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PubMed2005

Coping with predator stress: interclonal differences in induction of heat-shock proteins in the water flea Daphnia magna.

Although predation is a strong selection pressure, little is known about the molecular mechanisms to cope with predator stress. This is crucial to understanding of the mechanisms and constraints involved in the evolution of antipredator traits. We quantified the expression of heat-shock protein 60 (Hsp60), a potential marker for predator stress, in four clones of the water flea Daphnia magna, when exposed to fish kairomones. Expression of Hsp60 induction increased after 6 h and returned to base levels after 24 h of predator stress. This suggests that it is a costly transient mechanism to temporarily cope with novel predator stress, before other defences are induced. We found genetic variation in the fixed levels and in the fish-induced levels of Hsp60, which seemed to be linked to each clone's history of fish predation. Our data suggest that Hsp60 can be considered part of a multiple-trait antipredator defence strategy of Daphnia clones to cope with predator stress.

Adaptation, Physiological↗
PubMedDate not supplied

Nolleria pulicis n. gen., n. sp. (Microsporida: Chytridiopsidae), a microsporidian parasite of the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae).

A new species of microsporidium, Nolleria pulicis, is described and named here from the cat flea, Ctenocephalides felis. The genus Nolleria is created and placed within the family Chytridiopsidae. The family is slightly modified to accommodate certain features of intracellular development seen in N. pulicis, which is otherwise very similar to other species in the family Chytridiopsidae. Sporulation is described from ultrastructural analysis of infected midgut epithelial cells of adult C. felis. The term "multiple division by vacuolation" is proposed for describing sporogony as it occurs in this species and certain related species of microsporidia. The probable mode of transmission and apparent absence of merogony are discussed.

Animals↗
PubMed2005

Glycine-rich antifreeze proteins from snow fleas.

We purified antifreeze proteins from winter-active snow fleas, Hypogastrura harveyi. These 6.5- and 15.7-kilodalton thermolabile proteins are glycine-rich (45% of the residues), and the short isoform is composed of the tripeptide repeat Gly-X-X. This makes them very different from other antifreeze proteins, including two from insects, suggesting independent adaptation to freezing environments.

Amino Acid Sequence↗
PubMed1968

Flea Ctenophthalmus: heterogeneous hexagonally organized layer in the midgut.

The ventriculus or midgut of adult fleas of the genus Ctenophthalmus (Hystricopsyllidae) is surrounded by a complex investment consisting of a "beaded layer," circumferential and longitudinal muscles, minute fibrils of the sort commonly called collagenous, and a granular layer at the boundary of the hemocoel. The beaded layer is remarkable in consisting of two types of short cylinders of greatly different diameters, each type arranged in a mixed hexagonal array.

Animals↗
PubMed2006

Rickettsia felis from cat fleas: isolation and culture in a tick-derived cell line.

Rickettsia felis, the etiologic agent of spotted fever, is maintained in cat fleas by vertical transmission and resembles other tick-borne spotted fever group rickettsiae. In the present study, we utilized an Ixodes scapularis-derived tick cell line, ISE6, to achieve isolation and propagation of R. felis. A cytopathic effect of increased vacuolization was commonly observed in R. felis-infected cells, while lysis of host cells was not evident despite large numbers of rickettsiae. Electron microscopy identified rickettsia-like organisms in ISE6 cells, and sequence analyses of portions of the citrate synthase (gltA), 16S rRNA, Rickettsia genus-specific 17-kDa antigen, and spotted fever group-specific outer membrane protein A (ompA) genes and, notably, R. felis conjugative plasmids indicate that this cultivatable strain (LSU) was R. felis. Establishment of R. felis (LSU) in a tick-derived cell line provides an alternative and promising system for the expansion of studies investigating the interactions between R. felis and arthropod hosts.

Animals↗
PubMed1995

Isolation, cultivation, and partial characterization of the ELB agent associated with cat fleas.

ELB rickettsiae from cat flea homogenates were recovered in tissue culture cells following sequential passage through laboratory rats and the yolk sacs of embryonated chicken eggs. Seven days after inoculation of ELB from the infected yolk sacs, Vero cells and L929 cells were observed to contain intracellular bacteria as demonstrated by Diff Quik and indirect immunofluorescence assay staining. The rickettsial and ELB identity of the cultured agent was confirmed by PCR detection of the 16S rRNA and citrate synthase genes and PCR-restriction fragment length polymorphism analysis of the 17-kDa conserved rickettsial antigen gene. The ELB rickettsiae induced plaques in Vero cells on day 11 postinfection. Rat anti-ELB serum reacted at 1:4,096 to cultured ELB and had lower reactivity to Rickettsia typhi Wilmington (1:1,024), Rickettsia akari Kaplan (1:512), and Rickettsia australis JC (1:64). Spotted fever group polyclonal sera also exhibited lower reactivity to ELB than to the homologous antigen. Coomassie blue-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles of the ELB isolate and two R. typhi strains were identical.

Animals↗
PubMed2004

Evaluation of the role of constitutive isocitrate lyase activity in Yersinia pestis infection of the flea vector and mammalian host.

Yersinia pestis, unlike the closely related Yersinia pseudotuberculosis, constitutively produces isocitrate lyase (ICL). Here we show that the Y. pestis aceA homologue encodes ICL and is required for growth on acetate but not for flea infection or virulence in mice. Thus, deregulation of the glyoxylate pathway does not underlie the recent adaptation of Y. pestis to arthropod-borne transmission.

Animals↗
PubMed2005

Analysis of expressed sequence tags of the water flea Daphnia magna.

To study gene expression in the water flea Daphnia magna we constructed a cDNA library and characterized the expressed sequence tags (ESTs) of 7210 clones. The EST sequences clustered into 2958 nonredundant groups. BLAST analyses of both protein and DNA databases showed that 1218 (41%) of the unique sequences shared significant similarities to known nucleotide or amino acid sequences, whereas the remaining 1740 (59%) showed no significant similarities to other genes. Clustering analysis revealed particularly high expression of genes related to ATP synthesis, structural proteins, and proteases. The cDNA clones and EST sequence information should be useful for future functional analysis of daphnid biology and investigation of the links between ecology and genomics.

Animals↗
PubMed2000

The pattern of sex chromosome kinetochore phosphorylation during nonrandom segregation in a flea beetle.

In the flea beetle species, Alagoasa bicolor, males have two sex chromosomes, X and Y, each of which is larger than the rest of the genome combined. These large sex chromosomes do not pair at meiosis I, and are therefore not joined at metaphase I. Nevertheless, they always segregate from each other at anaphase I. As prometaphase I progresses, the unpaired X and Y undergo reorientation from a parallel to a linear configuration. Using 3F3/2, an antibody that detects the level of phosphorylation of a kinetochore protein or proteins, we have determined that this reorientation is not accompanied by a change in the level of phosphorylation of the kinetochores of either X or Y. This implies that: i) either the reorientation does not involve the loss or gain of kinetochore microtubules, or ii) if such loss or gain occurs, it does not effect a change in the tension placed on the nonrandomly segregating kinetochores, or iii) the sex chromosomes, as in some other species, have lost the ability to sense kinetochore tension changes. Evolution of nonrandom segregation may necessitate the inability of the participating chromosomes to affect the metaphase checkpoint.

Animals↗
PubMed2006

Incidence and distribution pattern of Rickettsia felis in peridomestic fleas from Andalusia, Southeast Spain.

The presence of Rickettsia felis was investigated in three species of pulicid fleas (Ctenocephalides felis, Ctenocephalides canis and Pulex irritans) collected in 38 locales in Andalusia (Spain) over the period 1999-2004. Amplification of a fragment of OmpB gene was positive in 54.17 % of lots of Ct. felis. The identity of the PCR bands was confirmed as R. felis by sequence data obtained directly from the PCR amplicon. No rickettsia was found in Ct. canis nor P. irritans.

Animals↗
PubMed2003

Microtubule distribution during meiosis I in flea-beetle [Alagoasa (Oedionychus)] spermatocytes: evidence for direct connections between unpaired sex chromosomes.

The meiosis-I spindle in flea-beetle spermatocytes is unusual in that the autosomes and univalent sex chromosomes are separated by a mitochondrial sheath and move polewards at different times. To help understand the basis for this interesting chromosome behaviour, and to gather more detailed information about it, we studied microtubule distributions throughout meiosis I using immunofluorescence and confocal microscopy, and took careful measurements of pole and kinetochore positions at all stages of division. Our results show that, by late prophase, there is a spindle-shaped cytoplasmic array of microtubules in the central part of the cell, with the nucleus at the periphery. Following nuclear envelope breakdown, both autosomes and sex chromosomes become associated with cytoplasmic microtubules, although only the autosomes move centrally to the 'cytoplasmic spindle'. The two unpaired sex chromosomes remain at the cell periphery and appear to be connected to each other by a microtubule bundle extending between their kinetochores. These bundles often persist into anaphase. Analysis of measurements taken from fixed/stained cells supports previous observations that sex chromosomes move part way to the pole in early prometaphase and then stop. The measurements also suggest that during autosomal anaphase, spindle elongation precedes autosome movement to the poles and polewards movement of sex chromosomes is limited or absent when autosomes are moving polewards.

Acetylation↗
PubMed1995

Ballistics and visual targeting in flea-beetles (Alticinae)

The kinematics of jumping was measured in seven species of flea-beetle (Alticinae). The accuracy of two species during targeted jumping was also investigated. Take-off accelerations ranged from 15 to 270 times gravity. Rotational energy accounted for 4­21 % of the total translational energy. Two species were able to control jump direction and landing. When presented with a high-contrast optical grid, Chalcoides aurata exhibited two alternative jump modes. In mode 1 or wingless jumping, the body rotated continuously, the insect rarely landed on its feet and no discrimination was shown between landing on the black or white stripes of the grid. In mode 2 jumping, recruitment of the wings eliminated rotation and virtually ensured a feet-first landing; there was also a significant preference for jumping towards the black stripes. Aphthona atrocaerulea could alter take-off angle in order to strike targets at inclinations of 0­90 ° to the horizontal. Targets consisting of a white illuminated cross on a black background were struck with equal accuracy, regardless of distance (within the normal jumping range). The beetle aimed specifically for the centre of the target and not for the high-contrast boundary. The distribution of hits about the target centre was radially symmetrical. Although take-off was wingless, rotation could be abolished in mid jump, within 10 ms, by extending the wings. This virtually guaranteed a feet-first landing. Targeting accuracy is discussed in the context of biomechanical steering mechanisms and visual control.

Journal Article↗
PubMedDate not supplied

Parasite genotypically related to a monoxenous trypanosomatid of dog's flea causing opportunistic infection in an HIV positive patient.

An HIV positive patient presenting a clinical picture of visceral leishmaniasis co-infection was submitted to a bone marrow aspiration after admission to hospital. Amastigotes forms were seen in the bone marrow aspirate and the parasite grew in culture as promastigotes. Molecular analyses showed that the flagellates isolated did not belong to the genera Leishmania, Trypanosoma or Sauroleishmania. It was not possible to establish infection in laboratory animals. In vitro culture of mouse peritoneal macrophages revealed the invasion of the host cells by the flagellates and their killing 48 hr after infection. Opportunistic infection with an insect trypanosomatid was suspected. Further hybridization analyses against a panel of different monoxenous and heteroxenous trypanosomatids showed kDNA cross-homology with Leptomonas pulexsimulantis a trypanosomatid found in the dog's flea.

AIDS-Related Opportunistic Infections↗
PubMed2000

Effects of pyriproxyfen spray, powder, and oral bait treatments on the relative abundance of fleas (Siphonaptera: Ceratophyllidae) in black-tailed prairie dog (Rodentia: Sciuridae) towns.

Separate black-tailed prairie dog, Cynomys ludovicianus (Ord), towns on the Rocky Mountain Arsenal National Wildlife Refuge, Colorado, were treated with technical pyriproxyfen (Nylar) using spray, powder, and oral bait carriers. Direct combing methods (1997 and 1998) and burrow flagging (1998) were used to estimate relative abundance of the plague vector Oropsylla hirsuta (Baker). Pyriproxyfen spray (0.05%) and powder (0.05%) did not significantly reduce (P > 0.05) O. hirsuta abundance. Pyriproxyfen bait, when applied every 4 wk at a concentration of 286 mg/50 g bait, significantly reduced (P < or = 0.05) O. hirsuta infesting prairie dogs, 4 mo after initial treatment. However, flea populations had recovered to pretreatment levels by the following summer (July 1999).

Animals↗
PubMed2001

Effect of air temperature and humidity on the survival of pre-imaginal stages of two flea species (Siphonaptera: Pulicidae).

The survival of immatture fleas at 25 and 28 degrees C and 40, 55, 75, and 92% RH was studied to test the hypothesis that the difference in microclimatic preferences determines habitat distribution of Xenopsylla conformis Wagner, 1903 and Xenopsylla ramesis Rothschild, 1904. Survival of X. conformis eggs did not depend on either temperature or humidity or both, whereas eggs of X. ramesis survived significantly less at 40% RH than at higher humidities. No larva of either species survived at 40% RH at either temperature. Larval survival of both species at both temperature regimes was significantly lower at 55% humidity than at higher humidities. Maximal survival time of larvae that died before pupation depended on both temperature and humidity in both species. Change of humidity during early stages of the life cycle (from egg to larva) increased the maximal survival time in X. conformis larvae but decreased that in X. ramesis larvae. Pupal survival was higher at higher humidities independent of temperature. Survival of X. conformis pupae was lower than that of X. ramesis pupae when the relative humidity was low. Humidity change on later stages (from larva to cocoon) decreased X. conformis pupal survival and had no effect on X. ramesis pupal survival. The sex ratio of emerged adults was not affected by either temperature or humidity in both species. Changes in humidity between egg and larval emvironments significantly decreased the percentage of females in X. conformis emergence at 28 degrees C.

Air↗
PubMed2000

Cat flea (Ctenocephalides felis) infestation in quarantined marsh deer (Blastocerus dichotomus) populations.

Marsh deer (Blastocerus dichotomus) were captured for a research program in Brazil and maintained in quarantine stations. After 60 days, fleas were detected on animals and identified as Ctenocephalides felis felis. Elimination of the infestation was difficult. Animal treatment with a fipronil-based compound was effective, and subsequently captured animals were treated prophylactically. Some animals remained infested, and some died from the infestation.

Animals↗
PubMed2002

Rickettsia felis in Ctenocephalides spp. fleas, Brazil.

In June 2000, suspected cases of Brazilian spotted fever (BSF) occurred in Coronel Fabriciano Municipality, Minas Gerais State, Brazil. Pooled fleas collected near two fatal cases contained rickettsial DNA. The nucleotide sequence alignment of the 391-bp segment of the 17-kDa protein gene showed that the products were identical to each other and to the R. felis 17-kDa gene, confirming circulation of R. felis in Brazil.

Animals↗