Influence of Phytase Transgenic Corn on the Intestinal Microflora and the Fate of Transgenic DNA and Protein in Digesta and Tissues of Broilers

An experiment was conducted to investigate the effect of phytase transgenic corn (PTC) on intestinal microflora, and the fate of transgenic DNA and protein in the digesta and tissues of broilers. A total of 160 1-day-old Arbor Acres commercial male broilers were randomly assigned to 20 cages (8 chicks per cage) with 10 cages (replicates) for each treatment. Birds were fed with a diet containing either PTC (54.0% during 1–21 days and 61.0% during 22–42 days) or non-transgenic isogenic control corn (CC) for a duration of 42 days. There were no significant differences (P>0.05) between birds fed with the PTC diets and those fed with the CC diets in the quantities of aerobic bacteria, anaerobic bacteria, colibacillus and lactobacilli, or microbial diversities in the contents of ileum and cecum. Transgenic phyA2 DNA was not detected, but phyA2 protein was detected in the digesta of duodenum and jejunum of broilers fed with the PTC diets. Both transgenic phyA2 DNA and protein fragments were not found in the digesta of the ileum and rectum, heart, liver, kidney, and breast or thigh muscles of broilers fed with the PTC diets. It was concluded that PTC had no adverse effect on the quantity and diversity of gut microorganisms; Transgenic phyA2 DNA or protein was rapidly degraded in the intestinal tract and was not transferred to the tissues of broilers.     

Growth form and distribution of introduced plants in their native and non-native ranges in Eastern Asia and North America

There is a growing interest in understanding the influence of plant traits on their ability to spread in non-native regions. Many studies addressing this issue have been based on relatively small areas or restricted taxonomic groups. Here, we analyse a large data base involving 1567 plant species introduced between Eastern Asia and North America or from elsewhere to both regions. We related the extent of species distributions in each region to growth form and the distinction between upland and wetland habitats. We identified significant relationships between geographical distribution and plant traits in both native and exotic ranges as well as regional differences in the relationships. Range size was larger for herbaceous graminoids and forbs, especially annuals compared to perennials, than for woody species, and range size also was larger for plants of wetland compared to upland habitats. Distributions were more extensive in North America than in Eastern Asia, although native plants from both regions had broader distributions than non-natives, with exotics from elsewhere intermediate. Growth form and environment explained more of the variance in distribution of plants in North America than in Eastern Asia. The influence of growth form and habitat on distribution suggests that these traits might be related to tolerance of ecological conditions. In addition, the smaller extents of species in non-native compared to native areas suggest roles for dispersal limitation and adaptation to region-specific ecological conditions in determining distribution.     

Soluble expression and purification of Brucella cell surface protein (BCSP31) of Brucella melitensis and preparation of anti-BCSP31 monoclonal antibodies

Brucella cell surface protein (BCSP31) is potentially useful for diagnosing brucellosis. We aimed to establish a monoclonal antibody (MAb) against Brucella melitensis BCSP31 and to investigate its distribution in diagnosis. Soluble recombinant BCSP31 was successfully expressed and purified. Two MAbs (1F1 and 1E5) against B. melitensis BCSP31, effective in detecting both recombinant and cellular proteins, were obtained and characterized. The MAbs did not react with Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Mycobacterium tuberculosis, or Bacillus aeruginosus, but strongly reacted with BCSP31 and B. melitensis by ELISA and Western blot analysis. We also tested different Brucella species and brucellosis using the prepared anti-BCSP31 MAbs. BCSP31 and anti-BCSP31 MAbs may play important roles in future research in diagnosing brucellosis.     

Direct Regulation of Osteocytic Connexin 43 Hemichannels through AKT Kinase Activated by Mechanical Stimulation

Connexin (Cx) 43 hemichannels in osteocytes are thought to play a critical role in releasing bone modulators in response to mechanical loading, a process important for bone formation and remodeling. However, the underlying mechanism that regulates the opening of mechanosensitive hemichannels is largely unknown. We have recently shown that Cx43 and integrin α5 interact directly with each other, and activation of PI3K appears to be required for Cx43 hemichannel opening by mechanical stimulation. Here, we show that mechanical loading through fluid flow shear stress (FFSS) increased the level of active AKT, a downstream effector of PI3K, which is correlated with the opening of hemichannels. Both Cx43 and integrin α5 are directly phosphorylated by AKT. Inhibition of AKT activation significantly reduced FFSS-induced opening of hemichannels and disrupted the interaction between Cx43 and integrin α5. Moreover, AKT phosphorylation on Cx43 and integrin α5 enhanced their interaction. In contrast to the C terminus of wild-type Cx43, overexpression of the C-terminal mutant containing S373A, a consensus site previously shown to be phosphorylated by AKT, failed to bind with α5 and hence could not inhibit hemichannel opening. Together, our results suggest that AKT activated by FFSS directly phosphorylates Cx43 and integrin α5, and Ser-373 of Cx43 plays a predominant role in mediating the interaction between these two proteins and Cx43 hemichannel opening, a crucial step to mediate the anabolic function of mechanical loading in the bone.     

Cell Elasticity Is Regulated by the Tropomyosin Isoform Composition of the Actin Cytoskeleton

The actin cytoskeleton is the primary polymer system within cells responsible for regulating cellular stiffness. While various actin binding proteins regulate the organization and dynamics of the actin cytoskeleton, the proteins responsible for regulating the mechanical properties of cells are still not fully understood. In the present study, we have addressed the significance of the actin associated protein, tropomyosin (Tpm), in influencing the mechanical properties of cells. Tpms belong to a multi-gene family that form a co-polymer with actin filaments and differentially regulate actin filament stability, function and organization. Tpm isoform expression is highly regulated and together with the ability to sort to specific intracellular sites, result in the generation of distinct Tpm isoform-containing actin filament populations. Nanomechanical measurements conducted with an Atomic Force Microscope using indentation in Peak Force Tapping in indentation/ramping mode, demonstrated that Tpm impacts on cell stiffness and the observed effect occurred in a Tpm isoform-specific manner. Quantitative analysis of the cellular filamentous actin (F-actin) pool conducted both biochemically and with the use of a linear detection algorithm to evaluate actin structures revealed that an altered F-actin pool does not absolutely predict changes in cell stiffness. Inhibition of non-muscle myosin II revealed that intracellular tension generated by myosin II is required for the observed increase in cell stiffness. Lastly, we show that the observed increase in cell stiffness is partially recapitulated in vivo as detected in epididymal fat pads isolated from a Tpm3.1 transgenic mouse line. Together these data are consistent with a role for Tpm in regulating cell stiffness via the generation of specific populations of Tpm isoform-containing actin filaments.