Antioxidant capacity and rate of decomposition of organic amendments in a Vertisol

We hypothesized that antioxidants in organic amendments would control the rate of their decomposition in soil, such that those with more antioxidant capacity (AOC) would have slower rates of decomposition. This has been tested using materials from an incubation experiment, in which a Vertisol had been amended with a number of organic materials. Green waste compost, wheat straw, sugarcane trash and mineral fibre had been added to the soil and incubated for different periods of up to 84 days. Decomposition had been monitored by measuring cumulative carbon dioxide emissions. One and four m NaOH extracts of soil material from the experiment were analysed for their AOC by the Trolox equivalent method. The same method was used to characterize the organic amendments and the unamended soil. AOCs of the amendments were much greater than that of the soil and therefore we expected that the AOC of amended soils would be greater than the unamended control. However, this was not generally the case. A comparison of the AOC of amended soil measured after 7 days with that calculated from the components showed that the measured values of incubated amended soils were less than the calculated ones, particularly for wheat straw and sugarcane trash amendments. This suggests that some of the extractable antioxidants in the amendments were lost or transformed during the first 7 days of incubation. In the remainder of the incubation period there was a small increase in AOC with time in 4 m NaOH extracts of the amended soils, but this was not the case for 1 m NaOH extracts. There was some evidence that amendments with larger AOCs had slower rates of decomposition, especially during the first 7 days of the incubation. Other factors may have been responsible, but C:N ratio alone could not explain the differences. The results are encouraging, but more data are required to test our hypothesis thoroughly.     

Chlamydia-related abortions in cattle from Graubunden, Switzerland

In 2001, the first case of bovine chlamydial abortion was reported in canton Graubunden, Switzerland. In this region, Chlamydophila (Cp.) abortus is endemic in small ruminants. Hence, we aimed to investigate the incidence of chlamydia-related abortions in cattle from Graubunden. During breeding seasons of 2003-2004, formalin-fixed and paraffin-embedded placenta specimens (n = 235) from late-term abortions in cattle were analyzed by histopathology, immunohistochemistry with a Chlamydiaceae-specific monoclonal antibody against chlamydial lipopolysaccharide (LPS), and 2 different polymerase chain reaction (PCR) methods (16 S ribosomal ribonucleic acid [rRNA] PCR, intergenic spacer [IGS-S] PCR), followed by PCR product sequencing. In 149 of 235 cases (63.4%), histopathologic lesions such as purulent and/or necrotizing placentitis were observed. Chlamydial antigen was clearly demonstrated in immunohistochemistry in only 1 of 235 cases (0.4%). Cp. abortus or Cp. psittaci was found in 12 of 235 (5.1%) and 10 of 235 cases (4.2%) by 16 S rRNA PCR and IGS-S PCR, respectively. However, we detected, by 16 S rRNA PCR, 43 of 235 cases (18.3%) to be positive for chlamydia-like organisms. In contrast to the situation in small ruminants in the canton Graubunden, bovine abortion from Cp. abortus seems not to play an important role. Nevertheless, zoonotic potential should be taken into account when handling abortion material from cattle. The significance of chlamydia-like isolates other than Waddlia chondrophila remains an open question in abortion and needs further investigation.     

PCR analysis of bisulfite-modified DNA to investigate developmental variation in micropropagated potatoes (Solanum tuberosum L.)

Summary Bisulfite modification of DNA from potato leaves showing juvenile and mature leaf morphologies and from leaves of autotrophic and heterotrophic microplants showing different morphologies was carried out to deaminate cytosine residues while leaving 5-methylcytosine residues intact. RAPD analysis of the DNA was then performed using selective primers; firstly, with a 50–70% GC content and subsequently with a 50–70% AT content which contained CG or CA 3' ends. Three of the 4 primers used detected band polymorphisms in the juvenile versus mature leaves and all four primers detected band polymorphisms in the autotrophic·versus heterotrophic in vitro leaf samples. These results indicate differences in methylation in the different paired DNA samples. The hypothesised increase in band numbers in the relatively less mature samples was confirmed for both the in vivo and in vitro leaf samples; a higher number of bands was amplified from the DNA of the leaves from heterotrophic cultures compared with those from autotrophic culture when the results for all primer sets were grouped. however, this trend did not apply to the results from all the individual primers. The application of this approach to the evaluation of in vitro protocols for potato micropropagation is discussed.