Sperm mitochondrial regulation in motility and fertility in horses

The biological nature of age‐related declines in fertility in males of any species, including stallions, has been elusive. In horses, the economic costs to the breeding industry are frequently extensive. Mitochondrial function in ejaculated sperm, which is essential for sperm motility, is reflected by adenosine triphosphate production, mitochondrial oxidative efficiency and production of reactive oxygen species, and that this balance may become compromised in ageing stallions and during the process of cryopreservation. This presentation will focus on mitochondrial integrity and function as an avenue for understanding the pathophysiology of sperm when undergoing cryopreservation and male ageing. We discuss the importance of understanding the differences and similarities of sperm mitochondria to that of somatic cells regarding structure and mitochondrial biochemistry relating to sperm function. The roles of oxidative phosphorylation and glycolysis in sperm mitochondria are outlined as is the method of determining oxygen consumption and calcium homoeostasis in sperm mitochondria. Further, we outline the role of oxidative stress and reactive oxygen species.     

All creatures great and minute: a public policy primer for companion animal zoonoses

Approximately 63% of US households have at least one pet, a large percentage of which are considered family members. Pet owners can derive substantial physical and psychological benefits from interaction with companion animals. However, pet ownership is not without risks; zoonotic diseases are increasingly drawing the attention of healthcare professionals, policy makers and the general public. While zoonoses of 'traditional' pets are widely recognized and their prevention and treatment factors are generally known, the growing popularity of 'non-traditional' pets has the potential to facilitate human exposure to novel zoonoses. However, the greatest risk of zoonoses probably arises from animals taken directly from the wild to serve as pets. Non-governmental organizations, state veterinary associations and others have been calling for increased regulation of animal imports, some proposing that all 'exotics' be banned from the pet trade. Because zoonotic diseases of companion animals are influenced by interacting factors of ecological, technical, socio-economic, and political origin, efforts to minimize their impact need be multi-dimensional, simultaneously addressing both the ecological and socio-political drivers of disease emergence and transmission. This study is intended to serve as a primer for animal care professionals seeking to engage with policy makers and the pet industry on the prevention of companion animal zoonoses. We provide background on the human-animal bond, risks of zoonoses associated with groups of companion animals, and the public policy context, as well as identify the factors needed to build a comprehensive approach to companion animal zoonoses risk management. Also included are examples of innovative, non-regulatory initiatives designed to limit the spread and impact of companion animal zoonoses, including a reptile salmonella poster, the National Reptile Improvement Plan, Habitattitude campaign, Pet Zoonoses Committee, and a wildlife disease surveillance initiative known as Project TripWire.     

Characterization of the equine platelet aggregation response.

Equine platelet aggregation responses to bovine collagen, adenosine diphosphate (ADP), serotonin, epinephrine, and arachidonate in a platelet aggregometer were recorded. Equine platelets exhibited irreversible aggregation when incubated with ADP at a final concentration of 10 microM and bovine collagen. A secondary aggregation wave was recorded from platelets from certain horses at final ADP concentrations of 1 to 5 microM. Serotonin and arachidonate induced a weak reversible aggregation response, but a response was not observed following epinephrine addition. Equine platelet aggregation was influenced by concentration of anticoagulant (sodium citrate). Platelet aggregation responses at 37 C were indistinguishable from those recorded at 39 C. Platelet aggregation responses also were altered if the aggregation tests were not performed within 4 hours of blood sample acquisition. An assessment of platelet aggregation from multiple blood samples from the same horse indicated that the procedures described provide a reliable method to assess equine platelet aggregation in vitro.     

Flocculation mechanism: charge neutralization and bridging

Electrophoresis measurements and electron-microscope observations with two model colloids and a polymeric flocculant show zeta-potential changes and details of floc structure. Fibers of the flocculant extend radially from the particle surface and vary in thickness from 20 to 300 angstroms. Both charge neutralization and bridging may function simultaneously.     

Genome-wide insertional mutagenesis of Arabidopsis thaliana

Over 225,000 independent Agrobacterium transferred DNA (T-DNA) insertion events in the genome of the reference plant Arabidopsis thaliana have been created that represent near saturation of the gene space. The precise locations were determined for more than 88,000 T-DNA insertions, which resulted in the identification of mutations in more than 21,700 of the approximately 29,454 predicted Arabidopsis genes. Genome-wide analysis of the distribution of integration events revealed the existence of a large integration site bias at both the chromosome and gene levels. Insertion mutations were identified in genes that are regulated in response to the plant hormone ethylene.     

Evasion of mercury vapor from the surface of a recently limed acid forest lake in Sweden

Mercury is emitted from soil and water surfaces, but few actual direct flux measurements have been reported. During June, 1994 we performed the first micrometeorological measurements of Hg vapor fluxes over a boreal forest lake. Using highly precise methods with multiple replicate samplers, we measured concentration gradients of Hg vapor, CO₂ and H₂O over the lake surface. Mercury was readily emitted from the lake surface, and we found no evidence of Hg dry deposition to the lake. Emission rates over the lake averaged 8.5 ng m² h^?1, and appeared to be weakly influenced by water temperature and solar radiation. These fluxes were somewhat higher than those previously measured using surface chambers at this site.     

Atmospheric concentrations and deposition of Hg to A deciduous forest atwalker branch watershed,Tennessee, USA

Aerosol and total vapor-phase Hg concentrations in air have been measured at Walker Branch Watershed, Tennessee for ≈ 2 yr. Airborne Hg at this site is dominated by vapor forms which exhibit a strong seasonal cycle, with summer maxima that correspond to elevated air temperature. Concentrations in this forest are near background levels; however, concentrations at a site within 3 km are significantly elevated due to emissions from Hg-contaminated soils. The concentration data have been combined with a recently modified dry deposition model to estimate dry deposition fluxes to the deciduous forest at Walker Branch. Weekly mean modeled V_d values for Hg° ranged from <0.01 (winter) to > 0.1 (summer) cm s¹. Weekly dry deposition fluxes ranged from <0.1 μg m⁻² during winter to > 1.0 μgg m⁻² in the summer. Our dry deposition estimates plus limited measurements of wet deposition in this area indicate that dry deposition may be the dominant input process in this forest, at least during the summer.