Signaling Pathways That Control the Growth and Survival of Prostate Carcinoma Cells in the Absence of Androgens

Androgen-dependent human prostate adenocarcinoma cell line LNCaP was used to study the effect of androgen deprivation on the cell response to TNF-related cytokines. Several signaling pathways were implicated in cell survival in the absence of androgens. In androgen-deprived LNCaP cells, TNF- and TRAIL stimulated the cell growth and activated the mitogenic and antiapoptotic signaling pathways involving NF-B, STAT3, PI3K, and -catenin. The results suggested a role of cytokines in the survival of prostate adenocarcinoma cells deprived of androgens in vitro.     

Der soziologische konnex der 47 häufigsten makrophyten der gewässer mitteleuropas

Summary Phytosociological species groups within the classes Lemnetea and Potametea are investigated on the basis of 3000 relevés. The relations between species are calculated with the coefficient of Hamming and a % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Xdm2aaW% baaSqabeaacaqGYaaaaaaa!3885!\[\chi ^{\text{2}} \]. The results are presented in the form of a table with the species ordered in a linear sequence as well as in a plexus diagram. The 47 most frequent species are grouped into 4 clusters and the significance of these phyto-sociological species groups for the syntaxonomy of aquatic communities is discussed. Cluster 1 shows many high contingency values. It comprises the pleustophytic species of the Lemnetea. The isolated position of Utricularia vulgaris, the almost identical contingency profiles of Lemna minor and Spirodela polyrrhiza, the contrast between Lemna gibba versus Lemna trisulca, Riccia fluitans and Ricciocarpus natans, and the strong relation between Hydrocharis and Stratiotes are emphasized.The remaining species are characteristic for the Potametea complex. Cluster 2 represents the competitive species of the magnonymphaeid and magnopotamid growth form while clusters 3 and 4 are composed of parvopotamids and batrachids. As to cluster 2 the division of the Nymphaeion group into a subset with Myriophyllum verticillatum, Nuphar luteum and Nymphaea alba and one with Trapa natans and Nymphoides peltata, the strong correlation of Potamogeton lucens, P. perfoliatus, Myriophyllum spicatum and Ranunculus circinatus, the connecting position of Ceratophyllum demersum and the isolated position of Polygonum amphibium are emphasized. Cluster 3 is subdivided into several overlapping subgroups. Remarkable is the contrast of stenotopic species groups (Najas marina, Potamogeton gramineus; Callitriche hamulata, Myriophyllum alterniflorum) and eurytopic species groups (Potamogeton pectinatus, P. pusillus; P. crispus, P. friesii; Callitriche platycarpa, Ranunculus peltatus). A clear division into Parvopotamion- and Callitricho-Batrachion-species cannot be found. Hydrophytic differential species of a Ranunculion fluitantis are also absent. Hottonia palustris shows special relations to a group of mesotrophic species.Cluster 4 is closely related to several subgroups of cluster 3. The high contingency coefficients are caused by the common occurrence of these species in calcium-rich running waters. Hippuris vulgaris shows a distribution which is very difficult to interpret. Potamogeton coloratus is another rather isolated species.Finally, the ordination of species by phytosociological affinity is compared with the hydrochemical data for 31 species that are frequent in southern Lower Saxony (ef. Wiegleb 1976). It is estimated that the hydrochemistry accounts for only 20 to 25 percent of the observed phytosociological variance. Other factors, e.g. water depth, motion, and temperature may not be neglected.

Die Nomenklatur der höheren Pflanzen folgt Ehrendorfer, F. 1973. Liste der Gefäßpflanzen Mitteleuropas. 2. Aufl. Fischer, Stuttgart.     

High-affinity binding of fungal β-glucan elicitors to cell membranes of species of the plant family Fabaceae

Microsomal preparations of six species of the plant family Fabaceae were screened for high-affinity binding of branched (1 3), (1 6)--glucans. Oligoglucosides of this type are specific elicitors of phytoalexin accumulation in soybean (Glycine max L.), a member of this family. The species studied were alfalfa (Medicago sativa L.), broadbean (Vicia faba L.), chickpea (Cicer arietinum L.), french bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), and white lupin (Lupinus albus L.). A ¹²⁵I-labeled 4-(2-aminophenyl)ethylamine conjugate of a (1 3), (1 6)--glucan fraction with an average degree of polymerization (DP) of 18, obtained from mycelial walls of Phytophthora sojae, was used as radioligand for initial screening. The structural complexity of this fraction allowed the identification of binding sites with affinities for isomeric structures other than the (1 3), (1 6) hepta--glucoside for which soybean binding sites display highest affinity. Radioligand competition experiments against unlabeled fungal -glucan resulted in the identification of high-affinity binding in alfalfa, bean, lupin, and pea. Half-maximal competition concentrations (IC₅₀) for fungal -glucan in these species were between 5 and 30 nM. Pseudoheterologous radioligand competition by unlabeled hepta--glucoside showed that for alfalfa, lupin and pea the IC₅₀ values for this structure (4 to 16 nM) were similar to those of soybean (7.7 nM). Bean microsomes, however, displayed an IC₅₀ significantly higher than soybean (68 nM) suggesting that the structural motif recognized by its binding sites is not identical to that of soybean or the other three species. Radioligand saturation assays with alfalfa, lupin and pea microsomes using an ₁₂₅I-labeled aminophenylethylamine hepta--glucoside conjugate gave dissociation constants (K_d) of 5.3, 3.7, and 1.8 nM, respectively. The affinity of these sites for hepta- glucoside was in the same range as that of soybean (K_d 1–3 nM), whereas the affinity of the binding sites of bean for the same ligand was significantly lower (K_d = 33 nM). Good correlation was found between the presence of high-affinity binding and the accumulation of isoflavonoid phytoalexins in roots of alfalfa, bean, chickpea and pea seedlings after exposure to fungal -glucan. Lupin displayed a strong wound-induced accumulation of prenylated isoflavones which was independent of the presence of -glucan, making it impossible to determine phytoalexin induction in response to elicitor. No specific binding or phytoalexin accumulation in response to glucans was observed in broadbean. This is the first report on the existence of possibly homologous elicitor-binding sites within a plant taxonomic family and may provide preliminary evidence for putative evolutionary relationships in pathogen perception mechanisms in plants.Abbreviations DP degree of polymerization - EC₅₀ concentration of elicitor necessary to obtain a half-maximal biological response - HG synthetic (1 3), (1 6)-hepta--glucoside phytoalexin elicitor - HG-APEA 1-[4-(2-aminophenyl)ethylamino-1-hexaglucosyl]deoxyglucitol - IC₅₀ ligand concentration necessary to obtain half-maximal displacement of radioligand in competition binding assays - K_d dissociation constant - OS branched (1 3), (1 6)--glucan obtained by hydrolysis of mycelial walls of Phytophthora sojae - OS-APEA 1-[4-(2-armnophenyl)ethylamino-1-oligoglucosyl]deoxyglucitol conjugate of OS This work was supported by the Comision Interministerial de Ciencia y Tecnologia grant BI091-0366 (E.G.C.), the Volkswagen-Stiftung (E.G.C. and J.E.), the Deutsche Forschungsgemeinschaft, SFB-369 (J.E.), the Bundesministerium fiir Bildung, Wissenschaft, Forschung und Technologie (J.E.), Fonds der Chemischen Industrie (J.E.) and the EU Human Capital and Mobility Program (J.E. and E.G.C.).     

Toxic responses of germinating pollen and soybeans to aflatoxins

Aflatoxin producing strains of Aspergillus grow on soybeans thereby contaminating the latter through secretion of the toxin. Investigations dealing with either soybean seed germination or intact seedling growth responses to aflatoxin (B₁) are lacking. Similarly, a possible interaction of aflatoxins with phosphate in the germination and elongation of both soybeans and pollen as well as roots of the former and tubes of the latter has not been examined. Imbibition of Glycine max, cv. Essex seeds for 18 hours in solutions containing 0.38, 2.90, 5.80 or 11.60 g/ml (AFB₁) yielded% germination inhibitions of 5, 20, 40 and 80, respectively. By 36 hours these were 6, 4, 13 and 19 % for the same toxin concentration series. At 140 hours attached root elongation was inhibited 26, 35 and 50 % for 2.90, 5.80 and 11.60 g/ml AFB₁. No effect was noted at 0.38 g/ml AFB₁. Incubation of excised roots in medium containing 3.0 mM KH₂PO₄ stimulated their elongation 3.2 fold. Addition of 33.28 g/ml mixed aflatoxins together with KH₂PO₄ resulted in only a 1.5 fold stimulation. When KH₂PO₄ was added to a culture medium lacking AFB₁, Lilium longiflorum, cv. Ace pollen germination was enhanced 50%. Withholding KH₂PO₂ but supplying AFB₁ did not markedly affect germination. However, supplementing the medium with KH₂PO₄ while simultaneously adding AFB₁ did not inhibit germination at 5 and 10 g/ml but caused 27.3 and 45.1 % declines at 25 and 30 g/ml. In the absence of KH₂PO₄ AFB₁ stimulated pollen tube elongation 7.5, 14.3, 16.5 and 13.2 % at 5, 10, 15 and 20 g/ml but 30 g/ml inhibited it 11.1%. In contrast, tube elongation was suppressed at all AFB₁ concentrations (maximum 36.1% at 30 g/ml) tested upon KH₂PO₄ addition. Results derived from germinating pollen in medium supplemented with KH₂PO₄ or NaH₂PO₄ indicate that the phosphate anion does not preferentially promote aflatoxin-induced inhibition of tube elongation.Aided by grant IN-127 from the American Cancer Society to W.V. Dashek and funds from the Departments of Biology, West Virginia University and Virginia Commonwealth University and the West Virginia University Foundation.     

Lambda transducing phages derived from a FinO- R100::lambda cointegrate plasmid: proteins encoded by the R100 replication/incompatibility region and the antibiotic resistance determinant.

Summary Three transducing phages have been isolated from pEDR20, an R100:: cointegrate plasmid in which the insertion inactivated the R100 finO gene. Physical analysis of the three phages showed that the is inserted at kilobase coordinate 81.3 of R100. All three phages carry different amounts of R100 DNA in the left arm of . Each phage contains IS1b, the mer genes and the region between coordinate 81.3 and 88.6; thus, all contain the genes necessary for R100 replication. One phage, VA73, contains the entire r-determinant of R100 in addition to the above DNA. Five proteins coded by the region between 81.3 and 88.6 were detected. These had subunit molecular weights of 10,400; 12,200; 16,200; 19,600; and 38,300. The first was made constitutively and the other four only from a promoter. Other constitutive proteins were one from the cml fus region with a molecular weight of 22,400 (cml) and two from the str sul region with molecular weights of 31,500 (str?) and 30,100 (sul?). Mercuric ion induced synthesis of at least 10 proteins. Six of these were known from earlier work. The total size of the proteins which appear to derive from the mer genes exceeds by a factor of 1.5, the coding capacity of this region without overlapping genes. Some, or all of these extra proteins may be chromosomal in origin, possibly derepressed in response to mercury gene products.     

Recovery of riverine vegetation after experimental disturbance: a field test of the patch dynamics concept

The Patch Dynamics Concept predicts different recovery patterns of communities after disturbance according to the spatial and temporal heterogeneity of the habitat. The aim of this study was to test the predictions arising from the Patch Dynamics Concept on the recovery of macrophyte communities after an experimental disturbance. The test was based on the comparison of the vegetation recovery in three stations located on former channels of the Rhône River, France, differing by their temporal heterogeneity, which was estimated by the frequency of flood scouring. In each station the experimental disturbance was set up by uprooting the aquatic plants in three experimental sets comprising four 1 m²-plots. The aquatic plants were surveyed in these sets as well as in their reference sets from July to November 1991.As predicted, the most frequently disturbed station recovered its species richness (19 species) and its vegetation cover in less than two months. The biological traits of the species occurring in this station are considered as r-strategies. The species colonizing the experimental sets were not necessarily present on the sets before the disturbance, but occurred regularly on other sites station. The rapidity of the community recovery demonstrates the high resilience of this ecosystem. According to the unpredictable character of its recolonization, the macrophyte community of this station could be said to be founder controlled with competitive lottery for establishment.The station with intermediate temporal heterogeneity was overgrown by some r-selected species but the community recolonization was predictable and this station had intermediate resilience. Its species richness was low (6 species).The less frequently disturbed station presented low resilience with a slow recovery of its community (more than 5 months); the species richness (4 species) and the traits of some species were related to K-strategies while others were related to r-strategies. The macrophyte community of this station could be said to be dominance controlled.Different patterns of recovery of the macrophyte communities of former channels of the Rhône River could be depicted according to their temporal heterogeneity; these patterns were consistent with the hypotheses arising from the Patch Dynamics Concept. However, the competitive lottery appeared to be limited at the scale of our experiment.     

Calcium absorption as an index of root parameters of cucumber (Cucumis sativus L.)

Summary In a solution culture study the absorption of Ca in the shoot of cucumber (Cucumis sativus L.) and various root parameters viz fresh weight, dry weight, length and surface area were measured at weekly intervals. All the root parameters were significantly correlated (p=0.01) with the amount of Ca absorbed when the concentration of Ca was such (5 meq/l) that the absorption capacity of the root membrane was fully saturated. The use of this relationship has been suggested in estimating the amount of roots developed in the soil system where identical conditions exist with respect to Ca concentration. Such estimated values have been termed as equivalent root length or equivalent root surface area as the case may be. P and K flux into the roots growing in the soil system have been worked out from these estimates of root parameters.     

Flood disturbance and riparian species diversity on the Colorado River Delta

We investigated the influence of channel migration and expansion on riparian plant species diversity along the lower Colorado River near the United States–Mexico border. Using repeat aerial photography in a GIS we identified and classed areas of low, moderate, and high disturbance frequency caused by channel expansion and migration. Replicate vegetation plots (12m×12m) were sampled in each of the three disturbance classes. One-way ANOVA was used to test for differences in species richness, species diversity (using the Shannon–Weiner Index) and overall percent ground cover of plants between the three disturbance classes. Regardless of disturbance class, plots were dominated by trees or shrubs, especially the non-native Tamarix ramosissima, as well as Pluchea sericea, Baccharis salicifolia and Salix goodingii. Clearly woody species constitute the great bulk of overall species richness, percent ground cover, and species diversity (H) in each disturbance group. No overall statistically significant differences were revealed among the disturbance groups for values of species richness, percent ground cover, or the Shannon–Wiener Index, though paired contrasts of means revealed that total percent ground cover on low disturbance plots was significantly higher than on moderately disturbed plots. Spatial and temporal variability in riparian diversity in the study area appears to hinge on factors other than disturbance frequency such as salt or drought stress. Alternately, our results could be interpreted as suggesting that in the presence of intensive flow regulation, disturbance plays a secondary role to ecological stresses, similar to that demonstrated by others. Intentional flood pulses are advocated as a restorative management strategy for improving plant productivity, management of exotic species (particularly T. ramosissima), and restoration of overall biodiversity.     

Expansins in the bryophyte Physcomitrella patens

Expansins are cell wall proteins which play a key function in basic processes of plant growth and differentiation. It has been proposed that expansins are likely to be present in all land plants and, to date, they have been reported in angiosperms, gymnosperms and pteridophytes. In this paper, we provide the first report and analysis of genes encoding expansin-like proteins in the bryophyte, Physcomitrella patens. Our analysis indicates that both - and -expansins are present as gene families in this plant and expression analysis indicates that these genes are subject to a complex regulation by both hormonal and environmental factors. In particular, the expression of many expansin genes in P. patens is upregulated by stress conditions, suggesting that they play a role in the specific cellular differentiation displayed by P. patens in response to such stress. Finally, we provide the first report on the generation and analysis of a series of knockout mutants for individual expansin genes. Abbreviations: IAA, indole-acetic acid; BAP, 6-benzylaminopurine; ABA, abscisic acid; npt, neomycin phospotransferase; KO, knockout     

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.     

Physical and Epitope Analysis of a Recombinant Human T-Cell Receptor Vα/Vβ Construct Support the Similarity to Immunoglobulin

The genetic organization and protein structure of T-cell receptors (TCR) and immunoglobulins (Ig) are remarkably similar. Through recombinant, physical, and peptide-based immunological studies we demonstrated that rabbit antisera generated against a recombinant single-chain TCR (scTCR) react with defined peptide epitopes of their constituent TCR and chains. These antisera cross-react with the light-chain Mcg as well as with peptides duplicating its covalent structure. Conversely, rabbit antisera generated to human light chains cross-reacted with the recombinant scTCR. Rabbit anti- antibodies purified on an scTCR affinity column bound to T-cell lines and to T and B lymphocytes from peripheral blood. Circular dichroism analysis demonstrated plots characteristic of -sheets for both Mcg and recombinant scTCR. Antisera directed against TCR -chain synthetic peptides reacted with scTCR, Mcg light-chain protein, synthetic peptides from regions of sequence homology in -chains, and Mcg. Based upon this homology and the serological cross-reactions which reflect conformational determinants, we suggest that the V/V antigen-binding domain of this particular monoclonal scTCR construct is substantially similar to the conformational structure of light chains.     

Effect of stalk damage on growth and yield of certain maize cultivars by the maize stalk borer Chilo partellus

The effects of different degrees of stem tunneling caused by different levels of artificial infestation by the larvae of Chilo partellus (Swinhoe) on growth and yield of 4 maize cultivars were studied. The susceptible Inbred A suffered much more tunneling than ICZ1-CM, ICZ2-CM and Katumani Composite B. This tunneling influenced significantly the plant growth of all the four cultivars. There was a significant negative correlation between tunneling and yield for the cultivars Inbred A and Katumani Composite B, but such a relationship was not significant for ICZ1-CM and ICZ2-CM. Such differences in the relationships between tunneling and yield among the 4 cultivars are due to different degrees of tunneling caused by C. partellus larvae to the plants of these cultivars.

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Résumé L'étude a porté sur la croissance et la production avec différents niveaux de minage des tiges de 4 cultivars de maïs, lors de divers degrés de contamination artificielle par des chenilles de C. partellus. Le cultivar sensible Inbred A souffre plus des mines de C. partellus que ICZ1-CM, ICZ2-CM et Katumani composite B. Les mines influent significativement sur la croissance des 4 cultivars. Il y a une corrélation négative significative entre le minage des tiges et la production pour les cultivars Inbred A et Katumani composite B, mais la relation n'est pas significative pour ICZ1-CM et ICZ2-CM. Les différences entre le minage des tiges et la récolte des 4 cultivars sont dues aux différents degrés de minage des tiges de ces cultivars par C. partellus.

     

Strong genetic differentiation of the East-Himalayan <Emphasis Type="Italic">Megacodon stylophorus</Emphasis> (Gentianaceae) detected by Inter-Simple Sequence Repeats (ISSR)

Megacodon stylophorus (Clarke) Smith is a perennial alpine herb endemic to the species-rich eastern Himalayan region. Its populations are locally scattered as isolated patches throughout this region. Genetic variation within and among six populations of this species was assessed using ISSR fingerprinting with 13 primers. High levels of genetic diversity exist within species (P = 69.83%, H_T = 0.1949 and H_sp = 0.3047), while the within-population diversity is low (P = 11.21%, H_E = 0.0532 and H_pop = 0.0792). Extraordinarily high levels of genetic differentiation were detected among populations based on various statistics, including Neis genetic diversity analysis (72.7%), Shannons diversity index (74.01%) and AMOVA (80.70%). That is, populations shared low levels of genetic identity (I = 0.8203 ± 0.0430). This genetic structure was probably due to severe genetic drift of the small-sized patchy populations resulting from postglacial habitat fragmentations. The observed genetic structure of the populations implies that as many populations as possible should be considered for any in situ and ex situ conservation practice on this species.     

Thermodynamics of all-or-none water channel closure in red cells

Summary The relation of osmotic to diffusional water permeability of human red blood cells was compared after treating the cells with different concentrations of PCMBS (p-chloromercuribenzene sulfonate). After subtracting the PCMBS-insensitive permeability (presumably the water permeability of the lipid bilayer) from each, the ratio of osmotic to diffusional permeability remains invariant (11) as more and more water channels are inhibited by increasing concentrations of PCMBS. This result implies that the channels close in an all-or-none way and suggests a two-state model. Analysis of the dependence of osmotic water permeability on PCMBS concentration in terms of the model reveals a 11 stoichiometry and a dissociation constant for the PCMBS/membrane receptor complex of about 0.019mm at 37°C. Temperature dependence studies show that the reaction is entropically driven (H ^o25 kcal/mol, S ^o100 cal/moldeg) and suggest the involvement of hydrophobic interactions.     

On the mode of antirepressor action in anti-immune cells

Summary The mode of antirepressor action in anti-immune cells was analysed in respect to its two main features, low lysogenization and high cell killing. By means of complementation experiments between and i434 in anti-immune cells, it was shown that the antirepressor no longer channels phages towards lysis in such cells if the genes which are needed for lysogenization are provided in trans by the heteroimmune phage i434. Since complementation could be demonstrated, it was possible to exclude that direct action of the antirepressor over repressor production is responsible for the feature under analysis. It was also shown that both int- and cII-product are required to improve lysogenization and to prevent high levels of killing.Recipient of an EMBO predoctoral fellowship.     

Microbial oxidation of alpha-pinene by Serratia marcescens

Summary A strain of the bacterium Serratia marcescens, isolated from sewage sludge, can oxidise the terpene hydrocarbon -pinene to produce rans-verbenol as the major product, with verbeone and trans-sobrerol as minor products. A change in nitrogen source and inclusion of glucose as a second carbon source caused the bacterium to produce -terpineol as the major oxidation product. Products were identified by gas liquid chromatography and mass spectrometry.     

Comparative Analysis of the Mechanisms Underlying Nifedipine-Induced Blockade of Three Subtypes of T-Type Ca2+ Channels

We analyzed the effects of nifedipine on a family of recombinant low-threshold Ca²⁺ channels functionally expressed in Xenopus oocytes and formed by three different subunits (1G, 1H, and 1I). The 1G and 1I channels demonstrated a low sensitivity to nifedipine even in high concentrations (IC₅₀ = 98 and 243 M, maximum blocking intensity A_max = 25 and 47%, respectively). At the same time, the above agent effectively blocked channels formed by the 1H-subunit (IC₅₀ = 5 M and A_max = 41%). The nifedipine-caused effects were voltage-dependent, and their changes depended on the initial state of the channel. In the case of 1G-subunits, the blockade was determined mostly by binding of nifedipine with closed channels, whereas in the cases of 1H- and 1I-subunits this resulted from binding of nifedipine with channels in the activated and inactivated states. The obtained data allow us to obtain estimates of the pharmacological properties of the above three subtypes of recombinant channels and, in the future, to compare these characteristics with the properties of low-threshold Ca²⁺ channels in native cells.     

Structure and floristic composition of the Heard Island “pool complex” community

Summary The stratigraphy, hydrology and vegetation of the Heard Island (sub-Antarctic; 53°05S, 73°30E) pool complex bogs are described. Spatial variation in processes that might have contributed to their formation are discussed. This community occurs where drainage is impeded. with Callitriche antarctica being the indicator species. Particular attention is paid to the interaction of the vegetation, pools and animals. Surface stratigraphy, peat depth, water depth and vegetation composition were measured along transect lines. Species cover abundance data of 300 quadrats were classified using a two-way indicator species analysis program and ordinated using detrended correspondence analysis. The major factors determining vegetation composition were found to be peat depth, surface topography, and the degree and type of animal disturbance. Similarities between the pool complexes on Heard Island and corresponding bogs in Tasmania, and the northern hemisphere temperate and boreal zones appear to diminish as the density of the animals occupying this habitat increases.     

Improvement on laboratory fermentation equipment to study Saccharomyces cerevisiae metabolism

Beside being an ordinary fermenter, the present equipment was conceived to sample the medium, to store the samples and to record photographs of the yeasts. Ten sensors were used to measure gas exchanges. During the growth of ScM1 (a Saccharomyces cerevisiae strain) on glucose, we could observe two different linear decreases of CO₂ production rates (18.17±0.12 mmol CO₂ h^–2 (g biomass)^–1 and 8.67±0.12 mmol CO₂ h^–2 (g biomass)^–1), together with a sudden variation of slope during the respiro-fermentative phase. Nomenclature F_in InletairFlowl h ^–1 F_out OutletgasFlowl h ^–1 _in Inletairtemperature°C_out Outletgastemperature°CP _atm AtmosphericPressuremmHgP _in InletairOverPressuremmHgP _out OutletgasOverPressuremmHgDODissolvedO ₂ mg l^–1 pO₂ PartialPressureO ₂ in Outlet gas % (v/v) pCO₂ PartialPressureCO ₂ in Outlet gas % (v/v) Int(t) Whole number of hours