Internal filters: Prospects for UV-acclimation in higher plants

Wavelength-selective absorption of solar radiation within plant leaves allows penetration of visible radiation (400–700 nm) to the chloroplasts, while removing much of the damaging ultraviolet-B (UV-B, 280–320 nm) radiation. Flavonoids are important in this wavelength-selective absorption. Induction of flavonoid synthesis by solar radiation, and specifically by UV-B radiation, is discussed as this relates to the potential acclimation of plants to enhanced solar UV-B radiation that would result from stratospheric ozone reduction.     

SNP frequency, haplotype structure and linkage disequilibrium in elite maize inbred lines

Background  

Recent studies of ancestral maize populations indicate that linkage disequilibrium tends to dissipate rapidly, sometimes within 100 bp. We set out to examine the linkage disequilibrium and diversity in maize elite inbred lines, which have been subject to population bottlenecks and intense selection by breeders. Such population events are expected to increase the amount of linkage disequilibrium, but reduce diversity. The results of this study will inform the design of genetic association studies.     

The effect of methylation of the 6 oxygen of guanine on the structure and stability of double helical DNA

The effect of methylation of the O-6 position of guanine in short segments of double helical DNA has been investigated by molecular mechanical simulations on the sequences d(CGCGCG)2, d(CGC[OMG]CG)2, d(CGT[OMG]CG)2, d(CGC[OMC]CG/(CGCGCG), d(CGC[OMG]CG/d(CGTGCG), d(CGCGAATTCGCG)2 and d(CGCGAATTC[OMG]CG)2. Guanines methylated at the O-6 position are found to form hydrogen bonds of roughly equal strength to cytosine and thymine. The optimum structure of these modified base pairs are not dramatically different from normal GC pairs, but both involve some bifurcation of the proton donors of cytosine (4NH2) or thymine (3NH) between the guanine N3 and O6 groups.     

KERA: analysis tool for multi-process,multi-state single-molecule data

Molecular machines within cells dynamically assemble, disassemble and reorganize. Molecular interactions between their components can be observed at the single-molecule level and quantified using colocalization single-molecule spectroscopy, in which individual labeled molecules are seen transiently associating with a surface-tethered partner, or other total internal reflection fluorescence microscopy approaches in which the interactions elicit changes in fluorescence in the labeled surface-tethered partner. When multiple interacting partners can form ternary, quaternary and higher order complexes, the types of spatial and temporal organization of these complexes can be deduced from the order of appearance and reorganization of the components. Time evolution of complex architectures can be followed by changes in the fluorescence behavior in multiple channels. Here, we describe the kinetic event resolving algorithm (KERA), a software tool for organizing and sorting the discretized fluorescent trajectories from a range of single-molecule experiments. KERA organizes the data in groups by transition patterns, and displays exhaustive dwell time data for each interaction sequence. Enumerating and quantifying sequences of molecular interactions provides important information regarding the underlying mechanism of the assembly, dynamics and architecture of the macromolecular complexes. We demonstrate KERA’s utility by analyzing conformational dynamics of two DNA binding proteins: replication protein A and xeroderma pigmentosum complementation group D helicase.     

Mule Deer Migrations and Highway Underpass Usage in California,USA

Roadways may pose barriers to long-distance migrators such as some ungulates. Highway underpasses mitigate wildlife-vehicle collisions and can be an important management tool for protecting migration corridors. In northern California, 3 underpasses were built on United States Route 395 (Route 395) in Hallelujah Junction Wildlife Area (HJWA) in the 1970s for a migratory mule deer (Odocoileus hemionus) herd that had been negatively affected by highway traffic. To determine whether these underpasses were still reducing mule deer mortalities >40 years after construction, we investigated deer use of the underpasses from 2006–2019 using cameras, global positioning system (GPS) collars, and roadkill records. We used occupancy models, approximations of GPS-collared mule deer movement paths, and roadkill locations to estimate the highway crossing patterns of deer. From camera data, there was higher use of the underpasses by deer during migration (spring [Mar–Jun], fall [Oct–Dec]) than in summer (Jul–Sep), when only resident deer were present. Higher underpass usage occurred in the spring compared to fall migrations. Eleven of 21 GPS-collared migrating mule deer crossed Route 395. We estimated 30% of the crossings (by 7 of the 11 deer) occurred south of the underpasses where deer could easily access the highway because of short (1-m high) and deteriorating highway fencing. Roadkill data confirmed that deer-vehicle collisions were occurring south of the underpasses and at the underpasses. This was likely due to deteriorating infrastructure at the underpasses that allows wildlife access to the highway. Overall, our study indicated that although underpasses can provide safe passage for migratory deer decades (>40 yr) after their construction, deteriorating infrastructure such as fencing and gates can lead to wildlife mortalities on highways near underpasses. © 2021 The Wildlife Society.     

Adaptive signaling behavior in stomatopods under varying light conditions

Stomatopod crustaceans (mantis shrimp) are aggressive benthic marine predators with extraordinary color vision. When communicating with conspecifics, many stomatopods display conspicuously colored body areas, often in combination with other types of signals such as motion and chemical cues. Some species occupy wide depth ranges (>30 m), where changing light conditions can influence color perception. To test the potential effects of differing ambient lights on signaling behavior, stomatopods (Gonodactylus smithii) interacted with conspecifics in aquaria, under full-spectrum, high intensity light or light restricted in either spectrum or intensity. During intrasexual and intersexual trials in full-spectrum, high intensity light, animals performed more aggressive acts using colored body parts (meral spread, lunge, strike). Stomatopods used significantly more antennular flicking, and performed aggressive acts at reduced distances under restricted light conditions. To compare the use of antennules in visual and chemical communication, additional experiments showed more antennular flicking in response to chemical stimuli from food or conspecifics compared to seawater controls. This response ceased immediately after ablation of antennular chemoreceptors but returned to pre-treatment levels after 5 days of recovery. These findings suggest that stomatopods can vary their use of signals during conspecific interactions under different photic conditions. These inducible, plastic behavioral responses can potentially improve signal transfer in varying light environments.