In vitro Evaluation of in vivo Fertilizing Ability of Frozen Rabbit Semen

The present work studied different spermatozoa parameters and the ability of frozen rabbit spermatozoa to fertilize, in vitro, in vivo‐matured oocytes, as a test to predict their in vivo fertility and prolificacy. Semen from rabbit bucks was frozen using two freezing protocols [in a freezer at ?30°C or in liquid nitrogen vapour (LNV)]. For the in vivo trial, females were inseminated with frozen‐thawed spermatozoa. Oocytes used for in vitro testing were recovered 14 h after ovulation induction from donors and co‐incubated with 2 × 10⁶ frozen‐thawed spermatozoa during 4 h at 37°C in Tyrode's medium under an atmosphere of 5% CO₂ in air with maximal humidity. After co‐incubation period, presumptive zygotes were cultured in TCM199 supplemented with 20% foetal bovine serum (FBS), under the same conditions described above. Although no statistical differences were observed between freezing protocols in seminal parameters [motility rate: 40 and 35%, VCL: 35 and 46 μm/s, amplitude of lateral head displacement (ALH): 1.7 and 2.4 μm, for semen frozen at ?30°C and in LNV, respectively], significant differences were noted in the fertilizing ability in vivo and in vitro. Semen frozen at ?30°C showed the highest fertilizing ability in vitro (26.7% vs 6.2 and 8.7% for semen frozen at ?30°C, in LNV and fresh semen, respectively) and the lowest fertility rate in vivo (21.7% vs 64.2% and 70.6% for semen frozen at ?30°C, in LNV and fresh semen, respectively). Sperm frozen at ?30°C seemed to be more capacitated.     

Formation of kafirin microparticles by phase separation from an organic acid and their characterisation

Protein microparticles (microspheres) have numerous food and pharmaceutical applications. However, generally preparation of prolamin protein microparticles involves aqueous ethanol as a solvent. An ethanol-free method of making microparticles from kafirin with a novel structure was devised. Glacial acetic acid or other organic acids were used as kafirin solvent and the microparticles formed by phase separation on addition of water. The kafirin microparticles were characterised by light microscopy, scanning electron microscopy and transmission electron microscopy and their size distribution was measured. The kafirin microparticles prepared by phase separation from organic acid were spherical or irregular shaped, between 1 and 10 μm in diameter, with rough, porous outer surfaces and many internal holes or vacuoles. The holes seem to be the footprint of air bubbles which were entrapped during microparticle preparation. With an increase in the final concentration of acetic acid, the structure of the microparticles changed from porous spheres to an open matrix, with a concomitant change in kafirin secondary structure from α-helical to β-sheet, indicative of protein aggregation. These highly vacuolated and open matrix type microparticles appear to have potential as encapsulating agents and support structures.     

Spitzer spectral observations of the deep impact ejecta

Spitzer Space Telescope imaging spectrometer observations of comet 9P/Tempel 1 during the Deep Impact encounter returned detailed, highly structured, 5- to 35-micrometer spectra of the ejecta. Emission signatures due to amorphous and crystalline silicates, amorphous carbon, carbonates, phyllosilicates, polycyclic aromatic hydrocarbons, water gas and ice, and sulfides were found. Good agreement is seen between the ejecta spectra and the material emitted from comet C/1995 O1 (Hale-Bopp) and the circumstellar material around the young stellar object HD100546. The atomic abundance of the observed material is consistent with solar and C1 chondritic abundances, and the dust-to-gas ratio was determined to be greater than or equal to 1.3. The presence of the observed mix of materials requires efficient methods of annealing amorphous silicates and mixing of high- and low-temperature phases over large distances in the early protosolar nebula.     

Alteration of kafirin and kafirin film structure by heating with microwave energy and tannin complexation

Heating with microwave energy and tannin complexation of kafirin both increase the tensile strength of cast kafirin bioplastic films. The effects of these treatments on the molecular structure of kafirin and of kafirin in the film were investigated. SDS-PAGE of heated wet kafirin showed an increase in kafirin oligomers. Disulfide groups increased in heated kafirin and in films made from the heated kafirin. Fourier transform infrared (FTIR) spectroscopy of heated kafirin and films made from the heated kafirin indicated an increase in beta-sheet conformation. In contrast, kafirin complexation with tannic acid (TA) and sorghum condensed tannin (SCT) resulted in a slight decrease in beta-sheet conformation in the kafirin and a larger decrease in the kafirin in the films. Raman spectroscopy showed that, with TA, there was a shift in peak from 1710 to 1728 cm(-1) for kafirin-tannic acid complexes, indicating kafirin and tannic acid interaction. The protein conformational changes presumably facilitated cross-linking between kafirin molecules and/or between kafirin and the tannins. Thus, although both heating with microwave energy and tannin complexation cause cross-linking of kafirin to increase film tensile strength, their effects on kafirin structure appear to be different.     

Plasticization of a protein-based film by glycerol: a spectroscopic, mechanical, and thermal study

Kafirin, the seed storage protein of the cereal sorghum, is highly homologous with the maize storage protein zein. The effects of plasticisation of a kafirin film by glycerol in the absence of water were examined by a combination of spectroscopic (NMR and infrared), rheological, and calorimetric methods. The results suggest that at low glycerol levels the glycerol is absorbed onto and possibly into the protein. Increasing the level of glycerol increases the motion of the protein and changes the protein conformation. There are corresponding changes of the mechanical properties of protein films. At 40% (w/w) of glycerol, two glass transition temperatures were observed, one of which corresponded to the glass transition temperature of pure glycerol. This result indicates that at this level of plasticizer there are sufficient glycerol/glycerol interactions occurring to allow a separate glass formation process for glycerol.     

Knowledge and attitudes of Australian livestock producers concerning biosecurity practices

Biosecurity risks are a major threat to the profitability of the industry as well as impacting human and animal health. Livestock producers play a crucial role in biosecurity as the first to notice changes in the health or productivity of their stock and are generally responsible for implementing protective measures. However, uptake of biosecurity measures by producers is variable. We critically appraised the current literature regarding biosecurity practices in Australian livestock industries and highlight aspects that are well understood as well as those where further research or information is needed. Findings from 12 cross-sectional studies suggest that Australian producers' knowledge of biosecurity methods and importance might have a positive influence on their willingness to implement or incorporate biosecurity practices. There is moderate evidence supportive of biosecurity being well understood by livestock producers across Australia. Barriers to producers using biosecurity practices included lack of information or communication from agricultural, veterinary or government organisations. It was found that larger stock numbers were positively correlated with biosecurity implementation and that producers used veterinarians, government and industry agencies as resources for trusted information.