Identification and Characterisation of Xanthomonas campestris pv. campestris Strains from Tanzania by Pathogenicity Tests, Biolog, rep-PCR and Fatty Acid Methyl Ester Analysis

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), is a major disease constraint to cabbage production by smallholder farmers in Africa. Variability exists within the pathogen, and yet differentiation of Xcc strains from other closely-related xanthomonads attacking crucifers is often difficult. The Biolog system, fatty acid methyl ester analysis using microbial identification system (MIS), rep-PCR and pathogenicity tests were used to identify and characterise Xcc strains from Tanzania. Great diversity was observed among Xcc strains in their Biolog and rep-PCR profiles. Specific rep-PCR genomic fingerprints were linked to some geographical areas in the country. Most of the Xcc strains were clustered in two groups based on their fatty acid profiles and symptom expression in cabbage although some deviant strains were found. Each of the methods allowed a degree of identification from species, pathovar to the strain level. Biolog and MIS identified all Xcc strains at least to the genus level. Additionally, Biolog identified 47% of Xcc strains to the pathovar and 43% to strain level, whereas MIS identified 43% of the strains to pathovar level. In the absence of a database, the utility of rep-PCR for routine diagnosis of strains was limited, although the procedure was good for delineation of Xcc to the strain level. These findings indicate the existence of Xcc strains in Tanzania that are distinct from those included in Biolog and MIS databases. The limitations noticed warrant continued improvement of databases and inclusion of pathogenicity testing, using universally susceptible cultivars, as an integral part of strain identification.     

Water distribution and microstructure in enhanced pork

Water characteristics and meat microstructure of NaHCO3-enhanced pork were compared with NaCl- and Na4O7P2-enhanced pork using low-field proton NMR relaxometry, advanced microscopy techniques, and traditional meat quality measurements. Porcine samples were enhanced at 4 degrees C for 48 h with sodium salts individually and in the following combinations: (i) 5% NaCl, (ii) 5% Na4O7P2, (iii) 3% NaHCO3, (iv) 5% NaCl and 5% Na4O7P2, (v) 5% NaCl and 3% NaHCO3, (vi) 5% Na4O7P2 and 3% NaHCO3, and (vii) 5% NaCl, 5% Na4O7P2, and 3% NaHCO3. Independently of the marinade used, the water-binding capacity was improved, cooking loss was reduced, and the yield was enhanced compared with nonmarinated pork samples. This was also reflected in the water mobility within the samples measured by proton NMR relaxometry. Visualization of samples by confocal laser scanning microscopy (CLSM) revealed salt-dependent microstructural changes in the green pork samples treated with NaHCO3, giving rise to nearly complete disintegration of overall structures. High-resolution visualization by atomic force microscopy (AFM) further suggested that a higher cooking loss in sodium chloride-enhanced samples could be ascribed to less solubilization and higher heat-induced protein denaturation compared with phosphate- and bicarbonate-enhanced samples.     

Impacts of the Kyoto Protocol on boreal forest climate change mitigation

? Context

The Kyoto Protocol allows the use of domestic forest carbon sequestration to offset emissions to a limited degree, while bioenergy as an unlimited emission reduction option receives substantial financial support in many countries.

? Aim

The primary objective of this study was to analyze (1) whether these limits on forest carbon sequestration would be binding, thereby leading to inefficient mitigation, and (2) the total potential effect of the protocol on the greenhouse gas (GHG) fluxes in the forest sector.

? Methods

A partial equilibrium model of the Norwegian forest sector was used to quantify the GHG fluxes in a base scenario with no climate policy, a Kyoto Protocol policy (KP policy), and a policy with no cap on forest carbon sequestration (FC policy), assuming that the policies apply the rest of the century.

? Results

Carbon offsets are higher under the KP policy than in the base scenario and likewise higher than under the FC policy in the short run, but the KP policy fails to utilize the forest carbon sequestration potential in the long run as it provides considerably less incentives to invest in forestry than the FC policy.

? Conclusion

The KP increases the Norwegian forest sector’s climate change mitigation compared to no climate policy but less in the long run than a carbon policy with no cap on forest carbon credits.     

SOS response induction by beta-lactams and bacterial defense against antibiotic lethality

The SOS response aids bacterial propagation by inhibiting cell division during repair of DNA damage. We report that inactivation of the ftsI gene product, penicillin binding protein 3, by either beta-lactam antibiotics or genetic mutation induces SOS in Escherichia coli through the DpiBA two-component signal transduction system. This event, which requires the SOS-promoting recA and lexA genes as well as dpiA, transiently halts bacterial cell division, enabling survival to otherwise lethal antibiotic exposure. Our findings reveal defective cell wall synthesis as an unexpected initiator of the bacterial SOS response, indicate that beta-lactam antibiotics are extracellular stimuli of this response, and demonstrate a novel mechanism for mitigation of antimicrobial lethality.     

Post-mortem changes in porcine M. longissimus studied by solid-state 13C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy

Solid-state (13)C cross-polarization (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) experiments are carried out for the first time on rapidly frozen muscle biopsies taken in M. longissimus in vivo and at 1 min, 45 min, and 24 h post-mortem from three pigs. Two of the pigs were CO(2)-stunned (control animals), and one was pre-slaughter-stressed (treadmill exercise) followed by electrical stunning to induce difference in metabolism post-mortem. (13)C resonance signals from saturated and unsaturated carbons in fatty acids, carboxylic carbons, and carbons in lactate and glycogen are identified in the solid-state NMR spectra. The (13)C CP MAS spectra obtained for post-mortem samples of the stressed, electrically stunned pig differ significantly from the post-mortem control samples, as the intensity of a resonance line appearing at 30 ppm, assigned to carbons of the methylene chains, is reduced for the stressed pig. This spectral difference is probably due to changes in lipid mobility and indicates altered membrane properties in the muscle of the stressed/electrically stunned animal when compared with the control animals already 1 min post-mortem. In addition, the post-mortem period changes in glycogen carbons can be estimated from the (13)C CP MAS spectra, yielding a correlation of r = 0.74 to subsequent biochemical determination of the glycogen content.     

Molecular water motions of skim milk powder solutions during acidification studied by 17O and 1H nuclear magnetic resonance and rheology

The molecular motion of water was studied in glucono-δ-lactone-acidified skim milk powder (SMP) solutions with various pH values and dry matter contents. NMR relaxometry measurements revealed that lowering the pH in SMP solutions affected 17O and 1H T2 relaxation rates almost identically. Consequently, the present study indicates that the proteins present in the samples do not affect the 1H relaxation behavior markedly, even at relatively high SMP concentrations (15-25%). Comparison of rheological measurements and NMR measurements suggested that the collapse of κ-casein during acidification could contribute to the initial decrease in 17O and 1H relaxation rate in the pH range between 6.6 and 5.5 for 15% SMP and in the pH range between 6.6 and 5.9 for 25% SMP. However, below pH 5.5 the viscosity and 17O and 1H NMR relaxation rates did not correlate, revealing that the aggregation of casein micelles, which increases viscosity below pH 5.5, does not involve major repartitioning of water.     

Premature death, risk factors, and life patterns in dogs with epilepsy

BACKGROUND: Epilepsy in dogs is often difficult to medically control, resulting in premature death of dogs with epilepsy. However, the risks of premature death are not known. HYPOTHESIS: Dogs with epilepsy have an increased risk of premature death as compared to a general population of dogs. ANIMALS: Sixty-three dogs diagnosed with epilepsy between 1993 and 1996 were included in this study. METHODS: A prospective longitudinal study of the population was performed from the diagnosis of epilepsy until the time of euthanasia, death, or a maximum of 12 years to investigate mortality and risk factors. Information about sex, onset, type, frequency, and control of seizures, remission of epilepsy, death, cause of death, and owner's perspective was collected and analyzed. RESULTS: The median age at death of dogs was 7.0 years. The life span of dogs in which euthanasia or death was directly caused by their epileptic condition was significantly shorter as compared with epileptic dogs that were euthanized because of other causes (P = .001). The median number of years that a dog lived with epilepsy was 2.3 years. Females lived longer with epilepsy than males (P = .036). Seizure type (primary generalized versus focal seizures) was not significantly associated with survival time. The remission rate of epilepsy (spontaneous remission and remission with treatment) was 15%. CONCLUSION AND CLINICAL IMPORTANCE: The diagnosis of epilepsy implies an increased risk of premature death. The prognosis for dogs with epilepsy is dependent on a combination of veterinary expertise, therapeutic success, and the owner's motivation.     

Effect of differential N and S competition in inter- and sole cropping of Brassica species and lettuce on glucosinolate concentration

Field and greenhouse pot experiments were conducted to evaluate the potential to use intercropping as an alternative method to increase glucosinolates in Brassicas by manipulating nitrogen (N) and sulfur (S) balance by intercropping with lettuce (Lactuca sativa L. var. capitata). In both experiments, four combinations of N and S fertilization were used. In the field experiment no effect of intercropping on the total glucosinolate concentration was found as the growing lettuce was strongly inhibited by the presence of broccoli (Brassica oleracea L. var. italic). In contrast to this, in the pot experiment both total and individual glucosinolate concentrations in red leaf mustard (Brassica juncea L.) increased by intercropping. Fertilization treatments influenced glucosinolate concentrations in both experiments, and an interaction between N and S fertilization was noticed.     

Grain yield increase in cereal variety mixtures: A meta-analysis of field trials

Plant ecology theory predicts that growing seed mixtures of varieties (variety mixtures) may increase grain yields compared to the average of component varieties in pure stands. Published results from field trials of cereal variety mixtures demonstrate, however, both positive and negative effects on grain yield. To investigate the prevalence and preconditions for positive mixing effects, reported grain yields of variety mixtures and pure variety stands were obtained from previously published variety trials, converted into relative mixing effects and combined using meta-analysis. Furthermore, available information on varieties, mixtures and growing conditions was used as independent variables in a series of meta-regressions. Twenty-six published studies, examining a total of 246 instances of variety mixtures of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), were identified as meeting the criteria for inclusion in the meta-analysis; on the other hand, nearly 200 studies were discarded. The accepted studies reported results on both winter and spring types of each crop species. Relative mixing effects ranged from −30% to 100% with an overall meta-estimate of at least 2.7% (p < 0.001), reconfirming the potential of overall grain yield increase when growing varieties in mixtures. The mixing effect varied between crop types, with largest and significant effects for winter wheat and spring barley. The meta-regression demonstrated that mixing effect increased significantly with (1) diversity in reported grain yields, (2) diversity in disease resistance, and (3) diversity in weed suppressiveness, all among component varieties. Relative mixing effect was also found to increase significantly with the effective number of component varieties. The effects of the latter two differed significantly between crop types. All analyzed models had large unexplained variation between mixing effects, indicating that the variables retrievable from the published studies explained only a minority of the differences among mixtures and trials.