1977. Analisis Genetico de Alguno Nuevos Colores Mutantes en El Goldfish. Universidad de Nagoya,...

8/6/2019 1977. Analisis Genetico de Alguno Nuevos Colores Mutantes en El Goldfish. Universidad de Nagoya, Japon.

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GENETIC AND DEVELOPMENTAL ANALYSIS OF SOME NEWCOLOR MUTANTS IN THE GOLDFISH, CARASSZUS AURATUS

TAKA0 KAJISHIMABiological Institute, Faculty of Science, Nagoya University,

Nagoya 464, JapanManuscript received August 31 , 1976Revised copy received January 4,1977

ABSTRACTThe genotypes of three color mutants in goldfish: a depigmentation char-

acter of larval melanophores, albinism and a recessive-transparent character,were analyzed by crossing experiments. The depigmentation character in thecommon goldfish is controlled by two dominant multiple genes, Dp, and Dpd,and only fish with double recessive alleles dp,dp, dp,dp, can retain larvalmelanophores throughout life. Albinism is also controlled by double autosomalgenes, p and c. The genotype of an albino fish is represented by p p cc; thenon-albino fish is PP CC . Fish with either a p p CC or p p C c genotype arealbino when scored at the time of melanosome differentiation i n the pigmentretina, but after the time of skin melanophore differentiation, they change tothe nonalbino type under the control of the C gene. The recessive-transparentcharacter is controlled by a single autosomal gene, g. The mechanisms of geneexpression of these characters were proposed as a result of observation and/orexperimental data on the differentiation processes of their phenotypes, and thegenotypes of these color mutant goldfish were considered in relation to the"gene duplication hypothesis in the Cyprinidae."

HE goldfish is one o l the most popular animals used as an experimentalsubject in many laboratories. Although it has many varieties of color and

form, only a few genetic analyses of these characters have been carried out. Oneof the reasons or this is that a great deal of time and space is required to raise asufficient number of offspring. Furthermore, as has been pointed out, manycharacters of the goldfish are controlled by multiple factors, so that it is difficultto get invariablc and regular ratios that fit Mendelian expectations (CHEN 1934).

The first report on the genetics of the goldfish was that of HANCE1924), whoreported the recessiveness of the telescope-eye to the normal-eye, although noexperimental data were shown. The first well-founded case of a Mendeliancharacter in the goldfish was reported by BERNDT 1925) and CHEN (1925,1928) on the transparency and mottling character of the scales. A few yearslater, MATSUI1934) reported his detailed results on the genetic analysis of thegoldfish varieties involving scale-transparency and telescopeeye. In the sameyear, CHEN (1934) reported on the inheritance of blue and brown coloration inthe goldfish, and concluded that there are four pairs of independent factors con-trolling the production of these characters, and only when all of these pairs werein the homozygous recessive condition was the brown coloration produced.Genetics 86: 161-174 May, 1977


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162 T. KAJISHIMAWhen rearcd at 21 C, the common goldfish begins to differentiate the melano-

somes in its retinal pigment cells about 36 hours after spawning (Stage-21,developmental stage from KAJISHIMA1960d), and more than 14 hours laterthree kinds of skin chromatophores begin to differentiate successively; at firstthe melanophores (50 !iours after spawning, St-22), hen iridophores (80 hoursafter spawning, St-24) and finally xanthophores (50 hours after hatching, 150hours after spawning, St-26). Then the fry usually have black eyes and blackish-brown coloration. However, as is well known, the larval melanophores of thecommon goldfish begin to depigment about two to three months after hatching,and within a month the fish becomes xanthic to deep orange in coloration. Onthe other hmd, the black moor (black telescope-eyed goldfish) usually retainsits melanophores throughout life. In the present paper, the depigmentation andnondepignien tation character of larval melanophores is analysed first.

Albinism is a common mutation, which has been reported in many animals,including the fish. In the goldfish, however, it was not reported until 1956 in anAmerican hobbyists magazine, The Aquarium. According to the report, albinogoldfish were offspring of an albino fish found in Singapore, but unfortunatelyall of the fish died without any genetic investigations. In 1967,YAMAMOTOndhis colleague, TOMITA,ound albino goldfish in Favors Aquarium in New York,and the following year they brought the live fish back to our laboratory. Thesefish did not seem to be related to the 1956 strain, because the eye character of the1956 fish secmed to be genetically dominant (normal-eye) in type, whereas thepresent animals are all homozygous recessive (telescope-eye) in type.

The original fish and their progeny lack melanosomes not only in the skin,but also in the retinal pigment cells from the earliest developmental stage; theyare orange in color and have pink eyes. The results of genetic analyses of albinogoldfish that were carried out by crossing albinos with various geneticallydefined, color-mutant fish are described, and the processes of the phenotypicexpression of the albino genes, including the mechanisms of their functions, arediscussed.

From 1957 to 1960 we were engaged in experiments to clarify the mechanismsof gene function of the dominant transparent-scaled character T (KAJISHIMA1960a,b,c; MATSUMOTO,AJISHIMA nd HAMA960). During that time, a newrecessive transparent mntant was discovered. The results of the gene analysis ofthis mutant are also reported here.

Recently, OHNO and his co-workers have proposed the hypothesis that someof the teleosts of the family Cyprinidae duplicated their chromosome numbersduring the evolutionary process, and the genomes of these fish are tetraploid andnot diploid (OHNO 1970). The data obtained from the genetic analyses of colormutants in the goldfish will be considered in relation to this hypothesis.

MATERIALS AND METHODSThe fish used in these experiments were of the following varieties:The common goldfish, wakin:The wakin acquires its mature coloration following destruc-

tion of the larval melanophores. The fish used in these experiments were inbred more than ten


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COLOR MUTANTS I N GOLDFISH 163generations by brother-sister matings in our laboratory, and all of the offspring had depigmentedmelanophores within a year.

T h e red telescope-eyed goldfish: The red telescope fish also loses its skin melanophores duringits life, but the time of depigmentation varies extensively, usually occurring at an age of morethan two years. Until that time, it cannot be distinguished from the black moor. However, afterdepigmentation it has a deep orange coloration and usually does not develop melanophoresagain. The fish used in these experiments were progenies which were inbred more than fivegenerations.

The black telescope-eyed goldfish, black moor: The black moor usually does not showdepigmentation of its melanophores throughout its entire life and produces more of them duringdevelopment. The fish used in these expeiiments were also inbred in our laboratory more thanten generations and during tha t period none of the individuals lost their melanophores.T h e transparent-scaled goldfish: The adult homozygous transparent-scaled goldfish is pinkishin coloration and has no pigment except in the retinal pigment cells. At the time of hatching,however, it has the same three kinds of chromatophores as the common goldfish, i .e., melano-phores, iridophores and xanthophores. But when the fry reaches six to seven mm in length(St-27+), about ten days after hatching, all three kinds of chromatophores begin to depigmentand within a month they acquire the final coloration.

The transparent-scaled character ( T T ) is incompletely dominant to the normal-scaled char-acter ( I t ) ,and heterozygous F, fish show a characteristic calico pattern (CHEN 928; MATSUI1934) following partial depigmentation of the three kinds of chromatophores. The F, offspringsegregate into the homozygous transparent type, heterozygous transparent type (calico) andnormal type in the ratio of 1:2:1. The homozygous fish used in these experiments were alsoinbred more than ten generations.The albino goldfish: The albino goldfish used in these experiments were the inbred off-spring of the albino goldfish discovered in Favors Aquarium. Albino goldfish have no mel-anosomes in the skin o r the retinal pigment cells, and they have an orange body color and pinkeyes.

As mentioned above, in the nonalbino goldfish (wakin, black moor, transparent-scaled gold-fish, etc.) the retinal pigment granules become visible a t St-21, and the skin melanophores beginto appear at St-22. In the analysis of albino genes, th e scoring of phenotype was carried out intwo different stages; first in St-21, soon after the differentiation of retinal pigment granules,and then in St-27, when the skin melanophores are completely developed.

The recessiue transparent-scaled goldfish: Fish carrying this character were isolated in ourlaboratory in 1960 from the F, offspring of homozygous transparent fish an d wakin. In one ofthese matings, six new mutant fish appeared, which almost completely lacked pigment granulesin their iridophores. These fish were apparently different from the ordinary transparent-scaledfish, because they did not differentiate the pigment granules from the time of iridophore dif-ferentiation (St-24), although some of the fish later synthesized them incompletely.

The melanophores and xanthophores differentiated as usual in the embryonic stage, and theydid not depigment a t the time the pigment cells degenerate in the ordinary transparent-scaledgoldfish (St-27-k). Two of them, however, lost their melanophores two to three months afterhatching, at the time of depigmentation of larval melanophores in the common goldfish. Theremaining four have retained their melanophores throughout their lives. The former type wasdesignated red recessive-transparent fish (simply, red transparent fish) and the latter wasblack recessive-transparent fish (simply, black transparent fish) .

All of the matings were carried out between a single male and a single female under naturalbreeding conditions. The specific matings are presented in the results. There was no evidenceof sex linkage for any of the mutations i n an y of the experiments, and it is assumed that a ll ofthe mutations are autosomal.

RESULTSI. Analysis of the depigmentation character of larval melanophores:

( A ) Crosses of wakin with black moor: Results of crosses between wakin and


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164 T. KAJISHIMATABLE 1

Resulis of crosses between wakin and black moor goldfish

Crosses Number of offspringDepigmented Pigmented Ratio XZ- -Wakin x Black Moor (F,) 478 0

Fl x F, 185 12 15:l 0.9 (P=O.5-0.3)F, x Black Moor 62 26 3: l 0.97 (P=O.5-0.3)black moor F,, F, X F, fish, and F, fish backcrossed to black moor fish are givenin Table 1. It is apparent that the character f o r depigmentation of the melano-phores in the wakin is dominant to the character for nondepigmentation in theblack moor. The results of the F, X F, and F, x black moor are consistent withthe assumption that the depigmentation character of wakin (nondepigmentationcharacter of black moor) is controlled by two multiple genes.The results presented in Table 1 are the final phenotypes of the fish after fouryears; however, not all fish that were eventually scored as depigmented startedto lose their pigment a t two to three months after hatching, as do the wakin gold-fish. Some of the fish in the F, x F, crosses and F, x black moor cross did notdepigment until their third year. T o ascertain the genotypes of the depigmentedF, individuals, the fish that depigmented in the first year, second year and thirdyear were backcrossed to the black moor. As shown in Table 2, backcross off-spring of four of the five fish which depigmented in their first year all depig-mented completely, while offspring of the fifth fish segregated in the ratio of 3: 1depigmented to pigmented. Three crosses out of five involving second-year depig-

TABLE 2Result of back crosses b etwe en dep igmenied F , ( w a k i n x black moor) and black moor

Age of Number of offspringdepigmentation (year) N o. Depigmented Pigmented Ratio X Z

- - -1 672 784 535 72 -1 622 87 -

Second 3 47 13 3:l 0.36 (P=0.7-0.5)4. 59 21 3:l 0.07 (P=0.8-0.7)5 1321 21 19 1:l 0.10 (P ~0 .8 -0 .7 )2 47 55 1:l 0.62 (P=O.5-0.3)

- - -First 3 62 23 3:l 0.62 (P=O.5-0.3)- - -

- -- - -

- -- - -

Third 3 31 29 1:l 0.06 (P=0.9-0.8)4 24 30 1:l 0.66 (P=0.5-0.3)

Th e numbers represent the total number of depigmented or nondepigmented offspring for fouryears.


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COLOR MUTANTS IN GOLDFISH 165mented F, produced all depigmented progeny, and in the other two crosses thesegregation ratio of the depigmented and pigmented types was 3 :1. All the off-spring of third-year depigmented F, segregated in the ratio of 1 1 depigmented topigmented.

The differences in segregation ratios in these crosses can be explained by thedifferences in the number and combination of dominant and recessive genes.Those parental fish that produced all depigmented offspring may be homozygousdominant for one or both depigmentation genes, and those fish producing theratio of 1:1 may be homozygous recessive at one locus and heterozygous at theother. The fish whose offspring segregated in the ratio of 3 :1 must have bothdominant genes in the heterozygous condition, because the same ratio wasobserved in the backcross of wakin and black moor F, to black moor (Table 1 ) .These results indicate that the onset of depigmentation is related to the numberof depigmentation and/or nondepigmentation genes.(B ) Crosses of red telescqpe fish with wakin and black moor:The parental redtelescope-eyed fish were inbred for five generations in our laboratory. However,the offspring of these crosses always included some of the nondepigmentationtype (Table 3A) that could not be distinguished from the black moor. In thedepigmented offspring, more than two-thirds of the individuals lost their mel-anophores in the second to fourth year, thereby acquiring their final phenotype.From these results it became apparent that the red telescope fish are not homo-zygous, but heterozygous for the depigmentation genes.

The results of crosses between red telescope fish and wakin (F,) and F, X F,are shown in Table 3A. All of the F, and F, offspring lost their melanophores.

T A B L E 3( A ) Results of inbreeding of red telescope fish and of crosses between red telescope fish and wakin

( B ) Results of crosses betw een black moor and red telescope fish( C ) Results of crosses betwe en homozygous transparent-scaled fish and wakinand between F , and black moorN u m b e r of offspringCrosses Depigmented P igm ented Rat io X2

x Red Telescope 80 30 - -x W a k i n (F,) 156 0F, x F, 309 0X Red Telescope (1 ) 81 0

Red Telescope(A ) Red Telescope - -

- -Black Moor

- -( B ) -__-- 2) 36 41 1:l 0.3 (P=O.7-0.5)

(3) 93 35 3: l 0.37 (P=0.7-0.5)Homo. T r a n s p a r e n t - -x W a k i n (F,) 194 0(C ) F, X F, 144 9 15:l 0.56 (P=0.7-0.5)F, X Black M oor 134 47 3:l 0.09 (P=0.8-0 .7)


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COLOR MUTANTS IN GOLDFISH 167TABLE 4

Results of crosres ( A ) between albino and wakin, ( B ) between albino and black moor and( C ) between albino and homozygous transparent-scaledgoldfish, scored at St-21 and St-27

Number of offspringCrosses Albino Pigmented R at io X2Albino x Wakin (F,) 0 381F, x F, (St-21) 137 427

(A) (St-27) 65 991F, x Albino (St-21) 133 151(St-27) 32 104

Albino x Black Moor (F,) 0 258(B) __-- (St-27) 30 425F, X F, (St-21) 54 144.F, x Albino (St-27) 33 101

Albino x Transparent-scaled fish (F,) 0 563(C) F, X F, (St-21) 1 32 302-_-_ (St-27) 80 1256

- -1:3 0.15 (P=O.7-0.5)1:15 0.02 (P=O.9-0.8)1:l 1.08 (P=0.3-01.2)1:3 0.15 (P=0.7-0.5)- -

1 3 0.53 (Pz0.5-0.3)1:15 0.10 ( P y 0 . 8 - 0 . 7 )1:3 0.10 (P=O.8-0.7)

- -1 3 0.01 (P=0.95-0.9)1:15 0.15 (Pz0.7-0.5)

(B ) Crosses of albino with black moo r: All of the F, offspring were pigmented,and the larval melanophores in the skin were depigmented during their lifespan.This suggests that the albino character in the goldfish is recessive to the blackmoor, though the albino carries the dominant depigmentation genes. The segre-gation ratios of the albino and nonalbino types in the F, offspring are shown inTable 4B, and the ratio of the albino and nonalbino types in offspring resultingfrom F, backcrossed with albino was 1 3.(C ) Crosses of albino with homozygous transparent-scaled f ish: The F, fishhad the characteristic calico pattern, and in the F, offspring (both albino andnonalbino) three kinds of scale types segregated in the ratio of 1:2:1. The ratioof the albino and nonalbino types was 1:15 (Table 4C). Offspring exhibitingboth the homozygous transparent and albino types, with no pigment at all in theskin or pigment retina, segregated in the ratio of 1 63. From these results it wasascertained that the albino and scale transparency character are not linked toeach other.111. Ana l ys i s of recessive-transparent character:

(A) Crosses of recessive-transparent fis h with hom ozy gou s transparent-scaledf i sh: All of the F, offspring were heterozygous transparent in type, having threekinds of pigment cells in a complicated calico pattern. This indicates that therecessive-transparent fish is homozygous normal-scaled in type and is recessiveto the ordinary transparent-scaled type. The F, offspring segregated into thefollowing three types: homozygous transparent-scaled type, heterozygous trans-parent-scaled type and normal-scaled type in the ratio of 1 2:1; and in thenormal-scaled type, the recessive-transparent type segregated in the ratio of 1 :3(Table 5A ) .


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168 T. KAJISHIMATABLE 5

Results of crosses ( A ) beiween recessive-iramparent fish and homozygous transparent-scaled fish,( B ) beiween recessive-transparent fish and wakin and ( C ) between recessive-transparentfish and albino goldfish

CrossesNumber of offspringNorma l transparent Ratio x z

Recessive

Recessive-transparent x- -Homo. Transparent (F,) 0 0

22 7 3:l 0.10 (P=0.8-0.7)A) F, X F,'Recessive-transparent x

- -Wakin (F,) 390 0(B) F, x F, 67 19 3 : l 0.39 (P=0.7-0.5)Recessive-transparent x

- -Albino (F,) 253 0( C ) F, x F,t 287 91 3:l 0.17 (P=0.7-0.5)* Scored osnly in normal-scaled type.+ Scored only i n non-albino type.(B) Crosses of recessive-transparent fish with wakin: In the first mating a

red transparent male fish was used, and in the second a black transparent femalewas used. In both cases the F, offspring were all normal (wakin) type. But thedepigmentation character of the larval melanophores was different iE the twomatings. In the first cross, all of the F, fish lost their larval melanophores withina year, but in the second, some of the offspring retained their larval melanophoresfor more than two years. These differences seemed to be caused by a differencein the genotypes of the depigmentation genes. The segregation ratio of normaland recessive-transparent type in the F, offspring is shown in Table 5B . Fromthese results it became apparent that the wakin is dominant to the recessive-transparent type, and the latter character is controlled by a single gene.(C ) Crosses of recessive-transparent fish with albino: All of the offspringwere normal in type. The segregation ratio of the F, offspring is shown in Table5C . From these results it became apparent that the albino goldfish is dominantfor the recessive-transparent character, although the fish i s recessive for thealbino character.

DISCUSSIONDepigm entation character of the m elanophore: In the present experiments it

became apparent that depigmentation of the larval melanophores in the wakinis dominant to nondepigmentation in the black moor, and that the character iscontrolled by two autosomal dominant multiple genes. When the two genes areboth homozygous recessive, the fish retains its larval melanophores throughoutits life. The symbols D p , and D p2 are proposed for the depigmentation type, andd p , and dp9 for the nondepigmentation type. The genotype of the wakin is repre-sented by D p , D p , D p 2 D p , and the black moor by dp l dp l dp , dp2 .


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COLOR MUTANTS IN GOLDFISH 169As mentioned in the previous section, red telescope fish always produced some

nondepigmented offspring upon inbreeding, and it was concluded that the geno-type of these fish is not homozygous dominant for the depigmentation character.The recessive transparent fish (both red and black) also did not seem to behomozygous for the depigmentation genes, although a detailed analysis was notcarried out on this character.

On the other hand, the segregation ratios in the F, and F, of crosses of homo-zygous transparent-scaled fish with wakin and of F, with black moor (Table 3C)were in complete agreement with the ratios in the crosses of black moor withwakin (Table 1 ) . From these results it became apparent that the homozygoustransparent-scaled fish carries the same genotype as the black moor for the depig-mentation character of larval melanophores. The segregation ratios of albino towakin (Table 4A) lead to the conclusion that the fish carries the homozygousdominant genes for the depigmentation character.

In the backcross of F, with wakin and black moor with black moor, the segre-gation ratios of depigmented and nondepigmented type separated into three types(Table 2). These results led to the following conclusions: fish that depigmentedwithin a year may carry the dominant depigmentation genes in the homozygouscondition, and the later it occurs, the smaller the number of dominant alleles.Though the initiation of depigmentation in melanophores may be related to thenumber of depigmentation alleles, no qualitative nor quantitative differencesbetween the functions of the two genes were found in the present experiments.

Albinism: Albinism in the goldfish is not a simple Mendelian character, butis represented by the double homozygous condition of two recessive genes. A finalsegregation ratio of 1: 15 in the F, offspring resulting from crosses between thealbino and non-albino types supports this conclusion. Moreover, developmentalobservations on the course of phenotypic expression revealed that three-fourthsof the initially albino fish changed to the pigmented type in an advanced embry-onic stage. Thus, the precise phenotypes in the F, offspring are in a ratio of1 :3:12 for the albino, late-pigmented and pigmented types. This ratio is char-acteristic of duplicate gene interaction in dominant epistasis, and the followingsymbols are proposed for the genes for melanin synthesis in goldfish (KAJISHIMA1972) .P: Controls primarily the normal pigmentation of the pigment retina. The

homozygous recessive allele p causes pink eyes.C: Controls primarily the color formation in the skin melanophores and is

epistatic to P and p . The homozygous recessive allele c causes a colorlesscondition in melanophores.

The genotype of an albino is represented by pp cc, and the genotype of wakin,black moor, homozygous transparent-scaled fish and recessive transparent fishare all represented by PP CC.YAMAMOTO1973) has proposed the symbols M and 5 for normal pigmentedgoldfish. The M gene controls normal melanin formation and normal melano-

phore develcpment; and S governs slower melanin and melanophore formation.


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172 T. K A J I S H I M AAs a result of the present experiment, it becomes plausible that the time of

initiation of depigmentation is controlled by the number of depigmentationgenes. When the dominant genes are in the homozygous condition, depigmenta-tion usually occurs within a year, and the lesser the number of dominant genes,the later it occurs. Finally, in the homozygous recessive condition, the larvalmelanophores do not depigment throughout the life of the fish. These facts, how-ever, do n o t contradict the assumptions of the previous paper. The quantity ofgene products which carry out the melanophore destruction must be proportionalto the gene dosage, and the production of such substances may be initiated by thetriggering factor(s). But the nature of the gene product, and the reason itsquantity affects the time of melanophore destruction, remain in question.Color mu tan t genes and Gem -duplic at ion hypothesis: Recently OHNOandhis coworkers proposed the Gene-duplication hypothesis in the fish familyCyprinidae (OHNOand ATKZN 966; OHNOet al. 1967; WOLF t al. 1969;OHNO 1970). This hypothesis is chiefly attributed to the following three obser-vations: (1 In some species of Cyprinidae, including the goldfish, the numberof chromosomes are duplicated. (2) The comparative DNA content per cell isincreased relatively along with the chromosome number. (3 ) The number ofgene loci which control some of the dehydrogenase isozyme patterns are dupli-cated in tetraploid fish. If this is true, the number of gene loci which control thepigmentation of chromatophore and pigment retina may also be duplicated in thegoldfish.

The genotypes which have been analyzed in the present experiment are sum-marized in Table 6. It is remarkable that half of the characters in this table aregoverned by multiple gene pairs; especially the depigmentation character ofmelanophores in which two multiple genes, D p, and Dp,, eem to be identicalin function, and the albino genes, in which the information of the P and C genesseems to resemble each other. Though it is not cited in this table, CHEN (1934)

T A B L E 6The genotypes of color mutants in the go ld f i s h

Gene function Melanophore IridophoreMutants Formation Destruction Formation Destruction-W a k i n (Common goldfish) p p cc DPlDP, DP,DP, GG tt

Black p p cc dPldP, dP,dP, GG ttTelescope-eyed fish(The B lack M oor )RedAlbinoRecessive trsnsparent-fish

Black P P cc gg ttRed PP cc D p , D p , DP,DP,? gg tt______Transparent-scaled fishHom ozygous f ish PP cc dP,dP, dP,dP, GG T THeterozygous fish PP cc ~ P & P , dp,dp, GG T t


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COLOR MUTANTS I N GOLDFISH 173has reported tetrahybrid inheritance in the brown coloration in the goldfish.These facts seem to support OHNOSypothesis.

On the other hand, the remaining two mutants, which are both related to theiridophore character, are each controlled by a single gene. However, for the trans-parent-scaled character, some question remains as to whether o r not it is actuallycontrolled by a single gene. It has been pointed out that the results of the earlyexperiments show that the homozygous transparent-scaled type TT does notalways lose the iridophores completely, and frequently some of the fish retain aconsiderable number of chromatophores (not only the iridophores, but also themelanophores and xanthophores) so that sometimes the fish are not easily dis-tinguishable from the heterozygous typeTt (CHEN1928; GOODRICHnd HANSEN1931; MATSUI 934; KAJISHIMA 960a). These facts cannot be explained by theincomplete dominance of gene T.

An hypothesis which can explain these situations is as follows: scale trans-parency is a character that is controlled by two multiple genes; one the T alleleand the other an unknown wild-type allele. If this is true, the genotype of homo-zygous transparent fish is represented by TT ++, and the phenotype of thesefish may be difficult to distinguish from that of the heterozygous fish Tt ++.From 1957 to 1960, we examined more than fifty thousand F, fish resulting fromcrosses between the homozygous transparent-scaled fish and wakin, but wereunable to get any specimens which verify the above hypothesis, so that it stillremains in doubt at the present time.

On the other hand, it was ascertained in the present experiment that therecessive-transparent character is apparently controlled by a single recessivegene. The same conclusion has been reported by MATSUI 1934) for the inheri-tance of the telescope-eyed character. To explain these exceptional cases, OHNO(personal communication) has proposed the hypothesis tha t the redundant copyof a gene can either be a new gene o r become degenerate, joining the rank ofnonfunctional DNA base sequences. At the present time, however, we have noevidence to test this hypothesis, but a detailed analysis of these problems may beexpected in the future.

The author wishes to express his hearty thanks to EMERITUS ROF.TOKI-o AMAMOTOndDR. H. TOMITA,ho kindly provided the opportunity to use the albino goldfish for this experi-ment. I am also grateful to Mrs. C. A. MAHI,of The University of Hawaii for critical readingof the manuscript.

LITERATURE CITEDBERNDT,W., 1925 Vererbungsstudien am Goldfischrassen. Zeits. Indik. Abst. Vererd . 36:

161-349.BLACHER,. J., 1927 The role of the hypophysis an d of the thyroid gland in the cutaneous pig-

mentary function of amphibian and fishes. Trans. Lab. exp. Biol. Zoopark, Moscow 3: 79-81.CHEN,S . C., 1925 Variation in external characters of goldfish, Carassius auratus. Contri. Biol.

Lab. Sci. Soc. China 1: 1-651. Transparency and mottling, a case of Men-delian inheritance in the goldfish, Carassius auratus. Genetics 13: 434452. 1934The inheritance of blue and brown colors in the goldfish, Carassius auratus. J. Genet. 29:

__ 1928 -,61-74.


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174 T. KAJISHIMAFUKUI, . 1927 On the color pattern produced by various agents in the goldfish. Folia. Anat.

Japonica 5: 257-302.GOODRICH,. . and P. L. ANDERSON,939 Variations of color pattern i n hybrids of the gold-

fish, Carassius aumtus. Biol. Bull. 77: 184-191.GOODRICH,. B. and I. B. HANSEN,931 The postembryonic development of Mendel ian char-acters in the goldfish,Carassius auratus. J. exp. Zool. 59: 337-358.HANCE,R. T., 1924 Heredity in goldfish. A note on the inheritance of dove-tail and telescope-

eyes in goldfish. J. Heredity 15: 177-182.KAJISHIMA,T., 1960a Analysis of gene action in the transparent-scaled goldfish, Carassiusauratus . I. On the gene action in the disappearance of guanophoers. Embryoolgia 5: 107-

126. -, 1960b Analysis of gene action in the transparent-scaled goldfish, Caras iusaura!us. 11. The effects of pituitary and thyroid on gene action. Embryologia 5 : 127-138.-_ , 1960c Analysis of gene action in t he transparent-scaled goldfish, Carassius auralus.111. Guanine metabolism in the developing larvae. Annot. Zool. Japon. 33: 245-248. -,1960d The normal developmental stages of the goldfish, Carassius auralus. Jap. Jour.Ichthy. 8 : 20-28. -, 1967 Inher itance of a new recessive transparent fish in thegoldfish. Jap. J. Genet. 42: 418. (abstract) -- 1972 Genetics and embryologicalstudies of albino goldfish, Jap. J. Genet. 48: 351-352. (abstract) - 1975 In v i t roanalysis of gene depression in goldfish choroidal melanophores. J. exp. Zool. 191 121-126.MATSUI, ., 1931. Genetical studies on goldfish of Japan. J. Fish. Inst. Tokyo 30: 1-96.

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Corresponding editor: D. T. SUZUKI

1977. Analisis Genetico de Alguno Nuevos Colores Mutantes en El Goldfish. Universidad de Nagoya,...

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Transcript of 1977. Analisis Genetico de Alguno Nuevos Colores Mutantes en El Goldfish. Universidad de Nagoya,...