On the Divergence of Alleles in Nested Subsamples from Finite Populations

Within-population variation at the DNA level will rarely be studied by sequencing of loci of randomly chosen individuals. Instead, individuals will usually be chosen for sequencing based on some knowledge of their genotype. Data collected in this way require new sampling theory. Motivated by these observations, we have examined the sampling properties of a finite population model with two mutation processes and with no selection or recombination. One mutation process generates new alleles according to an infinite-alleles model, and the other generates polymorphisms at sites according to an infinite-sites model. A sample of n genes is considered. The stationary distribution of the number of segregating sites in a subsample from one of the allelic classes in the sample conditional on the allelic configuration of the sample is studied. A recursive scheme is developed to compute the moments of this distribution, and it is shown that the distribution is functionally independent of the number of additional alleles in the sample and their respective frequencies in the sample. For the case in which the sample contains only two alleles, the distribution of the number of segregating sites in a subsample containing both alleles conditional on the sample frequencies of the alleles is studied. The results are applied to the analysis of DNA sequences of two alleles found at the Adh locus of Drosophila melanogaster. No significant departure from the neutral model is detected.     

Reaction of triosephosphate isomerase with L-glyceraldehyde 3-phosphate and triose 1,2-enediol 3-phosphate

Triosephosphate isomerase catalyzes the isomerization and/or racemization reactions of L-glyceraldehyde 3-phosphate (LGAP), the enantiomer of the physiological substrate. The reaction is inhibited by the active site directed reagent glycidol phosphate. The amount of protonation product formation catalyzed by a fixed enzyme concentration is nearly independent of increasing steady-state concentrations of triose 1,2-enediol 3-phosphate caused by buffer catalysis of LGAP deprotonation. Therefore, enzymatic protonation of the enediol or enediolate, which could account for the observed enzymatic catalysis of LGAP isomerization and/or racemization, is at best a minor reaction. Instead LGAP reacts directly at the enzyme active site. Triosephosphate isomerase catalysis of the protonation of triose 1,2-enediol 3-phosphate was expected because of the strong evidence supporting an enediol reaction intermediate for the overall reaction catalyzed by isomerase. The most reasonable explanation for the failure to observe enzymatic protonation is that in solution the enediol undergoes beta elimination of phosphate (t 1/2 is estimated to be 10(-6) s) faster than it can diffuse to and form a complex with isomerase.     

Diagrammatic Icons and Historical Processes in Belau

In this paper I analyze the relationship between diagrammatic representations of social relations and historical processes in Belau (formerly Palau), Micronesia. Four diagrams, linear paths, balanced sides, quadripartition, and graded series, are discussed in terms of their lexical labels, schematic arrangements, prototypical embodiments, and semantic fields. Ethnographic and historical examples presented reveal the differential historical vulnerability of social institutions modeled by these diagrams. The use of Peirce's typology of signs is demonstrated to be an important corrective to the structuralist notion of transformation.     

Multiple copies of phosphorylated filaggrin in epidermal profilaggrin demonstrated by analysis of tryptic peptides

The precursor of mouse (c57/B16) epidermal filaggrin (profilaggrin) is a very large (ca. 500 000 daltons), highly phosphorylated protein containing multiple copies of filaggrin (26 000 daltons). The conversion of profilaggrin to filaggrin late in epidermal cell differentiation involves dephosphorylation and proteolysis to yield the unphosphorylated filaggrin, which polymerizes with keratin filaments into macrofibrils. In order to gain insight in the nature of these processes, we compared tryptic digests of profilaggrin with those of filaggrin by reverse-phase liquid chromatography. Approximately 80% of the profilaggrin mass consists of multiple copies of filaggrin. Twenty peptides purified in good yield from both profilaggrin and filaggrin accounted for most of the filaggrin sequence. A detailed analysis of the yield of several peptides provided an estimate of the size and frequency of the repeat unit within profilaggrin. These data indicate that the repeating substructure of profilaggrin contains about 265 amino acids and that about 50 residues are removed per filaggrin domain as the precursor is processed to filaggrin. Assuming a molecular weight of 500 000 (as estimated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis), this indicates there are 16 repeats. Analysis of phosphopeptides isolated from profilaggrin showed that 66% of the phosphate was located on peptides that are unphosphorylated in filaggrin. Analysis of peptide recoveries confirmed the repeat size and showed that every copy of filaggrin was phosphorylated in profilaggrin.     

The morphology and anatomy ofHydrastis (Ranunculales): Systematic reevaluation of the genus

Evidence from morphology and anatomy (including embryology), as well as from palynology, chemistry and cytology, indicates thatHydrastis is quite divergent from Ranunculaceae (in which the genus has been most often included) as well as from both Glaucidiaceae and Berberidaceae. Distinctive features ofHydrastis, which demarcate it from Ranunculaceae but which are sometimes shared by Berberidaceae, are: the unique mode of origin of the vascular supply to stamens and carpels; the micropyle being formed by both integuments; the xylem not V-shaped in cross section; scalariform vessel perforations present; haploid chromosome number 13; pollen tectum consisting of a compound layer of striae; leaf mesophyll not differentiated; the unique course of stem medullary bundles; D-galactose present. Its distinctive higher haploid chromosome number, as well as its many less-specialized character states (in floral structure, leaf anatomy, and xylem and vessel morphology), suggest thatHydrastis is a relictual primitive group which diverged early from a common ancestral stock of Ranunculaceae, Berberidaceae and probably of Circaeasteraceae; at least some of the features shared byHydrastis and one or another of the families concerned seem to be a heritage from their common ancestor. We propose a reestablishment of a monotypic family, Hydrastidaceae.     

In vitro response of leaf tissues from Lolium multiflorum — a comparison with leaf segment position,leaf age and in vivo mitotic activity

Summary Immature gramineous leaves provide a convenient system for comparing the response of cells in culture with their state of differentiation. Callusing frequency is compared with leaf segment position, leaf age and in vivo mitotic activity in Lolium multiflorum. (1) In a succession of one millimeter sections from the immature leaf base, callus was formed from the first and second sections but not the third or subsequent sections. The frequency of those explants callusing decreased with distance from the base of the leaf and with leaf age (or leaf extension growth). (2) In vivo, the proportion of cells in mitosis declined from around 10–14% at the base of young leaves to zero at 5 mm from the base and beyond. Mitotic activity also declined in leaves as they aged, and dividing cells were not observed in leaves 30 days from initiation or older. (3) A high frequency of callus formation was associated with a high mitotic index in the explant. But for corresponding mitotic indices, cells further away from the leaf base were less responsive in culture. (4) It is proposed that cells are becoming differentiated even in highly meristematically active regions of the leaf and concomitantly losing their ability to respond in culture.     

HLA Haplotypes with C4B5; evidence for further allelic heterogeneity

Twenty-three individuals from various disease groups and normal controls were identified by immunofixation with anti-C4, C4-dependent lysis, determination of Rg (Rodgers) and Ch (Chido) phenotypes, and immunoblotting with C4-specific mouse monoclonal antibody. We found that one haplotype predominates with the C4B ^* 5 allele, HLA-A11, B22(55), Cw3, Bf ^* S, C4A ^* 4B ^* 5, which also carries the Ch ^{1,–2, 3} haplotype. The B5 allotype was also found with HLA-1360, HLA-1335 in Caucasoids, and HLA-B18 in non-Caucasoids; these carried the Ch ^{–1, –2, –3} haplotype. Our results are in accord with an earlier report of two B5 subtypes, B5Rg⁺ and B5Rg^– (Roos et al. 1984). The specificity of the mouse monoclonal antibodies IC4 and 21312 had been previously related to C4A and C4B, respectively, but our results suggest that they relate more closely to Rg and Ch determinants.     

The stimulation of anthraquinone production by Cinchona ledgeriana cultures with polymeric adsorbents

Summary Anthraquinones produced by suspension cultures of Cinchona ledgeriana are released into the medium, which becomes saturated with products late in the growth cycle. When a high affinity polymeric adsorbent, such as the macro-reticular Amberlite XAD-7, is added to the culture the concentration of anthraquinone in the medium is maintained at a low level and production may be stimulated 15-fold, yielding up to 20 mg/1/day. More than 90% of the product is released from the cells. For maximal yields it is shown that both the amount of adsorbent used and the time after sub-culture at which it is added to the system are critical. The value of such a method for product recovery from immobilised cells is discussed.