Variation in leaf photosynthetic characteristics in wild rice species

Variations in leaf gas-exchange characteristics, leaf pigment content, and other important leaf traits were investigated in seven wild Oryza species, five hybrids, and five improved varieties. The significant variations were observed in photosynthetic pigment contents amongst different species of Oryza. The mean chlorophyll (Chl) content was higher in O. sativa (varieties and hybrids), while O. eichengeri showed the lowest Chl content. The mean carotenoid (Car) content in O. sativa (varieties and hybrids) was higher than in other wild rice species. O. eichengeri and O. barthii had significantly lower Car contents than other rice species. Significant differences were noticed in the rate of photosynthesis (P _N), stomatal conductance (g _s), transpiration rate (E), internal CO₂ concentration (C _i), specific leaf mass (SLM), and leaf thickness amongst different Oryza species. The mean P _N was the highest in O. nivara followed by O. eichengeri. The mean P _N was the lowest in O. glumaepatula, which was lower than that of cultivated varieties and hybrids of O. sativa. High rates of photosynthesis were observed in O. nivara (ACC. No. CR 100097), O. rufipogon (ACC.No. CR 100267), and O. nivara (ACC.No. CR 100008). The O. nivara and O. rufipogon genotypes with high P _N might be used in rice improvement programmes for an increase of leaf photosynthesis in rice. Multiple correlations performed between different gas-exchange characteristics and other physiological traits revealed that the rate of photosynthesis was not dependent on the leaf pigment content or the leaf thickness. A strong positive correlation between P _N and the P _N/C_i ratio, which represents the carboxylation efficiency, indicated that the observed variation in P _N was not based on pigment content or other leaf traits.     

Biomechanical and structural response of healing Achilles tendon to fatigue loading following acute injury

Achilles tendon injuries affect both athletes and the general population, and their incidence is rising. In particular, the Achilles tendon is subject to dynamic loading at or near failure loads during activity, and fatigue induced damage is likely a contributing factor to ultimate tendon failure. Unfortunately, little is known about how injured Achilles tendons respond mechanically and structurally to fatigue loading during healing. Knowledge of these properties remains critical to best evaluate tendon damage induction and the ability of the tendon to maintain mechanical properties with repeated loading. Thus, this study investigated the mechanical and structural changes in healing mouse Achilles tendons during fatigue loading. Twenty four mice received bilateral full thickness, partial width excisional injuries to their Achilles tendons (IACUC approved) and twelve tendons from six uninjured mice were used as controls. Tendons were fatigue loaded to assess mechanical and structural properties simultaneously after 0, 1, 3, and 6 weeks of healing using an integrated polarized light system. Results showed that the number of cycles to failure decreased dramatically (37-fold, p<0.005) due to injury, but increased throughout healing, ultimately recovering after 6 weeks. The tangent stiffness, hysteresis, and dynamic modulus did not improve with healing (p<0.005). Linear regression analysis was used to determine relationships between mechanical and structural properties. Of tendon structural properties, the apparent birefringence was able to best predict dynamic modulus (R²=0.88–0.92) throughout healing and fatigue life. This study reinforces the concept that fatigue loading is a sensitive metric to assess tendon healing and demonstrates potential structural metrics to predict mechanical properties.     

The effect of leaffolder Cnaphalocrocis medinalis (Guenee) [Lepidoptera: Pyralidae] injury on the plant physiology and yield loss in rice

Influence of leaffolder feeding on chlorophyll, PS II activity and plant–water relations, effect of larval density on leaf damage and time course studies on larval feeding behaviour on altered physiological changes in TN1 rice culture were studied. Quantification of yield losses in the field caused by leaffolder was also assessed. Leaffolder damage resulted in 57% reduction in chlorophyll content, 23% reduction in PS II activity and 23% reduction in relative water content in comparison with control. Rice leaffolder larva folds the leaf and scrapes the green tissue from within the fold resulting in scorching and drying of the leaves. Larval density had differentially influenced effective leaf area of rice crop. Larval densities of more than 3 larvae per hill at maximum tillering stage resulted up to 20% unfilled grains, 28–57% reduction in PS II activity and 23% reduction in relative water content in comparison with the control. At flowering stage, flag leaf area damage of above 25% resulted in more than 50% unfilled grains over control, indicating direct effect of yield reduction in rice. Thus, a cumulative effect of loss in chlorophyll, reduced photosynthate availability and altered water relations caused by the leaffolder injury to flag leaf lead to greater yield loss in rice.     

Discovery of novel 1,4-dihydropyridine-based PDE4 inhibitors

Substituted 1,4-dihydropyridines were discovered as a novel and potent series of phosphodiesterase 4 (PDE4) inhibitors. Structure–activity relationships within this series have been carried out and studies revealed that the dihydropyridine core, with indole moiety and 3,4-dimethoxybenzyl group, is a potent analogue for PDE4 inhibition. These novel series of compounds were prepared via a 3-component reaction in a single pot. In vitro biological activity, modeling studies and crystallography data are also reported.     

Soil application of silicon reduces yellow stem borer,Scirpophaga incertulas (Walker) damage in rice

The effect of soil application of rice husk ash (RHA), a cheap renewable source of silicon, and imidazole (a silicon solubilizer and carrier) on yellow stem borer (YSB), Scirpophaga incertulas (Walker), and its damage to rice plants were investigated. Treatments included soil application of RHA (T1), imidazole (T2), RHA + imidazole (applied once at vegetative stage, T3) and RHA + imidazole (applied twice at both vegetative and booting stages of crop growth, T4) with an untreated control (T5). The effect was tested in five varieties, viz., BPT 5204, KRH2, Pusa Basmati 1, MTU1010 and Vandana. All the soil treatments reduced damage by YSB at vegetative and reproductive phases across five varieties as compared to untreated control. Scanning electron micrograph and electron‐dispersive X‐ray spectrum analysis of stem tissue of rice variety BPT 5204 treated with silicon revealed the enhanced deposition of silicon in cell walls and 2.1‐ to 5.3‐fold increase in silicon content across treatments. Larvae collected from the silicon‐treated plants had worn mandibles, and the histological studies showed rupture of the peritrophic membrane, increased vacuolation, disintegration of columnar cells and discharge of cellular contents into the gut lumen due to abrasion of midgut epithelium, as compared to untreated control where the columnar cells and midgut lining were intact. Although all the treatments were effective, T4‐imidazole applied twice along with RHA was more effective in reducing YSB damage followed by T3‐imidazole applied once with RHA at tillering stage, T2‐imidazole alone and T1‐RHA in the descending order of efficacy.     

Evaluation of the tert-butyl group as a probe for NMR studies of macromolecular complexes

Journal of Biomolecular NMR - The development of methyl transverse relaxation optimized spectroscopy has greatly facilitated the study of macromolecular assemblies by solution NMR spectroscopy....     

Discovery of benzo[d]imidazo[5,1-b]thiazole as a new class of phosphodiesterase 10A inhibitors

The design, synthesis and structure activity relationship studies of a series of compounds from benzo[d]imidazo[5,1-b]thiazole scaffold as phosphodiesterase 10A (PDE10A) inhibitors are discussed. Several potent analogs with heteroaromatic substitutions (9a–d) were identified. The anticipated binding mode of these analogs was confirmed by performing the in silico docking experiments. Later, the heteroaromatics were substituted with saturated heteroalkyl groups which provided a tool compound 9e with excellent PDE10A activity, PDE selectivity, CNS penetrability and with favorable pharmacokinetic profile in rats. Furthermore, the compound 9e was shown to be efficacious in the MK-801 induced psychosis model and in the CAR model of psychosis.