Mir1-CP,a novel defense cysteine protease accumulates in maize vascular tissues in response to herbivory

When lepidopteran larvae feed on the insect-resistant maize genotype Mp708 there is a rapid accumulation of a defensive cysteine protease, Maize insect resistance 1-cysteine protease (Mir1-CP), at the feeding site. Silver-enhanced immunolocalization visualized with both light and transmission electron microscopy was used to determine the location of Mir1-CP in the maize leaf. The results indicated that Mir1-CP is localized predominantly in the phloem of minor and intermediate veins. After 24 h of larval feeding, Mir1-CP increased in abundance in the vascular parenchyma cells and in the thick-walled sieve element (TSE); it was also found localized to the bundle sheath and mesophyll cells. In situ hybridization of mRNA encoding Mir1-CP indicated that the primary sites of Mir1-CP synthesis in the whorl are the vascular parenchyma and bundle sheath cells. In addition to the phloem, Mir1-CP was also found in the metaxylem of the leaf and root. After 24 h of foliar feeding, the amount of Mir1-CP in the root xylem increased and it appeared to move from xylem parenchyma into the root metaxylem elements. The accumulation of Mir1-CP in maize vascular elements suggests Mir1-CP may move through these tissues to defend against insect herbivores.     

9-Deoxopodophyllotoxin derivatives as anti-cancer agents.

Several 9-deoxo-9-substituted podophyllotoxin derivatives were synthesised starting from naturally occuring podophyllotoxin and their anti-cancer activity was evaluated against in vitro human cancer cell line assay. It was observed that these compounds do possess good anti-cancer activity particularly against ovarian, renal and lung cancer cell lines.     

Ornithine Decarboxylase Activity and Edema Formation in Cerebral Ischemia of Conscious Gerbils

Abstract: General anesthetic agents often affect the biochemical and physiologic changes triggered by cerebral ischemia. This study examined the regional activities of ornithine decarboxylase (ODC) in gerbils subjected to 5 min of bilateral carotid occlusion without anesthesia. At 2, 4, and 6 h of reperfusion, significant ODC activity was observed in both the cortex and the hippocampus. Pretreatment with α-difluoromethylornithine (DFMO) significantly blocked the ODC activity at 2, 4, and 6 h. Significant edema formation was found at 2, 4, and 6 h. At 2 h, edema formation was unaffected by administration of DFMO. However, DFMO treatment reduced later edema formation at 4 and 6 h. These results demonstrate that ODC activity and edema formation are delayed in gerbils after the induction of transient ischemia even with the removal of anesthetic agents and their potentially protective effects. These findings suggest that ODC activity and its induction of delayed cerebral edema are specific to cerebral ischemia and not to an anesthetic effect. DFMO treatment reduced both the ODC activity and edema formation, indicating a role for polyamines in postischemic edema formation.     

The role of gibberellic acid in the pollen-pistil interaction in sporophytic self-incompatible systems

Self-incompatibility is exhibited by callose deposition in the stigmatic papillae and total inhibition of pollen germination in sporophytic self-incompatible (SSI) systems of Ipomoea cairica (Convolvulaceae), Brassica campestris and Raphanus sativus (Brassicaceae). This has been partially overcome, in vitro by treating pollen and/or stigma with gibberellic acid (GA₃). Experiments employing tryptophan and chlorocholine chloride either alone or in combination with GA₃ (10^–3 M) further elucidate the role of gibberellin in overcoming the barrier to self-compatibility. These results support our earlier contention [7, 24] that growth regulators play a significant role in pollen-pistil recognition in SSI systems.     

Modulation of fatty acid-binding capacity of heart fatty acid-binding protein by oxygen — derived free radicals

Summary In this study, we examined the effects of exposure of heart fatty acid-binding protein (h-FABP) to chemically generated O₂ ^– or OH · with respect to its oleate binding and to its electrophoretic properties. Purified rat h-FABP at 40 M scavenged as much as 30% O₂ ^– and 85% OH ·. On the other hand, when 2 nmol (4 M) FABP were exposed to free radicals, the maximum oleate binding capacity as measured by Scatchard analysis was reduced only by 14% and 27% for O₂ ^– and OH ·, respectively. The electrophoretic pattern of free radical-exposed FABP was not markedly different when examined either by the non-denaturing or by denaturing PAGE, suggesting the absence of any degradation or aggregation of FABP by O₂ ^– or OH ·. It is hypothesized that O₂ ^– or OH · in physiological concentration may not alter the function of FABP markedly in the ischemic-reperfused myocardium.Abbreviations h-FABP Heart Fatty Acid Binding Protein - NEFA Non-Esterified Fatty Acids - O₂ ^– Superoxide anions - OH· hydroxyl radicals - OCI hypohalite radicals - H₂O₂ hydrogen peroxide - HPLC High Pressure Liquid Chromatography     

Enhanced production of an alkaline pectinase from Streptomyces sp. RCK-SC by whole-cell immobilization and solid-state cultivation

An alkalophilic Streptomyces sp. RCK-SC, which produced a thermostable alkaline pectinase, was isolated from soil samples. Pectinase production at 45 °C in shaking conditions (200 rev min⁻¹) was optimal (76,000 IU l⁻¹) when a combination of glucose (0.25% w/v) and citrus pectin (0.25% w/v) was added along with urea (0.25% w/v) in the basal medium devoid of yeast extract and peptone. All the tested amino acids and vitamins greatly induced pectinase production and increased the specific productivity of pectinase up to 550%. In an immobilized cell system containing polyurethane foam (PUF), the pectinase production was enhanced by 32% (101,000 IU l⁻¹) compared to shake flask cultures. In solid-state cultivation (SSC) conditions, using wheat bran as solid substrate, pectinase yield of 4857 IU g⁻¹ dry substrate was obtained at substrate-to-moisture ratio of 1:5 after 72 h of incubation. The partially purified pectinase was optimally active at 60 °C and retained 80% of its activity at 50 °C after 2 h of incubation. The half life of pectinase was 3 h at 70 °C. Pectinase was stable at alkaline pH ranging from 6.0 to 9.0 for more than 8 h at room temperature retaining more than 50% of its activity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dependence of endoplasmic reticulum-associated degradation on the peptide binding domain and concentration of BiP

ER-associated degradation (ERAD) removes defective and mis-folded proteins from the eukaryotic secretory pathway, but mutations in the ER lumenal Hsp70, BiP/Kar2p, compromise ERAD efficiency in yeast. Because attenuation of ERAD activates the UPR, we screened for kar2 mutants in which the unfolded protein response (UPR) was induced in order to better define how BiP facilitates ERAD. Among the kar2 mutants isolated we identified the ERAD-specific kar2-1 allele (Brodsky et al. J. Biol. Chem. 274, 3453-3460). The kar2-1 mutation resides in the peptide-binding domain of BiP and decreases BiP's affinity for a peptide substrate. Peptide-stimulated ATPase activity was also reduced, suggesting that the interdomain coupling in Kar2-1p is partially compromised. In contrast, Hsp40 cochaperone-activation of Kar2-1p's ATPase activity was unaffected. Consistent with UPR induction in kar2-1 yeast, an ERAD substrate aggregated in microsomes prepared from this strain but not from wild-type yeast. Overexpression of wild-type BiP increased substrate solubility in microsomes obtained from the mutant, but the ERAD defect was exacerbated, suggesting that simply retaining ERAD substrates in a soluble, retro-translocation-competent conformation is insufficient to support polypeptide transit to the cytoplasm.     

Rhamnogalacturonan lyase reveals a unique three-domain modular structure for polysaccharide lyase family 4

Rhamnogalacturonan lyase (RG-lyase) specifically recognizes and cleaves alpha-1,4 glycosidic bonds between L-rhamnose and D-galacturonic acids in the backbone of rhamnogalacturonan-I, a major component of the plant cell wall polysaccharide, pectin. The three-dimensional structure of RG-lyase from Aspergillus aculeatus has been determined to 1.5 A resolution representing the first known structure from polysaccharide lyase family 4 and of an enzyme with this catalytic specificity. The 508-amino acid polypeptide displays a unique arrangement of three distinct modular domains. Each domain shows structural homology to non-catalytic domains from other carbohydrate active enzymes.