Caught in the Act: Live-Cell Imaging of Plant Meiosis

Live-cell imaging is a powerful method to obtain insights into cellular processes, particularly with respect to their dynamics. This is especially true for meiosis, where chromosomes and other cellular components such as the cytoskeleton follow an elaborate choreography over a relatively short period of time. Making these dynamics visible expands understanding of the regulation of meiosis and its underlying molecular forces. However, the analysis of meiosis by live-cell imaging is challenging; specifically in plants, a temporally resolved understanding of chromosome segregation and recombination events is lacking. Recent advances in live-cell imaging now allow the analysis of meiotic events in plants in real time. These new microscopy methods rely on the generation of reporter lines for meiotic regulators and on the establishment of ex vivo culture and imaging conditions, which stabilize the specimen and keep it alive for several hours or even days. In this review, we combine an overview of the technical aspects of live-cell imaging in plants with a summary of outstanding questions that can now be addressed to promote live-cell imaging in Arabidopsis and other plant species and stimulate ideas on the topics that can be addressed in the context of plant meiotic recombination.

Network Narratives in Global Cinema: The Shift from Community to Network and Their Narrative Logics

In the backdrop of global interconnection, such films as “Crash”, “Syriana”, and “Babel” drew attention to the six-degrees-of-separation “network narrative.” This type of distributed narrative with multiple access points or discrete threads has long evolved, perhaps since Griffith’s “Intolerance” and via modern masterpieces: Altman’s “Nashville” and “Shortcuts” weave many characters into a portrait of their social ground unmapped by themselves; Bunuel’s “Phantom of Liberty” shifts among characters only through the contingent movement of the camera. These two elements (multiple characters, a floating agent) intermingle now in the way that the protagonist takes the role of the very agent navigating among contingently networked characters in further decentralized directions: “Birdman” centers on the hero’s salvation but many other people around him form and cross small dramas; the protagonist in “Waking Life” shuffles through a dream meeting various people; “Holly Motors” stages a Parisian’s bizarre city odyssey, with the true agent turning out to be a car/cars; “Mysterious Object at Noon” experiments on the ‘exquisite corpse’ relay of a story through different people whom the director encounters while moving around... What does this non-linearity with different causal relations imply? How do mobile agents floating over decentralized events relate to global networks in general? This paper investigates today’s network narratives through an interdisciplinary approach to the notion of network as opposed to community even beyond film narratology. For instance, if the masculine formula of Lacan’s sexuation (all are submitted to the phallic function but for one exception) underlies community, its feminine formula (not all are submitted to the phallic function but there is no exception) works for networking. Community forms the totality of all and an exception that fuels the universal desire to make it utopian, but network has the infinity of drives to (dis)connections dismantling community, yet thereby leaving no exceptional outside. Community is a closed set of subjects who may be ‘abjected’ from it; network is an open whole of endless links along which the subject-abject shift constantly occurs in the mode of being ‘on/off’ rather than ‘in/out.’ In Deleuze’s terms, community works as a “tree-like” vertical system of hierarchical units in the historical trajectory to its perfection, whereas the network creates a “rhizomatic” horizontal movement of molecular forces in non-dialectic, non-linear directions. Foucauldian “discipline” is a key to subjectivation in the community, but it turns into Deleuzian “control” in the network that promotes flexible agency and continuous modulation without exit. As actor-network theorists argue, nothing precedes and exists outside ever-changing networks of relationship. The network narrative will thus be explored as a cinematic symptom of the radical shift from community to network that both society and subjectivity undergo with all the potentials and limitations in our global age.

A Forgotten Corner in Cancer Immunotherapy: The Role of Lipids

In the past decade, cancer immunotherapy has achieved great success owing to the unravelling of unknown molecular forces in cancer immunity. However, it is critical that we address the limitations of current immunotherapy, including immune-related adverse events and drug resistance, and further enhance current immunotherapy. Lipids are reported to play important roles in modulating immune responses in cancer. Cancer cells use lipids to support their aggressive behaviour and allow immune evasion. Metabolic reprogramming of cancer cells destroys the equilibrium between lipid anabolism and catabolism, resulting in lipid accumulation within the tumour microenvironment (TME). Consequently, ubiquitous lipids, mainly fatty acids, within the TME can impact the function and phenotype of infiltrating immune cells. Determining the complex roles of lipids and their interactions with the TME will provide new insight for improving anti-tumour immune responses by targeting lipids. Herein, we present a review of recent literature that has demonstrated how lipid metabolism reprogramming occurs in cancer cells and influences cancer immunity. We also summarise the potential for lipid-based clinical translation to modify immune treatment.

Application of Virtual Reality in Chemical Education Using Intermolecular Force Display System HaptiChem

Virtual reality technology has been recently more intensively applied in chemistry. HaptiChem, which was developed in 2006, is one of the systems appeared in the early stage of this field. It is an intermolecular force display system, which makes it possible to touch and move molecules as feeling intermolecular force in a three-dimensional virtual space by using a haptic device. The functions and graphic display were designed as simple as possible for educational use, so that learner can easily grasp the meaning of the concept of molecular forces. We introduced HaptiChem in chemical education. We held a high school chemistry class with 43 students entitled “Several Forces between Molecules” as being open to the media. The students learned about intermolecular force from a lecture together with experiences of the force using HaptiChem. They asked more questions about intermolecular force during the class than usual. Their answers to the questionnaires after the class indicated that the haptic system promoted curiosity and enhanced learning. The students could learn more effectively by combining with the active feeling with HaptiChem. The high-school teachers evaluated that such a system can more efficiently encourage students to learn and remember things by stimulating their sense of touch. The observations also suggested that a haptic device made it easier to establish three-dimensional perception, which is difficult only with 2D-display. This pilot experiment was performed on 15th March 2007. It was the first attempt at using it in the field of chemical education. The observation was done fourteen years ago. However, since the effectiveness of haptic device in chemical education has not been changed and the interests of the applications have been increased, we decided to report the data we observed, which should be still worth disclosing. We wish to dedicate the results to new developments now and in the future.

The Role of Methionine Residues in the Regulation of Liquid-Liquid Phase Separation

Membraneless organelles are non-stoichiometric supramolecular structures in the micron scale. These structures can be quickly assembled/disassembled in a regulated fashion in response to specific stimuli. Membraneless organelles contribute to the spatiotemporal compartmentalization of the cell, and they are involved in diverse cellular processes often, but not exclusively, related to RNA metabolism. Liquid-liquid phase separation, a reversible event involving demixing into two distinct liquid phases, provides a physical framework to gain insights concerning the molecular forces underlying the process and how they can be tuned according to the cellular needs. Proteins able to undergo phase separation usually present a modular architecture, which favors a multivalency-driven demixing. We discuss the role of low complexity regions in establishing networks of intra- and intermolecular interactions that collectively control the phase regime. Post-translational modifications of the residues present in these domains provide a convenient strategy to reshape the residue–residue interaction networks that determine the dynamics of phase separation. Focus will be placed on those proteins with low complexity domains exhibiting a biased composition towards the amino acid methionine and the prominent role that reversible methionine sulfoxidation plays in the assembly/disassembly of biomolecular condensates.

Mosaic Arrangement of the 5S rDNA in the Aquatic Plant Landoltia punctata (Lemnaceae)

Duckweeds are a group of monocotyledonous aquatic plants in the Araceae superfamily, represented by 37 species divided into five genera. Duckweeds are the fastest growing flowering plants and are distributed around the globe; moreover, these plants have multiple applications, including biomass production, wastewater remediation, and making pharmaceutical proteins. Dotted duckweed (Landoltia punctata), the sole species in genus Landoltia, is one of the most resilient duckweed species. The ribosomal DNA (rDNA) encodes the RNA components of ribosomes and represents a significant part of plant genomes but has not been comprehensively studied in duckweeds. Here, we characterized the 5S rDNA genes in L. punctata by cloning and sequencing 25 PCR fragments containing the 5S rDNA repeats. No length variation was detected in the 5S rDNA gene sequence, whereas the nontranscribed spacer (NTS) varied from 151 to 524 bp. The NTS variants were grouped into two major classes, which differed both in nucleotide sequence and the type and arrangement of the spacer subrepeats. The dominant class I NTS, with a characteristic 12-bp TC-rich sequence present in 3–18 copies, was classified into four subclasses, whereas the minor class II NTS, with shorter, 9-bp nucleotide repeats, was represented by two identical sequences. In addition to these diverse subrepeats, class I and class II NTSs differed in their representation of cis-elements and the patterns of predicted G-quadruplex structures, which may influence the transcription of the 5S rDNA. Similar to related duckweed species in the genus Spirodela, L. punctata has a relatively low rDNA copy number, but in contrast to Spirodela and the majority of other plants, the arrangement of the 5S rDNA units demonstrated an unusual, heterogeneous pattern in L. punctata, as revealed by analyzing clones containing double 5S rDNA neighboring units. Our findings may further stimulate the research on the evolution of the plant rDNA and discussion of the molecular forces driving homogenization of rDNA repeats in concerted evolution.

A Reversible shearing DNA-based tension probe for cellular force measurement

Cells can sense and respond to molecular forces ranging from a few pN to tens of pN through mechanosensitive receptors with an astounding diversity of mechanisms. DNA-based molecular tension sensors have been instrumental in studying the importance of mechanical forces in many biological systems. However, the respective shortcomings of these sensors, for instance, the irreversible rupture of tension gauge tether (TGT) under force and relatively limited dynamic range of the hairpin probes, limited our understanding of the molecular details of mechano-chemo-transduction in living cells. Here, we developed a reversible shearing DNA-based tension probe (RSDTP) for probing molecular pN-scale forces between 4-60 pN transmitted by cells. Using RSDTPs to study integrin-mediated mechanotransduction, we could real-time distinguish the differences of force-bearing integrins without perturbing adhesion biology in living cells.