Kansas State University

Genetic basis for an aberrant ascus in N. crass

Srb, A. M.

Fungal Genetics Reports 
Volume 1 Article 6 
Genetic basis for an aberrant ascus in N. crassa 
A. M. Srb 
Follow this and additional works at: https://newprairiepress.org/fgr 
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. 
Recommended Citation 
Srb, A. M. (1962) "Genetic basis for an aberrant ascus in N. crassa," Fungal Genetics Reports: Vol. 1, 
Article 6. https://doi.org/10.4148/1941-4765.1020 
This Research Note is brought to you for free and open access by New Prairie Press. It has been accepted for 
inclusion in Fungal Genetics Reports by an authorized administrator of New Prairie Press. For more information, 
please contact cads@k-state.edu. 
Genetic basis for an aberrant ascus in N. crassa 
Abstract 
Genetic basis for an aberrant ascus in N. crassa 
This research note is available in Fungal Genetics Reports: https://newprairiepress.org/fgr/vol1/iss1/6 
proportion of mosaics among mutations decreased from nitrous acid (77-87%) to UV (40%) to 
x-rays (28%). A substantial proportion of the X-ray induced mosaics and a smaller propor- 
tion of those induced by the other mutagens may have been derived from conidia with more than 
1 amycelial nucleus (only lethals induced in such nuclei are detected). The excess of 
mosaicism, especially after treatment with nitrous acid, is attributed either to segregation 
of mutated and non-mutated strands in the treated chromosome or to delayed mutation. In most 
mosaics, and independent of the mutagen, the lethal sector was much smaller than one half; 
sectors comprising 20% or less formed between 70 and 78%. Possible reasons for this are 
being examined. 
Srb, Adrian M. Genetic basis for an 
aberrant ascus in N. crassa. 
J. C. Murray and Adrian M. Srb have reported a 
gene, peak (pk), that appears to act as a re- 
cessive to its wild allele in determination of 
aberrant asci characterized by nonlinear spore arrangements (Proceedings IX International 
Botanical Congress). That is, when zygotes are +/+ or +/& normal asci are formed, but I& 
& zygotes give aberrant asci. The interpretation might have been strengthened or altered 
had reciprocal crosses been possible between wild and p-ak strains. Although e& is 
clearly a gene mapable on linkage group 5 and is not an extrachromosomal factor, the possi- 
bility remained that protoperithecia homocaryotic for peak would give aberrant asci irre- 
spective of the genotype of a conidial parent. More recently conditions have been found 
under which peak strains produce both protoperithecia and conidia, and reciprocal crosses 
between wild and peak have been made. The wild strains were the standard St. Lawrence 
strains 74A and 77a. The peak strains carried allele @, isolated in this laboratory. In 
the results given below, the protoperithecial parent is designated first, the conidial parent 
second. Crosses 74A x 77a, 77a x 74A, 74A x m, pk-2a x 74A, 77a x pk-LA, eka x 77a all 
gave linear asci. Crosses pk-2A x uk-2a and pk-2a x pk-2A gave aberrant asci. Therefore, it 
appears that the genotype of the zygote rather than the genotype of "maternal tissue" deter- 
vines normal or aberrant asci in these crosses. With reference to the condition of the 
ascus, the interpretation that peak acts as a zygote recessive is strengthened. D. Perkins 
has pointed out to us that peak is probably allelic to biscuit. Results of crosses made in 
our laboratory confirm the suggestion. 
Turian, G. and Seydoux. J. Iso- 
citratase studies in Neurospora. 
Previous results from our laboratory (Turian, G., 
Compt. Rend. Acad. Sci. 252: 1374, 1961 and Path. 
Microbial. 3: 819, 1961) on the acetate-induced 
isocitratase activity in Neurospora crassa are presently being extended with success to E. 
sitophila and &. tetrasperma. Acetate simultaneously induced pure canidiation without pra- 
toperithecial formation in the three species grown at 25'C. 
Comparative studies of isocitratase activity from acetate, acetate-sucrose, and sucrose- 
grown cultures of the three species will be presented at the annual meeting of the Swiss 
Microbiological Society in June in Lausanne. 


English

Genetic basis for an aberrant ascus in N. crassa

Hsu, K. S.

Fungal Genetics Reports 
Volume 1 Article 4 
Drug resistant mutants 
K. S. Hsu 
Follow this and additional works at: https://newprairiepress.org/fgr 
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. 
Recommended Citation 
Hsu, K. S. (1962) "Drug resistant mutants," Fungal Genetics Reports: Vol. 1, Article 4. https://doi.org/
10.4148/1941-4765.1018 
This Research Note is brought to you for free and open access by New Prairie Press. It has been accepted for 
inclusion in Fungal Genetics Reports by an authorized administrator of New Prairie Press. For more information, 
please contact cads@k-state.edu. 
Drug resistant mutants 
Abstract 
Drug resistant mutants 
This research note is available in Fungal Genetics Reports: https://newprairiepress.org/fgr/vol1/iss1/4 
eliminated when sulfur compounds required for growth are added to the minimal mediinn. The 
method therefore seems useful for obtaining a large class of sulfur-requiring auxotrophs 
with partial losses of enzymatic function. 
Hsu. K. S. Drug resistant mutants. DTLQ resistant mutants have been isolated and 
tested for their mode of inheritance, whether 
Mendelian or non-Mendelian. The aim was to add a new class of Mendelian markers besides 
the visible and nutritional ones, and to search for cytoplasmic determinants. No cytoplas- 
mic mutants have been found, but gene controlled resistance to the drugs acriflavine, acti- 
dione, and caffeine has been demonstrated. The results obtained are sL8lunarized in the 
following table: 
Isolation Resistance Locus and 
NO. Druq level (w/ml) Odin linkaae qzroup 
KHl acriflavine 2 spontaneous 
KH2 II 
acr-1 (IL) 
10 spontaneous acr-2 (IIIL) 
KH3 II 10 U.V. - - 
KH4 II 50 U.V. acr-2 (IIIL) 
KH5 11 50 spontaneous _ - 
KH6 9, 50 spo"ta"eous 
KH7 I, 
am-2 (IIIL) 
50 U.V. _ - 
KH51 actidione 10 u-v. _ _ 
KH52 II 10 U.V. 
KH53 71 
act-l (IR) 
10 U.V. 
KHlOl caffeine 2500 sDontaneous _ _ 
All in St. Lawrence background: A dash indicates that analysis is in progress. 
With the exception of KHl and KH2, which were picked up during serial subculture on 
acriflavine-containing minimal mediun, all of the mutants were recovered by plating coni- 
dia on Vogel's minimal medium plus the dr@. The concentration of the drug was such that 
no growth was observable when 106 to lo7 conidia from the sensitive strain were plated. 
U.V.-irradiation giving 50-75s killing was applied in some cases. Strains displaying 
colonial growth and conidiating well were selected for use in the experiments. These in- 
cluded cr.cot. cr.cot'y&. cr'bal. -s-3 --i-3 3 -a---) and 3 z, all in a background of St. Lawrence stocks 
74A and 73a. 
Scoring for resistant vs. sensitive is clear-cut for all of the three categories of 
mutants. The gene acr-2 is the first gene to be located in the left arm of linkage group 
III. In a three-pointcross acr-2 (allele KH2) x sc trvp-1, where SC is the centromere 
marker, the following phenotypic classes were observed; 
+ + 74 
I ","' 
1 
SC tryp 76 I++ + acr SC tryp 6 
acr + tryp 28 + + trYP 0 
i + *c + 31 i acr SC + 0 
Roves. J. The production of mosaic Nitrous acid, ultra violet light and X-rays have 
mutations in Neurospora crassa been used for producing recessive lethals in -- 
conidia of a balanced heterokaryon between 
arginineless and methionineless amycelial. A modification of Atwood's method showed that the 
E 


Drug resistant mutants

Huang, P. C.

Fungal Genetics Reports 
Volume 1 Article 19 
Information on Neurospora 
P. C. Huang 
Follow this and additional works at: https://newprairiepress.org/fgr 
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. 
Recommended Citation 
Huang, P. C. (1962) "Information on Neurospora," Fungal Genetics Reports: Vol. 1, Article 19. 
https://doi.org/10.4148/1941-4765.1033 
This Bibliographic Note is brought to you for free and open access by New Prairie Press. It has been accepted for 
inclusion in Fungal Genetics Reports by an authorized administrator of New Prairie Press. For more information, 
please contact cads@k-state.edu. 
Information on Neurospora 
Abstract 
Information on Neurospora 
This bibliographic note is available in Fungal Genetics Reports: https://newprairiepress.org/fgr/vol1/iss1/19 
Srr.ith, a. R. Mating type tests using Thz following method of using plates for deter- 
a plating technique. mining the mating types of isolates has been 
employed successfully for some tine. It enables 
large nvnbers of cultures to be tested rapidly with a great reduction in the quantity of 
glassware, time and medium required. 
Thick suspensions of conidia of each mating type of the morphological mutant m&' (B132) 
are made in sterile water. A 9 cm. Petri dish containing Westergaard's crossing mediwr 
(Wsstergaard, M. and Mitchell, H.K., 1947, Amer. J. Bot. 34, 573) is spread evaly with 0.2 
ml. of conidial suspension of spray mating type 2 and a similar plate spread with sprav A. 
Inoculated plates are incubated for five to six days at 25OC until a mat of mycelius is form- 
ed and protoperithecia are produced. Should the mycelium tend to spread over- the sides of the 
plate, it may be checked by wiping with sterile cotton wool dipped in alcohol. 
Incubated plates are marked on the back with wax pencil or ink into a convenient grid 
(of 24 01‘ 25 parts) with suitable orientation marks. Conidia from the cultures to be tested 
are inoculated with a loop in the centre of corresponding portions of plates of each mating 
type. In this way two plates are sufficient to test 24 or 25 cultures. The plates are then 
sealed with transparent adhesive tape and incubated at 25% until perithecia are formed. 
Sometimes plates may be scored after only 48 hours incubation but more usually three to six 
days are needed. 
BIBLIOGRAPHIC NOTE 
Huanq, P.C. Information on During the process of reviewing what has bnen 
Neurospora. known about Neurospora after Shear and Dodge 
first coined the name'in 1927, by reading 
the literature and preparing a file pertinent to this organism, I found the following fig- 
ures interesting and informative (Table 1). It can be seen thst there are only 503 papers 
abstracted and published in the Chemical Abstracts from 1933 to 1960 and 567 in the 9io- 
logical Abstracts from 1928 to 1958, the latter include reviews, abstracts, 2nd chapters in 
books. The multimode1 distribution of the number of abstracts is a reflection of the im- 
pact of papers by Dodge and by Lindegren in the 30s and by Beadle and Tatur in the 40s. 
While the majority of the papers in the early 50s deals with mutation, more of biochemical 
nature appeared in the late 50s. The literature is by no means covered completely in these 
two abstracting journals. It is estimated that the actual nlanber lies between 1500 (my 
estimate) to 2000 or more (Bachmann, personal communication). As information an Neurospora 
can be expected to accumulate, the present amount is still not unmanageable. A systematic 
preparation of an annotated bibliography should be feasible and the finished work and its 
subsequent editions would be greatly demanded by all interested. It is felicitatory to learn 
that such a task is being undertaken (see Announcements, this issue). 
*Earlier information on Neurospora may be traced under other names such as Candida, ~ocospora, 
Monilia, Myxosporium, Oidium. Oospora, or even Penicillium (Mireille Moreau-Froment, 1956, 
Revue de Mycologic: Les Neurospora. Bull. de la Sot. bot. Fr. 103: 678-738). 


Information on Neurospora

The problem of mitotic recombination in Neurospor

Case, M. E.

Giles, N. H.

Fungal Genetics Reports 
Volume 2 Article 5 
The problem of mitotic recombination in Neurospora 
M. E. Case 
N. H. Giles 
Follow this and additional works at: https://newprairiepress.org/fgr 
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. 
Recommended Citation 
Case, M. E., and N.H. Giles (1962) "The problem of mitotic recombination in Neurospora," Fungal Genetics 
Reports: Vol. 2, Article 5. https://doi.org/10.4148/1941-4765.1044 
This Research Note is brought to you for free and open access by New Prairie Press. It has been accepted for 
inclusion in Fungal Genetics Reports by an authorized administrator of New Prairie Press. For more information, 
please contact cads@k-state.edu. 
The problem of mitotic recombination in Neurospora 
Abstract 
The problem of mitotic recombination in Neurospora 
This research note is available in Fungal Genetics Reports: https://newprairiepress.org/fgr/vol2/iss1/5 
pH 5.5 pH 6.5 pH 7.5 
18 C 25C 35 C 18 C 25 C 35 C 18C 25C 35C 
A. Zero Nitrogen 
B0rlle.J 5.3 4.5 6.3 8.9 7.3 6.8 8. I IO. 0 0.7 
74 A 6.7 5.6 4.7 8.3 8.3 11.3 6.4 8.4 4.0 
B. NoNO 
Borne0 3.9 4.2 4.3 7.0 7.5 7.2 7.5 7.5 3.1 
74 A 32.9 43.4 25.7 37.9 51. 9 31.9 30.9 34.3 27.3 
C. NaN03 
Borne0 7.4 8.5 5.9 8. I 9.9 8.5 9.3 9.0 9.3 
74 A 44.7 87.3 67.5 61.0 94.2 68.7 59.3 88.3 64.4 
D. NH4CI 
Borne0 29.4 45.7 46.5 31.9 64.3 53.6 13.7 36.0 6.5 
74 A 74.6 97. I 74.5 98.0 112.9 86.3 40.7 88.4 73.5 
Mean dry weights in mg. of 3 replicate mycelial pads of Borneo strain and N. cmssa 
74 A after 7 days growth in modified Fries’ liquid medium with different nitrogen 
sources, buffered at 3 pH levels at 3 temperatures. A. No added nitrogen. 
B. NoNO at 0.0185 g nitrogen per liter. 
D. NH4C12at I. Ill 
C. 
g nitrogen per liter. 
NaN03 at I. III g nitrogen per liter. 
Case, M.E. and N. H. Giles. The problem There is evidence that mitotic recombination (or re- 
of mitotic recombination in Neurospora. assortment) occurs in certain ascomycetes. One such 
case has been reported in Neurospora utilizing unlinked 
,,,arkers (Weir, J.A., Genetics GlOl6, 1960). This phenomenon has been considered OS one possible 
explanation for intemllelic complementation and also for atypical segregations in asci. 
Preliminary evidence bearing on this question was obtained from platings of unisexual and bisexual 
heterocaryons utilizing unlinked biochemical mutant markers. These results produced no evidence for 
nuclear fusion followed by chromosomal reassortment such as to give rise to new genotypes, which would 
be capable of growing on an unsupplemented medium. 
Following the previously mentioned report of mitotic reassortment in Neurospora, this problem has 
been investigated further by making the following cross and looking for prototrophs on an adenine 
supplemented medium. This cross involves three of the seven linkage groups in Neurospom. The proto- 
peritheciol parent, hist-2 ~aan-2 YIO A was crossed utilizing conidia from CI heterocaryon hist-2 a + ad-6 - - 
The wand &markers are the sclme mutants in both the protoperithecial and hetero- pan-2 YIO a. 
caryon parental stmins. The &mutant is not linked to these mutants, while b is linked to &. 
In this manner, fertilization of the protoperitheciol parent nuclei by either one of the hvo parental nuclei 
in the heterocaryon would constitute CI selfing with respect to either the h&or the wn-2 locus and no 
prototrophs would be expected to occur when the cross is plated on an adenine-supplemented medium 
(Diagram A). 
Diagram A 
Protoperithecial parent X Heterocaryon parent 
A, hist-2 o, hist-2 a, hist-2+ 
ylo, pun-2 ylo+, pan-2+ + ylo, pall-2 
ad-& ad&t ad-6 
If however, mitotic reassortment has occurred at some point during either the formation or growth of the 
heterocaryon, or ~1s CI result of (I triple fusion and reassortment at the time of fertilization, then proto- 
trophs would be recovered in such a plating (Diagram B). 
Diagram B 
Protoperithecial parent X the reasserted parents I or 2 
I CI, h&-2+ 2 o, hist-2+ 
ad-6 ad-6+ 
ylo+, pan-2+ ylo+, pal-2+ 
This prototroph would This prototroph would not 
require adenine. require adenine. 
Furthermore, it should be noted that the pan-2 parent is stable and incapable of reverse mutation, and 
in addition that neither parent gives rise to prototrophs in selfings. At the present time, utilizing the 
heterocoryon os the conidial parent, 9.4 X 106 viable oscospores hove been plated from this cross and no 
prototrophs hove been recovered. The results of this type of test thus give no evidence for mitotic re- 
assortment in Neurosporo. ---Biology Department, Yale University, New Haven, Connecticut. 
Curtis, C. F. Studies on the ‘dispen- Atwood and Mukai (Proc. Not. Acad. Sci. 39, lO27- 
sability’ of recessive lethals. 35, 1953) devised o method for detecting mui;;ts which 
cannot grow on complete medium. They used o 
balanced heterokaryon with one of its nuclei carrying o recessive morphological marker. Lethals were 
detected by the non-appearance of marked homokoryons. They were then tested for supplementability 
on complete medium. 
Using the some system, I9 spontaneous lethals were tested and none proved to be supplementable, 
confirming Atwood and Mukoi’s finding that supplementable spontaneous lethals ore relatively rare. 
Gierer (10th Symp. Sot. Gen. Microbial. London, 1960) showed that nitrous acid has its mutagenic 
effect on TMV via deomination of o single RNA base. If its effect is similar in Neurospora, i.e., if 
-- 
it covers only o%oII orea of genetic material, o higher proportion of nitrous acid induced than spon- 
taneous lethals might be expected to be supplementable, from the argument of Horowitz and Leupold 
(Cold Spring Harbor Symp., 16, 65-74, 1951). This would seem particularly likely in the case of nitrous 
acid induced mosaic lethals Gyes, Neurospora Newsletter #I, 1962), which presumably affect one strand 
of DNA. Six mosaics and I8 total lethal5 were tested and among these only one of the total lethal5 WCS 
supplementable. Its requirement was found to be for arginine. Since the unmarked nucleus in the 
origin-1 heterokoryon was& the induced mutation must have been at o complementary locus. 
Non-supplementability on complete medium might be due to interaction of components of the complete 
medium. Accordingly B of the lethols were tested on each of 6 single nutrients which are known to 
interfere with the growth of certain auxotrophs. No cases of supplementation were found. --- Mutagenesis 
Research Unit, Institute of Animal Genetics, Edinburgh, Scotland. 
Johnson, Jane W. and Adrian M. Srb 
The genetic production of small, homo- 
karyotic spores in Neurospom tetrasperma. 
- 
When the colonial mutant pk-2 of Neurosporo cross~l 
- 
is crossed into N. tetrasperma, small, homokaryotic 
ascorpaes are Greed with high frequency. These 
smaller, homokaryotic spores ore easily distinguishable 
from the large, heterokaryotic, bisexual spores normally formed when N. tetrasperma reproduces sexually. 
Isolation of the exceptional spores provides a population genetically c&parable to random oscospore 
isolates after crosses in N. crosso or N. sitophila. Consequently, certain kinds of genetic work with N. 
tetraspermo ore greatlyxcilitated if=e parent in o cross includes the peak gene. 
- 
-shows the frequency of osci containing small, homokoryotic spores in o series of 12th and 13th 
generation buckcrosses of pk to wild-type N. tetrosperma. 
- - 


The problem of mitotic recombination in Neurospora

The Garden City Branch Experiment Station has served the people of Kansas during the past 50 years (1907-1957). This publication is intended to present a historical report of the establishment of the station, its progress, projects, and personnel

Not a member yet

Genetic basis for an aberrant ascus in N. crassa

Drug resistant mutants

Information on Neurospora

The problem of mitotic recombination in Neurospora

Southwest Research-Extension Center: 50 Years of Progress

17,849

19,105