Micronucleus

Question 1

MICRONUCLEUS/MICRONUCLEI is also known as

Answer 1

Howell-Jolly bodies

Question 2

Micronucleus/micronuclei or Howell-Jolly bodies is a _______________ that is ___________ from the main nucleus and
has originated from a chromosome or fragment of a
chromosome that ___________ to be included into one of the daughter
nuclei during cell division

Answer 2

DNA fragment; separated; fail

Question 3

micronucleus/micronuclei or Howell-Jolly bodies: Chromosomal breakage or spindle damage during
___________/____________

Answer 3

metaphase/anaphase

Question 4

T/F: If the cell is exposed to a genotoxic agent, there is spindle damage and can result in formation of
micronucleus

Answer 4

True

Question 5

Micronucleus is viewed through a microscope by the

Answer 5

OIO (oil immersion objective)

Question 6

Extranuclear biomarker of chromosomal damage

Answer 6

micronucleus/micronuclei or Howell-Jolly bodies

Question 7

Typically round with as diameter of about 1/20 to 1/5 of the
erythrocytes.

Answer 7

micronucleus/micronuclei or Howell-Jolly bodies

Question 8

Some are almost almond-shaped.

Answer 8

micronucleus/micronuclei or Howell-Jolly bodies

Question 9

T/F: Micronucleus can also be caused by ionizing radiation, a physical
mutagen

Answer 9

True

Question 10

double strand breakage or by DNA damage

Answer 10

Clastogens

Question 11

Accentric chromosome fragments are formed which
initiates formation of micronucleus

Answer 11

Clastogens

Question 12

damage to spindle

Answer 12

Aneugens

Question 13

Whole chromosome is affected as a result of spindle
damage, which normally pulls chromosomes from the
center part of the cell during mitosis

Answer 13

Aneugens

Question 14

T/F: Both (Aneugens and Clastogens) will result in the formation of micronucleus

Answer 14

True

Question 15

T/F: A single micronucleus can result in proliferation, unless
the cell undergoes apoptosis

Answer 15

True

Question 16

Point mutations or deletions/insertions that affect single
or blocks of genes

Answer 16

Gene mutation

Question 17

Structural chromosome changes

Answer 17

Clastrogenicity

Question 18

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

Answer 18

Aneuploidy

Question 19

Micronucleus test is in vivo or in vitro?

Answer 19

In vivo

Question 20

In vivo toxicity study developed by Schmid and coworkers in
1975.

Answer 20

Micronucleus test

Question 21

Micronucleus test is used to screen compounds for genotoxicity caused by
________ (chromosome-breaking) or ___________ (loss of
whole chromosome activity) by detecting micronuclei.

Answer 21

clastogens; aneugens

Question 22

Micronucleus test is used to check if the chemical can cause DNA damage,
specifically at _

Answer 22

chromosomal level

Question 23

Agents used are genotoxic or mutagenic that cause DNA
damage

Answer 23

Micronucleus test

Question 24

Alklyating agents used for cancer treatment such as __________ and __________ — affecting DNA mutations of
cancer cells and can also affect DNA of normal cells

Answer 24

vincristine and vinblastine

Question 25

**Micronucleus test: ** Genetic material replicates and divides ________ between two daughter cells

Answer 25

equally

Question 26

Principle of Micronucleus test: When a bone marrow erythroblast develops into a polychromatic erythrocyte, the main nucleus is ______________; micronuclei that have been formed may remain behind in the otherwise _____________ cytoplasm

Answer 26

extruded; enucleated

Question 27

Micronuclei are found in a variety of different marrow cells such as

Answer 27

myeloblast, myelocytes, erythroblasts, erythrocytes

Question 28

Majority of micronuclei are found in

Answer 28

polychromatic (immature) erythrocytes

Question 29

Giemsa stain color for immature

Answer 29

Blue

Question 30

Giemsa stain color for mature

Answer 30

Pinkish or orange

Question 31

Test animals for micronucleus test

Answer 31

male or female rodents (Swiss mice or rats)

Question 32

T/F: Male and female rodents exhibit the same mechanism of blood production within the bone marrow as humans.

Answer 32

True

Question 33

Test animals are supposed to be at __________ weeks old at the start of treatment

Answer 33

6-10 weeks old

Question 34

Weight variation of test animls

Answer 34

should not exceed ± 20% of mean weight

Question 35

Three dose levels

Answer 35

1/8, 1/4, 1/2 of the LD50

Question 36

T/F: solids must be dissolved in appropriate solvent first

Answer 36

True

Question 37

Solvents used

Answer 37

water, NSS, dimethylsulfoxide (DMSO)

Question 38

T/F: Liquids may be dosed directly or diluted prior to dosing

Answer 38

True

Question 39

Substances that produce a detectable increase in micronucleus frequency

Answer 39

Positive Control

Question 40

Mitomycin-C (anticancer/antineoplastic)

Answer 40

Positive control

Question 41

dimethylnitrosamine (alkylating agents),

Answer 41

Positive control

Question 42

cyclophosphamide

Answer 42

Positive control

Question 43

triethylenemelamine

Answer 43

Positive control

Question 44

ethylmethanesulfonate

Answer 44

Positive control

Question 45

Solvent or vehicle used in administering the test chemical

Answer 45

Negative control

Question 46

Ethyl methansulphonate

Answer 46

Negative control

Question 47

Methyl methanesulphonate

Answer 47

Negative control

Question 48

Ethyl nitrosourea

Answer 48

Negative control

Question 49

Mitomycin

Answer 49

Negative control

Question 50

Cyclophosphamide

Answer 50

Negative control

Question 51

Triethylenemelamine

Answer 51

Negative control

Question 52

Colchicine

Answer 52

Negative control

Question 53

Route of administration and frequency

Answer 53

Administered IP, IM, PO twice

Question 54

Drugs mus be given ________ hours before and _________ hours before the animals are sacrificed

Answer 54

30 hours, 6 hours

Question 55

_____ and _______ have faster exposure

Answer 55

IP and IM