Extensive variation in synonymous substitution rates in mitochondrial genes of seed plants

Background  

It has long been known that rates of synonymous substitutions are unusually low in mitochondrial genes of flowering and other land plants. Although two dramatic exceptions to this pattern have recently been reported, it is unclear how often major increases in substitution rates occur during plant mitochondrial evolution and what the overall magnitude of substitution rate variation is across plants.     

How propagule size and environmental suitability jointly determine establishment success: a test using dung beetle introductions

Both the size of founding populations (propagule size) and environmental suitability are known to influence whether a species newly introduced to a location will establish a self-sustaining population. However, these two factors do not operate independently: it is the interaction between propagule size and environmental suitability that determines the probability an introduced population will establish. Here I use the example of dung beetle introductions to Australia to illustrate the importance of this interaction. I first describe equations that model establishment success jointly as a function of propagule size and environmental suitability. I then show how these equations provide insight into the different outcomes observed in two dung beetle species widely introduced to Australia. In one species, variation in propagule size had relatively little influence on establishment success due to large variation in environmental suitability, leading to an essentially bimodal outcome: sites were either very suitable for establishment and introductions succeeded, or sites were unsuitable and introductions failed regardless of propagule size. For the second species, there was much less variation among locations in environmental suitability, leading to propagule size having a strong influence on establishment success. These examples highlight how the interplay between environmental suitability and founding population size is central to determining the probability an introduced species will establish.     

The role of humans in the diversification of a threatened island raptor

Background  

Anthropogenic habitat modifications have led to the extinction of many species and have favoured the expansion of others. Nonetheless, the possible role of humans as a diversifying force in vertebrate evolution has rarely been considered, especially for species with long generation times. We examine the influence that humans have had on the colonization and phenotypic and genetic differentiation of an insular population of a long-lived raptor species, the Egyptian vulture (Neophron percnopterus).     

Immunohistochemical Identification of Met-Enkephalin in Digestive System and Its Effect on Digestive Enzyme Activities of the Scallop <Emphasis Type="Italic">Chlamys farreri</Emphasis>

The study was designed to determine whether methionine-enkephalin (M-ENK) was present in the digestive system of the scallop Chlamys farreri and investigate the effects of M-ENK on the activity of amylase, protease and lipase in the digestive system of C. farreri. The results indicated that M-ENK-like material was present in the epithelium and connective tissue of labial palps, mouth labia, stomach, intestine, rectum, and hepatopancreas of the scallop C. farreri. Moreover, it was also found that many isolated small cells showing M-ENK-like immunoreactivity were scattered in the epithelial layer of intestine, and many isolated big epithelial cells showing M-ENK-like immunoreactivity were scattered in tubules of hepatopancreas of the scallop. The activity levels of amylase and lipase in crystalline style, hepatopancreas and intestine were enhanced at 1 h after injection of exogenous M-ENK into adductor muscle of the scallops, whereas protease activity levels were significantly suppressed. Our report constitutes the first characterization of M-ENK in the digestive system of scallop C. farreri and investigates the effects of M-ENK on the activities of digestive enzymes of mollusk for the first time. The results suggest an involvement of M-ENK in the functional regulation of the digestive system of C. farreri.     

Electronic properties of neuroleptics: ionization energies of benzodiazepines

Vertical ionization energies (VIEs) of medazepam, nordazepam and their molecular subunits have been calculated using the electron propagator method in the P3/CEP-31G* approximation. Vertical electron affinities (VEAs) have been obtained with a ∆SCF procedure at the DFT-B3LYP/6-31+G* level of theory. Excellent correlations have been achieved between IE_calc and IE_exp, allowing reliable assignment of the ionization processes. Our proposed assignment differs in many instances from that previously reported in the literature. The electronic structure of the frontier Dyson orbitals shows that the IE and EA values of the benzodiazepines can be modulated by substitution at the benzene rings. Hardness values, evaluated as (IE − EA)/2, follow the trend of the experimental singlet transition energies. Medazepam is a less hard (i.e., less stable) compound than nordazepam.     

Comparison Study of Bone Defect Healing Effect of Raw and Processed Pyritum in Rats

To evaluate and compare the effect of raw and processed pyritum on tibial defect healing, 32 male Sprague Dawley rats were randomly divided into four groups. After tibial defect, animals were produced and grouped: sham and control group were orally administrated with distilled water (1 mL/100 g), while treatment groups were given aqueous extracts of raw and processed pyritum (1.5 g/kg) for successive 42 days. Radiographic examination showed that bone defect healing effect of the treatment groups was obviously superior compared to that of the control group. Bone mineral density of whole tibia was increased significantly after treating with pyritum. Inductively coupled plasma-optical emission spectrometry showed that the contents of Ca, P, and Mg in callus significantly increased in the treatment groups comparing with the control. Moreover, serological analysis showed that the concentration of serum phosphorus of the treatment groups significantly increased compared with that of the control group. By in vitro study, we have evaluated the effects of drug-containing serum of raw and processed pyritum on osteoblasts. It was manifested that both the drug-containing sera of raw and processed pyritum significantly increased the mRNA levels of alkaline phosphatase and collagen type I. Protein levels of phosphorylated Smad2/3 also increased. The mRNA levels of osteocalcin and transforming growth factor β (TGF-β) type I and II receptors, as well as the protein levels of TGF-β1 in the processed groups, were higher than those in the control. In summary, both raw and processed pyritum-containing sera exhibited positive effects on osteoblasts, which maybe via the TGF-β1/Smad signaling pathway. Notably, the tibia defect healing effect of pyritum was significantly enhanced after processing.     

Biomedical implications from a morphoelastic continuum model for the simulation of contracture formation in skin grafts that cover excised burns

A continuum hypothesis-based model is developed for the simulation of the (long term) contraction of skin grafts that cover excised burns in order to obtain suggestions regarding the ideal length of splinting therapy and when to start with this therapy such that the therapy is effective optimally. Tissue is modeled as an isotropic, heterogeneous, morphoelastic solid. With respect to the constituents of the tissue, we selected the following constituents as primary model components: fibroblasts, myofibroblasts, collagen molecules, and a generic signaling molecule. Good agreement is demonstrated with respect to the evolution over time of the surface area of unmeshed skin grafts that cover excised burns between outcomes of computer simulations obtained in this study and scar assessment data gathered previously in a clinical study. Based on the simulation results, we suggest that the optimal point in time to start with splinting therapy is directly after placement of the skin graft on its recipient bed. Furthermore, we suggest that it is desirable to continue with splinting therapy until the concentration of the signaling molecules in the grafted area has become negligible such that the formation of contractures can be prevented. We conclude this study with a presentation of some alternative ideas on how to diminish the degree of contracture formation that are not based on a mechanical intervention, and a discussion about how the presented model can be adjusted.