We used otolith chemistry to test and complement current hypotheses regarding habitat use and connectivity between Dissostichus mawsoni sub-populations in Area 48 of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Sagittal otoliths from 45 fish sampled near the South Orkney Islands were analysed. Their elemental (Li, Na, Mg, Cr, Mn, Sr, Sn, and Ba relative to Ca) and isotopic (δ18O and δ13C) signatures were examined in both the nuclear and marginal regions, representing juvenile and adult stages. Potential nursery habitats were geo-located by comparing observed and expected δ18O values. Chemical differences between the nuclear and marginal regions indicated ontogenetic migrations to deeper offshore habitats, suggesting a distinct habitat shift between 11 and 13 years of life. The data supported the existence of two nursery origins contributing to the study area’s population. However, the exact locations of these origins remain unclear and did not provide direct support for the hypotheses currently under consideration by the CCAMLR. Therefore, further assessment of the connectivity between nursery and adult habitats, as well as spawning site fidelity, is necessary before ruling out alternative hypotheses.

• Book : 14(1)
• Pub. Date : 2025
• Page : pp.7
• Keyword :

ABSTRACT

Aim

The drivers of shrubland biomass in the Mediterranean‐Climate Region of southern California are not well understood. We aim to fill a critical information gap for resource managers of shrub‐dominated landscapes who need to estimate shrub recovery post‐fire, track and monitor carbon storage and sequestration, and determine the tradeoff in restoration goals between prioritising carbon storage and species richness.

Location

Southern California, USA.

Methods

Using data from 143 field plots located in 11 fire scars (ranging from 1 to 12 years old), we used Linear Mixed Models to assess the contribution of temporal and environmental variables, along with post‐fire regeneration strategies of shrub species to explain patterns of aboveground shrub biomass.

Results

We identified four key findings: (1) shrub biomass increased with time since last fire and the proportion of resprouting species, and decreased with distance to coast and solar radiation; (2) species with the ability to resprout (obligate resprouter and facultative seeders) contributed greater biomass at all post‐fire time periods and locations when compared with obligate seeders; (3) we found higher average biomass contributed by both obligate seeder and obligate resprouter species in plots closer to the coast than interior plots; and (4) fourth, we found a significant positive relationship between woody shrub species richness and biomass.

Conclusions

The findings of this study of biomass at a regional scale and using shrublands of multiple stand ages can help support natural resource management decision‐making for shrub‐dominated landscapes-including estimating biomass recovery post‐fire, quantifying carbon storage and setting goals for shrubland restoration.

• Book : 31(1)
• Pub. Date : 2025
• Page : pp.e13964
• Keyword :

• Book : 156(pb)
• Pub. Date : 2025
• Page : pp.104836
• Keyword :

• Book : 10(1)
• Pub. Date : 2025
• Page : pp.101661
• Keyword :

BACKGROUND:

Cerebral hypoperfusion is associated with vascular brain injury and neurodegeneration, but their longitudinal relationship is largely unknown, especially in healthy older adults.

METHODS:

We investigated the longitudinal relationship between cerebral hemodynamics and subclinical vascular brain disease in community-dwelling older adults without stroke or dementia at baseline. Participants underwent brain magnetic resonance imaging scans every 3 to 4 years between 2005 and 2016. Cerebral blood flow (CBF) was measured through 2-dimensional phase-contrast magnetic resonance imaging; the cerebrovascular resistance index (CVRi) was defined as the ratio of mean arterial blood pressure to total CBF. Simultaneous progression in subclinical brain disease was evaluated through repeated magnetic resonance imaging assessment of white matter hyperintensities (WMH), cerebral microbleeds, lacune, and brain atrophy. The longitudinal relationship was estimated using generalized estimating equations, with adjustment for age, sex, smoking habits, body mass index, systolic blood pressure (for CBF measures), lipid level, history of diabetes and cardiovascular disease, and the baseline burden of magnetic resonance imaging markers.

RESULTS:

Among 3623 older adults (mean age, 61.4±9.3 years; 54.6% women), large decreases and increases in CBF and increases in CVRi over time were associated with white matter hyperintensity progression. The risk ratios for white matter hyperintensity progression were 1.36 (95% CI, 1.19-1.55) for large decreases in total CBF (lowest quartile), 1.02 (95% CI, 0.91-1.14) for moderate decreases (second quartile), and 1.28 (95% CI, 1.14-1.45) for large increases (highest quartile), compared with stable CBF (third quartile). The corresponding risk ratios for changes in CVRi were 1.13 (95% CI, 1.00-1.30), 1.25 (95% CI, 1.09-1.43), and 1.33 (95% CI, 1.16-1.52) for the second to fourth (versus lowest) quartiles, respectively, showing a dose-response relationship. The changes in CBF also demonstrate a similar U-shaped association with the progression of brain atrophy and incident microbleeds, whereas increases in CVRi were associated with lower microbleed risk.

CONCLUSIONS:

Longitudinal changes in CBF and CVRi may capture distinct pathophysiologies linking cerebral hemodynamics to subclinical brain disease, extending beyond single-time point measurements.

• Book : 56(1)
• Pub. Date : 2025
• Page : pp.95-104
• Keyword :

• Book : 64(1)
• Pub. Date : 2025
• Page : pp.18-18
• Keyword :

ABSTRACT

The isolated river drainages of eastern North America serve as a natural laboratory to investigate the roles of allopatry and secondary contact in the evolutionary trajectories of recently diverged lineages. Drainage divides facilitate allopatric speciation, but due to their sensitivity to climatic and geomorphological changes, neighboring rivers frequently coalesce, creating recurrent opportunities of isolation and contact throughout the history of aquatic lineages. The freshwater mussel Quadrula quadrula is widely distributed across isolated rivers of eastern North America and possesses high phenotypic and molecular variation across its range. We integrate sequence data from three genomes, including female‐ and male‐inherited mitochondrial markers and thousands of nuclear encoded SNPs with morphology and geography to illuminate the group's divergence history. Across contemporary isolated rivers, we found continuums of molecular and morphological variation, following a pattern of isolation by distance. In contact zones, hybridization was frequent with no apparent fitness consequences, as advanced hybrids were common. Accordingly, we recognize Q. quadrula as a single cohesive species with subspecific variation (Q. quadrula rumphiana). Demographic modeling and divergence dating supported a divergence history characterized by allopatric vicariance followed by secondary contact, likely driven by river rearrangements and Pleistocene glacial cycles. Despite clinal range‐wide variation and hybridization in contact zones, the process‐based species delimitation tool delimitR, which considers demographic scenarios like secondary contact, supported the delimitation of the maximum number of species tested. As such, when interpreting species delimitation results, we suggest careful consideration of spatial sampling and subsequent geographic patterns of biological variation, particularly for wide‐ranging taxa.

• Book : 34(1)
• Pub. Date : 2025
• Page : pp.e17572
• Keyword :

Abstract

The influence of biomass burning (BB) aerosols arising from wildfires and agricultural fires on the transient coupled evolution of El Niño-Southern Oscillation (ENSO) is explored in Community Earth System Model, version 2 (CESM2). For both El Niño and La Niña, two 20-member ensembles are generated from initial states that are predisposed to evolve into ENSO events. For each ENSO phase, one ensemble is forced with the observed BB emissions during satellite-era ENSO events while the other is forced with a climatological annual cycle, with the responses to anomalous BB emissions estimated from interensemble differences. It is found that the regional responses to anomalous BB emissions occur mainly during boreal fall, which is also the time of the climatological seasonal maximum in emissions. Transient responses are identified in precipitation, clouds, and radiation in both the tropics and extratropics. At the onset of El Niño, these include increased precipitation in the northern branch of the intertropical convergence zone (ITCZ) and an enhancement of cloud albedo and amount across the Maritime Continent and eastern subtropical Pacific Ocean. Additional responses are identified through the course of El Niño and successive La Niña events, the net effect of which is to strengthen sea surface temperature (SST) anomalies in the eastern Pacific Ocean during El Niño and warm the tropical Pacific Ocean during La Niña. These responses improve the simulation of ENSO power, diversity, and asymmetry in CESM2.

Significance Statement

Biomass burning emissions from both wildfires and agricultural fires during ENSO act as a climate feedback, as they are both driven by fire weather anomalies tied to ENSO and influence clouds, radiation, and precipitation on a global scale. While the largest biomass burning (BB) emissions emanate mainly from Indonesia, other regions also exhibit systematic responses. When simulated in CESM2, the emissions collectively impact the flows of energy across the tropical Pacific Ocean in a spatially and temporally complex fashion, with the net effect of improving CESM2’s simulation of ENSO events.

• Book : 38(1)
• Pub. Date : 2025
• Page : pp.27-39
• Keyword :

Background:

Radiosensitivity remains an important factor affecting the clinical outcome of radiotherapy for non-small cell lung cancer (NSCLC). Liver kinase B1 (LKB1) as a tumor suppressor, is one of the most commonly mutated genes in NSCLC. However, the role of LKB1 on radiosensitivity and the possible mechanism have not been elucidated in the NSCLC. In this study, we investigated the regulatory function of LKB1 in the radiosensitivity of NSCLC cells and its possible signaling pathways.

Methods:

After regulating the expression of LKB1, cell proliferation was determined by Cell Counting Kit-8 (CCK-8) assay. The flow cytometry assay was used to analyse cell cycle distribution. Survival fraction and sensitization enhancement ratio (SER) were generated by clonogenic survival assay. Western blot analysis was used to assess expression levels of LKB1, p53, p21, γ-H2AX and p-Chk2.

Results:

Our study found that when the NSCLC cells were exposed to ionizing radiation, LKB1 could inhibit NSCLC cell proliferation by promoting DNA double strand break and inducing DNA repair. In addition, LKB1 could induce NSCLC cells G1 and G2/M phase arrest through up-regulating expression of p53 and p21 proteins.

Conclusion:

This current study demonstrates that LKB1 enhances the radiosensitivity of NSCLC cells via inhibiting NSCLC cell proliferation and inducing G2/M phase arrest, and the mechanism of cell cycle arrest associated with signaling pathways of p53 and p21 probably.

• Book : 25(3)
• Pub. Date : 2025
• Page : pp.351-358
• Keyword :

• Book : 301(1)
• Pub. Date : 2025
• Page : pp.108033
• Keyword :