An improved method for determining enantiomeric excess by 13C‐NMR in chiral liquid crystal media

By using a combination of inverse gated ¹H decoupled ¹³C‐NMR experiments 1 with short acquisition times and NMR Cryo‐probe technology, the sample requirements and experimental times necessary to accurately measure enantiomeric excess of small chiral molecules has been reduced 16‐fold. Quality ¹³C‐NMR spectra can now be obtained from a 1 to 5 mg sample in 12 minutes. The enantiomeric excess determination achieved from the average integration of all the ¹³C‐resonances in the spectrum is comparable to enantiomeric excess measured by chiral SFC. The advantage of the NMR method is that enantiomeric excess can rapidly be measured in situ on practical amounts of enantioselective reaction products without the need for chromatographic separation or chemical modification and with substantially less solvent waste. Chirality, 2010. © 2010 Wiley‐Liss, Inc.     

Comparative immunofluorescence and ultrastructural analysis of microtubule organization in Uronema sp., Klebsormidium flaccidum, K. subtilissimum, Stichococcus bacillaris and S. chloranthus (Chlorophyta)

A detailed comparative examination of microtubule (MT) organization in interphase and dividing cells of Uronema sp., Klebsormidium flaccidum, K. subtilissimum, Stichococcus bacillaris and S. chloranthus was made using tubulin immunofluorescence and transmission electron microscopy (TEM). During interphase all the species bear a well-organized cortical MT system, consisting of parallel bundles with different orientations. In Uronema sp. the cortical MT bundles are longitudinally oriented, whereas in the other species they are in transverse orientation to the axis of the cells. Considerable differences in MT organization were also observed during stages of mitosis, mainly preprophase, as well as cytokinesis. In Uronema sp., a particular radial MT assembly is organized during preprophase-early prophase, which was not observed in the other species. In Stichococcus a fine MT ring surrounded the nucleus during preprophase and prophase. An MT ring, together with single cytoplasmic MTs, was also found associated with the developing diaphragm during cytokinesis in Stichococcus. A phycoplast participates in cytokinesis in Uronema sp., but not in the other species. In Uronema sp. the centrosome functions as a microtubule organizing center (MTOC) during mitosis, but not during interphase and cytokinesis. The phylogenetic significance of these differences is discussed in combination with SSU/ITS sequencing and other, existing molecular data.     

Photomorphogenic reactions in geranium (Pelargonium x hortotum) plants stimulated by brief exposures of ultraviolet-C irradiation

Of all environmental factors that influence plant growth and development, light and other regions of the electromagnetic spectrum are most essential. In the present study, the effects of ultraviolet-C (UV-C) irradiation on two cultivars, Victor and Glacis, of pot grown geranium (Pelargonium x hortotum) plants were evaluated. Two-year experimental data showed that low doses of UV-C (i.e. 0.5–5.0?kJ?m^?2) irradiation led to photomorphogenic changes recorded as increases of fresh and dry weight, number of lateral stems and number of inflorescences formed. Although changes were recorded for both cultivars, responses to UV-C were population dependent with cv. Glacis appearing to be the more responsive one. The number of inflorescences formed on UV-C irradiated cv. Glacis plants was significantly (P?<?0.05) higher to that of the non-irradiated controls throughout the pot trials in 2010 and 2011. For example, in the 2010 pot trial, exposure to 2.5?kJ?m^?2 UV-C resulted in the increase of inflorescences by 75?%. Additionally, the number of lateral stems on UV-C irradiated plants of cvs. Victor and Glacis increased by 122?% and 64?%, respectively. Temperatures and PARs during the 2-year pot trials varied to a considerable level and seem to have affected floral development and growth of both cultivars. However, only in cv. Glacis the effect on floral development was significant as cv. Victor geraniums grown in 2010 and 2011 showed comparable numbers of inflorescences. Our results show that brief exposures of geranium plants to UV-C may facilitate the production of high quality final products in a cost effective and environmentally friendly way.     

Characteristics of the soil seed bank in Mediterranean temporary ponds and its role in ecosystem dynamics

Species in temporary ponds overcome periods of unfavorable weather conditions by building up a large seed bank. With this strategy, the species diversity of ponds is preserved and information on their dynamics and structure is retained. Little is known about the characteristics, spatial patterns and role in the vegetation dynamics of the soil seed banks of Mediterranean temporary ponds, which are regarded as priority habitats under protection. We studied two sites of western Crete: Omalos, a mountain plateau at 1,060 m a.s.l. and Elafonisos, located near the coast at 60 m a.s.l. The seed bank was surveyed along transects using the germination method. Aboveground vegetation was measured on quadrats along the same transects. Canonical Correspondence Analysis (CCA) was run to define the zonation patterns. High density and species richness were recorded in both sites, with an average of 75,662 seeds/m² found in Omalos and 22,941 seeds/m² in Elafonisos. The community composition of both sites was remarkably different but in both locations perennial species were inconspicuous while annuals, prevailed in the seed banks. An important array of protected or rare species as well as several others which were absent from the vegetation were hosted in the soil seed banks, thereby rendering a low similarity between their composition. Soil seed banks in these ecosystems indicated a spatial heterogeneity that mirrored the aboveground vegetation distribution, sorted along the moisture gradient by their tolerance to flooding. Soil seed banks play a key role in the vegetation recovery after summer drought. The acts of preserving the soil seed bank and ensuring a transient flooding regime are essential to protect the unique vegetation communities of Mediterranean temporary ponds.     

Association between adolescent idiopathic scoliosis prevalence and age at menarche in different geographic latitudes

Background

Age at menarche is considered a reliable prognostic factor for idiopathic scoliosis and varies in different geographic latitudes. Adolescent idiopathic scoliosis prevalence has also been reported to be different in various latitudes and demonstrates higher values in northern countries. A study on epidemiological reports from the literature was conducted to investigate a possible association between prevalence of adolescent idiopathic scoliosis and age at menarche among normal girls in various geographic latitudes. An attempt is also made to implicate a possible role of melatonin in the above association.

Material-methods

20 peer-reviewed published papers reporting adolescent idiopathic scoliosis prevalence and 33 peer-reviewed papers reporting age at menarche in normal girls from most geographic areas of the northern hemisphere were retrieved from the literature. The geographic latitude of each centre where a particular study was originated was documented. The statistical analysis included regression of the adolescent idiopathic scoliosis prevalence and age at menarche by latitude.

Results

The regression of prevalence of adolescent idiopathic scoliosis and age at menarche by latitude is statistically significant (p < 0.001) and are following a parallel declining course of their regression curves, especially in latitudes northern than 25 degrees.

Conclusion

Late age at menarche is parallel with higher prevalence of adolescent idiopathic scoliosis. Pubarche appears later in girls that live in northern latitudes and thus prolongs the period of spine vulnerability while other pre-existing or aetiological factors are contributing to the development of adolescent idiopathic scoliosis. A possible role of geography in the pathogenesis of idiopathic scoliosis is discussed, as it appears that latitude which differentiates the sunlight influences melatonin secretion and modifies age at menarche, which is associated to the prevalence of idiopathic scoliosis.     

The tomato NBARC-LRR protein Prf interacts with Pto kinase in vivo to regulate specific plant immunity

Immunity in tomato (Solanum lycopersicum) to Pseudomonas syringae bacteria expressing the effector proteins AvrPto and AvrPtoB requires both Pto kinase and the NBARC-LRR (for nucleotide binding domain shared by Apaf-1, certain R gene products, and CED-4 fused to C-terminal leucine-rich repeats) protein Prf. Pto plays a direct role in effector recognition within the host cytoplasm, but the role of Prf is unknown. We show that Pto and Prf are coincident in the signal transduction pathway that controls ligand-independent signaling. Pto and Prf associate in a coregulatory interaction that requires Pto kinase activity and N-myristoylation for signaling. Pto interacts with a unique Prf N-terminal domain outside of the NBARC-LRR domain and resides in a high molecular weight recognition complex dependent on the presence of Prf. In this complex, both Pto and Prf contribute to specific recognition of AvrPtoB. The data suggest that the role of Pto is confined to the regulation of Prf and that the bacterial effectors have evolved to target this coregulatory molecular switch.     

Repeated contractions alter the geometry of human skeletal muscle.

The aim of this study was to investigate the effect of repeated contractions on the geometry of human skeletal muscle. Six men performed two sets (sets A and B) of 10 repeated isometric plantarflexion contractions at 80% of the moment generated during plantarflexion maximal voluntary contraction (MVC), with a rest interval of 15 min between sets. By use of ultrasound, the geometry of the medial gastrocnemius (MG) muscle was measured in the contractions of set A and the displacement of the MG tendon origin in the myotendinous junction was measured in the contractions of set B. In the transition from the 1st to the 10th contractions, the fascicular length at 80% of MVC decreased from 34 +/- 4 (means +/- SD) to 30 +/- 3 mm (P < 0.001), the pennation angle increased from 35 +/- 3 to 42 +/- 3 degrees (P < 0.001), the myotendinous junction displacement increased from 5 +/- 3 to 10 +/- 3 mm (P < 0.001), and the average fascicular curvature remained constant (P > 0.05) at approximately 4.3 m(-1). No changes (P > 0.05) were found in fascicular length, pennation angle, and myotendinous junction displacement after the fifth contraction. Electrogoniometry showed that the ankle rotated by approximately 6.5 degrees during contraction, but no differences (P > 0.05) were obtained between contractions. The present results show that repeated contractions induce tendon creep, which substantially affects the geometry of the in-series contracting muscles, thus altering their potential for force and joint moment generation.     

A patch of surface-exposed residues mediates negative regulation of immune signaling by tomato Pto kinase

Tomato (Lycopersicon esculentum) Pto kinase specifically recognizes the Pseudomonas effector proteins AvrPto and AvrPtoB, leading to induction of defense responses and hypersensitive cell death. Structural modeling of Pto combined with site-directed mutagenesis identified a patch of surface-exposed residues required for native regulation of signaling. Mutations in this area resulted in constitutive gain-of-function (CGF) forms of Pto that activated AvrPto-independent cell death via the cognate signaling pathway. The patch overlaps the peptide binding region of the kinase catalytic cleft and is part of a broader region required for interaction with bacterial effectors. We propose that the negative regulatory patch is normally occupied by a peptide that represses Pto signaling. Furthermore, we found that Pto kinase activity was required for Avr-dependent activation but dispensable for signaling by CGF forms of Pto. This suggests that Pto signals by a conformational change rather than phosphorylation of downstream substrates in the defense signaling pathway.     

Changes in metalloproteinases in healthy normotensive patients with high-normal blood pressure

INTRODUCTION: High-normal blood pressure (HNBP) seems to be related to increased cardiovascular risk in healthy, normotensive subjects, while essential hypertension is associated with an increase in extracellular matrix content, especially fibrillar collagen type I. The aim of our study was to investigate whether collagen degradation is altered in healthy normotensives with HNBP, and whether this alteration could be related to disturbances in the matrix metalloproteinases plasma concentration, and to compare the findings to those of healthy normotensives with normal blood pressure (NBP) levels, matched for age, sex and BMI. METHODS: Twenty six (14 males, 12 females) healthy, normotensive patients with HNBP, mean age 52 +/- 5 yrs, and BMI 23 +/- 1.5 kg/m(2) (group A), and 24, healthy normotensive patients (13 males, 11 females) with NBP, mean age 53 +/- 6 yrs, and BMI 23.2 +/- 1.4 kg/m(2) (group B), were studied. The two groups were matched for age, sex and BMI. Plasma levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitors (TIMP-1) and (TIMP-4) were determined by relevant ELISA in the study population. RESULTS: Plasma MMP-9 levels were significantly higher, while TIMP-1 and TIMP-4 levels were significantly lower in group A compared to group B, (MMP-9 579 +/- 147 versus 294 +/- 111 ng/mL, TIMP-1 178 +/- 45 versus 237 +/- 35 ng/mL p < 0.01, and TIMP-4 2.2 +/- 1.4 versus 4.4 +/- 2.1 p < 0.04 respectively). CONCLUSIONS: Our findings suggest that healthy normotensives with high-normal blood pressure have significantly increased MMP-9 and decreased TIMP-1 and TIMP-4 plasma levels compared to healthy normotensives with normal blood pressure. These findings need further investigation.