Flowering of Contrasting White Clover Varieties in Relation to Temperature in Controlled Environments

Effects of temperature on floral initiation of ten white clovervarieties growing in controlled environments are described.Plants grown under long days (16 h) were subjected to constanttemperatures of 26, 18 and 10 ^°C. Relationships betweenmorphological and physiological traits and flowering were examined. Most plants flowered at the two higher temperatures but only10 per cent of plants flowered at 10 ^°C. Larger leaved typestended to produce more reproductive buds per stolon at the highertemperatures than did smaller leaved varieties. Of the floral characters studied, floret number was least affectedby temperature. Ovule number and peduncle length were greatestat 18 ^°C. Variation in, and absolute level of nectar secretionwas greatest at the highest temperature. Trifolium repens, white clover, flowering, temperature     

Soil carbon stabilization in jack pine stands along the Boreal Forest Transect Case Study

Boreal forests, containing >20% of the total organic carbon (OC) present at the surface of the Earth, are expected to be highly vulnerable to global warming. The objective of this study was to compare soil OC stocks and chemistry in jack pine stands located along a latitudinal climatic transect in central Canada. Total OC stocks (0–1 m) increased with decreasing mean annual temperature (MAT). We used a combination of physical fractionation of soil OC pools, ¹³C isotopic determination and cross‐polarization, magic‐angle spinning ¹³C nuclear magnetic resonance (NMR) spectroscopy to further characterize OC composition at all sites. Soil OC was dominated by labile pools. As illustrated by the C/N ratios, δ¹³C data and results from the ¹³C NMR analysis, the light fraction showed little alteration within the soil profiles. Instead, this fraction reflected the importance of fresh litter inputs and showed an increase in root contribution with depth. As opposed to the light fraction, the clay‐ and silt‐stabilized OC exhibited an increase in δ¹³C and a decrease in C/N with depth, indicating an increase in its degree of decomposition. These changes with depth were more marked at the southern than the northern sites. Results hence suggest that if the MAT were to increase in the northern boreal forest the overall jack pine soil OC stocks would decrease but the remaining OC would become more decomposed, and likely more stabilized than what is currently present within the soils.     

Comparative genomic analysis reveals significant enrichment of mobile genetic elements and genes encoding surface structure-proteins in hospital-associated clonal complex 2 Enterococcus faecalis

Background  

Enterococci rank among the leading causes of nosocomial infections. The failure to identify pathogen-specific genes in Enterococcus faecalis has led to a hypothesis where the virulence of different strains may be linked to strain-specific genes, and where the combined endeavor of the different gene-sets result in the ability to cause infection. Population structure studies by multilocus sequence typing have defined distinct clonal complexes (CC) of E. faecalis enriched in hospitalized patients (CC2, CC9, CC28 and CC40).     

Regenerative potential of human muscle stem cells in chronic inflammation

Introduction

Chronic inflammation is a profound systemic modification of the cellular microenvironment which could affect survival, repair and maintenance of muscle stem cells. The aim of this study was to define the role of chronic inflammation on the regenerative potential of satellite cells in human muscle.

Methods

As a model for chronic inflammation, 11 patients suffering from rheumatoid arthritis (RA) were included together with 16 patients with osteoarthritis (OA) as controls. The mean age of both groups was 64 years, with more females in the RA group compared to the OA group. During elective knee replacement surgery, a muscle biopsy was taken from the distal musculus vastus medialis. Cell populations from four RA and eight OA patients were used for extensive phenotyping because these cell populations showed no spontaneous differentiation and myogenic purity greater than 75% after explantation.

Results

After mononuclear cell explantation, myogenic purity, viability, proliferation index, number of colonies, myogenic colonies, growth speed, maximum number of population doublings and fusion index were not different between RA and OA patients. Furthermore, the expression of proteins involved in replicative and stress-induced premature senescence and apoptosis, including p16, p21, p53, hTERT and cleaved caspase-3, was not different between RA and OA patients. Mean telomere length was shorter in the RA group compared to the OA group.

Conclusions

In the present study we found evidence that chronic inflammation in RA does not affect the in vitro regenerative potential of human satellite cells. Identification of mechanisms influencing muscle regeneration by modulation of its microenvironment may, therefore, be more appropriate.     

Cnidarian taphonomy and affinities of the Ediacara biota

Plaster impressions and sand casts of extant medusae, a chondrophoran, and a pennatulid share basic structural characteristics with fossils in the Upper Proterozoic Ediacara assemblage. Impressions of extant medusae and Proterozoic circular impressions show general similarities in arrangement and position of radial and concentric structures and a central raised boss. However, annular rings and radial grooves are more numerous in the Proterozoic fossils and strongly folded or deformed fossils are rare as compared with impressions of modem medusae. Recent pennatulids yield impressions that are more deformed and irregular than the Proterozoic genus Charniodiscus. The greater frequency of deformation of most simulated fossil medusoids relative to Precambrian circular impressions implies that Proterozoic medu-soids were substantially stiffer than many modern taxa of comparable sizes. Many fossils with abundant circular rings have no constructional counterparts among the extant forms studied here and their medusoid affinities should remain in doubt. The structural simplicity of impressions of Ediacara organisms and extant cnidarians suggests that their mutual similarities may be due to convergence. However, there is no compelling morphological reason to reject the claim that some Proterozoic fossils may share affinities with living cnidarians. □ Taphonomy. Ediacara biota, cnidarians, phylogenetic relationships.     

The risk for depression in patients with ankylosing spondylitis: a population-based cohort study

Introduction

Depression is frequent in ankylosing spondylitis (AS) patients. However, epidemiological data about the potential increase in risk are lacking. This study compares the rate of doctor-diagnosed depression in a well defined cohort of AS patients to the general population seeking care.

Methods

The Skåne Healthcare Register comprises healthcare data of each resident in Region Skåne, Sweden (population 1.2 million), including ICD-10 diagnoses. Using physician coded consultation data from years 1999 to 2011, we calculated depression consultation rates for all AS patients. We obtained standardized depression-rate ratios by dividing the observed depression rate in AS patients by the expected rate based on the corresponding age- and sex-specific rates of depression in the general population seeking care. A ratio >1 equals a higher rate of depression among AS patients.

Results

The AS cohort consisted of 1738 subjects (65% men) with a mean age of 54 years. The reference population consisted of 967,012 subjects. During the 13-year observation period 10% (n = 172) of the AS cohort had a doctor-diagnosed depression compared to 6% (n = 105) to be expected. The standardized estimate of depression-rate ratio was 1.81 (95% confidence interval 1.44 to 2.24) in women men and 1.49 (1.20 to 1.89) in men.

Conclusions

The rate of doctor-diagnosed depression is increased about 80% in female and 50% in male AS patients. Future challenges are to timely identify and treat the AS patients who suffer from depression.