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At least 307 records · Page 17Linked to original sources
PubMed2001

An initial study on the succession of sarcosaprophagous Diptera (Insecta) on carrion in the southeastern Iberian peninsula.

We present the results of the first study concerning Diptera carried out on the sarcosaprophagous fauna of southeastern Spain. This work represents the first attempt to describe dipteran sarcosaprophagous fauna in the Iberian peninsula, the seasonal succession, main features of the population dynamics and the main taxa useful for estimation of the post-mortem interval. The results of this study could be very useful for further forensic case work in the west Mediterranean area.

Animals↗
PubMed2002

The development of Blastocrithidia triatomae (Trypanosomatidae) in the reduviid bug Triatoma infestans (Insecta): influence of starvation.

Fifth instars of Triatoma infestans with established Blastocrithidia triatomae infections were dissected after different periods of starvation. After a short starvation period of 30 days, 60% of the total population (2,700,000 flagellates) occurred in the small intestine. Within the following 3 months, the numbers of living flagellates there (epimastigotes, cysts) were reduced by about 70% and the percentage of dead mastigotes increased to 30% of the respective total population. Epimastigotes always dominated (about 90%), followed by cysts and only up to 3% spheromastigotes. These relations were only slightly changed by starvation. In the rectum, at 30-120 days after feeding, the total population of living epimastigotes was reduced by 90% and the percentage of those attached to the rectal wall decreased from 10% to <3%. During this period, the proportion of dead from all epimastigotes increased from 34% to >99%. In the rectum, the percentage of cysts from the total population of living parasites increased from 41% to 88% at 30-60 days after feeding and remained at this percentage and total numbers, showing that especially the early phase of starvation strongly induced the encystment of B. triatomae.

Animals↗
PubMed2002

The development of Blastocrithidia triatomae (Trypanosomatidae) in the reduviid bug Triatoma infestans (Insecta): influence of feeding.

The population density and composition of an established infection of Blastocrithidia triatomae in the intestinal tract of fifth instars of Triatoma infestans were compared in unfed bugs, at 4 h and up to 15 days after feeding, and also in feces and urine deposited in the first 4 h after feeding. In unfed bugs, about 1-2 million B. triatomae colonized the small intestine and rectum, mainly epimastigotes (85% and 80%, respectively). During excretion, the percentage of cysts increased within the first two drops (from 15% to 35%) and then decreased slowly, indicating a washing-out of these unattached stages. The initial reduction in the B. triatomae population lasted up to 6 days after feeding. By 15 days after feeding, the populations had strongly increased in the small intestine and rectum, to 22 million and 2 million flagellates, respectively, as had cysts, comprising some 50% of the total population in the rectum.

Animals↗
PubMed2006

Supergroup F Wolbachia bacteria parasitise lice (Insecta: Phthiraptera).

We studied six species of lice from three of the four suborders of lice. These lice were infected with Wolbachia bacteria from supergroups A and F. This is the first report of an infection of supergroup F Wolbachia in lice. To date, Wolbachia from supergroup F have been found in filarial nematodes, Mansonella spp., and, rarely, in insects. We inferred the phylogeny of the Wolbachia from lice and representatives of all Wolbachia supergroups, with nucleotide sequences from the small subunit ribosomal RNA gene (SSU rRNA). There was no evidence of congruence between the taxon of louse and the Wolbachia bacteria that infect lice. There is no evidence that Wolbachia and their louse hosts co-evolved at least at the level of Wolbachia supergroups. We propose a novel mechanism for the horizontal transfer of Wolbachia between different species of lice from birds: transfer of Wolbachia during phoresis by hippoboscid flies.

Animals↗
PubMed2005

FMRFamide-like immunocytochemistry in the brain and subesophageal ganglion of Triatoma infestans (Insecta: Heteroptera). Coexpression with beta-pigment-dispersing hormone and small cardioactive peptide B.

The distribution of FMRFamide (FMRFa)-like immunoreactivity (LI) was studied in the brain and subesophageal ganglion of Triatoma infestans, the insect vector of Chagas' disease. The neuropeptide displayed a widespread distribution with immunostained somata in the optic lobe, in the anterior, lateral, and posterior soma rinds of the protocerebrum, and around the antennal sensory and mechanosensory and motor neuropils of the deutocerebrum. FMRFa-immunoreactive profiles of the subesophageal ganglion were seen in the mandibular, maxillary, and labial neuromeres. Immunostained neurites were detected in the medulla and lobula of the optic lobe, the lateral protocerebral neuropil, the median bundle, the calyces and the stalk of the mushroom bodies, and the central body. In the deutocerebrum, the sensory glomeruli showed a higher density of immunoreactive processes than the mechanosensory and motor neuropil, whereas the neuropils of each neuromere of the subesophageal ganglion displayed a moderate density of immunoreactive neurites. Colocalization of FMRFa-LI and crustacean pigment-dispersing hormone-LI was found in perikarya of the proximal optic lobe, the lobula, the sensory deutocerebrum, and the labial neuromere of the subesophageal ganglion. The distribution pattern of small cardioactive peptide B (SCP(B))-LI was also widespread, with immunolabeled somata surrounding every neuropil region of the brain and subesophageal ganglion, except for the optic lobe. FMRFa- and SCP(B)-LIs showed extensive colocalization in the brain of this triatomine species. The presence of immunolabeled perikarya displaying either FMRFa- or SCP(B)-LI confirmed that each antisera identified different peptide molecules. The distribution of FMRFa immunostaining in T. infestans raises the possibility that FMRFa plays a role in the regulation of circadian rhythmicity. The finding of immunolabeling in neurosecretory somata of the protocerebrum suggests that this neuropeptide may also act as a neurohormone.

Animals↗
PubMed1998

Subcellular effects and localization of binding sites of phytohemagglutinin in the potato leafhopper, Empoasca fabae (Insecta: Homoptera: Cicadellidae).

To identify the means by which phytohemagglutinin (PHA) exerts its toxicity on the potato leafhopper, four different methods (thick and semi-thin sectioning combined with immunofluorescent staining, in vitro receptor autoradiography, and immunoelectron microscopy) were used to elucidate the PHA target tissue, binding site, and its effects on this tissue. Sixteen 1- or 2-day-old female potato leafhoppers were fed for 36 h on each of three treatments: a control, diet or a diet containing either the PHA-E subunit or the PHA-L subunit. The PHA-E subunit, but not PHA-L, had previously been shown to be lethal. The insects were then prepared for both light and confocal microscopy. Analysis of images showed that PHA bound only to the surface of midgut epithelial cells of the potato leafhopper. PHA-E caused severe disruption, disorganization, and elongation of the brush border microvilli, and swelling of the epithelial cells into the lumen of the gut, leading to complete closure of the lumen. Furthermore, PHA-E stimulated the division of midgut epithelial cell nuclei, leading to two nuclei in each cell. Nuclei later elongated and degraded. In contrast, PHA-L had little effect on the epithelial cells of the midgut. It did not strongly bind to the surface of epithelial cells and caused much less disruption of brush-border microvilli, less disorganization of the cells and less elongation of nuclei. Strong binding of PHA occurred solely on the cell membrane of the brush border microvilli of epithelial cells. In contrast, the controls (i.e., midgut tissue, blocking agent, PHA, and antibodies) showed that midgut tissue was not autofluorescent and showed no fluorescent binding signal. Analysis of both bright- and dark-field images obtained by autoradiography and immunoelectron microscopy confirmed these findings.

Animals↗
PubMedDate not supplied

Non-concerted evolution of the RET76 satellite DNA family in Reticulitermes taxa (Insecta, Isoptera).

The evolutionary dynamics of satellite DNA is most often studied in canonical mating systems, where bisexuality and panmixis are the rule. In eusocial termites, the limited number of reproducers starting a new colony and the maintenance of the colony through few neotenics act as bottle-necks both in space and time. No data on repetitive DNA are available for Isoptera and for their peculiar reproductive strategy. Here we present the first satellite DNA family isolated in European Reticulitermes. RET76 is a G+C rich satellite embodying two sub-families with a 76 bp monomer. RET76 sequences are highly variable (sequence homology is lower than 80% within sub-families and lower than 68% in the entire family) and this variability is equally distributed among the eight analysed taxa, thus depicting a pattern of non-concerted evolution. The absence of variant fixation--together with the strict monomer length conservation--may be explained at the molecular level as due to functional constraints acting on these sequences, and/or at the organismic level by considering the involvement of eusociality in preventing or greatly reducing variant fixation, somehow mimicking an unisexual strategy.

Animals↗
PubMed1998

Ecdysteroid resistant subclones of the epithelial cell line from Chironomus tentans (Insecta, Diptera). I. Selection and characterization of resistant clones.

Chironomus tentans cells were cultured in the presence of gradually increasing concentrations of 20-OH-ecdysone or a nonsteroidal molting hormone agonist, the benzoylhydrazine RH 5992, for a period of about 2 yr. From these cultures, subclones were selected, which are resistant to up to 25 microM 20-OH-ecdysone according to morphological (changes in cell shape and cell arrangement) and physiological criteria (acetylcholinesterase induction, secretion of chitinolytic enzymes, thymidine incorporation). Some subclones, selected in the presence of 20-OH-ecdysone, are resistant only to molting hormone, but still respond to RH 5992 morphologically and biochemically, whereas subclones selected in the presence of the benzoylhydrazine showed no reaction neither to 20-OH-ecdysone nor to the hormone agonist. Hormone resistance is stable; 3 mo. after hormone withdrawal, resistant clones still do not respond to renewed exposure to 20-OH-ecdysone or RH 5992, respectively. Because in all resistant subclones tested so far all hormonally regulated responses known from sensitive cells were no longer detectable, it is assumed that the hormone signaling pathway itself is interrupted. Possible mechanisms of hormone resistance were discussed.

Acetylcholinesterase↗
PubMed1987

Forskolin-insensitive adenylate cyclase in cultured cells of Choristoneura fumiferana (Insecta).

Adenylate cyclase from a spruce budworm cell line, IBRI-Cfl, is activated by octopamine (Ka = 50 microM), guanine nucleotides and sodium fluoride but not by forskolin. In addition, forskolin does not potentiate the octopamine-sensitive response. To our knowledge, this is the first published report of a hormone-sensitive adenylate cyclase, with a functional guanine nucleotide regulatory protein, that is insensitive to forskolin both in intact cells and washed membrane preparations.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Purification of a protease inhibitor which controls prophenoloxidase activation in hemolymph of Locusta migratoria (insecta).

A protein which inhibits the prophenoloxidase----phenoloxidase (EC 1.14.18.1) proteolytic activation in hemocyte extracts of Locusta migratoria was isolated from the plasma of the same insect and partially characterized. It shows a molecular weight of 14,000, an inhibiting activity toward the cascade system in the insect hemocytes, which resulted in a lower production of phenoloxidase, a key enzyme for the defence mechanism in arthropods. To identify the specificity of the Locusta inhibitor and consequently the specificity of its target enzyme, inhibitory tests were performed against a number of known serine-proteases. A strong in vitro inhibiting activity toward chymotrypsin and, to a lesser extent, toward human leukocyte elastase was present, while trypsin, Carlsberg subtilisin, human thrombin and pancreatic elastase failed to react. The lack of trypsin inhibition by the isolated inhibitor suggested that the trypsin-catalysed activation of the system in the hemocyte extract takes place under different controls or at an earlier stage of the cascade. The N-terminal sequence of the inhibitor reveals that this molecule is different from the protease inhibitors isolated from other arthropods.

Amino Acid Sequence↗
PubMed1988

Further experimental evidence for the involvement of ecdysone in the control of meiotic reinitiation in oocytes of Locusta migratoria (Insecta, Orthoptera).

Ecdysone has recently been shown to be able to trigger meiotic reinitiation in vitro in submature oocytes of Locusta. In the present study we have experimentally depressed (by 60-70%) ecdysone biosynthesis in the ovaries of adult females by rearing them on a diet with a modified sterol profile. Mature oocytes from such females fail to undergo normal reinitiation, but when incubated in vitro, can be induced to break their meiotic arrest by the addition of exogenous ecdysone. These results lend further support to the hypothesis that in Locusta, ovarian ecdysone is involved in the control of meiotic reinitiation.

Animals↗
PubMed1989

A monoclonal antibody against an adult-specific cuticular protein of Tenebrio molitor (Insecta, Coleoptera).

To study the sequential expression of the epidermal program in the mealworm Tenebrio molitor, monoclonal antibodies were prepared against the water-soluble proteins from preecdysial adult cuticle. Among the 16 clones obtained, one of them (named K2F6) recognized a 20-kDa antigen, found only in adult extracts but not in the larval or pupal ones, as revealed by immunoblot analysis. Our results strongly suggest an epidermal origin for this protein. The monoclonal antibody K2F6 fails to react with water-soluble proteins from fat body and hemolymph taken during the deposition of the 20-kDa antigen. Electron microscopic immunogold localization of this antigen showed that it is secreted, just after epicuticle deposition, in the 30 first-deposited preecdysial lamellae of sternal and elytral cuticles only. The sclerotizing process, which modifies the physicochemical properties of these cuticles, does not prevent the immunoreaction. When the expression of the adult program was inhibited by application of a juvenile hormone analog (ZR 515), the water-soluble proteins from different pupal-adult intermediates were never recognized by the monoclonal antibody K2F6 using immunoblot analysis. These results support the conclusion that this 20-kDa antigen is a protein specific for the sclerotized cuticle of the adult stage.

Animals↗
PubMed1992

What are and what are not imaginal discs: reevaluation of some basic concepts (Insecta, Holometabola).

Some general aspects of the concept of imaginal discs in the Holometabola are reevaluated. Their monolayer character and continuity with the surrounding epidermis are confirmed. Studies on the imaginal discs of the silkworm (Bombyx mori) and data from the literature show that the discs and their peripodial cells produce cuticle during larval life, as well as at metamorphosis. In B. mori it is demonstrated that adult and larval antennae are produced by the same cells or their progeny. The results also suggest that segments of the typically three-segmented larval antenna of Holometabola are not scape, pedicel, and one-segmented flagellum; at least segments 2 and 3 are of flagellar origin. Based on these and some additional facts it is argued that: (1) No larval organs are "replaced" at metamorphosis, but strict "sequential homology" is always maintained. (2) Imaginal discs are not undifferentiated structures destined to form the adult after larval breakdown, cannot be unambiguously defined, and do not represent qualitatively different epidermal structures. Classical imaginal discs (invaginated and present also in pre-final larval instars) arose several times independently and were not present in the larvae of ancestral Holometabola. (3) Since the disc cells are not undifferentiated and "embryonic" (if these words have a defined meaning at all), it is unreasonable to expect that the processes taking place in discs at metamorphosis would differ fundamentally from those occurring in other diploid metamorphosing epidermal cells.

Animals↗
PubMed1985

Studies on the toxicity of some carbamate fungicides in Drosophila melanogaster Meig. (Insecta, Diptera).

This paper reports the effects of three commercial powders mixed into the diet, Dithane M-45 (mancozeb 80%), Pomarsol (thiram 80%) and Peltar (maneb 50% and methyltiophanate 25%) on survivorship of adults Drosophila and on the progeny. With wild-type adults (Oregon), fungicides were added to the diet at the rate recommended on the label. The mean lifespan was reduced by 42.5% (Pomarsol), 50% (Dithane M-45), and 83% (Peltar). For larvae of two strains (Oregon and triploid) intoxicated with Dithane M-45 and Peltar, a linear relationship was demonstrated between the doses and the percentage of the progeny reduction. The calculated doses inducing a 50% reduced progeny (PR50) are in the range of 400 to 700 ppm. With Pomarsol in the range of 500 to 1500 ppm and for the both strains, the progeny was decreased by about 60%. A very reduced size and a leg paralysis was observed with each toxic powder for Oregon and triploid flies. It appears that a triploid stock of chromosomes does not significantly modify the reaction of the flies.

Animals↗