Cockroach Leg Research Articles

Form and role of deformation in excitation of an insect mechanoreceptor.

THE proprioceptive campaniform sensilla of insect legs are thought to sense strains developed in the cuticle of the leg in weight bearing and walking. Pringle1 proposed that a ridge in the cuticular cap of the sensillum bulges outward under compressional shear stress, thus stretching and exciting the underlying single bipolar sensory neurone. His main assumption was that the mechanical compliance of the cuticle should differ in at least two subregions of the cap. This hypothesis has been widely accepted and is probably substantially correct, but several essential details have not been tested directly. Until now, the structure of the cap has not been shown clearly in cockroach legs, although it has been in dipterous halteres2,3, and neither the mechanical properties of the cap cuticle nor the magnitude and direction of the excitatory deformation have been measured, although the fine structure of the bipolar neurone4,5 and its responses to punctate stimulation6,7 are known.

EFFECTS OF β-ECDYSONE ON MOLT-LINKED DIFFERENTIATIONIN VITRO

A study of the effects of β-ecdysone on the initiation of cuticle deposition and seta formation by cockroach leg regenerates in vitro showed that both processes are ecdysone-dependent and are initiated by the same threshold dose, but the responses differ qualitatively and quantitatively. The initiation of cuticle deposition depends primarily on the accumulation of hormone-initiated events by the target tissue. The initiation of seta formation has an additional requirement for simultaneous protein synthesis.

The determination of the symmetry properties in the larval legs of cockroaches (blattaria).

The determination of the symmetry properties in the larval legs of cockroaches (blattaria).

The origin of the epidermis in the supernumerary regenerates of triple legs in cockroaches (Blattaria)1

ABSTRACT An attempt has been made to clarify the origin of the supernumerary regenerates of triple legs by transplantations between two species of cockroaches, Gromphadorhina portentosa and Leucophaea maderae. The three ways of combining stump and transplant tissues were: heteropleural, dorso-dorsal, antero-posterior (I); heteropleural, dorso-ventral, anteroanterior (II); homopleural, dorso-ventral, antero-posterior (III). The transplantations have been performed at the level of the tibia as well as at the level of the coxa. (1) The supernumerary regenerates were partly mixed, i.e were composed of a mosaic of the tissues of both species of cockroach, partly homogeneously built up by the tissues of only one of the two species. In combination I nearly all regenerates were mixed; in the other two combinations homogeneous regenerates were relatively numerous, sometimes even the most numerous. Both supernumerary regenerates of a triple leg might be mixed; or one was homogeneous and the second mixed; or they were both homogeneous. In the latter case one regenerate was built up by Gromphadorhina tissues, the other by Leucophaea tissues, or, more rarely, both were built by up Gromphadorhina tissues. (2) The intraspecific transplantations simultaneously done in Leucophaea gave results which correspond in general with the results of the interspecific transplantations. (3) From the composition of the supernumerary regenerates it must be concluded that the four different properties of a cross-section (anterior, posterior, etc.) are not yet determined irreversibly in the tissues of the cockroach legs. Thus, missing properties may be completed by the other properties to give an entire cross-section.

Effects of ecdysterone on the deposition of cockroach cuticle in vitro.

Quantitative studies were made of the stimulation of cuticular deposition in cockroach leg regenerates in vitro by the molting hormone ecdysterone. Preliminary experiments showed that the hormone remained active and that the tissues remained sensitive in vitro for as long as 30 days. Large doses given one week apart resulted in the production of multiple cuticles, but small doses given at shorter intervals gave a single, cumulative response. Time-dosage studies showed that the concentration of the hormone and the length of exposure make roughly equal contributions to the effect of the dose.

Loss of the Sensory Process of an Insect Receptor at Ecdysis

CAMPANIFORM sensilla on cockroach legs are mechanosensitive sense organs associated with the exoskeleton which are thought to help coordinate the animal's walking movements1. Although the fine structure of campaniform sensilla has been elucidated2, little is known about the morphogenetic changes they undergo during moulting. I wish to report initial findings of an electron microscopic investigation of the development of cockroach campaniform sensilla.

Microtubules and sensory transduction.

Cockroach legs bear tactile spines equipped with campaniform sensilla-mechanoreceptors associated with the cuticle-which function by a single bipolar neuron from whose dendrite tip extends a modified cilium packed with 350-1000 parallel cytoplasmic microtubules. These microtubules, which can be chemically disassembled with colchicine and vinblastine, are intimately associated with the site of mechanical stimulation. Treatment of living sensilla with colchicine and vinblastine abolishes their ability to respond to mechanical stimulation 1-2 hr after drug application. Loss of function is accompanied by large-scale disassembly of microtubules in the modified cilium. The experimental evidence strongly suggests that microtubules play an important role in the process of sensory transduction in campaniform sensilla.

The fine structure of cockroach campaniform sensilla.

Campaniform sensilla on cockroach legs provide a good model system for the study of mechanoreceptive sensory transduction. This paper describes the structure of campaniform sensilla on the cockroach tibia as revealed by light- and electron-microscopy. Campaniform sensilla are proprioceptive mechanoreceptors associated with the exoskeleton. The function of each sensillum centers around a single primary sense cell, a large bipolar neuron whose 40 micro-wide cell body is available for electrophysiological investigation with intracellular microelectrodes. Its axon travels to the central nervous system; its dendrite gives rise to a modified cilium which is associated with the cuticle. The tip of the 20 micro-long dendrite contains a basal body, from which arises a 9 + 0 connecting cilium. This cilium passes through a canal in the cuticle, and expands in diameter to become the sensory process, a membrane-limited bundle of 350-1000 parallel microtubules. The tip of the sensory process is firmly attached to a thin cap of exocuticle; mechanical depression of this cap, which probably occurs during walking movements, effectively stimulates the sensillum. The hypothesis is presented that the microtubules of the sensory process play an important role in mechanoelectric transduction in cockroach campaniform sensilla.

The structure and function of a connective chordotonal organ in the cockroach leg

The micromorphology of the tibio-tarsal joint of Periplaneta is described, based on the mesothoracic limb. There are two muscles acting on the joint, numbered 144 and 145. There is a connective chordotonal organ, which branches off from the trunk of N5 proximally and inserts on the intersegmental membrane distally. In addition, a previously undescribed group of campaniform sensilla is reported from the tibiotarsal joint. The tibio-tarsal chordotonal organ subdivides into a main branch and two side branches. It contains 26 bipolar sensory neurons, whose dendrites are associated distally with 14 scolopales. These scolopidia are arranged in three groups which differ in position, fine structure and number of cells per scolopale. There is one group 1 scolopidium in each of the side branches and two proximally in the main branch. Group 2 scolopidia are spread out along the main branch and group 3 scolopidia occur distally in the main branch. Group 1 scolopidia consist of two bipolar neurons, 15 to 20 µm in diameter, whose dendrites, heavily sheathed, insert in a single scolopale. Group 2 scolopidia consist of two bipolar neurons, 8 to 15 µm in diameter, whose dendrites are less well sheathed and insert in a single scolopale. Group 3 scolopidia consist of a single bipolar neuron, about 10 µm in diameter, with a short, poorly sheathed dendrite inserting in a single scolopale. The scolopales of groups 1 and 2 are identical, consisting of the usual pattern of a ring of scolopale rods inserting into a distal cap and enclosing the cilia on the dendrite terminations. In this case, the cap is particularly long and pointed and both the cilia and the scolopale rods penetrate a long way into it. The cilia of the two members of a pair of dendrites are identical but the ciliary roots differ between the two members of a pair. Electrophysiological recordings show that the organ responds to downward and backward deflexion of the tarsus. The response comprises at least two classes of sensory fibre distinguishable both by their size and by their behaviour. The larger fibres show a unidirectional phasic and tonic response to extreme deflexion of the tarsus and are identified with the group 1 scolopidia. The smaller fibres show a unidirectional tonic response to the full range of deflexion of the tarsus and are identified with the group 2 scolopidia. On structural evidence, it is suggested that the differences in adaptation between these two groups of scolopidia is not likely to be caused by differences in mechanical attachment. The combination of electrophysiological and fine structural evidence indicates that in this chordotonal organ the adequate stimulus of the scolopidia is an increase in their longitudinal tension but it is not possible to say which fine structural component responds to strain.

Cockroach leg regeneration: effects of ecdysterone in vitro.

Regenerating epithelial tissue from the cockroach leg forms two cuticular coverings. The first of these consists of a protein-carbohydrate complex that is replaced before molting. The second covering represents the cuticle containing chitin. The deposition of the cuticle can be induced in vitro by adding ecdysterone to the culture medium.

Structural features of muscle fibres in the cockroach leg

Studies of muscle fibres in several leg muscles of the cockroach ( Periplaneta americana) were made with the electron microscope. The pink muscles of the coxa were found to have a thin: thick filament ratio of 3:1 compared with a ratio of 6:1 in most of the other leg muscles. Sarcomere lengths were uniform in some muscles and variable in others. Fibres with reduced sarcoplasmic reticulum and an unusual T-system were found in coxal muscle 135b. The significance of the findings is discussed in relation to contractile properties of arthropod muscle fibres.

Nerve regeneration in the cockroach, Leucophaea maderae: the effect of humoral substances in vitro.

An in vitro system was used to study the effects of diffusible substances from various endocrine tissues on the growth of nerve tissue from regenerating cockroach legs. Incubates prepared from endocrine glands and gland combinations were tested for their effect on regenerative growth from the stump of the fifth mesothoracic nerve of 8-day leg regenerates from late instar nymphs of Leucophaea maderae. Incubates prepared from the prothoracic ganglion produced a stimulatory effect, while the prothoracic gland, allatum-cardiacum complex, and brain showed no effect. When prothoracic gland and prothoracic ganglion incubates were combined, the results were the same as with ganglion incubate alone. When the glands were incubated together and allowed to interact, the nerve growth stimulating effect of the ganglion was reduced by 50%. To explain these findings, it is postulated that a diffusible substance is released by the prothoracic ganglion which stimulates regenerative nerve growth from the leg regenerate. The...

Histochemical detection of several enzymes in Crytomphallus and Blaptica and its relation to neuromuscular transmission

1. 1. Histochemical techniques for the demonstration of glutamate dehydrogenase (GDH), succinate dehydrogenase (SDH), cholinesterases (ChEase) and phosphorylase were performed in the pharyngeal retractor muscle of the snail ( Cryptomphallus) and in the muscles of the cockroach leg ( Blaptica). 2. 2. In the smooth muscle of snail the presence of the four reactions in the sarcolemma and sarcoplasm stands out. 3. 3. In the striated muscle of the cockroach leg a positive reaction for dehydrogenases and cholinesterases is obtained in the sarcolemma and sarcoplasm. 4. 4. The meaning of these results in relation to neuromuscular transmission and findings of electron microscopy is discussed.

Conduction Velocities and Their Temperature Coefficients in Sensory Nerve Fibres of Cockroach Legs*

ABSTRACT The cockroach-leg preparation of Pumphrey (1936) and Pringle & Wilson (1952) lends itself easily to measurements of conduction velocity in afferent nerve fibres from many of the larger mechanoreceptive sensilla of the leg. Conduction velocity is a quantity that can be measured quite precisely, and it has an important bearing on several open problems involving sensory mechanisms in insects, as well as in cellular neurophysiology more generally. One group of problems relates to the sensory transfer functions for tactile spine mechanoreceptors of Periplaneta, determined by Pringle & Wilson (1952) and Chapman & Smith (1963). Sensory transfer functions are quantitative expressions of the stimulus-response relationship, which describe some aspects of the temporal sensory code used in information transmission, and which provide useful insight in identifying component transducer mechanisms in the sensory ending. Conduction velocity is important in this context because it contributes quantitatively to the sensory code, and because it generates a quantifiable experimental artifact in the analysis of transducer mechanisms. In the present work these effects are evaluated and are shown to be small but not negligible.

Proprioceptive leg reflexes in cockroaches.

ABSTRACT Proprioceptive feedback from the moving wings of locusts contains information which could be sufficient for the control of the timing of the wing-muscle contractions. It has been found, however, that at the high frequency of limb movement used in flight this phasic information content is lost in the ganglionic transfer (Wilson & Gettrup, 1963). During rapid running the legs of cockroaches also oscillate at high frequencies, sometimes as rapidly as wing movements of similar-sized animals. It is therefore necessary to know whether the frequency response capabilities of the leg reflexes are similar to or different from those of the wings in order to understand how the legs are coordinated. If the leg reflexes are limited to the same range as that available to the wing reflexes, then coordination of the legs would necessarily depend upon ganglionic phasing mechanisms ; that is, the elementary pattern of leg movements could be due to central nervous control alone, as is true of the locust wing control (Wilson, 1961). However, it can be shown that the phasic leg reflexes are capable of operation at frequencies even greater than those encountered in running. Apparently the significant limitation on rate of leg movement is not nervous but mechanical; that is, due to the maximum rate of contraction of the muscles.

The effect of acetylcholine, glutamic acid and GABA on the contractions of the perfused cockroach leg

1. 1. The perfused cockroach leg preparation is described. 2. 2. The leg gives an increased contraction to the addition of acetylcholine (5 × 10 −6); l-glutamic acid (10 −7); d-glutamic acid (10 −6); l-aspartic acid (10 −3). The figures in brackets are the threshold values in g/ml. 3. 3. Increased amounts of acetylcholine, glutamic acid or aspartic acid bring about greater and longer lasting contractions. 4. 4. Addition of 5-HT has little effect, though higher concentrations (10 −3 g/ml) can cause a slight inhibition of the contraction. 5. 5. GABA has a marked inhibition on the contraction; the threshold concentration being 5×10 −6 g/ml. Higher concentrations bring about more marked and longer lasting inhibition. The effect is quickly reversible. 6. 6. GABA has little inhibitory effect on contractions induced by acetyklcholine but it will easily inhibit contractions caused by glutamic acid.

An investigation into the mode of action of the subgenual organ in the termite, Zootermopsis angusticollis Emerson, and in the cockroach, Periplaneta americana L.

Action potentials deriving from the tibial subgenual organ have been recorded from the cockroach leg and termite nerve cord preparations. In both insects the response to a vibrational stimulus had a latency of 10–20 msec and died out after about the first half sec. Synchronous non-adapting responses were obtained to pulses of vibration of a pulse rate of up to 50/sec for the cockroach and 3/sec for the termite. In the cockroach, synchronous non-adapting responses were obtained to substratum vibration of certain low frequencies. Threshold sensitivities to vibration determined by electrophysiological means and by a study of behaviour are compared for the termite. Taking into consideration the structure of the subgenual organ, a theory is proposed that could explain the mode of action of the organ. It is suggested that the two kinds of cell in the organ, which are differently disposed, will be set into transient oscillation following their displacement from steady-state conditions. The natural frequencies of the two kinds of cell will be different, and for the short time that the transient vibrations last rapidly changing forces will act about the junctions of the two kinds of cell, and these forces could initiate nervous discharge. The responses recorded from the cockroach subgenual organ show many similarities with the responses recorded from insect tympanal organs. The mode of action of the insect tympanal organ is discussed in this light.

Regenerating Tissues from the Cockroach Leg: A System for Studying in vitro

Regenerating leg tissue of Leucophaea maderae shows considerable activity in vitro. Migrations of ameboid and fiber-like cells from the explant take place, vesicles are produced, and interaction occurs between tissues. The system described facilitates the study of these activities in vitro.

Slow and Fast Responses in Cockroach Leg Muscle

ABSTRACT Intracellular recording from individual muscle fibres of the flexor tibiae of the cockroach shows two types of action potentials. One of these represents fast fibre activity, while the other represents slow fibre activity in this muscle. The fast response consists of an all-or-none potential varying from 40 to 85 mV., with 60% of the responses between 55 and 70 mV. This potential has an overshoot over the resting potential, and is followed by an absolute and a relative refractory period. For these reasons it is considered likely that the potential is a propagated one. The slow response is a small, facilitating potential, varying from 8 to 20 mV., and is quite likely a local phenomenon. All the evidence indicates that the two types of activity do not take place in the same muscle fibres, but rather represent the responses of two different types of fibres, as is the case in some amphibian muscles. Gradation of activity in the fast system seems to depend solely on the activation of a very small number of motor units and on mechanical summation. The response of this system shows little, if any, facilitation as the frequency of stimulation is increased. The facilitating slow system may be concerned with slower, more finely graded movements. The resting potential in roach muscle has an amplitude of 45 ± 9 mV., which falls within the range expected on the basis of the intracellular and extracellular potassium concentrations. Slow and fast fibre activity in insects and Crustacea is discussed, and a revision of the earlier work on Crustacea with the use of intracellular recording is suggested.

The effect of DDT on sensory and motor structures in the cockroach leg

Journal of Cellular and Comparative PhysiologyVolume 32, Issue 2 p. 175-186 Article The effect of DDT on sensory and motor structures in the cockroach leg† Kenneth D. Roeder, Kenneth D. Roeder Department of Biology, Tufts College, Medford, MassachusettsSearch for more papers by this authorElizabeth A. Weiant, Elizabeth A. Weiant Department of Biology, Tufts College, Medford, MassachusettsSearch for more papers by this author Kenneth D. Roeder, Kenneth D. Roeder Department of Biology, Tufts College, Medford, MassachusettsSearch for more papers by this authorElizabeth A. Weiant, Elizabeth A. Weiant Department of Biology, Tufts College, Medford, MassachusettsSearch for more papers by this author First published: October 1948 https://doi.org/10.1002/jcp.1030320206Citations: 55 † The work described in this paper was done under contract between the Medical Division, Chemical Corps U. S. Army and Tufts College. Under the terms of this contract the Chemical Corps neither restricts nor is responsible for the opinions or conclusions of the authors. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume32, Issue2October 1948Pages 175-186 RelatedInformation