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1.
Science ; 207(4433): 898-900, 1980 Feb 22.
Article in English | MEDLINE | ID: mdl-17729872

ABSTRACT

Inactive female corpora allata implanted into adult males become active and continue to synthesize juvenile hormone at high rates. However, when an ovary is implanted together with the corpora allata, rates of juvenile hormone synthesis decline as the oocytes complete maturation. Injections of ecdysterone mimic the effect of an implanted ovary.

2.
Brain Res ; 208(2): 451-5, 1981 Mar 16.
Article in English | MEDLINE | ID: mdl-6111379

ABSTRACT

A protein, located within the protocerebral neurosecretory system of locusts, is released from the storage lobes of the corpora cardiaca following the propagation of a compound action potential to the storage lobe via the nervus corpus cardiacum I. Release depends upon the entry of extracellular calcium during depolarization. The data presented here indicate that a protein, similar to the neurophysins of vertebrates, is released from neurohaemal tissue of locusts following stimuli which are known to favour hormone release.


Subject(s)
Brain/physiology , Neurophysins/metabolism , Neurosecretory Systems/physiology , Synaptic Transmission , Animals , Axons/physiology , Calcium/pharmacology , Electric Stimulation , Female , Grasshoppers , Neurotransmitter Agents/physiology , Synaptic Transmission/drug effects
3.
Toxicon ; 27(3): 305-16, 1989.
Article in English | MEDLINE | ID: mdl-2728023

ABSTRACT

Immobilizing and lethal effects of the venoms obtained from six spider species (Brachypelma albopilosum, Atrax robustus, Cupiennius salei, Selenops mexicanus, Tegenaria atrica, Argiope bruennichi) were tested on Blatta orientalis (cockroach) and Tenebrio molitor (common mealbeetle). The immobilizing effects were quantified by measuring insect locomotor activity in circle arenas observed over 72 hr after venom injection. Both insect species showed cramps, quivering and jerking of the limbs as well as flaccid paralysis after venom injection. Through relative toxicity of the venoms tested is the same in T. molitor and B. orientalis, T. molitor is absolutely less sensitive to spider venoms. The effects on locomotor activity show time characteristics specific for each venom. A dependence of the venom paralyzing effects on insect locomotor activity, low intensity of the initial excitatory phase of the venom effects and partial recovery of the insects was found with A. bruennichi and T. atrica venom. The maximal venom yields of A. bruennichi and S. mexicanus are not lethal to B. orientalis, indicating that the mere immobilizing effects of spider venoms are far more crucial to prey capture than their lethal effects. The contribution of a variety of differently acting neurotoxic components in spider venoms to the observed venom effects on insects and the significance of the venoms in spider nutrition, hunting behaviour and ecology are discussed.


Subject(s)
Arthropod Venoms/toxicity , Cockroaches/physiology , Insecta/physiology , Paralysis/chemically induced , Spider Venoms/toxicity , Animals , Female , Lethal Dose 50 , Male , Motor Activity/drug effects , Proteins/analysis , Spider Venoms/analysis , Time Factors
4.
J Nat Prod ; 62(9): 1256-9, 1999 Sep.
Article in English | MEDLINE | ID: mdl-10514308

ABSTRACT

A Geodia species collected from southern Australian waters of the Great Australian Bight has yielded a potent new in vitro nematocidal agent identified as geodin A Mg salt (1), a new macrocyclic polyketide lactam tetramic acid magnesium salt. The structure for 1 was assigned on the basis of detailed spectroscopic analysis.

10.
J Exp Biol ; 202(Pt 16): 2151-9, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10409486

ABSTRACT

Substratum vibrations elicit a fast startle response in unrestrained quiescent desert locusts (Schistocerca gregaria). The response is graded with stimulus intensity and consists of a small, rapid but conspicuous movement of the legs and body, but it does not result in any positional change of the animal. With stimuli just above threshold, it begins with a fast twitch of the hindlegs generated by movements of the coxa-trochanter and femur-tibia joints. With increasing stimulus intensity, a rapid movement of all legs may follow, resulting in an up-down movement of the whole body. The magnitude of both the hindleg movement and electromyographic recordings from hindleg extensor and flexor tibiae muscles increases with stimulus amplitude and reaches a plateau at vibration accelerations above 20 m s(-)(2) (peak-to-peak). Hindleg extensor and flexor tibiae muscles in unrestrained animals are co-activated with a mean latency of 30 ms. Behavioural thresholds are as low as 0. 47 m s(-)(2) (peak-to-peak) at frequencies below 100 Hz but rise steeply above 200 Hz. The response habituates rapidly, and inter-stimulus intervals of 2 min or more are necessary to evoke maximal reactions. Intracellular recordings in fixed (upside-down) locusts also revealed co-activation of both flexor and extensor motor neurones with latencies of approximately 25 ms. This shows that the neuronal network underlying the startle movement is functional in a restrained preparation and can therefore be studied in great detail at the level of identified neurones.


Subject(s)
Grasshoppers/physiology , Animals , Behavior, Animal , Electromyography , Electrophysiology , Habituation, Psychophysiologic , Motor Neurons/physiology , Reflex, Startle/physiology , Vibration
11.
Experientia ; 35(5): 657-8, 1979 May 15.
Article in English | MEDLINE | ID: mdl-446673

ABSTRACT

An approach to the isolation of neurosecretory material from planarians is described. This material stimulated RNA synthesis, in a dose-dependent response, in regenerating Dugesia tigrina. The data support the concept that neurosecretion plays a key role in the process of regeneration in planarians.


Subject(s)
Neurosecretion , Planarians/physiology , RNA/biosynthesis , Regeneration , Turbellaria/physiology , Animals , Planarians/metabolism , Uridine/metabolism
12.
J Nat Prod ; 64(5): 640-2, 2001 May.
Article in English | MEDLINE | ID: mdl-11374963

ABSTRACT

A southern Australian marine sponge, Trachycladus laevispirulifer, has yielded a potent new nematocide with antifungal activity which has been identified as onnamide F (1). The structure for 1 was assigned by detailed spectroscopic analysis and chemical conversion to the methyl ester 2. Onnamide F contains a common structural motif previously described in a number of natural products exhibiting interesting pharmacological activities, including the insect chemical defense agent pederin (3), and the sponge metabolites the onnamides, mycalamides, and theopederins.


Subject(s)
Antinematodal Agents/chemistry , Antinematodal Agents/toxicity , Porifera/chemistry , Pyrans/chemistry , Pyrans/toxicity , Animals , Antifungal Agents/pharmacology , Antinematodal Agents/isolation & purification , Australia , Haemonchus/drug effects , Mass Spectrometry , Microbial Sensitivity Tests , Pyrans/isolation & purification , Saccharomyces cerevisiae/drug effects , Tissue Extracts/chemistry , Tissue Extracts/toxicity
13.
J Nat Prod ; 63(12): 1682-3, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11141116

ABSTRACT

A marine actinomycete (MST-MA190) isolated from a sample of beach sand collected near Lorne on the southwest coast of Victoria, Australia, has yielded two new aromatic amides, lorneamide A (1) and lorneamide B (2). The lorneamides belong to a novel class of tri-alkyl-substituted benzenes, and their structures were determined by spectroscopic methods.


Subject(s)
Actinomycetales/chemistry , Alkenes/isolation & purification , Amides/isolation & purification , Alkenes/chemistry , Amides/chemistry , Marine Biology , Spectrum Analysis
14.
Vaccine ; 14(17-18): 1603-12, 1996 Dec.
Article in English | MEDLINE | ID: mdl-9032888

ABSTRACT

Glutathione S-transferase (GST) from the liver fluke Fasciola hepatica was assessed as a vaccine immunogen in cattle in a number of immunological adjuvants. Significant reductions in fluke burdens (49-69%) were only observed in cattle vaccinated with GST in Quil Alsqualene Montanide (SM) and PLG microspheres in SM but there was no correlation between anti-GST IgG titres and protection. In separate experiments, animals vaccinated with GST in Quil AlSM were still significantly protected (48%, P < 0.05) 6 months after boosting and no significant differences in protection were seen when the metacercarial challenge was given over 1 month instead of as a single bolus. Inhibition of GST enzyme activity in vitro by cattle antisera did not correlate with reduced fluke burdens.


Subject(s)
Adjuvants, Immunologic , Cattle Diseases/prevention & control , Fasciola hepatica , Fascioliasis/veterinary , Glutathione Transferase/immunology , Vaccination , Animals , Antibodies/blood , Body Burden , Cattle , Enzyme-Linked Immunosorbent Assay , Fascioliasis/prevention & control , Glutathione Transferase/analysis , Glutathione Transferase/antagonists & inhibitors , Male , Quillaja Saponins , Saponins , Titrimetry , Trematoda
15.
J Org Chem ; 66(23): 7765-9, 2001 Nov 16.
Article in English | MEDLINE | ID: mdl-11701034

ABSTRACT

Bioassay-directed fractionation of the EtOH extract of an Oceanapia sp. collected off the northern Rottnest Shelf, Australia, has yielded three novel dithiocyanates, thiocyanatins A (1), B (2a), and C (2b). The structures were determined by detailed spectroscopic analysis and confirmed by total synthesis. In addition to featuring an unprecedented dithiocyanate functionality, thiocyanatins possess an unusual 1,16-difunctionalized n-hexadecane carbon skeleton and are revealed as a hitherto unknown class of nematocidal agent.


Subject(s)
Alkenes/chemical synthesis , Alkenes/isolation & purification , Antinematodal Agents/chemical synthesis , Antinematodal Agents/isolation & purification , Porifera/chemistry , Thiocyanates/chemical synthesis , Thiocyanates/isolation & purification , Alkenes/pharmacology , Animals , Antinematodal Agents/pharmacology , Haemonchus/drug effects , Haemonchus/growth & development , Nuclear Magnetic Resonance, Biomolecular , Structure-Activity Relationship , Thiocyanates/pharmacokinetics , Thiocyanates/pharmacology
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