Postfledging habitat selection and survival of Henslow’s Sparrow: management implications for a critical life stage

Conserving populations of species that rely on rare habitat requires that managers understand which habitat characteristics will best support population growth across multiple life stages. For songbirds, management is most often aimed at nesting adult habitat associations. However, habitat that meets adult requirements may not be similarly suited to requirements for other life stages. Henslow’s Sparrow (Centronyx henslowii) is a tallgrass prairie songbird listed as threatened or endangered in 13 states. We examined survival and habitat selection of Henslow’s Sparrow during the postfledging period. During the nesting seasons in 2015 and 2016, we attached radio transmitters to 46 nestlings in a tallgrass prairie and modeled their survival and habitat selection as a function of habitat characteristics. Thirty-five percent of fledglings survived until two weeks postfledge. Survival was negatively associated with areas of sumac (Rhus copallinum) cover, positively associated with years since last burn, and decreased as the breeding season progressed. Snakes were the most common predator of fledglings. Independent fledglings used habitat that was different than that used by adults and dependent fledglings, with habitat used during the independent period having lower litter cover and increased forb cover compared to points used during the dependent period. During the dependent period, points used by fledglings were a mean distance of 40 m (± 11 SD) from the natal nest. Following independence, points used by fledglings were 236 m (± 89 SD) from the natal nest. Henslow’s Sparrow populations may benefit from removal of encroaching sumac in tallgrass prairie, and from consideration of the varying habitats used by the species during different life stages

Inducible expression of large gRNA arrays for multiplexed CRISPRai applications

CRISPR gene activation and inhibition (CRISPRai) has become a powerful synthetic tool for influencing the expression of native genes for foundational studies, cellular reprograming, and metabolic engineering. Here we develop a method for near leak-free, inducible expression of a polycistronic array containing up to 24 gRNAs from two orthogonal CRISPR/Cas systems to increase CRISPRai multiplexing capacity and target gene flexibility. To achieve strong inducibility, we created a technology to silence gRNA expression within the array in the absence of the inducer, since we found that long gRNA arrays for CRISPRai can express themselves even without promoter. Using this method, we create a highly tuned and easy-to-use CRISPRai toolkit in the industrially relevant yeast, Saccharomyces cerevisiae, establishing the first system to combine simultaneous activation and repression, large multiplexing capacity, and inducibility. We demonstrate this platform by targeting 11 genes in central metabolism in a single transformation, achieving a 45-fold increase in succinic acid, which could be precisely controlled in an inducible manner. Our method offers a highly effective way to regulate genes and rewire metabolism in yeast, with principles of gRNA array construction and inducibility that should extend to other chassis organisms

Phosphorylation of the androgen receptor is associated with reduced survival in hormonerefractory prostate cancer patients

Cell line studies demonstrate that the PI3K/Akt pathway is upregulated in hormone-refractory prostate cancer (HRPC) and can result in phosphorylation of the androgen receptor (AR). The current study therefore aims to establish if this has relevance to the development of clinical HRPC. Immunohistochemistry was employed to investigate the expression and phosphorylation status of Akt and AR in matched hormone-sensitive and -refractory prostate cancer tumours from 68 patients. In the hormone-refractory tissue, only phosphorylated AR (pAR) was associated with shorter time to death from relapse (<i>P</i>=0.003). However, when an increase in expression in the transition from hormone-sensitive to -refractory prostate cancer was investigated, an increase in expression of PI3K was associated with decreased time to biochemical relapse (<i>P</i>=0.014), and an increase in expression of pAkt<sup>473</sup> and pAR<sup>210</sup> were associated with decreased disease-specific survival (<i>P</i>=0.0019 and 0.0015, respectively). Protein expression of pAkt<sup>473</sup> and pAR<sup>210</sup> also strongly correlated (<i>P</i><0.001, c.c.=0.711) in the hormone-refractory prostate tumours. These results provide evidence using clinical specimens, that upregulation of the PI3K/Akt pathway is associated with phosphorylation of the AR during development of HRPC, suggesting that this pathway could be a potential therapeutic target

The role of interstitial gas in determining the impact response of granular beds

We examine the impact of a solid sphere into a fine-grained granular bed. Using high-speed X-ray radiography we track both the motion of the sphere and local changes in the bed packing fraction. Varying the initial packing density as well as the ambient gas pressure, we find a complete reversal in the effect of interstitial gas on the impact response of the bed: The dynamic coupling between gas and grains allows for easier penetration in initially loose beds but impedes penetration in more densely packed beds. High-speed imaging of the local packing density shows that these seemingly incongruous effects have a common origin in the resistance to bed packing changes caused by interstitial air.Comment: 5 pages, 4 figures, submitted to EP

Why name generators with a fixed number of alters may be a pragmatic option for personal network analysis

Social network analysis (SNA) has grown exponentially in recent years, giving rise to methodological innovations in different scientific disciplines. In psychology, SNA has been incorporated into studies of individual personality differences and has generated novel areas, such as network psychometrics and network interventions. In community psychology, a recent review examined the use of network analysis in American Journal of Community Psychology publications (Neal & Neal, American Journal of Community Psychology , 2017, 60, 279). Based on their study, the authors advise researchers to avoid using the fixed-choice name generator when possible, as one of the five methodological recommendations proposed. In this essay, I explain how the recent increase of name generators with a fixed number of alters when studying personal networks is originally linked to an interest in describing structural properties. Second, I analyze the pragmatic contributions of this method: establishing a limit of alters a priori can entail advantages in terms of standardization and comparability of personal networks. Finally, to contextualize the methodological debate, I argue that personal networks represent the diversity of contexts in which the individual participates and are naturally integrated into community surveys

Factors influencing graphene growth on metal surfaces

Graphene forms from a relatively dense, tightly-bound C-adatom gas, when elemental C is deposited on or segregates to the Ru(0001) surface. Nonlinearity of the graphene growth rate with C adatom density suggests that growth proceeds by addition of C atom clusters to the graphene edge. The generality of this picture has now been studied by use of low-energy electron microscopy (LEEM) to observe graphene formation when Ru(0001) and Ir(111) surfaces are exposed to ethylene. The finding that graphene growth velocities and nucleation rates on Ru have precisely the same dependence on adatom concentration as for elemental C deposition implies that hydrocarbon decomposition only affects graphene growth through the rate of adatom formation; for ethylene, that rate decreases with increasing adatom concentration and graphene coverage. Initially, graphene growth on Ir(111) is like that on Ru: the growth velocity is the same nonlinear function of adatom concentration (albeit with much smaller equilibrium adatom concentrations, as we explain with DFT calculations of adatom formation energies). In the later stages of growth, graphene crystals that are rotated relative to the initial nuclei nucleate and grow. The rotated nuclei grow much faster. This difference suggests first, that the edge-orientation of the graphene sheets relative to the substrate plays an important role in the growth mechanism, and second, that attachment of the clusters to the graphene is the slowest step in cluster addition, rather than formation of clusters on the terraces