αS1-CnD, another allele associated with a decreased synthesis rate at the caprine αS1-casein locus

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αS1-CnD, another allele associated with a decreased

synthesis rate at the caprine αS1-casein locus

M.F. Mahé, F. Grosclaude

To cite this version:

Note

α

S1

-Cn

D

,

another allele associated with

a

decreased

synthesis

rate at

the

_{caprine α}

_S1

_-casein

locus

M.F. Mahé

F.

Grosclaude

Institut National de la Recherche

_Agronomique,

Laboratoire de

_{Génétique Biochimique.}

Centre de

Jouy-en-Josas,

78350

_{Jouy-en-Josas,}

France

(received

20

_September

_1988,

_accepted

15 November

₁₉₈₈₎

Summary —

A seventh allele of the

_{caprine a}

_s

_,--asein

locus, called

_!X

_S1-Cn

_D

_,

was observed in

French

_Alpine

and Saanen breeds. Its

_frequency

in a

_large

herd _{(AM 98)} was 0.025. Like

_!X

_S1-Cn

_B

_-,

!X

S1-Cn

F

and

_!X

_S1-Cn

_o

_,

this allele is associated with a decreased

_synthesis

rate, its

_approximate

mean contribution

_being

0.6 - 0.8

_g/I,

very close to that of

_!X

_S1-Cn

_F

_.

goat -

<X

s1

-caseln - polymorphism - quantitative

variations

Résumé &mdash;

_<X

_s1

_-Cn

_D

_,

un autre allèle à taux de

_synthèse

réduit au locus de la caséine

o

si

-caprine.

Un

_septième

allèle du locus de la caséine

_a

_S1

_-caprine,

_as!!no,

a été observé dans les races

Alpine

et Saanen

_françaises.

Sa

_fréquence

dans un

_{grand troupeau ( N=198)}

était de

0,025. Comme

_a

_S1

_-Cn

_B

_-,

_a

_S1

_-

_C

_n

_F

et

_a

_,

_a

_-Cn

_S1

cet allèle est associé à un taux de

synthèse

réduit, sa contribution _{moyenne étant} d’environ 0,6 à _0,8

_g4,

donc très

proche

de celle

_{d as!!nF.}

chèvre - caséine as, -

polymorphisme -

variations

quantitatives

Introduction

Grosclaude et al.

₍₁₉₈₇₎

have

_recently

concluded that the

_polymorphism

of

_goat

cx

s1

-casein

is under the control of a minimum of 6 alleles. Alleles

_c

_x

_S1-Cn

_A

_,

_c

_x

_S1-Cn

_B

and

c

x

S1-Cn

c

were found to be associated with a

_{high c}

_x

_s1-casein

content

_(approximate

mean

contribution of each allele

_being

3.6

_{g/1) compared}

to

_c

_x

_S1-Cn

_F

and

_a

_si

_-Cn"

which are

associated

_respectively

with a low content

_{(0.6 g/1)}

and an intermediate content

(1.6

g/I),

while

_c

_x

_S1-Cn

_o

_appeared

to be a true null allele.

In the same

_publication,

_{the authors mentioned the presence in the}

_{electrophoregrams}

of some

_milks,

of an additional

band,

called x, which

reacted

in

immunoblotting

with

anti-a

s1

-casein

antibodies. We show in the

_present

note that this band

_corresponds

in

Material and Methods

Individual milk

_samples

were obtained from the &dquo;Station de

_{Testage Caprin&dquo;}

near

Mois-sac, Sainte-Croix Vall6e

_Frangaise,

France or from

_private

farms located in west central France. All

_techniques

were as described in Grosclaude etal.

(1987).

Results and Discussion

Band x

_(Fig.

2 in Grosclaude et

al.,

1987),

hereafter called

D,

migrates slightly

more

slowly

than

_{(3-casein (Fig.}

₁₎

in

_{SDS-polyacrylamide gel.}

Because of unavoidable varia-tions in the

_{electrophoretic}

conditions,

this band may be masked

by

the

_(i-casein

_band,

but,

in all cases, its presence can be ascertained

_{by immunoblotting.}

In order to establish the

_genetic

determinism of fraction

D,

our

_family

data were

screened for the presence of sires

transmitting

this fraction to their

_daughters.

One such

sire,

numbered

A316,

was

_found,

with a total of 16

_{dam-daughter pairs.}

_{In the progeny of}

this

_sire,

fraction D

_appeared

to be controlled

_by

an allele of the locus

_a

_si

_-Cn

because it

was transmitted in atternance with variant

F,

the

_proportion

of the 2 classes of

_daughters

not

_{being significantly}

different from the 1: 1 ratio

(Table

I).

In

_addition,

12 dams

possessed

fraction

D,

together

with either variant F

_{(9 cases)}

or

variant B-

_{(3 cases). Except}

in one

_dam-daughter

_{pair, suspected}

to be a case of

from sires which did not transmit fraction

D,

8 did and 12 did not receive

_D,

a

_proportion

which

_again

was not

_{significantly}

different from the 1: 1 ratio.

Grosclaude et al.

_{(1987) reported}

_that,

_curiously,

fraction x

_{(here D),}

_present

in the

milk of certain

dams,

was not transmitted to their

_daughters,

an observation at variance with the conclusions of the

_present

note. Re-examination of the

_{surviving dam-daughter}

pairs

among the 7 considered

by

these authors

suggests

the

_probable

occurrence of 2

parentage

errors in this

_sample.

The non-transmission of fraction D in the 5

_remaining

pairs

is attributable to mere chance

_(P=

_0.03).

Allele

_a

_S1

_-Cn

_D

is the seventh allele identified at the

_goat

_as!!asein

locus. Its

frequency

in the

_{large Alpine}

herd of Moissac

_(N

=

198)

was 0.025. It was also observed

in the Saanen breed. Grosclaude et al.

₍₁₉₈₇₎

estimated that the

_frequencies

of

_a

_s

_,-Cn

_O

were 0.05 in

_Alpine

and 0.03 in Saanen. Because in their data

_a

_S1

_-Cn

_D

was not

distin-guished

from

_a

_s

_,-Cn

_O

_,

these values in fact

_apply

to the combined

_frequencies

of

a

S1

-Cn

o

and

_a

_S1

_-Cn

_D

_.

The

_frequencies

of each of these 2 alleles are thus rather low in

both breeds.

On

_immunoblots,

as well as on

_{SDS-polyacrylamide gels,}

variant

a

s

,-CnD

_appears

much weaker than variants

_a

_S1

_-CnA,

B or C. Quantification of this variant

by

rocket-immunoelectrophoresis,

carried out on individual milk

_samples

from four animals with the

genotype

as!-Cn!iF,

indicated that the

_approximate

mean contribution of allele

_a

_s

_,-Cn

_D

was = 0.6 - 0.8

_g/I,

a low

_value,

close to that found for

_F

_a

_-Cn

_S1

(0.6

g/I).

Allele

_a

_si

_-Cn

_D

is thus the fourth out of a total of 7 alleles associated with a decreased

_synthesis

rate at

the

_goat

_ag

_i

_-casein

locus. The biochemical

_{particularities}

of variant

_a

_S1

_-CnD

are under

Acknowledgments

We thank J. Bouillon, A.

_Maingot,

A. _Piacere, G. Ricordeau and J.-P.

_Sigwald

for their constant and valuable

_help

and N. Mazure for her skillful assistance.

Reference

Grosclaude _F., Mah6 M.-F.,

Brignon

G., Di Stasio L. & Jeunet R. ₍₁₉₈₇₎ A Mendelian

_polymorphism