A GYNANDROMORPH OF THE BRINE SHRIMP, ARTEMIA SALINA1
SARANE THOMPSON BOWEN
AND
JEAN HANSON
Depariment of Biology, S a n Francisco State College, San Francisco, California
Received November 20, 1961
S EXUAL mosaics have been reported in three genera of Crustacea. A bilateral
mosaic of Carcinus was found to have a testis on one side and a mixed gonad
on the other (VEILLET1945). Gynandromorphs with a testis and ovary have
been reported in Homarus (see review by CHACEand MOORE1959) and in the
WOOD,
BROWNand INGLE
1939). No intersex
cladoceran, Simocephalus (BANTA,
or mosaic of Artemia has been reported previously.
The method of sex determination in Artemia is of interest because one bisexual
race and many parthenogenetic races have been reported to be polyploid
(BARIGOZZI
1957; BARIGOZZI
and TOSI1959). The cytological studies of Artemia
(reviewed by BARIGOZZI
1957) have not demonstrated the presence of heterochromosomes nor a difference in chromosome number in the two sexes.
Although no studies have been made of sexual differentiation in Artemia,
extensive studies have been made of another crustacean, Orchestia gummarellus.
CHARNIAUX-COTTON
( 1960) has demonstrated that differentiation in this amphipod is mediated by a male hormone produced by an androgenic gland.
Homologous male and female tissues respond in the same manner to the hormone. Therefore, the hormone suppresses the normal differentiation of genetically female tissue.
I n the following morphological descriptions, we have used the terminology of
LOCHHEAD
(1941, 1950) with few exceptions. W e have adopted the term uterus
used by GOLDSCHMIDT
(1952) to designate the organ in which the eggs undergo
segmentation. W e use the terminology of CASSELL(1937) for the male reproductive system.
External sexual dimorphism in Artemia is seen in the larger size and modified
shape of the male antennae. The male has a penis on each side of the body,
whereas the female has one median ovisac.
The male has two separate reproductive systems, one on each side of the
body. Each consists of testis, seminal vesicle, and vas deferens. When the penis
is retracted, the seminal vesicle is folded in a U-shaped loop. During copulation,
the penis is everted, the seminal vesicle is straightened, and the inner surface of
the vas becomes the outer surface of the penis. The female reproductive system
consists of two ovaries, two pouch-like oviducts, and a median uterus which lies
within the ovisac. Attached to the uterus are four clusters of shell glands.
1This investigation was supported by a grant from The National Science Foundation
(G-13219).
Genetics 47: 277-280 March 1962.
278
S.
T.
BOWEN A N D J. H A N S O N
OBSERVATIONS
The gynandromorph was descended by four generations of brother-sister
matings from California amphigonic diploid shrimp which had received 300
roentgens of X-ray irradiation. The young adult had attained a length of 6.7 mm
at the time it was examined under the microscope and photographed. It was then
imbedded in paraffin and sectioned.
Examination of the transparent living animal revealed that the entire right
side of the body was composed of normal male tissue; sperm were seen within
the testis and seminal vesicle. On the left side there was a small antenna
characteristic of the normal female. The ovisac was equivalent to the haIf ovisac
of a female but the distal portion was deflected to the side (Figure 1). Within
the ovisac was one oviduct and two clusters of shell glands connected to the
iiterus. The ovary contained five yolky eggs.
Histological study indicated that the testis and ovary lay in their normal
positions. The half uterus did not join with any portion of the male reproductive
system. Although male and female tissues did not merge, they were in close
proximity in the genital segments. In Figure 2, the seminal vesicle is seen to be
a distance of a few microns from the shell glands.
DISCUSSION
This bilateral gynandromorph suggests that sex determination in Artemia is
chromosomal rather than environmental. The right and left sides of the shrimp
may hare been determined at the first cleavage division. The presence of an
ovary and a testis indicates that the gonads arose from two different germ cells.
FIGURE
1 .-Diagram of the gynandromorph, ventral view.
G Y N A N D R O M O R P H O F ARTEMIA
279
FIGURE
2.-Transvrrsc section passing through thr scaminal wsicle (left) and shell glands
(right). Each gland consists of two large secretory cells; three complete glands and a portion of
a fourth are seen. c. cytoplasm and n, nucleus of shell gland cell; s. spermatazoon i n seminal
vesicle.
A gynandromorph has been accepted by many authors as evidence that the
chromosomes determine the sex characteristics of each cell of the body by autodifferentiation rather than through the action of sex hormones. Such evidence is
not conclusive because the cells on the two sides of the body. being of different
genetic constitution. may respond differently to the same hormone. Furthermore, it is possible that hormones are present which govern cyclical physiological
processes such as egg maturation. The discovery of this gynandromorph does
indicate, however. that if a sex hormone is present in Artemia, it has no action in
suppressing the differentiation of either the gonad or the accessory reproductive
organs of the opposite sex. This is in contrast to the situation in Orchestia which
was outlined above.
SUMMARY
A bilateral sex mosaic of Artemia was found to have a testis containing sperm
on the right side and an ovary containing eggs on the left. If a sex hormone is
present in the brine shrimp, it does not suppress the differentiation of the gonad
or of the accessory reproductive organs of the opposite sex.
280
S. T. BOWEN AND J. HANSON
LITERATURE CITED
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Genetics, and Evolution of Some Chdocera. Carnegie Inst. Wash. Publ. 513.
BARIGOZZI,
C., 1957 Diffkrenciation des genotypes et distribution gkographique d’Artemia salina
Leach: donnkes et problimes. Annke Biol. 33: 241-250.
BARIGOZZI,
C., and M. TOSI,1959 New data on tetraploidy of amphigonic A. salina Leach and
on triploids resulting from crosses between tetraploids and diploids. Convegno di Genetica,
1957. Ricerca Sci. Suppl. 29: 3-6.
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