B chromosomes in Apodemus flavicollis
2015
Autori:
Rajičić, MarijaAdnađević, Tanja
Bugarski-Stanojević, Vanja
Stamenković, Gorana
Jojić, Vida
Budinski, Ivana
Jovanović, Vladimir
Blagojević, Jelena
Vujošević, Mladen
Tip dokumenta:
Konferencijski prilog (Objavljena verzija)
,
© 2015 by the Institute of molecular and cellular biology SB RAS
Metapodaci
Prikaz svih podataka o dokumentuApstrakt:
In genus Apodemus, the presence of B chromosome has been confirmed in six out of
twenty-two species. One of them is yellow-necked field mouse Apodemus flavicollis. The
presence of B chromosomes has been confirmed in almost all studied populations of A. flavicollis
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in Serbia in a wide range of frequencies (0,07- 0,63). Five B chromosomes per animal was the
highest number of Bs recorded in our analyzed populations.
These extra chromosomes in A. flavicollis are euchromatic and acrocentric, and by size
and distribution of G- and C-bands can be sorted into the group of five smallest chromosomes in
karyotype.
The absence of Bs accumulation in male meiosis, no significant difference in the mean
number of scars and embryos between females with and without Bs, as well as the absence of
significant difference in the presence of Bs among six age categories, speaks in favor of heterotic
model of their maintenance, contrary to the model of parasitic behavior of these additional
genomic elements.
In general, the number of Bs carriers is higher in environment that is not optimal for this
species which indicates that those individuals have higher fitness. Seasonal variation of Bs
frequencies has been recorded, in such a manner that highest frequencies are present before and
after winter, with stable frequency fluctuations during successive years. Different frequency of Bs
carriers is related to adaptive differentiation to diverse habitats mediated by environmental
variables that directly and/or indirectly influence population dynamics of A. flavicollis. Changes
in frequency follow up increase in population density in circumstances without food and space
competition. Positive correlation between the frequency of Bs carriers and the average number of
sub zero days, as well as with altitude increase, has been recorded.
Considering phenotypic effects, higher level of morphological integration of mandible in
animals with Bs in A. flavicollis has been found. Furthermore, studies of the effects of Bs on
nonmetric cranial traits, as well as on three components of cranial variability confirmed that Bs
does not disturb developmental homeostasis in their carriers. Moreover, Bs play a significant role
in structuring cranial variation.
Negative correlation between the expression of Tgf-β gene and the presence of Bs was also
observed. This could be of great importance for B chromosome which has to pass through
different mitotic and meiotic check points, and Tgf-β gene, through cell cycle regulation,
influences development and homeostasis.
The existence of specific DNA profiles and differential expressions of three genes in the
presence of Bs, testify about interaction of Bs with the rest of the genome. Absence of C-KIT
exon 1 in more than one copy in specimens with 1, 2 and 3B chromosomes excludes the
possibility that this gene is present on Bs. On the other hand, presence of S18 gene copy has been
indicated on some Bs.
Considering the results of population studies, euchromatic structure of Bs and molecular
studies that have been conducted so far, we can say that the contribution of Bs to overall genetic
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diversity in this species is in sight, but there is still need for more specific evidence such as
precise determination of Bs molecular structure, origin and function.
Finansiranje / projekti:
- Genetička i fenetička raznovrsnost u prirodnim populacijama u različitim sredinama - doprinos polimorfizma B hromozoma (RS-MESTD-Basic Research (BR or ON)-173003)
U:
- Abstracts of the International conference “Chromosome 2015”; 2015 Aug 24-28; Novosibirsk, Russia. Institute of molecular and cellular biology SB RAS; 2015. p. 45-7.