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At least 73 records · Page 4Linked to original sources

Inhibition of the DNA amplification of trypanosomes present in tsetse flies midguts: implications for the identification of trypanosome species in wild tsetse flies.

The present study was carried out in order to investigate if there was really a failure of PCR in identifying parasitologically positive tsetse flies in the field. Tsetse flies (Glossina palpalis gambiensis and Glossina morsitans morsitans) were therefore experimentally infected with two different species of Trypanosoma (Trypanosoma brucei gambiense or Trypanosoma congolense). A total of 152 tsetse flies were dissected, and organs of each fly (midgut, proboscis or salivary glands) were examined. The positive organs were then analysed using PCR. Results showed that, regardless of the trypanosome species, PCR failed to amplify 40% of the parasitologically positive midguts. This failure, which does not occur with diluted samples, is likely to be caused by an inhibition of the amplification reaction. This finding has important implications for the detection and the identification of trypanosome species in wild tsetse flies.

Animals↗

Negative and translation termination-dependent positive control of FLI-1 protein synthesis by conserved overlapping 5' upstream open reading frames in Fli-1 mRNA.

The proto-oncogene Fli-1 encodes a transcription factor of the ets family whose overexpression is associated with multiple virally induced leukemias in mouse, inhibits murine and avian erythroid cell differentiation, and induces drastic perturbations of early development in Xenopus. This study demonstrates the surprisingly sophisticated regulation of Fli-1 mRNA translation. We establish that two FLI-1 protein isoforms (of 51 and 48 kDa) detected by Western blotting in vivo are synthesized by alternative translation initiation through the use of two highly conserved in-frame initiation codons, AUG +1 and AUG +100. Furthermore, we show that the synthesis of these two FLI-1 isoforms is regulated by two short overlapping 5' upstream open reading frames (uORF) beginning at two highly conserved upstream initiation codons, AUG -41 and GUG -37, and terminating at two highly conserved stop codons, UGA +35 and UAA +15. The mutational analysis of these two 5' uORF revealed that each of them negatively regulates FLI-1 protein synthesis by precluding cap-dependent scanning to the 48- and 51-kDa AUG codons. Simultaneously, the translation termination of the two 5' uORF appears to enhance 48-kDa protein synthesis, by allowing downstream reinitiation at the 48-kDa AUG codon, and 51-kDa protein synthesis, by allowing scanning ribosomes to pile up and consequently allowing upstream initiation at the 51-kDa AUG codon. To our knowledge, this is the first example of a cellular mRNA displaying overlapping 5' uORF whose translation termination appears to be involved in the positive control of translation initiation at both downstream and upstream initiation codons.

3T3 Cells↗

[Improving the salivation technic in the tsetse fly for the detection of infective metatripanosomes: study of the effect of biologic and non-biologic factors in the probing behavior of the tsetse fly].

The probing and salivation behaviour on a warm slide of three tsetse fly species or subspecies (glossina morsitans morsitans, Glossina palpalis gambiensis, Glossina tachinoides) was examined with respect to various parameters (species, sex, age, starvation period, trypanosome infection, quality of support). Each fly was given the opportunity to probe the warm slide (38 degrees C) for 5 minutes (we mean by probing an attempt to touch the glass slide by the proboscis in a biting position). G.m morsitans is by far the most efficient at probing (70.50%) when compared with G. tachinoides (50.50%) and G. palpalis gambiensis (45.80%). Globally, males (61.30%) are more active than females (52%) and those of the morsitans group are more active than those of the palpalis group. Teneral flies probe more easily than non-teneral flies, with an increased advantage in G. m. morsitans. The starvation period increases the probing behaviour, but at 48 h. G. m. morsitans probed as much as G. palpalis gambiensis and G. tachinoides at 72 h. The males of G. m. morsitans and G. palpalis gambiensis are more precocious than females, but the inverse is observed in G. tachinoides. Infection by T. congolense (EATRO 325 strain) does not affect the probing behaviour of males of all 3 species but seems to lower that of females in the palpalis group. Addition of a drop of PSG or blood improves the probing behaviour of infected G. m. morsitans females (the only ones tested). The results are discussed in relation to biological data and knowledge of the receptor systems of tsetse flies.

Animals↗

Cuticular hydrocarbons of buffalo fly, Haematobia exigua, and chemotaxonomic differentiation from horn fly, H. irritans.

We determined the quantity and chemical composition of cuticular hydrocarbons of different strains, sexes, and ages of buffalo flies, Haematobia exigua. The quantity of cuticular hydrocarbons increased from less than 1 microg/fly for newly emerged flies to over 11 microg/fly in 13-d-old flies. The hydrocarbon chain length varied from C(21) to C(29), with unbranched alkanes and monounsaturated alkenes the major components. Newly emerged flies contained almost exclusively C(27) hydrocarbons. Increasing age was accompanied by the appearance of hydrocarbons with shorter carbon chains and an increase in the proportion of alkenes. 11-Tricosene and 7-tricosene were the most abundant hydrocarbons in mature H. exigua. Cuticular hydrocarbons of H. exigua are distinctly different from those of horn flies, Haematobia irritans. The most noticeable differences were in the C(23) alkenes, with the major isomers 11- and 7-tricosene in H. exigua and (Z)-9- and (Z)-5-tricosene in H. irritans, respectively. Cuticular hydrocarbon analysis provides a reliable method to differentiate the two species, which are morphologically difficult to separate. The differences in cuticular hydrocarbons also support their recognition as separate species, H. exigua and H. irritans, rather than as subspecies.

Alkenes↗

Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment.

The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na(2)SO(4)+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al(2)O(3) content of the fly ash. The diffusion of SO(4)(2-), Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition.

Coal↗

New diets for production of house flies and stable flies (Diptera: Muscidae) in the laboratory.

A diet for rearing the house fly, Musca domestica (L.), was developed from feed constituents available on a year-round basis in Gainesville, FL. The diet, called the Gainesville House Fly Diet, performed as well or better than the Chemical Specialties Manufacturers' Association fly larval medium (CSMA) and can be mixed, bagged, and delivered by a local feed mill within 3 d. By adding pelleted peanut hulls 1:1 by volume, the house fly diet becomes suitable for rearing the stable fly, Stomoxys calcitrans (L.). Use of these diets and the economics involved are discussed further.

Animal Feed↗

The Drosophila alcohol dehydrogenase gene may have evolved independently of the functionally homologous medfly, olive fly, and flesh fly genes.

cDNAs for alcohol dehydrogenase (ADH) isozymes were cloned and sequenced from two tephritid fruit flies, the medfly Ceratitis capitata and the olive fly Bactrocera oleae. Because of the high sequence divergence compared with the Drosophila sequences, the medfly cDNAs were cloned using sequence information from the purified proteins, and the olive fly cDNAs were cloned by functional complementation in yeast. The medfly peptide sequences are about 83% identical to each other, and the corresponding mRNAs have the tissue distribution shown by the corresponding isozymes, ADH-1 and ADH-2. The olive fly peptide sequence is more closely related to medfly ADH-2. The tephritid ADHs share less than 40% sequence identity with Drosophila ADH and ADH-related genes but are >57% identical to the ADH of the flesh fly Sarcophaga peregrina, a more distantly related species. To explain this unexpected finding, it is proposed that the ADH: genes of the family Drosophilidae may not be orthologous to the ADH: genes of the other two families, Tephritidae and Sarcophagidae.

Alcohol Dehydrogenase↗

Sound radiation around a flying fly.

Many insects produce sounds during flight. These acoustic emissions result from the oscillation of the wings in air. To date, most studies have measured the frequency characteristics of flight sounds, leaving other acoustic characteristics--and their possible biological functions--unexplored. Here, using close-range acoustic recording, we describe both the directional radiation pattern and the detailed frequency composition of the sound produced by a tethered flying (Lucilia sericata). The flapping wings produce a sound wave consisting of a series of harmonics, the first harmonic occurring around 190 Hz. In the horizontal plane of the fly, the first harmonic shows a dipolelike amplitude distribution whereas the second harmonic shows a monopolelike radiation pattern. The first frequency component is dominant in front of the fly while the second harmonic is dominant at the sides. Sound with a broad frequency content, typical of that produced by wind, is also recorded at the back of the fly. This sound qualifies as pseudo-sound and results from the vortices generated during wing kinematics. Frequency and amplitude features may be used by flies in different behavioral contexts such as sexual communication, competitive communication, or navigation within the environment.

Acoustics↗

A shot in the dark: the silent quest of a free-flying phonotactic fly.

To reproduce, females of the parasitoid fly Ormia ochracea detect and localise a calling male cricket upon which they deposit their endoparasitic larvae. Calling male crickets are therefore subject to both sexual and natural selection by simultaneously attracting mates and phonotactic parasitoids. The possible strategy of song interruption employed by the cricket host to reduce his attractiveness to acoustic parasitoids was tested in the laboratory by examining the fly's phonotactic quest in response to synthetic cricket songs. Phonotactic flight trajectories were recorded in three dimensions with a stereo infrared video tracking system while the sound stimulus was controlled on-line as a function of the fly's position in space. Within a single flight, three distinct phases could be observed: a take-off phase, a cruising phase, during which course and altitude were rather constant, and a landing phase characterised by a spiralling descent towards the sound source. The flies showed remarkable phonotactic accuracy in darkness; they landed at a mean distance of 8.2 cm from the centre of the loudspeaker after a flight distance of approximately 4 m. The present data illustrate the fly's surprising ability to gauge the direction and distance of a sound source in three dimensions and, subsequently, to find it in darkness and silence.

Acoustic Stimulation↗

Improved attractants for Mediterranean fruit fly, Ceratitis capitata (Wiedemann): responses of sterile and wild flies to (-) enantiomer of ceralure B1.

Tests were conducted on wild Mediterranean fruit flies, Ceratitis capiata (Wiedemann), in Hawaii, Italy, and Kenya, and on sterile released flies in Florida and California with a new male attractant, (-)-ceralure B1. Compared on an equal dosage basis, Mediterranean fruit fly males were significantly more attracted to the (-)-ceralure B1 than to trimedlure in each of the sites tested except for California. Compared with the standard commercial 2 g trimedlure plug, 10 mg applied on cotton wicks (Kauai) was as attractive to wild males as trimedlure after the first 2 d of the test but not after 7 d. At a dose of 40 mg (50 times less than in the 2-g plug), the (-)-ceralure B1 was significantly more attractive to male flies than the 2-g trimedlure plug for the first week of service (Florida) but not after 2 wk. Studies using released sterile flies in Florida confirm our previous work on the improved attraction of (-)-ceralure B1 (40 mg) over trimedlure. However, this trend did not hold up in a single test conducted in a residential area in California that did not show a significant difference in attraction using 20 mg of compound. Future refinements in synthesis and costs of this compound and increased availability and testing will be needed before any final evaluation in the field can be carried out.

Animals↗

Assessment of parasitism of house fly and stable fly (Diptera: Muscidae) pupae by pteromalid (Hymenoptera: Pteromalidae) parasitoids using a polymerase chain reaction assay.

The internal transcribed spacer (ITS) regions of the ribosomal DNA of house flies, Musca domestica L., the stable flies, Stomoxys calcitrans (L.), and four parasitoid species in the genus Muscidifurax (Hymenoptera: Pteromalidae) were characterized to develop a method based on the polymerase chain reaction (PCR) to better define the role of pteromalid parasitism of pupae of the house fly and stable fly. Two parasitoid-specific primers were designed to anneal to the 5' end of the 5.8S rRNA gene in the parasitoid species. When paired with a universal primer at the 3' end of the 18S rRNA, the primers amplified the target ITS1 region in 10 pteromalid species. PCR allowed detection of parasitoid DNA within 24 h after females of Spalangia endius Walker oviposited into house fly puparia. PCR failed to amplify parasitoid DNA or detect parasitism in puparia that were exposed to parasitoid oviposition, allowed to develop 7 d, then killed by freezing and held at 20-24 degrees C for 4 d to allow DNA degradation. Digestion of the PCR products with restriction enzymes produced restriction fragment length polymorphisms that allowed identification of individual parasitoid species. Significantly greater levels of parasitism (P < 0.05) were detected by PCR for two of the five field collection dates in 1997. On the dates when PCR detected higher levels of parasitism than estimates provided by emergence of adult insects from samples taken at Feedlot M in 1997, more than 65% of all puparia in the emergence samples failed to produce an adult insect. Three puparia collected in 1997 produced double PCR bands that corresponded to PCR band sizes of Muscidifurax spp. and Spalangia sp., possibly indicating multiple parasitism or hyperparasitism.

Animals↗

Ets-1 regulates fli-1 expression in endothelial cells. Identification of ETS binding sites in the fli-1 gene promoter.

To understand the role of the Ets-1 transcription factor during angiogenesis, we have overexpressed it in endothelial cells and analyzed the levels of expression of several candidate target genes involved in angiogenesis. The transcripts levels of the ETS transcription factor fli-1 are specifically up-regulated in endothelial cells, which overexpress Ets-1, but not in fibroblasts. Analysis of the promoter of the mouse fli-1 gene reveals that the 1-kb region that comprises the transcription starts and part of exon 1 is responsible for the response of the promoter to Ets-1. The -270/-41 fragment contains two known Spi-1-responding Ets binding sites (EBS), which are also necessary for the activation by Ets-1. In contrast to Spi-1, a third EBS is necessary for the full response of this promoter fragment to Ets-1. The rest of the promoter activity has been located in the -986/-505 region, where three active EBSs have been identified. Furthermore, endogenous Fli-1 was found to be bound to its own gene promoter and to be able to promote the transactivation of its gene. These results suggest that Ets-1 activates an auto-regulatory loop of expression of fli-1 in endothelial cells, a mechanism that could have significant implications for the endothelial cell fate.

3T3 Cells↗

[Observations on tsetse flies in a forest focus of human trypanosomiasis in Ivory Coast. 3. Dispersal and distribution of fly populations around a village (author's transl)].

In the Vavoua human trypanosomiasis focus (forest zone of Ivory Coast) four tsetse fly catching series, of nine days each, were made during the rainy season using eighty five biconical traps. The dispersion of flies in the study area was studied by the mark-release-recapture method. Two series of two sets of capture-mark-release were carried out. In the first set flies were captured, marked and released in their point of origin and in the second set captured and marked in the village periphery but released in coffee plantations and vice versa. A total of 10198 tsetse flies were marked and released and 267 were recaptured. There was no difference between recapture rates of the different village or plantation released G. palpalis; this suggested that the same population was living in different biotops. Males and females from the periphery of the village behaved differently. Males dispersed evenly in contrast to females which remained in their original area. This difference in dispersion of the two sexes may be of epidmiological importance for human trypanosomiasis. Of interest was the discovery of a small community of peri-domestic G. pallicera during the periods March--April and May. The estimation of tsetse population by the Lincoln Index, is related to the dispersive power of the species concerned. When evaluated through the recapture rate this was found to be ten and seven times higher for G. pallicera and G. nigrofusca respectively, than for G. palpalis. This difference may be important in explaining the phenomenon of reinvasion and the little apparent effect of insecticidal control on the two former species.

Animals↗

Courtship dances in the flies of the genus Lispe (Diptera: Muscidae): from the fly's viewpoint.

Two predatory fly species, Lispe consanguinea Loew, 1858 and L. tentaculata DeGeer, 1776, inhabit the supralittoral zone at the shore of a fresh-water reservoir. Both species look alike and possess similar "badges," reflective concave silvery scales on the face. Flies occupy different lek habitats. Males of the first species patrol the bare wet sand on the beach just above the surf. Males of the second species reside on the more textured heaps of algae and stones. Courtship and aggressive behaviour of males was video-recorded and analysed frame by frame. Visual stimuli provided by the conspecific partner were computed in the body-fixed space of a fly observer. Males of L. consanguinea perform long pedestrian dances of pendulating circular arcs (frequency 2 s(-1), median radius 2.5 cm, linear velocity 0.130 m/s). Right and left side runs are equally probable. Circular runs are interrupted by standby intervals of average duration 0.35 s. The female views the male as a target covering 2 by 2 ommatidia, moving abruptly with the angular velocity over 200 degrees/s in a horizontal direction down the path of about 50 degrees till the next standpoint. Dancing is evenly distributed around the female. On the contrary, the male fixates the image of the female within the narrow front sector (median +/-10 degrees); the target in his view has 6-7 times less angular velocity and angular span of oscillations, and its image in profile overlays 6-8 by 2 ommatidia. If the female walks, the male combines tracking with voluntary circular dances. Rival males circle about one another at a distance shorter than 15 mm, but not in close contact. Males of L. tentaculata are capable of similar circular courting dances, but do so rarely. Usually they try to mount any partner immediately. In the latter species, male combat consists of fierce wrestling. Flies of both species often walk sideward and observe the partner not in front but at the side.

Aggression↗

Genome reorganization from polyteny to polyploidy in the nurse cells found in onion fly (Delia antiqua) and cabbage root fly (Delia radicum) ovaries (Diptera, Anthomyiidae).

The material required to ensure successful embryogenesis in the onion fly (Delia antiqua) and the cabbage root fly (Delia radicum) (Diptera, Anthomyiidae) is supplied by 15 nurse cells, while the oocyte chromosomes enter a quiescent stage during prophase I of meiosis. This level of transcription is achieved by the polyploidization of the nurse cell DNA. Elongate polytene chromosomes form in both species, but lack the banding and conspicuous puffing commonly seen in other dipteran tissues. The polytene chromosomes contract until they finally appear as small, densely staining spheres. These fragment into large numbers of endochromosomes that are much smaller than their mitotic counterparts, which then despiralize, resulting in the flocculate appearance of the nurse cell nucleus. Photodensitometry revealed a gradient of DNA values between nurse cells near the oocytes and those further away. Final DNA values 1000 times the haploid level were recorded in the nurse cell nearest to the oocyte compared with 336 times the C-value in the most distal cell. At lower temperatures (< 10 degrees C), the polytene chromosomes become banded and longer. None of the onion flies kept in these conditions produced viable eggs, though there was some reproductive success among the cabbage root flies.

Animals↗

Surface ultrastructure of the puparia of the blow fly, Lucilia cuprina (Diptera: Calliphoridae), and flesh fly, Liosarcophaga dux (Diptera: Sarcophagidae).

Surface ultrastructure of the puparia of the blow fly, Lucilia cuprina, and flesh fly, Liosarcophaga dux, are presented utilizing scanning electron microscopy (SEM). Emphasis was focused on characteristic features of the puparia that could be used for differentiation from other forensically important fly species. The puparium of L. cuprina typically measures 6.2+/-0.2 mm in length and 2.3+/-0.1 mm in width. Each anterior spiracle contains a single row of 5-7 papillae. The intersegmental spines between the prothorax and mesothorax are triangular with constricted tips. A clustered bubble membrane, comprising about 30 mammillate structures, is positioned dorsolaterally on each side of the first abdominal segment in young puparia but is replaced by short, tubular respiratory horns in aged puparia. The posterior end of the puparium is broadly truncate and bears a pair of medially positioned posterior spiracles that each contains three straight spiracular slits. The puparium of L. dux is larger in comparison to L. cuprina and typically measures 9.9+/-0.3 mm in length and 3.8+/-0.2 mm in width. An anterior spiracle of this species contains 14-17 papillae. The intersegmental spines between the prothorax and mesothorax are broad and triangular. A convoluted structure of unknown function was observed at the dorsolateral edge of segments 5-11. In L. dux, the caudal segment of the puparium is slightly tapered and abruptly truncated and contains a pair of posterior spiracles that are located within a deep concavity in the terminal end. Each posterior spiracular disc appears D-shaped, with a pronounced medial projection and three vertically oriented long, narrow spiracular slits. The anatomical features presented herein may be useful for identification of fly puparia of these two species in future forensic entomological investigations.

Animal Structures↗

Trigeminal nerve section induces Fos-like immunoreactivity (FLI) in brainstem and decreases FLI in sensory cortex.

Transecting the infraorbital nerve to the rat whiskers induced Fos-like immunoreactivity (FLI) in lamina I and II neuronal nuclei of the spinal trigeminal nucleus pars caudalis (Sp5c). The Fos-like immunostaining persisted for several weeks. The prolonged expression of FLI in Sp5c could be related to persistent activity in the sectioned nerve, or to trophic effects of injured ganglion neurons on brainstem cells. We postulate that Fos and related proteins may be involved in mediating alterations in gene expression associated with relatively long-term CNS adaptations to peripheral nerve injuries. Surprisingly, FLI decreased in contralateral sensory cortex, mainly in layers 2, 3 and 6, up to several days after the lesion. These decreases of cortical FLI may be due to decreased sensory neuronal activity, and/or to reducing the trophic influence of thalamic inputs on cortical neurons.

Animals↗

Identification of PVK/CAP2b neuropeptides from single neurohemal organs of the stable fly and horn fly via MALDI-TOF/TOF tandem mass spectrometry.

MALDI-TOF/TOF tandem mass spectrometry has been applied to determine the complete sequences of the PVK/CAP2b neuropeptides in the stable fly Stomoxys calcitrans and horn fly Haematobia irritans, insect pests of livestock. This peptidomic analysis of single neurohemal organ preparations allows the unambiguous assignment of internal Leu/Ile positions not distinguishable by previous mass spectrometric techniques. The sequences are as follows: Stoca-PVK/CAP2b-1, AGGASGLYAFPRVa; Stoca-PVK/CAP2b-2, NAKLYPVPRVa; and Haeir-PVK/CAP2b-1, AGGASGLYAFPRVa; Haeir-PVK/CAP2b-1, NAKLYPMPRVa. Both Stoca-PVK/CAP2b-1 and -2 stimulate Malpighian tubule fluid secretion in the stable fly, with EC50 values between 3 and 11 nM. The identification of these novel neuropeptides adds to our knowledge of the peptidomes of flies, and can aid in the development of neuropeptide-based control strategies of these insect pests.

Amino Acid Sequence↗