sterile mutants

Model Organism: Worms Scientific Discussion
1

Dear all,

i would like to use sterile mutant for my work in pathogen study to reduce the confounding effect of baggings, progenies production etc.
However, the choice of using glp-1 and glp-4 mutant are out, because we would prefer to use worm with an intact germline,
which otherwise would have caused the pathogen resistance effect (which could be DAF-16-dependent due to germline loss)

May i have the suggestion if there is any mutant worm that is temperature sensitive, carry the germline but fail to reproduce at
restrictive temperature while not affecting the normal physiology of worm (like movement, feeding behavior) and DAF-16 regulation?

What i have in mind now is:

  1. fer-15 mutant but it seems fer-15 gene does have impact on DAF-16
  2. fer-1 mutant but fer-1 mutant has subtle locomotion defect
  3. fer-2 mutant – though fer-2 mutant has reduced brood size at permissive temperature.
  4. fer-3, fer-4

i can go through from fer-1—15, or fem-1–3,
but may i know other than this, is there any more suggestion?

thanks

2

fog-1(q253)

3

There are a number of Spe (spermatogenesis-defective) mutants that satisfy your criteria. The best would probably be one of the spe-9 t.s. alleles (hc52 or hc88), which produces spermatozoa that are defective for fertilization but otherwise normal. Note that the Fems and Fogs produce worms that make only one type of gamete, which may impact your results [e.g., fog-1(q253) lacks sperm, which are necessary for normal oocyte maturation and ovulation).

4

tyrael’s assumption that there is an interaction between fer-15 and daf-16 is based on:

http://www.wormbase.org/species/c_elegans/interaction/WBInteraction000518680

There seems to be a mis-annotation here, as the cited evidence does not support an interaction between daf-16 and fer-15.

Rather, the cited results indicate that daf-16 suppresses the age-1-associated increase in lifespan:

“fer-1(b26) age-1(hx546) at 25.5 was 28.0 days whereas the mean life span of daf-16(m26) I;fer-1 age-1 II was reduced to 15.8 days. The control daf-16;fer-1 strain had a mean lifespan of 12.7 days at 25.5”.

[fer-1(b26) = fer-15(b26)]

but as the authors of the same paper write,

“The mean life spans of the sterile fer-15; daf-c double mutants were like that of wild type”.

Indeed there appears to be no published evidence for a genetic interaction between daf-16 and fer-15. Evidence to the contrary includes:

  • “The ts fer15 mutation causes sterility, but does not increase life span (FRIEDMAN and JOHNSON 1988)”.

  • The time course of survival of fer-15 on certain pathogens is essentially identical with that of wild-type worms (see for example, http://www.wormbase.org/resources/paper/WBPaper00005819)

  • The fact that the original age-1 alleles were isolated in an fer-15 background.

In our hands, fer-15 has been a very suitable mutant for pathogenesis work.

5

This has been a very helpful discussion for me as well, as I am interested in whether mechanosensation of unlaid eggs
affects egg-laying circuit activity. We’ve treated L4’s with FUDR, but I would also like to test a ts sterile mutant. While
the sperm-defective ts mutants look really good, am I correct is assuming that the unfertilized oocytes are still laid?

Is there a ts mutant that gives an uterus devoid of even unfertilized eggs?

Thanks! -Kevin.

6

Egg-laying is delayed but not abrogated in worms lacking sperm (e.g., fem-1). Your options for an egg-free uterus are to use hermaphrodites that 1) produce only sperm [like fem-3(gf)], 2) produce no gametes (glp-4), or 3) have finished egg-laying (old adults).

7

Thanks!