Gene order in albino region of LGI

Gene order in albino region of LGI Creative Commons License This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. This linkage data is available in Fungal Genetics Reports: http://newprairiepress.org/fgr/vol18/iss1/19 L I N K A G E D A T A Perk ins, D. D. Gene order in the albino The marker arg-6: orginine-6 is usually shown left of 01-Z: alregion of linkage group I. bino-2 in prbm maps. This location was bared larg-n dote with the incompletely albino mutant our: awexent and involved the assumption that al-2 and arg-6 arecontiguous. The data prerented here suggest that this arrumption may be incorrect. arg-6 is almost certainlyright of mand is probably located between al-2 and our. The results in Table I indicate the order ad--l 01-Z erg-6 our hr. (The alternative ad-9 act-l al-2 org-6 hr 3’1 perme b u t l e s s l i k e l y . ) act-I: actidione-I wouldthu~~~e~&gmorker l e f t o f al-Z. Methods: Crosses were made ot 25’C. shocked the tubes. For the first two crosses, arcospons were isnlotcd to agor slants in 75 mm tuber and heatGlycerol complete medium was used in cross 1. Vcgel’r minimal + L-orginine (OS mg/ml ) + DL-homoserine (0.2 mg/ml ) was used in cross 2. Scoring was by transfer to slants of minimal medium plus appropriate rupplementr. Actidione (cycloheximide) war used for testing at IO Pg/ml , with norm01 auto&wing. Tests were unambiguous. Although act-l (Hru 1963 J.Gen.Microbiol.32:341 ) is M)+ 0s close to albino 01 might be desired, it has the advantages of rhowing excsllentility and rcowbility and requiring no supplement. hr: homoserine is also a gocd marker, though caution must be taken to use supplemented minimal medium rather than complete med.& so as to avoid inhibition by unidentified conrtituentr of the latter. q-6 presents no difficulties of culture or scoring. For crosses 3 to 5, wcosporer were suspended, heatshocked and plated in minimal medium containing 1% sorbore + 0.05% glucose + 0.05% fructose, and incubated 48 hwrs at 34’C before colonies were irolrzted to minimal slants. Results: The preferred order, 01-Z left of arg-6, is clear when the least frequent single-crossover class is compared with the do~ossovers, considering three loci at [I time in crosser I and 2, and assuming first one and then the other of the two alternotive orders (0) arg-6 right of 01-2, and (b) arg-6 left of al-Z: Singles Postulated order Parent& Region I R e g i o n 2 Dxbles W a d 9 a l 2 q-6 66 2 4 I 0 (b) m .rg-6= 6 6 2 4 0 I (a) actl a l -2 “‘9-6 359 3 5 6 I (b) act-l q-6 al-2 3 5 9 35 I 6 The order al-2 o&hr was indicated by cross 2 on the basis of 2 singles between al-2 and hr versus 0 doubler. This order was supported by= 3, wh;rre the coupling phase is reversed. Ascorporer were plated ~nimarsabae medium. Of 67 prototrophic prcgeny, 62 were albino. The remaining five isolates (from oh/pi&l slow colonies) developed orange pigment, but all five produced albino progeny when crossed by aIf. They thus originated as pseudowild types or mixtures, and were excluded from the tabulation. Only prototrophr from fast-grzng colonies were isolated in the succeeding &orrer. in 1969(Gene+ics 44, second cross on p. 1194) arg-6 was placed left of our on the basis of a rmoll number of isolates picked visually as prototrophic germinating arcorporer. Theidentical parental rtraa hove been preserved, and were crossed to obtain the results listed under cross 4. Seven+y fort-growing prototrophic colonies were isolated to slants, and only one among them was rejected as an apparent aneuploid that darkened the medium and grew atypically. The 69 bona fide recombinontr were 2, consistent either with the order arg-6 aur hr or argd hs aur, but not with the order our arg-6 hr. Cross 4 results indicate that our is much closer to hs than to arg-6. This was borne out in cross 5, where aur separated from hr in only one prototrphic recomb=“+ among (I total 0-l between erg-6 and hs. The single our-hr recombinZ favors locatingour left rather than right of hr. There results suggest that al-2 and our are separate genes located on opposite cider of erg-6, consistent with what is known both as to recombination and complem~totion between 01-2 and wr. Obviously furtherxol data ore needed. Canfirmotion of the order al-2 arg-6 our would support the proporol of BaG++ e+ al. (1954) that th e our locus be designated al-l: .Ibino-1. The assistance of R. J. Lloyd and R. E. Padilla is appreciated. (Support: PHS Grontr AI 01462 and K6-GM-4899. ) Department of Biological Sciences, Stanford Universi+y, Stanford, California 94305. + + al-2 em-6 36 6 5 1 1 Y154M37 ad-9 ace-l .lY + 29 7 6 0 0 K"52 1 15.4 13.2 1.1 153w ALs4 29997 + + + be 148 8 3 1 1 310 IO,52 2 ace-1 sl-2 arg-6 + 131 15 2 1 0 (78%) 15300 7.7 1.9 0.6 29997 51504 + era-6 + . . . . . . . 0 62 15300 3 al-2 + he . . . . 62 . . protorroph. 29997 (.I1 Q 51504 + + h. . . 69 0 . . 69 29997 arg-6 *UT + . . . . . . . . prOtCltrOph. 34508 4 (all & 51504 ---__----------------------------------------------1959 reeulre: . . 5 3 . . 8 . . . . . . . . praeotroph. (5 & + + e”r he . . . . 60 1 . . 61 15300 5 al-2 arp.-6 + + . . . . . . . . . . prototraph. 29997 (60 ~~,;y”. 34508 51504 (The top number in each 9.W repre.enL. the cLas th.t h., the + allele of the leftmost rmrksr.) ,., ,., .,,.,,,., .,. .,. “., ,,. ,. ,, ,,,, ,,,, ~, ,,.^ ,.~,, I,, ,” ,... ,,,., ,,.. ,,.,,,,,., II,, ”

region of linkage group I. bino-2 in prbm maps. This location was bared larg-n dote with the incompletely albino mutant our: awexent and involved the assumption that al-2 and arg-6 arecontiguous. The data prerented here suggest that this arrumption may be incorrect. arg-6 is almost certainlyright of mand is probably located between al-2 and our. The results in Table I indicate the order ad--l 01-Z erg-6 our hr. -(The alternative ad-9 act-l al-2 org-6 hr 3'1 perme but less likely. ) act-I: actidione-I wouldthu~~~e~&gmorker left of al-Z. ------Methods: Crosses were made ot 25'C. shocked the tubes.
For the first two crosses, arcospons were isnlotcd to agor slants in 75 mm tuber and heat-Glycerol complete medium was used in cross 1. Vcgel'r minimal + L-orginine (OS mg/ml ) + DL-homoserine (0.2 mg/ml ) was used in cross 2. Scoring was by transfer to slants of minimal medium plus appropriate rupplementr. Actidione (cycloheximide) war used for testing at IO Pg/ml , with norm01 auto&wing. Tests were unambiguous.
Although act-l (Hru 1963 J.Gen.Microbiol.32:341 ) is M)+ 0s close to albino 01 might be desired, it has the advantages of rhowing excsllentility and rcowbility and requiring no supplement. hr: homoserine is also a gocd marker, though caution must be taken to use supplemented minimal medium rather than complete med.& so as to avoid inhibition by unidentified conrtituentr of the latter. q-6 presents no difficulties of culture or scoring. -For crosses 3 to 5, wcosporer were suspended, heatshocked and plated in minimal medium containing 1% sorbore + 0.05% glucose + 0.05% fructose, and incubated 48 hwrs at 34'C before colonies were irolrzted to minimal slants. The order al-2 o&hr was indicated by cross 2 on the basis of 2 singles between al-2 and hr versus 0 doubler. This order was supported by= 3, wh;rre the coupling phase is reversed. Ascorporer were plated ~nimarsabae medium. Of 67 prototrophic prcgeny, 62 were albino. The remaining five isolates (from oh/pi&l slow colonies) developed orange pigment, but all five produced albino progeny when crossed by aIf. They thus originated as pseudowild types or mixtures, and were excluded from the tabulation. Only prototrophr from fast-grzng colonies were isolated in the succeeding &orrer.

Results
in 1969(Gene+ics 44, second cross on p. 1194) arg-6 was placed left of our on the basis of a rmoll number of isolates picked visually as prototrophic germinating arcorporer. Theidentical parental rtraa hove been preserved, and were crossed to obtain the results listed under cross 4. Seven+y fort-growing prototrophic colonies were isolated to slants, and only one among them was rejected as an apparent aneuploid that darkened the medium and grew atypically.
The 69 b ona fide recombinontr were 2, consistent either with the order arg-6 aur hr or argd hs aur, but not with the order our arg-6 hr.
---------Cross 4 results indicate that our is much closer to hs than to arg-6. This was borne out in cross 5, where aur separated from hr in only one prototrphic recomb="+ among (I total 0-l between erg-6 and hs. The single our-hr recombinZ favors locatingour left rather than right of hr.
---There results suggest that al-2 and our are separate genes located on opposite cider of erg-6, consistent with what is known both as to recombination and complem~totion between 01-2 and wr.