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At least 307 records · Page 17Linked to original sources
PubMed1985

Octopamine enhances neuromuscular transmission in developing and adult moths, Manduca sexta.

The effect of octopamine on neuromuscular transmission was examined in developing and adult Manduca sexta. Intracellular recordings were made from the dorsal longitudinal muscle (DLM), superfused with solutions containing DL-octopamine or other amines. In untreated adult moths and pharate adults nearly ready to enclose (stage Day 19), stimulation of the motor nerve evokes a large excitatory junction potential (EJP), an active membrane response, and a twitch. In adults and Day 19 animals DL-octopamine (10(-7) to 10(-4)M) has no effect on the amplitude and rise-time of the electrical response in normal saline, but 10(-6) to 10(-4) M DL-octopamine increases the amplitude of the excitatory junction potential recorded in saline containing one-third the normal calcium concentration. Immature (Day 16) muscle, which normally produces only small EJPs following stimulation of its motor nerve, responds to 10(-6) to 10(-4) M DL-octopamine by an increase in the EJP above threshold for an active membrane response and a contraction. When the muscle has developed sufficiently to spike and contract in response to nerve stimulation in the absence of exogenous octopamine (Days 17 and 18), application of DL-octopamine increases the maximum rate at which the muscle contracts in response to each stimulus in a train (designated the maximum following frequency, MFF). The threshold dose for an effect on the MFF of Day 18 immature moths is less than 10(-10) M. At this stage 10(-8) M DL-octopamine increases the MFF four-fold. The effect on the MFF is dose-dependent over the range 10(-10) M to 10(-6) M. The biogenic amines DL-epinephrine, DL-norepinephrine, tyramine, DL-phenylethanolamine, 2-phenylethylamine, and dopamine, applied at concentrations of 10(-8) or 10(-4) M, do not change the MFF. Both DL-synephrine (10(-8) M) and serotonin (10(-7) M) mimic the action of 10(-10) M DL-octopamine on the MFF. The action of DL-octopamine (10(-7) M) is blocked by phentolamine (10(-4)M) but not by propranolol (10(-4)M). The octopamine content of hemolymph was determined with a radioenzymtic assay. The concentration of octopamine in the hemolymph increases 3.6-fold, from 5 X 10(-8) M on Day 18 (duration of adult development is 19 days) to 1.85 X 10(-7) M one day following eclosion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Effects of octopamine on miniature excitatory junction potentials from developing and adult moth muscle.

Intracellular recordings of excitatory junction potentials (EJPs) and miniature EJPs (MEJPs) were made from the dorsal longitudinal muscle of Manduca sexta to determine the sites of action of octopamine. MEJPs increased in amplitude and frequency as the moth developed during the 3 days before eclosion. DL-Octopamine (5 X 10(-6) M) increased the amplitude of excitatory junction potentials in both immature moths (one day before eclosion) and adults. Octopamine (10(-5) M) also increased the amplitude and frequency of MEJPs from immature animals (one and two days before eclosion) but had the opposite effect on adults and pharate adults ready to eclose. Treatment with octopamine (10(-5) M) resulted in a decrease in input resistance and a hyperpolarization in both immature and adult muscle fibers. The results suggest that octopamine acts both presynaptically and postsynaptically but that the increase in the amplitude of the evoked response is due primarily to influences on presynaptic processes.

Age Factors↗
PubMed1986

Adult-specific neurons in the nervous system of the moth, Manduca sexta: selective chemical ablation using hydroxyurea.

The segmental ganglia of adults of the moth, Manduca sexta, are constructed both from remodeled larval neurons and from adult-specific cells. The latter are produced by identified stem cells (neuroblasts) during larval life and then differentiate to form functional neurons during metamorphosis. The mitotic activity of the larval neuroblasts could be irreversibly blocked by the DNA-synthesis inhibitor hydroxyurea (HU). Treatment on day 1 of the third larval stage resulted in 80-90% of the neuroblasts being blocked before they produced any progeny while leaving the functional larval neurons unaffected. Treated larvae finished growth, underwent metamorphosis, and produced an adult CNS that contained the normal set of remodeled larval neurons but lacked most of the new adult-specific cells. When HU treatment was delayed until the start of the fourth or fifth larval stage, the neuroblasts produced the early portions of their respective lineages before they were blocked. The immature neurons that were generated prior to treatment survived to contribute adult-specific neurons to the moth CNS, but the remainder of each lineage was missing. This technique therefore enables one to produce adult nervous systems containing the basic set of remodeled larval cells plus defined sets of adult-specific neurons.

Animals↗
PubMed1987

Possible interactions of a steroid hormone and neural inputs in controlling the death of an identified neuron in the moth Manduca sexta.

The emergence of the adult Manduca sexta moth is followed by the loss of almost half of this insect's abdominal motoneurons and interneurons (Truman, 1983). This programmed cell death completes the transformation of the nervous system of the caterpillar into that of the moth. The death of these neurons has been previously shown to be a response to an endocrine signal: the decline in ecdysteroids that occurs at the end of metamorphosis (Truman and Schwartz, 1984). Our current research is focussed on the regulation of the fate of a pair of identified motoneurons, the MN-12 cells, in the third abdominal ganglion. Isolation of this ganglion from anterior parts of the nervous system can prevent the death of these cells at the time when they would normally die in response to the decline in ecdysteroids. Transection of the ventral nerve cord at various levels revealed that the source of this regulatory "death signal" is the fused pterothoracic ganglion and that it is transmitted via the interganglionic connectives. We hypothesize that the factors mediating this effect may act in concert with the ecdysteroid decline to specify the exact time of death for individual neurons.

Animals↗
PubMed1995

Domain III exchanges of Bacillus thuringiensis CryIA toxins affect binding to different gypsy moth midgut receptors.

Aminopeptidase-N, purified from gypsy moth (Lymantria dispar L.) brush border membrane vesicles, exhibited specific binding to CryIAc toxin but not to CryIAa toxin. CryIAa-CryIAc hybrid toxins were used to localize the aminopeptidase-N binding region on CryIAc. Slot blot assays and ligand blot experiments demonstrated that the hybrid toxins which have the residues 451 to 623, comprising essentially domain III, from CryIAc toxin exhibited strong binding to purified aminopeptidase-N and 120 kDa brush border membrane protein. In contrast, the hybrid toxins which have the residues 451 to 623 from CryIAa toxin failed to bind to aminopeptidase-N, but did bind to another receptor, a 210 kDa protein. This is the first direct evidence that domain III is involved in receptor binding and the first to demonstrate that domain III substitutions direct the binding of these toxins to different gypsy moth midgut receptors.

Animals↗
PubMed1998

Functional characterization of a new class of odorant-binding proteins in the moth Mamestra brassicae.

A new protocol of binding assay allowed us to functionally characterize two additional odorant-binding proteins in antennae of the moth Mamestra brassicae. These proteins have no N-terminal sequence homology with the moth pheromone-binding proteins and general odorant-binding proteins previously described. One of the two proteins designated MbraAOBP2 is between 60 and 73% similar in N-terminal to several proteins characterized in chemosensory organs of Diptera, Hymenoptera, Lepidoptera, and Phasmids, indicating that these proteins constitute a new group of odorant-binding proteins. A particularly high similarity between MbraAOBP2 and ejaculatory bulb specific protein III of Drosophila suggested that vaccenyl acetate could be a specific ligand for these proteins. As a matter of fact, MbraAOBP2 bound vaccenyl acetate in vitro, but we failed to detect any receptor cell in long and short sensilla trichodea of males. This protocol could be used as a rapid method to identify new odorant-binding proteins in chemosensory organs or tissues.

Amino Acid Sequence↗
PubMed1999

Impact of Vairimorpha sp. (Microsporidia: Burnellidae) on Trichogramma chilonis (Hymenoptera, Trichogrammatidae), a hymenopteran parasitoid of the cabbage moth, Plutella xylostella (Lepidoptera, Yponomeutidae).

A multi-generation mass breeding colony of the cabbage moth, Plutella xylostella, was found to be infected with a microsporidium, Vairimorpha sp., which is passed transovarially between generations. The microsporidian infection had little impact on the fitness of this lepidopteran pest. However, when Trichogramma chilonis parasitized such infected host eggs, the offspring of this parasitoid species suffered from severe deficiencies. Microsporidian spores, ingested by parasitoid larvae together with the host egg nutrients, gave rise to stages which developed in various tissues of the parasitoid, such as the flight muscle and the nervous system. This infection resulted in a significantly increased rate of metamorphosis failure (related to host age) and reduced longevity and reproductive performance of the parasitoids. There are two main consequences arising from our findings if T. chilonis is to be used in an integrated control strategy against P. xylostella: (1) T. chilonis must be raised on Vairimorpha-free host eggs to receive viable and efficaceous parasitoids for release and (2) if natural populations of the cabbage moth in cruciferous crops are infected with Vairimorpha to a significant extent, the parasitoid must be released repeatedly within infested crop areas.

Animals↗
PubMed1999

Characterization of a nucleopolyhedrovirus from the vapourer moth, Orgyia antiqua (Lepidoptera Lymantriidae).

The first characterization of a nucleopolyhedrovirus (NPV Baculoviridae) isolated from the vapourer moth, Orgyia antiqua (Lepidoptera Lymatriidae), in the United Kingdom is presented. Transmission electron microscopy revealed that the virus nucleocapsid rods were singly enveloped in the polyhedron inclusion body (PIB) so that the virus is assigned to the SNPV subgenus of the Baculoviridae. Restriction endonuclease analyses of viral DNA indicated a genomic size of approximately 148 kb. Restriction profiles of O. antiqua SNPV closely resembled those of heterologous NPVs isolated from four different Orgyia species and was most similar to a North American SNPV isolate from the Douglas-fir tussock moth, O. pseudotsugata. In host range tests, O. antiqua SNPV was not infectious to 23 lepidopteran species representing four families. Heterologous Orgyia NPV isolates were permissive in O. antiqua larvae. Using a diet plug bioassay method, the median lethal dose response (LD(50)) for this virus in second and third instar O. antiqua larvae were estimated at 52 and 539 PIBs per larva, respectively.

Animals↗
PubMed2001

Impact of a North American isolate of the microsporidium Nosema carpocapsae on a laboratory population of the codling moth, Cydia pomonella.

Nosema carpocapsae is a microsporidian pathogen of the codling moth, Cydia pomonella. We report the occurrence of this pathogen in a colony originating from collections made in the United States. This is the first record of N. carpocapsae infecting North American codling moths. This North American isolate of N. carpocapsae was indistinguishable from isolates received from New Zealand and Bulgaria, based on small subunit ribosomal RNA sequencing, but was more virulent than the previously described New Zealand isolate. In the laboratory, infected larvae and pupae had increased mortality compared to their uninfected counterparts and developmental time increased by 1 week. There was no effect on female fecundity. Within a cohort of eggs laid by infected females, neonates that emerged first were more likely to be uninfected. We established an uninfected colony by interrupting horizontal transmission and only utilizing the larvae that emerged from the first-laid eggs.

Animals↗
PubMed1988

Functional morphology of the ommatidia in the compound eye of the moth, Antheraea polyphemus (Insecta, Saturniidae).

The fine structure of the superposition eye of the Saturniid moth Antheraea polyphemus Cramer was investigated by electron microscopy. Each of the approximately 10,000 ommatidia consists of the same structural components, but regarding the arrangement of the ommatidia and the rhabdom structure therein, two regions of the eye have to be distinguished. In a small dorsal rim area, the ommatidia are characterized by rectangularly shaped rhabdoms containing parallel microvilli arranged in groups that are oriented perpendicular to each other. In all other ommatidia, the proximal parts of the rhabdoms show radially arranged microvilli, whereas the distal parts may reveal different patterns, frequently with microvilli in two directions or sometimes even in one direction. Moreover, the microvilli of all distal cells are arranged in parallel to meridians of the eyes. By virtue of these structural features the eyes should enable this moth not only discrimination of the plane of polarized light but also skylight-orientation via the polarization pattern, depending on moon position. The receptor cells exhibit only small alterations during daylight within the natural diurnal cycle. However, under illumination with different monochromatic lights of physiological intensity, receptor cells can be unbalanced: Changes in ultrastructure of the rhabdomeres and the cytoplasm of such cells are evident. The effects are different in the daytime and at night. These findings are discussed in relation to the breakdown and regeneration of microvilli and the influence of the diurnal cycle. They are compared with results on photoreceptor membrane turnover in eyes of other arthropod species.

Animals↗
PubMed1991

Parallel processing of afferent input by identified interneurones in the auditory pathway of the noctuid moth Noctua pronuba (L.).

1. Interneurones 501 and 504 are identified sound-sensitive interneurones in the pterothoracic ganglion of the noctuid moth Noctua pronuba. Both neurones receive monosynaptic input from the A1 afferent and experiments with current injection suggest that the synapse is chemical. The EPSPs evoked in either IN 501 or 504 by the A1 afferent do not facilitate. 2. Temporal integration in INs 501 and 504 was compared by presenting the moth with tones at repetition rates found in the search, approach and terminal phases of the echolocating call of a hunting bat. INs 501 and 504 differ in their capacity to resolve stimulus repetition rates because the mean decay times of their compound EPSPs differ by a factor of three, although both interneurones receive monosynaptic input from the A1 afferent. 3. The features extracted from the authentic, prerecorded, call of an echolocating bat at the level of the pterothoracic ganglion were examined by recording sequentially from a range of interneurones in the same preparation. The capacity of INs 501 and 504 to encode the various phases of the call was examined in the light of their measured mean decay times and related to the avoidance behaviour of the insect.

Acoustic Stimulation↗
PubMed1990

Acetylcholinesterase activity in antennal receptor neurons of the sphinx moth Manduca sexta.

We have used a cytochemical technique to investigate the distribution of acetylcholinesterase (AChE) activity in the antenna of the sphinx moth Manduca sexta. High levels of echothiophate-insensitive (presumably intracellular) AChE activity were found in six different types of antennal receptors localized in specific regions of the three antennal segments of the adult moth. Mechanosensory organs in the scape and pedicel, the Böhm bristles and Johnston's organ, are innervated by AChE-positive neurons. In each annulus of the antennal flagellum, AChE-positive neurons are associated with six sensilla chaetica and a peg organ, probably a sensillum styloconicum. At least 112 receptor neurons (8-10 per annulus) innervating the intersegmental membranes between the 14 distalmost annuli also exhibit high levels of echothiophate-resistant AChE. In addition, each annulus has more than 30 AChE-positive somata in the epidermis of the scale-covered (back) side of the flagellum, and 4 AChE-positive somata reside within the first annulus of the flagellum. Since none of the olfactory receptor neurons show a high level of echothiophate-resistant AChE activity, and all known mechanoreceptors are AChE-positive, apparently "intracellular" AChE activity in the antenna correlates well with mechanosensory functions and is consistent with the idea that these cells employ acetylcholine as a neurotransmitter.

Acetylcholinesterase↗
PubMed1992

Postembryonic development of leucokinin I-immunoreactive neurons innervating a neurohemal organ in the turnip moth Agrotis segetum.

In the abdominal ganglia of the turnip moth Agrotis segetum, an antibody against the cockroach neuropeptide leucokinin I recognizes neurons with varicose fibers and terminals innervating the perisympathetic neurohemal organs. In the larva, the abdominal perisympathetic organs consist of a segmental series of discrete neurohemal swellings on the dorsal unpaired nerve and the transverse nerves originating at its bifurcation. These neurohemal structures are innervated by varicose terminals of leucokinin I-immunoreactive (LKIR) fibers originating from neuronal cell bodies located in the preceding segment. In the adult, the abdominal segmental neurohemal units are more or less fused into a plexus that extends over almost the whole abdominal nerve cord. The adult plexus consists of peripheral nerve branches and superficial nerve fibers beneath the basal lamina of the neural sheath of the nerve cord. During metamorphosis, the LKIR fibers closely follow the restructuration of the perisympathetic organs. In both larvae and adults the LKIR fibers in the neurohemal structures originate from the same cell bodies, which are distributed as ventrolateral bilateral pairs in all abdominal ganglia. The transformation of the series of separated and relatively simple larval neurohemal organs into the larger, continuous and more complex adult neurohemal areas occurs during the first of the two weeks of pupal life. The efferent abdominal LKIR neurons of the moth Agrotis segetum thus belong to the class of larval neurons which persist into adult life with substantial peripheral reorganization occurring during metamorphosis.

Animals↗
PubMed1987

GABA-mediated synaptic inhibition of projection neurons in the antennal lobes of the sphinx moth, Manduca sexta.

Responses of neurons in the antennal lobe (AL) of the moth Manduca sexta to stimulation of the ipsilateral antenna by odors consist of excitatory and inhibitory synaptic potentials. Stimulation of primary afferent fibers by electrical shock of the antennal nerve causes a characteristic IPSP-EPSP synaptic response in AL projection neurons. The IPSP in projection neurons reverses below the resting potential, is sensitive to changes in external and internal chloride concentration, and thus is apparently mediated by an increase in chloride conductance. The IPSP is reversibly blocked by 100 microM picrotoxin or bicuculline. Many AL neurons respond to application of GABA with a strong hyperpolarization and an inhibition of spontaneous spiking activity. GABA responses are associated with an increase in neuronal input conductance and a reversal potential below the resting potential. Application of GABA blocks inhibitory synaptic inputs and reduces or blocks excitatory inputs. EPSPs can be protected from depression by application of GABA. Muscimol, a GABA analog that mimics GABA responses at GABAA receptors but not at GABAB receptors in the vertebrate CNS, inhibits many AL neurons in the moth.

Animals↗
PubMed1990

The toxicity of two Bacillus thuringiensis delta-endotoxins to gypsy moth larvae is inversely related to the affinity of binding sites on midgut brush border membranes for the toxins.

The delta-endotoxin from Bacillus thuringiensis subspecies kurstaki strain HD1-9 is almost 400 times more potent than the delta-endotoxin from strain HD-73 as a gypsy moth larvicide. The two delta-endotoxins compete for a high-affinity binding site on the brush border membrane of larval gypsy moth midguts. The affinity for the delta-endotoxin from strain HD-73 is much greater than the affinity for the delta-endotoxin from strain HD1-9.

Animals↗
PubMed1978

Gypsy moth cell lines divergent in viral susceptibility. I. Culture and identification.

A series of cell lines unique in insect virus susceptibility pattern have been isolated from the ovaries of the gypsy moth (Lymantria dispar: Lepidoptera: Lymantriidae) on a synthetic medium with mammalian and avian serum supplementation. Growth curves showed the poorest growth occurring on peptone-based media with somewhat better growth on amino-acid-based media. The best growth was obtained with combined media. Serological study distinguished the present cell lines from one another and from cell lines derived from other insect species grown routinely in the same laboratory. Baculovirus susceptibility among the new lines varied from no response to a specific complete replication response upon challenge by the homologous (gypsy moth) nuclear polyhedrosis virus.

Cell Division↗
PubMed1997

Immunocytochemical localization of testis ecdysiotropin in the pupa of the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae).

Antiserum against testis ecdysiotropin isolated from the gypsy moth, Lymantria dispar, reacted with neurons in the protocerebrum, optic and antennal lobes, subesophageal, thoracic and abdominal ganglia, as well as in nerve tracts extending through the optic lobes, tritocerebrum, and interganglionic connectives of the pupal stage of these insects. Testis ecdysiotropin is a peptide required by immature moths to initiate production of testes ecdysteroid, which is necessary for the development of the male reproductive system and initiation of spermatogenesis. Antiserum against testis ecdysiotropin also detected an accumulation of testis ecdysiotripic-like material between the inner and outer testis sheaths of pupae. The localization of this peptide in the imaginal disks of the last larval stage, cells and nerve fibers in the optic and antennal lobes of the pupa of both sexes, as well as in the testes during development of the adult reproductive system indicates that testis ecdysiotropin has a much larger impact on adult metamorphosis than development of the reproductive system and initiation of gametogenesis. Although this peptide may have a modulatory role in the central nervous system (CNS), it may also initiate a cascade of activity required for the development of the adult nervous system, in addition to its role in reproduction.

Abdomen↗
PubMed1997

Biosynthetic pathway for producing the sex pheromone component (Z,E)-9,12-tetradecadienyl acetate in moths involves a delta 12 desaturase.

Sex pheromones are used by insects as a form of chemical communication for the purpose of attracting conspecific mates. Female moths Cadra cautella and Spodoptera exigua use the diene (Z,E)-9,12-tetradecadienyl acetate as the major pheromone component. Biosynthesis of this pheromone component was demonstrated to occur through delta 11 desaturation of hexadecanoic acid (palmitate) to produce (Z)-11-hexadecenoic acid which is then chain-shortened to (Z)-9-tetradecenoic acid. A unique delta 12 desaturase uses the (Z)-9-tetradecenoic acid to produce (Z,E)-9,12-tetradecenoic acid which is reduced and acetylated to form the acetate ester pheromone component. Both moths also use a pheromonotropic peptide to stimulate pheromone biosynthesis.

Animals↗