Significance of rooting depth in mire plants: Evidence from natural <Superscript>15</Superscript>N abundance

Variation in stable nitrogen isotope ratios (¹⁵N) was assessed for plants comprising two wetland communities, a bog-fen system and a flood plain, in central Japan. ¹⁵N of 12 species from the bog-fen system and six species from the flood plain were remarkably variable, ranging from –5.9 to +1.1 and from +3.1 to +8.7, respectively. Phragmites australis exhibited the highest ¹⁵N value at both sites. Rooting depth also differed greatly with plant species, ranging from 5cm to over 200cm in the bog-fen system. There was a tendency for plants having deeper root systems to exhibit higher ¹⁵N values; plant ¹⁵N was positively associated with rooting depth. Moreover, an increasing gradient of peat ¹⁵N was found along with depth. This evidence, together with the fact that inorganic nitrogen was depleted under a deep-rooted Phragmites australis stand, strongly suggests that deep-rooted plants actually absorb nitrogen from the deep peat layer. Thus, we successfully demonstrated the diverse traits of nitrogen nutrition among mire plants using stable isotope analysis. The ecological significance of deep rooting in mire plants is that it enables those plants to monopolize nutrients in deep substratum layers. This advantage should compensate for any consequential structural and/or physiological costs. Good evidence of the benefits of deep rooting is provided by the fact that Phragmites australis dominates as a tall mire grass.     

Development of an L6 myoblast in vitro model of moniliformin toxicosis

L6 myoblasts were used as an in vitro model to investigate the role of moniliformin and its interaction with monensin in turkey knockdown syndrome and sudden death syndromes in poultry. Cell viability and microscopic and ultrastructural alterations noted in L6 myoblasts cultured in the presence of moniliformin (0.0–0.3 g/l) were compared to those observed in parallel cultures also containing one of the following compounds: selenium (0–0.004 ng/l), thiamine (0–0.3 g/l), or pyruvate (0–0.46 g/l). Marked dilation of the RER, membranous whorls, glycogen deposition, membrane-bound cytoplasmic inclusions and necrosis were observed in myoblasts exposed to 0.03/2-0.30 g moniliformin/l medium. Supplementation of medium with thiamine and pyruvate, or selenium, provided significant protection to cells exposed to 0.0–0.3 g/l or 0.0–0.15 g moniliformin/l, respectively. Dose-dependent differences in protein and ATP production were not detected. Myoblasts grown in medium containing 0–0.15 g moniliformin/l and 7.5–50.0 M A23187, beauvericin or monensin had degrees of cytotoxicity similar to parallel cultures receiving only an ionophore. L6 myoblasts were a useful model of moniliformin toxicosis. The findings of this study suggest cytotoxicity due to moniliformin in L6 myoblasts may be due in part to oxidative damage and altered pyruvate metabolism, and that moniliformin does not predispose myoblasts to ionophore toxicosis. This study supports the results of in vivo investigations in poultry that moniliformin and monensin do not act synergistically to induce knockdown or monensin toxicosis.     

Mode of uptake of sterol by Arthrobacter simplex

The mechanism of uptake of water-insoluble -sitosterol by a newly isolated strain of Arthrobacter simplex SS-7 was studied. The production of an extracellular sterol-pseudosolubilizing protein during growth of A. simplex on -sitosterol was demonstrated by isolating the factor from the cell-free supernatant and its subsequent purification by Sephadex G-150 column chromatography. The M _r of the purified sterol-pseudosolubilizing protein determined by SDS–PAGE was 19kDa. The rate of sterol pseudosolubilization (5.2×10^–3g l^–1h^–1) could not adequately account for the rate of sterol uptake (72×10^–3g l^–1h^–1) and the specific growth rate (56×10^–3 h^–1). However in the unfavourable growth condition, when the cells were treated with sodium azide at the level of 30–60% of MIC, the sterol pseudosolubilization accounted for nearly 74% of the total growth containing 96% free cells. Cellular adherence to substrate particles was found to play an active role in the normal growth of the strain on -sitosterol. Unlike sodium acetate-grown cells, whose surface activity was negligible (60mNm^–1), the sterol-grown cells had strong surface activity (40mNm^–1). The high lipid content and long chain fatty acids in the cell-wall of -sitosterol-grown cells probably contribute to the high sterol adherence activity of the cells.     

Summer egg production rates of paracalanid copepods in subtropical waters adjacent to Australia's North West Cape

The biological oceanography of waters adjacent to Australia's North West Cape (21° 49 S, 114° 14 E) was studied during the austral summers of 1997/98 and 1998/99. We measured egg production rate (EPR) by the small paracalanid copepods that dominated the calanoid community. Bottle incubation experiments were conducted at a shallow (20 m) station in the mouth of Exmouth Gulf, and at a shelf-break station (80 m). In 1997/98, we measured EPR by Paracalanus aculeatus, P. indicus, Acrocalanus gracilis and Bestiolina similis, but in 1998/99, we concentrated on P. indicus. Maximal observed EPRs by Paracalanus and Acrocalanus species were 30 eggs female^–1 d^–1, but B. similis attained only 17 eggs female^–1 d^–1. Sporadic measurements of EPR by P. aculeatus minor (maximum 4 eggs female^–1 d^–1) and Parvocalanus crassirostris ( 9 eggs female^–1 d^–1) were also made. However, maximal EPRs were seldom achieved and were often less than 10 eggs female^–1 d^–1. There was no difference between EPR of either P. indicus or B. similis in 1997/98 and 1998/99, despite differences in temperature. Trophic resources severely limit copepod egg production in this area. We suggest that variability and skewness of egg production data derived from individual incubations may be used to judge the degree of food limitation of the population and the variability in feeding success between individuals. The dominance of small copepods and the invariance in their EPR suggest that pulses in physical forcing and subsequent primary production will be severely damped by trophodynamic processes before reaching larval fish.     

Descriptive morphology of the reared eggs,larvae, and juveniles of the marine atherinid fish <Emphasis Type="Italic">Atherinomorus duodecimalis</Emphasis>

Embryonic, larval, and juvenile development of the marine atherinid Atherinomorus duodecimalis are described from laboratory-reared specimens. The eggs, measuring 1.15–1.24mm in diameter, were demersal and almost spherical in shape with numerous chorionic filaments. Hatching occurred 7 or 8 days after spawning, the newly hatched larvae measuring 4.5–5.1mm in body length (BL) and having 5+34=39 myomeres. Notochord flexion started at 6.9mm BL and finished at 8.3mm BL. Aggregate numbers of all fin rays were completed by 14mm BL. Eggs of this species could be distinguished from other known atherinid eggs on the basis of egg diameter and the arrangement, length, and number of chorionic filaments. Larvae were also distinctive in myomere counts, pigmentation, and locations of the anus and second dorsal fin origin.     

Metal Cations Defibrillize the Amyloid Beta-Protein Fibrils

Amyloid beta-protein (A) is the major constituent of amyloid fibrils composing -amyloid plaques and cerebrovascular amyloid in Alzheimer's disease (AD). We studied the effect of metal cations on preformed fibrils of synthetic A by Thioflavin T (ThT) fluorescence spectroscopy and electronmicroscopy (EM) in negative staining. The amount of cross beta-pleated sheet structure of A 1–40 fibrils was found to decrease by metal cations in a concentration-dependent manner as measured by ThT fluorescence spectroscopy. The order of defibrillization of A 1–40 fibrils by metal cations was: Ca²⁺ and Zn²⁺ (IC₅₀ = 100 M) > Mg²⁺ (IC₅₀ = 300 M) > Al³⁺ (IC₅₀ =1.1 mM). EM analysis in negative staining showed that A 1–40 fibrils in the absence of cations were organized in a fine network with a little or no amorphous material. The addition of Ca²⁺, Mg²⁺, and Zn²⁺ to preformed A 1–40 fibrils defibrillized the fibrils or converted them into short rods or to amorphous material. Al³⁺ was less effective, and reduced the fibril network by about 80 % of that in the absence of any metal cation. Studies with A 1–42 showed that this peptide forms more dense network of fibrils as compared to A 1–40. Both ThT fluorescence spectroscopy and EM showed that similar to A 1–40, A 1–42 fibrils are also defibrillized in the presence of millimolar concentrations of Ca²⁺. These studies suggest that metal cations can defibrillize the fibrils of synthetic A.     

Tissue culture ofKarwinskia humboldtiana—a plant producing toxins with antitumoural effects

Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10^-2 mol l^–1, gibberellic acid (GA₃) 3.10^-2 mol l^–1, and 6-benzylaminopurine (BA) 2 mol l^–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l^–1, GA₃ 14 mol l^–1, and kinetin 5 mol l^–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l^–1 and BA 10 mol l^–1 was induced.Abbreviations BA 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - TEM transmission electron microscopy     

The North Sea: source or sink for nitrogen and phosphorus to the Atlantic Ocean?

Annual nitrogen and phosphorus budgets for the whole North Sea taking into account the most recent data available were established. The area considered has a total surface of approximately 700,000km² and corresponds to the definition by OSPARCOM (Oslo and Paris Commission) with the exclusion of the Skagerrak and Kattegat areas. Input and output fluxes were determined at the marine, atmospheric, sediment and continental boundaries, and riverine inputs based on river flows and nutrient concentrations at the river–estuary interface were corrected for possible estuarine retention. The results showed that the North Sea is an extremely complex system subjected to large inter-annual variability of marine water circulation and freshwater land run-off. Consequently, resulting total N (TN) and P (TP) fluxes are extremely variable from 1 year to another and this has an important influence on the budget of these elements. Total inputs to the North Sea are 8870±4860kTNyear^–1 and 494±279kTPyear^–1. Denitrification is responsible for the loss of 23±7% of the TN inputs while sediment burial is responsible for the retention of only of 2±2% of the TP input. For TN, due to the large variability on marine and estuarine fluxes, and to the uncertainty related to the denitrification rate, it was concluded that the North Sea could either be a source (1930kTNyear^–1) or a sink (1700kTNyear^–1) for the waters of the North Atlantic Ocean. For TP it was concluded that the North Sea is mostly a source (–4 to 52kTPyear^–1) for the waters of the North Atlantic Ocean.     

Adventitious shoot regeneration from leaf explants of tissue cultured and greenhouse-grown raspberry

Adventitious shoot regeneration was observed using leaf-petiole explants from shoot-proliferating cultures of Comet red raspberry (Rubus idaeus L.). A maximum regeneration rate of 70% (3.7 shoots/explant) was obtained using 4.5–9.1 M (1–2 mg l^–1) N-phenyl-N-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ) with 2.5–4.9 M (0.5–1 mg l^–1) 1H-indole-3-butanoic acid (IBA) or 2.3 M (0.5 mg l^–1) TDZ with 4.9 M (1 mg l^–1) IBA in modified Murashige-Skoog medium. TDZ was more effective than N-(phenylmethyl)-1H-purin-6-amine (BA) at promoting regeneration in combinations tested with IBA (maximum 50% regeneration rate; 1.8 shoots/explant). Variation in the agar concentration or incubation temperature, orientation or scoring of the leaf-petiole explants and use of separate leaf or petiole explants had no effect on shoot regeneration. Incubation in the dark for 1, 2 or 3 weeks prior to growth in the light did not influence the percent regeneration rate but depressed the number of adventitious shoots. Explant source, from micropropagated shoots or greenhouse-grown plants, had an effect on shoot regeneration that was genotype dependent. Only 8 of 22 (36%) raspberry cultivars were capable of regeneration from leaf explants derived from greenhouse-grown plants.     

Structural Features of Pregna-D′-pentaranes Determining Their Interaction with Three Rat Proteins

Competition of a number of progesterone 16,17-cycloalkane derivatives with ³H-labeled ligands for the binding sites of rat uterine progesterone receptor, uterine pentaranophilin, and blood serum pentaranophilin was studied. We found that the selective ligands for the progesterone receptor are progesterone, 16,17-cyclopropanoprogesterone, and 16,17-cyclopent-3-enoprogesterone and the selective ligands for serum pentaranophilin are 6-methyl-16,17-cyclohexanopregna-1,4-diene-3,20-dione and 3-hydroxy-16,17-cyclohexanopregn-5-en-20-one. No selective ligands for the uterine pentaranophilin were found. The majority of substituents in rings A, B, and D we studied decreased the affinity of ligands for all the three proteins. The substitution of the ⁵-3-hydroxy grouping for the ⁴-3-keto grouping exerted the strongest negative effect in the case of the progesterone receptor and the uterine pentaranophilin, whereas the introduction of the 3,4-dimethyl grouping strongly inhibited the ligand affinity for the uterine pentaranophilin. The extent and even the direction of the effect of a substituent on the affinity of ligands for the proteins substantially depended on the presence of other substituents in the steroid molecules. We hypothesized that a certain similarity exists between three proteins studied in respect to the structures of their ligand-binding pockets.     

Direct Development of the Visual System of the Coral Reef Teleost, The Spiny Damsel, Acanthochromis polyacanthus

Unlike most marine teleosts, the coral reef-dwelling spiny damsel, Acanthochromis polyacanthus, lacks a pelagic larva dispersal phase and represents one of few examples of self recruitment onto a natal reef by a marine teleost immediately after hatching. Benthic eggs are protected by the parents, and upon hatching the young remain under parental care for several months. Visual morphogenesis of spiny damsel embryos and juveniles was examined to evaluate the potential visual capabilities of the young after emergence onto the reef. The optic primordia were visible in the embryo as hollow spheres of undifferentiated neuroblasts 2 days after fertilization (daf). Visual morphogenesis proceeded rapidly thereafter in the embryo such that at hatching (between 10 and 12daf) gross visual morphology was consistent with that reported in the majority of juvenile marine teleosts, reflecting direct development of the retina of the spiny damsel within the egg. At hatching, the outer nuclear layer comprised 2 classes of photoreceptors; cones and rods. Tangential sections of the retina revealed a square cone mosaic in which 4 double cones surrounded a single cone. This arrangement remained unchanged in all later life history intervals examined. Absolute eye size was large compared to larvae of marine pelagic spawners. Eye and lens diameters increased from 0.69 and 0.23mm, respectively, on the day of hatching (12daf), to 3.77 and 1.52mm, respectively, in a fish 131daf. Angular density of cones increased from 0.25 cones 10 visual arc^–1 in an embryo 8daf, to 1.14 cones 10 visual arc^–1 in a fish 131daf, demonstrating the potential for significant increase in spatial resolution with increasing eye size. Convergence ratios of cones to ganglion cells remained relatively constant from the time of hatching, suggesting that the determinate ganglion cell photopic receptive field was established early in development. The increase in the convergence ratios of rods: ganglion cells from 1.4 in the late stages of embryogenesis (10daf; 2 days prior to hatching) to 4.9 in a fish 103daf, demonstrated increasing scotopic ganglion cell receptive field size, with increasing age. This was a result of rod cell addition with growth. An increase in the angular density of rods from 0.18 rods 10 visual arc^–1 in an embryo 8daf, to 4.07 rods 10 visual arc^–1 in a fish 131daf, and the increase in mean scotopic light path-length from 13.3±1.1m in an embryo 8dpf, to 55±5.2m a fish 22dpf, collectively indicate the potential for increasing scotopic sensitivity during growth. On the basis of visual morphology it is predicted that newly hatched spiny damsel juveniles have substantially greater visual capabilities than first feeding larvae with a pelagic dispersal phase. In addition, we propose that the developmental trajectory of the spiny damsel is different from that of pelagic dispersing larvae and does not simply reflect displacement along a common developmental continuum by an extended embryonic duration.     

Ethanol production in multistage continuous, single stage continuous, Lactobacillus-contaminated continuous, and batch fermentations

Saccharomyces cerevisiae-based ethanol fermentations were conducted in batch culture, in a single stage continuous stirred tank reactor (CSTR), a multistage CSTR, and in a fermentor contaminated with Lactobacillus that corresponded to the first fermentor of the multistage CSTR system. Using a glucose concentration of 260 g l^–1 in the medium, the highest ethanol concentration reached was in batch (116gl^–1), followed by the multistage CSTR (106gl^–1), and the single stage CSTR continuous production system (60gl^–1). The highest ethanol productivity at this sugar concentration was achieved in the multistage CSTR system where a productivity of 12.7gl^–1h^–1 was seen. The other fermentation systems in comparison did not exceed an ethanol productivity of 3gl^–1h^–1. By performing a continuous ethanol fermentation in multiple stages (having a total equivalent working volume of the tested single stage), a 4-fold higher ethanol productivity was achieved as compared to either the single stage CSTR, or the batch fermentation.     

The Use of the [13C]/[12C] Ratio for the Assay of the Microbial Oxidation of Hydrocarbons

The study deals with a comparative analysis of the relative abundances of the carbon isotopes ¹²C and ¹³C in the metabolites and biomass of the Burkholderia sp. BS3702 and Pseudomonas putida BS202-p strains capable of utilizing aliphatic (n-hexadecane) and aromatic (naphthalene) hydrocarbons as sources of carbon and energy. The isotope compositions of the carbon dioxide, biomass, and exometabolites produced during the growth of Burkholderia sp. BS3702 on n-hexadecane (¹³C = –44.6 ± 0.2) were characterized by the values of ¹³C_{CO 2} = –50.2 ± 0.4, ¹³C_biom = –46.6 ± 0.4, and ¹³C_exo = –41.5 ± 0.4, respectively. The isotope compositions of the carbon dioxide, biomass, and exometabolites produced during the growth of the same bacterial strain on naphthalene (¹³C = –21 ± 0.4) were characterized by the isotope effects ¹³C_{CO 2} = –24.1 ± 0.4, ¹³C_biom = –19.2 ± 0.4, and ¹³C_exo = –19.1 ± 0.4, respectively. The possibility of using the isotope composition of metabolic carbon dioxide for the rapid monitoring of the microbial degradation of petroleum hydrocarbons in the environment is discussed.     

Altitudinal distribution of first-year male Black Redstarts(Phoenicurus ochruros) in the western Pyrenees

Summary First-year, Black Redstart- in brown plumage were found to breed above tree-line in the western Pyrenees. Significantly more brown than black (adult) ones bred at higher than at lower altitudes. It is suggested that adult establish territories at lower altitudes, thereby forcing younger birds to settle higher up the slopes.

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Zusammenfassung Höhenverbreitung einjähriger Hausrotschwanz- in den Westpyrenäen. — Einjährige braune des Hausrotschwanzes wurden als Brutvögel oberhalb der Baumgrenze in den Westpyrenäen festgestellt. Im Vergleich brüteten signifikant mehr braune als schwarze (=ad.) in größeren Höhen. Vermutlich besetzen ad. Reviere in niedrigeren Höhenstufen und zwingen so jüngere Vögel, sich in größeren Meereshöhen anzusiedeln.

     

Contribution of flow cytometry to estimate picoplankton biomass in estuarine systems

Picoplankton (plankton 3 m) biomass was determined by flow cytometry in three European estuarine systems (Krka Estuary in Croatia, Rhône Delta in France, and Lena Delta and Laptev Sea in Russia). The size of natural phytoplankton groups was obtained by a calibration curve, with different picoplankton's strains (from 1.6 to 3.4 m), measured by a Coulter counter (size) and a flow cytometer (light-scattering). Two natural groups of picoplankton were identified by flow cytometry in the three systems: Synechococcus sp and picoeukaryotes. Picoplankton cells abundance ranged between: 2800 and 42000, 5000 and 37000, 1000 and 50000 cells ml^–1 in the Krka estuary, in the Rhône delta and in the Lena-Laptev system, respectively. In the Krka estuary, picoplankton biomass ranges between 11 and 68 gC l^–1. It can make up as much as 88% of the total photosynthetic plankton population and 50% of total organic particulate carbon. Picoplankton biomass was greater in the summer than in the autumn. At the halocline layer this biomass can attempt ca. 390 gC l^–1during the summer cruise. In the Rhône delta, a lower picoplankton biomass (6–39 gC l^–1) was observed at the end of the winter. These biomass represented between 0.4 and 22% of the particulate organic carbon, which could reach 71% of the total photosynthetic plankton biomass at the marine station. In the Lena-Laptev system, picoplankton biomass varied between 6 and 56 gC l^–1 in surface waters. Picoplankton biomass decreased with depth, but picoeukaryotes were still observed in deep samples (20, 30 m) in the Laptev Sea, showing a considerable autotrophic activity in spite of low temperatures (0–1 °C). Although the widely dispersed estuary geographic distribution and their different estuarine characteristics, the data point out that these small organisms can also play an important role in the transfer of organic carbon from rivers to oceans and that flow cytometry can be able to detect these small cells in turbid systems.     

Analysis of primary food sources and trophic relationships of aquatic animals in a mangrove-fringed estuary,Khung Krabaen Bay (Thailand) using dual stable isotope techniques

Stable carbon (¹³C) and nitrogen (¹⁵N) isotopes were used to elucidate primary food sources and trophic relationships of organisms in Khung Krabaen Bay and adjacent offshore waters. The three separate sampling sites were mangroves, inner bay and offshore. The ¹³C values of mangrove leaves were –28.2 to –29.4, seagrass –10.5, macroalgae –14.9 to –18.2, plankton –20.0 to –21.8, benthic detritus –15.1 to –26.3, invertebrates –16.5 to –26.0, and fishes –13.4 to –26.3. The ¹⁵N values of mangrove leaves were 4.3 to 5.7, seagrass 4.3, macroalgae 2.2 to 4.4, plankton 5.7 to 6.4 , benthic detritus 5.1 to 5.3, invertebrates 7.2 to 12.2 , and fishes 6.3 to 15.9. The primary producers had distinct ¹³C values. The ¹³C values of animals collected from mangroves were more negative than those of animals collected far from shore. The primary carbon sources that support food webs clearly depended on location. The contribution of mangroves to food webs was confined only to mangroves, but a mixture of macroalgae and plankton was a major carbon source for organisms in the inner bay area. Offshore organisms clearly derived their carbon through the planktonic food web. The ¹⁵N values of consumers were enriched by 3–4 relative to their diets. The ¹⁵N data suggests that some of aquatic animals had capacity to change their feeding habits according to places and availability of foods and as a result, individuals of the same species could be assigned to different trophic levels at different places.     

Degradation by and toxicity to bacteria of chlorinated phenols and benzenes,and hexachlorocyclohexane isomers

Mixed cultures degrading chlorinated benzenes, chlorinated phenols, or hexachlorocyclohexane (HCH) as the sole source of carbon and energy were obtained by enrichment from contaminated soil samples. Cultures which metabolized 3-chlorophenol (3-CP), 2,3-dichlorophenol (2,3-DCP), or 2,6-dichlorophenol (2,6-DCP) were able to utilize several other chlorinated compounds as substrates, whereas cultures enriched with 1,2,4,5-tetrachlorobenzene (1,2,4,5-TeCB), -HCH, or -HCH did not metabolize most of the other chlorinated congeners tested. Chloride release and growth rates with all four chlorinated phenols decreased with increasing initial substrate concentrations within the range of 30–250 mol liter^–1. Maximum chloride release was 3.8 mg liter^–1 corresponding to 35 mol liter^–1 trichlorophenol within 7 weeks. In contrast, the rate of metabolism of the nonphenolic compounds 1,2,4,5-TeCB, -HCH, or -HCH increased with increasing substrate concentrations. Initial concentrations of 750 mol liter^–1 -HCH or 1,2,4,5-TeCB were completely dechlorinated within 2 weeks. Because aqueous solubility and bioavailability of the chlorophenolic compounds is much higher than that of the nonphenolic compounds, it is suggested that the high bioavailability of the chlorophenolic compounds is the reason for the high toxicity of these substrates to the degrading cultures. In contrast, the low aqueous solubilities of the chlorinated benzenes and HCH-isomers caused consistently low concentrations in the medium, which were high enough to induce degradation but too low to damage the bacterial cells.Correspondence to: E. Lang     

Interleukin-2-dependent long-term cultures of low-density lymphocytes allow the proliferation of lymphokine-activated killer cells with natural killer,Tiγ/δ or TNK phenotype

Summary We have developed a culture system for longterm growth of human lymphokine-activated killer (LAK) cells exhibiting an elevated, wide-spectrum antitumor cytotoxicity. The system allows the exponential growth of monocyte-depleted low-density lymphocytes in the presence of human serum and recombinant human interleukin-2 (10³ U/ml), alone or in combination with interleukin-1 or (both at 10 U/ml). Eighteen cultures were established from 18 normal adult donors. The membrane phenotypes of the final LAK cell population, assessed by a panel of monoclonal antibodies (mAb), consist of three main types: (a) NKH-1⁺, Ti/^–, Ti/^–, and CD3^– lymphocytes; (b) NKH-1⁺, Ti/^–, Ti/⁺, and CD3⁺ lymphocytes and (c) NKH-1⁺, Ti/⁺, Ti/^– and CD3⁺ lymphocytes. Northern blot analysis showed that all these cell populations express relatively high levels of perforin RNA, particularly cells exhibiting the first phenotype. This culture system may provide a tool for cellular and molecular studies on the mechanisms of antitumor cytotoxicity, as well as the basis for new adoptive immunotherapy protocols in advanced cancer.     

Increased erythritol production in Torula sp. by Mn2+and Cu2+

The production of erythritol and the erythritol yield from glucose by Torula sp. were improved, in increasing order, by supplementing with 10 mg MnSO₄4H₂O l^–1, 2 mg CuSO₄5H₂O l^–1, and both 10 mg MnSO₄4H₂O l^–1 and 2 mg CuSO₄5H₂O l^–1. Mn²⁺ decreased the intracellular concentration of erythritol, whereas Cu²⁺ increased the activity of erythrose reductase in cells. These results suggest that Mn²⁺ altered the permeability of cells, whereas Cu²⁺ increased the activity of erythrose reductase in cells.     

Diversity,metabolic types and δ13C carbon isotope ratios in the grass flora of Namibia in relation to growth form,precipitation and habitat conditions

The grass flora of Namibia (374 species in 110 genera) shows surprisingly little variation in ¹³C values along a rainfall gradient (50–600 mm) and in different habitat conditions. However, there are significant differences in the ¹³C values between the metabolic types of the C4 photosynthetic pathway. NADP-ME-type C4 species exhibit the highest ¹³C values (–11.7 ) and occur mainly in regions with high rainfall. NAD-ME-type C4 species have significantly lower ¹³C values (–13.4 ) and dominate in the most arid part of the precipitation regime. PCK-type C4 species play an intermediate role (–12.5 ) and reach a maximum abundance in areas of intermediate precipitation. This pattern is also evident in genera containing species of different metabolic types. Within the same genus NAD species reach more negative ¹³C values than PCK species and ¹³C values decreased with rainfall. Also in Aristida, with NADP-ME-type photosynthesis, ¹³C values decreased from –11 in the inland region (600 mm precipitation) to –15 near the coast (150 mm precipitation), which is a change in discrimination which is otherwise associated by a change in metabolism. The exceptional C3 species Eragrostis walteri and Panicum heterostachyum are coastal species experiencing 50 mm precipitation only. Many of the rare species and monotypic genera grow in moist habitats rather than in the desert, and they are not different in their carbon isotope ratios from the more common flora. The role of species diversity with respect to habitat occupation and carbon metabolism is discussed.