Gall midge olfaction: Pheromone sensitive olfactory neurons in Contarinia nasturtii and Mayetiola destructor

This study describes the morphology and function of the antennal sensilla in two gall midge species, Contarinia nasturtii and Mayetiola destructor, where multi-component sex pheromones have been identified. Both species possess sensilla trichodea, s. coeloconica, s. chaetica and s. circumfila. Sensilla circumfila, which consist of several sensilla that bifurcate and fuse into one structure, are unique for the gall midges. In C. nasturtii s. circumfila are sexually dimorphic. In males, they form elongated loops suspended on cuticular spines, whereas in females they run like worm-like structures directly on the antennal surface. Single sensillum recordings demonstrated that olfactory sensory neurons housed in male s. circumfila in C. nasturtii responded to the female sex pheromone. In M. destructor, s. circumfila were attached to the antennal surface in both sexes, and displayed no response to sex pheromone components.A sexual dimorphism was also found in the number of s. trichodea per antennal segment in both C. nasturtii (male 1 vs. female 7) and M. destructor (male 13 vs. female 10). OSNs located in male M. destructor s. trichodea responded to the sex pheromone. This is the first gall midge single sensillum study, and the first demonstration of the functional significance of s. circumfila.     

Flavour formation by amino acid catabolism

Microbial catabolism of amino acids produces flavour compounds of importance for foods such as cheese, wine and fermented sausages. Lactic acid bacteria are equipped with enzyme systems for using the amino acids in their metabolism and are useful for flavour formation of foods. Branched-chain amino acids (Leu, Ile, Val) are converted into compounds contributing to malty, fruity and sweaty flavours; catabolism of aromatic amino acids (Phe, Tyr, Trp) produce floral, chemical and faecal flavours; aspartic acid (Asp) is catabolised into buttery flavours and sulphuric amino acids (Met, Cys) are transferred into compounds contributing to boiled cabbage, meaty and garlic flavours.     

Human-associated extended-spectrum β-lactamase in the Antarctic

Escherichia coli bacteria with extended-spectrum β-lactamase (ESBL) type CTX-M resistance were isolated from water samples collected close to research stations in Antarctica. The isolates had bla(CTX-M-1) and bla(CTX-M-15) genotypes and sequence types (ST) indicative of a human-associated origin. This is the first record of ESBL-producing enterobacteria from Antarctica.     

TOF-SIMS analysis of lipid accumulation in the skeletal muscle of ob/ob mice

Skeletal muscle lipid accumulation is associated with several chronic metabolic disorders, including obesity, insulin resistance (IR) and type 2 diabetes. The aim of this study is to evaluate whether static imaging time-of-flight-secondary-ion mass spectrometry (TOF-SIMS) equipped with a Bismuth-cluster ion source can be used for studying skeletal muscle lipid accumulation associated with obesity. Mouse gastrocnemius muscle tissues in 10-week-old obese ob/ob (n = 8) and lean wild-type C57/BL6 (n = 6) mice were analyzed by TOF-SIMS. Our results showed that signal intensities of fatty acids (FAs) and diacylglycerols (DAGs) were significantly increased in skeletal muscle of the obese ob/ob mice as compared to the lean wild-type mice. These differences were revealed through a global analytical approach, principal component analysis (PCA) of TOF-SIMS spectra, and ion-specific TOF-SIMS images. Region-of-interest (ROI) analysis showed that FA signal intensities within the muscle cell were significantly increased in ob/ob mice. Moreover, analysis of the ratio between different FA peaks revealed changes in monounsaturated FAs (MUFAs) and polyunsaturated FAs (PUFAs), which is in agreement with previous reports on obesity. These changes in FA composition were also reflected in the ratio of different DAGs or phosphatidylcholines (PCs) that contain different FA residues. Imaging TOF-SIMS together with PCA of TOF-SIMS spectra is a promising tool for studying skeletal muscle lipid accumulation associated with obesity.     

Bifidobacteria-mediated immune system imprinting early in life

1. Download : Download high-res image (173KB)
2. Download : Download full-size image

     

Effect of mycorrhizal colonization and phosphorus on ethylene production by snapdragon (Antirrhinum majus L.) flowers

 We determined the effects of phosphorus (P) concentration and mycorrhizal colonization on ethylene production by flowers of snapdragons (Antirrhinum majus L.). Mycorrhizal colonization in a soil-less medium did not significantly affect the total number of flowers per spike or flower P concentration, but it significantly increased flower vase-life and significantly decreased flower ethylene production. This demonstrates for the first time that mycorrhizal colonization can have a non-localized effect on host ethylene production. The reduction in ethylene production caused by mycorrhizal colonization was as large as the variation in ethylene production among snapdragon cultivars. Thus, mycorrhizal colonization may be a viable alternative to toxic ethylene inhibitors such as silver thiosulfate. Increased fertilizer P concentration (15 versus 3 μg P ml^–1) significantly increased plant fresh weight and the total number of flowers per spike. In contrast to mycorrhizal colonization, increased fertilizer P concentration resulted in an increase in ethylene production. There was no significant effect of fertilizer P concentration on vase-life. This suggests that factors other than ethylene have at least partial control over vase-life. Postharvest amendment of individual flowers with phosphate also significantly increased flower ethylene production. Phosphorus apparently does not mediate the mycorrhizal effect because mycorrhizal colonization decreased ethylene production without significantly influencing flower P concentration. Moreover, treatment with phosphate increased flower ethylene production. Mycorrhizal colonization did not significantly influence response to exogenous ethylene. Accepted: 14 June 1999     

Intestinal absorption of copper from drinking water containing fulvic acids and an infant formula mixture studied in a suckling rat model

The purpose of this study was to investigate if the intestinal absorption of copper in drinking water is altered in the presence of complexing agents from a fulvic acid mixture and an infant formula powder. Ten to twelve day old rat pups were given a single oral dose of radio-labeled Cu in deionized water (0.93 mg Cu/l), in water containing fulvic acids (10 mg/l), in infant formula mixed with deionized water, or in infant formula mixed with water containing fulvic acids. Six hours after dosage, radioactive Cu was analyzed in the mucosa of the small intestine, the liver and the remaining carcass (excluding the liver and gastrointestinal tract) by gamma counting. Dialysis and centrifugation experiments showed that Cu was complexed by components in the fulvic acid and formula mixtures, although the presence of fulvic acids in the water did not alter the Cu fractionation in the formula. The fractional Cu uptake (% of dose) from the intestinal lumen to the mucosa was not markedly changed by the presence of the chelating agents. However, the retention of Cu in the intestinal mucosa was increased by both fulvic acids and formula. Concomitantly, the absorption rate of Cd to the circulatory system was decreased. No interactive effect between fulvic acids and formula was found on the Cu absorption. These findings indicate that the water quality may be an important determinant of the rate of intestinal Cu absorption from drinking water. Moreover, in the future risk assessment of copper in drinking water, the possibility of alterations in absorption of drinking-water Cu has to be considered when the drinking water is used for cooking.