Effects of Ischaemic Conditions on Uptake of Glutamate, Aspartate, and Noradrenaline by Cell Lines Derived from the Human Nervous System

Abstract: The effect of hypoglycaemic, hypoxic, and ischaemic conditions on high-affinity neurotransmitter transport was studied in the human astrocytoma clone D384 and the human neuroblastoma clone SH-SY5Y. Both cell lines expressed a sodium-dependent glutamate/aspartate transporter. K _m values for d -[³H]aspartate uptake were 6.1 ± 0.9 µ M for D384 cells and 5.3 ± 0.3 µ M for SH-SY5Y cells (mean ± SEM of three experiments). In addition, SH-SY5Y, but not D384, expressed a sodium-dependent noradrenaline transporter with K _m = 0.6 ± 0.1 µ M (mean ± SEM of three experiments). Up to 3 h of hypoglycaemic conditions had no effect on neurotransmitter uptake or on ATP levels of each cell line. In sharp contrast, during hypoxic conditions, the uptake of d -[³H]aspartate and [³H]noradrenaline declined by 43–56% within 5 min. These reduced rates of neurotransmitter uptake were maintained over 30 min of hypoxic conditions. Five minutes of ischaemic conditions caused similar reductions in neurotransmitter uptake rates. A correlation between reductions in rates of neurotransmitter uptake and in ATP levels was observed for each cell line. Results are discussed in relation to other brain preparations, which are used as models of the nervous system to study the effects of ischaemic conditions on neurotransmitter and energy metabolism.     

Laboratory testing of a mycopesticide on non‐target organisms: The effects of an oil formulation of Metarhizium flavoviride applied to Apis mellifera

A technique was developed to allow ultra‐low volume (ULV) application of an oil formulation of the deuteromycete, Metarhizium flavoviride Gams & Rozsypal, to Apis mellifera (Linnaeus). In the first experiment, application of a dose equivalent to twice the expected field application rate killed 30% of the bees and a twenty‐fold dose killed 87%. In a second experiment, a realistic field dose formulated in oil killed 11% of the bees and a similar dose formulated in water killed 8%. The dose applied effectively killed the target host, the desert locust Schistocerca gregaria (Forskål). Application of a chemical pesticide comprising an organophosphate and two pyrethroids at a dose that was just sub‐lethal to locusts, killed all treated bees. Very few untreated bees died. The results demonstrated the feasibility of safety testing a mycopesticide with bees as a non‐target organism. In addition, it was demonstrated that the mycopesticide currently under development for the control of locusts and grasshoppers was quantifiably less hazardous to bees than the chemical pesticide.     

GROWTH OF THE EMBRYO OF GINKGO BILOBA UNDER EXPERIMENTAL CONDITIONS. III. GROWTH RATES OF ROOT AND SHOOT UPON MEDIA ABSORBED THROUGH THE COTYLEDONS

Ball , Ernest . (North Carolina State Coll., Raleigh.) Growth of the embryo of Ginkgo biloba under experimental conditions. III. Growth rates of root and shoot upon media absorbed through the cotyledons. Amer. Jour. Bot. 46(2) : 130-139. Illus. 1959.—Mature embryos of Ginkgo biloba were grown by inserting the cotyledons into agar medium containing one of the naturally-occurring sugars of the seed. These sugars were utilized at 1, 2, 4, 8 or 16% (w/v). Root growth was best on the sugar-mineral-water media and occurred at its maximum in media containing 4% sugar (ca. 0.25 M). The sugars may be listed as follows in order of decreasing effectiveness in root growth: glucose, sucrose, levulose, raffinose, galactose. Since very different growth rates of roots occurred on media of the same osmotic values when the latter were determined by the various sugars, it is suggested that the root utilized the entire sugar molecule as a unit whether it was mono-, di-, or trisaccharide. Such media were not effective in supporting shoot growth. Outstanding growth of shoots was obtained when either glutamine or coconut milk was placed in the culture medium. It is concluded that root growth can occur at a substantial rate by utilizing sugar and manufacturing organic nitrogen from nitrates. Shoot growth, in contrast, appears to require sources of organic nitrogen such as may be furnished by glutamine or coconut milk. These phenomena are thought to constitute fundamental differences between the metabolism of root and shoot of this embryo. Mannitol caused severe inhibition of growth of both root and shoot. It is probably toxic to this embryo. Indoleacetic acid caused severe inhibitions of growth of both root and shoot at all except the lowest concentrations utilized.