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1.
The name Tomato yellow leaf curl virus (TYLCV) has been applied to a group of virus species of the genus Begomovirus in the family Geminiviridae that cause a similar tomato disease worldwide. In 1995, TYLCV was first reported in Algarve (southern Portugal) as responsible for an epidemic outbreak of a severe tomato disease. Molecular data have shown that this Portuguese TYLCV isolate was distinct from those previously reported in Europe, as it belonged to the TYLCV-Israel species 1 . Since then, TYLCV epidemics have occurred annually, being a limiting factor mainly for autumn/winter glasshouse tomato crops. In 1998, TYLCV was also found associated with the emergence of a novel disease of Phaseolus vulgaris in Algarve. The affected bean plants were severely stunted and gave no marketable yield. However, the disease occurs only sporadically, even in conditions of high TYLCV infection pressure. Recently, Tomato chlorosis virus (ToCV), a whitefly-transmitted bipartite closterovirus (genus Crinivirus , family Closteroviridae ), was found associated with an unusual tomato yellow leaf syndrome, in single or mixed infection with TYLCV. The impact of this new pathosystem on tomato production has yet to be determined. Surveys are in progress in mixed cropping systems infested with whiteflies. So far, TYLCV and ToCV diseases are limited to the Algarve region.  相似文献   
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The gill structure of the Amazonian fish Arapaima gigas (Cuvier 1829) shows ontogenetic changes during development, particularly due the transition from the aquatic to the obligatory air breathing mode of respiration. However, three main cell types can be found in the gills: mitochondrial rich cells, pavement cells and mucous cells (MCs). The MCs are involved in the secretory pathway. The functions of the secreted molecules include mechanical protection of epithelia, protection against parasites and bacterial infection, and role on ion regulation. In this study, we analysed mucous cell location and mucous cell type, based on pH, during the development of A. gigas. Using samples obtained from the environment, gills were collected and fixed in buffered solution. Histological techniques for the identification of MCs were performed Alcian Blue (AB) and periodic acid‐Schiff (PAS). The results showed the presence of PAS+ and AB+ cells in the whole filament in all examined fish. In animals less than 50 g, few MCs were present, and no differences were observed in AB+ and PAS+ cells. In animals weighing close to 500 g, more PAS+ cells than AB+ cells were observed, and in animals that weighed more than 1,000 g, more AB+ cells than PAS+ cells were observed. These observations may be a result of the ontogenetic changes in the gill epithelia, which can change the osmorespiratory compromise in ion regulation functions as well the glycosaminoglycans secreted by PAS cells, which in large animals can play a role in the protection against parasites and bacterial infection.  相似文献   
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Tropical Animal Health and Production - Serological studies have characterized the presence of the bovine viral diarrhea virus (BVDV) infection in water buffalo herds worldwide. However, the...  相似文献   
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To assess the effect of the angiotensin‐converting enzyme (ACE) inhibition on the efficiency of the fixed‐time artificial insemination (TAI), 69 goats were divided randomly into two groups: enalapril (n = 35) and control (n = 34). In the experiment, all animals underwent the protocol of fixed‐time artificial insemination for 12 days. Enalapril group received enalapril maleate dissolved in saline (Enalapril, Lab Teuto Ltda) subcutaneously at the following doses: 0.2 mg/kg/day in D0‐D2; 0.3 mg/kg/day in D3‐D6 and 0.4 mg/kg/day in D7‐D11. The control group received the corresponding volume of 0.9% saline solution. We performed a single insemination 36 hr after sponge removal using frozen semen from two adult male goats with recognized fertility. The ultrasound pregnancy diagnosis was 30 days after the artificial insemination (AI). There was significant increase in pregnancy rates and twinning as well as a decrease in foetal loss in animals receiving enalapril (p < .01). The use of ACE inhibitors during the TAI protocol was shown to be a promising alternative to increase the efficiency of such reproductive biotechnology.  相似文献   
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ABSTRACT Using molecular markers, this work compares the genetic diversity in Colletotrichum gloeosporioides infecting species of the tropical forage legume Stylosanthes at the center of origin in Brazil and Colombia with that of Australia, China, and India, where Stylosanthes spp. have been introduced for commercial use. There was extensive diversity in the pathogen population from Brazil, Colombia, China, and India. The Australian pathogen population was least diverse probably due to its geographical isolation and effective quarantine. The extensive diversity in China and India means that threats from exotic pathogen races to Stylosanthes pastures can potentially come from countries outside the South American center of origin. In Brazil and India, both with native Stylosanthes populations, a high level of genetic differentiation in the pathogen population was associated with sites where native or naturalized host population was widely distributed. There was limited genetic diversity at germplasm evaluation sites, with a large proportion of isolates having identical haplotypes. This contrasts recent pathogenicity results for 78 of the Brazilian isolates that show hot spots of complex races are more common around research stations where host germplasm are tested, but few are found at sites containing wild host populations. For a pathogen in which the same races arise convergently from different genetic backgrounds, this study highlights the importance of using both virulence and selectively neutral markers to understand pathogen population structure.  相似文献   
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In this study, we compare the development of infection and/or disease in Beagle dogs intradermally infected with Leishmania chagasi, in the presence or absence of Lutzomyia longipalpis saliva, with those of intravenously infected animals.Spleen samples of all the animals inoculated with parasites had positive polymerase chain reaction tests for Leishmania DNA. Positive spleen cultures for Leishmania were detected earlier (P < or = 0.018) and were more frequent (five out of the five animals) in intravenously infected animals than in the intradermally infected animals, in presence (two out of the six animals) or absence (three out of the five animals) of salivary gland lysate of L. longipalpis. Significant increase in serum antibodies against Leishmania was observed only in the intravenously infected group (P = 0.004). In addition, dogs with infection confirmed by isolation of amastigotes or detection of parasite DNA were, nevertheless, negative for anti-Leishmania antibodies up to 5 months or more after infection. Only animals of the intravenously infected group developed progressive decreases in hematocrit (Pearson r = -0.8076, P = -0.0026) and hemoglobin (Pearson r = -0.8403, P = 0.0012) during the infection period. No significant difference in the course of infection was observed between groups of intradermally infected animals. The data presented herein confirms that the intradermal inoculation of dogs with Leishmania produces an asymptomatic form of infection. It also fails to show an advantage in using L. longipalpis saliva as an infection-enhancing agent in experimental canine leishmaniasis.  相似文献   
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Effect of floor cooling on performance of lactating sows during summer   总被引:2,自引:0,他引:2  
Forty Landrace × Large White lactating sows were used to evaluate the effects of cooling of the floor when maintained under high temperature conditions during summer on their productive and reproductive performance. The sows were allocated in a completely randomized design with two treatments with 20 replicates according to parity number and body weight, with each animal being considered an experimental unit. The treatments consisted of cooling of the floor under the sow with water circulation at about 17 °C and no cooling. The resulting temperatures of the floor were 27.6 and 35.8 °C for the cooled and the control treatments, respectively. The sows from both treatments were exposed to average maximum and minimum environmental temperatures of 26.9 and 20.8 °C, respectively. Sows maintained on a cooled floor had a higher feed intake (6.47 vs. 5.61 kg/day; P < 0.01). Despite this higher intake, sows maintained on a cooled floor had higher body weight and body protein losses during the lactation period (P < 0.01) in connection with a higher milk yield and subsequent growth of the litter (2280 vs. 1798 g/day; P < 0.01). There was an effect of treatment on rectal temperature, surface temperatures and respiratory rate (P < 0.01) with lower values in sows submitted to floor cooling. It is concluded that floor cooling under the lactating sow improves its productive and reproductive performance, as well as the performance of its litter.  相似文献   
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