A SeqA hyperstructure and its interactions direct the replication and sequestration of DNA

A level of explanation in biology intermediate between macromolecules and cells has recently been proposed. This level is that of hyperstructures. One class of hyperstructures comprises the genes, mRNA, proteins and lipids that assemble to fulfil a particular function and disassemble when no longer required. To reason in terms of hyperstructures, it is essential to understand the factors responsible for their formation. These include the local concentration of sites on DNA and their cognate DNA-binding proteins. In Escherichia coli, the formation of a SeqA hyperstructure via the phenomenon of local concentration may explain how the binding of SeqA to hemimethylated GATC sequences leads to the sequestration of newly replicated origins of replication.     

Spatial memory shapes migration and its benefits: evidence from a large herbivore

From fine‐scale foraging to broad‐scale migration, animal movement is shaped by the distribution of resources. There is mounting evidence, however, that learning and memory also guide movement. Although migratory mammals commonly track resource waves, how resource tracking and memory guide long‐distance migration has not been reconciled. We examined these hypotheses using movement data from four populations of migratory mule deer (n = 91). Spatial memory had an extraordinary influence on migration, affecting movement 2–28 times more strongly than tracking spring green‐up or autumn snow depth. Importantly, with only an ability to track resources, simulated deer were unable to recreate empirical migratory routes. In contrast, simulated deer with memory of empirical routes used those routes and obtained higher foraging benefits. For migratory terrestrial mammals, spatial memory provides knowledge of where seasonal ranges and migratory routes exist, whereas resource tracking determines when to beneficially move within those areas.     

Surface Vulnerability of Cerebral Cortex to Major Depressive Disorder

Major depressive disorder (MDD) is accompanied by atypical brain structure. This study first presents the alterations in the cortical surface of patients with MDD using multidimensional structural patterns that reflect different neurodevelopment. Sixteen first-episode, untreated patients with MDD and 16 matched healthy controls underwent a magnetic resonance imaging (MRI) scan. The cortical maps of thickness, surface area, and gyrification were examined using the surface-based morphometry (SBM) approach. Increase of cortical thickness was observed in the right posterior cingulate region and the parietal cortex involving the bilateral inferior, left superior parietal and right paracentral regions, while decreased thickness was noted in the parietal cortex including bilateral pars opercularis and left precentral region, as well as the left rostral-middle frontal regions in patients with MDD. Likewise, increased or decreased surface area was found in five sub-regions of the cingulate gyrus, parietal and frontal cortices (e.g., bilateral inferior parietal and superior frontal regions). In addition, MDD patients exhibited a significant hypergyrification in the right precentral and supramarginal region. This integrated structural assessment of cortical surface suggests that MDD patients have cortical alterations of the frontal, parietal and cingulate regions, indicating a vulnerability to MDD during earlier neurodevelopmental process.     

Physiological responses of Pterocladia and Gelidium (Gelidiales,Rhodophyta) from the Azores,Portugal

Manometric studies were conducted on Pterocladia capillacea, Gelidium latifolium and Gelidium spinulosum from the Azores, Portugal to determine optimal values of temperature, light and salinity for growth. Physiological responses were considered in relation to vertical distribution patterns of these species commonly observed throughout the Azores. Optimal parameters for the growth of Pterocladia capillacea, Gelidium latifolium and G. spinulosum were 17 to 25 °C, a photon flux density between 200 and 300 µmol m^–2 s^–1 and salinities of 25 to 35.     

Isolation of an Lc-specific Escherichia coli bacteriophage.

We isolated an OmpF-specific bacteriophage whose host range mutant, SQ108h2, requires the presence of the Lc porin for its attachment and which can be used to screen or select for Lc-defective mutants among Escherichia coli K-12 strains lysogenic for the PA-2 converting phage.     

Membrane Association of Conjugally Transferred Deoxyribonucleic Acid in Escherichia coli Minicells

The conjugally acquired deoxyribonucleic acid (DNA) of small, anucleate cells ("minicells") of a mutant strain of Escherichia coli K-12 was found to be predominantly associated with the bacterial membrane. Evidence from X-irradiation studies in vivo shows that there is no decrease in DNA-membrane association under conditions which reduce the DNA to one-sixth its original size and suggests the possibility of multiple DNA-membrane association sites. Preliminary enzymatic studies indicate the involvement of protein, DNA, and lipids in the membrane association of the DNA.     

Erwinia chrysanthemi tolC is involved in resistance to antimicrobial plant chemicals and is essential for phytopathogenesis

TolC is the outer-membrane component of several multidrug resistance (MDR) efflux pumps and plays an important role in the survival and virulence of many gram-negative bacterial animal pathogens. We have identified and characterized the outer-membrane protein-encoding gene tolC in the bacterial plant pathogen Erwinia chrysanthemi EC16. The gene was found to encode a 51-kDa protein with 70% identity to its Escherichia coli homologue. The E. chrysanthemi gene was able to functionally complement the E. coli tolC gene with respect to its role in MDR efflux pumps. A tolC mutant of E. chrysanthemi was found to be extremely sensitive to antimicrobial agents, including several plant-derived chemicals. This mutant was unable to grow in planta and its ability to cause plant tissue maceration was severely compromised. The tolC mutant was shown to be defective in the efflux of berberine, a model antimicrobial plant chemical. These results suggest that by conferring resistance to the antimicrobial compounds produced by plants, the E. chrysanthemi tolC plays an important role in the survival and colonization of the pathogen in plant tissue.