Science - USA (2022-05-27)

DEVELOPMENT

Demethylation controls

development

FTO was the first discov-

ered RNA demethylase that

reverses messenger RNA

N^6 -methyladenosine (m^6 A)

modification. Despite numerous

past studies, the physiological

substrates of FTO in mammalian

development remain unclear.

We i et al. uncovered RNA tran-

scribed from long-interspersed

element-1 (LINE1), one of the

most abundant mammalian

retrotransposons, as a major

substrate of FTO in mouse

embryonic stem cells and mouse

tissues. m^6 A demethylation by

FTO regulates the LINE1 RNA

level, which shapes local and

global chromatin state. Deletion

of Fto in cells deactivates LINE1-

containing genes by repressing

intragenic LINE1 RNA. This

FTO-LINE1 RNA axis also affects

mouse oocyte and embryonic

development. —BAP

Science, abe9582, this issue p. 968

ATMOSPHERE

Powerful oxidants

in the atmosphere

Hydrotrioxides (ROOOHs)

have intrigued the atmospheric

chemistry community because

of their strong oxidizing proper-

ties and theoretical predictions

that they could form in atmo-

spherically relevant RO 2 + OH

reactions. Much of the work to

date has focused on CH 3 O 2 , but

this chemistry has been found to

play a minor role. Using a mass

spectrometry–based scheme

for direct detection and ab initio

calculations supplemented by

global modeling, Berndt et al.

showed that ROOOHs could form

routinely for heavier RO 2 and have

appreciable lifetimes. Potentially

detectable steady-state concen-

trations in the atmosphere were

established. This work draws

attention to an important class of

strong oxidizing agents previously

disregarded in atmospheric kinet-

ics models. —YS

Science, abn6012, this issue p. 979

CATA LYS I S

Nanoparticle response

to redox conditions

In heterogeneous catalysts, the

interaction between transition

metal nanoparticles and their

oxide supports can be mainly

that of absorbed species mov-

ing between metal and oxide

surfaces. However, substantial

restructuring can occur. For plat-

inum nanoparticles on titania,

reaction conditions can cause

the oxide support to encapsulate

and deactivate the metal. Frey

et al. used transmission elec-

tron microscopy to image this

system interacting with 1 bar of

a hydrogen and oxygen mixture

forming water. The effects of this

redox-active chemical environ-

ment included destabilization of

the encapsulation layer, as well

as platinum particles forming

twin planes and directionally

migrating across the titania

surface. —PDS

Science, abm3371, this issue p. 982

IMMUNOLOGY
CD8a keeps T cells
humming along
In addition to acting as a T cell
lineage marker, the CD8 het-
erodimer acts as a co-receptor to
enhance T cell receptor (TCR) sig-
naling after antigen stimulation.
Whether CD8 plays any other
antigen-independent functions
is unclear. Zheng et al. found that
inducible deletion of CD8a in mice
resulted in a loss of both naïve
and memory CD8 T cell quies-
PHOTO: ANETTE MOSSBACHER/ALAMY STOCK PHOTO cence, which is essential for their

SCIENCE sciencemag.org

IN SCIENCE JOURNALS

RESEARCH

GLACIAL CYCLES

Solar controller

B

efore about 1.25 million years ago, glacial cycles reflected the 40,000-year obliquity insola-

tion cycle, whereas over the past 800 thousand years, glacial cycles have been paced

by the 100,000-year eccentricity cycle. What about the role of the 23,000-year cycle of

precession? Barker et al. present a 1.7-million-year record showing that glacial termination

has depended mostly on precession for the past million years. That change seems to be a

function of ice sheet size. —HJS Science, abm4033, this issue p. 961

27 MAY 2022 • VOL 376 ISSUE 6596 957

A record of North Atlantic ice rafting, as shown in the photograph, reveals the effect of precession on

ice sheet variability in the recent geologic past.

Edited by Michael Funk