Activity Determinants in Linear Spider Venom Peptide Fragments Against MRSA

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  Activity Determinants in Linear Spider Venom Peptide Fragments Against MRSA Abstract Objective: Using neural networks, we previously identified linear fragments of spider venom peptides active against methicillin-resistant Staphylococcus aureus (MRSA). Among them, peptide IX (IWLSLMKFAGKHL-NH 2 ) with a C -terminal amide displayed high antibacterial potency, whereas its non-amidated analogue, peptide X, was inactive. Peptide IX incorporates into zwitterionic multilamellar liposomes of dioleoylphosphatidylcholine (DOPC) without disrupting them, and also into anionic liposomes of dioleoylphosphatidylglycerol (DOPG) mimicking the MRSA cell membrane, leading to bilayer disruption. This study aims to elucidate the reasons for peptide X inactivation.  Methods: According to ¹H NMR spectroscopy, peptide X in water is governed by the ionization of the His12 residue. ³¹P NMR data show that peptide X interacts with DOPC and DOPG membranes. Monte Carlo simulations revealed conformati...

Polar bodies serve as a landmark for anteroposterior axis formation in spiders

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Polar bodies serve as a landmark for anteroposterior axis formation in spiders

Abstract

The early embryogenesis of many spiders involves the formation of a radially symmetric germ disc. While the cells of the rim of this germ disc develops into anterior structures, the center of the disc will form the posteriorly located segment addition zone of the embryo. Therefore, germ disc formation sets the anterior-posterior (AP) body axis of spider embryos. The early spider egg is a spherical structure with no apparent asymmetry. So far it is unclear if the placement of the germ disc is a predetermined or a stochastic process.
For this study, we have re-analyzed early spider embryogenesis and found a link between the position of the polar bodies and the formation of the germ disc. Using cell tracking and time-lapse recordings of live embryos injected with the live cell nuclear stain SPY555-DNA, we show that the germ disc forms opposite to the polar bodies. Our results suggest that germ disc formation in the common house spider Parasteatoda tepidariorum is not a stochastic but a pre-determined process. By analyzing germ disc formation in a basally branching cobweb spider and a curtain-web spider, we provide evidence that the initial process of germ disc placement might be conserved between araneomorph and mygalomorph spider species.
Wang, R., & Pechmann, M. (2025). Polar bodies serve as a landmark for anteroposterior axis formation in spiders. Developmental Biology. https://doi.org/10.1016/j.ydbio.2025.12.006