Regional differences in prostaglandin E2 and nitric oxide production in the knee meniscus in response to dynamic compression

Injury or loss of the knee meniscus is associated with altered joint stresses that lead to progressive joint degeneration. The goal of this study was to determine if dynamic mechanical compression influences the production of inflammatory mediators by meniscal cells. Dynamic compression increased prostaglandin E2 (PGE(2)) and nitric oxide (NO) production over a range of stress magnitudes (0.0125-0.5 MPa) in a manner that depended on stress magnitude and zone of tissue origin. Inner zone explants showed greater increases in PGE(2) and NO production as compared to outer zone explants. Meniscal tissue expressed NOS2 and NOS3 protein, but not NOS1. Mechanically induced NO production was blocked by NOS inhibitors, and the non-selective NOS inhibitor L-NMMA augmented PGE(2) production in the outer zone only. These findings suggest that the meniscus may serve as an intra-articular source of pro-inflammatory mediators, and that alterations in the magnitude or distribution of joint loading could significantly influence the production of these mediators in vivo.     

Aggregate Size Distribution of Ammonia-Oxidizing Bacteria and Archaea at Different Landscape Positions

To quantify the spatial distribution of ammonia-oxidizing bacteria (AOB) and archaea (AOA) and to determine nitrification activity in soil aggregates along a landscape, soil samples were collected from three landscape positions (shoulder, backslope, and toeslope) at two pasture sites with contrasting climatic conditions. The abundance of AOB and AOA was estimated by quantifying their respective bacterial and archaeal amoA gene copies using real-time polymerase chain reaction. Soil organic C (SOC), total N (TN), and the potential nitrification rate (PNR) were measured in aggregate size ranges (4–1, 1–0.25, and 0.25–0.05 mm). At site 1, a decreasing trend in PNR was observed as the size of aggregates decreased. Both bacterial and archaeal amoA genes were higher in the macroaggregates (4–1 and 1–0.25 mm) than in the microaggregates (0.25–0.05 mm) along the landscape. At site 2, PNR was higher in the smallest size of aggregates. In the 0.25–0.05-mm fraction, the abundance of bacterial and archaeal amoA genes was equal to, or greater than, those found in larger aggregate sizes. The relative abundance of archaeal amoA gene and the PNR correlated with relative SOC and TN contents along the landscapes. The positive relationship between relative archaeal amoA gene abundance and PNR suggests that nitrification in the studied pastures is probably driven by ammonia-oxidizing Thaumarchaeota.     

Kinetic analysis of nanoparticle‐protein interactions using a plasmon waveguide resonance

A plasmon waveguide resonance (PWR) sensor is proposed for studying the interaction between gold nanoparticles and proteins. The ability of the PWR sensor to operate in both TM and TE Polarizations, i.e. its polarization diversity, facilitates the simultaneous spectroscopy of the nanoparticles surface reactions using both polarizations. The response of each polarization to streptavidin‐biotin binding at the surface of gold nanoparticles is investigated in real time. Finally, using the principles of multimode spectroscopy, the nanoparticle's surface reactions are decoupled from the bulk solution refractive index variations.

Schematic diagram of the NP‐modified PWR sensor     

A recessive ryanodine receptor 1 mutation in a CCD patient increases channel activity

Ryanodine receptors plays a crucial role in skeletal muscle excitation–contraction coupling by releasing calcium ions required for muscle contraction from the sarcoplasmic reticulum. At least three phenotypes associated with more than 100 RYR1 mutations have been identified; in order to elucidate possible pathophysiological mechanisms of RYR1 mutations linked to neuromuscular disorders, it is essential to define the mutation class by studying the functional properties of channels harbouring clinically relevant amino acid substitutions. In the present report we investigated the functional effects of the c.7304G > T RYR1 substitution (p.Arg2435Leu) found in a patient affected by central core disease. Both parents were heterozygous for the substitution while the proband was homozygous. We characterized Ca²⁺ homeostasis in myoD transduced myotubes from controls, the heterozygous parents and the homozygous proband expressing the endogenous mutation. We also expressed the recombinant mutant channels in heterologous cells and characterized their [³H]ryanodine binding and single channel properties. Our results show that the p.Arg2435Leu substitution affects neither the resting [Ca²⁺], nor the sensitivity of the ryanodine receptor to pharmacological activators, but rather reduces the release of Ca²⁺ from intracellular stores induced by pharmacological activators as well as by KCl via the voltage sensing dihydropyridine receptor.     

An overview of Iranian mangrove ecosystems, northern part of the Persian Gulf and Oman Sea

Iranian mangrove forests occur between longitude 25°19′ and 27°84′, in the north part of the Persian Gulf and Oman Sea. In 2002, it was estimated that 93.37 km² of Iranian shorelines were covered with mangrove forests, with the largest area (67.5 km²) occurring between the Khamir Port and the northwest side of Qeshm Island, and the smallest area (0.01 km²) in the Bardestan estuary. Only two species of mangrove are found in the Persian Gulf: Avicennia marina from Avicenniaceae and Rhizophora macrunata from Rhizophoraceae. A. marina is the dominant specie in these forests whereas Rh. macrunata is found only in the Sirik region. Overexploitation of mangrove leaves and oil pollution are the main causes of mangrove destruction in this region.     

Herbaceous production in South India—limiting factors and implications for large herbivores

This study’s goal was to better understand the growth pattern and limitations of the herbaceous production that supports South India’s rich large herbivore grazer assemblage. We conducted a fully factorial nitrogen and water (three levels each) treatment field experiment in the herbivore rich South Indian Western Ghats region to determine the seasonal pattern and the extent to which nitrogen and water availability limit herbaceous production. Graminoid production was found to be nitrogen limited. Despite low rainfall, additional water did not significantly increase overall biomass production nor extend growth in the dry season. Accumulated standing biomass was highest in the late wet season (November) and lowest in the dry season (May). Leaf nitrogen was highest in the early wet season (June) and lowest in the late dry season (March). Grazing had a positive effect on grass production by extending the growing season. Biomass production and graminoid leaf nitrogen concentration levels in the study area were similar to other tropical areas in the world. Also similar to other tropical large herbivore areas, the dry season poses an annual challenge for large herbivores in the study area —particularly the smaller bodied species—to satisfy their nutrient requirements.     

Geometrical correlations in the nucleosomal DNA conformation and the role of the covalent bonds rigidity

We develop a simple elastic model to study the conformation of DNA in the nucleosome core particle. In this model, the changes in the energy of the covalent bonds that connect the base pairs of each strand of the DNA double helix, as well as the lateral displacements and the rotation of adjacent base pairs are considered. We show that because of the rigidity of the covalent bonds in the sugar-phosphate backbones, the base pair parameters are highly correlated, especially, strong twist-roll-slide correlation in the conformation of the nucleosomal DNA is vividly observed in the calculated results. This simple model succeeds to account for the detailed features of the structure of the nucleosomal DNA, particularly, its more important base pair parameters, roll and slide, in good agreement with the experimental results.     

Genetic Diversity and Pathogenic Variability of Colletotrichum truncatum Causing Anthracnose of Pepper in Malaysia

Colletotrichum truncatum was initially described from pepper and has been reported to infect 180 host genera in 55 plant families worldwide. Samples were collected from pepper plants showing typical anthracnose symptoms. Diseased samples after isolation were identified as C. truncatum based on morphological characters and ITS‐rDNA and β‐tubulin sequence data. Intersimple sequence repeat (ISSR) markers were used to estimate genetic diversity in C. truncatum from Malaysia. A set of 3 ISSR primers revealed a total 26 allele from the amplified products. Cluster analysis with UPGMA method clustered C. truncatum isolates into two main groups, which differed with a distance of 0.64. However, the genetic diversity of C. truncatum isolates showed correlation between genetic and geographical distribution, but it failed to reveal a relationship between clustering and pathogenic variability. Phylogenetic analyses discriminated the C. truncatum isolates from other reference Colletotrichum species derived from GenBank. Among the morphological characters, shape, colour of colony and growth rate in culture were partially correlated with the ISSR and phylogenetic grouping. Pathogenicity tests revealed that C. truncatum isolates were causal agents for pepper anthracnose. In the cross‐inoculation assays, C. truncatum isolates were able to produce anthracnose symptoms on tomato, eggplant, onion, lettuce and cabbage. A pathogenicity and cross‐inoculation studies indicated the potential of C. truncatum for virulence and dominancy on plant resistance.