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31.
Annual landings of chokka squid (Loligo reynaudii), an important fishing resource for South Africa, fluctuate greatly, and are believed to be related to recruitment success. The ‘Westward Transport Hypothesis’ (WTH) attributes recruitment strength to variability in transport of newly hatched paralarvae from spawning grounds to the ‘cold ridge’ nursery region some 100–200 km to the west, where oceanographic conditions sustain high productivity. We used an individual‐based model (IBM) coupled with a 3‐D hydrodynamic model (ROMS) to test the WTH and assessed four factors that might influence successful transport – Release Area, Month, Specific Gravity (body density) and Diel Vertical Migration (DVM) – in numerical experiments that estimated successful transport of squid paralarvae to the cold ridge. A multifactor ANOVA was used to identify the primary determinants of transport success in the various experimental simulations. Among these, release area was found to be the most important, implying that adult spawning behaviour (i.e., birth site fidelity) may be more important than paralarval behaviour in determining paralarval transport variability. However, specific gravity and DVM were found to play a role by retaining paralarvae on the shelf and optimizing early transport, respectively. Upwelling events seem to facilitate transport by moving paralarvae higher in the water column and thus exposing them to faster surface currents.  相似文献   
32.
Studies focusing on the equine humoral response are scarce, with a bias towards the pre- and post-parturition mare and its foal. The present study attempted to expand current knowledge by establishing normal ranges for adult horse serum isotypes. Immunoglobulin (Ig) concentrations were obtained by screening 47 horses of various breeds and in different training regimes. Radial immunodiffusion values (mg/dL) were 196 ± 73 for IgA, 2704 ± 1424 for IgG, 419 ± 220 for IgG(T) and 70 ± 30 for IgM. All values passed the Kolmogorov–Smirnov normality test. The results will be of use to the field veterinarian as well for the basic researcher working on horses.  相似文献   
33.
Two surveys (2005/2006 and 2009) were conducted in the state of São Paulo, Brazil, to investigate the incidence of ‘Candidatus Liberibacter asiaticus’ and ‘Ca. L. americanus’, two liberibacters associated with citrus huanglongbing (HLB) disease and both transmitted by Diaphorina citri, in orange jasmine (Murraya exotica), a widespread ornamental tree in cities and villages. The graft‐transmissibility of the two species, and their DNA relatedness to citrus‐associated liberibacters, were also investigated. Quantitative PCR was applied to PCR‐positive orange jasmine and HLB‐positive citrus growing in backyards and orchards to assess their inoculum source potentials. Liberibacters were detected in 91 of 786 sampled orange jasmine plants in 10 of 76 sampled locations. PCR‐positive trees exhibited yellow shoots and/or dieback symptoms indistinguishable from those on PCR‐negative trees. ‘Candidatus Liberibacter americanus’ was more common in 2005/2006 (96·6%) and ‘Ca. L. asiaticus’ in 2009 (84·8%). rplJ nucleotide sequences were identical within all populations of either species. Graft transmission succeeded only in homologous host combinations, including ‘Ca. L. americanus’ (2/10) from/to orange jasmine and ‘Ca. L. americanus’ (5/18) and ‘Ca. L. asiaticus’ (5/9) from/to citrus. Symptoms were mild and developed less rapidly in orange jasmine than in citrus, probably as a result of lower liberibacter multiplication rates. Respective titres of ‘Ca. L. americanus’ and ‘Ca. L. asiaticus’ in orange jasmine averaged 4·3 and 3·0 log cells g?1 tissue, compared with 5·5 and 7·3 in citrus. The results indicate that orange jasmine does not favour liberibacter multiplication as much as citrus. However, its importance in HLB epidemics should not be underestimated as it is a preferred host of D. citri and is not under any strict tree‐eradication programme or measures for insect control.  相似文献   
34.
The objective of this study was to evaluate neutrophil oxidative metabolism and haemogram in sheep experimentally infected with Haemonchus contortus and supplemented with selenium and vitamin E. Twenty male Corriedale sheep were utilised and distributed into four experimental groups each with five animals infected with larvae: G1‐ supplemented with sodium selenite, 0.2 mg/kg body weight (bw) given intramuscularly (IM); G2‐ supplemented with sodium selenite and vitamin E, 0.2 mg/kg bw and 2000 IU per animal, respectively, both IM; G3‐ supplemented with vitamin E, 2000 IU per animal IM; G4‐ not supplemented. A haemogram and the number of parasite eggs were determined in samples of blood and faeces, respectively, on days zero (T0), 20 (T1), 40 (T2) and 60 (T3) and nitroblue tetrazolium (NBT) assays were performed on heparinized blood samples taken on days zero, 30 and 60. A lower total leucocyte count was detected in G1 in relation to G4 at T4. Lymphocytes were reduced in G1 in relation to G3 and G4 at T3. In both non‐stimulated (NBT‐NS) and stimulated (NBT‐S) dye reduction assays, there was reduced activity at 60 days, in relation to other times in the groups treated with selenium (G1 and G2). On the basis of results obtained, we conclude that supplementation with selenium provides better antioxidant protection to neutrophils.  相似文献   
35.
The objective of this study was to evaluate oxidative stress in lambs experimentally infected with Haemonchus contortus and supplemented with selenium and vitamin E. Twenty male Corriedale lambs were divided into four experimental groups with five animals each: G1 consisted of animals infected and supplemented with 0.2 mg/kg of live weight (LW) sodium selenite by intramuscular injection (IM); G2 consisted of animals infected with larvae and supplemented with 0.2 mg/kg LW sodium selenite IM and 2000 IU per animal of Vitamin E IM; G3 consisted of animals infected with larvae and supplemented with 2000 IU per animal of Vitamin E IM; and G4 consisted of animals infected with larvae. The animals were infected orally with 500 H. contortus larvae (L3) every 48 hours for 20 days. For biochemical analyses and eggs per grams of feces (EPG) evaluation, blood and feces were both collected at zero (T0), 20 (T1), 40 (T2) and 60 (T3) days. The weight of the animals was also measured at these times. Lower TBARS values were observed in the supplemented animals compared to the control group. The groups supplemented with Selenium exhibited blood GSH-Px activity higher than that of non-supplemented animals. Supplementation with selenium provided greater antioxidant protection against oxidative stress generated from experimental infection of lambs with H. contortus.  相似文献   
36.
Ratoon stunting disease (RSD), caused by the bacterium Leifsonia xyli subsp. xyli (Lxx), is one of the most economically important diseases of sugarcane worldwide. Because knowledge on the interaction of Lxx with its host at the microscopic level is limited, the development of tools to monitor Lxx during the colonization process could shed new light on the processes that control disease development. In this investigation, a transformation protocol was optimized and a mutant Lxx strain engineered that stably expressed the gfp gene in sugarcane tissues. In vitro, the growth of the mutant did not differ from that of the wild type. Also, plants inoculated with both strains showed comparable growth and development when analysed 180 days after inoculation (dai). Fluorescence microscopy of roots, stalks, meristems and leaf tissues of Lxx‐GFP‐inoculated plants was performed at 180 dai. In the leaves, Lxx‐tagged cells were observed within the xylem vessels as has been described before but, in addition, they were found in a new niche within the host tissues, in the mesophyll and in the bundle sheath cells surrounding the vascular system. This finding indicates that Lxx is able to move from the xylem to the parenchyma of the leaf cells. This first report of an Lxx mutant expressing a heterologous gene revealed that colonization of sugarcane by this pathogen is not limited to the xylem vessels as commonly reported.  相似文献   
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Although the second largest chromosome of the genome, the X chromosome is usually excluded from genome-wide association studies (GWAS). Considering the presence and importance of genes on this chromosome that are involved in reproduction, the aim of this study was to evaluate the effect of its inclusion in GWAS on reproductive traits (scrotal circumference [SC], early pregnancy [P16] and age at first calving [AFC]) in a Nelore herd. Genotype data from 3,263 animals with the above-mentioned phenotypes were used. The results showed an increase in the variances explained by the autosomal markers for all traits when the X chromosome was not included. For SC, there was an increase of more than 10% for the windows on chromosomes 2 and 6. For P16, the effect was increased by almost 20% for windows on chromosome 5. The same pattern was found for AFC, with an increase of more than 10% for the most important windows. The results indicate that the noninclusion of the X chromosome can overestimate the effects of autosomes on SC, P16 and AFC not only because of the additive effect of the X chromosome itself but also because of its epistatic effect on autosomal genes.  相似文献   
40.
Horses at pasture are susceptible to the aspiration of foreign bodies. In Curitiba, southern Brazil, four horses of different breeds and ages were examined with regards to a persistent cough that lasted for several months, fetid breath, and no fever. The animals were referred for bronchoscopic examination performed under sedation and tracheobronchial topical anaesthesia. Bronchoscopies in all four horses revealed a pine branch of the species Araucaria angustifolia, native to southern Brazil, in the lumen of a third to fifth generation bronchus. Complete removal of the branch was possible in one case using a polypectomy loop inserted through the biopsy channel of the bronchoscope. In two cases, partial removal was possible. In one case the branch was adhered to the swollen mucosa and could not be extracted; this animal is being kept at pasture with intermittent antibiotic treatment as necessary. In conclusion, foreign bodies consisting of pine branches in the tracheobronchial tree of horses may be more common than currently recognised, as Araucaria genus is present in other countries and should be suspected in horses with chronic coughing associated with fetid breath and a history of reoccurrence following symptomatic treatments.  相似文献   
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