scholarly journals PHOTOTROPIC CIRCUS MOVEMENTS OF LIMAX AS AFFECTED BY TEMPERATURE

1924 ◽  
Vol 7 (1) ◽  
pp. 151-169 ◽  
Author(s):  
W. J. Crozier ◽  
H. Federighi

1. The theory of animal phototropism requires for particular instances a knowledge of the action of light as exerted through each of two bilaterally located receptors functioning singly. The measurement of "circus movements" which this involves must be concerned with such aspects of the reaction as are demonstrably dependent upon the effect of light. 2. The negatively phototropic slug Limax maximus exhibits very definite and continuous circus movement under vertical illumination when one eye-tentacle has been removed. The amplitude of the circling movement, measured in degrees deflection per cm. of path as an index of maintained differential tonus, is intimately related to the concurrent velocity of creeping. Analysis of the orienting mechanism is facilitated by the fact that in gasteropods such as Limax the animal creeps by means of the pedal organ, but orients (turns) by a totally distinct set of muscles in the dorsal and lateral regions of the body wall. 3. The expression of the phototropic orienting tendency, with illumination constant, is greatly influenced by the temperature. Above a zone centering at 15°, the amplitude of turning (degrees per cm. of path) is determined by the temperature in accurate agreement with Arrhenius' equation for chemical reaction velocity, with the critical increment µ = 16,820; and the rate of creeping is progressively less as the temperature rises, µ for its reciprocal being 10,900. Below 15°, the velocity of creeping becomes less the the lower the temperature, µ being again 16,800; while the amplitude of orientation is limited merely by the velocity of creeping, its reciprocal being directly proportional thereto. 4. Measurements of Limax circus movements in terms of turning deflection as function of light intensity must therefore be carried out at a temperature well above 15°. 5. The analysis provides a gross physical model of how an end-result may be influenced by temperature according to the effect of temperature upon each of several interconnected processes when the "temperature vs. effect" curves for these processes dynamically intersect. 6. It is pointed out that a certain type of unpredictability (quantative variability) in animal behavior under "normal" natural conditions probably results from dynamic equilibrium there obtaining between diverse mechanisms competing for effector control (in the present case, the creeping mechanism and that for turning, in the range 14–16°C.). It follows that the unraveling of the elements of conduct necessitates experimentation under diverse abnormal conditions favoring individual mechanism of response.

Author(s):  
Michel Duvert ◽  
Yvan Perez ◽  
Jean-Paul Casanova

The observation in natural conditions of headless chaetognaths with healed scars and ripe gonads led us to reproduce this condition experimentally. Histological sections were made on specimens of Sagitta and Spadella at different times after beheading. The muscles contract and the gut closes the wound, so that by the end of the first two hours, the body wall and gut ‘basement membranes’ are in continuity, so restoring the integrity of the body. After two hours, the muscular layer of the body wall is reshaped and closes up the wound; the gut seals off, and a ‘clot’ is evident in the wound area. The benthic Spadella cephaloptera survives some 30 d or more after decapitation. Specimens carrying ripe ova were able to lay them, to mature and fill their seminal vesicles once or twice and to mate with normal mature specimens. Headless chaetognaths must take up nutrients through the integument. It appears that chaetognaths cannot really regenerate head or tail tip.


1953 ◽  
Vol 4 (1) ◽  
pp. 95 ◽  
Author(s):  
AM Olsen

In south-eastern Australian waters, 5835 school sharks have been tagged since 1947. The two techniques used and the effects of some of the tags on the fins and body walls are described. It was found that the percentage return from experiments using both internal and fin tags was three times that from experiments using only fin tags. No significant difference was found in the numbers of white and grey Petersen disc fin tags returned. No deterioration has been detected in these tags and the silver tagging wires have not shown any appreciable signs of wear. Under natural conditions the incision made in the body wall for this insertion of the internal tag has been found to have healed completely within 2 months. Often there is no sign of the scar after 12 months.


1997 ◽  
Vol 17 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Philippe Moerman ◽  
Chris Van Geet ◽  
Hugo Devlieger
Keyword(s):  

Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.


Genetics ◽  
1994 ◽  
Vol 137 (2) ◽  
pp. 483-498
Author(s):  
J Ahnn ◽  
A Fire

Abstract We have used available chromosomal deficiencies to screen for genetic loci whose zygotic expression is required for formation of body-wall muscle cells during embryogenesis in Caenorhabditis elegans. To test for muscle cell differentiation we have assayed for both contractile function and the expression of muscle-specific structural proteins. Monoclonal antibodies directed against two myosin heavy chain isoforms, the products of the unc-54 and myo-3 genes, were used to detect body-wall muscle differentiation. We have screened 77 deficiencies, covering approximately 72% of the genome. Deficiency homozygotes in most cases stain with antibodies to the body-wall muscle myosins and in many cases muscle contractile function is observed. We have identified two regions showing distinct defects in myosin heavy chain gene expression. Embryos homozygous for deficiencies removing the left tip of chromosome V fail to accumulate the myo-3 and unc-54 products, but express antigens characteristic of hypodermal, pharyngeal and neural development. Embryos lacking a large region on chromosome III accumulate the unc-54 product but not the myo-3 product. We conclude that there exist only a small number of loci whose zygotic expression is uniquely required for adoption of a muscle cell fate.


1985 ◽  
Vol 260 (22) ◽  
pp. 12228-12233 ◽  
Author(s):  
H Takahashi ◽  
H Komano ◽  
N Kawaguchi ◽  
N Kitamura ◽  
S Nakanishi ◽  
...  

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1611-1622 ◽  
Author(s):  
Go Shioi ◽  
Michinari Shoji ◽  
Masashi Nakamura ◽  
Takeshi Ishihara ◽  
Isao Katsura ◽  
...  

Abstract Using a pan-neuronal GFP marker, a morphological screen was performed to detect Caenorhabditis elegans larval lethal mutants with severely disorganized major nerve cords. We recovered and characterized 21 mutants that displayed displacement or detachment of the ventral nerve cord from the body wall (Ven: ventral cord abnormal). Six mutations defined three novel genetic loci: ven-1, ven-2, and ven-3. Fifteen mutations proved to be alleles of previously identified muscle attachment/positioning genes, mup-4, mua-1, mua-5, and mua-6. All the mutants also displayed muscle attachment/positioning defects characteristic of mua/mup mutants. The pan-neuronal GFP marker also revealed that mutants of other mua/mup loci, such as mup-1, mup-2, and mua-2, exhibited the Ven defect. The hypodermis, the excretory canal, and the gonad were morphologically abnormal in some of the mutants. The pleiotropic nature of the defects indicates that ven and mua/mup genes are required generally for the maintenance of attachment of tissues to the body wall in C. elegans.


Parasitology ◽  
1965 ◽  
Vol 55 (1) ◽  
pp. 173-181 ◽  
Author(s):  
D. L. Lee

The cuticle of adults ofNippostrongylus brasiliensishas been described using histological, histochemical and ultrastructural techniques.The cuticle has the following layers: an outer triple-layered membrane; a single cortical layer; a fluid-filled layer which is traversed by numerous collagen fibrils; struts which support the fourteen longitudinal ridges of the cuticle and which are suspended by collagen fibrils in the fluid-filled layer; two fibre layers, each layer apparently containing three layers of fibres; and a basement lamella.The fluid-filled layer contains haemoglobin and esterase.The muscles of the body wall are attached to either the basement lamella or to the fibre layers of the cuticle.The mitochondria of the hypodermis are of normal appearance.The longitudinal ridges of the cuticle appear to abrade the microvilli of the intestinal cells of the host.Possible functions of the cuticle are discussed.I wish to thank Dr P. Tate, in whose department this work was done, for helpful suggestions and criticism at all stages of this work, and Mr A. Page for technical assistance. I also wish to thank Professor Boyd for permission to use the electron microscope in the Department of Anatomy.


1997 ◽  
Vol 17 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Philippe Moerman ◽  
Chris Van Geet ◽  
Hugo Devlieger
Keyword(s):  

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