- Tham gia
- 29/5/2011
- Bài viết
- 54
@All: Cứu Kaguya với!!!
Kaguya có một bài dịch thuật TA! Nhưng khoảng TA của Kaguya thì lại dở như con viết biết bơi! Mà thứ chiều thứ 5 này (19/07/2012) là Kaguya phải nộp bài rùi! (Ông thầy chiết tiệt! Bài thì dài mà cho có 3 ngày đề dịch!
)
Hy vọng có mem nào trong diễn đàn "ra tay nghĩa hiệp" giúp đỡ Kaguya với!
Giúp Kaguya với nha!!!!!!!!!!
Ax! Kaguya gõ xong còn thấy mệt huốn hồ là "anh hùng hay nữ anh hùng dịch"! Chắc là chẳng có hy vọng rùi! 
Kaguya có một bài dịch thuật TA! Nhưng khoảng TA của Kaguya thì lại dở như con viết biết bơi! Mà thứ chiều thứ 5 này (19/07/2012) là Kaguya phải nộp bài rùi! (Ông thầy chiết tiệt! Bài thì dài mà cho có 3 ngày đề dịch!
)Hy vọng có mem nào trong diễn đàn "ra tay nghĩa hiệp" giúp đỡ Kaguya với!
Giúp Kaguya với nha!!!!!!!!!!
Principles
Sometimes it is convenient to determine overall bacterial morphology without the use of harsh staining or heat-fixing techniques that change the shape of cells. This might be the case when the bacterium does not stain well (e.g., some of the spirochetes) or when it is desirable to confirm observations made on the shape and size of bacteria observed in either a wet-mount or
hanging drop slide. Negative staining is also good for viewing capsules (see exercise 11).
Negative, indirect, or background staining is achieved by mixing bacteria with an acidic stain such as nigrosin, India ink, or eosin, and then spreading out the mixture on a slide to form a film. The above stains will not penetrate and stain the bacterial cells due to repulsion between the negative charge of the stains and the negatively charged bacterial wall. Instead, these stains either produce a deposit around the bacteria or produce a dark background so that the bacteria
appear as unstained cells with a clear area around them (figure 6.1).
Figure 6.1 India Ink Stain of Bacillus megaterium (-1,000).
Notice the dark background around the clear bacterial cells.
Procedure
1. With a wax pencil, label the left-hand corner of three glass slides with the names of the respective bacteria.
2. Use an inoculating loop to apply a small amount of bacteria to one end of a clean microscope slide (figure 6.2a - Inoculating loop. 1–2 drops of bacterial culture. (a) Clean glass slide).
3. Add 1 to 2 loops of nigrosin, India ink, or eosin solution to the bacteria (figure 6.2b - 1–2 drops of nigrosin or other stain) and mix)) and mix thoroughly.
4. Spread the mixture over the slide using a second slide. The second slide should be held at a 45° angle so that the bacteria-nigrosin solution spreads across its edge (figure 6.2c - Second slide (45º angle with first slide). Bacteria–nigrosin suspension spreads along edge of slide). The slide is then pushed across the surface of the first slide in order to form a smear that is thick at one end and thin at the other (figure 6.2d - Direction of movement). This is known as a thin smear.
5. Allow the smear to air dry (figure 6.2e - Air dry. Stained material forms a thin feathered film). Do not heat-fix!
6. With the low-power objective, find an area of the smear that is of the optimal thickness for
observation.
7. Use the oil immersion lens to observe and draw the three bacterial species in the report for exercise 6.
HINTS AND PRECAUTIONS
(1) For a successful thin smear, the slides must be absolutely clean and free from oil and grease—including fingerprints. (2) If an inconsistent smear is obtained, it is better to prepare a new slide than to search unsuccessfully for an appropriate area on a poorly stained slide. (3) Do not use too much stain; use only a small drop of nigrosin. (4) The mixture must be drawn over the slide, not pushed. Drawing the mixture over the slide will produce a more uniform film. (5) Prepare a smear that consists of a thin layer of cells without clumps. (6) View the thinner or clearer portions of the film.
Sometimes it is convenient to determine overall bacterial morphology without the use of harsh staining or heat-fixing techniques that change the shape of cells. This might be the case when the bacterium does not stain well (e.g., some of the spirochetes) or when it is desirable to confirm observations made on the shape and size of bacteria observed in either a wet-mount or
hanging drop slide. Negative staining is also good for viewing capsules (see exercise 11).
Negative, indirect, or background staining is achieved by mixing bacteria with an acidic stain such as nigrosin, India ink, or eosin, and then spreading out the mixture on a slide to form a film. The above stains will not penetrate and stain the bacterial cells due to repulsion between the negative charge of the stains and the negatively charged bacterial wall. Instead, these stains either produce a deposit around the bacteria or produce a dark background so that the bacteria
appear as unstained cells with a clear area around them (figure 6.1).
Figure 6.1 India Ink Stain of Bacillus megaterium (-1,000).
Notice the dark background around the clear bacterial cells.
Procedure
1. With a wax pencil, label the left-hand corner of three glass slides with the names of the respective bacteria.
2. Use an inoculating loop to apply a small amount of bacteria to one end of a clean microscope slide (figure 6.2a - Inoculating loop. 1–2 drops of bacterial culture. (a) Clean glass slide).
3. Add 1 to 2 loops of nigrosin, India ink, or eosin solution to the bacteria (figure 6.2b - 1–2 drops of nigrosin or other stain) and mix)) and mix thoroughly.
4. Spread the mixture over the slide using a second slide. The second slide should be held at a 45° angle so that the bacteria-nigrosin solution spreads across its edge (figure 6.2c - Second slide (45º angle with first slide). Bacteria–nigrosin suspension spreads along edge of slide). The slide is then pushed across the surface of the first slide in order to form a smear that is thick at one end and thin at the other (figure 6.2d - Direction of movement). This is known as a thin smear.
5. Allow the smear to air dry (figure 6.2e - Air dry. Stained material forms a thin feathered film). Do not heat-fix!
6. With the low-power objective, find an area of the smear that is of the optimal thickness for
observation.
7. Use the oil immersion lens to observe and draw the three bacterial species in the report for exercise 6.
HINTS AND PRECAUTIONS
(1) For a successful thin smear, the slides must be absolutely clean and free from oil and grease—including fingerprints. (2) If an inconsistent smear is obtained, it is better to prepare a new slide than to search unsuccessfully for an appropriate area on a poorly stained slide. (3) Do not use too much stain; use only a small drop of nigrosin. (4) The mixture must be drawn over the slide, not pushed. Drawing the mixture over the slide will produce a more uniform film. (5) Prepare a smear that consists of a thin layer of cells without clumps. (6) View the thinner or clearer portions of the film.
