Transition-State Spectroscopy of Cyclooctatetraene

The 351-nanometer photoelectron spectrum of the planar cyclooctatetraene radical anion (COT·-) shows transitions to two electronic states of cyclooctatetraene (COT). These states correspond to the D4h 1A1g state, which is the transition state for COT ring inversion, and the D8h 3A2u state. The electron binding energy of the 1A1g transition state is 1.099 ± 0.010 electron volts, which is lower by 12.1 ± 0.3 kilocalories per mole than that of the 3A2u state. The photoelectron spectrum shows that the singlet lies well below the triplet in D8h COT and confirms ab initio predictions that the molecule violates Hund's rule. Vibrational structure is observed for both features and is readily assigned by use of a simple potential energy surface.     

Recalibrated Mariner 10 Color Mosaics: Implications for Mercurian Volcanism

Recalibration of Mariner 10 color image data allows the identification of distinct color units on the mercurian surface. We analyze these data in terms of opaque mineral abundance, iron content, and soil maturity and find color units consistent with the presence of volcanic deposits on Mercury's surface. Additionally, materials associated with some impact craters have been excavated from a layer interpreted to be deficient in opaque minerals within the crust, possibly analogous to the lunar anorthosite crust. These observations suggest that Mercury has undergone complex differentiation like the other terrestrial planets and the Earth's moon.     

Barley yellow dwarf virus resistance in the genus Avena

Summary The barley yellow dwarf virus resistance level was evaluated in acessions of most species of the genus Avena. Highest levels of resistance were found in A. sterilis and A. occidentalis. High resistance levels were also found in A. barbata, A. fatua, A. hybrida, A. macrostachya, diploid A. nuda and A. strigosa. Results are discussed in relation to breeding for resistance.Contribution No. 229.     

Barley Yellow Dwarf Virus Resistance in Triticum aestivum×Leymus angustus Hybrids

The enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration of barley yellow dwarf virus (BYDV) in leaves of spring wheat Triticum aestivum L. cv. ‘Fukuhokomugi’, Leymus angustus (Trin.) Pilger (Altai wild rye) and their F₁ hybrids inoculated at the 2- to 3-leaf stage. The BYDV isolate “Cloutier” (serotype PAV) was used. The results showed that L. angustus confers immunity or strong resistance to the virus. Significant multiplication of the virus occurred in ‘Fukuhokomugi’ which expressed an intermediate level of tolerance to the disease under field conditions. The F₁ haploid hybrids of ‘Fukuhokomugi’×L. angustus expressed a level of resistance almost equal to that of their wild parent, with a low concentration of virus appearing 16 days after inoculation and no more afterwards. The discovery of BYDV resistance in L. angustus and the expression of this character in the F₁ hybrids provide new opportunities for the enlargement of the gene pool for BYDV resistance in wheat.     

Identification of Rye Chromosomes Involved in Tolerance to Barley Yellow Dwarf Virus Disease in Wheat × Triticale Hybrids

Common wheat × hexaploid triticale hybrids were produced and evaluated for tolerance to barley yellow dwarf virus disease (BYD). The BYD tolerance expression varied with wheat × triticale combination. The selection for BYD tolerance increased the recovery of tolerant genotypes in the next generations. Homozygous tolerant and susceptible lines were obtained in advanced generations. The rye chromosomes 1R, 2R, and 4R with 7R were transmitted as disomic or monosomic, disomic, and double disomic substitution to the late generations of ‘Musala’ (common wheat) בMuskox 658’ (triticale), ‘Encruzilhada’ (common wheat) בNord Kivu’ (triticale) and ‘Encruzilhada’× 12th. International Triticale Screening Nursery 267 (12ITSN267) (triticale), respectively. A clear association was established between the 1R chromosome of the ‘Muskox 658’ triticale line and the tolerance to BYDV. Results suggest that the 2R chromosome may be involved in BYD tolerance of ‘Nord Kivu’ triticale line.     

A New Intergeneric Hybrid between Triticum aestivum L. and Agropyron fragile (Roth) Candargy: Variation in A. fragile for Suppression of the Wheat Ph-Locus Activity

New intergeneric hybrids were obtained between Triticum aestivum L. cv. Tukuho’ (2n = 6x = 42, AABBDD) and Agropyron fragile (Roth) Candargy PGR 8097 (2n = 4x = 28, PPPP) at a frequency of 1.06 %, through the use of direct embryo culture and in ovulo embryo culture. Such hybrids could be used to transfer barley yellow dwarf virus (BYDV) resistance and winterhardiness into bread wheat. The somatic chromosome number in all the hybrid plants was 2n = 5x = 35, as expected. Considerable variation in chromosome pairing was observed among the different hybrid plants. Average meiotic chromosome configuration at metaphase I was 17.29 Is + 6.57 rod Us + 1.97 ring Us + 0.18 III + 0.03 IV + 0.002 VI. The high level of chromosome pairing in some F₁ hybrids was attributed to Ph-suppressor gene(s) present in A. fragile. The hybrids could not be backcrossed to wheat, but amphiploid seeds have been obtained by colchicine treatment.     

Rainfall and breed effects on the efficacy of ivermectin jetting fluid for the prevention of fly strike and treatment of infestations of lice in long-wooled sheep

SUMMARY An ivermectin-based jetting fluid was assessed for its efficacy in the prevention of blowfly strike and treatment of lice in long-wooled sheep. The ivermectin concentrate was diluted to 0.03 mg/mL and applied via a standard hand jetting technique. In insectary studies, using laboratory-reared Lucilia cuprina, sheep jetted with ivermectin were protected from induced breech and body strikes for 18 weeks after treatment. Merino and Corriedale sheep were equally protected, as were sheep subjected to 25 mm simulated rainfall at 1, 3 or 6 hours after jetting. Naturally occurring infestations of lice, Bovicola (Damalinia) ovis, were successfully treated with ivermectin jetting fluid in Merino and Corriedale sheep using a standard hand jetting technique. In addition, the efficacy of treatment was not affected by simulated rainfall at 1, 3 or 6 hours after treatment.     

Effect of Short-Term Restricted Food Intake on Canine Pseudopregnancy

A non-pharmaceutical, dietary option may be useful to manage clinical pseudopregnancy (PSP). To describe the effect of short-term food restriction on canine PSP, 16 privately owned, overtly pseudopregnant bitches were randomly assigned to one of the following groups: Limit-fed (increasing amounts of a restricted maintenance: 50%, 40%, 30% restriction for 2, 3 and 2 days respectively) during 7 days (n = 8) or Maintenance-fed of the same food and period (n = 8). The bitches were physically examined and blood samples were taken for prolactin and progesterone determinations on days 2, 5 and 8. By day 8, none of the bitches had completely regressed the condition although all (8/8) the animals of the Limit-fed and two (25%) of the Maintenance-fed group improved in condition decreasing mammary size and secretion (p < 0.05). No day or group effects were observed for serum prolactin and progesterone concentrations (>0.05). It is concluded that although an 8-day food restriction did not cure PSP, it seemed to hasten PSP signs involution in these bitches. No endocrine change was related to these clinical findings.