Genetic variation underlying kernel size,shape, and color in two interspecific S. bicolor2 × S. halepense subpopulations

Genetic Resources and Crop Evolution - Throughout the history of sorghum domestication, kernel traits have been subject to extensive selection. Breeding of grain sorghum is highly dependent on...     

Immunity to canine adenovirus respiratory disease: effect of vaccination with an inactivated vaccine

Nine puppies without maternal antibody to canine adenovirus (CAV) were divided into two groups. The first consisted of six puppies, each of which was given two doses of a commercial inactivated CAV-1 vaccine, 14 days apart. Eight days after administration of the second dose of vaccine, all six puppies, together with the second group, consisting of three unvaccinated controls, were challenged with an aerosol of virulent CAV-2. One dog from each group was killed on the third, fifth and 10th days after challenge and the three additional vaccinates killed at intervening times. All of the dogs developed respiratory signs, mainly coughing and tachypnoea, but the vaccinated dogs made a more rapid recovery. The lungs of both groups were consolidated, the areas affected being more extensive in the controls, and histological examination revealed the main lesion to be a severe necrotising bronchiolitis. Virus was isolated from the respiratory tissues and from throat swabs collected from both groups of dogs. The presence of neutralising antibody in the serum was not, of itself, sufficient to control viral replication and oblate the disease.     

The effects of cattle sex on carcass characteristics and longissimus muscle palatability

Two experiments were conducted to determine the effects of sex on carcass traits and cooked beef steak palatability. In Exp. 1, steers (n = 99), heifers (n = 51), and intravaginally spayed heifers (n = 46) were fed a high-energy diet for 161 d. No implants were administered, and heifers were not fed melengestrol acetate to suppress estrus. In Exp. 2, 60 steers and 60 intact heifers from the same ranch source used in Exp. 1 were fed in 2 locations (sites 1 and 2). All management factors were equal across experiments except that intact heifers were fed melengestrol acetate to suppress estrus in Exp. 2. Steers in Exp. 1 were 25 kg heavier (P < 0.01) in HCW than heifers at comparable (P = 0.39) carcass fat thickness. Spayed heifers (Exp. 1) had a 5.7% smaller (P < 0.05) LM area compared with steers and intact heifers, which were similar. In Exp. 2, there was no difference (P = 0.2) in carcass weight, and heifers had greater (P < 0.01) 12th rib fat thickness compared with steers. Calculated yield grades were similar (P = 0.21) among treatments in Exp. 1 and tended (P = 0.08) to be greater for heifers compared with steers in Exp. 2. In Exp. 1, USDA quality grades and marbling scores were lower (P < 0.01) for steers compared with intact and spayed heifers, which were similar. The effects of sex on tenderness were examined at a common level of fat-thickness and marbling by covariate analysis. Steaks from steers, compared with those from nonimplanted, intact heifers, in the 2 experiments combined were: (a) superior (P < 0.05) in 2 of 9 palatability assessments when subcutaneous fat thickness (at the 12th rib) was adjusted to a common level, and (b) superior (P < 0.05) in 6 of 9 palatability assessments when marbling score was adjusted to a common level. In Exp. 1, steaks from nonimplanted steers compared with those from nonimplanted spayed heifers were: (a) superior (P < 0.05) in 0 of 8 palatability assessments when subcutaneous fat thickness (at the 12th rib) was adjusted to a common level, and (b) superior (P < 0.05) in 3 of 8 palatability assessments when marbling score was adjusted to a common level. These findings suggest that sex should be added to the list of antemortem factors contributing to variation in cooked beef steak tenderness. However, more research is needed to precisely identify those factors contributing to the lower tenderness observed for steaks from heifer carcasses.     

Clindamycin hydrochloride and clavulanate-amoxycillin in the treatment of canine superficial pyoderma.

A masked, randomised, controlled clinical trial for the treatment of canine superficial pyoderma was undertaken. Dogs with a clinical diagnosis of superficial pyoderma, supported by bacterial culture were admitted to the trial and randomly assigned to treatment with either clindamycin hydrochloride at 5.5 mg/kg twice daily or clavulanate-amoxycillin at 12.5 mg/kg twice daily. After 21 days the animals were re-assessed, and therapy was continued for a further 21 days in the dogs with persistent lesions if bacterial culture demonstrated continued sensitivity. Twenty-nine dogs were treated with clindamycin hydrochloride and 27 with clavulanate-amoxycillin. Complete cure was obtained after three weeks in 17 (59 per cent) of the clindamycin-treated cases, but in only eight (30 per cent) of the clavulanate-amoxycillin treated group. Clindamycin was significantly more effective than clavulanate-amoxycillin for the treatment of superficial pyoderma in dogs.     

Defoliation and fertiliser influences on the soil microbial community associated with two contrasting Lolium perenne cultivars

The influence of repeated defoliation on soil microbial community (SMC) structure and root turnover was assessed in two contrasting Lolium perenne cultivars (AberDove and S23) grown in fertilised (+F) and non-fertilised (NF) soil. BiOLOG sole carbon source utilisation profiles (SCSUPs) indicated consistently greater potential carbon utilisation in defoliated (+D) compared to non-defoliated (ND) soils regardless of cultivar and fertiliser, and was accounted for in a variety of substrate groups (sugars, carboxylic, amino and phenolic acids). Potential carbon utilisation was also stimulated in +F compared to NF soils, primarily through increased potential utilisation of carboxylic acids. PLFA indicators for the bacterial biomass did not significantly differ between cultivar, soil fertilisation, or defoliation. Defoliated swards grown in fertilised soil (+F+D) had a higher fungal:bacterial ratio and a greater bacterial stress index (cy19:0/18:1w7c), compared to that of +F ND, NF ND and NF+D, and regardless of cultivar. Overall SMC structure (canonical variate (CV) analysis of PLFAs) discriminated based on cultivar, defoliation and soil fertilisation. Primary discrimination of the SMCs could be related to differences in root density and total plant biomass, and in the case of NF soils, secondary community shifts, evident with defoliation, related to root disappearance over the growing season. Despite the strong common effects of defoliation, and to a lesser extent soil fertilisation, cultivar specific drivers of the soil microbial community were maintained, resulting in consistent, but subtle, discrimination of the SMC associated with the contrasting L. perenne cultivars.     

The effect of the temperature of potato tubers on the incidence of mechanical damage during grading and of gangrene (caused byPhoma exigua) during storage

Summary The amount of mechanical damage evident on potatoes graded by reciprocating square-mesh riddles decreased with increase in tuber temperature prior to grading. In a separate experiment, the extent of rotting by gangrene as a result of artificial infection of the surface of injured tubers was reduced in most cases with increase in tuber temperature at the time of inoculation. The incidence of gangrene in consignments of seed potatoes was reduced by storage at 15 to 17°C for about one week (five to ten days) after grading or after delivery.

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Zusammenfassung Sichtbarer mechanischer Schaden an Knollen, die in einem Raum mit Temperaturen von 6 und 11°C durch Schütteln von Quadratnetzsieben sortiert wurden, wurde mit dem Ansteigen der Knollentemperatur von 0 auf 16°C vor dem Sortieren vermindert. Die Temperatur der Knollen hatte weniger Einfluss auf den Schadenindex, wenn die Knollen bei h?herer Raumtemperatur sortiert wurden (Tabelle 1). Bei Kartoffeln mit verschiedenen Knollentemperaturen, die aus einer bestimmten H?he herunterfielen, gesiebt und angesteckt wurden durch Inokulation der Oberfl?che, nahm das Ausmass des durchPhoma-Knollenf?ule verfaulten Gewebes bei zunehmender Knollentemperatur ab (Tabelle 6). Das Vorkommen vonPhoma-Knollenf?ule in Pflanzkartoffelsendungen von Gutsbetrieben im n?rdlichen Schottland wurde in den meisten F?llen vermindert durch Lagerung bei 15 bis 17°C w?hrend ungef?hr einer Woche (5 bis 10 Tage) nach dem Sortieren oder nach Auslieferung der Sendung (Tabellen 7, 8 und 9).

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Résumé L'augmentation de la température du tubercule de 0 à 16° avant le calibrage réduit les dégats mécaniques visibles aux tubercules calibrés aux températures ambiantes de 6 à 11°C, au moyen de cribles à mouvement alternatif et ⦏ mailles carrées. La température du tubercule a moins d'effet sur l'indice des dommages quand les tubercules sont calibrés à une température ambiante plus élevée (Tableau 1). Chez des tubercules à différentes températures, tombés d'une certaine hauteur, calibrés et infectés par inoculation de la surface, le degré de pourriture des tissus causée par la gangrène diminue avec l'accroissement de la température dans le tubercule (Tableau 6). L'apparition de la gangrène dans les lots de plants de pomme de terre provenant des fermes du Nord de l'Ecosse est diminuée dans la plupart des cas par la conservation à des températures de 15 à 17°C pendant environ une semaine (5 à 10 jours) après calibrage ou après livraison (Tableau 7, 8, 9).

     

High proportion of diploid hybrids produced by interspecific diploid × tetraploid <Emphasis Type="Italic">Sorghum</Emphasis> hybridization

A perennial version of grain sorghum [S. bicolor (L.) Moench] would create opportunities for greatly reducing tillage and preventing soil degradation. Efforts to select for perenniality and grain production among progeny of hybrids between S. bicolor (2n = 20) and the weedy tetraploid perennial S. halepense (L.) Pers. (2n = 40) are complicated in that F₁ hybrids produced by diploid × tetraploid sorghum crosses are usually tetraploid. In 2013, a set of random pollinations between 19 diploid cytoplasmic male-sterile inbred lines and 43 tetraploid perennial plants produced 165 F₁ hybrid plants, more than 75% of which had highly atypical plant, panicle, and seed phenotypes. Phenotypic segregation in F₂ populations derived from atypical hybrids was also anomalous. Examination of mitotic metaphase cells in F₁ or F₂ root tips revealed that 129 of the 165 hybrids were diploid. Parentage of the diploid progenies was confirmed using simple-sequence repeat analysis. The mechanism by which diploid hybrids arise from diploid × tetraploid crosses is unknown, but it may involve either production of monohaploid (n = 10) pollen by the tetraploid parent or chromosome elimination during early cell divisions following formation of the triploid zygote. The ability to produce diploid germplasm segregating for S. bicolor and S. halepense alleles could have great utility, both for the development of perennial sorghum and for the improvement of conventional grain sorghum.     

Impact of plant species and atmospheric CO2 concentration on rhizodeposition and soil microbial activity and community composition

Both plant species and CO₂ concentration can potentially affect rhizodeposition and consequently soil microbial activity and community composition. However, the effect differs based on plant developmental stage. We focused on the effect of three plant species (forbs, grasses, and N₂‐fixers) at an early stage of development on root C deposition and fate, soil organic matter (SOM) mineralization and soil microbial community composition at ambient (aCO₂) and elevated (eCO₂) CO₂ levels. Plants were grown from seed, under continuous ¹³C‐labelling atmospheres (400 and 800 µmol mol^?1 CO₂), in grassland soil for three weeks. At the end of the growth period, soil respiration, dissolved organic C (DOC) and phospholipid fatty acid (PLFA) profiles were quantified and isotopically partitioned into root‐ and soil‐derived components. Root‐derived DOC (0.53 ± 0.34 and 0.26 ± 0.29 µg mL soil solution^?1) and soil‐derived CO₂ (6.14 ± 0.55 and 5.04 ± 0.44 µg CO₂‐C h^?1) were on average two times and 22% higher at eCO₂ than at aCO₂, respectively. Plant species differed in exudate production at aCO₂ (0.11 ± 0.11, 0.10 ± 0.18, and 0.58 ± 0.58 µg mL soil solution^?1 for Plantago, Festuca, and Lotus, respectively) but not at eCO₂ (0.20 ± 0.28, 0.66 ± 0.32, and 0.75 ± 0.15 µg mL soil solution^?1 for Plantago, Festuca, and Lotus, respectively). However, no differences among plant species or CO₂ levels were apparent when DOC was expressed per gram of roots. Relative abundance of PLFAs did not differ between the two CO₂ levels. A higher abundance of actinobacteria and G‐positive bacteria occurred in unplanted (8.07 ± 0.48 and 24.36 ± 1.18 mol%) and Festuca‐affected (7.63 ± 0.31 and 23.62 ± 0.69 mol%) soil than in Plantago‐ (7.04 ± 0.36 and 23.41 ± 1.13 mol%) and Lotus‐affected (7.24 ± 0.17 and 23.13 ± 0.52 mol%) soil. In conclusion, the differences in root exudate production and soil respiration are mainly caused by differences in root biomass at an early stage of development. However, plant species evidently produce root exudates of varying quality affecting associated microbial community composition.