Phosphoenolpyruvate Carboxylase Purified from Leaves of C3, C4, and C3-C4 intermediate species of Alternanthera: Properties at Limiting and Saturating Bicarbonate

Phosphoenolpyruvate carboxylase (PEPC) was purified from leaves of four species of Alternanthera differing in their photosynthetic carbon metabolism: Alternanthera sessilis (C₃), A. pungens (C₄), A. ficoides and A. tenella (C₃-C₄ intermediates or C₃-C₄). The activity and properties of PEPC were examined at limiting (0.05 mM) or saturating (10 mM) bicarbonate concentrations. The V_max as well as K_m values (for Mg²⁺ or PEP) of PEPC from A. ficoides and A. tenella (C₃-C₄ intermediates) were in between those of C₃ (A. sessilis) and C₄ species (A. pungens). Similarly, the sensitivity of PEPC to malate (an inhibitor) or G-6-P (an activator) of A. ficoides and A. tenella (C₃-C₄) was also of intermediate status between those of C₃ and C₄ species of A. sessilis and A. pungens, respectively. In all the four species, the maximal activity (V_max), affinity for PEP (K_m), and the sensitivity to malate (K_I) or G-6-P (K_A) of PEPC were higher at 10 mM bicarbonate than at 0.05 mM bicarbonate. Again, the sensitivity to bicarbonate of PEPC from C₃-C₄ intermediates was in between those of C₃- and C₄-species. Thus the characteristics of PEPC of C₃-C₄ intermediate species of Alternanthera are intermediate between C₃- and C₄-type, in both their kinetic and regulatory properties. Bicarbonate could be an important modulator of PEPC, particularly in C₄ plants. This revised version was published online in August 2006 with corrections to the Cover Date.     

Efficient Imputation of Missing Markers in Low-Coverage Genotyping-by-Sequencing Data from Multiparental Crosses

We consider genomic imputation for low-coverage genotyping-by-sequencing data with high levels of missing data. We compensate for this loss of information by utilizing family relationships in multiparental experimental crosses. This nearly quadruples the number of usable markers when applied to a large rice Multiparent Advanced Generation InterCross (MAGIC) study.     

Deformation-induced hydrolysis of a degradable polymeric cylindrical annulus

A thermodynamically consistent framework for describing the response of materials undergoing deformation-induced degradation is developed and applied to a particular biodegradable polymer system. In the current case, energy is dissipated through the mechanism of hydrolytic degradation and its effects are incorporated in the constitutive model by appropriately stipulating the forms for the rate of dissipation and for the degradation-dependent Helmholtz potential which changes with the extent of the degradation of the material. When degradation does not occur, the response of the material follows the response of a power-law generalized neo-Hookean material that fits the response of the non-degraded poly(l-lactic acid) under uniaxial extension. We study the inflation and extension of a degrading cylindrical annulus and the influence of the deformation on the mechanism of degradation and its consequent mechanical response. Depreciation of mechanical properties due to degradation confers time-dependent characteristics to the response of the biodegradable material: the material creeps when subjected to constant loads and stresses necessary to keep a fixed deformation relax.     

Molecular docking analysis of flavonoids with aldose reductase

Diabetes mellitus is a group of metabolic disorders that has risen to become the third most common cause in humans in recent years. The development of new bioactive substances from natural sources is a relatively new area. Flavonoids are believed to have a variety of beneficial properties in nature, including anti-inflammatory, antimicrobial, anticancer, antioxidant, neuroprotective, and anti-HIV properties. 15 naturally occurring flavonoids docked with the selected target aldose reductase. We report the optimal binding of Acumitin, Agathisflavone, Agehoustin B, and alpha-Toxicarol with aldose reductase for further consideration in drug discovery for T2DM.     

Changes in the level of cytosolic calcium, nitric oxide and nitric oxide synthase activity during platelet aggregation: an in vitro study in platelets from normal subjects and those with cirrhosis

Variceal bleeding due to abnormal platelet function is a well-known complication of cirrhosis. Nitric oxide-related stress has been implicated in the pathogenesis of liver cirrhosis.In the present investigation,we evaluated the level of platelet aggregation and concomitant changes in the level of platelet cytosolic calcium (Ca2+), nitric oxide (NO) and NO synthase (NOS) activity in liver cirrhosis.The aim of the present study was to investigate whether the production of NO by NOS and level of cytosolic Ca2+ influence the aggregation of platelets in patients with cirrhosis of the liver.Agonist-induced aggregation and the simultaneous changes in the level of cytosolic Ca2+, NO and NOS were monitored in platelets of patients with cirrhosis.Platelet aggregation was also measured in the presence of the eNOS inhibitor,diphenylene iodinium chloride (DIC).The level of agonist-induced platelet aggregation was significantly low in the platelets of patients with cirrhosis compared with that in platelets from normal subjects.During the course of platelet aggregation,concomitant elevation in the level of cytosolic Ca2+ was observed in normal samples,whereas the elevation was not significant in platelets of patients with cirrhosis.A parallel increase was observed in the levels of NO and NOS activity.In the presence of the eNOS inhibitor,platelet aggregation was enhanced and accompanied by an elevated calcium level.The inhibition of platelet aggregation in liver cirrhosis might be partly due to greater NO formation by eNOS.Defective Ca2+ release from the internal stores to the cytosol may account for inhibition of aggregation of platelets in cirrhosis.The NO-related defective aggregation of platelets in patients with cirrhosis found in our study is of clinical importance,and the underlying mechanism of such changes suggests a possible therapeutic strategy with cell-specific NO blockers.     

Phylogeny of spiny frogs Nanorana (Anura: Dicroglossidae) supports a Tibetan origin of a Himalayan species group

Recent advances in the understanding of the evolution of the Asian continent challenge the long‐held belief of a faunal immigration into the Himalaya. Spiny frogs of the genus Nanorana are a characteristic faunal group of the Himalaya–Tibet orogen (HTO). We examine the phylogeny of these frogs to explore alternative biogeographic scenarios for their origin in the Greater Himalaya, namely, immigration, South Tibetan origin, strict vicariance. We sequenced 150 Nanorana samples from 62 localities for three mitochondrial (1,524 bp) and three nuclear markers (2,043 bp) and complemented the data with sequence data available from GenBank. We reconstructed a gene tree, phylogenetic networks, and ancestral areas. Based on the nuDNA, we also generated a time‐calibrated species tree. The results revealed two major clades (Nanorana and Quasipaa), which originated in the Lower Miocene from eastern China and subsequently spread into the HTO (Nanorana). Five well‐supported subclades are found within Nanorana: from the East, Central, and Northwest Himalaya, the Tibetan Plateau, and the southeastern Plateau margin. The latter subclade represents the most basal group (subgenus Chaparana), the Plateau group (Nanorana) represents the sister clade to all species of the Greater Himalaya (Paa). We found no evidence for an east–west range expansion of Paa along the Himalaya, nor clear support for a strict vicariance model. Diversification in each of the three Himalayan subclades has probably occurred in distinct areas. Specimens from the NW Himalaya are placed basally relative to the highly diverse Central Himalayan group, while the lineage from the Tibetan Plateau is placed within a more terminal clade. Our data indicate a Tibetan origin of Himalayan Nanorana and support a previous hypothesis, which implies that a significant part of the Himalayan biodiversity results from primary diversification of the species groups in South Tibet before this part of the HTO was uplifted to its recent heights.     

Identification and characterization of endoglucanases for fungicidal activity in <Emphasis Type="Italic">Anabaena laxa</Emphasis> (Cyanobacteria)

A cyanobacterial strain (Anabaena laxa RPAN8) exhibiting fungicidal activity and β-1,3 and 1,4 endoglucanase activities was selected for identifying the gene(s) involved. Functional analyses of the genomic library revealed that four clones (8, 64, 116, and 248) of RPAN8 exhibited fungicidal activity and induced structural deformities in the cell wall of the growing mycelia of Pythium aphanidermatum. Higher expression of fungicidal and β-1,4 endoglucanase activities, along with low expression of β-1,3 endoglucanase activity, was recorded in two E. coli clones (8 and 64). Clones 8 and 64 exhibited identical sequences while clones 116 and 248 were also similar. Bioinformatic analyses were undertaken only for the two non-identical clones 8 and 116 which showed open reading frames (ORFs) of 348 (end 1) and 656 amino acid residues (end 2), respectively. The amino acid sequence analyses revealed that the end 1 encoding endoglucanases belonged to peptidase M20 family while end 2 showed significant similarities with several known genes. The putative promoters and ribosomal binding sites were identified and amino acid exchanges were observed in both end 1 and 2. The presence of signal peptides of 24 and 20 amino acid residues respectively revealed the secretory nature of these proteins.     

<Emphasis Type="Italic">In vitro</Emphasis> antileishmanial activity of <Emphasis Type="Italic">Aloe vera</Emphasis> leaf exudate: A potential herbal therapy in leishmaniasis

Aloe vera has wide spread use in health products, and despite several reports on the whole plant and inner gel, little work has been performed on the leaf exudate. Our aim was to evaluate the in vitro efficacy of Aloe vera leaf exudate (AVL) in leishmaniasis. Irrespective of the disease manifestation, promastigotes from strains responsible for cutaneous, mucocutaneous, and visceral leishmaniasis were susceptible to AVL and their IC₅₀ ranged from 100 to 180 μg/ml. In axenic amastigotes cultured from a L. donovani strain 2001 responsible for visceral leishmaniasis, the IC₅₀ was 6.0 μg/ml. AVL caused activation of host macrophages evident by an increased release of members of reactive oxygen species that was attenuated by preincubation with free radical scavengers. Collectively, our data indicates that AVL, via its direct leishmanicidal activity which can be further enhanced by activation of host macrophages, is an effective antileishmanial agent meriting further pharmacological investigations.     

The influence of sunlight on the localized corrosion of UNS S31600 in natural seawater

Tests were conducted on the performance of UNS S31600 stainless steel (SS) in a natural day/night cycle vs full darkness under conditions of natural marine biofilm accumulation. In quiescent flowing seawater tests in the laboratory as well as under natural immersion in the sea, diffuse sunlight (～10% of natural) counteracted the influence of marine biofilms and produced substantial inhibition of the corrosion of SS. Thus, the probabilities (percentage attack) and propagation rates (depths of attack) in multiple crevice tests were substantially lower in the day/night cycle than in the dark. A benefit was also observed for welded SS in terms of the time to corrosion initiation and the mass loss. SS in the passive state showed broader passive regions, well-defined breakdown potentials and markedly smaller anodic and cathodic current densities under the diurnal cycle. The overall reduction in corrosion is attributed to a combination of electrochemical photoinhibition and simultaneous photoinactivation of microbially mediated metal redox reactions linked to cathodic kinetics. These data offer fresh insights into the behaviour of SS under practical seawater situations and the proposed potential use of illumination in the mitigation of biologically influenced consequences.