EJE, vol. 96 (1999), issue 3

Evolution and function of the insect hexamerins

BURMESTER T.

Eur. J. Entomol. 96 (3): 213-225, 1999

Hexamerins are hemocyanin-related haemolymph proteins that are widespread in insects and may accumulate to extraordinarily high concentrations in larval stages. Hexamerins were originally described as storage proteins that provide amino acids and energy for non-feeding periods. However, in recent years other specific functions like cuticle formation, transport of hormones and other organic compounds, or humoral immune defense have been proposed. During evolution, hexamerins diversified according to the divergence of the insect orders. Within the orders, there is a notable structural diversification of these proteins, which probably reflects specific...

The evolution of sex chromosomes in insects: Differentiation of sex chromosomes in flies and moths

TRAUT W.

Eur. J. Entomol. 96 (3): 227-235, 1999

Although a monophyletic group, male (XX/XY) and female heterogametic (WZ/ZZ) sex chromosome systems with a couple of variants like XX/X, Z/ZZ and multiple sex chromosome systems occur in insects. Molecular and morphological differences between X and Y or W and Z range from imperceptible to conspicuous. This article illustrates sex chromosome differentiation mainly in two fly species, Drosophila melanogaster and Megaselia scalaris, and in Lepidoptera. The earliest phases of XY evolution are present in the fly M. scalaris. Occasionally in this species, the male determining gene jumps to another chromosome, transforming the new host...

Phylogeny of endopterygote insects, the most successful lineage of living organisms

KRISTENSEN N.P.

Eur. J. Entomol. 96 (3): 237-253, 1999

The monophyly of the Endopterygota is supported primarily by the specialized larva without external wing buds and with degradable eyes, as well as by the quiescence of the last immature (pupal) stage; a specialized morphology of the latter is not an endopterygote groundplan trait. There is weak support for the basal endopterygote splitting event being between a Neuropterida + Coleoptera clade and a Mecopterida + Hymenoptera clade; a fully sclerotized sitophore plate in the adult is a newly recognized possible groundplan autapomorphy of the latter. The molecular evidence for a Strepsiptera + Diptera clade is differently interpreted by advocates of parsimony...

Allatostatins and allatotropins: Is the regulation of corpora allata activity their primary function?

HOFFMANN K.H., MEYERING-VOS M., LORENZ M.W.

Eur. J. Entomol. 96 (3): 255-266, 1999

More than 60 neuropeptides that inhibit juvenile hormone synthesis by the corpora allata have been isolated from the brains of various insect species. Most of them are characterized by a common C-terminal pentapeptide sequence Y/FXFGL/I/V (allatostatin A family, allatostatin superfamily). Besides the allatostatin A family, allatostatic neuropeptides belonging to other two peptide families (W2W9)-allatostatins or allatostatin B family; lepidopteran allatostatin) were reported. So far, only one allatotropin has been identified. Here we discuss latest literature on the multiplicity and multifunctionality of the allatoregulating neuropeptides,...

Allatostatins in Gryllus bimaculatus (Ensifera: Gryllidae): New structures and physiological properties

LORENZ M.W., KELLNER R., HOFFMANN K.H.

Eur. J. Entomol. 96 (3): 267-274, 1999

Four peptides with allatostatic activity were isolated from brains of the Mediterranean field cricket, Gryllus bimaculatus. Three of them (Grb-AST A3: AGMYSFGL-NH2; Grb-AST A4: SRPFGFGL-NH2; Grb-AST A5: GPDHRFAFGL-NH2) belong to the wide-spread family of Y/FXFGL/I-amide peptides, the fourth (Grb-AST B5: AWDQLRPGW-NH2) is a member of the W2W9 - amide family of neuropeptides. All of these peptides are potent inhibitors of juvenile hormone (JH) biosynthesis by cricket corpora allata in vitro, causing 50% inhibition of JH biosynthesis at 0.4-3 10-8 M. The two peptides...

Myotropic neuropeptides from the retrocerebral complex of the stick insect, Carausius morosus (Phasmatodea: Lonchodidae)

PREDEL R., KELLNER R., GADE G.

Eur. J. Entomol. 96 (3): 275-278, 1999

Myotropic neuropeptides were isolated from the retrocerebral complex of the stick insect, Carausius morosus, by using three HPLC steps. Bioactivity during purification was measured by heterologous bioassays monitoring the contractions of the hyperneural muscle and hindgut of the American cockroach. Additionally, fractions not active in these bioassays were tested in a homologous bioassay evoking contractions of the hindgut of C. morosus. Peptide sequence analysis and mass spectrometry yielded the following structures: Pro-Phe-Cys-Asn-Ala-Phe-Thr-Gly-Cys-NH2 (CCAP), pGlu-Thr-Phe-Gln-Tyr-Ser-His-Gly-Trp-Thr-Asn-NH2...

Immunolocalization of two types of allatostatins in the central nervous system of the cricket Gryllus bimaculatus (Ensifera: Gryllidae)

WITEK G., VERHAERT P., LORENZ M.W., HOFFMANN K.H.

Eur. J. Entomol. 96 (3): 279-285, 1999

Two anti-peptide antisera (anti-A and anti-B) raised against Gryllus bimaculatus allatostatin A1 (Grb-AST A1) and B1 (Grb-AST B1), respectively, were applied in the peroxidase-antiperoxidase (PAP) immunohistochemical technique on complete series of sections from the brain, suboesophageal ganglion, corpora cardiaca (CC), and corpora allata (CA) of G. bimaculatus. Both antisera yielded intense staining of numerous cells and nerve fibres. Serial sections, alternately stained with anti-A and anti-B confirmed that the anti-B generally stained more cells and nerves. Extensive immunoreactivity in the retrocerebral complex suggests that the CC...

Juvenile hormone synthesis by corpora allata of tomato moth, Lacanobia oleracea (Lepidoptera: Noctuidae), and the effects of allatostatins and allatotropin in vitro

AUDSLEY N., WEAVER R.J., EDWARDS J.P.

Eur. J. Entomol. 96 (3): 287-293, 1999

The nature and rate of juvenile hormone (JH) biosynthesis and effects of allatostatins and allatotropin have been investigated in isolated corpora allata (CA) of adults and larvae of the noctuid tomato moth, Lacanobia oleracea. In adult female CA, mean rates of synthesis were relatively constant (10-16 pmol/pr/h) at all times. However, the range of JH synthesis by individual CA of similarly aged insects was quite large (2-30 pmol/pr/h). High performance liquid chromatography (HPLC) separation shows that adult female moth CA synthesise predominantly JH I and JH II. Rates of JH synthesis in vitro are dependent on methionine concentration. Synthetic...

Intracellular calcium in PTTH-stimulated prothoracic glands of Manduca sexta (Lepidoptera: Sphingidae)

BIRKENBEIL H.

Eur. J. Entomol. 96 (3): 295-298, 1999

Larval Manduca prothoracic gland cells in vitro responded to prothoracicotropic hormone (PTTH) from neurosecretory cells of the brain with an increase of intracellular free calcium. This effect is reversible and dose-dependent. Preincubation of the glands with TMB-8 and dantrolene, which inhibit the release of calcium from intracellular stores, did not decrease the PTTH-stimulated increase in calcium, indicating that intracellular calcium stores are not involved in the control of ecdysteroidogenesis. Pharmacological studies of the PTTH effect with calcium channel blockers revealed that the increase in calcium was totally blocked by cadmium,...

Metabolic neurohormones: Release, signal transduction and physiological responses of adipokinetic hormones in insects

VAN DER HORST D.J., VAN MARREWIJK W.J.A., VULLINGS H.G.B., DIEDEREN J.H.B.

Eur. J. Entomol. 96 (3): 299-308, 1999

In view of the extremely high metabolic rates involved, insect flight offers a fascinating model system for studying metabolism during exercise, including its regulation by metabolic neurohormones. In our laboratory the African migratory locust, Locusta migratoria, well-known for its long-distance flights, is used as an internationally recognized model insect. The insect is mass-reared under controlled conditions; its size permits convenient handling in vivo and in vitro, while flight activity can be easily evoked. In addition, research on this pest insect may be of economical importance.

A survey of the energy metabolism during locust...

Structure elucidation of Mas-AKH as the major adipokinetic hormone in the butterfly Vanessa cardui (Lepidoptera: Nymphalidae)

KOLLISCH G.V., VERHAERT P.D., LORENZ M.W., KELLNER R., GADE G., HOFFMANN K.H.

Eur. J. Entomol. 96 (3): 309-315, 1999

The presence of adipokinetic activity in crude extracts of corpora cardiaca (CC) from the butterfly (Vanessa cardui L., Nymphalidae) was demonstrated by bioassay and Mas-AKH was revealed as the major adipokinetic hormone (AKH) by use of two different technologies of sequence elucidation: HPLC separation of the peptide followed by Edman degradation and Q-TOF mass spectrometry. In contrast to the time- and material-consuming conventional methods of peptide purification and sequencing, substantial structural data of the peptide were confirmed - post factum - from one pCC (pair of CC) by Q-TOF mass spectrometry. Only males of our laboratory colony...

Activation of fat body in Periplaneta americana (Blattoptera: Blattidae) by hypertrehalosemic hormones (HTH): New insights into the mechanism of cell signalling

STEELE J.E.

Eur. J. Entomol. 96 (3): 317-322, 1999

In cockroaches and certain other insects the concentration of trehalose in the hemolymph is increased by hypertrehalosemic hormone (HTH), a neuropeptide originating in the corpus cardiacum. A vital step in the action of HTH to promote conversion of glycogen stored in the fat body to trehalose is the activation of phosphorylase. The means by which HTH activates phosphorylase, with particular emphasis on its role in the regulation of intracellular calcium, is discussed. Additional information supporting the view that HTH stimulated synthesis of trehalose, and possibly its release from the trophocyte, is regulated by fatty acids and eicosanoids is presented.

Immunocytochemical distribution of angiotensin-I converting enzyme in the central nervous system of insects and speculations about its possible function

VEELAERT D., SCHOOFS L., MACOURS N., VANDINGENEN A., DE LOOF A., ISAAC E., SALZET M., HUYBRECHTS R.

Eur. J. Entomol. 96 (3): 323-326, 1999

Insect peptidyl-dipeptidase A [angiotensin I - converting enzyme (ACE)] is a soluble single-domain peptidyl-dipeptidase that has many properties in common with the C-domain of mammalian somatic ACE and with the single-domain mammalian ACE. In agreement with a variety of insects, immunocytochemical studies reveal the presence of an ACE-like protein in Locusta migratoria. ACE-like immunoreactivity is present in neurosecretory cells of the pars intercerebralis. These cells have axons projecting into the nervus corporis cardiaci I and into the storage part of the corpus cardiacum, a neuroendocrine organ directly releasing into the aorta. The...

A Mediterranean population of Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae) exhibits wing morph-related differences in adipokinetic response

KODRIK D., SOCHA R.

Eur. J. Entomol. 96 (3): 327-330, 1999

Short-winged (brachypterous) and long-winged (macropterous) adult females of Pyrrhocoris apterus (L.) originating from a Mediterranean population (Israel) were analyzed for their adipokinetic responses. The adipokinetic response, expressed as an increase of haemolymph lipids after injection of adipokinetic hormone from Locusta migratoria (Lom-AKH-I), was assessed in relation to age and dose of the hormone. We demonstrate in this study that the adipokinetic responses induced by bug's corpora cardiaca extract and Lom-AKH-I were dose-dependent for both brachypterous and macropterous females. Significant differences between the morphs were...

Flight substrates in blister beetles (Coleoptera: Meloidae) and their regulation by neuropeptides of the AKH/RPCH family

GADE G., AUERSWALD L.

Eur. J. Entomol. 96 (3): 331-335, 1999

We measured energy substrates in haemolymph and flight muscles of the large blister beetle Mylabris oculata at rest and after tethered, lift-generating flight. Flight of 1 min duration at an ambient temperature of 38-42C did not effect a change in the concentration of lipids in the haemolymph, whereas a small, significant decrease in the concentrations of carbohydrates and a 3-fold larger one in the levels of proline were noted, as well as a concomitant increase in alanine. In the flight muscles, glycogen and proline concentrations were diminished slightly but significantly upon flight, whereas alanine levels were increased. Two hours of rest...

Conformational study on a representative member of the AKH/RPCH neuropeptide family, Emp-AKH, in the presence of SDS micelle

ZUBRZYCKI I.Z., GADE G.

Eur. J. Entomol. 96 (3): 337-340, 1999

Emp-AKH is a member of the large adipokinetic hormone (AKH) family of peptides. This peptide family appears to occur in the corpora cardiaca of all insect species and its members are involved in regulating substrate mobilisation. The secondary structure of Emp-AKH has been studied in the presence of sodium dodecyl sulfate micelles by comparing data obtained from Nuclear Magnetic Resonance and molecular dynamics simulations. The lowest energy conformer obtained in this study has a turn consisting of residues 5-8 and a tail consisting of the first five residues.