Cell Counts and Survival to Vitrification of Bovine In Vitro Produced Blastocysts Subjected to Sublethal High Hydrostatic Pressure

This work analyses the effects of a high hydrostatic pressure (HHP) treatment on in vitro survival of in vitro produced (IVP) bovine embryos vitrified with the Cryologic Vitrification Method (CVM). Consequences on embryo quality in terms of cell proliferation and differentiation, and levels of embryonic Heat Shock Protein 70 (Hsp‐70) were also examined. Day 7 and 8 bovine in vitro‐produced blastocysts were submitted to an HHP treatment (60 MPa, at 32°C for 1 h) and allowed to recover for 1 or 2 h in culture medium. The HHP treatment did not improve blastocyst survival rates after vitrification/warming. Survival (24 h post‐warming) and hatching (48 h post‐warming) rates were 79.3 ± 4.9 and 51.8 ± 4.2 vs 73.9 ± 4.2 and 44.7 ± 4.1 for untreated controls and HHP‐treated embryos, respectively. Total cell numbers measured in fresh embryos were reduced after 1 h at 32°C, with or without HHP treatment, indicating that cell proliferation was stopped as a result of stress. Vitrified HHP‐treated embryos that hatched at 48 h after warming showed increased cell numbers in their ICM compared with untreated controls (50.2 ± 3.1 vs 38.8 ± 2.7), indicating higher embryo quality. Treatment of blastocysts with HHP did not alter the level of the Hsp‐70 protein. In our conditions, HHP treatment did not affect the cryoresistance of these embryos. However, combination of HHP treatment and vitrification in fibreplugs resulted in an increase in the ICM cell number of hatched embryos 48 h post‐warming.     

Photoemission evidence for a remnant fermi surface and a d-wave-like dispersion in insulating Ca2CuO2Cl2

An angle-resolved photoemission study is reported on Ca2CuO2Cl2, a parent compound of high-Tc superconductors. Analysis of the electron occupation probability, n(k), from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant, even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the &cjs3539;coskxa - coskya&cjs3539; form along this remnant Fermi surface. Together with the data from Dy-doped Bi2Sr2CaCu2O8+delta, these results suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime.     

A dielectric omnidirectional reflector

A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices.     

Characterisation of genes isolated from a potato swellingstolon cDNA library

Summary In screening to isolate a full-length copy of a previously isolated cDNA clone, a further three cDNAs were also isolated from a library prepared from sub-apical swelling-stolon tissue of potato (Solanum tuberosum L.). Sequence analysis showed these clones to be similar to extensin-like protein genes, acyl carrier protein thioesterase genes and high mobility group protein genes, respectively. A further cDNA, isolated by subtractive hybridisation, was similar to a tomato cDNA previously isolated on the basis of its down-regulation following nematode infection. While all the newly isolated genes were expressed in swelling stolons, for most, maximal expression was seen to be in stem tissue. Possible roles for these genes in the development of potato plants are discussed, as is the significance of gene expression in stems and stolons to the process of tuberisation.     

In Vivo and In Vitro Sperm Interaction with Oviductal Epithelial Cells of Llama

Sperm reservoirs in South American Camelids would be crucial for successful fertilization. Since ovulation occurs approximately 36 h after mating, the maintenance of the sperm viability in the oviduct waiting for the ovum is a critical reproductive event. Our study aimed at determining whether the isthmus or the utero tubal junction (UTJ) could function as a sperm reservoir in llama by means of in vivo and in vitro experiments. For the in vivo experiments, the oviducts of adult females with a dominant follicle bigger than 7 mm were examined for the presence of sperm at 6, 18, 24, 28 and 35 h after mating. The results using scanning and transmission electron microscopy showed ultrastructural differences between isthmus and UTJ with respect to (1) predominance of secretory cells in the UTJ and ciliated cells in the isthmus epithelium and (2) cytoplasmic bulbous projection of the secretory cells in the UTJ. Sperm adhered by a mucus‐like substance were seen only in the UTJ at 6, 18, 24 and 28 h post‐mating. Lack of sperm adhered to oviductal mucosa was observed around ovulation (35 h). In vitro experiments demonstrated higher ability of UTJ epithelial cell explants with respect to isthmus explants to bind sperm in a co‐cultured system. The anatomical features and the presence of a sperm bonding agent in the UTJ together with the in vitro differential binding of sperm to UTJ explants strongly suggest that both may be feasible mechanisms that facilitate sperm storage in this oviductal region in llama.     

Genotypic diversity and migration of clonal lineages of Botrytis cinerea from chickpea fields of Bangladesh inferred by microsatellite markers

An analysis of allelic diversity at nine microsatellite loci provided an insight into the population structure of Botrytis cinerea from four fields (sampled in 2003 and 2004) that represented important regional locations for chickpea production in Bangladesh. Although three populations were limited by sample size after clone‐correction, a total of 51 alleles were amplified among 146 B. cinerea isolates from Bangladesh, which revealed a high amount of within‐population and overall genetic diversity (H_S = 0·48 and H_T = 0·54, respectively). The percentage of maximal genotypic diversity (G) ranged between populations (G = 23–40), with a total of 69 haplotypes detected (G = 25). Bayesian cluster analysis depicted two major clusters distributed among the four Bangladesh populations, indicating population admixture from two origins that have spread throughout these regions. Genotype flow between regions was detected and indicated the spread of clonal lineages, consistent with relatively low differentiation among the four populations (mean G_ST = 0·1, P < 0·05). These results highlighted the potential threat of host resistance breakdown as a result of considerable genetic diversity, genotype flow and the evolutionary potential of B. cinerea.     

Comparative evaluation of impulse oscillometry and a monofrequency forced oscillation technique in clinically healthy calves undergoing bronchochallenges

Multifrequency impulse oscillometry ( ) was compared with a monofrequency forced oscillation technique ( ) in calves undergoing experimentally induced bronchoconstriction and subsequent bronchodilatation. The dynamic lung compliance (Cdyn) was also measured by conventional methods. For each test, the baseline mean and the responses to saline, a bronchoconstrictive agent (carbachol) and a bronchodilator (fenoterolhydrobromide) were calculated. Using the 1os, the information was markedly frequency-dependent. The resistance (R) and the magnitude of respiratory impedance (Z) were only sensitive at 5 Hz, leading to negative frequency dependence of these parameters as an indicator of peripheral airway obstruction. A high sensitivity for reactance (X) and phase angle (0) values was observed between 5 and 20 Hz. For MFO (10 Hz), the parameters Ros (which includes resistive and capacitive components of the respiratory system), phase shift (psi), and the oscillatory derived compliance of the respiratory system (Crs) were of the greatest clinical potential. Crs showed a significant coefficient of linear correlation (r=0.88, P<0·001) with Cdyn. At the 10 Hz test frequency similar results were observed with MFO and 105, suggesting that for healthy calves the measurement effect of an impulse is not significant. With respect to peripheral airway calibre, a test frequency less than 10 Hz appeared to be most sensitive and least variable.     

Practices of cattle keepers of southwest Nigeria in relation to bovine trypanosomosis

Tropical Animal Health and Production - Significant increases in human and livestock populations coupled with agricultural practices have changed the socioeconomic perspectives of livestock...