Marcellus, M. | bioRxiv Science

bioRxiv2026

MDA-MB-231 cell morphology influences chemotactic sensing of CXCL12 gradients in type 1 bovine collagen matrix

Chemotaxis plays a critical role in the metastatic progression of breast cancer. The chemokine CXCL12 is well recognized as an essential component of chemotactic migration in triple-negative breast cancer (TNBC) cells in vivo. The purpose of this study is to determine how the highly metastatic TNBC cell line, MDA-MB-231, migrates in response to well-defined CXCL12 gradients in vitro. Traditional 2D transwell migration assays were optimized to gauge the MDA-MB-231 cells responsiveness to various CXCL12 concentrations. The optimum chemoattractant concentrations were applied to a commercially available 3D chemotaxis assay as stable linearly diffused gradients. Cells were embedded in type 1 bovine collagen at two different collagen concentrations, and individual unlabeled cells were monitored for 24 hours using brightfield microscopy. Time-lapse videos were used to track cell movement and shape. Quantitative data analysis was performed using an automated tracking software to measure chemotactic parameters based on cell morphology. MDA-MB-231 cells were responsive to CXCL12 concentrations greater than 200 ng/mL in 2D and 3D systems. In 3D systems, significant directed migration was observed in denser collagen matrices. It was observed that in 3D matrices a range of cell morphologies was present. Therefore, chemotaxis was evaluated as a function of cell shape revealing some differences between sub cellular populations. Our findings show the cells shape influences the chemotactic sensing towards CXCL12 gradients.

cell biology↗

bioRxiv2023

Direct and indirect fitness effects of competition limit evolution of allelopathy in an invading plant

O_LIInvading species encounter novel communities of consumers, pathogens, and competitors. Both phenotypic plasticity and rapid evolution can facilitate invasion across these heterogenous communities. However, the rate and extent of adaptive evolution on contemporary timescales can be constrained by adaptive phenotypic plasticity and the genetic architecture of traits under selection. C_LIO_LIWe measured phenotypic plasticity and quantified genetic variation for growth, leaf chlorophyll a (Chl a) and glucosinolates, and lifetime fitness among 23 naturally inbred seed families of Alliaria petiolata (garlic mustard) collected across its invasive range in eastern North America. After growing a self-pollinated generation in a uniform common garden to reduce maternal effects, we reared second-generation plants in a two-year greenhouse and field experiment with naive soil from an uninvaded habitat. We estimated selection gradients and causal factors affecting lifetime fitness when reared alone, with an intraspecific competitor, and under interspecific competition with naive Acer saccharum (sugar maple) saplings. C_LIO_LIWe defined Total Metabolite Production (TMP) as the first principal component of Chl a and glucosinolate concentrations, accounting for 84% of variation in these two traits. TMP was significantly plastic across growing environments (p < 0.001) with limited broad-sense heritability (H2 = 2.91; p = 0.08). Path analysis revealed that plastic phenotypes with higher TMP had an indirect positive effect on A. petiolata fitness via a direct, negative effect on performance of A. saccharum competitors. In contrast, the second principal component defined Relative Glucosinolate Investment (RGI), which was significantly heritable (H2 = 16.91, p < 0.001) with no detectable plasticity across treatments. Variation in RGI among A. petiolata genotypes had a direct, positive effect on A. saccharum performance and an indirect negative effect on A. petiolata fitness. C_LIO_LISynthesis. Adaptive evolution of allelopathy during invasion has been constrained by (i) a lack of heritable genetic variation for allelopathy, (ii) high plasticity for TMP across competition treatments, and (iii) selection for lower RGI under interspecific and intraspecific competition. As an alternative to eco-evolutionary feedbacks, plasticity in TMP may be an overlooked explanation for variable performance of A. petiolata across its introduced range. C_LI

ecology↗