THE COMPARATIVE SENSITIVITY OF SHEEP AND CHICKEN EMBRYOS TO BLUETONGUE VIRUS AND OBSERVATIONS ON VIRAEMIA IN EXPERIMENTALLY INFECTED SHEEP

The virus titre in sheep blood samples received from BT-suspected cases in the field was assayed in sheep and in chicken embryos. These infected blood samples represented 3 different BT virus types: 4, 10 and 16. Three identical experiments were performed, one with each of the 3 different virus types. Ten-fold dilutions of the infected blood samples were prepared and 1 ml of each blood dilution was inoculated IV into series of 10 to 12-month old susceptible sheep; at the same time 0.1 ml of each dilution was inoculated IV into series of 10 to 13-day-old chicken embryos. The virus titre was found to be similar when assayed in the two host systems. There was no correlation between the amount of virus inoculated and the severity of symptoms in the inoculated sheep. The virus content in daily blood samples collected from the experimental sheep was assayed by IV inoculation of CE. Virus was isolated from all the reacting sheep and was detected sometimes as early as 1 day PI and as late as 30 days PI. A high titre of log10 4.0 to 7.0 per 1 ml of blood was recorded during several consecutive days before and after the onset of clinical signs. There seemed to be an inverse ratio between the amount of virus inoculated and the number of days the virus persisted in the bloodstream. The neutralisation index in day 22 serum samples was 3.5 to 4.5. Virus was isolated from some of the reacting sheep on the day that these antibody levels were recorded. Since the comparative simultaneous titrations of BT virus in sheep and in CE yielded similar results, the IV inoculation of CE is advocated as the routine method to be employed for laboratory diagnosis of this disease.     

Antibiosis of maize inbred lines to the carmine spider mite, tetranychus cinnabarinus

The antibiosis of tenZea mays L. inbred lines to the carmine spider mite,Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae), was evaluated. Two maize inbred lines previously reported as resistant to this spider mite and a susceptible inbred line were compared with B96 (formerly called 41:2504B), reported as being resistant to the two-spotted spider mite T. urticae and to the European corn borer (Ostrinia nubilalis Hübner). Other lines were derived from B96. All lines originated in the U.S.A. and were tested in Israel at two different growth stages. Four days after inoculation of detached leaf squares with adult mites, significant differences in susceptibility were observed among lines. At the 3-leaf stage lines B68, B96, B79, A619, B65, B49 and B64 reduced the average mite daily fecundity by 43%, 64%, 66%, 67%, 77%, 81% and 87%, respectively, as compared with the most susceptible line, B52. At the flowering stage, the average reduction in mite daily fecundity was much lower: inbred lines B64, A619 and B96 reduced the average mite daily fecundity by 48%, 51% and 86%, respectively, whereas the seven other genotypes had an intermediate or a susceptible reaction to the carmine spider mite, with A661 being the most susceptible. Our results show that B96 could be used as a source of resistance in developing improved resistance of inbred lines of maize to carmine spider mites.     

Pseudo-random unitary operators for quantum information processing

In close analogy to the fundamental role of random numbers in classical information theory, random operators are a basic component of quantum information theory. Unfortunately, the implementation of random unitary operators on a quantum processor is exponentially hard. Here we introduce a method for generating pseudo-random unitary operators that can reproduce those statistical properties of random unitary operators most relevant to quantum information tasks. This method requires exponentially fewer resources, and hence enables the practical application of random unitary operators in quantum communication and information processing protocols. Using a nuclear magnetic resonance quantum processor, we were able to realize pseudorandom unitary operators that reproduce the expected random distribution of matrix elements.     

Differences in the responses of melon accessions to fusarium root and stem rot and their colonization by Fusarium oxysporum f. sp. radicis‐cucumerinum

Fusarium root and stem rot caused by the fungus Fusarium oxysporum f. sp. radicis‐cucumerinum is a major disease in greenhouse cucumbers. Over the past decade, the disease has been documented in melon greenhouses in Greece, and recently it has been sporadically recorded in greenhouse melons in Israel. Variations in disease response were found among 41 melon accessions artificially inoculated with the pathogen: 10 accessions were highly susceptible (90–100% mortality), 23 exhibited an intermediate response (20–86%) and eight were resistant (0–4%). Two melon accessions – HEM (highly resistant) and TAD (partially resistant) – were crossed with the susceptible accession DUL. The responses of the three accessions and F₁ crosses between the resistant and susceptible parents were evaluated. HEM contributed higher resistance to the F₁ hybrid than TAD. Roots of susceptible and resistant accessions were 100 and 79% colonized, respectively, following artificial inoculation. However, only susceptible plants showed colonization of the upper plant tissues. Microscopic evaluation of cross sections taken from the crown region of the susceptible DUL revealed profuse fungal growth in the intercellular spaces of the parenchyma and in xylem vessels. In the resistant cultivar HEM, very little fungal growth was detected in the intercellular spaces of the parenchyma, and none in the xylem or any other vascular tissue. Finding resistant accessions may create an opportunity to study the genetics of resistance inheritance and to develop molecular markers that will facilitate breeding resistant melon cultivars.     

Carotenoid pigmentation affects the volatile composition of tomato and watermelon fruits, as revealed by comparative genetic analyses

Tomato near-isogenic lines differing in fruit carotenogenesis genes accumulated different aroma volatiles, in a strikingly similar fashion as compared to watermelon cultivars differing in fruit color. The major volatile norisoprenoids present in lycopene-containing tomatoes and watermelons were noncyclic, such as geranial, neral, 6-methyl-5-hepten-2-one, 2,6-dimethylhept-5-1-al, 2,3-epoxygeranial, (E,E)-pseudoionone, geranyl acetone, and farnesyl acetone, seemingly derived from lycopene and other noncyclic tetraterpenoids. Beta-ionone, dihydroactinodiolide, and beta-cyclocitral were prominent in both tomato and watermelon fruits containing beta-carotene. Alpha-ionone was detected only in an orange-fleshed tomato mutant that accumulates delta-carotene. A yellow flesh (r) mutant tomato bearing a nonfunctional psy1 gene and the yellow-fleshed watermelon Early Moonbeam, almost devoid of carotenoid fruit pigments, also lacked norisoprenoid derivatives and geranial. This study provides evidence, based on comparative genetics, that carotenoid pigmentation patterns have profound effects on the norisoprene and monoterpene aroma volatile compositions of tomato and watermelon and that in these fruits geranial (trans-citral) is apparently derived from lycopene in vivo.     

Acetyl-coa: alcohol acetyltransferase activity and aroma formation in ripening melon fruits

Melon varieties (Cucumis melo L.) differ in a range of physical and chemical attributes. Sweetness and aroma are two of the most important factors in fruit quality and consumer preference. Volatile acetates are major components of the headspace of ripening cv. Arava fruits, a commercially important climacteric melon. In contrast, volatile aldehydes and alcohols are most abundant in cv. Rochet fruits, a nonclimacteric melon. The formation of volatile acetates is catalyzed by alcohol acetyltransferases (AAT), which utilize acetyl-CoA to acetylate several alcohols. Cell-free extract derived from Arava ripe melons exhibited substantial levels of AAT activity with a variety of alcohol substrates, whereas similar extracts derived from Rochet ripe melons had negligible activity. The levels of AAT activity in unripe Arava melons were also low but steadily increased during ripening. In contrast, similar extracts from Rochet fruits displayed low AAT activity during all stages of maturation. In addition, the benzyl- and 2-phenylethyl-dependent AAT activity levels seem well correlated with the total soluble solid content in Arava fruits.     

Dual role of the pigmentation gene B in affecting carotenoid and vitamin E content in squash (Cucurbita pepo) mesocarp

The yellow and orange colorations of the mesocarp of pumpkins and squash of Cucurbita pepo are due to the presence of carotenoid pigments that also greatly contribute to their nutritional value. Carotenoids, as well as tocopherols (vitamin E), are isoprenoid compounds formed by branches of a common biosynthetic pathway. Photodiode array HPLC analysis was used to simultaneously determine the content and composition of fruit-flesh carotenoids and tocopherols in five pairs of near-isogenic lines differing in the allelic state of genes previously identified as having profound effects on fruit color. The dominant B allele promoted carotenoid accumulation up to 5-fold and prevented tocopherol accumulation in all genetic backgrounds. The dominant L-2 allele doubled carotenoid content and, in combination with the dominant B allele, increased carotenoid content by 10-15-fold as compared to the recessive l-2 allele. The genes D and L-1 had no significant effects on mesocarp tocopherols or carotenoids content. These results indicate that the B gene, which affects both carotenoids and tocopherols, may play a regulatory role in the flux of the isoprenoid pathway products.