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  1. Jul 2019
    1. Transformation of ligation mixture in electro-competent E. coli host cells (DH5ααααstrain)
    2. Analysis of PCR amplicons using agarose gel electrophoresis
    3. Qualitative analysis of DNA by agarose gel electrophoresi
  2. Jun 2019
  3. May 2019
    1. 1X PBS diluted in distilled water 1X fixative solution diluted in distilled water Staining Solution25 μl Solution A 25 μl Solution B 25 μl Solution C 125 μl 20 mg/ml X-gal in DMF
    2. Working Solutions:
    1. and a colourless upper aqueous phase. The upper aqueous phase in which RNA existsexclusively, was transferred to a fresh microfuge tube and RNA was precipitated byadding 0.5 ml of isopropyl alcohol for each ml of Trizol used. Samples were incubatedat 15 to 30ºC for 10-min and centrifuged at 12000 rpm for 10-min at 4ºC. RNA formeda gel like precipitate at the bottom of the tube. Supernatant was removed and RNA waswashed with 75% ethanol (by adding 1 ml of ethanol per ml of Trizolemployed). RNAcould be stored after this step in –20 or –70ºC for more than a year. RNA pellet was airdried for 15-to 30-min following which it was dissolved in nuclease free water. Theconcentrations and purity of RNA samples were determined spectroscopically as wellas by visual inspection on formaldehyde-agarose gel in MOPS buffer (Goodet al., 1996). Before loading onto the gel, RNA was mixed with loading buffer and heated at90ºC for 3-min
    2. For isolation of RNA, cells were grown in minimal A medium supplemented with 0.2%glucose upto A600of 0.6. Cells were harvested by centrifugation and total RNA wasisolated by using Trizol (Invitrogen) according to manufacturer’s instructions. 1 ml ofTrizol was used to lyse cells equivalent of approximately 4 ml of overnight culture.Homogeneous lysis was achieved by gentle pipetting repeatedly. The homogenized samples were incubated at room temperature for 5-min to permit complete dissociationof nucleoprotein particles. Following homogenization, 0.2 ml of chloroform for each 1ml Trizol reagent was added and vigorously shaken with hand for 15-sec and incubatedfurther for 3-min at RT. It was then centrifuged at 12000 rpm for 10-min at 4ºC, whichseparates out the homogenate into lower phenol chloroform phase (red), an interphase
    3. Isolation of total cellular RNA
    4. Around 0.5 to 1 μg of DNA was regularly used for each restriction digestion. 2to 5units of restriction enzyme were used in the total reaction volume of 20 μl containing 2μl of the corresponding buffer supplied at 10 X concentration by the manufacturer. Thereaction was incubated for 2 hrs at the temperature recommended by the manufacturer.The DNA fragments were visualised by ethidium bromide staining after electrophoresison a 0.8 to 1% agarose gels. Commercially available DNA size markers were run alongwith the digestion samples to compare with and to estimate the sizes of the restrictionfragments
    5. Restriction enzyme digestion and analysis
    6. The colonies to be tested were streaked on the surface of minimal A-glucose plates containing either 0.4-0.7 M NaCl with 1 mM glycine betaine, and incubated at 37oC. NaCl-tolerant strains grew toform single colonies in 36-60 hrs whereas NaCl-sensitive ones did not. As controls, MC4100 (WT) and other previously identified NaCl sensitive mutants were streakedfor comparison
    7. NaCl-sensitivity testing
    1. stranded DNA. Final reaction volume was adjusted to 20 μl with DEPC-treated waterandamplificationreaction was carried out usingthese parameters: initial denaturation at 95 ̊C for 5 min followed by 40 cycles of denaturationat 95 ̊C for 30 sec, annealing at 55 ̊C-57 ̊C for 30 sec, elongation at 72 ̊C for 40 sec and final extension at 72 ̊C for 10 min. Transcript levelswerequantified with an end-point value known as Ct (cycle threshold). The Ctdefines the number of PCR cycles required forthe fluorescent signal of SYBR green dye to cross more than the background level. The Ctvalue isinversely proportional to the amount of nucleic acid product. Ctvalues were obtained during exponential phase of amplification and used forcalculation of relative-fold change in gene expression after normalization to Ctvalues ofeither housekeeping gene ACT1 (gene encoding actin)orTDH3 (gene encoding Gapdh)with the help of the following formula. Fold change in expression = 2-∆∆Ct∆∆Ct= ∆Cttreated -∆Ctuntreated∆Cttreated = Ctvalue forgene of interest under test/treatedcondition -Ctvalue forinternal controlgene(ACT1/TDH3) under test/treatedcondition∆Ctuntreated = Ctvalue forgene of interest under untreatedcondition -Ctvalue forinternal control (ACT1/TDH3)gene under untreatedcondition
    2. Todeterminethe expression level of a specific gene, quantitative real-time polymerase chain reaction (qRT-PCR/qPCR)was performed oncDNA usinggene specific primers. Primers for qPCR weredesigned in such a way so as to get amplification products in a size range of 150 to 300 bp. Optimalprimer and cDNA concentrationswere standardized and qPCR was performed in ABI Prism 7000/7500 Real time PCR Machine (Applied Biosystems). Briefly, 0.4 μl cDNA was mixed with 0.1 to 0.2 picomolesof gene specific forward and reverse primers and 10 μl 2X MESA GREEN qPCR™Mastermix Plus containing SYBR green dye (Eurogentec) in awell of a96-well PCR plate (Axygen). SYBR green is a dye that specifically binds to double
    3. Quantitative real-time polymerase chain reaction (qRT-PCR)
    1. 10 mg phosphatidylinositol-sodium salt(from Glycine max)was dissolved in 2 ml chloroform to prepare a 5 mg/ml stock solution. This solution was prepared in a small glass vial aschloroformis known to reactwith polypropylene. Small aliquots of stock solution were madeand stored at -20ºC till further use. To avoid spillage due to vapor pressure, vials containing phosphatidylinositol-sodium salt solutionwereopened very carefully.To prepare sonicated phosphatidylinositolfor one PI-3 kinase reaction, 2 μlof the stock phosphatidylinositolsolution (10 μg) wastransferredtoanew1.5 ml microcentrifuge tube. Using vacuum evaporator apparatus, chloroformwas evaporated from the solution and phosphatidylinositol-sodium saltwas resuspended in 5 μl sonication buffer.For sonication, a total of 20 pulses, each of 30 sec with30 sec resting time weregiven on ice
    2. Preparation and sonication of phosphatidylinositol-sodium salt solution
    3. homogenizedin 1 ml PBS and fungal burden was assessed by plating appropriate dilutions of tissue homogenate on YPD plates containing penicillin and streptomycinantibiotics (100units/mlpenicillin and 100μg/mlstreptomycin). All mice experiments were repeated twice with a set of 7-8 mice per strain in each experiment
    4. Experiments involving mice were conducted at VIMTA Labs, Hyderabad.100 l YPD-grown C.glabratacellsuspension(4 X 107cells)was injected into female BALB/c mice (6-8 weeks old) through tail vein. Seven dayspost infection, mice weresacrificedand kidneys, liver,spleenand brainwere harvested. Organs were
    5. Mouse infection assay
    6. Identified mutants were phenotypically characterized in 96-well plate format. Mutant cultures were grown in YPD medium for overnight, diluted 150-fold in PBS and 5 μl of cell suspension was spotted on different plates with a 96-pin replicator. Growth was recorded after 1-2 daysof incubation at 30°C
    7. Phenotypic profiling
    1. Agarose gels were preparedby boiling appropriate amount of agarose in TAEbuffer. After dissolution, it was cooled and then poured in a casting tray containing a comb for desired number of wells. The gel was allowed to solidify and then shifted to horizontal electrophoresis tank containing TAE buffer. The DNA samples were mixed with appropriate volumes of 6X DNA loading dye, loaded on the gel andelectrophoresedat appropriate voltage and current conditions (generally 80 V,400 mA). The gel was stained in ethidium bromide solution(1 μg/ml)for 15-min at room temperature and visualisedby fluorescence under UV-light in a UV-transilluminator
    2. Agarose Gel Electrophoresis
    1. Complementary-DNA synthesis was performed using reverse transcriptase enzyme (Invitrogen) and random hexamers (Qiagen). For this, 1 μg good quality RNA was treated with 1 μl (1 unit) DNase I (Invitrogen) for 20 min to remove DNA contamination. Next, Superscript III Reverse Transcriptase kit (Invitrogen) was used to synthesize cDNA according to the manufacturer’s instructions. cDNA synthesized was further confirmed by using it as a template for amplification in PCR. cDNA was stored at -20°C till further use
    2. Synthesis of complementary DNA (cDNA)
    1. For mouse infection assay, 10 ml YPD medium was inoculated with different C. glabratastrains and allowed to grow at 30°C for 12-16 h. After growth,cultures were washed twice in sterile 1X PBS and the cell pellet was resuspended in appropriate volume of 1X PBSto obtain a cell density corresponding to20OD600. 100 μlcell suspension(4x107yeast cells)was injected into female BALB/c mice (6-8 weeks old) through tailvein. Seven days post
    2. infection, mice were sacrificed and kidneys, liver, brain and spleen were harvested. Organs were homogenised in 1 ml PBS and appropriate dilutions of tissue homogenate were plated onYPD-agar mediumsupplemented with penicillin and streptomycin antibiotics (100 units/ml penicillin and 100 μg/ml streptomycin). Plates were incubated at 30°C for 24-48 h and CFUs were counted. Fungal burden in different organs wasdetermined by multiplying the CFUsobtainedwithanappropriate dilution factor
    3. For mouse infection assay, 10 ml YPD medium was inoculated with different C. glabratastrains and allowed to grow at 30°C for 12-16 h. After growth,cultures were washed twice in sterile 1X PBS and the cell pellet was resuspended in appropriate volume of 1X PBSto obtain a cell density corresponding to20OD600. 100 μlcell suspension(4x107yeast cells)was injected into female BALB/c mice (6-8 weeks old) through tailvein. Seven days post
    4. Mouse infection assay
    5. ml YPD broth at an initial OD600of 0.1. Cultures were allowed to grow for 4-5 hin a shaker incubator setat 30°C, 200 rpm until the OD600of the cultures reached 0.4-0.6. Next,cells were harvested ina15 ml centrifuge tube by centrifugation, washed twice with 10 ml of sterile water, resuspended in 1 ml of sterile water and were transferred to a 1.5 ml microfuge tube. Cells were harvested by centrifugation at 4,000 rpm for 5 min,resuspended in 50 μl of100 mM lithium acetate solution and transformation mixture was added. Transformation mixture consisted of 240 μl polyethylene glycol (50%), 36 μl of lithium acetate (1 M), 5 μl of heat denatured single stranded carrier DNA (10 mg/ml), 500 ng to 1 μg of transforming DNA and final volume was made to 360 μl with sterile water. The tubes were incubated at 30°C for 45 min. To this, 43 μl of sterile DMSO was added and heat shock was given at 42°C for 15 min. Next, tubeswere transferred to ice for 10-15 sec, centrifuged at 4,000 rpm and transformation mixture reagents wereremoved completely by pipetting. Cells were resuspended in 200 μl of sterile water and spread-plated on appropriate selection medium. Plates were incubated at 30°C for 24-48 h
    6. Yeast transformation was performed as described previously (Gietz et al., 1992) with fewmodifications. Briefly, overnight grown C. glabratacultures were freshly inoculated in 10
    7. Yeast transformation