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Malpighian Tubules (malpighian + tubule)

Distribution by Scientific Domains

Life Sciences	73%

Selected Abstracts

Identification of two cDNAs encoding synaptic vesicle protein 2 (SV2)-like proteins from epithelial tissues in the cat flea, Ctenocephalides felis

INSECT MOLECULAR BIOLOGY, Issue 3 2004
S. J. Walmsley
Abstract Two distinct cDNAs that appear to encode proteins in the synaptic vesicle-2 (SV2) family were identified as expressed sequence tags from a Ctenocephalides felis hindgut and Malpighian tubule (HMT) cDNA library. To date, SV2 proteins have been described only in vertebrates, and have been detected only in synaptic vesicles in neuronal and endocrine tissues, where they are thought to regulate synaptic vesicle exocytosis. The cDNAs for the C. felis SV2-like proteins SVLP-1 and SVLP-2 encode predicted full-length proteins of 530 and 726 amino acids, respectively. Of characterized proteins, the SVLP protein sequences were most similar to rat SV2B. Northern blot analysis revealed that both mRNAs were up-regulated in larval stages that feed and in adults after feeding, and were expressed primarily or exclusively in the HMT tissues in adult fleas. These results suggest that the flea SVLP-1 and SVLP-2 gene products may have roles that are specific for the HMT tissues, and may differ in function from vertebrate SV2 proteins. [source]

Brochosome influence on parasitisation efficiency of Homalodisca coagulata (Say) (Hemiptera: Cicadellidae) egg masses by Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae)

ECOLOGICAL ENTOMOLOGY, Issue 5 2005
Hans-Paul Velema
Abstract., 1.,Many cicadellid females in the tribe Proconiini (Hemiptera: Cicadellidae) cover their egg masses with specialised, usually rod-shaped, brochosomes as the eggs are being laid. The brochosomes are produced in Golgi complexes in the Malpighian tubules of Cicadellidae. In contrast to the gravid females, adult males, pre-reproductive adult females, and nymphal males and females produce specialised, usually spherically shaped brochosomes. Brochosomes are also used to cover the external surfaces of nymphs and newly moulted adult males and females. 2.,The function of the brochosome covering the egg masses is unknown but various hypotheses have been suggested, including protecting the eggs against pathogens, predators, and parasitoids. Based on preliminary observations of Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae) parasitising the eggs of the cicadellid, Homalodisca coagulata (Say), it is speculated here that brochosomes covering an egg mass hinder parasitisation of eggs by G. ashmeadi. This hypothesis was tested by observing G. ashmeadi females foraging on leaves with H. coagulata egg masses heavily covered with rod-shaped brochosomes vs. those lacking brochosomes. 3.,Cox's proportional hazards model was used to evaluate the probability, per unit time, that a female G. ashmeadi displayed the sequence of behaviours that ended in successful oviposition as influenced by five variables: (a) presence or absence of brochosomes on an egg mass, (b) the leaf surface, upper or lower, being searched by the parasitoid (the egg masses are laid in the parenchyma on the lower leaf surface), (c) the parasitoid's previous ovipositional experience, (d) egg mass size, and (e) the parasitoid's age. 4.,Brochosomes significantly decreased oviposition efficacy of G. ashmeadi females. Scanning electron microscopy showed that females exposed to brochosome-covered egg masses had brochosomes adhering to their tarsi, legs, antennae, and eyes, all of which prompted extensive bouts of grooming. [source]

Molecular cloning, characterization, expression pattern and cellular distribution of an ovarian lipophorin receptor in the cockroach, Leucophaea maderae

INSECT MOLECULAR BIOLOGY, Issue 3 2009
M. Tufail
Abstract A cDNA that encodes a lipophorin receptor (LpR) with a predicted structure similar to that of the low density lipoprotein receptor (LDLR) gene superfamily was cloned from ovaries of the cockroach, Leucophaea maderae (Lem) and characterized. This is the first LpR sequenced from the order Dictyoptera. The cDNA has a length of 3362 bp coding for an 888-residue mature protein with a predicted molecular mass of ~99.14 kDa and a pI value of 4.68. The deduced amino acid sequence showed that the LemLpR harbours eight ligand-binding repeats (LBRs) at the N-terminus similar to the other insect LpRs, and thus resembles vertebrate VLDLRs. In addition to eight tandemly arranged LBRs, the five-domain receptor contains an O -linked sugar region and the classic LDLR internalization signal, FDNPVY. Northern blot analysis revealed the presence of ~4.0 kb ovarian mRNA that was transcribed throughout oogenesis with its peak especially during late previtellogenic and vitellogenic periods (from days 3 to 11). LpR transcript(s) or homologues of LDLRs were also detected in the head, midgut, Malpighian tubules, muscles and in the fat body. RNA in situ hybridization and immunocytochemistry localized the LpR mRNA and protein to germ line-derived cells, the oocytes, and revealed that LpR gene transcription and translation starts very early during oocyte differentiation in the germarium. LpR protein was evenly distributed throughout the cytoplasm during previtellogenic periods of oogenesis. However, during vitellogenic stages, the receptor was accumulated mainly in the cortex of the oocyte. Immunoblot analysis probed an ovarian LpR protein of ~115 and 97 kDa under reducing and nonreducing conditions, respectively. The protein signal appeared on day 2, increased every day and was high during vitellogenic periods from day 4 to day 7. Southern blot analysis suggested the presence of a single copy of the LpR gene in the genome of Le. maderae. [source]

Cloning and molecular characterization of two invertebrate-type lysozymes from Anopheles gambiae

INSECT MOLECULAR BIOLOGY, Issue 3 2008
S. M. Paskewitz
Abstract We sequenced and characterized two novel invertebrate-type lysozymes from the mosquito Anopheles gambiae. Alignment and phylogenetic analysis of these and a number of related insect proteins identified through bioinformatics strategies showed a high degree of conservation of this protein family throughout the Class Insecta. Expression profiles were examined for the two mosquito genes through semiquantitative and real-time PCR analysis. Lys i-1 transcripts were found in adult females in the fat body and Malpighian tubules, whereas Lys i-2 was detected only in fat bodies. Blood-feeding resulted in significantly increased transcript abundance for both genes in the midguts. Neither gene was upregulated following bacterial challenge. [source]

Molecular cloning and immunolocalization of a diuretic hormone receptor in rice brown planthopper (Nilaparvata lugens)

INSECT MOLECULAR BIOLOGY, Issue 5 2004
D. R. G. Price
Abstract RNA extracted from guts of rice brown planthopper, Nilaparvata lugens, was used to clone cDNA predicted to encode a diuretic hormone receptor (DHR). The DHR, a member of the calcitonin/secretin/corticotropin-releasing factor family of G-protein-coupled receptors, contains seven transmembrane domains and a large N-terminal extracellular domain potentially involved in hormone binding. The N-terminal domain was expressed as a recombinant protein, purified and used to raise antibodies. Anti-DHR IgG bound specifically to Malpighian tubules in immunolocalization experiments using dissected guts, and to a putative DHR polypeptide from N. lugens gut on Western blots. Anti-DHR IgG delivered orally to insects was not detected in the haemolymph, and showed no binding to gut or tubules, confirming that DHR N-terminal hormone-binding domain is not exposed to the gut lumen. [source]

Expression of an Aedes aegypti cation-chloride cotransporter and its Drosophila homologues

INSECT MOLECULAR BIOLOGY, Issue 4 2003
V. Filippov
Abstract Insects maintain haemolymph homeostasis under different environmental conditions by modulating the concentrations of Na+, K+ and Cl, ions. One group of proteins involved in ion transport across cell membranes consists of cation-chloride cotransporters that form a family of structurally similar proteins. Although much is known about these proteins in mammalian systems, our understanding of them in insects is lacking. The recent sequencing of two insect genomes, Drosophila and Anopheles, enabled us to identify globally members of the family of cation chloride cotransporters in these insects. Using RT-PCR we monitored the transcription of members of this family in development and in several tissues. Our analyses showed that transcription of these genes differ considerably from the ubiquitously and highly expressed CG5594 gene to the almost silent gene CG31547. Comparison of Drosophila CG12773 and its Aedes homologue AaeCG12773 showed that they have similar transcript expression profiles. Immunohistochemical analysis of AaeCG1277 gene expression revealed that it is highly expressed in the gut of larvae and female adults but not in Malpighian tubules. A more detailed analysis showed that this protein is localized predominantly in the basolateral membrane of these tissues. This expression pattern confirmed the results of RT-PCR analysis. We also created a mutant for one of the genes, CG10413, in Drosophila using P-element excision. Analysis of this mutant showed this protein does not appear to be essential for development. [source]

High-nickel insects and nickel hyperaccumulator plants: A review

INSECT SCIENCE, Issue 1 2009
Robert S. Boyd
Abstract Insects can vary greatly in whole-body elemental concentrations. Recent investigations of insects associated with Ni hyperaccumulator plants have identified insects with relatively elevated whole-body Ni levels. Evaluation of the limited data available indicates that a whole-body Ni concentration of 500 ,g Ni/g is exceptional: I propose that an insect species with a mean value of 500 ,g Ni/g or greater, in either larval/nymphal or adult stages, be considered a "high-Ni insect". Using the 500 ,g Ni/g criterion, 15 species of high-Ni insects have been identified to date from studies in Mpumalanga (South Africa), New Caledonia and California (USA). The highest mean Ni concentration reported is 3 500 ,g Ni/g for nymphs of a South African Stenoscepa species (Orthoptera: Pyrgomorphidae). The majority of high-Ni insects (66%) are heteropteran herbivores. Studies of high-Ni insect host preference indicate they are monophagous (or nearly so) on a particular Ni hyperaccumulator plant species. Much of the Ni in bodies of these insects is in their guts (up to 66%,75%), but elevated levels have also been found in Malpighian tubules, suggesting efficient elimination as one strategy for dealing with a high-Ni diet. Tissue levels of Ni are generally much lower than gut concentrations, but up to 1200 ,g Ni/g has been reported from exuviae, suggesting that molting may be another pathway of Ni elimination. One ecological function of the high Ni concentration of these insects may be to defend them against natural enemies, but to date only one experimental test has supported this "elemental defense" hypothesis. Community-level studies indicate that high-Ni insects mobilize Ni into food webs but that bioaccumulation of Ni does not occur at either plant-herbivore or herbivore-predator steps. Unsurprisingly, Ni bioaccumulation indices are greater for high-Ni insects compared to other insect species that feed on Ni hyperaccumulator plants. There is some evidence of Ni mobilization into food webs by insect visitors to flowers of Ni hyperaccumulator plants, but no high-Ni insect floral visitors have been reported. [source]

Morphology and ultrastructure of the malpighian tubules of the Chilean common tarantula (Araneae: Theraphosidae)

JOURNAL OF MORPHOLOGY, Issue 1 2002
S. Renee Hazelton
Abstract Relatively little is known about the morphology and ultrastructure of the Malpighian tubules of spiders (Arachnida: Araneae). Our study represents the first investigation of the Malpighian tubules of a theraphosid spider and is the only study to examine the living Malpighian tubules using confocal laser scanning microscopy. In theraphosid spiders, the Malpighian tubules originate from the stercoral pocket in the posterior portion of the opisthosoma and extend forward toward the prosoma in a dendritic pattern. There are three distinct segments (initial, main, and terminal), all dark brown in appearance. Each segment has distinctive ultrastructural features. Both the terminal and the main segment appear to be composed of at least two cell types with finger-like cytoplasmic protrusions associated with one of these types. The terminal segment, which is most proximal to the stercoral pocket, is the largest in diameter. It is composed of large, cuboidal cells containing many mitochondria and lipid inclusions. The main segment is intermediate in diameter with many mitochondria and secretory vesicles present. The initial segment is relatively thin in comparison to the other segments and is intimately associated with the digestive gland. The cells of the initial segment contain very little cytoplasm, fewer mitochondria, secretory vesicles, and prominent inclusions. J. Morphol. 251:73,82, 2002. © 2002 Wiley-Liss, Inc. [source]

Establishment of Liebermannia dichroplusae n. comb. on the Basis of Molecular Characterization of Perezia dichroplusae Lange, 1987 (Microsporidia)

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 3 2007
YULIYA Y. SOKOLOVA
ABSTRACT. Perezia dichroplusae Lange, 1987 is a parasite of the Malpighian tubules of an Argentine grasshopper, Dichroplus elongatus (Orthoptera, Acrididae, Melanoplinae). In order to determine relationships of this microsporidium with Perezia nelsoni and with other microsporidia, we sequenced its small subunit ribosomal RNA gene (SSU rDNA) (GenBank Accession No. EF016249) and performed phylogenetic analysis of the novel sequence against 17 microsporidian SSU rDNA sequences from GenBank, using neighbor-joining (NJ), maximum-parsimony (MP), and maximum-likelihood (ML) methods. This analysis revealed the highest similarity (96%) of the new sequence to Liebermannia patagonica, a parasite of gut epithelium cells of another grasshopper from Argentina, versus only 65% similarity to P. nelsoni, a parasite of muscles of paenaeid shrimps. In phylogenetic trees inferred from SSU rDNA sequences, the microsporidium from D. elongatus is sister taxon to L. patagonica and both cluster with Orthosomella operophterae. At the higher hierarchical level, the Liebermania,Orthosomella branch forms a clade with the Endoreticulatus,Cystosporogenus,Vittaforma group and with Enterocytozoon bieneusi. Perezia nelsoni falls into another large clade together with Nosema and Ameson species. We propose transferring P. dichroplusae to the genus Liebermannia and creating a new combination Liebermannia dichroplusae n. comb., based both on SSU rDNA sequence analysis and on common characters between P. dichroplusae and L. patagonica, which include the presence of elongated multinuclear sporonts, sporoblastogenesis by a similar process of sequentially splitting off sporoblasts, ovocylindrical spores of variable size, tissue tropism limited to epithelial cells, Orthoptera as hosts, and geographical distribution of hosts in the southern temperate region of Argentina. We argue that the condition of the nuclei in spores (i.e. diplokaryotic in L. patagonica or monokaryotic in L. dichroplusae) cannot be used to distinguish genera. Therefore, we remove the statement about the presence of diplokaryotic spores from the revised diagnosis of the genus Liebermannia. [source]

Effects of acute or chronic exposure to dietary organic anions on secretion of methotrexate and salicylate by Malpighian tubules of Drosophila melanogaster larvae

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 3 2010
Sarah Chahine
Abstract The effects of dietary exposure to organic anions on the physiology of isolated Malpighian tubules and on tubule gene expression were examined using larvae of Drosophila melanogaster. Acute (24,h) or chronic (7,d) exposure to type I organic anions (fluorescein or salicylate) was associated with increased fluid secretion rates and increased fluxes of both salicylate and the type II organic anion methotrexate. By contrast, chronic exposure to dietary methotrexate was associated with increased fluid secretion rate and increased flux of methotrexate, but not salicylate. Exposure to methotrexate in the diet resulted in increases in the expression of a multidrug efflux transporter gene (MET; CG30344) in the Malpighian tubules. There were also increases in expression of genes for either a Drosophila multidrug resistance,associated protein (dMRP; CG6214) or an organic anion transporting polypeptide (OATP; CG3380), depending on the concentration of methotrexate in the diet. Exposure to salicylate in the diet was associated with an increase in expression of dMRP and with decreases of MET and OATP. Exposure to dietary salicylate or methotrexate was also associated with different patterns of expression of heat shock protein genes. The results suggest that exposure to specific type I or type II organic anions has multiple effects and results not only in increased organic anion transport but also in increased rates of inorganic ion transport, which drives osmotically-obliged fluid secretion. Increased fluid secretion may enhance secretion of organic anions by eliminating diffusive backflux from the tubule lumen to the hemolymph. © 2010 Wiley Periodicals, Inc. [source]

Prostaglandin E2 modulates the expression of antimicrobial peptides in the fat body and midgut of Anopheles albimanus

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2008
F.L. García Gil de Muñoz
Abstract Prostaglandins (PGs) participate in the regulation of vertebrate and in at least six insect orders' immune responses. We identified PGE2 in midgut, fat body, Malpighian tubules, and ovarioles of Anopheles albimanus (Aa) mosquitoes. Our data indicate that PGE2 synthesis in cultured midguts responds to the presence of two bacterial species, Micrococcus luteus and Klebsiella pneumoniae. The production of mRNA coding for antimicrobial peptides Aa -Attacin, Aa -Cecropin, and Aa -Gambicin was observed in cultured fat bodies and midguts. The production of these messengers was reduced in the presence of dexamethasone, and this effect was reversed by arachidonic acid. Adding PGE2 to cultures resulted in increased Aa -cecropin mRNA and decreased Aa -attacin and Aa -gambicin mRNAs. Arch. Insect Biochem. Physiol. 68:14,25, 2008. © 2008 Wiley-Liss, Inc. [source]

Phylogenetic Relationships of the Suborders of Coleoptera (Insecta)

CLADISTICS, Issue 1 2000
Rolf G. Beutel
One hundred seven external and internal characters of larval and adult representatives of 28 genera of the coleopteran suborders were analyzed cladistically. Four groups of Neuropterida were introduced as outgroup. The analysis yielded 18 trees with a minimum of 194 steps (CI 0.691). All trees support the monophyly of all four suborders and a branching pattern (Archostemata + (Adephaga + (Myxophaga + Polyphaga))). The presence of elytra with meso- and metathoracic locking devices, the specific hind-wing folding, the close connection of exposed sclerites, the absence of the mera, the absence of eight thoracic muscles, the reduced abdominal sternite I, and the invagination of terminal segments are autapomorphies of Coleoptera. The monophyly of Coleoptera excl. Archostemata is supported by further transformations of the thoracic sclerites such as absence of the mesothoracic discriminal line and katepisternal joint, by an internalized or absent metathoracic trochantin, by the presence of a bending zone in the hind-wing, and by eight further muscle losses. Fusion of tibia and tarsus and presence of a single claw are larval synapomorphies of Myxophaga and Polyphaga. Adults are characterized by fusion of protrochantin and propleura and by the rigid connection of the meso- and metathoracic ventrites. The eucinetoid lineage of Polyphaga is characterized by the secondary absence of the bending zone of the alae. This results in a distinctly simplified wing folding mechanism. The monophyly of Cucujiformia (+ Bostrichoidea) is supported by the presence of cryptonephric Malpighian tubules. Transformations of fore-and hind-wings, reinforcement and simplification of the thoracic exoskeleton, and an efficient use of a distinctly reduced set of thoracic muscles play an important role in the early evolution of Coleoptera. Many different larval character transformations take place in the earlier Mesozoic within the suborders. [source]