Regrowth and dry matter allocation in Quercus robur (L.) seedlings root pruned prior to transplanting

Two-year seedlings of Quercus robur (pedunculateoak) were root-pruned before transplanting in order toevaluate the importance of coarse versus fine roots onregrowth. Root systems were pruned by leaving c. 19,13 or 7 cm root from the root collar. Alternatively,coarse roots (>2 mm in diameter) were removed, leaving only the taproot and the fine roots (<2 mm)attached, or fine roots were removed from coarse rootsand taproot. Growth of shoots and roots after onegrowing season was compared to an unpruned controlunder standard nursery conditions. Seedlings rootpruned to 19, 13 or 7 cm were further tested undercompetition achieved by transplanting into a mixtureof clover and grass. Pruning of the root systemsignificantly reduced regrowth in terms of total plantDW in accordance with the severity of pruning, shootDW being more affected than root DW. Removal of coarseroots depressed final root DW whereas removal of fineroots reduced shoot DW and hence root:shoot ratioincreased. The study suggests that fine and coarseroots have different roles in root:shoot allocation.The competition test increased root:shoot ratioindicating that competition induced seedlings toallocate more of their resources into growth of theroot system.     

Reduced use of antimicrobials after vaccination of pigs against porcine proliferative enteropathy in a Danish SPF herd

The present study explored whether the use of group medication with antibiotics in a Danish pig herd was reduced after vaccination of the pigs against proliferative enteropathy (PE) caused by Lawsonia intracellularis. 7900 pigs originating from a single commercial sow herd were vaccinated against L. intracellularis, whereas 7756 pigs were kept as non-vaccinated controls. The pigs were included batch-wise in the study with every second batch being vaccinated. In the vaccinated batches, the consumption of oxytetracykline to treat PE was reduced by 79%, with a significantly lower number of pigs being treated (P < 0.0001). Vaccination also resulted in a highly significant improvement of average daily weight gain (+ 46 g/day; P = 9.55 × 10^-31) and carcase weight (+ 1.25 kg; P = 4.54 × 10^-05) as well as a shortened fattening period (-8 days; P = 2.01 × 10^-45).     

Binding of recombinant norovirus like particle to histo-blood group antigen on cells in the lumen of pig duodenum

Histo-blood group antigens (HBGA) expressed on cells in the human GI tract have been shown to function as receptors for noroviruses. In concordance with earlier reports (Backer et al., 1997; Yamamoto and Yamamoto, 2001), this study found that individual pigs are either HBGA type A positive or type H1 (type O) positive. Recombinant norovirus like particles from a genogroup I (rNVLP) or three genogroup II (rMOH, rVA207, and rVA387) strains bound to plates coated with pig gastro-intestinal washings with similar binding patterns to humans. The binding of human norovirus like particles was inhibited by pre-incubating the wells with MAbs specific for either type A or type H1 HBGA, or by the presence of free HBGAs from human saliva. Co-localization of rNVLP and corresponding HBGA on epithelial cells of pig gastro-intestinal tissue (PGIT) was also observed. These findings suggest that rNVLP binds to HBGAs expressed on PGIT epithelial cells. This is the first report of the specific binding of human rNVLP to HBGAs in epithelial cells of pig gastrointestinal tissue. It highlights the importance of further study of human norovirus incidence and potential infection and residence in non-human animal hosts and suggests the possibility that norovirus may be a zoonotic pathogen.