X-CHROMOSOME BALANCERS # asc: see In(1)scS1Lsc8R+S # Basc: see In(1)scS1Lsc8R+S # Binsc: see In(1)scS1Lsc8R+dl49 # Binscy: see In(1)scS1Lsc8R+dl49 # Binsinscy: see In(1)scS1Lsc8R+dl49 # Binsn: see In(1)scS1Lsc8R+dl49 # Biny: see In(1)sc8LscS1R+dl49 # C(1)M4: see section on compound chromosomes # ClB constitution: In(1)Cl, sc l(1)C t2 v sl B. synthesis: Muller. references: 1928, Genetics 13: 279-357. properties: Male lethal. Suppresses crossing over in the X chromosome. Originally used in recovery of sex-linked reces- sive lethals; replaced by Basc for this purpose. # complete: see In(1)sc8+dl49 # finsky: see In(1)scS1Lsc8R+dl49 # FM0: see In(1)sc8+dl49 # FM1: see In(1)sc8+dl49 # FM3: First Multiple 3 constitution: In(1)FM3, y31d sc8 dm B. order: 1A-1B2|20F|16B-19F|3F-4D7|11F2-4E1|11F4-16A|3E-1B|20F. synthesis: R.F. Grell, 1954. references: Mislove and Lewis, 1954, DIS 28: 77. properties: Male lethal owing to presence of two multilocus deficiencies in In(1)FM3, which may be covered by BSYy+ or by BSY and y+Y (Schalet). Effectively suppresses crossing over in the X chromosome. Useful for balancing sex-linked reces- sive, female-sterile mutants and, in combination with BSYy+, for balancing sex-linked recessive lethal and male-sterile mutants. # FM4 constitution: In(1)FM4, y31d sc8 dm B. order: 1A-1B2|20F-11F4|4E|3C-4D7|11F2-4F|3C-1B3|20F. synthesis: R.F. Grell, 1954. references: Mislove and Lewis, 1954, DIS 28: 77. properties: Male viable and fertile; homozygous female viable but sterile owing to dm. In(1)FM4 is the consequence of the approximate reinversion of In(1)dl49 in In(1)sc8+dl49 and is similar in sequence to In(1)sc8 but with the transposition of 3C-4F into 11F. Unless this small transposition has an abnor- mally large effect on crossing over (e.g., see Dp(2;2)C619) recombination might be expected to be frequent in FM4/+ heterozygotes and especially in FM4/In(1)sc8 heterozygotes. In FM4/+ heterozygotes, double crossovers with points of exchange inside or outside the 3C-11F interval produce euploid X chromosomes, and those with one point of exchange inside and one outside produce complementary duplications and deficien- cies for 3C-4F. The duplication survives in either sex and exhibits a Confluens phenotype (E.H. Grell); the deficiency might survive in the heterozygote as a Notch Minute female judging from the survival of the slightly smaller Df(1)wm258- 44 = Df(1)3C3-4;4D2-E1. Balancing properties not well deter- mined. Some lines carry w55f and in some y31d replaced with y+ or B with f or +. # FM6 constitution: In(1)FM6, y31d sc8 dm B. order: 1A-1B2|20F|15E-20F|15D-11F4|4E|3C- 4D7|11F2-4F|3C-1B3|20F. synthesis: R.F. Grell, 55i. references: Grell and Lewis, 1956, DIS 30: 71. properties: Male viable and fertile; homozygous females viable but sterile owing to the presence of dm. Like FM4 except for the presence of the additional In(1)15D-E;20A-B. Reservations similar to those about the balancing ability of FM4 apply in FM6 to the salivary chromosome region from 1B to 15D. In genotypes with a normal recombination rate, FM6 effectively eliminates recombination in FM6/+ heterozygotes but yields viable recombinants when heterozygous for such inversions as In(1)sc8. Used for balancing sex-linked recessive lethal and sterile mutations. Does not effectively balance cv or v in stocks that are also heterozygous for In(2LR)SM and In(3LR)Ubx130. Different markers have been introduced into FM6; they include w and dm+; the dm+ is probably a duplication introduced by a double crossover in regions 1B3-3C and 4F- 11F2; FM6, dm+ homozygotes are fertile. In addition recessive-lethal-bearing FM6 chromosomes have been described (e.g., Lifschytz and Falk, 1968, Mutat. Res. 6: 235-44). # FM7 constitution: In(1)FM7, y31d sc8 wa B. order: 1A-1B2|20F-20E|15E-20A|15D-11F4|4E1- 11F2|4D7-1B3|20F. properties: Males and homozygous females viable and fertile. An excellent suppressor of recombination with normal-sequence X chromosomes. Commonly used in balancing, even in female fertile versions. variants: version additional markers ref ( comments _____________________________________________________ FM7a vOf 1, 2 FM7b lzsp 2 female sterile FM7c snX2 vOf g4 3, 4 female sterile ( 1 = Merriam, 1968, DIS 43: 64; 2 = Merriam, 1969, DIS 44: 101; 3 = Merriam and Duffy, 1972, DIS 48: 43; 4 = Rob- bins, 1977, Genetics 87: 665-84. # In(1)dl49+BM1 constitution: In(1)dl49+BM1, sc v BM1. order: 1A-4D7|11F2-4E1|11F4-16A2|20D-16A5|20F. properties: Males and homozygous females viable and fertile. Effective suppressor of crossing over in X chromosome. # In(1)sc4Lsc8R+dl49 constitution: In(1)sc4Lsc8R+dl49, y sc4 sc8 wa. order: 1A-1B3|20F-11F4|4E1-11F2|4D7-1B3|20F. references: Gethmann, 1971, Mol. Gen. Genet. 114: 144-55. properties: Effective in suppressing crossing over with X chro- mosome in normal sequence. Deficient for proximal hetero- chromatin, including bb; accordingly X-Y nondisjunction high, and homozygous females lethal. # In(1)sc4Lsc8R+S constitution: In(1)sc4Lsc8R+S, y sc4 sc8 wa B. order: 1A-1B3|20F-11A1|6A3-10F10|6A1-1B3|20F. synonym: S5. references: Lindsley, Edington, and Von Halle, 1960, Genetics 45: 1649-70. properties: Male viable and fertile; homozygous females and X0 males inviable because of deficiency for bb. Suppresses crossing over in X chromosome. Used in recovery of Y- suppressed lethals. # In(1)sc7AM constitution: In(1)sc7+AM, sc7. order: 1A-1B3|6D8-1B4|6D8-8C17|16E2-8D1|16E3-20. properties: Male viable and fertile; homozygous female viable but sterile because of homozygous In(1)AM. Reduces X- chromosome crossing over. May be used to balance sex-linked recessive lethal or sterile mutations. # In(1)sc8+dl49 order: 1A-1B2|20F-11F4|4E1-11F2|4D7-1B3|20F. properties: Effective in eliminating recombination with X chro- mosomes in normal sequence. variants: mnemonic markers ref ( comments _______________________________________________________________ FM0 y31d sc8 w cv vOf m2 v f B 3 FM1 | y31d sc8 wa lzs 1 female sterile M6 y31d sc8 wa vOf f 2 M9 y31d sc8 wa mei9L1 vb v0f f 4 ( 1 = Lewis and Mislove, 1963, DIS 27: 57-58; 2 = Mortin and Lefevre, 1981, Chromosoma 82: 237-47; 3 = Rawls and Porter, 1979, Genetics 93: 143-61; 4 = Schalet (unpublished). | Originally designated complete. # In(1)sc8LscS1R+dl49 constitution: In(1)sc8LscS1R+dl49, y31d sc- vOf f B. order: 1A-1B2|20F-11F4|4E1-11F2|4D7-1B4|20F. synonym: Biny. references: Lindsley and Edington, 1957, DIS 31: 131-32. Lindsley, Edington, and Von Halle, 1960, Genetics 45: 1649- 70. properties: Male lethal owing to deficiency for sc. Suppresses crossing over in the X chromosome. Used in the recovery of Y-suppressed, sex-linked recessive lethals. # In(1)scS1+dl49 order: 1A-1B3|20F-11F4|4E1-11F2|4D7-1B4|20F. properties: Male viable and fertile; homozygous female viable but sterile owing to homozygosity for In(1)scS1. Reduces crossing over in X chromosome. May be used to balance sex- linked lethal or sterile mutations. # In(1)scS1Lsc8R+dl49 constitution: In(1)scS1Lsc8R+dl49, sc8 scS1. order: 1A-1B3|20F-11F4|4E1-11F2|4D7-1B3|20F. properties: Viable and fertile in both males and homozygous females; effective in suppressing crossing over with a normal-sequence X chromosome. Exists with many marker combi- nations, most of which were assembled by Muller. variants: mnemonic markers ref ( comments _________________________________________________ Binsc B Binscy yc4B 4, 5 Binsinscy yc4 w snX2 B 1, 2 female sterile Binsn snX2 B female sterile finscy yc4 vOf f 3 Insc - Inscy yc4 winscy yc4 w ( 1 = Arking, 1975, Genetics 80: 519-37; 2 = Bryant and Zor- netzer, 1973, Genetics 75: 623-37; 3 = Gethmann, 1971, Mol. Gen. Genet. 114: 144-55; 4 = Muller, 1952, DIS 26: 113-14; 5 = Muller and Oster, 1963, Methodology in Basic Genetics (W.J. Burdette, ed.). Holden-Day, Inc., San Francisco, pp. 249-78. # In(1)scS1Lsc8R+S constitution: In(1)scS1Lsc8R+S, sc8 scS1. order: 1A-1B3|20F-11A1|6A3-10F10|6A1-1B3|20F. references: Spencer and Stern, 1948, Genetics 33: 43-74. Baker, 1973, Dev. Biol. 33: 429-40. properties: Males and homozygous females viable and fertile; X0 male poorly viable; variegated for y, ac, cin and presumably for other lethals distal to y. Suppresses crossing over in X, but less so than In(1)scS1Lsc8R+dl49, since In(1)S = In(1)6A1-3;10F10-11A1 is less effective than In(1)dl49 = In(1)4D7-E1;11F2-4. Routinely used in the detection of sex- linked recessive lethals. variants: mnemonic markers ref ( __________________________________ asc wa Basc = M5 wa B 2 Bascy y82 wa B 1 ( 1 = Blount, 1982, DIS 58: 154; 2 = Spencer and Stern, 1948, Genetics 33: 43-74. # Insc: see In(1)scS1Lsc8R+dl49 # Inscy: see In(1)scS1Lsc8R+dl49 # M5: see Basc under In(1)scS1Lsc8R+S # M6: see In(1)sc8+dl49 # M9: see In(1)sc8+dl49 # Muller 5: see Basc under In(1)scS1Lsc8R+S # winscy: see In(1)scS1Lsc8R+dl49 SECOND-CHROMOSOME BALANCERS # CyO: Curly of Oster constitution: In(2LR)O, Cy dplvI pr cn2. order: 21-22D|33F5-30F|50D1-58A4|42A2- 34A1|22D2-30E|50C10-42A3|58B1-60. synthesis: Oster. synonym: Cy, InsO5. references: 1956, DIS 30: 145. O'Donnell, Gerace, Leister, and Sofer, 1975, Genetics 79: 73-83. properties: More effective suppressor of crossing over in chro- mosome 2 than In(2L+2R)Cy; should be superior to SM1 as a balancer for chromosome 2. Other markers introduced into CyO include AdhnA and AdhnB (O'Donnell et al.), l(2)DTS100, l(2)DTS486, and l(2)DTS573 (Falke and Wright, 1972, DIS 48: 89), as well as b, bw, esc2, pk81h, Roi, sple81h, and others. # SM1: Second Multiple 1 constitution: In(2LR)SM1, al2 Cy cn2 sp2. order: 21-22A3|60B-58B1|42A3-58A4|42A2- 34A1|22D2-33F5|22D1-22B1|60C-60F. synthesis: R.F. Grell, 1953. references: Lewis and Mislove, 1953, DIS 27: 58. properties: Homozygous lethal. Viability and fertility of heterozygote excellent. Reliable balancer for all of chromo- some 2, although there is an occasional double crossover in 2R if X and 3 are heterozygous for inversions. MacIntyre and Wright (1966, DIS 41: 141-42) found no recombination between In(2LR)SM1 and al dp b pr cn c px sp in females heterozygous for In(1)sc8 and In(3LR)Ubx130. Nondisjunction of compound autosomes occurs in SM1/+ females [Lindsley and Grell, 1969, Genetics 61 (Supplement): 69-71]; balancer shows interchromo- somal effect (Parry, 1973). #*SM2 constitution: T(2;3)SM2, al2 Cy ltv cn2 sp2. synthesis: R.F. Grell, 1953. references: Lewis and Mislove, 1953, DIS 27: 58. 1954, DIS 28: 77. properties: Not useful as a balancer. # SM5 constitution: In(2LR)SM5, al2 Cy ltv sn2 sp2. Series of over- lapping inversions and transpositions distributed over length of chromosome (Sankaranarayanan, 1974, Mutat. Res. 24: 389- 93). order: 21A-21D2|36C-40F|29D-22D2|34A1- 36C|21D3-22A3|60B-58B1|42A3-42D|42D- 43A|58B1-58F|53C-42D|53C-58A4|42A2- 40F|29E-33F5|22D1-22B1|60C-60F. synthesis: R.F. Grell, 1953. references: Mislove and Lewis, 1955, DIS 29: 75. properties: Homozygous lethal. Heterozygote usually has good viability and fertility, although may not be as good as SM1. Most complete balancer for chromosome 2. # SM6 constitution: In(1)2LR)SM6, al2 Cy dplvI cn2P sp2 combination containing both In(2LR)O and In(2LR)SMI. order: 21-22A3|60B-58B1|42A3-50C10|30E- 22D2|34A1-42A2|58A4-50D1|30F-33F5|22D1- 22B1|60C-60F. synthesis: Craymer. references: 1984, DIS 60: 234-36. properties: Suppresses recombination over entire chromosome 2; carries cn2P, an amorphic derivative of cn2. Two versions: without Roi = SM6a; with Roi = SM6b. THIRD-CHROMOSOME BALANCERS # C(3)x constitution: In(3L)P In(3R)P. (Probably not the same as Payne). # LVM constitution: In(3L)P In(3R)P, l(3)LVML pe l(3)LVMR. properties: Homozygous lethal; suppresses crossing over in chromosome 3. # MKRS constitution: Tp(3;3)MKRS, M(3)76A, kar ry2 Sb. order: 61-71B2|92E-93C|87F1-92E|71C-87E8|93C-100. synthesis: Chovnick. references: 1973, Genetics 76: 289-99. Hilliker, Clark, Chovnick, and Gelbart, 1980, Genetics 95: 95-100. properties: Homozygous lethal. Suppresses crossing over in the proximal regions of both arms of chromosome 3. Version lack- ing kar designated MRS. # TM1: Third Multiple 1 constitution: In(3LR)TM1, Me ri sbdl. order: 61-63|72E1-69E|91C-97D|89B-72E2|63C- 69E|91C-89B|97D-100. synthesis: Lewis. references: 1949, DIS 23: 92. Lewis and Mislove, 1953, DIS 27: 58. Shearn, 1974, Genetics 77: 115-25. properties: Homozygous lethal; suppresses crossing over in chromosome 3. # TM2 constitution: In(3LR)Ubx130, emc2 Ubx130 es. order: 61A|96A-93B|89D-74|61C-74|89E- 93B|96A-100. synthesis: Lewis. references: 1952, Proc Nat. Acad. Sci. USA 38: 953-61. 1952, DIS 26: 66. properties: Homozygous lethal. Eliminates crossing over in chromosome 3 except at the end of the right arm. Does not reliably balance mutations in the vicinity of ca. MacIntyre and Wright (1966, DIS 41: 141-42) observed about 9% double crossing over in the unbroken segment of the left arm from 61C to 74 on the polytene map and 15% recombination between the breakpoint at 96A and ca in In(3LR)Ubx130, Ubx130 e/ru h th st cu sr es Pr ca females that were also heterozygous for an X- chromosome inversion behaving like In(1)sc8 and In(2LR)SM1; no recombination observed in other regions. Some versions also carry pp. # TM3 constitution: In(3LR)TM3, y+ ri pp sep l(3)89Aa bx34e e [not es according to Craymer (1980, DIS 55: 197-200)]. Some TM3 stocks have lost y+ (Shearn, 1980, DIS 55: 167). order: 1A1-1A8|61A2-65E|85E-79E|100C-100F2|92D1-85E|65E- 71C|94D-93A|76C-71C|94F-100C|79E-76C|93A-92E1|100F3-100F5. synthesis: Lewis, 55g. references: Mitchell, 1958, Cold Spring Harbor Symp. Quant. Biol. 23: 279-90. Lewis, 1960, DIS 34: 53-54. Tinderholt, 1960, DIS 34: 53-54. properties: Stocks exist in which Ser or Sb and Ser are present in the balancer, making the TM3 chromosome homozygous lethal. With normal X and 2, all of chromosome 3 is effectively bal- anced; however, in the presence of FM6 and SM5, crossing over between y+ and ri (i.e., 61A2-65E) is appreciable. Double crossovers that separate Sb or Ser from the inversion complex are rare, even in the presence of FM6 and SM5. # TM6 constitution: In(3LR)TM6, HnP ssP88 bx34e UbxP15 e [UbxP15 listed as Ubx67b in CP627 (Craymer, 1980, DIS 55: 197-200)]. order: 61A|89C2-75C|94A-100F2|92D1- 89C4|61A2-63B8|72E1-63B11|72E2-75C|94A- 92E1|100F3-100F5. synthesis: Lewis and Bacher, 66i. references: CP627. properties: Homozygous lethal. Suppresses crossing over in chromosome 3. Has unbroken regions with genetic lengths of approximately 10, 15, 20, and 30 units. # TM6B constitution: In(3LR)TM6B, Hu e. Carries same inversions as TM6 except for substitution of In(3LR)HR33 for In(3LR)P88 and addition of In(3R)Hu. Exists with several marker combina- tions, usually carrying D3 or Tb with various combinations of ca, h, and HnP. order: 61A1|87B2-86C6|84F1-86C5|84B6- 84F1|84B3-75C|94A-100F2|92D1-87B4|61A2- 63B8|72E1-63B11|72E2-75C|94A-92E1|100F3- 100F5. synthesis: Craymer. references: 1984, DIS 60: 234-36. properties: Probably most efficient balancer of chromosome 3. # TM6C constitution: In(3LR)TM6C. Carries same inversions as TM6B except that In(3R)Hu is absent. Exists with various marker combinations (including cu and Sb) in addition to those listed for TM6B. order: 61A1|87B2-75C|94A-100F2|92D1- 87B4|61A2-63B8|72E1-63B11|72E2-75C|94A- 92E1|100F3-100F5. synthesis: Craymer. references: 1984, DIS 60: 234-36. properties: Homozygous viable, although homozygotes show lower viability and longer development time than wild type. Resem- bles TM6B in balancing efficiency except that the absence of In(3R)Hu in TM6C lessens its effectiveness in the centromere region. # TM8 constitution: In(3LR)TM8, l(3)DTS th st Sb e. origin: X ray induced in In(3L)C90 In(3R)C, l(3)DTS4/+. synthesis: Marsh. properties: Effective chromosome 3 balancer that carries dom- inant temperature-sensitive lethal; shows very few viable and fertile escapers from the DTS phenotype. 87C-92D-E not bal- anced (Duncan). # TM9 constitution: In(3LR)TM9, l(3)DTS th st Sb e. origin: X ray induced in In(3L)C90 In(3R)C, l(3)DTS4/+. synthesis: Marsh. properties: Effective chromosome 3 balancer that carries dom- inant temperature-sensitive lethal; shows very few viable and fertile escapers from the DTS phenotype. 87A-92D-E not bal- anced (Duncan). # winscy: see In(1)scS1L sc8R + dl49 # TMS: Third Multiple of Singson constitution: In(3R)87A-B; 97F-98A superimposed on Tp(3;3)MKR5, M(3)76A kar ry2 Sb P(ry+__2-3)99B. order: 61-71B2|92E-93C|87F-92E|71C-87A|97F-93C|87E-87B|98A-100. synthesis: Singson. properties: Useful in maintaining linkage between Sb and A2-3 when passed through heterozygous females. MULTI-CHROMOSOME BALANCERS # AM1: Autosomal Multiple 1 constitution: T(2;3)A1, Cy L Ubx130. Reciprocal translocation between balancers In(2L+2R)Cy and TM2. synonym: A1. synthesis: Wallace, 1966. references: Wallace, Zouras, and Krimbas, 1966, Am. Nat. 100: 245-51. Wallace, 1966, Am. Nat. 100: 565-83. Thompson, 1977, Genetics 85: 125-40. 1983, DIS 59: 129-30. properties: Homozygous lethal. Suppresses crossing over in chromosomes 2 and 3. Recombination on 2 increased in presence of X chromosome balancer, In(1)scS1Lsc8R+dl49 (Thompson).