Parnassia palustris: a genetically diverse species in Scandinavia

Patterns of variation at nine enzyme loci were examined in 528 plants representing diploid and tetraploid populations of Parnassia palustris s. l. in Europe to assess genetic variation patterns and migration history. Half of the plants showed a unique multilocus phenotype and 75% of all phenotypes occurred only in Scandinavia. Diploid populations showed similar levels of genetic diversity as other widespread outbreeding species with animal-mediated pollination and F -statistics indicated excessive heterozygosity and low rates of gene flow among them. In spite of dramatic population histories caused by the ice ages, diploid populations have maintained the same genetic diversity in Scandinavia as in central and southern Europe. Northern populations have apparently been established through the gradual advance of genetically variable populations and patterns of variation at individual loci indicate different migration routes, from the south-south-west and the east-north-east, respectively. The data strongly support a repeated autoploid origin of the tetraploid cytotype which has been much more successful than the diploid progenitors in colonizing new land since the last ice age. High genetic diversity in Scandinavia has apparently been obtained by a combination of immigration of plants from different source areas and recurrent formation of autotetraploids from diploid progenitors.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 347−372.     

Production of a Cellulase Complex in Culture Filtrates of Aspergillus tamarii Associated with Mouldy Cocoa Beans in Nigeria

Aspergillus tamarii Kita grown in media that contained single soluble or insoluble cellulosic sources of carbon, released a complex of cellulolytic enzymes into the medium. The complex was separated into thirteen components by gel filtration followed by ion exchange chromatography. Eight of the components had a high molecular weight and five had a low molecular weight. One of the high molecular weight components, designated Ab, had the character of C₁ cellulase enzyme. In a few cases there was synergism between the components, since in combination they liberated more glucose than when alone.     

Types of Rot, Rate of Rotting, and Analysis of Pectic Substances in Apples Rotted by Fungi

The rate at which the fungi grew through apples was determinedin various ways and used to estimate their rate of linear advance.Five fungi were studied;they were Sclerotinia fructigena (firm-browncoloured rot, rapid growth through apples), Botrytis cinerea(soft, light-brown coloured rot, rapid growth through apples),Psyrenochaeta furfuracea (firm to soft rot, variable in colourbut generaly dark, slow growth through apples), Penicilliumexpansion A (soft, white rot, slow growth through apples) andPenicillium expansum B (soft, white rot, medium rate of growththrough apples). S. fructigena which had the highest rate oflinear advance which was about three times that of P. furfuraceawhich had the lowest. Methods for extracting different types of pectic substancesfrom sound and rotted tissues are described, and details aregiven of a rapid and reasonably accurate colorimetric methodof determining the anhydrogalacturonic acid content of theseextracts. The firm-rot fungi reduced the water-insoluble pecticsubstances by 10–20 per cent., but the soft-rot fungicaused much larger changes, up to 70 per cent. being degraded,The firm-rot and soft-rot fungi had different effects on thepectic substances insoluble in dilute acid but soluble in dilutealkali. The soft-rot fungi had little effect on these substances,or reduced their concentration, whereas the firm-rot fungi causedsubstantial increases compared with sound tissue. These resultsare considered in terms of pectic enzyme activity. Analysisof extracts by paper chromatography showed that galacturonicacid, absent from sound tissue, was present in each type ofrotted tissue. Di- and tri-galacturonic acids were present inrots caused by P. expansum, and these rots probably also containedproducts from the break-down of other polysaccharides.     

Charge Dependent Distribution of Endogenous Proteins within Vitellogenic Ovarian Follicles of Actias luna

In vitellogenic ovarian follicles of Actis luna, internal Ca(2+) activity currents create an electrical gradient which influences the distribution of charged macromolecules between nurse cells and oocyte. We show that, between oocyte and nurse cells, there is an ionic gradient of 1-12 mV with the nurse cells being more electronegative than the oocyte by an average 3.5+/-0.2 mV(s.e.)(p<0.001). As previously reported for another saturniid, Hyalophora cecropia, the transbridge ionic gradient of luna: (1) is focused across the intercellular bridges, (2) is abolished by 200 &mgr;M vanadate and (3) includes a [Ca(2+)](i) gradient. Endogenous soluble proteins collected from control and from vanadate treated populations of nurse cells and oocytes were separated by two-dimensional (2-D) gel electrophoresis and visualized with sliver stain. Densitometric analysis showed that 14 out of the 19 acidic proteins and six of the eight basic proteins studied, changed their oocyte-to-nurse cell distribution in consort with change in the transbridge ionic gradient. This suggests that a transbridge ionic gradient may be, at least within the saturniidae, a method for maintaining different molecular concentrations in nurse cells compared to oocytes. Copyright 1997 Elsevier Science Ltd. All rights reserved     

The infection of oranges by Trichoderma viride and mixed infection by Trichoderma viride and Penicillium digitatum

Trichoderma viride spores applied in water to apparently uninjured skin of oranges do not cause lesions. Adding orange juice, rind extract, citric acid or orange essential oil did not influence infection. Oranges became infected only when the stem-end cuts or wounds deeper than 6 mm into oil vesicles were inoculated. Sound oranges in contact with decayed oranges did not become infected. Diphenyl-impregnated wrappers reduced infection. A mixed inoculum of T. viride and Penicillium digitatum caused as fast rotting as P. digitatum, which caused faster rotting than T. viride alone. Lesions infected with P. digitatum could become infected by T. viride but those caused by T. viride did not become infected by P. digitatum. T. viride was antagonistic to P. digitatum in vivo and in vitro, possibly because it produces a heat-labile diffusible substance toxic to P. digitatum.     

Unravelling the migration and moult strategies of a long-distance migrant using stable isotopes: Red Knot Calidris canutus movements in the Americas

For long‐distance migrants, such as many of the shorebirds, understanding the demographic implications of behavioural strategies adopted by individuals is key to understanding how environmental change will affect populations. Stable isotopes have been used in the terrestrial environment to infer migratory strategies of birds but rarely in marine or estuarine systems. Here, we show that the stable isotope ratios of carbon and nitrogen in flight feathers can be used to identify at least three discrete wintering areas of the Red Knot Calidris canutus on the eastern seaboard of the Americas, ranging from southeastern USA to Patagonia and Tierra del Fuego. In spring, birds migrate northwards via Delaware Bay, in the northeastern USA, the last stopping point before arrival in Arctic breeding areas, where they fatten up on eggs of spawning Horseshoe Crabs Limulus polyphemus. The isotope ratios of feather samples taken from birds caught in the Bay during May 2003 were compared with feathers obtained from known wintering areas in Florida (USA), Bahia Lomas (Chile) and Rio Grande (Argentina). In May 2003, 30% of birds passing through the Bay had Florida‐type ‘signatures’, 58% were Bahia Lomas‐type, 6% were Rio Grande‐type and 7% were unclassified. Some of the southern wintering birds had started moulting flight feathers in northern areas, suspended this, and then finished their moult in the wintering areas, whereas others flew straight to the wintering areas before commencing moult. This study shows that stable isotopes can be used to infer migratory strategies of coastal‐feeding shorebirds and provides the basis for identifying the moult strategy and wintering areas of birds passing through Delaware Bay. Coupled with banding and marking birds as individuals, stable isotopes provide a powerful tool for estimating population‐specific demographic parameters and, in this case, further our understanding of the migration systems of the declining Nearctic populations of Red Knot.