Publications

In 1926, Cushman described Rotalia beccarii var. tepida from San Juan Harbor, Puerto Rico. His publication illustrates a strew slide with many individuals, and no holotype was designated. Consequently, over the years, researchers have assumed that no holotype exists. A search of the Cushman Collection, however, discovered a slide labeled as holotype and it is so recorded in the Cushman Catalog of 1929. Here, this specimen is re-described and designated as a lectotype. All nine of the other surviving syntypes from the original collection in San Juan Harbor, Puerto Rico, now become paralectotypes. Hopefully, the designation of formal types for Ammonia tepida (Cushman) will help stabilize the taxonomy of this important species. Our study shows that the lectotype is morphologically distinguishable from other Ammonia types and that the distribution of Ammonia tepida is restricted to tropical shallow-water environments.

Nummulitidae are the largest extant calcareous Foraminifera, and are widely distributed in tropical and subtropical shallow-water seas. Classical morphology-based taxonomy divides the Nummulitidae in two subfamilies, the Nummulitinae and Heterostegininae, according to the presence or absence of secondary septa. To test the evolutionary importance of this morphological feature, phylogenetic relationships of five Recent nummulitid genera were investigated by sequencing fragments of the SSU and LSU rRNA gene. According to our results, species characterized by septate chambers (Heterostegina depressa, Planostegina operculinoides, and Cycloclypeus carpenteri) either group with species lacking septate chambers (Operculina ammonoides, Nummulites venosus) or branch separately. This suggests that chamber subdivisions developed several times independently in the evolutionary history of the Nummulitidae, providing an example of parallel evolution in Foraminifera.

Fossil Foraminifera appear in the Early Cambrian, at about the same time as the first skeletonized metazoans. However, due to the inadequate preservation of early unilocular (single-chambered) foraminiferal tests and difficulties in their identification, the evolution of early foraminifers is poorly understood. By using molecular data from a wide range of extant naked and testate unilocular species, we demonstrate that a large radiation of nonfossilized unilocular Foraminifera preceded the diversification of multilocular lineages during the Carboniferous. Within this radiation, similar test morphologies and wall types developed several times independently. Our findings indicate that the early Foraminifera were an important component of Neoproterozoic protistan community, whose ecological complexity was probably much higher than has been generally accepted.

The nuclear-transport protein importin-beta mediates the nuclear import of the transcription factor SREBP-2 without requiring adaptor proteins such as importin-alpha. An importin-beta-SREBP-2 HLHZ domain complex was purified and crystallized. The crystals belong to space group P2(1)2(1)2(1) and show diffraction to at least 3.0 A resolution. The unit-cell parameters are a = 101.0, b = 113.2, c = 240.0 A. Structure determination using the MAD or SAD method is under way.

Lobose amoebae are abundant free-living protists and important pathogenic agents, yet their evolutionary history and position in the universal tree of life are poorly known. Molecular data for lobose amoebae are limited to a few species, and all phylogenetic studies published so far lacked representatives of many of their taxonomic groups. Here we analyze actin and small-subunit ribosomal RNA (SSU rRNA) gene sequences of a broad taxon sampling of naked, lobose amoebae. Our results support the existence of a monophyletic Amoebozoa clade, which comprises all lobose amoebae examined so far, the amitochondriate pelobionts and entamoebids, and the slime molds. Both actin and SSU rRNA phylogenies distinguish two well-defined clades of amoebae, the "Gymnamoebia sensu stricto" and the Archamoebae (pelobionts + entamoebids), and one weakly supported and ill-resolved group comprising some naked, lobose amoebae and the Mycetozoa.

Progressive algorithms are widely used heuristics for the production of alignments among multiple nucleic-acid or protein sequences. Probabilistic approaches providing measures of global and/or local reliability of individual solutions would constitute valuable developments.

We describe a new species of cestode belonging to Postgangesia Akhmerov, 1969 (Proteocephalidea: Gangesiinae) from the catfish Silurus glanis Linnaeus in Iraq. This is the second species known from this genus, and a redescription of the type-species, P. orientalis Akhmerov, 1969 (emend.), as well as a differential diagnosis are provided. The new species is characterised by the arrangement of its vitelline follicles, and various meristic and metrical characters. The systematic position of Postgangesia is discussed on the basis of both scolex and strobilar characters and arguments are presented for its placement within the Gangesiinae together with Electrotaenia Nybelin,1942, Gangesia Woodland,1924, Silurotaenia Nybelin, 1942 and Vermaia Nybelin, 1942. Finally, we illustrate and discuss some particular structures found in these taxa, especially in relation to the apical organs of the scolex.

During vertebrate development, clustered genes from the Hox family of transcription factors are activated in a precise temporal and spatial sequence that follows their chromosomal order (the "Hox clock"). Recent advances in the knowledge of the underlying mechanisms reveal that the embryo uses a variety of strategies to implement this colinear process, depending on both the type and the evolutionary history of axial structures. The search for a universal mechanism has likely hampered our understanding of this enigmatic phenomenon, which may be caused by various and unrelated regulatory processes, as long as the final distribution of proteins (the HOX code) is preserved.