Phloem-restricted trypanosomatids form a clearly characterised monophyletic group among trypanosomatids isolated from plants

Although only one genus name has been proposed as yet for all plant trypanosomes, 'Phytomonas', it is clear that they can differ from one another in terms of both their biological properties and their effects. Recent serological and molecular studies have confirmed the substantial heterogeneity of these trypanosomatids, which the use of a single genus name does not even hint at. We set out to show in this paper that there is at least one homogeneous group of plant trypanosomes that can be defined explicitly by a single genus and species name and that differs substantially from all the other clusters that may be identified by one technique or another: the phloem-restricted trypanosomatids found in Latin America.     

Swimming marine Synechococcus strains with widely different photosynthetic pigment ratios form a monophyletic group

Unicellular marine cyanobacteria are ubiquitous in both coastal and oligotrophic regimes. The contribution of these organisms to primary production and nutrient cycling is substantial on a global scale. Natural populations of marine Synechococcus strains include multiple genetic lineages, but the link, if any, between unique phenotypic traits and specific genetic groups is still not understood. We studied the genetic diversity (as determined by the DNA-dependent RNA polymerase rpoC1 gene sequence) of a set of marine Synechococcus isolates that are able to swim. Our results show that these isolates form a monophyletic group. This finding represents the first example of correspondence between a physiological trait and a phylogenetic group in marine Synechococcus. In contrast, the phycourobilin (PUB)/phycoerythrobilin (PEB) pigment ratios of members of the motile clade varied considerably. An isolate obtained from the California Current (strain CC9703) displayed a pigment signature identical to that of nonmotile strain WH7803, which is considered a model for low-PUB/PEB-ratio strains, whereas several motile strains had higher PUB/PEB ratios than strain WH8103, which is considered a model for high-PUB/PEB-ratio strains. These findings indicate that the PUB/PEB pigment ratio is not a useful characteristic for defining phylogenetic groups of marine Synechococcus strains.     

Validating Livanow: molecular data agree that leeches, Branchiobdellidans, and Acanthobdella peledina form a monophyletic group of oligochaetes.

To investigate the phylogenetic relationships of leeches, branchiobdellidans, and acanthobdellidans, whole nuclear 18S rDNA and over 650 bp of mitochondrial cytochrome c oxidase subunit I were acquired from 101 annelids, including 36 leeches, 18 branchiobdellidans, Acanthobdella peledina, as well as 28 oligochaetes and combined with homologous data for 17 polychaete outgroup taxa. Parsimony analysis of the combined aligned dataset supported monophyly of leeches, branchiobdellidans, and acanthobdellidans in 100% of jackknife replicates. Monophyly of the oligochaete order Lumbriculida with Acanthobdellida, Branchiobdellida, and Hirudinea was supported in 84% of jackknife replicates. These results provide support for the hypotheses that leeches and branchiobdellidans are sister groups, that acanthobdellidans are sister to them, and that together with the family Lumbriculidae they all constitute a clade within Oligochaeta. Results support synonymy of the classes Clitellata and the more commonly used Oligochaeta. Leeches branchiobdellidans, and acanthobdellidans should be regarded as orders equal to their closest relatives, the order Lumbriculida.     

Defining a monophyletic Cardinalini: a molecular perspective

Within the New World nine-primaried oscine assemblage, feeding morphology and behavior have long been used as a guideline for assigning membership to subgroups. For example, birds with stout, conical bills capable of crushing heavy seeds have generally been placed within the tribe Cardinalini (cardinal-grosbeaks). Many workers have tried to characterize this group more definitively, using a variety of morphological characters; however, the characters used often conflicted with one another. Previous molecular studies addressing the monophyly of Cardinalini have had only limited sampling within the group. In this study, we analyze mtDNA sequence data from all genera and 34 of the 42 Cardinalini species (sensu [Sibley, C.G., Monroe, B.L., 1990. Distribution and Taxonomy of the Birds of the World, Yale University Press, New Haven, CT]) to address the monophyly of the group and to reconstruct the most complete phylogeny of this tribe published to date. We found strong support for a redefined Cardinalini that now includes some members previously placed within Thraupini (tanagers; the genera Piranga, Habia, Chlorothraupis, and Amaurospiza) and some members previously placed within the Parulini (wood-warblers; the genus Granatellus). In addition, some genera traditionally considered members of the Cardinalini are shown to have affinities with other groups (the genera Porphyrospiza, Parkerthraustes, and Saltator). Our redefined Cardinalini contains 48 species, six more than are listed in Sibley and Monroe's (1990) taxonomy of the group. Within the nine-primaried oscine assemblage, the Cardinalini are more closely related to the Thraupini (tanagers) than they are to the Emberizini (sparrows), Parulini (wood-warblers), or Icterini (blackbirds), consistently forming a monophyletic group with Thraupini across all analyses. The reconfigured Cardinalini is comprised of five well-supported, major clades: (1) a "masked" clade (Piranga, Cardinalis, Caryothraustes, Periporphyrus, and Rhodothraupis), (2) a "blue" clade (Amaurospiza, Cyanocompsa, Cyanoloxia, Passerina, and Spiza), (3) a clade containing the genera Habia and Chlorothraupis, (4) a clade containing all species of Granatellus, and (5) a clade containing only species of Pheucticus. Diversification of these five lineages from one another occurred relatively rapidly during the mid-Pliocene, around 5 or 8 million years ago. Each of these major clades includes both North and South American species; thus, a complex biogeographic history is inferred for the group.     

Phylogeny and habitat adaptations within a monophyletic group of wetland moss genera (Amblystegiaceae)

Genus level phylogenetic patterns within a monophyletic group of wetland mosses consisting ofTomentypnum, Hamatocaulis, Scorpidium, Conardia, Calliergon, Warnstorfia, Straminergon, andLoeskypnum (Amblystegiaceae) are cladistically analysed, usingPalustriella and partlyCratoneuron as outgroups. The ingroup consists of two clades, one withTomentypnum, Hamatocaulis andScorpidium, the other with the other ingroup genera. The second clade gets completely resolved only with the inclusion of habitat data. The adaptation to relatively dry wetland habitats probably evolved in the ancestor ofStraminergon andLoeskypnum, the species ofCalliergon andWarnstorfia, which are more ancestral, growing in wetter habitats. The more primitive taxa of the ingroup, as well asPalustriella species, occur in relatively mineral-rich habitats and adaptations to poorer habitats occurred several times in the two clades.     

The "valve" of the ductus arteriosus--an enigma.

The urine/plasma creatinine ratio (U/P Cr), the urine sodium concentration (UNa), and the diuretic response to mannitol infusion in 23 patients were reviewed in an attempt to differentiate functional renal failure (FRF) from acute tubular necrosis (ATN). FRF was diagnosed if the plasma urea nitrogen (PUN) or serum creatinine stabilized within 72 hours. When renal failure persisted longer, patients had ATN. Subjects dying within 72 hours were excluded. Ten patients had ATN and five survived. The minimum duration of renal failure among survivors was 10 days. None responded to mannitol. Of 13 patients with FRF, 11 survived. Seven of 12 who received mannitol responded with a diuresis. The mean UNa in the patients with ATN was 51.4 mEq./1. ± 9.48 (SE). The mean U/P Cr was 11.2 ± 1.12. In patients with FRF, the mean UNa was 14.0 mEq./1. ± 4.2 and the mean U/P Cr was 42.5 ± 11.5. A significant overlap was present between the two groups. When UNa was factored by the U/P Cr, the resultant ratio was significantly different for the two groups of patients (P < 0.01), and this proved to be a useful clinical index with which to distinguish FRF from established ATN.     

The diversity and radiation of the largest monophyletic animal group on New Caledonia (Trichoptera: Ecnomidae: Agmina)

In area, New Caledonia is the smallest of the world’s 25 official biodiversity hotspots, but in many taxonomic groups, the island has the highest concentration of species on earth, particularly so in the freshwater insect order Trichoptera. This study aims at applying molecular data and morphology for estimating the real species diversity of the genus Agmina on New Caledonia and investigating potential effects of ultramafic rock substrate on diversification. A dated molecular phylogeny was applied to study diversity and diversification related to geological substrate using the dispersal–extinction–cladogenesis model, diva and Bayesian ancestral character reconstruction. More than 47 species (> 63%) were unknown to science. Initial radiation occurred on ultramafic substrate followed by several independent dispersal events to nonultramafic substrate. The rate of shift from ultramafic to nonultramafic substrate was significantly higher than the rate of shift in the opposite direction, indicating a possible cost associated with living on ultramafic substrate.     

Consciousness enigma: the "hard problem"--binding problem entanglement, "extra ingredient" and field principle

The "Hard problem" of consciousness relates to the perplexing emergence of consciousness as a result of the brain activity. The binding problem concerns separate processing of perceived data in functionally and topographically segregated cortical areas and functional integration of such locally disjoined operations into coherently perceived images and events. The existing field-grounded theories of consciousness fall into two groups: (i) those based on the physical (electromagnetic) field, and (ii) those grounded on autonomous fields irreducible to the established physical fundamentals. The critical analysis of the existing theories results in formulation of the extra ingredient and a novel irreducible field-based theory of consciousness.     

Evolution: the evolvability enigma

A report that a switch of a yeast protein to a 'prion' state triggers diverse phenotypic changes has prompted re-examination of the processes of evolution. To what extent should processes of gene expression and control be interpreted in terms of their capacity to allow future evolution as well as present adaptation?     

Platelet factor 4: a chemokine enigma

Platelet factor 4 (PF4) is a platelet alpha-granule protein sequenced over 25 years ago that is a founding member of the C-X-C chemokine family, yet its physiologic function has yet to be definitively established. Initial investigations focused on possible procoagulant roles for PF4 in platelet function and plasmatic coagulation. Subsequent in vitro studies have, however, described a puzzling array of other apparently unrelated biologic functions, including inhibition of angiogenesis and hematopoiesis, promotion of neutrophil adhesion, and activation, enhancement of oxy-LDL binding to the LDL receptor and stimulation of anti-coagulant activated protein C generation by the thrombomodulin/protein C system. Preliminary studies with a just-described PF4 knockout mouse line support a role for PF4 in platelet-dependent thrombosis in vivo.     

Cuticles of Nematothallus: a further enigma

EDWARDS, D. & ROSE, V. 1984. Cuticles of Nematothallus: a further enigma. Cuticles of Nematothallus Lang scnsu Edwards are described from a Lower Devonian (Ditton) exposure on the M50 motorway (Hereford and Worcester, England). Some bear highly distinctive cuticular thickenings sometimes surrounding perforations. The affinities of the cuticles, and the development and possible functions of the perforations are considered.     

The enigma of the haemogram "left-shift" in periwinkles infected with trematodes

To make further progress in the understanding of digenean immune evasive tactics in their snail host, we compared the haemopoietic parameters and haemocyte functional potencies in the prosobranch Littorina littorea, which were either healthy or infected with echinostome trematode Himasthla elongata. The haemocyte concentration in the circulation of infected individuals was significantly higher than in uninfected ones, 3300 microl(-1) and 1882 microl(-1), respectively. Intense haemopoiesis in haemolymph of infected snails was evidenced by 4-fold higher BrdU incorporation into nuclei of haemocytes as well as elevated level of cyclin D expression in these cells. Evident skewing of the haemocyte population toward a higher frequency of immature, undifferentiated haemocytes in infected L. littorea was found. Haemocytes in infected snails had a much lower functional potency in production of reactive oxygen intermediates (ROI) and cell-mediated cytotoxicity. Correlation analysis shows that both cytotoxic and ROI generation values were significantly and negatively correlated with proportion of juvenile cells in circulation. Experimental injection of H. elongata excretory/secretory products modulated haemopoiesis toward increasing a juvenile cells proportion by 7th day post-injection. This can be considered a haemogram "left-shift" by analogy to that seen in the human neutrophil compartment, when more immature bandforms are found in blood during acute inflammation or bone marrow disorders. We hypothesize that echinostomatide trematodes may interfere in the normal neuroendocrine management of haemopoiesis in the host and cause a haemopoietic signal to initiate multiplication to near neoplastic levels.     

Toll signaling: the enigma variations

Experiments reported in the past year have revealed considerable diversity in Toll-mediated pathways for signal transduction in development and innate immunity. Rather than function as a well conserved signaling cassette, Toll receptors and associated factors have apparently evolved as a diverse set of configurations to defend against microbial infection in species ranging from plants to humans.     

The ancient Yakuts: a population genetic enigma

This study is part of an ongoing project aiming at determining the ethnogenesis of an eastern Siberian ethnic group, the Yakuts, on the basis of archaeological excavations carried out over a period of 10 years in three regions of Yakutia: Central Yakutia, the Vilyuy River basin and the Verkhoyansk area. In this study, genetic analyses were carried out on skeletal remains from 130 individuals of unknown ancestry dated mainly from the fifteenth to the nineteenth century AD. Kinship studies were conducted using sets of commercially available autosomal and Y-chromosomal short tandem repeats (STRs) along with hypervariable region I sequences of the mitochondrial DNA. An unexpected and intriguing finding of this work was that the uniparental marker systems did not always corroborate results from autosomal DNA analyses; in some cases, false-positive relationships were observed. These discrepancies revealed that 15 autosomal STR loci are not sufficient to discriminate between first degree relatives and more distantly related individuals in our ancient Yakut sample. The Y-STR analyses led to similar conclusions, because the current Y-STR panels provided the limited resolution of the paternal lineages.     

Developmental genetic evidence for a monophyletic origin of the bilaterian brain

The widely held notion of an independent evolutionary origin of invertebrate and vertebrate brains is based on classical phylogenetic, neuroanatomical and embryological data. The interpretation of these data in favour of a polyphyletic origin of animals brains is currently being challenged by three fundamental findings that derive from comparative molecular, genetic and developmental analyses. First, modern molecular systematics indicates that none of the extant animals correspond to evolutionary intermediates between the protostomes and the deuterostomes, thus making it impossible to deduce the morphological organization of the ancestral bilaterian or its brain from living species. Second, recent molecular genetic evidence for the body axis inversion hypothesis now supports the idea that the basic body plan of vertebrates and invertebrates is similar but inverted, suggesting that the ventral nerve chord of protostome invertebrates is homologous to the dorsal nerve cord of deuterostome chordates. Third, a developmental genetic analysis of the molecular control elements involved in early embryonic brain patterning is uncovering the existence of structurally and functionally homologous genes that have comparable and interchangeable functions in key aspects of brain development in invertebrate and vertebrate model systems. All three of these findings are compatible with the hypothesis of a monophyletic origin of the bilaterian brain. Here we review these findings and consider their significance and implications for current thinking on the evolutionary origin of bilaterian brains. We also preview the impact of comparative functional genomic analyses on our understanding of brain evolution.