: COMPOUND CHROMOSOMES Compound chromosomes are monocentric elements in which the material from one chromosome arm is represented twice; they contain the entire diploid complement for the arm involved. They are designated by the symbol C followed parenthetically by the designation of the involved arm. Gametes of compound- bearing flies generally carry two or no doses of the chromo- some arm. Compound-X chromosomes [C(1)'s] exist only in females which, unless special steps are taken, carry a Y chro- mosome. Such C(1)/Y females produce patroclinous sons that inherit the X from their father and the Y from their mother and matroclinous daughters that inherit two X's from their mother and a Y from their father (so-called non-crisscross inheritance). Compound-autosome-bearing flies usually produce no viable progeny unless crossed to flies carrying compounds for the same arm or arms. Some compounds have arisen repeatedly from certain geno- types; they were studied collectively but not as individual occurrences. In other cases, similar compounds of independent origin were studied individually. Both general classes of compounds and compounds of unique origin are listed. The two chromosome arms comprising a compound may join (1) by attachment of the base of one to the terminus of the other to form an acrocentric chromosome or (2) by attachment of both proximally to a single centromere to form a metacentric; the ends of either an acrocentric or a metacentric may join to form a compound ring. In addition, the component arms may be in the same sequence or one may be entirely inverted with respect to the other. Thus, the elements of a compound may pair as a spiral (the tandem configuration) or as a hairpin (the reversed configuration). Simple compounds may therefore be classified according to the conventions of Novitski (1954, Genetics 39: 127-40) as reversed acrocentrics, reversed meta- centrics, reversed rings, tandem acrocentrics, tandem metacen- trics, and tandem rings; where applicable, this classification was retained and is used in the designation of compounds. When the component arms differ in sequence by something other than whole-arm inversion, the classification tandem or reversed becomes ambiguous. Furthermore, when the component arms are separable from each other by a single break, the terms acrocentric and metacentric are descriptive; however, when elements of the two arms become interspersed (as for example by interarm rearrangements), these terms lose meaning. Consequently, the more-complex compounds are given arbitrary symbols. The chromosomal constitution of compounds in which the chro- mosome arms remain intact is designated: metacentrics, by the sequences of the component arms separated by a centerpoint (which represents the centromere); acrocentrics, by the sequence of the distal arm separated by an em dash from the sequence of the proximal arm followed by a centerpoint; rings (which are derived from acrocentrics or metacentrics) by ori- gin. In heterozygotes, the gene content of the component arms is listed according to the same conventions, with the genes on the first arm listed in the chromosomal designation followed by those on the second arm. In homozygotes, the genes are listed in chromosome map order. Complete designation of a compound includes its symbol, its chromosomal constitution, and the gene content of its component arms; e.g., C(1)TM2, + - In(1)sc4LENR, y cv v.sd.y sn g. It should be emphasized that the heterozygous gene content of compounds is often highly unstable owing to homozygosis and changes in coupling rela- tions resulting from exchange. In compounds in which elements of the component arms have become interspersed, it is usually not feasible to designate the chromosomal constitution in terms of the component arms; rather, it is described in terms of the order of chromosome segments as seen in salivary-gland chromosomes. In heterozy- gotes, the gene content is listed in such a way as to indicate which genes were originally in the different component arms. # .=: see C(1)RM # :=: see C(1)DX # 2L: see C(2L)RM # 2R: see C(2R)RM # 3L: see 3(3L)RM # 3R: see C(3R)RM # Attached 2L: see C(2L)RM # Attached 2R: see C(2R)RM # Attached 3L: see C(3L)RM # Attached 3R: see C(3R)RM # Attached-X: see C(1)RM # C(1)94-2A constitution: Homozygous for y; originally heterozygous for cv, sn, v, g, and sd. Ring shaped in mitotic metaphase. Salivary chromosome analysis shows order to be |1A - 5E|1F - 1A.20 - 5E|1F - 20| . origin: Spontaneous (although possibly X ray induced premeioti- cally) derivative of C(1)TR94-2. Apparently arose through an asymmetrical or reversed exchange between the 1F region near the centromere and the 5E region near the interstitial hetero- chromatin of C(1)TR94-2. synthesis: Rosenfeld, 1964. properties: Crossing over in region 1F - 6A produces a single ring carrying In(1)94-2A = In(1)1F-2A;5E-6A. Reversibly con- vertible to other double-ring configurations by other types of exchange (e.g., Novitski and Braver, 1954, Genetics 39: 197- 209). # C(1)A: Compound (1) of Armentrout constitution: Homozygous for y and probably originally hetero- zygous for cv, sn, v, g, and sd. Ring shaped in mitotic meta- phase. Salivary chromosome analysis shows order to be |1A - 6F2 |6F2 - 1A|20 - 7A1|7A1 - 20.|. origin: Spontaneous stable derivative of C(1)TR94, which was originally y cv v sd.y sn g. Apparently arose by a process describable as reversed crossing over in region 6F2 - 7A1. Current versions of this chromosome have apparently opened, since they are no longer ring-shaped in metaphase. Shown to have separated at 13E by Traverse and Pardue (1988, Proc. Nat. Acad. Sci. USA 85: 8116-20) such that the new order is 13E - 7A1| 7A1 - 20.1 - 6F2| 6F2 - 1| 20 - 13E| 13E - 20.1 - 6F2| 6F2 - 1| 20 - 7A1| 7A1 - 13E which are interconvertable by exchange between regions 20 and 13. The newly terminal ends at 13E have acquired moderately repeated sequences (He-T DNA) ordinarily encountered at telomeres and in the chromocenter (Traverse and Pardue). Transmission of C(1)A is reduced owing to the fact that half of meiotic exchanges lead to the produc- tion of dicentric chromosomes. synthesis: Armentrout, 1964. properties: An apparently completely stable, compound-ring-X chromosome; cannot produce single-X chromosome derivative by heterochromatic exchange. Should be the best of all compound-X chromosomes for stock purposes. # C(1)DX: Compound (1) Double X constitution: C(1)DX, In(1)dl-49 - In(1)sc8., y f - y- sc8 f.. origin: X ray induced in In(1)dl-49, y w f/In(1) sc8 sc8 B female [stated by Muller to have been In(1)dl- 49/In(1)sc8Ly3PR, but the derivative does not carry y3P]. Was originally y w f - y- sc8 B., but by double exchange f became homozygous and B was lost. synthesis: Muller. synonym: The symbol :=. references: 1943, DIS 17: 61-62. Valencia, Muller, and Valencia, 1949, DIS 23: 99-102. properties: A reversed acrocentric heterozygous for In(1)dl-49; it is useful in balancing because it is very stable, which is probably due to little interstitial heterochromatin. y w f detachments very rarely produced. Also produces a low incidence of homozygosis for w, and y w f versions exist. C(1)DX/0 lethal; deficient for bb. #*C(1)M2: Compound (1) Multiple constitution: C(1)M2, In(1)sc7+ AM - In(1)FM4., sc7 - y- sc8 dm B.. origin: X-ray-induced exchange between the proximal hetero- chromatin of In(1)sc7 + AM and the distal heterochromatin of In(1)FM4. synthesis: Lewis, 54h. synonym: FMA2: First Multiple Attached. references: 1958, DIS 32: 81. # C(1)M3 constitution: C(1)M3, In(1)AM - In(1)FM4., y2 - y- sc8 dm B.. origin: Recombinant between In(1)sc7 In(1)AM element of C(1)M2 and In(1)AM, y2 in triploid. synthesis: Lewis, 55b. synonym: FMA3. references: 1958, DIS 32: 81-82. properties: Detachment rare; useful in balancing. # C(1)M4 constitution: C(1)M4, In(1)wm4 + AB - FM7., y wm4 - y- wa vOf sc8.. origin: X-ray-induced exchange between the proximal hetero- chromatin of In(1)wm4 + AB and the distal heterochromatin of FM7. synthesis: Craymer, 72e. references: 1974, DIS 51: 21. properties: Because of the wm4/wa constitution, C(1)M4 females without a Y chromosome display strong variegation, those with YS moderate variegation, and those with YL or a complete Y almost no variegation. Useful in maintenance of XY -bearing stocks without a free Y. Detachment rate approximately 1/15,000. A powerful enhancer of autosomal recombination, but has low viability in combination with autosomal rearrange- ments. Some derivatives are y2 bb-. C(1)NB: Compound (1) of Novitski and Braver From Novitski and Braver, 1954, Genetics 39: 197-209. # C(1)NB: Compound (1) of Novitski and Braver constitution: C(1)NB, In(1)dl-49.In(1)sc4LENR; originally y v f car.y m; In(1)dl-49 and In(1)EN attached proximally to a sin- gle centromere. origin: Crossover between the heterochromatic short arm of In(1)EN and the proximal heterochromatin of In(1)dl-49. synthesis: Novitski and Braver. references: 1954, Genetics 39: 197-209 (fig.). properties: Essentially a tandem metacentric heterozygous for In(1)dl-49. Can exist in a number of different configurations interconvertible by crossing over. Generates single rings at different frequencies, depending on configuration of the com- pound. C(1)RA: Compound (1) Reversed Acrocentric Redrawn from Sandler, 1954, Genetics 39: 923-42. # C(1)RA: Compound (1) Reversed Acrocentric constitution: C(1)RA, + - In(1)sc8.. origin: Spontaneous from X.YL/In(1)sc8 either by exchange between the proximal heterochromatin of X.YL and the distal heterochromatin of In(1)sc8, or possibly by sister-strand union in one of the heterochromatic segments followed by a normal euchromatic exchange. A frequently recurring event that seems to require the presence of YL. More recent attempts to repeat such constructions have been unsuccessful, except in response to x irradiation. synthesis: Novitski. synonym: RA. references: Novitski, 1954, Genetics 39: 127-40. Sandler, 1954, Genetics 39: 923-42. 1958, Cold Spring Harbor Symp. Quant. Biol. 23: 211-23. Sandler and O'Tousa, 1979, Genetics 91: 537-51. properties: Yields frequent detachments resulting from exchange between the Y chromosome and the interstitial heterochromatin of the reversed acrocentric and preferential recovery of the proximal X. Tetrad distribution usually quite abnormal; one- exchange tetrads infrequent and no- and two-exchange tetrads frequent. Exchange frequency increased by addition of Y or y+YL, but tetrad distribution remains abnormal (Sandler, 1954). YL appended as a second arm to C(1)RA normalizes tetrad distribution (Sandler, 1958). Tetrad distribution is normal in more recently recovered C(1)RA chromosomes (Sandler and O'Tousa), reason for differences between 1954 and 1979 data is unclear. The presence of a Y chromosome or a free-X duplication as a homologue markedly increases both exchange between the elements of the compound and fecundity of compound-bearing females. # C(1)RA60g constitution: C(1)RA60g, + - In(1)sc8. origin: A spontaneous euchromatic event (perhaps sister chroma- tid union) in a triploid female heterozygous for In(1)sc8 + dl49. synthesis: Mohler, 60g. references: 1960, DIS 34: 52. Gethmann, 1979, Genetics 55: 673-79. properties: Deficient for interstitial heterochromatin and proximal euchromatin, including su(f). Requires a duplication carrying both su(f)+ and bb+ in order to survive. Exhibits standard distribution of tetrads in meiosis (Gethmann). other information: The reciprocal exchange product, Dp(1;f)60g, recovered from same fly. # C(1)RA85 constitution: C(1)RA85, y w1118 f5- In(1)scS1L sc8R +S, y- sc8 wr f5. origin: Spontaneous exchange between the proximal heterochromatin of y w1118 f5 and the distally inverted heterochromatin of Basc, with subsequent loss of B and homozy- gosis of f5. references: Mount, Green, and Rubin, 1988, Genetics 118: 221- 34. properties: A stable compound X chromosome. # C(1)RM: Compound (1) Reversed Metacentric constitution: C(1)RM, +.+; two X chromosomes in normal sequence attached proximally to the same centromere; exists with many combinations of markers. origin: Spontaneous. Recurs regularly by exchange between heterochromatin of the short arm of one X, XYS, or XYL and that of the base of the long arm of a sister or homolog. Can be induced in mature X.YL -bearing sperm (Leigh, 1972, DIS 48: 107). Presumably the pericentric heterochromatic consti- tutions of independently arising C(1)RM chromosomes varies. discoverer: L. V. Morgan, 21b12. synonym: Attached-X; also the symbol .=. references: 1922, Biol. Bull. 42: 267-74. 1938, Am. Naturalist 72: 434-46. properties: Recombination with the Y chromosome leads to detachments with a frequency of about 10-3 in C(1)RM/Y females. Has been extensively used in studies of crossing over (e.g., Anderson, 1925, Genetics 10: 403-17; Beadle and Emerson, 1935, Genetics 20: 192-206; Welshons, 1955, Genetics 40: 918-36). #*C(1)RR1: Compound (1) Reversed Ring constitution: C(1)RR1, + - In(1)EN, y- sc- - y; two X chromo- somes attached by their normally distal ends to a common cen- tromere and by their normally proximal ends to each other. Marked with y. origin: Spontaneous derivative of C(1)TR1. synthesis: Zimmering. synonym: RR. references: Novitski, 1954, Genetics 39: 127-40. #*C(1)RR2 constitution: C(1)RR2, In(1)sc8.In(1)scS1LENR; originally y- cv v f.y m car. In(1)sc8 and In(1)scS1LENR attached proximally to a single centromere and distally at their distal hetero- chromatic segments. origin: X ray induced in an attached-X with In(1)sc8 and In(1)scS1LENR attached proximally to a single centromere. Recovered as simultaneous loss of y+ from the tip of both arms. synthesis: Sandler. references: 1957, Genetics 42: 764-82 (fig.). 1958, Cold Spring Harbor Symp. Quant. Biol. 23: 211-23. properties: Tetrad distribution abnormal; one-exchange tetrads are infrequent and no- and two-exchange tetrads are frequent. Exchange frequency increased by addition of Y or y+YL, but tetrad distribution remains abnormal. C(1)RR2: Compound (1) Reversed Ring 2 From Sandler, 1957, Genetics 42: 764-82. # C(1)RR94-2F constitution: C(1)RR94-2F, +.+; two X chromosomes of normal sequence attached proximally to a single centromere and joined distally by a segment of heterochromatin. origin: X-ray-induced derivative of C(1)TR94. synthesis: Rosenfeld, 1964. references: Sandler, 1965, Nat. Cancer Inst. Monograph No. 18: 243-72. properties: Tetrad distribution more nearly normal than in C(1)RR2. # C(1)SB: Compound (1) of Sturtevant and Beadle constitution: C(1)SB, + .In(1)y4; In(1)y4 and a normal sequence attached proximally to a single centromere. origin: Recombinant between the uninverted portion of In(1)y4 and C(1)RM in a triploid. synthesis: Sturtevant and Beadle. references: 1936, Genetics 21: 554-604. Novitski and Sandler, 1956, Genetics 41: 194-206. properties: A reversed metacentric heterozygous for In(1)y4. Meiotic behavior similar to that of a tandem metacentric. Crossing over within inversion generates single ring, R(1)y4. #*C(1)TA1: Compound (1) Tandem Acrocentric constitution: C(1)TA1, In(1)sc4 - In(1)EN.YL, y sc4 - y.. origin: X-ray-induced exchange between the proximal hetero- chromatin of In(1)sc4 and YS of YSX.YL. synthesis: Novitski. synonym: TA. references: 1954, Genetics 39: 127-40. properties: Produces a single, centric, rod-X chromosome and either an acentric, ring-X or a tandem triple-X chromosome by recombination between the proximal and distal X chromosomes. C(1)TA2: Compound (1) Tandem Acrocentric 2 From Sandler and Lindsley, 1963, Genetics 48: 1533-43. # C(1)TA2 constitution: C(1)TA2, + - +.; originally y cv f - y f.. origin: X-ray-induced recombinant in YSX, y+ KS y cv v f/XYL, y car KL female; origin required triple exchange. synthesis: Sandler and Lindsley. references: 1963, Genetics 48: 1533-43 (fig.). properties: Generates single X chromosomes like C(1)TA1. Tetrad distribution about normal. C(1)TA2/0 lethal, probably deficient for bb. # C(1)TA.YL constitution: C(1)TA.YL, + - +., y - y.KL; original line segre- gating for cv, v, f, and car. origin: Spontaneous in a X.YS, In(1)sc8LENR, y+ y/X.YL, y cv v f car; thought to result from an euchromatic exchange between the X.YL chromosome and the acentric ring formed by dyscentric exchange between the distal and proximal heterochromatin of the long arm of X.YS, In(1)sc8LENR. references: Merriam, 1968, Genetics 59: 351-66. # C(1)TA.scV1 constitution: C(1)TA.scV1, + - +., y - y.scV1 y+. origin: Derived as a recombinant in the B - car region between C(1)TA.YL and the XP4D element of T(1;4)BSLIn(1LR)scV1R, BS car.scV1 y+. references: Merriam, 1968, Genetics 59: 351-66. # C(1)TM1: Compound (1) Tandem Metacentric constitution: C(1)TM1, +.In(1)sc8LENR, y Hw f.y+ y f; a normal sequence and In(1)EN attached proximally to a single cen- tromere derived from R(1)2. origin: Product of one crossover between + and R(1)2 and one between In(1)EN and R(1)2 in a +/R(1)2/In(1)EN triploid. synthesis: Novitski, 1950. references: Novitski and Lindsley, 1950, DIS 24: 90-91. properties: Single crossover between the arms produces single- ring-X chromosome with the same structure as R(1)2 and an acentric-rod X chromosome. Tetrad distribution about normal (Novitski, 1951, Genetics 36: 267-80; Novitski and Sandler, 1956, Genetics 41: 194-206. # C(1)TM2 constitution: C(1)TM2, +.In(1)sc4LENR; originally y cv v sd.y sn g. The sequence in mitotic prophase is: the normal X euchromatin, two large heterochromatic segments, a small seg- ment, the centromere, a small segment, the inverted X euchromatin. origin: X-ray-induced exchange between the proximal hetero- chromatin of a normal X and YL of X.YL, In(1)sc4LENR. synthesis: Lindsley and Sandler, 1963. synonym: TMX y. references: 1965, Genetics 51: 223-45 (fig.). properties: Recombination between the arms produces a single- ring-X chromosome and an acentric, rod-X chromosome. Meiotic behavior similar to that of C(1)TM1; tetrad distribution about normal. # C(1)TM5 constitution: C(1)TM5, YSIn(1)EN.+; originally y w v B KS.y. origin: X ray induced in YSX.YL, In(1)EN, y w v f B/XYL.YS, y .y+ females. synthesis: Lucchesi, Mills, and Rosenbleeth. references: 1965, DIS 40: 57-58. Pasztor, 1967, DIS 42: 107. Pasztor, 1971, Genetics 68: 245-58. properties: Single exchange generates highly unstable single ring chromosomes as seen by very low recovery of ring-bearing daughters and by 16-46% gynandromorphs among single-ring- bearing progeny. Single rings apparently deficient for proxi- mal euchromatic material, as they are male-lethal in combina- tion with a normal Y but survive in combination with BSY or su(f)+Y. # C(1)TM-H: Compound (1) Tandem Metacentric of Hinton constitution: C(1)TM-H, In(1)sc4LR(1)2R [.In(1)wvC] + dl49; position of centromere indeterminate. origin: Generated by exchange between the BS duplication of Dp(1;1)BS-H and In(1)dl49. references: Hinton, 1957, Genetics 42: 55-65. proberties: These are linear derivatives of the unstable R(1)2, In(1)wvC. They exhibit variable stability as indicated by (a) their reduced recovery among the progeny C(1)TM-H -bearing mothers, (b) the production of X0 patroclinous sons, and (c) the instability of single rings produced by single exchange between the arms of the tandem metacentric. C(1)TM2: Compound (1) Tandem Metacentric 2 From Lindsley and Sandler, 1965, Genetics 51: 223-45. # C(1)TMBS9-1: Compound (1) Tandem Metacentric with Bar Stone constitution: C(1)TMBS9-1, Dp(1;1)BSTAG.In(1)sc8L ENR; origi- nally BS y cv v sd.y sn g. The sequence in mitotic prophase is: the normal X euchromatin, two large heterochromatic seg- ments, a small segment, the centromere, a small segment, the inverted X euchromatin. origin: X-ray-induced exchange between the proximal hetero- chromatin of Dp(1;1)BSTAG and YL of X.YL, In(1)sc8LENR. synthesis: Lindsley and Sandler, 1963. synonym: TMXBS 9-1; also designated as Dp(1;1)BSTRG. references: 1965, Genetics 51: 223-45. properties: Recombination between the arms produces a single- ring-X chromosome, R(1)9-1, and an acentric, rod-X chromosome. Recombination between the BS duplication and the homologous region of the inverted arm generates a nontransmissible tandem-ring chromosome. Meiotic behavior similar to that of C(1)TM2. # C(1)TMBS9-4 constitution: C(1)TMBS9-4, Dp(1;1)BSTAG.In(1)sc8L ENR; origi- nally BS y cv v sd.y sn g. The sequence in mitotic prophase is: the normal X euchromatin, a large heterochromatic seg- ment, a small segment, the centromere, a small segment, the inverted X euchromatin. origin: X-ray-induced exchange between the proximal hetero- chromatin of Dp(1;1)BSTAG and YL of X.YL, In(1)sc8LENR. synthesis: Lindsley and Sandler, 1963. synonym: TMXBS9-4; also designated as Dp(1;1)BSTRG. references: 1965, Genetics 51: 223-45 (fig.). properties: Recombination between arms produces single-ring-X chromosome, R(1)9-4, and an acentric, rod-X chromosome. Recombination between the BS duplication and the homologous region of the inverted arm produces a tandem-ring chromosome that may be transmissible. C(1)TMBS: Compound (1) Tandem Metacentric with Bar-Stone From Lindsley and Sandler, 1965, Genetics 51: 223-45. #*C(1)TR1: Compound (1) Tandem Ring constitution: C(1)TR1, In(1)sc4 - In(1)EN., y- sc- - y.. origin: Spontaneous derivative of C(1)TA1 in which the YL second arm had been replaced by the XP4D element of T(1;4)BS = T(1;4)15F9-16A1;16A7-B1;102F. A product of recombination between the duplicated BS second arm and the homologous region of the distal element of the tandem acrocentric. synthesis: Novitski. references: 1954, Genetics 39: 127-40. properties: Seems to be poorly transmissible (Novitski, 1954). Produces a centric, single-ring-X and either an acentric, single-ring-X or a tandem, triple-ring-X chromosome by recom- bination between the two elements of the compound. C(1)TR94: Compound (1) Tandem Ring 94 From Sandler and Lindsley, 1967, Genetics 55: 645-71. # C(1)TR94 constitution: C(1)TR94, +.In(1)sc4LENR.; originally y cv v sd.y sn g. origin: Regular but infrequent product of C(1)TMBS9-4. Formed by exchange between the duplicated BS section and the homolo- gous region of the inverted arm. synthesis: Sandler and Lindsley. references: 1967, Genetics 55: 645-71. properties: Produces a centric, single-ring-X and either an acentric, single-ring-X or a tandem, triple-ring-X chromosome by crossing over between the two arms of the compound. Transmission higher than that of C(1)TR1. Tetrad distribution about normal. Exhibits < 0.20% dicentric quadruple rings in mitotic metaphases (Gatti, Santini, Pimpinelli, and Olivieri, 1979, Genetics 91: 255-74). #*C(1)VM: Compound (1) of Valencia and Muller constitution: C(1)VM, + - In(1)scS1 In(1)dl-49.; originally y ac sc pn w rb cm ct6 sn3 oc ras2 v dy g f car - y scS1 lzs B.. origin: X ray induced in +/In(1)scS1 In(1)dl-49/YL female, either by exchange between the proximal heterochromatin of the normal sequence and the distal heterochromatin of In(1)scS1 or by sister-strand union in one of the heterochromatic elements accompanied by normal euchromatic exchange. A regularly induced product in such females. synthesis: Valencia, Muller, and Valencia. references: 1949, DIS 23: 99-102. properties: Essentially a reversed acrocentric in which the proximal element contains In(1)dl-49. Detachment by crossing over with a Y chromosome relatively frequent. # C(2)EN: Compound (2) ENtire constitution: C(2)EN, 2R2L - 2L2R. origin: Synthesized by first selecting a T(Y;2) with a break in YL of BSYy+ and an absolutely terminal break in 2L, and next transferring the terminal YL to C(2L)RM by recombination in a Dp(Y;2)/C(2L)RM/C(2R)RM triploid; the terminal YL was homozy- gosed to produce C(2LYL)RM, BS. Irradiated C(2LYL)RM, BS/C(2R) females were crossed to C(2L); F(2R)/F(2R) males; this cross selects for progeny that receive C(2LYL)RM, BS plus a single copy of 2R from their mothers; those with wider Bar eyes are putative results of a translocation between the base of 2R from C(2R)RM and a terminal YL of C(2LYL)RM and the sur- viving offspring are YL2L.2L2R/F(2R); crosses of females of this constitution to C(2L)RM; C(2R)RM have yielded C(2)EN- bearing progeny as a consequence of fertilization of an ovum that has received a derivative homozygous (non BS) for the 2L2R arm of the compound and no F(2R) by a nullo-2 sperm. In situ hybridization with a telomeric probe reveals the presence of telomeric sequences at the junction between 2L and 2R (Goldstein, Berry, and Novitski, 1984, DIS 60: 117). references: Novitski, 1977, Genetics and Biology of Drosophila (Ashburner and Novitski, eds.). Academic Press, London, New York, San Francisco, Vol. 1b, pp. 562-68. Novitski, Grace and Strommen, 1981, Genetics 98: 257-73. properties: Provides all of chromosome 2 necessary for normal development. C(2)EN-bearing flies produce two types of meiotic products with respect to chromosome 2; half disomic and half nullosomic. Accordingly crosses to normal diploids produce mainly inviable mono- and triplo-2 zygotes; however crosses of C(2)EN flies to each other produce progeny. Transmission of C(2)EN by males versus that from females varies from about 30% to very low values (see also Robbins, 1977, Genetics 87: 67- 81). This is attributed to zygote mortality by Novitski et al.; however, it may be reflected in defects in spermato- genesis as seen in cross sections of bundles of elongated sperm tails. Male transmission ratio is sensitive to the par- ticular Y chromosome present (Strommen, 1982, Mol. Gen. Genet. 187: 126-31). Sex-chromosome disjunction in both sexes influenced by C(2)EN (Falk, 1982, Genet. Res. 41: 17-28); in XY/0 males the XY segregates preferentially from the compound; in X/Y males and X/X females, sex chromosome nondisjunction is elevated with the sex chromosomes segregating preferentially away from C(2)EN. In general, C(2)EN -bearing flies perform poorly in stocks and crosses. # C(2;3)EN: Compound (2;3) ENtire constitution: C(2;3)EN, 2R2L.3L3R. origin: Induced by irradiation of C(2)EN; 3R3L.YSy+ females. Recovered as a translocation involving the centric hetero- chromatin of both elements resulting in the replacement of one arm of C(2)EN with 3R3L. references: Novitski, Grace and Strommen, 1981, Genetics 98: 257-73. properties: Carries a complete haploid set of the large auto- somes attached to a single centromere. Transmission by heterozygous females is reduced by nonrandom disjunction of heteromorphic dyads resulting from exchange between the com- pound and a normal homologue, but it is high if recombination is suppressed by homologous inversions. Transmission by heterozygous males is low. Homozygous viability and fertility not indicated. # C(3)EN: Compound (3) ENtire constitution: C(3)EN, 3R3L.3L3R. origin: Synthesized by first selecting a T(Y;3) with a break in YL of BSYy+ and an absolutely terminal break in 3L. Females heterozygous for BSYL3L.3R and a normal third chromosome were irradiated and crossed to F(3L)/F(3L)/C(3R)RM males; one of the few surviving products of this cross is non-Bar and comes from fertilization of an ovum containing a half translocation between the base of 3R of the normal third and the distal YL material of the Dp(Y;3) fertilized by a sperm containing F(3L) but no C(3R); the F(3L) in this case was the YP3LD of a T(Y;3) involving breaks in YL of BSYy+ and the proximal heterochroma- tin of 3L, so that the desired survivor is 3R.3L3R/y+YS.3L in constitution. One product of recombination between 3L's in females of the above constitution is y+YS.3L3R. Females homozygous for the latter derivative were irradiated and crossed to C(3L)RM; C(3R)RM males; surviving y offspring car- ried 3R3L.3L3R = C(3)EN from the mother and no third chromo- somal elements from the father. In situ hybridization with telomeric sequences provides no evidence for the presence of such sequences at the 3L - 3R junction (Goldstein, Barry and Novitski, 1984 DIS 60: 117). references: Novitski, Grace and Strommen, 1981, Genetics 98: 257-73. properties: Provides all of chromosome 3 necessary for normal development. C(3)EN-bearing flies produce two types of meiotic products with respect to chromosome 3: half disomic and half nullosomic; accordingly crosses to normal diploids produce only inviable mono- and triplo-3 zygotes; however crosses of C(3)EN flies to each other produce progeny. Transmission of C(3)EN by males versus that from females varies widely depend- ing on the particular isolations tested, from 40% relative maternal transmission in some crosses through equal recovery in others, to 30% relative paternal transmission in yet oth- ers. In general these chromosomes perform poorly in stocks and crosses. # C(4)RM constitution: 4.4; exists with various marker combinations. Two right arms of chromosome 4 attached proximally to a single centromere. origin: X ray induced. synonym: E. B. Lewis. properties: Produces haplo-4 and triplo-4 progeny in crosses to normal diplo-4 flies. Tetra-4 flies carrying two copies of C(4)RM exhibit but slightly reduced viability (Grell, 1972, DIS 48: 69). Segregates quasi regularly from C(1)RM in C(1)RM/0; C(4)RM/0 females (Grell, 1963, Genetics 48: 1217- 29). # C(A): Compound (Autosomal arm) Autosomal compound chromosomes may be subdivided into two classes, homocompounds, consisting of two copies of the same autosomal arm attached to a common centromere, and heterocom- pounds in which two arms from different autosomes are con- nected through the centromere of one of them. These are dis- cussed separately in the following section. Homocompounds: Compound chromosomes containing two copies of an autosomal arm [C(A)] have been constructed for each auto- somal arm, as reversed metacentrics in every case so far. The compound for a particular autosomal arm may be kept in stock either with the compound for the other arm of the same auto- some [e.g., C(AL); C(AR)] or with free arms [e.g., C(AL); F(AR)/F(AR)]. Most compound autosome stocks are of the former constitution; outcrosses to wild type are virtually sterile, the rare survivors being triploids, triploid intersexes, and triploid metafemales (4X3A) thought to arise from unreduced ova (Gethmann, 1972, DIS 49: 62) or products of tetraploid oocytes (Kuznetsova and Glotoff, 1978, Genetika 14: 463-69; Kuznetsova and Balakireva, 1980, Genetika 16: 1498-1500; Kuz- tenova, 1983, Genetika 19: 775-78); in addition some diploid survivors contain reconstituted 2L.2R chromosomes. Stocks of the second type are similarly unproductive when outcrossed to wild type; rare survivors carry detachments of the C(A) resulting from exchange between the base of the compound auto- some and either the Y or the X chromosome (Chadov, 1975, Genetika 11(1): 80-90; 91-100; 1976, Genetika 12(3): 67-77; Chadov and Chadova, 1977, Genetika 13: 477-89; Chadov, Cha- dova and Khostina, 1983, Genetika 19: 1111-20). Once the first C(2L); C(2R) and C(3L); C(3R) strains were constructed (Rasmussen, 1960, DIS 34: 53), it became possible to generate additional compound chromosomes, either spontaneously or by irradiation of normal chromosome complements and by crossing to a compound-autosome-containing line to recover them in com- bination with a compound for the complementary arm. Compound autosomal arms result from interchanges involving breaks on opposite sides of the centromere of two chromosomes, either homologues or sisters. The resultant chromosomes have an intact autosomal arm on one side of the centromere and a prox- imal segment of the other arm on the other side to which is attached the distal majority of the first arm from the sister chromatid or the homologous chromosome. Thus compound arms carry two doses of the majority of the arm but only one dose of a proximal segment of variable length, plus a proximal seg- ment of the opposite arm. New compounds may be induced by irradiation of oocytes (Bateman, 1968, Effects of Irradiation on Meiotic Systems, International Atomic Energy Agency, Vienna, pp. 63-70) and in spermatocytes and spermatids (Leigh and Sobels, 1970, Mutat. Res. 10: 475-87). Compound auto- somes with desired marker constitutions may be achieved by recombination in triploids or by inducing them anew in appropriately marked diploids; since the latter is the pre- ferred method, most different marker combinations represent independent occurrences, and are so considered in the follow- ing table. Reconstitution of AL.AR from C(AL); C(AR), either induced or spontaneous, generates chromosomes that may be duplicated or deficient for regions adjacent to the cen- tromere; these have been used to investigate the genetic con- tent of pericentric regions (Baldwin and Suzuki, 1971, Mutat. Res. 11: 203-13; Hilliker and Holm, 1975, Genetics 81: 705- 21). In otherwise normal genotypes C(AL) and C(AR) segregate from one another regularly in females (Grell, 1970, Genetics 65: 65-74; Holm and Chovnick, 1975, Genetics 81: 293-311); in males they segregate at random with respect to one another (Hilliker, 1981, DIS 56: 61-62; Holm and Chovnick, 1975), generating a trimodal distribution of mature sperm-head volumes; chromosome loss is indicated by the presence of micronuclei in spermatids (Hardy, 1975, Genetics 79: 231-64). Regular segregation in females can be upset by the addition of heterologous inversions or by the addition of an extra Y chro- mosome or an attached X (Grell, 1970), compounds that carry only heterochromatic material from the opposite arm segregate randomly in males, whereas those that contain euchromatic material from the opposite tend to segregate from the comple- mentary compound. The table below lists a selection of com- pound autosomal arms that have been characterized or refer- enced in some way. compound ( ref | comments __________________________________________________________________________ C(2L)CN10 14 complex contains Y fertility genes and bw+ and sp+ from 2R C(2L)RM-P, dp 5 = C(2L)#4? C(2L)RM, b pr 13 C(2L)RM, j 13 C(2L)RM-P, b 13 C(2L)RM-SD72 9, 10 21 - 40F.41A - 42A10|39D3 - 21; induced in In(2LR)SD72; -> 80% segregation from C(2R)RM-SD72 in males C(2L)RM-SH1 7, 10 carries rl+ from 2R; segregates ran- domly in males C(2L)RM-SH3, + 7, 10 C(2L)RM-VH1, lt 7 carries rl+ from 2R; segregates ran- domly in males C(2L)RM-VH2, lt C(2L)RM-VT1, ho C(2R)RM-P, px 3, 5, 13 not duplicated for lt, same as C(2L)RM#4? C(2R)RM, + C(2R)RM, bw C(2R)RM, bw 3 C(2R)RM, cn 3, 13, 15 60F - 41A.40F - 39|41A - 60F; segregates regularly from C(2L) in males C(2R)RM, stw bw 13 C(2R)RM, vg 13 C(2R)RM-P, px 3 Same as C(2R)RM#4? C(2R)RM-SD72 9, 10 60F - 42A14|39D4 - 40F.41A-60F; induced in In(2LR)SD72; -> 80% segregation from C(2L)RM-SD72 in males = C(2R)RM-V43 C(2R)RM-SH1, + 7, 10 C(2R)RM-SH3, + 7, 10 C(2R)RM-VHK1, rl cn 8 C(2R)RM-VK1, bw 14 C(2R)RM-VK2, bw 7 carries lt+ from 2R; segregates randomly in males C(3L)RM-P2, ri 11 C(3L)RM-P5 12 originally In(3L)P/ve h th C(3L)RM, h2 5, 13 C(3L)RM, se h rs2 5 C(3L)RM-SH2, + 12 C(3L)RM-SH3, + 12 C(3L)RM-VG1, ru st 4 C(3L)RM-VH3, st C(3R)RM, + 5 C(3R)RM, sbd2 gl e2 5, 13 C(3R)RM-P2, sr 2 C(3R)RM-P5, sbd2 gl es 12 C(3R)RM-SB1, pp gl3 11 C(3R)RM-SC1, kar ry C(3R)RM-SH3, + C(3R)RM-SH3, ry2 1 C(3R)RM-SH4a 12 originally In(3R)C sb e l(3)e/ca K-pn C(3R)RM-SH4b, ca K-pn 12 C(3R)RM-SH19, + C(3R)RM-SH20, + 12 C(3R)RM-SH21 12 C(3R)RM-SHK16 1 originally kar2 ry406 piclG23/ry+10 Acel26; used in half-tetrad analysis or ry fine structure C(3R)RM-SK2 12 originally pp ss es/cu gl C(3R)RM-VC1, es 4 C(3R)RM-VK1, es C(3R)RM-VT2, cu 6 ( In these designations the laboratory of origin is indicated by P = Pasadena, S = Storrs and V = Vancouver. The investi- gator by B = Baldwin, C = Chovnick, G = Garvin, H = Holm, HK = Hilliker, K = Kiceniuk, and T = Tabatabaie-Harger. | 1 = Clark, Daniels, Rushlow and Hilliker, 1984, Genetics 108: 953-68; 2 = Evans, 1971 DIS 46: 123-24; 3 = Gethmann, 1976, Genetics 83: 743-51; 4 = Gosh and Mukherjee, 1986, DIS 63: 59-60; 5 = Hardy, 1975, Genetics 79: 231-64; 6 = Harger and Holm, 1980, Genetics 96: 455-70; 7 = Hilliker, 1981, DIS 56: 61-62; 8 = Hilliker, Gibson, Yeomans and Holm, 1977, DIS 52: 32; 9 = Hilliker, Holm and Appels, 1982, Genet. Res. 39: 157-68; 10 = Holm, 1983, DIS 59: 56-59; 11 = Holm, Baldwin, Duck and Chovnick, 1973, DIS 44: 112; 12 = Holm and Chovnick, 1975, Genetics 81: 293- 311; 13 = Leigh and Sobels, 1970, Mutat. Res. 10: 475-87; 14 = Nishimura and Gethmann, 1983, Genetics 104: 545; 15 = Sandler, Lindsley, Nicoletti, and Trippa, 1969, Genetics 60: 525-58. Heterocompounds: Four types of heterocompounds are possible: C(2L . 3L), C(2L . 3R), C(2R . 3L), and C(2R . 3R); the chro- mosomal origin of the centromere in such compounds is fre- quently ambiguous. Pairs of these are produced as the com- ponents of 2-3 translocations in which both breakpoints are in the pericentric heterochromatin, e.g., C(2L . 3L); C(2R . 3R), and they may be carried together as translocations in either the homozygous or heterozygous condition. Pairs from two dif- ferent translocations, which have one autosomal arm in common can be carried in combination with a normal chromosome and a homocompound for the missing arm. The two heterocompounds and the normal compound form a tricomplex; tricomplexes are chro- mosome constitutions that form a triradial synaptic configura- tion, involving three entire autosomal arms rather than four as seen in reciprocal-translocation heterozygotes. They are maintained in stock in combination with a compound for the fourth autosomal arm. For example, a triradial synaptic con- figuration is formed in the constitution C(2L . 3L)/3L . 3R/C(3R . 2L), and it can be maintained in the presence of C(2R). Alternatively a heterocompound may be carried in homozygous condition in combination with homocompounds for the missing arms, e.g., C(2L); C(2R . 3L)/C(2R . 3L); C(3R). New heterocompounds may be induced by crossing irradiated females to heterocompound-bearing males that can generate the comple- mentary gametic types (Parker, 1968, Effects of Radiation on Meiotic Systems, International Atomic Energy Agency, Vienna, pp. 209-18; Puro, 1985, Genet. Res. 46: 287-307). Puro (1973, Hereditas 75: 140-43; 1985, Genet. Res. 46: 287-307) used T(2;3)N2-29 and T(2;3)N2-46, which he determined to be 2L . 3L; 2R . 3R and 2L . 3R; 2R . 3L respectively, to generate all four types of tricomplex and to characterize their meiotic behaviors. Such tricomplex-bearing flies are produced by crossing T(2;3)N2-29/T(2;3)N2-46 females to C(2L); C(2R) or C(3L);C(3R) males. In addition to the heterocompounds recovered from the above two translocations he recovered and characterized C(2R . 3R)HT10 and C(2L . 3R)HT26 from irradi- ated females. # First Multiple Attached: see C(1)M # FMA: see C(1)M # RA: see C(1)RA # RR: see C(1)RR # TA: see C(1)TA # TMXBS: see C(1)TMBS