Experimental Breeder Research Articles

Production of Peanut Seed Free of Peanut Stripe and Peanut Mottle Viruses in Florida

Peanut (Arachis hypogaea 1.) seed free of both peanut stripe (PStV) and peanut mottle (PMoV) potyviruses were harvested in 1986-1990 from virus-indexed, greenhouse-grown plants for field propagation. Neither virus was detected in field plots sown in 1987 and 1989 with virus-indexed, greenhouse-grown seed and isolated by at least 5 km from any commercial or experimental plantings. PMoV, but not PStV, was detected in a similar field plot sown in 1988 and located about 1.5 km from a 128-ha commercial field. PStV was detected in 247 of 497 plants in an experimental breeder's field sown in 1988-1991 with seed infected with this virus but was detected in only one of 1,431 plants in a similar field located 13 km away and sown with virus-indexed, greenhouse-grown seed

Effects of Chemically or Virus-Induced Immunodepression on Response of Chickens to Avian Leukosis Virus

The effects of chemically or virus-induced immunodepression on the infection profile (development of viremia and antibody) and shedding of avian leukosis virus (ALV) were studied in progeny chickens of experimental or commercial breeder flocks. Chickens were infected with ALV subgroup A by contact at hatching and by oral inoculation at 4-5 weeks of age. In the first experiment, chickens were inoculated with a virulent strain of infectious bursal disease virus (IBDV) at 1 day or 6 weeks of age. In the second experiment, chickens were neonatally treated with cyclophosphamide (CY), or were inoculated with strain T of reticuloendotheliosis virus (REV) at hatching, or were inoculated with strain JM of Marek's disease virus (MDV) at 2 weeks of age. The infection profile and cloacal shedding of ALV in chickens exposed to ALV and inoculated with immunodepressive viruses or CY were compared with those in hatchmates exposed only to ALV. In two of four chicken lines tested in the first experiment, shedding of ALV, as determined by virological assays of cloacal swabs at 22 weeks of age, was significantly higher in chickens infected with IBDV at 1 day of age than in uninfected hatchmates. The rate of shedding of ALV in one of these two lines was also significantly higher in chickens infected with IBDV at 6 weeks of age than in uninfected chickens. Further, the frequency of ALV-antibody detection at 22 weeks of age was significantly lower in chickens of these two lines infected with IBDV at 1 day of age than in uninfected chickens. In the second experiment, neonatal treatment with CY significantly increased the frequency of viremic chickens of both experimental and commercial flocks. The frequency of ALV-viremic chickens at 22 weeks of age was considerably higher in the REV- and MDV-inoculated groups (54% and 44%, respectively) than in control hatchmates (29%), but only in chickens of the commercial line. These findings suggest that chemically or virus-induced immunodepression may lead to an increase in rates of viremia and shedding of ALV in chickens infected with virus after hatching, especially in certain genetic lines.

Indication lowering of average magnitude type campbelling system in low pulse rate region. Dependence of characteristic on product of pulse rate and pulse width.

In the nuclear power calibration process of JOYO, the first experimental fast breeder reactor in Japan, the indication of the Intermediate Range Monitoring System (IRMS), employing Average Magnitude type Campbelling System (AMCS), was calibrated with the reactor power at 45.82 kW. The reactor power was then decreased and the nonlinear indication lowering of the IRMS was observed.In this paper, we present a derivation of an equation representing the AMCS characteristic and show that the indication lowering occurs when the product of mean arrival rate of pulses and their width is small. The computed values based on the derived equation agreed very well with the observed ones in the JOY() IRMS below 45.82 kW, and it was confirmed that the evaluation method was applicable. Furthermore, it was evident from the evaluation that the indication lowering of the JOYO IRMS above 45.82 kW was negligibly small, and did not affect the reactor power ascension testing. Also, it was proved in a following thermal calibration test above 50 kW that the indication lowering was allowably small indeed in this power region.

Controlling Cesium in the Coolant of the Experimental Breeder Reactor II

Carbon has been shown to be an effective getter for cesium in liquid sodium. A cesium trap containing reticulated vitreous carbon and operating at 190°C has been used at the Experimental Breeder Re...

Lubrication at Dounreay

The diesel installation for the new Dounreay Atomic Plant on the extreme northern coast of Scotland will be one of the largest multi‐engined stations built in recent years. This station, the first British experimental fast breeder reactor will be entirely dependent upon it for its power supply. Much attention has been given to the storage and handling of fuel and lubricants. Shell Rimula Oil 30 has been chosen as the lubricating oil and one of the chemists at Dounreay has been trained by Shell in the analysis of used lubricating oils and the interpretation of results. He will be made responsible for regular examination of samples from each engine. Simultaneously, Shell are conducting a parallel series of tests with a view to determining optimum oil change periods in the interests of economy.

CORROSION COMMENTARY

PREPARING THE DOUNREAY SPHERE. The 135 ft. dia. sphere under construction for the United Kingdom Atomic Energy Authority at Dounreay, Caithness, is now about half completed. It will house the world's first large‐scale experimental fast breeder reactor and the project is estimated to cost some £15 million. This vast welded steel structure represents the collaboration and combined effort of several firms using many specialised items of equipment, prominent amongst which is the equipment for surface preparation and anti‐corrosive treatment.

Oenothera Cytology in Relation to Genetics

1. In attempting to relate the chromosome circles which are observed in many species of Oenothera, to the extensive linkages which characterize this group of plants, Cleland makes two assumptions: (a) that homologous chromosomes are adjacent to each other in the circles, and (b) that chromosomes of maternal and paternal origin alternate with each other in a definitely fixed order. 2. The evidence cited by Cleland and others for the first of these theses is convincing, but not for the second. 3. In the absence of evidence regarding the arrangement of the chromosomes in the original diploid spireme following fertilization, it seems reasonable to assume that homologous chromosomes become associated in pairs which may lie in any plane with reference to adjacent pairs, and that when the spireme is formed, the maternal or paternal origin of the chromosomes has no influence in determining the order of arrangement of the members of each pair of homologues. 4. Even if it be assumed that the order of succession of maternal and paternal chromosomes in the original spireme is definite, they need not remain in the same order until the chromosome circles emerge in late meiotic prophase, since the looping of the chromosomes during "second contraction" provides for possible reversals in the positions of the homologous chromosomes. 5. A spireme in which each pair of homologues remains associated, but in which the order of maternal and paternal chromosomes is indeterminate, provides for the normal separation of homologues when adjacent chromosomes move to opposite poles of the meiotic spindle, and such separation is probably achieved even when adjacent chromosomes move to the same pole, if two other adjacent chromosomes in some other part of the circle move together to the other pole. 6. It also provides for a chance assortment at each pole, of chromosomes of maternal and paternal origin, just as is known to take place when the arrangement of the chromosomes is parasynaptic. 7. This being the case, there may be as many independent linkage groups as there are haploid chromosomes regardless of the grouping of the chromosomes into circles. The discovery of three linkage groups in Oe. Lamarckiana, in which the chromosomes are associated in a circle of twelve and one pair, is favorable to this view. 8. The telosynaptic arrangement of the chromosomes and their persistent cohesion into chains or circles, therefore, probably have no very fundamental genetical significance. 9. Irregularities in distribution of the chromosomes of the circles at anaphase are more frequent in such stable species as Oe. biennis, Oe. muricata and Oe. franciscana sulfurea than the number of visible genetical variations would lead one to expect if each such irregularity resulted in the exchange of genetically dissimilar chromosomes from one parental "complex" to the other. 10. Different species having like arrangement of the chromosome circles do not agree with one another in their genetical behavior, but seem to differ from each other rather on the basis of the number and nature of the lethal factors they possess. 11. Studies of Illick, Cleland and Hakansson have shown that at the time of second contraction in meiotic prophase, chromatin loops which probably represent pairs of homologous chromosomes show twisting and fusion which provide the possibility of transfer of chromatin particles or of whole sections of the chromosome from one homologue to the other, thus providing for crossing over within the linkage groups, notwithstanding the fact that the chromosomes are arranged telosynaptically. This sets aside Gates's (1922) contention that no mechanism exists for the production of crossing over in Oenothera. 12. The conception of the spireme here presented is just as hypothetical as is Cleland's view. Fortunately a decision between the two views seems capable of experimental attainment, especially through close cooperation between the experimental breeder and the cytologist.

Studies in Ranch Economics

Studies in ranch economics and related problems comprise a relatively new and fertile field for agricultural research workers. Not only is this an inviting field for the research economist, but also for the animal husbandman, the botanist, the pathologist, the experimental breeder, the chemist, and the nutrition specialist. In fact it is the combined and correlated efforts of the several types of specialists that is necessary to render the industry the maximum of research service. Such work was initiated in Texas about 1915 when the governing board established a Ranch Experiment Station in a typical ranching area on the Edwards Plateau. The problem was (1) to focus the activities of the different research specialists-the chemist, the botanist, the entomologist, and the animal husbandman-on the varying problems of the range livestock industry; (2) to coordinate the research activities of these physical and biological research workers with those of the research agricultural economist; (3) to find the most important of the ranch problems; (4) to develop research methods especially suited to the different studies to be made; and (5) to make headway with appropriate projects. Some of the major objectives of ranch economics research, considered from the point of view of the industry as well as that of the investigator, are: (1) To study with a view of improvement and better utilization of the carrying capacity of our ranges; (2) To improve the quantity and also the quality of our ranch products; (3) To effect a consistent way to lower production and marketing costs;