Combining ability for nodulation in common bean (Phaseolus vulgaris L.) genotypes from Andean and Middle American gene pools

Ten F₁'s obtained from crosses among five common bean genotypes of Andean (WAF 15, Mineiro Precoce and Batatinha) and Middle American (BAT 304 and Ouro) gene pools were assessed for their combining abilities for root nodulation with Rhizobium tropici strain CIAT 899. The plants were grown under controlled conditions and evaluated for number of nodules per plant (NN), nodule dry weight (NDW), mean nodule weight (MNW) and plant fresh weight (PFW). The subdivision of the treatment effects on the general (GCA) and specific combining effects (SCA) were performed according to Griffing's diallel analysis method 2, model 1. The analyses of variance and estimates of quadratic components showed that non-additive gene effects were more important in the expression of NN and PFW, whereas additive gene effect was predominant for NDW and MNW. A close association was observed between high number of nodules and GCA. Generally, crosses involving parents of different gene pools yielded hybrids with high positive estimates of SCA for all assessed traits. The genotypes of Andean origin WAF 15 and Mineiro Precoce are the most promising parents for breeding programs to increase NN and NDW in common beans. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pharmacokinetics and bioavailability of oral firocoxib in adult,mixed‐breed goats

Pharmacokinetic (PK) studies of oral firocoxib in large animal species have been limited to horses, preruminating calves, and adult camels. The aim of this study was to describe pharmacokinetics and bioavailability of firocoxib in adult goats. Ten healthy adult goats were administered 0.5 mg/kg firocoxib intravenously (i.v.) and per os (p.o.) in a randomized, crossover study. Plasma firocoxib concentrations were measured over a 96‐hr period for each treatment using HPLC and mass spectrometry, and PK analysis was performed. The p.o. formulation reached mean peak plasma concentration of 139 ng/ml (range: 87–196 ng/ml) in 0.77 hr (0.25–2.00 hr), and half‐life was 21.51 hr (10.21–48.32 hr). Mean bioavailability was 71% (51%–82%), indicative of adequate gastrointestinal absorption of firocoxib. There were no negative effects observed in any animal, and all blood work values remained within or very near reference range at the study's conclusion. Results indicate that oral firocoxib is well‐absorbed and rapidly reaches peak plasma concentrations, although the concentration also decreased quickly prior to the terminal phase. The prolonged half‐life may suggest tissue accumulation and higher plasma concentrations over time, depending on dosing schedule. Further studies to determine tissue residue depletion, pharmacodynamics, and therapeutic concentrations of firocoxib in goats are necessary.