A portable EAG system for the measurement of pheromone concentrations in the field

A robust and portable apparatus for the measurement of pheromoneconcentrations under field conditions has been developed. Ituses the insect antenna (Lobesia botrana Hb.) itself as a sensitiveand specific pheromone detector. Shock-proof contact with theelectrodes is maintained by fixing the antenna in a specially-shapedplexiglass holder mounted within a glass tube. This allows measurementsto be made while moving the apparatus. Continuous airflow throughthe tube is generated by a suction pump and the incoming aircan be purified by passage through a charcoal filter. This allowsto readjust the offset and to calibrate the instrument by theapplication of pheromone pulses of known concentrations. Removalof the filter allows the direct access of ambient air over theantenna which responds by generating an electro-antennogram(EAG) as a measure of the pheromone concentration. Using the calibration curve, relative pheromone concentrationsin ambient air in a vineyard can be determined. Sample measurementsfrom areas treated with artificial pheromone for pest controlare presented.     

Utilization of alpha-ketoglutarate as a precursor for transmitter glutamate in cultured cerebellar granule cells

Alpha-ketoglutarate together with an amino group donor (alanine) was shown to be able to serve as a precursor for the glutamate pool which is released by potassium-induced depolarization (i.e., transmitter glutamate) in cerebellar granule cells. However, these compounds could not be utilized as precursors for intracellular glutamate or for release of transmitter aspartate. The formation of transmitter glutamate was inhibited by the transamination inhibitor aminooxyacetic acid but not by phenylsuccinate, an inhibitor of the dicarboxylate carrier in the mitochondrial membrane. Both of these inhibitors have previously been found to inhibit synthesis of transmitter glutamate from glutamine. The results support the hypothesis that alpha-ketoglutarate and alanine undergo transamination in the cytosol to form pyruvate and glutamate, and that this glutamate pool is available for transmitter release of glutamate but does not constitute the major intracellular pool of glutamate.     

Characterization of microcarrier cultures of neurons and astrocytes from cerebral cortex and cerebellum

In the present investigation a method is described for culturing cerebellar granule cells (glutamatergic neurons), cerebral cortical neurons (GABAergic neurons) and cortical astrocytes on Cytodex 3 microcarriers. It was possible to obtain a high yield of attached neurons and astrocytes on the microcarriers and the cell specific characteristics such as the ability to release neurotransmitter (neurons) and a high activity of glutamine synthetase (astrocytes) were preserved. This system, allowing mixtures of neurons and astrocytes at any given ratio to be produced, may constitute an attractive model system by which the interaction between neurons and astrocytes with regard to exchange of neurotransmitter precursors as well as other compounds may be studied.     

Phytotoxins from Alternaria helianthi: radicinin,and the structures of deoxyradicinol and radianthin

A novel compound, radianthin, with phytotoxic activity was isolated from liquid cultures of Alternaria helianthi and identified as a pyrone related to radicinin. A second metabolite was identified as radicinin itself while deoxyradicinol is described for the first time as a natural product.     

The genus Iphiona (Compositae-Inuleae)

The genus Iphiona Cass. emend. A. Anderb. (Compositae-Inuleae-Inulinae) is revised and considerably amended. The former genera Grantia Boiss. (= Perralde-riopsis Rauschert) and Hirschia Baker are included as well as the major part of Iphiona Cass. s.str. and the species Inula grantioides Boiss., and Pulicaria phillipsiae S. Moore. Five new combinations are made: I. anthemidifolia (Baker) A. Anderb., I. arachnoidea (Boiss.) A. Anderb., I. grantioides (Boiss.) A. Anderb., I. phillipsiae (S. Moore) A. Anderb., and I. senecionoides (Baker) A. Anderb. The new species I. teretifolia A. Anderb. is described. A discussion of the phylogeny of the group and a cladogram, involving reticulation, of the Iphiona species are presented. The 11 species are distributed in Egypt, Israel, Jordan, Sudan, Ethiopia, Somalia, Saudi Arabia, Peoples Democratic Republic Yemen, Oman, Iran and Pakistan.     

The Cladocera and Copepoda of the Alta water-course, Northern Norway

Cladocera and Copepoda fauna, from ten lakes in the Alta water-course,northern Norway, have been collected and investigated. A totalof 42 species (34 Cladocera and 8 Copepoda) were recorded. Thenumber of Cladoceran species is high when compared with thatregistered for other areas of similar latitude, and Cladoceranspecies abundance is also greater than that reported for otherregions of northern and central Scandinavia. In addition, themean number of planktonic species present at any given timein the lakes (4.9 Cladocera and 3.4 Copepoda) was comparativelyhigh. Eight species have never been recorded as existing farthernorth than the Alta water-course, Three other species have beenrecorded at higher latitudes in North America, but not in Eurasia.Several species, of which there are only a few published records,arc rare in northern Scandinavia, and nine species were notconsidered by Illies (1978), as existing in the region of thepresent study.     

The distribution and interconversion of ammonium and nitrate in the Skallingen salt marsh (Denmark) and their exchange with the adjacent coastal water

The potential nitrogen sources for the primary production in the intertidal area are nitrogen compounds obtained from mineralization in the sediment and the water column, nitrogen fixation, outflow from rivers and groundwater seeping from the mainland. The available inorganic nitrogen in the adjacent coastal waters decreases from 50–80 μmol NO₃ ^-/l and 6–15 μmol NH₄ ⁺/l in early spring to ca one tenth during the growing season. In the sediment of the tidal flats available ammonia and nitrate vary between 50 and 100 μmol/1 pw. In the salt marsh available ammonia increases from 200–300 nmol NH₄ ⁺/g fwt to approximately double the amount, and the available nitrate varies from 100–300 nmol NO₃ ^-/g fwt (250–750 μmol NO₃ ^-/l pw) to ca one third during the growing season. The exchange of NH₄ ⁺, NO₂ ^- and NO₃ ^- across the sediment water interface has been estimated during tidal cycles under light and dark conditions on the tidal flats. The flux of nitrogen was dependent on the flora and fauna as well as the time of the year. The tidal activity, frequency and length of inundation are considered the driving force in a two-way process between salt marshes and adjacent coastal waters. The role of marsh sediment, tidal water and sediments of the tidal flats as sites of accumulation, consumption and remineralization of organic matter is emphasized. The possible exchange of ammonia and nitrate between the salt marsh and the different compartments of the tidal water is discussed.     

On the ecophysiology of Halimione portulacoides

Growth rate and salt accumulation were investigated in experiments on Halimione portulacoides with seven sodium chloride treatments, in water culture. The growth of Halimione was found to be stimulated by moderate, 85–170 mM NaCl, levels of salinity, but increasingly depressed by salinities from 410–690 mM NaCl, which is comparable to salinities in salt marshes during the growing season. Using the same technique, growth rate, chloride and nitrogen uptake experiments at four different sodium chloride and nitrate treatment levels were conducted, in order to study the effect of nitrogen and salt. At 8 mM NaCl in the growth medium growth was depressed at 16.2 mM nitrate treatment levels. At 137 mM, 410 mM and 684 mM of NaCl growth was stimulated by increasing levels of nitrogen. The results of these experiments are discussed in relation to the nitrogen and salt conditions prevailing in Halimione portulacoides salt-marsh communities.     

Elevation of the Extracellular Concentrations of Glutamate and Aspartate in Rat Hippocampus During Transient Cerebral Ischemia Monitored by Intracerebral Microdialysis

Rats were implanted with 0.3-mm-diameter dialysis tubing through the hippocampus and subsequently perfused with Ringer's solution at a flow rate of 2 microliter/min. Samples of the perfusate representing the extracellular fluid were collected over 5-min periods and subsequently analyzed for contents of the amino acids glutamate, aspartate, glutamine, taurine, alanine, and serine. Samples were collected before, during, and after a 10-min period of transient complete cerebral ischemia. The extracellular contents of glutamate and aspartate were increased, respectively, eight- and threefold during the ischemic period; the taurine concentration also was increased 2.6-fold. During the same period the extracellular content of glutamine was significantly decreased (to 68% of the control value), whereas the concentrations of alanine and serine did not change significantly during the ischemic period. The concentrations of gamma-aminobutyric acid (GABA) were too low to be measured reliably. It is suggested that the large increase in the content of extracellular glutamate and aspartate in the hippocampus induced by the ischemia may be one of the causal factors in the damage to certain neurons observed after ischemia.