Effects of flowering tree density on the mating system and gene flow in Shorea leprosula (Dipterocarpaceae) in Peninsular Malaysia

Pristine tropical rainforests in Southeast Asia have rich species diversity and are important habitats for many plant species. However, the extent of these forests has declined in recent decades and they have become fragmented due to human activities. These developments may reduce the genetic diversity of species within them and, consequently, the species’ ability to adapt to environmental changes. Our objective in the study presented here was to clarify the effect of tree density on the genetic diversity and gene flow patterns of Shorea leprosula Miq. populations in Peninsular Malaysia. For this purpose, we related genetic diversity and pollen flow parameters of seedling populations in study plots to the density of mature trees in their vicinity. The results show that gene diversity and allelic richness were not significantly correlated to the mature tree density. However, the number of rare alleles among the seedlings and the selfing rates of the mother trees were negatively correlated with the density of the adult trees. Furthermore, in a population with high mature tree density pollination distances were frequently <200 m, but in populations with low adult tree density the distances were longer. These findings suggest that the density of flowering trees affects selfing rates, gene flow and, thus, the genetic diversity of S. leprosula populations. We also found an individual S. leprosula tree with a unique reproductive system, probably apomictic, mating system.     

LIM domain protein FHL1B interacts with PP2A catalytic β subunit--a novel cell cycle regulatory pathway

Four-and-a-half LIM domain protein 1B (FHL1B) is an alternatively-spliced isoform of FHL1. In this study, FHL1B was demonstrated to interact with the β catalytic subunit (Cβ) of a type 2A protein phosphatase (PP2A) by yeast two-hybrid screening. Domain studies using a small-scale yeast two-hybrid interaction assay revealed the mediation of protein-protein interaction by FHL1B’s C-terminus. Interaction between FHL1B and PP2A was further verified by co-immunoprecipitation. FHL1B was also shown to shuttle between nucleus and cytoplasm at different phases of the cell cycle. These data suggest that the FHL1B/PP2A_Cβ interaction may illustrate a novel cell-cycle regulatory pathway.

Structured summary

MINT-8044739: FHL1B (uniprotkb:Q13642-2) physically interacts (MI:0915) with PP2Acbeta (uniprotkb:P62714) by two hybrid (MI:0018)MINT-8044769, MINT-8044778: FHL1B (uniprotkb:Q13642-2) physically interacts (MI:0915) with PP2Acbeta (uniprotkb:P62714) by anti bait coimmunoprecipitation (MI:0006)     

Surface Temperature Distribution of a Breast With and Without Tumour

Breast cancer is a common and dreadful disease in women. Regular screening helps in its early detection. At present the most common methods of screening are by self examination and mammography. The surface temperature distribution of the breast can also provide some information on the presence of tumour. This distribution has a relation to the size and location of tumour and can be seen using thermography, where the infrared radiation emitted from the surface of the breast is recorded and a thermal pattern obtained. Thermography is a non-invasive and an inexpensive tool which could be used for early detection. In order to simulate the surface temperature distribution, a two-dimensional model of female breast with and without a carcinoma is considered. The breast is modelled with varying layer thickness close to the actual shape and numerically solved using finite element analysis. Temperature profiles are obtained for a normal breast and for a malignant one by varying the tumour size, location and the blood flow rates. The results show that the surface temperature for a malignant breast is higher than that of a normal one. In addition the size and location of the tumour do have an effect on the surface temperature distribution. It can also be seen that tumour of different sizes placed at the same location would yield the same maximum temperature depending on the blood perfusion rate.     

Heterogeneity of the mechanical properties of demineralized bone

Knowledge of the mechanical properties of the collagenous component of bone is required for composite modeling of bone tissue and for understanding the age- and disease-related reductions in the ductility and strength of bone. The overall goal of this study was to investigate the heterogeneity of the mechanical properties of demineralized bone which remains unexplained and may be due to differences in the collagen structure or organization or in experimental protocols. Uniaxial tension tests were conducted to measure the elastic and failure properties of demineralized human femoral (n = 10) and tibial (n = 13) and bovine humeral (n = 8) and tibial (n = 8) cortical bone. Elastic modulus differed between groups (p = 0.02), varying from 275 +/- 94 MPa (mean +/- SD) to 450 + 50 MPa. Similarly, ultimate stress varied across groups from 15 + 4.2 to 26 + 4.7 MPa (p = 0.03). No significant differences in strain-to-failure were observed between any groups in this study (pooled mean of 8.4 +/- 1.6%; p = 0.42). However, Bowman et al. (1996) reported an average ultimate strain of 12.3 +/- 0.5% for demineralized bovine humeral bone, nearly 40% higher than our value. Taken together, it follows that all the monotonic mechanical properties of demineralized bone can display substantial heterogeneity. Future studies directed at explaining such differences may therefore provide insight into aging and disease of bone tissue.     

Molecular dynamics simulations of beta-hairpin folding

Molecular dynamics simulations of beta-hairpin folding have been carried out with a solvent-referenced potential at 274 K. The model peptide V4DPGV4 formed stable beta-hairpin conformations and the beta-hairpin ratio calculated by the DSSP algorithm was about 56% in the 50-ns simulation. Folding into beta-hairpin conformations is independent of the initial conformations. The simulations provided insights into the folding mechanism. The hydrogen bond often formed in a beta-turn first, and then propagated by forming more hydrogen bonds along the strands. Unfolding and refolding occurred repeatedly during the simulations. Both the hydrogen bonding and the hydrophobic interaction played important roles in forming the ordered structure. Without the hydrophobic effect, stable beta-hairpin conformations did not form in the simulations. With the same energy functions, the alanine-based peptide (AAQAA)3Y folded into helical conformations, in agreement with experiments. Folding into an alpha-helix or a beta-hairpin is amino acid sequence-dependent.