Cell Death in Salivary Glands of Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae) Females at Semi-engorged Feeding Stage

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rhipicephalus (Boophilus) microplus: Distinct acute phase proteins vary during infestations according to the genetic composition of the bovine hosts, Bos taurus and Bos indicus

Tick bites may trigger acute phase responses. Positive and negative acute phase proteins were measured in infested cattle genetically resistant and susceptible to ticks. During heavier infestations levels of haptoglobin increased significantly in susceptible bovines; levels of serum amyloid A increased in resistant bovines; levels of alpha-l-acid glycoprotein decreased significantly in resistant bovines; levels of transferrin decreased significantly in susceptible bovines.In conclusion, tick infestations trigger acute phase responses and enhancement of specific acute phase proteins differs according to the genetic composition of hosts. Acute phase proteins may constitute useful biological signatures for monitoring the stress induced by tick infestations. (c) 2007 Elsevier B.V. All rights reserved.

Controle de larvas de Boophilus microplus por Metarhizium anisopliae em pastagens infestadas artificialmente

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of Metarhizium anisopliae fungus on off-host Rhipicephalus (Boophilus) microplus from tick-infested pasture under cattle grazing in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cellular and molecular characterization of an embryonic cell line (BME26) from the tick Rhipicephalus (Boophilus) microplus

The cellular and molecular characteristics of a cell line (BME26) derived from embryos of the cattle tick Rhipicephalus (Boophilus) microplus were studied. The cells contained glycogen inclusions, numerous mitochondria, and vesicles with heterogeneous electron densities dispersed throughout the cytoplasm. Vesicles contained lipids and sequestered palladium meso-porphyrin (Pd-mP) and rhodamine-hemoglobin, suggesting their involvement in the autophagic and endocytic pathways. The cells phagocytosed yeast and expressed genes encoding the antimicrobial peptides (microplusin and defensin). A cDNA library was made and 898 unique mRNA sequences were obtained. Among them, 556 sequences were not significantly similar to any sequence found in public databases. Annotation using Gene Ontology revealed transcripts related to several different functional classes. We identified transcripts involved in immune response such as ferritin, serine proteases, protease inhibitors,. antimicrobial peptides, heat shock protein, glutathione S-transferase, peroxidase, and NADPH oxidase. BME26 cells transfected with a plasmid carrying a red fluorescent protein reporter gene (DsRed2) transiently expressed DsRed2 for up to 5 weeks. We conclude that BME26 can be used to experimentally analyze diverse biological processes that occur in R. (B.) microplus such as the innate immune response to tick-borne pathogens. (C) 2008 Elsevier Ltd. All rights reserved.

In vitro acaricidal activity of neem (Azadirachta indica) seed extracts with known azadirachtin concentrations against Rhipicephalus microplus

The effect of four extracts from neem seeds (Azadirachta indica) containing 2000, 5000, 9000 and 10,000 ppm of azadirachtin A (AZA), quantified by high-performance liquid chromatography (HPLC) and diluted to 1.25%; 2.5%; 5.0%; 10.0% and 12.8% was verified by in vitro tests with engorged females and larvae of the cattle tick Rhipicephalus micro plus. The results from the bioassays with the engorged females showed that the main toxic effect of the extracts was reduction of the reproductive parameters, with a sharp drop in the number of eggs laid and the hatching rate, mainly when the extracts were diluted to 10.0% and 12.8%. The product effectiveness (PE) calculations for all the solutions tested showed that the AZA solution at 10,000 ppm (N10) was the most effective. However, statistical analysis of the PE data obtained for the proportional AZA concentrations in the different diluted extracts showed significance (P<0.05) of the effects included in the model (extract dilution, principle effect (classificatory) of the assay (extract) and the interaction between the two), indicating significant variations due to the dilution, the test and the interaction between the two factors in the tests with engorged females. For solutions N2, N5, and N9, it was not possible to estimate LC(90) values in the dilution range tested. The lowest LC(50) was observed for extract N5, and although extract N10 was the only extract for which the LC(90) could be estimated within the range tested, the LC(50) was higher than for N5 and N9. These results suggest that substances other than AZA present in the extracts influenced the efficacy, especially up to a certain LC range. In the tests with larvae, no mortality was observed, indicating zero effectiveness of all the extracts tested. The results of the tests with engorged females showed that the neem extracts had acaricide activity, inhibiting egg laying and the larval hatching rate. Complementary studies are necessary to develop new methods to isolate and/or identify other substances besides AZA contained in this plant, to enable using products made from it as acaricides. (C) 2011 Elsevier B.V. All rights reserved.

Resistance of cattle of various genetic groups to the tick Rhipicephalus microplus and the relationship with coat traits

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mapping of quantitative trait loci controlling tick [Riphicephalus (Boophilus) microplus] resistance on bovine chromosomes 5, 7 and 14

Differences in domestication and selection processes have contributed to considerable phenotypic and genotypic differences between Bos taurus and Bos indicus cattle breeds. of particular interest in tropical and subtropical production environments are those genetic differences between subspecies that underlie the phenotypic extremes in tolerance and susceptibility to parasite infection. In general, B. taurus cattle are more susceptible to ectoparasites than B. indicus cattle in tropical environments, and much of this difference is under genetic control. To identify genomic regions involved in tick resistance, we developed a B. taurus x B. indicus F-2 experimental population to map quantitative trait loci (QTL) for resistance to the Riphicephalus (Boophilus) microplus tick. About 300 individuals were measured for parasite load in two seasons (rainy and dry) and genotyped for 23 microsatellite markers covering chromosomes 5, 7 and 14. We mapped a suggestive chromosome-wide QTL for tick load in the rainy season (P < 0.05) on chromosome 5. For the dry season, suggestive (P < 0.10) chromosome-wide QTL were mapped on chromosomes 7 and 14. The additive effect of the QTL on chromosome 14 corresponds to 3.18% of the total observed phenotypic variance. Our QTL-mapping study has identified different genomic regions controlling tick resistance; these QTL were dependent upon the season in which the ticks were counted, suggesting that the QTL in question may depend on environmental factors.

Babesia spp. infection in Boophilus microplus engorged females and eggs in São Paulo State, Brazil

Babesia spp. infections were investigated in Bos taurus x Bos indicus dairy cows and calves and in Boophilus microplus engorged female ticks and eggs. Blood samples and engorged female ticks were collected from 25 cows and 27 calves. Babesia spp. was detected in ticks by microscopic examination of hemolymph of engorged female and by squashes of egg samples. Cattle infection was investigated in blood thin smears and by DNA amplification methods (PCR and nested PCR), using specific primers for Babesia bovis and Babesia bigemina. Merozoites of B. bovis (3 animals) and B. bigemina (12 animals) were detected exclusively in blood smears of calves. DNA amplification methods revealed that the frequency of B. bigemina infection in calves (92.6%) and in cows (84%) and of B. bovis in calves (85.2%) and in cows (100%) did not differ significantly (P > 0.05). Babesia spp. infection was more frequent in female ticks and eggs collected from calves (P < 0.01) than from cows, especially in those which had patent parasitemia. Hatching rates of B. microplus larvae were assessed according to the origin of engorged females, parasiternia of the vertebrate host, frequency and intensity of infection in engorged female tick, and frequency of egg infection. Hatching rate was lower in samples collected from calves (P < 0.01) than from cows, and in those in which Babesia spp. was detected in egg samples (P < 0.01). Published by Elsevier B.V.

Detection of Babesia bigemina in cattle of different genetic groups and in Rhipicephalus (Boophilus) microplus tick

Babesia bigemina infections were investigated in four genetic groups of beef cattle and in Rhipicephalus (Boophilus) microplus engorged female ticks. Blood samples and engorged female ticks were collected from 15 cows and 15 calves from each of the following genetic groups: Nelore, Angus x Nelore, Canchim x Nelore, and Simmental x Nelore. Microscopic examination of blood smears and tick hemolymph revealed that merozoites of B. bigemina (6/60) as well as kinetes of Babesia spp. (9/549) were only detected in samples (blood and ticks, respectively) originated from calves. PCR-based methods using primers for specific detection of B. bigemina revealed 100% infection in both calves and cows, regardless the genetic group. Tick infection was detected by nested-PCR amplifications showing that the frequency of B. bigemina was higher (P 0.01) in female ticks collected from calves (134/549) than in those collected from cows (52/553). The frequency of B. bigemina was similar in ticks collected from animals, either cows or calves, of the four genetic groups (P > 0.05). (C) 2008 Elsevier B.V. All rights reserved.

Oocysts of Hepatozoon canis in Rhipicephalus (Boophilus) microplus collected from a naturally infected dog

Canine hepatozoonosis is a tick-borne disease caused by protozoans of the genus Hepatozoon. Several tick species have been implicated as potential vectors. Therefore, extensive studies are needed to determine the 'natural' endemic cycle of this parasite. This paper presents the first report of the presence of Hepatozoon canis oocysts in Rhipicephalus (Boophilus) microplus collected from an infected dog. (C) 2011 Elsevier B.V. All rights reserved.

Morphological, histological, and ultrastructural characterization of degenerating salivary glands in females of the cattle-tick Rhipicephalus (Boophilus) microplus (CANESTRINI, 1887) (Acari : Ixodidae)

The present study describes the morphology and ultrastructure of the salivary glands of semi-engorged females of the southern cattle-tick Rhipicephalus (Boophilus) microplus. The acini that compose these glands, at that specific feeding stage, show cells featuring degenerative process of the salivary glands, such as: vacuolated cytoplasm, condensed chromatin, fragmented nuclei, and presence of apoptotic bodies. In addition, the presence of microorganisms was detected, with morphology typical of protozoa, inside these organs. (c) 2005 Elsevier Ltd. All rights reserved.

Structural and cytochemical changes in the salivary glands of the Rhipicephalus (Boophilus) microplus (CANESTRINI, 1887) (Acari : Ixodidae) tick female during feeding

This study describes the morphology of salivary glands of Rhipicephalus (Boophilus) microplus female ticks at beginning of feeding (24-48 h of attachment) and semi-engorged (4-5 days of attachment) to verify the degenerative characteristics of these organs and the secretory phase in which the process begins. At the beginning of feeding, secretion granules had been observed only in the cytoplasm of cells b, c(1), c(2), c(4) (type II acinus) and d (type III acinus), as well as large nuclei with regular and preserved morphology. In the semi-engorged females the acini presented few normal cells, few partially preserved ones, and the remaining ones in several stages of degeneration, that is, with retraction and cytoplasmic vacuolization, and nuclei with chromatin in several stages of condensation, picnotic and/or in fragmentation. In type I acinus and in the excretory ducts of the studied glands, at both feeding stages, no degenerative characteristic was observed. In females of R. (B.) microplus, the salivary glands degenerate asynchronically and precociously when compared with those of others tick's species. (c) 2006 Elsevier B.V. All rights reserved.

Morphological, histological, and ultrastructural studies of the ovary of the cattle-tick Boophilus microplus (Canestrini, 1887) (Acari : Ixodidae)

This study presents the morphology of the ovary, as well as the dynamics of the vitellogenesis process in oocytes of the cattle-tick Boophilus microplus. The ovary of these individuals is of the panoistic type; therefore, it lacks nurse cells. This organ consists of a single tubular structure, continuous, and composed of a lumen delimitated by a wall of small epithelial cells with rounded nuclei. In this tick species, the oocytes were classified into six stages varying from I to VI and according to: cytoplasm appearance and presence of the germ vesicle, yolk granules, and chorion. Oocytes of various sizes and at different developmental stages remain attached to the ovary through a cellular pedicel until completing stage V. Afterwards, they are liberated into the lumen and from there to the exterior. Some oocytes (classified as type VI) showed an atypical appearance indicating that some of the cellular components would be undergoing a degenerative process and/or reabsorption. (c) 2004 Elsevier B.V. All rights reserved.