A simple and efficient method for the long-term preservation of plant cell suspension cultures

In-cell 31P solid-state NMR measurements of the lipid dynamics and influence of exogeneous β-amyloid peptides on live neuroblastoma neuro-2a cells

Non-specific disruption of cellular membranes induced by aggregation of exogeneous β-amyloid (Aβ) peptides is considered a viable pathological mechanism in Alzheimer's disease (AD). The solid-state nuclear magnetic resonance (ssNMR) spectroscopy has been widely applied in model liposomes to provide important insights on the molecular interactions between membranes and Aβ aggregates. Yet, the feasibility of in-cell ssNMR spectroscopy to probe Aβ-membrane interactions in native cellular environments has rarely been tested. Here we report the application of in-cell³¹P ssNMR spectroscopy on live mouse neuroblastoma Neuro-2a (N2a) cells under moderate magic angle spinning (MAS) conditions. Both cell viability and cytoplasmic membrane integrity are retained for up to six hours under 5 kHz MAS frequency at 277 K, which allow applications of direct-polarization ³¹P spectroscopy and ³¹P spin-spin (T₂) relaxation measurements. The ³¹P T₂ relaxation time constant of N2a cells is significantly increased compared with the model liposome prepared with comparable major phospholipid compositions. With the addition of 5 μM 40-residue Aβ (Aβ_1-40) peptides, the ³¹P T₂ relaxation is instantly accelerated. This work demonstrates the feasibility of using in-cell³¹P ssNMR to investigate the Aβ-membrane interactions in the biologically relevant cellular system.

Production of Lectins from Marine Algae: Current Status, Challenges, and Opportunities for Non-Destructive Extraction

Marine algae are an excellent source of novel lectins. The isolation of lectins from marine algae expands the diversity in structure and carbohydrate specificities of lectins isolated from other sources. Marine algal lectins have been reported to have antiviral, antitumor, and antibacterial activity. Lectins are typically isolated from marine algae by grinding the algal tissue with liquid nitrogen and extracting with buffer and alcohol. While this method produces higher yields, it may not be sustainable for large-scale production, because a large amount of biomass is required to produce a minute amount of compound, and a significant amount of waste is generated during the extraction process. Therefore, non-destructive extraction using algal culture water could be used to ensure a continuous supply of lectins without exclusively disrupting the marine algae. This review discusses the traditional and recent advancements in algal lectin extraction methods over the last decade, as well as the steps required for large-scale production. The challenges and prospects of various extraction methods (destructive and non-destructive) are also discussed.

Cryopreserved astrocytes maintain biological properties: Support of neuronal survival and differentiation

BACKGROUND

Astrocytes, one of the main glial cell types, play critical roles in the central nervous system (CNS) development and function, including support of neuronal survival and differentiation, blood brain barrier formation, synapse homeostasis and injury response. Cell isolation and culture techniques have been proved to be a powerful tool to study astrocyte physiology and function. Due to financial constraints and rigid biosafety and ethics rules to use animal models, freezing techniques and the creation of cell banks emerged as alternatives to optimize the use of experimental animals. One of the main challenges, however, of these techniques is to guarantee that conserved cells keep their biological properties.

NEW METHOD

In this work, we characterized morphologically and functionally murine secondary astrocyte cultures that have been submitted to freezing/thawing procedures.

RESULTS

Morphological characterization of SAC (secondary astrocyte culture) and SFAC (secondary frozen-astrocyte culture) did not reveal significant differences on astrocyte morphology, confluence time and cell number along culture period. Functionally, SAC and SFAC did not reveal differences in their potential to support neuronal survival, maturation, neuritogenesis and synapse formation.

CONCLUSIONS

Our results suggest that murine astrocytes that are submitted to freezing/thawing procedure maintain morphological and functional characteristics when compared with non-frozen astrocytes. Thus, this methodological approach is a valuable tool for in vitro research and might allow experimental optimization and reduction of animal use.

Cellular aggregation is a key parameter associated with long term variability in paclitaxel accumulation in Taxus suspension cultures

Plant cell cultures provide a renewable source for synthesis and supply of commercially valuable plant-derived products, particularly for secondary metabolites. However, instability in product yields over multiple passages has hampered the efficient and sustainable use of this technology. Paclitaxel accumulation in Taxus cell suspension culture was quantified over multiple passages and correlated to mean aggregate size, extracellular sugar level, ploidy, and cell cycle distribution. Paclitaxel levels varied approximately 6.9-fold over the six-month timeframe investigated. Of all of the parameters examined, only mean aggregate size correlated with paclitaxel accumulation, where a significant negative correlation (r = - 0.75, p < 0.01) was observed. These results demonstrate the relevance of measuring, and potentially controlling, aggregate size during long term culture passages, particularly for plant suspensions where industrially relevant secondary metabolites are not pigmented to enable rapid culture selection.