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Groups of Aotus (owl) monkeys were immunized with either the Plasmodium falciparum merozoite surface-coat precursor protein and its processing fragments or a complex of high molecular mass rhoptry proteins and challenged with a lethal infection of the homologous P. falciparum Uganda Palo Alto (FUP) strain. No patent parasitemia could be detected on thick blood films of monkeys immunized with the merozoite surface antigens; however, only one of three monkeys immunized with the rhoptry proteins was partially protected, while two required drug therapy. The experiment clearly demonstrates that the merozoite surface-coat precursor protein can completely protect Aotus monkeys against a lethal infection of the human malaria parasite.

I assemble stable multispecies Lotka-Volterra competition communities that differ in resident species number and average strength (and variance) of species interactions. These are then invaded with randomly constructed invaders drawn from the same distribution as the residents. The invasion success rate and the fate of the residents are determined as a function of community-and species-level properties. I show that the probability of colonization success for an invader decreases with community size and the average strength of competition (alpha). Communities composed of many strongly interacting species limit the invasion possibilities of most similar species. These communities, even for a superior invading competitor, set up a sort of "activation barrier" that repels invaders when they invade at low numbers. This "priority effect" for residents is not assumed a priori in my description for the individual population dynamics of these species; rather it emerges because species-rich and strongly interacting species sets have alternative stable states that tend to disfavor species at low densities. These models point to community-level rather than invader-level properties as the strongest determinant of differences in invasion success. The probability of extinction for a resident species increases with community size, and the probability of successful colonization by the invader decreases. Thus an equilibrium community size results wherein the probability of a resident species' extinction just balances the probability of an invader's addition. Given the distribution of alpha it is now possible to predict the equilibrium species number. The results provide a logical framework for an island-biogeographic theory in which species turnover is low even in the face of persistent invasions and for the protection of fragile native species from invading exotics.

The early reactions in the catabolism of quinic acid in Neurospora crassa are controlled by at least four genes which are clustered on linkage group VII. Three of the loci (qa-2, qa-4, and qa-3) encode enzymes that convert quinic acid to protocatechuic acid. The fourth gene (qa-1) encodes a positive regulatory protein which, in the presence of quinic acid, leads to the de novo synthesis of the other proteins in the qa cluster. This communication describes a series of recombinant plasmids that span 36.5 kilobases of linkage group VII and contain the coding sequences for qa-2, qa-4, qa-3, and the qa-1 regulatory protein. The plasmids were obtained by partial digestion of wild-type N. crassa DNA with EcoRI and ligation into the cosmid cloning vehicle pHC79. Two independently derived plasmids (pMSK331 and pMSK335), each containing 36.5-kilobase inserts, were shown by transformation back into N. crassa to contain the entire qa gene cluster. A preliminary physical organization of the gene cluster is presented. An improved procedure for the transformation of N. crassa with plasmid DNA is also described.

A coevolutionary model of species packing is developed that allows evolutionary adjustment in both niche position and within-phenotype niche width of one-three competing species. The environment is specified as a single resource dimension xand availability of resources along xis given by a gaussian curve that has parameters x[unk]Rand σR. The model predicts that, for Sspecies, the ratio of optimal niche width w[unk] to σRis roughly independent of σRand can be approximated by 1/Swhen the competitors are completely resource limited. Niche separation (d[unk]/w[unk]) increases only moderately with increases in resource diversity σRand is greater for two than for three competing species. To the extent that the competitors are not completely resource limited, both coevolutionary niche separation and niche width decrease. Many of the general trends in niche width and niche separation predicted by this coevolutionary model parallel those from optimal foraging theory and limiting similarity models of community structure. The coevolutionary model stands out, however, in the singularly high values predicted for niche separation, making coevolved communities highly invasible. Hence, the theory suggests, as some empirical evidence indicates, that coevolved competition communities can only eixst as such on remote islands or in other habitats that might be free from invasion by outside species.

Transcriptional activation of the Neurospora crassa qa genes normally requires the positive regulatory gene, qa-1F+, whose function is controlled by the inducer quinic acid and by the product of the negative regulatory gene, qa-1S+. The properties of qa-1F+ activator have been examined in transcriptional mutations of the qa-2 structural gene, in which activator-independent transcription of qa-2 (qa-2ai mutants) occurs in strains having a qa-1F- gene. Seven qa-2ai mutants with DNA rearrangements in different 5' regions of qa-2 were analyzed in qa-1F+ strains. In five with rearrangements at position -190 or further upstream, expression of the qa-2 gene was inducible, and induction was accompanied by a change in the initiation site for transcription from position -45, characteristic of constitutive initiation in qa-2ai mutants to position +1, characteristic of the induced wild type. In two mutants with breakpoints at positions -86 and -53, qa-2 transcription initiated from upstream sequences within the rearrangements but not at the +1 site, and qa-2 expression was noninducible. The results indicate that (i) sequences between positions -190 and -86 are required for positive control of initiation at position +1, and (ii) negative control does not require sequences downstream of position -86. Additional evidence suggests that the product of the qa-1F+ gene in the noninduced state may also interact with distal upstream sequences positioned midway between divergently transcribed qa genes.

Elucidating earlier work, it is shown that the Kadomtsev-Petviashvili equation has n+ 2 constants for all n≥ 0. It also has a pseudo-constant from which the constants can be obtained by differentiation with respect to time. The pseudo-constant can be obtained from a basis functional Jn(n+2)= -1/18 [unk] yn+2qby taking repeated Poisson brackets with the Hamiltonian.

Adjuvant arthritis in rats is a T-cell dependent "autoimmune" disease with close similarities to several forms of human arthritis. Injection of mycobacterial adjuvant leads to T-cell activation and proliferation, processes in which the de novo expression of the interleukin 2 (IL-2) receptor plays a pivotal role. The subsequent massive mononuclear cell infiltration of the joints ultimately results in complete joint destruction. Because activation of the helper/inducer subset of T lymphocytes is critical to the establishment of disease, we reasoned that IL2-PE40, a cytotoxic IL-2-Pseudomonas exotoxin fusion protein that targets the membrane-penetration and ADP-ribosylation domains of the toxin to cells bearing the IL-2 receptor, would be an effective and specific therapy. Adjuvant-injected rats were randomized to treatment with IL2-PE40, phosphate-buffered saline, or either of two control proteins related to IL2-PE40 but lacking either the receptor-binding moiety or an enzymatically active toxin domain and previously demonstrated to lack cytotoxicity in vitro. Intraperitoneal IL2-PE40 given before the establishment of overt clinical disease proved an effective and specific modifier of adjuvant arthritis by clinical, histological, and radiographic criteria. Our data suggest that IL2-PE40 may be effective in those diseases in which activated T-cells play an important role.

To test the hypothesis that the evolution of organisms is dependent to a large degree on gene rearrangement, we devised a way of estimating rates of evolutionary change in karyotype. This non-biochemical method is based on consideration of chromosomal variability within taxonomic groups having a fossil record. The results show that chromosomal evolution has been faster in placental mammals than in other vertebrates or molluscs. This finding is consistent with published evidence that placentals have also been evolving unusually fast in anatomy and way of life. However, the structural genes of placentals seem not to have experienced accelerated evolution. Possibly, therefore, anatomical evolution may be facilitated by gene rearrangement. To explain how placentals achieved this rate of chromosomal evolution, we consider the process by which a new gene arrangement becomes fixed and spreads. The structure and dynamics of placental populations may be especially favorable for this process. The key factor involved seems to be the type of social behavior which produces small effective population sizes and inbreeding. As Bush points out elsewhere, such social structuring of populations may promote rapid fixation of gene rearrangements and rapid speciation.

The first three reactions in the catabolism of qainic acid in Neurospora crassa are under the genetic control of the qa gene cluster. This cluster consists of three structural genes encoding three inducible enzymes plus a regulatory gene (qa-1+) whose diffusible product apparently acts in a positive fashion to initiate coordinate synthesis of the three enzymes when an appropriate inducer is present. Genetic and biochemical evidence for both complementing and temperature-sensitive qa-1 alleles indicates that the product of the qa-1+ gene is an oligomeric (multimeric) protein. On the basis of cis-trans tests of appropriate double mutants (plus genetic mapping data for temperature-sensitive mutants), at least certain constitutive mutants (which produce all three qa enzymes in the absence of an inducer) are mutants in the regulatory gene and not in controlling elements such as initiators. The detection of stable (non-revertible) qa-1 intralocus deletion (multisite)mutants provides additional evidence for positive regulation in the qa system. Extensive genetic recombination data provide evidence that the two types of qa-1 mutants--slow-complementing (qa-1-s) and fast-complementing (qa-1-f)--map in discrete, non-overlapping segments of the qa-1 locus. These two distinct types of mutants are hypothesized to produce altered regulatory protein molecules that fail to interact either with a DNA initiator site (qa-1-s types) or with an inducer (qa-1-f types). The striking similarities between the qa system in this lower eukaryote and certain prokaryote operon systems are discussed.

An efficient transformation system has been developed for Neurospora crassathat uses spheroplasts and pVK88 plasmid DNA. pVK88 is a recombinant Escherichia coliplasmid carrying the N. crassa qa-2+gene which encodes catabolic dehydroquinase (3-dehydroquinate hydro-lyase, EC 4.2.1.10) and is part of the qagene cluster. The recipient strain carries a stable qa-2-mutation and an arom-9-mutation, thus lacking both catabolic and biosynthetic dehydroquinase activities. Transformants were selected as colonies able to grow in the absence of an aromatic amino acid supplement. These colonies were qa-2+and had normal levels of catabolic dehydroquinase. DNA·DNA hybridization evidence with appropriate labeled probes indicates clearly that in some instances transformation involves the integration of bacterial plasmid sequences together with the qa-2+gene into the N. crassagenome. On the basis of genetic, enzyme assay, and DNA hybridization data, at least three types of transformation events can be distinguished: (i) replacement of the qa-2-gene by the qa-2+gene without any effect on the expression of the other genes in the qacluster, (ii) linked insertion of a normal qa-2+gene accompanied by inactivation of the adjacent qa-4+gene, and (iii) insertion of a normal qa-2+gene at an unlinked site in the N. crassagenome. This newly integrated qa-2+genetic material is inherited in a typical Mendelian fashion. A low level of transformation has also been obtained by using linear total N. crassaDNA. Two such qa-2+transformants are unlinked to the qa-2-gene of the recipient.

Autoradiographic localization of [3H]flunitrazepam in nuclei of the rat cerebral cortex was further confirmed by biochemical analysis of specific nuclear binding. Highly purified rat cerebral cortex nuclei were shown to bind [3H]flunitrazepam specifically. The Kd(app) for nuclear binding was 28 nM for the nuclei compared with a Kd(app) of 1.1 nM for binding of [3H] flunitrazepam to synaptosomal membrane fractions of the same tissue. Inhibition of the nuclear binding with inosine and hypoxanthine was greater than inhibition of the synaptic membrane fractions. These results lead to to conclude that specific binding may occur at both the synaptic membrane and the nuclear levels and that different endogenous ligands may compete at each site for binding. Furthermore, the possibility exists for translocation and alteration of the bound ligand complex from membrane site to nuclear site.

A hybrid pBR322 plasmid (designated pDV1001) containing two functional Escherichia coli antibiotic resistance genes (kanr and camr) and a qa-2+ gene from Neurospora crassa transforms N. crassa qa-2- mutants to qa-2+ with a frequency of ca. 5 X 10(-5) per regenerated spheroplast (ca. 100 transformants per microgram of plasmid DNA). This plasmid can replicate autonomously without integrating into the N. crassa genome. The autonomously replicating hybrid plasmid was detected in N. crassa transformants by Southern gel hybridizations. DNA from these transformants can be recovered by retransformation back into E. coli aroD recipients and selection for chloramphenicol resistance. These E. coli transformants complement an aroD mutant. The hybrid plasmid DNA present in the E. coli transformants remains unchanged on the basis of DNA restriction enzyme analyses. The original, nonhomokaryotic N. crassa transformants can be maintained on a selective medium, but there is as yet no evidence that the self-replicating plasmid can be transmitted through meiosis. In addition, the self-replicating plasmid often integrates into the N. crassa genome and then is inherited in a generally stable fashion through meiosis. Our findings suggest that this plasmid, or some derivative of it, will prove useful as a routine shuttle vector for cloning genes in N. crassa.

To test the hypothesis that population subdivision into small demes promotes both rapid speciation and evolutionary changes in gene arrangement by inbreeding and drift, we estimated rates of speciation and rates of chromosomal evolution in 225 genera of vertebrates. Rates of speciation were estimated by considering the number of living species in each genus and the fossil record of each genus as well as information about extinction rates. Speciation rate was strongly correlated with rate of chromosomal evolution and average rates of speciation in lower vertebrate genera were one-fifth those in mammalian genera. Genera with high karyotypic diversity and rapid speciation rates may generally have small effective population size (Ne), whereas large Ne values may be associated with karyotypically uniform genera and slow rates of speciation. Speciation and chromosomal evolution seem fastest in those genera with species organized into clans or harems (e.g., some primates and horses) or with limited adult vagility and juvenile dispersal, patchy distribution, and strong individual territoriality (e.g., some rodents). This is consistent with the above hypothesis regarding the evolutionary importance of demes.

Expression of the qa-2 gene of Neurospora crassa normally requires a functional activator protein encoded by qa-1F. Twelve transcriptional mutants of the qa-2 gene have been isolated in qa-1F- strains, and these allow partial expression of qa-2 (1-45% of induced wild type) in the absence of functional activator protein. All 12 mutants have been characterized by genomic (Southern) blot hybridization and the DNAs of 5 have been cloned and sequenced. Eight mutations consist of large DNA rearrangements within a 500-base-pair region 5' to the qa-2 gene. One large rearrangement mutation, located 378 base pairs before the normal site of transcription initiation, causes exceptional levels of qa-2 transcription (45% of induced wild type) from near the normal initiation site. Two of the other four mutations cloned involve tandem duplications (68 and 84 base pairs) of the same upstream region (centered at nucleotide - 145), and two involve "point" mutations (at nucleotides -200 and -95) that closely flank the duplicated region. With one possible exception, none of the mutations appears to involve changes directly associated with RNA polymerase II binding and hence they differ from analogous mutations in comparable prokaryotic systems. The overall results suggest that at least some of the large DNA rearrangement mutations may be acting as upstream activator elements, possibly by juxtaposing enhancer-like sequences, whereas the duplications and point mutations may define a region of qa-2 regulation, for instance at the level of RNA polymerase II access.

A linear model of interspecific competition with separate parameters for exploitation and interference is deduced. Interference is assumed to have a cost and an effect. The interfering species realizes a “profit” if some resources, which the species interfered against would have utilized, are made available as a result of the interference. Interference is favored when its cost is small, its effect is high, and the resource overlap with the species interfered against is high. Interference is likely to be an alternative strategy to high exploitation efficiency. The incorporation of interference into niche theory clarifies the competitive phenomenon of unstable equilibrium points, excess density compensation on islands, competitive avoidance by escape in time and space, the persistence of the “prudent predator,” and the magnitude of the difference between the size of a species' fundamental niche and its realized niche.

In Neurospora crassa, evidence has recently been obtained for a cluster of four closely-linked genes controlling the inducible enzymes catalyzing the first three reactions in the catabolism of quinic acid. Three of these genes appear to be the structural genes for the three enzymes. The fourth gene, designated qa-1, has been interpreted as having a regulatory function, since qa-1mutants are pleiotropic types, are noninducible for the three enzymes, and form heterocaryons which complement mutants in the structural genes. The present studies were undertaken to elucidate further the nature of the regulatory role of the qa-1locus. A number of constitutive (qa-1C) mutants have been obtained from certain qa-1mutants as revertants selected for their ability to grow on quinic acid as a sole source of carbon. These qa-1Cmutants produce high levels of all three enzymes in the absence of an inducer, map within (or very close to) the qa-1locus, and produce a catabolic dehydroquinase (EC 4.2.1.10) which is indistinguishable, on the basis of thermolability tests, from that of wild type. In addition, when grown in the absence of an inducer, heterocaryons between wild-type (qa-1+) and different qa-1Cmutants exhibit markedly different levels of constitutivity (from 5 to 50% of the particular parental qa-1Cmutant) for catabolic dehydroquinase, one of the enzymes under qa-1control. These overall results are interpreted as supporting the hypothesis that the qa-1+gene product (presumably a multimeric protein) plays only a positive regulatory role in initiating synthesis of the three quinate catabolic enzymes.

Molecular weights of enzymically active aromaggregates produced by pleiotropic and various arom-1mutants of Neurospora crassahave been estimated by sucrose density gradient centrifugation. In contrast to most single-gene mutants (which produce intact arommultienzyme aggregates of normal molecular weight— about 230,000), pleiotropic mutants that lack two or more of the five enzyme activities in the aromaggregate produce partial aromaggregates of molecular weights ranging from about 60,000 to about 85,000. In addition, certain arom-1mutants are pleiotropic in producing aromaggregates of about half the normal molecular weight. Experiments with heterocaryons, as well as with mixtures of extracts from various mutants, have provided evidence concerning the presence or absence of interactions (as detectable molecular hybridization) between different aromaggregates. An evaluation has been made of the relation between the genetic location of particular mutants within the aromgene cluster and the size and enzymic content of the aromaggregates they produce. Interpretations concerning the molecular organization of the arommultienzyme aggregate in N. crassaare presented.

It is shown that the Benjamin—Ono equation is one of a hierarchy of nonlinear partial differential singular integral equations. Explicit multisoliton solutions are constructed for all equations of the hierarchy.

Many nonlinear equations arising in plasma physics, hydrodynamics, and solid-state physics can be written in Hamiltonian form. The full advantage of this is achieved only when the existence of canonical coordinates and momenta is known. Here such coordinates are exhibited for three large classes of equations—which seem to include almost all known completely integrable Hamiltonian systems.

A simple theorem in Hamiltonian mechanics is pointed out. One consequence is a generalization of the classical result that symmetries are generated by Poisson brackets of conserved functionals. General applications are discussed. Special emphasis is given to the Kadomtsev-Petviashvili equation.

A class of Bäcklund transformations for multidimensional sine-Gordon equations is shown to relate solutions of only one- and two-dimensional equations. Also, a proposed superposition principle is shown to be useless.

A theorem is deduced that reduces the problem of finding the N-soliton solution of the Benjamin-One equation to that of solving an algebraic equation of degree N.

Conserved densities for Hamiltonian systems are shown to satisfy simple linear equations. These are essentially the original equations linearized around a particular solution. A number of examples are displayed, which pertain to many systems of physical interest.