Effective,appropriate and simple culture,egg hatching and cryopreserving of the nematode Cheilospirura hamulosa

1. Successful invasion by nematode parasites is associated with several factors including egg hatching at the right time in their hosts. To determine a simple and appropriate medium for culture and egg hatching of the highly pathogenic species of the Acuariidae family, Cheilospirura hamulosa were cultured in three different media. In addition the viability of C. hamulosa eggs was determined after storage in frozen infected gizzards.

2. Eggs removed from the uteri of the female worms in infected gizzards were pooled and washed in distilled water and screened under a stereo dissecting microscope. Eggs were counted and cultured in three different media, nutrient agar, normal saline 0.9% and Bearman, at room temperature. Additionally, 10 infected gizzards were kept at ?20°C for 2 and 8 months.

3. After 4–5 d there had been no growth in the nutrient agar medium, whereas 11% of the cultured eggs in the Bearman medium contained larvae 2–3 d after culturing. In 0.9% normal saline medium the two polar knobs appeared on the two poles of the eggs at 2 d post cultivation, and 74% of the eggs contained a larva on the third day. Mature larvae gradually exited from the eggs.

4. Eggs collected from female worms in gizzards frozen at ?20°C were cultured in the same three culture media at room temperature. Larvae were visible in the eggs after 2–3 d in the Bearman and 0.9% normal saline media and hatched thereafter.

5. The 0.9% normal saline medium is recommended for egg hatching and cultivation of C. hamulosa due for simplicity, efficacy and cost effectiveness. Moreover, freezing of the infected gizzards at ?20°C is proposed for long-term storage of the eggs.     

Genetic variability of tolerance to Verticillium albo-atrum and Verticillium dahliae in Medicago truncatula

Verticillium wilt caused by Verticillium albo-atrum and Verticillium dahliae is responsible for yield losses in many economically important crops. The capacity of pathogenic fungi to adapt to new hosts is a well-known threat to the durability of resistant crop varieties. In the present work, 25 Medicago truncatula genotypes from a core collection and six V. albo-atrum and V. dahliae strains were used to study the potential of non-host Verticillium strains isolated from different plant species to infect this legume plant and the plant’s susceptibility to the pathogens. The experiment was designed as factorial with randomised complete blocks and with three repetitions. The wilt symptoms caused by V. albo-atrum and V. dahliae were scored on a disease index scale from 0 to 4, during 30 days after inoculation of 10-day-old plantlets. Disease severity was quantified by maximum symptom scores (MSS) and areas under the disease progress curves (AUDPC), which integrate the time course of symptom development. Highly significant differences were observed among plant genotypes and fungal strains, and their interaction was also significant. The correlation between MSS and AUDPC was 0.86. The most severe symptoms were caused by the alfalfa strain V. albo-atrum V31-2 and the least severe by V. dahliae JR2, as shown by mean values obtained on the 25 genotypes. M. truncatula genotype TN8.3 was the most susceptible genotype by mean values obtained with the six fungal strains, whereas F11013-3, F83005.9 and DZA45.6 were highly resistant to all strains studied. The results can be used to choose parents for studying the genetics of resistance in Medicago truncatula to Verticillium strains with different levels of aggressiveness.     

Finite element analysis of stress and strain distributions in mortise and loose tenon furniture joints

We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon （M＆amp;LT） furni-ture joints under uniaxial bending loads, and determined the effects of loose tenon length （30, 45, 60, and 90 mm） and loose tenon thickness （6 and 8 mm） on bending moment capacity of M＆amp;LT joints constructed with polyvinyl acetate （PVAc） adhesive. Stress and strain distributions in joint elements were then estimated for each joint using ANSYS finite element （FE） software. The bending moment capacity of joints increased significantly with thickness and length of the tenon. Based on the FE analysis results, under uniaxial bending, the highest shear stress values were obtained in the middle parts of the tenon, while the highest shear elastic strain values were estimated in glue lines between the tenon sur-faces and walls of the mortise. Shear stress and shear elastic strain values in joint elements generally increased with tenon dimensions and corre-sponding bending moment capacities. There was consistency between predicted maximum shear stress values and failure modes of the joints.     

The radio-frequency single-electron transistor (RF-SET): A fast and ultrasensitive electrometer

A new type of electrometer is described that uses a single-electron transistor (SET) and that allows large operating speeds and extremely high charge sensitivity. The SET readout was accomplished by measuring the damping of a 1.7-gigahertz resonant circuit in which the device is embedded, and in some ways is the electrostatic "dual" of the well-known radio-frequency superconducting quantum interference device. The device is more than two orders of magnitude faster than previous single-electron devices, with a constant gain from dc to greater than 100 megahertz. For a still-unoptimized device, a charge sensitivity of 1.2 x 10(-5) e/hertz was obtained at a frequency of 1.1 megahertz, which is about an order of magnitude better than a typical, 1/f-noise-limited SET, and corresponds to an energy sensitivity (in joules per hertz) of about 41 Planck's over 2pi.     

Influence of Carotino oil on in vitro rumen fermentation,metabolism and apparent biohydrogenation of fatty acids

The study appraised the effects of Carotino oil on in vitro rumen fermentation, gas production, metabolism and apparent biohydrogenation of oleic, linoleic and linolenic acids. Carotino oil was added to a basal diet (50% concentrate and 50% oil palm frond) at the rate of 0, 2, 4, 6 and 8% dry matter of the diet. Rumen inoculum was obtained from three fistulated Boer bucks and incubated with 200 mg of each treatment for 24 h at 39°C. Gas production, fermentation kinetics, in vitro organic matter digestibility (IVOMD), volatile fatty acids (VFA), in vitro dry matter digestibility (IVDMD), metabolizable energy and free fatty acids were determined. Carotino oil did not affect (P > 0.05) gas production, metabolizable energy, pH, IVOMD, IVDMD, methane, total and individual VFAs. However, Carotino oil decreased (P < 0.05) the biohydrogenation of linoleic and linolenic acids but enhanced (P < 0.05) the biohydrogenation of oleic acid. After 24 h incubation, the concentrations of stearic, palmitic, pentadecanoic, myristic, myristoleic and lauric acids decreased (P < 0.05) while the concentration of linolenic, linoleic, oleic and transvaccenic acids and conjugated linoleic acid (CLAc9t11) increased (P < 0.05) with increasing levels of Carotino oil. Carotino oil seems to enhance the accumulation of beneficial unsaturated fatty acids without disrupting rumen fermentation.     

Alpha‐Linolenic Acid Supplementation in Tris Extender Can Improve Frozen–Thawed Bull Semen Quality

The study was conducted to evaluate the effects of α ‐linolenic acid (ALA) on frozen–thawed quality and fatty acid composition of bull sperm. For that, twenty‐four ejaculates obtained from three bulls were diluted in a Tris extender containing 0 (control), 3, 5, 10 and 15 ng/ml of ALA. Extended semen was incubated at 37°C for 15 min, to allow absorption of ALA by sperm cell membrane. The sample was chilled for 2 h, packed into 0.25‐ml straws and frozen in liquid nitrogen for 24 h. Subsequently, straws were thawed and evaluated for total sperm motility (computer‐assisted semen analysis), membrane functional integrity (hypo‐osmotic swelling test), viability (eosin‐nigrosin), fatty acid composition (gas chromatography) and lipid peroxidation (thiobarbituric acid‐reactive substances (TBARS)). A higher (p < 0.05) percentage of total sperm motility was observed in ALA groups 5 ng/ml (47.74 ± 07) and 10 ng/ml (44.90 ± 0.7) in comparison with control (34.53 ± 3.0), 3 ng/ml (34.40 ± 2.6) and 15 ng/ml (34.60 ± 2.9). Still, the 5 ng/ml ALA group presented a higher (p < 0.05) percentage of viable sperms (74.13 ± 0.8) and sperms with intact membrane (74.46 ± 09) than all other experimental groups. ALA concentration and lipid peroxidation in post‐thawed sperm was higher in all treated groups when compared to the control group. As such, the addition of 5 ng/ml of ALA to Tris extender improved quality of frozen–thawed bull spermatozoa.     

Effects of Microalgae and Alfalfa Meal on Population Growth and Production of a Freshwater Rotifer,Euchlanis dilatata (Rotifera: Mongononta)

Population growth and production of the freshwater rotifer, Euchlanis dilatata, were determined after being fed 1 of 12 diets: Scenedesmus quadricauda (S), Chlorella vulgaris (C), baker's yeast (Saccharomyces cerevisiae) (Y), alfalfa meal (Medicago spp.) (A), and eight combinations of S+C, S+Y, C+Y, S+C+Y, S+A, C+A, S+C+A, and Y+A (mixture in the same ratio by equal nitrogen weight). Results showed that both microalgal and alfalfa meal alone and in combination with Y had a significantly higher (P < 0.05) population growth and production compared with Y alone. The mean maximum E. dilatata population density fed on S, S+Y, C, C+Y, S+C, S+C+Y, Y, A, S+A, C+A, S+C+A, and Y+A diets were 65 ± 7.5 (mean ± SE), 124.6 ± 17.2, 115.8 ± 7.9, 41.5 ± 7.9, 131 ± 14.1, 93.5 ± 8.7, 14.5 ± 7.6, 129.5 ± 18.5, 255.0 ± 20.5, 180 ± 30.5, 124.5 ± 25.4, and 61.5 ± 24.5 individuals/mL, respectively. Correspondingly, the mean population growth rates (K) through the 16‐d culture period were 0.29, 0.40, 0.45, 0.27, 0.34, 0.41, 0.26, 0.51, 0.58, 0.59, 0.39, and 0.45/d, respectively. Results indicated that alfalfa meal in combination with microalgae and yeast could be used as primary diets for E. dilatata culture. This may reduce the costs of rotifer production.