Gene Flow Analysis of Phytophthora porri Reveals a New Species: Phytophthora brassicae Sp. Nov.     

Willem A. Man in 't Veld  Arthur W.A.M. de Cock  Elena Ilieva  C. André Lévesque 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(1):51-62

Isozyme analysis and sequence analysis of the internal transcribed spacer regions (ITS-1 and ITS-2) and the 5.8S subunit of the ribosomal DNA gene repeat were used to examine whether isolates of Phytophthora porri from Allium and Brassica represent a single homogeneous species. Twenty-six strains of P. porri, 16 strains isolated from the genus Allium, and 10 strains isolated from the genus Brassica, were analyzed using malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH) and lactate dehydrogenase (LDH), represented altogether by four putative loci (Mdh-2, Idh-1, Idh-2, and Ldh-2). Isozyme analysis revealed that strains isolated from Allium contained five private alleles at three isozyme loci (Ldh-2 ⁸³, Ldh-2 ¹⁰⁴, Idh-1 ¹⁰⁸, Idh-1 ¹¹², and Idh-2 ⁹⁸), whereas six different alleles were observed at four isozyme loci (Ldh-2 ⁸⁵, Ldh-2 ¹⁰⁰, Ldh-2 ¹¹⁴, Idh-1 ¹⁰⁰, Idh-2 ¹⁰⁰, and Mdh-2 ¹¹¹) in strains obtained from Brassica. The heterozygosity at the Ldh-2 locus, differing in allele composition, however, between strains from Allium and Brassica, was present in all strains, indicating that it is probably fixed. Sequence analysis of the ITS regions and the 5.8S subunit showed consistent differences between isolates from Allium and isolates from Brassica. Based on isozyme data, ITS sequence analysis and formerly published differences in restriction enzyme patterns of mitochondrial DNA, morphology and pathogenicity, it was concluded that the isolates of P. porri Foister did not represent a homogeneous species. Isolates from Brassica constitute a distinct species which is described here as P. brassicae sp. nov. It was inferred from isozyme patterns, which were in no case intermediate between the two species, that P. porri and P. brassicae do not hybridize and are reproductively isolated by barriers to gene flow.  相似文献   

Arthroscopic Removal of Large Extensor Process Fragments in 18 Friesian Horses: Long‐Term Clinical Outcome and Radiological Follow‐Up of the Distal Interphalangeal Joint          下载免费PDF全文

Ellen Compagnie  Frerik ter Braake  Natascha de Heer  Willem Back 《Veterinary surgery : VS》2016,45(4):536-541

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Factors associated with variation in Neospora caninum bulk-milk S/P ratios in initially bulk-milk negative testing Dutch dairy herds     

Bartels CJ  van Schaik G  van Maanen K  Wouda W  Dijkstra T 《Preventive veterinary medicine》2007,81(4):265-273

We conducted a study on 81 initially bulk-milk ELISA negative dairy herds taken from a random sample of Dutch dairy herds to evaluate variation in bulk-milk S/P ratios and to study reasons for bulk-milk conversion. These herds were repeatedly (3-month intervals) tested between April 2004 and August 2005 and serostatus of all animals had previously been established as negative (N), low-positive (LP) or high-positive (HP). Of these herds, herd- and test-related factors associated with variation in sample over positive (S/P) ratios were analysed using a multivariable linear-mixed model with ‘herd’ as random effect. In addition, changes of animal serostatus in converting herds were described. S/P ratios were calculated as the optical density of the bulk-milk sample minus the optical density of the negative serum control divided by the difference in optical density between the positive and negative serum control.

Sixteen bulk-milk conversions in 12 dairy herds were seen with few indications of serological conversion in lactating cattle except for one herd in which recrudescence of infection appeared likely in nine cows. The effect of HP serostatus on bulk-milk S/P ratio was 2–3 times stronger compared with LP serostatus. In addition, bulk-milk S/P-ratio increased when the proportion of HP animals between 1 and 60 days in milk increased and decreased when the average milk-production level of the herd increased. Besides these herd-related factors, the use of different ELISA-testkits between test rounds had a significant effect on the S/P-ratio in bulk-milk samples.  相似文献   

Seasonal turnover and insights into the overwintering biology of wireworms (Coleoptera: Elateridae) in the Canadian Prairies     

Ivan Drahun  Elise A. Poole  Katherine A. Hunt  Willem G. van Herk  Christophe M. LeMoine  Bryan J. Cassone 《Pest management science》2023,79(2):526-536

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Water requirement of Aloe vera in a dry caribbean climate     

Willem B. M. Genet  Cok A. M. van Schooten 《Irrigation Science》1992,13(2):81-85

Summary As hardly any data can be found on the water requirement and yield response to water of Aloe vera, an irrigation experiment on transplanted aloe poles was conducted on the Caribbean island of Aruba. Compared to non-irrigated treatments irrigation shows a positive influence on growth, number of developed leaves, raw gel figure and gel production per plant. The amount of irrigation water to apply can be best calculated based on crop coefficients (K_c) between 0.20 and 0.30. Treatment based on a K_c value higher than 0.30 did not further increase production. A lysimeter study conducted over a relatively short period revealed that the crop coefficient for Aloe vera varied between 0.25 and 0.40 which is characteristic of the so-called agave/pineapple group.  相似文献   

Effect of the fungicide imazalil on hepatic microsomal cytochrome P-450 and cytochrome P-450 dependent activities in the Bobwhite quail (Colinus virginianus)     

Karel Lavrijsen  Jos Van Houdt  Dirk Van Dyck  Willem Meuldermans  Jos Heykants 《Pest management science》1990,29(1):47-56

Bobwhite quails were treated with imazalil for 8 weeks. The fungicide was given admixed in the food at 0, 100, 300, 500 and 1000 mg kg^?1. Even at the highest dose tested, imazalil did not affect the liver weight or the hepatic microsomal protein content. In treated quails, no significant induction of cytochrome P-450 or NADPH-cytochrome c-reductase activity was observed. Furthermore, imazalil did not induce or inhibit 7-ethoxyresorufin or 7-ethoxycoumarin O-deethylase in quail microsomes. Only a slight but significant increase by 35% and 49% in aniline hydroxylase activity was measured for the 500- and 1000-mg kg^?1 dose levels, respectively. After a drug-free period of one week, aniline hydroxylase activity returned to control values, indicating that the effect was fully reversible. It is concluded that imazalil does not induce or inhibit drug-metabolizing enzymes in the quail, even at doses which exceed by far the maximum levels currently used to dress seed under field conditions (100 mg kg^?1).  相似文献   

Identification of barley yellow mosaic virus by immuno-electron microscopy in barley but not in Polymyxa graminis or Lagena radicicola     

Willem G. Langenberg  Derk Van Der Wal 《European journal of plant pathology / European Foundation for Plant Pathology》1986,92(3):133-136

Samenvatting Gerstegeelmozaïekvirus (BaYMV) werd in een perceel wintergerst (cv. Igri) gevonden by Wittem in Limburg, Nederland. Het virus werd met immuno-elektronen-microscopie geïdentificeerd in bladweefsel als BaYMV. In de wortels van geïnfecteerde planten werden alle vormen die van de schimmel-vector (Polymyxa graminis Led.) bekend zijn aangetroffen nl. cystosori, plasmodia en zoosporangia. Inwendig kon geen BaYMV worden aangetoond of waargenomen inPolymyxa ofLagena spp.Cooperative investigation of the ARS, USDA, the Nebraska Agricultural Experiment Station, and the Plant Protection Service, Wageningen. Research conducted under Project 21-12. Published as Paper No. 7787, Journal Series, Nebraska Agricultural experiment Station. Mention of a trademark or proprietary product does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.  相似文献   

Neuroendocrine-immune interactions in fish: a role for interleukin-1   总被引：10，自引：0，他引：10  

Engelsma MY  Huising MO  van Muiswinkel WB  Flik G  Kwang J  Savelkoul HF  Verburg-van Kemenade BM 《Veterinary immunology and immunopathology》2002,87(3-4):467-479

Bi-directional communication between the hypothalamus-pituitary-adrenal (HPA)-axis and the sympathetic nervous system with the immune system is crucial to ensure homeostasis. Shared use of ligands and especially receptors forms a key component of this bi-directional interaction. Glucocorticoids (GC), the major end products of the HPA-axis differentially modulate immune function. Cytokines, especially interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), ensure immune signalling to the neuroendocrine system. In addition, hormones from leukocyte origin such as corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and beta-endorphin, as well as centrally synthesised and secreted cytokines, contribute to the communication network.In teleost fish cortisol is the major product of the hypothalamus-pituitary-interrenal (HPI)-axis which is the teleost equivalent of the HPA-axis. Moderate and substantial increases in cortisol during stressful circumstances negatively affect B-lymphocytes, whereas rescue of neutrophilic granulocytes may support innate immunity. Recent elucidation of lower vertebrate cytokine sequences has facilitated research into neuroendocrine-immune interactions in teleosts and the first evidence for a significant function of interleukin-1 in the bi-directional communication is discussed.  相似文献   

<Emphasis Type="Italic">Amaranthus leaf mottle virus</Emphasis>: 3′-end RNA sequence proves classification as distinct virus and reveals affinities within the genus <Emphasis Type="Italic">Potyvirus</Emphasis>     

Eduardo Segundo  Dietrich E. Lesemann  Germán Martín  María P. Carmona  Leticia Ruiz  Isabel M. Cuadrado  Leonardo Velasco  Dirk Janssen 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(1):81-87

Amaranthus leaf mottle virus (AmLMV) was classified as a member of the genus Potyvirus on the basis of its particle morphology, serology, and biological properties (Casetta et al., 1986). Based on these properties, an Amaranthus viridis-infecting virus isolated in Spain, causing mottle and leaf blistering as well as reduced growth has been identified as AmLMV. The 3′ terminal genomic region of this and a reference isolate from Italy has been sequenced and reveals a 95% nucleotide identity between the two isolates. The sequenced part comprises the coat protein with 281 amino acids and 315 nucleotides of the 3′ untranslated region (UTR) preceding a polyadenylated tail. Pairwise comparisons and phylogenetic analysis of the nucleotide and deduced amino acid sequences of the CP and 3′ UTR of the cloned cDNAs with those of other potyviruses shows that AmLMV is a distinct potyvirus closely related to Potato virus Y.  相似文献   

Identifying crop yield gaps with site- and season-specific data-driven models of yield potential     

Filippi  Patrick  Whelan  Brett M.  Vervoort  R. Willem  Bishop  Thomas F. A. 《Precision Agriculture》2022,23(2):578-601

Precision Agriculture - There is considerable interest and value in identifying the gap between crop yields that have actually been achieved, and yields that could have potentially been achieved. A...  相似文献