Microbial levan in the diet of Labeo rohita Hamilton juveniles: effect on non-specific immunity and histopathological changes after challenge with Aeromonas hydrophila

A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group ( P  > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila , moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles.     

Factors and processes of soil degradation in vertisols of the Purna Valley,Maharashira, India

The Vertisols of the Purna Valley, which cover the districts of Amravati, Akola and Buldhana in the state of Maharashtra, India, lack any perceptible evidence of salt efflorescence on the soil surface which would indicate the presence of salt, but the drainage conditions are poor. The limited data available indicate that the adverse physical condition of the soils is due to their poor hydraulic conductivity (HC), which is impaired by sodium in the exchange complex. However, the factors and processes that are inherently related to the development of sodicity in these shrink-swell soils are not yet understood. In order to establish the cause-effect relationship, eight Vertisol pedons from methodically selected sites were studied morphometrically in the field, and for their sodicity-related physical and chemical properties in the laboratory. The soils are deep, calcareous, clayey and very dark greyish brown to dark brown in colour. Cracks extend up to the slickenside zones in soils of Pedons 1–3 in the northeastern area of the valley, while they cut through the slickenside zones in soils of Pedons 4–8 in the southwest. The slickenside faces were larger in the soils of the southwest than in those of the northeast. All these soils meet the specifications of the Vertisols order of soil taxonomy. Saturation extracts of the soils had very low electrical conductivity (ECe ⩽ 2 ds m⁻¹). They ranged from moderately alkaline in the northeast, Pedons 1–3, to strongly alkaline in the southwest, pedons 4–8. In soils from the northeast the exchangeable sodium percentage (ESP) was less than 5 throughout the depth of the pedons, whereas in other soils it was up to 6 in the surface horizons and between 7 and 26 in the subsoil horizons; four of these soils qualified as sodic according to the criteria of the United States Salinity Laboratory. The inherently low hydraulic conductivity was due to the dispersion of clay particles caused by a high percentage of exchangeable magnesium (EMP) in the highly smectitic soils, and also to a slight increase in ESP (⩾5). The results of this study suggest that ESP 5 should be used as the lower limit for sodic subgroups of Vertisols, rather than ESP 15 as given in Keys to Soil Taxonomy (Soil Survey Staff, 1994). This is because there are severe limitations to the use of such soils owing to the development of adverse physical conditions even at such a low ESP. The authors emphasize the need to keep this fact in mind during future land resource management programmes on the soils of this valley as well as on similar soils occurring elsewhere. The development of sodicity in the soils of the southwestern part of the valley has been attributed to the semi-arid climatic conditions that have induced the pedogenetic process of depletion of calcium ions from the soil solution in the form of calcium carbonate, thereby resulting in an increase of both the sodium adsorption ratio (SAR) and the ESP with pedon depth. This chemical degradation, which affects the sodicity of Vertisols, appears to be a basic process that needs to be recognised in the future along with those already described as natural processes of soil degradation.     

Endocrine disruption and metabolic changes following exposure of Cyprinus carpio to diethyl phthalate

Diethyl phthalate (DEP) enter into aquatic environment from industries manufacturing cosmetics, plastic and many commercial products and can pose potential fish and human health hazard. This experiment evaluated effects of DEP in adult male (89 g) common carp (Cyprinus carpio) by exposing them to fractions of LC₅₀ (1/500-1/2.5) doses with every change of water for 28 days. Vitellogenin induction metabolic enzymes, somatic indices and bioaccumulation were studied on 7th, 14th, 21st and 28th day. The 96th hour LC₅₀ of DEP in fingerlings was found to be 48 mg/L. Compared to control, except increase (P < 0.01) in alkaline phosphatase activity (EC 3.1.3.1) and liver size, there was decrease (P < 0.01) in activity of acid phosphatase (EC 3.1.3.2), aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and testiculosomatic index following exposure to 1, 5 and 20 ppm DEP. Significant (P < 0.01) dose dependant vitellogenin induction was observed with exposure of fish to 0.1, 1 and 5 ppm DEP. The bioaccumulation of DEP in testis, liver, brain, gills and more importantly in muscle tissues of fish increased significantly (P < 0.01) with increase of dose from 1 to 5 ppm. Significant interaction (P < 0.01) of dose and duration of exposure indicated that exposure period of a week to two was sufficient to bring about changes in quantifiable parameters studied. Fish exposed to 20 ppm DEP became lethargic and discolored during onset of the 4th week. This is the first report describing metabolic changes and vitellogenin induction following exposure of C. carpio to DEP dose that is as low as 1/500th fraction of LC₅₀.     

Organoleptic and microbiological examination of suffocated carp stored under various conditions]

A process of dead market carp deterioration was studied in relation to conditions of the environment and the fish treatment by organoleptic and microbiological methods. A scheme is presented for fish assessment according to the symptoms of deterioration and the limits of carp storability under the given conditions of storing are determined. The results of the microbiological examination were not in keeping with the degree of deterioration of the fish.     

DNA origami with complex curvatures in three-dimensional space

We present a strategy to design and construct self-assembling DNA nanostructures that define intricate curved surfaces in three-dimensional (3D) space using the DNA origami folding technique. Double-helical DNA is bent to follow the rounded contours of the target object, and potential strand crossovers are subsequently identified. Concentric rings of DNA are used to generate in-plane curvature, constrained to 2D by rationally designed geometries and crossover networks. Out-of-plane curvature is introduced by adjusting the particular position and pattern of crossovers between adjacent DNA double helices, whose conformation often deviates from the natural, B-form twist density. A series of DNA nanostructures with high curvature--such as 2D arrangements of concentric rings and 3D spherical shells, ellipsoidal shells, and a nanoflask--were assembled.     

Chlamydia infections and heart disease linked through antigenic mimicry

Chlamydia infections are epidemiologically linked to human heart disease. A peptide from the murine heart muscle-specific alpha myosin heavy chain that has sequence homology to the 60-kilodalton cysteine-rich outer membrane proteins of Chlamydia pneumoniae, C. psittaci, and C. trachomatis was shown to induce autoimmune inflammatory heart disease in mice. Injection of the homologous Chlamydia peptides into mice also induced perivascular inflammation, fibrotic changes, and blood vessel occlusion in the heart, as well as triggering T and B cell reactivity to the homologous endogenous heart muscle-specific peptide. Chlamydia DNA functioned as an adjuvant in the triggering of peptide-induced inflammatory heart disease. Infection with C. trachomatis led to the production of autoantibodies to heart muscle-specific epitopes. Thus, Chlamydia-mediated heart disease is induced by antigenic mimicry of a heart muscle-specific protein.     

Structure-dependent phytotoxicity of catechins and other flavonoids: flavonoid conversions by cell-free protein extracts of Centaurea maculosa (spotted knapweed) roots

Invasive plants are believed to succeed in part by secretion of allelochemicals, thus displacing competing plant species. Centaurea maculosa (spotted knapweed) provides a classic example of this process. We have previously reported that spotted knapweed roots secrete (+/-)-catechin and that (-)-catechin, but not (+)-catechin, is phytotoxic and hence may be a major contributor to C. maculosa's invasive behavior in the rhizosphere. In this communication, we explore both structure/activity relationships for flavonoid phytotoxicity and possible biosynthetic pathways for root production of (+/-)-catechin. Kaempferol and dihydroquercetin were shown to be phytotoxic, while quercetin was not. Kaempferol was converted to dihydroquercetin and (+/-)-catechin when treated with total root protein extracts from C. maculosa, but quercetin was not. This finding suggests an alteration in the standard flavonoid biosynthetic pathway in C. maculosa roots, whereby kaempferol is not a dead-end product but serves as a precursor to dihydroquercetin, which in turn leads to (+/-)-catechin production.     

The effects of electrolyte concentrations on calcium-sodium exchange equilibria in two soil samples of india

The effects of total electrolyte concentrations of the equilibrium solutions (t.e.c.) on Ca²⁺-Na⁺ exchange equilibria in two soil samples (high and low in organic matter, clay content and CEC) were studied. Homoionic (Na⁺-saturated) soil samples were equilibrated with solutions having a large range in sodium adsorption ratio (SAR) at 25, 50, 75 and 100 meq. 1^-1 t.e.c. The exchange equilibria data were analysed, using a thermodynamic approach and the selectivity coefficients of Gapon (1933), Vanselow (1932) and Krishnamoorthy et al. (1948) (K_G, K_V and K_KDO). At a given proportion of Ca²⁺: Na⁺ in the equilibrium solution, the development of the exchangeable sodium percentage (ESP) in both soil samples increased with the increase in t.e.c. At a given SAR, the effect of t.e.c. on the development of ESP was less on a soil sample with high organic matter (O.M.), clay content and cation exchange capacity (CEC) than on a soil sample with low O.M., clay content and CEC. The values of exchange selectivity coefficients decreased with the increase in t.e.c, and did not remain constant throughout the exchange isotherm for any of the t.e.c. tried.