via the transcription factor Relish, a NFk-B homologue. Furthermore,we describe novel differential roles for each of the Drosophila cGKs,DG1 and DG2, in Relish activation, AMP production and fly survival.

These novel modulatory effects of DG1 and DG2 on the IMDpathway are not associated with the fat body but are effective via thetubules in natural infection assays, and thus constitute an endogenousmechanism of bacterial resistance.

doi:10.1016/j.cbpa.2008.04.319

A11.13Peptidergic regulation of physiology and behavior in insects

N. Tublitz (University of Oregon)

This talk discusses several separate mechanisms underlying pep-tidemediated neuroplasticity in insects. The first is at the cellular levelin the moth Manduca sexta. Manduca has a set of larval neurons thatexpress a subset of cardioacceleratory peptides (CAPs). During meta-morphosis these neurons undergo a complete transformation, chan-ging their physiological, biochemical and morphological properties.This cellular alteration is hormonally triggered by the insect steroidhormone 20-OH ecdysone. CAP expression in other neurons is alsosignificantly altered duringmetamorphosis. The secondpart of the talkwill focus on peptide mediated plasticity at the developmental levelin the fruit fly Drosophila melanogaster. Two CAPs, CCAP and CAP2b,are expressed in the mesodermally-derived midline mesoderm cells(MMCs) of Drosophila. The MMCs extend a neuronal-like process,express neuronal markers, have voltage-dependent channels, andcontain bioactive CAPs. These data suggest that the MMCs act asneurosecretory cells despite their non-neural origins. Other mechan-isms will also be presented.

doi:10.1016/j.cbpa.2008.04.320

A11.14Spatiotemporal filtering of mitochondrial calcium and its role inthe Drosophila Malpighian tubule

S. Terhzaz, P. Cabrero, S. Davies, J. Dow (University of Glasgow)

By generating Drosophila transgenic for both luminescent andfluorescent mitochondrial calcium reporters, we previously showedthat in tubule principal cells, mitochondrial calcium tracked changesin cytoplasmic calcium. This resulted in both increased mitochondrialmembrane polarisation and elevated cellular ATP levels — the apicalplasma membrane V-ATPase is a major consumer of ATP. Using mito-chondrial calcium imaging and a potential sensing dye, the apicalmitochondria of principal cells were found to be selectively responsiveto capa1 neuropeptide signalling. The results highlight the dynamicnature and both spatial and temporal heterogeneity of calcium sig-nalling possible in differentiated, organotypic cells; and also providesa new model for neuroendocrine control of V-ATPase.

A great advantage of working with Drosophila is the availability ofmutants for pathways of interest. We show here that themutants of thegene encodingmitochondrial ADP/ATP translocase, sesB, which fromourpublished microarray data is enriched in tubules, impact on mitochon-drial function. Based on the interaction between the mitochondrialpermeability transition (MPT) pore component sesB and Ca2+ signalling

we characterize the role of the two sesB isoforms (SesB-1 and SesB-2) inmitochondrial Ca2+ uptake. In parallel using confocal microscopy weassessed changes in mitochondrial biogenesis in sesB mutant flies.

doi:10.1016/j.cbpa.2008.04.321

A11.15Identified Drosophila ion transport peptide splice forms aredifferentially expressed in central and peripheral neuronsthroughout postembryogenesis

H. Dircksen, L. Kahsai, C. Albus, M. Mandali, D. Nässel (StockholmUniversity)

Insect ion transport peptides (ITPs) are members of a large familyof arthropod neuropeptides (72–87amino acids (aa) long) originallydefined by the homologous crustacean hyperglycemic hormones (CHHs).Insect and crustacean ITP/CHH gene are similar and their products areusually alternatively spliced into one amidated isoform of 72–73aa (ITP/CHH)which, in locusts, is known to have antidiuretic bioactivity, and intoone long isoform (ITPLN78aa) of unknown function. We have found, inDrosophila melanogaster, that the gene CG13586 gives rise to three iden-tified mRNAs encoding peptide isoforms, one short amidated DrmITP(73aa) and two other longer DrmITPLs (DrmITPL1 and DrmITPL2, both87aa). The peptides have been identified by biochemical analysesandmass spectrometry. In situ-hybridisation and immunocytochemistryfound short DrmITP in several larval neurons most of which even persistinto the adult stage: four novel pairs of neurons innervate the corporacardiaca and allata, and two pairs of hindgut-innervating neurons in theabdominal ganglia. In larvae and pupae, DrmITP-neurons exist as a pair inthe SOG, and one pair of peripheral bipolar LBD-neurons in closeproximity to the anal organ, a knownchloride-transportingorgan. Similarbipolar neurons were found on dorsal areas of adult ventral nerve roots.Further LBD and other peripheral neurons are the only site for longisoforms DrmITPL1/L2 of the larva and the adult. Colocalisations ofDrmITP with allatostatin-ir are found in hindgut innervating neurons.Partial overlapof branchesofDrmITPneuronswith thoseof clockneuronsoccurs in adult brains. Functional implications are currently investigated.

doi:10.1016/j.cbpa.2008.04.322

A11.16On the breathing patterns of Rhodnius prolixus

T. Bradley (University of California, Irvine)

The immoderate feeding habits of Rhodnius prolixus have made it afavorite object of study for insect physiologists. The periodic nature ofits meals allowed Wigglesworth to gain insights into the release ofhormones regulating molting, metamorphosis and growth. The vastsize of the meals and their liquid nature provided Maddrell withextraordinary material for examining the processes involved in iontransport in theMalpighian tubules. The size of themeals also dictatessubstantial increases in the rate of metabolism following feeding asthe meal is digested and protein synthesis proceeds prior to the nextmolt. The metabolic rate increases almost 10-fold over resting, pre-fedrates, although the insect is outwardly quiescent throughout. Rhod-nius exhibits a classic pattern of discontinuous respiration in the unfedstate. We have taken advantage of the insect's capacity to ramp up

S134 Abstracts / Comparative Biochemistry and Physiology, Part A 150 (2008) S131-S138