the other half remain dark. 3. The colour of the fish blinded by bilateral section of the optic nerve could not be affected by external conditions. 4. Following complete removal of the optic tectum the fish at first paled, but after 24 h they darkened to very variable tints. 5. Unilateral section of the optic nerve coupled with unilateral tectal removal on the same or opposite side did not affect the ability of the fish to change colour. 6. The bilateral removal of the anterior tectum from a blinded darkened fish did not affect its colour. 7. The bilateral removal of the posterior tectum of a darkened fish caused maximal pallor. 8. By a series of lesions an area in the dorsal posterior part of the optic tectum was found to cause darkening in the blinded fish because following its removal the fish paled. 9. It is suggested that the fibres from the tectum may act by exciting or inhibiting the neurones of the paling centre in the anterior medulla.

The Central Nervous Control of Colour Change in the Minnow (Phoxinus Phoxinus L.)

1971 ◽  
Vol 54 (1) ◽  
pp. 93-102
Author(s):  
MICHAEL J. GENTLE
Keyword(s):  
Optic Tectum ◽  
Colour Change ◽  
The Other ◽  
Dorsal Part ◽  
Nervous Control ◽  
Phoxinus Phoxinus ◽  
Normal Fish

1. A series of ablations were carried out in the optic tectum of the minnow, Phoxinus phoxinus, in order to investigate its importance in colour change. 2. The presence of the anterior or posterior tectum alone one on or both sides caused persistent pallor in normal fish. 3. The presence of the anterior tectum on one side and the posterior on the other enabled the fish to adapt chromatically to its background. 4. Small bilateral removals from the dorsal part of the optic tectum did not effect colour change. Larger removals from the dorsal tectum reduced the extent of change and still larger removals caused the fish to pale on all backgrounds.

scholarly journals The lantern shark's light switch: turning shallow water crypsis into midwater camouflage

2010 ◽  
Vol 6 (5) ◽  
pp. 685-687 ◽  
Author(s):  
Julien M. Claes ◽  
Jérôme Mallefet
Keyword(s):  
Shallow Water ◽  
Deep Sea ◽  
Light Emission ◽  
Colour Change ◽  
Hormonal Control ◽  
Nervous Control ◽  
Luminous Bacteria ◽  
Physiological Colour Change ◽  
Physiological Suppression

Bioluminescence is a common feature in the permanent darkness of the deep-sea. In fishes, light is emitted by organs containing either photogenic cells (intrinsic photophores), which are under direct nervous control, or symbiotic luminous bacteria (symbiotic photophores), whose light is controlled by secondary means such as mechanical occlusion or physiological suppression. The intrinsic photophores of the lantern shark Etmopterus spinax were recently shown as an exception to this rule since they appear to be under hormonal control. Here, we show that hormones operate what amounts to a unique light switch, by acting on a chromatophore iris, which regulates light emission by pigment translocation. This result strongly suggests that this shark's luminescence control originates from the mechanism for physiological colour change found in shallow water sharks that also involves hormonally controlled chromatophores: the lantern shark would have turned the initial shallow water crypsis mechanism into a midwater luminous camouflage, more efficient in the deep-sea environment.

Evidence for the participation of a melanin-concentrating hormone in physiological colour change in the eel

1984 ◽  
Vol 102 (2) ◽  
pp. 237-243 ◽  
Author(s):  
I. D. Gilham ◽  
B. I. Baker
Keyword(s):  
Colour Change ◽  
Rapid Decline ◽  
White Background ◽  
Slight Effect ◽  
Pectoral Fin ◽  
Nervous Control ◽  
Antagonistic Effects ◽  
Melanin Concentrating Hormone ◽  
Physiological Colour Change

ABSTRACT The hormonal and nervous control of colour change in the eel has been investigated. The only bioactive forms of MSH found in eel pituitary extracts or secreted by eel pituitary cultures were forms of α-MSH; no β-MSH was detected. After transfer of eels from a black to a white background, the melanin concentration in skin melanophores was accompanied by a rapid decline in plasma α-MSH titres. Hypophysectomy resulted in melanin concentration, and pituitary extracts injected into hypophysectomized eels caused melanin dispersion. This effect was eliminated if the pituitary extracts were first incubated with a specific α-MSH antiserum or if the antiserum was injected into the hypophysectomized eel. However, injection of α-MSH antiserum into intact, black-adapted eels failed to result in melanin concentration although the same antiserum was effective in causing pallor in black-adapted toads. Partially purified preparations of teleost melanin-concentrating hormone (MCH), free from catecholamines, induced melanin concentration when injected into black-adapted eels and this effect was significantly potentiated by injections of α-MSH antiserum. The denervation of melanophores on the pectoral fin had only a slight effect on the responses of the melanophores to humoral agents. It is concluded that the control of physiological colour change in the eel is largely hormonal, and involves the antagonistic effects of α-MSH and a melanin-concentrating agent which is probably MCH. J. Endocr. (1984) 102, 237–243

Electrical Activity in the Optic Tectum and Colour Change in the Minnow (Phoxinus Phoxinus L.)

1971 ◽  
Vol 55 (3) ◽  
pp. 641-649
Author(s):  
MICHAEL J. GENTLE
Keyword(s):  
Electrical Activity ◽  
Optic Tectum ◽  
High Frequency ◽  
Colour Change ◽  
Phoxinus Phoxinus ◽  
Black Background ◽  
High Frequency Activity

1. The electrical activity of the optic tectum was recorded from the minnow under various conditions to investigate its relationship to colour change. 2. The superficial E.E.G. was found to consist of two rhythms a 6-14 Hz (20-112 V) and a 18-24 Hz (6-18 µV). 3. When the fish were deeply anaesthetized the E.E.G. was reduced virtually to nothing. 4. Almost no activity was present in the optic tectum 30 min after bilateral blinding. There was an increase in activity after 5 h and this continued for 5 or more days but never returned to normal. 5. In darkness the activity of the superficial E.E.G. first increased and then decreased, and when the eyes were re-exposed to light the activity increased again. 6. The E.E.G. patterns were recorded and analysed from various depths and positions in the optic tectum during background reversal. In the stratum plexiformeet fibrosum externum, plexiforme internum and griseum internum no changes were observed. In the stratum fibrosum profundum and griseum periventriculare an increase in the high-frequency activity of approximately 10 Hz was observed on a black background.

scholarly journals The Photoreceptors of Lampreys

1935 ◽  
Vol 12 (3) ◽  
pp. 254-270
Author(s):  
J. Z. YOUNG
Keyword(s):  
Colour Change ◽  
Diurnal Changes ◽  
Posterior Pituitary ◽  
Nervous Control ◽  
Pineal Complex ◽  
Artificial Illumination ◽  
Pituitary Secretion ◽  
Set Up ◽  
The Brain ◽  
Illumination Removal

1. Illumination of the dorsal region of the head of an ammocoete larva is followed by movements of the animal, but only after exposure for longer periods than are necessary to elicit responses from the tail. 2. Since this reaction persists unaffected after removal of the pineal and paired eyes, it is concluded that it is produced by the direct effect of light on some tissue in the brain. 3. Larval and adult L. planeri show very pronounced daily rhythms of colour change, becoming pale at night and dark during the daytime. 4. Continuous artificial illumination of the animals produces maximal darkening and stops the diurnal rhythm. 5. When animals are left in total darkness the diurnal changes usually persist, though diminished in extent; sometimes the melanophores come to rest in the expanded phase. 6. Since section or faradic stimulation of spinal nerves is not followed by local changes in the melanophores, it is concluded that these are not under nervous control. 7. After removal of either the whole pituitary complex or its pars nervosa and intermedia the animals become maximally pale, and remain so indefinitely in spite of changes of illumination. 8. Injection of extracts of mammalian posterior pituitary lobe causes darkening of such hypophysectomised lampreys. 9. Pituitrin was also found to be capable of maintaining the expansion of isolated melanophores. 10. After removal of the pineal complex from ammocoetes the rhythms of colour change were interrupted, the melanophores remaining in the expanded phase under all conditions of illumination. Removal of the pineal of adult L. planeri disturbed the colour rhythm, which was then completely abolished if the paired eyes were also removed. 11. Thus the paling of an ammocoete when it passes from light to darkness is probably due to the inhibition of posterior pituitary secretion by nervous impulses set up by the change of illumination of the pineal complex.

scholarly journals The Pigmentary Effector System IV.--A Further Contribution to the Role of Pituitary Secretion in Amphibian Colour Response

1924 ◽  
Vol 1 (2) ◽  
pp. 249-270
Author(s):  
LANCELOT T. HOGBEN
Keyword(s):  
Colour Change ◽  
Complete Removal ◽  
Posterior Lobe ◽  
Pituitary Extract ◽  
Nervous Control ◽  
Normal Individuals ◽  
Effector System ◽  
Physiologically Active Substances ◽  
Normal Colour ◽  
Pituitary Secretion

1. The contracted melanophores of both Anura (frogs and toads) and Urodela (salamanders) react by maximal expansion to pituitary extract; the active substance in the latter does not appear to be confined invariably to the posterior lobe of the mammalian gland. A positive melanophore response was obtained from the gland of a human abortus in the fourth month. 2. The removal of the whole pituitary gland may be accomplished in Urodele larvaæ (Amblystoma tigrinum) at any age (nine months to four years) without impairing their viability. After complete removal of the pituitary in Urodele larvæ, as in adult and larval Anura, the melanophores remain contracted and a state of permanent pallor ensues. The normal colour resulting from melanophore expansion can be re-established by injection of pituitary extract; but such animals regain pallor, although exposed to conditions in which melanophore expansion invariably occurs in normal individuals. 3. It is legitimate to conclude that pituitary secretion is the main factor in regulating the chromatic function throughout the Amphibia as a class. Fluctuating pituitary secretion in correlation with those conditions that evoke colour response in the frog (cf. the third paper of this series) provides a satisfactory basis for the interpretation of all the accredited bionomic data concerning colour response in adult Amphibia. Possibly adrenal secretion or some auxiliary mechanism plays a subsidiary part; but there are no satisfactory grounds for believing that nervous agencies directly influence amphibian melanophores; and there is reason to believe that even if amphibian melanophores are directly innervated, nervous control is not significant to the normal rhythm of colour change. 4. The study of amphibian colour response provides evidence not only of the presence of physiologically active substances in the pituitary, but functional activity of the gland in the intact animal. It does not appear, however, that the interpretation of colour response here put forward for Amphibia can be extended to Reptiles and Fishes.

The Eye and Colour Change in the Minnow (Phoxinus Phoxinus L)

1972 ◽  
Vol 57 (3) ◽  
pp. 701-707
Author(s):  
MICHAEL J. GENTLE
Keyword(s):  
Colour Change ◽  
White Background ◽  
Surgical Removal ◽  
Phoxinus Phoxinus ◽  
Black Background ◽  
Temporal Field ◽  
Dorsal Retina

1. Counts were made of the retinal receptors and observations were made of the colour of the minnow, Phoxinus phoxinus L., following the surgical removal of parts of the dorsal and ventral retina. 2. It was found that there were greater numbers of retinal receptors in the temporal field than in the rostral field of the eye. 3. There were very few triple and quadruple cones but a large number of double and single cones in the ventral retina compared to the dorsal. 4. Surgical removal of the dorsal retina or only part of it resulted in the fish being fully dark-adapted on a black or white background. 5. Surgical removal of the ventral retina resulted in the fish assuming an intermediate colour on a white background and a darker tint on a black background.

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