Fitness in Naturally Occurring and Restored Populations of a Grassland Plant Lychnis flos‐cuculi in a Swiss Agricultural Landscape

Wildflower seed mixtures are widely used for restoration of grasslands. However, the genetic and fitness consequences of using seed mixes have not been fully evaluated. Here, we studied the role of genetic diversity, origin (commercial regional seed mixtures, natural populations), and environmental conditions for the fitness of a grassland species Lychnis flos‐cuculi. First, we examined the relationship between genetic diversity, environmental parameters, and fitness in sown and natural populations of this species in a Swiss agricultural landscape. Second, we established an experiment in the study area and in an experimental garden to study the implications of local adaptation for plant fitness. Third, to examine the response of plants to different soil properties, we conducted an experiment in climate chambers, where we grew plants from sown and natural populations of L. flos‐cuculi as well as from seed suppliers on soils with different nutrient and moisture content. We detected no significant effect of genetic diversity on the fitness of sown and natural populations. There was no clear indication that plants from natural populations were better adapted to local environment than plants from sown populations or seed suppliers. However, plants of natural origin invested more into generative reproduction than plants from sown populations or seed suppliers. Furthermore, in the climate chamber, plants originating from natural populations tended to flower earlier. Our results indicate that using nonlocal seeds for habitat recreation may influence restoration success even if the seeds originate from the same seed zone as the restored site.     

Comparative Genome Analysis of Listeria Bacteriophages Reveals Extensive Mosaicism,Programmed Translational Frameshifting,and a Novel Prophage Insertion Site

The genomes of six Listeria bacteriophages were sequenced and analyzed. Phages A006, A500, B025, P35, and P40 are members of the Siphoviridae and contain double-stranded DNA genomes of between 35.6 kb and 42.7 kb. Phage B054 is a unique myovirus and features a 48.2-kb genome. Phage B025 features 3′ overlapping single-stranded genome ends, whereas the other viruses contain collections of terminally redundant, circularly permuted DNA molecules. Phages P35 and P40 have a broad host range and lack lysogeny functions, correlating with their virulent lifestyle. Phages A500, A006, and B025 integrate into bacterial tRNA genes, whereas B054 targets the 3′ end of translation elongation factor gene tsf. This is the first reported case of phage integration into such an evolutionarily conserved genetic element. Peptide fingerprinting of viral proteins revealed that both A118 and A500 utilize +1 and −1 programmed translational frameshifting for generating major capsid and tail shaft proteins with C termini of different lengths. In both cases, the unusual +1 frameshift at the 3′ ends of the tsh coding sequences is induced by overlapping proline codons and cis-acting shifty stops. Although Listeria phage genomes feature a conserved organization, they also show extensive mosaicism within the genome building blocks. Of particular interest is B025, which harbors a collection of modules and sequences with relatedness not only to other Listeria phages but also to viruses infecting other members of the Firmicutes. In conclusion, our results yield insights into the composition and diversity of Listeria phages and provide new information on their function, genome adaptation, and evolution.The opportunistic pathogen Listeria monocytogenes is ubiquitous in nature and can become endemic in food processing environments, causing contamination of dairy products, meats, vegetables, and processed ready-to-eat food (14). L. monocytogenes is the causative agent of epidemic and sporadic listeriosis. The risk of infection is markedly increased among immunocompromised patients, newborns, pregnant women, and the elderly and is associated with a mortality rate of about 20 to 30% (37).Although all strains of L. monocytogenes are considered potentially pathogenic, epidemiological evidence has shown that certain serovars are more frequently associated with both sporadic cases and larger food-borne outbreaks. However, genetic variation within the virulence genes of wild-type strains appears to be limited and could not be directly linked to differences in pathogenicity (30) or environmental distribution.It is becoming increasingly clear that bacteriophages have an important role in bacterial biology, diversity, and evolution, as indicated by the advances in genome sequencing which revealed a high incidence of phage-related sequences in bacterial genomes. Many phages have been described for the genus Listeria, and lysogeny appears to be widespread (28). Availability of the genome sequences of different L. monocytogenes and L. innocua strains also revealed the presence of several different putative prophages in the genomes of these bacteria, constituting up to 7% of the coding capacities of the genomes (15, 32). Although the genomes of L. monocytogenes were found to be essentially syntenic, a significant portion of sequence variability is apparently based upon phage insertions and subsequent rearrangements. Investigations of prophage contributions to population dynamics in Salmonella suggest that prophages can improve the competitive fitness of the lysogenized host strains (5). This type of selective pressure also results in diversification and generation of new strains by lysogenic conversion. In the case of Listeria, however, the potential influence of prophages on their host strains, such as phenotypic variation or provision of selective benefits, has not been investigated. To gain more insight in bacteriophage-host interactions and the molecular biology and characteristics of Listeria phages, more information on the structure, information content, and variability of different Listeria phage genomes is required.Although a number of Listeria phages have been isolated and described (25, 27, 42), only limited information was available at the sequence level for phages PSA, A118, A511, and P100 (9, 19, 26, 41). As the result of a comprehensive study to determine the diversity of this group of bacterial viruses, we here report the complete nucleotide sequences of a representative set of six different Listeria phages from the Siphoviridae (A006, A500, B025, P35, and P40) and Myoviridae (B054) families in the order Caudovirales. In addition to molecular and in silico analyses, we also determined the physical genome structures and attachment loci of the temperate phages, and we describe integration of the B054 prophage into a highly conserved elongation factor gene. Another interesting finding is the unusual decoding used by some of the phages, which use programmed frameshifting to generate C-terminally modified structural proteins required for assembly of the capsid and tail.     

CDC2/SPDY transiently associates with endoplasmic reticulum exit sites during oocyte maturation

Background  

Fibronectin 1 (FN1), a glycoprotein component of the extracellular matrix, exerts different functions during reproductive processes such as fertilisation, gastrulation and implantation. FN1 expression has been described to increase significantly from the morula towards the early blastocyst stage, suggesting that FN1 may also be involved in early blastocyst formation. By alternative splicing at 3 defined regions, different FN1 isoforms are generated, each with a unique biological function. The analysis of the alternative FN1 splicing on the one hand and the search for candidate FN1 receptors on the other hand during early bovine embryo development may reveal more about its function during bovine preimplantation embryo development.     

Prostasin regulates epithelial monolayer function: cell-specific Gpld1-mediated secretion and functional role for GPI anchor

Prostasin, a trypsinlike serine peptidase, is highly expressed in prostate, kidney, and lung epithelia, where it is bound to the cell surface, secreted, or both. Prostasin activates the epithelial sodium channel (ENaC) and suppresses invasion of prostate and breast cancer cells. The studies reported here establish mechanisms of membrane anchoring and secretion in kidney and lung epithelial cells and demonstrate a critical role for prostasin in regulating epithelial monolayer function. We report that endogenous mouse prostasin is glycosylphosphatidylinositol (GPI) anchored to the cell surface and is constitutively secreted from the apical surface of kidney cortical collecting duct cells. Using site-directed mutagenesis, detergent phase separation, and RNA interference approaches, we show that prostasin secretion depends on GPI anchor cleavage by endogenous GPI-specific phospholipase D1 (Gpld1). Secretion of prostasin by kidney and lung epithelial cells, in contrast to prostate epithelium, does not depend on COOH-terminal processing at conserved Arg³²². Using stably transfected M-1 cells expressing wild-type, catalytically inactive, or chimeric transmembrane (not GPI)-anchored prostasins we establish that prostasin regulates transepithelial resistance, current, and paracellular permeability by GPI anchor- and protease activity-dependent mechanisms. These studies demonstrate a novel role for prostasin in regulating epithelial monolayer resistance and permeability in kidney epithelial cells and, furthermore, show specifically that prostasin is a critical regulator of transepithelial ion transport in M-1 cells. These functions depend on the GPI anchor as well as the peptidase activity of prostasin. These studies suggest that cell-specific Gpld1- or peptidase-dependent pathways for prostasin secretion may control prostasin functions in a tissue-specific manner. serine protease; epithelial sodium channel; glycosylphosphatidylinositol anchor; transepithelial resistance; tight junction     

On the efficiency and correction of vertically oriented blunt bioaerosol samplers in moving air

The aspiration efficiency of vertical and wind-oriented Air-O-Cell samplers was investigated in a field study using the pollen of hazel, sweet chestnut and birch. Collected pollen numbers were compared to measurements of a Hirst-type Burkard spore trap. The discrepancy between pollen counts is substantial in the case of vertical orientation. The results indicate a strong influence of wind velocity and inlet orientation relative to the freestream on the aspiration efficiency. Various studies reported on inertial effects on aerosol motion as function of wind velocity. The measurements were compared to a physically based model for the limited case of vertical blunt samplers. Additionally, a simple linear model based on pollen counts and wind velocity was developed. Both correction models notably reduce the error of vertically oriented samplers, whereas only the physically based model can be used on independent datasets. The study also addressed the precision error of the instruments used, which was substantial for both sampler types.     

No skeletal dysplasia in the nariokotome boy KNM‐WT 15000 (homo erectus)—A reassessment of congenital pathologies of the vertebral column

The Nariokotome boy skeleton KNM‐WT 15000 is the most complete Homo erectus fossil and therefore is key for understanding human evolution. Nevertheless, since Latimer and Ohman (2001) reported on severe congenital pathology in KNM‐WT 15000, it is questionable whether this skeleton can still be used as reference for Homo erectus skeletal biology. The asserted pathologies include platyspondylic and diminutive vertebrae implying a disproportionately short stature; spina bifida; condylus tertius; spinal stenosis; and scoliosis. Based on this symptom complex, the differential diagnosis of spondyloepiphyseal dysplasia tarda, an extremely rare form of skeletal dysplasia, has been proposed. Yet, our reanalysis of these pathologies shows that the shape of the KNM‐WT 15000 vertebrae matches that of normal modern human adolescents. The vertebrae are not abnormally flat, show no endplate irregularities, and thus are not platyspondylic. As this is the hallmark of spondyloepiphyseal dysplasia tarda and related forms of skeletal dysplasia, the absence of platyspondyly refutes axial dysplasia and disproportionate dwarfism. Furthermore, we neither found evidence for spina bifida occulta nor manifesta, whereas the condylus tertius, a developmental anomaly of the cranial base, is not related to skeletal dysplasias. Other fossils indicate that the relatively small size of the vertebrae and the narrow spinal canal are characteristics of early hominins rather than congenital pathologies. Except for the recently described signs of traumatic lumbar disc herniation, the Nariokotome boy fossil therefore seems to belong to a normal Homo erectus youth without pathologies of the axial skeleton. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.     

The invasion of plant communities following extreme weather events under ambient and elevated temperature

Although the problem of plant invasions is expected to increase with climate change, there is as yet little experimental evidence, in particular, for the effects of extreme weather events. We established communities of European meadow species, which were subjected to warming and extreme event (drought and deluge) treatments in a factorial design at an experimental garden in Zurich, Switzerland. Phylogenetically matched pairs of native and alien species (Bromus erectus, B. inermis, Trifolium pratense, T. hybridum, Lactuca serriola, and Conyza canadensis) were introduced into the communities to test if invader performance is favored by warming and extreme events, and if alien invaders perform better than native colonizers. With a warming of on average 0.3?°C, a higher cover of native plant communities was observed, while drought decreased cover in the short-term and lowered biomass. Germination, survival, and growth of the introduced species were lower under elevated temperature. Survival of all pairs and growth of Trifolium was greater in drought pots, while deluge had no effect. While the alien species showed a faster rate of increase in the number of leaves, mortality of alien species was greater than of native species. Overall, the performance of the focal species varied much more among taxonomic groups than native/alien provenances. The results suggest that with climate change, different types of extreme events will differ in the severity of their effects on native plant communities. Meanwhile, the effects of climate change on plant invasions are more likely to operate indirectly through the impacts on native vegetation.     

Relationships Between Soil Microorganisms, Plant Communities, and Soil Characteristics in Chinese Subtropical Forests

We analyzed the influence of above- and belowground factors on the soil microbial community in a Chinese subtropical forest, one of the most diverse biomes in the northern hemisphere. Soil samples were taken at different depths from four replicate comparative study plots in each of three forest age classes (young 10–40?years, medium 40–80?years, old ≥80?years). Microbial biomass and community structure were then determined using phospholipid fatty acid (PLFA) analysis, and basal respiration and microbial biomass carbon (C_mic) were determined by substrate-induced respiration. These data were then related to plant community and soil variables using non-metric multidimensional scaling analysis and post-hoc permutational correlations. We found that microbial lipid composition and abundance were not related to forest age class. Instead, microbial lipid composition and abundance were related to factors reflecting primary production, i.e., percent litter cover, percent dead wood cover, and percent tree layer cover. Specifically, the relative abundance (mol fraction) of indicators for arbuscular mycorrhizal fungi, Gram-positive and Gram-negative bacteria were positively significantly correlated with percent litter cover. We also found that the biomass of all microbial groups and total PLFA were negatively significantly related to percent deadwood cover. In addition, $ {\text{pH}}_{{{\text{H}}_{ 2} {\text{O}}}} $ was the only soil parameter that was correlated significantly to microbial biomass. Our results indicate that overarching ecological factors such as plant productivity and soil pH are important factors influencing the soil microbial community, both in terms of biomass and of community composition in this subtropical ecosystem.     

General Relationships between Abiotic Soil Properties and Soil Biota across Spatial Scales and Different Land-Use Types

Very few principles have been unraveled that explain the relationship between soil properties and soil biota across large spatial scales and different land-use types. Here, we seek these general relationships using data from 52 differently managed grassland and forest soils in three study regions spanning a latitudinal gradient in Germany. We hypothesize that, after extraction of variation that is explained by location and land-use type, soil properties still explain significant proportions of variation in the abundance and diversity of soil biota. If the relationships between predictors and soil organisms were analyzed individually for each predictor group, soil properties explained the highest amount of variation in soil biota abundance and diversity, followed by land-use type and sampling location. After extraction of variation that originated from location or land-use, abiotic soil properties explained significant amounts of variation in fungal, meso- and macrofauna, but not in yeast or bacterial biomass or diversity. Nitrate or nitrogen concentration and fungal biomass were positively related, but nitrate concentration was negatively related to the abundances of Collembola and mites and to the myriapod species richness across a range of forest and grassland soils. The species richness of earthworms was positively correlated with clay content of soils independent of sample location and land-use type. Our study indicates that after accounting for heterogeneity resulting from large scale differences among sampling locations and land-use types, soil properties still explain significant proportions of variation in fungal and soil fauna abundance or diversity. However, soil biota was also related to processes that act at larger spatial scales and bacteria or soil yeasts only showed weak relationships to soil properties. We therefore argue that more general relationships between soil properties and soil biota can only be derived from future studies that consider larger spatial scales and different land-use types.