The effects of population density and sex ratio on mating frequency ofEarias insulana males and females in laboratory cultures

In laboratory populations ofEarias insulana Boisduval (Lepidoptera: Noctuidae) crowding did not affect spermatophore production by males or its acceptance by females. Sex ratio affected spermatophore transfer. A low male: female ratio resulted in the transfer of a large number of spermatophores per male. On the other hand, a high male: female ratio resulted in a high mating frequency of females. Egg production and hatching were not affected.     

Influence of culture medium and in vitro conditions on shoot regeneration in Solanum phureja monoploids and fertility of regenerated doubled monoploids

Incorporation of monoploids in practical breeding requires an efficient method of producing homozygous diploids. This study investigated factors for efficient regeneration of doubled monoploid (DM) potato, crossability of DMs and their field performance. Incorporation of silver thiosulphate (STS) in propagation medium for in vitro monoploid plantlets of Solanum phureja did not affect the frequency of cells with diploid(2x) nuclei but increased those with monoploid (1x) and decreased those with 4x nuclei. Higher shoot regeneration was obtained from leaf explants compared with stem explants. Induction of shoots from calluswas affected neither by light during incubation nor by overnight treatment with a benzyl adenine pulse. Female fertility based on seed set after pollination of DMs with heterozygous diploid clones varied among DMs but encouraged their utilization in practical breeding.     

β-Glucosidase involvement in the formation and transformation of oleuropein during the growth and development of olive fruits (Olea europaea L. cv. Arbequina) grown under different farming practices

The present study investigates oleuropein metabolism, as well as the involvement of β-glucosidase during the growth, development, and ripening of olive fruit. The results show that in olive fruit the in vivo formation and transformation of oleuropein takes place in three different stages. The first one is characterized by a net accumulation of oleuropein and occurs in the immature fruit. In the second stage, associated with the green and light-green fruits, oleuropein content is maintained practically constant, and finally, a third stage that begins in the green-yellow fruit is characterized by a progressive decline of the oleuropein concentration. Our findings confirm that in the absence of β-glucosidase the Damtoft-proposed pathway is active and that net synthesis of oleuropein is unquestionable. β-Glucosidase activity plays a key role in the oleuropein metabolism catalyzing its in vivo hydrolysis.     

Ferroelectric memories

In the past year it has become possible to fabricate ferroelectric thin-film memories onto standard silicon integrated circuits that combine very high speed (30-nanosecond read/erase/rewrite operation), 5-volt standard silicon logic levels, very high density (2 by 2 micrometer cell size), complete nonvolatility (no standby power required), and extreme radiation hardness. These ferroelectric random-access memories are expected to replace magnetic core memory, magnetic bubble memory systems, and electrically erasable read-only memory for many applications. The switching kinetics of these films, 100 to 300 nanometers thick, are now well understood, with switching times that fit an activation field dependence that scales applied field and temperature. Earlier problems of fatigue and retention failure are also now understood and have been improved to acceptable levels.