Enhanced upper tropical tropospheric COS: impact on the stratospheric aerosol layer

Carbonyl sulfide (COS) is considered to be a major source of the stratospheric sulfate aerosol during periods of volcanic quiescence. We measured COS at the tropical tropopause and find mixing ratios to be 20 to 50% larger than are assumed in models. The enhanced COS levels are correlated with high concentrations of biomass-burning pollutants like carbon monoxide (CO) and hydrogen cyanide (HCN). The analysis of backward trajectories and global maps of fire statistics suggest that biomass-burning emissions transported upward by deep convection are the source of the enhanced COS in the upper tropical troposphere.     

Effectiveness of selection at CIMMYT's main maize breeding sites in Mexico for performance at sites in Africa and vice versa

The exchange of elite breeding materials across regions is an important way in which multinational maize breeding programmes access new genetic variation, improve efficiency and reduce costs. Our objectives were to examine whether CIMMYT's breeding programmes for tropical and subtropical environments in Mexico and Eastern and Southern Africa (ESA) can effectively share materials. Sets of selected and unselected lines were evaluated for per se and testcross performance in multiple environments in Mexico and ESA for grain yield, days to anthesis and plant height. Genotypic correlations between performance in Mexico and ESA as testcross and line per se were high (≥ 0.72) for all experiments, and indirect selection efficiency ranged from 67 to over 100% for all traits. Lines selected in ESA or Latin America performed equally well in each region, indicating selection was for broad rather than regional adaptation. Thus, breeding programmes of CIMMYT in both Mexico and ESA can benefit tremendously by exchanging breeding materials and test results, and elite selections from each region should be fast‐tracked for evaluation in the other.     

Pharmacokinetics of enrofloxacin after multiple subcutaneous and intramuscular administrations in adult ostriches

1. The objective of the study was to evaluate the comparative pharmacokinetic behaviour of enrofloxacin in adult ostriches after single and multiple intramuscular (IM) and subcutaneous (SC) administrations. In addition, tissue tolerance was evaluated.

2. Enrofloxacin was well absorbed, but showed a short permanence after both administration routes. After multiple dose administrations the maximum and minimum peak plasma concentrations were very similar for both routes, obtaining a steady state phase from the second dose that extended until the last evaluated administration.

3. There was no significant accumulation after multiple IM or SC doses; however, there were differences in a fluctuation index after multiple intramuscular administrations that could be related to muscle damage.

4. The different microbiological efficacy indicators (PK/PD indices) obtained, the pharmacokinetic behaviour and CK serum concentrations suggest that subcutaneous enrofloxacin administration of 15 mg/kg every 12 h produce and maintain an efficient concentration of antibiotic that is a safer and more effective therapeutic option than intramuscular administration.     

In situ studies on the time-dependent degradation of recombinant corn DNA and protein in the bovine rumen

An in situ technique was adopted to investigate the time-dependent ruminal degradation of chloroplast compared with recombinant DNA of Bt176 corn using conventional and quantitative PCR assays. In parallel, the Cry1Ab protein content and fragment sizes were determined by ELISA and immunoblotting techniques. Triplicate nylon bags filled with 5 g of each substrate (whole-plant isogenic, whole-plant transgenic, ensiled isogenic, and ensiled transgenic corn) were positioned within the rumen of 5 rumen-cannulated, nonlactating cows and incubated for 2, 4, 8, 16, 24, and 48 h. To investigate the DNA degradation process, PCR assays were developed to detect fragments of the endogenous highly abundant rubisco gene (173, 896, 1,197, and 1,753 bp) and of the recombinant cry1Ab gene (211, 420, 727, and 1,423 bp). Short fragments of rubisco (<431 bp) and cry1Ab DNA (211 bp) were amplifiable in whole-plant and ensiled corn samples incubated in the rumen for 48 h, whereas the traceability of larger fragments depended on previous processing of the sample (whole-plant or ensiled corn), the length of the target sequence, and concomitantly on the length of time incubated in the rumen. Quantification of rubisco and cry1Ab gene fragments applying real-time PCR assays revealed degradation to <20% of initial 0-h values within 2 h and <0.5% after 48 h of ruminal incubation. Analysis of Cry1Ab protein in whole-plant corn using the ELISA technique revealed a decrease to 28.0% of the initial value within 2 h and to 2.6% within 48 h. The concentration of Cry1Ab protein of ensiled corn was only 10% that of whole-plant corn. Ensiled corn Cry1Ab protein decreased to 10% of initial values after 48 h of ruminal incubation. Using an immunoblotting technique, the full-size Cry1Ab protein was only detectable up to 8 h; thereafter, only fragments of approximately 17 and 34 kDa size were found. In conclusion, ruminal digestion decreased the presence of functional cry1Ab gene fragments. It is unlikely that full-size, functional Cry1Ab protein will be present after 8 h of incubation in the rumen. Therefore, results based on ELISA measurements should be interpreted carefully and verified by another detection method that discriminates between the full-size and fragmented Cry1Ab protein.     

The Plabsoft database: a comprehensive database management system for integrating phenotypic and genomic data in academic and commercial plant breeding programs

Besides phenotypic data from field trials and molecular data from lab experiments, modern plant breeding programs generate a wide variety of data, for instance pedigree, randomization, geostatistical or climate data. Due to the lack of an integrated database system, breeders generally exploit only part of these data for selection decisions or retrieve only part of the information present in the data. Most approaches in genomics, however, develop their full power only when they are based on analyses of large numbers of genotypes from multiple crosses and current as well as past generations. We have developed a flexible data management and -analyses system for storage and quality control of plant breeding data. It is implemented using the PostgreSQL database management system and linked to the R software environment for integrated statistical analyses of phenotypic and genomic data. The database structure is capable of managing the following types of data observed in breeding programs of all major crops: (a) germplasm data of any species including pedigree data, (b) phenotypic data of any trait and trait complexity, (c) trial management data for any field and trial design, (d) molecular marker data for all common types of markers, as well as (e) project and study management data.     

Genomic prediction and GWAS of Gibberella ear rot resistance traits in dent and flint lines of a public maize breeding program

Gibberella ear rot (GER) is a serious threat to maize cultivation, causing grain yield losses and contamination with mycotoxins. Genomic prediction (GP) has great potential to accelerate resistance breeding against GER. However, small training sets (TS) consisting of both phenotyped and genotyped individuals are a challenge for obtaining high prediction accuracy (ρ) in GP. A potential solution would be combining small-size populations across heterotic pools. However, genetic heterogeneity between populations in terms of segregating QTL, linkage disequilibrium (LD) pattern and genomic relationships can impair ρ of GP. In this study, we investigated the genetic architecture of GER severity, deoxynivalenol concentration (DON) and days to silking with genome-wide association studies within two elite panels of 130 dent and 114 flint lines from the maize breeding program of the University of Hohenheim tested in four environments. We also assessed the consistency of LD pattern and genomic relationships between the two heterotic pools. Furthermore, we compared four GP approaches differing in the composition of the TS with lines from a single or combined pool(s) and statistical models with marker effects identical or different but correlated between pools. We detected two and six QTL for DON within the dent and flint pool, respectively, but no common QTL. The LD pattern was consistent between pools for marker pairs ≤ 10 kb apart. GP across pools yielded low or even negative ρ. Combined-pool GP had no higher ρ than within-pool GP, regardless of the statistical model. Our findings underline the importance of investigating the genetic heterogeneity between populations prior to implementing GP using combined TS.     

Rates of Chlorimuron Applied in Glyphosate-Tolerant and Sulfonylurea-Tolerant Soybean

Susceptibility to chlorimuron varies according to soybean genotype. STS® (sulfonylurea-tolerant soybean) presents a high tolerance to some sulfonylureas; this feature is determined by semi-dominants alleles, Als1 and Als2. Experiments were conducted in the field for four seasons with two cultivars for season to evaluate the selectivity of chlorimuron rates in post-emergency (V4) of glyphosate-tolerant and sulfonylurea-tolerant soybean. Data analysis made it possible to infer that there was no significant effect on the productivity of the cultivars when they received application in post-emergency, of chlorimuron at the doses used (0, 15, 30, 45, 60, 75, and 90 g ai ha^-1). The maximum recommended rate for non-STS cultivars of chlorimuron is 20 g ai ha^-1, or 4.5 times less than the maximum rate employed in this study. The soybean cultivars CD 250 RR/STS, CD 236 RR/STS, CD 2630 RR/STS, and BMX Turbo RR/STS were tolerant to the application, in post-emergency (V4) of the herbicide chlorimuron, until the rate of 90 g ai ha^-1.