Mesodern-inducing factors and mesodermal patterning

Identification of the signalling molecules involved in mesoderm formation in amphibian embryos still presents problems. None of the original candidates, such as activin, have been definitively ruled out, and the new factors, such as the nodal-related genes, have come on to the scene. Of the original candidates, activin has been definitively shown to act as a morphogen, whereas bone morphogenetic protein (BMP)-4 has emerged as a ventral inducer and an inhibitor of neural differentiation. The effects of BMP-4 are antagonized by chordin, a molecule related to the product of the Drosophila gene short gastrulation.     

Secretion of trans-zeatin by Agrobacterium tumefaciens: A function determined by the nopaline Ti plasmid

Production of the plant cytokinin, trans-zeatin, by a number of strains of Agrobacterium tumefaciens was measured by a combination of traceenrichment, HPLC and radioimmunoassay and confirmed by mass spectrometry. Secretion of trans-zeatin into a culture medium is a constitutive function of those strains which harbor a nopaline Ti plasmid. Strains cured of the nopaline Ti plasmid and those which harbor octopine or agropine plasmids are non-producers. Reacquisition of nopaline plasmids by cured strains restores production.     

Ant genomics sheds light on the molecular regulation of social organization

Ants are powerful model systems for the study of cooperation and sociality. In this review, we discuss how recent advances in ant genomics have contributed to our understanding of the evolution and organization of insect societies at the molecular level.     

Languages Support Efficient Communication about the Environment: Words for Snow Revisited

The claim that Eskimo languages have words for different types of snow is well-known among the public, but has been greatly exaggerated through popularization and is therefore viewed with skepticism by many scholars of language. Despite the prominence of this claim, to our knowledge the line of reasoning behind it has not been tested broadly across languages. Here, we note that this reasoning is a special case of the more general view that language is shaped by the need for efficient communication, and we empirically test a variant of it against multiple sources of data, including library reference works, Twitter, and large digital collections of linguistic and meteorological data. Consistent with the hypothesis of efficient communication, we find that languages that use the same linguistic form for snow and ice tend to be spoken in warmer climates, and that this association appears to be mediated by lower communicative need to talk about snow and ice. Our results confirm that variation in semantic categories across languages may be traceable in part to local communicative needs. They suggest moreover that despite its awkward history, the topic of “words for snow” may play a useful role as an accessible instance of the principle that language supports efficient communication.     

Attenuation of pattern recognition receptor signaling is mediated by a MAP kinase kinase kinase

Pattern recognition receptors (PRRs) play a key role in plant and animal innate immunity. PRR binding of their cognate ligand triggers a signaling network and activates an immune response. Activation of PRR signaling must be controlled prior to ligand binding to prevent spurious signaling and immune activation. Flagellin perception in Arabidopsis through FLAGELLIN‐SENSITIVE 2 (FLS2) induces the activation of mitogen‐activated protein kinases (MAPKs) and immunity. However, the precise molecular mechanism that connects activated FLS2 to downstream MAPK cascades remains unknown. Here, we report the identification of a differentially phosphorylated MAP kinase kinase kinase that also interacts with FLS2. Using targeted proteomics and functional analysis, we show that MKKK7 negatively regulates flagellin‐triggered signaling and basal immunity and this requires phosphorylation of MKKK7 on specific serine residues. MKKK7 attenuates MPK6 activity and defense gene expression. Moreover, MKKK7 suppresses the reactive oxygen species burst downstream of FLS2, suggesting that MKKK7‐mediated attenuation of FLS2 signaling occurs through direct modulation of the FLS2 complex.     

Phylogenetic utility of the nuclear gene dopa decarboxylase in noctuoid moths (Insecta: Lepidoptera: noctuoidea)

Phylogenetic utility for the nuclear gene encoding dopa decarboxylase (DDC), little used in systematics, was recently demonstrated within the noctuid moth subfamily Heliothinae. Here we extend the test of the utility of a 709-bp DDC fragment to deeper levels, analyzing 49 species representing major groups across the superfamily Noctuoidea. Parsimony, distance, and maximum-likelihood analyses recover all or nearly all of a set of "test clades" supported by clear morphological synapomorphies, spanning a wide range of taxonomic levels. DDC also upholds a recent proposal that the Noctuidae are paraphyletic. Nt3 contributes a majority of the signal and recovers the basal split between Notodontidae and all other noctuoids, despite a plateau of nt3 divergence at this level. However, nonsynonymous changes also support groups at all levels, and in contrast to nt3, amino acid divergence shows no plateau. The utility of DDC promises to extend back to the early Tertiary and Cretaceous, a time span for which few suitable genes have been identified.