Cytogeographic Distribution and Genome Size Variation in Prairie Cordgrass (Spartina pectinata Bosc ex Link)

Prairie cordgrass plants (Spartina pectinata Bosc ex Link) were examined from 61 locations representing the geographic distribution of prairie cordgrass in the U.S. Using flow cytometry, the genome size of 183 individual plants of prairie cordgrass was determined, and the chromosome counts were obtained. Three distinct ploidy levels were observed: tetraploid ( $ \overline x = {1}.{56} {\text{pg}},{2}n = {4} \times = {4}0 $ ), hexaploid ( $ \overline x { = 2}.{33} {\text{pg}},{2}n = {6} \times = {6}0 $ ), and octoploid ( $ \overline {\text{x}} { = 3}.0{6} {\text{pg}},{2}n = {8} \times { = 8}0 $ ). In the sampled areas, the tetraploid populations extended from the East North Central to the New England regions of the U.S., while the octoploid cytotypes were mostly distributed in the West North Central regions. Populations of the tetraploids and octoploids were found in close proximity in the West North Central (Iowa and Kansas) and the West South Central (Oklahoma) regions. The hexaploid cytotype was found in one mixed population (4x?+?6x) occurring in Illinois. No statistically significant intraploidy genome size variation was found in the tetraploid populations, while significant intraploidy genome size variation was found in the octoploid populations. This study precisely defined the geographic distribution of cytotypes in prairie cordgrass throughout the different regions of the U.S. These results provide critical genome size and ploidy distribution information needed to design efficient breeding schemes for high yielding cultivars of prairie cordgrass with local adaption.     

Learning to smell the roses: experience-dependent neural plasticity in human piriform and orbitofrontal cortices

It is widely presumed that odor quality is a direct outcome of odorant structure, but human studies indicate that molecular knowledge of an odorant is not always sufficient to predict odor quality. Indeed, the same olfactory input may generate different odor percepts depending on prior learning and experience. Combining functional magnetic resonance imaging with an olfactory paradigm of perceptual learning, we examined how sensory experience modifies odor perception and odor quality coding in the human brain. Prolonged exposure to a target odorant enhanced perceptual differentiation for odorants related in odor quality or functional group, an effect that was paralleled by learning-induced response increases in piriform cortex and orbitofrontal cortex (OFC). Critically, the magnitude of OFC activation predicted subsequent improvement in behavioral differentiation. Our findings suggest that neural representations of odor quality can be rapidly updated through mere perceptual experience, a mechanism that may underlie the development of odor perception.     

Predation of seabirds by invasive rats: multiple indirect consequences for invertebrate communities

Invasive species are a global problem but most studies have focused on their direct rather than indirect ecological effects. We studied litter and soil‐inhabiting invertebrate communities on 18 islands off northern New Zealand, to better understand the indirect ecological consequences of rat (Rattus) invasion. Nine islands host high densities of burrowing procellariid seabirds that transport large amounts of nutrients from the ocean to the land. The other nine have been invaded over the past 50–150 years by rat species that have severely reduced the density of seabirds by preying on eggs and chicks. Invaded islands had lower densities of seabird burrows but deeper forest litter than did the uninvaded islands, indicative of rats reducing disturbance effects of seabirds. However, despite deeper litter on the invaded islands, eight of the 19 orders of invertebrates that we measured were significantly less abundant on invaded islands. Furthermore, three soil‐inhabiting micro‐invertebrate groups that we measured were significantly less abundant on invaded islands. These differences probably result from rats thwarting transfer of resources by seabirds from the ocean to the land. We also investigated community‐level properties of each of three test groups of invertebrates (minute land snails, spiders and soil nematodes) to illustrate this process. Spiders were equally abundant on both groups of islands, but showed lower species richness on the invaded islands. The other two groups showed no difference in species richness with island invasion status, but were more abundant on uninvaded islands. Reduced abundance of soil nematodes on invaded islands provides strong evidence of indirect consequences of seabird reduction by rats, because nematodes are unavailable to rats as prey. We predict that if rats are eradicated from islands, components of below‐ground invertebrate dependent on seabird‐mediated soil conditions may take considerable time to recover because they require subsequent seabird recolonisation.     

Effects of age,size, and density on natural survival for an important coral reef fishery species,yellow tang, <Emphasis Type="Italic">Zebrasoma flavescens</Emphasis>

Hundreds of thousands of juvenile yellow tang, Zebrasoma flavescens, are caught each year in the state of Hawai’i (USA) for the live aquarium trade. As part of an extensive adaptive management strategy built around a network of protected areas, an emphasis was placed on understanding this important species’ life history. Multiple capture-mark-recapture techniques and a model selection approach to data analysis in Program MARK were used to estimate the effects of individual age and conspecific density on natural per-capita daily survival probabilities of yellow tang recruits (recently settled individuals, 30–50 mm total length) and the effects of body size and site on natural per-capita monthly survival probabilities for juveniles (58–127 mm total length). The models of recruit survival that included additive effects of density and age were best supported by the data and indicated an increase of survival with age and decrease of survival with increased conspecific density. At 1 day post-settlement, the model averaged daily per-capita survival probability ranged from 0.963 (95% CI: 0.932–0.981) at a low density of 0.1 recruits m⁻² to 0.848 (95% CI: 0.752–0.911) at a high density of 1.3 recruits m⁻². The best supported model of juvenile survival had no effect of fish length or site, with a constant monthly per-capita survival of 0.939 (95% CI: 0.925–0.950). Only about 1% of recruits may survive to adulthood when protected from fishing. These results can be used to better analyze and interpret data from protected area monitoring surveys and refine management practices. Continued long-term monitoring, combined with targeted life history studies and demographic modeling, is needed to further investigate the population level effects of fishing yellow tang juveniles.     

Mesophotic coral ecosystems in the Hawaiian Archipelago

Efforts to map coral reef ecosystems in the Hawaiian Archipelago using optical imagery have revealed the presence of numerous scleractinian, zoothanthellate coral reefs at depths of 30–130+ m, most of which were previously undiscovered. Such coral reefs and their associated communities have been recently defined as mesophotic coral ecosystems (MCEs). Several types of MCEs are found in Hawai‘i, each of which dominates a different depth range and is characterized by a unique pattern of coral community structure and colony morphology. Although MCEs are documented near both ends of the archipelago and on many of the islands in between, the maximum depth and prevalence of MCEs in Hawai‘i were found to decline with increasing latitude. The Main Hawaiian Islands (MHI) had significantly deeper and greater percentages of scleractinian coral, and peaks in cover of both scleractinian corals and macroalgae occurred within depth bins 20 m deeper than in the Northwestern Hawaiian Islands (NWHI). Across the archipelago, as depth increased the combined percentage of living cover of mega benthic taxa declined sharply with increasing depth below 70 m, despite the widespread availability of hard substrate.     

Microevolution of canine influenza virus in shelters and its molecular epidemiology in the United States

Canine influenza virus (CIV) emerged around 2000 when an equine influenza virus (EIV) was transmitted to dogs in Florida. After 2003, the canine virus was carried by infected greyhounds to various parts of the United States and then became established in several large animal shelters, where it has continued to circulate. To better understand the evolution of CIV since its emergence, and particularly its microevolution in spatially restricted populations, we examined multiple gene segments of CIV from dogs resident in two large animal shelters in New York City during the period 2006 to 2009. In particular, we focused on viruses circulating in the two shelters in 2008 and 2009, which we found shared a common ancestor. While viruses in each shelter were generally monophyletic, we observed some gene flow between them. These shelter sequences were compared to earlier CIV isolates. The shelter viruses differed in 1 to 6 amino acids in each gene segment compared to viruses isolated in Florida between 2003 and 2005 and in Colorado in 2006 and 2008. A comparison of the sequences of equine and canine viruses revealed amino acid replacements that distinguished the viruses from the two hosts, but no clear evidence of positive selection indicative of host adaptation was detected, suggesting that any host range adaptation in CIV occurred early in the emergence of this virus or even before it transferred to dogs.     

Endoplasmic reticulum-associated degradation is required for cold adaptation and regulation of sterol biosynthesis in the yeast Saccharomyces cerevisiae

Endoplasmic reticulum-associated degradation (ERAD) mediates the turnover of short-lived and misfolded proteins in the ER membrane or lumen. In spite of its important role, only subtle growth phenotypes have been associated with defects in ERAD. We have discovered that the ERAD proteins Ubc7 (Qri8), Cue1, and Doa10 (Ssm4) are required for growth of yeast that express high levels of the sterol biosynthetic enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR). Interestingly, the observed growth defect was exacerbated at low temperatures, producing an HMGR-dependent cold sensitivity. Yeast strains lacking UBC7, CUE1, or DOA10 also assembled aberrant karmellae (ordered arrays of membranes surrounding the nucleus that assemble when HMGR is expressed at high levels). However, rather than reflecting the accumulation of abnormal karmellae, the cold sensitivity of these ERAD mutants was due to increased HMGR catalytic activity. Mutations that compromise proteasomal function also resulted in cold-sensitive growth of yeast with elevated HMGR, suggesting that improper degradation of ERAD targets might be responsible for the observed cold-sensitive phenotype. However, the essential ERAD targets were not the yeast HMGR enzymes themselves. The sterol metabolite profile of ubc7Delta cells was altered relative to that of wild-type cells. Since sterol levels are known to regulate membrane fluidity, the viability of ERAD mutants expressing normal levels of HMGR was examined at low temperatures. Cells lacking UBC7, CUE1, or DOA10 were cold sensitive, suggesting that these ERAD proteins have a role in cold adaptation, perhaps through effects on sterol biosynthesis.     

Computerised dystrophic muscle simulator: prospecting potential therapeutic strategies for muscle dystrophies using a virtual experimental model

Inherited muscle diseases are often characterised by widespread muscle damage in the body, limiting the clinical relevance of cell or gene therapy based upon direct injections into muscles. Recent studies have shown, however, that cells originating from the bone marrow are able to target necrosis-regeneration sites as they occur and, in addition, may also participate in the muscle regeneration after undergoing myogenic differentiation. Here, we present a computerised dystrophic muscle simulator that allows the prospecting of different scenarios of both disease evolution and appropriate employment of blood-borne cells as therapeutic shuttles. It provides the option of examining their use either to transfer a healthy gene into the tissue or to impart substances designed to boost its regeneration. One of the major advantages of this tool is that it offers the opportunity of visualising and composing therapeutic strategies in virtual paradigms in which severe clinical situations, not necessarily available in animal models, can be created. The dystrophic muscle simulator is freely accessible via the Genethon web site (www.genethon.fr), and in the online version via http:@www.wiley.co.uk/genmed.     

Within-person variability of the ratios of urinary 2-hydroxyestrone to 16alpha-hydroxyestrone in Caucasian women

The ratio of urinary 2-hydroxyestrone (2-OHE1) to 16alpha-hydroxyestrone (16alpha-OHE1) has been suggested as a potential biomarker for breast cancer risk. We evaluated within-person variability of this biomarker in ten healthy Caucasian women aged 23-58 years. Each study participant was asked to provide an overnight fasting morning urine sample once a week for an average of 8 weeks. These urine samples were assayed for 2-OHE1 and 16alpha-OHE1 by using competitive enzyme immunoassay kits purchased from the ImmunaCare Corporation. The coefficients of variation for urinary 2-OHE1/16alpha-OHE1 over the study period ranged from 13.7 to 59.6% (mean, 33.3%) in our study participants. There was a good correlation between the level of the urinary 2-OHE1/16alpha-OHE1 ratio in any single urine sample and the average ratio over the 8-week study period from the same woman, with the mean correlation coefficient of 0.85. These results indicated that the within-person variation of the 2-OHE1 to 16alpha-OHE1 ratio for most women was moderate and the level of this ratio in a single urine sample, in general, reflects reasonably well the level of this biomarker over a 2-month period.     

Structures of host range-controlling regions of the capsids of canine and feline parvoviruses and mutants

Canine parvovirus (CPV) and feline panleukopenia virus (FPV) differ in their ability to infect dogs and dog cells. Canine cell infection is a specific property of CPV and depends on the ability of the virus to bind the canine transferrin receptor (TfR), as well as other unidentified factors. Three regions in the capsid structure, located around VP2 residues 93, 300, and 323, can all influence canine TfR binding and canine cell infection. These regions were compared in the CPV and FPV capsid structures that have been determined, as well as in two new structures of CPV capsids that contain substitutions of the VP2 Asn-93 to Asp and Arg, respectively. The new structures, determined by X-ray crystallography to 3.2 and 3.3 A resolutions, respectively, clearly showed differences in the interactions of residue 93 with an adjacent loop on the capsid surface. Each of the three regions show small differences in structure, but each appears to be structurally independent of the others, and the changes likely act together to affect the ability of the capsid to bind the canine TfR and to infect canine cells. This emphasizes the complex nature of capsid alterations that change the virus-cell interaction to allow infection of cells from different hosts.