207
The physiology and biochemistry behind the production of zoosporangia in water moulds have
been studied by several aquatic mycologists
(Salvin 1940 , 1941 ; Cantino, 1961 ; Nagai and
Takahashi 1962 ; Murphy and Lovett 1966 ;
Griffi n 1966 ; Griffi n and Breuker 1969 ; Sati and
Mer 1989 ).
Heterothallism and the concept of sexual
hormones in Achlya has been given by Raper
( 1936 , 1951 ) and was later followed by several
workers including Whiffen ( 1945 ), Zeigler and
Linthicum ( 1950 ), Faro ( 1972 ), Tingle ( 1972 )
and Schneider and Yoder ( 1973 ). Light, pH and
temperature conditions have been found to
affect the reproductive physiology of the oömycetes (Reischer 1949 ; Szaniszlo 1965 ; Lee 1965 ;
Lee and Scott 1967 ; Prabhuji 1980 ; Prabhuji and
Srivastava 1982 ; Prabhuji et al. 2009 ). Besides
these, various plant growth regulators have also
been found to affect the different stages of life
cycle of oömycetes (Prabhuji et al. 2009 ,
2012b ). However, a lot of work is further
required for complete understanding of the
metabolism of oömycetes.
Fish Mycopathological Studies
Out of three basic types of mycoses (fungal infection) in fi shes, viz., dermatomycoses (infection of
the skin), branchiomycoses (infection of the
gills) and deep mycoses (infection of the deep tissues and the internal vital organs), the dermatomycosis is associated with the integument and
can cause rapid destruction of the epidermis by
the aquatic fungi (oömycetes). Deep mycosis is
of two basic types: fi rst one, the deep dermal
mycosis and, the second, the mycosis of vital
organs. In deep dermal mycosis which is just a
type of dermatomycosis, the tissues beneath the
surface of epidermis, i.e. dermal tissues together
with scales as well as the underlying musculature, are involved whereas in the second type the
infection involves the vital organs like brain,
liver, kidney, intestines, etc.
Oömycetes that infect fi shes produce easily
recognized cottony mycelia on the surface of
the affected animal; they have probably been
recognized since antiquity (Arderon 1748 ;
Spallanzani 1777 ; Bennet 1842 ; Goodsir 1842 ;
Areschoug 1844 ; Unger 1844 ; Robin 1853 ;
Berkeley 1864 ). In 1877, oömycetes were
reported for the fi rst time in European literature
in association with an epizootic known as
‘Salmon disease’, and the causal organisms were
identifi ed and further studies were made (Stirling
1879 –1980; Huxley 1882a , b ; Willoughby 1968 ,
1969 , 1971 , 1977 , 1978 ; Neish 1976 , 1977 ).
Generally, saprolegnian (oömycetous) infections
are associated with the integument and can cause
destruction of the epidermis, thus depriving the
fi sh of the protection of the mucus. In cases
where saprolegnian infections are restricted to
the integument, it seems reasonable to suppose
that the actual cause of death may be related to
impaired osmoregulation and the inability of the
fi sh to maintain its body-fl uid balance (Gardner
1974 ; Hargens and Perez 1975 ).
Saprolegnian infections of fi sh are frequently
associated with the wounds and lesions and also
handling fi sh may predispose them to infection.
The obvious inference, drawn from these observations, is that these fungi act as ‘wound parasites’. The integument (skin) of fi sh in general
and the mucus, in particular, both present a physical and a biochemical barrier to the initiation of
infection, and if this barrier can be breached, an
infection can proceed unrestrained.
An important point to emphasize is that saprolegnian fungi are not tissue specifi c and are capable of attacking virtually any tissue. This aspect
has been most carefully documented in the
detailed studies of Nolard-Tintigner ( 1971 , 1973 ,
1974 ); however, several other studies have
extended and confi rmed the general applicability
of these observations (Bootsma 1973 ; Dukes
1975 ; Wolke 1975 ; Neish 1977 ; Hatai and Egusa
1977 ; Papatheodorou 1980 ; Srivastava 1979 ,
1980a , b , c ; Prabhuji et al. 1988 ; Srivastava et al.
1994 ; Prabhuji and Sinha 1994 ; Prabhuji et al.
1998 , 2012a ). Therefore, the common designation of saprolegniosis (a generalized term used
for fi sh infection caused by oömycetous fungi) as
a dermatomycosis is both incorrect and misleading. This contention has probably arisen as a
result of the fact that these infections are usually
12 Aquatic Oömycetology: A New Field of Futuristic Research
The physiology and biochemistry behind the production of zoosporangia in water moulds have
been studied by several aquatic mycologists
(Salvin 1940 , 1941 ; Cantino, 1961 ; Nagai and
Takahashi 1962 ; Murphy and Lovett 1966 ;
Griffi n 1966 ; Griffi n and Breuker 1969 ; Sati and
Mer 1989 ).
Heterothallism and the concept of sexual
hormones in Achlya has been given by Raper
( 1936 , 1951 ) and was later followed by several
workers including Whiffen ( 1945 ), Zeigler and
Linthicum ( 1950 ), Faro ( 1972 ), Tingle ( 1972 )
and Schneider and Yoder ( 1973 ). Light, pH and
temperature conditions have been found to
affect the reproductive physiology of the oömycetes (Reischer 1949 ; Szaniszlo 1965 ; Lee 1965 ;
Lee and Scott 1967 ; Prabhuji 1980 ; Prabhuji and
Srivastava 1982 ; Prabhuji et al. 2009 ). Besides
these, various plant growth regulators have also
been found to affect the different stages of life
cycle of oömycetes (Prabhuji et al. 2009 ,
2012b ). However, a lot of work is further
required for complete understanding of the
metabolism of oömycetes.
Fish Mycopathological Studies
Out of three basic types of mycoses (fungal infection) in fi shes, viz., dermatomycoses (infection of
the skin), branchiomycoses (infection of the
gills) and deep mycoses (infection of the deep tissues and the internal vital organs), the dermatomycosis is associated with the integument and
can cause rapid destruction of the epidermis by
the aquatic fungi (oömycetes). Deep mycosis is
of two basic types: fi rst one, the deep dermal
mycosis and, the second, the mycosis of vital
organs. In deep dermal mycosis which is just a
type of dermatomycosis, the tissues beneath the
surface of epidermis, i.e. dermal tissues together
with scales as well as the underlying musculature, are involved whereas in the second type the
infection involves the vital organs like brain,
liver, kidney, intestines, etc.
Oömycetes that infect fi shes produce easily
recognized cottony mycelia on the surface of
the affected animal; they have probably been
recognized since antiquity (Arderon 1748 ;
Spallanzani 1777 ; Bennet 1842 ; Goodsir 1842 ;
Areschoug 1844 ; Unger 1844 ; Robin 1853 ;
Berkeley 1864 ). In 1877, oömycetes were
reported for the fi rst time in European literature
in association with an epizootic known as
‘Salmon disease’, and the causal organisms were
identifi ed and further studies were made (Stirling
1879 –1980; Huxley 1882a , b ; Willoughby 1968 ,
1969 , 1971 , 1977 , 1978 ; Neish 1976 , 1977 ).
Generally, saprolegnian (oömycetous) infections
are associated with the integument and can cause
destruction of the epidermis, thus depriving the
fi sh of the protection of the mucus. In cases
where saprolegnian infections are restricted to
the integument, it seems reasonable to suppose
that the actual cause of death may be related to
impaired osmoregulation and the inability of the
fi sh to maintain its body-fl uid balance (Gardner
1974 ; Hargens and Perez 1975 ).
Saprolegnian infections of fi sh are frequently
associated with the wounds and lesions and also
handling fi sh may predispose them to infection.
The obvious inference, drawn from these observations, is that these fungi act as ‘wound parasites’. The integument (skin) of fi sh in general
and the mucus, in particular, both present a physical and a biochemical barrier to the initiation of
infection, and if this barrier can be breached, an
infection can proceed unrestrained.
An important point to emphasize is that saprolegnian fungi are not tissue specifi c and are capable of attacking virtually any tissue. This aspect
has been most carefully documented in the
detailed studies of Nolard-Tintigner ( 1971 , 1973 ,
1974 ); however, several other studies have
extended and confi rmed the general applicability
of these observations (Bootsma 1973 ; Dukes
1975 ; Wolke 1975 ; Neish 1977 ; Hatai and Egusa
1977 ; Papatheodorou 1980 ; Srivastava 1979 ,
1980a , b , c ; Prabhuji et al. 1988 ; Srivastava et al.
1994 ; Prabhuji and Sinha 1994 ; Prabhuji et al.
1998 , 2012a ). Therefore, the common designation of saprolegniosis (a generalized term used
for fi sh infection caused by oömycetous fungi) as
a dermatomycosis is both incorrect and misleading. This contention has probably arisen as a
result of the fact that these infections are usually
12 Aquatic Oömycetology: A New Field of Futuristic Research