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Insects' thermoregulatory processes depend on thermosensation and further processing of thermal information in the nervous system. It is commonly known that thermosensation involves thermoreceptors, including members of the TRP receptor family, but the involvement of neurotransmitters in thermoregulatory pathways remains unstudied. We conducted test to determine whether octopamine, a biogenic amine that acts as a neurotransmitter and neurohormone in insects, is involved in TRP-induced thermoregulatory responses in Periplaneta americana. We used capsaicin, an activator of the heat-sensitive TRP channel, Painless, to induce thermoregulatory response in cockroaches. Then, we evaluated the behavioural (thermal preferences and grooming), physiological (heart rate) and biochemical responses of insects to capsaicin, octopamine and phentolamine - octopaminergic receptor blocker. Capsaicin, similar to octopamine, increased cockroaches' grooming activity and heart rate. Moreover, octopamine level and protein kinase A (PKA) activity significantly increased after capsaicin treatment. Blocking octopaminergic receptors with phentolamine diminished cockroaches' response to capsaicin - thermoregulatory behaviour, grooming and heart rate were abolished. The results indicate that octopamine is a neurotransmitter secreted in insects after the activation of heat receptors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Of the nine genes of the American cockroach, Periplaneta americana, coding for peptides related to insulin and insulin-like growth factor, seven show significant expression in the central nervous system as demonstrated by the polymerase chain reaction on reverse transcribed RNA. In situ hybridisation shows that five of those are expressed by cells in the pars intercerebralis. Antisera raised to the predicted peptides show that these cells are neuroendocrine in nature and project to the corpora cardiaca. Interestingly, there are at least three cell types that each express different genes. This contrasts with Drosophila where a single cell type expresses a number of genes expressing several such peptides. Whereas in Drosophila the neuroendocrine cells producing insulin-like peptides also express sulfakinins, the arthropod orthologs of gastrin and cholecystokinin, in Periplaneta the sulfakinins are produced by different cells. Other neuropeptides known to be produced by the pars intercerebralis in Periplaneta and other insect species, such as the CRF-like diuretic hormone, neuroparsin, leucokinin or myosuppressin, neither colocalize with an insulin-related peptide. The separate cellular localization of these peptides and the existence of multiple insulin receptors in this species implies a more complex regulation by insulin and IGF-related peptides in cockroaches than in the fruit fly., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Although the baculovirus expression vector system (BEVS) is widely used in the production of recombinant proteins, only a few lepidopteran insect cell lines have been successfully used so far. This study aimed at evaluating the characteristics of an embryonic cell line from the American cockroach Periplaneta americana L., RIRI-PA1, and determining whether it could be used in recombinant protein expression. Wild type Autographa californica multiple nucleopolyhedrovirus (AcMNPV-wt) and green fluorescent protein (GFP)-replicating recombinant baculoviruses (AcMNPV-GFP) were used to infect RIRI-PA1 respectively, demonstrating that RIRI-PA1 cells could be infected by AcMNPV and express recombinant proteins. Within 24 h of infection with AcMNPV-GFP, the GFP expression was higher than that in Sf21 cells. Furthermore, the infection of RIRI-PA1 cells increased gradually (multiplicity of infection, 10) within 24 h, while in Sf21 cells, the infection only began to increase within 48 h. However, after exposure for 96-168 h, the virus progeny and recombinant protein production of RIRI-PA1 cells was lower than those of Sf21 cells. Western blotting revealed that RIRI-PA1 cells could express recombinant GFP, and the protein expression level positively correlated with the multiplicity of infection. In conclusion, this is the first report that a cell line from P. americana has shown susceptibility to infection from a baculovirus and likewise express recombinant protein. Although the yield of recombinant GFP was not as high as that of Sf21 cells, the results nonetheless showed that RIRI-PA1 had an infection rate advantage in the short term (within 24 h of infection), which is of great value for further development and utilization., (© 2022. The Society for In Vitro Biology.)

For the cockroach species Leucophaea maderae and Periplaneta americana two major juvenile hormone (JH)-binding proteins have been identified: lipophorin (Lp) and vitellogenin (Vg). Each of these macromolecules binds JH with an approximate affinity of K(d) of 10 nM. In Leucophaea the concentration of Lp is augmented by JH during vitellogenesis at the same time when Vg is induced de novo. The circulating levels of each of Lp and Vg at mid-vitellogenesis are in the 10 microM range. Similar values have been determined for Periplaneta. Total JH concentrations (bound and free) can be as high as micromolar in Leucophaea. However, because of the large quantities of the two major JH-binding proteins and their high affinity for JH, we can assume that the amount of free (unbound) JH in circulation is extremely low (the actual values are not know). The JH esterases (JHEs) of the hemolymph in both cockroach species have been isolated by anion exchange chromatography. The JHEs of Leucophaea bound to the anion exchange resin more tightly than the JHE of Periplaneta. The V(max) of the Leucophaea esterases fluctuated by a factor of 2 to 3 during vitellogenesis. The K(m) values for the two distinct esterases of Leucophaea were similar (about 0.15x10(-6) M). On the other hand, k(cat) of the JHEs for Leucophaea at ovulation time was two to three times higher than earlier during vitellogenesis, i.e. 23.30 min(-l) compared to 6.20 min(-1). The JHE of Leucophaea is shown to bind JH III with high affinity: K(d)=3x10(-9) M. However, since there are only very small amounts of JH available for degradation (due to the binding to Lp and Vg), the quantitative removal of JH from circulation, and this includes the release of bound JH, is indeed slow, with a measured half-life of 6-8 h. Classical kinetic assumptions are not met in conditions where the enzyme concentrations exceed by far that of the available substrate. Nonetheless, we attempted to determine the initial velocity of JH hydrolysis under natural conditions, i.e. for undiluted hemolymph, by measuring the initial velocities of JH hydrolysis in serially diluted hemolymph and extrapolating to zero dilution. For in vivo conditions we estimated an initial velocity of JH hydrolysis of <0.1 fmol microl hemolymph(-1) min(-1), i.e. four to five orders of magnitude lower than that measured at substrate saturation in vitro.

Proctolinlike immunoreactivity was mapped in the central nervous system of the cockroach, Periplaneta americana, by using whole-ganglion immunoreacted preparations. The procedure for this immunohistochemical staining of whole-mounts is described. Immunoreactivity was confined to neuronal cell bodies and and processes. These were found in all ganglia of the CNS. The cells varied in the consistency and intensity of their staining. The occurrence and variability of staining is described in detail. Cell bodies were found in the dorsal, ventral, and lateral regions of the ganglia. The highest number of cell bodies was found in the terminal ganglion and the lowest number in the cerebral ganglion. Those in the cerebral ganglion occurred mainly in the tritocerebral lobes. The distribution of immunoreactive cell bodies correlated with results previously obtained by radioimmunoassay. Immunoreactive processes were detected in all interganglionic connectives and many ganglionic nerve roots. Dense ramifications of immunoreactive processes and variocosities were detected in many of the ganglia. The widespread presence of immunoreactivity suggests that proctolin has diverse central and peripheral functions. The mapping immunoreactive neuronal somata provides a valuable step in the identification of putative proctolin-containing neurons suitable for further biochemical, anatomical, and physiological analysis.

Males of the American cockroach, Periplaneta americana, received an injection of 32P-orthophosphates and the specific activity of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) was determined after 120 min of in vivo incorporation. If the insects were forced to fly for 10 min immediately before the end of the experiment, the specific activity (S.A.) of PC and PE was lowered by 34.3 and 31.0%, respectively, that of PI by 17.5%. If the animals were allowed to rest for 10 min after cessation of flight, the S.A. of PC and PE did not differ significantly from the controls, whereas that of PI rose by 91.0% above the control value. These effects cannot be due to changes in precursor labelling (glycerophosphate and phosphoarginine were measured) and reflect changes in the rate of phospholipid biosynthesis. The possibility is discussed that mechanisms regulating the rate of phospholipid biosynthesis are involved.

The pharmacology of a gamma-aminobutyric acid (GABA) receptor on the cell body of an identified motor neuron of the cockroach (Periplaneta americana) was investigated by current-clamp and voltage-clamp methods. Iontophoretic application of GABA increased membrane conductance to chloride ions, and prolonged application resulted in desensitization. Hill coefficients, determined from dose-response data, indicated that binding of at least two GABA molecules was required to activate the chloride channel. Differences between vertebrate GABAA receptors and insect neuronal GABA receptors were detected. For the GABA receptor of motor neuron Df, the following rank order of potency was observed: isoguvacine greater than muscimol greater than or equal to GABA greater than 3-aminopropanesulphonic acid. The GABAB receptor agonist baclofen was inactive. Of the potent vertebrate GABA receptor antagonists (bicuculline, pitrazepin, RU5135 and picrotoxin), only picrotoxin (10(-7) M) produced a potent, reversible block of the response to GABA of motor neuron Df. Both picrotoxinin and picrotin also blocked GABA-induced currents. Bicuculline hydrochloride (10(-4) M) and bicuculline methiodide (10(-4) M) were both ineffective when applied at resting membrane potential (-65 mV), although at hyperpolarized levels partial block of GABA-induced current was sometimes observed. Pitrazepin (10(-4) M) caused a partial, voltage-independent block of GABA-induced current. The steroid derivative RU5135 was inactive at 10(-5) M. In contrast to the potent competitive blockade of vertebrate GABAA receptors by bicuculline, pitrazepin and RU5135, none of the weak antagonism caused by these drugs on the insect GABA receptor was competitive. Flunitrazepam (10(-6) M) potentiated GABA responses, providing evidence for a benzodiazepine site on an insect GABA-receptor-chloride-channel complex.

The nerve cord of the cockroach (Periplaneta americana) contains distinct saturable components of specific binding for the ligands N-[propionyl-3H]propionylated alpha-bungarotoxin and L-[benzilic-4,4'-3H]quinuclidinyl benzilate. N-[Propionyl-3H]propionylated alpha-bungarotoxin bound reversibly to homogenates with a Kd of 4.8 nM and Bmax of 910 fmol mg-1. The association rate constant (1.9 X 10(5) M-1 s-1) and dissociation rate constant (1.2 X 10(-4) s-1) yielded a Kd of 0.6 nM. Nicotinic ligands were found to displace toxin binding most effectively. The binding sites characterized in this way showed many similarities with the properties of the vertebrate neuronal alpha-bungarotoxin binding site. For a range of cholinergic ligands, inhibition constants calculated from toxin binding studies closely corresponded to their effectiveness in blocking the depolarizing response to acetylcholine recorded by electrophysiological methods from an identified cockroach motoneurone. The N-[propionyl-3H]propionylated alpha-bungarotoxin binding component therefore appears to be a constituent of a functional CNS acetylcholine receptor. Binding of L-[benzilic-4,4'-3H]quinuclidinyl benzilate was reversible with a Kd of 8 nM and Bmax of 138 fmol mg-1, determined from equilibrium binding experiments. The Kd calculated from the association rate constant (2.4 X 10(5) M-1 s-1) and dissociation rate constant (1.3 X 10(-4) s-1) was 1.9 nM. Muscarinic ligands were the most potent inhibitors of quinuclidinyl benzilate binding. The characteristics of this binding site resembled those of vertebrate CNS muscarinic cholinergic receptors. In contrast with vertebrate CNS, the nerve cord of Periplaneta americana contains more (approximately X 7) alpha-bungarotoxin binding sites than quinuclidinyl benzilate binding sites.

The effects of gamma-aminobutyric acid (GABA) on the uptake of 36Cl- into a membrane microsac preparation from isolated nerve cords of the cockroach Periplaneta americana was studied. On addition of 1 microM GABA (after 4-s incubation, then rapid quenching) the influx of 36Cl- was stimulated to a level 75% above that of the control value. This stimulation was reduced by picrotoxin (100 microM), but was not significantly affected by bicuculline (100 microM). Results of 36Cl- influx experiments are in agreement with data obtained from radiolabelled ligand binding assays and electrophysiological investigations on the same tissue. The method described represents a functional in vitro assay for CNS GABA receptors of insects.

Using the peroxidase antiperoxidase immunocytochemical method, we were able to demonstrate within the brain and retrocerebral complex of Periplaneta americana several neuronal structures which were very specifically stained with an anti-methionine-enkephalin antiserum. From the precise localization of this immunoreactive material some speculations about its possible functions could be derived, such as a neurotransmitter- or neuromodulatorlike function and/or a neurohormonal role. These data present new evidence for the recently developed concept that opiate peptides, identical or related to those found in higher species, occur also in invertebrates.

The vitellogenin in the oocyte of the American cockroach contains three different polypeptides with approximate molecular weights of 123 000, 118 000 and 57 000. These are present in a molar ratio of 2 : 2 : 2; all three contain carbohydrate. The same subunit structure is observed in vitellogenin isolated from hemolymph and in that secreted by fat body in organ culture. The only protein found within fat body by precipitation with female-specific antiserum is a large polypeptide, with a molecular weight of approx. 250 000. No mature vitellogenin subunits are found in fat body, even after pulsing with labeled amino acids and chasing with unlabeled substrates for up to 4 h. These data suggest that vitellogenin is synthesized in the fat body as a large precursor, which is processed to smaller polypeptides upon secretion into the hemolymph.

The present study deals with the distribution of adenosine triphosphatase and 5'-nucleotidase in the various constituents of thoracic ganglia and associated nerve of Periplaneta americana. The localization of both the enzymes in the thoracic ganglia is identical. The neural lamella is devoid of any activity for both the enzymes. The ganglion cells are intensely positive at their borders. The neuronal cell surface and/or glial cell processes which envelope the neurons show intense activity for these enzymes. Adenosine triphosphatase and 5'-nucleotidase are present around "giant fibres" and small axons. The activity appears to confine itself in the sheaths. The cytoplasm and the nuclei of the neurons are devoid of enzymatic activity, whereas the nucleoli are slightly active. The nerves are positive for both the enzymes. The role of these enzymes at different sites has also been discussed.

The activities of two enzymes of the serotonin biosynthetic pathway, namely tryptophan hydroxylase (TPH) and 5-hydroxytryptophan-decarboxylase (5-HTP-D), were determined in the cockroach, Periplaneta americana, brain using radiometric techniques, significant levels of both enzymes were found. p-Chlorophenylalanine (PCPA) inhibited brain TPH activity strongly both in vitro and in vivo. In vitro, 10 mM PCPA reduced the TPH activity by 76% and in vivo either 15 micrograms/g or 30 micrograms/g of PCPA inhibited brain TPH activity by 80-85%. The activity of 5-HTP-D enzyme was inhibited significantly in vivo by 3-hydroxybenzylhydrazine, commonly known as NSD-1015. A recovery in the activity of 5-HTP-D enzyme was observed 12 h after 50 micrograms/g of NSD-1015 but 100 micrograms/g caused an inhibition lasting for the 24 h period studied.

Serotonin-like immunoreactivity was mapped in the central nervous system (CNS) of the cockroach, Periplaneta americana. Immunoreactive staining occurred in every ganglion of the CNS. The largest numbers of immunoreactive somata were detected in the optic lobes and the brain, and lowest numbers in the first and second thoracic ganglia. Dense stained fibers, ramifications, and varicosities were found in all ganglia, and numerous axon like processes occurred in all interganglionic connectives. Immunoreactive processes were not, however, detected in most of the peripherally projecting nerve roots. Processes were found only in roots of the suboesophageal ganglion and the tritocerebral lobes of the brain. A comparison of the map for serotonin immunoreactivity with one generated for the pentapeptide transmitter proctolin suggests that the two systems overlap only in the suboesophageal ganglion and the tritocerebrum. The amine and peptide may co-occur in neurons in these regions. The serotonin immunoreactive system appeared significantly different from the octopaminergic system of the ventral nerve cord. Seventy-two potentially identifiable immunoreactive cells were located in the cockroach CNS. Some of these may be suitable for physiological study of the functional role of serotonin.

It has been shown by incubation of isolated midgut from Periplaneta americana fed double labelled triglycerides (3H glycerol, 14C oleic acid) that mostly triglycerides but also diglycerides and free fatty acids are released by the midgut. Fed triglycerides have been hydrolysed, then resynthetised before being released.

The RNA and DNA pattern in the follicle cells of cockroach ovary during vitellogenesis has been studied. Evidences indicate that there is an active synthesis of these two nucleic acids in the nucleus. It has been suggested from the observations presented that RNA is synthesized in the chromosomes and are then transported to nucleolus before being sent to the cytoplasm. It is also shown that the follicle cells do not contribute any RNA material to the vitellogenic oocyte.

Hemocytes and non hemocytes in vitro cell lines from Periplaneta americana, have been tested for their ability to incorporate, in the presence of vitamin B 12, various nucleic acid precursors into their DNA. Evidence was shown for enhanced transformation of all ribonucleotides into deoxyribonucleotides in the presence of vitamin B 12. Moreover, in hemocyte cell lines, it was demonstrated that vitamin B 12 produced an activation of thymidine kinase activity.

High-performance liquid chromatography with electrochemical detection was used to measure the concentrations of 3,4-dihydroxyphenylethylamine (dopamine), 5-hydroxytryptamine (5-HT), p-hydroxyphenylethanolamine (octopamine), alpha-methyl-p-tyrosine, and tryptophan in the cerebral ganglia of cockroaches (Periplaneta americana) after peripheral administration of alpha-methyl-p-tyrosine and alpha-methyltryptophan. In addition, the levels of dopamine, 5-HT, octopamine, alpha-methyl-p-tyrosine, and tryptophan were determined after injection of alpha-methyl-p-tyrosine, 6-hydroxydopamine, or 5,7-dihydroxytryptamine directly into the cerebral ganglia by means of microinjection needles. Peripheral administration of alpha-methyl-p-tyrosine (400-1,600 micrograms/insect) caused a reduction in dopamine and 5-HT concentrations in cockroach cerebral ganglia, although the reduction in dopamine concentrations was more pronounced. Peripheral injections of alpha-methyl-p-tyrosine also reduced octopamine levels in the cerebral ganglia. Peripheral injection of alpha-methyltryptophan (400-1,600 micrograms/insect) caused a marked reduction in 5-HT and tryptophan concentrations in cockroach cerebral ganglia without altering dopamine or octopamine concentrations. Central injections of alpha-methyl-p-tyrosine (80 micrograms/insect) reduced dopamine concentrations in the cerebral ganglia. However, neither 6-hydroxydopamine (20 micrograms/insect) nor 5,7-dihydroxytryptamine (20 micrograms/insect) caused reductions in amine levels when applied near or directly into the cerebral ganglia. The results suggest that specific lesions of aminergic neurons in insects by either 6-hydroxydopamine or 5,7-dihydroxytryptamine are impractical. The specific, long-lasting depletion of 5-HT by alpha-methyltryptophan suggests that this chemical may be useful in elucidating the functions of 5-HT in insects.

Brains, retrocerebral complexes and frontal and suboesophageal ganglia of adult American cockroaches, Periplaneta americana, were immunohistochemically investigated with a specific monoclonal antibody (McAb) directed against a well characterized antigenic determinant, namely the COOH terminus of the endecapeptide substance P (SP). This resulted in the detection of several neurons and nerve fibres containing a substance antigenically closely related to this typically vertebrate neuropeptide. No difference in staining pattern could be observed between male and female insects. Related to the age of the adult specimens, however, a slight quantitative difference in SP immunoreactivity seems to occur, which probably might have functional implications. The SP-like peptide demonstrated in this study appears to be located in different neuronal structures than the ones that we earlier described as containing ACTH-, CRF-, OT-, AVP-, NP I-, NP II-, BPP-, FMRFamide-, AKH-, met-ENK-, FSH-, LH- and LHRF-like material (Verhaert et al. 1984a, b, 1985; Verhaert and De Loof 1985a, b).

Uptake of 5-hydroxytryptamine (5-HT) by isolated whole nerve cords of the American cockroach, Periplaneta americana (L.), involved a dual component system, with one component consisting of rapid active uptake and the other of passive diffusion. Using high performance liquid chromatography with electrochemical detection, it was shown that nerve cords contained 5-HT levels of about 350 ng/g and an equivalent amount of 5-hydroxyindoleacetic acid (5-HIAA), a 5-HT metabolite not previously reported in cockroach nerve cords. Amidines had no discernable effect on uptake of 5-HT or octopamine by nerve cords or on endogenous levels of 5-HT and 5-HIAA in cords.

Evidence has been obtained to indicate that cyclodiene-type insecticides, e.g., heptachlor epoxide and gamma-BHC, mimic the action of picrotoxinin. These insecticides inhibit the GABA (gamma-aminobutyric acid)-stimulated chloride uptake in the coxal muscle of the American cockroach, and directly compete against [3H]a-dihydropicrotoxinin for binding in the rat brain synaptosomes. Moreover, several cyclodiene-resistant insect strains are also resistant to picrotoxinin. This cross-resistance is specific to picrotoxinin and does not extend to other neuroexcitants. These insecticides, like picrotoxinin, cause central nerve excitation by stimulating transmitter release. Similarity in molecular structures also has been pointed out. These results indicate that some of the nerve excitation symptoms that insecticides cause are likely due to their interaction with picrotoxinin receptor.

Thin-layer chromatography of cockroach corpora cardiaca (cc) extracts revealed a fraction (F1 in solvent system 1) which had hyperlipemic activity in locusts and which differed in mobility from synthetic locust adipokinetic hormone I (AKH I). Fractions 4 and 5 exhibited hypolipemic activity when injected into locusts. Pooled samples of these fractions caused a diminution of carbohydrate levels in the cockroach. Bovine insulin mimicked both these effects. No change in hemolymph lipid was evident in the cockroach after injection of either CC fractions 4 and 5 or bovine insulin. Both the active fraction from the cockroach CC and bovine insulin caused a decrease in hemolymph carbohydrate in neck-ligated locusts. Injection of locust hypolipemic hormone, separated from locust CC storage lobes by TLC, into neck-ligated locusts also caused a decrease in hemolymph carbohydrate concentration. Normal locusts showed no change in hemolymph carbohydrate.

The ionic events underlying gamma-aminobutyric acid (GABA) receptor activation on the cell body of a cockroach identified motor neuron were investigated by using current-clamp and voltage-clamp techniques. The reversal potential for GABA-induced hyperpolarization was -77.0 +/- 2.4 mV (mean +/- s.e.m.; n = 22). The reversal potential for GABA was highly sensitive to changes in external chloride, only weakly affected by changes in external potassium, and independent of changes in either sodium or calcium ion concentration. Intracellular ion-sensitive microelectrodes confirmed that an influx of chloride ions mediated the GABA response. Intracellular injection of acetate, citrate, sulphate, fluoride or ammonium caused no change in the reversal potential for GABA. Intracellular injection of chloride, bromide, chlorate, bromate, or methyl sulphate shifted the reversal potential for GABA to values more positive than resting membrane potential. Evidence for chloride accumulating and for extrusion mechanisms was examined by using putative inhibitors. However, internal application of ammonium ions, and external application of 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS), 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS), acetazolamide, furosemide, ammonium, zinc and copper ions, were all without effect on the reversal potential for GABA.

Ecdysteroid levels detected by RIA in extracts of mature ovaries from Periplaneta americana increased approximately fourfold (53 +/- 10 to 184 +/- 38 ng/g; +/- SEM, n = 3) on treatment with Helix pomatia "sulphatase" enzymes. HPLC analysis showed that this increase in immunoreactivity resulted from the hydrolysis of six apolar compounds that cochromatographed with the ecdysteroid esters previously shown to be present in newly laid oothecae (A1, A2, A3, A4, A5, and A6; A. J. Slinger, L. N. Dinan, and R. E. Isaac (1986). Insect Biochem. 16 (i), 115-119). Intact ovaries cultured in saline were able to take up [3H]ecdysone from the medium and synthesize ecdysone esters, most of which cochromatographed with immunoreactive peaks from ovaries and oothecae. Crude homogenates and membranes prepared from mature ovaries were also able to esterify ecdysone in vitro. The enzyme activity associated with a high-speed pellet was greatly enhanced by the addition of coenzyme A fatty acyl esters, each reaction resulting in the synthesis of a single major metabolite. The three esters formed on incubating ecdysone with coenzyme A-palmitate, -lineate, and -oleate could be characterized by their retention times on HPLC which were identical to compounds A2, A5, and A6, respectively. These compounds were the three quantitatively important immunoreactive esters found in ovaries and newly laid oothecae. The data presented indicates that ovaries can esterify ecdysone with palmitic, linoleic, and oleic acids and that these apolar derivatives are transferred to the egg. The esters appear to be different from the ecdysone 22-fatty acyl esters that have been isolated from ticks and other insects.

Ca2+-stimulated ATP hydrolyzing activities (i.e. Na-Ca ATP hydrolysis and Ca + Mg ATP hydrolysis) measured in cockroach brain tissue were highly sensitive to the action of pyrethroid insecticides under in vitro conditions. Non-cyano-containing pyrethroids inhibited Na-Ca ATP hydrolysis to a greater extent than their cyano-containing counterparts. The reverse is true for pyrethroid action on Ca + Mg ATP hydrolysis. Nonmitochondrial Ca + Mg ATP hydrolysis of disrupted synaptosomes was the most sensitive activity examined. Ca2+-stimulated ATP hydrolyzing activities were inhibited in cockroaches poisoned by permethrin in vivo. In vivo poisoning occurred in the presence of a similar amount of bound [14C]permethrin which had been determined to cause a substantial amount of inhibition to Ca2+-stimulated ATP hydrolyzing activities in vitro.

The effect of prolonged lithium administration on the phospholipid metabolism of flight muscles of the cockroach Periplaneta americana has been studied. Following daily injections of LiCl in a dose of 19.25 mumol LiCl per gram of wet weight [32P]- orthophosphate were injected and its incorporation into the phospholipids was measured 2, 12 and 24 h later. Lithium administration did not change the content of phospholipids but increased the 32P incorporation into phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine and sphingomyeline 1.87, 2.13, 2.02 and 1.87 times, respectively, as compared with the control values. These increases were neither due to an increased permeability of the tissue for inorganic phosphate nor to an increased turnover of gamma-P-ATP. It is concluded that prolonged lithium treatment increases the turnover of all phospholipids in insect flight muscle tissue.

The effect of toxaphene upon ion fluxes of the central nervous system (CNS) of the cockroach, Periplaneta americana (L.), was studied in vitro. The CNS, divided into three sections (brain, thoracic, and abdominal), was exposed to 10(-5) M toxaphene in saline containing 24Na+, 42K+, 36CL-, or 45Ca++. Uptake and efflux of these ion were evaluated. Toxaphene was responsible for significant increases in the internal levels of 42K+ and 45Ca++, but had little effect upon 24Na+ or 36Cl- movements. The resulting concentration changes of the ions may be involved in the neural activity observed with toxaphene poisoning. Of the three CNS sections, significant changes were more numerous and occurred earlier in abdominal sections.