Publications by authors named "Iris Klaiber"

Free amino acids (AA) are needed to fulfill the AA requirements of broiler chickens in diets low in CP. This study investigated whether the acid-base balance and the blood plasma metabolome are affected immediately after a change to diets with high free AA levels. Male broiler chickens received a starter diet with 164 g CP/kg and 80 g soy protein isolate/kg until d 7 post-hatch.

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Attempts have been made to determine the and suppressive potential of particular strains (T16 and T23) and their secondary metabolites (SMs) against Asian soybean rust (ASR) incited by . Aside from the previously identified SMs 6-pentyl-α-pyrone (6PAP) and viridiofungin A (VFA), the chemical structures of harzianic acid (HA), iso-harzianic acid (iso-HA), and harzianolide (HZL) were characterized in this study. Our results indicate that exposure of urediospores to 200 ppm 6PAP completely inhibits germination.

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Background: Certain Fusarium exometabolites have been reported to inhibit seed germination of the cereal-parasitizing witchweed, Striga hermonthica, in vitro. However, it is unknown if these exometabolites will consistently prevent S. hermonthica incidence in planta.

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Orotic acid (OA) is an intermediate of the pyrimidine biosynthesis with high industrial relevance due to its use as precursor for production of biochemical pyrimidines or its use as carrier molecule in drug formulations. It can be produced by fermentation of microorganisms with engineered pyrimidine metabolism. In this study, we surprisingly discovered the yeast Yarrowia lipolytica as a powerful producer of OA.

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Article Synopsis
  • Quinoa is a highly nutritious superfood known for being gluten-free and tolerant to various environmental stresses like drought and salinity.
  • The study focused on the epidermal bladder cells (EBCs) of quinoa, analyzing their metabolomes and lipidomes under different abiotic stress conditions using advanced mass spectrometry techniques.
  • Results revealed that while EBCs contained a variety of primary and secondary metabolites as well as lipids, only minor metabolic changes occurred in response to heat, cold, and high-light stresses, with Na levels being significantly lower than K levels across all treatments.
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  • The study examines flower bud induction in apple trees, focusing on the biennial-bearing 'Fuji' and regular-bearing 'Gala' cultivars, comparing buds from trees with high (ON) and low (OFF) crop loads.
  • It utilizes a multi-omics approach, including RNA sequencing and proteomics, to explore the physiological and molecular mechanisms of bud development before flower initiation.
  • Key findings reveal significant differences in metabolic profiles and gene expressions related to flower bud induction, highlighting variations in important compounds like thiamine and chlorogenic acid between the cultivars and crop load statuses.
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Biological nitrification inhibition (BNI) of Brachiaria humidicola has been attributed to nitrification-inhibiting fusicoccanes, most prominently 3-epi-brachialactone. However, its release mechanism from B. humidicola roots remains elusive.

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Extracts of kidney vetch (Anthyllis vulneraria L.) are becoming increasingly interesting as ingredients for the health and cosmetics industry. However, comprehensive phytochemical investigations of this plant are scant in the literature.

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Despite intensive research in recent years, the biosynthetic route to costunolide in sunflower so far remained obscured. Additional P450 sequences from public sunflower transcriptomic database were screened to search for candidate enzymes which are able to introduce the 6α-hydroxy-group required for the esterification with the carboxy group of germacarane A acid, the final step in costunolide formation. CYP71BL9, a new P450 enzyme from sunflower was shown to catalyze this hydroxylation, hence being identified as HaCOS.

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Sesquiterpene lactones (STL) are a subclass of isoprenoids with many known bioactivities frequently found in the Asteraceae family. In recent years, remarkable progress has been made regarding the biochemistry of STL, and today the biosynthetic pathway of the core backbones of many STLs has been elucidated. Consequently, the focus has shifted to the discovery of the decorating enzymes that can modify the core skeleton with functional hydroxy groups.

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The quality of grapevine berries, must and wine is influenced by environmental and viticultural inputs and their complex interactions. Aroma and flavour are decisive for quality and are mainly determined by primary and secondary metabolites. In particular, phenolic compounds contribute to berry and wine quality.

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Biosurfactants are amphiphilic molecules that interact with the surfaces of liquids leading to many useful applications. Most biosurfactants have been identified from cultured microbial sources, leaving a largely untapped resource of uncultured bacteria with potentially novel biosurfactant structures. To access the uncultured bacteria, a metagenomic library was constructed in Escherichia coli from environmental DNA within an E.

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We established an efficient fed-batch fermentation process for two novel dirigent proteins from cotton plants, GbDIR2 from Gossypium barbadense and GhDIR3 from G. hirsutum, using the engineered Pichia pastoris GlycoSwitch® SuperMan strain to prevent hyperglycosylation. The two (His)-tagged proteins were purified by metal-chelate affinity chromatography and obtained in quantities of 12 and 15 mg L of culture volume, respectively.

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Gossypol is a defense compound in cotton plants for protection against pests and pathogens. Gossypol biosynthesis involves the oxidative coupling of hemigossypol and results in two atropisomers owing to hindered rotation around the central binaphthyl bond. (+)-Gossypol predominates in vivo, thus suggesting stereochemically controlled biosynthesis.

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Uniseriate linear glandular trichomes occur on stems, leaves and flowering parts of Helianthus species and related taxa. Their metabolic activity and biological function are still poorly understood. A phytochemical study documented the accumulation of bisabolene type sesquiterpenes and flavonoids as the major constituents of the non-volatile metabolome of linear glandular trichomes in the common sunflower, Helianthus annuus.

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Unlabelled: To increase the efficiency of biocatalysts a thorough understanding of the molecular response of the biocatalyst to precursors, products and environmental conditions applied in bioconversions is essential. Here we performed a comprehensive proteome and phospholipid analysis to characterize the molecular response of the potential biocatalyst Pseudomonas putida KT2440 to the next-generation biofuel n-butanol. Using complementary quantitative proteomics approaches we were able to identify and quantify 1467 proteins, corresponding to 28% of the total KT2440 proteome.

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Unlabelled: Understanding of the molecular response of bacteria to precursors, products and environmental conditions applied in bioconversions is essential for optimizing whole-cell biocatalysis. To investigate the molecular response of the potential biocatalyst Pseudomonas putida KT2440 to the flavor compound vanillin we applied complementary gel- and LC-MS-based quantitative proteomics approaches. Our comprehensive proteomics survey included cytoplasmic and membrane proteins and led to the identification and quantification of 1614 proteins, corresponding to 30% of the total KT2440 proteome.

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Numerous peptides generated by triptic hydrolysis of micellar casein and β-casein from bovine milk have been reported to exhibit bio-functional or techno-functional activities. In this study, the focus was placed on the quantification of eleven potential functional peptides generated by enzymatic hydrolysis with trypsin. The identity of the target peptides was verified by LC-ESI-MS/MS and a reverse phase high performance liquid chromatography method (RP-HPLC) was established to quantify the peptides.

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MAPK signalling is a complex process not only requiring the core components Raf, MEK and Erk, but also many proteins like the scaffold protein KSR and several kinases to specifically localize, modulate and fine-tune the outcome of the pathway in a cell context specific manner. In mammals, protein kinase CK2 was shown to bind to the scaffold protein KSR and to phosphorylate Raf proteins at a conserved serine residue in the negative-charge regulatory (N-) region, thereby facilitating maximal activity of the MAPK signalling pathway. In this work we show that in Drosophila CK2 is also bound to KSR.

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The first phytochemical analysis of the aquatic macrophyte Stratiotes aloides afforded two new flavonoid glucuronides, luteolin 7-O-beta-D-glucopyranosiduronic acid-(1-->2)-beta-D-glucopyranoside (1) and chrysoeriol 7-O-beta-D-glucopyranosiduronic acid-(1-->2)-beta-D-glucopyranoside (2), as well as the new 2-(2-hydroxypentyl)-5-carboxy-7-methoxychromone (5) and chrysoeriol 7-O-beta-(6-O-malonyl)glucopyranoside (3), which has been assigned via NMR data for the first time. Additionally, free amino acids such as tryptophan, arginine, leucine, isoleucine, phenylalanine, and tyrosine along with choline, cis-aconitic acid, the phenolic glycoside alpha-arbutine, the chlorophyll derivative phaeophorbide a, and the flavonoid glycoside luteolin 7-O-beta-(6-O-malonyl)glucopyranoside (4) were isolated. Despite the low quantities obtained in some cases (between 50-300 microg), the structures of all compounds were unambiguously elucidated by extensive NMR and MS experiments.

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From the n-butanol soluble fraction of the methanol extract of the rhizomes of Smilax excelsa, three new furostanol saponins 3-O-[4-O-acetyl-alpha-L-rhamnopyranosyl-(1 --> 2)-{alpha-L-rhamnopyranosyl-(1 --> 4)}-beta-D-glucopyranosyl]-26-O-[beta-D-glucopyranosyl]-22alpha-hydroxy-(25R)-furost-5-ene-3beta,26-diol (1), 3-O-[2-O-acetyl-alpha-L-rhamnopyranosyl-(1 --> 2)-{alpha-L-rhamnopyranosyl-(1 --> 4)}-beta-D-glucopyranosyl]-26-O-[beta-D-glucopyranosyl]-22alpha-hydroxy-(25R)-furost-5-ene-3beta,26-diol (2), 3-O-[3-O-acetyl-alpha-L-rhamnopyranosyl-(1 --> 2)-{alpha-L-rhamnopyranosyl-(1 --> 4)}-beta-D-glucopyranosyl]-26-O-[beta-D-glucopyranosyl]-22alpha-hydroxy-(25R)-furost-5-ene-3beta,26-diol (3), and three known saponins: protodioscin (4), pseudoprotodioscin (5) and dioscin (6) were isolated.

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5-Hydroxy-3-oxopent-4-enoic acid esters can be efficiently transformed into the stable bis-potassium salts of the corresponding 5-hydroxy-3-oxopent-4-enoic acids, from which the sensitive acids are released in situ, the latter being converted into substituted 4-hydroxy-2H-pyran-2-ones, pyrazoles and isoxazoles under mild conditions; the efficiency of this method is demonstrated by the first synthesis of two naturally occurring pyrones.

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Two new cyclic heptapeptides, integerrimides A and B, have been isolated from the latex of Jatropha integerrima. Their structures were elucidated by using extensive 1D and 2D NMR, MS, and chemical degradation. At 50 microM both peptides 1 and 2 significantly inhibited neurite outgrowth in neuronal cell culture.

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