Functional Activity of Frozen Thawed Chinchilla lanigera Spermatozoa Cryopreserved with Glycerol or Ethylene Glycol

The cryopreservation of spermatozoa constitutes a valuable tool for the captive breeding management of valuable and/or threatened species. Chinchilla lanigera is a species almost extinct in the wild, and the domestic counterpart has one of the most valuable pelts in the world. The objectives of this study were to: (i) compare the functional activity of post‐thawed chinchilla spermatozoa cryopreserved at ?196°C either with glycerol (G) or ethylene glycol (EG) as cryoprotectants (1 m final concentration) and (ii) investigate the effects of incubating the gametes for 4 h in the presence or in the absence of the cryoprotectants; evaluations were performed taking into account motility, viability, response to hypo‐osmotic shock and acrosome integrity of the cells. Parameters reflecting post‐thaw (0 h) sperm functional activity were significantly lower than those of freshly ejaculated gametes. When comparing the cryoprotectant efficiency of G vs EG, neither cryoprotectant agent offered appreciable advantages. After 4 h of incubation, in the presence or absence of the cryoprotectant agent, a rapid and significant decrease was found in all functional parameters and remained at ～ 20–30% motile, viable and viable acrosome intact cells. Viability was significantly lower when the cryoprotectant was removed from the media (possibly due to the centrifugation process). With respect to the maintenance of sperm membrane integrity, only ～ 10% of cells showed membrane resistance to hypo‐osmotic conditions after the 4 h incubation period. These results constitute new insights for cryopreservation protocols and the development of assisted reproductive techniques in this species.     

Ostertagiasis in calves. I. The effect of control measures on infection levels and body weight gains during the grazing season in Denmark

The investigation was designed to study the gastro-intestinal helminth infection established in yearling calves with reference to fluctuations in the larval contamination of the herbage during the grazing season. In a 2 × 3 factor experiment, comprising six groups, each of six calves, a comparison was made between infection levels, growth rates etc. in calves grazing the same paddock over an entire season and calves moved before the July rise in herbage contamination to paddocks not grazed earlier in the same season. A comparison was also made between animals receiving no anthelminthic treatment, animals treated 3 weeks after the start of the grazing season and again when moved, and animals treated every 3 weeks during the season.Before July there were no weight gain differences between the various groups of calves. During the rest of the season, the calves which were moved gained 647–869 g, while those that remained on the same paddock, and were exposed to a high level of larval contamination gained only 81–361 g per day. The effect of anthelmintic treatment was less pronounced, though significant. The weight gains were correlated to a high degree with the larval contamination levels of the respective paddocks (r = ? 0.79) as well as with the serum pepsinogen (r = ? 0.75) and albumin levels (r = 0.75) of the calves and to a minor degree also with faecal egg counts (r = ? 0.45). The observed weight gain differences could not be accounted for by differences in grass quantity or quality.     

Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films

Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.     

Induced responses to herbivory and increased plant performance

Plant resistance to herbivores was induced in a field experiment to evaluate the consequences of induced responses for subsequent herbivory and plant fitness. Induction early in the season resulted in halving of herbivory by chewing herbivores and a reduction in the abundance of phloem-feeding aphids when compared with controls. A correlate of lifetime plant fitness, seed mass, was enhanced by over 60 percent for individuals that were induced.