Biomedical subjects

Bernard Grodzinski

Publications and source records attributed to Bernard Grodzinski.

4 recordsLinked to original sources

PubMed2006

Diel patterns of leaf C export and of main shoot growth for Flaveria linearis with altered leaf sucrose-starch partitioning.

Diel C export from source leaves of two Flaveria linearis lines [85-1: high cytosolic fructose-1,6-bisphosphatase (cytFBPase) and 84-9: low cytFBPase] were estimated using three methods, including leaf steady-state (14)CO(2) labelling, leaf metabolite analysis, and leaf dry mass analysis in conjunction with leaf CO(2) exchange measurements. Synthesis and accumulation of starch during the daytime were much higher in 84-9. Relative (14)C-export (export as a % of photosynthesis) in the light was 36% higher in 85-1. The diel export patterns from (14)C-analyses correlated with those based on metabolite or dry weight/gas exchange analyses during the daytime, but not during the night. Night-time export estimated from (14)C-disappearance was 3.6 times lower than those estimated using the other methods. Even though the starch degradation at night was greater for 84-9, night-time export in 84-9 was similar to 85-1, since 84-9 showed both higher respiration and accumulation of soluble sugars (i.e. glucose) at night. Patterns of (14)C allocation to sink organs were also different in the two lines. Main stem growth was less in 84-9, being reduced most in the light when leaf export was lower relative to 85-1. Supplementation with sucrose for 1 h daily via the roots at a time when leaf export in 84-9 was low relative to 85-1 increased the stem growth rate of 84-9 to a level similar with that of 85-1. This study provides evidence that diel C availability predicted by source strength (e.g. C-export rate) influences main stem extension growth and the pattern of sink development in F. linearis.

Carbon↗

PubMed2005

An improved method for constructing and selectively silanizing double-barreled, neutral liquid-carrier, ion-selective microelectrodes.

We describe an improved, efficient and reliable method for the vapour-phase silanization of multi-barreled, ion-selective microelectrodes of which the silanized barrel(s) are to be filled with neutral liquid ion-exchanger (LIX). The technique employs a metal manifold to exclusively and simultaneously deliver dimethyldichlorosilane to only the ion-selective barrels of several multi-barreled microelectrodes. Compared to previously published methods the technique requires fewer procedural steps, less handling of individual microelectrodes, improved reproducibility of silanization of the selected microelectrode barrels and employs standard borosilicate tubing rather than the less-conventional theta-type glass. The electrodes remain stable for up to 3 weeks after the silanization procedure. The efficacy of a double-barreled electrode containing a proton ionophore in the ion-selective barrel is demonstrated in situ in the leaf apoplasm of pea (Pisum) and sunflower (Helianthus). Individual leaves were penetrated to depth of approximately 150 microm through the abaxial surface. Microelectrode readings remained stable after multiple impalements without the need for a stabilizing PVC matrix.

Journal Article↗

PubMed2004

A flavanone and two phenolic acids from Chrysanthemum morifolium with phytotoxic and insect growth regulating activity.

Leaves of Chrysanthemum morifolium cv. Ramat were extracted sequentially with hexane, ethyl acetate, and methanol. The methanol fraction, when incorporated into artificial diet was found to reduce the growth of cabbage looper (Trichoplusia ni Hubner) larvae at concentrations between 500 and 5000 ppm of diet. Fractionation of the methanol extract on a Sephadex column yielded five fractions, three of which reduced the weight of larvae relative to the control. One fraction was analyzed using high performance liquid chromatography (HPLC) and found to contain three main constituents. These compounds were purified using a combination of gel permeation chromatography on Sephadex LH20 and HPLC, and analyzed by 1H and 13CNMR as well as undergoing chemical and physical analyses. The compounds were identified as: 1, chlorogenic acid (5-O-caffeoylquinic acid); 2, 3,5-O-dicaffeoylquinic acid; and 3, 3', 4',5-trihydroxyflavanone7-O-glucuronide (eriodictyol7-O-glucuronide). At concentrations between 100 to 1000 ppm these compounds reduced both growth and photosynthesis of Lemna gibba L. with the order of efficacy being: flavanone > chlorogenic acid > 3,5-O-dicaffeoylquinic acid. Furthermore, when incorporated separately into artificial diet these compounds, at 10 to 1000 ppm, enhanced or reduced growth of the cabbage looper (Trichoplusia ni) and gypsy moth (Lymantria dispar L.).

Animal Feed↗

PubMed2003

Daily photosynthetic and C-export patterns in winter wheat leaves during cold stress and acclimation.

Diurnal patterns of whole-plant and leaf gas exchange and 14C-export of winter wheat acclimated at 20 and 5 degrees C were determined. The 5 degrees C-acclimated plants had lower relative growth rates, smaller biomass and leaf area, but larger specific leaf weight than 20 degrees C plants. Photosynthetic rates in 20 degrees C and 5 degrees C-acclimated leaves were similar; however, daytime export from 5 degrees C-acclimated leaves was 45% lower. Photosynthesis and export remained steady in 20 degrees C and 5 degrees C-acclimated leaves during the daytime. By comparison, photosynthesis in 5 degrees C-stressed leaves (20 degrees C-acclimated plants exposed to 5 degrees C 12 h before and during measurements) declined from 70 to 50% of the 20 degrees C-acclimated leaves during the daytime, while export remained constant at 35% of the 20 degrees C-acclimated and 60% of the 5 degrees C-acclimated leaves. At high light and CO2, photosynthesis and export increased in both 20 degrees C and 5 degrees C-acclimated leaves, but rates in 5 degrees C-stressed leaves remained unchanged. At all conditions daytime export was greater than nighttime export. Taken together, during cold acclimation photosynthesis was upregulated, whereas export was only partially increased. We suggest that this reflects a requirement of cold-acclimated plants to both sustain an increased leaf metabolic demand while concomitantly supporting translocation of photoassimilates to overwintering sinks.

Journal Article↗