SOCIAL SELECTION AND THE EVOLUTION OF ANIMAL SIGNALS

Social selection is presented here as a parallel theory to sexual selection and is defined as a selective force that occurs when individuals change their own social behaviors, responding to signals sent by conspecifics in a way to influence the other individuals' fitness. I analyze the joint evolution of a social signal and behavioral responsiveness to the signal by a quantitative-genetic model. The equilibria of average phenotypes maintained by a balance of social selection and natural selection and their stability are examined for two alternative assumptions on behavioral responsiveness, neutral and adaptive. When behavioral responsiveness is neutral on fitness, a rapid evolution by runaway selection occurs only with enough genetic covariance between the signal and responsiveness. The condition for rapid evolution also depends on natural selection and the number of interacting individuals. When signals convey some information on signalers (e.g., fighting ability), behavioral responsiveness is adaptive such that a receiver's fitness is also influenced by the signal. Here there is a single point of equilibrium. The equilibrium point and its stability do not depend on the genetic correlation. The condition needed for evolution is that the signal is beneficial for receivers, which results from reliability of the signal. Frequency-dependent selection on responsiveness has almost no influence on the equilibrium and the rate of evolution.     

Purification of almond emulsin alpha-L-fucosidase I by affinity chromatography.

An affinity chromatographic method to purify α-l-fucosidase I from almond emulsin was developed. A derivative of lacto-N-fucopentaose II, ?-aminocaproyl-lacto-N-fucopentaosylamine, was coupled to sepharose 4B and packed in a column. By adopting this column for affinity chromatography, the enzyme was purified a hundredfold. The enzyme preparation was free from any other exoglycosidases which act on natural substrates.     

Heritability estimates of phenthoate resistance in the diamond-back moth

Realized heritabilities were estimated for the character of phenthoate resistance in two local strains of the diamond-back moth, Plutella xylostella L. (Lepidoptera: Yponomeutidae), by performing artificial laboratory selection for resistance and susceptibility to phenthoate. Heritability estimates indicated that such traits are moderately heritable ( ²=0.42 and 0.41 in the resistant selection and ²=0.31 and 0.21 in the susceptible selection), and give an experimental basis accounting for rapid evolutionary changes of phenthoate resistance observed in field populations of this insect.The observed changes in variances of phenthoate susceptibility are discussed in relation to the additive genetic variance eliminated by directional selection. The explanation stresses the importance on the underlying genetic system.

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Résumé L'héritabilité de la résistance au phenthoate obtenue chez deux souches locales de P. xylostella L. (Lep.; Yponomeutidae) a été calculée en procédant au laboratoire à des sélections artificielles pour la résistance et pour la sensibilité à cet insecticide. Les calculs de l'héritabilité ont montré que de tels caractères sont moyennement héritables ( ²=0,42 et 0,41 lors de la sélection pour la résistance, et ²=0,31 et 0,21 lors de la sélection pour la sensibilité), et ont fourni la base expérimentale rendant compte des changements évolutifs rapides observés pour la résistance au phenthoate chez des populations naturelles de cet insecte.Les changements observés de la variance de la sensibilité au phenthoate sont discutés en fonction de la variance génétique additive éliminée par la sélection orientée. L'explication insiste sur l'importance du système génétique souligné.

     

Construction and expression of human aldolase A and B expression plasmids in Escherichia coli host

E. coli expression plasmids for human aldolases A and B (EC 4.1.2.13) have been constructed from the pIN-III expression vector and their cDNAs, and expressed in E. coli strain JM83. Enzymatically active forms of human aldolase have been generated in the cells when transfected with either pHAA47, a human aldolase A expression plasmid, or pHAB 141, a human aldolase B expression plasmid. These enzymes are indistinguishable from authentic enzymes with respect to molecular size, amino acid sequences at the NH2- and COOH-terminal regions, the Km for substrate, fructose 1,6-bisphosphate and the activity ratio of fructose 1,6-bisphosphate/fructose 1-phosphate (FDP/F1P), although net electric charge and the Km for FDP of synthetic aldolase B differed from those for a previously reported human liver aldolase B. In addition, both the expressed aldolases A and B complement the temperature-sensitive phenotype of the aldolase mutant of E. coli h8. These data argue that the expressed aldolases are structurally and functionally similar to the authentic human aldolases, and would provide a system for analysis of the structure-function relationship of human aldolases A and B.     

Formation of glycine conjugate and (-)-(R)-enantiomer from (+)-(S)-2-phenylpropionic acid suggesting the formation of the CoA thioester intermediate of (+)-(S)-enantiomer in dogs.

It has been proposed that the chiral inversion of the 2-arylpropionic acids is due to the stereospecific formation of the (-)-R-profenyl-CoA thioesters which are putative intermediates in the inversion. Accordingly, amino acid conjugation, for which the CoA thioesters are obligate intermediates, should be restricted to those optical forms which give rise to the (-)-R-profenyl-CoA, i.e., the racemates and the (-)-(R)-isomers. We have examined this problem in dogs with respect to 2-phenylpropionic acid(2-PPA). Regardless of the optical configuration of 2-phenylpropionic acid administered, the glycine conjugate was the major urinary metabolite and this was shown to be exclusively the (+)-(S)-enantiomer by chiral HPLC. Both (-)-(R)- and (+)-(S)-2-phenylpropionic acid were present in plasma after the administration of either antipode, and further evidence of the chiral inversion of both enantiomers was provided by the presence of some 25% of the opposite enantiomer in the free 2-phenylpropionic acid and its glucuronide excreted in urine after administration of (-)-(R)- and (+)-(S)-2-phenylpropionic acid. The (+)-(S)-enantiomer underwent chiral inversion to the (-)-(R)-antipode when incubated with dog hepatocytes. These data suggests that both enantiomers of 2-phenylpropionic acid are substrates for canine hepatic acyl CoA ligase(s) and thus undergo chiral inversion, but that the CoA thioester of only (+)-(S)-2-phenylpropionic acid is a substrate for the glycine N-acyl transferase. These studies are presently being extended to the structure and species specificity of the reverse inversion and amino acid conjugation of profen NSAIDs.     

Cloning and sequence analysis of a snake, Atractaspis engaddensis gene encoding sarafotoxin S6c.

A 469 base pair genomic DNA, which encodes the mature region of a snake cardiotoxic peptide, sarafotoxin S6c, was isolated from the liver of the burrowing asp, Atractaspis engaddensis. The nucleotide sequence encoding the mature peptide region showed a high sequence homology with those of mammalian vasoconstrictor peptides, endothelin family as expected from the high homology of their amino acid sequences. In contrast, both of the upper and lower flanking sequences of sarafotoxin gene and the deduced amino acid sequence of the sarafotoxin precursor were quite different from those of endothelin family. These results suggest that the ancestral gene and biosynthetic pathway of sarafotoxins are different from those of endothelin.     

Structure-receptor binding relationships of sarafotoxin and endothelin in porcine cardiovascular tissues

The specific binding of 125I-sarafotoxin S6b was observed in the microsomal fractions from porcine thoracic aorta, and two vasoconstrictive peptides with strikingly homologous structures, sarafotoxin (SRT) and endothelin (ET), interact with a common receptor of the vasculature. The order of the potency of an each endothelin or sarafotoxin analogue as a competitor against 125I-sarafotoxin S6b binding was ET-1 greater than ET-2 greater than SRT S6b greater than ET-3 much greater than SRT S6c. The hydrophobic carboxyl-terminal tail and intramolecular disulfide bridges are essential for the binding activity. In addition, Ser4, Ser5 and Lys9 seem to be important for the activity while the 6th residue does not affect the activity.     

Details of Retropositional Genome Dynamics That Provide a Rationale for a Generic Division: The Distinct Branching of All the Pacific Salmon and Trout (Oncorhynchus) from the Atlantic Salmon and Trout (Salmo)

Salmonid species contain numerous short interspersed repetitive elements (SINEs), known collectively as the HpaI family, in their genomes. Amplification and successive integration of individual SINEs into the genomes have occurred during the evolution of salmonids. We reported previously a strategy for determining the phylogenetic relationships among the Pacific salmonids in which these SINEs were used as temporal landmarks of evolution. Here, we provide evidence for extensive genomic rearrangements that involved retropositions and deletions in a common ancestor of all the Pacific salmon and trout. Our results provide genetic support for the recent phylogenetic reassignment of steelhead and related species from the genus Salmo to the genus Oncorhynchus. Several other informative loci identified by insertions of HpaI SINEs have been isolated, and previously proposed branching orders of the Oncorhynchus species have been confirmed. The authenticity of our phylogenetic tree is supported both by the isolation of more than two informative loci per branching point and by the congruence of all our data, which suggest that the period between succesive speciations was sufficiently long for each SINE that had been amplified in the original species to become fixed in all individuals of that species.