Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) differ in their suitability as hosts for the endangered freshwater pearl mussel (Margaritifera margaritifera) in northern Fennoscandian rivers

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Climate drivers of diatom distribution in shallow subarctic lakes

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Lightsheet fluorescence lifetime imaging microscopy with wide‐field time‐correlated single photon counting

We report on wide‐field time‐correlated single photon counting (TCSPC)‐based fluorescence lifetime imaging microscopy (FLIM) with lightsheet illumination. A pulsed diode laser is used for excitation, and a crossed delay line anode image intensifier, effectively a single‐photon sensitive camera, is used to record the position and arrival time of the photons with picosecond time resolution, combining low illumination intensity of microwatts with wide‐field data collection. We pair this detector with the lightsheet illumination technique, and apply it to 3D FLIM imaging of dye gradients in human cancer cell spheroids, and C. elegans.     

The Effect of Various Mono–and Disaccharides on the Growth of Sphagnum nemoreum Thalli in Sterile Cultures

Sphagnum nemoreum Scop. thalli were grown under sterile conditions in order to study their ability to use certain carbohydrates for their growth, with special reference to the sugars occurring free in Sphagnum peat. It was found that Sphagnum nemoreum thallus could not grow at ail in vitro unless some organic carbon source war present. Growth was dependent on both the quality and the quantity of the sugar. Sucrose (1 per cent) proved to be the best carbon source and light intensity did not have any marked influence on growth under these conditions. Glucose and fructose were also growth promoting. Glucose is the main free sugar in the peat. Mannose (0.25 per cent) was almost as good a carbon source as sucrose in the same concentration. It is known that mannose accumulates in the Sphagnum peat during humification. and so does rhanmose, which was utilized to some extent. These two sugars are inhibitory to many mono–and dicotyledons. Ribose, galactose. arabinose and xylose were found to be toxic to Sphagnum.     

Effect of Nitrate, Ammonium and Some Amino Acids on Growth and Nitrate Reductase Activity in Suspension Cultures of Atropa belladonna

Growth and nitrate reductase activity (NRA) of Atropa belladonnacells were studied in medium supplemented with NaNO₃, NH₄NO₃,and amino acid precursors to tropane alkaloids. Growth and NRAwere stimulated by NH₄⁺ and by proline, by proline plus ornithine,but not by glutamate, in NO₃^–-containing medium. Testedamino acids inhibited neither utilization of inorganic nitrogennor growth. (Received September 30, 1988; Accepted August 28, 1989)     

IL-22 promotes the formation of a MUC17 glycocalyx barrier in the postnatal small intestine during weaning

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Larval chaoborid mandibles in surface sediments of small shallow lakes in Finland: implications for palaeolimnology

The aim of this study was to assess the value of phantom midge Chaoborus (Diptera: Chaoboridae) larvae as a palaeoenvironmental proxy in northern Europe. The presence of Chaoborus was examined in 80 small shallow lakes across Finland (60–70°N), based on their subfossil mandibles preserved in lake sediments. Chaoborus flavicans was present in 33 lakes, but was the most abundant midge taxon in only one of the lakes. Chaoborus crystallinus/obscurripes mandibles were present in two lakes. Statistical analyses showed that the distribution of Chaoborus was significantly correlated with lake depth and mean July air temperature. Chaoborus was absent in the northern study lakes, whereas the results indicated that C. flavicans was frequently found in small shallow lakes in southern Finland. Chaoborus flavicans was particularly abundant in fish-free, macrophyte-rich, dystrophic lakes, but absent in oligotrophic clear-water lakes having fish. The results of this study indicate that the subfossil mandibles of Chaoborus can provide valuable information in multiproxy palaeolimnological studies, especially when investigating past changes in water level and temperature in small shallow lakes in northern Europe. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water     

Chromosome counts in the Carex flava complex (Cyperaceae) in Finland

Chromosome numbers from 17 Finnish populations of six taxa in the Carex flava complex were examined. Special attention was given to taxa claimed to be endemic to Fennoscandia. The meiotic counts for C. flava n = 30, C. viridula var. viridula n = 35 and var. pulchella n = 35 are in accordance with previous reports. The counts for C. jemtlandica n = 34, C. bergrothii n = 35, and C. kotilaini n = 34 are new. The hybrid C. flava × kotilaini reveals severely disturbed meiosis with many uni- and multivalents. The results are briefly discussed in relation to morphological data. Carex jemtlandica should evidently be included in C. lepidocarpa. Carex bergrothii and C. kotilaini belong to the polymorphic C. viridula , but the latter probably consitute a specific cytotype.     

Indoor-related microbe damage induces complement system activation in building users

In this comparative study, serum complement system antimicrobial activity was measured from 159 serum samples, taken from individuals from microbe-damaged (70 samples) and from reference buildings (89 samples). Antimicrobial activity was assessed using a probe-based bacterial Escherichia coli-lux bioluminescence system and comparison was made at a group level between the experimental and reference group. The complement activity was higher in users of microbe-damaged buildings compared with the reference group and the significant (P < 0.001) increase in activity was found in the classical reaction pathway. This study strengthens our notion that exposure to indoor-related microbe damage increases the risk for systemic subclinical inflammation and creates a health risk for building users.     

The occurrence of Gonyostomum semen (Ehr.) Diesing in Finnish lakes

Since the early nineteen-eighties swimmers have complained of the nuisance effect of Gonyostomum semen in Finnish lakes. This alga causes an unpleasant slimy coating on the skin after swimming. Although it was first identified in Finland in 1894, the first complaints concerning G. semen were reported to the Finnish water authorities in 1978. During the period 1978–1989 a total of 110 water samples were qualitatively microscoped for G. semen. According to the results the alga seems to have spread from the south-eastern part of Finland throughout the southern part of the country and northwards almost to the Arctic circle.139 quantitative samples from monitored lakes were also analysed. The alga seems to prefer dystrophic and eutrophic conditions.