Effect of CO2 on neurons of the house cricket, Acheta domestica

The effect of elevated levels of CO2 on the neurons of the metathoracic ganglion of the common house cricket was examined. Elevated CO2 produced a profound depolarization of the neurons without a substantial change in conductance. The depolarization was not due to CO2 acidification of the external solution since exposure of the neurons to a solution which was nominally CO2 free, but at an acid pH, produced little effect. The effect of elevated CO2 appeared to be due to intracellular acidification, since other treatments which acidified the cell interior also produced depolarization. Agents which block intracellular pH regulation also substantially enhance the effect and prevent recovery. The mechanism producing the depolarization appears to be blockage of a metabolic component of the resting potential, since the action of metabolic blockers mimics the effect of elevated CO2.     

The morphofunctional condition of the basic organ systems, life span and fecundity of the domestic cricket, Acheta domestica, during normal imaginal development and following allatectomy]

3 main periods of imaginal development: juvenility, reproduction, ageing, were established in Acheta domestica and characterized by morphological and functional features of some organs (integument, wings, fat body, wing muscles, ovaries, and body proportions). Allatectomized crickets remain in the first period up till the day of death; this allowed to suggest that the hormone of corpora allata in imago controls the normal correlated development of different organs and tissues and ensures the transition to subsequent periods of imaginal ontogenesis. In allatectomized crickets of both the sexes, the duration of imaginal life is markedly longer and the fecundity of females is much lower. It is suggested that the hormone of corpora allata controls the life span and the fecundity independently.     

Serotonin-immunoreactive and dopamine-immunoreactive neurones in the terminal ganglion of the cricket,Acheta domestica: Light- and electron-microscopic immunocytochemistry

Summary The distribution and ultrastructure of serotonin- and dopamine-immunoreactive (5-HTi and DAi) neurones have been investigated in the terminal ganglion of the cricket, Acheta domestica, using a pre-embedding chopper technique. Special attention has been paid to the immunoreactive structures in the neuropil. 5-HTi structures are extensively distributed and densely packed throughout the 5 neuromeres of the terminal ganglion and originate from several interneurones and efferent neurones. In contrast, DAi fibres are distributed sparsely although they extend to all neuromeres of the ganglion and originate from 6 interneurons only. For both 5-HTi and DAi neurones characteristic axonal projections and branching patterns can be distinguished. The 5-HTi axons exhibit rich varicose arborizations, whereas DAi neurones possess fewer varicosities in the neuropil. Electron microscopy shows that 5-HTi varicosities contain small ( 60 nm) and large ( 100 nm) agranular vesicles, and large ( 100 nm) granular vesicles, whereas in DAi varicosities small ( 60 nm) agranular and large ( 100 nm) granular vesicles are seen. Both 5-HTi and DAi varicosities form synaptic contacts. We conclude that both serotonin and dopamine may be used as neurotransmitters in the terminal ganglion of the cricket.Fellow of the Alexander von Humboldt-Stiftung     

Effect of benserazid and allatectomy on the development and structure of the ovariole in the house cricket, Acheta domestica L

Light and electron microscopic investigations were carried out on the fourth day imago of the house cricket, Acheta domestica L. treated with benserazid, or allatectomized. Introduction of benserazid (daily on the 1st, 2nd and 3rd days of imaginal life in 0.1 mg/g) failed to influence the development of the oocytes. However, benserazid in the concentration of 0.2 mg/g inhibited the growth of the terminal oocytes, while in 0.6 mg/g it completely blocked the development of terminal oocytes and vitellogenesis. The effect of benserazid proved to be reversible. Application of juvenile hormone analogue (ZR-515) prevented the effect of benserazid on the gonads of the crickets. Ultrastructural damages of the oocytes and follicular epithelium were the same in case of benserazid treatment and allatectomy, although the changes were more expressed in the latter case. The benserazid effect was found to be indirect, caused by damage to the interaction between the aminergic and peptidergic systems of the brain.     

Changes in basic chromosomal proteins during spermatogenesis in the mature rat.

Nuclei of the seminiferous epithelial cells of rat testis were filtered through glass wool to remove sperm heads, flagellae and late-stage spermatids and then centrifuged through sucrose gradients to yield three fractions. The cellular origins of the predominant nuclei in these fractions were identified through the kinetics of labeling with [³H]thymidine. The relative amounts of the different histone fractions changed during the various stages of spermatogenesis in an interesting and systematic manner. For example, the ratio of the trailing (acetylated) to the leading member of the histone F2a1 doublet was greater in spermatid nuclei than in nuclei of a fraction enriched in primary spermatocytes. Similarly, the ratio $\text{X}{}_1\text{F}\text{1}$ was greatest in spermatid nuclei. On the other hand, the ratio $\text{X}{}_3\text{F}\text{2b}$ was greater in the nuclei of pachytene-diplotene primary spermatocytes than in the fraction enriched in nuclei of spermatogonia and preloptotene primary spermatocytes.A basic protein fraction with some of the properties of a protamine was extracted from rat sperm heads and from the nuclei of spermatids. This protein fraction has high contents of arginine and cysteine (after reduction), and it appears to be identical with the protamine described by Kistler et al. In addition, a new protamine was isolated from rat sperm heads which has high arginine content but appears to be devoid of lysine and cyst(e)ine. Two other basic protein fractions with high electrophoretic mobilities were extracted with acid from the nuclei of testicular seminiferous epithetial cells without prior reduction. One of these proteins may be identical with the testis-specific protein of Kistler et al.     

The efferent innervation of the genital chamber by an identified serotonergic neuron in the female cricket Acheta domestica

Summary The serotonergic innervation of the genital chamber of the female cricket, Acheta domestica, has been investigated applying anti-serotonin (5-HT) immunocyto-chemistry at both light- and electron-microscopic levels as well as using conventional electron microscopy. Whole mount and pre-embedding chopper techniques of immuno-cytochemistry reveal a dense 5-HT-immunoreactive network of varicose fibers in the musculature of the genital chamber. All of these immunoreactive fibers originate from the efferent serotonergic neuron projecting through the nerve 8v to the genital chamber (Hustert and Topel 1986; Elekes et al. 1987). At the electron-microscopic level, 5-HT-immunoreactive nerve terminals, which contain small (50–60 nm) and large ( 100 nm) agranular vesicles as well as granular vesicles (100nm), contact the muscle fibers or the sarcoplasmic processes without establishing specialized neuromuscular connections. In addition to the 5-HT-immunoreactive axons, two types of immunonegative axons can also be found in the musculature. By use of conventional electron microscopy, three ultrastructurally distinct types of axon processes can be observed, one of which resembles 5-HT-immunoreactive axons. While the majority of the varicosities do not synapse on the muscle fibers, terminals containing small (50–60 nm) agranular vesicles occasionally form specialized neuromuscular contacts. It is suggested that the 5-HTergic innervation plays a non-synaptic modulatory role in the regulation circular musculature in the genital chamber of the cricket, while the musculature as a whole may be influenced by both synaptic and modulatory mechanisms.Fellow of the Alexander von Humboldt-Stiftung     

Role of juvenile hormone metabolism during embryogenesis of the house cricket,Acheta domesticus

The duration of embryogenesis was 9.5 days for house crickets, Acheta domesticus (L.), reared at 35°C. The major route of juvenile hormone (JH) metabolism was ester hydrolysis. The level of α-naphthyl acetate (α-NA) esterase activity per mg wet weight remained relatively constant throughout embryogenesis and was similar to that of eggs dissected from the oviducts. JH esterase activity per mg wet weight was highest in the dissected and day-1 eggs, declined to one-third of this peak activity by day 5, and then remained unchanged through hatching. Two populations of esterases (130,000 and > 200,000 in molecular weight) which metabolized JH and α-NA were resolved in day-1 eggs by gel filtration chromatography. Specific JH esterase appeared by day 4 with a molecular weight of 200,000. Correlative evidence is presented from other insect species that supports a functional role for JH metabolism during embryo development.     

Cyclic nucleotide phosphodiesterases in the cricket, Acheta domesticus.

Exceptionally high levels of guanosine 3'-5'-cyclic monophosphate (cyclic GMP) in the accessory reproductive gland of the male house cricket, Acheta domesticus, led to an investigation of cyclic nucleotide phosphodiesterase (EC 3.1.4.--) as a possible regulatory enzyme. Cricket cyclic nucleotide phosphodiesterase activity with cyclic GMP or cyclic AMP as substrate had a pH optimum around 9.0, required Mg2+ or Mn2+ for maximal activity, and was inhibited by EDTA and methylxanthines. Cyclic GMP phosphodiesterase occurred mainly in the soluble fraction of homogenates of accessory glands or whole crickets, but cyclic AMP phosphodiesterase in the accessory gland was primarily particulate. Kinetic analysis indicated three forms of cyclic GMP phosphodiesterase, with Km values at 2.9 muM, 71 muM and 1.5 mM. Chromatography of whole cricket or accessory gland extracts on DEAE cellulose gave an initial peak having comparable activity with either cyclic GMP or cyclic AMP, and a second peak specific for cyclic AMP. There were no appreciable changes in the specific activity or kinetic properties of accessory gland cyclic GMP phosphodiesterase during a developmental period over which cyclic GMP levels rise more than 500-fold. Thus, the accumulation of cyclic GMP in the accessory gland is probably not associated with concomitant developmental modulation of phosphodiesterase activity.     

The role of cercal sensory feedback during spermatophore transfer in the cricket, Acheta domesticus

The role of the cerci in the spermatophore transfer behavior of the cricket Acheta domesticus was examined. During transfer, the male cerci were held close to the female abdomen where they produced small flicking movements. Male cercal ablation significantly decreased mating success by reducing both the ability of the male to hook the epiphallus on to the female subgenital plate and to transfer the spermatophore. During spermatophore transfer, the male must thread the spermatophore tube into the female genital papilla and attach the spermatophore, via its attachment plate, to the base of the ovipositor. Extracellular recordings from the male genital nerve revealed that a centrally driven, rhythmic bursting activity of genital efferents produced the rhythmic contractions of the five pairs of genital muscles responsible for spermatophore threading. Tactile stimulation of campaniform sensilla on the medial aspect of each cercus inhibited the activity of those motor units responsible for advancing the spermatophore tube during threading, while simultaneously activating the motor units responsible for adjusting the position of the epiphallus. We conclude that mechanosensory neurons on the cerci of the male cricket supply important information on female position to the motor program responsible for spermatophore threading and transfer.     

Effect of benserazid and 6-hydroxydopamine on the development of the last larval instar of the house cricket, Acheta domestica L

The effect of benserazid and 6-OHDA on the duration of the last larval instar and development of wings with intact corpora allata and following allatectomy on Acheta domestica L. was studied. 6-OHDA failed to alter the duration of the last larval instar in the nymphs with intact corpora allata but prolonged it in the allatectomized crickets. Introduction of 6-OHDA in the second phase of the last larval instar caused a deformation of the wings both in allatectomized and intact crickets. Injection of benserazid to the nymphs of the last larval instar prolonged the duration of this phase only in the presence of the corpora allata. The effect of benserazid can be connected to elimination of central inhibition of the corpora allata involving dopaminergic neurons of the brain.     

Fate of neuroblast progeny during postembryonic development of mushroom bodies in the house cricket,Acheta domesticus

Mushroom bodies represent the main sensory integrative center of the insect brain and probably play a major role in the adaptation of behavioral responses to the environment. Taking into account the continuous neurogenesis of cricket mushroom bodies, we investigated ontogenesis of this brain structure. Using BrdU labeling, we examined the fate of neuroblast progeny during the postembryonic development. Preimaginal Kenyon cells survived throughout larval and imaginal moults and persisted during adulthood. Our results indicate that the location of labelled Kenyon cells in the cortex of the adult cricket mainly depends upon the period when they were produced during development. The present data demonstrate that cricket mushroom bodies grow from the inside out and that, at any developmental stage, the center of the cortex contains the youngest Kenyon cells. This study also allowed us to observe the occurrence of quiescent neuroblasts. Kenyon cell death during postembryonic and adult life seems to be reduced. Although preimaginal Kenyon cells largely contribute to adult mushroom body structure, a permanent remodeling of the mushroom body occurs throughout the whole insect life due to the persistence of neurogenesis in the house cricket. Further studies are needed to understand the functional significance of these findings.     

The energetic costs of fighting in the house cricket, Acheta domesticus L

The cost of performing an agonistic behavior, or tactic, willhave consequences for an individual's rate of cost accrual,the tactic's evolutionary stability if used as an assessmentsignal, and its pattern of use in the behavioral choreographyof a contest. Few studies have attempted to quantify the costsof fighting, particularly with regard to energy expenditure.Flow-through respirometry revealed that house cricket malescan expend energy at relatively high rates when fighting (morethan eight times resting levels) depending on the particulartactic performed. Acoustic signalling (stridulation) constitutedthe least costly of seven measured agonistic tactics, whilewrestling with an opponent, the most energetically costly tactic,consumed oxygen at a net rate more than 40 times that of stridulation.Low-cost tactics are used by opponents more frequently thanmore costly tactics, providing evidence for an escalating tacticalconvention based on energetic costs. The moderate energeticcost of some tactics suggests they may function as reliablesignals in the assessment of wrestling ability. Net energy costsper contest increased linearly with contest duration for bothcontest winners and losers, but winners tended to expend moreenergy per contest than losers. The likely fitness effects ofenergy expended while fighting are discussed. The results ofthis study indicate that energy expenditure is an importantcost shaping contest strategies in Acheta domesticus     

The afferent projection of mesothoracic bristle hairs in the cricket,Acheta domesticus

Summary One of the sensory systems of the thoracic segments of the cricket,Acheta domesticus, was investigated by using cobalt to stain the axonal arborizations of bristles of various types and locations. The results demonstrate that a variety of hair-like receptors project to the ventral areas of thoracic neuropil previously called ventral association center (VAC) and ventralmost ventral association center (vVAC). Bristles located on the dorsal thorax or wings arborize in or near VAC, while those on the ventral thorax and legs arborize in vVAC. Within the area of neuropil occupied by thoracic bristle afferents, the axonal arborizations are distributed according to the position of the parent receptor at the body surface; thus, medial afferents arborize medially and lateral ones more laterally. For leg afferents, the location of the axonal arborization is also correlated with the various leg segments of origin of the parent receptor and its circumferential location on that segment (Fig. 9).Abbreviations vVAC ventralmost ventral association center - VAC ventral association center     

Fatty acid and lipid analysis of the house cricket,Acheta domesticus

The fatty acid content and composition of the house cricket Acheta domesticus have been investigated in entire insects at different developmental stages and in selected organs of male and female adults. We have also determined the fatty acid composition of the various lipid classes within extracts of the organs of adult female insects. Fatty acids were analysed by capillary gas chromatography or mass spectrometry as their methyl esters (FAMEs) after direct transesterification of insect material or separated lipid classes.The major esterified fatty acids in all extracts were palmitate (C_16:0), stearate (C_18:0), oleate (C_18:1) and linoleate (C_18:2). Levels of esterified fatty acid varied considerably between organs but the fatty acid compositions showed only small variations. The levels of polyunsaturated fatty acids of the C₁₈ series were considerably higher in phospholipid fractions than in other lipid classes. Triacylglycerols formed the major lipid class in ovaries, fat-body and newly-laid eggs, whereas diacylglycerols and phospholipid predominate in the haemolymph. Triacylglycerols, phospholipids, diacylglycerols and free fatty acids were all found in significant amounts in the gut tissue.     

Enzymatic patterns in the embryonic development of the cricket,Acheta domesticus L.

Summary The activity of the enzymes G6PDH, 6PGDH, GAPDH, LDH, CS, MDH, NADP-linked ICDH, GOT, GPT, and GLDH was tested in different stages of developing eggs and in just hatched larvae of crickets. A malic synthase could not be found. The enzymatic pattern changes considerably during this period. Considering this pattern, and especially the quotient (GAPDH)/CS, it seems justified to state that, up to the formation of the germ band, the energy is derived mainly from oxidation of glucose in the citric acid cycle. Later on, lipids substitute partly for glucose. Anaerobic energy production seems to be limited to the stage of the dorsal closure. By inhibiting the formation of the germ band, the activity of GAPDH, and CS is not changed significantly. The rise in activity of G6PDH is correlated with the increased rate of r-RNA synthesis. The increase of activity of MDH and NADP-linked ICDH corresponds to the differentiation of the germ band. These enzymes, together with GOT, GPT, and GLDH should be involved in the synthesis of amino acids from carbohydrates during the later part of development. In the hatched larvae the activity of all enzymes has risen considerably. This stage is characterized by the fact that G6PDH, 6PGDH, GAPDH, LDH, CS, and NADP-linked ICDH display the same activity.This work was supported by the Stiftung für Krebs- und Scharlachforschung (Strebelstiftung).     

Neuronal pathways from the dorsal acelli of the house cricket,Acheta domesticus

Each ocellar nerve in the house cricket Acheta domesticus contains giant nerve fibers of 10-15 μ diameter, characterized in Golgi Cox preparations by a single row of short collaterals which runs along nearly the entire length of a fiber. Numerous long collaterals are given off by thin fibers in the ocellar nerve; medium-size fibers give off relatively few collaterals. The lateral ocellar tracts extend posteriorly through the dorsal protocerebrum, crossing the protocerebral bridge dorsally. The smaller median ocellar tract runs more ventrally through the pars intercerebralis; posterior to the bridge its fibers turn out toward the lateral nerves. Golgi and cobalt preparations reveal branching of giant and mediu_-size ocellar fibers posterior to the bridge at two levels, forming bilateral regions of ocellar neuropile. No ocellar processes appear to be given off to the corpora pedunculata, centra! body, nervi corporis cardiaci, antenna! lobes, or circumesophageal connectives; it is uncertain whether ocellar collaterals extend into the protocerebral bridge or optic lobes. Cell bodies of giant and medium-sized fibers are located in the pars intercerebralis.     

Regional variation in cuticular hydrocarbon composition in the common house cricket,Acheta domesticus

• 1.1. The hydrocarbon composition of different cuticular regions (pronotum, legs, abdominal tergites and sternites, pleural membrane) was determined for adult female crickets (Acheta domesticus).
• 2.2. Hydrocarbon groups included n-alkanes, 2-methylalkanes, long-chain internally branched monomethyl- and dimethyalkanes, n-alkenes, 2-methylalkenes and alkadienes.
• 3.3. Saturated hydrocarbons were more abundant than unsaturated hydrocarbons and branched saturates more abundant than n-alkanes in all regions of the cuticle examined.
• 4.4. Except for a higher percentage of n-alkanes in the pleural membrane (soft cuticle), little difference was noted in compositional patterns or relative amounts of individual molecules from the different cuticular regions.