Analysis of regulation of pentose utilisation in Aspergillus niger reveals evolutionary adaptations in Eurotiales     

Battaglia E  Visser L  Nijssen A  van Veluw GJ  Wösten HA  de Vries RP 《Studies in Mycology》2011,69(1):31-38

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Physiological action of humic substances on microbial cells     

S.A. Visser 《Soil biology & biochemistry》1985,17(4):457-462

By incorporating molecular weight fractions of humic acids of various origins into selective substrates designed for the enumeration of physiological groups of microorganisms, it was found that the presence of humic acids at concentrations of up to 30mgl^?1 normally resulted in increased numbers of soil microbes active within a particular physiological group. Observed increases could be as much as 2000-fold. Microbes in an organic humus-rich soil were more stimulated by humic substances than organisms from a sandy soil.In certain microbes humic substances appeared to induce a change in metabolism, allowing the organisms to proliferate on substrates which previously they could not utilize. Indications were obtained that within the 10–30 mgl^?1 concentration range lower molecular weight humic fractions (approx. 5500 dallons) were more effective than higher molecular weight material. At higher concentrations the reverse was sometimes noticed. Similarly, fulvic acids at concentrations of up to approximately 50mgl^?1 would appear to have a more pronounced physiological effect than humic acids, whereas the latter might be more effective at higher concentrations.The response of certain physiological groups to humic products of natural origin appeared to be comparable to that of surfactants such as Tween and Brij. This would suggest that the physiological action of humic substances is, at least partly, the result of their surface activity, making the membrane one of the prime targets of the physiological action of humics on living cells.  相似文献   

Screening for new sources of resistance to Clavibacter michiganensis subsp. michiganensis (Cmm) in tomato     

Yusuf Sen  Zhu Feng  Henri Vandenbroucke  Jan van der Wolf  Richard G. F. Visser  A. W. van Heusden 《Euphytica》2013,190(2):309-317

Bacterial canker of tomato, caused by Clavibacter michiganensis subsp. michiganensis (Cmm), is considered the most serious bacterial threat, resulting in high damages in production areas. Worldwide, Cmm is subjected to quarantine regulations.There is no cultivar in market containing Cmm resistance genes. This project aimed to screen tomatoes or wild relatives of tomato for resistance to Cmm, to be used for starting breeding programs. We have screened 24 different wild accessions of tomato and found several new tolerant sources: Solanum pimpinellifolium GI.1554, S. parviflorum LA735 and S. parviflorum LA2072. We also confirmed the tolerance which was reported previously in S. peruvianum LA2157, S. peruvianum PI127829, S. peruvianum LA385, S. habrochaites LA407 and S. lycopersicum cv. IRAT L3. No immunity was found. Also accessions showing a low disease score still contained high titers of bacteria as determined by a dilution plating method, using tow selective media. These results were confirmed with a TaqMan real time PCR assay, which was developed to determine and quantify Cmm in planta.  相似文献   

Elucidation of intergenomic recombination and chromosome translocation: meiotic evidence from interspecific hybrids of Lilium through GISH analysis     

Songlin Xie  Munikote S. Ramanna  Richard G. F. Visser  Paul Arens  Jaap M. van Tuyl 《Euphytica》2013,194(3):361-370

Intergenomic exchange has been found to be a normal phenomenon in sexual polyploids. In order to distinguish whether such exchanges are derived from intergenomic recombination or translocation, 13 genotypes of an interspecific hybrid, which were previously used as parents to generate sexual polyploids, were selected for a detailed meiosis analysis. In all genotypes under study, variable numbers of bivalents (0–12) resulting from homoeologous pairing were observed. But in two genotypes (006001-6 and 006001-13), a multivalent which was either a quadri- or a trivalent, as well as a bivalent involving two Asiatic chromosomes, was observed. Two Asiatic chromosomes in 006001-6 which were non-homologous were always found to be associated together, and formed trivalent or quadrivalent with chromosomes from homoeologous genome. This indicated that there was a duplication between these two Asiatic chromosomes. Such a duplication might have resulted from the segregation of a chromosomal translocation between two non-homologous chromosomes in the Asiatic parent ‘Connecticut King’ which was transmitted to the progeny (006001-6). With the exception of two genotypes, in 11 genotypes that formed variable frequencies of bivalents, the homoeologous chromosome pairing and chiasma formation were similar to that between homologous chromosomes. After from the analysis of anaphase I stages it was evident that the expected types of chiasma formation involving non-sister chromatids gave rise to two strand single, two strand double, three strand double, four strand double and multiple exchanges. Whereas these events resulted from locus specific homoeologous exchanges, the translocations resulted from an aberrant form of non-homologous chromosomal exchange of segments. Elucidation of such differences is only possible through the analysis of meiosis using GISH.  相似文献   

Ryegrass staggers     

IJ Cunningham  WJ Hartley 《New Zealand veterinary journal》2013,61(2)

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Descriptive overview of the 2011 epidemic of arboviral disease in horses in Australia     

SE Roche  R Wicks  MG Garner  IJ East  R Paskin  BJ Moloney  M Carr  P Kirkland 《Australian veterinary journal》2013,91(1-2):5-13

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Genetics and molecular mechanisms of resistance to powdery mildews in tomato (Solanum lycopersicum) and its wild relatives     

Alireza Seifi  Dongli Gao  Zheng Zheng  Stefano Pavan  Luigi Faino  Richard G. F. Visser  Anne-Marie A. Wolters  Yuling Bai 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(3):641-665

Powdery mildews (PMs) cause disease in a wide range of plant species including important crops. Taking tomato as an example, here we review findings on the genetic basis and mechanisms of plant resistance to PMs. First, we present a summary of our research on tomato resistance to two PM species, with the focus on Oidium neolycopersici. We discuss the genetics of resistance to this pathogen in tomato. Then, we compare different forms of resistance mediated by different resistance genes based on molecular and cytological data. Also, we provide a comparison between these resistance genes in tomato with those in barley, Arabidopsis and wheat, in order to present a model for the genetic basis of resistance to PMs in plants. We try to accommodate these resistance mechanisms in the current model of plant innate immunity. At the end we discuss possibilities to translate these findings to practical approaches in breeding for resistance to PMs in crops.  相似文献   

The relationship between clinical signs of respiratory system disorders and lung lesions at slaughter in veal calves     

Leruste H  Brscic M  Heutinck LF  Visser EK  Wolthuis-Fillerup M  Bokkers EA  Stockhofe-Zurwieden N  Cozzi G  Gottardo F  Lensink BJ  van Reenen CG 《Preventive veterinary medicine》2012,105(1-2):93-100

The presence and severity of lung lesions recorded post-mortem is commonly used as an indicator to assess the prevalence of respiratory problems in batches of bovines. In the context of a welfare monitoring based on on-farm measures, the recording of clinical signs on calves at the farm would be more convenient than the recording of lung lesions at slaughter. The aim of the present study was to investigate the relationship between clinical respiratory signs at farm and post-mortem analyses of lung lesions observed at slaughter in veal calves. If clinical signs were a good predictor of lung lesions it could be possible to integrate only those measures in a welfare monitoring system. One-hundred-and-seventy-four batches of calves were observed 3 times: at 3 and 13 weeks after arrival of the calves at the unit and at 2 weeks before slaughter. For each batch a maximum of 300 calves was observed and the proportions of calves showing abnormal breathing, nasal discharge and coughing were recorded. Post-mortem inspection was carried out on a sample of lungs belonging to calves from the observed batches. Each examined lung was classified according to a 4-point scale for pneumonia from healthy lung (score 0) to severe lesions (score 3). The clinical signs recorded infra vitam were significantly correlated with moderate and severe lung lesions for observations at 13 weeks and 2 weeks before slaughter and the level of the correlation was highly variable (r(sp) from 0.16 to 0.40). Receiver operating characteristic (ROC) curves were created and the area under the curves showed that batches with a high proportion of lungs with moderate or severe lesions could not be accurately detected by the three clinical signs of respiratory disorders. These results suggest that both clinical signs and post-mortem inspection of lung lesions must be included in a welfare monitoring schemes for veal calves.  相似文献   

Application of DNA markers in parentage verification of Boran cattle in Kenya     

Kios D  van Marle-Köster E  Visser C 《Tropical animal health and production》2012,44(3):471-476

Boran cattle provide livelihood to thousands of households in the arid and semiarid lands of Kenya. Due to their superior adaptive and productive traits in comparison to other breeds of cattle, they have also become a popular choice for breeders in Eastern and Southern Africa. Continued genetic improvement of the breed is important, and therefore accurate performance and pedigree records are required. One hundred seventy-eight pedigree records and blood samples of four Boran stud herds were evaluated for accuracy of parentage allocation using 11 microsatellite markers recommended by ISAG for parentage verification. The panel of the 11 microsatellite markers was found to be highly polymorphic (PIC of 0.6901) with a combined probability of exclusion of 0.9997. The dam misidentification was low ranging between 0% and 5% for the herds tested. The estimated rate of mispaternity however ranged between 4.3% and 80% among the four stud herds, and more than 50% of the offspring of some herds were misidentified. The high rate of mispaternity will have a negative impact on the response to selection. The use of DNA markers for parentage assignment will improve the accuracy of the pedigree records of Boran stud cattle in Kenya and contribute to more accurate selection of superior animals.  相似文献   

Potential for analytic breeding in allopolyploids: an illustration from Longiflorum × Asiatic hybrid lilies (<Emphasis Type="Italic">Lilium</Emphasis>)     

Nadeem Khan  Shujun Zhou  M. S. Ramanna  Paul Arens  Jeronimo Herrera  Richard G. F. Visser  Jaap M. Van Tuyl 《Euphytica》2009,166(3):399-409

Ploidy level and intergenomic recombination was studied in interspecific hybrids between Longiflorum × Asiatic lilies (LA hybrid) backcross to Asiatic parents in order to assess the possibility for analytic breeding in lily. By backcrossing the diploid (2n = 2x = 24) F1 interspecific hybrid between Longiflorum × Asiatic lilies to Asiatic parents, 104 BC1 progeny plants were produced. Among these, there were 27 diploids, 73 triploids (2n = 2x = 36) and 4 aneuploids (2x − 1, 2x + 2 or 2x + 3). In addition, by backcrossing triploid BC1 (LAA) plants to diploid Asiatic parents in 2x − 3x and reciprocal combinations, 14 diploid BC2 progenies were produced. Genomic in situ hybridization (GISH) was performed to study the intergenomic recombination and karyotype composition. GISH indicated extensive intergenomic recombination among the chromosomes in LA hybrids. A large number of Longiflorum chromosomes were transmitted to the BC1 progenies from LA hybrids. However, very few Longiflorum chromosomes were transmitted from the BC1 triploid (LAA) plants to the BC2 progenies. The occurrence of diploid plants in the BC progenies of LA hybrids has opened the prospects of analytic breeding in lilies. In this approach, the selection of superior genotypes can be carried out at the diploid level and polyploid forms are synthesized from superior diploid parents. The advantages of analytic breeding are evident: (a) a maximum level of heterozygosity can be attained in the synthetic polyploids and (b) introgression can be achieved with a minimum of linkage drag. Based on GISH results the potential application of analytic breeding in lily allopolyploids has been discussed.  相似文献