Nuage constituents arising from mitochondria: Is it possible?

An ultrastructural study of nuage-mitochondria complexes in spermatogonia of the sea urchin, Anthocidaris crassispina, was carried out. Release of mitochondrial contents into the cytoplasm was observed. The mitochondrial derivatives persisted as cristae-containing globules of friable material that subsequently contacted and integrated with nuage. The present ultrastructural findings agree with the results of other researchers who proposed that germ plasm substance probably produced by the nucleus is supplemented by the mitochondrial genome.     

Is it possible to predict amyloidogenic regions from sequence alone?

Identification of potentially amyloidogenic regions in polypeptide chains is very important because the amyloid fibril formation can be induced in most normal proteins. In our work we suggest a new method to detect amyloidogenic regions in protein sequence. It is based on the assumption that packing is tight inside an amyloid and therefore regions which could potentially pack well would have a tendency to form amyloids. This means that the regions with strong expected packing of residues would be responsible for the amyloid formation. We use this property to identify potentially amyloidogenic regions in proteins basing on their amino acid sequences only. Our predictions are consistent with known disease-related amyloidogenic regions for 8 of 11 amyloid-forming proteins and peptides in which the positions of amyloidogenic regions have been revealed experimentally. Predictions of the regions which are responsible for the formation of amyloid fibrils in proteins unrelated to disease have been also done.     

Abscisic acid in the xylem: where does it come from, where does it go to?

Abscisic acid is a hormonal stress signal that moves in the xylem from the root to the different parts of the shoot where it regulates transpirational water loss and leaf growth. The factors that modify the intensity of the ABA signal in the xylem are of particular interest because target cells recognize concentrations. ABA(xyl), will be decreased as radial water flow through the roots is increased, assuming that radial ABA transport occurs in the symplast only. Such dilutions of the plant hormone concentration can be compensated in different ways, which help to keep the ABA-concentrations in the xylem constant: (i) apoplastic bypass flows of ABA, (ii) ABA flows between the stem parenchyma and the xylem during transport and (iii) the action of beta-D-glucosidases that release free ABA from its conjugates to the root cortex and the leaf apoplast. The significance of reflection coefficients (sigma(ABA)), permeability coefficients of membranes (P(S)(ABA)) and apoplastic barriers for ABA is discussed.     

Biogas from Macroalgae: is it time to revisit the idea?

The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae) for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example.     

Information from single-cell bacterial biosensors: what is it good for?

Bacterial reporter cells (i.e. strains engineered to produce easily measurable signals in response to one or more chemical targets) can principally be used to quantify chemical signals and analytes, physicochemical conditions and gradients on a microscale (i.e. micrometer to submillimeter distances), when the reporter signal is determined in individual cells. This makes sense, as bacterial life essentially thrives in microheterogenic environments and single-cell reporter information can help us to understand the microphysiology of bacterial cells and its importance for macroscale processes like pollutant biodegradation, beneficial bacteria-eukaryote interactions, and infection. Recent findings, however, showed that clonal bacterial populations are essentially always physiologically, phenotypically and genotypically heterogeneous, thus emphasizing the need for sound statistical approaches for the interpretation of reporter response in individual bacterial cells. Serious attempts have been made to measure and interpret single-cell reporter gene expression and to understand variability in reporter expression among individuals in a population.     

Free cholesterol in atherosclerotic plaques: where does it come from?

PURPOSE OF REVIEW: Free cholesterol in plaques is an emerging contributing factor to lesion instability and, until recently, apoptosis of lipid-laden macrophages was considered the major source of free cholesterol. The validity of this concept is beginning to be challenged since there is recent evidence of erythrocyte membrane-derived cholesterol in plaques. Therefore, intraplaque hemorrhage may not be a passive event, as once considered as studies continue to support the relationship of intraplaque hemorrhage and necrotic core expansion. RECENT FINDINGS: The association of intraplaque hemorrhage, accumulated free cholesterol, and necrotic core expansion is beginning to unfold and recent MRI studies suggest the value of intraplaque hemorrhage as a predictor of recurrent cerebrovascular events. The amount of erythrocyte membrane-derived cholesterol is also suggested to be a measure of lesion vulnerability in acute coronary syndromes. Recent inhibitors studies of vascular permeability factors further emphasize the importance of intraplaque hemorrhage in plaque progression. Finally, DNA microarray analysis is starting to reveal key molecules involved in the accumulation of free cholesterol that are selectively induced in high-risk plaques. SUMMARY: These recent findings emphasize the importance of intraplaque hemorrhage as a contributor of free cholesterol in plaques and point to its provocative role in lesion destabilization.     

Proteomic cancer biomarkers from discovery to approval: it’s worth the effort

The current landscape of cancer biomarkers is changing rapidly, with new and exciting developments. With the advances of proteomic technologies, many potential cancer biomarkers have been discovered. However, the number of new cancer biomarkers cleared or approved by the US FDA is rather limited. Although technological advances are important, clearly defining intended use, good study design and appropriate patient specimens are critical for the success of FDA approval. While obtaining FDA clearance/approval for newly developed and clinically useful cancer biomarkers has been slow, the reward for patient care could be enormous.     

Molecular recognition of plant DNA: Does it differ from conventional animal DNA?

The recognition mechanism of DNA with small drugs/ligands is an important field of research from pharmacological point of view. Such studies are ample with DNAs extracted from animal cells, but are rare for those extracted from plant cells. However, such a study is strongly demanding for the formulation of pesticides and other agrochemicals. In this contribution, for the first time, we report the interaction of two well-known DNA binder ethidium bromide (EB) and Hoechst 33258 (H33258) with two genomic DNAs extracted from the leaves of Ricinus communis L. (castor bean) and Mangifera indica (mango) using steady-state and picosecond-resolved fluorescence spectroscopy. The purity of the extracted DNAs is confirmed from gel electrophoresis and optical absorption studies. As evidenced from the circular dichroism (CD) measurements the DNAs retain physiologically relevant B forms. The well-known DNA intercalator EB has been found to show an additional electrostatic mode of binding with the DNAs, which is not present in the conventional animal DNAs. The binding affinity of EB is found to be even weaker for the DNA extracted from M. indica compared to that in R. communis L. On the other hand, the binding affinity of H33258 with the plant DNAs is found to be comparable to that of animal DNAs. The difference in interaction could be rationalized from the possible differences in the base sequences.     

NAD-dependent hydrogenase from Alcaligenes eutrophus Z1: Does it have a regulatory centre?

Evidence is presented for the existence of a relatively high-potential regulatory centre in the NAD-dependent hydrogenase from the hydrogen oxidizing bacterium Alcaligenes eutrophus Z1. Reduction of the hydrogenase to the redox potentials lower than -100 mV converts the enzyme into a catalytically active state that is remarkably stable to oxidants. Once activated, the enzyme does not loose its activity on intensive oxygenation for at least 3 hours. A novel hydrogenase ESR signal with a wide temperature optimum and a approximately -100 mV midpoint redox potential was detected. We suggest that the reduction of this redox centre trigger conformational changes in the inactive oxidized enzyme molecule, thus reorganizing the latter into the active one.     

Radiation from mobile phone systems: Is it perceived as a threat to people's health?

The aim of this study was to explore the prevalence, nature and determinants of concerns about mobile phone radiation. We used data from a 2006 telephone survey of 1004 people aged 15+ years in Denmark. Twenty‐eight percent of the respondents were concerned about exposure to mobile phone radiation; radiation from masts was of concern to about 15%. In contrast, 82% were concerned about pollution. Nearly half of the respondents considered the mortality risk of 3G phones and masts to be of the same order of magnitude as being struck by lightning (0.1 fatalities per million people per year) while 7% thought it was equivalent to tobacco‐induced lung cancer (～500 fatalities per million per year). Among women, concerns about mobile phone radiation were positively associated with educational attainment, perceived mobile phone mortality risk and concerns about unknown consequences of new technologies. More than two thirds of the respondents felt that they had received inadequate public information about the 3G system. The results of the study indicate that the majority of the population has little concern about mobile phone radiation while a small minority is very concerned. Bioelectromagnetics 30:393–401, 2009. © 2009 Wiley‐Liss, Inc.     

Step on it: can footprints from tracking tunnels be used to identify lizard species?

There are few effective or efficient established methods for monitoring cryptic herpetofauna. Footprint tracking tunnels are routinely used to index small mammal populations, but also have potential for monitoring herpetofauna. We evaluated the utility of tracking tunnels for identification of New Zealand lizards using captive- and wild-sourced animals (four skink and eight gecko species). All skink prints that we obtained were indistinct or obscure, but we obtained relatively clear, measurable prints for all gecko species. We found that identification to species level was possible for the two gecko species for which we had a large sample—Naultinus gemmeus and Woodworthia ‘Otago large’—using linear discriminant analysis (the best model correctly assigned 96.1% of individuals). Our findings suggest that footprints from tracking tunnels may be used to distinguish between species of geckos. Additional research is needed to assess the ability to further discriminate intra- and inter-genera lizard footprints from tracking tunnels, and the utility of the technique for surveying and monitoring lizard populations.     

Chemical carcinogenicity: can it be predicted from knowledge of mutagenicity and allergic contact dermatitis?

Naturally occurring substances were tested for genotoxicity using a modified laboratory protocol of the Escherichia coli PQ37 genotoxicity assay (SOS chromotest) in the presence and in the absence of an exogenous metabolizing system from rat liver S9-mix. Aristolochic acid I, II, the plant extract aristolochic acid and psoralene were genotoxic; cycasine, emodine, monocrotaline and retrorsine were classified as marginal genotoxic in the SOS chromotest in the absence of S9-mix. In the presence of an exogenous metabolizing system from rat liver S9-mix aristolochic acid I, the plant extract, beta-asarone, cycasin, monocrotaline, psoralen and retrorsine showed genotoxic effects; aristolochic acid II marginal genotoxic effects. Arecoline, benzyl acetate, coumarin, isatidine dihydrate, reserpine, safrole, sanguinarine chloride, senecionine, senkirkine, tannin and thiourea revealed no genotoxicity in the SOS chromotest either in the presence or in the absence of an exogenous metabolizing system from rat liver S9-mix. For 17 of 20 compounds, the results obtained in the SOS chromotest could be compared to those obtained in the Ames test. It was found that 12 (70.6%) of these compounds give similar responses in both tests (6 positive and 6 negative responses). The present investigation and those reported earlier, the SOS chromotest, using E. coli PQ37, was able to detect correctly most of the Salmonella mutagens and non-mutagens.