Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Manduca”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2000

Effects of Manduca diuresin on neonates of the tobacco hornworm, Manduca sexta.

Manduca diuresin (MD), a 30 amino acid peptide, was isolated and identified from the type IIb median neurosecretory cells in the brain of adult Manduca sexta (Blackburn et al., Biochem. Biophys. Res. Commun., 181, 927-932, 1991). The synthetic hormone stimulates water loss in the adult moth both in vitro using isolated Malphigian tubule preparations and in vivo using decapitated adult moths as bioassay animals (Blackburn and Ma, Arch. Insect Biochem. Physiol., 27, 3-10, 1994). In the present study, MD was shown to have adverse physiological effects on neonates of Manduca sexta when fed synthetic hormone-treated leaf discs. With a sustained diet of MD-treated discs, neonates exhibited symptoms of reduced food consumption and marginal weight increases. In addition to slowed growth and reduced developmental rates, a high percentage of these neonates failed to molt into second instar larvae and death usually followed shortly thereafter. This is a first report that a synthetic insect neuropeptide has shown detrimental effect on insect larvae by ingestion. The possibility of utilizing this peptide in plant protection is discussed.

Animals↗
PubMed1998

Inhibition of midgut ion transport by allatotropin (Mas-AT) and Manduca FLRFamides in the tobacco hornworm Manduca sexta.

Short-circuit current (Isc) across the posterior midgut of day 2 fifth-instar tobacco hornworms (Manduca sexta) is inhibited by Manduca allatotropin (Mas-AT) and two Manduca FLRFamides (F7G and F7D). Another FLRFamide, F10, and the related molluscan tetrapeptide FMRFamide elicited only a modest inhibition of Isc. Mas-AT, F7G and F7D inhibited the Isc in a dose-dependent manner. Maximal inhibition of Isc by Mas-AT was achieved at a concentration of 50 nmol l-1. At 100 nmol l-1, Mas-AT produced a significantly greater inhibition of Isc than did F7G and F7D. The inhibition caused by Mas-AT was reversed by removing the peptide. Furthermore, the action of Mas-AT could be blocked by preabsorption with its antiserum. When F7G or F7D was added after the Isc had been inhibited by Mas-AT, a further reduction in the Isc was observed. No additive effects were seen when F7G and F7D were added together. In comparison with the anterior and middle regions, the posterior section of the midgut was the most sensitive to these three peptides. The Isc of midguts dissected from feeding fourth instars was inhibited by Mas-AT, F7D and F7G, whereas the Isc of midguts dissected from pharate fifth instars or wandering fifth instars was virtually unaffected by these peptides. Active ion transport across the posterior midgut of the silk moths Hyalophora cecropia and Bombyx mori was unaffected by these peptides.

Amino Acid Sequence↗
PubMed2001

Remodeling of motor terminals during metamorphosis of the moth Manduca sexta: expression patterns of two distinct isoforms of Manduca fasciclin II.

During metamorphosis of the moth Manduca sexta, the neuromuscular system of the thoracic legs is reorganized dramatically. Larval leg muscles degenerate at the end of larval life, and new adult leg muscles develop during the ensuing pupal stage. Larval leg motoneurons persist, but undergo substantial remodeling of central and peripheral processes. As part of our on-going investigation of mechanisms underlying the remodeling of motor terminals, we have used antisera generated against Manduca-specific isoforms of the homophilic adhesion molecule fasciclin II (MFas II) to label motor terminals during metamorphosis. Antisera generated against the glycosyl-phosphatidylinositol (GPI) -linked isoform of MFas II (GPI-MFas II) labeled the motor nerves at all stages and seemed to be associated with glial cells ensheathing the peripheral nerves. In addition, the anti-GPI-MFas II antisera labeled regions associated with synaptic boutons at both larval and adult stages. In contrast, antisera generated against a transmembrane isoform of MFas II (TM-MFas II) only labeled specific neuronal processes at discrete intervals during remodeling. Identified leg motoneurons (such as the femoral depressor motoneuron) expressed detectable levels of TM-MFas II in their peripheral processes only during phases of motor-terminal retraction and initial stages of motor-terminal re-growth. Putative modulatory neurons (such as the unpaired median neurons), however, expressed TM-MFas II in their processes during larval stages as well as during remodeling. Use of the isoform-specific anti-MFas II antisera provided a novel method for visualizing remodeling of motor terminals during metamorphosis and helped distinguish different components of the motor nerves and neuromuscular junction.

Animals↗
PubMed2003

Cloning, expression, and characterization of diuretic hormone Manduca diuresin from Manduca sexta in Escherichia coli.

Manduca diuresin (MD), a 30 amino acid peptide isolated from the tobacco hornworm Manduca sexta, was found to play an important role in the regulation of water and salt balance in the insect. To facilitate studies relating to the function and structure of MD, a synthetic gene encoding MD was assembled and expressed in Escherichia coli. Using an excretion vector, expression of the MD gene in an induced transformant was detected at the transcriptional and translational levels by Northern-blot and ELISA analyses, respectively. With the use of glutathione-S-transferase as the reporter protein, MD was confirmed to be expressed in E. coli. The recombinant product was resolved by reverse-phase HPLC into three peptide groups of different retention times, which were shown by mass spectrometry to be composed of MD deletants missing various lengths of the C-terminus. Despite the deletions and the absence of an amidated C-terminus, the deletants were shown to be biologically active, suggesting the importance of the N-terminus of MD for biological activity.

Amino Acid Sequence↗
PubMed2005

Effects of Manduca allatotropin and localization of Manduca allatotropin-immunoreactive cells in earwigs.

Manduca sexta allatotropin (Manse-AT) was first isolated on the basis of its ability to stimulate production of juvenile hormone in that insect. We examined whether this neuropeptide affects corpus allatum activity and visceral muscle contraction in adult females of the earwig, Euborellia annulipes. We also assessed the presence of allatotropin-like material in tissues using immunocytochemistry. Manse-AT at 1 nM to 10 muM stimulated juvenile hormone production in vitro by glands of low activity from 2-day virgin females. In glands of high activity from 12-day mated females, 1 and 100 nM allatotropin were effective, but 10 muM was not. Similarly, hindguts of 2-day and 12-day females significantly increased in motility in vitro in response to Manse-AT. A monoclonal antibody to Manse-AT was used to demonstrate allatotropin-like material throughout the nervous system of 2-day, virgin females. Immunoreactivity was most pronounced within varicosities of the corpora cardiaca and perisympathetic organs. No immunofluorescence was observed in gut tissue. Lastly, we showed that extract of retrocerebral complexes also enhanced in vitro hindgut motility from 2-day virgin females, in a dose-dependent manner. These results indicate material similar to M. sexta allatotropin in female earwigs and that such peptides may modulate juvenile hormone biosynthesis and visceral muscle contractions. Sensitivity to the peptides may change with physiological stage.

Animals↗
PubMedDate not supplied

Interaction between Manduca sexta allatotropin and manduca sexta allatostatin in the fall armyworm Spodoptera frugiperda.

A peptide that strongly stimulates juvenile hormone (JH) biosynthesis in vitro by the corpora allata (CA) was purified from methanolic brain extracts of adult Spodoptera frugiperda. Using HPLC separation followed by Edman degradation and mass spectrometry, the peptide was identified as Manduca sexta allatotropin (Mas-AT). Treating the CA from adult S. frugiperda with synthetic Mas-AT (at 10(-6) M) caused an up to sevenfold increase in JH biosynthesis. The stimulation of JH synthesis was dose-dependent and reversible. Synthetic M. sexta allatostatin (Mas-AS) (10(-6) M) did not affect the spontaneous rate of JH secretion from CA of adult S. frugiperda, nor did any of the allatostatins of the Phe-Gly-Leu-amide peptide family tested. However, when CA had been activated by Mas-AT (10(-6) M), addition of synthetic Mas-AS (10(-6) M) reduced JH synthesis by about 70%. This allatostatic effect of Mas-AS on allatotropin-activated glands was also reversible. When CA were incubated in the presence of both Mas-AT (10(-6) M) and various concentrations of Mas-AS (from 10(-8) to 10(-5) M), the stimulation of JH-biosynthesis observed was inhibited in a dose-dependent manner. The experiments demonstrate a novel mechanism of allatostatin action. In S. frugiperda JH synthesis was inhibited only in those glands which had previously been activated by an allatotropin.

Animals↗
PubMed1994

The prothoracicotropic hormone (PTTH) of the commercial silkmoth, Bombyx mori, in the CNS of the tobacco hornworm, Manduca sexta.

Immunocytochemistry revealed that a Bombyx mori prothoracicotropic hormone (PTTH)-like peptide is expressed by the Manduca sexta big PTTH-producing neurons, the lateral neurosecretory cell group III (L-NSC III). Independent PCR of genomic DNA and a L-NSC III cDNA library yielded products with 99% sequence similarity to the cDNA encoding Bombyx PTTH. This similarity necessitated evaluation of the relationship between Manduca big PTTH and Bombyx PTTH by 1) bioassay of IEF separated Manduca PTTH and 2) direct assessment of Bombyx PTTH biological activity with Manduca prothoracic glands. Together, these studies indicate that Bombyx PTTH and Manduca PTTH are different peptides expressed by the L-NSC III. The possible physiological significance of a Bombyx PTTH-like peptide in Manduca and its coexpression with Manduca big PTTH by the L-NSC III are discussed.

Animals↗
PubMed1999

Homeotic gene expression in the wild-type and a homeotic mutant of the moth Manduca sexta.

Antibodies were used to examine the expression patterns of Antennapedia (Antp), Ultrabithorax (Ubx), Ubx and abdominal-A combined (Ubx/abd-A), and Distalless (Dll) in the embryos of the moth Manduca sexta. We found that the spatial and temporal pattern of Antp expression in Manduca was correlated with the anterior migration of two patches of epithelium that include the anterior-most tracheal pits, and with the development of functional spiracles. Ubx expression showed an intricate pattern which suggests complex regulation during development. Throughout Manduca embryogenesis the expression of Ubx/Abd-A and Dll was similar to that reported for other insects. However, there was no apparent reduction in Ubx/Abd-A expression in the Manduca abdominal proleg primordia that expressed Dll. The expression of these four proteins was also examined in embryos of the Manduca homozygous homeotic mutant Octopod (Octo). The Octo mutation results in the transformation of A1 and A2 in the anterior direction, with homeotic legs appearing on A1 and occasionally A2. Our results suggest that in Octo animals there is a reduction in the level of Ubx protein expression throughout its domain. Based on homeotic gene expression in wild-type and mutant Manduca and in other insects, we discuss potential roles of homeotic genes in insect morphological evolution.

Amino Acid Sequence↗
PubMed2001

Manduca sexta IRP1: molecular characterization and in vivo response to iron.

Manduca sexta IRP1 was cloned and sequenced. The deduced amino acid sequence of Manduca IRP1 shows high similarity to other IRP1 proteins. The Cys residues required as ligands for the iron sulfur cluster, as well as all residues necessary for aconitase activity are conserved in the insect protein. Purified recombinant Manduca IRP1 binds specifically to transcripts of the iron responsive element (IRE) of Manduca or human ferritin subunit mRNA. Binding activity of the recombinant protein was not influenced by the presence of beta-mercaptoethanol. However, IRP/IRE binding activity of cytoplasmic extracts from fat body was decreased by reducing agents in a dose-responsive manner. Fat body IRP1/IRE binding activity was reduced for Manduca sexta larvae injected with low doses of iron, while IRP1 mRNA and protein levels remained stable. At higher iron doses, binding activity increased and stabilized. Hemolymph ferritin levels showed an inverse relationship to IRP1/IRE binding activity. These data suggest that the Manduca IRP1 is likely involved in translational control of ferritin synthesis in a manner similar to that found in vertebrates. However, factors other than iron can influence IRP/IRE interaction and hemolymph ferritin levels in insects.

Animals↗
PubMed2003

Molecular cloning of the prothoracicotropic hormone from the tobacco hornworm, Manduca sexta.

A cDNA encoding a putative precursor of prothoracicotropic hormone (PTTH) from the tobacco hornworm, Manduca sexta, was isolated and sequenced. This clone contains an open reading frame encoding a 226-amino acid prepropeptide hormone. The deduced amino acid sequence is composed of a signal sequence, a precursor domain and a mature hormone and shows similarities to the other PTTHs that have been cloned from closely related lepidopteran species, Bombyx mori, Samia cynthia ricini, Antheraea peryni, and Hyalophora cecropia. Although these cDNAs showed slightly less similarities in predicted amino acid sequences, seven cysteine residues and the hydrophobic regions within those mature peptides were conserved. In situ hybridization using a cDNA probe encoding the Manduca PTTH showed that PTTH mRNA was in two pairs of neurosecretory cells in the Manduca brain. The recombinant putative Manduca PTTH produced in E. coli was biologically active, both causing a larval molt in neck-ligated Manduca 4th instar larvae (ED(50)=50 pM) and the adult molt of diapausing Manduca pupae (ED(50)=79 pM), but was unable to stimulate molting of debrained Bombyx pupae.

Amino Acid Sequence↗
PubMed2003

Molecular interactions between the specialist herbivore Manduca sexta (lepidoptera, sphingidae) and its natural host Nicotiana attenuata. VI. Microarray analysis reveals that most herbivore-specific transcriptional changes are mediated by fatty acid-amino acid conjugates.

Evidence is accumulating that insect-specific plant responses are mediated by constituents in the oral secretions and regurgitants (R) of herbivores, however the relative importance of the different potentially active constituents remains unclear. Fatty acid-amino acid conjugates (FACs) are found in the R of many insect herbivores and have been shown to be necessary and sufficient to elicit a set of herbivore-specific responses when the native tobacco plant Nicotiana attenuata is attacked by the tobacco hornworm, Manduca sexta. Attack by this specialist herbivore results in a large transcriptional reorganization in N. attenuata, and 161 genes have been cloned from previous cDNA differential display-polymerase chain reaction and subtractive hybridization with magnetic beads analysis. cDNAs of these genes, in addition to those of 73 new R-responsive genes identified by cDNA-amplified fragment-length polymorphism display of R-elicited plants, were spotted on polyepoxide coated glass slides to create microarrays highly enriched in Manduca spp.- and R-induced genes. With these microarrays, we compare transcriptional responses in N. attenuata treated with R from the two most damaging lepidopteran herbivores of this plant in nature, M. sexta and Manduca quinquemaculata, which have very similar FAC compositions in their R, and with the two most abundant FACs in Manduca spp. R. More than 68% of the genes up- and down-regulated by M. sexta R were similarly regulated by M. quinquemaculata R. A majority of genes up-regulated (64%) and down-regulated (49%) by M. sexta R were similarly regulated by treatment with the two FACs. In contrast, few genes showed similar transcriptional changes after H(2)O(2)- and R-treatment. These results demonstrate that the two most abundant FACs in Manduca spp. R can account for the majority of Manduca spp.-induced alterations of the wound response of N. attenuata.

Amino Acids↗
PubMed1991

Isolation and embryonic expression of an abdominal-A-like gene from the lepidopteran, Manduca sexta.

Using sequence homology to the Drosophila Antennapedia gene, we isolated a homeobox-containing gene from the lepidopteran, Manduca sexta. Sequence analysis and in situ hybridizations to tissue sections suggest that the Manduca gene encodes a lepidopteran homologue of the Drosophila Bithorax complex gene abdominal-A. The predicted amino acid sequence of a 76 amino acid region that includes the homeobox and the regions immediately flanking it are identical between the Manduca and Drosophila genes. Northern blots reveal that the manduca abd-A gene is expressed first in the early embryo and continues to be expressed throughout later embryonic and larval stages. In situ hybridizations show that the posterior half of the first abdominal segment marks the anterior border of the Manduca abd-A expression. This expression pattern demonstrates the conservation of parasegments as domains of gene activity in the lepidopteran embryo. The Manduca abd-A expression extends from the posterior half of the first abdominal segment through the tenth abdominal segment, a domain that is greater than that of the Drosophila abd-A expression, and reflects the difference in visible segment number between the two insects.

Amino Acid Sequence↗
PubMed1995

Comparison of ecdysteroid production in Drosophila and Manduca: pharmacology and cross-species neural reactivity.

In both Manduca sexta and Drosophila melanogaster, metamorphic events are driven by ecdysteroids whose production in prothoracic gland (PGs) is stimulated periodically by neural factors. Differences in the life cycle of moths and flies have made it difficult to compare the regulation of ecdysteroid biosynthesis in these two species. As in Manduca, at least two neural factors in the larval Drosophila BVG complex were separable by molecular weight, and they stimulated increased ecdysteroid biosynthesis from the ring gland, a composite organ that includes PG cells. Drosophila neural extracts accelerated ecdysteroid biosynthesis in Manduca PGs and, conversely, partially purified Manduca PTTH preparations elevated ecdysteroid biosynthesis in Drosophila ring glands, suggesting that the two species may share structurally similar prothoracicotropic factors. Drosophila ring glands required the presence of calcium ions to respond to neural extracts, but the phosphodiesterase inhibitor MIX and cAMP analogues exerted little, if any, positive effect on production. Mean ecdysteroid production rates of BVG-ring gland complexes taken from Drosophila larvae during various phases of the wandering period were often submaximal and highly variable, suggesting that they fluctuate widely prior to pupariation. Based on available data in Drosophila and the Manduca model for the control of ecdysteroid biosynthesis, a developmental scheme for neuroendocrine control in Drosophila is proposed.

Animals↗
PubMed2003

Evolution of the Drosophila broad locus: the Manduca sexta broad Z4 isoform has biological activity in Drosophila.

The Drosophila melanogaster broad locus is essential for normal metamorphic development. Broad encodes three genetically distinct functions (rbp, br, and 2Bc) and a family of four zinc-finger DNA-binding proteins (Z1-Z4). The Z1, Z2, and Z3 protein isoforms are primarily associated with the rbp, br, and 2Bc genetic functions respectively. The Z4 protein isoform also provides some rbp genetic function, however an essential function for the Z4 isoform in metamorphosis has not been identified. To determine the degree of conservation of Z4 function between the tobacco hornworm Manduca sexta and Drosophila we generated transgenic Drosophila expressing the Manduca broad Z4 isoform and used this transgene to rescue rbp mutant lethality during Drosophila metamorphosis. We find that the Manduca Z4 protein has significant biological activity in Drosophila with respect to rescue of rbp-associated lethality. There was also some overlap in effects on cuticle gene expression between the Manduca Z4 and Drosophila Z1 isoforms that was not shared with the Drosophila Z4 isoform. Our findings show that Z4 function has been conserved over the 260-million-year period since the divergence of Diptera and Lepidoptera, and are consistent with the hypothesis that the Drosophila Z4 and Manduca Z4 isoforms have essential roles in metamorphosis.

Animals↗
PubMed2004

Sequence and expression of the CAPA/CAP2b gene in the tobacco hawkmoth, Manduca sexta.

The gene coding for cardioacceleratory peptide 2b (CAP2b; pELYAFPRV) has been isolated and sequenced from the moth Manduca sexta (GenBank accession #AY649544). Because of its significant homology to the CAPA gene in Drosophila melanogaster, this gene is called the Manduca CAPA gene. The Manduca CAPA gene is 958 nucleotides long with 29 untranslated nucleotides from the beginning of the sequence to the putative start initiation site. The CAPA gene has a single open reading frame, 441 nucleotides long, that codes for a predicted precursor protein of 147 amino acids. The predicted prepropeptide encodes a single copy of each of three deduced propeptides, a CAP2b propeptide, with a Q substituted for an E at the N-terminus (QLYAFPRVa), and two novel CAP2b-related propeptides (DGVLNLYPFPRVa and TEGPGMWFGPRLa). To reduce confusion and to adopt a more standardized nomenclature, we rename pELYAFPRVa as Mas-CAPA-1 and assign the names of Mas-CAPA-2 to DGVLNLYPFPRVa and Mas-PK-1 (Pyrokinin-1) to TEGPGMWFGPRLa. The spatial and temporal expression pattern of the CAPA gene in the Manduca central nervous system (CNS) was determined in all major post-embryonic stages using in situ hybridization techniques. The CAPA gene is expressed in a total of 27 pairs of neurons in the post-embryonic Manduca CNS. A total of 16 pairs of cells is observed in the brain, two pairs in the sub-esophageal ganglion (SEG), one pair in the third thoracic ganglion (T3), one pair in each unfused abdominal ganglion (A1-A6) and two pairs in the fused terminal ganglion. The mRNA from the CAPA gene is present in nearly every ganglion in each post-embryonic stage. The number of cells expressing the CAPA gene varies during post-embryonic life, starting at 54 cells in first-instar larvae and declining to a minimum of 14 cells midway through adult development.

Amino Acid Sequence↗
PubMed1996

Dopaminergic control of corpora allata activity in the larval tobacco hornworm, Manduca sexta.

The corpora allata (CA) of insects are innervated by axons of non-neurosecretory cerebral neurons, and of the various known neurotransmitters in the brain of the tobacco hornworm, Manduca sexta, only dopamine is detected in the CA by electrochemical detection HPLC. This neurotransmitter stimulates the biosynthetic activity of the CA in vitro for the first 2 days of the last larval stadium, but inhibits CA from day 3 through day 6, the beginning of the prepupal period. Stimulation of JH synthesis has previously been linked with an increase in the production of cyclic AMP (cAMP) in the CA, and dopamine stimulates the adenylyl cyclase system of CA from larvae early in the fifth stadium, while on day 6, its effect is inhibitory. These results suggest: (1) the existence in the CA of both D1- and D2-like dopamine receptors, which in vertebrates stimulate and inhibit, respectively, adenylyl cyclase; and (2) the developmental control of their expression. A potent D1 agonist, (+/-)-SKF 82958-HBr, did not stimulate JH biosynthesis by day 0 CA as expected, but appeared to inhibit it at a concentration of 10(-5)M. Thus the apparent D1-like receptor in Manduca CA may be pharmacologically distinct from vertebrate D1 receptors. The existence of D2-like receptors is supported by the finding that a vertebrate D2 receptor agonist, (+/-) PPHT-HCl, and an antagonist, eticlopride, have the predicted effects on JH acid biosynthesis and cAMP production by day 6 Manduca CA. However, the D1 agonist also significantly reduces JH acid biosynthesis and cAMP production, indicating that while the Manduca D2-like receptor is pharmacologically similar to the vertebrate D2, it shares some characteristics with D1 receptors. The developmental regulation of these receptors by ecdysteroids is suggested by the fact that when day 0 larvae are treated in vivo with exogenous ecdysone:20-hydroxyecdysone, the biosynthetic activity of the CA in vitro 24 h later is no longer stimulated by dopamine.

Adenylyl Cyclases↗
PubMed2003

Molecular characterization, functional expression, and developmental profile of an ether à-go-go K+ channel in the tobacco hornworm Manduca sexta.

A very large number of evolutionarily conserved potassium channels have been identified but very little is known about their function or modulation in vivo. Metamorphosis of the tobacco hornworm, Manduca sexta, is a compelling model system for such studies because it permits analysis to be conducted at the level of identified neurons whose roles in simple behaviors and endocrine regulation are known. We present here the characterization of the first ion channel to be cloned from this animal. Partial genomic sequence for Manduca sexta ether à-go-go (Mseag) and a cDNA clone encoding the Mseag open reading frame were obtained. Genomic Southern analysis indicates that Manduca contains a single member of the eag subfamily per haploid genome. When expressed in Xenopus oocytes, MsEag channels conduct a voltage-dependent, K+ selective outward current with an inactivating component that closely resembles the Drosophila eag current. Mseag transcripts were restricted to the nervous system, adult antenna, and one set of larval skeletal muscles. Steroid hormonal regulation of Mseag expression is suggested by the temporal correlation of developmental changes in transcript expression with the changing steroid titers that promote metamorphosis. These results provide the foundation for functional and modulatory studies of the Eag family of K+ channels in Manduca, which will complement the genetic analysis in Drosophila.

Amino Acid Sequence↗
PubMed1999

Specific binding of human interferon-gamma to particulates from hemolymph and protocerebrum of tobacco hornworm (Manduca sexta) larvae.

Specific binding sites for human interferon-gamma (hIFN-gamma) were found on particulates prepared from the hemolymph and protocerebrum of fifth-instar larvae of the tobacco hornworm, Manduca sexta. A portion of these sites could be solubilized in an active form by the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS). A well-defined specific binding was also associated with hemolymph particulate residue after solubilization by CHAPS. About one-half of [125I]hIFN-gamma binding could be displaced by heparin. The bound hIFN-gamma could be covalently cross-linked to the binding sites using disuccinylamide suberate, and the molecular weight range of these complexes was 200-800 kDa as determined by density gradient sedimentation and gel-exclusion chromatography. Only a small fraction of the hemolymph IFN-gamma binding could be competed by another mammalian cytokine, rat prolactin (rPRL), while there was no sensitivity to rat growth hormone. The small specific rPRL binding found in Manduca hemolymph showed an affinity similar to the prolactin sites found in the liver of pregnant rats. The detergent-insoluble Manduca hIFN-gamma binding was bimodal and similar in affinity distribution to the binding found with human platelet membranes (Kdiss range 0.1-2 nM). The detergent-solubilized IFN-gamma sites were homogenous, with a Kdiss of about 1.5 nM. The IFN-gamma binding sites in Manduca tissues may therefore include molecular species similar to the known invertebrate cytokine receptors and proteoglycan co-receptors.

Amino Acid Sequence↗