No abstract

Species of the Bos genus, including taurine cattle, zebu, gayal, gaur, banteng, yak, wisent and bison, have been domesticated at least four times and have been an important source of meat, milk and power for many human cultures. We sequence the genomes of gayal, gaur, banteng, wisent and bison, and provide population genomic sequencing of an additional 98 individuals. We use these data to determine the phylogeny and evolutionary history of these species and show that the threatened gayal is an independent species or subspecies. We show that there has been pronounced introgression among different members of this genus, and that it in many cases has involved genes of considerable adaptive importance. For example, genes under domestication selection in cattle (for example, MITF) were introgressed from domestic cattle to yak. Also, genes in the response-to-hypoxia pathway (for example, EGLN1, EGLN2 and HIF3a) have been introgressed from yak to Tibetan cattle, probably facilitating their adaptation to high altitude. We also validate that there is an association between the introgressed EGLN1 allele and haemoglobin and red blood cell concentration. Our results illustrate the importance of introgression as a source of adaptive variation and during domestication, and suggest that the Bos genus evolves as a complex of genetically interconnected species with shared evolutionary trajectories.

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By using the MIN6 cell line and pancreatic islets, we show that in the presence of a low glucose concentration, corresponding to physiological glucagon release from ␣ cells, glucagon treatment of the ␤ cell caused a rapid, time-dependent phosphorylation and activation of p44/p42 mitogen-activated protein kinase (ERK1/2) independently from extracellular calcium influx. Inhibition of either cAMP-dependent protein kinase (PKA) or MEK completely blocked ERK1/2 activation by glucagon. However, no significant activation of several upstream activators of MEK, including Shc-p21Ras and phosphatidylinositol 3-kinase, was observed in response to glucagon treatment. Chelation of intracellular calcium (intracellular [Ca 2؉ ]) reduced glucagon-mediated ERK1/2 activation. In addition, internalization of glucagon receptors through clathrin-coated pits formation is required for ERK1/2 activation. Remarkably, glucagon promotes the nuclear translocation of ERK1/2 and induces the phosphorylation of cAMP-response elementbinding protein (CREB). Miniglucagon, produced from glucagon and released together with the mother hormone from the ␣ cells in low glucose situations, blocks the insulinotropic effect of glucagon, whereas it does not inhibit the glucagon-induced PKA/ERK1/2/CREB pathway. We conclude that glucagon-induced ERK1/2 activation is mediated by PKA and that an increase in [Ca 2؉ ] i is required for maximal ERK activation. Our results uncover a novel mechanism by which the PKA/ ERK1/2 signaling network engaged by glucagon, in situation of low glucose concentration, regulates phosphorylation of CREB, a transcription factor crucial for normal ␤ cell function and survival.

No abstract

Indigenous Chinese cattle combine taurine and indicine origins and occupy a broad range of different environments. By 50 K SNP genotyping we found a discontinuous distribution of taurine and indicine cattle ancestries with extremes of less than 10% indicine cattle in the north and more than 90% in the far south and southwest China. Model-based clustering and f4-statistics indicate introgression of both banteng and gayal into southern Chinese cattle while the sporadic yak influence in cattle in or near Tibetan area validate earlier findings of mitochondrial DNA analysis. Geographic patterns of taurine and indicine mitochondrial and Y-chromosomal DNA diversity largely agree with the autosomal cline. The geographic distribution of the genomic admixture of different bovine species is proposed to be the combined effect of prehistoric immigrations, gene flow, major rivers acting as genetic barriers, local breeding objectives and environmental adaptation. Whole-genome scan for genetic differentiation and association analyses with both environmental and morphological covariables are remarkably consistent with previous studies and identify a number of genes implicated in adaptation, which include TNFRSF19, RFX4, SP4 and several coat color genes. We propose indigenous Chinese cattle as a unique and informative resource for gene-level studies of climate adaptation in mammals.

No abstract

c Symbioses between leguminous plants and soil bacteria known as rhizobia are of great importance to agricultural production and nitrogen cycling. While these mutualistic symbioses can involve a wide range of rhizobia, some legumes exhibit incompatibility with specific strains, resulting in ineffective nodulation. The formation of nodules in soybean plants (Glycine max) is controlled by several host genes, which are referred to as Rj genes. The soybean cultivar BARC2 carries the Rj4 gene, which restricts nodulation by specific strains, including Bradyrhizobium elkanii USDA61. Here we employed transposon mutagenesis to identify the genetic locus in USDA61 that determines incompatibility with soybean varieties carrying the Rj4 allele. Introduction of the Tn5 transposon into USDA61 resulted in the formation of nitrogen fixation nodules on the roots of soybean cultivar BARC2 (Rj4 Rj4). Sequencing analysis of the sequence flanking the Tn5 insertion revealed that six genes encoding a putative histidine kinase, transcriptional regulator, DNA-binding transcriptional activator, helix-turn-helix-type transcriptional regulator, phage shock protein, and cysteine protease were disrupted. The cysteine protease mutant had a high degree of similarity with the type 3 effector protein XopD of Xanthomonas campestris. Our findings shed light on the diverse and complicated mechanisms that underlie these highly host-specific interactions and indicate the involvement of a type 3 effector in Rj4 nodulation restriction, suggesting that Rj4 incompatibility is partly mediated by effector-triggered immunity. P lants of the legume family can effectively make their own fertilizers by forming symbioses with a diverse group of nitrogen-fixing soil bacteria known as rhizobia. This cross-kingdom collaboration is characterized by the formation of the root nodule, a specialized plant organ that provides an optimized environment in which the bacteria convert atmospheric nitrogen into ammonia. The symbiotic interactions between leguminous plants and Rhizobium bacteria show high species specificity, which is determined by the exchange of signal molecules. The best-known determinants of host specificity derived from rhizobia are the so-called Nod factors (NFs), which comprise a family of lipochitooligosaccharides with various strain-specific chemical decorations (1). Legume roots excrete flavonoid compounds that can interact specifically with the rhizobial transcriptional factor NodD. Activation of NodD induces the expression of nodulation genes in rhizobia, which are required for the synthesis of NFs (2, 3). NFs are received by host NF receptors (NFRs) and activate host signal transduction pathways that lead to root hair infection and nodule organogenesis (2, 3). A recent study showed that introduction of the putative NFRs NFR1 and NFR5 of Lotus japonicus into Medicago truncatula initiated nodulation of the transgenic roots by the L. japonicus symbiont Mesorhizobium loti (4, 5). Thus, NFs and their receptor proteins contribute significantly to the de...