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[New mermithid genera and species parasitic in fleas].

A new genus and a new species Imosmermis morosovi gen. sp. n. found in the flea Xenopsilla gerbilli minor Jordan are described. The genus Imosmermis differs from all known genera of Mermithidae by the absence of mouth and reduction of stihostome and the dorsal chord. Body is long and very thin. A new genus Aphanimermis comb. n. for the species Psyllomermis tshumacovae Rubzov is created. This genus is characterized with a stilet, with high developed lateral and ventral chord as well as with a tail which is absent in other genera infecting fleas.

Animals↗

Efficacy of lufenuron against developmental stages of fleas (Ctenocephalides felis felis) in dogs housed in simulated home environments.

Twenty-four, adult, female Beagles were arranged by body weight from greatest to least and allocated to 2 groups of 12 dogs, using random numbers. Dogs were housed collectively in 2 adjacent metal buildings, each divided into 4 rooms measuring 2.1 x 3.7 m. Each room was paneled and carpeted and had an access door to the outside with a connecting run that measured 2.1 x 9.1 m. Each run had a surface consisting of 5 cm of pea gravel overlaying 5 cm of sand, and was partially covered by an awning that provided shade at its proximal end. For placement in room/run units, dogs in each of the treated and control groups were alloted to 4 subgroups of 3 dogs each. Each subgroup of dogs was placed in a separate room/run unit. Units containing treatment or control subgroups were alternated to avoid placing identically treated subgroups adjacent to each other. Dogs of subgroups A, C, E, and G were treated with lufenuron monthly at a minimal target dosage of 10 mg/kg of body weight; those of subgroups B, D, F, and H were treated with excipient tablets. Dogs were treated on study days 7, 37, 68, and 98. Each dog was infested with 100 newly emerged, unfed, insectary-reared, adult Ctenocephalides felis on each of study days 0 and 2. Thereafter, infestations on all dogs were dependent on continued development of fleas either in the indoor or outdoor environment. Numbers of fleas on each of the treated and control dogs were determined, using a nondestructive counting technique on days 6, 14, 21, 28, 35, 56, 70, 84, 98, 112, and 119.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[The variability of Yersinia pestis in the body of the flea].

Changes in the morphology and ultrastructure of Y.pestis cells at different periods of their stay in the body of fleas (Citellophilus tesquorum altaicus) have been studied. The study, carried out by means of optical and electron microscopy, as well as with the use of a culture medium for the isolation of L-forms, has revealed that in the body of fleas Y.pestis cells undergo the effect of processes leading to their L-transformation. As the result of L-transformation, the infective agent may take altered forms, including L-like variants. Such forms are retained in hungry insects and are capable of prolonged survival in the body of the carrier.

Animals↗

[The factors that regulate oviposition in Leptopsylla segnis (Leptopsyllidae: Siphonaptera) fleas].

In the fleas Leptopsylla segnis settled on white mice the steady egg-laying took place under conditions including three factors--darkness, high relative air humidity (80-100%) and the "smell of host nest". The absence of anyone of these factors reduced an egg-production by 34-56%. The removal of the "smell" source coupled with substitution of high air humidity on low one (50-60%) interrupted the egg-laying almost completely inspite darkness or light. Owing such reaction on joint influence of the "smell of host nest" and air humidity the fleas are capable to interrupt and to recommence egg-laying depending on either the host is outside or in the nest.

Animals↗

[Histological study of Ceratophyllus consimilis Wagn. fleas infected with the causative agent of listeriosis (Listeria monocytogenes)].

Histological studies have shown that in experimentally infected fleas (C. consimilis) Listeria are preserved in the alimentary canal. In infected individuals microbes occur along the whole intestine, from oesophagus to the rectum but most often they are recorded from the mid-gut and proventriculus. Listeria are able to penetrate into its muscular tissue and in some cases enter the body cavity of the insect. The finding of Listeria in the oesophagus confirms the possibility of the transmission of the infarction by fleas through the bite without blocking.

Animals↗

[Domestic cats as a source of human flea infestations in towns].

During the summer and autumn periods of 1990-1992 a periodic massive incidence, infestation as well as parasitization of humans with flea Ctenocephalides felis were recorded in the basements of flat blocks in the central area of Kosice. The urban population of domestic cats served as a source of the infestation. The dark field examination of fleas for the presence of borrelias revealed negative results.

Animals↗

[The dependence of egg-laying activity on the number of Leptopsylla segnis (Siphonaptera: Leptopsyllidae) fleas on the host].

The egg-laying activity in the fleas Leptopsylla segnis Schonherr declined when their number on the host (white mouse) was risen from 2-5 to 20. However, if the number of the parasites on host exceeded 30 the egg output per female increased. It is supposed, there is an density-dependent regulation of egg-laying activity in L. segnis, which operates in certain diapason of flea abundance. It appears that mechanism of this regulation is suppressed by heavy infestation.

Animals↗

[The flea fauna of small mammals in Kostroma Province].

There were 22 species of fleas recorded on different Rodentia and Insectivora in Kostroma Province. The flea species M. turbidus, M. penicilliger, M. walkeri, C. agyrtes, C. uncinatus, P. sylvatica dominate on the rodents, and the species C. bisoctodentatus, P. soricis, P. kohauti, D. dasycnema dominate on the insectivores.

Animals↗

[The host-loyalty index of fleas, its analysis and importance in plague epizootiology].

Simple geographical models using chronometric parasitic characteristics were applied to substantiate the determination of the host-loyalty index of fleas. A mathematical relationship was inferred between the number of fleas feeding on a single rodent within a time unit and their quantity and the duration of an once-through parasitizing.

Animals↗

Sticktight fleas associated with fowl pox in a backyard chicken flock in California.

A mixed breed rooster, from a backyard flock of 13 chickens, was received at California Veterinary Diagnostic Laboratory System-Turlock Branch for postmortem examination. The bird presented with thickened, featherless, scab-encrusted skin around the head region. Numerous sticktight fleas were found attached to the encrusted skin. Microscopic evaluation of the skin revealed a lymphoplasmacytic reaction in the dermis with visible embedded flea mouthparts. Also noted histologically in this region were epidermal hyperplasia and ballooned epidermal cells containing intracytoplasmic inclusions indicative of fowl poxvirus.

Animals↗

[The preservation of the causative agent of intestinal yersiniosis in Xenopsylla cheopis fleas].

Experimentally infected fleas of X. cheopis are capable of preserving two strains of Y. enterocolitica. One of the strains was found to belong to the 3rd, the other to the 9th serotype. The both strains actively multiplied and accumulated in great amount (up to several millions of microbial cells) in ectoparasites which were maintained at 6 to 8 degrees C. At a temperature of 18 to 21 degrees C some part of fleas gradually became free from the agent that was favoured by their periodical feeding or constant maintenance on the host. In insects infected with the strain of the 3rd serotype the decrease of the infected individuals carried out quicker and was accompanied by the reduction in the number of microbes. The strain of the 9th serotype preserved more steadily and was found in many individuals in amount exceeding the initial level.

Animals↗

[A study on the transmission of plague though seven kinds of fleas in rat type and wild rodent type plague foci in Yunnan].

In order to assess vector position and vector action of seven kinds of fleas in the rat type and wild rodent type plague foci in Yunnan, we studied the indices as: infection rate, rate of feed bacterial emboli, colony transmission vector efficiency, life-span, bloodthirsty to human, body weight, quantity of blood-sucking, rate of dissociation by using animal model and raise film method. The results showed that Xenopsylla cheopis and Neopsylla specialis specialis were the main vectors of two type plague foci. Pulex irritans was an important vector of human plague in Yunnan. This paper reported that Xenopsylla cheopis and Neopsylla special special could twice form bacterial emboli, and with other information about vector efficiency, Index of Pulex irritans, Neopsylla special special, Frontopsylla spadix, Monopsyllus anisus, rate of bloodthirsty to human and life-span of seven kinds of fleas. Reason from quiescence to resuscitate was also deduced and the vector position of Leptopsylla segnis was revised. The vector action of main vector for Ctenophalmus quadratus was negated which proved that Apodemus chevrieri was the main reservoirs in these plague foci.

Animals↗

[Pathological changes in fleas caused by the action of Bacillus thuringiensis exotoxin].

Pathogenic effect of the crystalline exotoxine of Bacillus thuringiensis on the larvae of fleas was investigated. Deformities and changes in the functions of organs and tissues caused by the exotoxin in larvae and imago developed from the latter result in the premature death of the individuals (to 100%) or in the sterility of the remaining fleas.

Abnormalities, Drug-Induced↗

The genome sequence of a flea beetle, Neocrepidodera transversa (Marsham, 1802).

We present a genome assembly from a male specimen of Neocrepidodera transversa (flea beetle; Arthropoda; Insecta; Coleoptera; Chrysomelidae). The genome sequence has a total length of 671.30 megabases. Most of the assembly (93.58%) is scaffolded into 21 chromosomal pseudomolecules, including the X chromosome. The mitochondrial genome has also been assembled and is 17.02 kilobases in length. Gene annotation of this assembly on Ensembl identified 13,840 protein-coding genes.

Coleoptera↗

The genome sequence of a flea beetle, Altica lythri Aubé, 1843.

We present a genome assembly from a female specimen of Altica lythri (flea beetle; Arthropoda; Insecta; Coleoptera; Chrysomelidae). This was a triploid specimen and one subgenome was assembled. The genome sequence has a total length of 1,003.51 megabases. Most of the assembly (82.29%) is scaffolded into 12 chromosomal pseudomolecules, including the X sex chromosome. The mitochondrial genome has also been assembled, with a length of 18.39 kilobases. Gene annotation of this assembly on Ensembl identified 18,969 protein-coding genes.

Altica lythri↗

[A histologic study of Ceratophyllus consimilis Wagn. fleas infected by the agent of murine typhus (Salmonella typhimurium)].

Histological studies of C. consimilis infected with S. typhimurium have shown that the microbes are preserves along the whole extent of the alimentary canal, expecially in the midgut and pyloric portion. Bacteria are concentrated in the gastral cavity; in addition, they were found to penetrate the alimentary epithelium cells and pyloric valve tissue. The number of microbes and their distribution in the intestine undergo great variations that depends largely on the insects feeding rhythm. During bloodsucking a "lavenment" of the alimantary canal takes place; as a result, numerous microbes accumulated here are periodically excreted outside. The infection with Salmonella typhimurium is often accompanied by pathological changes in fleas tht is expressed in the destruction of the midgut epithelium and pyloric valve tissue.

Animals↗

Flow cytometry of cell proliferation through the incorporation of bromodeoxyuridine as an index of growth rate in the water flea, Daphnia magna (Crustacea, Cladocera).

BACKGROUND: In this paper, we used a small crustacean as a model to develop a method for quantifying growth rates through the measurement of a cell proliferation marker. This was done in order to study the feasibility of this assay for estimating zooplankton production in the ocean. Flow cytometry immunodetection of bromodeoxyuridine (BrdU) was performed to detect and quantify the cycling nuclei of Daphnia magna. METHODS: A combination of mechanical dissociation and cell enucleation procedures proved to be the most convenient method for preparing nuclear suspensions from whole organisms. Up to three populations of nuclei with different ploidy were observed. The relative abundance of these nuclear populations changed with the size of the flea. RESULTS: The staining technique has been optimized. The time and concentration for the maximum detection of BrdU-labeled nuclei were 3 h at 300 microM BrdU. Whole organisms can be frozen (-20 degrees C) after incubation with no changes in the final results. The method was used in different physiological conditions under controlled food and temperature in order to test the inverse relationship between physiological rates and size of organisms at several developmental stages. The quantification of BrdU-labeled nuclei in 1-6 day-old larvae showed the highest labeling index, with a mean of 95 +/- 1% (n = 22). In contrast, young animals (0.8-1.2 mm) had 25 +/- 4% (n =16, P < 0.001) and adults (>1.4mm) had 14 +/- 3% (n = 4, P < 0.001). The results obtained show an expected tendency, suggesting that a direct relationship exists between the labeling index and the instantaneous growth rate. CONCLUSIONS: Certain features of our method, such as the short times required for labeling and the possibility of preserving the samples during field experiments and under different conditions (including natural concentrations and types of food), are advantageous to the study of processes governing energy fluxes in pelagic ecosystems.

Animals↗

Identification, characterization, and cloning of an immunoglobulin degrading enzyme in the cat flea, Ctenocephalides felis.

The degradation of cat immunoglobulin G (IgG) in blood-fed adult C. felis midguts was examined. SDS-PAGE analysis of dissected midgut extracts obtained from C. felis that had been blood fed for various times between 0 to 44 h revealed that by 24 h most of the high molecular weight proteins, including the heavy chain of IgG, were digested. A 31-kDa serine protease with IgG degrading activity was purified from fed C. felis midguts by benzamidine affinity chromatography, hydrophobic interaction chromatography, and cation exchange chromatography. Three primary cleavage products between 30- and 40-kDa were observed when the purified protease was incubated with protein A purified cat IgG. N-terminal amino acid sequence analysis of the products revealed that the IgG degrading protease cleaves after specific cysteine and lysine residues within the hinge region of IgG. The enzyme is also capable of degrading other immunoglobulins, serum albumin, and hemoglobin, suggesting that it may have roles in both combating the host's immune system and providing nutrients for the flea. A cDNA clone encoding the 265 amino acid IgG degrading protease proenzyme was isolated. When expressed in a baculovirus/insect cell expression system, the recombinant protein had the same N-terminus as the processed 237 amino acid mature native protein and possessed IgG degrading activity indistinguishable from the native protein. Arch. Insect Biochem.

Amino Acid Sequence↗