Physiological Responses of <Emphasis Type="Italic">Rosa rubiginosa</Emphasis> to Saline Environment

The aim of this work was to analyse the response of Rosa rubiginosa to salinity induced by different concentrations of sodium chloride and calcium chloride (0, 25, 50, 100, 150 and 200 mM). Besides salt accumulation and pH changes, other parameters were investigated including photosynthetic activity, leaf water content, the dynamics of necrosis and chlorosis appearance and leaf drying. The study was complemented with microscopic analysis of changes in leaf anatomy. R. rubiginosa was more sensitive to the salinity induced by calcium chloride than by sodium chloride. Plant response to salinity differed depending of the salt concentration. These differences were manifested by higher dynamics of necrosis and chlorosis appearance and leaf drying. CaCl₂ showed greater inhibition of the photosynthetic apparatus and photosynthetic activity. Treatment with CaCl₂ caused more visible deformation of palisade cells, reduction in their density and overall reduction in leaf thickness. The study demonstrated higher accumulation of CaCl₂ in the soil, and thus greater limitations in water availability resulting in reduced leaf water content and quicker drying of leaves as compared with NaCl-treated plants.     

Diminished vessel diameter as a possible factor in the decline of European ash (Fraxinus excelsior L.)

? The aim of this work was to examine the anatomy and functioning of secondary xylem in stems in relation to the decline of European ash (Fraxinus excelsior L.).

? We tested the hypothesis that declining trees show changes in the structure of wood, which result in impaired water transport.

? Anatomical analyses were carried out on wood samples (comprising all annual rings formed during the 30 years life of the analysed trees) collected at breast height from the main stem of healthy, weakened and dead ash trees. The width of annual wood increments, the diameter and density of earlywood vessels were measured and the theoretical hydraulic conductivity index through the secondary xylem calculated by application of Hagen-Poisseuille’s formula.

? Anatomical characteristics changed both with the age of trees and in response to unfavorable factors. The largest vessels were observed in healthy trees, which implied that they had the highest hydraulic conductivity index, whereas trees considered to be in decline produce smaller vessels and hence had reduced conductivity.

     

Probiotic preparation reduces the faecal water genotoxicity in chickens fed with aflatoxin B1 contaminated fodder

The aim of the study was to evaluate the influence of a probiotic preparation on the genotoxicity of faecal water of broiler chickens fed with a fodder contaminated with aflatoxin B₁ (AFB₁) at 1 or 5 mg per kg. Human blood lymphocytes were exposed to chicken’s faecal water samples and DNA damage was measured using the comet assay. Genotoxicity of faecal water did not depend on the AFB₁ concentration in the fodder. The mean DNA damage, measured as the percentage of DNA in the tail of the comets, for chickens fed with fodder with AFB₁ at 1 mg/kg was 16.80 ± 0.66, at 5 mg/kg – 16.73 ± 1.51 and in the controls – 12.79 ± 0.66. The supplementation of fodder with the probiotic preparation decreased the extent of DNA damage to 10.02 ± 0.39 for 1 mg/kg AFB₁ and to 11.89 ± 0.72 for 5 mg/kg.     

Artificial reproduction of wild and cultured barbel (Barbus barbus, Cyprinidae) under controlled conditions

The aim of this work was to compare the effects of controlled reproduction of cultured and wild common barbel, Barbus barbus (L.). Preparations containing different GnRH analogues and dopamine receptor antagonists (Ovopel, Ovaprim) as well as human chorionic gonadotropin (hCG) (in the case of cultured fish) were applied and their influence on ovulation, spermiation and quality of gametes obtained was determined. No differences in the qualitative or quantitative parameters of semen were found between fish stimulated with different hormonal preparations and those not receiving hormonal stimulation. The high suitability of Ovaprim for ovulation induction in (cultured and wild) barbel was confirmed. The highest synchronisation of ovulation was obtained after the application of Ovopel (18 ± 3 h), but the best results of controlled reproduction (expressed as the percentage of ovulations and survival of embryos) were obtained by applying Ovaprim (83.2 ± 4.1). A significantly higher percentage of ovulation was obtained in cultured fish (80-90%) than in wild fish (< 25%).     

Profiles of seroconversion to porcine circovirus type 2 in herds affected and not affected by postweaning multisystemic wasting syndrome

The aim of the present study was to explore the usefulness of serological methods in the diagnosis of postweaning multisystemic wasting syndrome (PMWS). The study was carried out in 4 PMWS-affected and 6 control farms. Based on the serological profiles, infection with porcine circovirus type 2 (PCV2) was determined to take place at 3-7 weeks of age in the PMWS-affected and at 3-11 weeks of age in the control farms. To compare the dynamics of seroconversion to PCV2 among farms, cross-sectional serological profiles were normalised in relation to the inferred age of infection. The results indicated that the proportion of seropositive pigs increased significantly slower in the affected herds. The most pronounced difference was observed about 4 weeks after infection, when the proportion of seropositive pigs ranged from 0 to 53.3% and from 70 to 100% in PMWS-affected and control herds, respectively. Mean antibody titres at that age were also significantly lower in the affected farms. These observations suggest a delay in the production of PCV2-specific antibodies and indicate that serological methods may be helpful in identifying herds with a high risk of PMWS.     

QTLs for potato tuber resistance to Dickeya solani are located on chromosomes II and IV

The goal of this research was to identify quantitative trait loci (QTLs) for potato tuber resistance to the soil- and seedborne bacterium Dickeya solani and for tuber starch content, to study the relationship between these traits. A resistant diploid hybrid of potato, DG 00-270, was crossed with a susceptible hybrid, DG 08-305, to generate the F₁ mapping population. Tubers that were wound-inoculated with bacteria were evaluated for disease severity, expressed as the mean weight of rotted tubers, and disease incidence, measured as the proportion of rotten tubers. Diversity array technology (DArTseq) was used for genetic map construction and QTL analysis. The most prominent QTLs for disease severity and incidence were identified in overlapping regions on potato chromosome IV and explained 22.4% and 22.9% of the phenotypic variance, respectively. The second QTL for disease severity was mapped to chromosome II and explained 16.5% of the variance. QTLs for starch content were detected on chromosomes III, V, VI, VII, VIII, IX, XI, and XII in regions different from the QTLs for soft rot resistance. Two strong and reproducible QTLs for resistance to D. solani on potato chromosomes IV and II might be useful for further study of candidate genes and marker development in potato breeding programmes. The relationship between tuber resistance to bacteria and the starch content in potato tubers was not confirmed by QTL mapping, which makes the selection of genotypes highly resistant to soft rot with a desirable starch content feasible.     

Multiplex detection ofPotato virus S, Potato virus X, andPotato virus Y by non-radioactive nucleic acid spot hybridization in potato tissue culture plantlets

Potato plantlets initiated into tissue culture must be tested for numerous viruses prior to propagation for seed potato production. Ideally, one plantlet is tested for all pathogens of concern and, if found pathogen-free, this plantlet is propagated for production of seed potatoes. Commercially available ELISA kits are generally used for the pathogen tests, but the commercial kits have some limitations. For example, the protocols differ for different viruses, so multiple extractions must be completed, increasing the time and expense of testing. This is a significant problem with tissue culture plantlets, for which there is limited material available to test and an ever-increasing number of pathogens that must be tested for, including viruses in the potyvirus, carlavirus, potexvirus, luteovirus, pomovirus, tobravirus, tospovirus, alfamovirus, and tymovirus groups. We have optimized a non-radioactive nucleic acid hybridization (NASH) assay for the simultaneous detection of carlavirusPotato virus S (PVS), potexvirusPotato virus X (PVX) and potyvirusPotato virus Y (PVY) in potato tissue culture plantlets. This assay requires a single extraction from a small portion of a tissue culture plantlet for the detection of viruses from three different families.