Agrar-, Ernährungs- und Ingenieurwissenschaftliche Fakultät

Deep phenotyping of dairy cows with different body condition for characterizing their adaptability to the onset of lactation

2026-05-22T00:00:00Z

Deep phenotyping of dairy cows with different body condition for characterizing their adaptability to the onset of lactation Hosseini Ghaffari, Morteza Metabolic and endocrine functions of dairy cows under non- optimal body condition (underconditioned or over-conditioned) exhibit marked abnormalities that result in a significant decrease in milk production. Underconditioned cows (although not specifically addressed in this paper) may not be able to successfully make the transition from late gestation to lactation, resulting in health problems. Underconditioned cows may not be able to mobilize enough energy for maximum lactation and have greater mobilization of muscle mass after calving than optimally conditioned cows. Over-conditioned cows lose a relatively large amount of body fat around calving, have higher circulating concentrations of free FA, BHB, and AcylCN in their circulation, and experience a more pronounced and prolonged NEB in early lactation than optimally conditioned cows.
Based on deep phenotyping, chapter 2 of this thesis deals with metabolic phenotyping of dairy cows with different body condition. Results for BA, AA, and AcylCN derived from targeted serum metabolomics are described in Publications I - IV, along with a detailed phenotype comparing optimally conditioned and over-conditioned dairy cows to elucidate the pathophysiological reasons for increasing metabolic dysfunction due to overconditioning. By comparing the metabolic profiles of optimally conditioned cows with those of over-conditioned cows, we identified important metabolites associated with overconditioning. Machine learning allowed us to move from descriptive studies to a better understanding of metabolic processes. Given the central role of the liver in metabolism, we also studied hepatic mRNA expression of genes involved in FA metabolism (especially FA oxidation) during transition in dairy cows to investigate the molecular mechanisms of overconditioning around parturition.
In the following study, for a deeper understanding of the pathophysiology of overconditioning, a quantitative proteomics approach was used together with bioinformatics analyzes to investigate the changes in the plasma proteome of optimally and over-conditioned dairy cows during the transition period. A large portion of the plasma proteome was strongly influenced by lactation stage and exhibited longitudinal changes, with inflammation, immune responses, and acute phase response being most affected. Overconditioning around calving was found to be associated with changes in signaling pathways related to the acute inflammatory167 response and regulation of complement and coagulation cascades in transition cows. Our results are a first step toward understanding the complexity of longitudinal and individual variations in the plasma proteome of over-conditioned cows. We also compared the serum miRNA profile of optimal and over-conditioned dairy cows during the transition period and performed pathway enrichment analyzes. We found only subtle differences in circulating miRNA in optimally or overconditioned cows, so we could not derive potential biomarkers. However, we observed a longitudinal shift in serum miRNA profiles, independent of body condition. Our knowledge of miRNA pathways was extended to a higher level by identifying the most enriched pathways associated with cell cycle and insulin signaling, glucose and lipid metabolism, and many other pathways involving DE-miRNA.
In Chapter 3, different machine learning approaches were used to analyze metabolic phenotypes and body condition variability in periparturient dairy cows. Accordingly, in one publication, data from a large cohort of multiparous Holstein cows were subjected to cluster analysis to characterize interindividual differences in the relationship between BFT ap and subsequent BFT losses during early lactation. Specifically, a lack of consistency in adaptation responses during lactation was observed in over-conditioned cows, and the over-conditioned cows with the least BFT loss produced less milk than over-conditioned cows with greater BFT loss. In another study, we used various machine learning algorithms and serum metabolomics data to see whether we could distinguish divergent metabolic patterns from apparently similar BCS phenotypes. According to the study, HBCS-PN cows consumed more feed and energy than HBCSPH cows, but produced milk with a higher protein content, resulting in a lower NEB. The results suggest that determining overconditioning based on BCS and BFT alone may not be sufficient to adequately address the needs of all individuals, such as management and feeding.

Characterization of the phenylboronic acid-induced defects in primary roots of maize (Zea mays L.) and the association of boron homeostasis with the benzoxazinoid pathway

2026-05-19T00:00:00Z

Characterization of the phenylboronic acid-induced defects in primary roots of maize (Zea mays L.) and the association of boron homeostasis with the benzoxazinoid pathway Chu, Liuyang Boron is an essential micronutrient for plants. In planta, boron predominantly resides in the primary cell wall, crosslinking the pectic polysaccharide rhamnogalacturonan II (RG-II), which is vital for maintaining cell wall integrity. Non-optimal levels of boron negatively affect the development of plants and reduce crop yield. In adaptation to variable soil boron conditions, plants have developed mechanisms to maintain boron homeostasis, of which the best known are boron transporters. In the cereal crop and model plant maize (Zea mays L.), the importance of boron during reproductive development is well studied, and genes encoding boron transporters have been characterized. However, the effects of boron deficiency on the maize root, and regulators of boron homeostasis in maize next to boron transporters, remain largely obscure.
To assess boron deficiency-induced defects in maize roots, one strategy is to induce boron deficiency using a chemical approach. Phenylboronic acid (PBA) was hypothesized to inhibit RG-II dimerization and therefore might mimic boron deficiency. However, the characterization of PBA as a boron deficiency mimic in planta has not been demonstrated.
To identify new regulators of boron homeostasis in maize, one strategy is to assess natural variation of boron concentration in association panels, and to subsequently analyze the phenotypic variation with the genetic variation through genome-wide association analysis (GWAS).
This thesis characterized the boron deficiency-induced defects in maize roots, tested the usability of PBA as a boron deficiency mimic, and identified additional regulators of boron homeostasis in maize leaves using GWAS.
In chapter 2, the primary root defects induced by boron deficiency and by PBA were characterized and compared. Both boron deficiency and PBA induced defects in primary root length, lateral root density, auxin levels and reactive oxygen species levels. Although the PBA-induced defects were similar to the boron deficiency-induced defects, the severity was different. Notably, PBA did not inhibit nor promote RG-II crosslinking in vitro, and PBA did not incorporate into pectin in vivo. Specifically, the PBA-induced lateral root density defects appeared linked to functions of the boric acid moiety. Using the ratios of primary root length and lateral root density between PBA treatment and no-PBA control, putative targets of PBA related to phytohormones, cell wall modification, endocytosis, and root development were detected through GWAS.
In chapter 3, a GWAS of boron levels in maize ear leaves was conducted to identify novel genetic regulators of boron homeostasis. Integrated analysis of the GWAS results and gene expression data highlighted benzoxazinless3 (bx3) as a promising candidate, suggesting an association between leaf boron homeostasis and the benzoxazinoid pathway, a well-characterized defense pathway. The loss-of-function mutation of bx3 in maize and the overexpression of BX1 and BX2 in Arabidopsis, a species that does not endogenously express the benzoxazinoid pathway, both resulted in elevated boron levels in leaves. Furthermore, the product of the BX3 enzyme function, 3-hydroxy-indolin-2-one (HION), was found to form a complex with boric acid in vitro. Our study, therefore, detected a novel connection between boron homeostasis and the benzoxazinoid pathway, likely through bx3 and the direct substrate and product of BX3, furthermore suggesting a potential target for crop engineering for better adaptability to low soil boron levels.; Bor ist ein essentieller Mikronährstoff für Pflanzen. In Pflanzen befindet sich Bor überwiegend in der primären Zellwand, wo es das pektische Polysaccharid Rhamnogalacturonan II (RG-II) vernetzt. Diese Vernetzung ist entscheidend für die Aufrechterhaltung der Zellwandintegrität. Nicht-optimale Konzentrationen von Bor beeinträchtigen die Pflanzenentwicklung und verringern den Ernteertrag. Zur Aufrechterhaltung der Borhomöostase haben Pflanzen unterschiedliche Mechanismen entwickelt, von denen die bekanntesten über Bortransporter wirken. Bei der Nutz- und Modellpflanze Mais (Zea mays L.) ist die Bedeutung von Bor während der reproduktiven Entwicklung gut untersucht. Zusätzlich sind auch die Bortransporter in Mais charakterisiert. Dennoch bleiben die Auswirkungen von Bormangel auf die Maiswurzel sowie Regulatoren der Bor-Homöostase neben den Transportern weitgehend unklar.
Um Bormangel-bedingte Defekte in Maiswurzeln zu untersuchen, besteht eine Strategie darin, Bor-Mangelbedingungen chemisch zu induzieren. Es wird angenommen, dass Boronsäuren, wie Phenylborsäure (PBA), die Dimerisierung von RG-II blockieren und dadurch Bormangel imitieren. Eine Charakterisierung von PBA in Bezug auf dessen Fähigkeit Bormangel in planta zu induzieren wurde jedoch bisher nicht durchgeführt.
Zur Identifizierung neuer Regulatoren der Bor-Homöostase in Mais können beispielsweise genomweite Assoziationsanalysen (GWAS) durchgeführt werden. Dabei wird die natürliche Variation von Merkmalen, z. B. die Borkonzentration, in genetischen Populationen erfasst und anschließend die phänotypische Variation mit genetischen Informationen der Population assoziiert.
Diese Dissertation charakterisierte die durch Bormangel verursachten Defekte in Maiswurzeln, prüfte die Verwendbarkeit von PBA zur Induzierung von Bormangel und identifizierte neue Regulatoren der Bor-Homöostase in Mais.
In Kapitel 2 wurden die durch Bormangel und durch PBA induzierten Primärwurzeldefekte charakterisiert und verglichen. Sowohl Bormangel als auch PBA führten zu Defekten in der Primärwurzel-Länge, der Dichte der Seitenwurzeln, sowie dem Gehalt an Auxin und reaktiver Sauerstoffspezies. Obwohl die durch PBA induzierten Defekte denjenigen des Bormangels ähnelten, unterschieden sie sich in ihrer Ausprägung. Auffällig war, dass PBA in vitro weder die RG-II-Vernetzung hemmte noch förderte und in vivo nicht in Pektin eingebaut wurde. Insbesondere schienen die durch PBA hervorgerufenen Defekte in der Seitenwurzel-Dichte mit Funktionen der Borsäure-Gruppe zusammenzuhängen. Durch die Analyse der Verhältnisse von Primärwurzel-Länge und Seitenwurzel-Dichte zwischen PBA-Behandlung und Kontrollbedingungen konnten mittels GWAS potenzielle PBA-Zielgene identifiziert werden, die im Zusammenhang mit Phytohormonen, Zellwandmodifikation, Endozytose und Wurzelentwicklung standen.
In Kapitel 3 wurde eine GWAS der Borgehalte in Mais-Kolbenblättern durchgeführt, um neue genetische Regulatoren der Bor-Homöostase zu identifizieren. Die integrierte Analyse der GWAS-Ergebnisse mit öffentlich verfügbaren Genexpressionsdaten hob benzoxazinless3 (bx3) als vielversprechendes Kandidatengen hervor und deutete auf eine Verbindung zwischen der Bor-Homöostase in Blättern und dem Benzoxazinoid-Stoffwechselweg hin. Sowohl die Funktionsverlust-Mutation von bx3 in Mais als auch die gleichzeitige Überexpression von BX1 und BX2 in Arabidopsis, einer Art, die den Benzoxazinoid-Stoffwechselweg endogen nicht exprimiert, führten zu erhöhten Borgehalten in Blättern. Darüber hinaus wurde festgestellt, dass das Produkt der BX3-Enzymfunktion, 3-Hydroxy-Indolin-2-on, in vitro einen Komplex mit Borsäure bilden kann. Somit zeigte unsere Studie, dass der Benzoxazinoid-Stoffwechselweg in Mais mit der Bor-Homöostase verknüpft ist, wahrscheinlich über bx3 sowie das direkte Substrat und Produkt von BX3. Somit wurde in dieser Dissertation ein potenzielles Ziel für die Pflanzenzüchtung zur besseren Anpassungsfähigkeit von Mais an geringe Borgehalte im Boden identifiziert.

Funktionelle Genomik der Keimlingswurzeln von Mais (Zea mays L.)

2026-05-19T00:00:00Z

Funktionelle Genomik der Keimlingswurzeln von Mais (Zea mays L.) Marcon, Caroline Die in der vorliegenden Habilitationsschrift zusammengefassten Forschungsarbeiten umfassen erstens molekulargenetische Untersuchungen, sowie Transkriptom- und Proteomanalysen der jungen Keimlingswurzeln von Mais (Zea mays L.) und zweitens die Herstellung einer Kollektion von Maismutanten für funktionell genomische Analysen. In den nachfolgenden Kapiteln sind die Referenzen mit eigener Publikationsbeteiligung farblich hervorgehoben. Detaillierte Beschreibungen der hier in den Kontext gestellten Forschungsergebnisse und deren Diskussion, in Form von Original-Publikationen, finden sich im Anhang (Kapitel 10).

International Trade: Determinants of Patterns and Policy Impacts

2026-05-18T00:00:00Z

International Trade: Determinants of Patterns and Policy Impacts Jafari, Yaghoob International trade is shaped by various factors affecting firms— the main trade actors— and the economic environment in which they operate. This economic environment may relate to country and country-pair specific factors and policies; the formation and deformation of economic agreements; and the global factors and policies that affect the overall functioning of the trading system. Changes in factors affecting firms and their economic environment can affect trade patterns directly and indirectly, interacting with the rest of the economy. The research presented in this thesis analyzes the relevance of factors at different scales (firm level, country level, economic partnership level, and global level) in shaping international trade patterns and their consequences beyond trade impacts. It also introduces several theoretical, methodological, and data contributions that advance such analyses. Overall, this research highlights that factors at different scales may relate to firms' fixed and variable costs and product prices. Changes in those factors, as long as they are aligned with firms' profitability, can increase firms' trade activities. As firms increase their trade activities, their performance measures may improve. This involves impacts on the environment in which firms operate.