Characterization of hemiacetal forms of anthocyanidin 3-O-beta-glycopyranosides

The 3-O-beta-glucopyranosides of delphinidin, petunidin, and malvidin (1-3) and cyanidin 3-O-beta-galactopyranoside (4) dissolved in deuterated methanolic solutions without and with acid (5%, CF3COOD) were identified by homo- and heteronuclear NMR techniques. The hemiacetal forms of all the four anthocyanins were characterized as two epimeric 2-hydroxy-hemiacetals on the basis of assignments of both proton and carbon NMR signals together with chemical shift considerations. This is the first report of 13C NMR assignments of two epimeric anthocyanin hemiacetal forms. No 4-hydroxy-hemiacetal form was detected for any of the pigments. For each anthocyanin dissolved in deuterated methanol, the equilibrium between each of the two epimeric hemiacetals and the corresponding flavylium cation was confirmed by the observed positive exchange cross-peaks in the 2D 1H NOESY spectra. The molar proportions of the flavylium cation and the two hemiacetals of 1-4 in deuterated methanol were very similar for all pigments, even during storage for weeks. The majority of the anthocyanins reported to occur in fruits have the same or similar structures as 1-4. These pigments have been proposed to exist predominantly as hemiacetals in slightly acidic to neutral solvents, which is a relevant pH range in plants and in the human gastrointestinal tract.     

Genomewide association study reveals novel quantitative trait loci associated with resistance towards Septoria tritici blotch in North European winter wheat

Fungal diseases are a major constraint for wheat production. Effective disease resistance is essential for ensuring a high production quality and yield. One of the most severe fungal diseases of wheat is Septoria tritici blotch (STB), which influences wheat production across the world. In this study, genomewide association mapping was used to identify new chromosomal regions on the wheat genome conferring effective resistance towards STB. A winter wheat population of 164 North European varieties and breeding lines was genotyped with 15K single nucleotide polymorphism (SNP) wheat array. The varieties were evaluated for STB in field trials at three locations in Denmark and across 3 years. The association analysis revealed four quantitative trait loci, on chromosomes 1B, 2A, 5D and 7A, highly associated with STB resistance. By comparing varieties containing several quantitative trait loci (QTL) with varieties containing none of the found QTL, a significant difference was found in the mean disease score. This indicates that an effective resistance can be obtained by pyramiding several QTL.     

Changes in phosphorus fractions in three tropical soils amended with corn cob and rice husk biochars

ABSTRACT

The formation of phosphorus (P) compounds including iron-P, aluminum-P and calcium-P in highly weathered tropical soils can be altered upon biochar addition. We investigated the effect of corn cob biochar (CC) and rice husk biochar (RH) pyrolyzed at three temperatures (300°C, 450°C and 650°C) on phosphorus (P) fractions of three contrasting soils. A 90d incubation study was conducted by mixing biochar with soil at a rate of 1% w/w and at 70% field capacity. Sequential P fraction was performed on biochar, soil and soil-biochar mixtures. Increase in most labile P (resin-P_i, NaHCO₃-P_i) and organic P fraction (NaHCO₃-P_o + NaOH-P_o) in CC and RH biochars were inversely related to increasing temperature. HCl-P_i and residual P increased with increasing temperature. Interaction of CC and RH with soils resulted in an increase in most labile P as well as moderately labile P (NaOH-P_i) fractions in the soils. CC increased most labile P in the soils more than RH. The increase in most labile P fraction in soils was more significant at relatively lower temperatures (300°C and 450°C) than 650°C. However, the increase in HCl-P_i and residual P of the soils was more predominant at high temperature (650°C). The study suggested that biochar pyrolyzed at 300–450°C could be used to increase P bioavailability in tropical soils.     

Inhibition of juvenile hormone biosynthesis and methyl farnesoate epoxidase activity by 1,5-disubstituted imidazoles in the cockroach,Diploptera punctata

Seventeen substituted imidazoles were tested as inhibitors of juvenile hormone (JH) III synthesis by cockroach corpora allata in an in-vitro radio-chemical assay. Most of these 1,5-disubstituted imidazoles were highly potent, with IC₅₀ values of less than 100nM. The compounds differed in their ability to cause an accumulation of the precursor methyl farnesoate in the glands. Four of the imidazoles were tested by topical application to previtellogenic adult females, and all caused a significant inhibition of JH synthesis and an accumulation of intraglandular methyl farnesoate for at least three days after treatment. Methyl farnesoate epoxidase activity of homogenates of corpora allata was inhibited by the compounds TH -14 and TH -27. This P450-dependent epoxidase activity was inhibited at less than 10 nM. The results show that the 1,5-disubstituted imidazoles are powerful inhibitors of the last step of juvenile synthesis in this cockroach.     

In situ hybridization for the detection and localization of swine Chlamydia trachomatis

Gnotobiotic piglets were inoculated intralaryngeally with swine Chlamydia trachomatis strain R33 or orally with swine C. trachmatis strain R27. Archived formalin-fixed, paraffin-embedded tissues from piglets euthanatized 4-7 days postinoculation were examined by in situ hybridization for C. trachomatis nucleic acid using a nonradioactive digoxigenin-labeled DNA probes that targeted specific ribosomal RNA or omp1 mRNA molecules of the swine C. trachomatis strains. Positive hybridization signals were detected in bronchial epithelial cells, bronchiolar epithelial cells, pneumocytes, alveolar and interstitial macrophages, and jejunal and ileal enterocytes. Chlamydia-infected cells had a strong signal that was confined to the intracytoplasmic inclusions. Positive hybridization signals were not detected in tissue sections from an uninfected control piglet or in C. psittaci-infected sheep placenta. The morphology of host cells was preserved despite the relatively high temperature required in parts of the incubation procedure. The data indicate that in situ hybridization can be used to detect swine C. trachomatis in formalin-fixed, paraffin-embedded tissue specimens.     

Dietary calcium-phosphorus ratios for growing pigs in relation to serum levels and bone development

Two experiments comprising a total of 80 Danish Landrace pigs in the period 20–90 kg live-weight were carried out to study the effect of dietary levels and ratios of Ca and P on serum values of Ca, inorg. P, and alkaline phosphatase and on the development of degenerative arthritis and atrophic rhinitis.In both experiments each kg feed (Table 1) was supplemented with 600 i. u. vitamin D₃ and 80 p. p. m. Zn.In the first experiment the Ca:P ratio was 1.2 and the amount of Ca increased from 0.48 % to 1.20 % without influencing daily gain, feed conversion, carcass performance (Table 2) or frequency of atrophic rhinitis (Table 3). The Ca:P ratio in scapula was 2.15. Only when the diet was supplemented with 1.20 % Ga and 1.00 % P the bone quality was histomorphologically adequate (Figs. 1–4).In the second experiment various Ca:P ratios (ranging from 0.1 to 3.0) were compared with the recommended level and ratio of 0.72 % Ga and 0.60 % P. Performance of pigs on the normal level was better than for the other pigs (Table 4). Clinically, various degrees of leg-weakness and -deformation occurred, most pronounced in the high Ca — low P group. Very little lameness and no convulsions were observed. Marked hypocalcemia was not found. Unilateral high Ca intake increased serum Ca significantly, and serum alkaline phosphatase slightly, and decreased serum P (Figs. 5–7). Advanced pericytic osteolysis, poor mineralization and generalized osteodystrophia fibrosa were found in the low Ca groups (Figs. 8–13). The groups showed no differences in frequency of atrophic rhinitis (Table 5), and rickets was not observed.The incidence of degenerative joint lesions was not increased in pigs on the unfavourable Ca:P ratios, and depended apparently more on litters than on diets.     

Risk factors associated with faecal shedding of verocytotoxin-producing Escherichia coli O157 in eight known-infected Danish dairy herds

A risk-factor study was performed in eight dairy herds found to excrete verocytotoxin-producing Escherichia coli (VTEC) O157 in a former prevalence study. Associations between excretion of VTEC O157 and management factors such as housing and feeding were analysed in a generalised linear mixed model. The animals were stratified in three age groups and sampled four times during 1 year. The risk of excreting VTEC O157 was higher among weaned calves than non-weaned calves. Among the calves aged 1–4 months, the risk was reduced if the calf had suckled colostrum from the mother or if the calf had stayed >2 days with the mother after calving. Calves aged 5–24 months that had been moved within the last 2 weeks had a higher risk, but risk was reduced if fed barley silage. Cows fed grain or molasses had a higher risk of excreting VTEC O157.     

The need for built-in validation of surveillance data so that changes in diagnostic performance of post-mortem meat inspection can be detected

Time trends in animal-disease surveillance often are evaluated on the basis of crude estimates of apparent prevalence. In addition to possible changes in the true prevalence of the condition, changes in apparent prevalence over time might reflect changes in sensitivity and/or specificity of the diagnostic classification used. To illustrate this, comparative post-mortem meat inspection data from four Danish slaughter plants sampled in 1993-1994 and 1997-1998 were used to obtain latent-class model estimates of the sensitivity and specificity of traditional and extended post-mortem meat inspection of visceral and parietal chronic pleuritis (CP), respectively.True prevalence of CP was estimated for each study period and slaughter plant by latent-class models. Estimated sensitivities of traditional post-mortem meat (TPM) inspection ranged from 28.8 to 61.4% (1993-1994) and 39.2 to 87.3% (1997-1998). An increase in sensitivity with time was seen for all slaughter plants. Estimated sensitivities of extended post-mortem meat (EPM) inspection ranged from 85.7 to 94.8% (1993-1994) and 73.8 to 93.0% (1997-1998). All estimated specificities were >93.3%.The possible association of the estimated true prevalence of CP with time (1993-1994 versus 1997-1998) was investigated with a logistic-regression model with random effects. A slight, but non-significant decrease in the odds of CP from 1994 to 1998 was found (odds ratio=0.9).In this and similar situations, one should consider conducting ongoing double-classification of samples of units followed by statistical estimation of true prevalences, sensitivities and specificities, so that decisions can be based on such estimates rather than on crude apparent prevalences.     

Comparisons of sampling procedures and time of sampling for the detection of Salmonella in Danish infected chicken flocks raised in floor systems

Bacteriological follow-up samples were taken from 41 chicken (Gallus gallus) flocks in floor systems, where Salmonella enterica (Salmonella) had been detected either directly in bacteriological samples or indirectly by serological samples. Three types of follow-up samples were compared to each other within each flock: 1) 5 pairs of socks, analysed as 5 samples, 2) 2 pairs of socks, analysed as one sample, and 3) 60 faecal samples, analysed as one pooled sample. Agreement between sampling methods was evaluated by the following statistical tests: 'Kappa', 'The adjusted rand', McNemar's test for marginal symmetry, Proportion of agreement P0, P+, P-, and Odds Ratio. The highest agreement was found between the 2 types of sock sampling, while the lowest agreement was found by comparing 60 faecal samples with 5 pairs of socks. Two pairs of socks analysed as one pool appeared to be just as effective in detecting S. enterica as the 60 faecal samples. In broiler flocks, 5 pairs of socks were used both in the routine samples taken at about 3 weeks of age for the establishment of infection of the flock, and as one of the follow-up samples taken shortly before slaughter age, which means that the only notable differences between the 2 sampling rounds were the age of the broilers and of their litter. S. enterica was detected more frequently in samples from broilers about 3 weeks old, than in similar samples taken from broilers a few days prior to slaughter at ca. 33-40 days of age.