Phylogenetic diversity is a better predictor of wetland community resistance to Alternanthera philoxeroides invasion than species richness

• Highly biodiversity communities have been shown to better resist plant invasions through complementarity effects. Species richness (SR) is a widely used biodiversity metric but lacks explanatory power when there are only a few species. Communities with low SR can have a wide variety of phylogenetic diversities (PD), which might allow for a better prediction of invasibility.
• We assessed the effect of diversity reduction of a wetland community assemblage typical of the Beijing area on biotic resistance to invasion of the exotic weed Alternanthera philoxeroides and compared the reduction in SR and PD in predicting community invasibility.
• The eight studied resident species performed similarly when grown alone and when grown in eight‐species communities together with the invasive A. philoxeroides. Variation partitioning showed that PD contributed more to variation in both A. philoxeroides traits and community indicators than SR. All A. philoxeroides traits and community indicators, except for evenness index, showed a linear relationship with PD. However, only stem length of A. philoxeroides differed between the one‐ and two‐species treatments, and the diversity index of the communities differed between the one‐ and two‐species treatments and between the one‐ and four‐species treatments.
• Our results showed that in natural or semi‐natural wetlands with relatively low SR, PD may be a better predictor of invasibility than SR. When designing management strategies for mitigating A. philoxeroides invasion, deliberately raising PD is expected to be more efficient than simply increasing species number.

     

Identity between the novel integrin beta 7 subunit and an antigen found highly expressed on intraepithelial lymphocytes in the small intestine.

A cDNA clone encoding the N-terminal sequence of the murine integrin beta 7 subunit, a novel member of the leukocyte cell adhesion molecule subset (Leu-CAM), has been isolated. An N-terminal region of 13 contiguous amino acids deduced from the cDNA shows complete identity with the N-terminus of the 120 kDa subunit of the M290 antigen, a surface molecule found highly expressed on mouse intestinal intraepithelial lymphocytes (IEL). This unexpected result focuses two previously unconnected areas of research and suggests that integrins may have a special role to play in the defence of the gut mucosa.     

Culture media conditioned by wounded cells modify the fibronectin localization pattern of unwounded confluent PtK2 cells

A confluent PtK2 cell sheet was incised in a serum-free culture medium, at 15 min, 2 hr and 24 hr after wounding. The culture media were collected in the same way and used as conditioned media. Unwounded confluent cells were cultured in the conditioned medium for 24 hr. They showed a modification of fibronectin localization similar to that which we had previously observed in wounded confluent PtK2 cells: cells lost their normal fibronectin fibrils and were surrounded by fibronectin lace. This finding suggested that during wound healing, the cells released soluble chemical factors which could modify the fibronectin localization pattern of unwounded confluent cells. Subconfluent cells did not respond to conditioned media, showing that confluent cells and subconfluent cells had different susceptibilities.     

Synthesis and biological evaluation of sulfonylurea and thiourea derivatives substituted with benzenesulfonamide groups as potential hypoglycemic agents

A novel class of sulfonylurea and thiourea derivatives substituted with benzenesulfonamide groups were designed and synthesized. The target compounds were assayed for the effects on the insulin release of isolated rat pancreatic islets and the glucose transport in adipocytes of rats. Some of them exhibited high potency. Compound 10 also had potent antiplatelet activity and showed an excellent property to protect collagen–epinephrine-induced mice mortality as well as plasma glucose-lowering activity in vivo. The preliminary pharmacological profile of compound 10 showed that it might be useful in the treatment of diabetics with cardiovascular and nephropathy complications.     

The positive and negative effects of exotic Spartina alterniflora in China

Spartina alterniflora is a perennial salt marsh grass native to the Atlantic and Gulf Coasts of North America. Recognized for its effects of diminishing strong tide even storms and accelerating sediment deposition, S. alterniflora was introduced into China in 1979. Now the artificial vegetation of Spartina has expanded to around 50 000 h m² along the east coast of China due to its strong capability of propagating by seeds and rhizome fragments. Although it was listed among 16 harmful exotic species in China 3 years ago, we need to evaluate its positive and negative effects in the coastal region of China objectively. This paper reviews some major positive effects of S. alterniflora in China, e.g. being a dominant primary producer, buffering against tides, accelerating accretion and reclamation, absorbing nutrients and digesting pollutants, as well as some major negative effects, e.g. occupying the niche of local species, altering the mudflat habitat, changing and even diminishing biodiversity, and damaging the aquiculture in the tidal land. In addition, its biomaterial uses and biological substitution as a means of ecological regulation is also discussed.     

Identification and comprehensive analysis of the CLV3/ESR‐related (CLE) gene family in Brassica napus L.

• The CLE (CLAVATA3/ESR) gene family, encoding a group of small secretory peptides, plays important roles in cell‐to‐cell communication, thereby controlling a broad spectrum of development processes. The CLE family has been systematically characterized in some plants, but not in Brassica napus.
• In the present study, 116 BnCLE genes were identified in the B. napus genome, including seven unannotated, six incorrectly predicted and five multi‐CLE domain‐encoding genes. These BnCLE members were separated into seven distinct groups based on phylogenetic analysis, which might facilitate the functional characterization of the peptides.
• Further characterization of CLE pre‐propeptides revealed 31 unique CLE peptides from 45 BnCLE genes, which may give rise to distinct roles of BnCLE and expansion of the gene family. The biological activity of these unique CLE dodecamer peptides was tested further through in vitro peptide assays. Variations in several important residues were identified as key contributors to the functional differentiation of BnCLE and expansion of the gene family in B. napus. Expression profile analysis helped to characterize possible functional redundancy and sub‐functionalization among the BnCLE members.
• This study presents a comprehensive overview of the CLE gene family in B. napus and provides a foundation for future evolutionary and functional studies.

     

Contributions of residue 45(CD3) and heme-6-propionate to the biomolecular and geminate recombination reactions of myoglobin

Overall association and dissociation rate constants were measured at 20 degrees C for O2, CO, and alkyl isocyanide binding to position 45 (CD3) mutants of pig and sperm whale myoglobins and to sperm whale myoglobin reconstituted with protoheme IX dimethyl ester. In pig myoglobin, Lys45(CD3) was replaced with Arg, His, Ser, and Glu; in sperm whale myoglobin, Arg45(CD3) was replaced with Ser and Gly. Intramolecular rebinding of NO, O2, and methyl isocyanide to Arg45, Ser45, Glu45, and Lys45(native) pig myoglobins was measured following 35-ps and 17-ns excitation pulses. The shorter, picosecond laser flash was used to examine ligand recombination from photochemically produced contact pairs, and the longer, nanosecond flash was used to measure the rebinding of ligands farther removed from the iron atom. Mutations at position 45 or esterification of the heme did not change significantly (less than or equal to 2-fold) the overall association rate constants for NO, CO, and O2 binding at room temperature. These data demonstrate unequivocally that Lys(Arg)45 makes little contribution to the outer kinetic barrier for the entry of diatomic gases into the distal pocket of myoglobin, a result that contradicts a variety of previous structural and theoretical interpretations. However, the rates of geminate recombination of NO and O2 and the affinity of myoglobin for O2 were dependent upon the basicity of residue 45. The series of substitutions Arg45, Lys45, Ser45, and Glu45 in pig myoglobin led to a 3-fold decrease in the initial rate for the intramolecular, picosecond rebinding of NO and 4-fold decrease in the geminate rate constant for the nanosecond rebinding of O2. (ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma membrane Ca(2+)-pump ATPase is not a substrate for cGMP-dependent protein kinase.

A plasma membrane Ca(2+)-pump ATPase preparation purified from porcine aorta was incubated with cGMP-dependent protein kinase (G-kinase) under the conditions under which dose-dependent stimulation of the enzyme by G-kinase was observed. Several proteins were phosphorylated, but two isoforms of plasma membrane Ca(2+)-pump ATPase with molecular masses of 135- and 145-kDa were not phosphorylated. The protein that was phosphorylated by G-kinase and identified in our previous study as the 135-kDa isoform of Ca(2+)-pump ATPase, on the basis of its almost identical mobility on SDS-PAGE, was found to be another protein with a molecular mass of 138 kDa. Fractionation of the enzyme preparation after incubation with G-kinase by a newly developed calmodulin affinity chromatographic method resulted in the separation of all the G-kinase substrates from the two isoforms of plasma membrane Ca(2+)-pump ATPase. These results suggest that the direct phosphorylation of the Ca(2+)-pump ATPase does not occur in association with the stimulation of the plasma membrane Ca(2+)-pump ATPase by G-kinase.     

Investigating the role of Aurora kinases in RAS signaling

Activating ras mutations are frequently found in malignant tumors of the pancreas, colon, lung and other tissues. RAS activates a number of downstream pathways that ultimately cause cellular transformation. Several recent studies suggested that one of those pathways involves Aurora kinases. Overexpression of Aurora‐B kinase can augment transformation by oncogenic RAS, however the mechanism was not determined. The cooperative effect of high levels of Aurora kinase is important since this kinase is frequently overexpressed in human tumors. We have used two Aurora kinase inhibitors to test their effect on RAS signaling. We find that these inhibitors have no effect on the phosphorylation of MEK1/2 or MAPK in response to RAS. Furthermore, inhibiting Aurora kinases in human cancer cells with or without activated RAS did not change the length of the cell cycle nor induce apoptosis suggesting that these kinases do not play a direct role in these key cellular responses to activated RAS. Overexpression of Aurora B can cause cells to become polyploid. Also, inducing polyploidy with cytochalasin D was reported to induce neoplastic transformation, suggesting that Aurora overexpression may cooperate with RAS indirectly by inducing polyploidy. We find that inducing polyploidy with cytochalasin D or blebbistatin does not enhance transformation by oncogenic RAS. Our observations argue against a direct role for Aurora kinases in the RAS‐MAPK pathway, and suggest that the polyploid state does not enhance transformation by RAS. J. Cell. Biochem. 106: 33–41, 2009. © 2008 Wiley‐Liss, Inc.