Woodland caribou habitat selection patterns in relation to predation risk and forage abundance depend on reproductive state

The ideal free distribution assumes that animals select habitats that are beneficial to their fitness. When the needs of dependent offspring differ from those of the parent, ideal habitat selection patterns could vary with the presence or absence of offspring. We test whether habitat selection depends on reproductive state due to top‐down or bottom‐up influences on the fitness of woodland caribou (Rangifer tarandus caribou), a threatened, wide‐ranging herbivore. We combined established methods of fitting resource and step selection functions derived from locations of collared animals in Ontario with newer techniques, including identifying calf status from video collar footage and seasonal habitat selection analysis through latent selection difference functions. We found that females with calves avoided predation risk and proximity to roads more strongly than females without calves within their seasonal ranges. At the local scale, females with calves avoided predation more strongly than females without calves. Females with calves increased predation avoidance but not selection for food availability upon calving, whereas females without calves increased selection for food availability across the same season. These behavioral responses suggest that habitat selection by woodland caribou is influenced by reproductive state, such that females with calves at heel use habitat selection to offset the increased vulnerability of their offspring to predation risk.     

The interface of protein structure, protein biophysics, and molecular evolution

Abstract The interface of protein structural biology, protein biophysics, molecular evolution, and molecular population genetics forms the foundations for a mechanistic understanding of many aspects of protein biochemistry. Current efforts in interdisciplinary protein modeling are in their infancy and the state-of-the art of such models is described. Beyond the relationship between amino acid substitution and static protein structure, protein function, and corresponding organismal fitness, other considerations are also discussed. More complex mutational processes such as insertion and deletion and domain rearrangements and even circular permutations should be evaluated. The role of intrinsically disordered proteins is still controversial, but may be increasingly important to consider. Protein geometry and protein dynamics as a deviation from static considerations of protein structure are also important. Protein expression level is known to be a major determinant of evolutionary rate and several considerations including selection at the mRNA level and the role of interaction specificity are discussed. Lastly, the relationship between modeling and needed high-throughput experimental data as well as experimental examination of protein evolution using ancestral sequence resurrection and in vitro biochemistry are presented, towards an aim of ultimately generating better models for biological inference and prediction.     

The effect of chlorophyll-bleaching herbicides on growth,carotenoid and diosgenin levels in cell suspension cultures of Dioscorea deltoidea

Bleaching herbicides of the phenylpyridazinone group (norflurazon, metflurazon, SAN 9774 and SAN 9785) and difunon and amitrole were added to cell suspension cultures of Dioscorea deltoidea at 1μM. Difunon inhibited growth and carotenoid biosynthesis and metflurazon inhibited growth. Norflurazon was the only herbicide tested that influenced diosgenin production. Norflurazon increased the rate of diosgenin biosynthesis so that 180mg/l were obtained after 14 days of incubation as compared to 30 days for the control to reach the same level.     

Kinematic features of continuous hand reaching movements under simple and complex rhythmical constraints

BackgroundAuditory cues are known to alter movement kinematics in healthy people as well as in people with neurological conditions (e.g., Parkinson’s disease or stroke). Pacing movement to rhythmical constraints is known to change both the spatial and temporal features of movement. However, the effect of complexity of pacing on the spatial and temporal kinematic properties is still poorly understood. The current study investigated spatial and temporal aspects of movement (path and speed, respectively) and their integration while subjects followed simple isochronous or complex non-isochronous rhythmical constraints. Spatiotemporal decoupling was expected under the latter constraint.MethodsTen subjects performed point-to-point hand movements towards visual targets on the surface of a hemisphere, while following continuous auditory cues of different pace and meter. The spatial and temporal properties of movement were compared to geodesic paths and unimodal bell-shaped speed profiles, respectively. Multiple two-way RM-ANOVAs (pace [1–2 Hz] × meter [duple–triple]) were performed on the different kinematic variables calculated to assess hand deviations from the model data (p ? 0.05).ResultsAs expected, increasing pace resulted in straighter hand paths and smoother speed profiles. Meter, however, affected only the path (shorter and straighter under triple) without significantly changing speed. Such an effect was observed at the slow pace only.ConclusionsUnder simple rhythmic cues, an increase in pace causes spontaneous adjustments in spatial features (straighter hand paths) while preserving temporal ones (maximally-smoothed hand speeds). Complex rhythmical cues in contrast perturb spatiotemporal coupling and challenge movement control. These results may have important practical implications in motor rehabilitation.     

Evolution of spliceosomal introns following endosymbiotic gene transfer

Background  

Spliceosomal introns are an ancient, widespread hallmark of eukaryotic genomes. Despite much research, many questions regarding the origin and evolution of spliceosomal introns remain unsolved, partly due to the difficulty of inferring ancestral gene structures. We circumvent this problem by using genes originated by endosymbiotic gene transfer, in which an intron-less structure at the time of the transfer can be assumed.     

High Throughput MicroRNA Profiling: Optimized Multiplex qRT-PCR at Nanoliter Scale on the Fluidigm Dynamic ArrayTM IFCs

The broad involvement of miRNAs in critical processes underlying development, tissue homoeostasis and disease has led to a surging interest among the research and pharmaceutical communities. To study miRNAs, it is essential that the quantification of microRNA levels is accurate and robust. By comparing wild-type to small RNA deficient mouse embryonic stem cells (mESC), we revealed a lack of accuracy and robustness in previous published multiplex qRT-PCR techniques. Here, we describe an optimized method, including purifying away excessive primers from previous multiplex steps before singleplex real time detection, which dramatically increases the accuracy and robustness of the technique. Furthermore, we explain how performing the technique on a microfluidic chip at nanoliter volumes significantly reduces reagent costs and permits time effective high throughput miRNA expression profiling.     

The Replication Initiation Protein Sld3/Treslin Orchestrates the Assembly of the Replication Fork Helicase during S Phase

The initiation of DNA replication is a highly regulated process in eukaryotic cells, and central to the process of initiation is the assembly and activation of the replication fork helicase. The replication fork helicase is comprised of CMG (Cdc45, Mcm2–7, and GINS) in eukaryotic cells, and the mechanism underlying assembly of the CMG during S phase was studied in this article. We identified a point mutation of Sld3 that is specifically defective for Mcm3 and Mcm5 interaction (sld3-m10), and also identified a point mutation of Sld3 that is specifically defective for single-stranded DNA (ssDNA) interaction (sld3-m9). Expression of wild-type levels of sld3-m9 resulted in a severe DNA replication defect with no recruitment of GINS to Mcm2–7, whereas expression of wild-type levels of sld3-m10 resulted in a severe replication defect with no Cdc45 recruitment to Mcm2–7. We propose a model for Sld3-mediated control of replication initiation, wherein Sld3 manages the proper assembly of the CMG during S phase. We also find that the biochemical functions identified for Sld3 are conserved in human Treslin, suggesting that Treslin orchestrates assembly of the CMG in human cells.