Relationship between Polyamines and Other Cold‐induced Response Mechanisms in Different Cereal Species

To find a connection between polyamines and various protective effectors involved in the development of cold tolerance, eight different cereal genotypes, including wheat, barley and oat species, were investigated during the acclimation phase to low temperature. Exposure to low temperature induced different changes in the levels of polyamines, and other signalling molecules, such as salicylic acid and abscisic acid, and of other protective compounds, namely flavonols, sugars and antioxidant enzyme activity, and in the lipid composition of certain membrane factions. The most remarkable differences were observed in the oat varieties compared to the other cereal genotypes, which was manifested in the lack of spermidine accumulation and of decrease in trans‐Δ³‐hexadecanoic acid content, in lower initial and not cold‐inducible abscisic acid content and guaiacol peroxidase activity after cold treatment. Correlation analysis revealed that spermidine shows strong positive relationship with flavonols, abscisic acid and ascorbate peroxidase, while was in negative relationship with trans‐Δ³‐hexadecanoic acid. These results suggest that spermidine may have a crucial role in the cold acclimation signalling processes in cereals.     

Aggregation of sow lactobacilli with diarrhoeagenic Escherichia coli

A total of 20 strains of lactobacilli were isolated from the oesophagus and vagina of 20 sows at the time of partus. Aggregation activity was seen between six homofermentative autoaggregative lactobacilli and three strains of pathogenic Escherichia coli with F4, F5 and F6 fimbriae. The highest aggregation activity was observed between vaginal Lactobacillus acidophilus PV 32 or oesophageal OE 2/1 and E. coli with F4 (K88). The presence of aggregation-promoting factor (APF) was confirmed by polymerase chain reaction (PCR) with primers of a specific fragment the apf gene derived from human L. gasseri 4B2 in one oesophageal L. acidophilus strain OE 2/1. We propose that autoaggregative lactobacilli that aggregate with diarrhoeagenic E. coli can express a class of APF proteins that exhibit the function of an aggregation mediator.     

Study of gastrointestinal parasites in water buffalo (Bubalus bubalis) reared under Mexican humid tropical conditions

Tropical Animal Health and Production - The objective was to determine the frequency of gastrointestinal parasites (GP) genera affecting water buffalo (Bubalus bubalis) reared under humid tropical...     

Penetration of parenterally administered ceftiofur into sterile vs. Pasteurella haemolytica-infected tissue chambers in cattle

The effect of bacterial infection on antibiotic activity and penetration of parenterally administered ceftiofur into implanted tissue chambers was studied in cattle. Tissue chambers were implanted subcutaneously in the paralumbar fossae of eight calves (256-290 kg body weight). Approximately 80 days after implantation, the two chambers on one side of each animal were inoculated with Pasteurella haemolytica (10⁶ CFU/chamber). Eighteen hours after inoculation, ceftiofur sodium was administered intravenously (5 mg/kg) to each of the calves. Non-infected chamber fluid, infected chamber fluid and heparinized blood samples were collected immediately before and at 1, 3, 6, 12 and 24 h after drug administration. Concentrations of ceftiofur and desfuroylceftiofur metabolites and ceftiofur-equivalent microbiological activity were measured by high-pressure liquid chromatography and microbiological assay respectively. Concentrations of ceftiofur and desfuroylceftiofur metabolites and antimicrobial activity in P. haemolytica -infected tissue chambers were significantly higher than those in non-infected tissue chambers at all sampling times, indicating that ceftiofur, regardless of the method used for analysis, localizes at higher concentrations at tissue sites infected with P. haemolytica . Antibiotic activity-concentration ratios were lower in plasma and infected chamber fluid compared with non-infected chamber fluid, suggesting that antibiotic was bound to proteins. However, higher antimicrobial activity in the infected chamber fluid compared with the non-infected chamber fluid suggests that active drug is reversibly bound to proteins. Protein-bound desfuroylceftiofur may represent a reservoir for release of active drug at the site of infection in the animal.