2008 Savremena poljoprivreda 57 1-2.indd - Poljoprivredni fakultet ...

gene expression has been reported in several multiple lines of transgenic animals including
mouse and pigs (Chen et al., 2002, Van Cott et al., 1997). Our results correspond to
data of earlier studies.
Transgenic females, no.116 and no.117, showed gradual increase of milk production
until day 20th, afterwards it was decreased next 10 days upon the end of experiment (Table
1). No signifi cant differences were obtained between transgenic and non-transgenic females
at the fi rst lactation.
Milk production of transgenic females was comparable with those of non-transgenic
does. Schranner (1993) reported similar results (day 10– 0.18 kg, day 20– 0.21 kg, day
30– 0.17 kg), and this observation is in agreement with previously published reports of other
authors (Dragin et al., 2004).
In milk samples from both lactating transgenic females from F3 generation, Westernblotting
analysis revealed a 21 kDa specifi c band, which corresponds to a light chain of
rhPC.
The concentrations of rhPC produced in the mammary gland of both transgenic females
from F3 generation, determined by ELISA, ranged within 0.109 to 0.351 μg/ml depending
on lactation day (Table 2). No signal was detected in milk of non-transgenic female.
However, the concentration of rhPC in mammary gland of transgenic rabbit females
was low, similarly to F1 and F2 generation (Table 3) of transgenic rabbits (Chrenek et al.
2002). The concentration of recombinant hPC is changing concomitantly with change in
milk yield during lactation, with peak on 20th day of lactation.
Concentration of rhPC in milk among different generations and even among animals
within the same generation was highly variable (for instance, F2 generation 0.030–0.375
μg/ml). This means that transgene expression is individual parameter of each female. It is
possible that such variability is due to different copy number of transgene or localization
of transgene on the chromosome. Otherwise, it may be affected by different milk yield,
eventually different milk composition (content of fat, proteins and other), which can interfere
with proper measurement of rhPC.
Van Cott et al. (2001) using different hPC gene construct, obtained rhPC secretion in
transgenic pig milk, in range of 40 to 1200 μg/ml. He also suggested that pigs with rhPC
expression levels less than 500 μg/ml had no signifi cant differences in milk protein composition
compared to non-transgenic pigs. Same authors concluded that transgenesis and
rhPC secretion in milk was not related to any abnormality of milk production such as mastitis
or other mammary gland disorders.
CONCLUSIONS
In conclusion, present study confi rms stability of hPC transgene transmission and proves
that rhPC can be steadily secreted over multiple generations with no interference on
milk production.
REFERENCES
CHEN C.M., WANG C.H., WU S.C., LIN C.C., LIN S.H., CHENG W. T. K.: Temporal and spatial
expression of biologically active human factor VIII in the milk of transgenic mice driven by mammary-specifi
c bovine alfa-lactalbumin regulation sequences. Transgenic Res. 11, 257–268, 2002.
134