Antarctic
krill
is
a
species
with
fundamental
importance
for
the
Southern
Ocean
ecosystem.
Their
large
biomass
and
synchronized
movements,
like
diel
vertical
migration
(DVM),
significantly
impact
ecosystem
structure
biological
carbon
pump.
Despite
decades
of
research,
mechanistic
basis
DVM
remains
unclear.
Circadian
clocks
help
organisms
anticipate
daily
environmental
changes,
optimizing
adaptation.
In
this
study,
we
used
recently
developed
activity
monitor
to
record
swimming
individual,
wild-caught
under
various
light
conditions
across
different
seasons.
Our
data
demonstrate
how
circadian
clock,
in
combination
light,
drives
distinct
bimodal
pattern
activity,
which
could
facilitate
ecologically
important
behavioral
patterns,
such
as
DVM.
Rapid
damping
flexible
synchronization
indicate
that
clock
adapted
life
at
high
latitudes
seasonal
recordings
suggest
clock-based
mechanism
timing
processes.
findings
advance
our
understanding
high-latitude
adaptation
key
species.
The
development
of
long-read
sequencing
is
promising
for
the
high-quality
and
comprehensive
de
novo
assembly
various
species
around
world.
However,
it
still
challenging
assemblers
to
handle
thousands
genomes,
tens
gigabase-level
sizes,
terabase-level
datasets
efficiently,
which
a
bottleneck
large-scale
studies.
A
major
cause
read
overlapping
graph
construction
that
state-of-the-art
tools
usually
have
cost
terabyte-level
RAM
space
days
large
genomes.
Such
lower
performance
scalability
are
not
suited
numerous
samples
being
sequenced.
Herein,
we
propose
xRead,
novel
iterative
approach
achieves
high
performance,
scalability,
yield
simultaneously.
Under
guidance
its
coverage-based
model,
xRead
converts
read-overlapping
heuristic
read-mapping
incremental
tasks
with
highly
controllable
faster
speed.
It
enables
processing
very
(such
as
1.28
Tb
Ambystoma
mexicanum
dataset)
less
than
64
GB
obviously
time
costs.
Moreover,
benchmarks
suggest
can
produce
accurate
well-connected
graphs,
also
supportive
kinds
downstream
strategies.
able
break
through
lays
new
foundation
assembly.
This
tool
number
from
genomes
may
play
important
roles
in
many
PeerJ,
Год журнала:
2025,
Номер
13, С. e19054 - e19054
Опубликована: Фев. 26, 2025
Crustacean
zooplanktons
are
key
secondary
and
tertiary
producers
in
marine
ecosystems,
yet
their
genomic
resources
remain
poorly
understood.
To
advance
biodiversity
research
on
crustacean
zooplankton,
this
study
evaluated
the
effectiveness
of
genome
skimming,
a
method
that
assembles
genetic
regions,
including
mitogenome,
from
shotgun
sequencing
data.
Because
small
amount
DNA
available
is
limitation
zooplankton
genetics,
different
input
amounts
(1
pg–10
ng)
were
prepared
for
library
construction
skimming
using
two
large
species:
Euphausia
pacifica
(Euphausiacea)
Calanus
glacialis
(Copepoda).
Additionally,
de
novo
assembly
was
used
to
obtain
long
contigs
short
reads
because
reference-guided
can
not
be
applied
all
zooplankton.
Evaluation
raw
sequence
showed
increased
proportions
high-quality
distinct
(low
duplication
levels)
inputs.
By
contrast,
low
quality
high
observed
≤
10
pg
samples,
owing
amplification
cycles.
Complete
mitogenomes,
37
genes,
successfully
retrieved
≥
(
E.
)
100
C.
DNA.
Despite
estimated
sizes
these
species,
only
1
3
M
sufficient
mitogenome
,
respectively.
Nuclear
ribosomal
repeats
histone
identified
assembled
contigs.
As
obtaining
(≥
pg)
feasible
even
powerful
approach
robust
phylogenetics
population
genetics
Nature Communications,
Год журнала:
2025,
Номер
16(1)
Опубликована: Март 5, 2025
We
report
156
sediment
metagenomes
from
Adélie
penguin
(Pygoscelis
adeliae)
colonies
dating
back
6000
years
along
the
Ross
Sea
coast,
Antarctica,
and
identify
marine
terrestrial
eukaryotes,
including
locally
occurring
bird
seal
species.
The
data
reveal
spatiotemporal
patterns
of
diet,
spatial
in
consumption
cnidarians,
a
historically
overlooked
component
diets.
Relative
proportions
mitochondrial
lineages
detected
at
each
colony
are
comparable
to
those
previously
reported
bones.
Elevated
levels
nucleotide
diversity
upper
stratigraphic
samples
several
active
consistent
with
recent
population
growth.
Moreover,
highest
recovered
surface
layers
two
largest
colonies,
indicating
that
sedaDNA
could
provide
estimates
for
former
size
abandoned
colonies.
SedaDNA
also
reveals
prior
occupation
Cape
Hallett
site
by
southern
elephant
(Mirounga
leonina),
demonstrating
how
can
detect
faunal
turnover
events
Antarctica
driven
past
climate
or
sea
ice
conditions.
Low
rates
cytosine
deamination
indicate
exceptional
preservation
within
region,
suggesting
there
is
high
potential
recovering
much
older
records
local
Pleistocene
sediments.
Applied Sciences,
Год журнала:
2025,
Номер
15(7), С. 3563 - 3563
Опубликована: Март 25, 2025
The
first
luciferase
from
Antarctic
krill
(LAK)
was
cloned
and
successfully
expressed
in
Escherichia
coli
BL21(DE3).
LAK
exhibits
the
unique
ability
to
emit
bright
violet
fluorescence
at
an
emission
wavelength
of
350
nm,
which
represents
lowest
reported
bioluminescence
for
luciferases.
However,
its
low
thermal
stability
poses
a
limitation
broader
application.
In
this
study,
we
employed
rational
design
approach
introduce
three
pairs
artificial
disulfide
bonds
into
LAK.
Circular
dichroism
(CD)
analysis
revealed
that
introduction
resulted
significant
increase
secondary
structural
content
α-helices
β-sheets
compared
wild-type
(WT)
enzyme.
these
modifications
did
not
influence
spectrum.
Among
resultant
mutant
strains,
two
exhibited
markedly
enhanced
stability.
Notably,
Mut2
demonstrated
6.18-fold
half-life
50
°C.
Molecular
docking
studies
indicated
D-fluorescein
can
form
additional
hydrogen
with
surrounding
amino
acid
residues
(A323,
T347,
K534).
energies
between
enzyme
substrate
WT
were
−19.5
kcal/mol
−23.4
kcal/mol,
respectively,
thereby
establishing
strong
interactions
within
catalytic
pocket
region.
These
likely
contribute
2.92-fold
improvement
affinity,
as
evidenced
by
reduced
Michaelis–Menten
constant
(Km).
Our
activity
analyses
linker
region
N-
C-domains
plays
crucial
role
overall
Furthermore,
C-terminus
does
participate
substrate-binding
catalysis;
local
excessive
rigidity
found
restrict
release
AMP
product,
negatively
impacting
activity.
findings
offer
new
insights
mutagenesis
luciferases
pave
way
further
optimization
various
biotechnological
applications.
Antarctic
krill
is
a
species
with
fundamental
importance
for
the
Southern
Ocean
ecosystem.
Their
large
biomass
and
synchronized
movements,
like
diel
vertical
migration
(DVM),
significantly
impact
ecosystem
structure
biological
carbon
pump.
Despite
decades
of
research,
mechanistic
basis
DVM
remains
unclear.
Circadian
clocks
help
organisms
anticipate
daily
environmental
changes,
optimizing
adaptation.
In
this
study,
we
used
recently
developed
activity
monitor
to
record
swimming
individual,
wild-caught
under
various
light
conditions
across
different
seasons.
Our
data
demonstrate
how
circadian
clock,
in
combination
light,
drives
distinct
bimodal
pattern
activity,
which
could
facilitate
ecologically
important
behavioral
patterns,
such
as
DVM.
Rapid
damping
flexible
synchronization
indicate
that
clock
adapted
life
at
high
latitudes
seasonal
recordings
suggest
clock-based
mechanism
timing
processes.
findings
advance
our
understanding
high-latitude
adaptation
key
species.