Influence of tree age, tree size and crown structure on lichen communities in mature Alpine spruce forests

Testing the relations between tree parameters and the richness and composition of lichen communities in near-natural stands could be a first step to gather information for forest managers interested in conservation and in biodiversity assessment and monitoring. This work aims at evaluating the influence of tree age and age-related parameters on tree-level richness and community composition of lichens on spruce in an Alpine forest. The lichen survey was carried out in four sites used for long-term monitoring. In each site, tree age, diameter at breast height, tree height, the first branch height, and crown projection area were measured for each tree. Trees were stratified into three age classes: (1) <100 years old, immature trees usually not suitable for felling, (2) 100–200 years old, mature trees suitable for felling, and (3) >200 years old, over-mature trees normally rare or absent in managed stands. In each site, seven trees in each age class were selected randomly. Tree age and related parameters proved to influence both tree-level species richness and composition of lichen communities. Species richness increased with tree age and related parameters indicative of tree size. This relation could be interpreted as the result of different joint effects of age per se and tree size with its area-effect. Species turnover is also suspected to improve species richness on over-mature trees. Similarly to species richness, tree-level species composition can be partially explained by tree-related parameters. Species composition changed from young to old trees, several lichens being associated with over-mature trees. This pool of species, including nationally rare lichens, represents a community which is probably poorly developed in managed forests. In accordance to the general aims of near-to-nature forestry, the presence of over-mature trees should be enhanced in the future forest landscape of the Alps especially in protected areas and Natura 2,000 sites, where conservation purposes are explicitly included in the management guidelines.     

Patterns in species richness,species density,and evenness in groundfish assemblages on the continental slope of the U.S. Pacific coast

For many taxa, diversity, often measured as species richness, decreases with latitude. In this report patterns of diversity (species richness, species diversity, and evenness) in groundfish assemblages were investigated in relation to depth (200–1200 m) and latitude (33–47°N) on the continental slope of the U.S. Pacific coast. The data originated from the 1999–2002 upper continental slope groundfish surveys conducted by the National Marine Fisheries Service. When the data were pooled across depths, species density and evenness were found to decline with latitude. All three diversity measures declined with depth, with the lowest overall diversity in the 600- to 900-m depth range where longspine thornyhead Sebastolobus altivelis constituted close to 70% of the catch. When latitudinal gradients were examined within four depth zones (200–300 m, 400–500 m, 600–900 m, and 1000–1200 m) more complex patterns emerged. At depth species richness and evenness were inversely correlated with latitude as longspine thornyhead dominated catches to the north. However, in shallower areas of the slope, species richness and evenness were positively correlated with latitude. Latitudinal patterns of diversity in the deeper zones and when pooled across depths were positively correlated with temperature and broadly consistent with the Ambient Energy hypothesis discussed by Willig et al. [Annu Rev Ecol System 34:273–309 (2003)].     

Molecular studies on isopenicillin N synthases

The isopenicillin N synthases isolated thus far are related to oxidases from other microorganisms and plants. These enzymes maintain a non-heme monoferrous-dependent catalytic centre comprising a HisXAsp(53–57)XHis motif and a crucial substrate-binding pocket with an ArgXSer motif for their functionality. The elucidation of these motifs was dependent on information collated from studies on structural chemistry, structural biology, site-directed engineered mutations and biochemical experiments. It is envisaged that these enzymes can potentially be improved through molecular breeding and protein engineering. Received: 15 December 1999 / Received revision: 26 January 2000 / Accepted: 27 January 2000     

Topography of cell traces studied by atomic force microscopy

Migrating adherent cells release material onto artificial substrates like glass and silicon while moving. Traces of mouse fibroblasts (L929) have been visualised by atomic force microscopy (AFM). “Non-contact” mode AFM in a liquid environment can extract topographic information from these traces. This dynamic mode allows the study of these soft structures without damage or compression. The AFM images show crossing and branching networks (with specific angles of branching), structured patches, nodular elements, linear elements with irregular height and other features. Fourier analysis of segment spacing in the strands is presented. These spatial features of fibroblast traces are strong indications that actin linked to structural proteins is involved in the formation of cell traces. We also give methods for trace preparation and undistorted imaging and discuss further perspectives. Received: 11 January 1999 / Revised version: 1 April 1999 / Accepted: 8 April 1999     

The estimated pore diameter for plasmodesmal channels in the Abutilon nectary trichome should be about 4 nm, rather than 3 nm

By injecting varous-size fluorescent probes into Abutilon striatum Dicks nectary trichomes, Terry and Robards (1987, Planta 171: 145–157) arrived at an estimate of 3 nm for the physical diameter of the channels involved in cell-to-cell movement. However, their calculations contain an arithmetic error in the volume assumed for the cell into which the probes diffused. (The actual volume is ten times larger.) The corrected calculations give a physical diameter of about 4 nm. Received: 5 January 1999 / Accepted: 29 January 1999     

Effects of river level fluctuation on plant species richness, diversity, and distribution in a floodplain forest in Central Amazonia

River levels in Central Amazonia fluctuate up to 14 m annually, with the flooding period ranging from 50 to 270 days between the rising and falling phases. Vast areas of forest along the rivers contain plant species that are well adapted to annual flooding. We studied the effect of flooding level on tree species richness, diversity, density, and composition in lake, river, and stream habitats in Jaú National Park, Brazil. 3051 trees >10 cm diameter (at 1.3 m diameter at breast height, dbh) were measured and identified in 25 10 m × 40 m randomly selected plots in each habitat. Ordination methods and analysis of variance results showed that forested areas near lakes had significantly lower species richness of trees than riverine and streamside habitats. Plot species richness and diversity were strongly negatively correlated with the water level and duration of flooding. The drier (stream) habitat had more total species (54 species of trees) and more unique species of trees (6 tree species) than the riverine (52 tree species; 3 unique species) and lake (33 tree species; 3 unique species) habitats. Species composition overlap among habitats was surprisingly high (42.6–60.6% overlap), almost one-third of the species were found in all three habitat types, and few species were unique to each habitat. We conclude that: (1) duration of flooding has a strong impact on species richness, diversity and plant distribution patterns; (2) most species are adapted to a wide range of habitats and flood durations; and (3) while flood duration may decrease local diversity, it also creates and maintains high landscape-scale diversity by increasing landscape heterogeneity. Received: 20 April 1997 / Accepted: 14 January 1999     

Periodical cicadas

The evolution of periodicity and synchronicity of magical cicadas is studied by means of mathematical models. Received: 28 January 1999 / Revised version: 4 November 1999 / Published online: 3 April 2000     

Effect of temperature and pH on growth and product formation of Lactococcus lactis ssp. lactis ATCC 19435 growing on maltose

Lactococcus lactis ssp. lactis ATCC 19435 is known to produce mixed acids when grown on maltose. A change in fermentation conditions only, elevated temperatures (up to 37 °C) and reduced pH values (down to 5.0) resulted in a shift towards homolactic product formation. This was accompanied by decreased growth rate and cell yield. The results are discussed in terms of redox balance and maintenance, and the regulation of lactate dehydrogenase and pyruvate formate-lyase. Received: 14 December 1998 / Received revision: 12 January 1999 / Accepted: 22 January 1999     

Explaining co-occurrence among helminth species of lesser snow geese (Chen caerulescens) during their winter and spring migration

The digestive tracts of 771 lesser snow geese (Chen caerulescens) collected from January to May 1983 from 12 locations (27 samples) were examined for helminth parasites to determine whether parasite species present in wintering geese or in spring migrants occurred independently of each other. Nine helminth species were identified. Seven had mean prevalences >5% and were the focus of this study. Six of those species were waterfowl generalists, one was a goose specialist. Our primary objective was to assess the potential contribution of factors, other than species interactions, in determining patterns of co-occurrence between helminth species. There were few negative relationships between helminth species, regardless of whether presence-absence or abundance data were used. However, some species pairs showed recurrent and significant co-occurrences. There were similar and significant effects of timing of sampling, host gender, and host age, on prevalence and mean abundance of particular species. Co-occurrences were found for those species that showed seasonal declines in prevalence, for those expected to have high colonizing ability based on host age profiles (using abundance data), and for abundant species that may have shared vectors or environmental conditions favorable for transmission. Thus, similarities between parasites in their abundance, transmission biology, and phenology seem sufficient to explain species co-occurrences without invoking other processes such as species interactions. Received: 18 March 1996 / Accepted: 20 April 1999     

Characterisation of a starch-hydrolysing enzyme of Aspergillus niger

A UV-induced mutant strain of Aspergillus niger (CFTRI-1105-U9) overproduced a starch-hydrolysing enzyme with properties characteristically different from the known amylases of the fungus. The purified enzyme of 4.0 pI had an apparent molecular mass of 125 kDa and it dextrinised starch and then saccharified the dextrins. Patterns of the enzyme activity on starch, resulting in glucose at 60 °C and glucose, maltose and maltodextrins at 70 °C as primary products, suggested significant applications for the enzyme in starch-processing industries. Received: 29 October 1998 / Received revision: 11 January 1999 / Accepted: 19 January 1999     

Solid matrix characterization of immobilized Pseudomonas putida MTCC 1194 used for phenol degradation

Characterization studies of calcium alginate beads with encapsulated Pseudomonas putida MTCC 1194, used for the biodegradation of phenol, were carried out to investigate the reactivity, reusability and structural strength of the solid matrix. Various techniques were employed to improve the structural stability of the immobilized solid necessary for its use in commercial reactors like packed bed flow reactor, fluidized bed and CSTR systems. Experiments were performed to establish the optimum conditions for durability, strength and steady biochemical reactivity. During a batch run of 40 h a gradual decline in the rate of phenol degradation was observed with the immobilized system. The calcium alginate beads with high structural strength yielded decreased activity. Treatment with a hardening agent like glutaraldehyde for different concentrations and treatment times led to variations in structural stability, reusability and the extent of phenol degradation. Scanning electron microscope studies of the immobilized solid indicated the internal distribution pattern of the cells encapsulated in a calcium alginate bead. Received: 13 November 1998 / Received revision: 27 January 1999 / Accepted: 31 January 1999     

1H NMR studies: dynamics of water in gelatin

 Proton magnetic resonance was used to characterize the dynamics of water in gelatin. Both sol and gel states were investigated. Transverse relaxation rates (R ₂) were dependent on the proton frequency measurement. (R ₂) measured with the Carr-Purcell-Meiboom-Gill pulse sequence was dependent on pulse spacing. These observations were interpreted in terms of chemical exchanges between water protons and those of the macromolecules in the sol state, whereas in the gel state the contribution of diffusion through microheterogeneities in the sample seems to provide an additional transverse relaxation mechanism. Received: 10 May 1999 / Revised version: 13 December 1999 / Accepted: 25 January 2000     

Construction of a flocculent Saccharomyces cerevisiae fermenting lactose

A flocculent Saccharomyces cerevisiae strain with the ability to express both the LAC4 (coding for β-galactosidase) and LAC12 (coding for lactose permease) genes of Kluyveromyces marxianus was constructed. This recombinant strain is not only able to grow on lactose, but it can also ferment this substrate. To our knowledge this is the first time that a recombinant S. cervisiae has been found to ferment lactose in a way comparable to that of the existing lactose-fermenting yeast strains. Moreover, the flocculating capacity of the strain used in this work gives the process several advantages. On the one hand, it allows for operation in a continuous mode at high cell concentration, thus increasing the system's overall productivity; on the other hand, the biomass concentration in the effluent is reduced, thus decreasing product separation/purification costs. Received: 2 October 1998 / Received revision: 15 January 1999 / Accepted: 17 January 1999     

Degradation of phosphonates by streptomycete isolates

Wild-type Streptomyces sp. strains, able to utilise both naturally occurring and synthetic organophosphonates, were isolated. High levels of inorganic phosphate were necessary for their growth in complete medium as well as in medium, supplemented with phosphonates as the sole carbon or nitrogen source. Isolate StA expressed detectable enzymatic activity against 2-aminoethylphosphonate in vivo. Streptomycete StC had a surprising ability to degrade N-phosphonomethylglycine (glyphosate) in a phosphate-independent manner via C–P bond cleavage accompanied by sarcosine formation. Received: 5 January 1999 / Received revision: 8 March 1999 / Accepted: 14 March 1999     

Functionality of biphenyl 2,3-dioxygenase components in naphthalene 1,2-dioxygenase

Naphthalene 1,2-dioxygenase (Nap dox) and biphenyl 2,3-dioxygenase (Bph dox) are related enzymes that have differentiated during evolution as their specificity has changed. Although their component arrangement is similar, the structure of each component has been modified quite extensively. The purpose of this work was to determine the catalytic capacity of purified Nap dox toward chlorobiphenyls and to investigate the functionality of Bph dox components in the Nap dox system. Both enzyme systems were purified by affinity chromatography as histidine-tagged fused proteins. Data show for the first time that Nap dox can catalyze the oxygenation of all three monochlorobiphenyl isomers, but it is unable to hydroxylate 2,5-, 2,2′-, 3,3′-, 4,4′-di- and 2,2′,5,5′-tetrachlorobiphenyl. The rates of cytochrome c reduction by the ferredoxin components of the two enzymes were identical when the Bph dox reductase component was used in the assay, showing an efficient electron transfer between the Bph dox reductase component and the Nap dox ferredoxin. However, when the Bph dox ferredoxin was used to reconstitute a hybrid Nap dox, the enzyme was only 22% as active as the parental enzyme. These data are discussed in terms of the potential use of Nap dox for the development of enhanced chlorobiphenyl-degrading dioxygenases. Received: 15 October 1998 / Received revision: 21 January 1999 / Accepted: 31 January 1999     

International radiobiology archives of long-term animal studies: structure, possible uses and potential extension

Animal experiments have contributed a great deal to our information on effects and risks arising from exposure to radionuclides. This applies, in particular, to alpha-emitting radionuclides where information from man is limited to thorotrast, ²²⁴Ra and ²²⁶Ra. The late C.W. Mays was the first to suggest that animal data in conjunction with epidemiological data could allow estimates of human risks for radionuclides – predominantly from actinides – where information in man is scarce. The ’International Radiobiology Archives of Long-term Animal Studies’ were created through the combined efforts of European, American and Japanese scientists and aim to safeguard the large amount of existing data on long-term animal experiments and make them available for, among others, an improved assessment of risks from alpha-emitting radionuclides. This paper summarizes the structure of the archives and reviews their present status and future plans. It also demonstrates the extensive information available in these archives on alpha-emitting radionuclides which is suitable for further analysis. Also, the structure of the animal archives could – in a slightly modified form – accommodate the epidemiological data available on ²²⁴Ra and thorotrast and, thus, facilitate a direct comparison of data from man, dogs and rodents. Received: 9 January 1999 / Accepted in revised form: 23 March 1999     

Nutrient requirements of lactococci in defined growth media

Many attempts have been made for the last six decades to design defined media for species of the lactococcus group. The general outcome of the studies suggests that this group is heterogeneous with respect to specific requirements for nutrients. Lactococcal species are limited in various metabolic pathways. Early attempts to trace the required nutrients were not always successful because of the poor quality of analysis and the presence of impurities in the medium components. Received: 15 January 1999 / Received revision: 6 April 1999 / Accepted: 9 April 1999     

The use of self-pollinated progenies as ’in-groups’ for the genetic characterization of cocoa germplasm

Theobroma cacao ) genotypes. Six primers were sufficient to distinguish all but three pairs of the 62 accessions examined. A UPGMA dendrogram was used to provide a measure of the genetic variability between genotypes. The scale was supplied by the inclusion of Theobroma grandiflora as an ’out group’ and also by the use of two contrasting progenies as ’in groups’. The ’in groups’ were obtained from the self-pollination of one plant (SPEC 54.1) known to be highly homozygous and also of a second, highly heterozygous, clone (P 19B). These reference points allowed several documentation errors to be resolved and provided a basis for identifying unwanted or low-priority material. Implications of the work for the routine maintenance of large germplasm collections are briefly discussed. Received: 20 January 1999 / Accepted: 25 May 1999     

Subcellular location of enzymes involved in oxidation of n-alkane by Cladosporium resinae

More than 70% of n-hexadecane-grown cells of Cladosporium resinae ATCC 22711 were converted to spheroplasts when they were treated with chitinase and lytic enzyme from Trichoderma harziamum. The light mitochondrial fraction, containing microbodies, mitochondria and vacuoles, was isolated from spheroplasts. Vacuoles in cells were demonstrated by the inability of acridine orange to stain organelles previously treated with 2.5 μM Bafilomycin A₁, a vacuolar ATPase inhibitor. Microbodies, mitochondria and vacuoles were separated from the light mitochondrial fraction by self-generated density-gradient ultracentrifugation using iodixanol as gradient medium. NADH-dependent n-alkane monooxygenase activity and fatty alcohol oxidase activity were located in the cytoplasm and mitochondrial fractions respectively. Received: 21 September 1998 / Received revision: 21 January 1999 / Accepted: 31 January 1999     

The role of the alternative respiratory pathway in the stimulation of cephalosporin C formation by soybean oil in Acremonium chrysogenum

Addition of soybean oil to Acremonium chrysogenum cultures growing on sugars doubled the specific production of cephalosporin C during the idiophase of growth. While the addition of soybean oil had no effect on the total rate of respiration, the respiration that proceeded via the alternative, cyanide-insensitive pathway exhibited a more than twofold increase. Addition of soybean oil also stimulated the formation of isocitrate lyase activities. Inhibition of oxidative metabolism of one of the products of isocitrate lyase (succinate) by thenoyltrifluoroacetone completely inhibited the alternative respiratory pathway. The role of soybean-oil-stimulated alternative respiration in the stimulation of cephalosporin C production and the role of isocitrate lyase are discussed. Received: 13 October 1998 / Revised revision: 14 January 1999 / Accepted: 22 January 1999