Biology subjects

Laaksonen, T.

Publications and source records attributed to Laaksonen, T..

8 recordsLinked to original sources

bioRxiv2026

3D-Printable and Cytocompatible Hydrogel from Acinetobacter baylyi ADP1 Extracellular Matrix

Tissue engineering has advanced significantly, yet multicomponent hydrogels inspired by the compositional complexity of natural extracellular matrices (ECMs) are still underexplored. Most current hydrogels are based on single-component formulations, which can limit their biochemical and mechanical versatility. Developing synthetic multicomponent hydrogels remains challenging because it requires the controlled integration of multiple functional groups within a single material platform. Here, a biologically driven strategy is introduced by leveraging Acinetobacter baylyi ADP1, a bacterium that naturally produces extracellular polymeric substances (EPS) composed of a multicomponent matrix of polysaccharides and proteins. Through three-day cultivation and a simple extraction method, a hydrogel is obtained that can be methacrylated and photocrosslinked using red or blue light. This hydrogel is porous, cytocompatible, 3D-bioprintable, injectable, and undergoes rapid gelation for in situ crosslinking. This work highlights the potential of using bacterial-derived multicomponent hydrogels for biofabrication.

bioengineering↗

bioRxiv2026

DNA origami uptake in Y-79 retinoblastoma cells driven by oligolysine coating

DNA origami nanoparticles (DONs) are attractive nanocarriers of controllable size, shape and addressability that have potential for treating eye diseases by overcoming ocular barriers. However, suboptimal physiological stability and poor cell uptake due to the negative charge may limit their use. Previous reports show that electrostatic complexation of DONs with cationic PEG-oligolysine block-copolymers like PEG5K-K10 can improve structural integrity and promote cell internalization. Here, we investigated a dual approach of PEG5K-K10 coatings and PL3 targeting peptides to improve uptake of 24-helix bundle (24HB) DONs into Y-79 retinoblastoma cells. Uptake studies revealed that PEG5K-K10 was essential for DON uptake in Y-79 cells, as uptake only occurred upon exceeding a distinct PEG5K-K10 amount. Longer exposure times or increased polymer amounts improved cell association. However, no beneficial effect of PL3 was observed. While free PEG5K-K10 reduced cell viability at higher concentrations (IC50 36.8 {micro}M), coated DONs were well-tolerated. Furthermore, single particle tracking in ex vivo porcine eyes revealed comparable vitreal mobility for uncoated and coated 24HB, with a slight decrease at higher coating amounts. Our findings highlight that PEG5K-K10 can enhance ocular cell uptake without limiting nanoparticle diffusivity in the vitreous, and support further optimization of DONs for ocular drug delivery.

biochemistry↗

bioRxiv2025

Biomass-derived Lignin Nanoparticles for the Sustained Delivery of Vascular Endothelial Growth Factor-C

Vascular Endothelial Growth Factor C (VEGFC) is a promising biological drug, as preclinical studies have shown its potential in treating a variety of conditions, including myocardial infarction and neurodegenerative diseases. For lymphedema, a disease that currently can only be treated symptomatically, adenoviral VEGFC gene therapy has been evaluated up to phase II studies. However, the AdVEGFC is rapidly inactivated by the immune system, and alternative delivery methods might yield better results. Thus, we wanted to investigate the synthesis, characterization, and stability of lignin nanoparticles (LNPs) as carriers for VEGFC. As biomass-derived lignin nanoparticles provide a sustainable, cost-effective, and tunable platform for drug delivery, with the potential to enhance drug stability and release, lignin was extracted from wood biomass derived from grape shoots using the organosolv method and subsequently synthesized into nanoparticles. The resulting lignin nanoparticles (LNPs), with an average size of 142{+/-}62 nm and a zeta potential of -40{+/-}8 mV, were characterized through comprehensive techniques, including spectroscopy and microscopy, to gain insights into their structural and morphological properties. Furthermore, the loading and release efficiency of VEGFC onto LNPs were evaluated, demonstrating effective loading and controlled release. Stability tests in plasma and cell proliferation/viability assessments using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay were conducted to assess biocompatibility and therapeutic potential. Our data shows that VEGFC is a relatively stable protein and that the primary advantage of nanoparticle-based delivery would be to delay release as opposed to protect VEGFC from degradation/inactivation. Graphical AbstractFlow chart of the generation and analysis of biomass-derived VEGFC-loaded lignin nanoparticles. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/649697v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@1476841org.highwire.dtl.DTLVardef@10d861corg.highwire.dtl.DTLVardef@dfa209org.highwire.dtl.DTLVardef@72c81_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2024

Fluorescence Anisotropy Analysis of the Interaction between Doxorubicin and DNA Origami Nanostructures

Owing to doxorubicins high DNA binding affinity, doxorubicin-loaded DNA origami nanostructures (DOX-DONs) are promising nanocarriers against cancer. However, understanding the interactions between doxorubicin (DOX) and DNA origami nanostructures (DONs) is important to ensure the quality of DOX-DONs. This interaction is often taken for granted and the influence of DOX loading conditions is poorly characterized. Exploiting the inherent fluorescence of DOX, steady-state and time-resolved fluorescence anisotropy spectroscopy techniques are used for characterizing non-destructively the binding between DOX and DONs, and the purity of formed complexes. The difference in fluorescence anisotropy between free DOX and DOX-DONs confirms the DOX-DON complex formation. Further, at loading ratios of DOX to DNA base pairs > 0.5, homo-Forster resonance energy transfer (homo-FRET) between closely packed DOX molecules is observed. Moreover, time-resolved anisotropy reveals DOX aggregation on DONs at high loading ratios > 1. For loading ratios > 0.1, spin-filtration to remove excess free DOX is efficient and necessary, though at loading ratios > 1 some DOX aggregates remain attached to the DONs. In summary, fluorescence anisotropy analysis provides more detailed information and insight into DOX-DONs compared to regularly used fluorescence intensity-based characterization methods, and these results can help designing more efficient and safer DNA intercalator-based nanocarriers.

biochemistry↗

bioRxiv2023

A gradual migratory divide determines not only the direction of migration but also migration strategy of a social migrant bird

Migratory divides separate populations of migratory animals, facilitating the evolution of intraspecific differences in migration strategies. The optimal migration theory suggests differing migration strategies for birds using different flyways (with different habitats), but the knowledge regarding the impact of the flyway to the individual migration strategies is scarce. We used satellite tracking and neckband resightings to unravel the structure of the migratory divide between two European flyway populations of greylag geese Anser anser. We modelled satellite tracking data using Gaussian processes to study migration strategies of birds using different flyways. The mean posterior probability for an individual to migrate along the Western Flyway decreased gradually from 0.98 to 0.06 within the Baltic Sea coast, revealing a gradual migratory divide. In addition, migration strategies differed between the flyways. The birds using Western Flyway migrated earlier in autumn, performed longer annual migration and made a clear stopover during migration, whereas the birds using Central Flyway flew directly to their wintering sites. The gradual migratory divide that also divided migration strategies provides exciting insights to ecological and evolutionary factors behind migratory divides. Gaussian processes enabled modelling of detailed migration strategies, encouraging their future usage in movement ecology.

ecology↗

bioRxiv2022

When and where to count? Implications of migratory connectivity and non-breeding distribution to population censuses in a migratory bird population

Migratory connectivity is a metric of the co-occurrence of migratory animals originating from different breeding sites, and like their spatio-temporal distributions, can vary substantially during the annual cycle. Together, both these properties affect the optimal times and sites of population censusing. We tracked taiga bean geese (Anser fabalis fabalis) during 2014-2021 to study their migratory connectivity and non-breeding movements, and determine optimal periods to assess the size of their main flyway population. We also compared available census data with tracking data, to examine how well two existing censuses covered the population. Daily Mantels correlation between breeding and non-breeding sites lay between 0 and 0.5 during most of the non-breeding season, implying birds from different breeding areas were not strongly separated other times in the annual cycle. However, the connectivity was higher among birds from the westernmost breeding areas compared to the birds breeding elsewhere. Daily Minimum Convex Polygons showed tracked birds were highly aggregated at census times, confirming their utility. The number of tracked birds absent at count sites during the censuses however exceeded numbers double-counted at several sites, indicating that censuses might have underestimated the true population size. Our results show that connectivity can vary in different times during the non-breeding period, and should be studied throughout the annual cycle. Our results also confirm previous studies, which have found that estimates using marked individuals usually produce higher population size estimates than total counts. This should be considered when using total counts to assess population sizes in the future.

ecology↗

bioRxiv2021

Population differences in the length, early-life dynamics, and heritability of telomeres among European pied flycatchers

Telomere length and shortening rate are increasingly used as biomarkers for long-term costs in ecological and evolutionary studies because of their relationships with survival and fitness. Both early-life conditions and growth, and later-life stressors can create variation in telomere shortening rate. Studies on between- population telomere length and dynamics are scarce, despite the expectation that populations exposed to varying environmental constraints would present divergent telomere length patterns. The pied flycatcher (Ficedula hypoleuca) is a passerine bird breeding across Eurasia (from Spain to western Siberia) and migrating through the Iberian Peninsula to spend the non-breeding period in sub-Saharan Africa. Thus, different populations show marked differences in migration distance. We studied the large-scale variation of telomere length and early-life dynamics in the pied flycatcher by comparing six European populations across a north- south gradient (Finland, Estonia, England, and Spain) predicting negative effect of migration distance on adult telomere length, and of nestling growth on nestling telomere dynamics. There were clear population differences in telomere length, with English birds from mid-latitudes having the longest telomeres. Telomere length did not thus show consistent latitudinal variation and was not linearly linked to differences in migration distance. Early-life telomere shortening rate tended to vary between populations. Fast growth was associated with shorter telomeres in the early life, but faster nestling growth affected telomeres more negatively in northern than southern populations. While the sources of between-population differences in telomere-related biology remain to be more intensively studied, our study illustrates the need to expand telomere studies at the between-population level.

zoology↗

bioRxiv2019

Inter-specific variation of maternal thyroid hormones associate with migration, mode of development, and captivity: a phylogenetic comparative analysis

Life-history traits vary largely across species and several physiological parameters have been proposed to be associated with life-history variation, such as metabolic rates, glucocorticoids, and oxidative stress. Interestingly, the association between thyroid hormones (THs) and life history variation has never been considered, despite a close interaction between THs and these physiological traits. Because of the crucial effects on embryonic development, THs can also induce transgenerational plasticity when transferred to developing offspring, for instance, via egg yolks in birds. In this study, we compiled a unique data set of maternal yolk THs in 34 bird species across 17 families and 6 orders, and tested for associations with various life-history traits. Our phylogenetic mixed models indicated that both concentrations and total amounts of the two most important forms of THs (T3 and T4) were higher in the eggs of migratory species than in those of resident species, and that there were higher total amounts of T3 in the eggs of precocial species than in those of altricial species. However, maternal THs did not show clear associations with any traits of the pace-of-life syndrome, such as developmental duration, growth rate, or lifespan. When taking environmental factors into account, we found that captive species deposited higher TH concentrations and larger amounts in the egg yolks than wild species. These findings suggest that maternal THs are likely involved in the evolution of life-history variation, or vice versa.

evolutionary biology↗