Nutritional Value of the Duckweed Species of the Genus Wolffia (Lemnaceae) as Human Food

Species of the genus Wolffia are traditionally used as human food in some of the Asian countries. Therefore, all 11 species of this genus, identified by molecular barcoding, were investigated for ingredients relevant to human nutrition. The total protein content varied between 20 and 30% of the freeze-dry weight, the starch content between 10 and 20%, the fat content between 1 and 5%, and the fiber content was ~25%. The essential amino acid content was higher or close to the requirements of preschool-aged children according to standards of the World Health Organization. The fat content was low, but the fraction of polyunsaturated fatty acids was above 60% of total fat and the content of n-3 polyunsaturated fatty acids was higher than that of n-6 polyunsaturated fatty acids in most species. The content of macro- and microelements (minerals) not only depended on the cultivation conditions but also on the genetic background of the species. This holds true also for the content of tocopherols, several carotenoids and phytosterols in different species and even intraspecific, clonal differences were detected in Wolffia globosa and Wolffia arrhiza. Thus, the selection of suitable clones for further applications is important. Due to the very fast growth and the highest yield in most of the nutrients, Wolffia microscopica has a high potential for practical applications in human nutrition

Wehrchemie in Blattkäfern: Aufklärung eines neuen Acylierungskomplexes in Insekten am Beispiel von Chrysomela lapponica

Im Laufe der Evolution haben Blattkäfer (Coleoptera: Chrysomelidae) erstaunlich vielfältige Verteidigungsmechanismen gegen Fraßfeinde entwickelt. Dazu gehören nicht nur morphologische Charakteristika und bestimmte Verhaltensweisen, sondern auch eindrucksvolle chemische Verteidigungsstrategien. Die sogenannte Interrupta-Gruppe der Chrysomelinae, der die in dieser Arbeit untersuchte Spezies Chrysomela lapponica angehört, zeigt ein sehr breites Spektrum an Wehrsubstanzen, welches von über 70 verschiedenen Estern dominiert wird, sofern die Spezies auf Birke oder anderen salicinarmen Wirtspflanzen leben. Fressen Interrupta-Spezies auf salicinreichen Weiden bevorzugen sie die Bildung von Salicylaldehyd. Der Fokus dieser Dissertation lag auf der Aufklärung des Biosyntheseweges für Ester in den Sekreten der Birke fressenden Spezies. Dieser Acylierungskomplex kombiniert die Aufnahme pflanzenbürtiger Alkohole und die de novo Synthese von Acyldonoren. Von besonderem Interesse war die Aufklärung der reaktiven Acyldonoren, welche als Substrat für die Acyltransferase in der Produktion von Estern dienen. Mit Hilfe von synthetischen Analoga verschiedener Acyldonoren und Aktivitätsassays mit Rohsekret wurden erstmalig 1-O-β-D-Acylglucosen als reaktive Acyldonoren in Insekten nachgewiesen. Durch Isotopenverhältnismassenspektrometrie wurden bestimmte Aminosäuren als Vorstufen für Acyldonoren identifiziert. Die breite Substrattoleranz der involvierten Acyltransferase zusammen mit einem unspezifischen Glucosidimport erklärt die extrem große Variabilität der Substanzen im Wehrsekret. Nicht zuletzt wurde durch Agardiffusionstests bestimmten Estern auch ein antimikrobielles Potential zugeordnet, welches das Überleben der Birke fressenden Populationen sichert

Glucose and Glucose Esters in the Larval Secretion of Chrysomela Lapponica; Selectivity of the Glucoside Import System from Host Plant Leaves

Larvae of Chrysomela lapponica (Coleoptera: Chrysomelidae) sequester characteristic O-glucosides from the leaves of their food plants, namely Betula and/or Salix The present study focuses on birch-feeding larvae of C. lapponica from the Altai region in East Kazakhstan. As in other sequestering leaf beetle larvae, the compounds are transported intact via different membrane barriers into the defensive system, followed by glucoside cleavage and subsequent transformations of the plant-derived aglycones. Unlike previous studies with model compounds, we studied the sequestration of phytogenic precursors by analyzing the complex pattern of glucosides present in food plant Betula rotundifolia (39 compounds) and compared this composition with the aglycones present as butyrate esters in the defensive secretion. In addition to the analytic approach, the insect's ability, to transport individual glucosides was tested by using hydrolysis-resistant thioglucoside analogs, applied onto the leaf surface. The test compounds reach the defensive system intact and without intermediate transformation. No significant difference of the transport capacity and selectivity was observed between larvae of birch-feeding population from Kazakhstan, and previous results for larvae of birch-feeding population from the Czech Republic or willow-feeding populations. Overall, the transport of the phytogenic glucosides is highly selective and highly efficient, since only minor compounds of the spectrum of phytogenic glucoside precursors contribute to the limited number of aglycones utilized in the defensive secretion. Interestingly, salicortin 44 and tremulacin 60 were found in the leaves, but no aldehyde or esters of salicylalcohol. Surprisingly, we observed large amounts of free glucose, together with small amounts of 6-O-butyrate esters of glucose (27a/b and 28a/b). © 2011 Springer Science+Business Media, LLC.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

De novo biosynthesis versus sequestration: A network of transport systems supports in iridoid producing leaf beetle larvae both modes of defense

In the larval chrysomelines the de novo synthesis of monoterpenoids (iridoids) is believed to represent the ancestral state in the evolution of chemical defenses. Here we demonstrate that the iridoid producing larvae of Plagiodera versicolora and Phratora laticollis have the potential to sequester precursors from food. In nature, iridoids may even have a dual origin, namely plant-derived and de novo produced. The ability to sequester plant-derived precursors was proved by (i) 13C-labelling of the terpenoids in the food plant, (ii) by larval feeding on leaves impregnated with analogs and labelled putative precursors for iridoid biosynthesis; and (iii) by injection of the precursors into the hemolymph followed by mass spectroscopic analysis of their distribution in the hemolymph, defensive secretion, and faeces. The experimental findings support a network of transport systems which allows a broader range of glucosides to enter and to leave the hemocoel, while only the appropriate precursor, 8-hydroxygeraniol-8-O-β-d-glucoside, is channelled to the reservoir and processed to iridoids. The dual system of de novo biosynthesis and sequestration of phytogenic precursors may have favoured the larvae to shift from one host plant to another without losing their defense. © 2008 Elsevier Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Sequestration of plant-derived phenolglucosides by larvae of the leaf beetle Chrysomela lapponica: Thioglucosides as mechanistic probes

SCOPUS: ar.jinfo:eu-repo/semantics/publishe