The natural hosts of larvae and nymphs of Amblyomma tigrinum Koch, 1844 (Acari: Ixodidae)     

Nava S  Mangold AJ  Guglielmone AA 《Veterinary parasitology》2006,140(1-2):124-132

The hosts of larvae and nymphs of Amblyomma tigrinum, a tick whose adults feed on wild and domestic Canidae in South America, are uncertain. A 17 months survey was carried out trapping wild vertebrates in north-western Córdoba, Argentina, to evaluate their parasitism with A. tigrinum subadults. Larvae and nymphs of this tick species were identified conventionally and by comparison of 16S rDNA sequences with GenBank deposited sequences. A total of 207 small and medium-sized rodents and 182 birds were captured and examined for ticks. Most ticks on birds were from ground forest feeding birds (BB) with a minimal contribution of birds feeding in open pastures. All ticks from rodents were obtained from representatives of the families Cricetidae (SR) and Caviidae (MR). Percent of larvae infestation was higher (P<0.01, Chi-square distribution) in BB (55.2%) and SR (46.4%) than in MR (17.4%) and the same trend was found for number of larvae on these hosts (test of Kruskal-Wallis). Caviidae (only representative Galea musteloides) rodents were extremely prone to be infested with nymphs of A. tigrinum (94.2%) followed by BB (50.6%) and SR (3.6%) (P<0.01) and the same tendency was found for number of nymphs (P<0.01). The index of aggregation for nymphs on MR was the lowest (0.409) followed by nymphs on BB (0.706) which may be a consequence of higher and homogenous exposure of G. musteloides to host-seeking nymphs. Several BB are food source for both larvae and nymphs of A. tigrinum while for rodents larvae were common only on SR (mainly on the Sigmodontinae Akodon dolores and Graomys sp.) and nymphs feed almost exclusively on MR. Therefore, both birds and rodents are of importance for the survival strategy of A. tigrinum subadults. The plasticity of A. tigrinum to colonize areas with different climates plus the capacity of their subadults to feed on hosts widely distributed indicates that this tick has the potential to become a widespread parasite but this does not seem to be the actual situation. Several proposals are presented to further understand its ecology.  相似文献   

Seroprevalence of caprine arthritis-encephalitis virus in goats in the Cariri region, Paraiba state, Brazil     

Bandeira DA  de Castro RS  Azevedo EO  de Souza Seixas Melo L  de Melo CB 《Veterinary journal (London, England : 1997)》2009,180(3):399-401

The seroprevalence of caprine arthritis–encephalitis virus (CAEV) in the Cariri Region of Paraíba State, Brazil, was determined in 60 goat herds using the agar gel immunodiffusion test. The overall seroprevalence was 8.2%, with seropositivity in 21/60 (35%) herds and 13/15 (86.6%) municipalities. Bucks had a significantly higher frequency of infection (28.3%) than does (5.9%), and bucks that originated in other states had a significantly higher frequency of infection (76.5%) than those from Paraíba State (9.3%).  相似文献   

Seasonal dynamics and hosts of Amblyomma triste (Acari: Ixodidae) in Argentina     

Nava S  Mangold AJ  Mastropaolo M  Venzal JM  Fracassi N  Guglielmone AA 《Veterinary parasitology》2011,181(2-4):301-308

The seasonal dynamics and host usage of Amblyomma triste in Argentina were analyzed. Adults of A. triste were present from early winter to mid-summer, with the peak of abundance from late winter to mid-spring (August to October). Larvae and nymphs were found from December to June, with the peak of abundance in summer. There were no differences among the biological parameters (pre-moult period of larvae and nymphs, pre-oviposition period of females, and minimum incubation period of eggs) of engorged ticks exposed to different photoperiod regimens at the laboratory, but the periods for each biological parameter obtained from ticks exposed in the field were significantly longer than those from the laboratory. Field results fit better with the data of seasonal distribution of each stage. Morphogenetic diapause was not detected, but complementary studies should test the presence of behavioral diapause. Rodents of the subfamily Sigmodontinae (Akodon azarae, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus rufus and Scapteromys aquaticus) are the principal hosts for immature stages of A. triste, the caviid Cavia aperea could be another potential host for these stages, and birds are exceptional hosts for larvae and nymphs. Regarding hosts of adults in Argentina, domestic and wild large-sized mammals belonging to different orders (cattle, dog, horse, Blastocerus dichotomus and Hydrochoerus hydrochaeris) serve as hosts for adults of this tick species. In conclusion, A. triste has a life cycle of 1 year with adults feeding on large endemic and introduced mammals and immature stages using sigmodontine and caviid rodents as hosts.  相似文献   

Anti-<Emphasis Type="Italic">Leptospira</Emphasis> sp. agglutinins in ewes in the Federal District,Brazil     

Luiza de S. Seixas  Cristiano Barros de Melo  Rômulo C. Leite  Élvio C. Moreira  Concepta M. McManus  Márcio B. de Castro 《Tropical animal health and production》2011,43(1):9-11

To define the prevalence of anti-Leptospira sp. agglutinins in ewes in the Federal District, Brazil, serum samples from 157 ewes were tested for antibodies against serovars of Leptospira sp. by the microscopic agglutination test. Antibodies were detected in three flocks in a prevalence of 3% (95% CI = 0.4%–5.7%). Considering that sheep and cattle were raised together, the lack of sanitary control could represent a risk to cattle production, which is the most important activity in the Centre-West region of Brazil.  相似文献   

Intermediate syndrome of chlorpyriphos toxicity (Polaris) in a caracal (Caracal caracal)     

Merbl Y  Aroch I  Klainbart S  Aizenberg Z  Kelmer E 《Journal of zoo and wildlife medicine》2011,42(1):144-148

A 5-yr-old spayed female caracal (Caracal caracal) was presented with complaints of acute onset of mental dullness, ataxia, and ventroflexion of 24-hr duration. The animal's garden territory was sprayed a day earlier with an organophosphate (OP) insecticide (chlorpyriphos-methyl). The caracal was treated for OP toxicosis and mildly improved. It was discharged a day later at the owner's request, although clinical signs did not resolve. During the following week, the caracal was confined to prevent further toxin exposure but did not improve and was presented 8 days later with similar clinical signs. Serum butyril-cholinesterase activity was markedly low. The relatively long interval from OP exposure, along with the duration of clinical signs, suggested an intermediate syndrome of OP toxicity. The caracal was treated symptomatically and progressively improved. It was discharged after 8 days of hospitalization and made full recovery 30 days later. This is the first report of OP toxicity in a caracal, suspected to progress to an intermediate syndrome of OP poisoning.  相似文献   

Yield and fruit quality of ‘Gala’ and ‘Fuji’ apple trees protected by white anti-hail net     

Cassandro Vidal Talamini do Amarante  Cristiano André Steffens  Luiz Carlos Argenta 《Scientia Horticulturae》2011

Covering apple orchards with nets protects them from hailstorms but this changes the amount and quality of the light supplied to the trees. This study was carried out to assess the effects of shade provided by white protection net on yield and fruit quality of apple orchards in Southern Brazil, along three growing seasons (2002/2003, 2003/2004, and 2004/2005). ‘Gala’ and ‘Fuji’ apple trees (on MM111 rootstock, raised as slender spindles, with a spacing of 5.5 m × 3 m) were left uncovered (control trees) or covered with white net. The white net reduced the photosynthetically active radiation (λ = 400–700 nm) accumulated over the trees’ canopy along a day by 18.4%, leading to a higher leaf chlorophyll content in both cultivars, and a higher specific leaf area in ‘Gala’. The shade provided by the net did not affect yield and increased fruit average weight in both cultivars. At harvest, the number of seeds per fruit and severity of russet were not affected by netting in both cultivars, as well as the incidence of watercore in ‘Fuji’. The main beneficial effects of the white net were the reduced incidence of sunburn on ‘Gala’, reduced incidence of bitter pit during cold storage in both cultivars, and reduced incidence of apple scab at harvest and of decay after cold storage in ‘Fuji’. Fruit fly damage in ‘Gala’ (assessed in one season) was reduced by netting. However, netting affected negatively some fruit quality attributes. ‘Gala’ and ‘Fuji’ apples from trees protected by the net had a poor skin color (pale blush and a more intense green background color) at harvest. The net reduced flesh firmness and SSC, and increased the starch index of ‘Gala’ apples at harvest, and reduced flesh firmness and SSC, assessed after cold storage and shelf life, in fruits of both cultivars.  相似文献   

Archaeal communities in the sediments of three contrasting mangroves     

Armando Cavalcante Franco Dias  Francisco Dini-Andreote  Rodrigo Gouvêa Taketani  Siu Mui Tsai  João Lúcio Azevedo  Itamar Soares de Melo  Fernando Dini Andreote 《Journal of Soils and Sediments》2011,11(8):1466-1476

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Early optical polarization of a gamma-ray burst afterglow     

Mundell CG  Steele IA  Smith RJ  Kobayashi S  Melandri A  Guidorzi C  Gomboc A  Mottram CJ  Clarke D  Monfardini A  Carter D  Bersier D 《Science (New York, N.Y.)》2007,315(5820):1822-1824

We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.  相似文献   

Transcriptional regulatory networks in Saccharomyces cerevisiae   总被引：2，自引：0，他引：2  

Lee TI  Rinaldi NJ  Robert F  Odom DT  Bar-Joseph Z  Gerber GK  Hannett NM  Harbison CT  Thompson CM  Simon I  Zeitlinger J  Jennings EG  Murray HL  Gordon DB  Ren B  Wyrick JJ  Tagne JB  Volkert TL  Fraenkel E  Gifford DK  Young RA 《Science (New York, N.Y.)》2002,298(5594):799-804

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Seismicity remotely triggered by the magnitude 7.3 landers, california, earthquake   总被引：7，自引：0，他引：7  

Hill DP  Reasenberg PA  Michael A  Arabaz WJ  Beroza G  Brumbaugh D  Brune JN  Castro R  Davis S  Depolo D  Ellsworth WL  Gomberg J  Harmsen S  House L  Jackson SM  Johnston MJ  Jones L  Keller R  Malone S  Munguia L  Nava S  Pechmann JC  Sanford A  Simpson RW  Smith RB  Stark M  Stickney M  Vidal A  Walter S  Wong V  Zollweg J 《Science (New York, N.Y.)》1993,260(5114):1617-1623

The magnitude 7.3 Landers earthquake of 28 June 1992 triggered a remarkably sudden and widespread increase in earthquake activity across much of the western United States. The triggered earthquakes, which occurred at distances up to 1250 kilometers (17 source dimensions) from the Landers mainshock, were confined to areas of persistent seismicity and strike-slip to normal faulting. Many of the triggered areas also are sites of geothermal and recent volcanic activity. Static stress changes calculated for elastic models of the earthquake appear to be too small to have caused the triggering. The most promising explanations involve nonlinear interactions between large dynamic strains accompanying seismic waves from the mainshock and crustal fluids (perhaps including crustal magma).  相似文献