Synthesis and anticonvulsant activity of sulfonamide derivatives-hydrophobic domain

A series of sulphonamide derivatives (1-11) were synthesized in good yield and evaluated for their possible anticonvulsant activity and neurotoxic study. The structures of the synthesized compounds were confirmed on the basis of their spectral data and elemental analysis. Majority of the compounds were active in MES and scPTZ tests. All the compounds were less toxic than the standard drug phenytoin.     

Dual inhibition of cyclooxygenase and lipoxygenase by human haptoglobin: its polymorphism and relation to hemoglobin binding

Haptoglobin (Hp) binds hemoglobin (Hb) specifically and stoichiometrically. Since Hb stimulates prostaglandin (PG biosynthesis), we investigated if Hp effects arachidonic acid (AA) metabolism. The results showed that Hp (50-250 microg protein) inhibited the biosynthesis of PGs via cyclooxygenase (COX) and 12-HETE via lipoxygenase pathway in human platelets. Additional evidence was obtained by the loss of Hp inhibitory activity upon removal of Hp by affinity chromatography on hemoglobin sepharose and by inhibition of AA or bradykinin-induced bronchoconstriction in the guinea pig. Hb reduced the inhibitory effect of Hp in a concentration-related manner such that all its inhibitory activity was lost when completely bound by Hb. Of the three Hp phenotypes, Hp 1-1 showed maximum binding capacity to Hb indicating its greater protective role. These findings implicate Hp in the regulation of COX and lipoxygenase pathways and show Hp involvement in the body's endogenous defense system against inflammation. This indicates that mammals have dual defense system, i.e., a specific immune system and non-specific Hp defense system.     

Systematic Analysis in Caenorhabditis elegans Reveals that the Spindle Checkpoint Is Composed of Two Largely Independent Branches

Kinetochores use the spindle checkpoint to delay anaphase onset until all chromosomes have formed bipolar attachments to spindle microtubules. Here, we use controlled monopolar spindle formation to systematically define the requirements for spindle checkpoint signaling in the Caenorhabditis elegans embryo. The results, when interpreted in light of kinetochore assembly epistasis analysis, indicate that checkpoint activation is coordinately directed by the NDC-80 complex, the Rod/Zwilch/Zw10 complex, and BUB-1—three components independently targeted to the outer kinetochore by the scaffold protein KNL-1. These components orchestrate the integration of a core Mad1^MDF-1/Mad2^MDF-2-based signal, with a largely independent Mad3^SAN-1/BUB-3 pathway. Evidence for independence comes from the fact that subtly elevating Mad2^MDF-2 levels bypasses the requirement for BUB-3 and Mad3^SAN-1 in kinetochore-dependent checkpoint activation. Mad3^SAN-1 does not accumulate at unattached kinetochores and BUB-3 kinetochore localization is independent of Mad2^MDF-2. We discuss the rationale for a bipartite checkpoint mechanism in which a core Mad1^MDF-1/Mad2^MDF-2 signal generated at kinetochores is integrated with a separate cytoplasmic Mad3^SAN-1/BUB-3–based pathway.     

Pheromone mass trapping of bagworm moths,Metisa plana Walker (Lepidoptera: Psychidae), for its control in mature oil palms in Perak,Malaysia

The bagworm, Metisa plana Walker (Lepidoptera: Psychidae), is an important pest of oil palms in Malaysia. A serious infestation cause yield declines of 30–40% over 2 years after attack. Successful mass trapping depends on efficient removal of adults, which reduces the chances of mating, eventually causing a decline in the population. This study was conducted in three smallholder blocks where palm age varied from 6 to 16 years. Sticky vane traps were baited with four receptive females of M. plana and placed in three transects within each trapping plot. The percentage of female bags with eggs (i.e., those pupal bags housing the female with eggs that hatched) determined the effects of trapping on mating and reproduction success. Palm yield was compared between the trapping and control plots. The number of live larvae and the percentage of bags with eggs in the trapping plots were always relatively lower (9.1–28.2%) compared to the control plots (28.6–48.6%). Trapping plots had relatively higher bunch weight (7.8–14.3 kg) compared to the control plots (4.5–9.2 kg). The bunch weight in the trapping plots increased 22% after trapping compared to 15% in the control plot. Damage ratings on the fronds declined between 35–45% in the trapping blocks. Damage ratings declined between 20% and 27% in most control plots but increased 17% in one of the blocks with an increased bagworm population. There, mass trapping reduces the chances of bagworm mating and oviposition, which leads to lower populations and, therefore, lower frond damage and higher yields.     

Termite‐induced heterogeneity in African savanna vegetation: mechanisms and patterns

Objectives: To (1) assess the strength of evidence for the role of termites in vegetation heterogeneity in African savannas, and (2) identify the mechanisms by which termites induce such heterogeneity. Location: African savannas. Methods: We conducted a review of the literature, a meta‐analysis and qualitative systems analysis to identify mechanisms to explain the observed patterns. Results: The review provided evidence for termite‐induced heterogeneity in floristic composition and vegetation patterning in savannas across Africa. Termites induced vegetation heterogeneity directly or indirectly through their nest‐building and foraging activities, associated nutrient cycling and their interaction with mammalian herbivores and fire. The literature reviewed indicated that termite mounds essentially act as islands of fertility, which are responsible for ecosystem‐level spatial heterogeneity in savannas. This was supported by the meta‐analysis, which demonstrated that mounds of Ancistrotermes, Macrotermes, Odontotermes (family Macrotermitinae), Cubitermes (family Termitinae) and Trinervitermes (Nasutitermitinae) are significantly enriched in clay (75%), carbon (16%), total nitrogen (42%), calcium (232%), potassium (306%) and magnesium (154%) compared to the surrounding savanna soil. Conclusions: Termite activity is one of the major factors that induce vegetation patterning in African savannas. The implications of this are discussed and research questions for future studies and modelling efforts are indicated.     

Error-correcting microarray design

We describe a microarray design based on the concept of error-correcting codes from digital communication theory. Currently, microarrays are unable to efficiently deal with "drop-outs," when one or more spots on the array are corrupted. The resulting information loss may lead to decoding errors in which no quantitation of expression can be extracted for the corresponding genes. This issue is expected to become increasingly problematic as the number of spots on microarrays expands to accommodate the entire genome. The error-correcting approach employs multiplexing (encoding) of more than one gene onto each spot to efficiently provide robustness to drop-outs in the array. Decoding then allows fault-tolerant recovery of the expression information from individual genes. The error-correcting method is general and may have important implications for future array designs in research and diagnostics.     

The minus end in sight

Microtubules are intrinsically polar structures. A consequence of this polarity is that the two ends of the microtubule polymer exhibit different properties. The more dynamic plus ends and the mechanisms that regulate their behavior have been the focus of much recent attention. Here, we concentrate on the dynamics and regulation of minus ends, which play distinct but equally critical roles in microtubule function. In the first part of this review, we compare the in vitro and in vivo behavior of microtubules from a minus end perspective. This comparison suggests that cells possess conserved mechanisms to specifically inhibit minus end polymerization, and perhaps also to actively promote depolymerization. In the second part, we focus on the spatial positioning of minus ends, which is achieved by localized microtubule nucleation, minus end capping and minus end anchoring as well as by motor-dependent sorting. These mechanisms are used in different biological contexts to generate the diversity of organized microtubule arrays in cells.     

Effect of substrate-dependent microbial ethylene production on plant growth

Various compounds have been identified as precursors/substrates for the synthesis of ethylene (C₂H₄) in soil. This study was designed to compare the efficiency of four substrates, namely L-methionine (L-MET), 2-keto-4-methylthiobutyric acid (KMBA), 1-aminocyclopropane-1-carboxylic acid (ACC), and calcium carbide (CaC₂), for ethylene biosynthesis in a sandy clay loam soil by gas chromatography. The classic “triple” response in etiolated pea seedling was employed as a bioassay to demonstrate the effect of substrate-dependent microbial production of ethylene on plant growth. Results revealed that an amendment with L-MET, KMBA, ACC (up to 0.10 g/kg soil) and CaC₂ (0.20 g/kg soil) significantly stimulated ethylene biosynthesis in soil. Overall, ACC proved to be the most effective substrate for ethylene production (1434 nmol/kg soil), followed by KMBA, L-MET, and CaC₂ in descending order. Results further revealed that ethylene accumulation in soil from these substrates caused a classic “triple” response in etiolated pea seedlings with different degrees of efficacy. A more obvious classic “triple” response was observed at 0.15, 0.10, and 0.20 g/kg soil of L-MET, KMBA/ACC, and CaC₂, respectively. Similarly, direct exposure of etiolated pea seedlings to commercial ethylene gas also modified the growth pattern in the same way. A significant direct correlation (r = 0.86 to 0.97) between substrate-derived C₂H₄ and the classic triple response in etiolated pea seedlings was observed. This study demonstrated that the presence of substrate(s) in soil may lead to increased ethylene concentration in the air of the soil, which may affect plant growth in a desired direction. Published in Russian in Mikrobiologiya, 2006, Vol. 75, No. 2, pp. 277–283. The text was submitted by the authors in English.     

The chemistry of a termite fungus comb

Summary The chemical and spectroscopic data presented herein show that about 50% of the weight of the termite fungus comb consists of carbohydrates (⊂40%) and proteinaceous materials (⊂10%). Of the remaining material about 30% appears to be aliphatic in nature (long-chain and branched alkanoic acids) and 20% aromatic and phenolic. The data on monosaccharide composition indicate that the fungus comb material, rich in glucose, arabinose and xylose, is predominantly of plant origin.     

Stimulation of calcium efflux from rat liver mitochondria by adenosine 3′5′ cyclic monophosphate

Summary The uptake or release of Ca²⁺ from rat liver mitochondria was studied by means of a sensitive Ca-electrode. It was found that using palmitoyl coenzyme A together with carnitine and ATP as substrates that Ca²⁺ was released gradually from mitochondria by adenosine 35 cyclic monophosphate. The effect was obtained with either mitochondria preloaded with Ca²⁺ or with their physiological content of Ca²⁺. No such release was obtained with the usual substrates used to provide energy for Ca²⁺ uptake by mitochondria.