The binding of Varp to VAMP7 traps VAMP7 in a closed, fusogenically inactive conformation.

SNAREs provide energy and specificity to membrane fusion events. Fusogenic trans-SNARE complexes are assembled from glutamine-contributing SNAREs (Q-SNAREs) embedded in one membrane and an arginine-contributing SNARE (R-SNARE) embedded in the other. Regulation of membrane fusion events is crucial for intracellular trafficking. We identify the endosomal protein Varp as an R-SNARE-binding regulator of SNARE complex formation. Varp colocalizes with and binds to VAMP7, an R-SNARE that is involved in both endocytic and secretory pathways. We present the structure of the second ankyrin repeat domain of mammalian Varp in complex with the cytosolic portion of VAMP7. The VAMP7-SNARE motif is trapped between Varp and the VAMP7 longin domain, and hence Varp kinetically inhibits the ability of VAMP7 to form SNARE complexes. This inhibition will be increased when Varp can also bind to other proteins present on the same membrane as VAMP7, such as Rab32-GTP

Does Landscape Composition Influence the Diets of Feral Cats in Agroecosystems?

Habitat fragmentation can influence the diet of mammalian predators, potentially increasing their impact on prey species. Agroecosystems are fragmented landscapes that often have high densities of invasive mammalian predators. Feral cats are generalist predators that have successfully adapted to living in agricultural landscapes. Feral cats are known to eat rabbits, rodents, and birds, but it is unclear how landscape characteristics affect prey consumption. Here, we tested whether feral cat diet in New Zealand agroecosystems was affected by landscape composition and spatial configuration. We examined the contents of 112 feral cat gastrointestinal tracts collected from agroecosystems in different New Zealand regions over a 3-year period. We related prey richness and composition to the landscape composition and spatial configuration in a 500-ha area within which each cat was caught. Dietary analysis showed that feral cats were consuming invertebrates, birds, rodents, and rabbits, and that there were some regional and seasonal effects. No significant differences in prey richness or composition of the diet were associated with variation in landscape composition or spatial configuration. This study confirms feral cats as generalist predators that feed on a wide range of prey types in New Zealand agroecosystems, including some native species. Our study highlights the importance of further research for understanding how current conservation interventions in New Zealand, which include revegetation and rodent control, interact with feral cat populations and behaviours to impact on future biodiversity outcomes

Identification of an imprinting control region affecting the expression of all transcripts in the Gnas cluster.

Genomic imprinting results in allele-specific silencing according to parental origin1. Silencing is brought about by imprinting control regions (ICRs) that are differentially marked in gametogenesis2. The group of imprinted transcripts in the mouse Gnas cluster (Nesp, Nespas, Gnasxl, Exon 1A and Gnas) provides a model for analyzing the mechanisms of imprint regulation. We previously identified an ICR that specifically regulates the tissue-specific imprinted expression of the Gnas gene3. Here we identify a second ICR at the Gnas cluster. We show that a paternally derived targeted deletion of the germline differentially methylated region (DMR) associated with the antisense Nespas transcript unexpectedly affects both the expression of all transcripts in the cluster and methylation of two DMRs. Our results establish that the Nespas DMR is the principal ICR at the Gnas cluster and functions bidirectionally as a switch for modulating expression of the antagonistically acting genes Gnasxl and Gnas. Uniquely, the Nespas DMR acts on the downstream ICR at exon 1A to regulate tissue-specific imprinting of the Gnas gene