A thermostable lipase produced by a newly isolated <Emphasis Type="Italic">Geotrichum</Emphasis>-like strain,R59

Growth and production of lipase by a new Geotrichum-like strain, R59, were studied. Production of extracellular lipase was substantially enhanced when the initial pH of the culture medium, types of carbon and nitrogen sources, substances probably stimulating the lipase biosynthesis, the temperature, and time of growth were optimized. Sucrose and triolein were the most effective carbon sources for lipase production. Maximum lipase activity (146 U/ml^–1) was obtained with urea as the nitrogen source. Growth at 30°C, an initial pH of 6.0 and incubation time of 48 h were found as optimum conditions for cell growth and production of lipase by Geotrichum-like strain R59. The enzyme was thermostable and exhibited very high activity after 1 h incubation at 60°C.     

Prevalence of agglutinating antibodies against<Emphasis Type="Italic"> Listeria monocytogenes</Emphasis> in chicks of the white stork (<Emphasis Type="Italic">Ciconia ciconia</Emphasis> Linnaeus, 1758) in Poland

In 2002 and 2003, blood samples from white stork (Ciconia ciconia) chicks were examined for the presence of antibodies against Listeria monocytogenes. Listeria antibodies were detected in 121 (59%) of 205 chick samples. The probability of Listeria antibodies being present increased with chick age; chicks detected with Listeria antibodies were in better condition than those without the bacterium.     

<Emphasis Type="Italic">Erysiphe catalpae</Emphasis> and <Emphasis Type="Italic">Erysiphe elevata</Emphasis> in Europe

The recent epidemic spread of the North American powdery mildew Erysiphe elevata in Europe is described and discussed. Since 2002, this plant pathogenic fungus has been collected on Catalpa bignonioides, C. erubescens and C. speciosa in the Czech Republic, Germany, Hungary, Slovakia and Switzerland. The diagnostically important anamorph of E. elevata, so far unknown, is described and illustrated in detail. Type material of Erysiphe catalpae and two specimens of E. catalpae recently collected in Poland have been examined and compared with E. elevata. The anamorph as well as the teleomorph of E. catalpae proved to be easily distinguishable from E. elevata. The supposition that E. catalpae, introduced in Armenia, was based on immature ascomata of E. elevata proved to be wrong. The origin and distribution of E. catalpae are discussed, and a key to powdery mildew fungi on Catalpa spp. in Europe is provided.     

Molecular characterization and functional expression of flavonol 6-hydroxylase

Background  

Flavonoids, one of the major groups of secondary metabolites, play important roles in the physiology, ecology and defence of plants. Their wide range of activities is the result of their structural diversity that encompasses a variety of functional group substitutions including hydroxylations. The aromatic hydroxylation at position 6 of flavonols is of particular interest, since it is catalyzed by a 2-oxoglutarate-dependent dioxygenase (ODD), rather than a cytochrome P450-dependent monooxygenase. ODDs catalyze a variety of enzymatic reactions implicated in secondary metabolite biosynthesis.     

High level of male-biased Scandinavian admixture in Greenlandic Inuit shown by Y-chromosomal analysis

We have used binary markers and microsatellites on the Y chromosome to analyse diversity in a sample of Greenlandic Inuit males. This sample contains Y chromosomes typical of those found in European populations. Because the Y chromosome has a unique and robust phylogeny of a time depth that precedes the split between European and Native American populations, it is possible to assign chromosomes in an admixed population to either continental source. On this basis, 58+/-6% of these Y chromosomes have been assigned to a European origin. The high proportion of European Y chromosomes contrasts with a complete absence of European mitochondrial DNA and indicates strongly male-biased European admixture into Inuit. Comparison of the European component of Inuit Y chromosomes with European population data suggests that they have their origins in Scandinavia. There are two potential source populations: Norse settlers from Iceland, who may have been assimilated 500 years ago, and the Danish-Norwegian colonists of the eighteenth century. Insufficient differentiation between modern Icelandic and Danish Y chromosomes means that a choice between these cannot be made on the basis of diversity analysis. However, the extreme sex bias in the admixture makes the later event more likely as the source.     

The location of the<Emphasis Type="Italic">Mus musculus/M. domesticus</Emphasis> hybrid zone in the Balkans: clues from morphology

Three morphological characters were used to depict the position of the hybrid zone between two species of house mice,M. musculus Linnaeus, 1758 andM. domesticus Schwarz et Schwarz, 1943, across a vast area covering countries of the former Yugoslavia, Albania, Bulgaria and Greece. Quantitative approach based on a morphological index (MI), resembling the hybrid index widely used in allozyme-based genetic studies, was used. The zone crosses Slovenia south of the Sava River, and then follows the Dinaric Mts to Montenegro and northern Albania. Contrary to many previously published results, the zone was found to run parallel with northern borders of Albania and the former Yugoslavian Macedonia, about 150 km north of the Greek border, thus giving its course rather “shallow” appearance at this part of the Balkan Peninsula.     

Changes in amount of bacteria during gut passage of leaf litter and during coprophagy in three species of<Emphasis Type="Italic">Bibionidae (Diptera)</Emphasis> larvae

To elucidate the interaction between bacteria and saprophagous Diptera larvae, the amounts of bacteria in leaf litter, individual gut compartments, and feces of three species of Bibionidae (Bibio pomonae, Bibio marci, and Penthetria holosericea), feeding either directly on leaf litter or on fecal pellets produced from leaf litter by larvae of the same species, were assessed by determining total direct counts and viable counts on solid media at different pH. In P. holosericea, the effect of various cultivation temperatures on direct counts of bacteria in individual compartments was also demonstrated. In all species, the amount of bacteria in the anterior mesenteron was lower than in the consumed food, regardless of whether the larvae were feeding on leaf litter or feces, and increased again in the posterior part of the gut. The amount of bacteria in these compartments was generally higher in larvae feeding on feces than in those feeding on leaf litter, whereas the amount of bacteria found in the ceca varied. In B. marci, the amount of bacteria in the mesenteron sections able to grow on alkaline medium (pH 9) was higher than that of bacteria able to grow on slightly acidic medium (pH 5.5) during both the first and the second gut passage. In B. pomonae and P. holosericea, this increase was observed only during the second gut passage. The effect of gut passage in P. holosericea on changes in direct counts of bacteria was more pronounced when the larvae were fed at 5 degrees C as compared to 20 degrees C. Radiolabeled bacteria were digested in the gut and utilized as a source of energy and nutrients by the larvae; digested bacteria represented up to 10% of the material assimilated by the larvae. Lysozyme activity in whole-gut extracts of P. holosericea had a pH optimum of at pH 7, indicating a low in situ activity in the alkaline mesenteron. Proteinase activity, however, had an optimum at pH > 12, suggesting that the digestion of bacteria in the bibionid gut is caused by a combination of digestive proteinases and alkaline pH in the anterior mesenteron.     

Indirect effects of lemming cycles on sandpiper dynamics: 50 years of counts from southern Sweden

The bird-lemming hypothesis postulates that breeding success of tundra-nesting geese and waders in Siberia follows the cyclic pattern of lemming populations, as a result of predators switching from lemmings to birds when the lemming population crashes. We present 50 years of data on constant-effort catches of red knot Calidris canutus and curlew sandpiper C. ferruginea at an autumn migratory stopover site (Ottenby) at the Baltic Sea, supplemented with literature data on winter censuses of dark-bellied brent goose Branta b. bernicla and white-fronted goose Anser albifrons in northwestern Europe, and waders in Germany and Southern Africa. Number and proportion of juveniles in these bird populations (both our own and literature data) were compared with an index of predation pressure (calculated from the abundance of lemmings on the Taimyr peninsula), and climate indices for the North Eurasia and the North Atlantic regions. The index of predation pressure correlated significantly with the number of juveniles of red knot and curlew sandpiper, but not with number of adults. Also, this index correlated with the reproductive performance of geese and waders reported in the literature. Fourier analysis revealed a significant deviation from random noise with the maximum spectral density at the period length of 3 years for number of juvenile red knots and curlew sandpipers captured at Ottenby, abundance of lemmings, reproduction in arctic fox Alopex lagopus, and reproductive performance in geese on the Siberian tundra. Also, the date of passage at Ottenby for adult red knot and curlew sandpiper showed a spectral density peak at a period length of 3 years, the latter species also showing a peak at a period length of 5-6 years. Passage dates for adult red knot and curlew sandpiper were earlier in years of high predation pressure compared with years of low predation pressure. The fluctuations in reproductive success of the studied Siberian goose and wader species appear to be primarily influenced by biotic factors in the breeding area, rather than by abiotic factors, such as climate oscillations. Annual variations in migratory arctic bird populations may have far reaching effects in habitats along their migration routes and in their wintering areas. We suggest a link between lemming cyclicity in the Northern Hemisphere and predation pressure on Southern Hemisphere benthos, in which the signal is carried between continents by long distance migrating waders.