Distribution of a pathological form of prion protein in the brainstem and cerebellum in classical and atypical cases of bovine spongiform encephalopathy

This study evaluated the distribution and signal intensity of a prion protein resistant to proteolysis (PrP(res)) in the brainstem and cerebellum of cattle affected with classical and atypical forms of bovine spongiform encephalopathy (BSE) using a Western immunoblotting technique. In both classical and atypical cases of BSE, a stronger signal was detected in the more rostral brainstem regions relative to the obex. In classical and H-type cases a significant decrease in the PrP(res) signal was found in the cerebellum when compared to that in the obex, whereas L-type BSE cases were characterised by signals of similar intensity in these regions. The uniform distribution of PrP(res) in the region rostral to the obex suggests that when autolysed samples are being tested for BSE, both classical and atypical forms are detectable, even when this target site is missing or cannot be clearly identified. The findings indicate that both the obex and rostral brainstem can be used for BSE diagnosis whereas use of the more caudal brainstem regions and cerebellum is not recommended.     

Defence responses ofArabidopsis thalianaduring invasion and feeding site induction by the plant–parasitic nematodeHeterodera glycines

The nature of local defence responses occurring during the infection ofArabidopsis thalianaby the soybean cyst nematodeHeterodera glycineswas analysed by light and electron microscopy.Arabidopsis thalianais not a regular host of this nematode, but invasion, feeding site induction and in rare cases development of juveniles was observed. Compared toHeterodera schachtii, which interacts compatibly withA. thaliana, the period of invasion and migration was prolonged. During migration a strong hypersensitive response, characterized by extensive necroses, browning, autofluorescence and cell wall depositions, occurred in cells that were not in direct contact with the nematodes. Cells selected as initial syncytial cells were pierced with the stylet and, after having passed a preparation phase, secretions were released. The cells responded with rapid vacuolation and deposition of callose-like material around the stylet and at the cell walls, and subsequent necrosis. In a very few cases the initial syncytial cells and neighbouring cells deposited callose-like material on their walls, but these cells remained intact so that functional syncytia developed, which allowed occasional nematode development.     

Different recombination frequencies in wheat doubled haploid populations obtained through maize pollination and anther culture

This study compared the meiotic recombination frequency between wheat doubled haploid (DH) populations obtained through two different methods, maize pollination (MP♀) and anther culture (AC♂). The comparison was based on a genetic linkage analysis, performed with DNA markers. Thirty-five polymorphic markers (15 SSR, 15 AFLP, 5 RAPD) were screened in MP♀ and AC♂ doubled haploids populations, derived from the same hybrid genotype (F₁ of ‘Eta’ × ‘Darkhan 15’). Nine linkage groups, comprising 35 loci (the MP♀ lines) and 31 loci (the AC♂ lines), were constructed. The linkage groups in both DH populations showed identical orders of markers, except for one group mapping to chromosome 6B. The MP♀ and AC♂ linkage maps differed significantly in recombination frequencies for corresponding intervals. In total, the AC♂ linkage map (495.5 cM) was 40.5% longer than the MP♀ map (352.8 cM), indicating a significantly higher meiotic recombination rate in pollen mother cells. The enhancement in recombination was visible in five of nine linkage groups, and in 7 intervals between individual loci out of 19 compared. Moreover, for 6 other intervals a lack of linkage was observed in the AC♂ population, as compared to the MP♀ map.     

An automated,cost-effective and scalable,flood-and-drain based root phenotyping system for cereals

Background

Genetic studies on the molecular mechanisms of the regulation of root growth require the characterisation of a specific root phenotype to be linked with a certain genotype. Such studies using classical labour-intensive methods are severely hindered due to the technical limitations that are associated with the impeded observation of the root system of a plant during its growth. The aim of the research presented here was to develop a reliable, cost-effective method for the analysis of a plant root phenotype that would enable the precise characterisation of the root system architecture of cereals.

Results

The presented method describes a complete system for automatic supplementation and continuous sensing of culture solution supplied to plants that are grown in transparent tubes containing a solid substrate. The presented system comprises the comprehensive pipeline consisting of a modular-based and remotely-controlled plant growth system and customized imaging setup for root and shoot phenotyping. The system enables an easy extension of the experimental capacity in order to form a combined platform that is comprised of parallel modules, each holding up to 48 plants. The conducted experiments focused on the selection of the most suitable conditions for phenotyping studies in barley: an optimal size of the glass beads, diameters of the acrylic tubes, composition of a medium, and a rate of the medium flow.

Conclusions

The developed system enables an efficient, accurate and highly repeatable analysis of the morphological features of the root system of cereals. Because a simple and fully-automated control system is used, the experimental conditions can easily be normalised for different species of cereals. The scalability of the module-based system allows its capacity to be adjusted in order to meet the requirements of a particular experiment.

     

Effect of feeding various levels of poultry by‐product meal on the blood parameters,filet composition and structure of female tenches (Tinca tinca)

Homogeneous background (age, sex, genetic lineage, culture conditions) was created to clearly demonstrate the impact of the tested dietary treatments. No feeds optimized for the rearing of the tench (Tinca tinca L. 1758) are available. Feeds are formulated to increase the growth rate or eliminate skeletal deformations. With the increasing prices of the basic components, fish meal (FM) and fish oil, poultry by‐product meal (PBM) can be used. The aim of the study was to evaluate the effects of substitution of FM with PBM on the tench blood parameters, body composition and structure of skeletal muscles. Cage‐reared female tenches (325 ± 18 g) were fed for 86 days with five types of feeds with 0% (control), 25.7%, 48.6%, 71.4% and 100% substitution of FM with PBM. No significant differences between the formulations were reported for weight, total length, fillet weight, visceral, liver, gonado‐somatic, proximate composition and biochemical blood parameters. However, significant differences were found in the fillet profiles of fatty acids—an increase in the PBM content correlated with an increase in saturated and monounsaturated fatty acids and a decrease in n‐3 PUFA and, generally, n‐6 PUFA. Significant differences were also observed in, for example, the content of intramuscular fatty tissue and the level of organ lipidosis between the control variant (0% PBM) and that with 100% substitution. A sensory assessment indicated a higher gustatory value of the fillets in the case of feeds with 48.6% and 71.4% substitution.     

Arginase activity in Arabidopsis thaliana infected with Heterodera schachtii

The activity of arginase (ARGAH), which results in ornithine and urea production, is important for nitrogen metabolism in all organisms as well as for defence responses. The second‐stage juveniles of the cyst‐forming nematode Heterodera schachtii penetrate roots and induce the formation of a permanent feeding site. To determine whether infection with H. schachtii causes the induction of arginase, the expression was studied in Arabidopsis roots and shoots at the day of inoculation and at 3, 7 and 15 days post‐inoculation (dpi). Parasite infection caused a strong decrease of root arginase activity and ARGAH1 gene expression, which persisted over the entire examination period. In shoots, the mRNA expression of ARGAH2 increased at 3 and 7 dpi, but the enzymatic activity was significantly enhanced only at 3 dpi. Thus, while arginase down‐regulation occurs in roots, which is apparently due to the presence of nematode effectors, in shoots the activity is only transiently up‐regulated despite persistently high gene expression. As oxidative stress is possible during nematode infection, the activity and gene expression of glutathione reductase, a marker of the redox equilibrium, were estimated and found to be significantly enhanced at 7 dpi in shoots of infected plants. The level of proline, an amino acid known for its ability to scavenge free radicals, was increased 60‐fold. The results suggest that the disruption of redox homeostasis, as reflected by increased proline level and glutathione reductase expression and activity, accompanies changes in arginine metabolism in the shoots, indicating systemic changes induced by nematode infection.     

Induction of Out-of-Season Spawning of Pikeperch, Sander Lucioperca (L.)

Pikeperch were induced to spawn 3 months prior to the natural spawning period through photothermal and hormonal stimulation. Females (five specimens in each group) were stimulated with injection of human chorionic gonadotropin (hCG) once (200 IU kg^–1), twice (200 IU kg^–1, second dose after 48 h–400 IU kg^–1) or three times (200 IU kg^–1, after 24 h–200 IU kg^–1 and after another 24 h–200 IU kg^–1). The control group was injected once with 0.9% NaCl. The males were stimulated with a single hormone dose of 200 IU kg^–1. Eggs were obtained from all the hormonally treated fish. None of the control group females, which were only stimulated photothermally, ovulated any eggs. The time of ovulation was 66–71 h following the first injection, and the eggs viability until the eyed stage (from 71.5 to 77.5%) did not depend on the number of hormone doses (P > 0.05). The out-of-season spawning method described in this paper could be used to provide pikeperch larvae for intensive culture systems (recirculating water systems) before natural spawning season and to produce larger-sized pikeperch fingerlings for stocking.     

Dependence of Coregonus albula embryogenesis rate on the incubation temperature

Eggs stripped from Coregonus albula were incubated at different constant temperatures. The duration of embryogenesis varied from 183 days at 1.1°C to 45 days at 9.9°C. We describe the course of embryogenesis using 16 easily recognizable developmental stages (DS j). Development rate (DR j) for any given stage (DS j) is expressed as the reciprocal of time (in days) from fertilization to attainment of a given developmental stage. The generalized equation relating rate of development to stages DS j with respect to temperature (x) is

The values of DR to the “eyed egg” stage and to 50% hatch, expressed as percentage per day of the total development period, were computed and tabulated for temperatures ranging from 0.1 to 9.9°C. To verify the derived regression model we observed the course of embryogenesis of C. albula eggs incubated in a commercial hatchery at fluctuating temperatures. The observed times of attainment of the successive developmental stages were compared to the predicted times based on mean daily water temperatures. The time observed agreed well with times predicted by the model; the only exception was the time of hatching, which was systematically overestimated (5 to 7 days) by the model. This was possibly due to the influence of dissolved oxygen on the time course of hatching processes, which was not considered in our regression model.