Heritability and impact of environmental effects during pregnancy on antral follicle count in cattle

Previous studies have documented that ovarian antral follicle count (AFC) is positively correlated with number of healthy follicles and oocytes in ovaries (ovarian reserve), as well as ovarian function and fertility in cattle. However, environmental factors (e.g., nutrition, steroids) during pregnancy in cattle and sheep can reduce AFC in offspring. The role that genetic and environmental factors play in influencing the variability in AFC and, correspondingly, the size of the ovarian reserve, ovarian function, and fertility, are, however, poorly understood. The present study tests the hypothesis that variability in AFC in offspring is influenced not only by genetic merit but also by the dam age and lactation status (lactating cows vs. nonlactating heifers) and milk production during pregnancy. Antral follicle count was assessed by ultrasonography in 445 Irish Holstein-Friesian dairy cows and 522 US Holstein-Friesian dairy heifers. Heritability estimates for AFC (± standard error) were 0.31 ± 0.14 and 0.25 ± 0.13 in dairy cows and heifers, respectively. Association analysis between both genotypic sire data and phenotypic dam data with AFC in their daughters was performed using regression and generalized linear models. Antral follicle count was negatively associated with genetic merit for milk fat concentration. Also, AFC was greater in offspring of dams that were lactating (n = 255) compared with nonlactating dams (n = 89) during pregnancy and was positively associated with dam milk fat concentration and milk fat-to-protein ratio. In conclusion, AFC in dairy cattle is a moderately heritable genetic trait affected by age or lactation status and milk quality but not by level of dam’s milk production during pregnancy.     

Effects of pork collagen on thermal and viscoelastic properties of purified porcine myofibrillar protein gels

The objectives of this study were to examine the thermal, water-binding and viscoelastic properties of mixed protein systems containing purified myofibrils from porcine semimembranosus (MP) and pork collagen (PC) during gelation and subsequent cooling. MP:PC mixtures (100:0, 90:10, 80:20, 70:30, 60:40, 50:50) normalized to 4% protein were evaluated. No significant differences in thermal characteristics of these mixtures could be detected using differential scanning calorimetry. A primary peak was observed near 66?°C. Using small-strain oscillatory testing, the rheological properties during gelling and cooling were quantified. Storage modulus (G') increased upon heating for all treatments, but the rate of gel firming and the G' value at 85?°C were significantly lower (P<0.05) as PC was added to the mixed protein system. Upon cooling, gels revealed a significantly lower (P<0.05) rate of gel firming and significantly lower (P<0.05) G' value at 5?°C in samples with 20% inclusion of PC and higher. Addition of PC yielded a significant linear (R(2)=0.65; P<0.01) increase in the water-holding capacity (WHC) of the gels, indicating that the matrix formed in MP:PC gels had a greater ability to entrap water than that of the control MP gels. The inclusion of 10% PC resulted in gels with significantly higher (P<0.05) WHC and similar firmness when compared with gels comprised of MP as the only protein source.     

Rate and extent of pH decline affect proteolysis of cytoskeletal proteins and water-holding capacity in pork

The objective of this study was to determine the extent to which early postmortem (PM) pH decline influences proteolysis of the intermediate filament protein desmin, the costameric proteins vinculin and talin and autolysis of μ-calpain in the longissimus muscle (LM) of pigs from two genetic lines. Based on the LM 3 h pH (H = 3 h pH of LM > 6.0; L = 3 h pH of LM pH < 5.7) PM, 10 carcasses per line and pH group were selected. The average 3 h pH within pH group was 6.23 (H) and 5.44 (L). The LM samples were collected 24, 48, 72, and 120 h PM and percent drip loss was measured after 1, 2, and 4 d of storage. Samples collected at 24, 48, 72, and 120 h PM were used to monitor desmin, vinculin, and talin degradation and samples collected at 24 h PM were used to determine the extent of μ-calpain autolysis by immunoblotting. Higher (P < 0.01) pH values at 45 min, 6 h, and 24 h PM and lower (P < 0.01) drip losses after 1, 2, and 4 d of storage were recorded in the H-compared to the L-group. Abundance of the 76 kDa μ-calpain autolysis product was greater (P < 0.01), proteolysis of talin at all measured time points and proteolysis of desmin after 24 and 48 h PM was greater (P ? 0.03) in the H-group than in the L-group. The current findings indicate activation rate of μ-calpain may be associated with proteolysis of desmin and talin and could play a role in the development of drip loss. The rate of early PM pH decline can partly explain the variation of desmin and talin degradation by affecting the activation of μ-calpain.     

Sintering Mechanisms and Kinetics for Reaction Hot‐Pressed ZrB2

Sintering mechanisms and kinetics were investigated for ZrB₂ ceramics produced using reaction hot pressing. Specimens were sintered at temperatures ranging from 1800°C to 2100°C for times up to 120 min. ZrB₂ was the primary phase, although trace amounts of ZrO₂ and C were also detected. Below 2000°C, the densification mechanism was grain‐boundary diffusion with an activation energy of 241 ± 41 kJ/mol. At higher temperatures, the densification mechanism was lattice diffusion with an activation energy of 695 ± 62 kJ/mol. Grain growth exponents were determined to be ~4.5, which indicated that a grain pinning mechanism was active in both temperature regimes. The diffusion coefficients for grain growth were 1.5 × 10^?16 cm⁴/s at 1900°C and 2.1 × 10^?15 cm⁴/s at 2100°C. This study revealed that dense ZrB₂ ceramics can be produced by reactive hot pressing in shorter times and at lower temperatures than conventional hot pressing of commercial powders.     

Dimethylsulfoxide elevates extracellular laccase (phenol oxidase) activity of Pycnoporus cinnabarinus grown on a low nutritional newspaper medium

The white‐rot fungus Pycnoporus cinnabarinus, grown on a low nutrient newspaper medium, secreted low amounts of extracellular laccase. The laccase activity was increased when 3% methanol was added to the medium and further increased when 3% dimethylsulfoxide was added. Dimethylsulfoxide increased the enzyme activity over controls when the fungus was grown on a malt extract broth, or media containing either recycled Kraft paper or cellobiose. Treatment with the ionophore A23187 suggested that dimethylsulfoxide acted as a paramorphogen to increase the branch points of the mycelial mat. Hence, the number of ion channels for secretion of the enzyme was increased. When the fungus was grown in a 2 dm³ bioreactor, sparged with air, the measured extracellular protein concentration rose and remained relatively steady for 15 days. The enzyme activity and specific activity reached a maximum between days 6 and 9 and then fell from day 10 of fermentation. The presence of dimethylsulfoxide in the bioreactor caused a four‐fold increase in enzyme activity and prolonged its secretion in the bioreactor for at least 25 days. The protein concentration and specific activity also remained at high levels over this period. © 2001 Society of Chemical Industry     

An automated multi‐unit composting facility for biodegradability evaluations

A system has been developed for studying the biodegradation of natural and synthetic polymeric material. The system is based on standard methods developed by the European Committee for Standardisation (CEN TC 261) (ISO/DIS 14855) and the American Society of Testing Materials, ‘ASTM Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials under Controlled Composting Conditions’ (ASTM D 5338‐92). A new low‐cost compost facility has been used which satisfies the requirements of these standards. The system has been automated for data collection and has been run under the conditions specified by the standards. In the system, cellulose, newspaper and two starch‐based polymers were treated with compost in a series of 3 dm³ vessels at 52 °C and under conditions of optimum moisture and pH. The degradation was followed over time by measuring the amount of carbon released as carbon dioxide. © 2001 Society of Chemical Industry     

Nephrogenic rests, nephroblastomatosis, and associated lesions of the kidney

The fetal kidney is formed by the development of nephrons from fetal metanephric blastema surrounding the ureteric bud. The fetal renal tissue matures into normal renal parenchyma during gestation, but, occasionally, fetal tissue persists into infancy as microscopic foci called nephrogenic rests. Nephrogenic rests are found in approximately 1% of infant kidneys at autopsy. Nephrogenic rests are associated with an increased risk of Wilms tumor, and it is theorized that nephrogenic rests undergo neoplastic change into Wilms tumor. Fortunately, this transformation occurs in less than 1% of young children with nephrogenic rests. Nephrogenic rests are associated with many syndromes, including Beckwith-Wiedemann syndrome, hemihypertrophy, and sporadic aniridia. Children with identifiable syndromes, once diagnosed, should be screened for the development of Wilms tumor. Nephrogenic rests are associated with other lesions such as multilocular cystic nephroma and multicystic dysplasia, usually without malignant complications.