Evolutionary game dynamics in a Wright-Fisher process

Evolutionary game dynamics in finite populations can be described by a frequency dependent, stochastic Wright-Fisher process. We consider a symmetric game between two strategies, A and B. There are discrete generations. In each generation, individuals produce offspring proportional to their payoff. The next generation is sampled randomly from this pool of offspring. The total population size is constant. The resulting Markov process has two absorbing states corresponding to homogeneous populations of all A or all B. We quantify frequency dependent selection by comparing the absorption probabilities to the corresponding probabilities under random drift. We derive conditions for selection to favor one strategy or the other by using the concept of total positivity. In the limit of weak selection, we obtain the 1/3 law: if A and B are strict Nash equilibria then selection favors replacement of B by A, if the unstable equilibrium occurs at a frequency of A which is less than 1/3.     

Kidney alloantigens determined by two regions of the rat major histocompatibility complex

Recombination inH-1, the major histocompatibility complex (MHC) of the rat, has defined two regions,H-1A andH-1B, which determine antigens apparently homologous to the KJD and Ia antigens of the mouse, respectively. Alloantisera directed at these antigens have been absorbed with kidney homogenates. The results showed that cells in the kidney express serologically detectable MHC antigens determined by both theH-1A andH-1B region. Control absorptions indicated that to account for these results in terms of recirculating lymphocytes, two perfused kidneys would need to contain more than 60 percent of the recirculating lymphocyte pool. It appears likely, therefore, that H-1B antigens are expressed by cells resident in the kidney.     

The kinetics of linear systems with special reference to periodic reactions

It is shown on the basis of (1) conservation of mass, (2) positive concentrations, and (3) the principle of detail balancing that periodic reactions cannot occur in a closed system described bylinear differential equations. The matrix,A, of the rate equations must be such that |A|=0,a _ij>0 fori≠j,a _ii<0, andVAV ⁻¹=B, whereV is diagonal andB is symmetric. These properties ofA imply that the latent roots are real and non-positive and that neither catalysis nor inhibition can be described bylinear equations. It is further shown that periodic reactions cannot occur in anopen system for which the matrix associated with the chemical reactions has the above properties and in which thesimple law of diffusion is obeyed. The relation of these results to Onsager's reciprocal relations and to previous work on periodic and cyclic chemical reactions is discussed. The utility of certain of these results for the treatment of isotope kinetics is indicated. A portion of this work was performed while the author was in the Department of Physiology, University of Chicago, and was supported by a grant from the Dr. Wallace C. and Clara A. Abbott Memorial Fund.     

Synthesis of phosphites and phosphates of neuraminic acid and their glycosyl donor properties — convenient synthesis of GM3

The importance and requirements for catalytic activation of sialyl donors are discussed, leading to the acid sensitive phosphite and phosphate moiety, respectively, as leaving group and nitriles as solvent. Therefore, from readily availableN-acetylneuraminic acid, derivative1 with phosphochloridites2a-f and Huenigs' base sialyl phosphites3a-f were prepared and isolated in high yields. Oxidation of3a, c withtert-butyl-hydroperoxide afforded the corresponding phosphates4a, c. As expected, phosphites3 could be activated in acetonitrile by catalytic amounts of TMSOTf; thus, from3a-e as donors and lactose derivatives8A, B as acceptors the ganglioside building blocks9A and9B, respectively, were obtained in good yields. The best results were obtained with diethyl phosphite derivative3a as sialyl donor, which exceeded by far the reults obtained with the corresponding phosphate derivative4a. Trisaccharide9B was transformed into known9A and into the fullyO-acetylated GM₃-trisaccharide10.     

The effects of chemicals on the phenotypic expression of aVestigial mutant inDrosophila melanogaster

Several kinds of chemicals were tested to determine their effects on the wings of avestigial mutant inDrosophila melanogaster. Two isogenic strains were used, viz.vg-ms andB; vg-ms, both co-isogenic with the Oregon-isogenic strain. Ammonium lactate was found to have a conspicuous effect in enlarging thevestigial wings. At an appropriate concentration of this agent the wings of thevg-ms- andB;vg-ms-co-isogenic strains were restored almost to wild-type wing at 27°C. This fact indicates that the wings of thevg-ms mutant can be restored to wild type not only by temperature but also by certain chemicals. Ammonium lactate was effective conspicuously on bothBar andvestigial-ms mutants. However, there was found an interaction betweenBar andvestigial-ms when these genes were combined. The manifestation ofB is enhanced byvg-ms, especially under the the condition of feeding in medium containing the chemical, and the manifestation ofvg-ms is reduced byB.This work forms part of a thesis for the doctorate of Kyoto University.     

Alternate promoters direct stress-induced transcription of the Bacillus subtilis clpC operon

clpC ofBacillus subtilis is part of an operon containing six genes. Northern blot analysis suggested that all genes are co-transcribed and encode stress-inducible proteins. Two promoters (P_A and P_B) were mapped upstream of the first gene. P_A resembles promoters recognized by the vegetative RNA polymerase Eσ^A. The other promoter (P_B) was shown to be dependent on σ^B, the general stress σ factor in B. subtilis, suggesting that clpC, a potential chaperone, is expressed in a σ^B-dependent manner. This is the first evidence that σ^B in B, subtilis is involved in controlling the expression of a gene whose counterpart, clpB, is subject to regulation by σ³² in Escherichia coli, indicating a new function of σ^B-dependent general stress proteins. P_B deviated from the consensus sequence of σ^B promoters and was only slightly induced by starvation conditions. Nevertheless, strong induction by heat, ethanol, and salt stress occurred at the σ^B-dependent promoter, whereas the vegetative promoter was only weakly induced under these conditions. However, in a sigB mutant, the σ^A-like promoter became inducible by heat and ethanol stress, completely compensating for sigB deficiency. Only the downstream σ^A-like promoter was induced by certain stress conditions such as hydrogen peroxide or puromycin. These results suggest that novel stress-induction mechanisms are acting at a vegetative promoter. Involvement of additional elements in this mode of induction are discussed.     

Tissue-specific interplay between copper uptake and efflux in Drosophila

The vinegar fly Drosophila melanogaster is proving to be an excellent system to study the in vivo regulation of the essential metal copper. The Ctr1A/B and DmATP7 copper transport proteins have well-established roles in Drosophila copper uptake and efflux, respectively. Both Ctr1A and DmATP7 are essential genes, whereas Ctr1B mutants are viable but die in excess or depleted copper conditions. Less is known about the tissue-specific requirements for these three genes and how they interact to maintain copper homeostasis in different cell types. Here, we use targeted overexpression and suppression of each gene to examine these questions in vivo. We find that in the epidermal cells that form the adult thoracic and abdominal cuticle, Ctr1A plays a major role in copper uptake, whereas Ctr1B plays only a minor supporting role and DmATP7, as previously shown, is essential for transfer of copper to the trans-Golgi network. We also find that the copper chaperone dSco1 appears necessary for supplying the mitochondria with copper in these tissues. In contrast, in the developing Drosophila eye, DmATP7 appears to be non-essential unless copper levels in these cells are artificially elevated. Again, Ctr1A is the main copper uptake gene in the eye, but when ectopically expressed, Ctr1B has greater phenotypic effects than Ctr1A. Furthermore, Ctr1A and Ctr1B show a dramatic synergistic interaction, indicating their relationship is more complicated than a simply additive one and that they may in fact act cooperatively for optimal copper import.     

A genetical and biochemical study of chlorate-resistant mutants ofSalmonella typhimurium

S.typhimurium can form nitrate reductase A, chlorate reductase C, thiosulfate reductase, tetrathionate reductase and formic dehydrogenase. None of these enzymes are formed in chlorate-resistant mutants. Conjugation experiments showed the presence of a strong linkage between thechl andgal markers of the bacterial chromosome. By deletion mapping the gene ordernic A aro G gal bio chl D uvr B chl A was found. Strains with deletions terminating betweenbio anduvr B or betweenuvr B andchl A have a number of aberrant properties. Though resistant against chlorate they reduce nitrate and form gas. After growth with nitrate they form less nitrate reductase than the wild type which may explain the resistance against chlorate. After growth with thiosulfate they form small amounts of thiosulfate reductase and chlorate reductase C. In crosses between anE.coli Hfrchl ⁺ strain and aS.typhimurium chl A strain recombinants were obtained, forming nitrate reductase A and chlorate reductase C. These recombinants do not form gas, which indicates that thechl ⁺ gene fromE.coli does not function normally inS.typhimurium.The author is very gratefull to Miss C. W. Bettenhaussen, Miss W. M. C. Kapteijn and Mr. K. Pietersma for technical assistance. Helpfull suggestions of Dr. P. van de Putte (Medical Biological Laboratory of the National Defence Organization TNO, Rijswijk) are gratefully acknowledged.     

Maximum yield and the C-D effects in natural white birch stands

The competition-density effect for natural Japanese white bitch (Betula platyphylla var.japonica) stands, located in the northern part of Hokkaido Island, was examined for various growth stages to establish mean tree weight-density relationships over a considerable extent of stand growth of white birch. Aboveground yields of investigated stands ranged from 16.0 to 161.7 t·ha⁻¹, and it was recognized that maximum aboveground yield of this species was about 160 t·ha⁻¹. ConstantsA andB of the reciprocal equation of the C-D effect, 1/w=AN+B (w, mean tree weight; N, tree density), were related to mean height classes of birch stands. ConstantB was related to the entire mean height classes as the allometric relationship. On the other hand, constantA had an allometric relationship to mean height classes under 16 m, but became fixed over the 16 m class. White birch stands can come up to the maximum yield approximately at the stage of the 16 m class. The asymptotic tendency seemed to be appropriate for constantA-mean height class relationship. The maximum yield of white birch stands was predicted by the asymptotic value ofA. The trend of mean tree weight-density relationships with stand growth also changed with constantA. It was considered that maximum yield was an important characteristic for practical applications of the C-D effect to agriculture and forestry.     

Genetic definition of a further gene region and identification of at least three different histocompatibility genes in the rat major histocompatibility system

Two new recombinant haplotypes of the rat major histocompatibility system,RT1, have been detected in [LEW.1A (RT1 ^a ) ×LEW.1W (RT1 ^u )] × LEW 1N(RT1 ⁿ ) segregating hybrids. Recombinantr3 carries theRTL1. A region (determining classical transplantation antigens) and theRT1.B region (determining strong mixed lymphocyte reactivity and genetic control of antipolypeptide immune responsiveness) of the RT1^a parent, bur rejects RT1^a skin grafts. Recombinantr4 carries theA andB regions of the RT1^u parent, but rejects RT1^u skin grafts. The two histocompatibility genes detected are allelic to each other. The relevant locus, designated asH-C, maps to theB-region side of theRT1 system and appears to mark a thirdRT1 gene region,RT1.C. Availability of haplotypes r3 andr4 allowed the definition of a histocompatibility locus in theB region,H-B. The products ofH-C, H-B and of the previously describedH-A gene vary in antigenic strength.     

The sequence of electron carriers in the reaction of cytochromec oxidase with oxygen

Kinetic studies of the electron transfer processes performed by cytochrome oxidase have assigned rates of electron transfer between the metal centers involved in the oxidation of ferrocytochromec by molecular oxygen. Transient-state studies of the reaction with oxygen have led to the proposal of a sequence of carriers from cytochromec, to Cu_A, to cytochromea, and then to the binuclear (i.e., cytochromea ₃-Cu_B) center. Electron exchange rates between these centers agree with relative center-to-center distances as follows; cytochromec to Cu_A 5–7 Å, cytochromec to cytochromea 20–25 Å, Cu_A to cytochromea 14–16 Å and cytochromea to cytochrome a₃-Cu_B 8–10 Å. It is proposed that the step from cytochromea to the binuclear center is the key control point in the reaction and that this step is one of the major points of energy transduction in the reaction cycle.     

The growth analysis of water hyacinth,Eichhornia crasipes solms,in different water temperature conditions

A 40-day culture experiment of water hyacinth was made in 4 different water temperatures, 15, 20, 25 and 30°C, which were combined with 4 levels of concentration of culture solution, 1/3, 1, 3 and 9-fold of the standard solution containing 28 ppm of totalN and 7.7 ppm of totalP. The optimum condition for obtaining the maximum plant growth shifted from 30°C: 3-fold condition in the early stage to 20–25°C: 3-fold condition in the later stages of the experiment. The relation between the fresh weight biomass per 100-l tank,w, and the concentration of culture solution,f, was expressed successfully by a reciprocal equation,1/w=A F/f+A F ^′f/(1-f/C F)+B F, in whichA f,A f′, andB f are time dependent coefficients andC f is the upper limit of the concentration to permit plant growth which can change with time. The relation betweenw and water temperature,T, was expressed by another reciprocal equation,1/w=A T/e ^aT+A T^′e^bT+B T, in whicha andb are constants andAt At′ andB t are time dependent coefficients. The latter formulation shows that the temperature can be breated as an exponential factor, and it suggests the possibility of the growth coefficient of the logistic growth equation, ψ, being affected by temperature.     

Resolution and reconstitution of complex V of the mitochondrial oxidative phosphorylation system: properties and composition of the membrane sector

The antigenic properties of purified glycinin subunits were studied using antibodies prepared against them. Antisera against native glycinin did not react with the isolated subunits, and antibodies prepared against the purified subunits were not active against native glycinin. When native glycinin -was denatured, the antiglycinin immunoglobulins lost their ability to react with it, although the denatured complex was then recognized by antibodies against the purified subunits. Substantial structural rearrangement apparently occurred when the native complex was denatured and disaggregated. Acidic polypeptides A_1a, A_1b, and A₂ had similar determinants as judged by their reactions against A_1a and A_1a antisera. The reaction of the A₃ polypeptides with these antibodies was of lower intensity and in each case clear spurs of cross-reactivity were visible. No cross-reaction was detected between polypeptide A₄ and either anti-A_1a or A₂. Anti-A₃ antibodies reacted with each of the acidic polypeptides of glycinin, and distinct spurs of cross-reactivity were observed between A₃ vs A_1a, A₃ vs A₂, and A₃ vs A₄. B₁ Antisera developed a reaction of identity between basic polypeptides B₁ and B₂, but reacted very weakly with B₃ and B₄. The acidic and basic polypeptides of glycinin were immunologically unrelated. The results demonstrated that immunological tests would successfully differentiate some members of the family of acidic subunits, and other immunoglobulins would discriminate between members of the family of basic subunits.     

Examination of fungal growth and aflatoxin production on marihuana

Under favorable growth conditions,Aspergillus flavus andA. parasiticus produced aflatoxins on marihuana. Cultures ofA. flavus ATCC 15548 produced both aflat oxin B₁(AFB₁) and G₁(AFG₁). The production of AFG₁ was substantially greater than that of AFB₁. Cultures ofA. flavus NRRL 3251 andA. parasiticus NRRL 2999 produced only AFB₁. All natural flora cultures tested negative for aflatoxins. NoAspergilli sporulations were observed in these cultures. In the cultures inoculated with known toxigenic fungi, the highest mean level for total aflatoxins was 8.7 g/g of medium. Marihuana appears not to yield large quantities of these mycotoxins but sufficient levels are present to be a potential health hazard for both the user and the forensic analyst who is in daily contact with such plant material. Careful processing, storage, and sanitation procedures should be maintained with marihuana. If these conditions are disregarded due to the illicit status of marihuana, the potential for mycotoxin contamination must be considered.     

INDUCTION OF ANTHERIDIA IN ASCOBOLUS STERCORARIUS

Sexual organs develop in the hermaphroditic, heterothallic ascomycete Ascobolus stercorarius only when strains of opposite mating-type are paired under appropriate conditions. A previous study of the two reciprocal compatible interactions, A-antheridial/a-ascogonial and a-antheridial/A-ascogonial, revealed several differences between them. The present study of the induction of antheridia has uncovered several other differences. Such induction occurred on severed hyphae, non-germinated oidia and germinated oidia of mating-type A but not of a under two different sets of conditions: (1) when such elements were placed on an agar medium containing only the secretions of a compatible mycelium, and (2) when they were in close proximity to a second group of compatible non-germinated or germinating oidia on an agar surface. This tendency for vegetative elements of A to differentiate as male structures more readily than those of a is consistent with the previous observation that the interaction of A-antheridial/a-ascogonial is generally the more vigorous one. It may also be responsible for a condition approaching functional sexual dimorphism in many mixed (A + a) mycelial cultures.     

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.     

Hydrophobicity of biosurfaces as shown by chemoreceptive Thresholds inTetrahymena,Physarum andNitella

Summary Responses (chemotaxis and changes in membrane potential) ofTetrahymena, Physarum, andNitella against aqueous solution of homologous series ofn-alcohols,n-aldehydes andn-fatty acids were studied for clarifying the hydrophobic character of chemoreceptive membranes. Results were: (1) All organisms studied responded to homologous compounds examined when the concentration of these chemicals exceeded their respective threshold,C _th , and the response,R, were expressed approximately asR= log (C/C _th ) forC>C _th , (2) Increase of the length of hydrocarbon chain in homologues decreasedC _th . Plots of logC _th against the number of carbon atoms,n, inn-alcohols,n-aldehydes andn-fatty acids showed linear relationships as represented by logC _th =–An+B. A andB are positive constants for respective functional end groups of the chemicals and biological membranes used. The above empirical equation was interpreted in terms of the partition equilibrium of methylene groups between bulk solution and membrane phase. ParameterA was shown to be a measure of hydrophobicity of the membrane, andB represented the sensitivity of chemoreception of the membrane. (3) Thresholds,C _th , for various hydrophobic reagents were compared with those of human olfactory reception,T. Plots of logT against logC _th fell on straight lines for respective organisms with different slopes which were proportional to parameterA.     

Structure and genomic organization of centromeric repeats in<Emphasis Type="Italic"> Arabidopsis</Emphasis> species

Centromeric repetitive sequences were isolated from Arabidopsis halleri ssp. gemmifera and A. lyrata ssp. kawasakiana. Two novel repeat families isolated from A. gemmifera were designated pAge1 and pAge2. These repeats are 180 bp in length and are organized in a head-to-tail manner. They are similar to the pAL1 repeats of A. thaliana and the pAa units of A. arenosa. Both A. gemmifera and A. kawasakiana possess the pAa, pAge1 and pAge2 repeat families. Sequence comparisons of different centromeric repeats revealed that these families share a highly conserved region of approximately 50 bp. Within each of the four repeat families, two or three regions showed low levels of sequence variation. The average difference in nucleotide sequence was approximately 10% within families and 30% between families, which resulted in clear distinctions between families upon phylogenetic analysis. FISH analysis revealed that the localization patterns for the pAa, pAge1 and pAge2 families were chromosome specific in A. gemmifera and A. kawasakiana. In one pair of chromosomes in A. gemmifera, and three pairs of chromosomes in A. kawasakiana, two repeat families were present. The presence of three families of centromeric repeats in A. gemmifera and A. kawasakiana indicates that the first step toward homogenization of centromeric repeats occurred at the chromosome level.Communicated by W. R. McCombie     

Staphylococcal plasmid cointegrates are formed by host- and phage-mediated general rec systems that act on short regions of homology

Summary Cointegrates involving pairs of compatible staphylococcal plasmids can be isolated either by co-selection during transduction (Novick et al. 1981) or by selection for survival at the restrictive temperature of a thermosensitive, replication defective plasmid in the presence of a stable one. Cointegrates are formed by recombination at two specific sites, RS_A and RS_B. RS_B is present on each of six plasmids analyzed, namely pT181, pE194, pC194, pS194, pUB110, and pSN2, and RS_A is present on two of these, pT181 and pE194. In this communication, it is shown that the RS represent short regions of homology (RS_A is some 70 bp in length and RS_B is about 30) embedded in largely non-homologous contexts and that the crossovers take place within these homologous regions. The pT181 and pE194 RS_A sequences contain several mismatches which permit the localization of the crossover events to several different sites within the overall RS segment. The recombination system involved is therefore general (homology-specific) rather than site-specific (sequence-specific). Mismatches included within the crossover region are always corrected to the pT181 configuration. The cointegrates are therefore formed by a relatively efficient general rec system that recognizes short regions of homology and gives rise to Holliday junctions that probably involve very short heteroduplex overlaps. The sequence results are consistent with asymmetric single-strand invasion of a contralateral gap with nucleotide conversion by copying. It is noted that RS_B has substantial homology with the par sequence of plasmid pSC101, suggesting that it may be involved in plasmid partitioning.     

Study of the effect of mutations in DNA repair genes on the thermal induction of error-free repair inEscherichia coli

Previous studies from this laboratory have shown that heat shock can induce alon gene-dependent, error-free DNA repair process in certain strains ofEscherichia coli. Further experiments have now shown that the phenomenon is dependent upon therecA, uvrA, anduvrB genes. However,lexA^– anduvrC^– strains still show the effect, although at a reduced level, so the corresponding proteins may not be essential. None of the mutations affects the induction of thermotolerance; this proves that two separate pathways are involved.