Diffusing-Wave Spectroscopy of Dynamics in a Three-Dimensional Granular Flow

Diffusing-wave spectroscopy was used to measure the microscopic dynamics of grains in the interior of a three-dimensional flow of sand. The correlation functions show that minutely separated grains fly from collision to collision with large random velocities. On a time scale 10(3) to 10(4) times longer than the average time between collisions, the grains displayed slow, collective rearrangements, which, at the long-time limit, produced diffusive dynamics.     

Freezing equine semen: the effect of combinations of semen extenders and glycerol on post-thaw motility

Objective   We evaluated combinations of two commercial semen extenders and three concentrations of glycerol to determine the combination that yielded the highest post-thaw sperm motility.
Design   A randomised 2 × 3 block design was used.
Procedure   Semen was collected from four stallions (6 collections per stallion). The sample was diluted with either a dried skim-milk glucose extender (EZ Mixin Original Formula) or a chemically defined, milk-free diluent (INRA 96), and each was used in combination with 2%, 3% or 4% glycerol in standard commercial freezing medium. Sperm motility was assessed by microscopy in fresh and post-thaw semen.
Results   There was a significant difference between the two extenders in the motility of spermatozoa after cryopreservation (48.9% for INRA 96; 38.6% for EZ Mixin OF; P < 0.0001). Glycerol at 4% in freezing medium yielded the highest post-thaw motility, significantly better than 2% ( P < 0.05). Three of four stallions had significantly higher post-thaw motility using INRA 96 relative to EZ Mixin OF ( P < 0.01), and two of four stallions had significantly higher post-thaw motility using 4% glycerol ( P < 0.05). The combination of INRA 96 and 4% glycerol in freezing medium gave the highest average post-thaw motility of 51.5%.
Conclusion   In this study, INRA 96 combined with 4% glycerol yielded an average recovery of progressively motile sperm consistently above the 35% target.     

Identification of differentially expressed genes in ileum, intestinal lymph node and peripheral blood mononuclear cells of sheep infected with Mycobacterium avium subsp. paratuberculosis using differential display polymerase chain reaction

Discovery of differentially expressed genes aids in understanding molecular mechanisms underpinning normal and pathological states. When studying animals such as sheep where the entire genome has not been characterized, techniques that do not require knowledge of gene sequences are particularly advantageous. We used one such technique, differential display polymerase chain reaction (DD-PCR), to identify genes that had different degrees of expression in response to Mycobacterium avium subsp. paratuberculosis (M. ptb), the organism that causes Johne's disease in ruminants. Differentially expressed genes were validated by quantitative PCR using especially selected reference genes established in this study. Sheep (n = 47) were classified according to history of exposure to M. ptb and infection status by histology and faecal and tissue culture. Differences in levels of gene expression were analyzed using restricted maximum likelihood (REML) in a linear mixed model. Five genes from the ileum and 17 genes from lymph node were differentially expressed in ovine Johne's disease. Expression of seven of these genes was also significantly different in peripheral blood mononuclear cells. Genes identified in association with M. ptb infection had a wide range of functions in pathways including: antigen presentation, signal transduction and cell differentiation, TLR signaling, immune cell activation and chemokine functions, granulomatous inflammation, Th1 suppression and apoptosis.     

Discrimination between Icelandic cod (Gadus morhua L.) populations from adjacent spawning areas based on otolith growth and shape

Studies on Atlantic cod (Gadus morhua L.) have demonstrated extensive variation in life history characteristics among populations exposed to different environmental conditions. In Iceland, cod sampled from adjacent spawning areas, within the main spawning area at the southwest coast, exhibit variation in vital life history characteristics. In this study, we investigated the stock structure of Icelandic cod on the main spawning grounds to discriminate between these adjacent spawning groups by using otolith growth and shape. Otolith growth was based on annual increment width estimated for the major age groups (6–7 year olds) of the spawning stock. Otolith shape was determined using Fourier analysis and compared among cod sampled from the different spawning areas with stepwise canonical discriminant analysis (CDA). We found significant differences in growth and otolith shape between adjacent spawning groups of cod where those sampled close to the coast differed from those that were sampled further out on the bank and continental shelf. Our results suggest that these cod may belong to different populations and the large and fast growing cod spawning in the coastal area may need special protection given their significance to the overall productivity of the stock.