Ventral nerve cord

Fig. 20.1. Confocal images of whole mounts of the ovijector region of A suum stained with phalloidin-tetramethylrhodamine isothiocyanate (TRITC) to show muscle and with an anti-RFamide antiserum coupled to fluorescein isothiocyanate (FITC) to show FaRPergic nerves. (A) Main ventral nerve cord encircles opening of ovijector where it meets the body wall and is immunopositive for FaRPs. (B) Flat-fixed preparation of the ovijector showing circular muscles and tracts of parallel FaRPergic nerves (arrows). (C) Detail of the circular muscle of ovijector and associated nerves (arrows). (D) A FaRPergic cell body is localized in the ventral nerve cord at junction with ovijector and provides innervation to ovijector muscle.

PNs terminate (67, 72, 73). The LALs are also linked to each other by bilateral neurons with arborizations in each LAL. Neuropil adjacent to the LAL contains branches of many neurons that descend in the ventral nerve cord. Local neurons link the LAL to this adjacent neuropil. Some descending neurons also have arborizations in the LAL. Thus, the LAL is interposed in the pathway of olfactory information flow from the AL through the lateral protocerebrum to descending neurons. 

The crayfish ventral nerve cords were excised, the medial and lateral giant axons partially desheathed. and the preparations placed in a chamber divided into 3 (1 cm ) sections. Each section was separated by petroleum jelly. Experiments were performed at room temperature (20-22 C). The crayfish Ringers was composed of (in mM/1) NaCl (146) KCl (4) CaCl2 Tris-... 

Keenan, L., Koopowitz, H. and Bernardo, K. (1 979) Primitive nervous systems action of aminergic drugs and blocking agents on activity in the ventral nerve cord of the flatworm Notoplana acticola. Journal of Neurobiology 10, 397-407. 

Iglesias F., Marco M. R, Jacquin-Joly E., Camps F. and Fabrias G. (1998) Regulation of sex pheromone biosynthesis in two noctuid species, S. littoralis and M. brassicae, may involve both PBAN and the ventral nerve cord. Arch. Insect Biochem. Physiol. 37, 295-304. 

Park Y. I. and Ramaswamy S. B. (1998) Role of brain, ventral nerve cord and corpora cardiaca-corpora allata complex in the reproductive behavior of female tobacco budworm (Lepidoptera Noctuidae). Ann. Entomol. Soc. Am. 91, 329-334. 

Tang J. D., Charlton R. E., Carde R. T. and Yin C.-M. (1987) Effect of allatectomy and ventral nerve cord transection on calling, pheromone emission and pheromone production in Lymantria dispar. J. Insect Physiol. 33, 469-476. 

Neuronal signals that descend from the central nervous system (CNS) or ascend through the ventral nerve cord (VNC) can modulate sex pheromone production and/or its release. 

Figure 3. Neurophysiological preparation of Trichoplusia ni. Head, thorax and gut are removed. Tungsten electrodes were placed into the hemocoel along side abdominal ganglion VIII (at Rl), the ventral nerve cord (at R2) and the abdominal wall (ground, Rj). Injections of alkaline-dissolved BTI -endotoxin, methamidophos and phospholipase-A2 were into the second pair of abdominal prolegs (Ch). Mechanical sensory stimulation with a glass probe was at the anal proleg (S). Activity in the ventral nerve cord was monitored through 24 h post-treatment (38-40) (see Figure 4).

Figure 4. Time dependency of nervous activity in the ventral nerve cord of Trichoplusia ni injected with 3.7 PPM alkaline-dissolved BTI 6-endotoxin (Sandoz), with 10 PPM methamidophos (MMP) and with 35 PPM phospholipase-A2 (P-A2). Mechanical sensory stimulation is given at arrow S. The control response was the same as the recording for P-A2. BTI and P-A2 were injected into T ni at their respective LDjq.

Proctolin appears to potentiate synaptic transmission in the central nervous system of the cockroach P. americana (37). Bursts of spike activity in the ventral nerve cord of this insect were elicited by mechanical stimulation of the cereal organs. In the presence of micromolar proctolin, the peak frequency and the duration of bursts were slowly, but significantly, increased. Carbacol, by comparison, caused an immediate enhancement of spontaneous activity, but potentiation of bursts was not observed. Thus, it was concluded that proctolin might function as a neuromodulator in the terminal ganglion. 

The nervous system resembles that of the annelid worms, but it is not segmented. The brain is the dorsal ganglion, an accumulation of nerve cells located over the esophagus, which extend into a single ventral nerve cord. 

Adenylate cyclase activity was measured essentially as described by Nathanson and Greengard (J ) except that a mixture of ATP (0.75 mM) and GTP (0.15 mM) was used to initiate the reaction. The amount of cAMP in the reaction mixture was determined with an assay kit from Amersham Corp. based on the method of Tovey et al. (20). Tissue homogenates were made from firefly light organs, and the ventral nerve cords of adult Periplaneta and larval Manduca. 

Initial experiments on MLA were carried out using the mannitol gap technique described by Callec et al. (12). However, comparable results could be obtained using a much simpler preparation, in which the sixth abdominal ganglion and cereal nerves were placed in a saline filled chamber, and the ventral nerve cord was draped over a wax partition into a separate chamber (Fig.4). The saline contained 210 mM NaCl, 3.1 mM KC1, 5.4 mM CaCl2, 0.1 mM NaH2P04,... 

The avermectins (AVM) are a family of naturally occurring macrolides which are produced by Streptomyces avermitilis and possess potent broad-spectrum anthelmintic, acaricidal and insecticidal activity (25-27). One of the major components of the avermectin complex is AVM Bla. This has been shown to interfere with neurotransmission at excitatory neuronal (nerve-nerve) synapses in the ventral nerve cord of A. suum where the mode of action seems to involve a GABA-ergic mechanism (1, 3) AVM Bla also abolishes the hyper polarizing potentials recorded from muscle bags of A. suum in response to stimulation of inhibitory motorneurones O, 3.). Kass and co-workers (2, 28) suggest that the effect on inhibitory neuromuscular transmission results from blockade of GABA receptors present on the postsynaptic muscle membrane. As the postsynaptic receptors are... 

Look for the eye-antennal imaginal discs which will be attached to the mouth hooks and to the optic lobes and ventral nerve cord (Fig. 2b, c). 

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