The ultrastructure of the metathoracic femoral extensors of the cockroach,Periplaneta americana

The ultrastructure of the femoral extensors of the metathoracic leg of the cockroach, Periplaneta americana was studied to determine morphological correlations with the known patterns of innervation, physiological properties and biochemical properties. Three different types of muscle fibers were described. Type 1 consisted of short sarcomeres (mean 3.7 μm), few mitochondria and sparse glycogen-like material; Type 2, short sarcomeres (4.2 μm), numerous mitochondria, large amounts of glycogen; Type 3, long sarcomeres (7.5 μm), numerous mitochondria and large amounts of glycogen. A qualitative examination of the sarcoplasmic reticulum (SR) and transverse tubular system (TTS) revealed the density of SR and TTS to be greatest in Type 1 and least in Type 3. There were obvious correlations between the morphological features and the other known characteristics of these muscle fibers. The role of these different muscle fiber types in different locomotory behaviors was discussed. In summary, the three types of muscle fibers are used in three different behaviors: Type 1, rapid walking; Type 2, slow walking; Type 3, postural control.     

The mechanosensory apparatus of the femoral tactile spine of the cockroach,Periplaneta americana

Summary Tactile spines are large cuticular sense organs that appear to provide insects with a sense of touch which is spatially coarse but of great sensitivity. Cockroach legs have a number of these spines on each leg and a particularly prominent spine on the end of each femur, the femoral tactile spine. The ease of recording afferent activity from this spine during mechanical stimulation has made it one of the most thoroughly studied insect mechanoreceptors and yet it has never been examined by electron microscopy.We report here the results of an examination of the femoral tactile spine by both scanning and transmission electron microscopy, as well as by light microscopy. The spine is shown to be innervated by a single sensory bipolar neuron with its soma located in the base of the spine. A canal through the wall of the spine leads to the outside and emerges just above the junction between the base of the spine and its articulating socket membrane. The sensory dendrite of the neuron passes from the soma through this canal and forms a modified ciliary sensory ending with the typical dendritic sheath and dense tubular body that is characteristic of insect mechanosensory cuticular sensilla. The tubular body is embedded in a cuticular terminal plug which closes the exterior end of the canal but appears to be fastened to the spine by a very flexible ring of cuticle. This plug is connected to the socket membrane by a specialized socket attachment which presumably serves to move the plug relative to the wall of the spine during movement of the spine within the socket. The morphology of this sensillum is discussed in terms of the possible ways in which it is stimulated by movements of the spine and also in light of the dynamic behaviour of the receptor which is now very well described.Supported by the Canadian Medical Research Council. The authors gratefully acknowledge the expert technical assistance of Sita Prasad and Rodney Gramlich     

The excretory efficiency of the American cockroach,Periplaneta americana L.

The efficiency of the excretory system of the American cockroach was measured using a dye clearance test. Indigo carmine in aqueous solution was injected into the blood and the rate of its removal was checked by densitometric measurements of blood spots on filter paper strips. The results show that the rate of excretion is significantly changed by changes in temperature and that certain biologically active chemicals inhibit the rate of excretion.     

The mode of action of pyrethnxm on the cockroach, Periplaneta americana L

Pyrethrin, the active principle of pyrethrum powder, is insoluble in water but is soluble in, the body fluid of the cockroach. It has a selective action on nerve ganglia, and the destruction of their cells is responsible for the death of the insect. Whereas pyrethrum, when used -either in the powdered form or in a fluid state mixed with kerosene and introduced directly into the body cavity reaches the ganglion with the circulation, its mode of action when it acts through the spiracles is different. Kerosene-pyrethrum mixture when introduced into the tracheal trunks through the spiracles is quickly diffused into the haemocoele. When the dry powder is inserted into the trachea, its mode of action is analogous to a fluid preparation. As the conversion of pyrethrum from a dry into a fluid state is alone possible in the interior of the trachea, the natural conclusion is that a fluid analogous to the body fluid is present in the same situation. As soon as the pyrethrin is dissolved, it is quickly diffused into the haemocoele and thus reaches the nearest ganglion.     

Alkaline phosphatase activity in the brain of the American cockroach Periplaneta americana L

Summary The supra- and suboesophageal ganglia of the American cockroach contain material which catalyses the alkaline hydrolysis (pH 9.5) of 5-bromo-4-chloro-3-indolyl phosphate in the presence of Nitro blue tetrazolium. Histochemical studies on unfixed cryostat sections indicate that this type of alkaline phosphatase is restricted to discrete regions in the cockroach brain. Highest enzyme activity is encountered in the mushroom bodies, central body, antennal glomeruli and specific parts of some distinct neural connections including the optic nerve, antennal nerve, circumoesophageal connectives and nerves leaving the suboesophageal ganglion. Tissue fixation by use of formaldehyde-type fixatives, as well as routine paraffin-embedding, completely destroy all histochemically detectable enzyme activity.Native polyacrylamide gradient electrophoresis suggests that the alkaline phosphatase activity is present as multiple isozymic forms, which show up in the 120–130 kD range of standard proteins. Enzyme activity becomes undetectable after fixation (trichloroacetic acid, formaldehyde containing fixatives) of electrophoretically separated native proteins, as well as after electrophoresis in denaturing conditions (SDS and -mercapto-ethanol, boiling). However, the enzyme activity remains virtually unaffected after storage of the sample for prolonged periods at –20 to –80°C.     

Classical olfactory conditioning in the cockroach Periplaneta americana

We established a classical conditioning procedure for the cockroach, Periplaneta americana, by which odors were associated with reward or punishment. Cockroaches underwent differential conditioning trials in which peppermint odor was associated with sucrose solution and vanilla odor was associated with saline solution. Odor preference of cockroaches was tested by allowing them to choose between peppermint and vanilla sources. Cockroaches that had undergone one set of differential conditioning trials exhibited a significantly greater preference for peppermint odor than did untrained cockroaches. Memory formed by three sets of differential conditioning trials, with an inter-trial interval of 5 min, was retained at least 4 days after conditioning. This conditioning procedure was effective even for cockroaches that had been harnessed in plastic tubes. This study shows, for the first time in hemimetaborous insects, that both freely moving and harnessed insects are capable of forming olfactory memory by classical conditioning procedure. This procedure may be useful for future electrophysiological and pharmacological studies aimed at elucidation of neural mechanisms underlying olfactory learning and memory.     

Morphology and function of Malpighian tubules and associated structures in the cockroach, Periplaneta americana.

This paper describes the different regions of the Malpighian tubules and the associated structures (ampulla, midgut, ileum) in the cockroach, Periplaneta americana. There are about 150 tubules in each insect. Each tubule consists of at least three parts. The short distal region is thinner than the other parts and is highly contractile. The middle region comprises most of the tubule length and is composed of primary and stellate cells. Primary cells contain numerous refractile mineral concretions, while stellate cells have smaller nuclei, fewer organelles, simpler brush border, and numerous multivesicular bodies. Symbiont protozoa are sometimes present within the lumen of the middle region near where it opens into the proximal region of the tubule. The latter is a short region that drains the tubular fluid into one of the six ampullae. These are contractile diverticula of the intestine located at the midgut-hindgut junction. The ampulla is highly contractile, and consists of a layer of epithelial cells surrounding a cavity that opens into the gut via a narrow slit lined by cells of unusual morphology. The proximal region of the tubule and the ampulla resemble the midgut in that they have similar micromal origin and reabsorptive function for the proximal region of the tubule and for the ampulla. A number of inclusions found within the tubule cells are described, including peroxisomes and modified mitochondria. Current theories of fluid transport are evaluated with regard to physiological and morphological characteristics of Malpighian tubules. The possible role of long narrow channels such as those between microvilli and within basal folds is considered, as is the mechanism by which these structures are formed and maintained. Also discussed is the role of peroxisomes and symbionts in the excretory process.     

Distribution of 5-hydroxytryptamine and indolealkylamine metabolites in the American cockroach, Periplaneta americana L

A procedure is described for simultaneous estimation of tryptophan (TP), 5-hydroxytryptophan (5-OHTP), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), N-acetyl 5-hydroxytryptamine (NA5-HT) and N-acetyldopamine (NADA) using high performance liquid chromatography with coulometric electrochemical detection. The procedure has been used to determine the distribution of these compounds in the central nervous system of the American cockroach, Periplaneta americana. The ratio of TP:5-HT is greatest in the cerebral ganglia (6.5) with lesser ratios evident in the thoracic ganglia (15.5-18.9) and abdominal ganglia (9.6-11.2). Relatively low concentrations of 5-OHTP and NA5-HT were observed in the cerebral ganglia whereas 5-HIAA was not detected. Incubation of ganglia resulted in increased concentrations of NA5-HT. Reserpine reduced levels of 5-HT and NADA whereas probenecid caused a marked reduction in TP and slight elevation of NADA levels. No MAO activity was detected in the central nervous system.     

Multisensory control of escape in the cockroach Periplaneta americana

1. All giant interneurons (GIs) were ablated from the nerve cord of cockroaches by electrocautery, and escape behavior was analyzed with high-speed videography. Animals with ablations retained the ability to produce wind-triggered escape, although response latency was increased (Table 1, Fig. 4). Subsequent lesions suggested that these non-GI responses depended in part on receptors associated with the antennae.
2. Antennal and cereal systems were compared by analyzing escape responses after amputating either cerci or antennae. With standard wind stimuli (high peak velocity) animals responded after either lesion. With lower intensity winds, animals lost their ability to respond after cereal removal (Fig. 6).
3. Removal of antennae did not cause significant changes in behavioral latency, but in the absence of cerci, animals responded at longer latencies than normal (Fig. 7).
4. The cercal-to-GI system can mediate short latency responses to high or low intensity winds, while the antennal system is responsive to high intensity winds only and operates at relatively longer latencies. These conclusions drawn from lesioned animals were confirmed in intact animals with restricted wind targeting the cerci or antennae only (Fig. 9).
5. The antennae do not represent a primary wind-sensory system, but may have a direct mechanosensory role in escape.

     

Glial cells in peripheral nerves of the cockroach, Periplaneta americana

The ultrastructural organization and the junctional complexes of peripheral nerves have been investigated in the cockroach Periplaneta americana. Nerve 5 is surrounded by a layer of connective tissue, the neural lamella, beneath which is a layer of perineurial glial cells wrapping the axons. Adjacent perineurial cells are joined to one another by septate, gap and tight junctions. Septate and gap junctions were observed in freeze-fracture replicas of main trunk nerve 5. Septate junctions were found as rows of PF particles mainly in perineurial cell membranes. Gap junctions exhibited EF macular aggregates in perineurial and subperineurial glial cells. During incubations in vivo with extracellularly applied ionic lanthanum, the lanthanum did not penetrate beyond the perineurium. Where nerve 5 branches and contacts the muscle, lanthanum penetrated freely between the muscle fibres and the nerve branches. In small peripheral branches where the axons are surrounded by single a glial layer, lanthanum is unable to penetrate to the axolemma.     

美洲大蠊粪便粗提物的聚集活性

用不同溶剂不同方法提取美洲大蠊Periplaneta americana(L.)粪便,测定美洲大蠊各虫态的诱集活性。结果表明,采用直接浸泡提取方法,丙酮、乙醇、正己烷和二氯甲烷4种粗提物对美洲大蠊各虫态都具有明显的诱集作用,其中乙醇和丙酮粗提物的引诱效果最好,正己烷次之,二氯甲烷最弱。4种溶剂粗提物对美洲大蠊雄成虫和高龄若虫聚集活性最强,对低龄若虫聚集活性最弱。用乙醇溶剂对粪便粗提,3种提取方法均对美洲大蠊有很强的诱集效果,其中索氏抽提诱集效果最弱,直接浸泡和超声波提取效果好,且差异不显著,但直接浸泡提取效果更好。     

Citrinin interferes with spiracle control in the cockroach, Periplaneta americana

A preparation of citrinin from an isolate of Penicillium citrinum disrupted the spiracle control mechanism of the cockroach, resulting in excessive evaporation of water. The insect rapidly lost body weight and died due to dehydration within 48 h of treatment with citrinin. Presumptive evidence is given here for the neurotoxic nature of the mycotoxin.     

The ocellus of the cockroach,Periplaneta americana (Blattariae)

Summary The ocelli of Periplaneta americana were studied by light and electron microscopy. The view that the ocellus of the cockroach represents a degenerated structure can no longer be supported. All organelles necessary for function are present.The club-shaped retinular cells lie homogeneously distributed in the cupule of the ocellus. Rhabdoms are seen as sickle-, y-, x-or star-shaped structures with up to six cells in formation. Cells were found which had formed two rhabdomeres.The mass of cell organelles lies in the cytoplasm between the cell nucleus and the rhabdom. Smooth endoplasmic reticulum is wound into a spindle formation of considerable size at the origin of the axon in some cells. A cylindrical body in which 10–40 microtubules are packed, as yet unknown in insect retinular cells, is described.The receptory area of the ocellus terminates in a tapetum which contains granules, soluble in alcohol. The axon bundles of the retinular cells run through the tapetum and immediately thereafter make synaptic contact with dendrites of the ocellar nerve cells, while still within the ocellus.The authors are indebted to Mrs. Margaret Weber-Wood for her linguistic assistance     

Modulation by octopamine of olfactory responses to nonpheromone odorants in the cockroach, Periplaneta americana L

Olfactory receptor cells in insects are modulated by neurohormones. Recordings from cockroach olfactory sensilla showed that a subset of sensory neurons increase their responses to selected nonpheromone odorants after octopamine application. With octopamine application, recordings demonstrated increased firing rates by the short but not the long alcohol-sensitive sensilla to the nonpheromone volatile, hexan-1-ol. Within the same sensillum, individual receptor cells are shown to be modulated independently from each other, indicating that the octopamine receptors reside in the receptor not in the accessory cells. A uniform decrease in the amplitude of electroantennogram, which is odorant independent, is suggested to reflect the rise in octopamine concentration in the antennal hemolymph. Perception of general odorants measured as behavioral responses changed qualitatively under octopamine treatment: namely, repulsive hexan-1-ol became neutral, whereas neutral eucalyptol became attractive. Octopamine induced a change in male behavioral responses to general odors that were essentially the same as in the state of sexual arousal. Our findings suggest that sensitivity to odors having different biological significances is modulated selectively at the peripheral as well as other levels of olfactory processing.