2015 Steel Update

Original Steel Article (2013)

Steel: One or Many?

Steel has gotten more confusing with time. Steel was originally noticed in a "black" female named Uno. From Uno, the mutation was traced back to an earlier "black" female named Rigel:

sstars_rigel1
rigel1 rigel3


The path of inheritance was assumed to be:

uno-if-from-rigel


Of note, Arrakis and GEG's Kylee produced the presumed SpSp Sl+ pups.

At the time, I had acquired a line of highly-inbred "pure" (aa CC DD EE UwUw pp) Lilacs, the "Wiles" line. You can see above that the Wiles line was crossed into Rigel's line after Arrakis's generation but before Uno's generation.

In an attempt to produce true Black gerbils for comparison against Black-Steel, two females from the pure Wiles line were paired with two Black males that were not related to each other, the Wiles line, or any lines involved with Steel. Shockingly, these pairings produced Steel pups! Somehow, the Wiles line was also carrying a Steel mutation.

This really threw a wrench in things. There was no way of knowing whether Uno's Steel mutation came from Rigel or from the Wiles line! Because some of the first Steel litters were between Uno and her uncle Dancer, it's possible that both versions are present in Uno's line, or were at one point.

uno-dancer_wilesVSrigel


One key point may be the fact that, after Uno's generation, I did not see any lethal SpSp Sl* pups. It is likely that the Steel mutation I am currently working with came from the Wiles line, and that this particular mutation does not have the same effects as the original (Rigel's) when combined with Dominant Spotting.

A pair consisting of offspring from the pure-Wiles outcross has since produced pups with the typical Steel markings.

Wiles-steels


Of course, it couldn't be that easy, either. Once again, a pup with typical Steel markings popped up in a litter where it shouldn't. This time, neither parent had any ties to any of the known Steel lines.

SGL1-Sl01m-crop


However, one parent did go back to some High White lines. Digging a little deeper, Rigel also went back to some High Whites. Maybe coincidence... maybe not.


US High Whites and Mock-WhitePaws

Let's sidetrack for a bit. When High Whites were getting particularly popular, some strange pups started occurring in the same litters. These pups didn't seem to have DomSpot, but did show extensive white on the forepaws and bib, and even some white on the back paws, a head spot, neck spot, or ventral spot. The immediate concern, seeing both high white expression and low white expression in the same litters, was that Semi-dominant Lethal Spotting (Sls) had made its way to North America. When heterozygous, this gene gives a pattern known as WhitePaws (WP)(Sls+). These gerbils have white on all four paws, often a mix of colored and clear nails, and sometimes a head, neck, or ventral spot. And when this is combined with DomSpot, you get Extreme White (EW)(Sls+ Sp+): a gerbil with white markings covering well over 75% of the body. Sounds like a match so far, right?

sstars_abcs_spot1 sstars_abcs_explosion
Mock-WhitePaws and High White sibling


The problem is, as the name might suggest, Sls homozygotes are lethal. And not early in development like with DomSpot. Two doses of Sls produces a RumpBlack (RB)(SlsSls), a white gerbil with pigment around the base of the tail, and occasionally on the head. Combined with DomSpot, it creates a Pure White (PW)(SlsSls Sp+). Both of these die a slow, unfortunate death of toxic megacolon. Thus the serious concern that we might be encountering Sls in the States.

However, no US breeder has ever reported a RB or PW pup. So without further evidence, it seems our US High White is not created by the same mechanism as the European Extreme White. What is it, then? And what are the pups that are spotted-but-not? The prevailing theory is a simple accumulation of the nebulous "spotting modifiers". The same way modifiers change a Pied gerbil to Mottled, they would change a Mottled gerbil to High White. Solid pups from Mottled lines are well known to have extra-large bibs and knuckle-dusters, so the odd "spotted solid" pups would just be an exaggeration of that.

Personally, I think there's something else going on. I think there's a third factor at play. Not Sls, but something. If all you needed to "make" High White was DomSpot and a bunch of modifiers, then A) the increased expression of white would have been more gradual over the years, and B) any breeder could have made them. Instead, you see High Whites suddenly appearing from, and tracing back to, only a few select kennels.

What do I think that "third factor" is?

Steel, of course! Not necessarily the same Steel mutation I'm currently working with - I've already encountered as many as four separate mutations. It appears likely that Steel is particularly prone to mutations (and remutations), with an unknown number of mutant alleles circulating in the gene pool at any given time. Without selective breeding to highlight the Steel markings, they're easy to miss.

I think what I'm currently seeing is a Steel mutation (or more than one!), with and without DomSpot. Because I'm not working with much in the way of spotting modifiers, I'm not seeing High Whites. Or perhaps the version of Steel I'm working with doesn't make High White. However, they do make something quite attractive...


Roan

I've noted before that Steel seems to interact with DomSpot, giving odd patterns and increased flecking. I've started to breed away from the usual spotting modifiers to bring out that flecking, with encouraging results.

roan-side


The mixture of white and colored hairs (roan) produces a very attractive patterned gerbil, without the risks of excessive depigmentation (head tilts, hyperactivity, loss of balance) that can come with High White gerbils.

roan-top



Progression of Steel

At the same time, selecting for increased expression of white in my Steel-only lines is showing success as well. The selectively-bred Steel phenotype is getting closer and closer to a mimic of the WhitePaws (and Mock-WP) phenotype, while having a very different interaction with Dom Spot. The pup below is one of the closest thus far, with white on front paws extending into the nailbeds, white on both top and bottom sides of back paws, and a ventral spot.

SSL3_2015-11-29_m02 SSL3_2015-11-29_m01


This pup's mother was also bred with a Dom Spot male (Aa CC DD ee Uw* P* Sp+), producing pups in the Spotted to Pied range - further distancing this Steel mutation from WP and Mock-WP lookalikes by the lack of Extreme White or High White pups.

SCL1_2014-11-15_01SCL2_2015-01-04_01
sugarplum-side1





Updated information on Steel 2020

 


Last updated: Jan 2021
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