Existence and uniqueness of a sharp travelling wave in degenerate non-linear diffusion Fisher-KPP equations

In this paper we use a dynamical systems approach to prove the existence of a unique critical value c ^* of the speed c for which the degenerate density-dependent diffusion equation u _ct = [D(u)u _x ] _x + g(u) has: 1. no travelling wave solutions for 0 < c < c ^*, 2. a travelling wave solution u(x, t) = (x - c ^* t) of sharp type satisfying (– ) = 1, () = 0 ^*; '(^*–) = – c ^*/D'(0), '(^*+) = 0 and 3. a continuum of travelling wave solutions of monotone decreasing front type for each c > c ^*. These fronts satisfy the boundary conditions (– ) = 1, '(– ) = (+ ) = '(+ ) = 0. We illustrate our analytical results with some numerical solutions.     

Laboratory culture studies of Trichodesmium isolated from the Great Barrier Reef Lagoon, Australia

Cultures of Trichodesmium from the Northern and Southern Great Barrier Reef Lagoon (GBRL) have been established in enriched seawater and artificial seawater media. Some cultures have been maintained with active growth for over 6years. Actively growing cultures in an artificial seawater medium containing organic phosphorus (glycerophosphate) as the principal source of phosphorus have also been established. Key factors that contributed to the successful establishment of cultures were firstly, the seed samples were collected from depth, secondly, samples were thoroughly washed and thirdly, incubations were conducted under relatively low light intensities (PAR 40–50molquantam^–2s^–1). N₂ fixation rates of the cultured Trichodesmium were found to be similar to those measured in the GBRL. Specific growth rates of the cultures during the exponential growth phase in all enriched media were in the range 0.2–0.3day^–1 and growth during this phase was characterised by individual trichomes (filaments) or small aggregations of two to three trichomes. Characteristic bundle formation tended to occur following the exponential growth phase, which suggests that the bundle formation was induced by a lack of a necessary nutrient e.g. Fe. Results from some exploratory studies showed that filament-dominated cultures of Trichodesmium grew over a range of relatively low irradiances (PAR 5–120molquantam^–2s^–1) with the maximum growth occurring at 40–50molquantam^–2s^–1. These results suggest that filaments of the tested strain are well adapted for growth at depth in marine waters. Other studies showed that growth yields were dependent on salinity, with maximum growth occurring between 30 and 37psu. Also the cell yields decreased by an order of magnitude with the reduction of Fe additions from 450 to 45nM. No active growth was observed with the 4.5nM Fe addition.     

Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.     

The solution structure of rat Aβ-(1–28) and its interaction with zinc ion: insights into the scarcity of amyloid deposition in aged rat brain

The amyloid -peptide (A) is a major component of insoluble amyloid deposits in Alzheimers disease, and the ability of the -peptide to exist in different conformations is dependent on residues 1–28 [-(1–28)]. However, different from humans, no A amyloid deposition has been found in aged rats brains. Studying the three-dimensional solution structure of rat A-(1–28) and the binding circumstance of Zn²⁺ is beneficial to a clear understanding of the potential role of Zn²⁺ in Alzheimer-associated neuropathogenesis and to suggest why there is no amyloid deposition in aged rats brains. Here we used nuclear magnetic resonance (NMR) spectroscopy to determine the solution structure of rat A-(1–28) and the binding constant of Zn²⁺ to rat A-(1–28). Our results suggest that (1) the three-dimensional solution structure of rat A-(1–28) is more stable than that of human A-(1–28) in DMSO-d₆ and that a helical region from Glu16 to Val24 exists in the rat A-(1–28); (2) the affinity of Zn²⁺ for rat A-(1–28) is lower than that for human A-(1–28) and the NMR data suggest that Arg13, His6, and His14 residues provide the primary binding sites for Zn²⁺; and (3) the proper binding of Zn²⁺ to rat A-(1–28) can induce the peptide to change to a more stable conformation.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00775-004-0556-xAbbreviations A amyloid -peptide - AD Alzheimers disease - hA-(1–28) human A-(1–28) - rA-(1-28) rat A-(1–28) - REM restrained energy minimization     

Freeze-fracture studies on the cockroach hemocyte membrane complex: Symmetric and asymmetric membrane particle distributions

Summary Freeze-fracture studies were conducted on the membranes of normal cockroach hemocytes. The plasmalemma is asymmetric with the A fracture face containing 80–100 Å membrane intercalated particles at a concentration of 2500/². The B fracture face contains 120–150 Å particles with a relatively low density (800/²). The nuclear envelope displays an asymmetry with the A fracture face containing 1500 particles/² and the B face containing 300/ ². No significant particle size differences were observed in nuclear envelope fracture faces. Two types of symmetric membranes were also found in these cells. Both A and B fracture faces of the membrane surrounding the numerous cytoplasmic inclusion bodies contain particle sizes and concentrations similar to the B face of the plasmalemma. A second type of symmetry was observed in cells apparently engaged in exocytosis. Vesicles (0.1 D) from this process were completely particle free on both fracture faces. Such particle free vesicles could be found in the cytoplasm, attached to the plasmalemma, or completely separated from the cell.Supported by a Pharmaceutical Manufacturers Association Foundation Fellowship.The author wishes to thank Ms. Annalena K. Charla for assistance in plate preparation, Dr. Julius Schultz and the Papanicolaou Cancer Research Institute for use of the freeze-etch device, and Dr. David Smith for the electron microscope facilities.     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

Proliferation and germination of somatic embryos from embryogenic suspension cultures in <Emphasis Type="Italic">Phœnix dactylifera</Emphasis>

The present study demonstrates a procedure for the rapid development of a high number of somatic embryos from embryogenic suspension culture. This method might be efficient for mass propagation of Phnix dactylifera L. Embryogenic callus placed in liquid medium with 10^–5M ABA yielded an average 72 embryos per 100ml of culture medium within 2months, while those placed on solid medium yielded an average of 33, 20 and 16 embryos per 100ml of culture medium respectively for 10^–7, 10^–6 and 10^–5 M ABA after 4months. The combination of 2,4-DIchlorophenoxyacetic acid (2,4-D) (4.5×10^–7M), glutamine (6.7×10^–4M), and ABA (10^–5M) (L8 liquid medium) showed a beneficial effect on somatic embryos production compared to 2,4-D and glutamine alone, while this combination significantly (p<0.05) increased the accumulation of storage proteins (144 and 138mgg^–1 DW respectively for Jihel and Bousthami noir cultivars) in somatic embryos. The somatic embryos which underwent maturation on medium containing only 4.5×10^–7M 2,4-D and 10^–5M ABA (L6 liquid medium) accumulated more sugars (292 and 265mgg^–1 DW respectively for Jihel and Bousthami noir) than those matured on any other liquid medium. Histological studies revealed that somatic embryos (developed in L6 and L8 liquid media) accumulated less reserve compounds (proteins and sugars) than zygotic embryos. The addition of activated charcoal (0.25 and 0.5gl^–1) and phytagel^® (2.5gl^–1) to the germination medium may be useful for enhancing the germination of Phnix dactyliferasomatic embryos.     

Light and GTP dependence of transducin solubility in retinal rods

The physical origin and functional significance of the near infra-red light scattering changes observable upon flash illumination of diluted suspensions of magnetically oriented, permeabilised frog retinal rods has been reinvestigated with particular attention paid to the degree with which transducin remains attached to the membrane. In the absence of GTP, the so called binding signal is shown to include two components of distinctive origins, widely different kinetics, and whose relative amplitudes depend on the dilution of the suspension and resulting detachment of transducin from the disc membrane. The fast component is a consequence of the fast interaction between photoexcited rhodopsin (R^*) and the transducin remaining on the membrane. Its kinetics monitors a structural modification of the discs caused by a change in electrostatic interaction between closely packed membranes upon the formation of R^*-T complexes. The slow component monitors the slow rebinding to the membrane and possible subsequent interaction with excess R^* of T-GDP which, in spite of its low solubility, had eluted into solution given the high dilution of the permeated rods. In the presence of GTP, the so called dissociation signal includes a fast, anisotropic release component that specifically monitors the release into the interdiscal space of T -GTP formed from the membrane-bound pool, and a slower isotropic loss component monitoring the leakage from the permeated rod of the excess T -GTP which did not interact with the cGMP phosphodiesterase. The amplitudes of both components depend exclusively on the membrane bound T-GDP pool. The kinetics of the loss component is limited by the size and degree of permeation of the rod fragments, rather than by the dissociation rate of T -GTP from the membrane.Abbreviations ROS rod outer segment - R rhodopsin - R^* photoactivated rhodopsin - T, T-GDP, T -GDP, T -GTP, T transducin and its various forms - T _mb, T _sol: T bound to membrane or soluble - PDE cGMP-phosphodiesterase - GTP guanosine 5-triphosphate - GDP guanosine 5-diphosphate - GDP S guanosine 5-O-(2-thiodiphosphate) - cGMP guanosine-3-5 cyclic-monophosphate - DTT dithiothreitol - HEPES 4-(2-hydroxyethyl)-1-piperazine-ethane sulfonic acid - TRIS Tris (hydroxymethyl)aminomethane - SDS sodium dodecyl sulfate     

A Confirmation of 125I-ω-Conotoxin Labeled Sites in a Crude Membrane Fraction from Chick Brain as the α1 Subunit of N-Type Calcium Channels

Omega-conotoxin GVIA (-CTX), as a selective blocker for an N-type Ca²⁺ channel, has been conveniently used in many molecular biochemical and pharmacological experiments. There has been little elucidation of ¹²⁵I--CTX binding sites (mainly the 135-kDa band) in the crude membranes from chick brain, although the characteristics of specific ¹²⁵I--CTX binding and labeling sites in chick brain membranes have been investigated in our previous research. In this work, our goal is to further identify ¹²⁵I--CTX labeling sites in chick brain membranes by using anti-B1Nt antibodies (against the N-terminal segment B1Nt of N- or P-type Ca²⁺ channel ₁-subunits). The ¹²⁵I--CTX–labeled sites in chick brain membranes could be solubilized and immunoprecipitated by using an anti B1Nt antibody. The molecular weight of the immunoprecipitated protein was determined as 135 kDa, which is inconsistent with that of the specific ¹²⁵I--CTX binding protein reported previously. Moreover, the ¹²⁵I--CTX–labeled protein could be purified by the method of preparative SDS-PAGE and recognized by anti-B1Nt antibodies in Western blotting analysis. These results indicated that anti-B1Nt antibodies could truly recognize ¹²⁵I--CTX–labeled sites as the main band of 135 kDa from chick brain membranes, and the -CTX–labeled site (mainly the 135-kDa band) should be N-type Ca²⁺ channel ₁-subunits.     

Paramagnetic spin catalysis of a radical recombination reaction

Recombination of the triplet state radical pair consisting of two hydrogen atoms catalysed by molecular oxygen is considered as a simulating example of a paramagnetic-exchange catalytic process. Intermolecular exchange interaction in the collision complex between the H₂ and O₂ molecules is calculatedab initio in STO-6G and 6–31 G^* basis sets with complete active space configuration interaction. Calculations are done at a fixed O–H distance (3 Å), scanning the H–H bond length from 0.6 till 12 Å at the linear geometry of collision. The mixture of the triplet (T)³ _u ⁺ and singlet (S)¹ _g ⁺ states of the hydrogen moiety is possible because both states have the same triplet symmetry in the collision complex with O₂ (³ _g ^– ). A strong mixture of the S (¹ _g ⁺ , H₂ +³ _g ^– , O₂) and T) and T (³ _u ⁺ , H₂ +³ _g ^– , O₂) states is actually obtained even at large H–H distances. The quintet and singlet states^5,1(³ _u ⁺ , H₂ +³ _g ^– , O₂) are also considered for comparison of the exchange potentials. Atr(H–H)4.4 Å the S-T splitting is approximately constant (12 cm^-1 in the STO-6G basis set; 55.5 cm^-1 in the 6–31 G^* basis set) and is determined by the exchange interaction between O₂ and the nearest hydrogen atom in the O–O...H fragment. The paramagnetic catalyst can accelerate radical recombination through the triplet-singlet nonadiabatic transition to the lowest S reactive state when the radical encounter takes place in the vicinity of the catalyst. Though we do not consider the radical dynamics in a real solvent, which modulates the exchange potentials and the T-S transitions, the nature of this mechanism of spin catalysis is obvious. The electric polarization and charge transfer are important in the analysis of the exchange interaction and radical recombination potentials for all multiplets. In accordance with the concept of spin catalysis, the electronic spin-uncoupling mechanism, induced by O₂ perturbation, has the same nature as other known catalytic processes of paramagnetic-exchange type.     

Changes of fluorescence lifetime and rotational correlation time of bovine serum albumin labeled with 1-dimethylaminonaphthalene-5-sulfonyl chloride in guanidine and thermal denaturations

The nanosecond fluorescence depolarization method was applied to measure the fluorescence lifetime () and the rotational correlation time () of bovine serum albumin (BSA) labeled with 1-dimethylaminonaphthalene-5-sulfonyl chloride (dansyl-Cl). Changes of and of dansyl BSA in the guanidine denaturation and in the thermal denaturation were examined. In parallel, the secondary structural change of dansyl BSA was followed by circular dichroism measurements. The magnitude of was almost unchanged between 1 and 2 M guanidine, where the secondary structure of the protein was predominantly disrupted; whereas that of began to increase before the disruption of secondary structure in the guanidine denaturation. In the thermal denaturation, in contrast, changes of both and occurred in a temperature range where the secondary structure was predominantly disrupted. The volume of equivalent sphere (V _e ) and the axial ratio () for the BSA were 3.6–3.8×10^–19 cm³ and 3.6 at 2M guanidine as against 2.1×10^–19 cm³ and 2.2 in the absence of guanidine (25°C), respectively. The magnitudes ofV _e and were 4.9×10^–19 cm³ and 4.5 at 65°C, respectively. Although the secondary structural change of dansyl BSA was irreversible in the thermal denaturation,V _e and were reversible.     

Stable isotope and radiocarbon compositions of methane emitted from tropical rice paddies and swamps in Southern Thailand

Stable isotopes (¹³C, D) and radiocarbon weremeasured in methane bubbles emitted from rice paddies and swamps in southernThailand. Methane emitted from the Thai rice paddies was enriched in¹³C (mean ¹³C; –51.5 ±7.1 and–56.5 ± 4.6 for mineral soil and peat soil paddies,respectively)relative to the reported mean value of methane from temperate rice paddies(– 63 ± 5). Large seasonal variation was observed in¹³C(32) in the rice paddies, whereas variationinD was much more smaller (20), indicating that variation in¹³C is due mainly to changes in methane production pathways.Values of ¹³C were lower in swamps (–66.1 ±5.1)than in rice paddies. The calculated contribution of acetate fermentation from¹³C value was greater in rice paddies (mineral soils:62–81%, peat soils: 57–73%) than in swamps (27–42%). Din methane from Thai rice paddies (–324± 7 (n=46)) isrelativelyhigher than those from 14 stations in Japanese rice paddies ranging from–362 ± 5 (Mito: n=2) to –322 ± 8(Okinawa: n=3), due tohigher D in floodwaters. ¹⁴C content in methane produced fromThai rice paddies (127±1 pMC) show higher ¹⁴Cactivity compared with previous work in paddy fields and those from Thai swamps(110±2 pMC).     

High-level Expression of Maize <Emphasis Type="Italic">γ</Emphasis>-zein Protein in Transgenic Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)

Primers were developed for 118 microsatellites isolated from grape (Vitis vinifera) genomic libraries enriched for (AC)n repeats. Only one microsatellite sequence matched other grape SSR-sequences in the GeneBank database. Genotyping was carried out in the parental lines and four offspring of two pseudo-test-cross populations, Cabernet Sauvignon x Seyval and Chardonnay x Bianca, and a further six other grape genotypes (V. vinifera Sultanina, Merlot, Syrah, Müller-Thurgau, Vitis Regent and V. riparia Gloire de Montpellier). A total of 108 microsatellites showed easily scorable alleles and 100 of them segregated according to a configuration suitable for mapping in either cross. A further 8 SSRs, although unsuitable for mapping in those crosses, showed polymorphism in the other genotypes tested. This set of markers was used, along with 75 microsatellites of other repeat-types, to fingerprint 46 offspring of the cross Chardonnay x Bianca. For each full-sib, individual heterozygosity and distance in repeat units between pairs of alleles at each locus (mean d²) were calculated as a tool for predicting highly outbred recombinant individuals. Six microsatellites with segregation ratios significantly distorted towards the lack of homozygous sibs were identified and mapped to linkage groups LG 3 and LG 5. Estimation of heterozygosity at genome-wide level and genotyping at loci for which homozygous sibs are discriminated against are discussed for marker-assisted background selection in outcrossing grapevines.     

Style morph frequencies in Minnesota populations of Lythrum (Lythraceae)

Style morph frequencies (shortmidlong) were determined for a total of n = 11 918 plants in 16 Minnesota populations of Lythrum salicaria L. Nine populations were in the establishment phase, with population sizes ranging from n = 56 to n = 2 192. Most of these populations exceeded previously reported population sizes in the native European habitat. A nonparametric statistical test, the chi-square (²), can be used to determine if populations are at isoplethic equilibrium (111, shortmidlong); a ² value >5.99 is significant at the 5% level. Only one established population (White Bear Lake, n = 1991, ² = 3.0) fitted the null hypothesis for isoplethy, although all established populations contained all three style morphs. Pooled values for these populations indicated an excess of mids and longs, with shorts being deficient. Colonizing populations had a higher percentage of mids (54%) when compared to established populations (33.7%). Short styles were almost nonexistent (8%) in colonizing populations. Five out of the seven populations lacked at least one style morph. A review of the literature reporting style morph frequencies in tristylous L. salicaria revealed that no statistical analysis for isoplethy has been performed. Darwin originally assumed that all populations would be isoplethic, possessing equal numbers of all three style morphs, but concluded, without statistical analysis, that, instead, populations were anisoplethic. Since tests for statistical deviations from the expected frequencies (111) have not been used, ² analysis was performed. Several of these populations were at isoplethic equilibrium (Nadder su2 = 1.7, Blelham ² = 1.69, Potsdam ² = 1.5, Vestfold ² = 0.4, Buskerud ² = 5.62, Kilchberg ² = 0.35, Lausanne ² = 3.32, Canberra ² = 5.29, Massachusetts ² = 3.13), suggesting that the general conclusion of anisoplethy in tristylous L. salicaria is inappropriate.This is Scientific Journal Series Paper Number 19 128 of the Minnesota Agricultural Experiment Station     

The electrical response ofAvena coleoptile cortex to auxins

Solute mobilities of 28 compounds in isolated cuticular membranes (CM) from Capsicum annuum L. fruit, Citrus aurantium L. and Pyrus communis L. leaves were studied using unilateral desorption from the outer surface. First-order rate constants of desorption (k^*), which are directly proportional to the diffusion coefficient in the waxy outer limiting skins of cuticles were measured. When log k^* was plotted vs. molar volumes of test compounds linear graphs were obtained. The y-intercepts of these graphs (k^*) represent the mobility of a hypothetical molecule having zero molar volume and the slopes of the graphs () represent the size selectivity of the barrier and are related to the free volume available for diffusion. Thus, solute mobilities in cuticles are composed of two independent terms which are subtractive. If k^* and are known, k^* can be estimated for any solute from its molar volume (V_x) using the equation log k^*=log k^* –V_x. These parameters were used to analyse the effects of plant species, extraction of cuticular waxes and molecular structure of solutes on solute mobilities in plant cuticles. For aliphatic solutes, k^* was a factor of 10 smaller than for cyclic compounds, while was 0.011 and 0.012, respectively. The k^*-values for CM of the three species were very similar, but was higher for bitter-orange CM (0.012) than for those of pepper fruits and pear leaves (0.009). This has the consequence that differences in solute mobilities (k^*) among cuticles from different plan species increase with increasing molar volumes of solutes. Our data and our analysis provide evidence that constituents of cuticular waxes are mobile, at least in the solid amorphous wax fraction, but mobility decreases rapidly with increasing molar volume. For instance, if amounts to 0.01, mobilities of wax monomers decrease by a factor of 10 for every increase in molar volume of 100 cm³ · mol^–1. Thus, hexadecanoic acid is quite mobile in the amorphous wax fraction of Citrus (k^*=1.5×10^–6·s^–1), but for dotriacontane having twice the molar volume, k^* was only 2.5×10^–9·s^–1, which is almost three orders of magnitude smaller. Wax esters have even higher molar volumes and their mobilities will be even smaller (about 4×10^–12·s^–1 for a C₄₈-ester). Since low chain mobilities are a prerequisite for low mobilities and permeabilities, the selective advantage of high-molecular-weight wax monomers in plant cuticular waxes becomes obvious. Extracting cuticular waxes from pear leaf CM increased solute mobilities by a factor of 182, but it had no effect on size selectivity. We interpret this result as evidence to the effect that cuticular waxes reduce mobility by increasing tortuosity of the diffusion path, rather than by decreasing the mean free path of diffusional jumps and jump frequencies of diffusants.Abbreviations CM cuticular membrane(s) - 2,4-D 2,4-dichloro-phenoxyacetic acid - LAB lactic acid buffer - MX polymer matrix membranes - UDOS unilateral desorption from the outer surface     

Product inhibition during the feeding phasein fed-batch ethanol fermentation of sugar-cane blackstrap molasses

Summary The following equations represent the influence of the ethanol concentration (E) on the specific growth rate of the yeast cells () and on the specific production rate of ethanol () during the reactor filling phase in fed-batch fermentation of sugar-cane blackstrap molasses: = ₀ - k · E and v = v ₀ · K/(K +E) Nomenclature E ethanol concentration in the aqueous phase of the fermenting medium (g.L^–1) - E_m value of E when = 0 or = 0 (g.L^–1) - F medium feeding rate (L.h^–1) - k empirical constant (L.g^–1.h^–1) - K empirical constant (g.L^–1) - M_as mass of TRS added to the, reactor (g) - M_cs mass of consumed TRS (g) - M_e mass of ethanol in the aqueous phase of the fermenting medium (g) - M_s mass of TRS in the aqueous phase of the fermenting medium (g) - M_x mass of yeast cells (dry matter) in the fermenting medium (g) - r correlation coefficient - S TRS concentration in the aqueous phase of the fermenting medium (g.L^–1) - S_m TRS concentration of the feeding medium (g.L^–1) - t time (h) - T temperature (° C) - TRS total reducing sugars calculated as glucose - V volume of the fermenting medium (L) - V₀ volume of the inoculum (L) - X yeast cells concentration (dry matter) in the fermenting medium (g.L^–1) - filling-up time (h) - specific growth rate of the yeast cells (h^–1) - ₀ value of when E=0 - specific production rate of ethanol (h^–1) - ₀ value of when E=0 - density of the yeast cells (g.L^–1) - dry matter content of the yeast cells     

Glycogen phosphorylase ‘b’ in Dictyostelium: stability and endogenous phosphorylation

Summary The slime mold Dictyostelium discoideum has two forms of the enzyme glycogen phosphorylase. The inactive phosphorylase b form requires 5 AMP for activity and is present in early development. The active phosphorylase a form is 5 AMP independent and occurs during later development. We here show that the 92 kd b enzyme subunit exists either as a singlet or a doublet upon SDS-PAGE, depending on the method of sample extraction. In the presence of exogenously added Mn²⁺ and ATP, the phosphorylase b shows apparent conversion into a 5 AMP independent form as measured by enzyme activity. In addition, Mn²⁺ and ATP also support an in vitro phosphorylation of the 92 kd phosphorylase b subunit. We also demonstrate phosphorylation of the b enzyme subunit in vivo by ³²-P incorporation into the enzyme protein. A protein kinase responsible for the observed in vitro phosphorylation of the phosphorylase b subunit is characterized.     

Structural diversity of O-polysaccharides and serological classification of <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv. <Emphasis Type="Italic">garcae</Emphasis> and other strains of genomospecies 4

Novel O-serotypes were revealed among Pseudomonas syringae pv. garcae strains by using a set of mouse monoclonal antibodies specific to the lipopolysaccharide O-polysaccharide. Structural studies showed that the O-polysaccharide of P. syringae pv. garcae NCPPB 2708 is a hitherto unknown linear L-rhamnan lacking strict regularity and having two oligosaccharide repeating units I and II, which differ in the position of substitution in one of the rhamnose residues and have the following structures: I:3)--L Rha (12)-- L Rha (12)--L-Rha-(13)--L Rha (1;II: 2)--L-Rha-(13) -L-Rha-(12)--L-Rha-(13)--L Rha (1.The branched O-polysaccharides of P. syringae pv. garcae ICMP 8047 and NCPPB 588^T have the same L-rhamnan backbone with repeating units I and II and a lateral chain of 14)- or 13)-linked residues of 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc). Several monoclonal antibody epitopes associated with the L-rhamnan backbone or the lateral -D-Fuc3NAc residues were characterized.Translated from Mikrobiologiya, Vol. 73, No. 6, 2004, pp. 777–789.Original Russian Text Copyright © 2004 by Ovod, Zdorovenko, Shashkov, Kocharova, Knirel.     

α-Globin gene deletions associated with αAand αG Philadelphiagenes in an Algerian family that includes two Hb G homozygotes

Summary An Algerian family with a high degree of consanguinity and including two homozygotes for Hb-G Philadelphia is presented. Whether homozygotes or heterozygotes, all subjects displayed microcytosis (with various degrees of poikilocytosis) and a moderately depressed -globin chain synthesis. Hb H and Heinz bodies were absent. DNA mapping revealed the presence of 3.7 kb deletion resulting from the rightward type of recombination event between ₂ and ₁ genes on both the ^A/and the ^G chromosomes. Such data indicate that the –^A/ and –^G/ haplotypes are involved and suggest that the –^G/ haplotype, which is very rare in Algeria, has an African Black origin. In subjects with genotype (–^A/–^G/) or (–^G/–^G/), the output of the remaining genes is sufficiently high to avoid the appearance of Hb H. This situation contrasts with that reported in an Algerian patient, who had a (–^A/–^A/) genotype but who was producing Hb H (Whitelaw et al. 1980). The data collected from this family suggest that the –^A/ haplotypes are heterogeneous in Algerians.     

Stereospecific assignment of β-methylene protons in larger proteins using 3D15N-separated Hartmann-Hahn and13C-separated rotating frame Overhauser spectroscopy

Summary ³J _x coupling constants and complementary nuclear Overhauser data on the intraresidue C ^x H–CH distances form an essential part of the data needed to obtain stereospecific assignments of -methylene protons in proteins. In this paper we show that information regarding the magnitude of the³J _x coupling constants can be extracted from a semi-quantitative interpretation of relative peak intensities in a 3D¹⁵N-separated¹H–¹H Hartmann-Hahn¹H–¹⁵N multiple quantum coherence (HOHAHA-HMQC) spectrum. In addition, we demonstrate that reliable information on the intraresidue C ^x H–CH distances, free of systematic errors arising from spin diffusion, can be obtained from a 3D¹³C-separated¹H–¹H rotating frame Overhauser effect¹H–¹³C multiple quantum coherence (ROESY-HMQC) spectrum. The applicability of these experiments to larger proteins is illustrated with respect to interleukin-1, a protein of 153 residues and 17.4 kDa molecular weight.Abbreviations 1L-1 interleukin-1 - NOE nuclear Overhauser effect - ROE rotating frame Overhauser effect - HOHAHA homonuclear Hartmann-Hahn spectroscopy - NOESY nuclear Overhauser enhancement spectroscopy - ROESY rotating frame Overhauser spectroscopy - HMQC heteronuclear multiple quantum coherence spectroscopy