A Study of the Function of the Neural Fat-Body Sheath in the Stick Insect, Carausius Morosus

1972 ◽  
Vol 56 (1) ◽  
pp. 129-137
Author(s):  
J. E. TREHERNE
Keyword(s):  
Action Potentials ◽  
Sodium Level ◽  
Fat Body ◽  
Sodium Concentration ◽  
Stick Insect ◽  
Rapid Decline ◽  
Carausius Morosus

1. The effects of variation in the sodium concentration of the bathing media on axonal function has been measured in de-sheathed connectives in the presence of the overlying neural fat-body sheath. 2. The response to solutions of the same sodium concentration as the haemolymph (15 mM/1) was found to be essentially similar to that recorded in de-sheathed connectives in the absence of the fat-body sheath, there being a rapid decline in amplitude of the recorded action potentials in both preparations. 3. On the basis of these observations it is concluded that the neural fat-body sheath is unlikely to be involved in the regulation of the extra-neuronal sodium level.

Membrane Potentials in the Central Nervous System of a Phytophagous Insect (Carausius Morosus)

1967 ◽  
Vol 46 (3) ◽  
pp. 413-421
Author(s):  
J. E. TREHERNE ◽  
S. H. P. MADDRELL
Keyword(s):  
Action Potentials ◽  
Fat Body ◽  
Chloride Concentration ◽  
Sodium Concentration ◽  
Stick Insect ◽  
Mean Value ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Glass Capillary ◽  
Positive Potential

1. The nerve cord of the stick insect is surrounded by a fat-body sheath. This sheath encloses an extraneural space and thus interposes an additional fluid compartment between the neural lamella and the haemolymph. The axons in the thoracic connectives were found to be relatively small, the largest ones averaging 7--II µ in diameter. 2. The apparent resting potentials of axons, impaled with glass capillary microelectrodes, were found to be relatively small, averaging only 25.1 mV., with an overshoot of 59.3 mV. in action potentials in intact preparations. In the absence of the neural fat-body sheath the resting potentials were increased to a mean value of 40.3 mV., there being no significant alteration in the total amplitude of the action potentials. This effect appears to result from the interpolation of a positive potential of some 15-20 mV. between the indifferent and recording electrodes. 3. The positive potential was abolished, in intact preparations, when the nerve cords were bathed with solutions of elevated chloride concentration. Positive potentials were also obtained when gradients of chloride ions were maintained across the isolated fatbody sheath. It is suggested that the positive potentials may result from a chloride diffusion potential across the neural fat-body sheath. 4. The results are discussed in relation to the ability of the axons of this species to function in ganglia and connectives bathed with solutions of low sodium concentration.

Calcium Action Potentials in the Skeletal Muscle Fibres of the Stick Insect Carausius Morosus

1981 ◽  
Vol 93 (1) ◽  
pp. 257-267 ◽  
Author(s):  
FRANCES M. ASHCROFT
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Inhibitory Effect ◽  
Stick Insect ◽  
Muscle Fibres ◽  
Carausius Morosus ◽  
Outward Currents ◽  
Ca Antagonist ◽  
Ventral Longitudinal Muscle ◽  
Skeletal Muscle Fibres

The ionic requirements for the generation of action potentials in the ventral longitudinal muscle fibres of the stick insect, Carausius morosus, were investigated. Ca-free Ringer rapidly and reversibly abolished the action potential. In the presence of tetraethylammonium (TEA) ions (to suppress outward currents) the overshoot of the action potential changed 26 mV for a 10-fold change in [Ca]o. The maximum rate of rise of the action potential (measured in TEA Ringer) showed saturation at high [Ca]o. Cobaltous ions (20 mM) and the organic Ca antagonist D 600 (5×10−4g/ml) reversibly inhibited the action potential; the inhibitory effect of 1 mM-La3+ was irreversible. Barium and strontium, but not magnesium, were able to substitute for calcium as charge carriers. These results suggest that an inward movement of Ca2+ underlies the action potential of Carausius fibres.

scholarly journals Vitellogenesis in the stick insect Carausius morosus I. Specific protein synthesis during ovarian development

1980 ◽  
Vol 46 (1) ◽  
pp. 1-16
Author(s):  
F. Giorgi ◽  
F. Macchi
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Protein Synthesis ◽  
Gel Electrophoresis ◽  
Fat Body ◽  
Polyacrylamide Gel Electrophoresis ◽  
Stick Insect ◽  
Polyacrylamide Gel ◽  
Carausius Morosus

Vitellogenesis in the stick insect Carausius morosus (Br.) has been studied with the goal of identifying vitellogenin in various tissues. Following exposure to in vivo to radioactive amino acids, oocytes in the medium size range are labelled with a minimum delay of 6 h after the time of injection. Incorporation of radioactivity under these conditions is shown to depend upon accumulation of proteins rather than on a differential rate of protein synthesis in succeeding stages of oogenesis. By immunochemical analyses, it is shown that at least two antigens are common to both haemolymph and ovary and that one of these is also present in the fat body. Both antigens are labelled during exposure to radioactive amino acids. When analysed by the SDS polyacrylamide gel electrophoresis, extracts from both haemolymph and ovary appear to share a number of protein fractions which range in molecular weight from 40 000 to 200 000 Daltons. The labelling pattern exhibited by these fractions is clearly indicative of a protein transfer from the fat body to the oocyte. Fat body cultured in vivo for up to 4 h releases a major macromolecular complex in the external medium. The latter has been identified as vitellogenin by both immuno-precipitation assay and SDS polyacrylamide gel electrophoresis. The protein which is synthesized and secreted under these conditions results from the processing of a protein complex of higher molecular weight.

scholarly journals A Fat Body-Derived Protein Is Selectively Sulfated during Transit to Ovarian Follicles in the Stick Insect Carausius morosus

1995 ◽  
Vol 167 (1) ◽  
pp. 379-387 ◽  
Author(s):  
Franco Giorgi ◽  
Antonella Cecchettini ◽  
Maria Teresa Locci ◽  
Massimo Masetti ◽  
James T. Bradley
Keyword(s):  
Fat Body ◽  
Ovarian Follicles ◽  
Stick Insect ◽  
Carausius Morosus

Some Preliminary Observations on the Effects of Cations on Conduction Processes in the Abdominal Nerve Cord of the Stick Insect, Carausius Morosus

1965 ◽  
Vol 42 (1) ◽  
pp. 1-6
Author(s):  
J. E. TREHERNE
Keyword(s):  
Electrical Stimulation ◽  
Nerve Conduction ◽  
Nerve Cord ◽  
Action Potentials ◽  
Ionic Composition ◽  
Stick Insect ◽  
Carausius Morosus ◽  
Stimulation Of

1. In the haemolymph of the stick insect Carausius morosus the concentration of potassium exceeds that of sodium and the concentration of magnesium exceeds that of calcium. The implications of this situation for nerve conduction have been studied. 2. Conduction is maintained in intact and desheathed preparations of the fourth adbominal ganglion under irrigation with a solution resembling haemolymph in ionic composition. 3. Action potentials recorded in response to electrical stimulation of the nerve cord decline in sodium-free solutions, both in intact and in desheathed preparations. 4. Conduction declines slowly under irrigation with magnesium-free solutions both in intact and in desheathed preparations.

Vitellogenin is Glycosylated in the Fat Body of the Stick Insect Carausius morosus and Not Further Modified Upon Transfer to the Ovarian Follicle

Micron ◽  
1998 ◽  
Vol 29 (6) ◽  
pp. 451-460 ◽  
Author(s):  
F Giorgi ◽  
A Cecchettini ◽  
A Falleni ◽  
M Masetti ◽  
V Gremigni
Keyword(s):  
Fat Body ◽  
Ovarian Follicle ◽  
Stick Insect ◽  
Carausius Morosus
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