The brain mechanism of error detection: the P.E.T. study

In present research, the brain maintenance of the error detection mechanism was studied in resting condition and while subjects consciously implemented incorrect actions (i.e. deception). Assessment of the regional cerebral blood flow revealed involvement of anterior cingulated cortex in deception. The obtained data indicate that it is impossible to consciously control the activity of the error detection mechanism. PET study of patients with obsessive compulsive disorder in resting condition revealed a decrease of brain glucose metabolism in the anterior cingulated cortex in comparison with healthy subjects. These data pointed to malfunctioning of the error detection mechanism. The findings support the formerly proposed hypothesis about the impact of the error detection mechanism in formation and support of obsessive compulsive disorder.     

Hippocampal neurogenesis is associated with migratory behaviour in adult but not juvenile sparrows (Zonotrichia leucophrys ssp.)

It has been hypothesized that individuals who have higher demands for spatially based behaviours should show increases in hippocampal attributes. Some avian species have been shown to use a spatially based representation of their environment during migration. Further, differences in hippocampal attributes have been shown between migratory and non-migratory subspecies as well as between individuals with and without migratory experience (juveniles versus adults). We tested whether migratory behaviour might also be associated with increased hippocampal neurogenesis, and whether potential differences track previously reported differences in hippocampal attributes between a migratory (Zonotrichia leucophrys gambelii) and non-migratory subspecies (Z. l. nuttalli) of white-crowned sparrows. We found that non-migratory adults had relatively fewer numbers of immature hippocampal neurons than adult migratory birds, while adult non-migrants had a lower density of new hippocampal neurons than adult and juvenile migratory birds and juvenile non-migratory birds. Our results suggest that neurogenesis decreases with age, as juveniles, regardless of migratory status, exhibit similar and higher levels of neurogenesis than non-migratory adults. However, our results also suggest that adult migrants may either seasonally increase or maintain neurogenesis levels comparable to those found in juveniles. Our results thus suggest that migratory behaviour in adults is associated with maintained or increased neurogenesis and the differential production of new neurons may be the mechanism underpinning changes in the hippocampal architecture between adult migratory and non-migratory birds.     

Temperature cues phenological synchrony in ant‐mediated seed dispersal

Species‐specific climate responses within ecological communities may disrupt the synchrony of co‐evolved mutualisms that are based on the shared timing of seasonal events, such as seed dispersal by ants (myrmecochory). The spring phenology of plants and ants coincides with marked changes in temperature, light and moisture. We investigate how these environmental drivers influence both seed release by early and late spring woodland herb species, and initiation of spring foraging by seed‐dispersing ants. We pair experimental herbaceous transplants with artificial ant bait stations across north‐ and south‐facing slopes at two contrasting geographic locations. This use of space enables robust identification of plant fruiting and ant foraging cues, and the use of transplants permits us to assess plasticity in plant phenology. We find that warming temperatures act as the primary phenological cue for plant fruiting and ant foraging. Moreover, the plasticity in plant response across locations, despite transplants being from the same source, suggests a high degree of portability in the seed‐dispersing mutualism. However, we also find evidence for potential climate‐driven facilitative failure that may lead to phenological asynchrony. Specifically, at the location where the early flowering species (Hepatica nobilis) is decreasing in abundance and distribution, we find far fewer seed‐dispersing ants foraging during its fruit set than during that of the later flowering Hexastylis arifolia. Notably, the key seed disperser, Aphaenogaster rudis, fails to emerge during early fruit set at this location. At the second location, A. picea forages equally during early and late seed release. These results indicate that climate‐driven changes might shift species‐specific interactions in a plant–ant mutualism resulting in winners and losers within the myrmecochorous plant guild.     

Development of cardiac form and function in ectothermic sauropsids

Evolutionary morphologists and physiologists have long recognized the phylogenetic significance of the ectothermic sauropsids. Sauropids have been classically considered to bridge between early tetrapods, ectotherms, and the evolution of endotherms. This transition has been associated with many modifications in cardiovascular form and function, which have changed dramatically during the course of vertebrate evolution. Most cardiovascular studies have focused upon adults, leaving the development of this critical system largely unexplored. In this essay, we attempt a synthesis of sauropsid cardiovascular development based on the limited literature and indicate fertile regions for future studies. Early morphological cardiovascular development, i.e., the basic formation of the tube heart and the major pulmonary and systemic vessels, is similar across tetrapods. Subsequent cardiac chamber development, however, varies considerably between developing chelonians, squamates, crocodilians, and birds, reflected in the diversity of adult ventricular structure across these taxa. The details of how these differences in morphology develop, including the molecular regulation of cardiac and vascular growth and differentiation, are still poorly understood. In terms of the functional maturation of the cardiovascular system, reflected in physiological mechanisms for regulating heart rate and cardiac output, recent work has illustrated that changes during ontogeny in parameters such as heart rate and arterial blood pressure are somewhat species‐dependent. However, there are commonalities, such as a β‐adrenergic receptor tone on the embryonic heart appearing prior to 60% of development. Differential gross morphological responses to environmental stressors (oxygen, hydration, temperature) have been investigated interspecifically, revealing that cardiac development is relatively plastic, especially, with respect to change in heart growth. Collectively, the data assembled here reflects the current limited morphological and physiological understanding of cardiovascular development in sauropsids and identifies key areas for future studies of this diverse vertebrate lineage. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

Morpho-functional features in adolescent males under iodine deficiency of the Saratov region

An auxological study of 538 adolescent males (from 12 to 17) from different settlements of the Saratov region with various degrees of industrialization and iodine deficiency was carried out. All subjects have undergone an ultra-sound screening of thyroid volume to reveal the frequency of endemic goiter in each group. The results obtained during investigation showed the existence of deviations in the physical development of boys with goiter in skinfold thickness, body circumferences (chest, shoulder, and forearm), biacromial and biiliocristal diameters, transversal and sagittal chest diameters, body height and weight, BMI, leg length, and corpus length, all of which are greater in healthy adolescents (SD = 1.0, p = 0.000). In 46 subjects with endemic goiter, characteristics of metabolic status were investigated by the method of registration of endogenous intoxication (Malakhova, 1995). In comparison to the control group, a 1.2 times lower LAMM level in erythrocytes (p < 0.05) and 1.1 in urine (p < 0.05), and an increase by 2.3 in the LAMM level in blood plasma (p < 0.01) were detected. The relative percentage of catabolic substances exceeded the control values by 3.2 (p < 0.001). The OP level in erythrocytes is reduced by 2.2 (p < 0.01), in urine (p < 0.01) by 8.4. The OP level is higher in plasma by 3.0 (p < 0.01). The adolescents with endemic goiter have a reallocation of protein matter between erythrocytes, plasma and urine. The spectrogram of erythrocytes shows lowering metabolites on membrane frames, which testifies to the destruction of the structurally functional properties of erythrocytes, and a lowering of absorption properties in glycocalix erythrocytes.     

Comparison of Small- and Large-scale Expression of Selected Pyrococcus furiosus Genes as an Aid to High-throughput Protein Production

As the natural extension of the genomic sequencing projects, the goal of the various world-wide Structural Genomics projects is development of techniques for high throughput (HTP) cloning, protein overexpression, purification and structural determination, with the ultimate goal of determining all possible protein structures. Rapid (small-scale) screening of potential expression clones under different growth conditions is presumed to be possible and a viable way to increase throughput of protein expression. In order to test the utility of screening for soluble, heterologous protein expression, we have compared the production of recombinant proteins on a small scale (1 ml cultures in 96-well plates) in Escherichia coli under two growth conditions [a rich medium and a defined (minimal) medium] using an enzyme-linked immunosorbent assay (ELISA) against the affinity tag, with the amount of recombinant protein produced during the large-scale (500 ml) growth of E. coli. The large-scale expression products were examined after a single step affinity purification by visualization on SDS-PAGE gels. Of the open reading frames that were successfully expressed on the 1 ml scale as judged by immunodetection, 80% of them successfully scaled-up to 500 ml in a rich medium and 81% of them scaled-up in a defined medium. This is significantly higher than would be expected by a randomly selected expression condition and validates the use of small-scale expression as a screening tool for more efficient protein production.     

Visualization of early chromosome condensation: a hierarchical folding, axial glue model of chromosome structure

Current models of mitotic chromosome structure are based largely on the examination of maximally condensed metaphase chromosomes. Here, we test these models by correlating the distribution of two scaffold components with the appearance of prophase chromosome folding intermediates. We confirm an axial distribution of topoisomerase IIalpha and the condensin subunit, structural maintenance of chromosomes 2 (SMC2), in unextracted metaphase chromosomes, with SMC2 localizing to a 150-200-nm-diameter central core. In contrast to predictions of radial loop/scaffold models, this axial distribution does not appear until late prophase, after formation of uniformly condensed middle prophase chromosomes. Instead, SMC2 associates throughout early and middle prophase chromatids, frequently forming foci over the chromosome exterior. Early prophase condensation occurs through folding of large-scale chromatin fibers into condensed masses. These resolve into linear, 200-300-nm-diameter middle prophase chromatids that double in diameter by late prophase. We propose a unified model of chromosome structure in which hierarchical levels of chromatin folding are stabilized late in mitosis by an axial "glue."     

The ecological relevance of sleep: the trade-off between sleep,memory and energy conservation

All animals in which sleep has been studied express signs of sleep-like behaviour, suggesting that sleep must have some fundamental functions that are sustained by natural selection. Those functions, however, are still not clear. Here, we examine the ecological relevance of sleep from the perspective of behavioural trade-offs that might affect fitness. Specifically, we highlight the advantage of using food-caching animals as a system in which a conflict might occur between engaging in sleep for memory/learning and hypothermia/torpor to conserve energy. We briefly review the evidence for the importance of sleep for memory, the importance of memory for food-caching animals and the conflicts that might occur between sleep and energy conservation in these animals. We suggest that the food-caching paradigm represents a naturalistic and experimentally practical system that provides the opportunity for a new direction in sleep research that will expand our understanding of sleep, especially within the context of ecological and evolutionary processes.     

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

The membrane-spanning segments of integral membrane proteins often are flanked by aromatic or charged amino acid residues, which may “anchor” the transmembrane orientation. Single spanning transmembrane peptides such as those of the WALP family, acetyl-GWW(LA)_nLWWA-amide, furthermore adopt a moderate average tilt within lipid bilayer membranes. To understand the anchor residue dependence of the tilt, we introduce Leu-Ala “spacers” between paired anchors and in some cases replace the outer tryptophans. The resulting peptides, acetyl-GX²ALW(LA)₆LWLAX²²A-amide, have Trp, Lys, Arg, or Gly in the two X positions. The apparent average orientations of the core helical sequences were determined in oriented phosphatidylcholine bilayer membranes of varying thickness using solid-state ²H NMR spectroscopy. When X is Lys, Arg, or Gly, the direction of the tilt is essentially constant in different lipids and presumably is dictated by the tryptophans (Trp⁵ and Trp¹⁹) that flank the inner helical core. The Leu-Ala spacers are no longer helical. The magnitude of the apparent helix tilt furthermore scales nicely with the bilayer thickness except when X is Trp. When X is Trp, the direction of tilt is less well defined in each phosphatidylcholine bilayer and varies up to 70° among 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, and 1,2-dilauroyl-sn-glycero-3-phosphocholine bilayer membranes. Indeed, the X = Trp case parallels earlier observations in which WALP family peptides having multiple Trp anchors show little dependence of the apparent tilt magnitude on bilayer thickness. The results shed new light on the interactions of arginine, lysine, tryptophan, and even glycine at lipid bilayer membrane interfaces.     

The RpoS-Mediated Regulation of Isocitrate Dehydrogenase Gene Expression in Escherichia coli

The Escherichia coli NADP⁺-dependent isocitrate dehydrogenase (IDH; EC 1.1.1.42), encoded by an icd gene, is a tricarboxylic acid (TCA) cycle enzyme responsible for the oxidative decarboxylation of isocitrate to α-ketoglutarate. In order to examine how the icd gene expression is regulated, an icd-lacZ reporter fusion was constructed. While the icd gene was induced in exponential growth phase, it was repressed in stationary growth phase. Genetic inactivation of an rpoS gene, whose product is an alternative sigma factor, induced the icd gene expression approximately 4.8 times more in the stationary phase and the IDH enzyme activity in the rpoS mutant was 3.2 times higher than that in the wild type, indicating that the RpoS factor acts as a negative regulator of the icd gene expression in the stationary phase.