Validation of a real-time PCR for the quantitative estimation of a G143A mutation in the cytochrome bc1 gene of Pyrenophora teres

A single nucleotide polymorphism (SNP) in the cytochrome b gene confers resistance to strobilurin fungicides for several fungal pathogens. Therefore, on the basis of a change at amino acid position 143 from glycine to alanine, a real-time PCR assay was established for the quantitative detection of the analogous SNP in the cytochrome b sequence of Pyrenophora teres Drechsler, which causes barley net blotch. Allelic discrimination was achieved by using allele specific primers with artificially mismatched nucleic acid bases and minor groove binding probes. Validation parameters for the lower limits of the working range, namely limits of detection (LOD) and limits of quantification (LOQ), were statistically determined by the variance of calibration data, as well as by the variance of the 100% non-strobilurin-resistant allele DNA sample (blank values). It was found that the detection was limited by the variance of blank values (five in 801 458 copies; 0.0006%), whereas the quantification was limited by the variance of calibration data (37 in 801 458 copies; 0.0046%). The real-time PCR assay was finally used to monitor strobilurin-resistant cytochrome b alleles in barley net blotch field samples, which were already classified in in vivo biotests to be fully sensitive to strobilurins. All signals for strobilurin-resistant cytochrome b alleles were below the LOD, and therefore the results are in total agreement with the phenotypes revealed by biotests.     

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Effects of grain processing and dietary lipid source on performance, carcass characteristics, plasma fatty acids, and sensory properties of steaks from finishing cattle

An experiment was conducted to evaluate the effects of grain processing and lipid addition to finishing diets on cattle performance, carcass characteristics, and meat quality. Eighty Hereford x Angus steers (384 kg +/- 17 kg of BW) were fed diets containing steam-flaked corn (SFC) or dry-rolled corn (DRC) with and without the addition of tallow (SFC/Fat and DRC/Fat) or steam-flaked corn with ground flaxseed (SFC/Flax). Ribeye steaks from steers fed SFC, SFC/Fat, or SFC/ Flax were used to evaluate the effects of fat source on meat quality. Cattle fed SFC and SFC/Fat tended to have greater ADG, G:F, HCW, and USDA yield grade, compared with those fed DRC and DRC/Fat (P < 0.10). Steaks from steers fed SFC/Flax developed a detectable off-flavor (P < 0.05) compared with steaks from steers fed SFC and SFC/Fat, and steaks from steers fed SFC retained desirable color longer than those from steers fed SFC/Flax (P < 0.05). Feeding SFC/Flax increased deposition of alpha-linolenic acid in muscle tissue compared with feeding SFC or SFC/Fat (P < 0.01). Dietary treatment did not cause differences in tenderness, juiciness, or flavor intensity. Ground flaxseed can replace tallow in finishing diets without loss in performance, but flax may affect flavor and color stability of beef. Feeding flaxseed can effectively alter composition of carcass tissues to yield beef that is high in n-3 fatty acids.     

Acoustic communication in fishes: Temperature plays a role

Temperature affects peripheral and central mechanisms of signal production and detection in ectothermic animals. This study reviews for the first time the effects of temperature on acoustic communication in fishes and analyses whether changes in sound properties are coupled to changes in auditory sensitivities. Effects of temperature on sound production have been studied in approximately one dozen families of teleosts. Calling activity increased or was unaffected by temperature, in the latter case probably because seasonal, daily and lunar rhythms also influence mating behaviour and calling. Sound characteristics (pulse repetition rate, fundamental frequency) are positively correlated with temperature if pulses are directly based on sonic muscle contractions. In fishes possessing other sonic mechanisms, the dominant frequency of their pulsatile pectoral sounds may increase as well. Auditory sensitivities were mainly determined in otophysines, which possess enhanced hearing abilities. Studies revealed that hearing increased with temperature, in particular at higher frequencies. We know close to nothing about whether temperature‐dependent changes in sound characteristics are coupled to changes in auditory sensitivity or mate choice. Female midshipman toadfish appear to choose males based on call frequency, which varies with temperature. Future studies need to address several topics: (i) temperature effects on sound production have to be separated from other sources of variation; (ii) effects on hearing need to be studied in many more taxa; (iii) potential negative effects of global warming on acoustic communication (because of temperature coupling) need to be investigated because fish constitute a major source of protein for humans.     

Atomabsorptionsflammenphotometrische Manganbestimmung in Pflanzenaschen

In 3 Lysimetern (Standort Brandis bei Leipzig) mit Bodenmonolithen (Lys. 5 ‐ Braunerde, Lys. 7 ‐Pseudogley, Lys. 10 ‐ Schwarzerde) wurden im September 1994 vergleichend zu Bodenprofilen der Herkunftsflächen schichtweise bis Im Tiefe Untersuchungen zum Vorkommen von Lumbriciden durchgeführt. Die Anzahl der Regenwürmer stieg mit zunehmendem pH‐Wert und C_org‐Gehalt in der Reihenfolge Lys. 10 > Lys. 7 > Lys. 5. Auf Grund des geringen Probenumfangs können keine flächenbezogenen Aussagen abgeleitet werden. Es wurden überwiegend endogäische Würmer gefunden. Es ließ sich nicht mit Sicherheit feststellen, ob die anözischen Würmer in den Lysimetern leben oder sich nur kurzzeitig dort aufhalten. Durchgängige vertikale Regenwurmgänge, wie sie abschnittsweise in verschiedenen Tiefen an senkrechten Schnitten mit Hilfe der Computertomographie nachgewiesen wurden, würden für einen ständigen Aufenthalt anözischer Arten sprechen. Nur dann sind Schlußfolgerungen zur Tätigkeit der Tiefgräber und deren Einfluß auf Infiltration, Nähr‐ und Schadstofftransport möglich. Vergleichsuntersuchungen an Bodenprofilen der Herkunftsflächen zeigten, daß wohl auf Grund der andersartigen Bewirtschaftung nur eine partielle Übereinstimmung im Regenwurmvorkommen zwischen Lysimetern und Bodenprofilen besteht. Da auch viele Ackerböden einen sehr geringen Regenwurmbesatz aufweisen, scheint eine Übertragung der Lysimeterergebnisse auf das Freiland unter diesem Gesichtspunkt möglich zu sein.     

Pyrite oxidation in sediment samples from the German open‐cut brown coal mine Zwenkau: mineral formation and dissolution of silicates

Changes in mineral composition occurring in pyrite‐containing sediments under aerobic conditions are complex and not fully understood. The objective was to study the mineral formation and dissolution of silicates using ion activity product (IAP) calculations and x‐ray diffraction (XRD) on samples of different degrees of pyrite oxidation. Three sediment samples were obtained from the open‐cut brown coal mine of Zwenkau (Saxony, Germany) with low (ZL: 28 g kg^—1), medium (ZM: 67 g kg^—1) and high (ZH: 95 g kg^—1) pyrite contents. These samples were oxidized in the laboratory for 3, 20, 67, and 130 days to obtain four different degrees of pyrite oxidation for each sediment. Sequential batch experiments were carried out for each sediment and oxidation status. Additionally, cation exchange capacities were determined. XRD showed the formation of gypsum (all sediments), jarosite (ZM, ZH), and rozenite (ZH) with increasing pyrite oxidation. IAP calculations suggested an occurrence of gypsum in all samples, of schwertmannite in slightly (ZH) and moderately oxidized (ZM, ZL) samples, and of alunite in a moderately oxidized sample (ZL). The contents of feldspar (ZL), mica/illite (ZL, ZH), and kaolinite (ZH) decreased with increasing pyrite oxidation. The cation exchange capacities of the sediments decreased by 20 (ZH) to 70 mmol_c kg^—1 (ZM). The change in mineral phases with increasing oxidation status of the sediments also changed the activities of Al, Fe, and SO₄ in solution phases. The results obtained in this study suggested the usefulness of predictive models to estimate sediment and water acidification due to pyrite oxidation.     

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.