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At least 595 records · Page 33Linked to original sources
PubMed1998

Characterization of apyrase activity from the salivary glands of the cat flea Ctenocephalides felis.

Apyrase activity (ATP diphosphohydrolase, EC 3.6.1.5) was detected in salivary glands of the cat flea Ctenocephalides felis. Whole extracts of salivary glands contain approximately 21 ng of protein, 145 U/mg ADP'ase and 158 U/mg ATP'ase activity; AMP is not hydrolysed by salivary gland extracts. DEAE-Sepharose CL-6B anion exchange chromatography, and Cibacron Blue affinity chromatography each give a single coincident peak of ADP/ATP'ase activity. Biogel P-100 gel filtration of salivary gland homogenates made in buffer containing Triton and protease inhibitors, separated enzymatic activity into 57 kD and 44 kD peaks of ADP/ATP'ase activity. Partially purified ADP/ATP'ases are dependent on divalent cations and activation increases between 0.125 mM and 5.0 mM calcium. At 5 mM, magnesium is almost equally effective as calcium in activating ADP/ATP'ase but manganese and zinc are less so, and EDTA abolishes activity. ADP/ATP'ases have a pH optima of 7-9. The Km for ADP hydrolysis by whole extracts and partially purified enzyme is approximately 66 microM ADP. The co-purification of ADP'ase and ATP'ase activity by three physiochemical techniques and parallelism between ADP and ATP hydrolysis under varying conditions of pH and activating cation indicates enzymatic activity is attributable to true apyrase(s).

Animals↗
PubMed2000

Evidence that kinetochore fibre microtubules shorten predominantly at the pole in anaphase flea-beetle spermatocytes.

Kinetochore spindle fibres in flea-beetle metaphase primary spermatocytes have two regions with distinct morphologies. As seen after staining with antibodies against tubulin, the kinetochore microtubules are tightly bundled in the 5 microm closest to the kinetochore but they splay out in the region closest to the pole. This morphology persists throughout anaphase. This distinct morphology allows one to deduce the site where kinetochore microtubules depolymerise during anaphase. During poleward movement of the autosomes in anaphase, the bundled region shortens by about 0.25 microm for each 1 microm the chromosome moves poleward; this suggests that, during anaphase, 75% of the kinetochore microtubule shortening occurs at the pole end. Sex chromosomes in metaphase cells are separated from the autosomes and do not move poleward at the same time as the autosomes: they are reported to move poleward when the autosomes are in metaphase, to stop part way to the poles, and to move poleward again as the autosomes do (Virkki 1970). Kinetochore microtubules of the sex chromosomes also have bundled and splayed regions; measurements of those regions suggest that these chromosomes may move poleward before the autosomes enter anaphase, but not afterwards.

Anaphase↗
PubMed2003

Astronomy (communication arising): black holes, fleas and microlithography.

Fresnel lenses allow almost perfect imaging in widely different circumstances, but their focus is perfect only for a single wavelength. Wang et al. have shown how the effective bandpass may be widened for X-ray microscopy by using a compound diffractive/refractive lens near to an absorption edge. A compound lens has also been proposed for high-energy astronomy, working well above all absorption edges. Although the scale is very different, we point out here that the principle is the same. Ever since Galileo constructed an astronomical telescope that he was able to reconfigure to study fleas and gnats, astronomy and microscopy have relied on optics that are closely related, but different in detail.

Animals↗
PubMed2003

New species of the fleas Farhangia and Nestivalius, from endemic rodents in Sulawesi, Indonesia.

The fleas (Siphonaptera: Pygiopsyllidae) Farhangia quattuordecimdentata sp. n. and Farhangia sedecimdentata sp. n. are described from pygmy squirrels (Prosciurillus spp.), and Nestivalius sulawesiensis sp. n. from murine rodents, all from Sulawesi, Indonesia. Both new species of Farhangia were collected in Central Sulawesi (Sulawesi Tengah); F. quattuordecimdentata sp. n. was recovered mainly from P. murinus, whereas F. sedecimdentata sp. n. was recovered mainly from P. leucomus. These new species are compared with the two previously described species of Farhangia: F. celebensis (Ewing) from P. murinus in North Sulawesi (Sulawesi Utara) and F. sciuri (Ewing) from the tree squirrel Callosciurus prevosti in Sabah (Borneo). Nestivalius sulawesiensis sp. n. was collected from six species of endemic murine rodents in both North and Central Sulawesi. It is compared to the morphologically similar N. pomerantzi (Traub) from Mindanao, which parasitizes murine hosts that are endemic to the Philippines.

Animals↗
PubMed2001

Demic structure and its relation with the distribution of an adaptive trait in Danish flea beetles.

The flea beetle Phyllotreta nemorum is an oligophagous species using crucifers as host plants. In Denmark two populations have been found which use Barbarea vulgaris ssp. arcuata (G-type) as a host plant, whereas this plant is unsuitable for the survival of the majority of P. nemorum. In the locations in which these two populations occur, alternative host plants are also present. The plants occur in patches, some of which contain a mixture of host plants. In this study of allozyme variation, genetic differentiation between P. nemorum using different host plants in patches in the two different localities was studied hierarchically to assess substructuring of the populations. Evidence was found for low, but significant, amounts of genetic differentiation between (sub)populations using spatially separated plant patches at a distance of approximately 100 m to 1 km (theta = 0.009) and between localities approximately 44 km apart (theta = 0.026), and there was an association between genetic differentiation and geographical distance. No genetic differentiation was found between beetles from different host plants with overlapping local distributions. No evidence was thus found for sympatric host race formation. The geographical distribution of genes enabling P. nemorum to use B. vulgaris as a host plant (100% 'resistant' beetles in samples from B. vulgaris, but much fewer on patches containing only alternative host plants) contrasts with the relatively low amount of genetic differentiation at the neutral allozyme loci. This distribution of 'resistant' beetles (to B. vulgaris defence) is likely to be influenced by local differences in selection and asymmetric gene flow.

Adaptation, Physiological↗
PubMedDate not supplied

Observations on a trypanosomatid flagellate in a flea, Peromyscopsylla silvatica spectabilis.

The method of attachment of a trypanosomatid parasite to the cuticular epithelium of the hindgut of a flea Peromyscopsylla silvatica spectabilis by a desmosome-like structure is described; the flagella are modified and have enlarged intraflagellar areas which occupy the whole surface area of the gut, including clefts and folds of the epithelium. Unusual features of the parasite itself include a very much reduced flagellar pocket and pellicular microtubules which are made up of doublets and triplets. The problems of differentiation and characterisation of monogenetic insect flagellates are discussed in the light of these findings.

Animals↗
PubMed1982

[On the phenology of the flea Xenopsylla cunicularis Smit, 1957 (Siphonaptera, Pulicidae) parasite of the European rabbit].

A population of Xenopsylla cunicularis parasite on the European rabbit Oryctolagus cuniculus was studied monthly during the year 1977 in the South-West of France. The large-scale emergence of adults take place at the beginning of summer. A major part of them is then found in the soil of the burrows. Reproduction lease at the beginning of autumn which is marked by a great mortality. Some fleas persisted in winter, and they are found on the hosts. The annual cycle of X. cunicularis is compared with that of Spilopsyllus cuniculi and the epidemiological interest is laid stress on.

Animals↗
PubMed1989

[Fleas from the Neuguén Province (Argentina); description of 4 new taxa (Insecta, Siphonaptera)].

The collect of 973 Fleas on various small terrestrial mammals, from December 1987 till May 1988, in the Neuquén Province (Argentina), has given 20 taxa. Hectopsylla pascuali n. sp., Plocopsylla consobrina n. sp., Agastopsylla boxi gibbosa n. ssp., Chiliopsylla allophyla tonnii n. ssp. are described. Plocopsylla diana Beaucournu, Gallardo and Launay, 1986, Ctenoparia inopinata Rothschild, 1909, Neotyphloceras crassispina chilensis Jordan, 1936, Tetrapsyllus satyrus Beaucournu and Torrés-Mura, 1986, Ectinorus martini Lewis, 1976, are new from Argentina.

Animals↗
PubMed1997

Susceptibility of the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae) to four pyrethroids.

The amounts of active ingredient required to kill adult Ctenocephalides felis fleas on filter insecticide impregnated papers were determined in an attempt to compare the activity of different active ingredients. The following compounds were tested: bioallethrin, deltamethrin, esbiothrin and permethrin. The LD50 and LD90 against Ctenocephalides felis were 121 and 770 mg/m2 respectively for bioallethrin, and 161 and 671 mg/m2 respectively for esbiothrin. For deltamethrin and permethrin, the LD50 were 0.38 and 23 mg/m2 respectively, and 15 and 60 mg/m2 respectively for LD90.

Animals↗
PubMed2000

The flea genus Sigmactenus (Siphonaptera: Leptopsyllidae): three new taxa from Sulawesi, updated identification key, and distribution map for all known species and subspecies.

One new species and two new subspecies of fleas are described. These are S. sulawesiensis n. sp. from North and Central Sulawesi, S. alticola pilosus n. ssp. from Central Sulawesi, and S. alticola crassinavis n. ssp. from North Sulawesi. All three of these new taxa are ectoparasites of native, endemic murine rodents. Two of the new taxa, S. sulawesiensis and S. alticola crassinavis, coexist on the same mountain, Gunung Moajat, in North Sulawesi. The related S. alticola alticola, which becomes the nominate subspecies, parasitises the murine rodent Maxomys alticola in northern Borneo (Sabah) and it is hypothesized that Sigmactenus first colonized Sulawesi as an ectoparasite of ancestral Maxomys, or perhaps Rattus, as these murines dispersed from southeast Asia to Sulawesi; 15 endemic murine rodent species belonging to these two genera are known to currently inhabit Sulawesi. An identification key and distribution map are included for all known species and subspecies of Sigmactenus. In addition to the three new taxa and S. a. alticola, these include: S. celebensis from South Sulawesi, S. timorensis from Timor, S. toxopeusi from New Guinea, and S. werneri from the Philippines (Mindanao and Negros).

Animals↗
PubMed2002

[A new flea species of the genus Allopsylla Beaucournu et Fain, 1982 (Siphonaptera: Ischnopsyllidae) from Central African Republic, found on a little known molossid bat].

A pair of Allopsylla lobayensis Beaucournu & Barrière, new species were collected the first of November 1999 in Ngotto forest, in the south-western part of the Lobaye basin, Central African Republic (CAR). The host specimen, a little known molossid bat (Myopterus whitleyi), constitutes the first record of this species in CAR. The new flea species appears taxonomically close to A. hetera Beaucournu & Fain, 1982, one of the two other Allopsylla species, previously know from other faunal regions (A. alloides in Nigeria and A. hetera in Democratic Republic of the Congo). The parasitism of three distinctly different hosts by the three known Allopsylla species raises questions regarding the host-parasite specificity of this group.

Animals↗
PubMed2003

Two new fleas (Siphonaptera: Ceratophyllidae: Leptopsyllinae) of Madagascar: Tsaractenus rodhaini n. sp. and Paractenopsyllus (Consobrinopsyllus n. subgen.) goodmani n. sp.

Following considerable sampling in Malagasy forests, two new species of endemic fleas from Madagascar are described. These are T. rodhaini n. sp. and P. goodmani n. sp., collected on small mammals. The material of T. rodhaini allows us to describe the previously unknown female of the genus Tsaractenus. We also complete the initial description of the genus with new diagnostic characters. Although it belongs to Paractenopsyllus, P. goodmani shows many unique characteristics. To help resolve certain systematic issues involving Malagasy Leptopsyllinae we introduce the new subgenus Consobrinopsyllus of Paractenopsyllus for P. goodmani. Its particular condition makes us consider valuable characters of the genus Tsaractenus. Carrying several traits of this genus, P. goodmani could constitute an intermediate step between the two endemic Malagasy leptopsylline genera. Considering these new findings the actual taxonomic position of the Malagasy genera among the Leptopsyllinae is discussed.

Animals↗
PubMed2004

[Two new species of fleas from Chile and Argentina(Insecta-Siphonaptera: Stephanocircidae and Rhopalopsyllidae) and raising of a new sub-genus of Plocopsylla Jordan, 1931].

A new subgenus of Plocopsylla is raised, Schrammapsylla Beaucournu and Ménier from the entire group B of Schramm & Lewis, 1988 and two new fleas from Chile and Argentina are described: Plocopsylla (S.) muruai n. sp. Beaucournu and Gallardo and Ectinorus (E.) mimacydis n. sp. Beaucournu and Gallardo. These two taxa are only known by the male sex.

Animals↗
PubMed1999

Heterogeneity and differential expression under hypoxia of two-domain hemoglobin chains in the water flea, Daphnia magna.

Hemoglobin (Hb) purified from the water flea, Daphnia magna, reared under hypoxia was analyzed by two-dimensional gel electrophoresis. The Hb was shown to be composed of six major subunit chain species (designated as DHbA to DHbF). The NH2-terminal amino acid sequences of DHbA, DHbB, DHbC, and DHbF are different from one another, indicating that at least four Hb genes are present in D. magna. The NH2-terminal amino acid sequences of DHbD and DHbE are the same as those of DHbA and DHbB, respectively. The six Hb chains were also found in the animal reared under normoxia in small amounts and with altered composition; the extent of decrease under normoxia was higher in the amounts of DHbC, DHbD, and DHbF than those of others. These results indicate that the Hb genes are differentially regulated by the ambient oxygen concentration. Four Hb genes constituting a cluster in the order, dhb4, dhb3, dhb1, and dhb2, were found on the chromosome of D. magna. The complete nucleotide sequences of the dhb1, dhb2, and dhb3 genes and their cDNAs showed that the genes have a seven-exon, six-intron structure. The structure consists of an intron separating an exon encoding a secretory signal sequence, two large repeated regions of a three-exon, two-intron structure that encode each a domain containing a heme-binding site, and an intron bridging the two repeated regions. The deduced amino acid sequences of the gene products showed higher than 79% identity to one another and showed unique features conserved in D. magna Hb chains. The analysis also suggested that DHbB (or DHbE), DHbF, and DHbC are encoded by the dhb1, dhb2, and dhb3 genes, respectively.

Amino Acid Sequence↗
PubMed1998

Seroprevalence of Bartonella henselae in cattery cats: association with cattery hygiene and flea infestation.

We attempted to determine what factors were common to catteries with high Bartonella henselae antibody prevalence compared with catteries with low prevalence, in order to contribute to better guidelines for the choice of a safe pet cat. The overall seroprevalence in 11 catteries from diverse geographical locations in North America in the present study was 35.8%. There was evidence of B. henselae exposure in all 11 homes tested, with 5 catteries being heavily infected. The distribution of B. henselae exposure was bimodal in catteries: either most or all cats in the home had been exposed, or very few or no cats had been exposed. Prevalence per home was also correlated with the home mean antibody titre. Flea infestation was the most important risk factor for high B. henselae seroprevalence in the catteries we surveyed. Individual cat titres were comparable for male and female cats, cats of various ages, and cats with concurrent infectious diseases. There was no association of B. henselae with cattery size, husbandry practices, presence or absence of rescued cats, dog ownership, attending cat shows, routine visits to a veterinarian, and outside travel. In summary, cattery cats can be easily identified as high or low risk to new potential cat owners.

Animal Husbandry↗
PubMedDate not supplied

Effect of salinity on the swimming velocity of the water flea Daphnia magna.

The swimming velocity of the water flea Daphnia magna is dependent on its body size. Therefore, environmental factors that influence growth also influence swimming velocity. This study examined whether exposure to increased salinity reduces swimming velocity only through its effect on body size or whether it also reduces size-specific swimming velocity. Initially, size-specific swimming velocity decreased in a salinity-dependent way. Thereafter, swimming velocities gradually returned to their expected values in all treatments. This acclimation coincided with considerable mortality in the highest-salinity treatment, indicating that daphnids in this treatment either acclimated or died. The initial decrease in size-specific swimming velocity could not be explained by decreased uptake of food. Thus, the results indicate that salinity temporarily impaired physiology. The experiment illustrates how size effects can be accounted for in swimming-velocity analysis and how size-specific swimming-velocity analysis can be used as a non-invasive method to detect stress-induced deviations from normal physiology.

Adaptation, Physiological↗
PubMed1989

Susceptibility of the cat flea (Siphonaptera: Pulicidae) to pyrethroids.

Adult cat fleas, Ctenocephalides felis felis (Bouché), from two laboratory colonies (one originating in California and one from Florida) were exposed to residues of eight pyrethroids to compare their susceptibilities. The Florida strain was more tolerant than the California strain, with 6.8-, 5.2-, and 4.8-fold tolerance to cyfluthrin, cypermethrin, and fluvalinate, respectively. The Florida strain showed less than 3-fold tolerance to the other five insecticides (permethrin, tralomethrin, d-phenothrin, resmethrin, and fenvalerate). Overall, the pyrethroids were ineffective against the Florida strain.

Animals↗