Aspartic Proteinase Members Secreted by the Ruminant Placenta: Specificity of Three Radioimmunoassay Systems for the Measurement of Pregnancy-associated Glycoproteins

Pregnancy‐associated glycoproteins (PAGs) isolated from the placenta of various ruminant species are enzymatically inactive members of the aspartic proteinase family. The measurement of these proteins in the maternal blood can be a good indicator of the presence of a live embryo. As certain aspartic proteinases are present in biological fluids in physiological and pathological conditions at various concentrations, it was necessary to determine the specificity of three radioimmunoassay (RIA) systems currently used for the detection of PAG molecules. Commercially available members of the aspartic proteinase family like pepsinogen, pepsin, chymosin, rennet, cathepsin D and renin were tested in a wide concentration range (10 ng/ml – 1 mg/ml). Pepsinogen cross‐reacted in RIA 1, RIA 2 and RIA 3 over 1 mg/ml, 50 μg/ml and 500 μg/ml concentrations, respectively. In the presence of pepsin, cross‐reaction was observed in RIA 1, RIA 2 and RIA 3 over 1 mg/ml, 500 μg/ml and 1 mg/ml concentrations, respectively. Chymosin and rennet could cross‐react in RIA 2 and RIA 3, while renin and cathepsin D did not decrease the binding of the tracer to antisera more, than that of the minimal detection limit. As the plasma/serum concentrations of the examined aspartic proteinases reported in the literature were outside the concentration range where cross‐reaction was observed, it can be concluded that these RIA systems were specific for the detection of PAGs in biological fluids.     

Generation of spatially coherent light at extreme ultraviolet wavelengths

We present spatial coherence measurements of extreme ultraviolet (EUV) light generated through the process of high-harmonic up-conversion of a femtosecond laser. With a phase-matched hollow-fiber geometry, the generated beam was found to exhibit essentially full spatial coherence. The coherence of this laser-like EUV source was shown by recording Gabor holograms of small objects. This work demonstrates the capability to perform EUV holography with a tabletop experimental setup. Such an EUV source, with low divergence and high spatial coherence, can be used for experiments involving high-precision metrology, inspection of optical components for EUV lithography, and microscopy and holography with nanometer resolution. Furthermore, the short time duration of the EUV radiation (a few femtoseconds) will enable EUV microscopy and holography to be performed with ultrahigh time resolution.     

Single-cycle nonlinear optics

Nonlinear optics plays a central role in the advancement of optical science and laser-based technologies. We report on the confinement of the nonlinear interaction of light with matter to a single wave cycle and demonstrate its utility for time-resolved and strong-field science. The electric field of 3.3-femtosecond, 0.72-micron laser pulses with a controlled and measured waveform ionizes atoms near the crests of the central wave cycle, with ionization being virtually switched off outside this interval. Isolated sub-100-attosecond pulses of extreme ultraviolet light (photon energy approximately 80 electron volts), containing approximately 0.5 nanojoule of energy, emerge from the interaction with a conversion efficiency of approximately 10(-6). These tools enable the study of the precision control of electron motion with light fields and electron-electron interactions with a resolution approaching the atomic unit of time ( approximately 24 attoseconds).     

Serotypes and analysis of distribution of Shiga toxin producing Escherichia coli from cattle and sheep in the lower North Island, New Zealand

AIMS: To serotype a subset of Shiga toxin-producing Escherichia coli (STEC) isolates from cattle and sheep to determine whether any corresponding serotypes have been implicated in human diarrhoeal disease, both in New Zealand and worldwide, and to examine the distribution of STEC and enteropathogenic Escherichia coli (EPEC) amongst cattle (calves, heifers and dairy) and sheep (lambs, rams and ewes), to assess whether carriage of identified bacterial genotypes may be associated with a particular age of animal. METHODS: Recto-anal mucosal swabs (RAMS) were taken from 91 calves, 24 heifers and 72 dairy cattle, and 46 lambs, 50 ewes and 36 rams, from four sites in the Manawatu and Rangitikei regions of New Zealand. Strains of E. coli selected from primary isolation plates were subjected to a multiplex polymerase chain reaction (PCR), to determine the presence of Shiga toxin genes (stx1 and stx2) and the E. coli attaching and effacing gene (eae). RESULTS: Overall, 186/319 (58.3%) animals sampled were positive for stx1, stx2, or eae isolates. More sheep (43.9%) were stx1-positive than cattle (2.7%; p = 0.036), and amongst sheep more lambs and ewes were stx1-positive than rams (p = 0.036). Amongst cattle, more calves and heifers were eae-positive than dairy cows (p = 0.030). Two or more different STEC were isolated from at least 28 (9%) animals (three cattle and 25 sheep), based on their stx/eae genotype. Enterohaemolysin genes were found in 39/51 (76%) isolates serotyped. Twenty-one different serotypes were detected, including O5:H-, O9:H51, O26:H11, O84:H-/H2 and O149:H8 from cattle, and O26:H11, O65:H-, O75:H8, O84:H-, O91:H-, O128:H2 and O174:H8 from sheep; O84:H-, O26:H11, O5:H-, O91:H- and O128:H2 serotypes have been associated with human disease. CONCLUSIONS: If nationally representative, this study confirms that cattle and sheep in New Zealand may be a major reservoir of STEC serotypes that have been recognised as causative agents of diarrhoeal disease in humans. Distribution of STEC and EPEC in cattle and sheep indicates that direct contact with, in particular, calves or their faeces, or exposure to environments cross contaminated with ruminant faeces, may represent an increased risk factor for human disease in New Zealand.     

Reduction in the mRNA expression of sVEGFR1 and sVEGFR2 is associated with the selection of dominant follicle in cows

The vascular endothelial growth factor (VEGF) is essential for follicular development by promoting follicular angiogenesis, as well as for the proliferation and survival of granulosa cells. The biological effects of VEGF are regulated by two membrane receptors, VEGFR1 and VEGFR2, and two soluble receptors, sVEGFR1 and sVEGFR2, which play an antagonistic role. Thus, the objective of this study was to identify the mRNA expression pattern of total VEGF, VEGFR1, VEGFR2, sVEGFR1 and sVEGFR2 in bovine preselected follicles (PRF) and post‐selected follicles (POF). The mRNA expression of these five genes in both granulosa cells (GC) and theca cells (TC) was compared between follicles classified as PRF and POF based on their diameter and on their ratio of estradiol/progesterone (E2/P4). Results showed a lower expression of mRNA of sVEGFR1 and sVEGFR2 in POF than in PRF (p < .05). Regarding the mRNA expression of total VEGF, VEGFR1 and VEGFR2, there was no difference between POF and PRF follicles (p > .05). Our results showed that the mRNA expression of VEGFR2 and sVEGFR1 was more abundant than the expression of VEGFR1 and sVEGFR2, while GC was the main source of mRNA for total VEGF. On the other hand, TC was the follicular compartment where the receptors were most expressed. Our results suggest that non‐dominant follicles maintain a greater concentration of the mRNA expression of both membrane and soluble VEGF receptors. On the other hand, follicular dominance is related to a reduction in the mRNA expression of sVEGFR1 and sVEGFR2, which may favour VEGF binding with VEGFR2 and, hence, improve the follicular health and development.     

Potential application of baited remote underwater video to survey abundance of west coast rock lobster Jasus lalandii

The first assessment of the baited remote underwater video system (BRUVs) for monitoring rock lobster Jasus lalandii (Milne‐Edwards) in South Africa was compared to annual ring net and trap survey data. Count data from 58 BRUVs, 36 ring net and 95 trap samples were fitted with generalised additive models using depth, habitat, time and spatial gradient as independent variables. A power analysis was used to determine the number of samples needed per annum to detect a 5 and 10% increase and decrease in population size. The BRUVs outperformed the nets and traps in terms of sampling effort and were better at detecting changes in abundance of lobster than abundance of three fish species. Considering factors such as cost, analysis time, additional data and environmental impact, traps are the most feasible method in deeper waters but BRUVs could replace nets and traps in depths less than 60 m, low‐density areas and marine reserves.     

AN EXPERIMENTAL SILO UNIT FOR THE CONTINUOUS MEASUREMENT OF LOSSES OCCURRING DURING ENSILAGE

An experimental silo unit consisting of four silos, each capable of holding 1000 kg. fresh grass, is described. The silos are suspended from a weighing apparatus enabling weight recordings to be taken at all stages during ensilage. The weighing apparatus is sufficiently sensitive to record a change in weight in the silo and contents of 100 grams.     

The prevalence of Shiga toxin-producing Escherichia coli in cattle and sheep in the lower North Island, New Zealand

AIM: To genotype Escherichia coli cultured from the faeces of healthy cattle and sheep in the lower North Island, in order to investigate the possible role of ruminants as a reservoir for Shiga toxin-producing E. coli (STEC) in New Zealand. METHODS: A total of 952 strains of E. coli were isolated on selective media, from faecal swabs from 319 animals (187 cattle and 132 sheep) from four sites in the Manawatu and Rangitikei regions of New Zealand. A multiplex polymerase chain reaction (PCR) was used to genotype the E. coli isolates, using amplification of Shiga toxin genes (stx1 and stx2) and the E. coli attaching and effacing gene (eae). RESULTS: Isolates of E. coli were cultured from swabs from 178/187 (95.2%) cattle and all 132 (100%) sheep. Ninety-nine (10.4%) of the isolates were stx1 only, 83 (8.7%) stx2 only, 33 (3.5%) stx1 and stx2, 23 (2.4%) stx1 and eae, one (0.1%) stx2 and eae, and 115 (12.1%) were eae only. Overall, 51 (27.3%) cattle and 87 (65.9%) sheep were stx-positive, whereas 69 (36.9%) cattle and 36 (27.3%) sheep were eae-positive. CONCLUSIONS: Both healthy cattle and sheep are asymptomatic reservoirs of STEC in New Zealand. Direct contact with cattle and sheep or consumption of water or foodstuffs contaminated with cattle of sheep faeces may represent a significant source of infection for humans.     

In vitro Development of Buffalo Oocytes in Media-containing Fluids from Different Size Class Follicles

Studies were conducted to investigate the effect of supplementation of fluid from different sized class [small (SFF, < 3 mm), medium (MFF, 3-8 mm) and large (LFF, > 8 mm)] of normal and cystic (CFF) ovarian follicles in oocyte culture media on oocyte maturation rate and embryo development in vitro and to test the efficacy of follicular fluid (FF) from different size classes as a whole oocyte maturation medium. Results suggested that FF were capable of developing buffalo oocytes to embryonic stage in vitro although its efficacy was lower than that of serum. Regardless of high maturation rates after in vitro maturation (IVM) in media containing FF or IVM in whole FF, low blastocyst rates were obtained after in vitro fertilization (IVF) and culture of embryos. Follicular fluid from small follicles had significantly (p < 0.05) higher potential of developing buffalo oocytes to embryonic stage in vitro than that from medium and large follicles. Cystic FF was not capable of supporting development of buffalo oocytes in vitro.