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A highly sensitive laser-driven photoacoustic detector responsive to [less than or equal to]2.1 nmol m-3 ethylene (50 parts per trillion [v/v]) was used for ethylene analysis. Dark-grown plants of Potamogeton pectinatus L. growing from small tubers made no ethylene. Exposure of shoots to white light, wounding, submergence in water followed by desubmergence, partial oxygen shortage, indole acetic acid, or carbon dioxide failed to induce ethylene production, although clear effects were observed in Pisum sativum L. Some ethylene was released after applying high concentrations of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC; 10 mol m-3) to P. pectinatus, but the amount was trivial compared with that released by P. sativum. More endogenous ACC was found in P. pectinatus than in P. sativum. Considerable ACC oxidase activity was present in tissue extracts of P. sativum. However, no ACC oxidase activity was found in P. pectinatus, indicating that this is where ethylene production is arrested.

The genus Pectinatus has been often reported in beer spoilage with off-flavours. The bacteria are strictly anaerobic, Gram-negative rods. Propionate and acetate are the main fermentation products from glucose in the two species belonging to the genus, P. cerevisiiphilus and P. frisingensis. Amino acids routinely present at a high level in beer were not growth substrates for both species, and a significant accumulation of succinate was observed with lactate as growth substrate. Both Pectinatus ssp. showed almost identical fermentation balances on glucose. Growth kinetics of both glucose-grown species were unchanged under a N2, H2 or 20% CO2-containing atmosphere. Combinations of culture medium pH values from pH 3 x 9 to pH 7 x 2, of glucose levels between 5 and 55 mmol l-1, and of lactate concentrations varied from 4 to 40 mmol l-1 demonstrated that biomass and volatile fatty acids production were proportional to glucose concentration for both Pectinatus species. A significant increase of volatile fatty acid production was measured for both species at the lowest pH values with a lactate or a glucose concentration increase. The maximum biomass production was observed at pH 6 x 2 for P. cerevisiiphilus, and between pH 4 x 5 and pH 4 x 9 for P. frisingensis. Glucose and lactate or pH value were dependent with regard to propionate and acetate production in P. frisingensis. On the other hand, the variations of these three parameters were independent with regard to biomass production for both strains, and to volatile fatty acids production for P. cerevisiiphilus. Addition of ethanol to glucose-grown cultures completely inhibited growth at 1 x 3 mol l-1 ethanol for P. cerevisiiphilus, and at 1 x 8 mol l-1 for P. frisingensis.

Argentine Potamogeton pectinatus L. was grown in The Netherlands under laboratory conditions at four light intensities (50, 100, 150 and 200 μE m −2 s−1), and photosynthetic performance was evaluated after about 1, 2 and 3 months of growth. At these moments, chlorophyll-a and -b and tissue N and P content were also determined. During the growing period, plant lengths and number of secondary shoots were measured. In the field in Argentina, photosynthetic performance of P. pectinatus was also measured at different light intensities created by artificial shading at various times during the growing season. Field and laboratory photosynthetic results were in good agreement. P. pectinatus showed a significant plasticity in its photosynthesis, rather than in morphology. A fairly constant maximum photosynthetic rate with reduced light enabled the plants to maintain net production rates rather unaffected at low light intensities. Still, it can be predicted that increasing turbidity from 1-2 m−1 at present to 3 m-1 could lead to a strongly light-limited growth which should reduce the present weed problem considerably. Such a turbidity increase might be achieved by the introduction of a fairly dense bottom-feeding fish population like Common carp (Cyprinus carpio L.).

Plants and seedlings of Potamogeton pectinatus were obtained from tubers grown under laboratory conditions. Four plants (mean total length: 14.3 m) and two seedlings (mean height: 10.9 cm) were placed in each of twenty 1001 aquaria illuminated with fluorescent lighting. A 5 cm-thick layer of muddy sediment was then put in each aquarium together with two size-matched fish (mean size classes: 6.8, 14.1 and 23.0 g) of the species Cyprinus carpio. After four weeks, the total length of the plants in the control and small fish aquaria had increased by 71% and 3% respectively, whereas plant total length in the aquaria with medium and large fish had diminished by 33% and 76%, respectively. Few seedlings survived in the presence of the fish. The reduction in plant growth was associated with an increase in water turbidity in all treatments as a result of the benthic feeding habit of C. carpio, and of direct herbivory action in the case of medium- and large-sized fish.

Mild acid hydrolysis of the smooth-type lipopolysaccharide (LPS) of Pectinatus frisingensis afforded no polysaccharide but monomeric 6-deoxy-L-altrose (L-6dAIt) which was identified by anion-exchange chromatography in berate buffer, GLC/MS, H-1-NMR spectroscopy, and optical rotation. LPS was degraded with alkali under reductive conditions to give a completely O-deacylated polysaccharide, which was studied by methylation analysis, H-1-NMR and C-13-NMR spectroscopy, including sequential, selective spin-decoupling, two-dimensional correlation spectroscopy (COSY), COSY with relayed coherence transfer, two-dimensional heteronuclear C-13, H-1-COSY, one-dimensional NOE and two-dimensional rotating-frame NOE spectroscopy. It was found that the O-specific polysaccharide chain of P. frisingensis LPS is a homopolymer of 6-deoxy-L-altrofuranose built up of tetrasaccharide-repeating units having the following structure: [GRAPHICS] Similarly, mild acid degradation of smooth-type LPS of Pectinatus cerevisiiphilus resulted in depolymerisation of the polysaccharide chain to give a disaccharide consisting of D-glucose and D-fucose, Study of the disaccharide by methylation analysis and alkali-degraded LPS by one-dimensional and two-dimensional H-1-NMR and C-13-NMR spectroscopy showed that the O-specific polysaccharide of P. cerevisiiphilus has the following structure: -->2)-beta-D-Fucf-(1-->2)-alpha-D-Glcp-(1-->

Survival of Pectinatus cerevisiiphilus DSM 20466 in pure culture at variable temperatures under different oxygen concentrations was measured. Survival of P. cerevisiiphilus in co-culture with Saccharomyces cerevisiae under both saturated oxygen and brewing conditions was also studied. The survival of strictly anaerobic bacteria to oxygen seems to follow the classical laws of heat resistance. The D(oxy) values of P. cerevisiiphilus , calculated as a function of oxygen level, shows that the oxygen level is important for the survival duration of the bacteria. The temperature greatly influences the oxygen resistance of P. cerevisiiphilus, which increases when the temperature decreases. P. cerevisiiphilus resists better in co-culture than in pure culture under saturated oxygen conditions. Therefore, the oxygenation of the wort does not totally eliminate the risk of beer contamination by this bacterium. Under brewing conditions in co-culture at 8 degrees C, P. cerevisiiphilus grows slowly to reach a final cell concentration up to 10(6) cells/mL in beer, which is undrinkable. Pectinatus is a strictly anaerobic bacterium; however, it is resistant under certain oxygen conditions of incubation. This resistance is considerably higher in the presence of Saccharomyces cerevisiae .

The nucleotide sequence of the 16S rRNA gene of the type strain of Dialister pneumosintes was determined. Phylogenetic analysis revealed that this species belongs to the Sporomusa branch of the Clostridium subphylum of the gram-positive bacteria and should therefore be excluded from the family Bacteroidaceae. Within this branch, which encompasses several other gram-negative taxa, such as Acidaminococcus, Pectinatus, Phascolarcobacterium, Quinella, Selenomonas, and Zymophilus, Dialister showed a specific, albeit distant, affinity with the genera Megasphaera and Veillonella.

SUMMARY The strictly anaerobic Gram-negative beer spoilage bacteria Megasphaera cerevisiae, Pectinatus cerevisiiphilus and P. frisingensis were subjected to cellular fatty acid analysis, employing acid- and base-catalysed cleavage, gas chromatography and mass spectrometry. M. cerevisiae contained 12:0, 16:0, 16:1, 18:1, 17:cyc, 19:cyc, 12:0(3OH), 14:0(3OH) as the main fatty acids, and alk-1-enyl chains instead of acyl chains were detected to a considerable extent (14% of total fatty acids), indicating the presence of plasmalogens. The fatty acid pattern of M. cerevisiae was almost identical to that of M. elsdenii, the only species previously assigned to this genus. P. cerevisiiphilus and P. frisingensis yielded fatty acids that were heavily dominated by odd-numbered chains; 11:0, 15:0, 17:1, 18:cyc and 13:0(3OH) were the main fatty acids detected in both species. Alk-1-enyl chains with similar chain lengths were also found. Both Pectinatus species contained six different 3-hydroxy fatty acids with chain lengths between 11 and 15 carbons, 13:0(3OH) being dominant and the others accounting for generally less than 1% of total fatty acids. Among the minor components, an unsaturated 3-hydroxy fatty acid was detected which was shown to be 13:1(30H). In addition, fatty acid analysis was shown to be applicable to detection of bacterial contamination of beer.

Cellular fatty acid profiles were determined for species in 33 genera of anaerobic gram-negative bacilli and were confirmed to be a useful taxonomic tool. Most of the genera could be differentiated by visual inspection of their profiles. The three genus pairs that were most difficult to distinguish visually (Bacteroides and Prevotella, Pectinatus and Megamonas, and Serpulina and Bilophila) and the species of these genera were differentiated by the MIDI (Microbial ID, Inc.) identification system. Similarities in cellular fatty acid profiles may be correlated with similarities in other phenotypic characteristics, but more often there is no other obvious phenotypic relationship. Although medium components may not change the constituents detected or the ratios among the constituents detected for some species, identical medium changes may result in vast differences in the profiles obtained with other species. Thus, if a worker wishes to compare profiles of various taxa, it is essential that the same cultural and analytical conditions be used.

The genus Pectinatus includes strictly anaerobic Gramnegative non-spore-forming mesophilic bacteria, often referred to as beer spoilage bacteria. Pectinatus frisingensis was chosen as reference strain. Growth was achieved in batch cultures under stringent anaerobic conditions with synthetic medium and pH regulation. Various glucose concentrations were used, and low inoculum reproduced spoilage conditions in bottled beer. A lag-phase of around 20 hours was observed in every case; glucose was converted to propionate, acetate, succinate and CO 2 , while lactate was a transient metabolite. Glucose concentrations typically found in beer allowed good growth of Pectinatus frisingensis , rapidly leading to cloudy culture medium. Resulting volatile fatty acid concentrations were far higher flavour thresholds. Monod-type modelling of strain growth allowed good forecast of both biomass and volatile fatty acid production over five-day time periods.

A description is given of the macrophyte growth model SAGA 1, developed for Potamogeton pectinatus L. Based on various laboratory and field experiments, the model incorporates effects of light and age on plant photosynthesis, growth and development and on tuber bank dynamics. The vegetation is described in layers and consists of three subvegetations, each with its own tuber bank with a fixed tuber size. Self-shading between and within subvegetations is incorporated. Light and age effects on photosynthetic parameters generate a decrease in production. This leads to an increased chance for wave damage. In most cases, this results in the disappearance of the vegetation at the end of the growing season.

Preface W. van Vierssen, M.J.M. Hootsmans, J.E. Vermaat. 1. Introduction, the Scope of the Research Project W. van Vierssen, M.J.M. Hootsmans, J.E. Vermaat. 2. The Zuiderzee: Transformation of a Brackish Water Ecosystem W. van Vierssen, A.W. Breukelaar. 3. Twenty Years of Dynamics and Distribution of Potamogeton pectinatus L. in Lake Veluwe M. Scheffer, H. Drost, M.R. de Redelijkheid, F. Noppert. 4. Intraspecific Variation in Potamogeton pectinatus L., a Controlled Laboratory Experiment J.E. Vermaat, M.J.M. Hootsmans. 5. Growth of Potamogeton pectinatus L. in a Temperature-Light Gradient J.E. Vermaat, M.J.M. Hootsmans. 6. Light-Response Curves of Potamogeton pectinatus L. as a Function of Plant Age and Irradiance Level during Growth M.J.M. Hootsmans, J.E. Vermaat. 7. Photoperiodic Effects on Photosynthesis and Tuber Production in Potamogeton pectinatus L. W. van Vierssen, M.J.M. Hootsmans. 8. Early Growth Characteristics of Potamogeton pectinatus L.: the Significance of the Tuber W. van Vierssen, A. Mathies, J.E. Vermaat. 9. Seasonal Dynamics of a Field Population of Potamogeton pectinatus L. under Various Experimental Light Conditions W. van Vierssen, M.J.M. Hootsmans, A.W. Bruekelaar, R. Gijlstra. 10. Factors contributing to Light Attenuation in Lake Veluwe G. Blom, E.H.S. van Duin, J.E. Vermaat. 11. Allelopathic Limitation of Algal Growth by Macrophytes M.J.M. Hootsmans, I. Blindow. 12. Periphyton Dynamics in a Temperature-Light Gradient J.E. Vermaat, M.J.M. Hootsmans. 13. Periphyton Removal by Freshwater Micrograzers J.E. Vermaat. 14. A Growth Analysis Model for Potamogeton pectinatus L. M.J.M. Hootsmans. 15. Interactions between Aquatic Macrophytes and Fish in Lake Veluwe, Direct and Indirect Effects H.W. de Nie, J.J.G.M. Backx. 16. General Conclusions and Implications for Lake Management W. van Vierssen, M.J.M. Hootsmans, J.E. Vermaat. Appendices. Index.

The influence of different combinations of photoperiods and photosynthetic periods on the production of tubers in Potamogeton pectinatus L. was studied under laboratory conditions. To distinguish between photosynthetic and photoperiod, three different light regimes were used. One regime consisted of the classical long-day condition (regime 1: 16 h 200 μE m−2 s−1; long photoperiod and long photosynthetic period). In regime 2, a period of 10 h 200 μE m−2 s−1 was wedged in beween 2 additional periods of 3 h dim light conditions (10 μE m−2 s−1 ; long photoperiod but short photosynthetic period). Regime 3 was a short day of 10 h of 200 μ m−2 s−1 ; i.e. a short photoperiod and a short photosynthetic period.

In a controlled laboratory experiment, the question was addressed whether intraspecific variation in Potamogeton pectinatus L. has a genotypic component. Two populations from contrasting habitats in The Netherlands were tested, one habitat was the exposed and eutrophic freshwater Lake Veluwe and the other a brackish ditch on the island of Texel. Weight frequency distributions of the natural tuber banks in spring were significantly different, while tuber specific densities (weight per volume) were not.

In the period 1986–1988, a shading experiment was performed in a homogeneous Potamogeton pectinatus L. vegetation in Lake Veluwe. The experiment consisted of two different main treatments. In the S-series, the vegetation was shaded during two years (1986–1987) using three different types of neutral density shade netting and an unshaded control. The shading intensities used were 26%, 45% and 73%. The vegetation was left unshaded during 1988. In the U-series, the vegetation was shaded during 1986 only, using the same shading levels as for the S-series. The vegetation was left unshaded during 1987–1988. In this way, the development of the vegetation under three different levels of shading could be studied, together with its recovery after different periods of shading.

A germination experiment was done with tubers of Potamogeton pectinatus L. originating from Californian (U.S.A.) irrigation canals. After 14 days it was found that: (a) the tubers germinated readily upon detachment from the mother plant, so no innate dormancy was present; (b) when the tubers remained attached to the mother rhizome, however, no germination was observed; (c) larger tubers germinated earlier than smaller ones; and (d) the proportion of a clutch from one motherplant that germinated after detachment was larger for larger clutches.

The effect of temperature and light on the growth of Potamogeton pectinatus L. was investigated in a laboratory experiment with three temperatures (13, 15 and 22 °C) and four irradiance treatments (dark, 50, 100 and 200 μE m−2 s−1). The experiment lasted two months. The plants were sprouted from a standard tuber size class (100–200 mg fresh weight) from one population, originating from a brackish ditch on’the island of Texel, The Netherlands.

Germinating tubers of the aquatic monocot P. pectinatus are shown to possess several unusual characteristics. Their rate of stem extension can be promoted by strictly anaerobic solutions, an effect sustained for several days. This leads to a stem several centimetres longer than that formed under aerated conditions. This appears to be the first report of such a phenomenon. Some cell production continues under anaerobic conditions as judged by cell counts of epidermal strips, and by the relative increases in length by cells and internodes. Stem extension is also promoted by solutions that are partially deficient in oxygen (5–8 kPa oxygen). The effect cannot be attributed to ethylene action, since applications of the gas fail to promote stem elongation, although leaf extension is stimulated. Ethylene production by germinating tubers is extremely small, even in the presence of oxygen. Production of ethylene is affected only slightly by treatment with aminoethoxyvinylglycine (AVG), an inhibitor of ethylene biosynthesis in many higher plants, or by additions of 1-aminocyclopropane-l-carboxylic acid (ACC), the putative precursor of ethylene. The low activity of ACC and AVG suggests that the conventional pathway of ethylene production from methionine, via S-adenosylmethionine and ACC, is suppressed in this species.

Lipopolysaccharides (LPS) from the type strains of the anaerobic beer spoilage bacteria Pectinatus cerevisiiphilus and P. frisingensis were extracted with the 5:5:8 volume ratio modification of the phenolchloroform-petroleum ether method (H. Brade and C. Galanos, Eur. J. Biochem. 122:233-237, 1982). Sequential precipitations of LPS with water and acetone from the phenol phase yielded LPS which differed in that water-precipitable material (LPS-H2O; 0.1 to 0.4% of the dry weight of the cells) was rough-type LPS, whereas acetone-precipitable material (LPS-Ac; 4.6 to 5.8% of the dry weight) contained both rough-type LPS and high-molecular-weight material resembling smooth LPS. The LPS were chemically characterized, and they contained D-glucosamine, 4-amino-4-deoxy-L-arabinose, 3-deoxy-D-manno-2-octulosonic acid, D-fucose, D-galactose, D-glucose, D-mannose, and phosphate. D-Fucose was present mostly in LPS-Ac, suggesting that it is a constituent of the O antigen. The major fatty acids were ester- and amide-linked (R)-3-hydroxytridecanoic and ester-linked undecanoic acids, with minor amounts of ester-linked tridecanoic and (R)-3-hydroxyundecanoic acids. The chemical compositions of LPS-H2O and LPS-Ac suggested that they differ not only in their smooth or rough nature but also in the structure of their core regions. This may explain their different precipitabilities from the extraction mixture. The extraction method was also shown to be applicable to the isolation of smooth-type LPS from Salmonella enterica serovar Typhimurium. Extraction of two Typhimurium strains carrying chemically different O antigens resulted in high yields (8% of the dry weight) of LPS. Strain SH2183, which contains the relatively hydrophobic O-4,5,12 antigen yielded almost exclusively LPS-Ac, whereas the LPS of strain SH5770, which has a hydrophilic O-6,7 antigen, was exclusively LPS-H2O. No fractionation to smooth and rough LPS occurred with the Typhimurium strains.

Movements of the cephalic appendages of nauplii (stages 3 and 4), copepodites (stage 4) and adult female Drepanopus pectinatus were investigated using a computerized micro-impedance unit. Direct measurements and visual observations of the behaviour of restrained copepods were made in the presence of filtered seawater, naturally occurring phytoplankton of different sizes, prefiltered extracts of phytoplankton and seston. The normal appendage movements recorded in filtered seawater were similar for adult females and copepodites. Traces for nauplii were different compared with those of the two other developmental stages. Appendage movements were modified when adult females were offered particles of different sizes and extracts of phytoplankton, showing significant changes in the frequency of the limb beats in relation to each stimulus. Impedance traces distinguished between activity of copepod appendages related to feeding and to swimming such as: flicking, stroking, jerking, combing, handling and rejecting particles. Prolonged recordings of restrained females in association with visual observations suggested that the activity of the mandibular palp was related to gut fullness and peristaltic movements, and to fecal pellet formation and evacuation. These results indicated that D. pectinatus is an intermittent beater responding to the physical and chemical characteristics of food.

Potamogeton pectinatus is a submerged halophyte which occurs in waters of low salinity (5% to 10%). Its upper salinity tolerance has been reported to be 19%. Reasons why P.pectinatus is unable to tolerate salinities in excess of 19%is important to our understanding of its biology. In the present study, leaf ultrastructure of plants growing at low salinity was compared with plants growing at high salinity in order to assess the effects of different salinities on the ultrastructure. Attention was focussed on ultrastructural changes occurring in the leaf epidermis, the main photosynthetic tissue.Plants were grown in seawater at two salinities : 5%(low salinity) and 20% (high salinity). Pieces of mature leaf blades from both treatments were harvested and prepared for Transmission Electron Microscopy (TEM) following standard procedures. The overall distribution and concentration of chlorine (CI) in the leaves was ascertained since this element is the most abundant anion in seawater and is important in considerations of salt tolerance in submerged halophytes.

On the basis of 16S rRNA gene sequence analysis and several key phenotypic features, it was ascertained that the cultures cited as the type strain of the species Pectinatus portalensis, CECT 5841(T) and LMG 22865(T), do not conform to the description, [Gonzalez, J. M., Jurado, V., Laiz, L., Zimmerman, J., Hermosin, B.Saiz-Jimenez, C. (2004). Antonie van Leeuwenhoek 86, 241-248]. The type strain does not exist in any other established culture collection or with the authors who described this species. Therefore, it cannot be included in any scientific study. It is proposed that the Judicial Commission place the name Pectinatus portalensis on the list of rejected names if a suitable replacement type strain is not found or a neotype is not proposed within two years following the publication of this Request for an Opinion.

Euryops pectinatus Cass. is an evergreen shrub that is planted extensively in Spain for landscape use. In 2007, powdery mildew outbreaks were observed on E. pectinatus in several nurseries located in the Axarquia area (Malaga, southern Spain). Fungal growth appeared as typical, white, powdery mildew colonies that were restricted to upper leaf surfaces. Initially, individual colonies were small and nearly circular, but later enlarged and coalesced to cover the whole leaf surface. With progress of the disease, all green parts (leaves, stems, and petioles) were covered with a white mycelium. Newly developed leaves especially became rapidly infected. Diseased leaves ultimately dried up and senesced, making nursery plants aesthetically unattractive and unsaleable. Conidiophores were erect, had crenate edge lines, cylindrical foot cells that measured 37.5 to 45.0 × 10.0 to 12.5 μm, and were followed by one to three shorter cells. Conidia were hyaline, ellipsoid to ovoid, borne in chains, and measured 27.5 to 35.0 × 12.5 to 17.5 μm. Conidial length-to-width ratios ranged from 1.6 to 2.4. Conidia possessed conspicuous fibrosin bodies and from their sides produced short germ tubes. No chasmothecia were found. The nuclear rDNA internal transcribed spacer (ITS) regions were amplified by PCR and sequenced (GenBank Accession No. EU424056). On the basis of morphological characteristics of the imperfect state and ITS sequence data, this powdery mildew was identified as Podosphaera fusca (Fr.) U. Braun & N. Shishkoff (1), this isolate belonging to ITS haplotype 15 (group III) (3); this group is considered a separate species, P. xanthii (Castagne) U. Braun & N. Shishkoff by some authors (2). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of healthy E. pectinatus plants. Plants were incubated in a growth chamber at 25°C, and after 14 days, powdery mildew colonies developed. A similar disease of E. pectinatus was observed in 1999 in California (4). P. fusca parasitizes a large number of asteraceous species including field marigold (Calendula arvensis) and fleabane (Erigeron sp.) weeds, as previously reported in the same area, and ornamentals such as Calendula officinalis, Chrysanthemum spp., and Gerbera spp., which are also grown in the same nurseries and frequently attacked by powdery mildew. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) U. Braun et al. Schlechtendalia 7:45, 2001. (3) T. Hirata et al. Can. J. Bot. 78:1521, 2000. (4) G. S. Saenz et al. Plant Dis. 84:1048, 2000.

A collection of 47 strains of obligately anaerobic, gram-negative, rod-shaped bacteria that were isolated mainly from spoiled beer and pitching yeast was studied to learn more about their taxonomic positions. A new species of the genus Pectinatus, Pectinatus frisingensis, a new species of the genus Selenomonas, Selenomonas lacticifex, and a new genus comprising two species, Zymophilus raffinosivorans and Zymophilus paucivorans, are described. All of the strains contained directly cross-linked meso-diaminopimelic acid-containing peptidoglycan and in addition the diamine cadaverine or (rarely) putrescine. The diamine was covalently linked to the alpha-carboxyl group of D-glutamic acid in the peptide subunit of peptidoglycan. Lipid F was also found as a characteristic cellular compound. The phylogenetic relationships of members of these new species were examined by reverse transcriptase sequencing of 16S rRNA or by DNA-DNA hybridization studies or both. All of the organisms belong to the subdivision containing species with gram-negative cell walls within the phylum of gram-positive bacteria. This finding is in good agreement with the presence of a peptidoglycan that contains diamine.

Yumenia Hong, 1982 preoccupied by Yumenia Hou, 1958, is replaced with Gansucossus (Hemiptera, Palaeontinidae). The diagnostic characters for Gansucossus are presented and synonymies for Gansucossus pectinatus (Hong, 1982) and Gansucossus luanpingensis (Hong, 1983) are established. The diagnostic characters for G. pectinatus and G. luanpingensis are revised. A new species, Gansucossus typicus sp. nov., is described from the Middle Jurassic of Daohugou, Inner Mongolia, China. The new genus Daohugoucossus gen. nov. and new species Daohugoucossus solutus sp. nov., are erected based on a hind wing from the Middle Jurassic of Daohugou.

The water-distilled essential oil of Thymus pectinatus Fisch. et Mey. var. pectinatus was studied by GC/MS. Fifty-six compounds representing 96.14% of the oil were characterized. Major constituents of the oil were thymol (35%), borneol (17.70%) and p-cymene (11.12%).

Gray-leaved Euryops (Euryops pectinatus Cass., Asteraceae) is an evergreen shrub that is widely planted in landscapes in the United States. In the fall of 1999, powdery mildew was observed on E. pectinatus planted in landscapes in Redlands (San Bernardino County), CA. Symptoms consisted only of slight cupping of leaves. Fungal growth was observed on stems, leaves, petioles, and pedicels and was ectophytic and amphigenous. The white mycelium was patchy to effuse. Hyphal appressoria were indistinct (1). Conidiophore foot cells were cylindric and sometimes were tapered toward or constricted at the base. Foot cells measured 30 to 50 by 10 to 12 μm and were followed by one to two shorter cells. Conidia were cylindric to slightly doliform, borne in chains of two to three, and measured 26 to 38 by 14 to 18 μm. Conidial length to width ratios ranged from 1.7 to 2.4. Catenate conidia had crenate edge lines (3). Conidia possessed conspicuous fibrosin bodies and from their sides produced short germ tubes without appressoria. Cleistothecia were not observed. Based on these characters, the fungus was identified as Podosphaera fusca (Fr.) U. Braun & N. Shishkoff (Podosphaera sect. Sphaerotheca) (1,2). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of healthy E. pectinatus plants. Plants were incubated in a humidity chamber at 22 to 24°C and after 12 to 14 days powdery mildew colonies developed. E. pectinatus cv. Viridis, a cultivar that lacks the extensive pubescence of E. pectinatus, also developed disease when inoculated. This appears to be the first report of powdery mildew on E. pectinatus in North America. A voucher specimen has been deposited into the University of California Herbarium (accession # UC1738635). P. fusca was also observed on cv. Viridis in a nursery in New York in 1999. It is unclear where this pathogen originated. P. fusca parasitizes a large number of asteraceous species including dandelion (Taraxacum officinalis) and sowthistle (Sonchus spp.) weeds, which occur in the area and sometimes are infected with powdery mildew. The Euryops powdery mildew pathogen may be a race that is different than those found on other composites in the United States. The fungus was observed on plants in shaded areas but not on plants in full sun. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (3) H. D. Shin and Y. J. La. Mycotaxon 46:445, 1993.

The impact of waterfowl herbivory on the macrophyte Potamogeton pectinatus was tested at six shallow sites adjacent to Asko island, in the northern Baltic proper. Protection by means of floating nets affected P. pectinatus at the three most sheltered sites but had no influence on the more wave-exposed sites. Ramet density in July of the first study year was 10-23 times higher in protected plots than in unprotected plots, at the sheltered sites. The density at two of the sites was constantly low in unprotected plots and remained much higher (10-80 times) in the protected plots throughout the 3-year study. At the third very sheltered site the impact of waterfowl was more variable. Additional studies of permanent plots and pot experiments revealed that waterfowl mainly suppressed P. pectinatus, not by grazing on shoots, but by eating subterranean tubers between late April and early June. This study suggests that waterfowl herbivory can constrain submerged macrophyte populations in shallow sheltered areas.

Plants of Potamogeton pectinatus L., growing rapidly from small tubers in the dark or from 12-week-old light-grown plants, contained high concentrations of the ethylene precursor 1-amino-cyclopropane- 1-carboxylic acid (ACC) (4.8 – 25.6 nmol g-1 fresh weight). However, ethylene (ethene) production was either completely absent or too small to raise concentrations significantly above background when measured by flame ionization gas chromatography sensitive to

Potamogeton subg. Coleogeton is el- evated to generic level. A combination of morpho- logical and anatomical features readily distin- guishes the new genus Coleogeton from both Groenlandia and Potamogeton, the two other gen- era recognized in the Potamogetonaceae. All new combinations for taxa that occur in North America are proposed for use in the Flora of North Amer- ica. These new combinations include Coleogeton striatus, C. pectinatus, C. filiformis, C. filiformis subsp. alpinus, C. filformis subsp. occidentalis, and C. vaginatus.

Clonal lines of the submersed aquatic angiospermPotamogeton pectinatus were grown in three culture systems. The first, which used sucrose as a carbon source in a liquid medium, supported vigorous vegetative growth and can be used to propagate large numbers of plants in axenic conditions. In this culture system, plants were responsive to increasings photosynthetically active radiation (PAR) photon flux density (PFD) and were photosynthetically competent. However, their growth was heterotrophic and root development was poor. When these plants were transferred to a second nonaxenic culture system, which used 16-1 buckets containing artificial sediments and tap water, growth was autotrophic and plants were morphologically identical to field-harvestedP. pectinatus. The last culture system which consisted of a sand substrate and inorganic nutrient bathing solution aerated with 135 ml min−1 ambient air enhanced to 3.0% CO2 was axenic and supported autotrophic growth by plants that were also morphologically normal.

Cells were isolated by enzymic digestion from a number of aquatic macrophytes and their photosynthetic activities were determined. Eichhornia crassipes (Mart.) Solms, Myriophyllum spicatum L. and M. brasiliense Cambess provided photosynthetically-active cells after digestion with commercial pectinase. Cells from emergent leaves of M. brasiliense were approximately 3 times more active than cells from submersed leaves (56.1 vs. 17.4 μmoles CO2 mg−2 Chl h−1). Cells could be isolated from E. crassipes by grinding as well as by digestion, but the former were less active (3.1 vs. 24.2 μmoles CO2 mg Chl h−1). Attempts to isolate cells from Hydrilla verticillata (L.f.) Royle or Potamogeton pectinatus L. were not successful.

The occurrence of Tosia parva (Perrier, 1881), Marginaster pectinatus Perrier, 1884 and Ldbidiaster radiosus Liltken, 1871 in the South Atlantic region is registered for the first time. The new varieties, Phrixometra longispina brasiliensis var. n., and Holothuria (Vaneyothuria) lentiginosa brasiliensis var. n., are de scribed. The genus Calliophidiaster Tommasi, 1970 is redescribed and its differences with Linckia Nardo, 1934, are reinforced. Ophiomyxa vivipara Studer, 1886 and Ophiura fallax Cherbonnier, 1959 are de scribed for the first time from Brazil. Amphiura iraciae sp. n. and A. rosae sp. n. are described.

Data on germination of tubers and subsequent growth of young plants of Potamogeton pectinatus were recorded at different depths of the water column in Lake Nainital. The depth of euphotic zone is about 5 m. Tubers were placed at 1, 2.5, 5.0, 7.5 and 10 m water depth in brass net bags. A highly significant negative correlation was found between depth on one hand and germination percentage of tubers, length of shoots and number of leaves on the other hand. Germination of tubers was positively related to pH, dissolved oxygen and temperature of water.

Summary Ranunuculus aquatilis, Ranunclus fluitans, Elodea canadensis, Potamogeton pectinatus, Potamogeton natans and Zannichellia palustris were collected from homogenous populations in their natural environment. 1. Fewer amino acid components were detected than usually found in plants with the described automatic method. 2. The absolute amounts of single components were equal to and — in some cases — even higher than in terrestrial plants. 3. Particularly high amounts of asparagine were found in Elodea canadensis and Zannichellia palustris . 4. Total amino acid content was lowest in Potamogeton pectinatus and Potamogeton natans but highest in Elodea canadensis . 5. Asparagine- and glutamine-types could be distinguished. Both Ranunculus -species were of the glutamine-type, all the Monocotyledons covered by this study were of the asparagine-type. 6. Elodea canadensis showed increased asparagine content under enhanced eutrophication, though there was no increase in nitrate content detectable.

Se reconocen nueve especies de Potamogeton para México en contra de 28 nombres registrados en fuentes bibliográficas. Potamogeton pectinatus L., P. crispus L., P. foliosus Raf. var. foliosus, P. pusillus L. var. pusillus, P. diversifolius Raf., P. nodosus Poiret, P. natans L., P. illinoensis Morong y P. praelongus Wulfen se describen con base en su variación regional. Se incluye sinonimia, mapas de distribución, ejemplares de referencia, dibujos de sus caracteres diagnósticos, clave dicotómica, e índice de nombres científicos.

The productivity of Potamogeton Richardsonii, P. pectinatus, Myriophyllum alterniflorum, Megalodonta Beckii, and Chara vulgaris in West Blue Lake, Manitoba, is reported. Measurements of changes in biomass and assimilation of 14CO2 in random and non-random samples throughout the growing season of 1973 were used. Changes in biomass of P. Richardsonii, M. alterniflorum, M. Beckii, and C. vulgaris determined from random samples compared favourably with those determined from non-random samples. This was not the case for P. pectinatus because of its restricted occurrence. Similarly, measurements of 14CO2 assimilation in random samples of P. Richardsonii, M. alterniflorum, and M. Beckii compared well with non-random samples. Productivity values derived from 14CO2 uptake were far in excess of those attained from biomass changes. Seasonal trends of production and the depth distribution of production are discussed, and macrophyte production is compared with phytoplankton production.

The growth of Potamogeton pectinatus L. at different concentrations of bicarbonate, phosphate and nitrate was studied during long-term culture experiments in aquaria. The uptake of bicarbonate, phosphate, nitrate and ammonium by the shoots or the root system was studied during short-term experiments in 2-compartment chambers. When P. pectinatus was cultured without a phosphorus source, the tubers were able to supply phosphorus and enable growth for about 5 weeks before the plants died. Depletion of nitrate or dissolved inorganic carbon (DIC) caused a rapid death of plants. Potamogeton pectinatus takes up phosphorus and nitrogen with the shoots and the root system, bicarbonate can only be taken up by the shoots. The nutrient contents of plants indicated luxury consumption of phosphorus at high external phosphate concentrations. Critical phosphorus concentrations for plant growth according to biomass production in cultures at different external phosphate concentrations are supposed to be between 1.5 and 14 μmol 1 −1 phosphate. Analysis of plant tissue shows that the critical phosphorus content is 0.15%, which corresponds with a stock phosphate concentration between 3 and 4 μmol PO 4 3− l −1 . It is argued that phosphate and nitrate are probably not limiting growth of P. pectinatus in the Veluwemeer study site (The Netherlands), but DIC might well be.

Until recently, gram-negative bacteria have not been considered to be common spoilers of finished (packaged) beer. In this article, however, two gram-negative, obligately anaerobic, beer spoilers o...

The translocation of lead and copper was studied in two species of submerged aquatic angiosperm, Potamogeton crispas L. and Potamogeton pectinatus L. A perspex container incorporating a potters' clay seal around the stems of intact plants was designed for the chemical separation of the shoot and root environments during 11-21 d treatment periods. Metal solutions were added to the root or shoot environments and concentrations were monitored in waters and sediments. A technique was developed for the direct quantitative analysis of metals in small (0-02-0-2 mg) segments of water plant tissue, using the graphite rod attachment to an atomic absorption spectro photometer. Experimental results indicated minimal translocation of lead, but extensive acropetal translocation of copper to particular sites of accumulation.

Six new ent -labdanes were isolated from the aerial parts of Gutierrezia species and nine from Happlopappus pectinatus . Four neoclerodanes and a friedolabdane were obtained from the aerial parts of Haplopappus paucidentatus . From the Grindelia species, in addition to known derivatives of grindelic acid, an arabinoside was isolated. The absolute configuration of the ent -labdanes was determined by transformation of grindelic acid to methyl-6-oxo-7,8-dihydrogrindelate where the configuration was established by the positive Cotton effect. From Solidago petradoria a new abietane derivative was isolated.

This third paper on the ecology of Potamogeton pectinatus L. deals with the reproductive strategies of different populations of this species. The various ways of propagation and survival, both generative and vegetative, are described. Attention is also given to the germination ecology of achenes and tubers. Flowering and achene production have been observed in most populations studied and the process of fructification is described in detail. Inflorescences of P. pectinatus are surface pollinated and the pollen is hydrophobous. The formation of seed banks by populations appears to be largely dependent on the degree of shelter in the habitats, the number of achenes produced seems to be less important. The results of the germination experiments with achenes support the field observations, indicating that achenes are relatively unimportant in the shory-term survival of populations. The main function of these generative propagules is most likely the dispersal of the species and the long-term survival. Potamogeton pectinatus shows several types of vegetative propagation. Subterranean tubers are the most common and most important propagules. Temperature and stratification appear to be major factors regulating the germination of tubers. The reproduction of P. pectinatus is discussed in relation to the life cycle and survival strategy of the populations.

Summary Samples of Potamogeton pectinatus were taken from its natural habitat from differently eutrophic sites. With increasing eutrophication there was a decrease in starch, hexoses, chloride, sodium, potassium, and malic acid, sucrose, several amino acids, PO 4 -P, and NO 3 -N levels increased. Raised sucrose contents could serve as a biological indicator for enhanced eutrophication; some explanations for other findings are discussed.

Epiphyton samples same taken from different macrophyte species (three chararaceans Potamogeton pectinatus L.). While some epiphyton taxa were evenly distributed, the density of others differed according to plant part, site or macrophyte species. Diatoms were classified according to host plant species by cluster analysis. Thus, the neutral substrate hypothesis is revised. Differences in epiphyton composition were larger between the closely related species Chara tomentosa L. and C. globularis Thuill. than between Chara tomentosa and Nitellopsis obtusa (Desv.) J. Groves. The latter two species were heavily marl-encrusted. Potamogeton pectinatus was separated from the other macrophyte species by its lower total density of epiphyton and the high abundance of Cocconeis placentula Ehr.

Fourteen species of sergestid shrimps were collected in the Sargasso Sea between the surface and 1500 m near Bermuda on 4 cruises. The vertical distribution and feeding activity of the most abundant species are discussed in relation to interspecific competition and the adaptive significance of vertical migration. Each species lives within a narrow depth range and exhibits a diel vertical migration. Sergestes splendens migrated as much as 825 m, while S. japonicus migrated less than 100 m. Neither the seasonal nor permanent thermocline influenced the migration range. The only species which occurred together both day and night were S. pectinatus with S. vigilax and S. pectinatus with S. sargassi. Morphological differences in the third maxillipeds of these species suggest differences in feeding. Although most species eat a variety of organisms, the foreguts of S. grandis, S. corniculum, and S. splendens contained euphausiids more often than those of other species, and S. grandis and S. robustus fed more frequently on fishes. In contrast, S. japonicus appears to feed on detritus. Food was found in the foreguts of most species less frequently during the day than night, but no species fed only at night. S. sargassi and S. pectinatus fed equally day and night.

Eleven Pectinatus cerevisiophilus strains of brewery origin were classified serologically by gel diffusion precipitin tests, immunoelectrophoresis, and the fluorescent antibody staining technique. The Pectinatus strains could be assigned immunologically to three different groups. Groups I and III were found to be very closely related, and only some of the antisera used showed differences. The antisera against the strains belonging to group II contained a common group antigen. A strong precipitation band found near the antigen was shown to represent the interaction of the lipopolysaccharide antibody and the respective antigen.

When recently germinated Potamogeton pectinatus L. tubers were grown at temperatures ranging from 10 to 37°C under low irradiances (6–120 μE m −1 s −1 ), temperature exerted a stronger influence on levels of the pigments chlorophyll a and chlorophyll b than did irradiance. Temperature and irradiance interacted to influence the level of total carotenoids. At low irradiances, changes in temperature modified the concentrations of accessory pigments relative to chlorophyll a . Two indicators of growth were also strongly affected by temperature. The relative rate of shoot elongation varied from −0.04 to 1.23 mm cm −1 day −1 . At 23–30°C, the relative shoot elongation rate was inversely related to irradiance, but at temperatures outside this range irradiance had no influence on the relative shoot elongation rate. The relative leaf production rate varied from 0 to 0.28 leaves leaf −1 day −1 and increased with temperature and irradiance. No leaves were produced at 37°C. These results indicate that the optimum temperature for early growth of P. pectinatus is near 23–30°C, and that, during the early growth period, temperature may be as important as irradiance in influencing growth of P. pectinatus .

Summary The translocation of phosphorus as 32P was investigated in two species of rooted, submerged, aquatic angiosperm, Potamogeton pectinatus and Potamogeton crispus. Experiments were conducted in two forms of partition apparatus for periods of either 1 to 48 h or 6 to 10 days. The apparatus used for the shorter-term experiments incorporated three compartments so that possible isotope leakage through seals could be critically distinguished from plant excretion. Results of autoradiography and of radioactive counting provide evidence for a circulation of 32P in these plants akin to that described for terrestrial plants but with slower rates of movement. Quantitative differences in rates and amounts of 2P transport in the two species are discussed in relation to their anatomy and ecological distribution. There was no evidence of excretion of isotope, following transport, in the experiments conducted.