Studies on the role of the Arabidopsis gene MONOPTEROS in vascular development and plant cell axialization

Three cDNA clones encoding lipid transfer proteins (LTPs) were isolated by applying the rapid amplification of cDNA ends (RACE) protocol to imbibed seeds and germinating seedlings of Brassica napus. The deduced amino-acid sequences show a great degree of homology and they exhibit the common features shared by all LTPs. Their expression pattern indicates a strong developmental, hormonal, and environmental regulation. They are expressed only in cotyledons and hypocotyls of germinating seedlings and their levels of expression increase upon treatment with cis-abscisic acid and NaCl. Their distribution in the cotyledons of young seedlings is suggestive of a role related to the mobilization of lipid reserves.     

Quantitative analysis of parasite DNA in the blood of immunized and naïve mice after infection with Neospora caninum

Real-time PCR was used to study the duration and level of parasitaemia in mice immunized with immune-stimulating complexes (iscoms) containing recombinant NcSRS2, one of the immunodominant surface antigens of Neospora caninum. After challenge infection, blood was collected daily for 9 days. During this period the amounts of parasite DNA detected in immunized mice were significantly lower (P<0.001), and the duration of parasitaemia appeared to be shorter, than in non-immunized controls. Furthermore, the degree of parasitaemia seemed to correlate well with the amount of N. caninum DNA in the brain 3 weeks post-inoculation and with disease severity measured as changes in body weight. These results indicate that the protective immunity induced by the NcSRS2-iscoms was sufficient to reduce the level of parasitaemia, which probably reduced the number of parasites reaching the brain, and could be the reason for the reduction in brain parasite load and clinical symptoms. Furthermore, real-time PCR was found to be a sensitive means for rapid assessment of N. caninum in blood.     

Salmonella, Campylobacter and Enterococcus spp.: Their Antimicrobial Resistance Profiles and their Spatial Relationships in a Synoptic Study of the Upper Oconee River Basin

Rivers may serve as reservoirs for enteric organisms. Very little is known about the boundaries of microbial communities in moving bodies of water so this study was undertaken to find the limits of distribution of some bacteria, focusing on enteric organisms. The presence of Salmonella, Campylobacter, and Enterococcus spp. and the antimicrobial resistance phenotypes carried by these organisms was evaluated for the Upper Oconee River basin, a small river in the lower Piedmont of northeastern Georgia, USA. Samples were obtained from 83 sites during a 3-h period on a spring day (April 2005) in an approximately 30 × 20 km region. Campylobacter spp. was isolated at 12 sites. The Campylobacter isolates from three sites were resistant to tetracycline. Of the five short-variable region (SVR) subtypes of Campylobacter that were found, three were found at more than one site, two types were found twice, and one subtype was found three times. Enterococcus was isolated at 71 sites. E. casseliflavus was the most common species. Based on species identification and antimicrobial resistance patterns, 24 types of Enterococcus were found. Salmonella was isolated from 62 sites. Of the 19 Salmonella serovars that were isolated, serovar Muenchen accounted for about 20% of the isolates. The next three most common serovars isolated, Rubislaw, Hartford, and Give, accounted for about 44% of the river isolates. Antimicrobial resistance profiling offered limited differentiation of Salmonella isolates because only seven isolates were resistant to any antimicrobial. The sites at which Salmonella, Campylobacter, or Enterococcus were isolated did not correlate with each other or with the total coliform number or Escherichia coli count for the site. However, isolates of some of the same species and type occurred in clusters that were restricted to areas within 5 to 6 km.     

A new member of the family of di-iron carboxylate proteins. Coq7 (clk-1), a membrane-bound hydroxylase involved in ubiquinone biosynthesis.

Ubiquinone (UQ) is an essential cofactor for respiratory metabolism. In yeast, mutation of the COQ7 gene results in the absence of UQ biosynthesis and demonstrates a role for this gene in the step leading to the hydroxylation of 5-demethoxyubiquinone. Intriguingly, the disruption of the corresponding gene in Caenorhabditis elegans, clk-1, results in a prolonged life span and a slowing of development. Because of the pleiotropic effect of this disruption, the small size of the protein, and the lack of obvious homology to other known hydroxylases, it has been suggested that Coq7 may be a regulatory or structural component in UQ biosynthesis, rather than acting as the hydroxylase per se. Here we identify Coq7 as belonging to a family of a di-iron containing oxidases/hydroxylases based on a conserved sequence motif for the iron ligands, supporting a direct function of Coq7 as a hydroxylase. We have cloned COQ7 from Pseudomonas aeruginosa and Thiobacillus ferrooxidans and show that indeed this gene complements an Escherichia coli mutant that lacks an unrelated 5-demethoxyubiquinone hydroxylase. Based on the similarities to other well studied di-iron carboxylate proteins, we propose a structural model for Coq7 as an interfacial integral membrane protein.     

Quantification of ammonia exchange between agricultural cropland and the atmosphere: Measurements over two complete growth cycles of oilseed rape,wheat, barley and pea

The exchange of ammonia between the atmosphere and the canopy of barley, wheat, oilseed rape and pea crops was studied over two growing seasons by use of a modified aerodynamic gradient technique in which passive horizontal flux samplers were applied with a wind profile in gradient configuration. The crop foliage was a net source of NH₃ to the atmosphere, with NH₃ emissions on a seasonal basis between 1 and 5 kg NH₃–N ha^–1. The amount of NH₃ lost constituted between 1 and 4% of the applied nitrogen and between 1 and 4% of the actual amount of nitrogen present in the mature shoots. The volatile NH₃ losses depended on seasonal variations in climatic conditions affecting the growth and nitrogen economy of the crops and increased under conditions with excessive N absorption by roots and a high N concentration in the foliage. The accumulated NH₃ loss was positively correlated with the above-ground crop N content at anthesis, but not with that at final maturity. There were no indications that NH₃ emissions were larger under conditions unfavourable for nitrogen remobilization from vegetative plant parts (low N harvest index). Nevertheless, a distinct peak in NH₃ emission occurred during senescence. It is concluded that crops in many areas will represent a significant input of ammonia to the atmosphere and that NH₃ losses may become large enough to significantly affect crop N budgets.     

Physiological regulation of plant-atmosphere ammonia exchange

Plants have a compensation point for NH₃ which ranges from 0.1 to 20 nmol mol^-1, and may be several-fold higher or lower than naturally occurring atmospheric NH₃ concentrations. This implies that NH₃ fluxes over vegetated surfaces are bi-directional and that ammonia exchange with the atmosphere in many cases contributes significantly to the nitrogen economy of vegetation. Physiological regulation of plant–atmosphere NH₃ fluxes is mediated via processes involved in nitrogen uptake, transport and metabolism. A rapid turnover of NH₃ ⁺ in plant leaves leads to the establishment of a finite NH₃ ⁺ concentration in the leaf apoplastic solution. This concentration determines, together with that of H⁺, the size of the NH₃ compensation point. Barley and oilseed rape plants with access to NH₃ ⁺ in the root medium have higher apoplastic NH₃ ⁺ concentrations than plants absorbing NO₃ ^-. Furthermore, the apoplastic NH₃ ⁺ concentration increases with the external NH₃ ⁺ concentration. Inhibition of GS leads to a rapid and substantial increase in apoplastic NH₃ ⁺ and barley mutants with reduced GS activity have higher apoplastic NH₃ ⁺ than wild-type plants. Increasing rates of photorespiration do not affect the steady-state NH₃ ⁺ or H⁺ concentration in tissue or apoplast of oilseed rape, indicating that the NH₃ ⁺ produced is assimilated efficiently. Nevertheless, NH₃ emission increases due to a temperature-mediated displacement of the chemical equilibrium between gaseous and aqueous NH₃ in the apoplast. Sugarbeet plants grown with NO₃ ^- seem to be temporarily C-limited in the light due to a repression of respiration. As a consequence, the activity of chloroplastic GS declines during the day causing a major part of NH₃ ⁺ liberated in photorespiration to be assimilated during darkness when 2-oxoglutarate is supplied in high rates by respiration. This revised version was published online in June 2006 with corrections to the Cover Date.     

Molecular identification and prevalence of Dictyocaulus spp. (Trichostrongyloidea: Dictyocaulidae) in Swedish semi-domestic and free-living cervids

Lungs of 102 roe deer (Capreolus capreolus), 136 moose (Alces alces), 68 fallow deer (Dama dama), and six red deer (Cervus elaphus) were examined during hunting seasons from 16 September 1997 to 1 March 2000. The aim was to determine the species composition and prevalence of Dictyocaulus lungworms in these hosts in Sweden. Worms were identified following polymerase chain reaction (PCR) amplification of the internal transcribed spacer of ribosomal DNA (ITS2), followed by hybridization with four species-specific oligonucleotides. In addition, 50 lungworms from five reindeer (Rangifer tarandus) from Norway were similarly analyzed. A total of 399 worms were recovered and analyzed representing a range of 29-128 worms per host species. All specimens from roe deer were identified as Dictyocaulus capreolus, whereas those from red deer and reindeer were identical with D. eckerti. From moose, 73 (81.1%) of the worms were identified as D. capreolus whereas 17 (18.9%) were D. eckerti. The ITS2 sequence of fallow deer lungworms differed significantly when compared with the ITS2 of D. viviparus, D. capreolus, and D. eckerti. This indicated that fallow deer in Sweden may be infected with a new genotype of Dictyocaulus spp. Consequently, a specific probe designed for the ITS2 from this Dictyocaulus sp. hybridized exclusively with samples from lungworms of fallow deer. Interestingly, no D. viviparus were found in any of these hosts. The prevalence of infection in each host was as follows: D. capreolus in roe deer (14.7%) and moose (10.6%); D. eckerti in moose (0.7%) and red deer (33.3%); and Dictyocaulus sp. in fallow deer (10.3%). Regardless of lungworm species, the overall prevalence of Dictyocaulus spp. in these hosts was 12.2%. Prevalence between male and female animals and among the different age groups did not differ significantly. Finally an enzyme linked immunosorbent assay (ELISA) specific for patent D. viviparus infection in cattle was utilized to analyze lung tissue fluids from infected animals. All samples from roe deer, red deer, and fallow deer were negative in the ELISA. However, three out of twelve (25%) samples from moose and 17 of 40 (43%) samples from cattle were positive. This indicated that moose anti-D. capreolus antibodies recognized the D. viviparus antigen and that anti-cattle immunoglobulin cross-reacted with moose antibodies.     

Life Cycle assessment of frozen cod fillets including fishery-specific environmental impacts

Goal, Scope and Background  The purpose of the present study was to perform an environmental assessment for the entire life cycle of a seafood product and to include fishery-specific types of environmental impact in inventory and assessment. Environmental data for a frozen block of cod fillets was collected and used for a Life Cycle Assessment, including the fishery-specific environmental aspects seafloor use and biological extraction of target, by-catch and discard species. The fishery takes place in the Baltic Sea where cod is mainly fished by benthic trawls and gillnets. Methods  The functional unit was a consumer package of frozen cod fillets (400 g) reaching the household. Data was gathered from fishermen, fishery statistics, databases, companies and literature. Fishery-specific issues like the impact on stocks of the target and by-catch species, seafloor impact and discarding were quantified in relation to the functional unit and qualitative impact assessment of these aspects was included. Results  Findings include the fact that all environmental impact categories assessed (Global Warming Potential, Eutrophication Potential, Acidification Potential, Photochemical Ozone Creation Potential and Aquatic Ecotoxiciy) are dominated by the fishery. Around 700 m² of seafloor are swept by trawls and around 50 g of under-sized cod and other marine species are discarded per functional unit. The phases contributing most to total environmental impact following fishery were transports and preparation in the household. The process industry and municipal sewage treatment cause considerable amounts of eutrophying emissions. Conclusions  Conclusions are that there are considerable options for improvement of the environmental performance of the seafood production chain. In the fishery, the most important environmental measure is to fish sustainably managed stocks. Speed optimisation, increased use of less energy-intensive fishing gear and improved engine and fuel technology are technical measures that would considerably decrease resource use and environmental impact caused by fishery. Due to the importance of fishery for the overall results, the most important environmental improvement option after landing is to maintain high quality and minimise product losses. Recommendations and Outlook  The need for good baseline data concerning resource use and marine environmental impact of fisheries in order to perform environmental assessment of seafood products was demonstrated. LCA was shown to be a valuable tool for such assessments, which in the future could be used to improve the environmental performance of the seafood production chain or in the development of criteria of eco-label-ling of seafood products originating in capture fisheries.