Publications by authors named "Michael M��ller"

2 Publications

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Differential expressions of anthocyanin synthesis genes underlie flower color divergence in a sympatric Rhododendron sanguineum complex.

BMC Plant Biol 2021 Apr 28;21(1):204. Epub 2021 Apr 28.

CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China.

Background: The Rhododendron sanguineum complex is endemic to alpine mountains of northwest Yunnan and southeast Tibet of China. Varieties in this complex exhibit distinct flower colors even at the bud stage. However, the underlying molecular regulations for the flower color variation have not been well characterized. Here, we investigated this via measuring flower reflectance profiles and comparative transcriptome analyses on three coexisting varieties of the R. sanguineum complex, with yellow flush pink, bright crimson, and deep blackish crimson flowers respectively. We compared the expression levels of differentially-expressed-genes (DEGs) of the anthocyanin / flavonoid biosynthesis pathway using RNA-seq and qRT-PCR data. We performed clustering analysis based on transcriptome-derived Single Nucleotide Polymorphisms (SNPs) data, and finally analyzed the promoter architecture of DEGs.

Results: Reflectance spectra of the three color morphs varied distinctively in the range between 400 and 700 nm, with distinct differences in saturation, brightness, hue, and saturation/hue ratio, an indirect measurement of anthocyanin content. We identified 15,164 orthogroups that were shared among the three varieties. The SNP clustering analysis indicated that the varieties were not monophyletic. A total of 40 paralogous genes encoding 12 enzymes contributed to the flower color polymorphism. These anthocyanin biosynthesis-related genes were associated with synthesis, modification and transportation properties (RsCHS, RsCHI, RsF3H, RsF3'H, RsFLS, RsANS, RsAT, RsOMT, RsGST), as well as genes involved in catabolism and degradation (RsBGLU, RsPER, RsCAD). Variations in sequence and cis-acting elements of these genes might correlate with the anthocyanin accumulation, thus may contribute to the divergence of flower color in the R. sanguineum complex.

Conclusions: Our results suggested that the varieties are very closely related and flower color variations in the R. sanguineum complex correlate tightly with the differential expression levels of genes involved in the anabolic and catabolic synthesis network of anthocyanin. Our study provides a scenario involving intricate relationships between genetic mechanisms for floral coloration accompanied by gene flow among the varieties that may represent an early case of pollinator-mediated incipient sympatric speciation.
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April 2021

Proteomic profiling of pretreatment serum from HIV-infected patients identifies candidate markers predictive of lymphoma development.

AIDS 2016 07;30(12):1889-98

aDepartment of Haematology, Aarhus University HospitalbDepartment of Biomedicine, Aarhus UniversitycInstitute of Pathology, Aarhus University Hospital, AarhusdDepartment of PathologyeDepartment of Infectious Diseases, Odense University Hospital, OdensefDepartment of Infectious Diseases, Aalborg University Hospital, AalborggThe Danish HIV Cohort, Department of Infectious Diseases, Copenhagen University Hospital, CopenhagenhDepartment of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark.*Maja Ølholm Vase and Maja Ludvigsen shared first authorships.†Francesco d'Amore and Bent Honoré shared last authorships.

Objective: HIV-infected individuals have an increased risk of developing lymphoma. We sought to identify markers predictive of lymphoma development by comparing protein expression patterns in serum obtained at the time of HIV diagnosis from patients who later developed malignant lymphoma or benign lymphadenopathy, with samples from patients with no subsequent history of neoplasia.

Design: All patients were identified retrospectively from the Danish HIV cohort.

Methods: Serum samples (N = 21), obtained at time of HIV diagnosis, were subjected to high-resolution two-dimensional gel electrophoresis. Differentially expressed proteins were identified by liquid chromatography-tandem mass spectrometry. A tissue microarray, containing diagnostic HIV-lymphoma tissue samples (N = 40), was used to investigate immunohistochemical expression of markers in tumoural lesions.

Results: Fourteen differentially expressed protein spots were detected. Using principal components analysis, spots containing immunoglobulin J chain, apolipoprotein A-I, procollagen C-endopeptidase enhancer-1 and complement C4-A were associated with lymphoma development (P < 0.0001). Serum amyloid A-2 was increased almost 10-fold in patients with subsequent lymphoma compared with patients without subsequent lymphoma. In the tissue microarray, amyloid A was widely expressed, and high expression showed a tendency towards inferior outcome (log-rank 0.073).

Conclusion: We identified several differentially expressed protein spots present already at the time of HIV diagnosis. Analysis of biological differences correlating to lymphoma development at this early stage of a possible malignant transformation may lead to the identification of predictive markers. Further investigation of the potential clinical application of differentially expressed proteins as risk stratification markers for monitoring HIV-positive individuals is warranted.
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July 2016