Download pH 5.5 pH 6.5 pH 7.5 18 C

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