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From: pell@boulder.Colorado.EDU (Anthony Pelletier)
Newsgroups: sci.bio
Subject: Re: C. elegans
Message-ID: <1090@sigi.Colorado.EDU>
Date: Wed, 13-May-87 13:46:00 EDT
Article-I.D.: sigi.1090
Posted: Wed May 13 13:46:00 1987
Date-Received: Sat, 16-May-87 04:08:11 EDT
References: <1055@thebes.UUCP> <9576@duke.cs.duke.edu> <1640@zeus.TEK.COM> <1044@sigi.Colorado.EDU> <1055@aecom.YU.EDU>
Sender: news@sigi.Colorado.EDU
Reply-To: pell@boulder.Colorado.EDU (Anthony Pelletier)
Organization: University of Colorado, Boulder
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Distribution:sci.bio


In article <1055@aecom.YU.EDU> werner@aecom.YU.EDU (Craig Werner) writes:
>
>	C. elegans has two sexes.  Hermaphrodites (which are both male
>and female combined) and Males (which only produce sperm).  Females are
>XX, there is no Y chromosome, males are X  (or XO signifying 1 X only),
>and arise by a non-disjunction event.
>	Most nematodes, on the other hand, have two definite sexes, where
>XX is female and X is male.
>


I must admit that I was tempted simply to take the advice of the quote at
the bottom of your article to heart and not reply; but I decided that it
might provide sufficient amusment to respond to your posting even at the
risk of a prolonged discussion with a twit.

If you choose to give an introductory lecture on on a topic, do try to get it
right.  Sean is quite competent and has already corrected a few of your errors.
I will point out only one more.  You are right that: C. elegans exist as male
or hermaphrodite; the XX animals are hermaphrodite and the X_ animals are
male; and males can arise in populations of hermaphrodites through a 
non-disjunction of the X during meiosis.  You are incorrect in your statement
that this differs from other nematodes, which are also male/hermaphrodite
species in which the male is X_.
In a cross fertilization between  male and hermaphrodite C. elegans, the
offspring are the expected 50% male.  Meiosis and fertilization are 
not fundamentally different.
You still get one X_ animal for each XX.  The reason for the low frequency
of males even inn mixed populations is that 
"The worm...prefers not to copulate at all with others but rather prefers 
itself...  It is after all British"  as John Sulstan so eloquently put it at the
1983 Cold Spring Harbor Symposium on Quantitative Biology (Neurobiology,
that year).
This species of nematode does have "two definite sexes" as do the others.
The hermaphrodites simply prefer not to mate and do so only when cornered
(it helps, if one wishes to do a cross, to make the hermaphrodite 
unco-ordinated by mutation, so that she cannot get away).

One more thing, any tech who sub-clones something into pBR has a plasmid
with her/his initials.  We are not impressed.
>~.
>
>-- 
>			      Craig Werner (MD/PhD '91)

Craig, if you mean second year student, say second year student.

A.J. Pelletier