This study focuses on reconstructing the time‐calibrated phylogeny of the nine families comprising the order Sapindales, representing a diverse and economically important group of eudicots including citrus, mahogany, tree‐of‐heaven, cashew, mango, pistachio, frankincense, myrrh, lychee, rambutan, maple, and buckeye. We sampled three molecular markers, plastid genes rbcL and atpB, and the trnL‐trnLF spacer region, and covered one‐third of the generic diversity of Sapindales. All three markers produced congruent phylogenies using maximum likelihood and Bayesian methods for a set of taxa that included outgroups, i.e., members of the closely related orders Brassicales and Malvales, and the more distantly related Crossosomatales, Ranunculales, and Ceratophyllales. All results confirmed the current delimitation of the families within Sapindales, and the monophyly of the order. Concerning inter‐familial relationships, Biebersteiniaceae and Nitrariaceae formed a basal grade (or sister clade) to the rest of Sapindales with moderate support. The sister relationship of Kirkiaceae to Anacardiaceae and Burseraceae was strongly supported. The clade combining Anacardiaceae and Burseraceae as well as the clade combining Meliaceae, Simaroubaceae, and Rutaceae each received strong support. The sister relationship between Meliaceae and Simaroubaceae was moderately supported. The position of Sapindaceae could not be resolved with confidence. The Sapindales separated from their sister clade, comprising Brassicales and Malvales, in the Early Cretaceous at ca. 112 Ma, and diversified into the nine families from ca. 105 Ma until ca. 87 Ma during Early to Late Cretaceous times. Biebersteiniaceae and Nitrariaceae have the longest stem lineages observed in Sapindales, possibly indicating that extinction may have had a greater role in shaping their extant diversity than elsewhere within the order. Divergence within the larger families (Anacardiaceae, Burseraceae, Meliaceae, Rutaceae, Sapindaceae, Simaroubaceae) started during the Late Cretaceous, extending into the Paleogene and Neogene.

Detailed biogeographic studies of pantropical clades are still relatively few, and those conducted to date typically use parsimony or event-based methods to reconstruct ancestral areas. In this study, a recently developed likelihood method for reconstructing ancestral areas (the dispersal-extinction cladogenesis [DEC] model) is applied to the angiosperm family Simaroubaceae, a geographically widespread and ecologically diverse clade of pantropical and temperate trees and shrubs. To estimate divergence dates in the family, Bayesian uncorrelated rates analyses and robust fossil calibrations are applied to the well-sampled and strongly supported phylogeny. For biogeographic analyses, the effects of parameter configurations in the DEC model are assessed for different possible ancestral ranges, and the likelihood method is compared with dispersal-vicariance analysis (DIVA). Regardless of the parameters used, likelihood analyses show a common pattern of multiple recent range shifts that overshadow reconstruction of events deeper in the family's history. DIVA produced results similar to the DEC model when ancestral ranges were restricted to two areas, but some improbable ancestral ranges were also observed. Simaroubaceae exhibit an early history of range expansion between major continental areas in the Northern Hemisphere, but reconstruction of ancestral areas for lineages diverging in the early Tertiary are sensitive to the parameters of the model used. A North American origin is suggested for the family, with migration via Beringia by ancestral taxa. In contrast to traditional views, long-distance dispersal events are common, particularly in the Late Oligocene and later. Notable dispersals are inferred to have occurred across the Atlantic Ocean in both directions, as well as between Africa and Asia, and around the Indian Ocean basin and Pacific islands.

Antibodies against apical membrane antigen 1 (AMA1) inhibit invasion of Plasmodium merozoites into red cells, and a large number of single nucleotide polymorphisms on AMA1 allow the parasite to escape inhibitory antibodies. The availability of a crystal structure makes it possible to test protein engineering strategies to develop a monovalent broadly reactive vaccine. Previously, we showed that a linear stretch of polymorphic residues (amino acids 187 to 207), localized within the C1 cluster on domain 1, conferred the highest level of escape from inhibitory antibodies, and these were termed antigenic escape residues (AER). Here we test the hypothesis that immunodampening the C1 AER will divert the immune system toward more conserved regions. We substituted seven C1 AER of the FVO strain Plasmodium falciparum AMA1 with alanine residues (ALA). The resulting ALA protein was less immunogenic than the native protein in rabbits. Anti-ALA antibodies contained a higher proportion of cross-reactive domain 2 and domain 3 antibodies and had higher avidity than anti-FVO. No overall enhancement of cross-reactive inhibitory activity was observed when anti-FVO and anti-ALA sera were compared for their ability to inhibit invasion. Alanine mutations at the C1 AER had shifted the immune response toward cross-strain-reactive epitopes that were noninhibitory, refuting the hypothesis but confirming the importance of the C1 cluster as an inhibitory epitope. We further demonstrate that naturally occurring polymorphisms that fall within the C1 cluster can predict escape from cross-strain invasion inhibition, reinforcing the importance of the C1 cluster genotype for antigenic categorization and allelic shift analyses in future phase 2b trials.The merozoite stage of Plasmodium falciparum is a highly specialized form of the parasite that selectively invades human red blood cells. Although the exact mechanism of invasion is still under investigation, the expression of apical membrane antigen 1 (AMA1) appears to be an absolute requirement for successful invasion (31). Monoclonal and polyclonal antibodies against AMA1 inhibit invasion in vitro, and immunization with recombinant AMA1 protects against live parasite challenge in animal models of malaria (10a, 18, 28).P. falciparum AMA1 vaccines based on two laboratory strains, 3D7 and FVO, are being studied for efficacy in human trials (23,27,30). One of the major concerns in further development of the AMA1 vaccine is that ϳ10% of its 622 amino acids are polymorphic (2). Strain specificity of vaccine-induced AMA1 antibodies has been observed by enzyme-linked immunosorbent assay (ELISA) and in a functional assay of parasite growth and invasion inhibition (growth inhibition assay [GIA]) (15, 24). Allelic replacement experiments show that sequence polymorphism within AMA1 causes antigenic escape (14), and the extent of escape correlates with sequence distance between the vaccine and target strain (18).The crystal structure of AMA1 shows that it contains two PAN domains, with loops extending outwar...

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The University of Chicago Press is collaborating with JSTOR to digitize, preserve and extend access to International Journal of Plant Sciences.Members of Simaroubaceae comprise a clade of 22 genera and ca. 100 species in the Sapindales. Previous phylogenetic analyses of the family were limited to a single gene and seven genera, and relationships among the genera remain poorly understood. Molecular data from three plastid genes (rbcL, atpB, and matK) and a nuclear gene (phyC), totaling ca. 6000 bp, are used to reconstruct the phylogeny of Simaroubaceae and clarify generic limits, employing maximum parsimony (MP) and Bayesian approaches. Individual analyses of genes are largely congruent, and both MP and Bayesian analyses of combined data produce well-supported phylogenies. Nothospondias, an African genus of uncertain affiliation, is found to be a member of the family. A clade composed of Picrasma, Holacantha, and Castela is sister to the rest of the family, and enigmatic Leitneria is sister to a clade of Brucea, Soulamea, and Amaroria. A broad circumscription of Quassia is unwarranted given several well-supported clades corresponding to traditional generic limits. Comparisons among Bayesian analyses, partitioned variously by gene and codon position, reveal that the most complex method of partitioning best explains the data under a Bayes factor criterion. However, tree topology did not change among partitioning strategies, suggesting that the phylogenetic signal is robust and resistant to model misspecification.

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