Chemical hybridizing agents for chickpea (Cicer arietinum L.): leads from QSAR analysis of ethyl oxanilates and pyridones

In the self-pollinated crops such as chickpea, induction of male sterility by deployment of chemical hybridizing agents (CHAs) facilitating "two-line" approach holds immense potential in heterosis breeding. A total of 40 test CHAs comprising 20 ethyl oxanilates and 20 pyridones were screened as potential CHAs on chickpea (variety BG 1088) at 500, 800, and 1000 ppm. Three test compounds mostly having either F (4)/Br (5)/CF(3) (19) at the para position of the aryl ring from a pool of 20 ethyl oxanilates were identified as the most potent CHAs causing >or=99% induction of pollen sterility and >90% total flower sterility at 1000-ppm test concentration. Among pyridone derivatives, N-(4-chlorophenyl)-5-carbethoxy-4,6-dimethyl, 1,2-dihydropyrid-2-one (26) was found to be the most active. Quantitative structure activity relationship (QSAR) analysis has revealed a direct involvement of Swain-Lupton field constant, F(p), with the target bioactivity which implied that field rather than resonance effect (R) had a positive effect on the activity. The real guiding principle for selectivity was found out to be the hydrophobic parameter pi value. The QSAR models indicated that increased steric bulk at the 4-position on the phenyl ring is associated with enhanced activity. The CHAs appeared to act by mimicking UDP-glucose, the key substrate in the synthesis of callose, or lead to an imbalance in acid-base equilibrium in pollen mother cells resulting in dissolution of callose wall by premature callase secretion.     

Synthesis and characterization of N-acylaniline derivatives as potential chemical hybridizing agents (CHAs) for wheat (Triticum aestivum L.)

Induction of male sterility by deployment of chemical hybridizing agents (CHAs) are important in heterosis breeding of self-pollinated crops like wheat, wherein the male and female organs are in the same flower. Taking a lead from the earlier work on rice, a total of 25 N-acylanilines comprising of malonanilates, acetoacetanilides, and acetanilides (including halogenated acetanilides) were synthesized and screened as CHAs on three genotypes of wheat, viz., PBW 343, HD 2046, and HD 2733 at 1500 ppm in the winter of 2001-2002. The N-acylanilines containing variations at the acyl and aromatic domain were synthesized by condensation of substituted anilines with appropriate diesters, acid chlorides, or monoesters. The test compounds with highly electronegative groups such as F/Br at the para position of the aryl ring were identified as the most potent CHAs, causing higher induction of male sterility. A variation of N-substitution at the side chain generally furnished analogues like 4'-fluoroacetoacetanilide (7) and ethyl 4'-fluoromalonanilate (1), which induced 89.12 and 84.66% male sterility, respectively, in PBW 343. Among halogenated acetanilides, the increasing number of chlorine atoms in the side chain led to an increase in the activity of 4'-fluoro (23) and 4'-bromo (24) derivatives of trichoroacetanilides, which induced >87% male sterility. Quantitative structure-activity relationship (QSAR) models indicated the positive contributions of the field effect exemplified by the Swain-Lupton constant (Fp) and negative contributions of the Swain-Lupton resonance constant (R) for the aromatic substitution. The positive influences of parachor (P) for the acyl domain have been underlined. These leads will be significant in explaining the CHA fit in the macromolecular receptor site. The CHAs appeared to act by causing an imbalance in the acid-base equilibrium in pollen mother cells resulting in dissolution of the callose wall by premature callase secretion.     

Dietary Multispecies Probiotic Supplementation Enhances the Immunohematological Responses and Reduces Mortality by Aeromonas hydrophila in Labeo rohita Fingerlings

A study was conducted to determine the immunomodulatory effect of probiotic mixture on the nonspecific immune response and disease resistance of Labeo rohita. Fish were fed with six different test diets with or without probiotics, namely, T1 (basal feed [BF] without probiotics), T2 (BF + Bacillus subtilis [BS] + Lactococcus lactis [LL]), T3 (BF + LL + Saccharomyces cerevisiae [SC]), T4 (BF + BS + SC), T5 (BF + BS + LL + SC), and T6 (BF + heat‐killed bacteria of BS + LL + SC). During the prechallenge period, significantly higher (P < 0.01) nitroblue tetrazolium assay (NBT), red blood cells (RBC), hemoglobin (Hb), globulin, and albumin content were recorded in the probiotic‐supplemented diet group. Feeding all the three probiotics significantly decreased (P < 0.01) the serum aspartate aminotransferases (AST), alanine aminotransferases (ALT), acid phosphatase (ACP), and alkaline phosphatase (ALP) activity and increased the myeloperoxidase (MPO) and immunoglobulin M (IgM) value. Significant difference in the NBT, Hb, serum albumin, and MPO was noticed in both prechallenged and postchallenged fish. Lowest survivability was recorded in the nonprobiotic fed group, followed by the group fed with heat‐killed probiotics, whereas the highest survivability was noticed in the group fed with all the three probiotics in live form. Thus, a probiotic mixture diet constituting of three probiotics in viable form is found to be optimum to enhance the immunity and postinfection survivability in L. rohita fingerlings.     

Cell cycle-dependent coupling of the calcitonin receptor to different G proteins.

Calcitonin is a calcium regulating peptide hormone with binding sites in kidney and bone as well as in the central nervous system. The mechanisms of signal transduction by calcitonin receptors were studied in a pig kidney cell line where the hormone was found to regulate sodium pumps. Calcitonin receptors activated the cyclic adenosine monophosphate (cAMP) or the protein kinase C (PKC) pathways. The two transduction pathways required guanosine triphosphate (GTP)-binding proteins (G proteins) (the choleratoxin sensitive Gs and the pertussis toxin sensitive Gi, respectively) and led to opposite biological responses. Moreover, selective activation of one or the other pathway was cell cycle-dependent. Therefore, calcitonin may induce different biological responses in target cells depending on their positions in the cell cycle. Such a modulation of ligand-induced responses could be of importance in rapidly growing cell populations such as during embryogenesis, growth, and tumor formation.     

Relative Agronomic Effectiveness of phosphate rocks and P adsorption characteristics of an Oxic Rhodustalf in Eastern India

The Relative Agronomic Effectiveness (RAE) of rock phosphates as compared to water soluble Triple Super Phosphate was measured on direct, residual, and cumulative application of the P fertilizers in a field experiment with rice on an Oxic‐Rhodustalf in the eastern plateau region of India. The fertilizers were Morocco Rock Phosphate (MORP), Mussoorie Rock Phosphate (MRP), Partially Acidulated Rock Phosphate (PARP), and Triple Super Phosphate (TSP). The RAE of the rock phosphates were lower for direct application (54–80 %) and cumulative application (70–93 %) of P but roughly equal or larger for the residual effect (92–142 %) as compared to TSP. The P adsorption characteristic of the experimental soil conformed to the linear relationship of both Freundlich and Langmuir isotherm equation. The adsorption data when plotted according to Langmuir equation deviated from a single linear relationship at higher concentration (10 μg ml^–1), thereby giving two adsorption maximum values ( 68.49 μg g^–1 and 256.41 μg g^–1) and binding energies ( 2.86 ml μg^–1 and 0.089 ml μg^–1) for the soil. Two populations of P adsorption site with widely different affinity for P probably existed in the soil.     

Microbial biomass and its activities in salt-affected coastal soils

Seasonal fluctuations in salinity are typical in coastal soils due to the intrusion of seawater in the groundwater. We studied the effect of salinity on the microbial and biochemical parameters of the salt-affected soils of the coastal region of Bay of Bengal, Sundarbans, India. The average pH values and average organic C (OC) contents of soils from nine different sites cultivated with rice (Oryza sativa) ranged from 4.8 to 7.8 and from 5.2 to 14.1 g kg⁻¹, respectively. The average electrical conductivity of the saturation extract (EC_e) during the summer season was about five times higher than that during the monsoon season. Within the nine sites, three soils (S₃, S₄, and S₅) were the most saline. The average microbial biomass C (MBC), average basal soil respiration (BSR), and average fluorescein diacetate hydrolyzing activity (FDHA) were lowest during the summer season, indicating a negative influence of soil salinity. About 59%, 50%, and 20% variation in MBC/OC, FDHA/OC, and BSR/MBC (metabolic quotient, qCO₂), respectively, which are indicators of environmental stress, could be explained by the variation in EC_e. The decrease in MBC and microbial activities with a rise in salinity is probably one of the reasons for the poor crop growth in salt-affected coastal soils.     

Quantitative structure-activity relationship analysis as a tool to evaluate the mode of action of chemical hybridizing agents for wheat (Triticum aestivum L.)

Augmentation of wheat production calls for introduction of wheat hybrids in cultivation. In the absence of viable alternative technology of hybrid wheat development, chemical induction of male sterility mediated technology based on chemical hybridizing agents (CHAs) holds a great potential. The QSAR method was applied to two families of CHAs in the N-acylanilines and pyridone class of chemistry. The models for each CHA family gave good correlation between the variations in log percent of male sterility and the steric-electrostatic properties of the sets. QSAR analysis has revealed a direct relationship of the Swain-Lupton constant F(p) and molecular mass but an inverse relationship of MR, ES, and Swain-Lupton resonance constant R in influencing the bioactivity in the N-acylanilines. QSAR analysis of four parent families consisting of two training sets each of pyrid-2-ones and prid-4-ones revealed the positive contributions of field effect exemplified by the Swain-Lupton field constant (F) and the negative contributions of the molar refractivity (MR) of aromatic substituents in all but one training set. The QSAR models also indicated that increased steric bulk at the 4-position on the phenyl ring is associated with enhanced activity. These leads will be useful in explaining the CHA binding fit in the macromolecular receptor site.     

Toxicokinetics, recovery, and metabolism of metamitron in goat

Toxicokinetic behavior and metabolism studies of metamitron and its effect on the cytochrome P(450) content of liver microsomal pellet were carried out in black Bengal goats after a single oral administration at 278 mg kg(-1) and consecutive oral administration of 30 mg kg(-1) for 7 days. Metamitron was detected in the blood sample at 0.08 h (12.0 +/- 0.87 microg mL(-1)), maximum at 4 h (84.3 +/- 8.60 microg mL(-1)) and minimum (14.6 +/- 1.67 microg mL(-1)) at 36 h blood sample after a single oral administration. The absorption rate constant was 0.69 +/- 0.09 h(-1). The Vd(area) (2.00 +/- 0.08 L kg(-1)) and t(1/2)beta (8.98 +/- 0.70 h) values suggested wide distribution and long persistence of the compound in the body. The values of T approximately B (0.80 +/- 0.04), F(c) (0.55 +/- 0.01), Cl(B) (0.15 +/- 0.00 L kg(-1) h(-1)), and K(21) (0.41 +/- 0.03 h(-1)) suggested that metamitron retained in the blood compared to that in the tissue. Maximum concentration of metamitron residue was found in the adrenal gland followed by bile on day 4 of single oral administration. The higher Cl(R) compared to Cl(H) value indicated the excretion of the major portion (34-40%) through urine compared to feces (20-26%). Maximum concentrations of metamitron and its metabolite, deaminometamitron, were excreted through urine and feces at 48 and 24 h samples, respectively. The recovery of metamitron including its metabolite in terms of parent compound varied from 69.3 to 80.1%, of which contribution of metabolite in terms of parent compound varied from 53.1 to 63.0%. Repeated oral administration of metamitron at 30 mg kg(-1) for 7 days caused induction of the cytochrome P(450) content of liver microsomal pellet of goat, suggesting oxidative deamination of metamitron.     

Performance of rice ( Oryza Sativa L.) cultivars to integrated application of fertilizer n and farmyard manure in acid laterite soil

Varietal adaptability in exploiting the natural resources is important. Field experiments were conducted during the wet seasons of 1998 and 1999 at the Regional Research Substation, Sekhampur. The aim was to evaluate the performance of locally popular IR-36 (high yielding, photo-insensitive) and Khejurthari (local land race, photosensitive) rice cultivars with variable proportions of N management through inorganic and organic supplements separately or combined. The cv. IR-36 produced the highest number of panicles/m 2 but the cv. Khejurthari had significantly higher number of grains/panicle and test weight. Fertilizer N and farmyard manure rates influenced the yield attributing characters. The cv. IR-36 produced 10% more grain yield than Khejurthari. Combined application of inorganic (urea) and organic (farmyard manure) sources increased the grain yield by 72% over no input (control). Nitrogen uptake by cv. IR-36 and Khejurthari was statistically similar. Application of 60 kg N/ha with 4 t farmyard manure/ha increased the N uptake by 1.88 times compared to control. Apparent N recovery was higher in cv. IR-36 at higher doses of N and in cv. Kejurthari at lower doses.