Enumeration and phylogenetic analysis of polycyclic aromatic hydrocarbon-degrading marine bacteria from Puget sound sediments.

Naphthalene- and phenanthrene-degrading bacteria in Puget Sound sediments were enumerated by most-probable-number enumeration procedures. Sediments from a creosote-contaminated Environmental Protection Agency Superfund Site (Eagle Harbor) contained from 10(4) to 10(7) polycyclic aromatic hydrocarbon (PAH)-degrading bacteria g (dry weight) of sediment-1, whereas the concentration at an uncontaminated site ranged from 10(3) to 10(4) g of sediment(-1). Isolates of PAH-degrading bacteria were obtained from these most-probable-number tubes as well as from sediment samples from noncontaminated sites and from bioreactors enriched with PAHs. The 18 resulting strains were grouped by whole-cell fatty acid analysis into two subgroups. The larger group of strains belonged to the newly described genus Cycloclasticus, whereas the other group contained members of the genus Vibrio. The Cycloclasticus group seems to be widespread in noncontaminated sediments. PAH degradation was confirmed in selected strains on the basis of removal of phenanthrene from growing cultures.     

Bestandsentwicklung, H?henverbreitung und Ansiedlungsverhalten des Trauerschn?ppersFicedula hypoleuca im Harz

Zusammenfassung Der Rückgang der Siedlungsdichte des Trauerschnäppers im Harz 1971–1995 um fast 60% führte zu einer Senkung der Höhenverbreitung von 1000 m (Baumgrenze) auf 600 m (–40%) und dadurch zu einem Arealverlust von mindestens 450 km² im Westharz. Im 1. Lebensjahr siedelte sich die Mehrzahl der Weibchen (88%) zwischen +200 m (aufwärts) und –200 m (abwärts) um den Geburtsort an mit einer Bevorzugung zu tieferen Lagen, maximal +310 m bzw. –360 m (im Untersuchungsgebiet höchstens 370 m möglich), Median und Mittelwert betrugen –10 m. Bei kühleren Apriltemperaturen (Ankunftszeit der Trauerschnäpper) brüteten Erstansiedler mehr als sonst in tieferen Lagen und umgekehrt. Die vertikalen Ansiedlungspfeile über Grund wiesen in alle Richtungen. 60% der Vögel blieben der Exposition des Geburtsortes treu, ein Wechsel fand um so häufiger statt, je höher und damit dichter der Geburtsort zu den Kammlagen gelegen war. Das komplexe Zusammenwirken von Einflüssen auf das Ansiedlungsverhalten im Bergland wird diskutiert.

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Population development, altitudinal distribution and settling behaviour ofFicedula hypoleuca in the Harz Mountains

Between 1971 and 1995, an almost 60% decline in the population density ofFicedula hypoleuca led to a reduction of the altitudinal boundary from 1000 (tree line) to 600 m a.s.l. in the Harz region. This means a loss of 40% of the area settled so far, equalling at least 450 km² in the Westharz. In their first year the majority of females (88%) settled within a distance of between 200 m above and 200 m below their places of birth with a marked preference for lower altitudes (range 310 m above to 360 m below). When in April temperatures were below average, birds breeding for the first time preferred lower altitudes. The preference was reversed when temperatures were above average. The vertical distribution vector pointed in all directions. In comparison to their birthplace 60% of the birds settled on the same exposure of slopes. A change of exposure was most noticeable when the birthplace was near the ridge. The interactions of factors influencing the pattern of settling mountains are discussed.

     

Die Aufnahme von Schwefeldioxyd (S35O2) aus der Luft

Zusammenfassung Mittels einer S³⁵O₂-Begasung von Sonnenblumen, Mais, Tabak und ?lrettich wurden Einbau und Transport des aus der Luft in die einzelnen Pflanzenorgane aufgenommenen Schwefels untersucht. W?hrend die Aufnahmeintensit?t der Pflanze für SO₂ aus der Atmosph?re mit dessen Konzentration (variiert von 0–1,5 mg SO₂/m³ Luft) und der Expositionsdauer (Zwischenernten der drei untersten Sonnenblumenbl?tter) stetig zunimmt, verl?uft der Einbau in die einzelnen Schwefelfraktionen unterschiedlich. Am st?rksten wurde der Sulfatschwefel angereichert, an dem die Bl?tter den h?chsten und Stengel und Wurzeln die niedrigsten Gehalte aufwiesen. Ebenso erf?hrt der organisch gebundene Schwefel mit steigender SO₂-Behandlung eine Zunahme, die bei den Bl?ttern am st?rksten ausgepr?gt ist und in der h?chsten Behandlungsstufe den Wert der Kontrolle um das 3–4 fache übersteigt. Das Verh?ltnis des s?ureunl?slichen organisch gebundenen Schwefels zum s?urel?slichen organisch gebundenen Schwefel nimmt mit steigender SO₂-Behandlung ab. Lediglich beim ?lrettich ist das Verh?ltnis dieser beiden S-Fraktionen in allen SO₂-Steigerungsstufen wenig ver?ndert. Der destillierbare Schwefel wurde bei Sonnenblumen, Tabak und Mais nur in geringen Mengen (5–14 ppm S) gefunden, was sowohl auf einen schnellen Umbau des aufgenommenen SO₂ als auch auf ein w?hrend der Trocknung eingetretenes Entweichen von noch ?u?erlich anhaftendem SO₂ hindeutet. Die bei ?lrettich h?heren Gehalte an destillierbarem Schwefel dürften auf eine teilweise Miterfassung von Senf?len zurückzuführen sein. Der Gehalt an diesen erfuhr mit steigender SO₂-Konzentration eine Abnahme, was auf eine Beeintr?chtigung der die Senf?lsynthese katalysierenden Enzyme durch das SO₂ hinweist. Die Ergebnisse werden ausführlich diskutiert und die Bedeutung des SO₂ sowohl als N?hrstoff als auch als Schadstoff herausgestellt.     

Zur Brutbiologie und H?henverbreitung der Wasseramsel(Cinclus c. aquaticus) im Harz

Zusammenfassung 1972–1980 wurden im Harz brutbiologische Daten der Wasseramsel gesammelt.Der Nestbau erfordert im Mittel 18 Tage (n=18). Der Legebeginn liegt im Mittel um den 21. 4. (n=83); er zeigt eine vertikale Verzögerung von 5,92 Tagen/100 m. Diese verläuft parallel zur Schneeschmelze bzw. zum Beginn der Vegetationsentwicklung (Entwicklung der Nahrung?).Die Brutdauer beträgt 16,5 Tage (n=16). Die Gelegegröße umfaßt im Mittel 4,86 Eier (n=88), sie sinkt um 0,17 Eier/Dekade und um 0,20 Eier/100 m ab.Der Bruterfolg beträgt im Mittel 3,91 Junge (n=66), das sind 80% der gelegten Eier. Er sinkt um 0,13 Junge/Dekade. Er zeigt ein Maximum bei 4–500 m und sinkt zu niedrigeren und größeren Höhen ab.Der Zweitbrutanteil beträgt 11,8%, Zweitbruten hatten im Mittel 4,38 Eier (n=8) und brachten 3,0 flügge Junge (n=5) zum Ausfliegen.In Bezug auf die Höhe liegt der Verbreitungsschwerpunkt bei 3–400 m; oberhalb sinkt die Besiedlung bei einer Höhenzunahme um jeweils 120–130 m auf die Hälfte, unterhalb ist das Vorkommen durch Talsperren und Städte reduziert.Aus dem Bruterfolg und der Überlebensrate läßt sich in einer Modellrechnung für den Westharz abschätzen, daß die Population der Wasseramsel zwischen 265 und 685 m stabil ist und die Vorkommen unterhalb und oberhalb aus dem Überschuß gestützt werden.

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On the breeding biology and the altitudinal distribution of the Dipper (Cinclus c. aquaticus) in the Harz Mountains

Summary 1972–80, breeding data of the Dipper in the Harz Mountains were collected.A mean of 18 days is required for nest building (n=18). Egg-laying starts on average of April 21 and shows an altitudinal retardation of 5.92 days per 100 m. This runs parallel to the melting of snow and the beginning of vegetation development respectively.The mean breeding period is 16.5 days (n=16). The mean clutchsize is 4.86 eggs (n=88) and decreases by 0.17 eggs per ten-day period and by 0.20 eggs per 100 m.The mean breeding success amounts to 3.91 young (n=66), which is 80% of the eggs laid. This decreases by 0.13 young per ten-day period. It shows a maximum at 4–500 m and decreases at lower and higher altitudes.The amount of second broods is to 11.8%, second clutches consisted of 4.38 eggs (n=8) and 3.0 fledged young (n=5) leave the nest.With reference to the altitude, the main distribution lies at 3–400 m; above this the population density decreases for every height increase of 120–130 m to half and below the occurrence is reduced by dams and towns.A calculation for the West Harz Mountains can be assessed from the breeding success and survival rates, and that is, that the population of the Dipper is stable between 265 and 685 m and the upper and lower occurrences are based on the surplus.

     

Baleen whales: preliminary evidence for forestomach microbial fermentation.

Baleen whales have a multichambered stomach divided into three distinct compartments. The forestomach (first compartment) consists of noncornified and nonglandular tissue and appears to be analogous to the tissue of the rumen. The exact function of the forestomach is unknown; however, we have detected volatile fatty acids in forestomach samples from seven bowhead (Balaena mysticetus) and four gray (Escherichtius robustus) whales. Acetic, propionic, and butyric acids were found in all samples. Seven whale samples also contained valeric, isobutyric, isovaleric, and isocaproic acids. Bacterial counts in 10 of the samples ranged from 5 X 10(8) to 630 X 10(8)/ml of fluid. The types, concentrations, and relative proportions of volatile fatty acids, the presence of significant levels of bacteria, and the morphology of the digestive tract support the hypothesis that a microbial forestomach fermentation occurs in these two species of baleen whales.     

Trophic transfer of biodiversity effects: functional equivalence of prey diversity and enrichment?

Producer diversity is frequently assumed to be detrimental to herbivores, because less edible taxa are more likely to dominate diverse communities. Many producers are, however, complementary in their resource use, and primary production is often positively related to producer diversity. We performed an experiment with microalgae and a generalist herbivore to explore the hypothesis that such positive effects are transferred up the food chain and are functionally comparable to effects of enrichment with a limiting resource. In both absence and presence of grazers, primary production was positively affected by both light supply and producer diversity. Survival, reproduction, and biomass of herbivores were also positively affected by light supply and producer diversity, with both factors contributing equally to grazer performance. We conclude that producer diversity can indeed have similar positive effects on secondary production as enrichment with a limiting resource and discuss conditions under which such positive effects are likely to dominate over negative ones.     

The g protein-coupled receptor agtrl1b regulates early development of myocardial progenitors

While many factors that modulate the morphogenesis and patterning of the embryonic heart have been identified, relatively little is known about the molecular events that regulate the differentiation of progenitor cells fated to form the myocardium. Here, we show that zebrafish grinch (grn) mutants form a reduced number of myocardial progenitor cells, which results in a profound deficit in cardiomyocyte numbers in the most severe cases. We show that grn encodes the G protein-coupled receptor (GPCR) Agtrl1b, a known regulator of adult cardiovascular physiology. Ectopic expression of Apelin, an Agtrl1b ligand, results in the complete absence of cardiomyocytes. Data from transplantation and transgenic approaches indicate that Agtrl1 signaling plays a cell-autonomous role in myocardial specification, with activity being required coincident with the onset of gastrulation movements. These results support a model in which agtrl1b regulates the migration of cells fated to form myocardial progenitors.     

GENETIC POPULATION STRUCTURE OF PSEUDO‐NITZSCHIA PUNGENS (BACILLARIOPHYCEAE) FROM THE PACIFIC NORTHWEST AND THE NORTH SEA1

Several species of the diatom Pseudo‐nitzschia produce the neurotoxin domoic acid (DA). Consumption of fish and shellfish that have accumulated this potent excitotoxin has resulted in severe illness and even death in humans, marine mammals, and seabirds. Pseudo‐nitzschia pungens (Grunow ex Cleve) Hasle is a cosmopolitan diatom commonly occurring in the waters of the Pacific Northwest (PNW) and the eastern North Atlantic, including the North Sea. However, genetic and physiological relationships among populations throughout this large geographic distribution have not been assessed. Population genetic parameters (e.g., Hardy–Weinberg equilibrium, linkage equilibrium, F_ST) calculated for P. pungens collected from the Juan de Fuca eddy region in the PNW indicated the presence of two distinct groups that were more divergent from each other than either was from a P. pungens sample from the North Sea. Geographic heterogeneity was also detected within each of the two PNW groups. These results suggested that the populations of P. pungens recently mixed in the Juan de Fuca eddy region (a seasonally retentive feature off the coasts of Washington State, USA, and Vancouver Island, Canada) but did not exchange genetic material by sexual reproduction. Alternatively, these two groups may be cryptic (morphologically identical, but reproductively isolated) species. Identifying cryptic diversity in Pseudo‐nitzschia is important for bloom prediction and aiding the identification of molecular markers that can be used for rapid detection assay development.     

A comparison of DNA extraction procedures for the detection of Mycobacterium ulcerans, the causative agent of Buruli ulcer, in clinical and environmental specimens

Mycobacterium ulcerans is the causative agent of Buruli ulcer, the third most common mycobacterial disease in humans after tuberculosis and leprosy. Although the disease is associated with aquatic ecosystems, cultivation of the bacillus from the environment is difficult to achieve. Therefore, at the moment, research is based on the detection by PCR of the insertion sequence IS2404 present in M. ulcerans and some closely related mycobacteria. In the present study, we compared four DNA extraction methods for detection of M. ulcerans DNA, namely the one tube cell lysis and DNA extraction procedure (OT), the FastPrep procedure (FP), the modified Boom procedure (MB), and the Maxwell 16 Procedure (M16). The methods were performed on serial dilutions of M. ulcerans, followed by PCR analysis with different PCR targets in M. ulcerans to determine the detection limit (DL) of each method. The purity of the extracted DNA and the time and effort needed were compared as well. All methods were performed on environmental specimens and the two best methods (MB and M16) were tested on clinical specimens for detection of M. ulcerans DNA. When comparing the DLs of the DNA extraction methods, the MB and M16 had a significantly lower DL than the OT and FP. For the different PCR targets, IS2404 showed a significantly lower DL than mlsA, MIRU1, MIRU5 and VNTR6. The FP and M16 were considerably faster than the MB and OT, while the purity of the DNA extracted with the MB was significantly higher than the DNA extracted with the other methods. The MB performed best on the environmental and clinical specimens. This comparative study shows that the modified Boom procedure, although lengthy, provides a better method of DNA extraction than the other methods tested for detection and identification of M. ulcerans in both clinical and environmental specimens.