Lipid Metabolism in Fucus serratus as Modified by Environmental Factors

The effect of changes in the environment on lipid metabolismhas been studied in the brown alga, Fucus serratus L. Lightstimulated the incorporation of radioactivity from /{^I4C/}acetateinto oleic and, especially, into linoleic acid. The same effectwas caused by lowering the incubation temperature from 15 °Cto 4 °C. Incubations in the presence of Cd ^{+ +}, Pb ^{+ +} orZn^{+ +} had no effect on the total uptake of /{¹⁴C/}acetate intothe frond tip samples, but lowered the labelling of total lipidsrelative to aqueous-soluble components. However, pre-exposureof the algae to heavy metal cations caused changes in the uptakeof radioactivity but had less effect on the relative labellingof lipids than incubations in the presence of heavy metal cations.Algae collected from sites where the dissolved levels of heavymetals were elevated, showed a decrease in the relative labellingof lipids from /{¹⁴C/}acetate. Concentrations of Cd^{+ +}, Pb⁺⁺ or Zn^{+ +} at 10 x levels found at the collection site had littleeffect on the pattern of fatty acids made by Fucus serratus. Key words: Lipid metabolism, Fucus serratus L., Environmental changes     

A monoclonal antibody to ochratoxin A

The production of patulin by P. expansum Link ex Gray growing in apple juice was determined over a range of pH. Patulin was found to be produced in large quantities over a narrow range of pH from 3-2 to 3–8. The biomass produced increased with increasing pH. The changes in pH due to growth of the organism were found to be small.     

A late Wenlock flora from Co. Tipperary, Ireland

An assemblage of macroplants preserved as highly coalified compressions which lack anatomy is described from a Wenlock locality in County Tipperary, Ireland. Most of the fertile specimens are assigned to Cooksonia Lang. The taxonomic status of this genus is discussed. Some poorly preserved palynomorphs, including miospores, acritarchs, chitinozoans and a variety of tubes, have been isolated from associated sediments, but the age of the flora is based on graptolites. Sedimentological and palaeontological studies of the region are summarized. They provide little direct evidence for the habitats of the plants which are considered to have been terrestrial. The relevance of this flora to the current debate on the colonization of the land is evaluated and it is concluded that these plants provide the earliest record of erect fertile land plants of possible pteridophyte affinity.     

Carbon isotope ratios of respired CO2 from castor bean, corn, peanut, pea, radish, squash, sunflower and wheat seedlings

During the first month after germination peanut and sunflowerseedlings exhibit a significant shift in the ¹³C/¹²C ratiosof respired CO₂ indicating thatcarbohydrate gives way to lipidas the respiratory substrate. Other species (castor bean, corn,pea,radish, squash and wheat) show no change in the ¹³C/¹²C ratio (Received March 9, 1971; )     

Transport of abscisic acid

The transport of abscisic acid in cotyledonary petiole sectionsof cotton seedlings was investigated using (2-¹⁴C)-ABA in adonor-receiver system. Using the intercept technique, a transportvelocity of 22.4 mm/hr was determined. This velocity was foundto be independent of the length of the petiole or of the concentrationof ABA applied. In a 24-hr period 70% of the applied ABA movedthrough the tissue sections. No polarity was found in any ofthe studies. The capacity of the transport system decreased with increasingage of the tissue and with increasing time of pre-exposure toABA. When metabolism of the tissue was restricted by cold temperature,low-O₂ tension or DNP treatment, transport was inhibited 80to 98%.The distribution of ABA in the petiole during transportwas also investigated. The results are discussed in relationto the well-studied transport of IAA and in relation to thephysiologicalrole of ABA. ¹ Present address: Stanford Research Institute-Irvine, 19722Jamboree Blvd., Irvine, Calif. 92664, U.S.A. (Received November 30, 1970; )     

Feline Ventricular Ganglion Cells

IN mammals, with the exception of artiodactyls and cetaceans, it is generally accepted that intrinsic cardiac ganglion cells are confined distally by the atrioventricular groove¹. This is interpreted as indicating that vagal influence is limited to the atrial and specialized tissues and this concept is supported by much physiological evidence. It has been suggested that, in dogs, the vagi exert a direct negative inotropic effect on the ventricles², although Furnival et al.³ found that this effect was relatively insignificant. Morphologists have, however, reported ventricular ganglion cells in primates^4–6. We offer here morphological evidence for the existence of ventricular ganglion cells in the cat.     

Light Intensity and Substrate Availability in Relation to Tracheid Development in Picea sitchensis

Assimilation and growth of Picea sitchensis seedlings maintainedat three light intensities were examined in relation to previously-reporteddata on tracheid development in this species. Increases in photosynthetic efficiency with decreased lightlevel failed to compensate completely for reduced total amountsof incident radiation as judged from assimilate distributionpattern and growth rate. Incorporation of assimilate into reservesand new growth declined with decreased light level, while theextent of turnover materials generally increased. Most treatment differences in relative dry weight distributionappeared to result from a combination of differences in growthrate and changes in growth pattern. The proportion of dry weightin branches and roots increased with increased light intensitywhile that in stems and the hypocotyl decreased At the two highest light levels tested, both absolute stem growthrate and total wall accumulation appeared to be independentof substrate availability. This situation contrasts with thatobserved in older material and it is suggested that the initialindependence reflects the temporary existence of a high ratioof functional foliage to stem and cambial material during thefirst year of growth. Since tracheid diameter showed a consistent, positive relationshipwith assimilate status, it is suggested that substrate levelcan exert an important modifying influence on cell expansion.     

The insect faunas of pear and apple orchards and the effect of windbreaks on their distribution

Two coir netting windbreaks, each 7 m tall and 46 m long, were erected in a pear and an apple orchard, to try to increase the number of insect pollinators present at blossom time. The flying insects were sampled with suction traps and insects visiting trees were sampled by examining marked clusters of blossom. The mean aerial density was calculated for each of the forty-two taxa, mainly families, identified from the aerial population. There were about 50% more insects flying in the pear than in the apple orchard. The distribution of flying insects was greatly affected by the windbreaks, and the sheltered zone contained three times as many of most species, and more than three times as many Chironomidae, Psychodidae and Bibionidae as elsewhere. Small flies were the most abundant insects in the air, in both orchards. In the pear orchard large insects comprised only about 7 % of the total aerial population, of which honeybees constituted 0–7% and wild bees 0–3%. By contrast, large insects accounted for a greater proportion of the population on blossom. The reasons for this are discussed. On apple blossom Syrphidae and honeybees were the insects most often seen, and on pear blossom Bibionidae and Mycetophilidae.     

An example of ant-assisted plant invasion

At a site near Armidale, New South Wales, Australia, unplanted individuals of two plant species not native to the region (Grevillea rosmarinifolia and Viola odorata) grow predominantly within 5 m of a nest of the ant Iridomyrmex purpureus, which is situated 40–50 m from planted, parent individuals. Seeds of both species, but not of two other plant species (Dianthus barbatus. Nigella damascena) not growing near the nest, were shown to be attractive to ants. Marked seeds of V. odorata were observed being carried into the I. purpureus nest, and some (with most of the elaiosome removed) were later discarded by ants from the nest. Plant invasion apparently is being facilitated by myrmecochory.