Succession and soil development in man-made coastal ecosystems at the Baltic Sea

By the creation of Køge Bay Seaside Park in 1978 the opportunity was given to study the establishment of vegetation and primary succession in a man-made coastal area. As the soil consists of marine material from the Baltic Sea, no organic matter or seedbank was present. The first steps of primary succession were followed in 1980, when the initial inventories of flora immigration and soil development were carried out in coastal grasslands and plantings. The surveys were repeated in 1992 and 1993. Except for the planted woody species and a few sown grasses, all other species of plants have reached the area through natural dispersal of diaspores. The total number of species in the permanent plots has increased from 26 in 1980 to 91 in 1993. The results indicate that this number will continue to increase in the coming years until a certain level. Then it will probably decrease as a result of competition from woody species, unless the vegetation is kept in a steady state by disturbances or management. Today the area is very far from the initial situation, and the off-shore barrier has changed towards a landscape dominated by small groves and grasslands of an urban common type.     

Physical map and gene organization of the mitochondrial genome from the unicellular green alga Platymonas (Tetraselmis) subcordiformis (Prasinophyceae)

the entire mitochondrial genome (mt genome) of the unicellular green alga Platymonas subcordiformis (synonym Tetraselmis subcordiformis; Prasinophyceae) was cloned and a physical map for the four restriction enzymes Hind III, Eco RI, Bgl II and Xba I was constructed. The mt genome of P. subcordiformis is a 42.8 kb circular molecule, coding for at least 23 genes. Hybridization and sequence analysis revealed the presence of a ca. 1.5 kb inverted repeat on the mt genome of P. subcordiformis. Phylogenetic analyses based on sequences of several coxI genes were carried out. Our data indicate that mitochondria from P. subcordiformis and from land plants form a natural, monophyletic group.     

Transformation of difluorinated phenols by Penicillium frequentans Bi 7/2

The Penicillium frequentans strain Bi 7/2, using phenol as a sole source of carbon and energy,transformed the fluorinated phenols 2,3-, 2,4-, 2,5-and 3,4-difluorophenol rapidly. After growth on phenol, resting mycelia of the fungus converted the difluorophenols completely at an initial concentration of 0.5 mM within 6 hours. The corresponding difluorinated catechols were found to be intermediates of all difluorophenols investigated. A relatively unspecific phenol hydroxylase catalyzed this hydroxylation step and showed activities towards all difluorophenols tested. One difluorocatechol was formed from each difluorophenol substituted with fluorine in the ortho-position, whereas two catechols were formed from 3,4-difluorophenol, due to its two vacant ortho-positions. A partial defluorination (50-77%) was observed in all cases. This revised version was published online in August 2006 with corrections to the Cover Date.     

Analysis of cleavage site mutations between the NC and PR Gag domains of Rous sarcoma virus.

In retroviruses, the viral protease (PR) is released as a mature protein by cleavage of Gag, Gag-Pro, or Gag-Pro-Pol precursor polypeptides. In avian sarcoma and leukemia viruses (ASLV), PR forms the C-terminal domain of Gag. Based on the properties of a mutation (cs22) in the cleavage site between the upstream NC domain and the PR domain, the proteolytic liberation of PR previously was inferred to be essential for processing of Gag and Pol proteins. To study this process in more detail, we have analyzed the effects that several mutations at the NC-PR cleavage site have on proteolytic processing in virus-like particles expressed in COS and quail cells. Mutant Gag proteins carrying the same mutations also were synthesized in vitro and tested for processing with purified PR. In both types of studies, N-terminal sequencing of the liberated PR domain was carried out to exactly identify the site of cleavage. Finally, synthetic peptides corresponding to the mutant proteins were assessed for the ability to act as substrates for PR. The results were all consistent and led to the following conclusions. (i) In vivo, if normal processing between NC and PR is prevented by mutations, limited cleavage occurs at a previously unrecognized alternative site three amino acids downstream, i.e., in PR. This N-terminally truncated PR is inactive as an enzyme, as inferred from the global processing defect in cs22 and a similar mutant. (ii) In Gag proteins translated in vitro, purified PR cleaves this alternative site as rapidly as it does the wild-type site. (iii) Contrary to previously accepted rules describing retroviral cleavage sites, an isoleucine residue placed at the P1 position of the NC-PR cleavage site does not hinder normal processing. (iv) A proline residue placed at the P2 position in this cleavage site blocks normal processing.     

Resting Energy Expenditure in Obese African American and Caucasian Women

The prevalence of obesity among African American women approaches 50% and greatly exceeds rates for Caucasian women. In addition, black women lose less weight than white during obesity treatment and gain more weight when untreated. This study assessed resting energy expenditure (REE) and body composition in obese white (n=122) and black (n=44) women to explore the relationship between biological variables and these observed differences. REE and body composition were assessed by indirect calorimetry and densitometry, respectively, before weight loss. REE was significantly lower in black subjects (1637.6 ± 236.9 kcal/d) than in white (1731.4 ± 262.0) (p=0.04). REE remained significantly lower in blacks than whites after adjusting for body weight (p=0.02). REE, adjusted for fat-free mass, was also significantly lower in blacks than whites (p<0.0001), although the overestimation of fat-free mass by densitometry in blacks may have contributed to this finding. There were no differences between the groups in respiratory quotient. These results suggest that a decreased REE may exist in obese black women, and it may be related to the observed differences between black and white women in the prevalence of obesity and in the response to weight loss treatment. These crosssectional findings await confirmation in longitudinal studies.     

Coral reefs in Saudi Arabia: 3.5 years after the Gulf War oil spill

As a consequence of the 1991 Gulf War, 6–8 million barrels of oil were released into the marine environment and a total of 1.12 billion barrels were burned in the Kuwaiti oil fields. In order to detect delayed effects of the Gulf War pollution, six permanent transect lines were placed on Saudi Arabian offshore and inshore reefs. A comparison of three sets of video recordings taken between 1992 and 1994 indicated a significant increase in live coral cover. Therefore, it has been conclded that corals in Saudi Arabia survived the largest oil spill on record remarkably unscathed, with no visible signs of immediate or late effects up to 3.5 years after the Gulf War.     

Reduction of sensory cells in antennal sensilla correlated with changes in feeding behavior in the beetle Loricera pilicornis (Insecta,Coleoptera, Carabidae)

Summary The structure of the setae on the proximal antennal segments of the beetle Loricera pilicornis is described using electron microscopical methods. These setae are part of a prey-capturing apparatus and are inserted within flexible sockets. They have no central lumen.Four or five sensory cells are connected to each seta. One cell is characterized as a mechanoreceptor due to the presence of a tubular body and the location of its dendritic outer segment. The other sensory cells are of two types. One type shows the usual features of sensillar receptors except that the dendritic outer segments end beneath the seta within the cuticular sheath. In the other type all parts of the cell, including the perikaryon, appear undersized, and no axon was found. In a single case a sixth cell was found which lacks any process, although, due to its location, it belongs to the sensory cell group.The enveloping cells also deviate from the usual pattern. Trichogen and tormogen cells have no membrane folds nor microvilli. From the membrane of the thecogen cell, where it borders on the inner receptor lymph cavity, invaginations have developed which form voluminous membrane whorls. Portasomes are found on these membranes.On the basis of the structural features we hypothesize that the setae represent sensilla undergoing stepwise reduction, losing primordial gustatory units whilst the prey-capturing mechanism is optimized.Dedicated to Professor Dr. Dietrich Schneider on occasion of his 65th birthday     

Characteristics of single chemoreceptive units sensitive to amino acids and related substances in the crayfish leg

Summary Impulses in single afferent fibres from amino acid receptors were recorded extracellularly. Doseresponse relations were determined for different superfused amino acids; the relations all had a slope of 1, a common saturation level, and the action of different amino acids was characterized by a specific half saturation concentration,K _M. The most effective amino acids were always L-serine, L-alanine and L-histidine, having aK _M of 10^–5, 2·10^–5 and 1.5·10^–4 mol/l, respectively. The sequence of effective amino acids was the same for all units tested. Structural requirements for optimal stimulatory action of the amino acid molecules were concluded.Abbreviation vH van Harreveld solution This work was supported by the Deutsche ForschungsgemeinschaftWe gratefully acknowledge assistance in electronics from Mr. W. Zeitz, and in mechanics from Mr. D. Beyer and Mr. L. Müller. Technical help was provided by Mrs. E. Köster, secretarial help by Mrs. L. Bauer.