Experience of Ring Rot Caused by Corynebacterium sepedonicum(Spieck. et Kotth.) Skapt. et Burkh. in Sweden. Particularly Detection of the Disease in its Latent Form)1

As it is difficult to detect ring rot in its latent form as well as in badly decayed tubers and in potato haulm, a diagnostic technique has been developed. With the help of a Turmix blender and a little water, a suspension is made of the suspected material. The suspension is inoculated into eggplants. Gram-staining of bacteria in sap from petioles of leaves showing symptoms is used to confirm the diagnosis. Some results obtained with this method applied on potatoes and potato haulm are described.     

Root colonisation by arbuscular mycorrhizal, fine endophytic and dark septate fungi across a pH gradient in acid beech forests

Colonisation by root endophytes can be beneficial to plants growing on acid, nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi can supply herbs with nutrients and may give protection against aluminium toxicity. Two other root colonising fungi, fine endophytes (FE) and dark septate fungi (DSE), are less well known but are potentially of benefit to their host plant. AM fungi are the most prevalent symbionts in herbs at neutral to acidic soil pH. At extremely low pH, fungal growth can be limited and AM colonisation is usually rare. Fine and dark septate endophytes, on the other hand, have been observed more often under these conditions. In order to relate endophyte colonisation to a gradient in soil pH, we investigated root colonisation by AM, FE and DSE in Maianthemum bifolium, Galium odoratum, Mercurialis perennis and Stellaria nemorum, from a range of acidic beech forests. With decreasing pH, colonisation by AM decreased, whereas the other two endophytes increased. AM and FE colonisation were inversely correlated in Maianthemum bifolium. We compared changes in root colonisation with those in chemical composition of soil and leaf samples and found a positive correlation between leaf magnesium concentrations and the presence of DSE in Galium odoratum. Aluminium concentration in Maianthemum bifolium tended to be lower when FE colonisation was high, suggesting a possible role for the fungi in plant protection against Al. We suggest that FE and DSE may replace AM fungi in herbaceous vegetation at extremely low pH, counteracting some of the negative effects of high soil acidity on plants.     

Single nucleotide polymorphisms found in the red alga Furcellaria lumbricalis (Gigartinales): new markers for population and conservation genetic analyses

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Foraging strategies of the external mycelium of the arbuscular mycorrhizal fungi Glomus intraradices and Scutellospora calospora

The responsiveness of the external mycelium of Glomus intraradices and Scutellospora calospora was tested in a multiple-choice experimental system in which mycelium encountered patches amended with nitrogen (N) or phosphorus (P), either alone or in combination with a host plant. We hypothesised that only AMF mycelium with sufficient supply of photosynthate from an actively growing host would respond to the amendments provided. Mycelium was allowed to grow either 11 or 21 weeks before we analysed hyphal proliferation in amended patches introduced in mesh bags that were not reached by roots but by foraging mycelium only. Hyphal length, the AMF signature fatty acid 16:1w5, and root colonisation in new host plant seedlings were used to measure AMF growth and resource allocation in the patches. Mycelium from both fungal strains was able to colonise new host roots and sand in all patches but S. calospora was overall more responsive to the amendments than G. intraradices. G. intraradices grew equally into all patches, including the unamended control, whereas S. calospora produced significantly more hyphal length in the patch containing a host plant than in the rest of the patches. Both strains showed lower hyphal growth at the second harvest and mycelium of G. intraradices lost almost entirely its capacity to develop new mycelium in all choices presented. Lipid measurements showed this fungus did not use storage lipids to exploit the patches. S. calospora mycelium had reduced growth and colonisation ability but still showed some growth in the patches at the second harvest. A reduction in the content of NLFA 16:1w5 from the first to the second harvest suggested that S. calospora mycelium likely used storage lipids to sustain proliferation in the patches. The results indicated that S. calospora was more active and used more resources for foraging than G. intraradices and that external mycelium foraging was maintained mainly with recently acquired plant carbon (C). This supported in general our hypothesis but showed as well that the two AMF strains had different strategies and resource allocation to forage. The overall low response of both AMF to the choices presented suggested that the responsiveness of mycelium searching freely in the substrate is lower than that observed in experimental systems in which the amendments have been placed in close contact with actively growing mycelium fronts in close vicinity with host roots.     

Millettia ferruginea from southern Ethiopia: Impacts on soil fertility and growth of maize

Growing agricultural crops under Millettia ferruginea (Hochst.) Baker, a tree that is endemic to Ethiopia, is an age-old practice in the country, but the beneficial effects of the tree on crops have not been scientifically quantified. To achieve this, four isolated and nearly identical Millettia trees growing on similar site conditions were selected and canopy coverage of each tree was divided into four radial transects. Four plots of 0.5 × 0.5 m were established on each radial transect at 0.5 to 1, 2.5 to 3, 4.5 to 5, and 6.5 to 7 m away from the tree bases. The control plot was established at 29.5 to 30 m. Composite soil samples from each of the four plots located at a comparable distance and at two soil depths, 0 to 10 and 20 to 30 cm, were collected and analyzed. The level of surface soil P, organic C, exchangeable base-forming cations and cation exchange capacity were all significantly higher (P < 0.000 to P < 0.015) under the trees than in the open field. Nutrient levels declined with depth and increasing distances from the tree trunk. Soil pH values did not show significant horizontal or vertical variations in all the soil samples analyzed. Maize plants grown on soils collected from underneath Millettia trees resulted in significantly better growth responses and higher dry matter yield as compared to the control (P < 0.001). Socioeconomic studies indicated that Millettia trees have good standing in the region both because of their desirable biological characteristics and because of their economic benefits.This revised version was published online in November 2005 with corrections to the Cover Date.     

Outbreak of Mycobacterium tuberculosis infection among captive Asian elephants in a Swedish zoo

Between 2001 and 2003, there was an outbreak of tuberculosis in a Swedish zoo which involved elephants, giraffes, rhinoceroses and buffaloes. Cultures of trunk lavages were used to detect infected elephants, tuberculin testing was used in the giraffes and buffaloes, and tracheal lavage and tuberculin testing were used in the rhinoceroses. The bacteria isolated were investigated by spoligotyping and restriction fragment length polymorphism. Five elephants and one giraffe were found to have been infected by four different strains of Mycobacterium tuberculosis.     

Ascorbic acid, carotenoids, and visual quality of baby spinach as affected by shade netting and postharvest storage

Baby spinach ( Spinacia oleracea L.) was grown under three types of shade netting (high transmittance, spectrum-altering, and low transmittance) to study the effect on the concentrations of vitamin C (ascorbic acid and dehydroascorbic acid), carotenoids, and chlorophyll and on the visual quality of the leaves. The spinach was sown in April and August and harvested at two growth stages. After harvest, leaves were stored in polypropylene bags at 2 and 10 degrees C. Shading significantly decreased the ascorbic acid concentration of April-sown spinach by 12-33%, but in the August-sown spinach, the response was inconsistent. Concentrations of total carotenoids and total chlorophylls were significantly higher under the nettings in many cases, especially under the spectrum-altering and low-transmittance nettings. Postharvest visual quality and postharvest persistence of the compounds analyzed were not greatly affected by shading. We conclude that these shade nettings are acceptable to use in baby spinach production when it comes to the studied aspects of internal and external quality of the produce.     

LH-β and FSH-β mRNA expression in nesting and post-breeding three-spined stickleback, Gasterosteus aculeatus, and effects of castration on expression of LH-β, FSH-β and spiggin mRNA

The mRNA expression of the LH- and FSH- subunits were measured in nesting and post-breeding male three-spined sticklebacks, Gasterosteus aculetaus, as well as in castrated and sham-operated nesting males. Furthermore, expression of an androgen induced kidney protein, spiggin, and 11-ketotestosterone (11KT) levels, were measured in the castrated and sham-operated males. Nesting males had significantly higher levels of both LH- and FSH- mRNA expression compared to post-breeding males. Furthermore, sham-operated males had significantly higher levels of LH- mRNA and spiggin mRNA expression than the castrated fish. Expression of FSH-, on the other hand, did not differ between castrated and sham-operated males. There were strong positive individual correlations between circulating levels of 11KT on the one hand and expressions of LH- and spiggin mRNA, whereas the correlation between 11KT levels and FSH- mRNA was weak. The negative effect of castration on -LH mRNA indicates that gonadal hormones stimulate this expression, whereas this was not the case for -FSH. The observed decline in -LH expression after the end of the breeding season may be the result of cessation of the gonadal stimulation of the pituitary. On the other hand, it is not likely that this can explain the decline in FSH- expression.     

Effects of harvesting date and storage on the amounts of polyacetylenes in carrots, Daucus carota

The amounts of three main polyacetylenes in carrots; falcarinol, falcarindiol, and falcarindiol-3-acetate, were determined by HPLC, during three seasons, in carrots harvested several times per season and at different locations in Sweden. The amounts of falcarindiol first decreased from a relatively high level and then increased later in the harvest season. The amounts of falcarindiol-3-acetate showed similar variations, whereas the amounts of falcarinol did not exhibit any significant variation during the harvest season. During storage the amount of polyacetylenes leveled off, increasing in samples initially low and decreasing in samples initially high in polyacetylenes. The amounts of all polyacetylenes varied significantly due to external factors and between stored and fresh samples. This variation opens up possibilities to achieve a chemical composition of polyacetylenes at harvest that minimizes the risk of bitter off-taste and maximizes the positive health effects reported in connection with polyacetylenes in carrots.     

Thin sow syndrome (TSS): the effect of amperozide

Sixty sows suffering from typical post-weaning TSS were divided into three groups: (1) 20 as negative controls (NC); (2) 20 as positive controls (PC) treated with vitamins, trace elements and antibiotics; and (3) 20 injected with amperozide (2 mg/kg body weight), a new neuroleptic compound with antistress and anxiolytic properties. Amperozide treated sows fully recovered (P less than 0.05) and 80% became pregnant, while figures for the PC and NC groups were only 15% and 10% respectively. Mortality was up to 50% in the NC, 40% in the PC and only 15% in the amperozide treated group (P less than 0.05). These field results warrant further studies in unravelling the aetiology and prevention of this condition.