There is new evidence that the “mother’s
curse” – the possibility that moms may transmit genes to their children
that harm their sons but not their daughters – holds true in animals.
Such a possibility arises because there are two independent parts of
the genome in the eukaryote cells, which are found in plants and
animals, and the two are locked in a “conflict-driven molecular arms
race” that impacts human health and wellness. The lion’s share of the
genome is located in the cell nucleus. But there is also a much smaller
secondary portion located in the mitochondria.
According to the generally accepted theory, mitochondria were
originally independent bacteria that developed an ability to tap highly
toxic oxygen molecules as a powerful energy source. Eukaryotes lacked
this capability, so some of them found a way to swallow the
mitochondria’s ancestor without digesting it – converting it into an
“endosymbiont,” an organism that lives within the body of another
organism. Unlike the nuclear genome, which is built from a combination
of father’s and mother’s genetic material, the mitochondrial genome is
passed down exclusively from the mother. As a result, male offspring are
an evolutionary dead end. While natural selection actively suppresses
mutations in the mitochondrial DNA (mtDNA) that weaken females, there is
no direct mechanism for weeding out those that weaken males: a
situation that leads to the mother’s curse.
While natural selection actively suppresses mutations in the
mitochondrial DNA (mtDNA) that weaken females, there is no direct
mechanism for weeding out those that weaken males: the situation that
makes the mother’s curse possible.
Maulik R Patel, Ganesh K Miriyala, Aimee J Littleton, Heiko Yang, Kien
Trinh, Janet M Young, Scott R Kennedy, Yukiko M Yamashita, Leo J
Pallanck, Harmit S Malik. A mitochondrial DNA hypomorph of cytochrome oxidase specifically impairs male fertility inDrosophila melanogaster. eLife, 2016; 5 DOI: 10.7554/eLife.16923
Mitochondria.Credit: National Institutes of Health
This unique snail species lives just beside black smokers that are churning out superheated water exceeding 350°C. Has also harnessed the power of chemosynthesis, housing endosymbiotic bacteria in an enlarged part of its gut. This produces the energy it needs. it has a food factory inside its body and doesn’t even need to feed! This is likely the reason it can grow to about 45mm in size, when most of its close relatives without endosymbionts are only 15mm or smaller.