Simultaneous quantitative analysis of maillard reaction precursors and products by high-performance anion exchange chromatography

A new analytical setup allowing the simultaneous analysis of precursors and products of the Maillard reaction is described. It is based on high-performance anion exchange chromatography with electrochemical (ECD) and diode array detectors (DAD) coupled in series. Chromatography and detection were optimized to permit simultaneous monitoring of compounds relevant to the Maillard reaction, such as the sugar, the amino acid, and the corresponding Amadori compound as well as the cyclic intermediates 5-(hydroxymethyl)-2-furaldehyde, maltol, and 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one. Separation was achieved on a CarboPac PA-1 column using a gradient of sodium acetate in aqueous sodium hydroxide. The Amadori compound, glucose, and glycine were monitored by an ECD operating in the integrated amperometry mode. The number of analyzed compounds was further increased by coupling the ECD with a DAD for the analysis of ultraviolet-active constituents. This method was successfully applied to model Maillard reaction mixtures based on glucose and glycine.     

Establishment of planted Norway spruce and Scots pine seedlings: effects of light environment,fertilisation, and orientation and distance with respect to shelter trees

The effects of stand stem density (SSD), orientation and distance with respect to shelter trees, and fertilisation on planted Pinus sylvestris and Picea abies seedlings were examined at two sites, one with a southerly aspect (64°14′N, 19°46′E, 225 m a.s.l.) and one with a northerly aspect (64°09′N, 19°36′E, 274 m a.s.l.) in boreal forests in Sweden. The damage and growth were compared at these sites in stands with three SSD’s and different light regimes: uncut forest (SSD 500, ~500 stems/ha), shelterwood (SSD 150,~150 stems/ha), and clear-cut (SSD, 0 stems). Half of the seedlings were irrigated with fertiliser (10 mM N). Fertilisation and SSD affected the height growth of P. abies, since fertilised seedlings in SSD 0 grew the most (22.2 cm). Fertilised seedlings in SSD 0 also generally had the greatest biomass (twigs, leading shoot and needles), even P. sylvestris seedlings on the North slope, where fertilised and unfertilised pine seedlings in SSD 0 had 62.6 and 39.7 g biomass, respectively. P. sylvestris increased about 150% in dry mass of leading shoot of the increase of P. abies with equal height growth, when comparing SSD 150 and SSD 0. The results indicate that the general conditions of the stand have stronger effects on the growth of planted seedlings than their orientation and distance with respect to the nearest tree and that light requirements cannot be moderated by fertilisation. We postulate that a system in which forest gaps are formed under a shelterwood could provide a way to regenerate forests that exploits the beneficial features of both shelter trees and clear-cuts.     

Genetic diversity analysis in Phaseolus vulgaris L. using morphological traits

Common bean (Phaseolus vulgaris) is an important export crop in Kyrgyzstan since the end of the twentieth century. Genetic diversity analysis of common bean populations is useful for breeding programs, as it helps to select genetic material to be used for further crossing. Twenty-seven common bean accessions were analyzed using 13 qualitative morphological traits. In some cases, obtained morphological data were combined with previously published results based on microsatellite markers. The similarity matrices generated from the molecular and morphological data were significantly correlated (r = 0.49, P < 0.01). Cluster analyses based on Dice’s similarity coefficient were constructed based on morphological data and the combined data set of morphology and microsatellite, and both grouped the 27 accessions according to their origin: 15 belonged to the Andean and 12 to the Mesoamerican gene pool. On average, the Andean accessions were less diverse than the Mesoamerican accessions. The average diversity based on the Shannon diversity index for the 13 qualitative morphological traits was 0.05. Overall, this study revealed that qualitative morphological markers are efficient in assigning modern cultivars to their gene pools of origin.     

Sugar fragmentation in the maillard reaction cascade: isotope labeling studies on the formation of acetic acid by a hydrolytic beta-dicarbonyl cleavage mechanism

The formation of acetic acid was elucidated based on volatile reaction products and related nonvolatile key intermediates. The origin and yield of acetic acid were determined under well-controlled conditions (90-120 degrees C, pH 6-8). Experiments with various 13C-labeled glucose isotopomers in the presence of glycine revealed all six carbon atoms being incorporated into acetic acid: C-1/C-2 ( approximately 70%), C-3/C-4 ( approximately 10%), and C-5/C-6 (approximately 20%). Acetic acid is a good marker of the 2,3-enolization pathway since it is almost exclusively formed from 1-deoxy-2,3-diulose intermediates. Depending on the pH, the acetic acid conversion yield reached 85 mol % when using 1-deoxy-2,3-hexodiulose (1) as a precursor. Hydrolytic beta-dicarbonyl cleavage of 1-deoxy-2,4-hexodiuloses was shown to be the major pathway leading to acetic acid from glucose without the intermediacy of any oxidizing agents. The presence of key intermediates was corroborated for the first time, i.e., tetroses and 2-hydroxy-3-oxobutanal, a tautomer of 1-hydroxy-2,3-butanedione, also referred to as 1-deoxy-2,3-tetrodiulose. The hydrolytic beta-dicarbonyl cleavage represents a general pathway to organic acids, which corresponds to an acyloin cleavage or a retro-Claisen type reaction. Although alternative mechanisms must exist, the frequently reported hydrolytic alpha-dicarbonyl cleavage of 1 can be ruled out as a pathway forming carboxylic acids.     

Effect of diets on carotenoid content,body coloration,biochemical composition and spermatophore quality in the “red cherry” shrimp Neocaridina davidi (Caridea,Atyidae)

In aquarium industry trade markets, Neocaridina davidi, the “red cherry” shrimp, is one of the most attractive ornamental shrimps due to the striking reddish coloration of females. Five commercial diets formulated for ornamental species were evaluated over a 90‐day period in N. davidi males and females, based on survival, biochemical composition, body weight, carotenoid content and body coloration. Furthermore, histological and histochemical analyses of the male reproductive system were performed to evaluate the spermatophore quality. In all treatments, survival was >80%, and protein content was similar in both female and male shrimps. Lipid content was higher in females and males fed on a diet having the highest lipid level. Carotenoid content was higher and body coloration was brighter in females and males fed on a diet containing the highest carotenoid level. Histological and histochemical analyses of the spermatophore structure and composition showed no differences among diets, suggesting that the five commercial diets are adequate for satisfactory growth and spermatophore quality of N. davidi. The diverse sources and quantities of carotenoids in the highest carotenoid level diet render it more suitable for colour enhancement of this species.     

Breeding and life cycle of the ornamental freshwater shrimp Neocaridina davidi in a biofilm‐based culture system

Neocaridina davidi is a popular shrimp in the aquarium industry; however, information regarding its husbandry is scarce. In this study, we investigated the contribution of biofilm to its life cycle, comprising three successive phases: (1) the evaluation of biofilm growth on plastic nets (PN), plastic sheets (PS) and agrovelo (AV); (2) the reproduction of adult shrimp to get juveniles (JI); and (3) the effects of biofilm on the survival and growth performance of JI. Trials were performed in aquaria with zero water exchange and natural environmental conditions. Biofilm was composed mainly of microalgae, diatoms, cyanobacteria and ciliates and used as the sole diet. Survival, biomass and biochemical reserves of JI reared in this culture system were significantly higher in the presence of PN and AV substrates. The occurrence of ovarian maturation and egg incubation of female shrimp in these treatments indicate that biofilm supplied the energy required for somatic growth and fecundity. Harvested females also displayed the size and the red pigmentation associated with premium pricing. Based on these results, it is concluded that N. davidi can complete the life cycle and display characteristic life history traits in a low‐cost biofilm technology system without losing economic value as ornamental species.     

Pan‐continental invasion of Pseudorasbora parva: towards a better understanding of freshwater fish invasions

In recent years, policy‐makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non‐target species that are unknowingly released alongside intentionally‐introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan‐continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits.