In vitro study of the action of adipokinetic hormone in locusts

The in vitro study was performed in order to demonstrate the structural changes of lipophorin induced in vivo by the injection of adipokinetic hormone (AKH) into adult locusts. After many unsuccessful attempts, we have established the reconstructed incubation system in which purified lipophorin and apolipophorin-III (9 mol/mol lipophorin) are incubated with the fat body in the presence of AKH under a supply of excess oxygen. In this system, high density lipophorin (HDLp) originally present in the incubation medium can be transformed entirely into low density lipophorin (LDLp) due to the loading of an increased amount of diacylglycerol from the fat body. The LDLp formed in this incubation system was exactly the same as the LDLp formed in vivo by the injection of AKH, in terms of density, particle size, diacylglycerol content, and the association with apolipophorin-III (apoLp-III). In the absence of apoLp-III, AKH did not exhibit its function to any extent. It was also demonstrated that the transformation of HDLp to LDLp requires calcium ions. Moreover, it appears that, up to a certain limit, the increase of diacylglycerol content of lipophorin and the amount of apoLp-III associated with lipophorin is nearly proportional to the amount of apoLp-III added to the incubation medium.

Stage-specific phosphorylation of the fushi tarazu protein during Drosophila development

The regulatory protein encoded by the fushi tarazu (ftz) gene is expressed during three different stages of Drosophila embryogenesis in three different developing tissues. Previously, we demonstrated that ftz protein ectopically expressed throughout developing embryos under the control of an hsp70 heat shock promoter is heavily modified. Here we show that these negatively charged isoforms of the protein are the result of phosphorylation at as many as 16 sites. Phosphate groups could be removed in vitro by treatment with various phosphatases and could be added in vivo by incubating embryo-derived cells or nuclei in the presence of [32P]-orthophosphate. Phosphoamino acid analysis of immunoprecipitated ftz protein yielded both phosphoserines and phosphothreonines at a ratio of approximately 1:1. Interestingly we find that the endogenous ftz protein is also phosphorylated at multiple sites and that different subsets of the phosphoisoforms occur during different stages of development.

Isolation, structure, and expression of labial, a homeotic gene of the Antennapedia Complex involved in Drosophila head development

The labial (lab) gene of Drosophila melanogaster is necessary for the proper development of the embryonic (larval) and adult head. We have identified the lab transcription unit within the proximal portion of the Antennapedia Complex (ANT-C) by mapping the molecular lesions associated with chromosomally rearranged lab alleles. We present its molecular structure, nucleotide sequence, and temporal pattern of expression. In addition, using antibodies generated against a fusion protein, we show that in the embryo the lab protein is distributed in neural and epidermal cells of the procephalic lobe; in a discrete loop of the midgut; and in specific progenitor sensory cells of the clypeolabrum, thoracic segments, and tail region. The regions of lab expression in the developing cephalon represent nonsegmented domains that are anterior to and largely nonoverlapping with the domains of expression of the Deformed (Dfd) and proboscipedia (pb) genes, two other homeotic loci of the ANT-C that also function to direct the development of head structures. Furthermore, lab head expression is associated with the complex cellular movements of head involution, a process that not only is defective in lab embryos, but the failure of which appears to be largely responsible for the defects observed in mutant embryos. Finally, we suggest that lab head expression provides a molecular marker for an intercalary segment, an ancestral segment that has become morphologically indistinct during the evolution of the insect head.

Biosynthesis of adipokinetic hormones (AKHs): further characterization of precursors and identification of novel products of processing

Two adipokinetic hormones (AKH I: pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2, and AKH II: pGlu-Leu-Asn-Phe-Ser-Thr-Gly-Trp-NH2) are synthesized by the neurosecretory cells of the corpora cardiaca (CC) of the locust Schistocerca gregaria. Both AKHs are released into the blood during flight and serve to regulate lipid metabolism and other physiological processes involved in flight. By in vitro "pulse-chase" experiments we show that 2 precursors (P1 and P2) are involved in AKH biosynthesis. These are about 8.4 kDa polypeptides which are AKH immunoreactive but also contain an amino acid (tyrosine) not present in the AKH peptides. By following the fate of 14C-tyrosine incorporated into P1 and P2, we have identified 2 novel products of precursor processing. These are called AKH-Precursor Related Peptides or APRP 1 and APRP 2. Size exclusion chromatography shows that the APRPs are about 6.5 kDa large and therefore represent major fragments of the precursors. The optical density peaks corresponding to P1, P2, APRP 1, and APRP 2 on a reverse-phase chromatogram are identified. The precursors being metabolic intermediates are represented by minor optical density peaks that disappear when de novo protein synthesis is blocked by cycloheximide. In contrast, the APRPs are represented by major optical density peaks consistent with their being accumulating end products of AKH precursor processing. The function of the APRPs is as yet unknown. They are, however, co-synthesized and also co-released with the AKHs, and may therefore also have hormonal functions related to flight.

Ionic dependence of depolarization-mediated adipokinetic hormone release from the locust corpus cardiacum

The locust corpus cardiacum (CC) is a peripheral neurohemal organ in which are clustered a prodigious array of neurosecretory cells (NSCs), nearly all of which synthesize and release adipokinetic hormones (AKHs). We have examined the extracellular requirements for Na+ and Ca2+ in the process of AKH release following NSC depolarization by high extracellular K+ or veratridine. Na+ is not required for release mediated by high external K+ although Ca2+ is. The Ca2+ channel antagonists cobalt and lanthanum prevent release and support the hypothesis that depolarization with K+ leads to Ca2+ channel activation and subsequent AKH release. Tetrodotoxin does not block K+-mediated release suggesting that Na+ channel activation and Na+ influx are not required for K+-mediated release. The alkaloid veratridine leads to cobalt- and tetrodotoxin-sensitive release and this suggests that cell depolarization by Na+ channel activation is nevertheless capable of opening Ca2+ channels and initiating release. Release mediated by high external K+ is reduced by nifedipine but is not significantly reduced by methoxyverapamil, however veratridine-mediated release is slightly reduced by methoxyverapamil. Glandular lobes accumulated greater amounts of 45Ca2+ following high K+-mediated depolarization compared to glands incubated in normal saline and this enhanced accumulation was blocked by the Ca2+ channel antagonist lanthanum. During prolonged exposure to high K+ saline the release of AKHs and the uptake of 45Ca2+ reach a maximum and then gradually decline. The temporal pattern of the reduction in AKH release is similar to that of 45Ca2+ accumulation by the glandular lobe. This reduction in AKH release and 45Ca2+ uptake may result from inactivation of Ca2+ channels associated with the release process. These results indicate that Ca2+ influx into the NSCs by way of voltage-sensitive Ca2+ channels plays a critical role in the process of depolarization-mediated AKH release.

Simulation of the activation of fat body glycogen phosphorylase and trehalose synthesis by peptide hormones in the American cockroach

A model is described which simulates activation of glycogen phosphorylase and induction of trehalose synthesis in the fat body of the American cockroach, Periplaneta americana, by two hypertrehalosaemic peptides. Parameters for the model were estimated from literature data (Siegert et al., Insect Biochem. 16, 365), with the exception of the half-life of the physiologically active peptides, which was estimated from the model. The model describes satisfactorily the activation of glycogen phosphorylase and the increase of haemolymph carbohydrates, which is dependent on the activation of glycogen phosphorylase in the model. It further explains the observed differences in sensitivity for glycogen phosphorylase activation and increase in haemolymph carbohydrates by these peptides. Best fits were obtained with a physiological half-life of about 12-15 min for the peptides. This value is similar to what can be calculated from the in vivo effects of these peptides on heart beat (Gersch et al., Zool. Jb. Physiol. 86, 17), but it is considerably shorter than the published half-life of 1 h for radioactive peptide (Skinner et al., Insect Biochem. 17, 433). However, both values are compatible if part of the peptides in the haemolymph is not present in freely dissolved form, but bound to a haemolymph component. The model half-life would then represent the half-life of the free, physiologically active peptide, which was estimated from the disappearance of radioactive peptide to be about 12-15 min. This suggests, that the model half-life is realistic and physiologically more important than the half-life of radioactive peptide of 1 h.

An Ultrabithorax protein binds sequences near its own and the Antennapedia P1 promoters

The homeotic gene Ultrabithorax (Ubx), located in the bithorax complex of Drosophila, encodes a family of closely related proteins that direct the developmental fates of posterior thoracic and anterior abdominal metameres. We have purified a member of the Ubx protein family from an overproducing E. coli strain and have shown that it is sequence-specific DNA binding protein. The protein binds tightly to sequences near its own promoter and near the P1 promoter of Antenna-pedia (Antp), a homeotic gene Ubx is known to repress from genetic studies. The binding sites occur in clusters downstream of the transcription start sites, and far upstream at Antp P1. They range in size from 40 to 90 bp, and contain tandem repeats of the trinucleotide TAA or the related hexanucleotide TAA-TCG. These results suggest that the regulatory activities of Ubx are direct and are mediated by binding of Ubx proteins to promoter region sequences.

Characterization and cDNA cloning of the pheromone-binding protein from the tobacco hornworm, Manduca sexta: a tissue-specific developmentally regulated protein

cDNA encoding pheromone-binding protein (PBP), the major soluble protein in olfactory sensilla of male moths, has been cloned from the tobacco hornworm, Manduca sexta. A study of the developmental time course of PBP reveals that it is first synthesized just prior to eclosion and that the percentage of antennal mRNA encoding PBP shifts from zero to about 20% at that time. PBP is also found in sensilla from female M. sexta antennae. No amino acid sequence homology is observed between PBP and the vertebrate odorant-binding protein.

A chemically synthesized Antennapedia homeo domain binds to a specific DNA sequence

A peptide 60 residues in length that corresponds to the homeo domain of Antennapedia (Antp), a protein governing development in Drosophila, was synthesized by segment condensation with protected peptide segments prepared on an oxime resin. A footprinting assay showed that the homeo domain binds specifically to a TAA repeat DNA sequence in the Antp gene. Thus the Antp homeo domain has a sequence-specific DNA binding property. The circular dichroism spectra of the homeo domain peptide showed the presence of a significant amount of alpha-helical structure in aqueous solution and in 50 percent trifluoroethanol. The alpha helicity measured in water appears to depend on the peptide concentration, which suggests that the peptide aggregates. These results support the hypothesis that the homeo domain binds to DNA through a helix-turn-helix motif.

Neuropeptide-degrading endopeptidase activity of locust (Schistocerca gregaria) synaptic membranes

Locust adipokinetic hormone (AKH, pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) was used as the substrate to measure neuropeptide-degrading endopeptidase activity in neutral membranes from ganglia of the locust Schistocerca gregaria. Initial hydrolysis of AKH at neural pH by peptidases of washed neural membranes generated pGlu-Leu-Asn and Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2 as primary metabolites, demonstrating that degradation was initiated by cleavage of the Asn-Phe bond. Amastatin protected the C-terminal fragment from further metabolism by aminopeptidase activity without inhibiting AKH degradation. The same fragments were generated on incubation of AKH with purified pig kidney endopeptidase 24.11, and enzyme known to cleave peptide bonds that involve the amino group of hydrophobic amino acids. Phosphoramidon (10 microM), a selective inhibitor of mammalian endopeptidase 24.11, partially inhibited the endopeptidase activity of locust neural membranes. This phosphoramidon-sensitive activity was shown to enriched in a synaptic membrane preparation with around 80% of the activity being inhibited by 10 microM-phosphoramidon (IC50 = 0.2 microM). The synaptic endopeptidase was also inhibited by 1 mM-EDTA, 1 mM-1,10-phenanthroline and 1 microM-thiorphan, and the activity was maximal between pH 7.3 and 8.0. Localization of the phosphoramidon-sensitive enzyme in synaptic membranes is consistent with a physiological role for this endopeptidase in the metabolism of insect peptides at the synapse.

A calmodulin-sensitive adenylate cyclase in the prothoracic glands of the tobacco hornworm, Manduca sexta

The Ca2+/calmodulin (CaM) dependence of adenylate cyclase activity in Manduca sexta prothoracic glands was investigated. Membrane fractions from two developmental stages were used, day 3 of the last larval instar and day 0 of the pupal stage, both of which respond to the neuropeptide prothoracicotropic hormone (PTTH) with increased cAMP production dependent on extracellular Ca2+. The data revealed that both larval and pupal prothoracic gland membrane fractions have a Ca2+/CaM-dependent adenylate cyclase which is inhibited by CaM antagonists and EGTA. The larval adenylate cyclase shows a multiphasic response to Ca2+/CaM, with a 2-fold stimulation between 0.02 and 0.01 microM, a further increase in adenylate cyclase activity at concentrations greater than 2 microM and a potentiation of NaF-stimulated activity at doses greater than 0.1 microM Ca2+/CaM. Pupal prothoracic gland membrane fractions exhibit only the second phase of stimulation. Stimulation by the GTP analogs GTP-gamma-S and Gpp(NH)p is dependent on CaM in larval, but not in pupal membrane fractions, suggesting a role for CaM in Gs protein-mediated regulation of adenylate cyclase. However, adenylate cyclase activity in glands from both stages is dependent on CaM, supporting our initial premise that Ca2+ is required for cAMP synthesis in the prothoracic glands.

Binding and action of cecropin and cecropin analogues: antibacterial peptides from insects

The mechanism of action of cecropin was studied by using liposomes as a model system. The bilayer was efficiently destroyed if the liposome net charge was zero or negative. Cecropin analogues with an impaired N-terminal helix had reduced membrane disrupting abilities that correlate with their lower antibacterial activity. The reduced bactericidal activity of the analogues was rationalized in terms of reduced binding to bacteria. The stoichiometry of cecropin killing of bacteria suggests that amounts of cecropin sufficient to form a monolayer strongly modify the bacterial membrane. Although some bacteria were resistant to cecropin they did bind large amounts in a non-productive manner. In contrast, mammalian erythrocytes achieve resistance by avoiding the binding of cecropin.

The EGPs: the eclosion hormone and cyclic GMP-regulated phosphoproteins. II. Regulation of appearance by the steroid hormone 20-hydroxyecdysone in Manduca sexta

Two proteins (the EGPs) in the CNS of the tobacco hornworm Manduca sexta are phosphorylated by the action of the neuropeptide eclosion hormone (EH), which triggers ecdysis behavior (Morton and Truman, 1986, 1988). The onset of sensitivity to EH requires prior exposure to the steroid hormone 20-hydroxyecdysone (20-HE). A series of steroid removal and replacement experiments indicates that the EGPs are also regulated by 20-HE with a time course that is similar to that seen for the 20-HE regulation of behavioral sensitivity to EH. This suggests that the steroid regulation of EH sensitivity is due to the regulation of the EGPs. The appearance of the EGPs requires not only the presence of 20-HE, but also its subsequent removal. The appearance of the EGPs can be blocked in vivo and in vitro by maintaining artificially elevated levels of 20-HE, but only up to a particular time in development. The ending of this steroid-sensitive period occurs 4 hr before the normal appearance of the EGPs, consistent with the hypothesis that the EGPs are synthesized de novo in response to the removal of 20-HE.

The EGPs: the eclosion hormone and cyclic GMP-regulated phosphoproteins. I. Appearance and partial characterization in the CNS of Manduca sexta

The present study describes 2 phosphoproteins, both with an apparent molecular weight of 54 kDa, in the CNS of the tobacco hornworm, Manduca sexta. Their phosphorylation is regulated by a neuropeptide, eclosion hormone (EH), and the second messenger cGMP, which thus have been named the EGPs (eclosion hormone- and cGMP-regulated phosphoproteins). Although cAMP was more effective than cGMP at stimulating the phosphorylation of the EGPs in CNS homogenates, in the intact CNS cGMP was more effective. Since cGMP mediates the action of EH, this strongly suggests that cGMP is the second messenger that stimulates the phosphorylation of the EGPs in vivo. The EGPs can only be phosphorylated in vitro during discrete time periods during the life of Manduca. During the larval and pupal molts, the EGPs can first be phosphorylated just prior to ecdysis. Their ability to be phosphorylated is correlated with the time when the insect is sensitive to EH. This close temporal correlation suggests that the ability to phosphorylate the EGPs determines when the insect can first respond to EH. During adult development, the EGPs first appeared on fluorograms 6 d before sensitivity to EH, suggesting that at this stage other factors may also be involved in the regulation of sensitivity. For the ecdyses of all 3 stages, EH appeared to stimulate the phosphorylation of the EGPs at ecdysis. The EGPs were found in all regions of the prepupal nervous system that were investigated, but only in the abdominal and pterothoracic ganglia of the developing adult. Fractionation of nervous system homogenates by ultracentrifugation revealed that one of the EGPs was present only in the pellet fraction, whereas the other was approximately equally distributed between pellet and supernatant. Furthermore, the EGPs in the pellet fraction could be partially solubilized with detergents and high salt concentrations.

Heterogeneous glycosylation of Musca domestica arylphorin

Two distinct fractions of Musca domestica arylphorin were isolated by affinity chromatography on Concanavalin A-Sepharose column. The results show that in the hexameric arylphorin that do not bind to the lectin there is no Concanavalin A binding subunit and in the majority of the hexamers that bind to the lectin there is only one subunit with Concanavalin A binding site. The results indicate that the carbohydrate moiety of the arylphorin is not involved in its specific uptake by the fat bodies and integument.

The influence of Blastocrithidia triatomae (Trypanosomatidae) on the reduviid bug Triatoma infestans: in vivo and in vitro diuresis and production of diuretic hormone

The homoxenous flagellate Blastocrithidia triatomae disturbs excretion in Triatoma infestans. During the first 4 and 24 h after feeding, infected 5th instars excreted approximately a 2.5-fold smaller volume of urine. Consequently, about double the normal volume of haemolymph could be obtained from these infected bugs 24 h after feeding. Surprisingly, the in vitro secretion rates of Malpighian tubules from uninfected and infected bugs were nearly identical. In addition, the storage and release of diuretic hormone in infected bugs was sufficient to induce normal secretion rates by isolated Malpighian tubules. Therefore, the previously observed ultrastructural alterations in the upper Malpighian tubules of infected bugs do not result in a disturbed in vitro secretion, although in vivo excretion is reduced.

Caenorhabditis elegans: occurrence and metabolism of ecdysteroids in adults and dauer larvae

1. Ecdysteroids were detected in extracts of egg-producing adult Caenorhabditis elegans, in dauer larvae and in dietary bacteria. 2. Similar concentrations of free ecdysteroids were recorded in adults and larvae, although the two life cycle stages differed in their ratio of ecdysone: 20-hydroxyecdysone. 3. Patent adults metabolized [3H]ecdysone into apolar products and putative [3H]ecdysone 22-phosphate.

Regulation of adipokinetic hormone release from locust neuroendocrine tissue: participation of calcium and cyclic AMP

In the locust, cyclic adenosine monophosphate (cAMP) mediates at least part of the effects of octopamine, the neurotransmitter which regulates the release of two adipokinetic hormones (AKHs) from the glandular lobe of the corpus cardiacum (CC). We have examined the requirement for extracellular Ca2+ in the process of AKH release mediated by octopamine and by agents which artificially elevate intracellular cAMP levels. Octopamine and the adenylate cyclase activator forskolin elevate the cAMP content of the glandular lobe in normal saline, in normal saline with the Ca2+ channel blocker, methoxyverapamil, and in Ca2+-free saline during 10-min exposure periods. Octopamine, forskolin, and 8-bromo cAMP mediate release of AKHs in vitro in normal saline, but release is prevented in the absence of extracellular Ca2+. When glands are exposed to these agents in normal saline in the presence of methoxyverapamil, AKH release is curtailed in a similar manner. Lanthanum and EGTA dramatically reduce cAMP production elicited by octopamine and forskolin, and lanthanum prevents octopamine-mediated release of AKHs. The phosphodiesterase inhibitor, IBMX, elevates cAMP content in the presence and absence of extracellular Ca2+, and stimulates normal release of AKHs both in the presence and absence of extracellular Ca2+. However, following extensive washing in Ca2+-free saline, IBMX fails to evoke AKH release. Methoxyverapamil has no effect on IBMX-mediated secretion. These results suggest that IBMX may mobilize intracellular stores of Ca2+ to induce release. Extracellular Ca2+ is apparently required for the process of neurotransmitter-evoked release, as has been shown for release of other peptide hormones. Cyclic AMP is intimately associated with Ca2+ in mediating this process. The release of AKHs is more dependent upon extracellular Ca2+ than is cAMP production under the conditions examined in this study. Ca2+ may provide the signal which initiates the secretory response, although cAMP may modulate this signal or the cells' responsiveness to this signal in some way. Support for this hypothesis is provided by experiments with the Ca2+ ionophore, A23187. This agent provokes release of AKHs in a Ca2+-dependent manner, probably by elevating intracellular Ca2+ levels. A23187 does not elevate cAMP levels in the glandular lobe, indicating that cAMP elevation is not a prerequisite for secretion.

Localization of the sevenless protein, a putative receptor for positional information, in the eye imaginal disc of Drosophila

The Drosophila gene sevenless encodes a putative trans-membrane receptor required for the formation of one particular cell, the R7 photoreceptor, in each ommatidium of the compound eye. Mutations in this gene result in the cell normally destined to form the R7 cell forming a non-neuronal cell type instead. These observations have led to the proposal that the sevenless protein receives at least part of the positional information required for the R7 developmental pathway. We have generated antibodies specific for sevenless and have examined expression of the protein by light and electron microscopy. sevenless protein is present transiently at high levels in at least 9 cells in each developing ommatidium and is detectable several hours before any overt differentiation of R7. The protein is mostly localized at the apices of the cells, in microvilli, but is also found deeper in the tissue where certain cells contact the R8 cell. This finding suggests that R8 expresses a ligand for the sevenless protein.

The sevenless+ protein is expressed apically in cell membranes of developing Drosophila retina; it is not restricted to cell R7

In the sevenless (sev) mutants of Drosophila, a single cell type, photoreceptor R7, does not develop. We made monoclonal antibody against a sev+-beta-galactosidase fusion protein, and used it to determine the ultrastructural localization of the sev+ protein in the larval eye disc. The protein is expressed on the apical surface of the developing retina. It is not restricted to cell R7; it is expressed in all the presumptive photoreceptor cells, cone cells, and possibly others. The protein localizes to the cell membranes of the apical tips and their microvilli, away from the bulk of the cell-cell contacts. Possible mechanisms for generating the specificity of the sev phenotype are discussed in light of these results.

Possible involvement of lumichrome in the binding of storage protein to its receptor in Sarcophaga peregrina

Previously, a receptor molecule on the surface of fat body cells of Sarcophaga peregrina larvae that is involved in the uptake of storage protein from the hemolymph was shown to be a 120-kDa protein (Ueno, K., and Natori, S. (1984) J. Biol. Chem. 259, 12107-12111). This paper reports evidence that lumichrome (7,8-dimethylalloxazine) may be present in the binding site of the receptor and mediate the binding of storage protein and receptor. A stoichiometric amount of lumichrome was shown to bind to the storage protein under conditions in which the latter bound to its receptor.

The parasitoid Apanteles kariyai inhibits pupation of its host, Pseudaletia separata, via disruption of prothoracicotropic hormone release

When the parasitoid Apanteles kariyai laid eggs into host Pseudaletia separata larvae, before prothoracicotropic hormone (PTTH) was released in the last instar preparatory to metamorphosis, the host did not pupate and the larvae of the wasps emerged. The ecdysteroid titer of unparasitized intact larvae increased up to 1 microgram/ml 1 day before pupation, whereas the titer of parasitized larvae was maintained at a low level without the surge. Isolated prothoracic glands from intact larvae synthesized much more ecdysone than those of parasitized larvae both in vivo and in vitro. Administration of exogenous PTTH caused the activation of the prothoracic glands seen during parasitization. Injection of 20-hydroxyecdysone (20-HE) into the parasitized larvae caused by host's pupation, but did not affect the development of the wasp larvae. However, the sensitivity of the integument to 20-HE was lower in parasitized than in unparasitized larvae. Injection of a mixture of adult wasp calyx and venom fluids into last instar unparasitized larvae delayed their pupation, suggesting that calyx and venom fluids are factors contributing to disturbance of the normal function of brain-prothoracic gland system. These results show that parasitization inhibits secretion and/or synthesis of PTTH and also delays the larval-pupal commitment of the integument by keeping the ecdysteroid level low.

Chemistry of pheromone and hormone metabolism in insects

Chemical evidence is needed in both insect endocrinology and sensory physiology to understand hormone and pheromone action at the molecular level. Radiolabeled pheromones and hormones have been synthesized and used to identify binding and catabolic proteins from insect tissues. Chemically modified analogs, including photoaffinity labels and enzyme inhibitors, are among the tools used to covalently modify the specific acceptor or catalytic sites. Such targeted agents can also provide leads for the design of growth and mating disruptants by allowing manipulation of the physiologically important interactions of the chemical signals with macromolecules.

Production and characterization of antibodies to neuroparsins A and B isolated from the corpora cardiaca of the locust

Antisera were raised in rabbits against neuroparsins A and B which were purified to near homogeneity using electroelution from 7.5% polyacrylamide electrophoresis gels. They were characterized using immunohistochemical, enzyme-linked immunosorbent assay (ELISA), and protein-blotting methods. The antineuroparsin A and the antineuroparsin B sera have different titers and sensitivities (higher titer for antineuroparsin A, higher sensitivity for antineuroparsin B). They exhibit very good specificity. The immunohistochemical study of the entire central nervous system using either antineuroparsin A or antineuroparsin B sera shows that only the A1 type of the protocerebral median neurosecretory cells are immunostained. Moreover, among the numerous proteins of the median region of the brain and of the corpora cardiaca, each immune serum recognized only neuroparsin A or neuroparsin B. Displacement curves obtained for each immune serum by competition between either neuroparsin A or neuroparsin B demonstrate that the neuroparsin A is recognized as well as neuroparsin B, with both antisera supporting the concept that these two proteins are chemically related. The nonspecific binding of neuroparsins to an antisomatostatin immune serum used at 1/100 dilution indicates that any cross-reactivities of invertebrate molecules obtained with very low dilutions of antisera to vertebrate molecules must be considered carefully before concluding any immunological relation between invertebrate and vertebrate products.

The product of the Drosophila zeste gene binds to specific DNA sequences in white and Ubx

Three different segments of the zeste coding sequence were inserted in an expression vector and antibodies were raised against the resulting zeste-beta galactosidase hybrid proteins. The antibodies were used to analyse the zeste protein produced in bacteria from a different expression vector containing the entire zeste coding region. The major products made in bacteria as well as the products of in vitro translation of zeste RNA migrate anomalously upon SDS--acrylamide gel electrophoresis. Specific DNA fragments from the white and Ubx gene co-immunoprecipitate with zeste protein. At least two independent zeste binding sites are found in a 250-bp interval of the white regulatory region that contains also the sites of wsp mutations, which are known to be deficient in zeste interaction.