R T - F - 4

CYTOGENETICS IN DOMESTIC ANIMAL PRODUCTION

La citogenfetica en la producci<5n pecuaria

C.P. POPESCU *

FRANCE

Human and animal cytogenetics are experimental d isc ip l in e s highly depen­

ding on the development of investigation techniques. The quality of chromosomes

preparations, the mode of s ta in ing and observation of chromosomes have played

an important role in the development of th is type of research.

Since the f i r s t chromosome observations at the end of the la s t century,

the history of cytogenetics can be divided into three periods :

The f i r s t one started at the beginning of th is century and lasted unt i l

nineteen hundred and s ix ty . During th is period, the chromosomes were observed in

h is to log ica l sections made on divid ing t issues. The chromosomes were dammaged by

the microtom and d istr ibuted over several planes. For these reasons, counting

and study of the morphology were extremely d i f f i c u l t and the results were very

often erroneous.

Towards nineteen hundred and s ix ty , several new technical procedures such

as use of in v it ro ce l l cultures, mitogenic products and a hypotonic treatment,

replaced the old h is to log ica l method and improved the quality of chromosomes

preparations. This second period of modern cytogenetics began towards nineteen

hundred and f i f t y nine, by the discovery of the 21 trisomy in man.

Thereafter came a period about ten years during which better knowledge of

the human karyotype was obtained. During th is time, many chromosome abnormali­

t ies were discovered in man, often connected with syndromes or severe malfor­

mations.

* In s t i tu t National de la Recherche Agronomique, Centre National de Recherches

Zootechniques, Laboratoire de Cytogenetique, 78350 JOllY-en-JOSAS (France).

375

The th ird period of cytogenetics began towards nineteen hundred and se­

venty, with the discovery of "banding methods". Before, the accurate iden t i f ica ­

tion of each chromosome pair in human and animal species was the main d i f f i c u l ­

ty. The banding methods resu lting in a d i f fe ren t ia l s ta in ing of each chromosome

pair allowed their precise identif icat ion.

The development of animal cytogenetics including that of domestic animals

followed with some delay that of human cytogenetics.

BANDING METHODS IN DOMESTIC ANIMALS.

The main domestic species except the p ig , possess a very high number of

chromosomes with s im ilar morphology. In some species such as cattle and goat,

the chromosomes stained by c la s s ica l methods, could not be c la s s i f ie d and there

was a considerable risk for confusion between two or several pairs. At the pre­

sent time, the banding techniques give a reproductible longitudinal differen­

t ia t ion of the chromosomes for each animal species and an international conven­

tion has been established for recognition and c la s s i f ic a t io n of karyotype in

domestic species (FORD and a l . , 1980). In a recent'review, GUSTAVSSON (1980)

described a l l these methods used in domestic animal cytogenetics.

I t would be advisable that a l l s c ien t is t s working on domestic animals

cytogenetics use th is c la s s i f ic a t io n for the description of chromosomal abnor­

malities. This would allow a periodic establishment of an inventory of abnorma­

l i t i e s for each species and thus lead to a better knowledge of the ir effects

upon karyotype and animal production performances.

INVENTORY OF CHROMOSOME ABNORMALITIES IN DOMESTIC SPECIES.

The discovery in 1964 of the 1/29 translocation in cattle by GUSTAVSSON

and ROCKBORN, drew the attention of cytogenetists upon the chromosome abnorma­

l i t i e s and their consequences in animal breeding. Cytogenetics studies on large

number of animals were started in different European and American countries.

They resulted in the description of new chromosomal abnormalities and the f i r s t

estimation of the frequency of some of them such as, for example, the 1/29

translocation and leucocyte chimerism in cattle. Cytogenetics laboratories

studing the domestic species were created in most European and American coun­

t r ie s ; at present their number ranges around th irty .

376

- 4 .

Tntife ). Fnequeucij of U 29 tnani location and eh miotic condition in c attic population & t tidied in the Labotatolij of

CytogeneticA, National Institute of Agnicultutal Re i catch

Breed Animalsstudied

Heterozygotes for 1/29 translocatior *

Homozygotes for 1/29 translocation X Chir.ierics %

Abondance 11 0 0 0 -

Armori caine 10 0 0 1 -

Blonde d'Aqui- taine 46 6 13,04 0 0 -

3rune des Alpes 7 0 0 0 -Charolais 359 11 3,06 1 0,28 3 0,84F.F.P.N. 798 0 0 9 1,13Holstein 399 0 0 8 2,00Hereford 16 0 0 0 -Limousine 133 10 7,52 0 2 1,50Mai ne-Anj ou 70 0 0 0Montbeliard 365 8 2,19 0 7 1,92Normand 312 0 0 1 0,32Pie Rouge 34 0 0 0 —Piemontaise 7 0 0 0 -Tarentaise 10 0 0 0 -Vosgienne 81 1 1,23 0 0 -Sinimenthal 1 1 - 0 0 -Baladi 12 0 0 0 -Baoule 85 3 3,53 0 0 —

N'Damas 26 0 0 0 -Zebu et croisSs 51 3 5,89 0 0 -

TOTAL 2 833 43 1 31

However, the most frequent chromosomal abnormalities involved in reproduc­

tive disorders and embryonic death in pigs are the reciprocal translocations.

Ten different types of reciprocal translocations have been described up t i l l now,

despite a very small number of pigs studied (Table 3). They reduce the p r o l i f i ­

cacy by 25 to 50 % and in some cases they cause tota l s t e r i l i t y .

Another domestic species in which chromosomal abnormalities seem to be

very frequents is the sheep. Thus 8RUERE and a l. (1976) in New Zealand have

studied a large number of animals and found three types o f Robertsonian trans­

locations. In Germany, GLAHN and WASSMUTH (1980) observed a reciprocal trans lo ­

cation and a autosomal deletion. (LUFT, 1973).

In the horse only few studies have been made on large populations. The

most common abnormalities whose frequency seems to be much higher than in other

species i s X monosomy. A systematic survey in-horses was started in our labo­

ratory in 1979, and about 300 animals have been examinated at present. Several

cases of X monosomy have been.discovered (METENIER and CRIBIU, 1980 ; CRIBIU,

unpublished).

A review of abnormalities described in th is species was published in 1978

by DE GIOVANNI and CRIBIU.

In the other species of domestic Mammals, only few animals have been stu­

died and the abnormalities described concern iso la ted individuals^ -So that the

frequency of abnormalities cannot be estimated.

CYTOGENETIC STUDIES OF DOMESTIC ANIMAL EM8RY0S.

Owing to the improvement of ce ll culture technics and cytogenetics methods

the last few years, study of human and animal chromosomes in very young embryos

i s now possible. In man th is type of investigation i s used for prenatal diag­

nosis of chromosomes abnormalities by amniocentesis.

In domestic animal and in part icu lar in catt le , studies of embryos chromo­

somes have much progressed because of the development of embryo transfer the

last ten years. They allowed to choose the sex of the future calf and they also

present the effects of free-martinism. The f i r s t studies were made on 13-14

380

day-old embryos (HARE and a l . , 1978 ; WINTENBERGER-TORRES and POPESCU, 1980).

At present 6 to 7 day-old embryos are used leading to a higher succes of free­

zing and transfer (SINGH and HARE, 1981). Embryonic ce ll culture techniques have

been improved (POPESCU and a l . , 1982) and embryonic ce ll sampling are now perfor­

med by micromanipulation.

This method can also be used to study the effects on f e r t i l i t y of some ab­

normalities. Indeed, i t i s possible to observe in the embryos the various unba­

lanced karyotypes, caused by the gametes coming from meiosis of heterozygotes for

structural abnormalit ies. In catt le , studies at seven (KING et a l . , 1981) and

forteen day-old embryos (POPESCU, 1980) s ired by a carr ier of the 1/29 trans loca-

t io n (has evidenced the presence of unbalanced karyotvoes.

In the p ig , in three cases of reciprocal trans locat ions, several types of

unbalanced karyotypes have been found in preinpl-antation embryos. This chromoso-

mally abnormal embryos die before birth (POPESCU, 1982).

CYTOGENETICS AND ANIMAL BREEDING.

Cytogenetics of domestic animals is becoming a more independent d isc ip l in e . The

very important theoretical interest of chromosome studies for the understanding

of the chromosomal evolution and i t s role in animal speciation, but a lso i t s im­

mediate p rac t ica l application fu l ly ju s t i f ie s the recent development of th is

f ie ld.

Population of domestic animals are very d ifferent from wild animal popula­

tions. The interest of farmers and the a r t i f i c i a l selection pressures are va r ia ­

ble according to the time elapsed after the domestication and the geographical

position. In that reason, i t is very d i f f i c u l t to estab lish wheter a given chro­

mosome abnormality constitutes a polymorphic system and to detect a possib le se­

lective advantage. Conversely, i t has been proved that some abnormalities in

cattle and pig cause unbalanced gametes, leading to lethal embryos and subse­

quently to a reduction of male and female p ro l i f icacy and to large economic lo s ­

ses.

In a modern animal production, where a r t i f i c i a l insemination becomes gene­

ralized, the r isks of a large spreading of chromosomal aberrations are increa-

381

s i n g . I n a d d i t i o n , the t r a n s f e r o f animal p o p u l a t i o n s , ve ry common at p r e s e n t ,

w ithou t c y t o g e n e t ic s s u r v e y , in c re a se the p o s s i b i l i t i e s o f chromosomal abnor­

m a l i t i e s d i s s e m in a t i o n in c o u n t r ie s c o n s t i t u t i n g new an imal p o p u la t i o n s .

Because o f t h e se n e g a t iv e consequences o f chromosomal a b n o rm a l i t ie s on

rep ro d u c t ion , d e te rm ina t ion of the karyotype o f la r g e an imal p o p u la t i o n s from

each dom est ic animal s p e c ie s i s ve ry im portant.

However, the s tu d y o f chromosomes i n dom est ic s p e c i e s , may a l s o lead to

d i s c o v e ry o f d i f f e r e n t chromosomal v a r i a n t s . They may be i n t e r e s t i n g i n s e l e c ­

t i o n as g e n e t ic markers o r i n p h y l e t i c and p h y lo g e n e t i c i n v e s t i g a t i o n s .

Some deeper m o d i f i c a t i o n s o f chromosome complements, such as t r i s o m ie s

o r d u p l i c a t i o n s , t o l e r a t e d by the l i v i n g o rg a n i sm s , might^Ce have a p o s i t i f

e f f e c t i n animal b re e d in g o f tomorrow.

SUMMARY

The development o f domestic animal c y t o g e n e t i c s , f o l lo w e d tha t o f human

c y to g e n e t ic s . The l a s t few y e a r s c y to g e n e t ic s t u d i e s have been made on la rge

number o f an im a l, e s p e c i a l l y i n c a t t l e . They r e s u l t e d i n the d i s c o v e r y o f a

r e l a t i v e l y la rg e number of chromosomal a b n o rm a l i t ie s in main dom est ic animal

s p e c ie s . Some o f them have a n e g a t i f e f f e c t s o n - f e r t i l i t y . I n connect ion w ith

embryo t r a n s f e r the c y to ge n e t ic s o f c a t t l e embryos have been improved. These

s t u d i e s can a l s o be used to stusly t h e ' e f f e c t s on f e r t i l i t y o f some chromosomal

a b n o rm a l i t ie s . Because o f a l l these a p p l i c a t i o n the c y t o g e n e t ic s s tudy o f do­

m est ic animal becomes a b so lu t e ly ne ce s sa ry i n a modern animal b reed ing .

RESUME

La c y togene t iq ue des especes domestiques a s u i v i le developpement de la

c y togenet iq ue humaine. Ces d e m ie r e s annees des e tudes ont e te e n t r e p r i s e s s u r

des g randes p o p u la t i o n s animates notamment chez le s b o v in s . Ceci a perm is la

decouverte de nombreuses anomal ies chromosomiques dont c e r t a in e s ont un e f f e t

n e g a t i f s u r la f e r t i l i t y . Les etudes s u r I 'em b ryon b o v in ont egalement p r o g re s s e

ces d e r n ie r s temps en l i a i s o n avec le s t ra vaux de. t r a n s p l a n t a t i o n d 'em bryons.

E l i e s ont egalement perm is chez la b o v in s , mais a u s s i chez le p o r e , d 'e t u d i e r

s u r I 'em bryon meme( le s e f f e t s de c e r t a in e s anom al ie s chromosomiques. En r a i s o n

des consequences n e g a t i v e s des anomal ies chromosomiques s u r la f e r t i l i t e des

animaux domestiques et du r i sq u e de d i s s e m in a t i o n p a r l 1 in s e m in a t i o n a r t i f i c i e l l e

I ' e t u d e c y togene t iq ue dev ient i n d i sp e n sa b le dans une zoo te ch n ie moderne.

382

REFERENCES

BRUERE A.N., CHAPMAN H.!"., JAINE P.M. a l . , 1976 : Origin and s ign if icance of centric fusions in domestic sheep.J.Hered. 67(3) 149-154

DE GIOVANNI A., CRIBIU E.P., 1978 : Le anomalie chromosomiche nel cavallo "Equus cabal Lus" L .Zootech.Nutr.Anim. 4, 9-16

FECHHEIMER N.S., 1979 : Cytogenetics in Animal production.J.of Dairy Science 62, 844-853

FORD C.E., POLLOCK D.L., GUSTAVSSON I . , 1980 : Proceedings of the F irs t Interna­t iona l Conference of the standardisation of banded karyotypes of domestic animals. Treading 1976.Hereditas 92(1) 145-162

GLAHN-LUFT B ., WASSHUTH R ., 1980 : The influence of the 1/20 translocation in sheep on the effic iency of reproduction.31st animal meet.of European association -for animal production. Commission on sheep and goat production.

GUSTAVSSON I . , R0CK80RN G., 1964. : Chromosome abnormality in three cases of lym­phatic leukaemia in cattle.Nature, 203, 990.

GUSTAVSSON I . , 1969 : Cytogenetics, d i s t r ib u t io n and phenotypic e ffects o f a t ran s lo ca t ion in Swedish cattle.Hereditas 63, 68-169.

GUSTAVSSON I . , 1979 : D istribution and effects of the 1/29 robertsonian trans­location in cattle.J. Dairy Sc. 62, 825-835

GUSTAVSSON I . , 1980 : Banding techniques in chromosome ana ly s i s of domestic ani­mals.Adv. Vet . S c i . Comp.Med. 24, 245-290

HERZOG A., H0HN H., 1971 : Autosomale Trisomie bei der letalen Brachygnathie des Rindes.Cytogenetics 10(5) 347-355

HARE W.C.D., SINGH E.L. , BETTERIDGE K.J., EAGLES0ME M.D. and RANDALL G.C.B., 1978 Embryo sexing with particular reference to cattle.Curr. Top. Vet. Med. 1_, 441-449.

KING W.A., LINARES T., GUSTAVSSON I . , BANE A., 1980 : Presumptive translocationtype trisomy in embryos sired by bu lls heterozygous for the 1/29 trans lo ­cation.Hereditas 92(1) 167-169

./..

383

LUFT B ., 1973 : Eine autosomale Deletion mit Auftreten von Fragmenten bei einem Schafbock.Zuchthygiene j5(3), 125-129

METENIER L . , DRIANCOURT M.A., CRIBIU E.P., 1979 : An XO chromosome constitution in a s te r i le Mare (Equus cabal lu s ) .Ann.Genet.S e l . anim., V\_, 161-163

METENIER L . , CRIBIU E.P., 1980 : F irst report on chromosomal examination of race horses in France.4th Eur.Colloq.Cytogenet.Domest.Anim. 1980 : 390-393

MORAES F.J.C., 1978 : Estudos cromossomi cos eni d ifferentes racas do rebanho bovino de Rio Grande do Sul.Porto Aegre.Dissertacao. Universidade Federal de Rio Grande do Sul.

POPESCU C.P., 1977 : Les anomalies chromosomiques des bovins (Bos taurus L.) : Etat actuel des connaissances.Ann.Genet.Sel. anim. , 9K4) 463-470

POPESCU C.P., 1980 : Cytogenetics study on embryos s ired by a bu ll carrier of 1/29 translocation.4th Eur.Colloq.Cytogenet. Domest. Anim., 1980 : 182-186

POPESCU C.P., B0SCHER Jeaninne, CRIBIU E.P., 1982 : Collagen substrates for cyto­genetic studies of domestfc animal embryos.J.of Heredity (in press)

POPESCU C.P., 1982 : Reciprocal translocations in pigs and consequences on their performances.P ig News and Information (in press).

SINGH E.L., HARE W.C.D., 1980 : The fe a s ib i l i t y of sexing bovine morula stage embryos pr ior to embryo transfer.Theriogenology J[4(6) 421-428

WINTENBERGER-TORRES S.„ POPESCU C.P., 1980 : Transfer of cow b lastocysts after sexing.Theriogenology _1_4(5) 309-318

o _ o _ o _o , o _ o _ o _ o _ o

384