Life on the edge: rare and restricted episodes of a pan-tropical mutualism adapting to drier climates

? The fig tree-fig wasp obligate pollination mutualism has strong ancestral affinities with tropical communities, but is present in much drier contemporary biomes, especially at higher latitudes at the edge of their range. The extent to which adaptation to environmental variables is evolutionarily conserved and whether environmental differences function in ecological speciation of the mutualism are unknown. ? Here we use climate models and phylogenetic reconstructions to test whether the Ficus-fig wasp mutualism has adapted and radiated into drier climates and led to ecological speciation in both plant and insect. ? The results showed phylogenetic correspondence between closely related Ficus species with either savanna, forest, or riparian habitat categories, were most strongly explained by both climate and environmental variables. Rare episodes of adaptation to dry apotypic conditions have resulted in substantial radiations into savanna. ? Inferences were consistent with predictions of niche conservatism and support the postulate that ecological speciation of the mutualism occurs, but under contrasting and intertwined circumstances among plant-pollinator adaptation and tolerance to the environment.     

Isolation and characterization of a benzoylformate decarboxylase and a NAD/NADP-dependent benzaldehyde dehydrogenase involved in d-phenylglycine metabolism in Pseudomonas stutzeri ST-201

Following induction with d-phenylglycine both d-phenylglycine aminotransferase activity and benzoylformate decarboxylase activity were observed in cultures of Pseudomonas stutzeri ST-201. Induction with benzoylformate, on the other hand, induced only benzoylformate decarboxylase activity. Purification of the benzoylformate decarboxylase, followed by N-terminal sequencing, enabled the design of probes for hybridization with P. stutzeri ST-201 genomic DNA libraries. Sequencing of two overlapping genomic DNA restriction fragments revealed two open reading frames which were denoted dpgB and dpgC. Sequence alignments suggested that the genes encoded a thiamin-diphosphate-dependent decarboxylase and an aldehyde dehydrogenase, respectively. Both genes were isolated and expressed in Escherichia coli. The dpgB gene product was confirmed as a benzoylformate decarboxylase while the dpgC gene product was characterized as a NAD⁺/NADP⁺-dependent benzaldehyde dehydrogenase. In keeping with their high sequence identities (both greater than 85%) the kinetic properties of the two enzymes were similar to those of the homologous enzymes in the mandelate pathway of Pseudomonas putida ATCC 12633. However, Pseudomonas stutzeri ST-201 was unable to grow on either isomer of mandelate, and sequencing indicated that the dpgB gene did not form part of an operon. Thus it appears that the two enzymes form part of a d-phenylglycine, rather than mandelate, degrading pathway.     

Application of proteomics to neutrophil biology

Polymorphonuclear leukocytes or neutrophils are a primary effector cell of the innate immune system and contribute to the development of adaptive immunity. Neutrophils participate in both the initiation and resolution of inflammatory responses through a series of highly coordinated molecular and phenotypic changes. To accomplish these changes, neutrophils express numerous receptors and use multiple overlapping and redundant signal transduction pathways. Dysregulation of the activation or resolution pathways plays a role in a number of human diseases. A comprehensive understanding of the regulation of neutrophil responses can be provided by high throughput proteomic technologies and sophisticated computational analysis. The first steps in the application of proteomics to understanding neutrophil biology have been taken. Here we review the application of expression, structural, and functional proteomic studies to neutrophils. Although defining the complex molecular events associated with neutrophil activation is in the early stages, the data generated to date suggest that proteomic technologies will dramatically enhance our understanding of neutrophil biology.     

Inbreeding ancestors: the role of sibmating in the social evolution of gall thrips

We used microsatellite data to estimate levels of inbreeding in four species of solitary gall thrips that are in the same clade as the six species with soldier castes. Three of the four species were highly inbred (Fis 0.54-0.68), and the other apparently mated randomly (Fis near zero). These estimates, combined with previous data from species with soldiers, suggest that inbreeding is a pervasive life-history feature of the gall-inducing thrips on Australian Acacia. Mapping of inbreeding estimates onto the phylogeny of the gall inducers showed that the ancestral lineage that gave rise to soldiers was apparently highly inbred, and therefore, inbreeding could have played a role in the origin of sociality within this group. Moreover, there was a trend from high levels of inbreeding at the origin of soldiers to low levels in the most derived species with soldiers, which exhibits the highest levels of reproductive division of labor and soldier altruism. These patterns are consistent with considerations from population genetics, which show that the likelihood of the origin of soldier altruism is higher in inbreeding populations but that, once soldiers have evolved, a reduction in inbreeding levels may facilitate the evolution of enhanced division of labor and reproductive skew.     

Identification of multiple integrin β1 homologs in zebrafish (Danio rerio)

Background  

Integrins comprise a large family of α,β heterodimeric, transmembrane cell adhesion receptors that mediate diverse essential biological functions. Higher vertebrates possess a single β1 gene, and the β1 subunit associates with a large number of α subunits to form the major class of extracellular matrix (ECM) receptors. Despite the fact that the zebrafish (Danio rerio) is a rapidly emerging model organism of choice for developmental biology and for models of human disease, little is currently known about β1 integrin sequences and functions in this organism.     

p38 Kinase-dependent MAPKAPK-2 activation functions as 3-phosphoinositide-dependent kinase-2 for Akt in human neutrophils

Akt activation requires phosphorylation of Thr(308) and Ser(473) by 3-phosphoinositide-dependent kinase-1 and 2 (PDK1 and PDK2), respectively. While PDK1 has been cloned and sequenced, PDK2 has yet to be identified. The present study shows that phosphatidylinositol 3-kinase-dependent p38 kinase activation regulates Akt phosphorylation and activity in human neutrophils. Inhibition of p38 kinase activity with SB203580 inhibited Akt Ser(473) phosphorylation following neutrophil stimulation with formyl-methionyl-leucyl-phenylalanine, FcgammaR cross-linking, or phosphatidylinositol 3,4,5-trisphosphate. Concentration inhibition studies showed that Ser(473) phosphorylation was inhibited by 0.3 microm SB203580, while inhibition of Thr(308) phosphorylation required 10 microm SB203580. Transient transfection of HEK293 cells with adenoviruses containing constitutively active MKK3 or MKK6 resulted in activation of both p38 kinase and Akt. Immunoprecipitation and glutathione S-transferase (GST) pull-down studies showed that Akt was associated with p38 kinase, MK2, and Hsp27 in neutrophils, and Hsp27 dissociated from the complex upon activation. Active recombinant MK2 phosphorylated recombinant Akt and Akt in anti-Akt, anti-MK2, anti-p38, and anti-Hsp27 immunoprecipitates, and this was inhibited by an MK2 inhibitory peptide. We conclude that Akt exists in a signaling complex containing p38 kinase, MK2, and Hsp27 and that p38-dependent MK2 activation functions as PDK2 in human neutrophils.