Selective REM sleep deprivation during daytime. II. Muscle atonia in non-REM sleep

One of the hallmarks of rapid eye movement (REM) sleep is muscle atonia. Here we report extended epochs of muscle atonia in non-REM sleep (MAN). Their extent and time course was studied in a protocol that included a baseline night, a daytime sleep episode with or without selective REM sleep deprivation, and a recovery night. The distribution of the latency to the first occurrence of MAN was bimodal with a first mode shortly after sleep onset and a second mode 40 min later. Within a non-REM sleep episode, MAN showed a U-shaped distribution with the highest values before and after REM sleep. Whereas MAN was at a constant level over consecutive 2-h intervals of nighttime sleep, MAN showed high initial values when sleep began in the morning. Selective daytime REM sleep deprivation caused an initial enhancement of MAN during recovery sleep. It is concluded that episodes of MAN may represent an REM sleep equivalent and that it may be a marker of homeostatic and circadian REM sleep regulating processes. MAN episodes may contribute to the compensation of an REM sleep deficit.     

Conservation strategies for lichens: insights from population biology

To design effective conservation strategies, the population biology of the target organism needs to be well understood. In lichens, the population dynamics of the symbiotic organism is closely tied to the dynamics of its substrate. Here, we review the population biology of selected lichens, highlighting the link between landscape and lichen population dynamics. We suggest strategies to efficiently protect lichen species and develop priorities for species conservation approaches.     

Congruent genetic structure in the lichen-forming fungus Lobaria pulmonaria and its green-algal photobiont

The extent of codispersal of symbionts is one of the key factors shaping genetic structures of symbiotic organisms. Concordant patterns of genetic structure are expected in vertically transmitted symbioses, whereas horizontal transmission generally uncouples genetic structures unless the partners are coadapted. Here, we compared the genetic structures of mutualists, the lichen-forming fungus Lobaria pulmonaria and its primary green-algal photobiont, Dictyochloropsis reticulata. We performed analysis of molecular variance and variogram analysis to compare genetic structures between symbiosis partners. We simulated the expected number of multilocus-genotype recurrences to reveal whether the distribution of multilocus genotypes of either species was concordant with panmixia. Simulations and tests of linkage disequilibrium provided compelling evidence for the codispersal of mutualists. To test whether genotype associations between symbionts were consistent with randomness, as expected under horizontal transmission, we simulated the recurrence of fungal-algal multilocus genotype associations expected by chance. Our data showed nonrandom associations of fungal and algal genotypes. Either vertical transmission or horizontal transmission coupled with coadaptation between symbiont genotypes may have created these nonrandom associations. This study is among the first to show codispersal and highly congruent genetic structures in the partners of a lichen mutualism.     

Variogram analysis of the spatial genetic structure of continuous populations using multilocus microsatellite data

A geostatistical perspective on spatial genetic structure may explain methodological issues of quantifying spatial genetic structure and suggest new approaches to addressing them. We use a variogram approach to (i) derive a spatial partitioning of molecular variance, gene diversity, and genotypic diversity for microsatellite data under the infinite allele model (IAM) and the stepwise mutation model (SMM), (ii) develop a weighting of sampling units to reflect ploidy levels or multiple sampling of genets, and (iii) show how variograms summarize the spatial genetic structure within a population under isolation-by-distance. The methods are illustrated with data from a population of the epiphytic lichen Lobaria pulmonaria, using six microsatellite markers. Variogram-based analysis not only avoids bias due to the underestimation of population variance in the presence of spatial autocorrelation, but also provides estimates of population genetic diversity and the degree and extent of spatial genetic structure accounting for autocorrelation.     

Pathophysiology of cutaneous lupus erythematosus

The pathophysiology of cutaneous lupus erythematosus (CLE) encompasses the complex interactions between genetics, the environment, and cells and their products. Recent data have provided enhanced understanding of these interactions and the mechanism by which they cause disease. A number of candidate genes have been identified which increase the risk of developing CLE. Ultraviolet radiation, the predominant environmental exposure associated with CLE, appears to initiate CLE lesion formation by inducing apoptosis, precipitating autoantigen presentation, and promoting cellular production of specific cytokines. Autoantibodies are a well-known entity in CLE, but their exact role remains unclear. Finally, cells ranging from native skin cells to innate and adaptive immune cells produce cytokines and other molecules and play specific roles in lesion formation and perpetuation. Native skin cells implicated in CLE include keratinocytes and endothelial cells. Innate immune cells crucial to CLE pathophysiology include dendritic cells and neutrophils. The primary adaptive immune cells thought to be involved include Th1 cells, Th17 cells, cytotoxic T cells, and invariant natural killer T cells. Though the pathophysiology of CLE has yet to be fully characterized, current research provides direction for future research and therapies.