Persistence and dissipation of the insecticide flubendiamide and its metabolite desiodo flubendiamide residues in tomato fruit and soil

A method for residue analysis of flubendiamide and its metabolite desiodo flubendiamide was developed using high performance liquid chromatography. This method was then used to evaluate the residual level and dissipation rate of flubendiamide and desiodo flubendiamide in the tomato fruit. The half-life of flubendiamide in tomato fruit was 1.64 and 1.98 days in recommended and double of the recommended dose, respectively. Tomato fruit and soil samples analyzed on the 10th day after the last spray revealed that flubendiamide and its metabolite desiodo flubendiamide residues at below determination level (0.01 μg g(-1)) at either dose of application.

Simultaneous determination of flubendiamide its metabolite desiodo flubendiamide residues in cabbage, tomato and pigeon pea by HPLC

A sensitive and simple method for simultaneous analysis of flubendiamide and its metabolite desiodo flubendiamide in cabbage, tomato and pigeon pea has been developed. The residues were extracted with QuEChERS method followed by dispersive solid-phase extraction with primary secondary amine sorbent to remove co extractives, prior to analysis by HPLC coupled with UV-Vis detector. The recoveries of flubendiamide and desiodo flubendiamide were ranged from 85.1 to 98.5% and 85.9 to 97.1% respectively with relative standard deviations (RSD) less than 5% and sensitivity of 0.01 μg g(-1). The method offers a less expensive and safer alternative to the existing residue analysis methods for vegetables.

Persistence and safety risk assessment of propineb in Indian tea

A supervised field trial was conducted on tea with propineb at 1,750 and 3,500 g a.i./ha at two locations (Assam and Darjeeling), applied thrice at an interval of 10 days during the year 2006-2007. Propineb residue was measured spectrophotometrically at 435 nm in terms of CS2. The initial deposit of propineb in green tea leaves were found to be in the range of 16.26-35.96 mg/kg and the residue persisted up to 10 days irrespective of doses and locations with half-life value ranging from 2.24 to 2.43 days and preharvest interval of 17.17-21.37 days. Made tea residues ranged from 9.27 to 20.86 mg kg(-1) on 7 days and no residues could be detected on 14 days. Infusion study indicated that propineb did not infuse into tea liquor from made tea. The limit of determination was found to be 0.1 mg kg(-1) in terms of propineb for green tea leaves, made tea, and tea liquor. The tea applied with the recommended dose of propineb is safe for consumption as liquor.

Assessment and occurrence of various heavy metals in surface water of Ganga river around Kolkata: a study for toxicity and ecological impact

A study was conducted during November, 2005-October, 2006 to evaluate the surface water quality of river Ganga around Kolkata. The samples were analyzed for a number of physico-chemical parameters using standard laboratory procedures and giving prime thrust to determine the heavy metal concentrations (Fe, Mn, Cu, Zn, Pb, Cd, Cr, and Ni) of surface water at four different locations of the river Ganga around Kolkata from two points (middle of the river stream and a discharge point) at each location. Out of 96 samples analyzed, Fe, Mn, Cu, Zn, and Ni were detected in 71, 47, 38, 60, and 45 samples in the concentrations ranging from 0.013 to 5.49, 0.022 to 1.78, 0.003 to 0.033, 0.005 to 0.293, and 0.045 to 0.24 mg L(-1), respectively. Cd and Pb were detected in six and 21 samples in the range of 0.005 to 0.006 and 0.05 to 0.53 mg L(-1), respectively. But Cr was not detected in any of the samples analyzed. The metals exhibited no significant variation with respect to sampling locations as well as discharge points. However, the concentration of those metals varied with season, being higher in rainy and lower in winter season.

Impact assessment of pesticide residues in fish of Ganga river around Kolkata in West Bengal

An investigation was conducted from 2001 to 2005 for determining the residual concentration of five pesticides, viz., total-HCH, total-DDT, total-Endosulfan, Dimethoate and Malathion in fish samples collected from various points of the river Ganga. Fish samples were analyzed for pesticide residues using standard laboratory procedures by GC method. It was found that total-HCH concentration remains above the MRL values for maximum number of times in comparison to four other pesticides. The pesticide contamination to fish may be due to indiscriminate discharge of polluted and untreated sewage-sludge to the river. The pesticide contents in some places are alarming. Thus proper care, maintenance, treatment and disposal of sewage water and sludge are most vital and should be the prime thrust for the nation.

DYX1C1 functions in neuronal migration in developing neocortex

Rodent homologues of two candidate dyslexia susceptibility genes, Kiaa0319 and Dcdc2, have been shown to play roles in neuronal migration in developing cerebral neocortex. This functional role is consistent with the hypothesis that dyslexia susceptibility is increased by interference with normal neural development. In this study we report that in utero RNA interference against the rat homolog of another candidate dyslexia susceptibility gene, DYX1C1, disrupts neuronal migration in developing neocortex. The disruption of migration can be rescued by concurrent overexpression of DYX1C1, indicating that the impairment is not due to off-target effects. Transfection of C- and N-terminal truncations of DYX1C1 shows that the C-terminal TPR domains determine DYX1C1 intracellular localization to cytoplasm and nucleus. RNAi rescue experiments using truncated versions of DYX1C1 further indicate that the C-terminus of DYX1C1 is necessary and sufficient to DYX1C1's function in migration. In conclusion, DYX1C1, similar to two other candidate dyslexia susceptibility genes, functions in neuronal migration in rat neocortex.

Structure of the zinc-induced heterodimer of two calcium-free isoforms of phospholipase A2fromNaja naja sagittiferaat 2.7 Å resolution

The crystal structure of a zinc-induced heterodimer of two metal-free isoforms of a cobra venom phospholipase A(2) has been determined at 2.7 angstroms resolution. The crystals belong to space group P4(1), with unit-cell parameters a = b = 65.5, c = 58.4 angstroms, and have a single dimer in the asymmetric unit. The structure has been refined to R(cryst) and R(free) factors of 0.188 and 0.232, respectively. The two isoforms have a sequence identity of 82%. The zinc ion forms a fivefold coordination with a trigonal bipyramidal geometry involving one O atom each from Asp24 and Asn112 from molecule A and Asp24 from molecule B and two water molecules. Both molecules of the dimer are inactive. Molecule A is inactive because Arg31 (B) binds to Asp49 (A), while an acetate ion has displaced the essential water molecule and interacts with His48 (A). On the other hand, Arg31 (A) interacts with the calcium-binding loop of molecule B, resulting in an altered conformation of the loop. The absence of a calcium ion, loss of the essential water molecule and the altered conformation of the calcium-binding loop may be the reasons for the loss of activity of molecule B.

Biotinyl endothelin-1 binding to endothelin receptor and its applications

The endothelin (ET) system consists of two membrane receptor types A and B and three 21-mer isopeptides endothelin-1, endothelin-2, and endothelin-3 as ligands. This system is involved in many physiological processes such as vasomodulation, neurotransmission, embryonic development, renal function, and regulation of cell proliferation. In many pathophysiological conditions involving endothelin system, the endothelin antagonism could be a possible clinical treatment. Designing of an antagonist involves the characterization of the binding of the test compounds to the endothelin receptors. This is being carried out using radioactive ligand. A simpler and quicker method will be of great advantage. This study reports a non-radioactive method for establishing the IC50 concentrations of the ligand. This method uses biotinylated-endothelin-1 and streptavidin conjugated with horseradish peroxidase. Hydroxyl apatite gel is used for separating the bound and unbound biotin-tagged endothelin-1. This method is applicable to detergent solubilized receptors and purified recombinant receptors. The endothelin receptor type A expressed in Pichia pastoris system has been used in this study. We show that this method is applicable in Western blot analysis of endothelin-1 and its receptor complex. This can be used to localize the receptor molecules as well.

Crystal Structure of Echicetin from Echis carinatus (Indian Saw-scaled Viper) at 2.4Å Resolution

Echicetin is a heterodimeric protein from the venom of the Indian saw-scaled viper, Echis carinatus. It binds to platelet glycoprotein Ib (GPIb) and thus inhibits platelet aggregation. It has two subunits, alpha and beta, consisting of 131 and 123 amino acid residues, respectively. The two chains are linked with a disulphide bond. The level of amino acid sequence homology between two subunits is 50%. The protein was purified from the venom of E.carinatus and crystallized using ammonium sulphate as a precipitant. The crystal structure has been determined at 2.4A resolution and refined to an R-factor of 0.187. Overall dimensions of the heterodimer are approximately 80Ax35Ax35A. The backbone folds of the two subunits are similar. The central portions of the polypeptide chains of alpha and beta-subunits move into each other to form a tight dimeric association. The remaining portions of the chains of both subunits fold in a manner similar to those observed in the carbohydrate-binding domains of C-type lectins. In echicetin, the Ca(2+)-binding sites are not present, despite being topologically equivalent to other similar Ca(2+)-binding proteins of the superfamily. The residues Ser41, Glu43 and Glu47 in the calcium-binding proteins of the related family are conserved but the residues Glu126/120 are replaced by lysine at the corresponding sites in the alpha and beta-subunits.

Structure of an acidic phospholipase A2 from Indian saw-scaled viper (Echis carinatus) at 2.6 A resolution reveals a novel intermolecular interaction

The crystal structure of an acidic phospholipase A(2) from the venom of Echis carinatus (saw-scaled viper; scPLA(2)) has been determined at 2.6 A resolution and refined to a crystallographic R factor of 0.192. Although the overall structure of scPLA(2) is essentially similar to those of other group II acidic PLA(2)s from different species, it shows unique features in several parts. Particularly noteworthy is the C-terminal part, which folds differently to those of other group II PLA(2)s. This part is considered to be responsible for inhibition of the platelet-aggregation activity. The calcium-binding loop is tightly organized with sevenfold coordination. Another striking feature of scPLA(2) is the involvement of Asn79 O(delta1) of a symmetry-related molecule in a coordination linkage with Ca(2+) of the calcium-binding loop. This is the first observation of an internal metal ion participating in an intermolecular interaction. The beta-wing of a molecule is deeply inserted into the hydrophobic channel of another molecule and forms several intermolecular interactions. This results in the formation of an infinite chain of molecules. These chains are stacked in an antiparallel arrangement in the crystals.

Crystal structure of human seminal diferric lactoferrin at 3.4 Angstrom resolution

Lactoferrin was purified from human seminal fluid obtained from the semen bank. The purified samples were saturated with Fe3+ and crystallized by microdialysis method. The crystals belong to orthorhombic space group P21212, with a = 55.9 Angstrom. b = 97.2 Angstrom, c = 156.1 Angstrom and Z = 4. The structure was determined with molecular replacement method and refined to an R factor of 18.7% for all the data to 3.4 Angstrom resolution. The overall structure of seminal lactoferrin is similar to human colostrum lactoferrin. The amino acid sequence of seminal lactoferrin shows that it has one amino acid less than human colostrum lactoferrin and the structure of its N-terminal region is far more ordered than other lactoferrins. The structure of the iron-binding site and its immediate surroundings indicate well defined features.

Expression, purification, and characterization of equine lactoferrin in Pichia pastoris

Lactoferrin is an 80kDa iron-binding glycoprotein. It is secreted by exocrine glands. Many functions such as iron sequestering, anti-bacterial activity, regulation of gene expression, and immunomodulation are attributed to it. In the present study, we report the production of recombinant equine lactoferrin (ELF) in the methylotropic yeast Pichia pastoris using pPIC9K vector. The recombinant protein was purified by one-step affinity chromatography using heparin-Sepharose column. The purified protein has a molecular weight of 80kDa and reacted with antibody raised against the native equine lactoferrin. Its N-terminal sequence was identical to that of the native ELF. The iron-binding behavior and circular dichroism studies of the purified protein indicate that it has folded properly. The recombinant protein appears to be hyperglycosylated by the host strain, GS115. This is the first heterologous expression of equine lactoferrin and also the first report of intact lactoferrin expression using P. pastoris system. An yield of 40mg/l obtained in shake-flask cultures with this system, which is higher than the reported values for other systems.

Camel lactoferrin, a transferrin-cum-lactoferrin: crystal structure of camel apolactoferrin at 2.6 A resolution and structural basis of its dual role

Camel lactoferrin is the first protein from the transferrin superfamily that has been found to display the characteristic functions of iron binding and release of lactoferrin as well as transferrin simultaneously. It was remarkable to observe a wide pH demarcation in the release of iron from two lobes. It loses 50 % iron at pH 6.5 and the remaining 50 % iron is released only at pH values between 4.0 and 2.0. Furthermore, proteolytically generated N and C-lobes of camel lactoferrin showed that the C-lobe lost iron at pH 6.5, while the N-lobe lost it only at pH less than 4.0. In order to establish the structural basis of this striking observation, the purified camel apolactoferrin was crystallized. The crystals belong to monoclinic space group C2 with unit cell dimensions a=175.8 A, b=80.9 A, c=56.4 A, beta=92.4 degrees and Z=4. The structure has been determined by the molecular replacement method and refined to an R-factor of 0.198 (R-free=0.268) using all the data in the resolution range of 20.0-2.6 A. The overall structure of camel apolactoferrin folds into two lobes which contain four distinct domains. Both lobes adopt open conformations indicating wide distances between the iron binding residues in the native iron-free form of lactoferrin. The dispositions of various residues of the iron binding pocket of the N-lobe of camel apolactoferrin are similar to those of the N-lobe in human apolactoferrin, while the corresponding residues in the C-lobe show a striking similarity with those in the C-lobes of duck and hen apo-ovotransferrins. These observations indicate that the N-lobe of camel apolactoferrin is structurally very similar to the N-lobe of human apolactoferrin and the structure of the C-lobe of camel apolactoferrin matches closely with those of the hen and duck apo-ovotransferrins. These observations suggest that the iron binding and releasing behaviour of the N-lobe of camel lactoferrin is similar to that of the N-lobe of human lactoferrin, whereas that of the C-lobe resembles those of the C-lobes of duck and hen apo-ovotransferrins. Hence, it correlates with the observation of the N-lobe of camel lactoferrin losing iron at a low pH (4.0-2.0) as in other lactoferrins. On the other hand, the C-lobe of camel lactoferrin loses iron at higher pH (7.0-6.0) like transferrins suggesting its functional similarity to that of transferrins. Thus, camel lactoferrin can be termed as half lactoferrin and half transferrin.

Three-dimensional structure of a new form of mare lactoferrin in 70% PEG 400 at 3.8 A resolution

Three-dimensional (3D) structure of a new form of diferric mare lactoferrin has been determined at 3.8 A resolution. The protein was crystallized in a space group P2(1)2(1)2(1) with a = 80.1 A, b = 103.7 A, c = 112.2 A with a solvent content of 57%. The structure was solved by molecular replacement method using the model of native mare lactoferrin. The structure has been refined using X-PLOR to a final R-factor of 22.6% for all the data in 15.0-3.8 A resolution range. The final refined model comprises 5281 protein atoms, 2Fe3+ and 2CO3(2-) ions. The protein folds into two globular N- and C-lobes. The two lobes are further divided into two domains N1, N2 in the N-lobe and C1, C2 in the C-lobe. The overall folding of the protein is similar to that observed for the native protein. The superposition of Calpha traces of native mare lactoferrin and the present structure gives an r.m.s shift of 0.7 A. There is a slight variation in the orientation of two lobes but the domain orientations in the present structure are identical to those observed in the native mare lactoferrin.

Sequence and crystal structure determination of a basic phospholipase A2 from common krait (Bungarus caeruleus) at 2.4 A resolution: identification and characterization of its pharmacological sites

This is the first phospholipase A2 (PLA2) structure from the family of kraits. The protein was isolated from Bungarus caeruleus (common krait) and the primary sequence was determined using cDNA approach. Three-dimensional structure of this presynaptic neurotoxic PLA2 from group I has been determined by molecular replacement method using the model of PLA2 component of beta2-bungarotoxin (Bungarus multicinctus) and refined using CNS package to a final R-factor of 20.1 % for all the data in resolution range 20.0-2.4 A. The final refined model comprises 897 protein atoms and 77 water molecules. The overall framework of krait phospholipase A2 with three long helices and two short antiparallel beta-strands is extremely similar to those observed for other group I PLA2s. However, the critical parts of PLA2 folding are concerned with its various functional loops. The conformations of these loops determine the efficiency of enzyme action and presence/absence of various pharmacological functions. In the present structure calcium-binding loop is occupied by a sodium ion with a 7-fold co-ordination. The conformation of loop 55-75 in krait PLA2 corresponds to a very high activity of the enzyme. A comparison of its sequence with multimeric PLA2s clearly shows the absence of critical residues such as Tyr3, Trp61 and Phe64, which are involved in the multimerization of PLA2 molecules. The protein shows anticoagulant and neurotoxic activities.

Structure of buffalo lactoferrin at 3.3 A resolution at 277 K

The three-dimensional structure of diferric buffalo lactoferrin has been determined at 3.3 A resolution. The structure was solved by molecular replacement using the coordinates of diferric human lactoferrin as a search model and was refined by simulated annealing (X-PLOR). The final model comprises 5316 protein atoms for all 689 residues, two Fe(3+) and two CO(3)(2-) ions. The final R factor was 21.8% for 11 711 reflections in the resolution range 17.0-3.3 A. The folding of buffalo lactoferrin is essentially similar to that of the other members of the transferrin family. The significant differences are found in the dimensions of the binding cleft and the interlobe orientation. The interlobe interactions are predominantly hydrophobic in nature, thus facilitating the sliding of two lobes owing to external forces. The interdomain interactions are comparable in the N and C lobes.

Structure of buffalo lactoferrin at 2.5 A resolution using crystals grown at 303 K shows different orientations of the N and C lobes

The structure of buffalo lactoferrin has been determined at 303 K. The crystals belong to orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 77.5, b = 91.0, c = 131.5 A and Z = 4. The structure has been refined to an R factor of 0.187. The overall structure of the protein is similar to its structure determined at 277 K in a different crystal form. However, the lobe orientations in the two structures differ by 9.0 degrees, suggesting significant inter-lobe flexibility in this family of proteins. The inter-lobe interactions are predominantly hydrophobic and could act as a cushion for a change in orientation under the influence of external conditions. On the other hand, the domain arrangements are found to be similar in 277 and 303 K crystal structures, with orientations differing by 1.5 and 1.0 degrees in the N and C lobes, respectively. The results of these investigations suggest that the increase in temperature helps in the production of better quality crystals.

Three-dimensional structure of mare diferric lactoferrin at 2.6 A resolution

Lactoferrin is a monomeric glycoprotein with a molecular mass of approximately 80 kDa. The three-dimensional structure of mare diferric lactoferrin (mlf) has been determined at 2.6 A resolution. The protein crystallizes in the space group P 212121with a=85.2 A, b=99.5 A, c=103.1 A with a solvent content of 55 % (v/v). The structure was solved by the molecular replacement method using human diferric lactoferrin as the model. The structure has been refined using XPLOR to a final R -factor of 0.194 for all data in the 15-2.6 A resolution range. The amino acid sequence of mlf was determined using a cDNA method. The final refined model comprises 5281 protein atoms, 2 Fe3+, 2 CO32-and 112 water molecules. The overall folding of mlf is similar to that of other proteins of the transferrin family. The protein folds into two globular lobes, N and C. The lobes are further divided into two domains, N1 and N2, and C1 and C2. The iron-binding cleft is situated between the domains in each lobe. The N lobe appears to be well ordered and is more stable than the C lobe in mlf unlike in other lactoferrins, where the C lobe is the more stable. The opening of the binding cleft in the N lobe of mlf is narrower than those in other proteins of the transferrin family. This is very unusual and is found only in mare lactoferrin. Apart from certain hydrophobic interactions at the mouth of the cleft, one salt-bridge (Lys301 . . . . . . . . Glu216) crosses between the two walls of the cleft. The two lobes are connected covalently by a three-turn alpha-helix involving residues 334-344. The N lobe displays a highly ordered structure with appreciably low temperature factors. The iron coordination is more symmetrical in the N lobe than in the C lobe. There are only 16 intermolecular hydrogen bonds in the structure of mlf.