J . Linn. SOC.(Bot.),58. 373, p . 343
With 1 text-jigure
Printed in
343
Gat Britain
On the physiology of sporogonium differentiation in mosses
BY LEOPOLD BAUER
Botaniscks Iwtitut, Universitiit Tiibingen, Germany
I"!I!RODUCTION
Musci are known to be a group of plants the physiological characteristics of which
cover an exceptionally wide range. Protonema is still at the primitive stage of organization of iilamentous algae, whilst the leafy moss plant and sporogonium, being axial
structures, represent a considerably higher stage of organization. Even gametophyte
and sporophyte axes, however, differ very widely in their morphological structure.
To the developmental physiologist mosses are particularly interesting objects of
research, especially since the production of the Merent morphological stages is not
rigorously determined, but open to influences by experiment. The most important
experimental possibilities are provided by artificially induced apospory and apogamy.
The hybrid sporogonium resulting from the cross between Physcomitrium piriforme
(Hedw.) Brid. and Funuria hygrometrica Hedw. (PiHy or HyPi) showed itself to be
particularly suitable for these experiments; under certain conditions the pure species
Physcomitrium was also suitable. Apart from these a few strains were used for the apogamy experiments which were the progeny by spores from the Physcomitrium x Funuria
cross (Bauer, 1957, 1959, 1961a).
Since Pringsheim (1876) and Stahl (1876), we have known that when a section is cut
from the seta of a moss and regenerated, the level of differentation collapses, and that
of the protonema, the lowest stage of differentiation, is reassumed. This protonema is
diploid, and so are the moss stems formed on it. We see that all three morphological
forms can be produced in specimens which have the same chromosome constitution:
the differences between the gametophyte and the sporophyte are thus not dependent
on the change in chromosome number which occurs in the cyclical alternation of generations. The question as to how one and the same genetic system is capable of producing
results of such a Wering nature is fundamental to the whole subject of developmental
physiology, and has the same validity for other groups of plants. Thus the experiments
on the morphogenesis of mosses have a fundamental significance above and beyond the
special aspects.
QUALITY OF THE PRODUCTS OF REGENERATION
Subsequent to our earlier research we now realize that under certain conditions
regeneration products of different kinds can be obtained from the same organ (Bauer,
1957 ; 1961a,b ) . The age of the sporogonium used for regeneration is of special signiscance
in this connexion (see Fig. 1). If the seta tips have h e a d y begun to thicken, only protonema is produced, so the experiments must be conducted on very young sporogonia,
the tips of which are still largely embryonic. On such a young sporogonium one can
differentiate between various morphologically clearly distinguished zones (Bauer, 1957).
The apical cell with its two cutting faces and the immediately following cells, still glassy
and translucent, represent zone A . This is followed by an intensely green section (zoneB).
In the later course of differentiation this section provides in its upper part the capsule
with the sporogenous tissue, and in its lower part the apophysis. In spite of this zone
being still generally meristematic, the upper part (33,) proves to be physiologically dissimilar from the lower (B2).Then we have the extension zone ( C )and the fully differentiated seta cells (zone D ) , the seta originating in the haustorium-like foot (zone E ) .
The extreme tip ( A )is ill-fitted for regeneration experiments because of its fragdity.
344
LEOPOLD
BAUER
When it can be successfully isolated, it regenerates in the same way as zone B,. If a
section is taken through zone B,, apolar-sphericalcells develop on the surface of the cut,
forming a thick callus. The formation of caJlus is promoted by the presence of glucose
(0.01-0.1~)or kinetin ( 1 0 4 ~ )during the process of regeneration (Bauer, 196lb).
The next section (zone BB),extending down to the extension zone, immediately
produces new seta tips, and also to some extent protonema. "he relative amounts depend
on the effect of wound stimulus during preparation. Glucose (0~001-0~01~)
stimulates
this process in the hybrid Piay or Hypi, but the pure species Physcornitrium pirifomne
reacts in this way only on a relatively dry culture medium (4 % agar). The three lowest
zones ( C , D ,E ) provide only protonema and hence offer nothing new. However, in the
Fig. 1. Regeneration products of the different zones of a sporogonium. A, apical cell
and immediately adjacent cells; B,, meristenz&tic region eventually giving rise to the
capsule; B,, meriatan contributing to the seta, at a later stage forming the apophysis;
C, exteneion one; D, fulls differentiated part of seta; 1,foot of 8 normally developed
sporogonium; E , foot of an apogamody formed sporogonium. "he broken lines indicate
indefinite continuation of the growth form depicted in the appropriate cultural conditions.
transitional zone between the meristematic zone and the extension zone, a kind of transitional state can be observed. For these experiments the hybrids PiHy or HyPi are
more satisfactory than the pure species P.p i r i f m . Here protonema is formed, but of
a peculiar kind, and occasionally a few adventitious sporogonia appear. This protonema does not a t f i s t differ in its habit from that regenerated from older parts of
the seta and regarded as normal protonema. Instead of producing buds giving rise to
leafy moss plants, however, as does normal protonema, that regenerated from the lower
limits of zone B,produces new sporogonia directly. These sporogonia can be cultivated
to maturity and spores obtained, or used again for similar regeneration experiments.
It is interesting that, in contrast with sporogonia developing normally, the foot of these
sporogonia formed apogamously on the protonema produces adventitious sporogonia in
the same way aa zone B,, and thus it has a similar physiological state (see Fig. 1, Ea).
From these observations we can conclude that those regions of the developing sporogonium which are still mainly embryonic possess a specific state of differentiation in
their tissues which is preserved through and beyond regeneration.
In the extreme tip (A and B,) the cells me almost entirely embryonic, and hence no
differentiation cttn be observed in the regeneration process.
On the physiology of sporogoniuvn differentiation i n masses
345
In the next lower zone (B2),
although it is still largely meristematic, the seta is beginning to differentiate. The new properties which the c e h have acquired in the process of
differentiation also persist throughout the regeneration process.
In the cells of the seta, which can be regarded as having aged physiologically, the
factors which determine sporophytic differentiation are either no longer active, or destroyed because of increasing lability during the process of regeneration. The stability
of these factors seems in fact to decline in the transitional zone between the meristematic
zone and the extension zone; for example, one or more of the factors responsible for
sporogonial differentiation must still be intact and able to in0uence the nature of the
regeneration.
PERMANENT CULTURES OF THE REQENERATION PRODUCTS
Our further analysis was aided by the fact that not only protonema, but also the two
other kinds of growth regenerated could be separated and cultivated further without loss
of their characteristic growth form. In this stability of a certain state of determination
we encounter an important principle of developmental physiology, reflected elsewhere
in plant morphogenesis.
( 1 ) Callus cultures
( a ) Nutritional conditions. The callus cultures, by now 14 years old, grow exceptionally
rapidly in an optimal culture medium. I n order to maintain them in a constant physiological condition for experimentat,ion,they are transferred every week to a fresh culture
medium ('rejuvenated'), and during this period they increase three- to four-fold. At the
same time they readily disintegrate into groups of cells and individual cells, and can
thus be spread out like an algae suspension. To facilitate propagation, they are cultivated
in a medium which contains 0.01M glucose and 0.3 yo Difco-yeast extract, as well as the
usual inorganic salts. I n an inorganic medium they grow only very slowly in light, in
spite of their intense green colour. Moreover, after several transfers they relapse into
protonema. The callus form cannot strictly therefore be termed autotrophic. With the
provision of Difco-yeast extract alone, which is an optimal source of nitrogen, growth is
very slight. The presence of a sugar however (e.g. glucose, fructose, or sucrose) a t a
concentration of 0 4 4 . 1 ~ / 1stimulates
.
intensive growth. Nitrogen can be supplied in
the form of nitrate or ammonia, but organically bound nitrogen, such as casein-hydrolysate or yeast-autolysate, is far superior. Individual amino acids like glutamic acid,
aspartic acid, and alanine tend to have harmful effects.
(a) Diflerentiation crmditions. An optimal provision of nitrogen stabilizes the growth
form of the callus, and thus acts against the tendency to differentiate. Sugar, on the
other hand (especially with a suboptimal provision of nitrogen, e.g. as potassium
nitrate) markedly promotes differentiation. Principally young setae, but also some
protonema, develop.
Although it is not necessary to add growth substances, the increase in mass of the
cultures is very strongly stimulated by the addition of indole-3-acetic acid or naphthylene-acetic acid (lo-'-lO-6~), kinetin ( l O - 5 ~ ) , gibberellic acid ( 1 0 - 4 ~ )and
,
coconut
milk (c. 4%). Differentiation, however, is neither induced nor retarded by these
substances.
I n contrast to the callus cultures of the spermatophytes, the calli of the mosses
examined up to the present are stable only in hght. An exact test of the effectiveness
of the various spectral regions has not yet been undertaken, but blue light (Schott Filter
BG 23) has a stabilizing effect on the callus form, whilst red light (Schott Filter RG 1)
has a polarizing effect (Osram HNT fluorescent lamps being used as a source of light in
both cases). This polarizing effect manifests itself in the fact that the spherical cells
which previously grew in disorder become organized, and link themselves to form a
linear cell chain. This chain form has a key position in the further process of differentiation, since this stage is passed through both in the transition to the protonema form
346
LEOPOLD
BATJER
(accompanied by cell elongation)and in the transition to the seta form (accompanied by
tissue formation).
In white light (Osmm HNT fluorescent lamp, 2000 lux) a rhythmic sequence of 16 hr.
light and 8 hr. darkness proved to be favourable for the stabilization of the callus form.
Constant light p r o m o b the f o m t i o n of metabolic products which damage the cultures.
A demewing length of day, down to a 4 hr. day, favours the formation of young setae
from the callus cells. It is noteworthy that in them circumstances the seta in its early
stagers has an apical cell whose longitudinal walls tend to be parallel and not inclined
diagonally towards each other; the apical cell with two cutting faces develops only later.
Where the daily exposure to light is between 1 and 4 hr., differentiation in general proceeds m far m the cell chains just mentioned, and with yet shorter exposure times there
is an ever-increasing tendency of the cells of the chain to elongate and form protonema.
In total darknessthe callus culture changes completely into protonema. The protonema
gained in this way grows well in darkness on an organic medium.
Differentiation can also be regulated by influencing the state of hydration of the
protoplmm. It has a,lready been observed in Physmitrium p’r$orme (Bauer, 1957)
that relatively dry culture conditions ( 3 4 % agar) during the regeneration process
promote the formation of setae. The same conditions also favour the transformation of
the callus into sporogonia. I n the more recent experiments the hydration of the culture
medium was controlled as follows : apart from the food materials, a substance was added
to the 1.5% agar which was without nutritional effect, but which was osmotically active.
Mannitol, which cannot be used by mosses as a source of carbon, proved to be suitable,
and also the polyethyleneoxide ‘Lutrol9’ (molecular weight c. 400). Already with the
~
(the optimum dosage is @2M) young setae
tddition of, for example, 0 . 1 mannitol
begin to develop witbin a week, even when there is an excellent supply of nitrogen which
would be expected to milifate against this behaviour. The control without mannitol
remained entirely in the callus form throughout.
It may be aasumed that protoplasmic structures differ in their sensitivity towards
dehydration. The activity of the individual enzymes may thus be influenced in varying
degrees, with the result that metabolic rakes are changed.
(2) Seta cultures
( a ) The different properties of seta cultures. A possible experiment would be to detach
the young setae and to follow the stages of maturation of the sporogonium, but this
inquiry will be left wide for the present. We shall attempt here to discover how far the
stage of Organization of the sporogonium itself can be preserved in a permanent culture.
It ahould be stressed that the growing secondary sporogonia behave in the same way in
respect to regeneration m the primary sporogonia. Cutting the meristematic tip in
zone B, always leads to the formation of new seta tips, and this method of regeneration
can be continued indefinitely.
The problem is, then, to guarantee the continuity of the physiological state of zone B,.
Up to a certain point in the development of the seta, i.e. before the capsule begins to
thicken, this physiological sfate remains almost unchanged, and the success of the
subcultures of the sporogonium stage is dependent on the secondary sporogonia being
still young enough at the time of regeneration. This is valid for the hybrid PiHy and
HyPi. But it is possible with another strain to maintain the sporophyte stage in culture
indefinitely without speoial precautionary measures. This strain derives from a spore
from the hybrid capsule M y . The gametophyte forms occasional sporogonia apogamously but the number is greatly increased if chloral hydrate (0*001M) is added to the
culture medium (Bauer, 19f33a). These sporogonia possess a quite unusual, and hitherto
unrealized, stability in their stage of organization. Protonema is only rarely formed on
aged, browning parta of the seta. On the other hand, even the fdly differentiated seta
On the physiology of sporogonium differentiation i n mosses
347
tissue can return to an embryonic state and form new seta tips aa lateral branches at
practically any point. This is hence the ideal strain for unlimited mass propagation of
mow sporophytes by means of explants (Bauer, 1961a).
( b ) ktetabolic peculiarities. The existence of these cultures gives us an opportunity to
investigate the question of the differences in metabolism between the gametophyte
and sporophyte. Although it is our aj,to d e h e those stages in metabolism which are
directly connected with morphogenesis, the analysis must necessarily begin with basal
metabolism. It must be prticulerly stressed that the most important heterotrophic
traits mentioned above for the callus form are characteristic also of the whole of the
sporophyte stage. Specially designed experiments with young sporogonia formed
apogamously on the protonema of P.pirtfn7ne showed that these traits are not only a
peculiarity of the hybrid combinations, but are valid also for the pure strains. This
similarity of behaviour justified the use of the hybrid strain for the main experiments,
since mass propagation is more readily possible with this strain.
Culture tests show that the sporophyte makes a better use of organically than of
inorganically bound nitrogen, whilst the gametophyte with the same genetic constitution
clearly prefers nitrate. When the gametophyte and sporophyh are dependent for their
carbohydrate on photosynthesis alone, the latter grows exceptionally slowly, whilst the
former grows well. As the experiments were carried out with young setae which did not
bear capsules, the possibility remains that the sporogonium might reach a short autotrophic phaae after the formation of the stomata in the region of the apophysis. The
addition of sugar promotes the growth of both gametophytes and sporophytes. The
gametophyte can be cultivated permanently and without injury in a culture medium
with 0.1M glucose, and it remains a normal green. The growth of the sporophyte, on the
other hand, is maintained by the same medium only for the first 4 days, and during this
time the new growth is almost completely free of chlorophyll. A golden-yellow pigment,
leter changing to yellowish brown, is deposited in its membranes. During the following
days this pigment is formed in such quantities that it escapes into the agar, and completely poisons the sporophyte culture within fourteen days. Although it has slightly
less powers of promoting growth, 0.01M/1. glucose is therefore to be preferred for permanent culture.
At present the saps pressed from gametophytes and sporophytes are being compared
for their composition with the aid of paper chromatography. The following information
can already be given from these experiments, which are not yet completed.
The content of amino acids or amides is several times greater in the sporophytes than
in the gametophytes. On feeding with 0.1M/l. glucose the total amount in the sporophyte
rises more sharply than in the gametophyte. Further, the ratios of the amounts of
several of the amino-acids differ in the two growth forms. When sugar is omitted from
the medium, no sugar can be detected in the expressed sap, but after the addition of
0.1 M/1. glucose more sugar accumulates in the sporophyte than in the gametophyte.
Whereas the sap of the letter shows only minute quantities of fructose and glucose,
and traces of sucrose, the correspondingsugar spots for the sporophyte are very strongly
marked on the paper (as yet there are no quantitative comparisons).
Acids of the Krebs cycle have only been established in very minute quantities (0.1yo)
in both cases.
Secondary plant products which couple with diazotized sulphanilic acid, i.e. mainly
substances of a phenolic nature, are found in both gametophyte and sporophyte. Not
only do they differ, however, in quantity, but elso very markedly in quality. Whether
and to what extent these substances peculiar to the gametophyte or the sporophyte
are concerned with the metabolic stages of differentiation will be the subject of a special
investigation.
Amongst the precursors of the nucleic acids, the higher content of adenine in the
sporophyte is especially striking.
348
LEOPOLD
BAUER
On the whole one can say that these phpiologioal comparisons between gametophyte
and sporophyte juati€y the assumption that the sporogonium doee not grow on the gametophyte because it is in need morphologidy of an anchorage, but because its metabolic
peculiarities require it to behave to some extent aa a parasite.
( 3 ) Protonenzcr generated by the sporogmium
The altered protonema gained from the lower limits of zone B, is not committed permanently to the apogamous formation of sporogonia. By the constant transferring of
the new growth to fresh culture medium the tendency to produce sporogonia is quickly
eliminated and the protonema functions henceforth exactly like normal protonema, i.e.
the buds it produces yield only the leafy gametophyte. No experimental re-induction of
the factor responsible for -the appearance of sporogonitt has yet been possible. Under
certain conditions, however, the fador can be stabilized to some extent. The regenerated protonema is cut away h m the sporogonium before it begins to produce sporogonia
apogamously and transferred to 3 4 yo agar. In these relatively dry culture conditions
the sporogonium factor can be preserved in a latent state in the protonema through
numerous subcultures, and can be made active a t any given time by allowing the
protonema to come to bud (Bauer, 1961a). The addition of 0-01-0-1~/1.
glucose also
helps to stabilize the sporogonium factor in the protonema. In the presence of glucose
it is possible to propagate the fador in protonema even where it is not normally stable in
conditions of reduced hydration, as for example with PhyscomitriUm p i r i f m .
We may conclude from this that the factor is not a hormone-like substance which
passes from the sporogonium to the protonema. After the removal from the sporogonium, the supply would be a t an end, and the substance in question would become
increasingly weak as it spread amongst the cells. With the large number of newly formed
cells there would soon be an inadicient number of molecules to go round. The factor
must therefore have the property of self-reproduction. It is able to propagate itself in
every protonema cell, even though it is in the ‘wrong’physiological place.
Leafy moss plants and sporogonia borne on protonema (sporophyte stems) have much
in common in their genesis. This is revealed by the f a d that all those factors which promote or retard the appearance of vegetative buds on the protonema behave in the same
way in respect of the buds giving rise apogamously to sporogonia (e.g. the quality and
quantity of light, the temperature, degree of hydration, nourishment, presence of growth
stimulators). They have in common an axial character, and this higher stage of organization distinguishes them h m the protonema. But this axial character, and the complex
of factors responsible for it, are still unspecific. There is, however, a specific difference in
the nature of their apical cells. That of the stem of the gametophyte has three cutting
faces, whereas that of the sporophytic axis has two, and the difference in habit between
gametophyte and sporophyte is certainly largely dependent upon the resulting differences
in the sequences of new cells. It is rewonable to asume that the factor which determines
that the protonema shall produce a sporogonium is reaponsible for the character of the
apical cell. !Chis factor thus completes in a specific way a complex of unspecific ‘stem
factors’ also present in the gametophyte, so that a whole sporogonium is generated.
When the buds on the protonema yield the characteristic configuration of the leafy
gametophyte we must m u m e that in this case the complex of unspecific ‘stem factors’
has been completed by a corresponding vegetative specific partial factor. Our experimenta have clearly shown that this partial factor can be replaced by the ‘sporogonium
factor ’.
(4) Protonema generated by the d u - s
A specific differentiation factor can also pass from the callus cells into the protonema
and there be p
d on through numerous sequences of cell divisions in a latent state
as a physiological ‘foreign body ’. As mentioned above, the callus produces protonema
On the physiology of aporogoniunz diffe.e.tiation in m s a e a
349
cells exclusively in darkness, but if the protonema is brought to the light after 2 weeks,
all its apical cells immediately change into the spherical shape characteristic of callus
growth. In this caae, then, we do not have to wait for the production or activation of a
supplementary complex of factors, a8 is necessary with the apogamous formation of
sporogonia on protonema. Normal protonema, although having the same genetic constitution, never reacts in this way under identical experimental conditions. The only
change is in the proportions of the cells, and these immediately become normal again in
the new growth when the culture is returned to the light.
CLOSINQ R E W K S
The degree of organization of the sporogonium is an expression of the combined action
of a large number of morphogenetically active factors. Its specific morphological and
physiological state represents a defbite position of balance amongst these factors. From
this complex of factors, a t first sight irresolvable, we can nevertheless distinguish a few
endogenous complexes of factors or partial factors:
(1) A factor which participates in an essential manner in the growth form of the callus
and which probably belongs to the embryonic state of the young sporogonium tip; it
can enter the protonema in a latent state.
(2) A partial factor determining the differentiation of the sporogonium, also able to
exist in the protonema, and which in connexion with bringing about the formation of the
typical apical cell compels the moss bud to develop into the sporogonium.
(3) A factor which was recognized in the physiology of bud formation. It promotes
(though at fist in an unspecific manner) the higher stage of organization, namely the
axial character, of the plant which arises on the simple protonema.
A characteristic of these factors (or complexes of factors) ia their interchangeability
with other factors of morphogenesis. We can observe this fact if we consider the factor
which conditions the formation of the apical cell with two cutting faces. This factor
brings about an anatomical feature which is an essential preliminary in the development
of the sporogonium, and as such is probably identical with or forms part of the factor
which passes into the protonema during regeneration. Looking now a t morphogenesis
in the moss plant as a whole we find that an apical cell with two cutting faces occurs
elsewhere in the development of the gametophyte. Thus the leaves, and the male and
female sexual organs, begin their development with an apical cell of tbis kind. It cannot
be accidental that it is in precisely these places that the apogamons formation of sporogonia is not infrequently found. Sporogonia borne in place of leaves were first described
in Phascum cwpidatum by Springer (1935). They were later discovered in Desmato&on
by Lazarenko (1960) and by Lazarenko, Paahuk & Lesnyak (1961), and by myself in
Splachnum sphuericum (Bauer, 1963b). Moreover, the transformation of young stages of
male and female gamehngia into sporogonia or sporogonium-likeformations can easily
be accomplishedin 8.sphaericunz. By transferring plants forming gametangia on to very
dry culture media, the processes of sexual maturation are interrupted, and aa yet undifferentiatedstages of the gametangia continue to develop like sporogonh. On the other
hand, the factors responsible for sexual differentiation can also affect leaf development,
and the tips of the leaves then change into gametangia. This has been recently described
by Hoffman (1956).
We can see, then, that the partial factor common to all three morphological forms
remains stable and can become concerned with the genesis of other morphological units
by association and interchange with other partial factors. This means, however, that a
factor which is of decisive sigdcance for the differentiation of the sporogonium or
gametophyte does not a t the same time need to be rigorously specific for this morphogenetic event. Specificity can only be attributed to certain combinations of factors.
Characteristic of the morphogenetic factors or combinations of factors describedJOURN. LINN. S O C . - B O T m ,
VOL. LVlII
23
350
LEOPOLD
BAUER
and this in itself poses a problem-is their relatively high stability, and associated ability
to reproduce themselves. Is thie the result of a certain combination of genes controlling
certain prooessea in morphogenesia being M c d t to destroy and eliminate ? After Beerman's (1952) experience with the giant ohmmommes of the C h i r w larva we can,
with all due caution, wume that for plants also a definite physiological state is wcomp h e d by a definite combination of genes in their active state, the remainder at that
time transmitting little or no information. Or must we reckon with plammtic structures
capable of self-reproduction? We do not yet know, but without doubt in our analysis
of the endogeneous factors d d b e d we me in a sphere of morphogenesis more closely
related to the effects of genetic structures than to those of the external environment.
SUMMA.FbY
1. The morphological nature of the tissue regenerating from the apmgoniUm of a
moss depenb upon the physiological age of the regenerating zone. After the sporogonium has attained a certain stage of ageing, only protonema is formed, irrespective of
the zone.
2. If the regeneration is carried out in the tip region of very young sporogonia, still
largely embryonic, factors influencing difFerentietionpass into the regnerated tissue.
3. Tisaue regenerated from the extreme tip retains embryonic features and consists
of undifferentiated, apolar, callus ceb.
4. In the subsequent zone, which later on gives rise to the apophysis, other factors
are present, and the regenerating tissue gives rise to new sebe.
6. The faotora mponsible for contxolljng the differentiation of tissue regenerating
from the meriskmatic zones cannot be detected in the subsequent extension zone by
regeneration experiments. Some influence persists, however, in the intermediate transition zone, and it is transmitted to and propagated in protonema arising in this region.
Such protonema in oertajn conditions give rise to sporogonia apogamously.
6. Although callus cultures give rise to protonema in derkness, a specific differentiation factor is present since callus is invariably reformed on il'hmhation.
7. All the forms of regenerated tissue (callus, that giving rise to setae, and protonema
giving rise to sporophytes) can be maintained in culture. In a strain of hybrid origin,
the stability of the seta form in culture is so high that it is comparable with the independent sporophytic regeneration of a higher archegoniate plant.
8. The callus and seta forms regenerated from the sp0rophyt.e have marked heterotrophic tendencies. In addition gametophyte and sporophyte produce secondary plant
products Mering qualitatively as well aa quantitatively.
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€"OSHE~,
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23-2