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.     

Air Pollution Modelling for a Proposed Limestone Quarry

Predictions of the air pollution impact of a proposed opencastlimestone quarry have been made using meteorological data, information on various quarrying activities and their associatedemission factors, baseline air quality and a validated modelconditions. Results have indicated that the haul routes and ore processing plant are the major sources of suspended particulatematter (SPM) emissions. The emission rates of other air pollutants are insignificant. It has been predicted that 24-hraverage SPM concentrations due to quarrying activities would be around 360 μg m^-3 in the work zone and less than 130 μg m^-3 beyond the site boundary. The total 24-hr average SPM concentration beyond the site boundary would be below 500 μg m^-3, which is the national air qualitystandard for SPM in an industrial area. Therefore, the impact of opencast extraction on the local air quality would be acceptable. However, implementation of a green belt comprisingof various tree species which will act as a dust attenuator of40 m width around the site boundary, along with efficient control measures at source, would effectively mitigate and minimize pollution impacts from the quarry. The effectivenessof the green belt around the quarry site has been assessed and a sensitivity analysis has been carried out for different parameters, namely, tree height, width of green belt, and distance of receptor from the source. The technique for designing a green belt around a quarry site has also been described.     

Endocrine profiles, testicular gonadotropin receptors and sperm production in hemi-castrated ram lambs

The effects of hemi-castration upon compensatory hypertrophy, serum gonadotropin and testosterone concentrations, testicular gonadotropin receptors and daily sperm production (DSP) were studied in 10 crossbred ram lambs. At 4 mo of age lambs were either hemi-castrated (HC; n = 5) or left intact (INT; n = 5). Blood samples were collected every 2 h for the first 24 h post-surgery, every 6 h for the next 24 h and then three times weekly for the following 14 wk. Serial blood samples (15-min intervals for 8 h) were collected during the 4th, 8th and 12th week following hemi-castration. Individual mean testicular and epididymal weights increased (P less than .05) 48 and 33% in HC compared with INT rams, respectively. Serum follicle stimulating hormone (FSH) increased (P less than .05) within 8 h after HC, reached peak concentrations within 1 wk and remained elevated for 4 wk before returning to concentrations of INT rams. Neither mean serum luteinizing hormone (LH) nor pulse patterns of LH or FSH were different (P greater than .05) between these two groups at any period examined. Serum testosterone (T) concentrations were lower (P less than .05) during the first 48 h post-surgery in HC rams, but by 1 wk concentrations were similar (P greater than .05) to those in INT rams. Remaining testes from HC and INT rams were removed at 7 mo of age, 3 mo after initial gonadal manipulation. On a per-testis basis there were more (P less than .05) LH and FSH receptors in HC than INT rams, respectively; however, concentrations of receptors were not different (P greater than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

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.     

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.     

Assessing forest fragmentation in north-western Himalaya: a case study from Ranikhet forest range,Uttarakhand, India

The northwestern Himalaya harbors high levels of biodiversity due to its unique topography, climatic conditions and heterogeneity. Forest fragmentation is one of the major threats causing a decline in biodiversity in the Himalayan region. We assesses forest fragmentation and changes in land use land cover(LULC) patterns using multi-temporal satellite data over a time span of four decades(1976–2013). Fragmentation analysis using the Landscape Fragmentation Tool(LFT) reveals a decrease in core and edge areas by 14 and 2.3 %, respectively; while an increase in non-forest, patch area and perforation area by 2.1, 0.4, and 14 %, respectively. The LULC dynamics show that the areas under dense forest and scrub forest have decreased by 2.8 % and 1.9 %, respectively; and there is an increase in open forest, crop land and fallow land area by 2.6, 1.7 and 2.1 %, respectively. The quantification of landscape heterogeneity is undertaken with the help of landscape metrics computed using FRAGSTATS at class and landscape level, showing signs of increased fragmentation. Our study provides baseline database that can support the future biodiversity conservation and sustainable forest management initiatives.     

Tomato leaf curl Gujarat virus, a New Begomovirus Species Causing a Severe Leaf Curl Disease of Tomato in Varanasi, India

ABSTRACT The biological and molecular properties of Tomato leaf curl Gujarat virus from Varanasi, India (ToLCGV-[Var]) were characterized. ToLCGV-[Var] could be transmitted by grafting and through whitefly transmission in a persistent manner. The full-length genome of DNA-A and DNA-B of ToLCGV-[Var] was cloned in pUC18. Sequence analysis revealed that DNA-A (AY190290) is 2,757 bp and DNA-B (AY190291) is 2,688 bp in length. ToLCGV-[Var] could infect and cause symptoms in tomato, pepper, Nicotiana benthamiana, and N. tabacum when partial tandem dimeric constructs of DNA-A and DNA-B were co-inoculated by particle bombardment. DNA-A alone also is infectious, but symptoms were milder and took longer to develop. ToLCGV-Var virus can be transmitted through sap inoculation from infected tomato plants to the above-mentioned hosts causing the same symptoms. Open reading frames (ORFs) in both DNA-A and DNA-B are organized similarly to those in other begomoviruses. DNA-A and DNA-B share a common region of 155 bp with only 60% sequence identity. DNA-B of ToLCGV-[Var] shares overall 80% identity with DNA-B of Tomato leaf curl New Delhi virus-Severe (ToLCNDV-Svr) and 75% with ToLCNDV-[Lucknow] (ToLCNDV-[Luc]). Comparison of DNA-A sequence with different begomoviruses indicates that ToLCGV-[Var] shares 84% identity with Tomato leaf curl Karnataka virus (ToLCKV) and 66% with ToLCNDV-Svr. ToLCGV-[Var] shares a maximum of 98% identity with another isolate of the same region (ToLCGV-[Mir]; AF449999) and 97% identity with one isolate from Gujarat (ToLCGV-[Vad]; AF413671). All three viruses belong to the same species that is distinct from all the other geminivirus species described so far in the genus Begomovirus of the family Geminiviridae. The name Tomato leaf curl Gujarat virus is proposed because the first sequence was taken from an isolate of Gujarat, India.