The recent evolution of a pseudogene: diversity and divergence of a mitochondria-localized small heat shock protein in Arabidopsis thaliana

In this study we examined the evolution of the genes for three organelle-localized small heat shock proteins in Arabidopsis thaliana: the chloroplast-localized (CP) protein HSP21 and two mitochondria-localized (MT) proteins, HSP23.5 and HSP23.6. We found that the CP protein and one of the MT proteins, HSP23.6, are evolving under purifying selection to maintain function. In contrast, the gene for HSP23.5, the other MT protein, is highly variable within A. thaliana, and in some accessions or ecotypes this gene may be a pseudogene. HSP23.5 and HSP23.6 are related via a segmental duplication event, and the presence of orthologs of each gene in other species within the Brassicaceae indicates that the duplication generating HSP23.5 and HSP23.6 may have occurred as much as 20 million years ago. This is considerably longer than the 4 million year half-life of gene duplicates (functional genes as well as pseudogenes) reported by some studies. Our results are consistent with the prediction that after gene duplication one gene duplicate can be maintained for some time under relaxed selection while it accumulates random mutations. By capturing a pseudogene in the making our study provides important information on how pseudogenes are formed.     

Epigenetic control

Epigenetics refers to mitotically and/or meiotically heritable variations in gene expression that are not caused by changes in DNA sequence. Epigenetic mechanisms regulate all biological processes from conception to death, including genome reprogramming during early embryogenesis and gametogenesis, cell differentiation and maintenance of a committed lineage. Key epigenetic players are DNA methylation and histone post‐translational modifications, which interplay with each other, with regulatory proteins and with non‐coding RNAs, to remodel chromatin into domains such as euchromatin, constitutive or facultative heterochromatin and to achieve nuclear compartmentalization. Besides epigenetic mechanisms such as imprinting, chromosome X inactivation or mitotic bookmarking which establish heritable states, other rapid and transient mechanisms, such as histone H3 phosphorylation, allow cells to respond and adapt to environmental stimuli. However, these epigenetic marks can also have long‐term effects, for example in learning and memory formation or in cancer. Erroneous epigenetic marks are responsible for a whole gamut of diseases including diseases evident at birth or infancy or diseases becoming symptomatic later in life. Moreover, although epigenetic marks are deposited early in development, adaptations occurring through life can lead to diseases and cancer. With epigenetic marks being reversible, research has started to focus on epigenetic therapy which has had encouraging success. As we witness an explosion of knowledge in the field of epigenetics, we are forced to revisit our dogma. For example, recent studies challenge the idea that DNA methylation is irreversible. Further, research on Rett syndrome has revealed an unforeseen role for methyl‐CpG‐binding protein 2 (MeCP2) in neurons. J. Cell. Physiol. 219: 243–250, 2009. © 2009 Wiley‐Liss, Inc.     

Modeling the Past and Current Distribution and Habitat Suitability for Ablepharus grayanus and A. pannonicus(Sauria: Scincidae)

Study of the climate variability in the past and present, and correlating those with changes in the distribution range of species has attracted considerable research interest. The genus Ablepharus consists of 10 recognized species, of which A. bivittatus, A. grayanus and A. pannonicus are documented from Iran. In the present study, we modeled with Max Ent the potential distribution areas and determined the suitable habitats in past(mid-Holocene [MH], and the Last Interglacial [LIG]) and their current distribution for two species of snake-eyed skinks(A. grayanus and A. pannonicus) separately. Models of the species indicated good fit by the average high area under the curve(AUC) values(A. grayanus= 0.929 ± 0.087 and A. pannonicus = 0.979 ± 0.007). Precipitation of the driest quarter of the year, mean temperature of the coldest quarter of the year, and precipitation of the driest month variables made important contributions to A. grayanus. Two important climate variables contributed importantly to A. pannonicus; temperature seasonality, and mean temperature of the wettest quarter of the year, and one topographic variable, slope. We conclude that these variables form a natural barrier for species dispersal. The MH and the LGM models indicated a larger suitable area than the current distribution.     

Effect of manganese on the development of glial cells cultured from prenatally alcohol exposed rats

Maternal alcohol abuse is known to produce retardation in brain maturation and brain functions. Using cultured glial cells as a model system to study these effects of alcohol we found an alcohol antagonizing property for manganese (Mn). Mn was added to the alcohol diet (MnCl₂ 25 mg/l of 20% v/v ethanol) of pregnant rats. Glial cells were cultured during 4 weeks from cortical brain cells of pups born to these mothers. Several biochemical parameters were examined: protein levels, enzymatic markers of glial cell maturation (enolase and glutamine synthetase), superoxide dismutase a scavenger of free radicals produced during alcohol degradation. The results were compared to appropriate controls. A beneficent effect of Mn was observed for the pups weight which was no more significantly different from the control values. Protein levels, enolase and glutamine synthetase activities were increased mainly during the proliferative period when Mn was added to the alcohol diet compared to the only alcohol treated animals. This Mn effect was not found for superoxide dismutase in cultured glial cells but exists in the total brain of the 2 week-old offspring. In the total 2 and 4 week-old brain the alcohol induced decrease of enolase and glutamine synthetase was also antagonized by the Mn suplementation. Our data suggest that Mn may act as a factor overcoming at least partially some aspects of alcohol induced retardation of nerve cell development.     

Flow injection amperometric detection of insulin at cobalt hydroxide nanoparticles modified carbon ceramic electrode

Cobalt hydroxide nanoparticles were prepared onto a carbon ceramic electrode (CHN|CCE) using the cyclic voltammetry (CV) technique. The modified electrode was characterized by X-ray diffraction and scanning electron microscopy. The results showed that CHN with a single-layer structure was uniformly electrodeposited on the surface of CCE. The electrocatalytic activity of the modified electrode toward the oxidation of insulin was studied by CV. CHN|CCE was also used in a homemade flow injection analysis system for insulin determination. The limit of detection (signal/noise [S/N] = 3) and sensitivity were found to be 0.11 nM and 11.8 nA/nM, respectively. Moreover, the sensor was used for detection of insulin in human serum samples. This sensor showed attractive properties such as high stability, reproducibility, and high selectivity.     

Hypo-Vascular Liver Metastases Treated with Transarterial chemoembolization: Assessment of Early Response by Volumetric Contrast-Enhanced and Diffusion-Weighted Magnetic Resonance Imaging

OBJECTIVE: To evaluate the value of anatomic and volumetric functional magnetic resonance imaging (MRI) in early assessment of response to trans-arterial chemoembolization (TACE) in hypovascular liver metastases. METHODS: This retrospective study included 52 metastatic lesions (42 targeted and 10 non-targeted) in 17 patients who underwent MRI before and early after TACE. Two reviewers reported response by anatomic criteria (Response Evaluation Criteria in Solid Tumor [RECIST], modified RECIST [mRECIST], and European Association for the Study of Liver Disease [EASL]) and functional criteria (volumetric apparent diffusion coefficient and contrast enhancement). Treatment endpoint was RECIST at 6 months. A 2-sample paired t test was used to compare the mean changes after intra-arterial therapy. P < .05 was considered statistically significant. RESULTS: Reduction in mRECIST and EASL at 1 month was significant in the whole cohort as well as in responders by RECIST at 6 months, and the changes fulfilled partial response criteria for both metrics in responders. Responders also had significant changes in volumetric apparent diffusion coefficient (P = .01 and P = .03) and contrast enhancement (P < .0001 and P < .0001) at 1 month for both readers, respectively. CONCLUSION: At 1 month post treatment, responders did not fulfill RECIST criteria but fulfilled mRECIST and EASL criteria. In addition, volumetric contrast-enhanced and diffusion-weighted MRI may be helpful in evaluating early treatment response after TACE in hypovascular liver metastases in patients who have failed to respond to initial chemotherapy.     

Action Initiation in the Human Dorsal Anterior Cingulate Cortex

The dorsal anterior cingulate cortex (dACC) has previously been implicated in processes that influence action initiation. In humans however, there has been little direct evidence connecting dACC to the temporal onset of actions. We studied reactive behavior in patients undergoing therapeutic bilateral cingulotomy to determine the immediate effects of dACC ablation on action initiation. In a simple reaction task, three patients were instructed to respond to a specific visual cue with the movement of a joystick. Within minutes of dACC ablation, the frequency of false starts increased, where movements occurred prior to presentation of the visual cue. In a decision making task with three separate patients, the ablation effect on action initiation persisted even when action selection was intact. These findings suggest that human dACC influences action initiation, apart from its role in action selection.