Effects of Apolipoprotein E Genotype on the Off-Line Memory Consolidation

Spontaneous brain activity or off-line activity after memory encoding is associated with memory consolidation. A few recent resting-state functional magnetic resonance imaging (RS-fMRI) studies indicate that the RS-fMRI could map off-line memory consolidation effects. However, the gene effects on memory consolidation process remain largely unknown. Here we collected two RS-fMRI sessions, one before and another after an episodic memory encoding task, from two groups of healthy young adults, one with apolipoprotein E (APOE) ε2/ε3 and the other with APOE ε3/ε4. The ratio of regional homogeneity (ReHo), a measure of local synchronization of spontaneous RS-fMRI signal, of the two sessions was used as an index of memory-consolidation. APOE ε3/ε4 group showed greater ReHo ratio within the medial temporal lobe (MTL). The ReHo ratio in MTL was significantly correlated with the recognition memory performance in the APOE ε3/ε4 group but not in ε2/ε3 group. Additionally, APOE ε3/ε4 group showed lower ReHo ratio in the occipital and parietal picture-encoding areas. Our results indicate that APOE ε3/ε4 group may have a different off-line memory consolidation process compared to ε2/ε3 group. These results may help generate future hypotheses that the off-line memory consolidation might be impaired in Alzheimer’s disease.     

1H, 13C and 15N resonance assignments of the major extracytoplasmic domain of the cell shape-determining protein MreC from Bacillus subtilis

MreB, MreC and MreD are essential cell shape-determining morphogenetic proteins in Gram-positive and in Gram-negative bacteria. While MreB, the bacterial homologue of the eukaryotic cytoskeletal protein actin, has been extensively studied, the roles of MreC and MreD are less well understood. They both are transmembrane proteins. MreC has a predicted single transmembrane domain and the C-terminal part outside the cell membrane. MreC probably functions as a link between the intracellular cytoskeleton and the cell wall synthesizing machinery which is located at the outer surface of the cell membrane. Also proteins involved in cell wall synthesis participate in cell morphogenesis. How these two processes are coordinated is, however, poorly understood. Bacillus subtilis (BS), a non-pathogenic Gram-positive bacterium, is widely used as a model for Gram-positive pathogens, e.g. Staphylococcus aureus (SA). Currently, the structures of MreC from BS and SA are not known. As part of our efforts to elucidate the structure–function relationships of the morphogenetic protein complexes in Gram-positive bacteria, we present the backbone and side chain resonance assignments of the extracytoplasmic domain of MreC from BS.     

A short-lived herbivore on a long-lived host: tree resistance to herbivory depends on leaf age

Short-lived insect herbivores should be able to adapt to the resistance mechanisms of their long-lived woody hosts because the life span of a single host will encompass numerous generations of herbivores. However, adaptation may be slowed down if host genotypes can create, in a single genotype, such large phenotypic variation in traits relevant for the herbivore that it matches variance among host genotypes. We tested this hypothesis by measuring leaf consumption by, and growth of, half-sibs of the geometrid moth Epirrita autumnata on individual birch trees, during three instars. The instar×tree interaction, rather than tree identity alone, was a significant variance component for both consumption and growth, indicating that different larval instars ranked individual trees differently. Both consumption and growth varied most between the 3rd and the later (4th and 5th) instars, coinciding with rapid seasonal changes in numerous nutritive and phenolic traits of maturing leaves. Thus, developmental variance in the leaf quality of individual trees may reduce the likelihood of E. autumnata genotypes adapting to the defenses of their host trees. We did not find evidence of in the ability of different half-sibs to utilize individual trees or leaf stages, indicating that E. autumnata larvae are generalists over a wide variety of host traits.     

Absence of TGFβ signaling in embryonic vascular smooth muscle leads to reduced lysyl oxidase expression,impaired elastogenesis,and aneurysm

To address the requirement for TGFβ signaling in the formation and maintenance of the vascular matrix, we employed lineage‐specific mutation of the type II TGFβ receptor gene (Tgfbr2) in vascular smooth muscle precursors in mice. In both neural crest‐ and mesoderm‐derived smooth muscle, absence of TGFβ receptor function resulted in a poorly organized vascular elastic matrix in late‐stage embryos which was prone to dilation and aneurysm. This defect represents a failure to initiate formation of the elastic matrix, rather than a failure to maintain a preexisting matrix. In mutant tissue, lysyl oxidase expression was substantially reduced, which may contribute to the observed pathology. genesis 47:115–121, 2009. © 2009 Wiley‐Liss, Inc.     

Secretion of the Hormoconis resinae glucoamylase P enzyme from Trichoderma reesei directed by the natural and the cbh1 gene secretion signal

Abstract We have isolated two alkaline phosphatases (H-AP and L-AP, for high and low molecular mass, respectively) from Pseudomonas aeruginosa PA01. These two enzymes were found to differ in mobility on sodium dodecyl sulphate polyacrylamide gels (H-AP, M _r = 51 000 and L-AP, M _r = 39 500), amino-terminal amino acid sequence and did not cross-react. Both enzymes were active as phosphomonoesterases while only L-AP demonstrated any phosphodiesterase activity. Both enzymes were purified from P. aeruginosa grown in phosphate limiting conditions using the same protocol and were identified in both periplasmic and extracellular locations. A low level of H-AP was produced constitutively whereas L-AP was produced only after induction by reduced phosphate concentration in the growth medium. An L-AP-like enzyme has been previously described, however, this is the first report of a second P. aeruginosa alkaline phosphatase.     

Female-biased natal dispersal in the Siberian flying squirrel

Natal dispersal is usually sex biased in birds and mammals.Female-biased natal dispersal is the prevailing pattern in birdsbut is rare among mammals. Hypotheses explaining sex bias indispersal include the mate-defense mating hypothesis, whichpredicts male-biased dispersal, the resource-defense hypothesispredicting female-biased dispersal, and the competition hypothesis,which predicts that if dispersal is caused by competition forresources between sexes, then the subdominant sex will disperse.We studied natal dispersal of Siberian flying squirrels Pteromysvolans using radio telemetry in Southern Finland in 1996–2004.Of 86 juveniles that survived over the dispersal period, almostall young females dispersed from the natal site, whereas almost40% of males were philopatric. Dispersal was farther for femalesthan males. Females began dispersal on average 2 weeks earlierthan males and were lighter in mass at the onset of dispersalthan later dispersing males. No mate- or resource-defense matingsystem could be found among males, but females seemed to defendnest and apparently food resources, in contrast to the expectationof dispersal bias in resource-defense systems. Competition forresources between sexes does not explain female bias either:in the flying squirrel, the female seems to be the dominantsex. We propose that young females are subordinate to theirmothers and have to disperse to find a vacant, suitable sitefor reproduction.     

The effect of landscape structure on dispersal distances of the Eurasian red squirrel

Landscape structure can affect dispersal and gene flow in a species. In urban areas, buildings, roads, and small habitat patches make the landscape highly fragmented and can inhibit movement and affect dispersal behavior. Similarly, in rural forested areas, large open areas, such as fields, may act as barriers to movement. We studied how landscape structure affects natal dispersal distances of Eurasian red squirrels (Sciurus vulgaris) in an urban area and a rural area in Finland, by monitoring juvenile red squirrels with radio telemetry. We observed extremely long dispersal distances—up to 16 km—in the rural study area, but shorter distances—on average only half a kilometer—in the urban study area. The landscape structure affected the eventual dispersal paths; in the rural landscape, dispersers favored spruce dominated areas and avoided fields along their dispersal route, although they occasionally even crossed wide fields. In the urban landscape, squirrels preferred areas with deciduous or coniferous trees. The movement steps made by dispersers were longer in the more hostile landscape compared to forested areas. Despite these effects on movement path, the landscape structure only had a minor effect on straight line dispersal distances moved from the natal nest. In other words, individuals moved longer distances and were likely to circumvent barriers in their path, but this did not affect how far they settled from their natal home. This result indicates that, although landscape structure has obvious effects on movement, it still may have only a small effect on other aspects of the population, for example, gene flow.