A single origin of the central nervous system?

As Denes et al. (2007) reveal in this issue, the expression profile and roles of genes that pattern the nervous system in embryos of chordates and annelids are surprisingly similar. This extraordinary conservation suggests that the patterning mechanism has been inherited largely unchanged from the bilaterian common ancestor and that the central nervous system, although dorsal in fish and ventral in worms, is an ancient characteristic of animals.     

A Taxonomic Signature of Obesity in the Microbiome? Getting to the Guts of the Matter

Obesity is an important and intractable public health problem. In addition to the well-known risk factors of behavior, diet, and genetics, gut microbial communities were recently identified as another possible source of risk and a potential therapeutic target. However, human and animal-model studies have yielded conflicting results about the precise nature of associations between microbiome composition and obesity. In this paper, we use publicly available data from the Human Microbiome Project (HMP) and MetaHIT, both surveys of healthy adults that include obese individuals, plus two smaller studies that specifically examined lean versus obese adults. We find that inter-study variability in the taxonomic composition of stool microbiomes far exceeds differences between lean and obese individuals within studies. Our analyses further reveal a high degree of variability in stool microbiome composition and diversity across individuals. While we confirm the previously published small, but statistically significant, differences in phylum-level taxonomic composition between lean and obese individuals in several cohorts, we find no association between BMI and taxonomic composition of stool microbiomes in the larger HMP and MetaHIT datasets. We explore a range of different statistical techniques and show that this result is robust to the choice of methodology. Differences between studies are likely due to a combination of technical and clinical factors. We conclude that there is no simple taxonomic signature of obesity in the microbiota of the human gut.     

A Fish-specific Member of the TPPP Protein Family?

A eukaryotic protein family, the tubulin polymerization promoting proteins (TPPPs), has recently been identified. It has been termed after its first member, TPPP/p25 or TPPP1, which exhibits microtubule-stabilizing function and plays a role in neurodegenerative diseases. In mammalian genomes, two further paralogues, TPPP2 and TPPP3, can be found. In this article, I show that TPPP1 and TPPP3, but not TPPP2, are included in paralogons, on human chromosomes, Hsa5 and Hsa16, respectively. I suggest that the single non-vertebrate tppp gene was duplicated in the first round of whole-genome duplication in the vertebrate lineage giving rise to tppp1 and the precursor of tppp2/tppp3. The existence of a teleost fish-specific fourth paralogue, tppp4, has also been raised, but it is not supported by synteny analysis. Alternatively, the new group can be considered as the fish orthologue of TPPP2. The case that the new group is the consequence of the teleost fish-specific whole-genome duplication (3R) cannot be excluded.     

A method to the madness of N-glycan complexity?

Cell-surface glycoprotein receptors have varying numbers of N-glycan sites. In this issue of Cell, Lau et al. (2007) report that increasing intracellular UDP-GlcNAc leads to increased branching of N-glycans, increased receptor association with cell-surface galectin-3, and enhanced signaling. They also show that the kinetics of this response differ between growth-promoting receptors, which have 8-16 N-glycans, and those that induce growth arrest, which have very few N-glycans, suggesting that hexosamine flux may regulate the transition from growth to arrest.     

A silver bullet for the treatment of depression?

The search for a rapid-acting antidepressant has been a subject of intense research interest for several decades. The article by Lucas and colleagues in this issue of Neuron provides compelling evidence from preclinical animal models that drugs acting at the serotonin 5-HT(4) receptor could finally achieve this goal. However, caution is warranted, as results from animal studies are not always predictive of therapeutic actions in humans.     

Can the size of the epiphysis determine the number of secondary ossification centers? A mathematical approach

Previous studies have concluded that the chemical feedback (loop) between two reagent molecular factors through a reaction-diffusion mechanism could explain the stable spatial pattern found in the origin of the secondary ossification centres (SOCs). Furthermore, the emergence of the SOC may depend on the size and shape of the head of the bone, as observed in different animals. In this paper, we develop new computer simulations that study the effect of the size of the epiphysis on the emergence of the SOC. This study determines two or more SOCs, that may appear in the head of long bones, depending on the size of the epiphysis.     

Can the size of the epiphysis determine the number of secondary ossification centers? A mathematical approach

Previous studies have concluded that the chemical feedback (loop) between two reagent molecular factors through a reaction–diffusion mechanism could explain the stable spatial pattern found in the origin of the secondary ossification centres (SOCs). Furthermore, the emergence of the SOC may depend on the size and shape of the head of the bone, as observed in different animals. In this paper, we develop new computer simulations that study the effect of the size of the epiphysis on the emergence of the SOC. This study determines two or more SOCs, that may appear in the head of long bones, depending on the size of the epiphysis.     

A picture of health? Unmasking the role of appearance in health

Evaluating health requires visual assessment. From the meticulous self-scrutiny of a worried woman in front of the looking glass to the doctor's reaction at the sight of a patient in the examining room, external appearance plays an important role in appraising health above and beyond clinical assessment. However, this dominance of the visual in our image-driven culture has assumed a disproportionately prominent position. Media, businesses, and health care commonly misrepresent appearance as the reality of health. Industry mongers beauty-promoting wares and services as health-protecting products, and physical appearance contributes to clinicians' imperfect heuristics. An explanation for this focus on appearance is persistence of the ancient belief that looks indicate inner character. In this article we unmask the historical origin of this belief and reveal how it contaminates contemporary approaches to health assessment and maintenance.     

Plicatamide: A lead to the biosynthetic origins of the tunichromes?

Plicatamide is a modified octapeptide from the ascidian Styela plicata having the structure Phe-Phe-His-Leu-His-Phe-His-decarboxyDeltaDOPA (where decarboxyDeltaDOPA = decarboxy-(E)-alpha,beta-dehydro-3, 4-dihydroxyphenylalanine). Edman sequencing, tandem mass spectrometry, and proton NMR have been used to characterize 100 microg of the compound. Plicatamide represents an important link between two classes of biomolecules: the tunichromes which share an oxidatively decarboxylated C-terminus and higher molecular weight DOPA-polypeptides. The 8-residue sequence provides the first opportunity to investigate the biosynthetic origins of the tunichrome family by molecular biological techniques.     

A new predictor for the onset of atrial fibrillation?

In this issue of the Netherlands Heart Journal, the results of a substudy of the PREVEND trial are published.1 This prospective registry of presumably healthy citizens of Groningen aims to establish the association between microalbuminuria and the emergence of renal and cardiovascular diseases.2 This general population based long-term study extends the series of previous large-scale epidemiological trials conducted in the Netherlands. We recall among them the 1970 Vlagtwedde study for epidemiological cardiology and ischaemic heart disease, the 1982 Zutphen study of diet and cardiovascular diseases, the 1997 Maastricht study of circulatory arrest and sudden death, the 1998 Amsterdam study of out-of-hospital cardiac arrest and the 1999 Rotterdam study of prolonged QT interval and mortality.     

A carboxysomal carbon-concentrating mechanism in the cyanelles of the 'coelacanth' of the algal world, Cyanophora paradoxa?

Cyanelles are the peculiar plastids of glaucocystophyte algae that retained a peptidoglycan wall from the ancestral cyanobacterial endosymbiont. All cyanobacteria and most algae possess an inorganic carbon-concentrating mechanism (CCM) that involves a microcompartment--carboxysomes in prokaryotes and pyrenoids in eukaryotes--harboring the bulk of cellular (plastidic) Rubisco. In the case of the living fossil, Cyanophora paradoxa, the existence of a CCM was a matter of debate. Microarray data revealing 142 CO(2)-responsive genes (induced or repressed through a shift from high to low CO(2) conditions), gas exchange measurements and measurements of photosynthetic affinity provided strong support for a CCM. We favor a recent hypothesis that glaucocystophyte cyanelles as the closest cousins to cyanobacteria among plastids contain 'eukaryotic carboxysomes': bicarbonate enrichment within cyanelles should be considerably higher than in chloroplasts with their pyrenoid-based CCM. Thus, the stress-bearing function of the peptidoglycan layer, the other unique heritage, would be indispensable. An isolation method for cyanelle 'carboxysomes' was developed and the protein components other than Rubisco analyzed by MS. Rubisco activase was identified and corroborated by western blotting. The well-established cyanelle in vitro import system allows to use them as 'honorary cyanobacteria': assembly processes of supramolecular structures as phycobilisomes and carboxysomes thus can be studied after import of nucleus-encoded precursor proteins and subsequent fractionation. Even minor components can easily be tracked and a surprisingly dynamic view is obtained. Labeled pre-activase was imported into isolated cyanelles and 30% of the mature protein was found to be incorporated into the carboxysome fraction. A final decision between carboxysome or pyrenoid must await the identification of cyanelle carbonic anhydrase and, especially, the demonstration of shell proteins.     

Why migrate? A test of the evolutionary precursor hypothesis

The question of why birds migrate is still poorly understood despite decades of debate. Previous studies have suggested that use of edge habitats and a frugivorous diet are precursors to the evolution of migration in Neotropical birds. However, these studies did not explore other ecological correlates of migration and did not control for phylogeny at the species level. We tested the evolutionary precursor hypothesis by examining the extent to which habitat and diet are associated with migratory behavior, using a species-level comparative analysis of the Tyranni. We used both migratory distance and sedentary versus migratory behavior as response variables. We also examined the influences of foraging group size, membership in mixed-species flocks, elevational range, and body mass on migratory behavior. Raw species analyses corroborated some results from studies that put forth the evolutionary precursor hypothesis, but phylogenetically independent contrast analyses highlighted an important interaction between habitat and diet and their roles as precursors to migration. Foraging group size was consistently associated with migratory behavior in both raw species and independent contrast analyses. Our results lead to a resource variability hypothesis that refines the evolutionary precursor hypothesis and reconciles the results of several studies examining precursors to migration in birds.     

Does domain swapping improve the stability of RNase A?

Self-assembling complexes have potential as novel supramolecular biomaterials but domain swapped complexes have yet to investigated in this capacity. Bovine ribonuclease A (RNase A) is a useful model protein as it is able to form a range of three dimensional domain swapped structures, including dimers, trimers and tetramers that have similar catalytic ability. However, little work has been carried out investigating the physical characteristics of these complexes. In an effort to characterise the strength of these oligomeric interactions, analytical ultracentrifugation was carried out to measure the dissociation of higher order complexes, using fluorescent tags to test for dissociation at very low concentrations. Results of this work suggest that the oligomers form a very tight complex, with no evidence of dissociation down to 250 pM. RNase A oligomers also had similar thermal stability to that of monomeric enzyme, suggesting that the main limiting factor in RNase A stability is the tertiary, rather than quaternary structure. Following thermal unfolding of RNase A, the protein refolded upon cooling, but returned to the monomeric state. This latter result may limit the potential of domain swapping as a means of material assembly.     

Was the Duchess of windsor right? A cross-cultural review of the socioecology of ideals of female body shape

Why do some cultures prefer thin women, while others value female fatness? Using the Standard Cross Cultural Sample, we investigated predictions derived from several socioecological hypotheses related to three biological functions of human female body fat (insulation, storage of calories, and regulation of fertility). Results suggest that attitudes toward fatness in women are related cross-culturally to (1) reliability of food supply, (2) climate, (3) relative social dominance of women, (4) the value placed on women's work, and (5) the probability that the expression of adolescent sexuality will have adverse consequences on girls. These hypotheses may be useful in providing an ultimate explanation for currently observed patterns in attitudes toward female fatnness, complementing the more proximate approach of the traditional social sciences.