Tributes to Truman G. Yuncker and Ethel Claflin Yuncker

Editor’s note: This tribute was prepared by Barbara Yuncker from a recorded interview she had with Dr. Callejas during his six-week visit to the Garden’s Herbarium in September 1988 to study the Piperaceae specimens received from DePauw University.     

‘Agonistic buffering’ in the wild barbary macaque,Macaca sylvana L.

Barbary apes are known to exhibit male care of babies at various locations, but only in the Middle Atlas mountains of Morocco has it been reported that a baby may be used in male-male interactions, apparently reducing the likelihood of aggression. The present study was made in order to discover if the behavior was characteristic of other groups reproductively isolated from the Atlas population. Male-male interactions involving a baby were observed in two groups and are described in detail; their friendly nature supports the hypothesis that the presence of a baby reduces the likelihood of aggression. We did not, however, see the active use of babies in this context which has been described for the Atlas population.     

Leptographium terebrantis sp. nov. associated with dendroctonus terebrans in loblolly pine

ALeptographium fungus associated with the black turpentine beetleDendroctonus terebrans (Olivier) is described for the first time. The nameLeptographium terebrantis sp. nov. is proposed.

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Zusammenfassung Der Pilz,Leptographium, der mit dem schwarzen Terpentinkäfer,Dendroctonus terebrans (Olivier) vergesellschaftet ist, wird das erste Mal beschrieben. Für den Pilz wird die BenennungLeptographium terebrantis vorgeschlagen.

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The authors are research entomologist and biological aide (microbiology) with the Forest Insect Research Project, at the Southern Forest Experiment Station, USDA Forest Service, Pineville, Louisiana.     

Cell-Surface Lectins of Azospirillum spp.

Cell-surface lectins were screened in seven strains of Azospirillum brasilense and A. lipoferum. The presence of lectins was determined by particle agglutination assays employing latex beads coated with neoglycoproteins and by Western blot with neoglycoproteins labeled with horseradish peroxidase as a probe. Seven strains were agglutinated with the assayed sugar residues. The highest agglutination was with fucose and glucose and to a lesser extent with mannose residues. Cell-wall proteins extracted from two Azospirillum spp. strains exhibit lectin-like activities. We believe that lectins are present in the cell-wall of Azospirillum spp. Received: 23 June 1997 / Accepted: 23 September 1997     

Use of the VNTR typing technique to determine the origin of Mycobacterium tuberculosis strains isolated from Filipino patients in Korea

With increasing international interchange of personnel, international monitoring is necessary to decrease tuberculosis incidence in the world. This study aims to develop a new tool to determine origin of Mycobacterium tuberculosis strains isolated from Filipino patients living in Korea. Thirty-two variable number tandem repeat (VNTR) loci were used for discrimination of 50 Filipino M. tuberculosis strains isolated in the Philippines, 317 Korean strains isolated in Korea, and 8 Filipino strains isolated in Korea. We found that the VNTR loci 0580, 0960, 2531, 2687, 2996, 0802, 2461, 2163a, 4052, 0424, 1955, 2074, 2347, 2401, 3171, 3690, 2372, 3232, and 4156 had different mode among copy numbers or exclusively distinct copy number in VNTR typing between Filipino and Korean M. tuberculosis strains. When these differences of the VNTR loci were applied to 8 Filipino M. tuberculosis strains isolated in Korea, 6 of them revealed Filipino type while 2 of them had Korean type. Using the differences of mode or repeated number of VNTR loci were very useful in distinguishing the Filipino strain from Korean strain.     

Blood group O alleles in Native Americans: Implications in the peopling of the Americas

All major ABO blood alleles are found in most populations worldwide, whereas the majority of Native Americans are nearly exclusively in the O group. O allele molecular characterization could aid in elucidating the possible causes of group O predominance in Native American populations. In this work, we studied exon 6 and 7 sequence diversity in 180 O blood group individuals from four different Mesoamerican populations. Additionally, a comparative analysis of genetic diversity and population structure including South American populations was performed. Results revealed no significant differences among Mesoamerican and South American groups, but showed significant differences within population groups attributable to previously detected differences in genetic drift and founder effects throughout the American continent. Interestingly, in all American populations, the same set of haplotypes O¹, O^1v, and O^1v(G542A) was present, suggesting the following: (1) that they constitute the main genetic pool of the founding population of the Americas and (2) that they derive from the same ancestral source, partially supporting the single founding population hypothesis. In addition, the consistent and restricted presence of the G542A mutation in Native Americans compared to worldwide populations allows it to be employed as an Ancestry informative marker (AIM). Present knowledge of the peopling of the Americas allows the prediction of the way in which the G542A mutation could have emerged in Beringia, probably during the differentiation process of Asian lineages that gave rise to the founding population of the continent. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Genomic Admixture Analysis in European Populus spp. Reveals Unexpected Patterns of Reproductive Isolation and Mating

Admixture between genetically divergent populations facilitates genomic studies of the mechanisms involved in adaptation, reproductive isolation, and speciation, including mapping of the loci involved in these phenomena. Little is known about how pre- and postzygotic barriers will affect the prospects of “admixture mapping” in wild species. We have studied 93 mapped genetic markers (microsatellites, indels, and sequence polymorphisms, ∼60,000 data points) to address this topic in hybrid zones of Populus alba and P. tremula, two widespread, ecologically important forest trees. Using genotype and linkage information and recently developed analytical tools we show that (1) reproductive isolation between these species is much stronger than previously assumed but this cannot prevent the introgression of neutral or advantageous alleles, (2) unexpected genotypic gaps exist between recombinant hybrids and their parental taxa, (3) these conspicuous genotypic patterns are due to assortative mating and strong postzygotic barriers, rather than recent population history. We discuss possible evolutionary trajectories of hybrid lineages between these species and outline strategies for admixture mapping in hybrid zones between highly divergent populations. Datasets such as this one are still rare in studies of natural hybrid zones but should soon become more common as high throughput genotyping and resequencing become feasible in nonmodel species.ADMIXTURE or hybrid zones between genetically divergent populations are increasingly being explored for their use in studies of adaptation, reproductive isolation, and speciation (Rieseberg et al. 1999; Martinsen et al. 2001; Wu 2001; Vines et al. 2003; Payseur et al. 2004; reviewed by Coyne and Orr 2004), especially for their potential in identifying recombinants for gene mapping (otherwise known as “admixture mapping”; Chakraborty and Weiss 1988; Briscoe et al. 1994; Rieseberg et al. 1999; Reich et al. 2005; Slate 2005; Zhu et al. 2005; Lexer et al. 2007; Nolte et al. 2009). In many taxa of animals and plants, recombinants are created by admixture between divergent populations or species in hybrid zones or ecotones (Buerkle and Lexer 2008; Gompert and Buerkle 2009). The growing interest of evolutionary geneticists in admixture has its roots in both basic evolutionary genetics and breeding.With respect to evolutionary genetics, admixed populations have been viewed as important resources for studying the genetics of adaptation and speciation, since the discovery that by fitting geographical clines of allele frequencies across hybrid zones, the strength of intrinsic and extrinsic (ecological) barriers to gene flow can be estimated (Barton and Hewitt 1985; Barton and Gale 1993). More recently, the genomics era has taken these concepts to a new level by providing genetic or physical genome maps for many species so that clines or introgression patterns of individual loci can be compared to their genomic background (see below; Falush et al. 2003; Gompert and Buerkle 2009). Thus, hybrid zones permit the identification and study of quantitative trait loci (QTL), genes, or other genetic elements involved in reproductive isolation and speciation in situ, directly in natural populations, if sufficient genetic recombination has occurred (Rieseberg and Buerkle 2002). In applied genetics, studies of hybrid zones yield information on the genomic architecture of barriers to introgression, which is of great interest to breeders concerned with the establishment of pedigrees for tree selection and domestication (Stettler et al. 1996).Most animal or plant hybrid zones studied to date involve hybridization between parental populations that are much more divergent than the admixed human populations that have been used successfully for gene mapping in human medical genetics (e.g., Reich et al. 2005; Zhu et al. 2005). Little experience exists with interpreting genomic patterns of ancestry and admixture in such highly divergent, nonhuman populations. Early genomic work on hybrid zones, based on dominant genetic markers, suggested the feasibility of mapping genome regions involved in reproductive isolation and speciation (Rieseberg et al. 1999; Rogers et al. 2001), but these studies did not allow tests for selection on genotypes at single loci in different genomic backgrounds. This became possible only recently due to the development of novel analytical tools suited to large numbers of codominant markers, especially linkage models of Bayesian admixture analysis (Falush et al. 2003, 2007) and methods to fit “genomic clines” of codominant marker genotypes across complete genomic admixture gradients (Lexer et al. 2007; Gompert and Buerkle 2009; Nolte et al. 2009; Teeter et al. 2010). Great advances also have been made in interpreting single-locus estimates of genetic divergence between populations and species (Beaumont 2005; Foll and Gaggiotti 2008; Excoffier et al. 2009a). Here, we bring these approaches together to yield novel insights into genomic patterns of reproductive isolation and mating in hybrid zones of two widespread and important members of the “model tree” genus Populus. Our goal was to infer patterns of reproductive isolation and the likely evolutionary trajectories of hybrid populations and to develop strategies for genetic mapping in admixed populations.Populus alba (white poplar) and P. tremula (European aspen) are ecologically divergent (floodplain vs. upland habitat) hybridizing tree species related to P. trichocarpa, the first completely sequenced forest tree (Tuskan et al. 2006). The two species are highly differentiated for neutral DNA-based markers (Lexer et al. 2007) and numerous phenotypic and ecological traits (Lexer et al. 2009). Mosaic hybrid zones between these species often form in riparian habitats (Lexer et al. 2005; hybrids sometimes referred to as P. × canescens) and have been proposed as potential “mapping populations” for identifying QTL and genes of interest in evolutionary biology (Lexer et al. 2007; Buerkle and Lexer 2008) and breeding (Fossati et al. 2004; Lexer et al. 2004). Previous studies of these hybrid zones were conducted with a relatively small number of genetic markers and without making use of linkage information; the genomic composition of hybrid zones between these species has never been studied with a genomewide panel of codominant markers with known linkage relationships. Specifically, we address the following questions in this contribution:(1) What does an analysis of admixture and differentiation based on a genome-wide panel of mapped markers tell us about patterns of reproductive isolation and mating in hybrid zones of European Populus species? (2) What are the likely roles of pre- and postzygotic barriers vs. recent, localized historical factors in generating the observed genomic patterns? (3) What are the practical implications for admixture mapping in hybrid zones between highly divergent populations? We showcase where the genetic peculiarities of hybrid zones will limit their use for gene mapping and where they suggest new approaches that were perhaps not foreseen by geneticists with a focus on human medical applications.     

Lytic activity and structural differences of amphipathic peptides derived from trialysin

Trialysin is a pore-forming protein found in the saliva of Triatoma infestans (Hemiptera, Reduviidae), the insect vector of Chagas' disease. The protein is active against a broad range of cell types from bacteria to eukaryotic cells. Recognizing that the N-terminus of trialysin harbors the lytic motif [Amino, R., Martins, R. M., Procopio, J., Hirata, I. Y., Juliano, M. A., and Schenkman, S. (2002) J. Biol. Chem. 277, 6207-6213], we designed a set of peptides scanning this region to investigate the structural basis of its biological function. Peptides encompassing residues 1-32 (P6), 1-27 (P7), and 6-32 (P5) efficiently induced lysis of the protozoan parasite Trypanosoma cruzi and Escherichia coli in the 0.4-9.0 microM range, while much higher concentrations were required to cause hemolysis. Other more internal peptides, including peptide P2 (residues 21-47) and others up to residue 52, were less effective. P6 turned out to be the most active of all. P7 has a significantly higher activity than P5 against E. coli, while P5 has a hemolytic activity comparable to that of P6. CD spectroscopy showed that all tested peptides acquire a comparable helical content in solvent mixtures or in detergent micelles. The solution structure of P2 and P5-P7 was determined in a 30% trifluoroethanol/water mixture by nuclear magnetic resonance. All peptides exhibit a structure characterized by a central helical fold, and except for P2, which does not show a continuous hydrophobic surface, they are amphipathic. The structural models show that P5 and P7 extend their structural similarities with the most active peptide, P6, in either the C-terminus or the N-terminus. Amino acid substitutions in the N-terminus of P6 improved hemolysis but did not change the activity against T. cruzi. These results suggest that while amphipathicity is essential for the lytic activity, the selectivity of the active peptides for specific organisms appears to be associated with the structural features of their N- and C-termini.     

Intranasal immunization with a recombinant truncated FimH adhesin adjuvanted with CpG oligodeoxynucleotides protects mice against uropathogenic Escherichia coli challenge

In this work, we assessed the efficacy of an experimental intranasal vaccine against urinary-tract infections. The vaccine contained a recombinant truncated FimH (rFimHt) adhesin plus CpG oligodeoxynucleotides. The efficacy of the vaccine was compared with that of an intramuscular vaccine that was formulated with the same immunogen plus Freund's adjuvant. Our results show that serum immunoglobulin G titers of vaccinated animals were similarly enhanced in both cases. However, the intranasal vaccine elicited higher vaginal-wash-specific immunoglobulin A titers against rFimHt than the intramuscular route. Both vaccines reduced the in vivo colonization of the bladder by uropathogenic Escherichia coli more than 100-fold in a murine cystitis model. Our results indicate that a recombinant truncated FimH adhesin plus CpG oligodeoxynucleotides is a suitable immunogenic combination that can contribute to the development of a highly efficacious urinary tract infection vaccine.