Variation in selectivity of univalent cations in slime moldPhysarum polycephalum caused by reception of polyvalent cations

Summary Specificity of reception on 11 electrolytes in the slime moldPhysarum polycephalum was investigated in the presence of polyvalent cations in media. Membrane potential and motive force of tactic movement were examined with the aid of the double chamber method, and the zeta potential at the membrane surface of the slime mold was measured by electrophoretic mobility. The results obtained are summarized as follows: (1) The presence of polyvalent cations (e.g., Ca²⁺, Mg²⁺, Sr²⁺, Ba²⁺, La³⁺, Th⁴⁺) in medium led to an increase in threshold concentration,C _th , determined from the potential measurements for Na- or Li-salts, and to a decrease inC _th for K-, Rb-, or NH₄-salts,C _th for 11 electrolytes changed discontinuously when the concentration of polyvalent cations in medium exceeded their respective thresholds. (2) TheC _th determined from chemotaxis agreed with that from the potential response both in the presence and absence of polyvalent cations. (3) Sequence of selectivity of univalent cations varied extensively in the presence of polyvalent cations. (4) Changes in the zeta potential induced by NaCl reception agreed with those in the membrane potential even in the presence of Ca²⁺ in medium. (5) TheC _th for reception of NaCl changed sharply at about 12 °C in the presence of polyvalent cations, while that for KCl was independent of the temperature.Conformational changes in surface membrane of the slime mold in response to reception of polyvalent cations were then discussed in relation to the discrimination of univalent cations.     

Volatile C6-Aldehyde Formation via Hydroperoxides from C18-Unsaturated Fatty Acids in Etiolated Alfalfa and Cucumber Seedlings

1. Etiolated seedlings of alfalfa and cucumber evolved n-hexanal from linoleic acid and cis-3-hexenal and trans-2-hexenal from linolenic acid when they were homogenized.

2. The activities for n-hexanal formation from linoleic acid, lipoxygenase and hydro-peroxide lyase were maximum in dry seeds and 1~2 day-old etiolated seedlings of alfalfa, and in 6~7 day-old etiolated seedlings of cucumber.

3. n-Hexanal was produced from linoleic acid and 13-hydroperoxylinoleic acid by the crude extracts of etiolated alfalfa and cucumber seedlings. cis-3-Hexenal and trans-2-hexenal were produced from linolenic acid and 13-hydroperoxylinolenic acid by the crude extracts of etiolated alfalfa and cucumber seedlings. But these extracts, particulariy cucumber one, showed a high isomerizing activity from cis-3-hexenal to trans-2-hexenal.

4. When the C₈-aldehydes were produced from linoleic acid and linolenic acid by the crude extracts, formation of hydroperoxides of these C₁₈-fatty acids was observed.

5. When 9-hydroperoxylinoleic acid was used as a substrate, trans-2-nonenal was produced by the cucumber homogenate but not by the alfalfa homogenate.

6. As the enzymes concerned with C₆-aldehyde formation, lipoxygenase was partially purified from alfalfa and cucumber seedlings and hydroperoxide lyase, from cucumber seedlings. Lipoxygenase was found in a soluble fraction, but hydroperoxide lyase was in a membrane bound form. Alfalfa lipoxygenase catalyzed formation of 9- and 13-hydroperoxylinoleic acid (35: 65) from linoleic acid and cucumber one, mainly 13-hydroperoxylinoleic acid formation. Alfalfa hydroperoxide lyase catalyzed n-hexanal formation from 13-hydroperoxylinoleic acid, but cucumber one catalyzed formation of n-hexanal and trans-2-nonenal from 13- and 9-hydroperoxylinoleic acid, respectively.

7. From the above results, the biosynthetic pathway for C₆-aldehyde formation in etiolated alfalfa and cucumber seedlings is established that C₆-aldehydes (n-hexanal, cis-3-hexenal and trans-2-hexenal) are produced from linoleic acid and linolenic acid via their 13-hydroperoxides by lipoxygenase and hydroperoxide lyase.     

Regulation of biosynthesis of pesticidal metabolic complexes inStreptomyces griseus

The complex of pesticidal metabolites produced byStreptomyces griseus LKS-1 consists of a peptide antibiotic (A), nonactic acids (B), macrotetrolides (C), pyrrolizines (D), and of cycloheximide. The latter unwanted phytotoxic compound was eliminated by treatment with mutagens. Combined approaches, including both genetic and physiological manipulations, resulted in the following alterations in the biosynthetic capacity: (1) A more than 80-fold increase in the production of C under a substantial decrease in the yields ofA, B andD, the ratio of the components ofC being steered toward the required more active ones; (2) a more than 300-fold increase in the production ofB under suppression of the formation ofA andC: (3) a 10-fold increase in the yields ofD under suppression ofA andC; (4 a significant increase in the yields ofA with eliminatingB, C andD. The level of inorganic phosphate in fermentation media and the sensitivity of the organism to carbon catabolite repression were important factors participating in the regulation of the above biosynthetic processes.     

FOUR PROTEIN POLYMORPHISMS IN PIGEON BRAIN EXTRACTS DETECTED BY TWO-DIMENSIONAL GEL ELECTROPHORESIS

Abstract— Proteins of the brain extracts of 85 individual pigeons (Columba livia) were mapped by two-dimensional gel electrophoresis. The method is a modification of O'Farrell 'S technique and separates proteins first by charge and then by molecular weight. There were three proteins, A, B and D which had each a variant form. The positions of these six proteins on the gel corresponded to the following pH values and molecular weight values: protein A₁, 6.4/43,000; A₂, 6.6/43,000; B₁, 5.7/41,000; B₂, 5.8/40,000; D₁, 6.2/22,000; D₂, 6.2/21,000. The variants are genetically determined, since protein A, B and D each occurred in three phenotypes (A₁, A₁A₂ and A₂; B₁, B₁B₂ and B₂; D₁, D₁D₂ and D₂) corresponding to the three possible genotypes. From the observed frequencies of the phenotypes the following allele frequencies were calculated: allele A₁, 72%; A₂, 28%; B₁, 15%; B₂, 85%; D₁, 74%; D₂, 26%. A fourth protein named C occurred in four different forms (C₁, 7.2/37,000; C₂, 7.2/36,000; C₃, 7.1/37,000; C₄, 7.1/36,000) and six phenotypes (C₁, C₁C₂, C₂, C₁C₃, C₂C₃ and C₄C₃). This polymorphism is also interpreted as being genetically determined. The four alleles coding for the four protein C forms had the following frequencies: allele C₁, 62%; C₂, 27%; C₃, 10.5%; C₄, 0.5%.     

Relationships between body temperature,thermal conductance,Q 10 and energy metabolism during daily torpor and hibernation in rodents

Summary In the present paper we examine the ability of rodents to maintain body temperature (T _B ) following the marked reductions in metabolic heat production associated with torpor. Previously published values for metabolic rate (M),T _B and ambient temperature (T _A ) were used to calculate thermal conductances (C') during normothermy and torpor in rodents capable of daily torpor (11 species) and hibernation (18 species). Values ofC' for torpid animals are uniformly lower thanC' in normothermic animals. In addition,C' of normothermic and torpid rodents decreases with increasing body mass (BM). However, the slope of the relationship betweenC' and BM is almost 4-fold greater for normothermic than for torpid animals. Thus, the ability of torpid rodents to conserve body heat by reducingC' decreases with increasing mass. Rodents that use daily torpor tend to be small and they tend to maintainT _B well aboveT _A during torpor. Hibernators tend to be larger and regulateT _B relatively close toT _A . Thus, the reductions inC' appear to be closely correlated with the level ofT _B regulation during torpor. We suggest that the changes inC' represent a suite of physiological adaptations that have played a central role in the evolution of torpor, enabling rodents to regulateT _B aboveT _B during periods of very low heat production. Based on the approach used here we address the controversy of whether reductions inM during torpor are due entirely to temperature effects or whether metabolic inhibition in addition to temperature effects may be important. We suggest that the controversy has been confused by usingQ ₁₀ to evaluate the relationship ofM andT _B in endotherms. What is perceived as metabolic inhibition (i.e.,Q ₁₀>3) is confounded by changes in the relationship ofM andT _B due to reductions inC' and reductions in the difference betweenT _B andT _A . Unfortunately, changes inM andT _B cannot be used to quantify changes in metabolic state in endotherms. Thus, neitherQ ₁₀ nor the approach used here can be used to make valid statements about the metabolic regulatory processes associated with torpor. Other methods, perhaps at the cell or tissue level, are needed.Abbreviations T _B body temperature - T _A ambient temperature - C' thermal conductance - C _n normothermicC whenT _A is above a lower critical temperature - C _t torporC when animals are in daily torpor or hibernation - M metabolic rate - BM body mass - WVPD water vapor pressure deficit     

Effects of pH and light on the membrane conductance measured in the acid and basic zones ofChara

Summary The area-specific coductance of the membrane in the acid and basic zones (denoted byG _A andG _B , respectively) ofChara cells was measured in flowing solutions, containing 5mm zwitterionic buffer, as a function of the external pH(denoted by pH⁰). During illuminationG _A was 1 S/m² for pH⁰ in the range 5 to 8.5, and increased markedly to 3 to 6 S/m² at higher pH₀.G _B , however, was always larger thanG _A during illumination with a typical magnitude of 5 to 15 S/m² for pH⁰ 6 to 12. Thus under many experimental conditions it is possible that there is no single correct value for the membrane area-specific conductance. A flow of current in the external medium between the acid and basic regions was found to be associated with pH banding, and also withG _B exceedingG _A . This current could be present in flowing solutions without added HCO ₃ ^– over a wide range of pH⁰ and at high (25mm) buffer concentration. Combining measurements ofG _A andG _B with measurements of the currents in the acid and basic zones (denoted byJ _A andJ _B , respectively), it was estimated that the resting (i.e. in the absence of net current flow) potential difference (PD) across the membranes within the individual zones (denoted byU _A andU _B ) was –265±20 and –183±5 mV, respectively, during illumination. Upon the removal of illumination at pH⁰-7.5,G _A ,G _B andJ _B were found to decrease rapidly during the initial few hundred seconds. During this period (U _B –V _m ) remained relatively constant. A transient hyperpolarization ofV _m often occurred, the magnitude of which was correlated with the magnitude ofJ _B prior to the removal of illumination. After some 0.5 to 1 ksec of darkness,G _A andG _B had both decreased considerably and nowG _A G _B andU _A U _B V _m . Eventually, after 2 to 8 ksec of darkness, the membrane conductance was effectively homogeneous with a much smaller magnitude (typically<0.2S/m²) andV _m was depolarized by typically 5 to 15 mV.     

Mechanism of sex determination inRumex hastatulus Baldw.

Summary The results presented indicate that the sex determination mechanism in the Texas race ofR. hastatulus 2n = 10 (XX + 8A); 2n = 10 (XX + 8A)] is intermediate between theX/Y andX/A systems. In this race, sex is determined to some extent by theX/A balance, but theY chromosome also affects sex expression, maleness or intersexuality being correlated with different ratios ofX andY chromosomes.The results obtained for the Texas race are fully compatible with data presented by Smith (1963) for the North Carolina race [ 2n = 8 (XX + 6A); 2n = 9 (XX ₁ Y ₂ + 6A)]. It may be concluded that evolution of the karyotype in this species is not accompanied by changes in the mechanism of sex determination.     

Approximate matching of regular expressions

Given a sequenceA and regular expressionR, theapproximate regular expression matching problem is to find a sequence matchingR whose optimal alignment withA is the highest scoring of all such sequences. This paper develops an algorithm to solve the problem in timeO(MN), whereM andN are the lengths ofA andR. Thus, the time requirement is asymptotically no worse than for the simpler problem of aligning two fixed sequences. Our method is superior to an earlier algorithm by Wagner and Seiferas in several ways. First, it treats real-valued costs, in addition to integer costs, with no loss of asymptotic efficiency. Second, it requires onlyO(N) space to deliver just the score of the best alignment. Finally, its structure permits implementation techniques that make it extremely fast in practice. We extend the method to accommodate gap penalties, as required for typical applications in molecular biology, and further refine it to search for substrings ofA that strongly align with a sequence inR, as required for typical data base searches. We also show how to deliver an optimal alignment betweenA andR in onlyO(N+logM) space usingO(MN logM) time. Finally, anO(MN(M+N)+N ²logN) time algorithm is presented for alignment scoring schemes where the cost of a gap is an arbitrary increasing function of its length.     

Effect of adherence,cell morphology,and lipopolysaccharide on potassium conductance and passive membrane properties of murine macrophage J774.1 cells

Summary The effects of adherence, cell morphology, and lipopolysaccharide on electrical membrane properties and on the expression of the inwardly rectifying K conductance in J774.1 cells were investigated. Whole-cell inwardly rectifying K currents (K _i), membrane capacitance (C _m), and membrane potential (V _m) were measured using the patch-clamp technique. SpecificK _i conductance (G _K i, whole-cell Ki conductance corrected for leak and normalized to membrane capacitance) was measured as a function of time after adherence, and was found to increase almost twofold one day after plating. Membrane potential (V _m) also increased from –42±4 mV (n=32) to –58±2 mV (n=47) over the same time period.G _K i andV _m were correlated with each other;G _L (leak conductance normalized to membrane capacitance) andV _m were not. The magnitudes ofG _K i andV _m 15 min to 2 hr after adherence were unaffected by the presence of 100 m cycloheximide, but the increase inG _K iandV _m that normally occurred between 2 and 8 hr after adherence was abolished by cycloheximide treatment. Membrane properties were analyzed as a function of cell morphology, by dividing cells into three categories ranging from small round cells to large, extremely spread cells. The capacitance of spread cells increased more than twofold within one day after adherence, which indicates that spread cells inserted new membrane. Spread cells had more negative resting membrane potentials than round cells, butG _K i andG _L were not significantly different. Lipopolysaccharide-(LPS; 1 or 10 g/ml) treated cells showed increasedC _m compared to control cells plated for comparable times. In contrast to the effect of adherence, LPS-treated cells exhibited a significantly lowerG _K i than control cells, indicating that the additional membrane did not have as high a density of functionalG _K i channels. We conclude that both adherence and LPS treatment increase the total surface membrane area of J774 cells and change the density of Ki channels. In addition, this study demonstrates that membrane area and density of Ki channels can vary independently of one another.     

Effects of ambient water vapor pressure and temperature on evaporative water loss inPeromyscus maniculatus andMus musculus

Summary Oxygen equilibria, ligand-binding kinetics and some other physicochemical properties are reported for erythrocruorins of two intertidal polychaetes:Marphysa sanguinea, which inhabits simple, relatively stagnant burrows, andDiopatra cuprea, which inhabits impermeable, parchment-like tubes that are vigorously ventilated.Marphysa erythrocruorin has a higher O₂ affinity, which is less pH dependent (at pH 7.3 and 20°C, half-saturation O₂ tension,P ₅₀, and Bohr factor, =logP ₅₀/pH, are 0.8 mm Hg and –0.25, respectively) than the corresponding parameters (P ₅₀=5.5; =–0.86) inDiopatra (Figs. 1 and 2). In contrast to vertebrate haemoglobins, inorganic salts increase erythrocruorin O₂ affinity (Fig. 3). The kinetic rates of ligand binding and dissociation ofMarphysa andDiopatra erythrocruorins (Tables 1 and 2) correlate well with the measured O₂ affinities and appear to illustrate basic molecular adaptations of the two species to their respective micro-environmental conditions.     

Telomere Length Distribution and Southern Blot Analysis

Southern blot analysis of terminal restriction fragments (TRFs) is the standard method for quantitative examination of telomere length distributions. Since TRFs contain a subtelomeric component, central parameters of the TRF distributionn(L) such as the arithmetic mean (M) or the median (Me) cannot be derived directly from Southern blot data, i.e. from the optical density distributionOD(L). Several estimates have been applied instead; the seeming arithmetic meanA, the “center of mass”C, and the positions of maximal (P) and half-maximal optical density (P). We show thatC>A>Mfor any non-truncated distributionsn(L), andP>M>P1/2 for any symmetrical unimodaln(L).Symmetric appearance on a Southern blot, however, suggests positive skewness ofn(L). Thus, alognormalform ofn(L) may be considered. Then,C>A>M>P=Me>P. Alternatively, aWeibulldistribution may be assumed. The latter is compatible with negative feedback-regulation of the telomere lengths. Using the maximum likelihood method we compare these distributions with FISH-data on telomere lengths in different cell types. The fit of the lognormal distribution is clearly superior. Lognormal genesis may relate to telomere breakage and recombination.Truncation of the upper end of the TRF distribution is possible due to Southern blot artifacts. Thereby, the order of the estimates may change toP>C>A. Having minimal sensitivity to truncation,Pseems to be the optimal choice. however, the variability ofPis high since peakedness ofOD(L) and DNA length resolution are inversely related.     

Hemoglobin types in saanen goats and Barbary sheep: Genetic and comparative aspects

By the use of the Immobiline technique at pH ranges 7.0–7.6 and 6.9–7.9, 16 different hemoglobin (Hb) phenotypes were observed in 61 English Saanen goats. They are explained in this breed by a genetic theory of five β-globin genes (A ₄,A ₆,A ₈,E, andD) and two closely linked α-globin loci (′α and ″α) of which the ″α has a variant allele, provisionally called ″α ^X . Family data together with observed and expected Hb frequencies were in agreement with the genetic theory. Among six Barbary sheep there were three Hb phenotypes explained by the occurrence of the β-chain allelesB andC ^na.     

A numerical experiment on the determination of kinetic rate constants in the presence of diffusion

Two chemicals,A andB, are allowed to diffuse together and a reaction described by $$A + B\mathop \rightleftharpoons \limits_{K_{ - 1} }^{K_1 } C$$ is allowed to proceed. This system is described mathematically by a system of partial differential equations. A numerical procedure is presented to find the rate constants ofK ₁ andK _?1. A systematic analysis of the effects of errors is also presented.     

Isolation of Novel Antifungal Antibiotics,Ezomycins A1, A2, B1 and B2

From ezomycin complex produced by a strain of Streptomyces were isolated four components named ezomycins A₁ (C₂₆H₄₀N₈O₁₆S), A₂ (C₁₉H₂₈N₆O₁₃), B₁ (C₂₆H₃₉N₇O₁₇S) and B₂ (C₁₉H₂₇N₅O₁₄) which are new pyrimidine nucleosides. Ezomycins A₁ and B₁ containing l-cystathionine were found to be responsible for specific antimicrobial activity of the complex against Sclerotinia and Botrytis species.     

Phospholipases. I. Effect ofn-alkanols on the rate of enzymatic hydrolysis of egg phosphatidylcholine

Summary The rate of hydrolysis of unsonicated liposomes of egg lecithin by phospholipase A (from bee venom and Russell viper venom) and phospholipase C (fromBacillus cereus andClostridium welchii) is markedly dependent on the nature and concentration of a variety of added alcohols. Typical plots of rate against alcohol concentration are bell-shaped. The maximum rate and the alcohol concentration at which it is achieved are alcohol-specific. In a homologous series ofn-alkanols, the maximal rates increase and the optimal concentrations decrease as the chain length is increased from C₄ to C₈. For longer alcohols (C₉ to C₁₂), progressively higher concentrations are required to elicit maximal activation. The optimal activating concentrationsC for C₄ to C₈ n-alkanols obey the relationshipp C=a logP _octanol+constant [cf. Hansch & Dunn,J. Pharm. Sci. 61:1 (1972)], suggesting that the alcohol-activating effect is a consequence of their incorporation into the liposomes with resultant modification of liposomal structure.     

Variation of Inhibition Modes by n-Alcohols in Arbutin (Hydroquinone-O-β-D-glucopyranoside) Hydrolysis by β-Glucosidase

When n-alcohols were added to the β-glucosidase-catalyzed hydrolysis of arbutin, the rate was decreased almost linearly with their elevating concentrations. The inhibition was shown in two modes, competitive for higher n-alcohols and noncompetitive for lower n-alcohols than n-butanol. The inhibition constants (K_i) obtained, moreover, clearly demonstrated classifying the modes in two groups according to physicochemical parameters, log P, Hildebrand solubility parameter (δ), and dielectric constant (?), of n-alcohols. n-Butanol being between two modes of inhibition showed a mixed-type inhibition. The data suggested that the inhibition of n-alcohols for p-glucosidase may be related with their chain length. An imaging model in this case of inhibition is presented.     

Comparative efficacies in vitro of antibacterial,fungicidal, antioxidant,and herbicidal activities of momilatones A and B

Abstract

Momilactones A (M_A) and B (M_B) are phytoalexins derived from rice plant (Oryza sativa) and were considered to be a part of the mechanism of rice self-defense system. The present study was to evaluate the comparative efficacies in vitro of antibacterial, fungicidal, antioxidant, and herbicidal activities of M_A and M_B. In general, M_B shows higher antifungal, antibacterial, and herbicidal action than M_A, although its antioxidant property was less than M_A. In herbicidal trial, the IC₅₀ values of M_B against germination, shoot and root elongation of barnyardgrass and monochoria were 40.9, 45.5, and 27.5, and 27.1, 17.3, and 0.9 µg, respectively. For M_A, these values were 40.3, 35.6, and 55.1, and 43.9, 24.3, and 0.5 µg, respectively. For antifungal activity, momilactone B (IC₅₀: 1.2, 123.9, and 53.4 µg) exerted significantly greater inhibition than M_A (IC₅₀: 78.1, 198.1, and 95.3 µg) against Botrytis cinerea, Fusarium solani, Colletrotrichum gloeosporioides, respectively, except for Fusarium oxysporum that both M_A and M_B showed no marked difference. In addition, M_B exhibited significantly stronger antibacterial activity than M_A against Pseudomonus ovalis, Bacillus cereus, and Bacillus pumilus, whereas the inhibitory activity of the two compounds was similar against Escherichia coli. Both M_A and M_B exerted rather weak antioxidant activity (EC₅₀ was 783.9 and 790.7 µg, respectively), of which M_A showed a slightly stronger antioxidant activity than M_B. This study is the first to examine antifungal, antibacterial, and antioxidant activities of two phytoalexins, as well as their comparative efficacies against growth of the noxious weeds barnyardgrass and monochoria.     

Note on psychophysical discrimination with more than two stimuli

H. D. Landahl's well-known theory of psychophysical discrimination between two stimuli (Psychometrica,3, 107–125, 1938) is generalized to the case ofn mutually inhibiting stimuli, such that all the corresponding reactions are mutually incompatible so that only one response at most can occur at a time. It is shown that while in the two-stimulus case a “no-response” situation does not necessarily need to occur, in the case ofn stimuli andn responses a “no-response” situation always occurs with finite probability. Therefore, there is a probabilityP _i of the occurrence of each responsei as well as a probabilityP _e of no response, with . The probabilitiesP _i andP _e are expressed in terms of the intensities of then stimuliS _i and in terms of then distribution functions of the fluctuations at then corresponding connections. The expressions are in the form of sums ofn-tuple integrals of the products of the distribution functions, the limits of integration being determined by the intensities of then stimuli.     

Photosynthetic pathways inChenopodiaceae from Africa, Asia and Europe with their ecological, phytogeographical and taxonomical importance

Photosynthetic pathways are reported for 305 species ofChenopodiaceae from Africa, Asia and Europe. Ecological characteristics, phytogeography and life forms of all species are given, and their correlation with relevant CO₂-fixation types are discussed. 205 species (67.2%) exhibit the C₄-pathway and 100 species (32.8%) the C₃-pathway of CO₂-fixation. Most of the C₄ species are of Irano-Turanian origin. The diversity of C₄ species of the Irano-Turanian phytochoria, with very harsh winters, are interpreted by the active period of Chenopods in summer. There is a close relationship between some special morphotypes and respective photosynthetic type. Halophytes and xerophytes with articulated stems and stem succulents ofAnabasis-type are exclusively C₄. Leaf succulent halophytes and xerohalophytes are predominantly C₄. Hygrohalophytes with leaf or stem succulence are often C₃. Probably many C₄ Salsoleae have been evolved in the Afroasiatic arid zone after the climatic changes of the Miocene. Among them there is a high proportion of annuals that have a younger origin. There is some evidence that the present Chenopods of the subfamily Salsoloideae may have their ancient stock in NW Africa. We found close taxonomic relationships between photosynthetic pathways and infrageneric classification in genera with both types of C₃ and C₄, likeAtriplex andSuaeda. Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer, Wien, on the occasion of his 70th birthday