Nutrient proportions in foliage of semi-mature loblolly pine

Summary Nitrogen and phosphorus limitations to growth are common in many loblolly pine (Pinus taeda) stands. Interactions of these nutrients may complicate interpretation of foliar nutrient analysis for predicting response to forest fertilization. Proportions of foliar nutrient concentrations (and the changes in these proportions following fertilization) were examined in 36 semi-mature loblolly pine plantations in the southeastern United States. Mean proportions of nutrient concentrations (NPKCaMg) for non-fertilized stands were 1009.336.517.29.2. Potassium and phosphorus were higher. Nitrogen fertilization generally decreased the PN ratio and enhanced growth, indicating a nitrogen deficiency in most stands under study. Additions of nitrogen and phosphorus together yielded a significant increase in the PN ratio. Effects of fertilization effects on other nutrient concentration ratios were also examined.Paper No. 9401 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695.     

O-Glycosylhydrolases of Marine Filamentous Fungi: β-1,3-Glucanases of Trichoderma aureviride

The ability to produce extracellular O-glycosylhydrolases was studied in 14 strains of marine filamentous fungi sampled from the bottom sediments of the South China Sea. The following activities were detected in the culture liquids of the fungi: N-acetyl--D-glucosaminidase, -D-glucosidase, -D-galactosidase, -1,3-glucanase, amylase, and pustulanase. -1,3-Glucanases were isolated by ultrafiltration, hydrophobic interaction chromatography, and ion exchange chromatography, and their properties were studied. Data on products of enzymatic digestion of laminaran, absence of transglycosylation activity, and the pattern of action of natural inhibitors confirmed that -1,3-glucanase belonged to the exo type. Inhibitor analysis demonstrated the role of a thiol group and tryptophan and tyrosine residues in the catalytic activity.     

Elongation factor 1α genes of the red alga Porphyra purpurea include a novel, developmentally specialized variant

The life cycle of the red alga Porphyra purpurea alternates between two morphologically distinct phases: a shell-boring, filamentous sporophyte and a free-living, foliose gametophyte. From a subtracted cDNA library enriched for sporophyte-specific sequences, we isolated a cDNA encoding an unusual elongation factor 1 (EF-1) that is expressed only in the sporophyte. A second EF-1 gene that is expressed equally in the sporophyte and the gametophyte was isolated from a genomic library. These are the only EF-1 genes detectable in P. purpurea. The constitutively expressed gene encodes and EF-1 very similar to those of most eukaryotes. However, the sporophyte-specific EF-1 is one of the most divergent yet described, with nine insertions or deletions ranging in size from 1 to 26 amino acids. This is the first report of a developmental stage-specific EF-1 outside of the animal kingdom and suggests a fundamental role for EF-1 in the developmental process.     

Phosphorus concentration in sediment, water and tissues of␣three submerged macrophytes of Myall Lake, Australia

Phosphorus content in sediment, water and tissues of three macrophyte species growing in Myall Lake, Australia were studied from January to November, 2004. The sites investigated were North–West (NW), North–East (NE), South–West (SW) bays and Central deep area of the lake (CL). The objective of this study was to investigate how total phosphorus (TP) in plant tissues relate to phosphorus pools and the role played by the aquatic macrophyte species under investigation in phosphorus recycling in the lake. Of the four investigated sites of the lake, TP in plant tissues were significantly higher in North–West and South–West bays compared to the rest. Najas marina had significantly higher TP content (e.g., 1.55 and 1.44 mg/g dw.; P < 0.05) for NW and SW respectively, than the other two species. N. marina is a rooted macrophyte while charophytes (C. fibrosa and Nitella hyalina) are pseudo-rooted macrophytes. Total phosphorus in the sediment and water column were significantly higher in Central deep area of the lake compared to the other three bays (P < 0.05, n 5). Soluble reactive phosphorus (SRP) and total dissolved phosphorus (TDP) in sediment pore water correlated significantly with phosphorus content in the tissue of N. marina ( ; ) as well as TP in sediment (␣ and ). Using the two-compartmental uptake model, it was observed that, sediment was the main compartment through which Ni. hyalina obtained phosphorus while for the other two species, water column was the uptake route for the phosphorus. These correlations suggest that, water column and sediments are important pathways for phosphorus uptake in plants.     

Ultrastructural analysis of the sperm cells of mature pollen of maize,Zea mays

Summary Ultrastructural analysis of the mature viable unhydrated pollen of maize,Zea mays from dehiscent anthers shows that the sperm cells are physically distant, each bounded by an envelope comprising their own plasma membrane and the inner plasma membrane of the vegetative cell. The chondriome is unusual in containing one or more filamentous complexes, up to 12m in length appressed to the side of the sperm nucleus. The extensions at each end of the elongate sperm cells contain longitudinally-oriented arrays of endoplasmic lamellae. In a three-dimensional reconstruction of serial thin sections, there is a long J-shaped sperm, c. 35 × 5m and up to 1m in thickness, sited within pointed evaginations of the vegetative nucleus and a second shorter sperm c. 20 × 5m and up to 3.5m in thickness.Abbreviations PA-TCH-SP periodic acid-thiocarbohydrazide-silver proteinate - DAPI 4,6-diamino-2-phenylindole - SC sperm cell - Sn sperm nucleus - Ua-Pb Uranyl acetate-lead citrate staining - ER endoplasmic reticulum     

Seasonal succession of phytoplankton in a lake of the Paraná river floodplain,Argentina

Phytoplankton biomass, morphological and taxonomic composition, species diversity and productivity were analyzed in a shallow lake of the Middle Paraná River floodplain (El Tigre, 31 ° 41 S and 60° 42 W), between November 1986 and July 1988. Lake inundation (filling and through-flow phases) constituted an intense long-term perturbation in the physical and chemical environment. As the lake filled with river water, K-selected species (netplanktonic filamentous bluegreens, > 37 µm, with low surface area/volume (SA/V) ratios) that had existed prior to filling (late spring 1986) were replaced in summer-fall by r-selected species (nannoplanktonic chlorophytes and cryptophytes, < 37 µm, mainly stout forms with high SA/V ratios). During the through-flow phase, lentic phytoplankton was replaced by lotic flagellate populations due to the direct flushing by river water. During the period of falling water (drainage and isolation phases), nanoplanktonic algae with similar characteristics to those of the filling phase dominated in late winter-spring. Later in the isolation phase, these were succeeded by K-selected species (netplanktonic algae, mainly motile spherical dinoflagellates and filamentous bluegreens with low SA/V ratios). Simultaneously, primary production per unit biomass decreased and total biomass and specific diversity increased. Seasonal changes of phytoplankton in floodplain lakes can be interpreted as the interaction between true successional development (as observed in the drainage and isolation phases) and intermediate disturbance. Using Reynolds' terminology, short-term disturbance (slight inflow of nutrient-rich river water) caused reversion to an earlier stage in the former succession, and long-term disturbance (lake inundation) truncated the successional progression and a new (or shifted) succession was initiated.     

Construction of stable lactose-utilizing Xanthomonas campestris by chromosomal integration of cloned lac genes using filamentous phage ϕLf DNA

Summary Previously, we constructed a lactose-utilizing strain of Xanthomonas campestris, Xc17 (pKMLT), by cloning lacZY genes with the RK2-derived vector pLAFR1. In this study, the narrow-host-range, -galactosidase expression plasmid pKM was fused with an integration vector pS19 to form pSF14. Following insertion into Xc17, pSF14 was integrated into the host chromosome. The integration function was provided by the 0.85-kb EcoRI-PstI fragment from the filamentous phage Lf. The integration caused no adverse effect to the cells and was stable for at least 66 generations without selection. The engineered strain, Xc17::pSF14, was able to grow as well and produce as much xanthan gum in lactose medium as the wild-type cells did in glucose medium, and the Xc17(pKMLT) in lactose medium. Therefore, Xc17::pSF14 is potentially useful for xanthan production by direct use of whey lactose as the fermentation substrate. This study has advanced one more step our efforts to contruct lactose-utilizing X. campestris and confirmed the feasibility of using pS19 as an integration vector.     

Quantitative Bestimmung der Fettsäuren von Rhodospirillum rubrum und Rhodopseudomonas capsulata während der Thylakoidmorphogenese

Zusammenfassung Eine Methode zur quantitativen Bestimmung des Fettsäuregehaltes im Mikrogrammbereich wird angegeben und auf Spezifität untersucht. Thylakoide aus Rhodospirillum rubrum und Rhodopseudomonas capsulata enthalten 330 bzw. 350 g Fettsäuren/mg Protein und 16,1 bzw. 15,4 g Lipid-Phosphor/mg Protein. In aeroben Dunkelkulturen beider Organismen werden 100–120 g Fettsäuren und 3,0–4,3 g Lipid-Phosphor pro mg Protein gefunden. In Thylakoiden sind 15–20%, in ganzen Zellen 25–45% der Fettsäuren nicht in Phospholipiden vom Glycerintyp gebunden.Wird die Thylakoidsynthese durch Absenken des O₂-Partialdruckes induziert, steigt der Fettsäuregehalt um 30%, der Lipid-Phosphor-Gehalt um 40% an. Elektronenmikroskopische Aufnahmen lassen jedoch auf eine Verdopplung bis Verdreifachung des Gehaltes an Membranen schließen. Dieser Widerspruch wird mit der Annahme erklärt, daß Phospholipide in gramnegativen Bakterien nicht nur in Membranen, sondern auch in der Zellwand lokalisiert sind. Der Wert der Bestimmung des Lipid-Phosphor in ganzen Zellen gramnegativer Bakterien als Maß für den Membrangehalt wird diskutiert.

---

Quantitative determinations of long-chain fatty acids in dark growing cells of Rhodospirillum rubrum and rhodopseudomonas capsulata during the synthesis of thylakoids

Summary The content of fatty acids in the thylakoids of Rhodospirillum rubrum and Rps. capsulata is 330 g and 350 g/mg protein, respectively, and the content of lipidphosphorus 16.1 and 15.4 g/mg protein, respectively. In aerobic dark cultures of both organisms 100 to 120 g fatty acids and 3.0 to 4.3 g lipid phosphorus per mg protein are demonstrable. 15 to 20% of fatty acids in thylakoids and 25 to 45% of fatty acids in whole cells are not bound to glycerol phosphatides. After induction of thylakoid synthesis by lowering of oxygen partial pressure the specific content of fatty acids is increased by 30% and the concentration of lipid phosphorus by 40%. Under the same conditions a two or threefold increase of membrane surface as evaluated from electron micrographs is observable. This pronounced difference is explainable by the assumption, that phospholipids in gram-negative bacteria are not only localized in membranes, but also in the cell wall. The validity of determinations of lipid phosphorus in whole cells of gram-negative bacteria as a measure for membrane content is discussed.

     

Seasonal change of seston size distribution and phytoplankton composition in bivalve pearl oyster Pinctada fucata martensii culture farm

Seasonal changes of seston were monitored in the pearl cultivation area of Uchiumi Bay, Ehime Prefecture, Japan where the pearl oyster Pinctada fucata martensii is cultivated. The concentrations of chlorophyll a and particulate carbon, nitrogen and phosphorus were measured and the community structure of the phytoplankton investigated between June 1997 and February 1999. The seston was divided into pico- (<2 m), nano- (2–20 m) and large (>20 m) size fractions. The dominant size fraction during the study period, <2 m (38.1–51.4%), is consumed by oyster larvae but is too small for the adult pearl oyster. During the summers of 1997 and 1998 Nitzschia spp. became dominant but is indigestible for the oyster which was thus subjected to food limitation. We suggest monitoring the composition of seston and phytoplankton >2 m for evaluation of the food environment of the pearl oyster.     

Evaluation of laboratory indexes of absorption of soil phosphorus by plants: II

Summary A comparison was made of several laboratory methods for estimating the yield of phosphorus in plants grown in greenhouse cultures on samples of 22 soils from different parts of the United States. The methods investigated and their rank in order of increasing precision of the estimates of the yield of phosphorus were as follows: extraction with lactic acid, calcium lactate buffer solution extraction with 2 per cent citric acid solution < extraction with 0.03N NH₄F, 0.025N HCl solution < percentage phosphorus saturation (found as follows: 100 × labile phosphorus by isotopic dilution/ phosphorus adsorption capacity according to Langmuir adsorption equation) labile phosphorus by isotopic dilution phosphorus extracted by water.Journal Paper No. J-3747 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1183. Contribution from the Department of Agronomy.     

Mutants of carotene production in Blakeslea trispora

The filamentous fungus Blakeslea trispora, an industrial carotene source, contains -carotene and precursors of its synthesis — phytoene, phytofluene, lycopene, and -carotene. Strain improvement through mutagenesis is difficult because all life stages are multinucleate. Mutants have been obtained following exposure of wild-type spores to N-methyl-N-nitro-N-nitrosoguanidine. Changes in the colour of the mycelia reflect variations in the accumulation of various precursors and the final product. Quantitative analysis of the mutants leads to the conclusion that the biosynthetic pathway is similar to that of the related fungus Phycomyces blakesleeanus, but the regulation is completely different. In particular, interruption of the pathway does not lead to overacummulation of precursors.     

Filamentous fungus Aspergillus oryzae has two types of α-1,2-mannosidases, one of which is a microsomal enzyme that removes a single mannose residue from Man9GlcNAc2

-Mannosidase activities towards high-mannose oligosaccharides were examined with a detergent-solubilized microsomal preparation from a filamentous fungus, Aspergillus oryzae. In the enzymatic reaction, the pyridylaminated substrate Man₉GlcNAc₂-PA was trimmed to Man₈GlcNAc₂-PA which lacked one -1,2-mannose residue at the nonreducing terminus of the middle branch (Man8B isomer), and this mannooligosaccharide remained predominant through the overall reaction. Trimming was optimal at pH 7.0 in PIPES buffer in the presence of calcium ion and kifunensine was inhibitory with IC₅₀ below 0.1[emsp4 ]M. These results suggest that the activity is the same type as was previously observed with human and yeast endoplasmic reticulum (ER) -mannosidases. Considering these results together with previous data on a fungal -1,2-mannosidase that trimmed Man₉GlcNAc₂ to Man₅GlcNAc₂ (Ichishima, E., et al. (1999) bit>Biochem J, 339: 589–597), the filamentous fungi appear to have two types of -1,2-mannosidases, each of which acts differently on N-linked mannooligosaccharides.     

Some observations on the diet and food selection ofDaphnia hyalina (Cladocera) in an eutrophic lake

Summary The food composition in the guts ofDaphnia hyalina was compared with the phytoplankton composition in the lake water on several dates during the year. The guts contained almost exclusively algae; detritus was not an important food item. ExceptOscillatoria agardhii, all large algal forms were generally avoided. On a whole,Scenedesmus was the most preferred taxon, but as numbers or biomass ingestedO. agardhii was more important. The filamentous blue-green algae>60 m (range: 60–1500 m) were strongly avoided byDaphnia. The observed size selective feeding is probably the result of limitations in their filtering apparatus rather than active selection.     

Scanning electron microscopy of the gut microflora of two earthworms: Lumbricus terrestris and Octolasion cyaneum

Scanning electron microscopy was used to investigate the presence of microorganisms, probably bacteria, on the gut surface of earthworms. The washed surfaces of the intestines of two earthworms, Lumbricus terrestris and Octolasion cyaneum, were examined. Numerous organisms resembling bacteria were observed throughout the gut, some in situations suggesting attachment. Compared with similar investigations in other invertebrates, there were fewer bacteria, showing less morphological diversity, on the earthworm gut surface. The majority of organisms viewed were coccoid, some were filamentous, and a few rod-shaped cells were observed. Cocci, often in chains, were seen in the foregut of both species. Although cocci were also numerous in the midgut region, particularly in the typhlosole, in O. cyaneum tufts of segmented, filamentous organisms were also seen with some segments resembling spores. Fewer organisms were found in the hindgut, but in L. terrestris there were segmented, filamentous organisms, attached to the epithelium by way of a socket-like structure, similar to that by which segmented, filamentous bacteria (SFBs) are attached to the ileum of rats and mice. Transmission electron microscopy of the hindgut of L. terrestris was undertaken to explore the structure and attachment of SFBs to the gut epithelium. However, although a few rod-shaped bacteria were observed, no SFBs were located. The observations reported here provide evidence that earthworms have an attached gut microflora of filamentous microorganisms which are probably indigenous, and as far as we are aware this is the first published report of such findings in these invertebrates. Offprint requests to: J.M. Jolly.     

The ultrastructural organization of the basement membrane of Bowman's capsule in the rat renal corpuscle

Summary The basement membrane of Bowman's capsule (BCBM) of the rat was studied by means of a modified tissue-preservation technique for transmission electron microscopy, which avoids the usual thorough fixation in OsO₄ and applies tannic acid and uranyl acetate for staining (Sakai et al. 1986). At most sites the BCBM is multilayered, consisting of one to seven dense layers separated by electron-lucent layers. The latter, which can be termed laminae rarae, contain fine filaments which connect the dense layers to each other and the innermost dense layer to the basal cell membrane of the parietal epithelium. The laminae densae are basically composed of fine filaments arranged in an anastomosing pattern. Individual filaments ranging from 5 to 15 nm in diameter, combine to form filament bundles up to 100 nm in thickness and 1 to 2 m in length. Within a dense layer, filaments and filamentous bundles are oriented mainly in the same direction. Often the inner dense layers do not form a continuous sheet, and the filamentous bundles are arranged in anastomosing or spiral patterns to form a ribbon-like structure that we call a microligament. These microligaments are often embedded in basal furrows of the parietal epithelium and are best developed around the vascular pole. Intracellular actin bundles of the parietal cells are regularly associated with these extracellular ribbon-like structures of the basement membrane. In conclusion, the BCBM has an unusual structure: the laminae densae are characterized by their filamentous nature and are arranged in different patterns, i.e. as a multilayered mat and as microligaments.Fellow of the Deutscher Akademischer Austauschdienst     

Observations on endonuclear bacteria in euglenoid flagellates

Summary Rod-shaped inclusions in the nuclei and/or cytoplasm of strains ofEuglena spirogyra, Lepocinclis ovum, Strombomonas conspersa andTrachelomonas oblonga var.punctata have been identified as living populations of bacteria by reference to size, shape and ultrastructure. Most strains contain 20–200 bacteria per nucleus. Each bacterial cell is surrounded by a mucilaginous sheath and consists of a double-membraned envelope, dense cytoplasm with small ribosomes, and a filamentous DNA-containing centre. The bacteria multiply to keep pace with euglenoid division but there is no evidence that the euglenoid cells benefit from or are harmed by the association. Attempts to transfer the endonuclear bacteria to uninfected strains and species have been unsuccessful, as have attempts to isolate the bacterium into pure culture. The infected strain ofEuglena spirogyra cannot fix nitrogen. The possible nature of the euglenoid/bacterium association is discussed.Dedicated to Prof. Dr.Lothar Geitler on the occasion of his 70th birthday.     

Influence of internal loading on phosphorus concentration in shallow lakes before and after reduction of the external loading

An analysis of data from 49 shallow lakes showed, that the parameters of empirical models between phosphorus loading and concentration in the lake (e.g. Vollenweider type of relations) differ significantly for lakes without or with a reduced external loading. For lakes without a reduction of the external loading the summer phosphorus concentration is determined by the external phosphorus loading and the hydraulic loading. For these lakes the classical models suffice; deviations between calculations and measurements are partly due to errors made in the determination of the loading.In contrast, for lakes where the external loading was reduced, the measured internal loading explains most of the variation in the summer lake concentration. The external loading is of minor importance and the classical models cannot be applied. The internal loading measured before reduction of the external loading is not useful in predicting the concentration afterwards. Instead of the internal loading, the sediment composition can be used. The advantage of using sediment composition is that these variables are easier to determine and vary less in time. The most promising variable is the ratio between total P and total Fe in the sediment.Abbreviations: Q_s hydraulic loading (m y^-1) - hydraulic retention time (y) - L_ext external phosphorus loading (gP m^-2 y^-1) - L_int internal phosphorus loading (gP m^-2 y^-1) - P_lake phosphorus concentration in the lake (gP m^-3) - P_inlet phosphorus concentration in the inlet water (gP m^-3) - P_sed phosphorus content on the sediment (gP kg^-1 d.w.) - Fe_sed iron content of the sediment (gFe kg^-1 d.w.) - Y dependent variable multiple regression calculations - X1, X2 independent variables multiple regressions calculations - a, a1 constants - a2, b constants     

<Emphasis Type="Italic">Vanderhorstia papilio</Emphasis>, a new shrimp-associated goby from the Ryukyu Islands,Japan (Perciformes: Gobiidae: Gobiinae), with comments on the limits of the genus

A new gobiid fish, Vanderhorstia papilio, is described based on a single specimen (40.9mm SL) captured from a sandy-mud bottom at a depth of 45m in a protected bay of Iriomote-jima Island, Ryukyu Islands, Japan. It is distinguished from congeners in having the following combination of characters: 11 segmented dorsal-fin rays; 11 segmented anal-fin rays; 27 longitudinal scales; 11 predorsal scales; third spine of first dorsal fin elongate, filamentous, and longer than preceding spine; fifth and ninth branched caudal-fin rays elongate, filamentous, and forming bifurcated caudal fin; fifth and ninth branched caudal-fin rays with a single branch in each; cephalic sensory-papillae row a comprises three widely-spaced papillae; when live or fresh, numerous small yellow spots scattered on head, body, and dorsal fins; dusky yellowish-brown vertical bar below eye; four dark gray-brown saddles on body, in addition to a similarly colored large blotch at midlateral caudal-fin base. The limits and diagnosis of the genus Vanderhorstia are discussed.     

Root hairs confer a competitive advantage under low phosphorus availability

Root hairs are presumably important in the acquisition of immobile soil resources such as phosphorus. The density and length of root hairs vary substantially within and between species, and are highly regulated by soil phosphorus availability, which suggests that at high nutrient availability, root hairs may have a neutral or negative impact on fitness. We used a root-hairless mutant of the small herbaceous dicot Arabidopsis thaliana to assess the effect of root hairs on plant competition under contrasting phosphorus regimes. Wildtype plants were grown with hairless plants in a replacement series design at high (60 m phosphate in soil solution) and low (1 m phosphate in soil solution) phosphorus availability. At high phosphorus availability, wildtype and mutant plants were equal in growth, phosphorus acquisition, fecundity and relative crowding coefficient (RCC). At low phosphorus availability, hairless plants accumulated less biomass and phosphorus, and produced less seed when planted with wildtype plants. Wildtype plants were unaffected by the presence of hairless plants in mixed genotype plantings. Wildtype plants had RCC values greater than one while hairless plants had RCC values less than one. We conclude that root hairs increase the competitiveness of plants under low phosphorus availability but do not reduce growth or competitiveness under high phosphorus availability.     

Oscillations of algal biomass,nutrients and dissolved oxygen as a measure of ecosystem stability

Graphic presentation of weekly rates of change of algal biomass (expressed as chlorophyll a) and nutrient and dissolved oxygen concentrations can be regarded as harmonic oscillation motion. Maximum amplitudes of these oscillations provide a useful tool to assess the degree of stability of aquatic ecosystems in relation to their trophic state. Data sets from seven different lakes ranging from hypereutrophic to oligo-mesotrophic were processed using a computerized method. The high values of oscillation amplitudes of approximately 150 g l^–1 wk^–1 chlorophyll a, 500 g l^–1 wk^–1 ammonia nitrogen, 50 g l^–1 wk^–1 soluble reactive phosphorus and 10 mg l^–1 wk^–1 dissolved oxygen, indicated strong ecosystem instability, while low values of less than 10 g l^–1 wk^–1 of chlorophyll a, 20 g l^–1 wk^–1 ammonia nitrogen, 2 g l^–1 wk^–1 soluble reactive phosphorus, and 3 mg l^–1 wk^–1 dissolved oxygen represented a stable system. Oscillation amplitudes of the chlorophyll a values were found to be the most representative indicator of ecosystem stability.