bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns ofMycoplasma hyopneumoniaeInfections in Belgian Farrow‐to‐Finish Pig Herds with Diverging Disease‐Course
Authors: Vicca J. , Maes D. , Thermote L. , Peeters J. , Haesebrouck F. , de Kruif A. 
Published: March 2003

SummaryPatterns ofMycoplasma hyopneumoniae(Mh) infections were investigated in five clinically infected herds and in five herds subclinically infected with Mh. In the clinically infected herds, housing and management conditions were good whereas these conditions were poor in the subclinically infected herds. In each herd, serum antibodies against Mh were detected in pigs of different ages and nasal swabs were taken for Mh detection using nested PCR (nPCR). The percentage of seropositive pigs in the clinically infected herds increased from 8% in pigs of 9 weeks to 52% in pigs of 18 weeks and seroconversion was most shown between 12 and 15 weeks. In the subclinically infected herds, the percentages increased from 2 to 24% and most of the pigs became seropositive between 15 and 18 weeks. The percentage of nPCR positive pigs at 6 weeks was 16 and 0% in the clinically and subclinically infected herds, respectively. The results demonstrate that the seroprevalences were higher in the clinically infected herds and that most of the pigs became infected with Mh at a younger age. It can be concluded that additional factors different from housing and management, like differences among Mh strains, may determine the infection pattern of Mh and the clinical course of the infection.
Transmission ofAnaplasma phagocytophila(Human Granulocytic Ehrlichiosis Agent) in Horses Using Experimentally Infected Ticks (Ixodes scapularis)
Authors: Pusterla N. , Chae J.‐S. , Kimsey R. B. , Berger Pusterla J. , DeRock E. , Dumler J. S. , Madigan J. E. 
Published: March 2003

SummaryMost human granulocytic ehrlichiosis (HGE) studies carried out in horses use needle inoculation of infected leucocytes or cell cultures. This route of inoculation does not accurately reflect natural infection of the tick‐borne agent. To investigate whether tick transmission influences the course of granulocytic ehrlichiosis in the horse model, experimental transmission through infected laboratory‐rearedIxodes scapularisticks was attempted into two healthy horses. One additional horse served as negative control and was exposed to uninfected ticks. Eleven days after exposure to nymphal or adult ticks infected withAnaplasma phagocytophila(HGE agent) the two horses developed severe clinical and laboratory signs consistent with granulocytic ehrlichiosis. Bacteraemia was determined at various time points in the two horses by observation of morulae within neutrophils and by detection ofA. phagocytophilagenomic DNA by PCR of peripheral blood leucocytes. Further, both horses seroconverted. In contrast the control horse stayed uninfected. The results demonstrate thatA. phagocytophilacan be experimentally transmitted by infected nymphal and adult ticks and that the agent is able to produce a severe disease, similar to naturally occurring cases. Therefore, tick transmission is highly reproducible and can be successfully used in the equine animal model in order to study HGE.
Foetal Protection against Bovine Virus Diarrhoea Virus after Two‐step Vaccination
Authors: Frey H.‐R. , Eicken K. , Grummer B. , Kenklies S. , Oguzoglu T. C. , Moennig V. 
Published: March 2003

SummaryIn order to assess the efficacy of a two‐step vaccination protocol with respect to foetal protection against transplacental infections with bovine virus diarrhoea virus (BVDV) with special attention to BVDV‐2 seronegative heifers were vaccinated with an inactivated BVDV‐1 vaccine and boostered with a modified live BVDV‐1 vaccine after 4 weeks. A second group was left unvaccinated as control. Between days 30 and 120 of pregnancy the heifers of both groups were intranasally challenged with a mixture of BVDV‐1 and ‐2. All heifers of the vaccinated group gave birth to nine clinically healthy, seronegative (precolostral) and BVDV‐free calves. In contrast in the control group four BVDV viraemic underdeveloped calves were born. Additionally, one calf was stillborn and another viraemic calf was not viable and died 2 days after birth. All six calves of the control group were viraemic with BVDV‐2.This study demonstrated for the first time that two‐step vaccination of breeding cattle with a modified live BVDV vaccine 4 weeks after application of an inactivated BVDV vaccine was capable of providing a foetal protection against transplacental infection with BVDV‐2.
Application of Different Methods for the Diagnosis of Paratuberculosis in a Dairy Cattle Herd in Argentina
Authors: Paolicchi F. A. , Zumarraga M. J. , Gioffre A. , Zamorano P. , Morsella C. , Verna A. , Cataldi A. , Alito A. , Romano M. 
Published: March 2003

SummaryParatuberculosis (Ptbc) has a high prevalence in Argentina, that affects dairy and beef cattle. The culture is the gold standard to the diagnosis of the disease.Mycobacterium aviumssp.paratuberculosis (M. paratuberculosis), the aetiological agent, is difficult to isolate and grow in culture. In this study, 24 randomly selected cows of the Fresian breed from a dairy herd with a history of Ptbc were used to evaluate the performance of different diagnostic techniques. These animals did not show clinical signs of the disease. However, another animal from this herd presented evidence of clinical disease at the moment of the present study. This animal was necropsied and one strain ofM. paratuberculosiswas isolated from faeces, lymph nodes and intestine. Serum for indirect absorbed enzyme‐linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) tests and whole blood samples to perform gamma interferon (γIFN) release assays were obtained from each animal. Faeces and milk samples to carry out bacteriological cultures, PCR identification ofM. paratuberculosis, and direct examinations of smears with Ziehl–Neelsen's (ZN) stain were also collected. Tuberculin test with bovine purified protein derivative (PPD) in the caudal fold was performed. The results showed that 10 out of 24 animals (41.6%) were positive to ELISA. Eight strains ofM. paratuberculosiswere isolated, six from faeces, two from milk. Five of the animals that excreted the bacteria through faeces were ELISA‐positive, whereas the excreters through milk were negative to ELISA. No positive samples by AGID were obtained in clinical asymptomatic animals. Seven samples gave positiveγIFN results with avian PPD, but only two of these animals were confirmed with culture. Direct PCR, to detect IS900(M. paratuberculosis) in faeces and milk samples, was negative, but PCR using material taken from faecal and milk cultures gave positive results before visualizing the colonies. No sample was positive by PCR directed to IS6110(M. tuberculosiscomplex). There was not always agreement between isolations and ZN in the studied samples. In conclusion, the absorbed ELISA was useful to detect positive animals and excreters through faeces but not through milk. PCR applied to cultures with incipient development before the visualization of colonies was effective to specifically determine the presence ofM. paratuberculosis. TheγIFN test was not able to detect the most positive animals confirmed by culture. The importance of using ELISA and cultures is emphasized by this study but it is necessary to continue with theγIFN test development for early detection of the disease.
Retrospective study on porcine circovirus type 2 infection in pigs from 1985 to 1997 in Spain
Authors: Rodríguez‐Arrioja G. M. , Segalés J. , Rosell C. , Rovira A. , Pujols J. , Plana‐Durán J. , Domingo M. 
Published: March 2003

SummaryA retrospective survey was performed to detect lesions of Postweaning multisystemic wasting syndrome (PMWS) and nucleic acid of porcine circovirus type 2 (PCV2) in archived formalin‐fixed, paraffin‐embedded tissues from 189 pigs, and antibodies to this virus in sera of 388 pigs from the Spanish livestock between the years 1985 and 1997. PCV2 nucleic acid was detected byin situhybridization (ISH) in tissues from 78 of 189 (41.3%) examined pigs. Variable amount of viral genome was detected in association with slight to severe microscopic lymphoid lesions consisting of lymphocyte depletion and histiocytic infiltration. The first positive case of PMWS with typical lesions and ISH positive corresponded to a pig necropsied in 1986. Two hundred and eighty‐two of 388 (72.7%) sera were positive by immunoperoxidase monolayer assay. Serological and pathological data of the present study indicate that PCV2 was a enzootic infection in Spain since 1985, suggesting that the introduction of this virus in the livestock occurred previously.
Identification of primary trisomics and other aneuploids in foxtail millet
Authors: Wang R. , Gao J. , Liang G. H. 
Published: March 2003

AbstractA complete set of nine primary trisomics (2n+ 1) for cv.‘Yugu No. 1’of foxtail millet, Setaria italica (L.) Beauv. (2n= 2x= 18), was identified cytologically from progenies derived from crosses between autotriploids(2n= 2x= 27) and their diploid counterparts. Five autotriploid plants were identified from 2100 seedlings derived from 4x‐2x crosses; the reciprocal crosses (2x‐4x) failed to produce autotriploids. Autotriploids grew vigorously and were morphologically very similar to diploids. Theprimary trisomics (2n= 2x= 19) constituted ≅32.5% of the total progeny from the 3x‐2x crosses, whereas 59.8% of the descendants were aneuploids with chromosome numbers ranging from 20 (double trisomics and tetrasomics) to 37 (2n= 4x+ 1; or autotetraploid with one additional chromosome). The nine primary trisomics identified were self‐fertile; seven had characteristic morphology, whereas trisomics VIII and IX resembled the disomics. The seed set for trisomic V was the lowest (20%), and trisomic VIII the highest (74%). Other aneuploids with 20 or more somatic chromosomes were either self‐sterile or partially fertile with various, but low, levels of seed set. Each of the primary trisomics showed its unique transmission rate when self‐pollinated; trisomic IX had the highest (45.8%), whereas trisomic V had the lowest (19.6%) transmission rate.
Inheritance of the resistance to Leptosphaeria maculans of Brassica nigra and B. juncea in near‐isogenic lines of B. napus
Authors: Dixelius C. 
Published: March 2003

AbstractThe inheritance of resistance to Leptosphaeria maculans was studied in near‐isogenic lines derived from asymmetric somatic hybrids between Brassica napus+Brassica nigra and Brassica napus+Brassica juncea, respectively. The hybrids had been backcrossed to B. napus for seven generations before the genetic segregation of the blackleg resistance was determined. The results of the inheritance studies suggested that one single dominant allele controls the resistance in the Brassica napojuncea line, whereas two independent dominant loci were found in the Brassica naponigra line. Total leaf DNA from the near‐isogenic lines was isolated and 89 loci were detected by hybridization to 66 restriction fragment length polymorphism (RFLP) markers previously mapped in the B. nigra genome. Out of the 89 loci, eight loci were detected in the B. naponigra line and six were found in the B. napojuncea line. RFLP markers co‐segregating with blackleg resistance in adult leaves were also found. Two markers associated with linkage group 5 and 8, respectively, of the B genome were found in the B. naponigra line and one marker was associated with linkage group 2 in the B. napojuncea line.
Comparison of isoenzymes in Prunus avium separated by two different electrophoretic techniques
Authors: Pashkoulov D. T. , Tobutt K. R. , BoŠković R. 
Published: March 2003

AbstractIsoenzyme variation for seven systems revealed by two different electrophoretic procedures was compared in Prunus avium. Fourteen cultivars and 14 wild selections were analysed for acid phosphatase (ACP), isocitrate dehydrogenase (IDH), leucine aminopeptidase (LAP), malate dehydrogenase (MDH), phosphoglucomutase (PGM), shikimate dehydrogenase (SKD) and superoxide dismutase (SOD). Extracts were separated by isoelectric focusing (IEF) and by polyacrylamide gel electrophoresis (PAGE). For the eight loci that had been described previously in these enzyme systems on the basis of IEF analysis, we compared the variation revealed with IEF and PAGE. Similar variation was revealed for Acp‐1 and Pgm‐1, and the alleles revealed by PAGE could be identified directly with those reported for IEF. For Lap‐1, Mdh‐1 and Skd‐1, variation was seen with IEF but not with PAGE. For Mdh‐2, PAGE revealed additional variation not revealed by IEF. For Idh‐1, different patterns of variation were revealed by PAGE and IEF, and both procedures would be needed to genotype cherry accessions. We were unable to detect variation corresponding to that reported previously for Sod‐1 with either technique. The implications of these findings for allele labelling, for studies of genetic diversity and for linkage analysis are discussed.
A chlorophyll‐reduced seedling mutant in oilseed rape, Brassica napus, for utilization in F1 hybrid production
Authors: Zhao Y. , Wang M. L. , Zhang Y. Z. , Du L. F. , Pan T. 
Published: March 2003

AbstractA mutant chlorophyll‐reduced (Cr) seedling with yellow‐green cotyledons and leaves was obtained from the Brassica napus inbred line 3529 induced by fast neutron and diethyl sulphate (DES). Genetic analysis revealed that the Cr seedling marker trait was controlled by a pair of recessive genes. A randomized complete block design was used to evaluate its agronomic performance. Results from 2 years of tests indicated that the seed yield of Cr lines was significantly lower than that of normal green plants; however, when the Cr gene was in the heterozygous condition, no deleterious effects on yield characteristics and disease resistance were observed. The Cr seedling marker trait was introduced into male‐sterile lines, and Cr male‐sterile lines revealed the same superior combining ability as normal chlorophyll (Nc) lines. The Cr trait can therefore be used as a marker to produce hybrid seed.
Regular segregation of four recessive marker genes among maternal haploids in maize
Authors: Chalyk S. T. , Chebotar O. D. 
Published: March 2003

AbstractThe objective of the study was to investigate whether a population of maternal haploid plants represents a random gametic array. Four inbred lines of maize (A619, MK01, 092 and 19‐3‐3) were used in the present study. These were crossed with line TO carrying four recessive genes: brown midrib (bm2), liguleless (Ig1), white endosperm (g1) and golden plant (g1). Maternal haploids were produced from the F 1 hybrids, using a haploid‐inducing pollinator line. Segregation of haploids for the marker genes was estimated under field conditions. The observed segregation data agreed with the expected 1:1 ratio. It is concluded that no segregation distortion occurred during the production of maternal haploids.
Genetic analysis of resistance to green leafhopper, Nephotettix virescens (Distant), in three varieties of rice
Authors: Angeles E. R. , Khush G. S. 
Published: March 2003

AbstractThe genetics of resistance to green leafhopper, Nephotettix virescens (Distant), in rice varieties ‘IR36’ and ‘Maddai Karuppan’ and breeding line ‘IR20965‐11‐3‐3’ was studied. The reactions of F1 hybrids, F2 populations and F3 lines from the crosses of test varieties with the susceptible variety ‘TN1’ revealed that resistance in ‘IR36’ and ‘Maddai Karuppan’, is governed by single recessive genes while resistance in ‘IR20965‐11‐3‐3’ is controlled by a single dominant gene. Allele tests with the known genes for resistance to green leafhopper revealed that the recessive gene of ‘IR36’ is different from and inherited independently of Glh1, Glh2, Glh3, Glh4, Glh5, Glh8 and Glh9t. This gene is designated as glh10t. The recessive gene of ‘Maddai Karuppan’ and the dominant gene of ‘IR20965‐11‐3‐3’ are also non‐allelic to Glh1, Glh2, Glh3, Glh4, Glh5 and Glh8t. Thus, the dominant gene of IR20965‐11‐3‐3 is designated as Glh11t. The allelic relationships of the recessive gene of ‘Maddai Karuppan’ with glh8 and glh10t should be investigated.
Resistance to Fusarium head blight and deoxynivalenol accumulation in wheat
Authors: Bai G.‐H. , Plattner R. , Desjardins A. , Kolb F. , McIntosh R. A. 
Published: March 2003

AbstractFusarium head blight (FHB), caused by Fusarium graminearum Schwabe (telomorph =Gibberella zeae (Schw.)), is an important wheat disease world‐wide. Production of deoxynivalenol (DON) by F. graminearum in infected wheat grain is detrimental to livestock and is also a safety concern in human foods. An international collection of 116 wheat lines was evaluated for FHB resistance and concentration of DON in grain. Plants were inoculated with mixed isolates of F. graminearum in the greenhouse by injecting conidia into a single spikelet of each spike and in the field by scattering F. graminearum‐infected wheat kernels on the soil surface. FHB symptoms were evaluated by visual inspection in both the greenhouse and field, and DON was analysed by HPLC. Significant differences in FHB ratings and DON levels were observed among cultivars. In the greenhouse test, visual symptoms varied from no spread of FHB from the inoculated spikelet to spread throughout the spike, and DON levels ranged from trace levels to 283 mg/kg. In the field test, DON ranged from 2.8 to 52 mg/kg. The greenhouse test identified 16 wheat lines from various origins that accumulated less than 2 mg/kg DON. These lines may be useful as sources for breeding wheat cultivars with lower DON levels. Correlation coefficients were significant between FHB symptom ratings, seed quality traits, and DON levels. Thus, the percentage of scabbed spikelets and kernels can be generally used to predict DON levels in harvested wheat grain. In breeding programmes, selection for plants having few scabbed spikelets and scabbed kernels is most likely to result in low DON levels.
Effect of germination, seed abrasion and seed size on polyphenol oxidase assay activity in wheat
Authors: Demeke T. , Chang H.‐G. , Morris C. F. 
Published: March 2003

AbstractPolyphenol oxidase (PPO) is one of the major enzymes responsible for browning of wheat food products. Wheat cultivars differ in PPO activity and plant breeders wish to select germplasm and cultivars with low PPO activities. Prior to harvest, seeds may be exposed to conditions conducive to preharvest sprouting and mechanical damage may occur during harvesting and subsequent handling. Sprouting, mechanical damage and seed size may affect PPO assay activity and therefore impinge upon the breeder's ability to accurately select low PPO genotypes. The effects of incipient germination, mechanical abrasion and seed size on PPO assay activity were investigated using the cultivars ‘Klasic’(hard white spring, high PPO), ‘Penawawa’(soft white spring, high PPO) and ‘ID377s’(hard white spring, low PPO). The influence of embryo vs. distal portions of the seed on PPO assay activity was also examined. PPO activity was assayed with constant mixing using L‐3,4‐dihydroxyphenyl alanine (L‐DOPA) substrate at pH 6.5 at room temperature; absorbance of the reaction solution was measured at 475 nm. There was no change in PPO assay activity for seeds imbibed in water for up to 8 h. PPO assay activity increased in seeds imbibed from 8 to 16 h, and then gradually declined with increasing imbibing time. PPO assay activity initially increased as a result of mechanical abrasion but then gradually declined with increasing abrasion time. Large seeds had a higher total PPO assay activity than small seeds, but the difference in activity was not proportional to seed weight. There was only a slight difference in PPO assay activity between half‐seeds with or without the embryo. Overall, PPO assay activity in dry seeds was stable and exposure of seeds to injury and moisture did not make any significant change in PPO assay activity among the cultivars or their relative rankings.
Two major genes for kernel weight in rye
Authors: Wricke G. 
Published: March 2003

AbstractPreviously, kernel weight in rye was considered mostly as a quantitatively inherited trait. F1 plants from parents showing a great difference in kernel weight were selfed and the segregating F2 population was analysed with molecular markers. Two simple sequence repeats markers, one on chromosome 5 and the other on chromosome 7, were found which allowed the genetic analysis of two major genes acting in a complementary way. The analysis of major genes is an advantage in breeding for this important economic trait. In addition it can provide more insight into the genetic structure of this character. This is, in turn, also a prerequisite for future investigations of this trait at the molecular level.
Cytogenetics of Brassica juncea×Brassica rapa hybrids and patterns of variation in the hybrid derivatives
Authors: Choudhary B. R. , Joshi P. , Rao S. Rama 
Published: March 2003

AbstractInterspecific hybridization is an important tool to elucidate intergenomic relationships, transfer characters across species and develop synthetic amphidiploids, and it has been widely applied for improving Brassicas. The objective of the present study was to create genetic variability in Brassica through interspecific hybridization. Crosses between Brassica juncea (AABB, 2n= 36), and Brassica rapa (AA, 2n = 20) vars toria, yellow sarson, and brown sarson were attempted, and the hybrid derivatives were advanced to the F4 generation. Hybrids were obtained from the crosses B. juncea× toria and B. juncea× yellow sarson. The F1 plants were vigorous and intermediate to the parents in many morphological traits. The meiotic study of AAB hybrids showed 10 II + 8 I in the majority (71.8%) of cells analysed. A maximum of 12 and a minimum of seven bivalents were also observed in a few cells. The occurrence of multivalent associations (trivalents to pentavalents) at diakinesis/metaphase I and a bridge‐fragment configuration at anaphase I were attributed to homoeology between A and B genomes. A high percentage of plants resembling B. juncea was observed in the F2 generation. Transgressive segregation in both directions was found for plant height, primary branches, main raceme length, siliquae on main raceme, siliqua intensity, seeds per siliqua and seed yield. There were significant differences for the 14 characters in the F4 derivatives. Moderate to high estimates of phenotypic and genotypic coefficients of variation, broad‐sense heritability, and expected genetic advance were found for seed yield, 1000‐seed weight, siliquae per plant, seeds per siliqua and days to flowering. Intergenomic recombination, reflected as wide variation in the hybrid progenies, permitted the selection of some useful derivatives.