Molec. gen. Genet. 172, I99~02 (1979) © by Springer-Verlag 1979
Genetical and Cytological Location of the Structural Parts Coding for the First Three Steps of Pyrimidine Biosynthesis in Drosophilamelanogaster B.P. Jarry Centre de Biochimie et de Biologie Mol6culaire, C.N.R.S., 31 chemin Joseph Aiguier, F-13274 Marseille, Cedex 2, France
Summary. The rudimentary locus (r; X-55.3) of Drosophila melanogaster is shown to contain the struc-
tural sequences for the enzymes CPSase, ATCase and DHOase. The enzyme concentration in adult flies is correlated with the number of r + copies in the genome. The expression of the locus follows the rules of the gene dosage compensation hypothesis when extracts of newly emerged males and females are compared.
Introduction
Rudimentary (1-55.3; r) is a sex linked recessive pleiotropic mutation affecting both wing phenotype and female fertility (Morgan, 1915). The locus has been extensively investigated genetically (Fahmy and Fahmy, 1959; Green, 1963; Carlson, 1971). Carlson (1971) first placed rudimentary between 14D1-2 on the salivary gland chromosome map on the basis that a portion of this region was missing on a deficiency chromosome which brought a standard r phenotype in hemi or homozygous flies. More recently the biochemical basis of this phenotype has been traced to a reduce activity of one single or all of the first three enzymes of de novo pyrimidine pathway, namley carbamyl phosphate synthetase (CPSase), aspartate transcarbamylase (ATCase) and dihydroorotase (DHOase) (Norby, 1973; Jarry and Falk, 1974; Rawls and Fristrom, 1975). Flies which carry a large duplication of the X chromosome covering the rudimentary locus exhibit increased activity for ATCase and DHOase in crude extracts even if homozygous for a r allele which brings a reduction of the CPSase enzymatic activity (Rawls and Fristrom, 1975). This was taken as an indication that this part of the genome contains the ATCase and DHOase structural gene(s).
On the basis of new cytological and genetical information, Lefevre (1976) presented evidence for the location of the locus in the vicinity of the 15A 1 band of the salivary chromosome cytological map. The fact that the duplication used by Rawls and Fristrom covered both 1 4 D l ~ and 15A1 regions did not permitted any conclusion on the exact location of the enzymes structural gene(s). We decided therefore to address ourself directly to this question using a set of deficiencies isolated independently by M.M. Green and in this laboratory. These deficiencies have been cytologically defined by G. Lefevre. The results confirm the location of rudimentary in the 15A1 band vicinity and demonstrate unambiguously that carbamyl phosphate synthetase, aspartate transcarbamylase and dihydroorotase are encoded by this small region of the chromosome. By correlation with the enzymatic data obtained with flies carrying single alleles of rudimentary, it is concluded that the locus contains the corresponding structural gene(s).
Material and Methods a) Drosophila Stocks. The special chromosomes used in this study are described in Table 1. The rudimentary alleles have been genetically described by Carlson (1971). Table 1
Chromosome designation
Origin
Homozygous viability
Cytology ~
Df(1) (D) Df(1)D34 Df(1)D17 Dp(1;4)r+j ~
B. Jarry M. Green M. Green M. Green
lethal lethal lethal lethal
14B6-15A2 14F1-2-14F6 14F6-15A6 13F-16A1-2
Chromosomes used to locate CPSase-ATCase-DHOase structural region on the salivary gland chromosome map All cytological descriptions done by G. Lefevre
0026-8925/79/0172/0199/$01. O0
200
B.P. Jarry: Pyrimidine Biosynthesis in Drosophila melanogaster
b) Media. Mass cultures have been routinely maintained in bottles on standard corn-meal dextrose medium at 22 ° C.
c) Enzyme Assays. Wild-type and rudimentary flies were collected daily after emergence at 22 ° C and kept frozen at - 8 0 ° C until they could be assayed for enzymatic activities. Methods of enzyme assays were those reported by Jarry (1976). d) Rocket Electrophoresis. Raising and characterization of the rabbit antiserum directed against the three proteins associated in a complex have been described in details (Jarry, 1978). The rocket electrophoresis technique using partially purified 7-globulin fraction was applied as described (Axelsen et al., 1975).
Table 2. ATCase activity levels in flies carrying various numbers of r + gene copies Genotype
Description
Nor+ genes a
Enzyme activity b
Dr(l) D17/+
Deficiency female Normal female Duplication female Normal male
1 2 3
25.0 -+ 2 47.5_+4 65.3 +3
1
38.2 _+4
Normal male Duplication male
1 2
40 _+2 70 _+5
+/+
+/+ ; Dp(1;4)r+f+ Df(1) D17/Y; Dp(1;4)r+f+ +/Y +/Y; Dp(1;4)r+f+
The flies of each different genotypes were collected from the crosses
Results
vDf(1)D17f/vf;Dp(1;4)r+ f * f~(X) vDf(1)D17f/Y;Dp(l ;4)r+f+ and v Of(1)D17 f/v ff~ (X) vf/Y 8.
I. Mapping of the CPSase-A TCase-DHOase Structural Gene at Rudimentary The Df(1)D17 deficiency chromosome does not complement r mutations (Table 4) and is missing bands 14F6 to 15A6 of the salivary gland chromosomes. Similarly the duplication Dp(1 ;4) r ~f+ (Green, 1963) covers this same region. Combination of both chromosomes leads to flies in which the number of r ÷ copies can vary from 1 to 3 in females and 1 to 2 in males. Should the polypeptides responsible for the CPSase, ATCase and DHOase be encoded by the rudimentary locus, we hypothesized that a gene dosage effect would be detectable. The availability of an antiserum prepared in rabbit against the three enzymes purified as a complex (Jarry, 1978) made it possible to test this prediction at the level of enzyme concentration in crude extracts. Figure 1 presents the
2~ o 0
t-
Siblings of each sex scored on the basis of their forked and vermilion phenotypes were collected immediatly after emergence (Mehl and Jarry, 1978) and used for the assay, which was repeated at least three times Number of r + genes per diploid genome b Expressed as nmoles carbamylaspartate produced in 30 rain at 30 ° C per mg of protein
quantitative estimation of CPSase-ATCase-DHOase related antigen in extracts from females carrying various combinations of these special chromosomes. The same relationship holds true for the measurements of enzymatic activities in crude extracts (Table 2). Furthermore, when the number of copies of r-- in males is increasing from one to two, the ATCase activity increases about two-fold when compared with data in sibling females of the same genotypic composition. This relationship was indeed predicted by the gene dosage compensation hypothesis (Lucchesi, 1973). Similar results were obtained with CPSase and DHOase activities. It is therefore concluded that the geue(s) coding for the first three enzymes of the pyrimidine pathway are located between bands 14F615A6 of the cytological map.
I I
t>
1 r + copies
2 3 / genome
Fig. 1. R0cket-electrophoresis of crude extracts from females carrying various numbers of r + gene copies in their genome. 100 ~tg of total protein were deposited in each well. Electrophoresis was for 4 h with 10 V/cm. The protein was then stained with Coomassie blue and the height of the rocket measured. The bars represent the standard deviation in three different experiments
H. Cytogenetic Location of Rudimentary Flies heterozygous for a wild-type chromosome and the deficiencies Df(1)D17 and Dr(l)(D) have a low CPSase, ATCase and DHOase activity content. By contrast, flies heterozygous for Df(1)D34 have normal enzymatic activities when compared with a wild type combination (Table 3). The same effect is, as expected, detected genetically: Df(1)DI7 and Df(1) (D) do not complement representative alleles of the different complementation groups which subdivide the rudimentary locus, while Df(1)D34 does (Ta-
201
B.P. Jarry: Pyrimidine Biosynthesis in Drosophila melanogaster Table 3. CPSase, ATCase and DHOase levels in various heterozygote females involving deficiencies exposing the rudimentary locus Enzymatic activity (units)
Genotype
vf/vf Df(1)D17/vf Df(1) (D)/vf Df(1)D34/vf
CPSase a
ATCase b
DHOase b
72.6 30.0 12.5 70.0
47.5 25.0 12.6 52.0
115.0 50.0 69 100.0
a picomoles citrulline produced in 30 min at 37°C per mg of protein b nanomoles carbamyl aspartate produced in 30 min at 30°C per mg of protein
Table 4. Complementation test of various deficiencies with charac-
terized rudimentary alleles (Jarry and Falk, 1974) r 1
Df(1)D34 Df(1)D17
r 11
+ .
.
Df(1) (D)
.
.
vf
+
r 29
+ .
. +
+ .
.
.
.
+
r 38
r 45
+
+
+
+
Complementation was checked visually on the wing shape of the emerging females and on their sterility phenotype
ATCase and DHOase activities, are each derived from a 210,000MW primary translation product. This protein corresponds to an average DNA coding capacity of 6.6 kilobases (Jarry, 1978). We have recently estimated the size of the corresponding messenger RNA as 8 kilobases (kb) (unpublished results). Carlson (1971) calculated that the length of the locus (from recombination data) extends to 0.07 map units. Using the relationship established by Gelbart et al. (1974) for the xanthine dehydrogenase structural gene between recombination frequency and DNA length we had previously estimated the total DNA length of the rudimentary locus to be in the order of 25 kb (Jarry and Falk, 1974). Lefevre (1971) estimated the DNA content of an average band of the X-chromosome, such as 15A1, to be 30 kb. If this value is indeed correct, the rudimentary locus, as genetically defined by its two most separated alleles, would fill almost the entire band. (The adjacent interbands being also of average size would only very slightly affect these calculations). One should therefore conclude that the large discrepancy between the coding capacity and total DNA length of the locus might be related to recent reports of nontranslated DNA sequences found within structural genes in various animals (Gilbert, 1978).
Acknowledgments. The author is strongly indebted to M.M. Green
ble 4). The r locus is therefore located between the distal break points of Df(1)D34 and of Dr(l)(D) that is between bands 14F6 and 15A2.
for many stimulating discussions and generous sending of stocks. None of these conclusions could have been drawn without the expertise of G. Lefevre who established all the cytology described in this paper. This research was carried out with the help of a NATO research grant.
Conclusion
Drosophila melanogaster is probably the best genetically characterized eucaryotic higher organism and is therefore very well suited for any detailed study of the genetic organization of the DNA. However, so far only a few genes with known products have been cytogenetically located, an essential prerequisite for any further molecular analysis. This paper demonstrates that the rudimentary locus does indeed encode the first three enzymes activities of the pyrimidine pathway. Using a set of deficiencies covering this region of the X-chromosome, it is concluded that the structural part of r is located between bands 14F6 and 15A2, a direct confirmation of the previously determined localization of r to the 15AI band (Lefevre, 1976). Biochemical results lead us to propose that the three polypeptides, carrying respectively the CPSase,
References Axelsen, N.H., Kroll, J., Weeke, B.: A manual of quantitative immuno-electrophoresis: Methods and applications. Oslo: Universitetsforlaget 1975 Bridges, C.V. : A revised map of the salivary gland X-chromosome of Drosophila melanogaster. J. Hered. 29, 11-13 (1938) Carlson, P.S. : A genetic analysis of the rudimentary locus of Drosophila melanogaster. Genet. Res. (Camb.) 17, 63-81 (197l) Fahmy, O.G., Fahmy, M.J. : Complementation among the subgenic mutants of the r locus of Drosophila melanogaster. Nature 184, 1927-1929 (1959) Gelbart, W.M., McCarron, M., Pandey, J., Chovnick, A. : Genetic limits of the xanthine dehydrogenase structural element within the rosy locus in Drosophila melanogaster. Genetics 78, 869 886 (1974) Gilbert, W. : Why genes in pieces? Nature 271, 501 (1978) Green, M.M. : InteralMic complementation and recombination at the rudimentary wing locus in Drosophila melanogaster. Genetics 34, 242-253 (1963) Jarry, B.P. : Isolation of a multifunctional complex containing the
202 first three enzymes of pyrimidine biosynthesis in Drosophila melanogaster. FEBS Lett. 70, 71-75 (1976) Jarry, B.P. : Purification of aspartate transcarbamylase from Drosophila melanogaster. Eur. J. Biochem. 87, 533-540 (1978) Jarry, B.P., Falk, D. : Functional diversity within the rudimentary locus of Drosophila melanogaster. Mol. Gen. Genet. 135, 113-122 (1974) Lefevre, G., Jr.: Salivary chromosome bands and the frequency of crossing over in Drosophila melanogaster. Genetics 67, 497-507 (1971) Lefevre, G., Jr. : In: The Genetics and Biology of Drosophila. (M. Ashburner and E. Novitsky, eds.), Vol. la, pp. 32 64. New York: Academic Press 1976 Lucchesi, J.C.: Dosage compensation in Drosophila. Ann. Rev. Genet. 7, 177 204 (1973)
B.P. Jarry: Pyrimidine Biosynthesis in Drosophila melanogaster Mehl, Y., Jarry, B.P. : Developmental regulation of the first three enzymes of pyrimidine biosynthesis in Drosophila melanogaster. Dev. Biol. 67, 1 10 (1978) Morgan, T.H.: The infertility of rudimentary winged females of Drosophila amyelophila. Am.Nat. 49, 240-250 (1915) Norby, S.: The biochemical genetics of rudimentary mutants of Drosophila melanogaster. Hereditas 73, 11-16 (1973) Rawls, J.M., Fristrom, J.W. : A complex genetic locus that controls the first three steps of pyrimidine biosynthesis in Drosophila. Nature 255, 738-740 (1975) Communicated
by M.M.
Received December 22, 1978
Green
Genetical and Cytological Location of the Structural Parts Coding for the First Three Steps of Pyrimidine Biosynthesis in Drosophilamelanogaster B.P. Jarry Centre de Biochimie et de Biologie Mol6culaire, C.N.R.S., 31 chemin Joseph Aiguier, F-13274 Marseille, Cedex 2, France
Summary. The rudimentary locus (r; X-55.3) of Drosophila melanogaster is shown to contain the struc-
tural sequences for the enzymes CPSase, ATCase and DHOase. The enzyme concentration in adult flies is correlated with the number of r + copies in the genome. The expression of the locus follows the rules of the gene dosage compensation hypothesis when extracts of newly emerged males and females are compared.
Introduction
Rudimentary (1-55.3; r) is a sex linked recessive pleiotropic mutation affecting both wing phenotype and female fertility (Morgan, 1915). The locus has been extensively investigated genetically (Fahmy and Fahmy, 1959; Green, 1963; Carlson, 1971). Carlson (1971) first placed rudimentary between 14D1-2 on the salivary gland chromosome map on the basis that a portion of this region was missing on a deficiency chromosome which brought a standard r phenotype in hemi or homozygous flies. More recently the biochemical basis of this phenotype has been traced to a reduce activity of one single or all of the first three enzymes of de novo pyrimidine pathway, namley carbamyl phosphate synthetase (CPSase), aspartate transcarbamylase (ATCase) and dihydroorotase (DHOase) (Norby, 1973; Jarry and Falk, 1974; Rawls and Fristrom, 1975). Flies which carry a large duplication of the X chromosome covering the rudimentary locus exhibit increased activity for ATCase and DHOase in crude extracts even if homozygous for a r allele which brings a reduction of the CPSase enzymatic activity (Rawls and Fristrom, 1975). This was taken as an indication that this part of the genome contains the ATCase and DHOase structural gene(s).
On the basis of new cytological and genetical information, Lefevre (1976) presented evidence for the location of the locus in the vicinity of the 15A 1 band of the salivary chromosome cytological map. The fact that the duplication used by Rawls and Fristrom covered both 1 4 D l ~ and 15A1 regions did not permitted any conclusion on the exact location of the enzymes structural gene(s). We decided therefore to address ourself directly to this question using a set of deficiencies isolated independently by M.M. Green and in this laboratory. These deficiencies have been cytologically defined by G. Lefevre. The results confirm the location of rudimentary in the 15A1 band vicinity and demonstrate unambiguously that carbamyl phosphate synthetase, aspartate transcarbamylase and dihydroorotase are encoded by this small region of the chromosome. By correlation with the enzymatic data obtained with flies carrying single alleles of rudimentary, it is concluded that the locus contains the corresponding structural gene(s).
Material and Methods a) Drosophila Stocks. The special chromosomes used in this study are described in Table 1. The rudimentary alleles have been genetically described by Carlson (1971). Table 1
Chromosome designation
Origin
Homozygous viability
Cytology ~
Df(1) (D) Df(1)D34 Df(1)D17 Dp(1;4)r+j ~
B. Jarry M. Green M. Green M. Green
lethal lethal lethal lethal
14B6-15A2 14F1-2-14F6 14F6-15A6 13F-16A1-2
Chromosomes used to locate CPSase-ATCase-DHOase structural region on the salivary gland chromosome map All cytological descriptions done by G. Lefevre
0026-8925/79/0172/0199/$01. O0
200
B.P. Jarry: Pyrimidine Biosynthesis in Drosophila melanogaster
b) Media. Mass cultures have been routinely maintained in bottles on standard corn-meal dextrose medium at 22 ° C.
c) Enzyme Assays. Wild-type and rudimentary flies were collected daily after emergence at 22 ° C and kept frozen at - 8 0 ° C until they could be assayed for enzymatic activities. Methods of enzyme assays were those reported by Jarry (1976). d) Rocket Electrophoresis. Raising and characterization of the rabbit antiserum directed against the three proteins associated in a complex have been described in details (Jarry, 1978). The rocket electrophoresis technique using partially purified 7-globulin fraction was applied as described (Axelsen et al., 1975).
Table 2. ATCase activity levels in flies carrying various numbers of r + gene copies Genotype
Description
Nor+ genes a
Enzyme activity b
Dr(l) D17/+
Deficiency female Normal female Duplication female Normal male
1 2 3
25.0 -+ 2 47.5_+4 65.3 +3
1
38.2 _+4
Normal male Duplication male
1 2
40 _+2 70 _+5
+/+
+/+ ; Dp(1;4)r+f+ Df(1) D17/Y; Dp(1;4)r+f+ +/Y +/Y; Dp(1;4)r+f+
The flies of each different genotypes were collected from the crosses
Results
vDf(1)D17f/vf;Dp(1;4)r+ f * f~(X) vDf(1)D17f/Y;Dp(l ;4)r+f+ and v Of(1)D17 f/v ff~ (X) vf/Y 8.
I. Mapping of the CPSase-A TCase-DHOase Structural Gene at Rudimentary The Df(1)D17 deficiency chromosome does not complement r mutations (Table 4) and is missing bands 14F6 to 15A6 of the salivary gland chromosomes. Similarly the duplication Dp(1 ;4) r ~f+ (Green, 1963) covers this same region. Combination of both chromosomes leads to flies in which the number of r ÷ copies can vary from 1 to 3 in females and 1 to 2 in males. Should the polypeptides responsible for the CPSase, ATCase and DHOase be encoded by the rudimentary locus, we hypothesized that a gene dosage effect would be detectable. The availability of an antiserum prepared in rabbit against the three enzymes purified as a complex (Jarry, 1978) made it possible to test this prediction at the level of enzyme concentration in crude extracts. Figure 1 presents the
2~ o 0
t-
Siblings of each sex scored on the basis of their forked and vermilion phenotypes were collected immediatly after emergence (Mehl and Jarry, 1978) and used for the assay, which was repeated at least three times Number of r + genes per diploid genome b Expressed as nmoles carbamylaspartate produced in 30 rain at 30 ° C per mg of protein
quantitative estimation of CPSase-ATCase-DHOase related antigen in extracts from females carrying various combinations of these special chromosomes. The same relationship holds true for the measurements of enzymatic activities in crude extracts (Table 2). Furthermore, when the number of copies of r-- in males is increasing from one to two, the ATCase activity increases about two-fold when compared with data in sibling females of the same genotypic composition. This relationship was indeed predicted by the gene dosage compensation hypothesis (Lucchesi, 1973). Similar results were obtained with CPSase and DHOase activities. It is therefore concluded that the geue(s) coding for the first three enzymes of the pyrimidine pathway are located between bands 14F615A6 of the cytological map.
I I
t>
1 r + copies
2 3 / genome
Fig. 1. R0cket-electrophoresis of crude extracts from females carrying various numbers of r + gene copies in their genome. 100 ~tg of total protein were deposited in each well. Electrophoresis was for 4 h with 10 V/cm. The protein was then stained with Coomassie blue and the height of the rocket measured. The bars represent the standard deviation in three different experiments
H. Cytogenetic Location of Rudimentary Flies heterozygous for a wild-type chromosome and the deficiencies Df(1)D17 and Dr(l)(D) have a low CPSase, ATCase and DHOase activity content. By contrast, flies heterozygous for Df(1)D34 have normal enzymatic activities when compared with a wild type combination (Table 3). The same effect is, as expected, detected genetically: Df(1)DI7 and Df(1) (D) do not complement representative alleles of the different complementation groups which subdivide the rudimentary locus, while Df(1)D34 does (Ta-
201
B.P. Jarry: Pyrimidine Biosynthesis in Drosophila melanogaster Table 3. CPSase, ATCase and DHOase levels in various heterozygote females involving deficiencies exposing the rudimentary locus Enzymatic activity (units)
Genotype
vf/vf Df(1)D17/vf Df(1) (D)/vf Df(1)D34/vf
CPSase a
ATCase b
DHOase b
72.6 30.0 12.5 70.0
47.5 25.0 12.6 52.0
115.0 50.0 69 100.0
a picomoles citrulline produced in 30 min at 37°C per mg of protein b nanomoles carbamyl aspartate produced in 30 min at 30°C per mg of protein
Table 4. Complementation test of various deficiencies with charac-
terized rudimentary alleles (Jarry and Falk, 1974) r 1
Df(1)D34 Df(1)D17
r 11
+ .
.
Df(1) (D)
.
.
vf
+
r 29
+ .
. +
+ .
.
.
.
+
r 38
r 45
+
+
+
+
Complementation was checked visually on the wing shape of the emerging females and on their sterility phenotype
ATCase and DHOase activities, are each derived from a 210,000MW primary translation product. This protein corresponds to an average DNA coding capacity of 6.6 kilobases (Jarry, 1978). We have recently estimated the size of the corresponding messenger RNA as 8 kilobases (kb) (unpublished results). Carlson (1971) calculated that the length of the locus (from recombination data) extends to 0.07 map units. Using the relationship established by Gelbart et al. (1974) for the xanthine dehydrogenase structural gene between recombination frequency and DNA length we had previously estimated the total DNA length of the rudimentary locus to be in the order of 25 kb (Jarry and Falk, 1974). Lefevre (1971) estimated the DNA content of an average band of the X-chromosome, such as 15A1, to be 30 kb. If this value is indeed correct, the rudimentary locus, as genetically defined by its two most separated alleles, would fill almost the entire band. (The adjacent interbands being also of average size would only very slightly affect these calculations). One should therefore conclude that the large discrepancy between the coding capacity and total DNA length of the locus might be related to recent reports of nontranslated DNA sequences found within structural genes in various animals (Gilbert, 1978).
Acknowledgments. The author is strongly indebted to M.M. Green
ble 4). The r locus is therefore located between the distal break points of Df(1)D34 and of Dr(l)(D) that is between bands 14F6 and 15A2.
for many stimulating discussions and generous sending of stocks. None of these conclusions could have been drawn without the expertise of G. Lefevre who established all the cytology described in this paper. This research was carried out with the help of a NATO research grant.
Conclusion
Drosophila melanogaster is probably the best genetically characterized eucaryotic higher organism and is therefore very well suited for any detailed study of the genetic organization of the DNA. However, so far only a few genes with known products have been cytogenetically located, an essential prerequisite for any further molecular analysis. This paper demonstrates that the rudimentary locus does indeed encode the first three enzymes activities of the pyrimidine pathway. Using a set of deficiencies covering this region of the X-chromosome, it is concluded that the structural part of r is located between bands 14F6 and 15A2, a direct confirmation of the previously determined localization of r to the 15AI band (Lefevre, 1976). Biochemical results lead us to propose that the three polypeptides, carrying respectively the CPSase,
References Axelsen, N.H., Kroll, J., Weeke, B.: A manual of quantitative immuno-electrophoresis: Methods and applications. Oslo: Universitetsforlaget 1975 Bridges, C.V. : A revised map of the salivary gland X-chromosome of Drosophila melanogaster. J. Hered. 29, 11-13 (1938) Carlson, P.S. : A genetic analysis of the rudimentary locus of Drosophila melanogaster. Genet. Res. (Camb.) 17, 63-81 (197l) Fahmy, O.G., Fahmy, M.J. : Complementation among the subgenic mutants of the r locus of Drosophila melanogaster. Nature 184, 1927-1929 (1959) Gelbart, W.M., McCarron, M., Pandey, J., Chovnick, A. : Genetic limits of the xanthine dehydrogenase structural element within the rosy locus in Drosophila melanogaster. Genetics 78, 869 886 (1974) Gilbert, W. : Why genes in pieces? Nature 271, 501 (1978) Green, M.M. : InteralMic complementation and recombination at the rudimentary wing locus in Drosophila melanogaster. Genetics 34, 242-253 (1963) Jarry, B.P. : Isolation of a multifunctional complex containing the
202 first three enzymes of pyrimidine biosynthesis in Drosophila melanogaster. FEBS Lett. 70, 71-75 (1976) Jarry, B.P. : Purification of aspartate transcarbamylase from Drosophila melanogaster. Eur. J. Biochem. 87, 533-540 (1978) Jarry, B.P., Falk, D. : Functional diversity within the rudimentary locus of Drosophila melanogaster. Mol. Gen. Genet. 135, 113-122 (1974) Lefevre, G., Jr.: Salivary chromosome bands and the frequency of crossing over in Drosophila melanogaster. Genetics 67, 497-507 (1971) Lefevre, G., Jr. : In: The Genetics and Biology of Drosophila. (M. Ashburner and E. Novitsky, eds.), Vol. la, pp. 32 64. New York: Academic Press 1976 Lucchesi, J.C.: Dosage compensation in Drosophila. Ann. Rev. Genet. 7, 177 204 (1973)
B.P. Jarry: Pyrimidine Biosynthesis in Drosophila melanogaster Mehl, Y., Jarry, B.P. : Developmental regulation of the first three enzymes of pyrimidine biosynthesis in Drosophila melanogaster. Dev. Biol. 67, 1 10 (1978) Morgan, T.H.: The infertility of rudimentary winged females of Drosophila amyelophila. Am.Nat. 49, 240-250 (1915) Norby, S.: The biochemical genetics of rudimentary mutants of Drosophila melanogaster. Hereditas 73, 11-16 (1973) Rawls, J.M., Fristrom, J.W. : A complex genetic locus that controls the first three steps of pyrimidine biosynthesis in Drosophila. Nature 255, 738-740 (1975) Communicated
by M.M.
Received December 22, 1978
Green
