国产精品国产精品一区精品国产自在现偷99精品国产在热2019国产拍偷精品网国产精品视频全国免费观看,国产精品v欧美精品v日韩精品青青精品视频国产久久国产精品久久精品国产亚洲精品国产精品国产欧美精品一区二区三区,国产精品第一页国产亚洲精品国产福利国产精品自拍国产精品视频在线观看亚洲国产精品一区二区久久国产精品国产三级国产专不,国产精品视频大陆精大陆国产国语精品2019精品国产品对白在线285年香蕉精品国产高清自在自线隔壁老王国产在线精品在线观看精品国产福利片,国产三级精品三级在专区精品国产自在现偷国产精品一区二区三区国产日韩精品欧美一区喷水亚洲精品国产精品国自产国产在线精品一区二区不卡

1. Harvest cells from a culture that is at or near peak density. To detach cells from the wall of the culture tubes place on ice for 10 minutes. Invert tubes several times until the majority of the cells are in suspension. Centrifuge tubes at 800 x g for 5 minutes.
2. Adjust the concentration of cells to 2 x 10⁷/mL in fresh medium.
3. Before centrifuging prepare a 24% (v/v) solution of sterile DMSO in fresh medium containing 8% (w/v) sucrose. The solution is prepared as follows:
   1. Add 1.05 g sucrose to 10 mL of fresh medium and filter sterilize through a 0.2 µm filter;
   2. Add 2.4 mL of DMSO to an ice cold 20 x 150 mm screw-capped test tube;
   3. Place the tube on ice and allow the DMSO to solidify (~5 min) and then add 7.6 mL of ice cold medium prepared in step 3a. The final concentration will be 24% (v/v) DMSO and 8% (w/v) sucrose;
   4. Invert several times to dissolve the DMSO;
   5. Allow to warm to room temperature.
4. Mix the cell preparation and the cryoprotective agent, prepared in step 3, in equal portions. Thus, the final concentration will equal 12% (v/v) DMSO + 4% sucrose (w/v) and 10⁷ cells/mL. The time from the mixing of the cell preparation and DMSO stock solution to the start of the freezing process should be no less than 15 min and no longer than 30 min.
5. Dispense in 0.5 mL aliquots into 1.0 - 2.0 mL sterile plastic screw-capped cryules (special plastic vials for cryopreservation).
6. Place the vials in a controlled rate freezing unit. From room temperature cool at -1°C/min to -40°C. If the freezing unit can compensate for the heat of fusion, maintain rate at -1°C/min through the heat of fusion. At -40°C plunge into liquid nitrogen. Alternatively, place the vials in a Nalgene 1°C freezing apparatus. Place the apparatus at -80°C for 1.5 to 2 hours and then plunge ampules into liquid nitrogen. (The cooling rate in this apparatus is approximately -1°C/min.)
7. The frozen preparations should be stored in either the vapor or liquid phase of a nitrogen refrigerator. Frozen preparations stored below -130°C are stabile indefinitely. Those stored at temperatures above -130°C are progressively less stabile as the storage temperature is elevated.
8. To establish a culture from the frozen state place an ampule in a water bath set at 35°C. Immerse the vial just to a level just above the surface of the frozen material. Do not agitate the vial.
9. Immediately after thawing, do not leave in the water bath, aseptically remove the contents of the ampule and inoculate a 16 x 125 mm screw-capped test tube containing 13 mL ATCC Medium 2695.
10. Incubate the culture on a 15º horizontal slant at 35°C.

Aggarwal A, Nash TE. Antigenic variation of Giardia lamblia in vivo. Infect. Immun. 56: 1420-1423, 1988. PubMed: 3372015

Nash TE, et al. Antigenic variation in Giardia lamblia. J. Immunol. 141: 636-641, 1988. PubMed: 2454999

Pimenta PF, et al. Variant surface antigens of Giardia lamblia are associated with the presence of a thick cell coat: Thin section and label fracture immunocytochemistry survey. Infect. Immun. 59: 3989-3996, 1991. PubMed: 1937758

Lujan HD, et al. Cholesterol starvation induces differentiation of the intestinal parasite Giardia lamblia. Proc. Natl. Acad. Sci. USA 93: 7628-7633, 1996. PubMed: 8755526

Nash TE, et al. Variant specific epitopes of Giardia lamblia. Mol. Biochem. Parasitol. 42: 125-132, 1990. PubMed: 1700296

Miller RL, et al. Identification of Giardia lamblia Isolates Susceptible and Resistant to Infection by the Double-Stranded RNA Virus. Exp. Parasitol. 66: 118-123, 1988. PubMed: 3366209