Molecular identification of the powdery mildew fungus infecting rubber trees in China

Powdery mildew is a foliar disease of rubber trees. It is one of the most important leaf diseases in rubber plantations worldwide. The causal agent of this powdery mildew, previously known as Oidium heveae, has been identified under various names. To precisely identify the causal agents of this disease, 57 conidial samples were collected from 2013 to 2017 in Hainan, Yunnan and Guangdong provinces, the main rubber tree planting regions in China. Based on morphological observations using light and scanning electron microscopy, pathogenicity testing, and nrDNA ITS and 28S sequences, Erysiphe quercicola is suggested as the only causal agent of rubber tree powdery mildew in China.     

Alley cropping of maize with calliandra and leucaena in the subhumid highlands of Kenya: Part 2. Biomass decomposition, N mineralization, and N uptake by maize

A major challenge in developing agroforestry approaches that utilize tree-leaf biomass for provision of N to crops is to ensure synchrony between the N released from decomposing prunings and N demand by crops. A study was conducted in the subhumid highlands of Kenya to assess the rate of decomposition and mineralization of soil-incorporated Calliandra calothyrsus Meissner (calliandra) and Leucaena leucocephala (Lam.) de Wit (leucaena) tree biomass and maize roots (Zea mays L.) both in an alley cropping and a sole cropping system. The amount of mineralized N peaked four weeks after planting (WAP) maize in all the treatments during both seasons of 1995. Cumulative mineralized N at week 20 ranged from 114 to 364 kg N ha⁻¹ season⁻¹, the absolute control treatment giving the lowest and the prunings-incorporated treatments giving the highest amounts in the two seasons. Total N uptake by maize, ranging from 42 to 157 kg ha⁻¹ season⁻¹, was lowest in the 'alley-cropped, prunings-removed' treatments, and highest in the 'non alley-cropped-prunings-incorporated' treatments. The apparent N recovery rate by maize was highest in the fertilizer applied treatments in the two seasons. Decomposition rate constants (kD) ranged from 0.07 to 0.21 week⁻¹, and the rates among the different plant residues were as follows: leucaena < calliandra < maize roots. Nitrogen release rate constants (kN), ranging from 0.04 to 0.25 week⁻¹, followed a similar pattern as the rate of decomposition with leucaena releasing the highest amount of N followed by calliandra and lastly by maize roots. This revised version was published online in June 2006 with corrections to the Cover Date.     

ATLes: the strategic application of Web-based technology to address learning objectives and enhance classroom discussion in a veterinary pathology course

A case-based program called ATLes (Adaptive Teaching and Learning Environments) was designed for use in a systemic pathology course and implemented over a four-year period. Second-year veterinary students working in small collaborative learning groups used the program prior to their weekly pathology laboratory. The goals of ATLes were to better address specific learning objectives in the course (notably the appreciation of pathophysiology), to solve previously identified problems associated with information overload and information sorting that commonly occur as part of discovery-based processes, and to enhance classroom discussion. The program was also designed to model and allow students to practice the problem-oriented approach to clinical cases, thereby enabling them to study pathology in a relevant clinical context. Features included opportunities for students to obtain additional information on the case by requesting specific laboratory tests and/or diagnostic procedures. However, students were also required to justify their diagnostic plans and to provide mechanistic analyses. The use of ATLes met most of these objectives. Student acceptance was high, and students favorably reviewed the online 'Content Links' that made useful information more readily accessible and level appropriate. Students came to the lab better prepared to engage in an in-depth and high-quality discussion and were better able to connect clinical problems to underlying changes in tissue (lesions). However, many students indicated that the required time on task prior to lab might have been excessive relative to what they thought they learned. The classroom discussion, although improved, was not elevated to the expected level-most likely reflecting other missing elements of the learning environment, including the existing student culture and the students' current discussion skills. This article briefly discusses the lessons learned from ATLes and how similar case-based exercises might be combined with other approaches to enhance and enliven classroom discussions in the veterinary curriculum.     

Maturation of bovine dendritic cells by lipopeptides

The response of DC, and the subsequent stimulation of T cells, is an essential part of the initiation of immune responses following microbial challenge. The response of human DC to bacterial lipopeptides is mediated by toll-like receptor 2, and is characterised by DC maturation and the enhanced capacity to stimulate of T cells. We report here that bovine DC are also induced to mature following lipopeptide stimulation. Exposure of DC to the model lipopeptide Pam3CSK4 was associated with increased expression of MHC, costimulatory molecules, and enhanced secretion of IL-12 and TNFalpha. Lipopeptide-matured DC were superior in their ability to induce T cell activation and IFNgamma secretion. In contrast, exposure of MPhi to lipopeptides induced down-regulation of MHC expression and much lower increases in IL-12 secretion. A lipopeptide derived from the sequence of a relevant mycobacterial lipoprotein, MPB83, also influenced bovine DC by stimulating increases in IL-12 and TNFalpha secretion. These different changes in bovine DC and MPhi may have important implications for immune responses induced following bacterial infection with uptake of microbes by DC resulting in potentiation of their immunostimulatory capacity and uptake by MPhi having a much less marked effect on immune responses.     

Use of khesari (lathyrus sativus) in chick diets

1. Broiler chicks, reared for 14 d in battery brooders, were given diets containing 100, 222 or 367 g/kg of khesari meal (Lathyrus sativus) in three different experiments.

2. Birds receiving raw khesari consumed less food and grew more slowly than birds receiving a maize‐soya diet. Supplementation with DL‐methionine did not improve the nutritive value of khesari diets, but the inclusion of L‐tryptophan produced a positive response.

3. When khesari was either autoclaved or heated in a commercial “ micronisation “ process and then incorporated at 367 g/kg in a balanced chick diet, growth and efficiency of food utilisation were at least equal to those obtained with a maize‐soya diet.

4. Khesari depresses chick growth when fed raw, but is an excellent protein source for growing chicks if fed after a suitable heat treatment. Since the component in raw khesari which is toxic to chickens is heat‐labile, it is probably not the same factor that is responsible for human lathyrism.     

The energetic cost of limbless locomotion

The net energetic cost of terrestrial locomotion by the snake Coluber constrictor, moving by lateral undulation, is equivalent to the net energetic cost of running by limbed animals (arthropods, lizards, birds, and mammals) of similar size. In contrast to lateral undulation and limbed locomotion, concertina locomotion by Coluber is more energetically expensive. The findings do not support the widely held notion that the energetic cost of terrestrial locomotion by limbless animals is less than that of limbed animals.     

Mineral status of beef cattle in Papua New Guinea

Groups of 22 steers grazed eight diverse environments in Papua New Guinea for one year. Haemoglobin, packed cell volume, MCHC, plasma albumen, calcium, magnesium, phosphorus, zinc, copper and saliva sodium and potassium were measured; half of each group received cobalt supplements. Growth rate was measured. Cobalt deficiency was tentatively diagnosed at two sites, sodium deficiency at five sites and phosphorus at three with two other sites marginal. Sodium supplementation at the three most affected sites corrected sodium status and increased growth rate. Additionally, at two of these sites plasma phosphorus concentration increased to more normal levels presumably due to increased appetite. Statistically significant differences between sites occurred in the concentrations of other minerals but were not related to growth rates. The significance of these results is discussed in relation to assessment of mineral status in beef cattle.     

A hypothesis to explain the relationship between low-temperature treatment,gibberellin activity,curd initiation and maturity of cauliflower

The effects of cold-treating young cauliflower plants (Brassica oleracea var. botrytis L.) of the cultivars ‘Lero’, ‘Lawyna’, ‘Novo’ and ‘Janavon’, on gibberellin activity and the spreads of curd initiation and maturity are described and discussed in relation to other similar work.Exposure of plants to 0°C for 15 days increased gibberellin activity in the apices of ‘Lero’ and ‘Lawyna’ plants. The spreads of curd initiation and maturity of ‘Lawyna’ were significantly reduced by cold-treatment at 0°C, but ‘Lero’ was not affected, possibly because plants had initiated too many leaves and were thus beyond the stage receptive to low-temperature treatment. This treatment had no effect on gibberellin activity nor on the spreads of curd initiation and maturity of ‘Novo’ or ‘Janavon’, probably because plants had not reached the sensitive stage when cold-treated.It is postulated that the phase of growth during which the curd-initiation period can be shortened by cold treatment is specific for each cultivar, and other data were used to confirm this. It seems likely that the receptive phase occurs at higher leaf-numbers with cultivars which take longer to initiate curds.     

A case report of <Emphasis Type="Italic">Mycoplasma wenyonii</Emphasis> associated immune-mediated haemolytic anaemia in a dairy cow

Background and case presentation

A three year old, second lactation Holstein dairy cow presented to the Scottish Centre for Production Animal Health and Food Safety, Glasgow University Veterinary School in November 2014 with a history of post-calving vulval/vaginal bleeding nine days prior to presentation, followed by a sudden reduction in milk yield. Subsequent investigations resulted in a diagnosis of immune-mediated haemolytic anaemia secondary to infection with Mycoplasma wenyonii.

Conclusion

This report of a novel presentation of Mycoplasma wenyonii in a dairy cow illustrates the need to consider M.wenyonii as a potential differential diagnosis when a cow presents with anaemia and will discuss the potential implications of the condition at herd-level.