Physico-chemical factors determining the phloem translocation of benzoic acids

A series of ¹⁴C-labelled benzoic acids, chosen to permit assessment of the role of pK_a and lipophilicity in determining movement in plants of these herbicide analogues, was synthesised and their phloem translocation investigated. Following application of substituted benzoic acids to castor bean, Ricinus communis L., by injection into the petioles, the compounds of intermediate lipophilicity (2-fluoro-, 4-chloro- and 3,4-dichlorobenzoic acids) gave highest concentrations in phloem exudates; 4-methyl-2,3,5,6-tetrafluoro- and pentafluorobenzoic acids were less well translocated, perhaps because their pK_a values are much less than those of the other benzoic acids studied. The polar 4-ureidobenzoic acid and the lipophilic 3-(4-methylphenoxy)benzoic acid were much less efficiently translocated in phloem. These results are similar to those previously obtained for phenoxyacetic acids, and provide further support for the role of ionisation in the accumulation and retention of chemicals in phloem sieve tubes.     

Transmission disequilibrium test for quantitative trait loci detection in livestock populations

The performance of several transmission disequilibrium tests (TDT) for detection of quantitative trait loci (QTL) in data structures typical of outbred livestock populations were investigated. Factorial mating designs were simulated with 10 sires mated to either 50 or 200 dams, each family having five or eight full sibs. A single marker and QTL, both bi‐allelic, were simulated using a disequilibrium coefficient based on complete initial disequilibrium and 50 generations of recombination [i.e. D = D₀(1 ? θ)⁵⁰], where θ is the recombination fraction between marker and QTL. The QTL explained either 10% (small QTL) or 30% (large QTL) of the genetic variance for a trait with heritability of 0.3. Methods were: TDT for QTL (Q‐TDT; both parents known), 1‐TDT (only one parent known) and sibling‐based TDT (S‐TDT; neither parent known, but sibs available). All were found to be effective tests for association and linkage between the QTL and a tightly linked marker (θ < 0.02) in these designs. For a large QTL, θ = 0.01, and five full sibs per family, the empirical power for Q‐TDT, 1‐TDT and S‐TDT was 0.966, 0.602 and 0.974, respectively, in a large population, versus 0.700, 0.414 and 0.654, respectively, in a small population. For a small QTL effect, θ = 0.01, large population the empirical power of these tests were 0.709, 0.287 and 0.634. The power of Q‐TDT, 1‐TDT and S‐TDT was satisfactory for large populations, for QTL with large effects and for five full sibs per family. The 1‐TDT based on a linear model was more powerful than the normal 1‐TDT. The empirical power for Q‐TDT and 1‐TDT with a linear model was 0.978 and 0.995 respectively. TDT based on analogous linear models, incorporating the polygenic covariance structure, provided only small increases in power compared with the usual TDT for QTL.     

SEROLOGICAL TITRES OF DAIRY COWS OVER A 63-WEEK PERIOD FOLLOWING NATURAL INFECTION WITH LEPTOSPIRA INTERROGANS SEROVAR HARDJO

SUMMARY Leptospirosis due to Leptospira interrogans serovar hardjo, occurred in a dairy herd of 104 cows and produced signs of mastitis, characterised by a sudden decrease in milk production and uniformly flaccid udders, in 11 cows. The microscopic agglutination (MA) test was used to determine antibody titres to serovar hardjo in all cows in the herd at 6, 33 and 63 weeks after the initial outbreak. The prevalence of MA antibodies to hardjo at week 6 was highest in cows in the youngest age groups and lowest in cows in the oldest age group. Over the 63-week period MA antibody titres to hardjo declined in 54 out of 62 seropositive cows, remained unchanged in 6 cows, and increased slightly in 2 cows. Fourteen of 59 cows (23.7%) with MA titres greater than 100 at week 6 had titres greater than 100 by week 63. Included in this group of 14 were 5 of 7 cows that had been affected with atypical mastitis. The distribution of serological titres to hardjo showed bimodal configurations at weeks 6 and 33 with the second peaks occurring at titres greater than 100, while the configuration was linear at week 63. MA titres to hardjo were also determined for 22 heifers 1, 16 and 36 weeks after they were added to the herd. No clinical signs of leptospirosis were observed in the heifers; however, the distribution of MA titres showed bimodal configurations at weeks 16 and 33 with second peaks occurring at titres greater than 100. Leptospiras were isolated from the urine of 2 seropositive heifers 16 weeks after their introduction to the herd, and cross-agglutinin absorption tests performed on one of the isolates indicated that it was identical to serovar hardjo.     

Follicle stimulating hormone, luteinising hormone and progesterone concentrations in the blood of thoroughbred mares exhibiting single and twin ovulations

The concentrations of follicle stimulating hormone, luteinising hormone and progesterone were measured in serial blood samples taken throughout one or more oestrous cycles from 12 Thoroughbred mares, some of which exhibited single and others twin ovulations. The resulting profiles clearly demonstrated that no simple relationship exists between circulating gonadotrophin levels and subsequent ovulation rate in the mare. However, plasma progesterone concentrations during dioestrus are, as expected, higher following twin than single ovulations. The findings suggest that the underlying cause of twin ovulation in some mares may exist at the ovarian end of the pituitary-ovarian axis which controls follicular development and ovulation.     

Patent Ductus Arteriosus in a Cat

Patent ductus arteriosus is the most common shunting congenital cardiac anomaly in the cat. If it is treated surgically, early in the course of the disease, the prognosis is good.     

Diagnostic characterization of a feral swine herd enzootically infected with Brucella.

Eighty feral swine were trapped from a herd that had been documented to be seropositive for Brucella and which had been used for Brucella abortus RB51 vaccine trials on a 7,100-hectare tract of land in South Carolina. The animals were euthanized and complete necropsies were performed. Samples were taken for histopathology, Brucella culture, and Brucella serology. Brucella was cultured from 62 (77.5%) animals. Brucella suis was isolated from 55 animals (68.8%), and all isolates were biovar 1. Brucella abortus was isolated from 28 animals (35.0%), and isolates included field strain biovar 1 (21 animals; 26.3%), vaccine strain Brucella abortus S19 (8 animals, 10.0%), and vaccine strain Brucella abortus RB51 (6 animals, 7.5%). Males were significantly more likely to be culture positive than females (92.9% vs. 60.6%). Thirty-nine animals (48.8%) were seropositive. Males also had a significantly higher seropositivity rate than females (61.9% vs. 34.2%). The relative sensitivity rates were significantly higher for the standard tube test (44.6%) and fluorescence polarization assay (42.6%) than the card agglutination test (13.1%). Lesions consistent with Brucella infection were commonly found in the animals surveyed and included inflammatory lesions of the lymph nodes, liver, kidney, and male reproductive organs, which ranged from lymphoplasmacytic to pyogranulomatous with necrosis. This is the first report of an apparent enzootic Brucella abortus infection in a feral swine herd suggesting that feral swine may serve as a reservoir of infection for Brucella abortus as well as Brucella suis for domestic livestock.