Rickettsial infection in farmed Atlantic salmon in eastern Canada

The cause of death in a postsmolt, Atlantic salmon population with elevated levels of mortalities was investigated. Diagnosis of a rickettsia-like organism was based on gross pathology, histopathology, differential staining, electron microscopy and fluorescent antibody tests. The course of the infection and response to treatment are discussed. This is the first reported occurrence of salmon rickettsias in the Atlantic coast of North or South America.     

Identification of pathogenic Leptospira strains in tissues of a premature foal by use of polymerase chain reaction analysis.

Studies were carried out to determine the cause of death in a prematurely born Thoroughbred foal that died 24 hours after birth. Necropsy revealed gross lesions suggestive of septicemia. A commercial Leptospira polymerase chain reaction (PCR) assay designed to specifically amplify the hemolysis-associated protein 1 (hap1) gene present only in pathogenic Leptospira strains detected the presence of Leptospira DNA in various tissues of the foal. Histologic examination of lung, liver, kidney, and myocardium revealed numerous spirochetes in Warthin-Starry-stained tissue sections. Results of PCR analysis and histologic examination suggested a leptospiral infection in the newborn foal. At the moment of death, the infection coexisted with a streptococcal-associated aspiration bronchopneumonia and postpartum septicemia. These findings indicate that the PCR assay based on the amplification of the hap1 gene represents a useful tool for specific detection of pathogenic leptospira in field samples taken from horses.     

Bridging the Gap between Centrally Defined Policies and Local Decisions – Towards more Sensitive and Creative Rural Landscape Management

European policies and instruments such as the Common Agricultural Policy (CAP) and many instruments for nature and landscape conservation in Europe have for some decades been dominated by centralisation and standardisation. This paper shows that this has led to the neglect of contextual and place-related approaches and an unnecessarily high degree of over-simplification. Recently, as a reaction to this over-simplification, diversity and specific character has been particularly stressed in many European and national strategies for rural landscapes and conservation, but the processes of simplification still continue. Using examples from mixed agriculture and forestry landscapes in Portugal, Slovenia and Sweden, this paper aims to contribute to understanding the gap between centrally defined strategies for rural landscapes and awareness and management practices at local level. The three countries are situated at the outer fringes of Europe, and are complementary with their different degrees of urbanisation, forest distribution and tree-richness in the agricultural landscapes. Furthermore, the aim is to show how local landscape management is driven and to identify factors contributing to a better use of public policies through a participatory process with visions for the future. Systems of landscape classifications such as landscape character assessment often recognise the specific character of these landscapes, but have so far achieved very little for the preservation of their locally specific values, nor have they contributed to the development and the creation of new visions for future management. Such systems could contribute much more if they could be opened to adaptation on a more local scale in communication-led management planning.     

Extravasation of lymphocytes via paracortical venules in sheep lymph nodes: visualization using an intracellular fluorescent label

In rodents and humans, lymphocytes extravasate into lymph nodes via specialized paracortical venules lined with high endothelium (HEV). Sheep and other ruminants do not have morphologically defined HEV in their lymph nodes. It has been assumed that lymphocyte extravasation in these species proceeds via analogous structures; i.e., paracortical venules lined with low to medium endothelium. In this study, lymphocyte suspensions were prepared from surgically excised lymph nodes of sheep and labeled with an intracellular fluorescent dye, H33342. Labeled cells were infused intravenously back into donors, and sheep were killed at various intervals after infusion. Frozen sections of lymph nodes were examined microscopically for the location of labeled cells. Ten minutes after infusion, labeled cells were seen in the lumen of venules located in the paracortical region of the nodes. At later time points, cells were seen apparently migrating through the venule walls and in the adjacent paracortical tissue. Similar experiments were performed in which H33342-labeled murine lymphocytes were infused into syngeneic mice. When equivalent cell numbers (based on animal size) were infused, no obvious differences were seen between location and kinetics of appearance of labeled cells in lymph nodes of sheep compared to those of mice. These results indicate that lymphocyte extravasation in sheep proceeds via paracortical venules in lymph nodes. The function of these venules appears to be analogous to HEV in nonruminant species.     

Kinematics of whip spider pedipalps: a 3D comparative morpho-functional approach

Amblypygi are tropical and subtropical ambush predators that use elongated, raptorial pedipalps for different activities. Although pedipalp use in predation and courtship has been explored in videography in vivo analyses, kinematic ex vivo examination of these appendages has not been conducted. Here, we rectify this lack of data by using micro-CT scans to 3D-kinematically model the appendage morphology and the range of motion (ROM) of the joints for Damon medius and Heterophrynus elaphus. We illustrate the successful application of this technique to terrestrial euarthropods in determining the maximum ROM values for each pedipalp joint. We also note that, in life, these values would be lower due to motion restricting structures like tendons, arthrodial membranes, and muscles. We further compare our maximum values obtained here with data from video-based motion analyses. The ROM of each joint shows the greatest flexibility in the femur-tibia joint (140–150°), the lowest in the basitarsus-claw joint (35–40°). ROM in the tibia-basitarsus joint is markedly distinct (D. medius: 44°; H. elaphus: 105°). This disparity reflects how H. elaphus uses the joint in the capture basket, while D. medius uses the femur-tibia joint to form the capture basket. We further illustrate notable vertical motion of the H. elaphus pedipalp compared to D. medius. This difference reflects the retro-ventral trochanter apophysis of H. elaphus. Our study opens the possibility to further whip spider kinematic understanding. Examination of other taxa using this approach will result in a more comprehensive understanding of the ecological significance and ethological implications of this unique arachnid group.     

Effect of dietary daidzein on egg production, shell quality, and gene expression of ER-alpha, GH-R, and IGF-IR in shell glands of laying hens

Our previous studies demonstrated that dietary daidzein improves egg production in ducks during the late period of the laying cycle. The present study was aimed to investigate the effect of daidzein in laying hens, with more focus on eggshell quality. The expression of ER-alpha, GH-R, and IGF-IR mRNA in shell glands was determined to identify the target genes of daidzein action and to reveal the relationship between shell quality and profiles of gene expression in shell glands of laying hens. 1000 ISA hens, at 445 days of age, were allotted at random to two groups and given the basal diet with or without 10 mg of daidzein per kg diet for 9 weeks. Daidzein supplement significantly increased the egg laying rate and the feed conversion ratio. The eggshell thickness increased, while the percentage of cracked eggs decreased in daidzein-treated hens. Serum E2 and phosphate concentrations were not altered, but the level of serum Ca2+ and the tibia bone mineral density were significantly increased in the daidzein-treated group compared with their control counterparts. In parallel with the significant increase of oviduct weight, significant down-regulation of GH-R and IGF-IR mRNA and a trend of decrease in ERalpha mRNA expression in shell glands were observed in daidzein-treated hens. The results indicate that dietary daidzein improves egg laying performance and eggshell quality during the late (postpeak) laying stage of hens, which is associated with modulations in gene expression in the shell gland.     

Assessment of attenuated Salmonella vaccine strains in controlling experimental Salmonella Typhimurium infection in chickens

Salmonella hold considerable promise as vaccine delivery vectors for heterologous antigens in chickens. Such vaccines have the potential additional benefit of also controlling Salmonella infection in immunized birds. As a way of selecting attenuated strains with optimal immunogenic potential as antigen delivery vectors, this study screened 20 novel Salmonella Typhimurium vaccine strains, differing in mutations associated with delayed antigen synthesis and delayed attenuation, for their efficacy in controlling colonization by virulent Salmonella Typhimurium, as well as for their persistence in the intestine and the spleen. Marked differences were observed between strains in these characteristics, which provide the basis for selection for further study as vaccine vectors.     

Marker assisted polycross breeding to increase diversity and yield in perennial ryegrass (Lolium perenne L.)

Summary In this study, the application of molecular markers to optimise genetic diversity in a polycross breeding program of perennial ryegrass (Lolium perenne L.) was evaluated. The genetic diversity among 98 potential parental plants from three maturity groups (early, intermediate and late flowering) was investigated using amplified fragment length polymorphism (AFLP) markers. For each maturity group, two polycrosses of six parental plants with contrasting levels of genetic diversity were composed. Average genetic diversity among parents selected for narrow polycrosses was 36% lower than among parents selected for wide polycrosses. Diversity within first generation synthetic progenies (Syn1) was proportional to the diversity within the respective parental polycrosses. However, differences were less pronounced with Syn1 progenies from narrow polycrosses showing 16% reduced diversity when compared to Syn1 progenies from wide polycrosses. Multivariate analyses allowed for a clear separation of the six Syn1 progenies based on AFLP markers and demonstrated their genetic distinctness. Evaluation of dry matter yield, date of ear emergence and stem length of Syn1 and Syn2 progenies showed progenies from wide polycrosses to be constantly higher yielding when compared to progenies from narrow polycrosses. On the other hand, there was no significant difference in variability for the two morphological traits between progenies of narrow- and wide polycrosses. The results presented here provide evidence for an efficient application of molecular markers to select genetically diverse polycross parents which resulted in an average yield increase of 3.8%.     

Involvement of mammalian Mus81 in genome integrity and tumor suppression

Mus81-Eme1 endonuclease has been implicated in the rescue of stalled replication forks and the resolution of meiotic recombination intermediates in yeast. We used gene targeting to study the physiological requirements of Mus81 in mammals. Mus81-/- mice are viable and fertile, which indicates that mammalian Mus81 is not essential for recombination processes associated with meiosis. Mus81-deficient mice and cells were hypersensitive to the DNA cross-linking agent mitomycin C but not to gamma-irradiation. Remarkably, both homozygous Mus81-/- and heterozygous Mus81+/- mice exhibited a similar susceptibility to spontaneous chromosomal damage and a profound and equivalent predisposition to lymphomas and other cancers. These studies demonstrate a critical role for the proper biallelic expression of the mammalian Mus81 in the maintenance of genomic integrity and tumor suppression.