We present a study of fine-scale spatial genetic structure (SGS) and assess the impact of seed and pollen dispersal on the pattern of genetic diversity in the predominantly selfing Hordeum spontaneum. The study included (1) direct measurement of dispersal in a controlled environment, and (2) analyses of SGS and estimation of the ratio of pollen to seed flow in three natural populations sampled in linear transects at fixed increasing inter-plant distances. Analysis of SGS with 10 nuclear SSRs showed in all three populations a significant autocorrelation for the distance classes of 1 or 2 m and a negative linear relationship between kinship coefficients, calculated for pairs of individuals, and logarithm of geographical distance between members of the pairs. Major seed dispersal (95%) was found to be within 1.2 m from the mother plant. Pollen flow, estimated from the comparison of nuclear and chloroplast variation, was spatially limited as much as was seed dispersal, and tended to be overestimated when measured at spatial scales exceeding that of SGS. We conclude that combined effects of selfing, occasional outcrossing, localized seed dispersal and high plant density create an equilibrium between drift and gene flow in this species resulting in SGS at a very fine spatial scale.

Populations of predominantly selfing plant species often show spatial genetic structure but little is known whether epistatic gene interactions are spatially structured. To detect a possible epistatic effect and a spatial scale at which it operates, we created artificial crosses between plants spanning a range of fixed distances from 1 to 400 m in three populations of wild barley. The self-pollinated and crossed progeny (F 1 ) and two generations of segregated progeny (F 2 and F 3 ) were tested in experimentally simulated population environments for relative performance (RP). The measured fitness traits included number of seeds, total seed weight and seed germination. For any of these traits, there was no association between RP of F 1 , F 2 and F 3 plants and either pairwise kinship coefficients or crossing distance. In contrast, in all three populations, we found lower seed viability of outcrossed as compared with self-pollinated genotypes in the first generation of segregation. However, in the F 3 generation this outbreeding effect disappeared in the two populations and greatly decreased in the third population. For seed production, heterosis in F 1 and outbreeding depression in F 2 were observed only in the population with unusually high number of heterozygotes. Our findings support the view that in selfing species a spatial mosaic of various locally abundant genotypes represents not randomly fixed combinations of alleles but the co-adapted gene complexes that were sieved by selection, while heterozygotes are characteristic for the transient phase of this process, when segregation and purging of maladaptive genotypes have not yet occurred.

One clone (M-2), out of several Agrobacterium rhizogenes transformed root clones of Cistus incanus, formed ecto- or endomycorrhiza in vitro with two isolates of Terfezia boudieri collected in Israel. All other clone-fungal isolate combinations formed ectomycorrhiza. The endomycorrhiza-forming isolate secreted smaller amounts of auxin than an ectomycorrhiza-forming isolate. Addition of 2,4-dichlorophenoxyacetic acid (2,4-D) led to ectomycorrhiza formation by the M-2 clone on low P medium. Endomycorrhizas were formed by both M-2 and a control clone with the same T. boudieri isolates on high P medium with 2,4-D. The M-2 clone of C. incanus exhibited greater sensitivity to exogenous auxins (IAA and 2,4-D) than other clones, and clonal sensitivity to auxin was increased tenfold under low P conditions. Results are discussed in relation to phosphate and auxin influence on T. boudieri-C. incanus interaction.

The structure and connectivity of protein-protein interaction (PPI) networks are maintained throughout evolution by coordinated changes (coevolution) of network proteins. Despite extensive research, relatively little is known regarding the molecular basis and functional implications of the coevolution of PPI networks. Here, we used proliferating cell nuclear antigen, a hub protein that mediates DNA replication and repair in eukaryotes, as a model system to study the coevolution of PPI networks in fungi. Using a combined bioinformatics and experimental approach, we discovered that PCNA-partner interactions tightly coevolved in fungal species, leading to specific modes of recognition. We found that fungal proliferating cell nuclear antigen-partner interaction networks diverged into two distinct groups as a result of such coevolution and that hybrid networks of these groups are functionally noncompatible in Saccharomyces cerevisiae. Our results indicate that the coevolution of PPI networks can form functional barriers between fungal species, and thus can promote and fix speciation.interdomain connecting loop | yeast two hybrid | directed evolution P rotein-protein interaction (PPI) networks play vital roles in executing almost all essential biological processes. The availability of sequencing data, as well as high-throughput experimental approaches to identify and generate comprehensive maps of PPIs, has enabled the development of a network-based view of biological processes (1, 2). Such networks are composed of ensembles of proteins that act together in a coordinated manner to execute a variety of essential biological processes, such as DNA replication, transcription, and signal transduction. In many cases, such networks are modular and contain highly connected proteins, termed "hub proteins," that can regulate a given biological process by switching partners with high spatial and temporal resolution (3).Many PPI networks are conserved over evolutionary time scales to promote a variety of biological processes in different organisms (4). One mechanism to maintain network structure and connectivity throughout evolution involves the coevolution of interacting proteins through coordinated changes in protein-protein interfaces (5). The coevolution of interacting proteins can form reproductive barriers between organisms as a result of hybrid network incompatibility, and thus can be an important driving force in promoting and fixing speciation. Currently, the study of coevolution of PPI networks is extremely challenging because of difficulties in identifying and characterizing coordinated sequence changes in network proteins during natural evolution. Even if such sequence changes are detected, their functional implications are difficult to predict. Thus, relatively little is known overall regarding the dynamics and functional importance of the coevolution of hubpartner interactions across different species.In eukaryotes, DNA replication and repair processes are mediated by proliferating cell nuclear antigen (PCNA) throug...

Interleukin-17 (IL-17) is a T-cell-derived cytokine that promotes inflammatory pathology in autoimmune diseases. Blocking IL-17A interactions with its endogenous IL-17 receptor (IL-17RA) can constitute an important target for therapeutic intervention. Here, we utilized a directed evolution approach to generate soluble IL-17RA mutants that exhibit increased IL-17A binding affinity and thermostability, relative to the wild-type. Human fibroblast cell-based assay and in vivo analysis in mice indicated that two improved IL-17RA mutants efficiently inhibit the secretion of IL-17A-induced proinflammatory cytokines. Analysis of one of these mutants in a psoriasis mouse model showed its efficacy in promoting the recovery of psoriasis plaques. This mutant can be used as a promising drug candidate for the treatment of psoriasis and may be a therapeutic agent for various other autoimmune diseases.

Although Halobacterium salinarum provided the first example of N-glycosylation outside the Eukarya, much regarding such post-translational modification in this halophilic Archaea remains either unclear or unknown. The composition of an N-linked glycan decorating both the S-layer glycoprotein and archaellins offers one such example. Originally described some 40 years ago, reports from that time on have presented conflicted findings regarding the composition of this glycan, as well as differences between the protein-bound glycan and that version of the glycan attached to the lipid upon which it is assembled. To clarify these points, liquid chromatography-electrospray ionization mass spectrometry was employed here to revisit the composition of this glycan both when attached to selected asparagine residues of target proteins and when bound to the lipid dolichol phosphate upon which the glycan is assembled. Such efforts revealed the N-linked glycan as corresponding to a tetrasacchride comprising a hexose, a sulfated hexuronic acid, a hexuronic acid and a second sulfated hexuronic acid. When attached to dolichol phosphate but not to proteins, the same tetrasaccharide is methylated on the final sugar. Moreover, in the absence of the oligosaccharyltransferase AglB, there is an accumulation of the dolichol phosphate-linked methylated and disulfated tetrasacchride. Knowing the composition of this glycan at both the lipid- and protein-bound stages, together with the availability of gene deletion approaches for manipulating Halobacterium salinarum, will allow delineation of the N-glycosylation pathway in this organism.

Summary• Changes in gene expression by isolates of Terfezia boudieri during mycorrhization with Cistus incanus hairy roots were followed.• Four fungus-hairy root clone combinations were cultivated under two sets of conditions, in which the root and the fungus were separated by a cellophane sheet or were allowed physical contact. One of the combinations produced endomycorrhizas, the other three solely ectomycorrhizas. Fragments isolated by cDNA-AFLP analysis from cellophane-separated cultures (preinfection) were used to identify differentially expressed genes by reverse Northern analysis.• Genes showing no homology to known sequences constituted the largest group under both growth conditions. Some fungal genes were expressed transiently, while others exhibited altered expression patterns as conditions changed from individually growing through the preinfection stage to mycorrhizas. Genes expressed exclusively under combinations allowing either ectomycorrhiza or endomycorrhiza under a particular condition were detected.• Our results point, for the first time, to some of the genes that might be involved in determining the type of association that will be formed: ecto-or endomycorrhiza.

N-glycosylation is a post-translational modification that occurs in all three domains. In Archaea, however, N-linked glycans present a degree of compositional diversity not observed in either Eukarya or Bacteria. As such, it is surprising that nonulosonic acids (NulOs), nine-carbon sugars that include sialic acids, pseudaminic acids, and legionaminic acids, are routinely detected as components of protein-linked glycans in Eukarya and Bacteria but not in Archaea. In the following, we report that the N-linked glycan attached to the S-layer glycoprotein of the haloarchaea Halorubrum sp. PV6 includes an N-formylated legionaminic acid. Analysis of the Halorubrum sp. PV6 genome led to the identification of sequences predicted to comprise the legionaminic acid biosynthesis pathway. The transcription of pathway genes was confirmed, as was the co-transcription of several of these genes. In addition, the activities of LegI, which catalyzes the condensation of 2,4-di-N-acetyl-6-deoxymannose and phosphoenolpyruvate to generate legionaminic acid, and LegF, which catalyzes the addition of cytidine monophosphate (CMP) to legionaminic acid, both heterologously expressed in Haloferax volcanii, were demonstrated. Further genome analysis predicts that the genes encoding enzymes of the legionaminic acid biosynthetic pathway are clustered together with sequences seemingly encoding components of the N-glycosylation pathway in this organism. In defining the first example of a legionaminic acid biosynthesis pathway in Archaea, the findings reported here expand our insight into archaeal N-glycosylation, an almost universal post-translational modification in this domain of life.