Combined preparative enzymatic synthesis of dTDP-6-deoxy-4-keto-D-glucose from dTDP and sucrose

dTDP–6–deoxy–4–keto–D–glucose (1), the common intermediate in the biosyntheses of the mainfold deoxysugars, was synthesized on a gram–scale by the combination of sucrose synthase and dTDP–D–glucose 4,6–dehydratase in a fed batch, starting the reaction with dTDP. This process allowed a dTDP conversion with a 100% rate. An easy and efficient three–step purification with anion–exchange chromatography and gel filtration gave 1.1 g of 1 in an overall yield of 73%. This work realizes a first step for an economic access to activated deoxysugars.     

[H]WAY–100635 for 5–HT1A receptor autoradiography in human brain: a comparison with [H]8–OH–DPAT and demonstration of increased binding in the frontal cortex in schizophrenia

WAY–100635 is the first selective, silent 5–HT_1A (5-hydroxytryptamine_1A, serotonin-1A) receptor antagonist. We have investigated the use of [³H]WAY–100635 as a quantitative autoradiographic ligand in post-mortem human hippocampus, raphe and four cortical regions, and compared it with the 5–HT_1A receptor agonist, [³H]8–OH–DPAT. Saturation studies showed an average Kd for [³H]WAY–100635 binding in hippocampus of 1.1 nM. The regional and laminar distributions of [³H]WAY–100635 binding and [³H]8–OH–DPAT binding were similar. The density of [³H]WAY–100635 binding sites was 60–70% more than that of [³H]8–OH–DPAT in all areas examined except the cingulate gyrus where it was 165% higher. [³H]WAY–100635 binding was robust and was not affected by the post-mortem interval, freezer storage time or brain pH (agonal state). Using [³H]WAY–100635, we confirmed an increase of 5–HT_1A receptor binding sites in the frontal cortex in schizophrenia, previously demonstrated with [³H]8–OH–DPAT. Compared to [³H]8–OH–DPAT, [³H]WAY–100635 has two advantages: it has a higher selectivity and affinity for the 5–HT_1A receptor, and it recognizes 5–HT_1A receptors whether or not they are coupled to a G-protein, whereas [³H]8–OH–DPAT primarily detects coupled receptors. Given these considerations, the [³H]WAY–100635 binding data in schizophrenia clarify two points. First, they indicate that the elevated [³H]8–OH–DPAT binding seen in the same cases is attributable to an increase of 5–HT_1A receptors rather than any other binding site. Second, the enhanced [³H]8–OH–DPAT binding in schizophrenia reflects an increased density of 5–HT_1A receptors, not an increased percentage of 5–HT_1A receptors which are G-protein-coupled. We conclude that [³H]WAY–100635 is a valuable autoradiographic ligand for the qualitative and quantitative study of 5–HT_1A receptors in the human brain.     

Experimental studies of rapid bioerosion of coral reefs in the Galápagos Islands

Experimental carbonate blocks of coral skeleton,Porites lobata (PL), and cathedral limestone (LS) were deployed for 14.8 months at shallow (5–6 m) and deep (11–13m) depths on a severely bioeroded coral reef, Champion Island, Galápagos Islands, Ecuador. Sea urchins (Eucidaris thouarsii) were significantly more abundant at shallow versus deep sites.Porites lobata blocks lost an average of 25.4 kg m^–2yr^–1 (23.71 m^–2yr^–1 or 60.5% decrease yr^–1). Losses did not vary significantly at depths tested. Internal bioeroders excavated an average of 2.6 kg m^–2 yr^–1 (2.41 m^–2 yr^–1 or 0.6% decrease yr^–1), while external bioeroders removed an average of 22.8 kg m^–2 yr^–1). (21.31 m^–2 yr^–1). or 59.9% decrease yr^–1). few encrusting organisms were observed on the PL blocks. Cathedral limestone blocks lost an average of 4.1 kg m^–2 yr^–1). (1.81 m^–2 yr^–1). or 4.6% decrease yr-'), also with no relation to depth. Internal bioeroders excavated an average of 0.6 kg m^–2 yr^–1). (0.31 m^–2 yr^–1). or 0.7% decrease yr^–1). and external bioeroders removed an average of 3.5 kg m^–2 yr^–1). (1.51 m^–2 yr^–1). or 3.9% decrease yr^–1). from the LS blocks. Most (57.6%) encrustation occurred on the bottom of LS blocks, and there was more accretion on block bottoms in deep (61.4 mg cm^–2 yr^–1). versus shallow (35.0 mg cm^–2 yr^–1) sites. External bioerosion reduced the average height of the reef framework by 0.2 cm yr^–1). for hard substrata (represented by LS) and 2.3 cm yr^–1). for soft substrata (represented by PL). The results of this study suggest that coral reef frameworks in the Galápagos Islands are in serious jeopardy. If rates of coral recruitment do not increase, and if rates of bioerosion do not decline, coral reefs in the Galápagos Islands could be eliminated entirely.     

Coccidian parasites of four Panamanian lizard species

Eight species of coccidia (Apicomplexa: Eimeriidae) are reported from Panamanian lizards. –Eimeria randolphi n. sp. is a biliary parasite of –Gymnopthalmus speciosus (Gymnopthalmidae) with cylindrical oöcysts, 29.1 × 16.8 m (25.0–31.5 × 15.0–18.5), an oöcyst length/width index (shape-index, SI) of 1.73 (1.46–2.07) and no polar granule or oöcyst residuum. Ovoidal sporocysts are 9.5 × 7.8 m (9.0–10.5 × 7.0–8.5), with an SI 1.21 (1.06–1.43), a sporocyst residuum and no Stieda body. –E. gymnopthalmi n. sp., an intestinal parasite of –G. speciosus, has round to oval oöcysts of 22.4 × 20.5 m (21–24 × 18–23), an SI of 1.09 (1.00–1.28) and no polar granule or oöcyst residuum. Sporocysts are ovoidal, 8.9 × 7.7 m (8–10 × 7–9), with an SI of 1.16 (1.06–1.29), a prominent sporocyst residuum and no Stieda body. –E. lepidophymae n. sp. parasitises the gall-bladder of –Lepidophyma flavimaculatum (Xantusiidae) and has cylindrical oöcysts of 36.7 × 18.5 m (34.0–40.0 × 16.0–20.5), an SI of 1.99 (1.79–2.31) and no polar granule or oöcyst residuum. Sporocysts are ovoidal, 10.3 × 8.8 m (9.0–11.0 × 8.0–9.5 m), with an SI of 1.17 (1.06–1.29), a sporocyst residuum and no Stieda body. –E. limifronsi n. sp. parasitises the intestine of –Anolis limifrons (Polychrotidae). Oöcysts are oval, 22.5 × 16.0 m (20.0–26.0 × 14.5–17.5), an SI of 1.41 (1.18–1.73) and no polar granule or oöcyst residuum. Sporocysts are ovoidal, 8.4 × 7.5 m (7.5–9.0 × 7.0–8.5), an SI of 1.13 (1.00–1.29), a small sporocyst residuum and no Stieda body. –Isospora limifronsi n. sp. parasitises –A. limifrons and has oval to round oöcysts with a rough, pitted wall, 24.5 × 22.4 m (20–27 × 19–25), an SI of 1.09 (1.00–1.23) and no oöcyst residuum or polar granule. Ovoidal sporocysts are 14.7 × 10.2 m (13–17 × 9–13), with an SI of 1.44 (1.27–1.58), a central sporocyst residuum, Stieda body and a prominent, homogeneous sub-Stieda body. –Anolis limifrons is also parasitised by –I. achiotensis n. sp. The oval to round oöcysts are 22.0 × 19.8 m (20–24 × 18–22.5), with a smooth wall, an SI of 1.11 (1.05–1.25) and no oöcyst residuum or polar granule. Sporocysts are ovoidal, 12.6 × 9.5 m (11–14.5 × 7.5–11), have an SI of 1.32 (1.10–1.60), a small central residuum often hidden by sporozoites, and no Stieda or sub-Stieda body. –I. gonatodi n. sp., from –Gonatodes albogularis fuscus, has oval to round oöcysts 23.0 × 21.8 m (20–25 × 19–24), an SI of 1.06 (1.00–1.16) and a variably present oöcyst residuum. Sporocysts, 12.0 × 9.6 m (10–14 × 9–11), with an SI of 1.25 (1.10–1.44), have no Stieda or sub-Stieda body. A sporocyst residuum comprised of loosely adherent or scattered, irregular granules is present. Panamanian –Gonatodes albogularis fuscus are also parasitised by –I. albogularis.     

Coccidian parasites (Apicomplexa: Eimeriidae) of the endemic Florida snake Tantilla relicta Telford (Serpentes: Colubridae)

The endemic Florida snake Tantilla relicta Telford is parasitised by six species of coccidia. Caryospora tantillae n. sp. has nearly spherical oöcysts, 19.6 × 18.9 µm (16–22 × 16–21), with no polar body, and an oöcyst length/width ratio (shape index, SI) of 1.04 (1.00–1.11). Ovoidal sporocysts are 15.1 × 11.6 µm (12–17 × 10–13), with an SI of 1.30 (1.1–1.6), a single prominent Stieda body and a sporocyst residuum. Sporozoites are 14 × 2.5 µm. Caryospora relictae n. sp. also has nearly spherical oöcysts, 18.5 × 17.6 µm (16–22 × 15–20), but is distinguished by having a distinct polar body and a substieda body in sporocysts. The oöcyst SI is 1.05 (1.0–1.2). Sporocysts are ovoidal, 14.8 × 11.4 µm (12–17 × 10–16), with an SI of 1.29 (1.1–1.5) and a sporocyst residuum. Sporozoites are 10–14 × 2–2.5 µm. Isospora cf. wilsoni has ovoidal to spherical oöcysts without a micropyle, measure 17.4 × 17.1 µm (15–19 × 15–19), and have an SI of 1.02 (1.00–1.07). Oöcysts have no polar granule or oöcyst residuum. Sporocysts are ovoidal, 11.4 × 8.2 µm (9–14 × 7–10), with an SI of 1.39 (1.18–1.62). Both a Stieda body and sporocyst residuum are present, but a substieda body, characteristic of I. wilsoni as described, was not observed. Sporozoites are 7–8 × 2.5–3 µm. An Eimeria sp., of which the sample was too small to justify taxonomic designation, has nearly spherical oöcysts without micropyle, a size of 22.5 × 20.9 µm (22–23 × 20–22), an SI of 1.08 (1.00–1.12) and no polar granule. Sporocysts measure 12.5 × 8.9 µm (11–14 × 7–11) and have an SI of 1.44 (1.18–1.87), a sporocyst residuum and no Stieda body. Sporozoites are 13 × 5 µm. Eimeria amphorae n. sp. has ovoidal to spherical oöcysts without a micropyle, a size of 24.8 × 22.3 µm (23–27 × 20–26), an SI of 1.12 (1.02–1.25) and no polar granule or oöcyst residuum. Sporocysts are elongate, 18.4 X 8.0 µm (17-22 × 6-9.5), with an SI 2.33 (1.79–3.00) and no discernible Stieda body or sporocyst residuum. Sporocyst shape differs by orientation, rectangular to amphora-like, tapering abruptly to a blunt point; sporozoites large, 15.5 × 4.2 µm. A biliary parasite, Eimeria pleistocenensis n. sp., has ovoidal to elongate oöcysts, without micropyle, with a size of 27.8 × 19.4 µm (23–32 × 14–23), with an SI of 1.44 (1.17–1.82) and an oöcyst residuum but no polar granule. Sporocysts ovoidal, 10.7 × 8.6 (9–13 × 8–10), with an SI of 1.24 (1.05–1.37), a sporocyst residuum, but without Stieda body; sporozoites 8.8 × 2.7 µm. Similar oöcysts from other Tantilla relicta populations, T. relicta neilli in north Florida T. relicta pamlica in southeastern Florida and T. relicta relicta in south-central Florida, have dimensions that lie within the range of variation in the type population and identically shaped sporocysts that suggest conspecificity with E. pleistocenensis, and presence of the species in the precursor to Tantilla relicta prior to the second interglacial period.     

Deletion analysis of the Brassica napus cruciferin gene cru 1 promoter in transformed tobacco: promoter activity during early and late stages of embryogenesis is influenced by cis-acting elements in partially separate regions

To define sequences in the cruciferin gene cru1 promoter of importance for expression, tobacco (Nicotina tabacum L.) plants were transformed with constructs in which the cru1 promoter, in front of the intact cru1 structural gene, was truncated at –1216, –974, –736, –515, –306, –46 and –17 bp relative to the cap-site. Cru1 expression in tobacco seeds was studied by Northern analysis, Western analysis and in-situ hybridizations. Comparisons of the Northern analysis of RNA from tobacco seeds harvested at 18 d after pollination with the Western analysis of protein from mature seeds showed that the regions between –974 to –736 and –306 to –46 were important for the expression of cru1 at an early developmental stage, whereas the regions –736 to –515 and –515 to –306 were important for expression throughout embryogenesis. By investigating the mRNA levels in transgenic seeds at different stages of development, indications were obtained that the two latter regions exerted their effects during the later stages. The in-situ hybridization showed that cru1 mRNA was distributed in parenchyma cells throughout the embryo in seeds expressing constructs –974 and –736. Constructs –515 and –306 showed an expression restricted to the axis or axis and parts of the cotyledons. Sequence comparisons of the cru1 promoter with other storage-protein gene promoters, identified several motifs implicated in gene regulation. Gel retardation assays with synthetic oligonucleotides showed that a region present in both cru1 and BnC1 promoters, a CANNTG motif, an SEF3 motif, an abscisic-acid-responsive element and an RY-like motif interacted specifically in vitro with DNA-binding proteins present in nuclear extracts from seeds of Brassica napus L. harvested 40 d after pollination.Abbreviations ABA abscisic acid - DAP days after pollination This work was supported by grants from the Swedish Research Council for Forestry and Agriculture and from the Swedish Natural Science Research Council. Ms Ulla Pihlgren, Elisabeth Westergren and Elfi Öhren are acknowledged for expert technical assistance.     

Winter fluxes of methane from Minnesota peatlands

Winter fluxes of methane were investigated in northern Minnesota during 1988–89 and 1989–90. Two bogs and a fen emitted methane throughout the snow-covered season (November through March). Fluxes decreased to a low level of 3–16 mg CH₄ m^–2 d^–1 in late March, reflecting decreasing peat temperatures and (in 1989–90) increasing depth of frost in the peat. Winter fluxes calculated by integration for an open poor fen, an open bog, a forested bog hollow, and a hummock site in the forested bog averaged 49, 12, 13, and 5 mg m^–2 d^–1, respectively, in 1989–1990 (the year most measurements were made). These comprised 11%, 4%, 15%, and 21% of total annual flux.     

Sensitivity of anaerobic sludge biogranule to sulfur compounds

The effects of sulfide, sulfite and sulfate on the methanogenesis in an upflow anaerobic sludge blanket process indicated that their relative toxicity towards degradation of total volatile fatty acid varied as SO42–-S>SO32–-S>S2–. The anaerobic biogranules' activity decreased by 50% when each gram of biomass came into contact with 32, 24 and 16 mg of S2–, SO32–-S and SO42–-S, respectively.     

Reconstituted Cl− pump protein: A novel ion(Cl−)-motive ATPase

Cl^– absorption by theAplysia californica foregut is effected through an active Cl^– transport mechanism located in the basolateral membrane of the epithelial absorptive cells. These basolateral membranes contain both Cl^–-stimulated ATPase and ATP-dependent Cl^– transport activities which can be incorporated into liposomes via reconstitution. Utilizing the proteoliposomal preparation, it was demonstrated that ATP, and its subsequent hydrolysis, Mg²⁺, Cl^–, and a pH optimum of 7.8 were required to generate maximal intraliposomal Cl^– accumulation, electrical negativity, and ATPase activity. Additionally, an inwardly-directed valinomycininduced K⁺ diffusion potential, making the liposome interior electrically positive, enhanced both ATP-driven Cl^– accumulation and electrical potential while an outwardly-directed valinomycininduced K⁺ diffusion potential, making the liposome interior electrically negative, decreased both ATP-driven Cl^– accumulation and electrical potential compared with proteoliposomes lacking the ionophore. Either orthovanadate orp-chloromercurobenzene sulfonate inhibited both the ATP-dependent intraliposomal Cl^– accumulation, intraliposomal negative potential difference, and also Cl^–-stimulated ATPase activity. Both aspects of Cl^– pump transport kinetics and its associated catalytic component kinetics were the first obtained utilizing a reconstituted transporter protein. These results strongly support the hypothesis that Cl^–-ATPase actively transports Cl^– by an electrogenic process.     

Control of the production of individual fusicoccins at different dissolved oxygen concentrations

The regulatory effect of different concentrations of dissolved oxygen on the production of fusicoccins by the fungus Fusicoccum amygdali Del. was studied. The maximum output of total fusicoccins was obtained by using a profiled dissolved oxygen tension (DOT) regime, in which the DOT was maintained at 15–20% during the biomass growth phase and at 5–8% during the fusicoccins production phase. In comparison with the profiled regime, the maintenance of DOT at 15–20% during the whole fermentation shortened the fusicoccins production phase. The fermentation performance at a low DOT (5–8%) inhibited both the accumulation of biomass and the production of fusicoccins. At high DOT (40–50%), an accelerated accumulation of the biomass with an expressed autolysis of mycelia took place, and the production of fusicoccins was lowered. The qualitative composition of individual fusicoccins varied substantially at different DOTs. Fusicoccins, A, C, D, J, H, 16-O-demethyl-J, detretpentenylfusicoccin and some minor fusicoccin metabolites were found in the fermentation broth using the method of liquid secondary ion mass spectrometry. It was established that the profiled DOT regime (15–20% to 5–8%) provided both the maximum concentration of fusicoccins and an enhanced accumulation of the main metabolite – fusicoccin A (FC A). The performance of the fermentation at a DOT of 15–20% decreased the content of FC A by 2–6% in comparison with the profiled DOT regime, and increased the content of fusicoccin C to 14–20% of the total fusicoccins. Fermentation at DOT of 5–8% was characterized by the highest content of the precursors of FC A, the less oxidized fusicoccins H and J, the contents of which were in range 7–12% and 16–17% of total fusicoccins, respectively.     

Improved operation of a dextran bioreactor-separator through variation of enzyme activity, viscosity, centrifugal parameters and rotor design

Viscosity regulation allowed the sedimentation of dextran to be increased from 1.89 to 2.89 g.h–1 within a novel centrifugal bioreactor. At an enzyme activity of 187 U, dextran pelleting was 1.66 mg g.h–1. U which was 50% greater than at an enzyme activity of 1344 U. Reactor productivity, at 1.5–2 g.h–1, was similar for both batch and semi-continuous trials. Rotor core design influenced productivity. © Rapid Science Ltd. 1998     

Phosphoinositide hydrolysis increase by angiotensin-(1--7) in neonatal rat brain

Angiotensin (Ang)-(1–7) is an endogenous peptide hormone of the renin–angiotensin system which exerts diverse biological actions, some of them counterregulate Ang II effects. In the present study potential effect of Ang-(1–7) on phosphoinositide (PI) turnover was evaluated in neonatal rat brain. Cerebral cortex prisms of seven-day-old rats were preloaded with [³H]myoinositol, incubated with additions during 30 min and later [³H]inositol-phosphates (IPs) accumulation quantified. It was observed that PI hydrolysis enhanced 30% to 60% in the presence of 0.01 nM to 100 nM Ang-(1–7). Neither 10 nM [D-Ala⁷]Ang-(1–7), an Ang-(1–7) specific antagonist, nor 10 nM losartan, an angiotensin II type 1 (AT₁) receptor antagonist, blocked the effect of 0.1 nM Ang-(1–7) on PI metabolism. The effect of 0.1 nM Ang-(1–7) on PI hydrolysis was not reduced but it was even significantly increased in the simultaneous presence of [D-Ala⁷]Ang-(1–7) or losartan. PI turnover enhancement achieved with 0.1 nM Ang-(1–7) decreased roughly 30% in the presence of 10 nM PD 123319, an angiotensin II type 2 (AT₂) receptor antagonist. The antagonists alone also enhanced PI turnover. Present findings showing an increase in PI turnover by Ang-(1–7) represent a novel action for this peptide and suggest that it exerts a function in this signaling system in neonatal rat brain, an effect involving, at least partially, angiotensin AT₂ receptors.     

Reception of millimeter-band electromagnetic radiation by the ampullae of Lorenzini of skates

During recording of impulse activity from single nerve fibers of electroreceptors of the ampullae of Lorenzini of skates, we studied the responses to electromagnetic radiation (EMR) at a frequency of 37–55 GHz and an intensity of 1–100 mW/cm².Exposure of the ampullar canal pore to EMR at an intensity of 1–5 mW/cm² and a distance of 1–10 mm evoked a transient increase in the frequency of low-threshold receptor activity (current threshold was 0.04–0.2 µA). An increase in EMR intensity by more than 8–10 mW/cm² produced, together with elevation of receptor activity, an inhibition due to a rise in temperature of 1–3°C in the region exposed. The phase of increase in frequency of activity was absent in high current-threshold receptors (0.3–2.0 µA) when exposed to EMR. The receptors responded to irradiation of the ampullar canal pore at a distance of 15–20 mm by an increase in discharge frequency for 20 min. Direct irradiation of the ampullae of Lorenzini induced only inhibitory responses in receptor cells regardless of their excitability.The results obtained indicate that the sensory receptors of vertebrates are sensitive to EMR. It is concluded that the excitatory effects are due to direct reception of EMR by electroreceptors, and the inhibitory effects are related to local heating of the Lorenzini ampullar pore.Neirofiziologiya/Neurophysiology, Vol. 25, No. 5, pp. 325–329, September–October, 1993.     

Effects of Desmin Gene Knockout on Mice Heart Mitochondria

In heart tissue from mice lacking the intermediate filament (IF) desmin, mitochondria show an abnormal shape and distribution (Thornell et al., 1997). In the present study we have isolated heart mitochondria from desmin null (D–/–) and control (D+/+) mice, and analyzed their composition by SDS–PAGE, immunoblotting, and enzyme measurements. We found both in vitro and in situ that the conventional kinesin, the microtubule-associated plus-end directed motor, was frequently associated with D+/+ heart mitochondria, but not with D–/– heart mitochondria, suggesting that the positioning of mitochondria in heart is a dynamic event involving the IF desmin, the molecular motor kinesin, and, most likely, the microtubules (MT) network. Furthermore, an increased capacity in energy production was found, as indicated by a threefold higher creatine kinase activity in heart mitochondria from D–/– compared to D+/+ mice. We also observed a significantly lower amount of cytochrome c in heart mitochondria from D–/– mice, and a relocalization of Bcl-2, which may indicate an apoptotic condition in the cell leading to the earlier reported pathological events, such as cardiomyocytes degeneration and calcinosis of the heart (Thornell et al., 1997).     

Two new coccidia (Apicomplexa:Eimeriidae) from the green peacock (Pavo muticus) from Saudi Arabia

Two new species of Eimeria were found from faecal samples of ten green peacocks (Pavo muticus) collected at Al-Kharj area, a central region of Saudi Arabia. Sporulated oocysts of Eimeria mutica n.sp. are ellipsoidal 23.1×17.4 (22.4–25.0×16.7–18.9) μm, with a smooth bilayered wall. A micropyle and bilobed polar body are present, but without an oocyst residuum. The sporocyst is an elongated-ovoid 13.7×6.2 (12.0–14.2×5.4–6.7) μm, with a Stieda body and a residuum. Sporulated oocysts of E. kharjensis n.sp. are subspherical 20.3×17.7 (19.0–21.5×16.2–18.7) μm, with a two layered wall and a single polar body. The micropyle is covered by a dome-shaped cap and the sporocyst is an elongate-ovoid 12.7×6.3 (11.9–13.5×5.4–6.8) μm, with a Stieda body. The sporocyst residuum is present as several small granules.     

Influence of up-flow velocity on the performance of an anaerobic filter under oleic acid overloads

An upflow velocity of 0.21 m h^–1 was optimal to minimize the effect of organic shocks (from 6 to 30 kg COD m^–3 d^–1) when operating an upflow anaerobic filter for the treatment of an oleic acid-based effluent (50% w/v COD). This value represented the transition between a mass transfer controlled regime and a kinetic regime. Under hydraulic shock loads, an increase in upflow velocity from 0.3 to 0.4m h^–1 decreased the removal efficiency from 68 to 51%.     

Effects of cold adaptation and noradrenaline on thermosensitivity of rat hypothalamic neurons studiedin vitro

The experiments performed on rat brain slices have shown that cold adaptation of an animal influences the thermosensitivity of hypothalamic medial preoptical neurons. The adaptation is followed by an increase in the proportion of 38–41°C-thermoresponsive neurons and by a decrease in the proportion of 35–38°C-thermoresponsive units. In control animals, noradrenaline (NA) increased the responses of hypothalamic neurons to the action of 35–38°C temperature and decreased them to the action of 38–41°C temperature. Cold adaptation prevented the effects of NA on neuronal thermosensitivity, which suggests that their NA sensitivity is modified by cold adaptation.Neirofiziologiya/Neurophysiology, Vol. 26, No. 3, pp. 171–176, May–June, 1994.     

Growth kinetics ofSaccharomyces cerevisiae in batch and fedbatch cultivation using sugarcane molasses and glucose syrup from cassava starch

Growth kinetics ofSaccharomyces cerevisiae in glucose syrup from cassava starch and sugarcane molasses were studied using batch and fed-batch cultivation. The optimum temperature and pH required for growth were 30°C and pH 5.5, respectively. In batch culture the productivity and overall cell yield were 0.31 g L^–1 h^–1 and 0.23 g cells g^–1 sugar, respectively, on glucose syrup and 0.22 g L^–1 h^–1 and 0.18 g cells g^–1 sugar, respectively, on molasses. In fed-batch cultivation, a productivity of 3.12 g L^–1 h^–1 and an overall cell yield of 0.52 g cells g^–1 sugar in glucose syrup cultivation and a productivity of 2.33 g L^–1 h^–1 and an overall cell yield of 0.46 g cells g^–1 sugar were achieved in molasses cultivation by controlling the reducing sugar concentration at its optimum level obtained from the fermentation model. By using an on-line ethanol sensor combined with a porous Teflon^® tubing method in automating the feeding of substrate in the fed-batch culture, a productivity of 2.15 g L^–1 h^–1 with a yield of 0.47 g cells g^–1 sugar was achieved using glucose syrup as substrate when ethanol concentration was kept at a constant level by automatic control.     

Relative hydrophobicity of organic compounds measured by partitioning in aqueous two-phase systems

Partitioning of a variety of organic compounds, the majority of which represent therapeutic drugs, was examined in an aqueous dextran–polyethylene glycol (Dex–PEG) two-phase system containing 0.15 M NaCl in 0.01 M sodium phosphate buffer at pH 7.3 and in an octanol–buffer (0.15 M NaCl in 0.01 M sodium phosphate buffer, pH 7.3) system. The possibility of introducing compounds to be partitioned in an aqueous two-phase system with dimethyl sulfoxide, and the effect of this solvent on the solute partitioning was explored. Relative hydrophobicity of the compounds was estimated and expressed in equivalent numbers of methylene units. Comparison of the results obtained for several subsets of compounds in the octanol–buffer and in aqueous Dex–PEG two-phase systems clearly demonstrates the advantage of aqueous two-phase partitioning for the hydrophobicity measurements over partitioning in octanol–buffer system.     

By-product formation by a novel glycerol-producing yeast,Candida glycerinogenes,with different O2 supplies

Candida glycerinogenes is an aerobe which does not depend on sulphite for production of glycerol. With a sufficient O₂ supply, up to 130 g glycerol l^–1 was produced with 2.6 g acetic acid l^–1 as by-product. However, with an insufficient O₂ supply – with higher volumes of medium or at higher corn steep liquid concentrations – the glycerol concentration was lower because the by-products, ethanol, pyruvate and lactic acid, were produced in greater amounts, up to 45 g l^–1, 4.3 g l^–1, 1.6 g l^–1, respectively, whereas, less acetic acid (0.6 g l^–1) was produced. In addition, ethanol decreased to 0.4 g l^–1 and the glycerol yield improved from 34 to 50% (w/w) by adding 50 g sulphite l^–1, nevertheless, acetic acid increased to 7.8 g l^–1.