and 9L days (table 3). After 122 days, however, DNA content was sli-
ghtly but significantly lower in the samples stored in dry ice than
the samples in liquid nitrogen.

Table 2. Effect of freezing and thawing on the DNA content in bull
spermatozoa during preservation for 3 and 11 days. (Each N=60)

Preserved Glycerol After 3 days After 11 days
condition 1level Feulgen-DNA Difference Feulgen-DNA Difference

mean s.d. from Control mean s.d. from Control

B A ey o B a4 A R Y e e .
Frozen in 7% 8.63 0.3L8 (%) 8.97 0.3411 (%)
dry ice
(Control)

At 5°C after
freezing and B o

thawing none 8.31 0.422 - 3.8 8.49 0.556 - 5.4

At SQC) 363 3*
unfrozen none 8.36 0,337 - 3.1 SR O KoY #2256

3
F ratio 8.80 211,89
%, #* indicate P 0.05 and P 0.0l, respectively.

¥*

7% 8.38 0.L02 - 2.9 8.25 0.596 - 8.1

3

Table 3. Difference of DNA content in bull spermatozoa between samples
stored in dry ice (DI) and liquid nitrogen (LN) for fairly long days.

 

Each N=30
Days Billl Cryogens Survival Feulgen-DNA [Results of variation analysis
name rate of Source of
sperm(%) mean s.d.| variation F ratio
0 13K 60 8.38 0,358
19K ey e
BB 13K ) 1N 55 9.10 0.299 Bull 38.20" "
DT 50 8.88 0.3L42| Cryogen 2.79
19K LN 60 8,60 V0,112 Interaction 3.80
; DI 60 8E62 11510527
ol’* 13K 1N 50 9.61 0.326] Bull 16,08
DI LS 9.62 0.387] Cryogen 0.15
19K LN 55 9.h42 0.196 Interaction 0.28
DI L5 9.37 0,276
122 13K LN 50 10.13 0.322( Bull Ll.295,
DI LO 10.11 0.361] Cryogen 17.56
19K LN Lo 9.96 0.293 Interaction 1.61
DI Lo 9.79 0.313

#% indicate P 0.0l.

DISCUSSION, From the standpoint of cell physiology and genetics, it is
interesting problem to investigate the influence of freezing and thaw-
ing on the DNA molecule in sperm nuclei. The occurence of cell protein
degeneration by freezing and thawing is widely knownm. However, at lea-
st in the DNA content there was demonstrated no difference before and

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