Cytogenetic characterization of the yak (Bos Grunniens) and comparison with cattle (Bos taurus)

(1)

ISSN 1594-4077

Vol.8

-

2OO9

Supplement

2

www.aspajournal.

it

ITnLIAN

JOURNAL

OF

ANIMAL

ScrENcE

Journal and Official

Organ

of

the

Scientific

Association

of Animal

Production (ASPA)

THE

ASPA

(b

_ulJ

EdizioniAvenue media'

Milano -Bologna

(2)

Cytogenetic

cha

racterization

of the yak

(Bos

grunnfens)

and

comparison

with

cattle

(Bos

taurus)

Davide

Nicodemo', Alfredo

Pauciullol,

Alberto

Castello2,

Gianfranco

Cosenzal, Luigi Ramunnol,

Giacomo

Ficco3,

liri

Rubesa,

Leopoldo

lannuzzis,

Dino

Di

Berardinol

lDipartimento di scienze

t"J;J.",';;

i?

l-T5i:.?;5:l*?f?§,r"

0"""

Produzioni Animari'

2 _{Museo Nacional de Ciencias}_Naturales,_{Madrid, Spain}

3CRA

_-

_{Centro per}_{la Produzione delle}_carni_e

_il

_{Miglioramento genetico, Monterotondo,}

_Italy

lVeterinary _research

_institute,

_{Brno, Czech Republic}

sConsiglio Nazionale delle Ricerche (CNR), ISPAAM, Napoli,

Italy

Correspond,ing author: Dho Di Berardi:ro. Dipartimento di Scienze del Suolo, della Pianta, dellAmbiente e

delle Produzioni Animali, Università di Napoli "Federico II". Via Università 133, 80055 Portici (NA),

Italy

-Tei. +39 08L2539265

_-Fax:

+39 0877762886 -Email: diberard@unina.it .A.BSTRACT

The domestic yak(Bos grunnlezs) belongs to the fa::ril1'Bondae ard rs one of the most imporbant species for the economl, of the Asiar high iands. Recentll'. the i:rterest for this species iacreased also irr Europeaa coultries, mainly because of its meat arrd nrilk charactenstrcs. Further:rnore,

it

is a species well adapted to

margilal conditions

ald it

could be used to presenre moulta:rr remtones econom5r We carried out a detailed rnvestigation on this species u'ith the fo1lo*-ing

ma:l

eìms:

lrto

perform a cl,togenetic screening of a yak herd recentiy introduced m

ltall.:

36 out of 60 arrimals q'ere aaalr.zed b.v conventional arid GTG-bandhg karyospe. Al1 arrima-ls were 2n=60 and no chromosomal abnormalities r.ere fould. conflrrning that the irr-troduced herd is a good nucleus to start up urth _-vakfarmrng in Ital]'; 2) to deterrnire the genetic stability of the a:rima-Ìs reared under ltalian conditions:frvo drfferent tests \vere used: "Chromatid./cbromosome breaks"

arrd "sister chromatid exchange (SCE)". Out of 400 arra-Ì1'zed ce11s. 3.7512 shorved one or more anomalies; the most represented were chromosome

ald

cbromand breaks. T'he mean number of SCE/cel1s u,as 5.2%. Com-pa:rson

uith

cattle revealed that the trvo species have the same percentage of chromosome anomalies, u'hìle SCE frequencv is lower in

yat

compared !o cattle: 3.r to racrease the cltogenetic knou,iedge about this species and compare Bos taurus arldBos grunmens j:r relation to male steriliq- of F1 hl.bnds; C-, R-,

ald

G-banded karvonpes of yak were prepared arrd compared u-ith the starrdard karyoqpes of cattle. To identify Nucleolar Organizer Regions, sequentiaÌ NOR's,& banded karyotlpes were performed.

Despite the ts,o species share 31,gry hìgh degree of banding homo1og1.. some djflerences can be pohted out, the most remarkable is on the centromeric region of chromosome 15, x-here a strong positive band is present irr

Bos grunniens ufuÌe absent inBos taurus. Molecular data indicate that ìrr ).ak, unlike in cattle, the X

chromo-some has retained a homologous sequence (182 bp) io the Y chromosome. To -',eri§- rf larger blocks olchromatin

are involr.ed. FISH analysis of yak metaphases usiag X and Y cattle paìrltirlg probe v,as perfor:med. The lack of unspecific sigaaÌ ìndicated that no large tlocks of chromatjn are rriterested. Finallii we mapped hvo genes

(SRY sex-determìning regron Y gene arrd ZF1-: zìlc flnger proteur, Y-linked) on the I'ak Y chromosome to veri$, if ttris chromos6rig, 'like rn other species, such as Bos indicus,underwent rearrangement during evolution. Ttre two genes mapped at the same positron compared to cattle, iridicatìng that the sterility of F1 hybrids seems

not to be due to Y chromosomal rearrangements relatively to the these tlvo genes.