A neurosecretory protein from Locusta migratoria

Neuropeptide precursors in Tribolium castaneum

Neuropeptides and neurohormones are among the more diverse and functionally important classes of cell-to-cell signaling molecules involved in animal development and behavior. Less is known about the hormones and neuropeptides of the red flour beetle, Tribolium castaneum, than many other insects. However, the genomic information becoming available from this organism presents an opportunity to identify multiple neuropeptide and hormone genes, and hence their associated protein precursors. Using similarity-based prediction, we report new neuropeptides and hormone precursors from T. castaneum, bringing the number of annotated precursors to 37. We identified one prohormone (SVDPIDGDLIG-containing) having little similarity to other insect prohormones. The conversion of the protein precursors into bioactive peptides requires a suite of processing enzymes and a number of enzymatic steps; using the web-based NeuroPred application and similarity-based bioinformatics approaches, we predict 132 likely peptides that may result from the enzymatic processing of these gene products.

Isolation of neurosecretory granules containing cytochromogenic hormone activity from the corpora cardiaca of Blaberus discoidalis cockroaches

Neurosecretory granules (NSG) were isolated by differential centrifugation from a homogenate of the corpora cardiaca-corpora allata complex of newly emerged, adult, female Blaberus discoidalis cockroaches. By centrifuging at 11,000 g, the procedure yielded a final pellet that was enriched in small, membrane-bound vesicles (103 nm mean diameter). This pellet contained 61% of the cytochromogenic activity present in the original homogenate at an 11-fold increase in concentration. A pellet formed at 4000 g contained a mixture of mitochondria and larger NSG (146 nm mean diameter) and most of the hindgut-stimulating hormone activity. This procedure provided a quick, simple method for purifying neurosecretory granules and separating them into two categories of size and endocrine content.

Immunoreactive material resembling vertebrate neuropeptides in the corpus cardiacum and corpus allatum of the insect Leucophaea maderae

The presence and differential distribution of substances antigenically related to known vertebrate neuropeptides demonstrated within the corpus cardiacum of the insect Leucophaea are as follows: Of ten mammalian antisera tested, six yielded substantial immunoreactive deposits resembling oxytocin, somatostatin, Substance P, met-enkephalin, bombesin, and neurotensin, respectively. In the remaining four, the reaction was moderate (vasopressin, beta-endorphin) or marginal (LH-RF, calcitonin). With regard to their regional distribution, these biochemically distinct reaction products seem to fall into two groups: (1) Materials resembling oxytocin, vasopressin, met-enkephalin, beta-endorphin (and presumably also neurotensin and LH-RF) predominate in the central release area of the organ and are considered to be of extrinsic (cerebral) origin. (2) Substances localized primarily in areas rich in intrinsic glandular cells of the corpus cardiacum, and revealed by antisera raised against somatostatin, Substance P, and bombesin, are judge to be synthesized and stored within this organ. In peptidergic fibers entering ther adjacent corpora allata, thus far Substance P-, beta-endorphin-, and LH-RF-like immunoreactivities have been demonstrated. Some of these "new" neuropeptides may be contained in classical neurosecretory neurons, formerly identified by less specific methods, others must be assigned to additional peptidergic neurons heretofore unknown.

Release of neurosecretory protein from insect neurohaemal tissue following electrical stimulation

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.