Quantitative screening for determination of xylanase in shake flask

Sonicated cells of E. coli having recombinant vector was centrifuged. Supernatant was dispensed into 0.2 % v/v xylan agar plate and incubated for 4 h. The plates were then flooded with Congo red solution (0.2 % w/v) for 30 min and destained with 1M NaCl solution till a clear zone of xylan hydrolysis was visible. The plates were gently shaken on a shaker to accelerate the process of staining/destaining

Qualitative detection of xylanolytic activity by plate assay

DETECTION OF XYLANASE ACTIVITY

All site-directed mutagenesis studies were performed usmg the QuickChange mutagenesis kit (Stratagene) following the manufacturer's instructions. It is a PCR based method for introducing point mutations, replace amino acids and delete or insert single or multiple amino acids into desired plasmid constructs. Primers containing mutations were designed and PCRs were performed using "wildtype" construct as template. The PCR product was' subjected to digestion with DpnI endonuclease, which is specific for methylated DNA. Following DpnJ digestion, the parental DNA template gets cleaved and DNA containing desired,mutation is selected. The residual mutant nicked DNA was transformed in E. coli DH5a competent cells and the resulting plasmids were isolated and sequenced to confirm incorporation of the desired mutations.

ite directed mutagenesi

cold PBS followed by incubation with fluorophore labeled secondary antibody at appropriate dilution for 30 min at 4°C. The fluorescence was then visualized under a fluorescence microscope or analyzed by flow cytometry

Immunostaining in Live cells: Immunostaining on live cells was performed by harvesting and resuspending cells in ice-cold PBS. The cells were then incubated with an appropriate dilution of the primary antibody for 1 h at 4 °C following which two washes were given with ice-

Immunostaining in fixed cells: The cells were fixed with 4% formaldehyde for 20 min, following which two washes were given with ice-cold PBS. Permeabilization and blocking were performed simultaneously by incubating the formaldehyde fixed cells in PBS containing 0.1% saponin and 3% normal goat serum for 30 min. The cells were washed once with ice-cold PBS. The permeabilized cells were incubated with the primary antibody at an appropriate dilution for 1 h at room temperature following which three washes with ice-cold PBS was given. These cells were then incubated with fluorophore conjugated secondary antibody (IgG) for 1 hat room temperature following which three washes with ice-cold PBS were given. The nuclei were stained with Hoechst 33342 at a concentration of 1 Jlg/mL for 2 min at room temperature. The staining was then visualized under a Nikon TE2000E fluorescence microscope using appropriate filter blocks. Image acquisition was carried out using a high-resolution Retiga Exi camera (Q-imaging, Surrey, BC, Canada) and subsequent image analysis was performed on Image-Pro Plus software v5.5 (Media Cybernetics, Silver Spring, MD). Alternatively, the fluorescence staining was detected by flow-cytometry (BD-LSR, Beckton Dickinson, NJ, USA) using an air-cooled argon ion laser (488 nm) at appropriate florescence channels. Subsequent data analysis was performed on WinMdi software (Microsoft, v 2.9)

Immunocytochemistry

checks the stereochemical quality of protein structures. The output of the program consists of comprehensive listings of the stereochemical parameters. These files were analyzed to determine if the error in the various stereochemical parameters were within acceptable limits. If any parameter ofthe model was found to be outside the accepted range, they were corrected by adjustment of the concerned residue followed by refinement. The elbow angles of all the Fab structures were calculated using web based applet developed by Standfield et a/ (Stanfield et al., 2006). The buried surface areas (i.e. the area rendered inaccessible to a 1.4 A sphere) were determined using PISA web server (Krissinel and Henr:ck, 2007). CONTACT program of the CCP4 package (Elizabeth Potterton, 2003) was used to determine van der Waals contacts and hydrogen bonds between peptide and Fab. Vander Waals contacts were defined to be present between atoms if they were within 4 A of each other. Hydrogen bonds were assigned for donors and acceptor atoms when the distance between them is less than 3.5 A. In case of hydrogen bonds where the nitrogen atom is the donor, the N-H ... O angle should be greater than 120°. When an oxygen atom is the donor, a cut off value of 90° was used. All Fab-peptide complexes ofmAbs; BBE6.12H3 and 36-65 were compared in terms of various parameters such as elbow angle, peptide and CDR conformation, buried surface area, van der Waal contacts and hydrogen bonding. To compare conformations, RMSD in the position of the Ca as well as all atoms were calculated using SUPERPOSE program of CCP4 package (Krissinel and Henrick, 2004). The CDR conformations in the liganded and unliganded forms were also compared.

Deviations from ideal geometry of the various structures were analyzed using PROCHECK (R. A. Laskowski, 1993) from the CCP4 suite. PROCHECK

Validation, analysis and comparison of models

of the plasmid DNA with 0.5 volume of cold isopropanol. The mixture was kept on ice for 10 min. and centrifuged at 12,000 rpm at 4°C for 15 min. DNA pellet thus obtained was washed with 80% ethanol, dried and dissolved in 50 J.!l TE buffer (pH 8.0). Minipreps were screened by restriction digestion. 5 J.tl of plasmid DNA was incubated with 5 units of appropriate enzyme(s) and 150 units of RNaseT1 for 2 h and the products were analyzed on an agarose gel to identify the positive clones.

5 ml LB containing 100 J.tg/ml of ampicillin was inoculated with single. bacterial colony picked from the culture plates. The culture was grown for 12 h at 37 °C with vigorous shaking. Cells were harvested from 3 ml of culture by centrifugation at 3000 rpm in a microfuge (Plastocraft) at 4 °C for 15 min. Added 200 J.tl of TEG buffer was added to the cells, and tt.ey were gently resusupended to get a uniform suspension and kept on ice for 5 min. 400 J.tl of freshly prepared alkaline-SDS solution was added to the cell suspension and mixed well by inverting the tubes followed by an incubation on ice for 10 min. Subsequently, 300 J.ll of chilled potassium acetate solution was added and mixed thoroughly by vortexing. The mixture was centrifuged at I 0.000 rpm at 4 °C for 15 min.. The supernatant was collected and phenol-chloroform extraction was performed followed by precipitation

Mini Plas~id Preparation and Screening

Progesterone levels were estimated from sera of bonnet monkeys which were bled biweekly using a radioimmunoassay employing reagents and protocol as prescribed by the W.H.O. Matched Assay Reagent Programme (Sufi et al., 1983). Each sample was run in duplicates. Progesterone was extracted from serum (0.1 ml) by the addition of 2 ml of ice-cold ether in each tube and vortexing for 2 min. The tube was immersed in liquid nitrogen in order to flash freeze the serum phase and the unfrozen ether phase which contained the extracted steroid hormone was decanted into another tube. The ether was allowed to evaporate 0/N and 0.5 ml of steroid assay buffer (0.1 M PBS, pH 7 .3, 0. 1% thiomersal and 0.1% gelatin) was added to the tubes and the tubes were incubated at 40°C for 30 min. Steroid sticking to the walls of the tubes was recovered by vigorous vortexing. 100 J..LI of anti-progesterone Ab (at a dilution giving -50% binding of tritiated p.rogesterone in the absence of unlabelled competing progesterone) was then added to the tubes followed by addition of 0.1 ml of 3H-progesterone ( -10,000 cpm/tube). The mixture was incubated for atleast 16 hrs at 4oc. Unbound progesterone

was separated by addition of 0.2 ml of ice cold assay buffer containing 0.625% activated charcoal and 0.0625% dextran and incubated for 30 min at 4oc. This was followed by centrifugation at 2500 rpm for I 5 min at 4°C. The supernatant was carefully decanted into scintillation vials and 4 ml of scintillation fluid (0.4% 2,5 diphenoxazole; 0.01% POPOP [1-4 bis(5-phenyl-2-oxazolyl)benzene] in sulfur free toluene) was added and counted in a liquid scintillation beta counter (Beckman Instruments, California, USA). The amount of progesterone per ml of serum was calculated from a standard curve with known amounts of progesterone in each assay.

Progesterone Radioimmunoassays

Expression conditions for bZP3 under the polyhedrin promoter were standardized using the Northern blot and Western blot analysis of cells infected with the VI virus. Sf9 cells, seeded at a density of 1.5 million in a 35 mm petridish were allowed to attach for I h at 27oc. The medium was removed and the cells were infected with AcNPV (Autographa californica nuclear polyhedrosis virus) or VI at -10 MOl for 1 h. The infected cells were harvested at different time points from 0-84 h pi. The cells (-2X I o6) were washed with chilled PBS and resuspended in I ml of denaturing solution ( 4 M GITC, 25 mM sodium citrate, pH 7, 0.5% sarcosyl, and 0.1 M BME) followed by addition of 50 Jll of 2 M sodium acetate (pH 4) and 500 Jll water saturated phenol and 1 00 Jll chloroform:isoamyl alcohol ( 49: 1 ). The suspension was mixed thoroughly after the addition of each reagent, vortexed for 1 0 sec and cooled on ice for 15 min. The aqueous and the phenol phases were separated by centrifugation at 12,000 rpm for 20 min in a refrigerated microfuge. The aqueous phase was transferred to a fresh tube and 500 Jll isopropanol was added. RNA was precipitated at -20°C for 1 h, and pelleted at 12,000 rpm for 20 min at 40C. The RNA pellet was dissolved in 300 Jll denaturing solution followed by addition of 300 Jll of isopropanol. RNA was reprecipitated at -2ooc for 1 h, washed with 75% ethanol and the pellet collected by centrifugation at 12,000 rpm in a refrigerated microfuge. RNA was dissolved in 25 Jll of 0.5% SDS by heating at 65°C for 10 min and stored at -700C. RNA was quantitated and 5 Jlg of RNA corresponding to each time point was resolved on a 1.2% agarose formaldehyde gel, transferred to a nylon membrane and probed with 32p labeled bZP3 probe. Cells harvested at different time points from -2X 106 cells 12-84 h pi were pelleted down, washed with 10 mM PBS, pH 7.4, and lysed in reducing buffer and resolved on a 0.1% SDS-10% PAGE as described earlier. The supernatant was concentrated to lOX for loading on the gel.

Expression 'Of bZP3 in BEVS

Double stranded plasmid pBluescript-bZP3 DNA was sequenced using Sanger's dideoxy chain termination method (Sanger et al., 1977) using the Sequenase version 2.0 kit according to the protocols recommended by the manufacturer. Purified plasmid DNA (5 J..Lg) and 2 pM of the sequencing primer was used in the sequencing reaction. Table 2 gives a list of the primers used for sequencing of the bZP3 eDNA clones. bZP3 sequence was confirmed by sequencing three independent clones 401, 403 and 404.

Sequencing of bZP3

minigel alongwith unligated vector to test the ligation. The ligated DNA was used to transform competent ~.coli cells.

Wherever possible, the cloning of DNA fragments was achieved by ligation of compatible sticky ends generated on the vector as well as the insert by digestion with the same enzyme. Self ligation of the linearised vector with compatible sticky ends was minimised by dephosphorylation of the vector DNA using bacterial alkaline phosphatase. The ligation conditions for each batch of T4 DNA ligase were standardised using Hind III generated fragments of lambda DNA as a test sample for sticky end ligation. Routinely, 200 ng of vector DNA was mixed with 2 - 5 fold molar excess of the insert fragment DNA, 2 ul each of the 10 X ligase buffer 500 mM Tris. HCl, pH 7. 5, 100 mM Mgcl2 ) , 10 mM ATP, and 200 mM DTT. The final reaction volume was adjusted to 15 - 2 0 ul with sterile double distilled water, and 0.5 - 1 ul of T4 DNA ligase ( 103 units I ml ) was added. The contents were mixed well and incubated at 13°C for 12 -16 hours. An aliquot of 2 ul was electrophoresed on a

Ligation of DNA fragments.

separately on LB plates containing 100 j...tg/ml ampicillin, 80 j...tg/ml of X-gal and 20 mM of IPTG. The plates were incubated at 37°C for 12 h.

The DH5a strain of E. coli was grown overnight (0/N) in LB at 37°C and subcultured ( 1: 1 OO)in 100 ml of fresh LB. The culture was grown until absorbance at 600 nm (A6oo) reached 0.4. The culture was centrifuged at 2500 X g for 15 min at 4°C. The cell pellet was resuspended in 10 ml of freshly prepared sterile ice cold CaC}z (100 mM) solution and incubated for 30 min on ice. Cells were centrifuged at 1800 X g and the pellet was very gently resuspended in 2 ml of chilled CaCh (100 mM) containing 15% glycerol. Aliquots of 100 111 were dispensed into sterile, chilled 1.5 ml eppendorf tubes and stored at -70°C until further use. For transformation, the ligation products from the above reactions were added separately to a vial each of DH5a competent cells thawed on ice. The contents were gently mixed and incubated on ice for 30 min. The cells were then exposed to heat shock at 42°C for 90 sec and incubated on ice for another 2 min. The transformed cells were grown in 1 ml of LB medium for lh at 37°C with shaking for the expression of the ampicillin resistance marker gene W-lactamase). Aliquots from each transformation were plated

Preparation of competent cells and transformation

Thecapabilityofheadkidneyneutrophilstomovewasassayedbyamigration-under-agarosetechniquemodifiedfromNelsonetal.(1975).ThemethodhasbeendescribedbySaloetal.(1998).Thedistance,thecellshadmigratedfromthemarginofthewelltowardsthewellcontainingcasein(directedmigration)andintheopposite direction(randommigration)weremeasuredunderthemicroscope.

Migration

Thereactionproduction,p-nitrophenolinacidphosphatewasmeasuredspectrophotometricallyat415nmagainstreagentblank.Theenzymeactivitywascalculatedfromthestandardcurveandexpressedasmicromolesofp-nitrophenolformedperhourpermilligramprotein.Therateofhydrolysisofp-nitrophenolphophateisproportionaltotheenzymepresentinthetissue.p-nitrophenylphosphate+NaoH—phosphat?-—>p -nitrophenol+phosphateThecolordevelopedinalkalinephosphataseactivitywasreadat410nmagainstreagentblankspectrophotometrically.Theactivityoftheenzymewasexpressedaspmolphenolformedmin'1mg'1protein

ThealkalinephosphataseactivitywasestimatedbythemethodofMorton(1955)usingp-nitrophenylphosphatesocolorlessinsolutionbutuponhydrolysis,thephosphategroupliberatesp-nitrophenylwhichishighlycoloredinalkalinesolution

Alkalinephosphatase(AKP:ortho-phosphoricmonoester-phosphohydrolase;E.C.3.1.3.1)

SamplesofC.punctataweretakenfromtheacclimationtanksandslightlyblottedonpapertowelstoremoveexcesswater.TheywereplacedindividuallyonaWhatmanfilterpaperinaonelitreglassbeaker.Theindividualswereimmediatelytransferredtobigglassdesiccatorscontaining250mlofthefollowingsolutionsfordesiredhumiditylevelsusinggradedsolutionsofKOHasdescribedbySolomon(1951).Watergiving95to97%relativehumidity(RH),mean95%;sodiumchloridegiving72to76%relativehumidity,mean75%;calciumchloridegiving28to31%relativehumidity,mean35%.Thedesiccatorswereplacedinanincubatorataconstanttemperatureof28°±1°Cwithdeterminationsofsurvivalandbodyweightatregularintervals.Thecontainerswereweighedatintervalstothenearest0.1mgandweightlosswasassumedtoequalwater loss

Survivaloutofwater

dried. These were counted directly to determine the total counts. In duplicate tubes, 1pl of the diluted probe was added to 100pg of carrier nucleic acid (tRNA or Herring Sperm DNA) in a total volume of 100pl. To this 500pl of ice-cold 5% TCA was added, mixed thoroughly and incubated on ice for 15-20 min. Glass fiber filters were wet (in duplicate) properly with 5% TCA and then these samples were applied on to them under vacuum. The filters were washed twice with 5ml of chilled 5% TCA and then air dried after rinsing with 2m1 of acetone. All the dry filters were inserted into scintillation vials containing scintillation fluid and the counts were taken in a liquid scintillation a-counter (LKB Wallac, 1219 Rackbeta, Sweden). The percentage incorporation, specific activity and the total amount of RNA made was then calculated according to the standard procedures. % incorporation =Incorporated cpm X100 Totalcpm Total RNA made (ng) = % incorporation X 338 Specific activity of probe = Total cpm incorporated p.g of RNA synthesized

To determine the percentage of incorporation and probe specific activity, 1:10 dilution of the labeled probe was made in NFW. lpl of this was spotted on to duplicate glass fiber filters (Whatman GF/ A, U.S.A.) and ai

richloro acetic acid (TCA) precipitation:

were then centrifuged at 1065 x g for 5 min at 4°C. The pellet obtained was resuspended in 1mL ice cold PBS and washed 5 times with PBS. Finally the pellet was resuspended in 1mL lysis buffer (10mM Tris-HCl containing 0.1% Triton X-100) and fluorescence was measured at 380nm/525nm. To normalize different samples and account for any errors in cell number between samples, 10011L of the above sample was also used for protein estimation, carried out as described above

Monodansylcadaverine (MDC) is a selective marker for autophagic vacuoles (Biederbick et al., 1995). It is an auto-fluorescent drug accumulates in acidic compartments by ion trapping and also is thought to interact with the membrane lipids of the vacuoles. Stock MDC (50mm, prepared in acetic acid) was diluted to a concentration of 50!lM in M199 medium containing 10%FBS. 107 parasites after appropriate treatment were resuspended in 1mL of working stock and incubated in the dark for 10 min at RT. These

Assay for measuring the level of autophagy in Leishmania parasites (MDC staining)

DNA fragments were resolved on 1-2 % agarose gel containing 0.5~-tg/mL ethidium bromide in Tris-Acetate-EDTA (TAE) buffer (40mM Iris-acetate, 2mM EDTA, pH 8.1). The samples were mixed with equal volume of 2X loading dye containing bromophenol blue, and the samples resolved by applying a voltage of 5-7 V /em. The resolved DNA fragments were visualized under ultraviolet illumination (312nm) and the relative band size was determined by comparison against DNA ladder with bands of known sizes. When required the images were acquired using a UVP Gel Documentation system

Agarose gel electrophoresis

To 1.0 ml of suitably diluted culture filtrate, 5.0 ml of solution C was added. It was incubated for 10 min at room temperature. To this, 0.5 ml of Folin Ciocalteau’s reagent (diluted 1:1 with distilled water) was added. The solution was vortexed and kept in dark for 30 min. After incubation, absorbance was read at 660 nm against a reagent blank. Protein content was calculated (in mg/ml) using standard curve of bovine serum albumin (BSA) prepared in the range 100-1000 μg/ml

The total protein content in the culture filtrate was estimated by Lowry’s method as described below: Reagents: Solution A: 2.0% Na2CO3 in 0.1 N NaOHSolution B: 0.5 % CuSO4 in 1.0 % Sodium potassium tartarate Solution C: 50.0 ml of solution A was mixed with 1.0 ml of solution B Folin Ciocalteau’s reagent

Protein estimation (Lowry et al., 1951)

Viewing slides under microscope

A drop of immersion oil was put on top of the cover-slip before viewing it under microscope. The cells were viewed at 100X resolution of Nikon Eclipse 80i microscope.Thedifferential interference contrast images of the cells were captured using NIS-Elements D3.0 software also used to find out mean cell size using at least 100 randomly selected cells.Fluorescence images were captured on Zeiss LSM 710 Meta inverted confocal microscope

The slides for microscopy were prepared as described in Dajkovic et al.,(2008)with slight modifications. After wiping the glass slide with ethanol, 200μL of 1% molten agarose was layered on it between two strips of tape and clean cover-slip placed on it to obtain levelled surface. The agarose was allowed to solidify and the cover-slip was carefully removed and5μlof sample was put on top of the agarose and carefully covered with a cover-slip

Preparation of microscopic slides

Fresh overnight cultures grown in LB containing appropriate antibiotics to select for plasmids were sub-cultured 1:100(or lower dilutions for some strains)in the same medium. The cells from these cultures weretaken for microscopy at exponential phase of growth(A600 of 0.5-0.6), as such or after concentrating the cells 10-fold

Sample preparation

Microscopy

Band intensities in gel autoradiogramswere determined by densitometry with the aid of the Fujifilm Multi Gauge V3.0 imaging system. Equal areas of radioactive bands were boxed and the PSL (Photo stimulated luminescence) values were further considered. Background signal (obtained from equal area as that of the radioactive band but from other part of the gel/blot) is subtracted from the signal intensities obtained from radioactive bands to get the final values

Densitometry

β-Galactosidase assay was performed according to(Miller, 1992).Cultures were grown to A600 of 0.4-0.6 from a 1:100 dilution of overnight cultures. Around 0.1-0.5 ml of culture was made up to 1 ml with Z-buffer and lysed with the addition of 100μl of chloroform and 50μl of 0.01% SDS solution. 0.2ml of freshly prepared 4mg/ml ONPG was added to start the reaction and incubated at 28oCtill the colour of the reaction mixture turned yellow. 0.5ml of 1M Na2CO3 was added to stop the reaction and the time duration from initial addition of ONPG to the stopping of the reaction was noted. The absorbance of reaction mix was taken at 420 nm (A420) afterspinning down the mix at 12000rpm for 3 minutes. The A600of the culturesused was also noted. The enzyme’sspecific activity (in Miller units) was calculated using the following equation: β-Galactosidase specific activity (Miller units) = (1000 ×A420) / t × v ×A600Where,‘t’ is the time period in minutes and ‘v’, the volume of culture used in ml