Search results for "hemolymph"
showing 10 items of 126 documents
Characterization of DrosophilaHemoglobin
2002
In contrast to previous assumptions, the fruit fly Drosophila melanogaster possesses hemoglobin. This respiratory protein forms a monomer of about 17 kDa that is not exported into the hemolymph. Recombinant Drosophila hemoglobin displays a typical hexacoordinated deoxy spectrum and binds oxygen with an affinity of 0.12 torr. Four different hemoglobin transcripts have been identified, which are generated by two distinct promoters of the hemoglobin (glob1) gene but are identical in their coding regions. Putative binding sites for hypoxia-regulated transcription factors have been identified in the gene. Hemoglobin synthesis in Drosophila is mainly associated with the tracheal system and the fa…
Evolutionary history and diversity of arthropod hemocyanins
2004
Hemocyanins are copper-containing, multi-subunit proteins that transport oxygen in the hemolymph of many molluscs and arthropods [Markl and Decher, Adv. Comp. Environ. Physiol. 13 (1992) 325; van Holde et al., J. Biol. Chem. 276 (2001) 15563]. Arthropod hemocyanins originated more than 550 million years ago from oxygen-consuming phenoloxidases. Hemocyanins are present in various Onychophora, Chelicerata, Myriapoda, Crustacea, and Hexapoda, but subunit evolution differs striking in these arthropod subphyla. Hemocyanins also gave rise to non-respiratory proteins (crustacean pseudo-hemocyanins, insect hexamerins, and hexamerin receptors), which most likely have storage functions.
Covalent modificaition of juvenile hormone binding proteins by photoaffinity labeling: An unexpected gel shift effect
1994
The 32 kD juvenile hormone binding protein (JHBP) and two 80 kD proteins in larval Manduca sexta hemolymph were labeled with [3H]FDK, a photoaffinity analog of methyl farnesoate (MF). The labeling could be completely displaced by a 30-fold excess of either MF or JH II, demonstrating that [3H]FDK binds specifically to the JH binding sites of the 32 kD JHBP and the 80 kD proteins. In addition, a high molecular-mass protein was labeled with [3H]FDK; labeling could be displaced by excess MF but not by JH II, demonstrating the selectivity in binding MF. The 32 kD JHBP also appeared to weakly bind the potent juvenoid, methoprene, at the JH binding site. Covalent modification by [3H]FDK induced a …
Pyrgomorphid grasshoppers of the genus Phymateus contain species-specific decapeptides of the AKH/RPCH family regulating lipid-mobilization during fl…
1996
. Using heterologous and conspecific bioassays, two peptides have been isolated from methanolic extracts of corpora cardiaca from the pyrgomorphid grasshopper Phymateus morbillosus L.The structures of both peptides were elucidated by a combination of Edman degradation, after deblocking the N-terminal pyroglutamic acid residue, and mass spectrometric techniques.One peptide is an octapeptide (pGlu-Leu-Asn-Phe-Ser-Thr-Gly-TrpNH2) which also occurs in other insects and is code-named Scg-AKH-II.The second peptide is a novel decapeptide member of the AKH/RPCH family (pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-SerNH2 code-named here Phm-AKH.It is the first example of a different peptide in the same genu…
Complete Nucleotide Sequence of a Hemoglobin Gene Cluster from the Midge Chironomus thummi piger
1991
The aquatic larvae of non-biting midges (Chironomidae, Diptera) contain a variety of Hb proteins in their hemolymph that enable them to survive in an anoxic environment (1). In Chironomus thummi thummi, 12 different Hb variants have been identified and their amino acid sequences determined (2). Based on these primary structures, the evolutionary relationships between the five monomeric and the s e v e n dimeric Hb proteins have been deduced (2). The two groups are thought to have evolved in two different lineages which separated more than 255 million years ago.
Insect Immunity
2001
Two novel antimicrobial peptides, which we propose to name termicin and spinigerin, have been isolated from the fungus-growing termite Pseudacanthotermes spiniger (heterometabole insect, Isoptera). Termicin is a 36-amino acid residue antifungal peptide, with six cysteines arranged in a disulfide array similar to that of insect defensins. In contrast to most insect defensins, termicin is C-terminally amidated. Spinigerin consists of 25 amino acids and is devoid of cysteines. It is active against bacteria and fungi. Termicin and spinigerin show no obvious sequence similarities with other peptides. Termicin is constitutively present in hemocyte granules and in salivary glands. The presence of …
Characterization of vitellogenins in Spilostethus pandurus (Hemiptera): Immunoelectrophoretic studies and short-term labelling experiments
1992
Abstract The haemolymph of Spilostethus pandurus contains three female-specific proteins (I, II and III) as revealed by SDS-PAGE. Antibodies prepared against them recognize three fractions (4, 5 and 6) in ovarian extracts which have similar molecular weights suggesting that I, II and III are vitellogenins. Upon injection of a 14C amino acid mixture into vitellogenic females, labelled proteins first appear in the fat body, then in the haemolymph and next in the ovarian follicles.
Metabolic integration in locust flight: the effect of octopamine on fructose 2,6-bisphosphate content of flight muscle in vivo
1994
The biogenic amine octopamine was injected into the haemolymph of 20-days old male locusts,Locusta migratoria, and the content of fructose 2,6-bisphosphate, a potent activator of glycolysis, was measured in the flight muscle after various time. Octopamine brought about a transient increase in fructose 2,6-bisphosphate. After the injection of 10 μl of 10 mmol·l-1 d, l-octopamine fructose 2,6-bisphosphate was increased by 61% within 2 min. Ten minutes after the injection fructose 2,6-bisphosphate was increased to 6.71±0.89 nmol·g-1 flight muscle, almost 300% over the control value. Flight caused fructose 2,6-bisphosphate in flight muscle to decrease, but this decrease was counteracted by octo…
Dissimilar Regulation of Antimicrobial Proteins in the Midgut of Spodoptera exigua Larvae Challenged with Bacillus thuringiensis Toxins or Baculoviru…
2015
Antimicrobial peptides (AMPs) and lysozymes are the main effectors of the insect immune system, and they are involved in both local and systemic responses. Among local responses, midgut immune reaction plays an important role in fighting pathogens that reach the insect body through the oral route, as do many microorganisms used in pest control. Under this point of view, understanding how insects defend themselves locally during the first phases of infections caused by food-borne pathogens is important to further improve microbial control strategies. In the present study, we analyzed the transcriptional response of AMPs and lysozymes in the midgut of Spodoptera exigua (Lepidoptera: Noctuidae…
Vitellogenesis inhibition in Oncopeltus fasciatus females (Heteroptera: Lygaeidae) exposed to cadmium
2005
Abstract Newly moulted females of the insect Oncopeltus fasciatus were exposed to cadmium (Cd) dissolved in the drinking water (50–400 mg l −1 Cd) for 5 days. Cd exposure delayed ovarian maturation and inhibited egg production. Exposure to Cd, moreover, decreased hemolymph levels of the two major vitellogenin polypeptides of O. fasciatus , VG1 and VG2, in a concentration-dependent way, probably by a reduction in their synthesis. The ovarian levels of VG1 and VG2 were also decreased in Cd-exposed females. It was next investigated whether Cd effects might be a consequence of the endocrine disruption of vitellogenin synthesis, which is controlled by juvenile hormone (JH). JH replacement therap…