Phenoloxidase activity of hemocyanin in whiteleg shrimp Penaeus vannamei: conversion, characterization of catalytic properties, and role in postmortem melanosis

Latent phenoloxidase activity of hemocyanin (Hc) in whiteleg shrimp Penaeus vannamei was assayed to determine its potential involvement in postmortem melanosis. Conversion of pure 12-mer, but not 6-mer, hemocyanin to phenoloxidase by endogenous (serine proteinases) and exogenous (SDS) effectors demonstrated the need of complex aggregation for displaying enzyme activity. Because Hc was converted to Hc-phenoloxidase (HcPO) by hemocytes extracts, the mechanism of conversion seems to be the same for polyphenoloxidases. HcPO has similar biochemical and kinetic properties as real polyphenoloxidases and uses mono- and diphenols as substrates. The kinetics of hydroxygenation of monophenols has a lag phase, typical for tyrosinases, contrary to oxidation of diphenols. Regardless of the structure of the substrate, melanin is finally formed. Because of the abundance, distribution, and resistance of Hc to freezing-thawing, involvement of Hc in black spot formation postmortem is suggested. This has important implications for commercialization of shrimp and related seafood.     

Online RPLC-GC via TOTAD method to isolate (+)-methyl epijasmonate from lemon (Citrus limon Burm.)

Pure (+)-methyl epijasmonate was isolated from lemon ( Citrus limon Burm.) for the first time. To that aim, two commercial essential oils and one homemade extract were included in the present paper. First, a study on the appropriate chromatographic conditions to avoid the epimerization from methyl epijasmonate to the more stable methyl jasmonate was accomplished. The results obtained are discussed. The presence of (+)-methyl epijasmonate in the three samples studied was initially established through the direct injection into GC-MS. However, the overlapping of (+)-methyl epijasmonate with other matrix components made it necessary to employ a multidimensional technique. RPLC-GC analysis via through-oven transfer adsorption-desorption (TOTAD) provided the selectivity and sensitivity required, reflecting that the homemade lemon extract was an adequate natural source to obtain pure (+)-methyl epijasmonate by means of the collection of the corresponding RPLC fraction.     

Triploid Induction in the Yellowtail Tetra,Astyanax altiparanae,Using Temperature Shock: Tools for Conservation and Aquaculture

Triploidization is an interesting tool to produce sterile fish. In the yellowtail tetra, Astyanax altiparanae, this can be applied for aquaculture and surrogate technologies. In this study, we compared the efficacy of cold (2 C) or heat shock (38 C, 40 C, and 42 C) on triploid induction in the yellowtail tetra. The eggs were treated with cold or heat shock, 2 min postfertilization (30 min in cold shock or 2 min in heat shock). Intact embryos served as the control group. Ploidy status was confirmed by karyotyping, flow cytometry, and nuclear diameter of erythrocytes. The hatching rate decreased after cold shock (12.69 ± 15.76%) and heat shock at 42 C (0.35 ± 0.69%) in comparison with the control group (63.19 ± 16.82%). At 38 C and 40 C, hatching rates (61.29 ± 17.73% and 61.75 ± 22.1%, respectively) were not decreased. Only one triploid arose at 38 C (1/80). At 40 C, a high number of triploids arose (72/78). At 42 C, very few embryos developed into the hatching stage. A large number of haploid individuals arose after cold shock (61/75), with only one triploid. Our results indicate that heat shocking of embryos at 40 C is optimum for triploid production in the yellowtail tetra.     

Cryptosporidium infection in calves from a rural area of Buenos Aires, Argentina

Dairy calves less than 1 month of age are commonly infected with Cryptosporidium spp. The objective of the present study was to evaluate the prevalence of Cryptosporidium spp. among dairy calves or=810 oocysts/field. This study shows that Cryptosporidium spp. is one of the causes of calf neonatal diarrhoea in a rural area of Buenos Aires, Argentina. The highest intensity of infection reported for the 相似文献   

Characterization of Mycobacterium avium subspecies paratuberculosis disseminated infection in dairy cattle and its association with antemortem test results

Mycobacterium avium subspecies paratuberculosis (MAP) disseminated infection in dairy cattle affects animal health and productivity and is also a potential public health concern. The study objectives were to characterize MAP disseminated infection in dairy cattle and to determine the role of antemortem tests in detecting cattle with disseminated infection. Forty culled dairy cows representing a variety of serum enzyme-linked immunosorbent assay (ELISA) results and body conditions were selected for the study. The physical condition of the cows was assessed via clinical examination prior to euthanasia and blood and feces were collected and tested by serum ELISA and fecal culture, respectively. Fifteen tissues were aseptically collected from each cow during necropsy and cultured for isolation of MAP. Disseminated infection was diagnosed when MAP was isolated in tissues other than the intestines or their associated lymph nodes (LNs) and was distinguished from infection found only in the gastrointestinal tissues and from absence of infection. Of the 40 cows in the study, 21 had MAP disseminated infection. Results showed that 57% (12/21) of cows with disseminated infection had average to heavy body condition and no diarrhea. Cows with disseminated infection had no to minimal gross pathologic evidence of infection in 37% (8/21) of cases. Only 76% (16/21) of cows with disseminated infection had positive historical ELISA results and only 62% (13/21) had a positive ELISA at slaughter. Thus, antemortem evidence of MAP infection was lacking in a high proportion of cows where MAP disseminated infection was confirmed.     

High Mycobacterium bovis genetic diversity in a low prevalence setting

The genetic diversity among South African Mycobacterium bovis isolates from cattle was determined by genetic fingerprinting. The restriction fragment length polymorphism (RFLP) markers IS6110 and polymorphic GC-rich sequence (PGRS) as well as spoligotyping and determination of variable number of tandem repeats (VNTR) were used to characterize sub samples of 91 M. bovis field isolates. PGRS RFLP was the single most discriminatory method and combinations of typing methods, which included IS6110 and/or PGRS had the highest discriminatory power, able to reveal 29 distinct genotypes among 35 farms with no epidemiological link. Three of the farms were co-infected with two genetically unrelated strains. In contrast to reports from European and also other colonised countries on the African continent our findings are suggestive of a high genetic diversity of M. bovis in South Africa's cattle population, implying a variety of unrelated ancestor strains. Despite effective intervention through test-and-slaughter campaigns no indication of a 'founder effect' was apparent in the panel of isolates derived from all infected provinces.     

Thromboelastographic tracings in retired racing greyhounds and in non-greyhound dogs

BACKGROUND: Bleeding disorders in patients with normal coagulation test results are frequently reported in Greyhounds. The purpose of this study was to compare Greyhounds to non-Greyhounds by thromboelastography (TEG). HYPOTHESIS: TEG parameters in Greyhounds are different from those in non-Greyhounds. ANIMALS: Forty-three healthy dogs (28 Greyhounds and 15 non-Greyhounds) based on the results of physical examination, CBC, activated partial thromboplastin time, prothrombin time, fibrinogen, and platelet count. MATERIALS AND METHODS: Recalcified citrated native TEGs were performed in both groups; data were compared using Student's, Mann-Whitney, and Pearson's statistical tests. RESULTS: In Greyhounds, mean +/- SD were as follows: R-time 4.3 +/- 1.7 minutes, K-time 3.8 +/- 1.4 minutes, angle (alpha) 50.0 +/- 8.0 degrees , maximum amplitude (MA) 47.6 +/- 5.6 mm, clot strength (G) 4,647 +/- 1,097 dyn/cm2, and percent lysis at 60 minutes (LY60) 2.8 +/- 5.0%. In the non-Greyhounds they were R-time 3.7 +/- 1.6 minutes, K-time 2.5 +/- 0.9 minutes, angle 59.8 +/- 7.0 degrees , MA 53.1 +/- 5.6 mm, G 5,811 +/- 1,256 dyn/cm2, and LY60 3.1 +/- 2.5%. All parameters were significantly different between the groups, except for R-time and LY60. CONCLUSION: In Greyhounds, clotting kinetics are slower and clot strength are weaker than in non-Greyhounds, supporting the increased tendency to bleed observed after minor trauma or surgical procedures in the breed. The findings may also be attributed to blood viscosity or to the concentration of citrate in the sample (ie, Greyhounds have higher hematocrit and less plasma per unit volume).     

Pharmacokinetic-pharmacodynamic integration of orbifloxacin in rabbits after intravenous, subcutaneous and intramuscular administration

The single-dose disposition kinetics of orbifloxacin were determined in clinically normal rabbits (n=6) after intravenous (i.v.), subcutaneous (s.c.) and intramuscular (i.m.) administration of 5 mg/kg bodyweight. Orbifloxacin concentrations were determined by high performance liquid chromatography with fluorescence detection. Minimal inhibitory concentrations (MICs) assay of orbifloxacin against 30 strains of Staphylococcus aureus from several European countries was performed in order to compute pharmacodynamic surrogate markers. The concentration-time data were analysed by compartmental and noncompartmental kinetic methods. Steady-state volume of distribution (V(ss)) and total body clearance (Cl) of orbifloxacin after i.v. administration were estimated to be 1.71+/-0.38 L/kg and 0.91+/-0.20 L/h x kg, respectively. Following s.c. and i.m. administration orbifloxacin achieved maximum plasma concentrations of 2.95+/-0.82 and 3.24+/-1.33 mg/L at 0.67+/-0.20 and 0.65+/-0.12 h, respectively. The absolute bio-availabilities after s.c. and i.m. routes were 110.67+/-11.02% and 109.87+/-8.36%, respectively. Orbifloxacin showed a favourable pharmacokinetic profile in rabbits. However, on account of the low AUC/MIC and C(max)/MIC indices obtained, its use by i.m. and s.c. routes against the S. aureus strains assayed in this study cannot be recommended given the risk of selection of resistant populations.     

Pseudorabies virus infection in mink: a host-specific pathogenesis

Pseudorabies virus (PRV) is an alphaherpesvirus that causes a neurological disease in many wild and domestic animals. The neuropathology elicited by PRV is quite consistent regardless of the host with the only exception of mink, in which it is characterized by a vasculopathy rather than by an encephalitis. In this study, we aimed to investigate the underlying pathogenic mechanism(s) of PRV infection in mink by using immunohistochemistry and laser capture microdissection (LCM) on material from naturally and experimentally infected animals. The inflammatory reaction induced by PRV was minimal or absent not only in the nervous system, where we identified a low number of macrophages and a few T lymphocytes, but also in the primary replication site, the oropharyngeal mucosa; however, the number of PRV-infected cells detected by immunohistochemistry was extremely high both in the peripheral mucosa and in the nervous tissue. On the other hand, the vascular pathology included parenchymal hemorrhages of various degrees and, in specific cortical areas of the brain, fibrinoid degeneration of the capillary walls. Detection of viral antigens by immunohistochemistry revealed infection of endothelial cells of capillaries situated both in the oropharyngeal mucosa and in the brain stem; the presence of PRV DNA in vessels was further demonstrated by PCR performed on LCM samples of brain capillaries. These results can be interpreted as supporting the idea that the different pathology of the disease in mink may be the consequence of an increased endotheliotropism of PRV in this species. Infection of the vessel wall may then lead to vascular pathology and impairment in endothelial cell function, resulting in a weak immune response to infection.