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Publikation

Bochnia, M.; Ziegler, J.; Glatter, M.; Zeyner, A.; Hypoglycin A in cow’s milk—A pilot study Toxins 13, 381, (2021) DOI: 10.3390/toxins13060381

Hypoglycin A (HGA) originating from soapberry fruits (litchi, and ackee) seeds or seedlings from the sycamore maple (SM) tree (related to Sapindaceae) may cause Jamaican vomiting sickness in humans and atypical myopathy in horses and ruminants. A possible transfer into dairy cow’s milk cannot be ruled out since the literature has revealed HGA in the milk of mares and in the offal of captured deer following HGA intoxication. From a study, carried out for another purpose, bulk raw milk samples from four randomly selected dairy farms were available. The cows were pastured in the daytime. A sycamore maple tree was found on the pasture of farm No. 1 only. Bulk milk from the individual tank or milk filling station was sampled in parallels and analyzed for HGA by LC-ESI-MS/MS. Measurable concentrations of HGA occurred only in milk from farm No. 1 and amounted to 120 and 489 nmol/L. Despite low and very variable HGA concentrations, the results indicate that the ingested toxin, once eaten, is transferred into the milk. However, it is unknown how much HGA the individual cow ingested during grazing and what amount was transferred into the bulk milk samples. As a prerequisite for a possible future safety assessment, carry-over studies are needed. Furthermore, the toxins’ stability during milk processing should also be investigated as well.
Publikation

Ziegler, J.; Bochnia, M.; Zeyner, A.; Aminosäurennachweis in geringsten ProbenmengenBestimmung von Hypoglycin A Wiley Analytical Science (2021)

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Publikation

Bochnia, M.; Sander, J.; Ziegler, J.; Terhardt, M.; Sander, S.; Janzen, N.; Cavalleri, J.-M. V.; Zuraw, A.; Wensch-Dorendorf, M.; Zeyner, A.; Detection of MCPG metabolites in horses with atypical myopathy PLOS ONE 14, e0211698, (2019) DOI: 10.1371/journal.pone.0211698

Atypical myopathy (AM) in horses is caused by ingestion of seeds of the Acer species (Sapindaceae family). Methylenecyclopropylacetyl-CoA (MCPA-CoA), derived from hypoglycin A (HGA), is currently the only active toxin in Acer pseudoplatanus or Acer negundo seeds related to AM outbreaks. However, seeds or arils of various Sapindaceae (e.g., ackee, lychee, mamoncillo, longan fruit) also contain methylenecyclopropylglycine (MCPG), which is a structural analogue of HGA that can cause hypoglycaemic encephalopathy in humans. The active poison formed from MCPG is methylenecyclopropylformyl-CoA (MCPF-CoA). MCPF-CoA and MCPA-CoA strongly inhibit enzymes that participate in β-oxidation and energy production from fat. The aim of our study was to investigate if MCPG is involved in Acer seed poisoning in horses. MCPG, as well as glycine and carnitine conjugates (MCPF-glycine, MCPF-carnitine), were quantified using high-performance liquid chromatography-tandem mass spectrometry of serum and urine from horses that had ingested Acer pseudoplatanus seeds and developed typical AM symptoms. The results were compared to those of healthy control horses. For comparison, HGA and its glycine and carnitine derivatives were also measured. Additionally, to assess the degree of enzyme inhibition of β-oxidation, several acyl glycines and acyl carnitines were included in the analysis. In addition to HGA and the specific toxic metabolites (MCPA-carnitine and MCPA-glycine), MCPG, MCPF-glycine and MCPF-carnitine were detected in the serum and urine of affected horses. Strong inhibition of β-oxidation was demonstrated by elevated concentrations of all acyl glycines and carnitines, but the highest correlations were observed between MCPF-carnitine and isobutyryl-carnitine (r = 0.93) as well as between MCPA- (and MCPF-) glycine and valeryl-glycine with r = 0.96 (and r = 0.87). As shown here, for biochemical analysis of atypical myopathy of horses, it is necessary to take MCPG and the corresponding metabolites into consideration.
Publikation

Bochnia, M.; Scheidemann, W.; Ziegler, J.; Sander, J.; Vollstedt, S.; Glatter, M.; Janzen, N.; Terhardt, M.; Zeyner, A.; Predictive value of hypoglycin A and methylencyclopropylacetic acid conjugates in a horse with atypical myopathy in comparison to its cograzing partners Equine Vet. Educ. 30, 24-28, (2018) DOI: 10.1111/eve.12596

Hypoglycin A (HGA) was detected in blood and urine of a horse suffering from atypical myopathy (AM; Day 2, serum, 8290 μg/l; urine: Day 1, 574, Day 2, 742 μg/l) and in its cograzing partners with a high variability (46–1570 μg/l serum). Over the period of disease, the level of the toxic metabolites (methylencyclopropylacetic acid [MCPA]‐conjugates) increased in body fluids of the AM horse (MCPA‐carnitine: Day 2, 0.246, Day 3, 0.581 μmol/l serum; MCPA‐carnitine: Day 2, 0.621, Day 3, 0.884 μmol/mmol creatinine in urine) and HGA decreased rapidly (Day 3, 2430 μg/l serum). In cograzing horses MCPA‐conjugates were not detected. HGA in seeds ranged from 268 to 367 μg/g. Although HGA was present in body fluids of healthy cograzing horses, MCPA‐conjugates were not detectable, in contrast to the AM horse. Therefore, increasing concentrations of MCPA‐conjugates are supposed to be linked with the onset of AM and both parameters seem to indicate the clinical stage of disease. However, detection of HGA in body fluids of cograzing horses might be a promising step in preventing the disease.
Publikation

Bochnia, M.; Ziegler, J.; Sander, J.; Uhlig, A.; Schaefer, S.; Vollstedt, S.; Glatter, M.; Abel, S.; Recknagel, S.; Schusser, G. F.; Wensch-Dorendorf, M.; Zeyner, A.; Hypoglycin A Content in Blood and Urine Discriminates Horses with Atypical Myopathy from Clinically Normal Horses Grazing on the Same Pasture PLOS ONE 10, e0136785, (2015) DOI: 10.1371/journal.pone.0136785

Hypoglycin A (HGA) in seeds of Acer spp. is suspected to cause seasonal pasture myopathy in North America and equine atypical myopathy (AM) in Europe, fatal diseases in horses on pasture. In previous studies, this suspicion was substantiated by the correlation of seed HGA content with the concentrations of toxic metabolites in urine and serum (MCPA-conjugates) of affected horses. However, seed sampling was conducted after rather than during an outbreak of the disease. The aim of this study was to further confirm the causality between HGA occurrence and disease outbreak by seed sampling during an outbreak and the determination of i) HGA in seeds and of ii) HGA and MCPA-conjugates in urine and serum of diseased horses. Furthermore, cograzing healthy horses, which were present on AM affected pastures, were also investigated. AM-pastures in Germany were visited to identify seeds of Acer pseudoplatanus and serum (n = 8) as well as urine (n = 6) from a total of 16 diseased horses were analyzed for amino acid composition by LC-ESI-MS/MS, with a special focus on the content of HGA. Additionally, the content of its toxic metabolite was measured in its conjugated form in body fluids (UPLC-MS/MS). The seeds contained 1.7–319.8 μg HGA/g seed. The content of HGA in serum of affected horses ranged from 387.8–8493.8 μg/L (controls < 10 μg/L), and in urine from 143.8–926.4 μg/L (controls < 10 μg/L), respectively. Healthy cograzing horses on AM-pastures showed higher serum (108.8 ± 83.76 μg/L) and urine concentrations (26.9 ± 7.39 μg/L) compared to control horses, but lower concentrations compared to diseased horses. The range of MCPA-carnitine and creatinine concentrations found in diseased horses in serum and urine were 0.17–0.65 mmol/L (controls < 0.01), and 0.34–2.05 μmol/mmoL (controls < 0.001), respectively. MCPA-glycine levels in urine of cograzing horses were higher compared to controls. Thus, the causal link between HGA intoxication and disease outbreak could be further substantiated, and the early detection of HGA in cograzing horses, which are clinically normal, might be a promising step in prophylaxis.
Bücher und Buchkapitel

Quint, M.; Lübberstedt, T.; Application of resistance gene analogs in breeding for virus resistance Plant Pathogens Series 6, (2008)

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Publikation

Frisch, M.; Quint, M.; Lübberstedt, T.; Melchinger, A. E.; Duplicate marker loci can result in incorrect locus orders on linkage maps Theor. Appl. Genet. 109, 305-316, (2004) DOI: 10.1007/s00122-003-1578-4

Genetic linkage maps, constructed from multi-locus recombination data, are the basis for many applications of molecular markers. For the successful employment of a linkage map, it is essential that the linear order of loci on a chromosome is correct. The objectives of this theoretical study were to (1) investigate the occurrence of incorrect locus orders caused by duplicate marker loci, (2) develop a statistical test for the detection of duplicate markers, and (3) discuss the implications for practical applications of linkage maps. We derived conditions, under which incorrect locus orders do or do not occur with duplicate marker loci for the general case of n markers on a chromosome in a BC1 mapping population. We further illustrated these conditions numerically for the special case of four markers. On the basis of the extent of segregation distortion, an exact test for the presence of duplicate marker loci was suggested and its power was investigated numerically. Incorrect locus orders caused by duplicate marker loci can (1) negatively affect the assignment of target genes to chromosome regions in a map-based cloning experiment, (2) hinder indirect selection for a favorable allele at a quantitative trait locus, and (3) decrease the efficiency of reducing the length of the chromosome segment attached to a target gene in marker-assisted backcrossing.
Publikation

Quint, M.; Dußle, C. M.; Melchinger, A. E.; Lübberstedt, T.; Identification of genetically linked RGAs by BAC screening in maize and implications for gene cloning, mapping and MAS Theor. Appl. Genet. 106, 1171-1177, (2003) DOI: 10.1007/s00122-002-1105-z

The resistance gene analogue (RGA) pic19 in maize, a candidate for sugarcane mosaic virus (SCMV) resistance gene (R gene) Scmv1, was used to screen a maize BAC library to identify homologous sequences in the maize genome and to investigate their genomic organisation. Fifteen positive BAC clones were identified and could be classified into five physically independent contigs consisting of overlapping clones. Genetic mapping clustered three contigs into the same genomic region as Scmv1 on chromosome 6S. The two remaining contigs mapped to the same region as a QTL for SCMV resistance on chromosome 1. Thus, RGAs mapping to a target region can be successfully used to identify further-linked candidate sequences. The pic19 homologous sequences of these clones revealed a sequence similarity of 94–98% on the nucleotide level. The high sequence similarity reveals potential problems for the use of RGAs as molecular markers. Their application in marker-assisted selection (MAS) and the construction of high-density genetic maps is complicated by the existence of closely linked homologues resulting in 'ghost' marker loci analogous to 'ghost' QTLs. Therefore, implementation of genomic library screening, including genetic mapping of potential homologues, seems necessary for the safe application of RGA markers in MAS and gene isolation.
Publikation

Dußle, C.; Quint, M.; Melchinger, A.; Xu, M.; Lübberstedt, T.; Saturation of two chromosome regions conferring resistance to SCMV with SSR and AFLP markers by targeted BSA Theor. Appl. Genet. 106, 485-493, (2003) DOI: 10.1007/s00122-002-1107-x

Quantitative trait loci (QTLs) and bulked segregant analyses (BSA) identified the major genes Scmv1 on chromosome 6 and Scmv2 on chromosome 3, conferring resistance against sugarcane mosaic virus (SCMV) in maize. Both chromosome regions were further enriched for SSR and AFLP markers by targeted bulked segregant analysis (tBSA) in order to identify and map only markers closely linked to either Scmv1 or Scmv2. For identification of markers closely linked to the target genes, symptomless individuals of advanced backcross generations BC5 to BC9 were employed. All AFLP markers, identified by tBSA using 400 EcoRI/MseI primer combinations, mapped within both targeted marker intervals. Fourteen SSR and six AFLP markers mapped to the Scmv1 region. Eleven SSR and 18 AFLP markers were located in the Scmv2 region. Whereas the linear order of SSR markers and the window size for the Scmv2 region fitted well with publicly available genetic maps, map distances and window size differed substantially for the Scmv1 region on chromosome 6. A possible explanation for the observed discrepancies is the presence of two closely linked resistance genes in the Scmv1 region.
Publikation

Dussle, C.; Quint, M.; Xu, M.; Melchinger, A.; Lübberstedt, T.; Conversion of AFLP fragments tightly linked to SCMV resistance genes Scmv1 and Scmv2 into simple PCR-based markers Theor. Appl. Genet. 105, 1190-1195, (2002) DOI: 10.1007/s00122-002-0964-7

In a previous study, bulked segregant analysis with amplified fragment length polymorphisms (AFLPs) identified several markers closely linked to the sugarcane mosaic virus resistance genes Scmv1 on chromosome 6 and Scmv2 on chromosome 3. Six AFLP markers (E33M61-2, E33M52, E38M51, E82M57, E84M59 and E93M53) were located on chromosome 3 and two markers (E33M61-1 and E35M62-1) on chromosome 6. Our objective in the present study was to sequence the respective AFLP bands in order to convert these dominant markers into more simple and reliable polymerase chain reaction (PCR)-based sequence-tagged site markers. Six AFLP markers resulted either in complete identical sequences between the six inbreds investigated in this study or revealed single nucleotide polymorphisms within the inbred lines and were, therefore, not converted. One dominant AFLP marker (E35M62-1) was converted into an insertion/deletion (indel) marker and a second AFLP marker (E33M61-2) into a cleaved amplified polymorphic sequence marker. Mapping of both converted PCR-based markers confirmed their localization to the same chromosome region (E33M61-2 on chromosome 3; E35M62-1 on chromosome 6) as the original AFLP markers. Thus, these markers will be useful for marker-assisted selection and facilitate map-based cloning of SCMV resistance genes.
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