sugar glider mosaic longitudinal study
DESCRIPTION
Sugar glider study focusing on mosaics that attempts to answer two questions: 1. Does homozygous inheritance of the dominant mosaic gene (MM) result in lethal embryonic death?2. Is powdering (graying) a heritable trait with epistatic function?TRANSCRIPT
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Part 1: Mosaic gene inheritance
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Some basics In the nucleus of each cell, humans
have 23 pairs of chromosomes a total of 46
Offspring will randomly inherit half of each chromosome from their mother, and half from their father
For each observable trait, an organism inherits 2 alleles (2 variations that make up a gene)
Human Father
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Understanding Gene Inheritance
50% of genes come from the mother, and 50% come from the father
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Dominant: Only one allele is needed to show observable trait (phenotype)Recessive: Two alleles are needed to show observable trait (phenotype)
Heterozygous: Two different alleles inherited
Homozygous: Two of the same alleles inherited
Remember:One half comes from each parent
Chromosome
Momshalf
Dadshalf
2 alleles = 1 gene
b
B
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Genotype PhenotypeThe genetic makeup Physical, observable expression of genotype
(color/pattern in our case)
mm
Mm
MM
Non-mosaic
Mosaic
Mosaic
Same phenotype, different genotype!
In theory
DOMINANT GENES
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Mosaic (Mm) a dominant gene
Mosaic Father
No
n-m
osa
ic M
oth
er
Mosaic
Mosaic
MosaicNon-mo
Non-mo
Non-mo
If joeys do not inherit the mosaic phenotype, then they do not have the mosaic gene and can not pass it on to future progeny
(Based on empirical evidence)
M = Abnormal gene (Mosaic
m = Normalgene
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In theory, inheritance of the mosaic gene should work in a similar way to earlobes in humans.
Those that inherit two copies of the dominant gene EE will have children with unattached earlobes 100% of the time, even if the other parent does not have the dominant gene.
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In theory
Mosaic Father Super Mosaic Father
No
n-m
osa
ic M
oth
er
Mo
saic
Mo
the
r
75% of gliders produced by a mosaic x mosaic pairing should be mosaic, with 1 in 3 of those mosaics being a super mosaic (will always produce mos, even when paired with a non-mo)
Mosaic Mosaic
Mosaic
Mosaic Mosaic
Mosaic MosaicNon-mo
Mosaic MosaicNon-mo
Super mosaic
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And yet based on breeder observation, it is not possible to breed a super mosaic
Could inheriting two copies of the mosaic gene result in homozygous lethal embryonic death?
Homozygous inheritance of lethal genes exists in horses, cats, rats, alpaca, and mice (1).
1: Gruneberg 1936; Hintz and Van Vleck 1979; Geissler et al. 1981; Niwa et al. 1991; Hosoda et al. 1994; Santschi et al. 1998
Agouti gene in mice
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Merle gene in Australian Shepherds
Lethal white in horses
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So how can we prove this?
If MM is lethal, then rather than produce a 3:1 (75%) mosaic offspring, mosaic x mosaic pairings hypothetically will result in a 2:1 (66%) ratio of mosaic to non-mosaic offspring.
66%
33%
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Why not just use the database?
Oftentimes breeders do not put pet-only gliders in the database. Rarer colors are more likely to be sold for breeding, and thus be put in the database, skewing results.
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Part 2: Powdering (graying)
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Some famous piebalds before and after
Sparrow
Kaleidoscope
Credit: Tyler Cleckley, Shelley S.
Credit: Priscilla Price
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Diamond as a joey
Diamond as an adult
Sometimes, gliders can powder pied (progressive pieds)
Ph
oto
cre
dit
: Ad
ri L
op
ez
Pixie
Ph
oto
cre
dit
: Bri
ttan
y H
.
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Possible candidate genes?
Vitiligo gene
Chinchilla/silvering gene
G locus graying gene (what turns gray horses white)
Silvering Gene
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Sometimes blood mark patches are left on horses that gray out
Gray at 4 years old
Same horse 3 years later
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Part One: Mosaic Gene Inheritance
Must have lineage
Must be breeding mosaic x mosaic
Report how many gliders born mosaic vs. non
Part Two: Powdering (Graying)
Must have lineage
May be pet-only or breeding
Pictures of glider as a joey and as an adult (preferred)
OR your description on whether or not glider has powdered