Micronucleus Test

Question 1

DNA fragment that is separated from the main nucleus and has originated from a chromosome or fragment of a chromosome that fail to be included into one of the daughter nuclei during cell division

Answer 1

Micronucleus / Micronuclei (Howell-Jolly bodies)

Question 2

Proponent of Howell-Jolly bodies

Answer 2

William Howell & Justin Jolly

Question 3

Micronucleus / Micronuclei is an extracellular biomarker for _______________, which is used to assess toxicity

Answer 3

Chromosomal damage

Question 4

Micronucleus / Micronuclei are typically round with a diameter of about ________ to _______ of the erythrocytes. They are almost __________-shaped (clue: nut)

Answer 4

1/20; 1/5; almond

Question 5

This stage of cell division is where chromosomal breaks happen

Answer 5

Metaphase

Question 6

This stage of cell division is where chromatin distribution disturbances happen

Answer 6

Anaphase

Question 7

This stage of cell division is where the displaced chromatin are excluded from the nuclei of the daughter cells

Answer 7

Telophase

Question 8

These are chromosome-breaking substances in the bone marrow and spleen

Answer 8

Clastogen

Question 9

This substance, in the bone marrow or spleen, leads to loss of whole chromosome activity

Answer 9

Aneugen

Question 10

Identification (Clastogen /Aneugen)
The pathway of this substance is: Break → Lagging Break → Acentric MN

Answer 10

Clastogen

Question 11

Identication (Clastogen /Aneugen)
The pathway of this substance is: Spindle dysfunction → Lagging chromosome → Centric MN

Answer 11

Aneugen

Question 12

Endpoints of genetic damage

Answer 12

Gene mutation, Clastrogenicity, Aneuploidy

Question 13

Point mutations or deletions/insertions that affect single or blocks of genes. This happens during the replication stage of central dogma

Answer 13

Gene mutation

Question 14

This endpoint results in structural chromosome changes

Answer 14

Clastrogenicity

Question 15

The occurrence of one or more extra or missing chromosomes, leading to unbalanced chromosome complement

Answer 15

Aneuploidy

Question 16

Micronucleus Test is an _________ toxicity study developed by ________ and co-workers in 1975.

Answer 16

In vivo; Schmid

Question 17

Used to screen compounds for genotoxicity caused by clastogens (chromosome-breaking) or aneugens (loss of whole chromosome activity) by detecting micronuclei.

Answer 17

Micronucleus Test

Question 18

Micronucleus Test Principle: When a bone marrow __________ develops into a _________ erythrocyte, the main nucleus is _________; micronuclei that have been formed may remain behind in the otherwise ____________________

Answer 18

Erythroblast; polychromatic; extruded; enucleated cytoplasm

Question 19

Immature erythrocytes: _________; Mature erythrocytes: nucleus disappears

Answer 19

Nucleated

Question 20

T/F: Micronuclei are found in a variety of different marrow cells (myeloblast, myelocytes, erythroblasts, erythrocytes)

Answer 20

True

Question 21

T/F: Majority of micronuclei are found in monochromatic (immature) erythrocytes

Answer 21

False. Majority are found in polychromatic (immature) erythrocytes

Question 22

Identify the Giemsa stain color

_______: immature; Pinkish or orange: mature

Answer 22

Blue

Question 23

Test animals in Micronucleus Test

T/F: male or female rodents may be used

Fill in the blanks
- ______ mice or rats
- Ideally _________ weeks old at the start of treatment
- Weight variation should not exceed +/- _____% of mean weight

Answer 23

True

Swiss; 6-10; 20

Question 24

Micronucleus Test substances

Three dose levels usually ____, ____, ____, of the LD50

Answer 24

1/8; 1/4; 1/2

Question 25

T/F: in micronucleus test substances, solids must be dosed directly or diluted prior to dosing. Liquids must be dissolved in appropriate solvent.

Answer 25

False

Solid – must be dissolved in appropriate solvent
Liquid – may be dosed directly or diluted prior to dosing

Question 26

Substances that produce a detectable increase in micronucleus frequency

Answer 26

Positive control

Question 27

These are positive control substances that are used as aneugens

Answer 27

Colchicine and vinblastine

Question 28

T/F: Colchicine and vinblastine, as aneugens, cause loss of chromosomal activity. They are microtubule synthesis inhibitors that cause metaphase arrest

Answer 28

True

Question 29

These are substances, solvents or vehicles used in administering the test chemical

Answer 29

Negative control (e.g. NSS)

Question 30

T/F: The administration of the test substance is administered IP, IM, PO twice, 48 hours before and 12 hours before the animals are sacrificed)

Answer 30

False. Administered IP, IM, PO twice (30 hours before and 6 hours before the animals are sacrificed)

Question 31

In the preparation of the bone marrow smear, both _______ of freshly sacrificed animal wholly cut through ______ and ______.

Answer 31

femurs; pelvis; tibia

Question 32

In the preparation of the bone marrow smear, insert a 1mL syringe through the cavity of the femur and submerge in the ____________________ contained in a 5mL centrifuge tube

Answer 32

fetal bovine serum

Question 33

T/F: In the preparation of the bone marrow smear, the insides of the femur must appear reddish after aspirating and flushing using the syringe

Answer 33

False. Whitish

Question 34

In the preparation of the bone marrow smear, the suspension must be spread thinly with the aide of the cover slip angled at _____ degrees. Then, it must be air dried for at least ____ hours

Answer 34

45; 24

Question 35

In staining, what is the ratio of the diluted Giemsa stain?

Answer 35

1:6

Question 36

How many polychromatic erythrocytes should be screened for micronucleated polychromatic erythrocytes?

Answer 36

1000

Question 37

T/F: Do not store the multinucleated cells and cells undergoing apoptosis

Answer 37

True

Question 38

Why is Andre Martin E. Marapao so very very very handsome

Answer 38

because he is perfect