Morphology and molecular phylogeny of Pseudotrichonympha hertwigi and Pseudotrichonympha paulistana (Trichonymphea, parabasalia) from neotropical rhinotermitids.

Pseudotrichonympha is a large hypermastigote parabasalian found in the hindgut of several species of rhinotermitid termites. The genus was discovered more than 100 years ago, and although over a dozen species have since been described, this represents only a small fraction of its likely diversity: the termite genera from which Pseudotrichonympha is known are all species rich, and in most cases their hindgut symbionts have not been examined. Even formally described species are mostly lacking in detailed microscopic data and/or sequence data.

The search for the missing link: a relic plastid in Perkinsus?

Perkinsus marinus (Phylum Perkinsozoa) is a protozoan parasite that has devastated natural and farmed oyster populations in the USA, significantly affecting the shellfish industry and the estuarine environment. The other two genera in the phylum, Parvilucifera and Rastrimonas, are parasites of microeukaryotes. The Perkinsozoa occupies a key position at the base of the dinoflagellate branch, close to its divergence from the Apicomplexa, a clade that includes parasitic protista, many harbouring a relic plastid.

The GC-rich mitochondrial and plastid genomes of the green alga Coccomyxa give insight into the evolution of organelle DNA nucleotide landscape.

Most of the available mitochondrial and plastid genome sequences are biased towards adenine and thymine (AT) over guanine and cytosine (GC). Examples of GC-rich organelle DNAs are limited to a small but eclectic list of species, including certain green algae. Here, to gain insight in the evolution of organelle nucleotide landscape, we present the GC-rich mitochondrial and plastid DNAs from the trebouxiophyte green alga Coccomyxa sp.

Morphological diversity between culture strains of a chlorarachniophyte, Lotharella globosa.

Chlorarachniophytes are marine unicellular algae that possess secondary plastids of green algal origin. Although chlorarachniophytes are a small group (the phylum of Chlorarachniophyta contains 14 species in 8 genera), they have variable and complex life cycles that include amoeboid, coccoid, and/or flagellate cells. The majority of chlorarachniophytes possess two or more cell types in their life cycles, and which cell types are found is one of the principle morphological criteria used for species descriptions.

Endosymbiosis: bacteria sharing the load.

A nested set of bacterial endosymbionts within mealybug cells collectively provides amino acids to their host, but their genomes show that some pathways are distributed between both endosymbionts, while other essential proteins are missing altogether. The possibility that additional functions are shared between partners warrants comparisons with organelles.

Identification of plant-like galactolipids in Chromera velia, a photosynthetic relative of malaria parasites.

Apicomplexa are protist parasites that include Plasmodium spp., the causative agents of malaria, and Toxoplasma gondii, responsible for toxoplasmosis. Most Apicomplexa possess a relict plastid, the apicoplast, which was acquired by secondary endosymbiosis of a red alga.

Symbiosis, morphology, and phylogeny of Hoplonymphidae (Parabasalia) of the wood-feeding roach Cryptocercus punctulatus.

Anaerobic cellulolytic flagellate protists of the hindguts of lower termites and the wood-feeding cockroach Cryptocercus are essential to their host's ability to digest lignocellulose. Many have bacteria associated with their surfaces and within cytoplasmic vesicles-likely important symbioses as suggested by molecular and other data. Some of the most striking examples of these symbioses are in the parabasalid family Hoplonymphidae, but little or no data exist on the structural aspects of their symbioses, their relationships with bacteria through different life-cycle stages, or their diversity and phylogenetic relationships in Cryptocercus.

How a neutral evolutionary ratchet can build cellular complexity.

Complex cellular machines and processes are commonly believed to be products of selection, and it is typically understood to be the job of evolutionary biologists to show how selective advantage can account for each step in their origin and subsequent growth in complexity. Here, we describe how complex machines might instead evolve in the absence of positive selection through a process of "presuppression," first termed constructive neutral evolution (CNE) more than a decade ago. If an autonomously functioning cellular component acquires mutations that make it dependent for function on another, pre-existing component or process, and if there are multiple ways in which such dependence may arise, then dependence inevitably will arise and reversal to independence is unlikely.

Nucleus- and nucleomorph-targeted histone proteins in a chlorarachniophyte alga.

The plastid of chlorarachniophytes is distinguished by the retention of a relict nucleus (nucleomorph) derived from a green algal endosymbiont, which is located in the periplastidal compartment (PPC). The nucleomorph genome of a chlorarachniophyte, Bigelowiella natans, encodes several plastid-targeted proteins and hundreds of housekeeping proteins, but it lacks many fundamental genes to maintain itself. Here we report the first two host nucleus-encoded genes for proteins targeted to the nucleomorph, histone H2A and H2B.

A retrospective analysis of benzodiazepine sedation vs. propofol anaesthesia in 252 patients undergoing endoscopic retrograde cholangiopancreatography.

Background: Historically, hepatopancreatobiliary surgeons and gastroenterologists have undertaken endoscopic retrograde cholangiopancreatography (ERCP) using benzodiazepine sedation (BS). This is poorly tolerated by a substantial number of patients, which leads to its potential premature abandonment and subsequent additional investigations and therapeutics, and hence to the exposure of patients to avoidable risk and the health service to increased costs. Furthermore, concerns have been raised in the recent literature regarding safe sedation techniques.

A bacterial proteorhodopsin proton pump in marine eukaryotes.

Proteorhodopsins are light-driven proton pumps involved in widespread phototrophy. Discovered in marine proteobacteria just 10 years ago, proteorhodopsins are now known to have been spread by lateral gene transfer across diverse prokaryotes, but are curiously absent from eukaryotes. In this study, we show that proteorhodopsins have been acquired by horizontal gene transfer from bacteria at least twice independently in dinoflagellate protists.

Microbial diversity associated with four functional groups of benthic reef algae and the reef-building coral Montastraea annularis.

The coral reef benthos is primarily colonized by corals and algae, which are often in direct competition with one another for space. Numerous studies have shown that coral-associated Bacteria are different from the surrounding seawater and are at least partially species specific (i.e.

Branching network of proteinaceous filaments within the parasitophorous vacuole of Encephalitozoon cuniculi and Encephalitozoon hellem.

The microsporidia are a diverse phylum of obligate intracellular parasites that infect all major animal groups and have been recognized as emerging human pathogens for which few chemotherapeutic options currently exist. These organisms infect every tissue and organ system, causing significant pathology, especially in immune-compromised populations. The microsporidian spore employs a unique infection strategy in which its contents are delivered into a host cell via the polar tube, an organelle that lies coiled within the resting spore but erupts with a force sufficient to pierce the plasma membrane of its host cell.

Shrink it or lose it: balancing loss of function with shrinking genomes in the microsporidia.

Microsporidia are obligate intracellular parasites that have evolved an elaborate mechanism for invading animal host cells, but which have otherwise greatly reduced biological complexity. In particular, microsporidia possess the smallest autonomous nuclear genomes known (as opposed to nucleus derived organelles, or nucleomorphs), and their 'anaerobic' core carbon metabolism is severely limited. Here we compare the extremes to which these two characteristics have evolved, and contrast how their reduction has either proceeded within the constraints of an unchanging set of functions, or has reduced the functional capabilities of the cell.

Evolution of Rhizaria: new insights from phylogenomic analysis of uncultivated protists.

Background: Recent phylogenomic analyses have revolutionized our view of eukaryote evolution by revealing unexpected relationships between and within the eukaryotic supergroups. However, for several groups of uncultivable protists, only the ribosomal RNA genes and a handful of proteins are available, often leading to unresolved evolutionary relationships. A striking example concerns the supergroup Rhizaria, which comprises several groups of uncultivable free-living protists such as radiolarians, foraminiferans and gromiids, as well as the parasitic plasmodiophorids and haplosporids.

Molecular and morphological analysis of the family Calonymphidae with a description of Calonympha chia sp. nov., Snyderella kirbyi sp. nov., Snyderella swezyae sp. nov. and Snyderella yamini sp. nov.

Calonymphids are a group of multinucleate, multiflagellate protists belonging to the order Cristamonadida (Parabasalia) that are found exclusively in the hindgut of termites from the family Kalotermitidae. Despite their impressive morphological complexity and diversity, few species have been formally described and fewer still have been characterized at the molecular level. In this study, four novel species of calonymphids were isolated and characterized: Calonympha chia and Snyderella yamini spp.

Environmental barcoding reveals massive dinoflagellate diversity in marine environments.

Background: Dinoflagellates are an ecologically important group of protists with important functions as primary producers, coral symbionts and in toxic red tides. Although widely studied, the natural diversity of dinoflagellates is not well known. DNA barcoding has been utilized successfully for many protist groups.

Towards IV drug standardization in critical care.

Local infusion practice within critical care has evolved over time, and one example of this is the wide variation in concentrations of drug infusions within critical care. While there are many similarities between critical care units, there are also many differences. Often drug infusions are used outside their product licence and, because of the diversity in practice, manufacturers are unlikely to license multiple preparations of even the most commonly used infusions.

Complex phylogenetic distribution of a non-canonical genetic code in green algae.

Background: A non-canonical nuclear genetic code, in which TAG and TAA have been reassigned from stop codons to glutamine, has evolved independently in several eukaryotic lineages, including the ulvophycean green algal orders Dasycladales and Cladophorales. To study the phylogenetic distribution of the standard and non-canonical genetic codes, we generated sequence data of a representative set of ulvophycean green algae and used a robust green algal phylogeny to evaluate different evolutionary scenarios that may account for the origin of the non-canonical code.

Results: This study demonstrates that the Dasycladales and Cladophorales share this alternative genetic code with the related order Trentepohliales and the genus Blastophysa, but not with the Bryopsidales, which is sister to the Dasycladales.

The complete sequence of the smallest known nuclear genome from the microsporidian Encephalitozoon intestinalis.

The genome of the microsporidia Encephalitozoon cuniculi is widely recognized as a model for extreme reduction and compaction. At only 2.9 Mbp, the genome encodes approximately 2,000 densely packed genes and little else.