Photo-Induced Spin Dynamics in Semiconductor Quantum Wells

We experimentally investigate the dynamics of spins in GaAs quantum wells under applied electric bias by photoluminescence (PL) measurements excited with circularly polarized light. The bias-dependent circular polarization of PL (PPL) with and without magnetic field is studied. ThePPLwithout magnetic field is found to be decayed with an enhancement of increasing the strength of the negative bias. However,PPLin a transverse magnetic field shows oscillations under an electric bias, indicating that the precession of electron spin occurs in quantum wells. The results are discussed based on the electron–hole exchange interaction in the electric field

Late Replication Domains in Polytene and Non-Polytene Cells of Drosophila melanogaster

In D. melanogaster polytene chromosomes, intercalary heterochromatin (IH) appears as large dense bands scattered in euchromatin and comprises clusters of repressed genes. IH displays distinctly low gene density, indicative of their particular regulation. Genes embedded in IH replicate late in the S phase and become underreplicated. We asked whether localization and organization of these late-replicating domains is conserved in a distinct cell type. Using published comprehensive genome-wide chromatin annotation datasets (modENCODE and others), we compared IH organization in salivary gland cells and in a Kc cell line. We first established the borders of 60 IH regions on a molecular map, these regions containing underreplicated material and encompassing ∼12% of Drosophila genome. We showed that in Kc cells repressed chromatin constituted 97% of the sequences that corresponded to IH bands. This chromatin is depleted for ORC-2 binding and largely replicates late. Differences in replication timing between the cell types analyzed are local and affect only sub-regions but never whole IH bands. As a rule such differentially replicating sub-regions display open chromatin organization, which apparently results from cell-type specific gene expression of underlying genes. We conclude that repressed chromatin organization of IH is generally conserved in polytene and non-polytene cells. Yet, IH domains do not function as transcription- and replication-regulatory units, because differences in transcription and replication between cell types are not domain-wide, rather they are restricted to small “islands” embedded in these domains. IH regions can thus be defined as a special class of domains with low gene density, which have narrow temporal expression patterns, and so displaying relatively conserved organization

Transcriptome Analysis of the Desert Locust Central Nervous System: Production and Annotation of a Schistocerca gregaria EST Database

) displays a fascinating type of phenotypic plasticity, designated as ‘phase polyphenism’. Depending on environmental conditions, one genome can be translated into two highly divergent phenotypes, termed the solitarious and gregarious (swarming) phase. Although many of the underlying molecular events remain elusive, the central nervous system (CNS) is expected to play a crucial role in the phase transition process. Locusts have also proven to be interesting model organisms in a physiological and neurobiological research context. However, molecular studies in locusts are hampered by the fact that genome/transcriptome sequence information available for this branch of insects is still limited. EST information is highly complementary to the existing orthopteran transcriptomic data. Since many novel transcripts encode neuronal signaling and signal transduction components, this paper includes an overview of these sequences. Furthermore, several transcripts being differentially represented in solitarious and gregarious locusts were retrieved from this EST database. The findings highlight the involvement of the CNS in the phase transition process and indicate that this novel annotated database may also add to the emerging knowledge of concomitant neuronal signaling and neuroplasticity events. EST data constitute an important new source of information that will be instrumental in further unraveling the molecular principles of phase polyphenism, in further establishing locusts as valuable research model organisms and in molecular evolutionary and comparative entomology

PHYSICAL CHARACTERISTICS OF ULTRA-MARATHON DISTANCE RUNNERS

Karolina Zavisiute1, Anthony Hagele1, Joesi Krieger1, Kyle Sunderland1, Petey Mumford1, Chad Kerksick, FACSM1, & 1Scott Richmond 1Exercise and Performance Nutrition Laboratory, Lindenwood University, St. Charles, Missouri Participation in long distance running events, specifically marathons and ultramarathons, has been growing at an incredible rate in the past two decades. As the number of participants has grown, so has the interest in learning more about the physiological differences between ‘typical’ distance runners (those running marathons and shorter distance races) from those running longer distance races such as ultramarathons. PURPOSE: The primary aim of this study is to explore physiological characteristics of non-elite ultramarathon runners and muscular changes after completion of a 100-mile trail race. METHODS: Within the two weeks preceding a 100-mile trail ultramarathon race, participants completed a test of aerobic capacity (VO2peak), muscle strength (isometric belt squat, IMBS), muscle power (countermovement jump, CMJ), and muscle structure (ultrasound). Within five days after the race, participants repeated the IMBS, CMJ and ultrasound. A total of 10 males (age = 36.6 ± 14.1y, height = 177.4 ± 7.2cm, weight = 75.4 ± 7.1kg, VO2peak = 52.8 ± 6.3mL/kg/min) participated in this study. RESULTS: Seven participants finished the race with an average time of 26:10:36 hr:min:sec (range = 20:39:50 to 33:27:59 hr:min:sec). CMJ results showed significant changes (p = 0.007) in braking RFD (pre = 6570.0 ± 4832.3N, post = 3914.7 ± 3036.9N) as well as significant changes (p = 0.029) during force at peak braking force for both the left (pre = 823.8 ± 154.6N, post = 716.9 ± 177.5N) and right legs (pre = 816.5 ± 109.5N, post = 746.6 ± 148.5N). No other significant changes were observed in IMBS or ultrasound. CONCLUSION: The observed changes in power may be attributable to the rocky terrain of the racecourse, as well as the impact incurred during repeated downhill running. The physiological characteristics of non-elite ultramarathon runners are similar to individuals with average fitness levels