Dispersive behaviour of larvae of the common cabbage butterflyPieris rapae crucivora

To investigate the aggregative nature of the larvae of Pieris rapae crucivora, each 50 individuals of the 4th and 5th instar larvae collected from cabbage farms and reared under crowded and solitary conditions were released on an experimental arena and their dispersive behaviour was observed with the lapse of time. Both the 4th and 5th instar larvae showed the trend to approach toward random distribution when they were released under clumped condition, and they maintained random distribution when they were released at random. Therefore, it may be concluded that the larvae have not any aggregative nature caused by the mutual attraction among individuals. However, as the larvae reared in crowds sometimes showed the slight aggregative behaviour, it seems that the larval dispersal is different between densely and sparsely populated plants in field.     

Extraction, characterization and potential applications of cellulose in corn kernels and Distillers’ dried grains with solubles (DDGS)

Cellulose with properties suitable for films and absorbents has been extracted from corn kernels and DDGS. Although DDGS is an inexpensive and abundant co-product that contains valuable components, it is currently not being used for industrial applications. DDGS contains about 9–16% cellulose by weight but the properties of cellulose in DDGS or even in corn kernels such as degree of polymerization (DP), morphology and crystallinity of cellulose have not been studied. In this study, cellulose was extracted from corn kernels and DDGS using alkali and enzymes. A minimum crude cellulose yield of 1.7% and 7.2% with cellulose content of 72% and 81% was obtained from corn kernels and DDGS, respectively. The solids obtained after extraction with cellulose contents ranging from 35% to 81% were made into films with tensile strength and elongation up to 42.5 MPa and 3.3%, respectively, using water and without any additional chemicals. The cellulose obtained holds water up to 9 times its weight and could therefore be used as an absorbent. The cellulose could also be used as paper, composites, lubricant and nutritional supplement.     

Aggregative oviposition of a phytophagous beetle overcomes egg‐crushing plant defences

1. Gregarious behaviours in phytophagous insects are common, but their adaptive value is rarely well understood. In the present study, we document a novel case of cooperative behaviour, the aggregative oviposition of a leaf beetle, Pyrrhalta viburni Paykull, and the realised fitness benefit of overcoming a plant defensive response (wound tissue production). 2. In laboratory choice‐tests, females exhibited aggregative oviposition, characterised by (i) a preference for twigs already infested by conspecifics, and (ii) positioning of new egg masses adjacent to existing ones. Field observations supported laboratory results, showing that P. viburni egg masses are most commonly found aggregated in large clusters. 3. In a field experiment using three host plants (Viburnum dentatum L., Viburnum opulus L. and Viburnum×bodnantense Aberc. ex Stearn), mean egg survivorship and twig mortality increased, while twig wound response decreased, with an increasing level of infestation. Egg survivorship was consistently higher on twigs that died than on twigs that remained alive. 4. Overall, these results suggest that, by aggregating their egg masses, P. viburni females overwhelm the twig wound response, often killing the twig in the process. Aggregative oviposition and low defences of V. dentatum to P. viburni could have facilitated the establishment and spread of this beetle in its introduced range (northeastern North America), in areas where V. dentatum is abundant.     

Porin from Thiobacillus versutus

The porin of Thiobacillus versutus IFO 14567 was isolated by extraction of cell-envelopes with sodium dodecyl sulfate. It exhibited strong porin-activity after reconstitution into artificial lipid bilayer membranes. The diameter of the pore was determined as 1.6 nm, with a weak selectivity for cations being observed. The porin migrated as a single band (Mr 35 kDa) on SDS-polyacrylamide gel-electrophoresis after heating (100 degrees C, 5 min). The porin oligomer was not sensitive towards EDTA. Analytical ultracentrifugation studies demonstrated the native oligomer to be a trimer.     

A simple purification procedure of buffalo lung cathepsin H,its properties and influence of buffer constituents on the enzyme activity

BackgroundCathepsin H (E.C.3.4.22.16) belongs to a family of lysosomal cysteine protease which regulates diverse normal biological processes mainly in intracellular proteolysis.MethodsPurification of cathepsin H from an unstudied system i.e. buffalo lung has been achieved by a simple process developed after incorporating appropriate alteration in the available methods for isolation of the enzyme from other sources. The use of DEAE-Cellulose and SP-Sephadex C-50 helped in better and simultaneous separation of cathepsin B and H up to homogeneity.ResultsThe SDS-PAGE result showed buffalo cathepsin H to be a single-chain molecule having MW, NH₂- and COOH- terminal residues of 25.4 kDa, Lys and Val respectively. The enzyme was a glycoprotein with pI of 6.2; it hydrolyzed Leu-NA (V_max/K_m = 301.6) as the most efficient substrate followed by Arg-NA, Arg-Arg-NA and BANA. Buffalo enzyme showed maximum activity at 36 °C, pH 6.75 and at a buffer concentration of 2 × 10^?3 M.ConclusionCatheptic activity was found to be quite stable at least for 20–30 min between pH 4.5–7.0, buffer concentration of 1 × 10^?2 to 4 × 10^?2 M and the temperature resistance up to 36 °C. The effects of various substances present in the buffers routinely used for the assay of catheptic activity revealed that the activity of buffalo lung cathepsin H depends not only qualitatively but also quantitatively on the constituents of assay buffer.General significanceThis study seems to provide valuable information regarding the biochemistry of cathepsin H in general as well as influence of buffer constituents on enzyme activity and physiological role in particular.     

Aggregative movement of C4 mesophyll chloroplasts is promoted by low CO2 under high intensity blue light

• C₄ plants supply concentrated CO₂ to bundle sheath (BS) cells, improving photosynthetic efficiency by suppressing photorespiration. Mesophyll chloroplasts in C₄ plants are redistributed toward the sides of the BS cells (aggregative movement) in response to environmental stresses under light. Although this chloroplast movement is common in C₄ plants, the significance and mechanisms underlying the aggregative movement remain unknown.
• Under environmental stresses, such as drought and salt, CO₂ uptake from the atmosphere is suppressed by closing stomata to prevent water loss. We hypothesized that CO₂ limitation may induce the chloroplast aggregative movement. In this study, the mesophyll chloroplast arrangement in a leaf of finger millet, an NAD-malic enzyme type C₄ plant, was examined under different CO₂ concentrations and light conditions.
• CO₂ limitation around the leaves promoted the aggregative movement, but the aggregative movement was not suppressed, even at the higher CO₂ concentration than in the atmosphere, under high intensity blue light. In addition, mesophyll chloroplasts did not change their arrangement under darkness or red light.
• From these results, it can be concluded that CO₂ limitation is not a direct inducer of the aggregative movement but would be a promoting factor of the movement under high intensity blue light.

     

Oxovanadium(IV) complexes of carbohydrates: A brief overview

In this brief review the most recent studies and the most relevant aspects of the complexes generated by interaction of carbohydrates and related molecules with the oxovanadium(IV) cation, VO²⁺, are presented and discussed. The survey includes complexes of mono-, di- and polysaccharides, and of other molecules related to simple sugars. First studies with conduritols and related molecules are also described. Moreover, complexes of ascorbic and quinic acids and of some peculiar flavonoids are also included. Some comments on the general physicochemical properties of these complexes are made and their biological activities and effects are also briefly discussed.