The formation of natural levees as a disturbance process significant to the conservation of riverine pastures

Disturbances and patch dynamics are inherent to many ecosystems of the world, especially in the riparian zone. This paper describes the influence of natural levee overbank deposition on riverine grasslands along the meandering River Dinkel (The Netherlands). Here, the rare vegetation type Diantho-Armerietum, characterised by Dianthus deltoides, Thymus pulegioides, Pimpinella saxifraga and Galium verum, has been identified as important to nature conservation. Diantho-Armerietum shows a strong preference for dry, nutrient poor, sandy and relatively young soils, with an elevation approximately 30–50 cm above bankfull discharge level, corresponding to a flooding frequency of 2–3 times per year. The lower zones are strongly influenced by nutrient-rich water, whereas the higher zones are vulnerable to soil acidification. In the intermediate zone, soil development may be reset due to the supply of calcium, adsorbed to recently deposited levee sands. Since deposition rates will decrease with increasing levee heights, new levees are regularly needed to stop the decline of this floriferous vegetation type. The formation of new natural levees is favoured by the occurrence of meander cutoffs, causing a cyclic succession of landforms along the river. Therefore a conservation strategy for this vegetation type needs to aim at the rehabilitation of the natural levee disturbance process, in conjunction with encouraging the meandering of the river.     

Assessment of Partial Resistance to Powdery Mildew (Podosphaera pannosa) in a Tetraploid Rose Population Using a Spore-suspension Inoculation Method

Powdery mildew (Podosphaera pannosa) is the most important fungal disease in greenhouse roses and is in practice controlled by fungicides. The creation of novel cultivars with durable resistance to powdery mildew is highly desirable. To understand the inheritance of mildew resistance, a tetraploid rose population with a size of 181 seedlings was obtained by crossing two tetraploid genotypes each having partial resistance. The population and its parents were tested under greenhouse conditions with two well-defined monospore isolates (2 and F1) using artificial inoculation with spore suspensions. Disease score at 11 days post-inoculation, latent period and rate of symptom development were used to describe seedling resistance. The tests for both isolates exhibited a wide and significant variation among genotypes for resistance. The distribution of the genotypic means of the disease scores was continuous and showed a considerable transgression. Statistical analysis, scatter plot of disease scores for the isolates, and correlation analyses indicated that the two isolates differed in pathogenicity. The outcome of the tests showed that the inoculation assay with spore suspensions was a reliable and effective way to screen large numbers of genotypes under greenhouse conditions for genetic and breeding studies. This is the first report on spore-suspension inoculation to be used successfully in rose.     

Endoscopy in birds

Endoscopic examination is described as a valuable diagnostic method in birds. In the introduction, reference is made to the literature on this subject. Apart from the classical approaches, alternative sites to enter the thoraco-abdominal cavity in birds are discussed. The basic equipment for endoscopy in birds is described and a new biopsy forceps which makes a secondary puncture redundant is introduced. After a discussion of the indications and complications, the value of the endoscopic examination is compared with other diagnostic methods for the diagnosis of avian tuberculosis in birds.     

Paramyxovirus disease in racing pigeons. Clinical aspects and immunization. A report from the Netherlands

Since 1981 a highly contagious viral disease causing high morbidity and low mortality in racing pigeons has spread over Europe. The virus belongs to the avian paramyxovirus sero group I. Clinical signs include watery droppings, polydypsia and neurologic signs in a high proportion of infected animals. Definitive diagnosis can be made by virus isolation in cell cultures or chicken embryos, and virus identification by haemagglutination and haemagglutination inhibition (HI) tests. The HI test, using sera from suspected animals, is a useful clinical tool to confirm the diagnosis. The most important differential diagnosis is salmonellosis. Good immunity against this disease can be acquired by subcutaneous vaccination with an inactivated oil adjuvant poultry NDV-vaccine. For the benefit of pigeon racing a plea is made for compulsory vaccination in countries in which the disease is endemic.     

Residential movements of top predators in Chile’s most isolated marine protected area: Implications for the conservation of the Galapagos shark,Carcharhinus galapagensis,and the yellowtail amberjack,Seriola lalandi

1. Marine protected areas (MPAs) are becoming a widely used tool for the conservation of biodiversity and for fishery management; however, most of these areas are designed without prior knowledge of the basic ecological aspects of the species that they are trying to protect.
2. This study investigated the movement of two top predators: the Galapagos shark, Carcharhinus galapagensis, and the yellowtail amberjack, Seriola lalandi, in and around the Motu Motiro Hiva Marine Park (MMHMP) using MiniPAT satellite tags to determine the effectiveness of this MPA for the protection of these species.
3. The Galapagos sharks (n = 4) spent most of their tag deployment periods inside the MMHMP. However, high intraspecific variability was observed in their movement dynamics. Daily individual maximum movements ranged from 17 to 58 km and the maximum distance from Salas y Gómez Island, the only emergent island within the MMHMP, ranged from 31 to 139 km.
4. The maximum linear distance travelled for a female juvenile Galapagos shark (152 cm total length) was 236 km, which is greater than the maximum distance previously documented for juveniles of this species (<50 km).
5. For the yellowtail amberjack (n = 1), 91% of the satellite geolocations were within the MMHMP, with a maximum daily distance travelled of 6 km. The maximum distance travelled between points was 111 km and the maximum distance from Salas y Gómez Island was 62 km.
6. All archival tagged fish spent most of their time at depths of <50 m and never left the epipelagic zone. Daytime versus night-time differences were pronounced in all individuals but showed high interindividual variability.
7. This study provides a baseline on the movement of these two top predators in the MMHMP and provides valuable insights for the creation of MPAs in the region and elsewhere.

     

Vigour evaluation for genetics and breeding in rose

Breeding of cut and pot rose cultivars for efficient production under low-energy conditions in greenhouses will be facilitated by understanding the inheritance of vigour. To get insight into the genetic variation of vigour-related traits, a diploid rose population was employed for an evaluation study in greenhouses in The Netherlands and Denmark. For all the traits investigated the population showed a continuous quantitative variation as well as a considerable transgression. For most of the traits, the genetic variation found among the tested entries was highly significant and tended to be large in comparison to the effects of genotype by environment interaction. The heritability based on means of the traits was high and ranged from 68 to 92%. Strong simple correlations (r = 0.65 to 0.95) were found among the traits shoot length, leaf area, leaf dry weight, stem dry weight, total dry weight and growth rate. The total dry weight and leaf area are suggested to be good parameters for early selection of rose genotypes with vigorous growth under suboptimal growth conditions.     

The theoretical proportion of the donor genome in near-isogenic lines of self-fertilizers bred by backcrossing

Summary The length was estimated of the chromosome segment with the desired marker gene introgressed from a donor by backcrossing into a recurrent parent. It was found that, for instance, for a chromosome with a length of 100 cM the length of the segment is 32 cM in BC6.These estimates were compared with those made by Hanson (1959). Two corrections proved to be necessary.The implications for breeders and researchers are discussed. Differences between two near-isogenic lines often ascribed to the difference in genotype at the marker locus, may also be caused by genes linked to the marker gene and dragged into the backcross product.     

Effects of lactoferrin, phytic acid, and EDTA on oxidation in two food emulsions enriched with long-chain polyunsaturated fatty acids

The influence of the addition of metal chelators on oxidative stability was studied in a milk drink and in a mayonnaise system containing highly polyunsaturated lipids. Milk drinks containing 5% (w/w) of specific structured lipid were supplemented with lactoferrin (6-24 muM) and stored at 2 degrees C for up to 9 weeks. Mayonnaise samples with 16% fish oil and 64% rapeseed oil (w/w) were supplemented with either lactoferrin (8-32 muM), phytic acid (16-124 muM), or EDTA (16-64 muM) and were stored at 20 degrees C for up to 4 weeks. The effect of the metal chelators was evaluated by determination of peroxide values, secondary volatile oxidation products, and sensory analysis. Lactoferrin reduced the oxidation when added in concentrations of 12 muM in the milk drink and 8 muM in the mayonnaise, whereas it was a prooxidant at higher concentrations in both systems. In mayonnaise, EDTA was an effective metal chelator even at 16 muM, whereas phytic acid did not exert a distinct protective effect against oxidation. The differences in the equimolar effects of the metal chelators are proposed to be due to differences in their binding constants to iron and their different stabilities toward heat and low pH.     

Use of component analysis in QTL mapping of complex crop traits: a case study on yield in barley

Genes contributing to the quantitative variation of a complex crop trait can be numerous. However, using existing approaches, the number of quantitative trait loci (QTL) detected for a trait is limited. Therefore, rather than looking for QTL for a complex trait itself, determining QTL for underlying component traits might give more information. In this study the potential of component analysis in QTL mapping of complex traits was examined using grain yield in spring barley as an example. Grain yield was divided into three components: number of spikes/m², number of kernels/spike, and 1000‐kernel weight. These traits were measured for individuals of a recombinant inbred‐line population in field trials conducted over 2 years. By the use of an approximate multiple QTL model, one to eight QTL were detected for each trait in a year. Some QTL were mapped to similar positions in both years. Almost all QTL for yield were found at the position of or in close proximity to QTL for its component traits. A number of QTL for component traits were not detected when yield itself was subjected to QTL analysis. However, relative to the QTL for yield itself, all component‐trait QTL did not explain the variation in yield better. The results in relation to the potential of using component analysis in studying complex crop traits are discussed.