The quiet revolution of numerical weather prediction.

Advances in numerical weather prediction represent a quiet revolution because they have resulted from a steady accumulation of scientific knowledge and technological advances over many years that, with only a few exceptions, have not been associated with the aura of fundamental physics breakthroughs. Nonetheless, the impact of numerical weather prediction is among the greatest of any area of physical science. As a computational problem, global weather prediction is comparable to the simulation of the human brain and of the evolution of the early Universe, and it is performed every day at major operational centres across the world.

Expression and bioactivity of allatostatin-like neuropeptides in helminths.

Allatostatins are the largest family of known arthropod neuropeptides. To date more than 150 different arthropod type-A allatostatins have been identified and are characterized by the C-terminal signature, (Y/F)XFG(L/I)amide. Using specific allatostatin antisera, positive immunoreactivity has been identified within the central and peripheral nervous systems of the flatworm (platyhelminth) Procerodes littoralis and the roundworm (nematode) Panagrellus redivivus. Comparative analyses of the allatostatin-like immunoreactivity and that of other known helminth neuropeptides (FMRFamide-like peptides [FLPs]) indicate differences in the distribution of these peptide families. Specific differences in neuropeptide distribution have been noted within the pharyngeal innervation of flatworms and in the cephalic papillary neurons of nematodes. In arthropods, type-A allatostatins have functions that include potent myoactivity. In this study, seven members of the allatostatin superfamily induced concentration-dependent contractions of flatworm muscle fibres. Pharmacological studies indicate that these peptides do not interact with muscle-based FLP receptors. The type-A allatostatins, therefore, represent the second family of neuropeptides that induce muscle contraction in flatworms. Although the majority of arthropod type-A allatostatins examined did not affect the somatic body wall muscle or the ovijector of the pig nematode, Ascaris suum, two type-A allatostatins (GDGRLYAFGLamide and DRLYSFGLamide) exhibited significant inhibitory effects on the A. suum ovijector at 10 microM. These data suggest that allatostatin-like peptides and receptors occur in helminths. Further, although arthropod type-A allatostatins display inter-phyla activities, their receptors are less compelling as potential targets for broad-spectrum parasiticides (endectocides) than FLP receptors.

Neuropeptide co-localisation in the lepidopteran frontal ganglion studied by electron-microscopic gold-labelling immunocytochemistry.

An immunogold-labelling electron-microscopic study of the frontal ganglion of two noctuids, Lacanobia oleracea and Helicoverpa armigera, has been carried out with antisera directed against three neuropeptides; allatostatins of the Y/FXFGL-NH2 type, Manduca sexta allatostatin (Mas-AS) and M. sexta allatotropin. The ganglion of both noctuids has two pairs of large peptidergic neurones with many clusters of electron-dense granules, one pair being situated anteriorly and the other posteriorly. By means of a double-labelling ("flip-flop") technique, with different sizes of gold particles, all possible paired combinations of the three different types of peptide have been visualised within granules of the anterior neurones, leading to the conclusion that the three peptides are co-packaged and co-stored in these cells. Within the posterior neurones of L. oleracea, gold labelling of granules is only linked to the Y/FXFGL-NH2 allatostatin antisera and, in contrast to the anterior cells of this species in which double gold labelling results in a sparse accumulation of gold particles for any one peptide type, single labelling gives a more intense, uniform pattern of gold particles. In contrast to L. oleracea, the gold-labelling pattern seen in the posterior neurones of H. armigera reflects the co-localisation of allatostatins of the Y/FXFGL-NH2 type with Mas-AS in this species. Allatotropin is absent in the posterior neurones of both species.

Helicostatins: brain-gut peptides of the moth, Helicoverpa armigera (Lepidoptera: Noctuidae).

Gene expression and immunolocalisation studies have determined that the helicostatins are brain-gut peptides in larvae of the lepidopteran, Helicoverpa armigera. Mapping of the distribution of these peptides in the nervous system and alimentary canal has provided evidence for multifunctional regulatory roles. In situ hybridisation studies have shown that the helicostatin precursor gene is expressed in neurones of the central and stomatogastric nervous systems, and endocrine cells of the midgut demonstrating that the helicostatins are true brain-gut peptides. Antisera raised against Leu-callatostatin 3 (ANRYGFGL-NH(2)), a peptide isolated from the blowfly, Calliphora vomitoria was used to map the distribution of allatostatin-like immunoreactive (Ast-ir) material in H. armigera to elucidate possible functions of the helicostatins. In situ hybridisation studies verified that the helicostatin precursor gene is expressed in neurones shown to contain Ast-ir, providing strong evidence that the Ast-ir material is helicostatins. Extensive immunoreactive axonal projections into complex regions of neuropile indicate that the helicostatins may have a neuromodulatory role in the brain and segmental ganglia of the ventral nerve cord. The presence of large amounts of immunoreactive material in axons within the corpora cardiaca (CC) and transverse nerves of the perisympathetic nervous system, two known neurohaemal organs, provides evidence for a neurohormonal role. The corpora allata (CA) were innervated only sparsely by Ast-ir axons suggesting that the CA are not a neurohaemal release site or a target. Thus, it is unlikely that the helicostatins regulate juvenile hormone (JH) biosynthesis or release. Ast-ir axons extended from the frontal ganglion through the recurrent nerve and many branches were closely associated with muscles of the foregut, stomodeal valve, and anterior midgut, implicating helicostatins in regulation of foregut motility. Ast-ir material was also present in nerves associated with muscles of the pyloric valve and rectum, and in endocrine cells of the midgut.

Allatostatins and allatotropin in the corpus cardiacum/corpus allatum complex of larval and adult lepidopterans studied by confocal laser scanning microscopy: correlation to juvenile hormone biosynthesis.

Peptidergic innervation of the corpus cardiacum/corpus allatum (CC/CA) retrocerebral complex, and neurosecretory areas of the brain of the lepidopterans Lacanobia oleracea, Heliothis virescens and Manduca sexta was studied by immunocytochemistry linked to confocal laser scanning microscopy. The patterns of immunostaining resulting from the simultaneous application of fluorochrome-conjugated antibodies against Manduca sexta allatostatin (Mas-AS), M. sexta allatotropin (Mas-AT), and a representative of the -Y/FXFGL-NH(2) superfamily of allatostatins was correlated with the physiological effects of these putative allatoregulatory peptides on juvenile hormone (JH) biosynthesis by the corpora allata. Whereas the two types of allatostatin immunoreactivity are present in both larval and adult CA of the three species, allatotropin immunoreactivity occurs only in the adult gland. The conclusion that withdrawal of the stimulatory effect of allatotropin is unlikely to be involved in the downregulation of CA activity prior to the onset of metamorphosis, but that an inhibitory influence of at least Mas-AS is important, is borne out in physiological experiments on JH biosynthesis in M. sexta larvae (Mas-AS inhibitory, Mas-AT without effect). Immunoreactivity to the Y/FXFGL-NH(2) allatostatins is present in both larval and adult CA and CC, frequently co-localised with Mas-AS. The function of this peptide family in the retrocerebral complex remains enigmatic since experiments on JH biosynthesis, either when the peptide is administered alone, or together with Mas-AS, show no effect on JH biosynthesis.

Allatostatins of the tiger prawn, Penaeus monodon (Crustacea: Penaeidea).

More than 40 peptides belonging to the -Y/FXFGL-NH(2) allatostatin superfamily have been isolated and identified from the central nervous system (CNS) of the tiger prawn, Penaeus monodon (Crustacea: Penaeidea). The peptides can be arranged in seven sub-groups according to the variable post-tyrosyl residue represented by Ala, Gly, Ser, Thr, Asn, Asp, and Glu. Two of the residues (Thr and Glu) have not been observed in this position previously in either insects or crustaceans. Also reported for the first time for allatostatins, two of the peptides are N-terminally blocked by a pyroglutamic acid residue. The yields of certain peptides with similar amino acid sequences to each other were, in some instances, very different. As an example, the yield of ANQYTFGL-NH(2) was 2pmol, compared with ASQYTFGL-NH(2), with a yield of 156 pmol. There are several possibilities to account for this. If, as in all species so far investigated, there is a single allatostatin gene in P. monodon, then it would appear that different sub-populations have contributed mutant forms of particular peptides to the extract. Another, less likely possibility is that this species has more than one allatostatin gene, producing a variable array of peptides albeit in different molar ratios. Several peptides were present apparently as a result of the loss of one or more residues at the N-terminus of a larger form, either due to N-terminal degradation or specific post-translational processing. The number of peptides identified exceeds that for any other insect or crustacean species previously investigated. None is identical to any of the 60-70 insect allatostatins so far identified, and only three are common to other crustaceans. Immunohistochemical study of the CNS of P. monodon, with the same antisera as used to monitor the purification, confirms the widespread nature and complexity of allatostatinergic neural pathways in arthropods. Thus, all neuromeres of the brain, and all except one of the ventral cord ganglia, possess allatostatin neurons and extensive areas of allatostatin-innervated neuropile. In addition to the cytological evidence that the allatostatins act as neurotransmitters, associated with tissues as varied as eyes and legs, their presence in neurohemal areas such as the sinus gland and the perineural sheath of the thoracic ganglia suggests a neuroendocrine function. As well as posing a challenge to physiologists assigning specific functions to the allatostatins, their extensive intra-species multiplicity, linked to their inter-species variability, also presents a complex problem to geneticists and evolutionists.