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1. Unwinding the roles of RNA helicase MOV10

   https://doi.org/10.1002/wrna.1682  

   Nawaz, Aatiqa ; Shilikbay, Temirlan ; Skariah, Geena ; Ceman, Stephanie ( July 2021 , WIREs RNA)

   MOV10 is an RNA helicase that associates with the RNA‐induced silencing complex component Argonaute (AGO), likely resolving RNA secondary structures. MOV10 also binds the Fragile X mental retardation protein to block AGO2 binding at some sites and associates with UPF1, a principal component of the nonsense‐mediated RNA decay pathway. MOV10 is widely expressed and has a key role in the cellular response to viral infection and in suppressing retrotransposition. Posttranslational modifications of MOV10 include ubiquitination, which leads to stimulation‐dependent degradation, and phosphorylation, which has an unknown function. MOV10 localizes to the nucleus and/or cytoplasm in a cell type‐specific and developmental stage‐specific manner. Knockout ofMov10leads to embryonic lethality, underscoring an important role in development where it is required for the completion of gastrulation. MOV10 is expressed throughout the organism; however, most studies have focused on germline cells and neurons. In the testes, the knockdown ofMov10disrupts proliferation of spermatogonial progenitor cells. In brain, MOV10 is significantly elevated postnatally and binds mRNAs encoding cytoskeleton and neuron projection proteins, suggesting an important role in neuronal architecture. HeterozygousMov10mutant mice are hyperactive and anxious and their cultured hippocampal neurons have reduced dendritic arborization. Zygotic knockdown ofMov10inXenopus laeviscauses abnormal head and eye development and mislocalization of neuronal precursors in the brain. Thus, MOV10 plays a vital role during development, defense against viral infection and in neuronal development and function: its many roles and regulation are only beginning to be unraveled.

   This article is categorized under:

   RNA Interactions with Proteins and Other Molecules > RNA‐Protein Complexes

   RNA Interactions with Proteins and Other Molecules > Protein‐RNA Interactions: Functional Implications

    

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2. The FUSED LEAVES1‐ ADHERENT1 regulatory module is required for maize cuticle development and organ separation

   https://doi.org/10.1111/nph.16837  

   Liu, Xue ; Bourgault, Richard ; Galli, Mary ; Strable, Josh ; Chen, Zongliang ; Feng, Fan ; Dong, Jiaqiang ; Molina, Isabel ; Gallavotti, Andrea ( August 2020 , New Phytologist)

   All aerial epidermal cells in land plants are covered by the cuticle, an extracellular hydrophobic layer that provides protection against abiotic and biotic stresses and prevents organ fusion during development.

   Genetic and morphological analysis of the classic maizeadherent1(ad1) mutant was combined with genome‐wide binding analysis of the maize MYB transcription factor FUSED LEAVES1 (FDL1), coupled with transcriptional profiling offdl1mutants.

   We show thatAD1encodes an epidermally‐expressed 3‐KETOACYL‐CoA SYNTHASE (KCS) belonging to a functionally uncharacterized clade of KCS enzymes involved in cuticular wax biosynthesis. Wax analysis inad1mutants indicates thatAD1functions in the formation of very‐long‐chain wax components. We demonstrate that FDL1 directly binds to CCAACC core motifs present inAD1regulatory regions to activate its expression. Over 2000 additional target genes of FDL1, including many involved in cuticle formation, drought response and cell wall organization, were also identified.

   Our results identify a regulatory module of cuticle biosynthesis in maize that is conserved across monocots and eudicots, and highlight previously undescribed factors in lipid metabolism, transport and signaling that coordinate organ development and cuticle formation.

    

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3. Pore constrictions in intervessel pit membranes provide a mechanistic explanation for xylem embolism resistance in angiosperms

   https://doi.org/10.1111/nph.17282  

   Kaack, Lucian ; Weber, Matthias ; Isasa, Emilie ; Karimi, Zohreh ; Li, Shan ; Pereira, Luciano ; Trabi, Christophe L. ; Zhang, Ya ; Schenk, H. Jochen ; Schuldt, Bernhard ; et al ( March 2021 , New Phytologist)

   Embolism spreading in angiosperm xylem occurs via mesoporous pit membranes between vessels. Here, we investigate how the size of pore constrictions in pit membranes is related to pit membrane thickness and embolism resistance.

   Pit membranes were modelled as multiple layers to investigate how pit membrane thickness and the number of intervessel pits per vessel determine pore constriction sizes, the probability of encountering large pores, and embolism resistance. These estimations were complemented by measurements of pit membrane thickness, embolism resistance, and number of intervessel pits per vessel in stem xylem (n = 31, 31 and 20 species, respectively).

   The modelled constriction sizes in pit membranes decreased with increasing membrane thickness, explaining the measured relationship between pit membrane thickness and embolism resistance. The number of pits per vessel affected constriction size and embolism resistance much less than pit membrane thickness. Moreover, a strong relationship between modelled and measured embolism resistance was observed.

   Pore constrictions provide a mechanistic explanation for why pit membrane thickness determines embolism resistance, which suggests that hydraulic safety can be uncoupled from hydraulic efficiency. Although embolism spreading remains puzzling and encompasses more than pore constriction sizes, angiosperms are unlikely to have leaky pit membranes, which enables tensile transport of water.

    

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4. Bluehead chub Nocomis leptocephalus hosts exploit selfish‐herd benefits from their heterospecific nest associates

   https://doi.org/10.1111/fwb.14224  

   Betts, Madison M. ; Abaid, Nicole ; Maurakis, Eugene G. ; Frimpong, Emmanuel A. ( January 2024 , Freshwater Biology)

   Prey species often congregate in groups to detect and evade predators, yet not all group members benefit equally. We observed the nesting aggregations of bluehead chub (Nocomis leptocephalus), where one nest “hosts” as many as several hundred “nest associates.” We predicted that the male chub exploits the aggregation in a manner consistent with selfish‐herd theory – specifically, by locating itself in the safest location within the aggregation (the centre) and using the aggregation to reduce its own vigilance requirements.

   Vigilance was measured as the time it took the host (male) chub, first chub female and first individual of each associate species to return to the nest under differing associate abundances (hypothesised to be inversely related to risk) following a simulated predator scare. Spatial position was investigated by digitising host movement and overlaying it with the aggregation and nest's spawning pit area.

   We used information theoretic statistics to analyse the effect of aggregation characteristics on the return time of chub and their nest associates. The best‐supported model included both species composition and abundance (inverse of risk) as predictors of return time. Hosts returned last under nearly all scenarios and the aggregation as a whole took longest to return in high‐risk environments. The 95% and 99% confidence ellipses of host spatial position contained the centroids of the aggregation and spawning pits, respectively, for all nests analysed (n = 11).

   We conclude that the host locates itself at the centre of both the aggregation and the spawning pit area of the nest, and that the host uses the aggregation to reduce its own vigilance requirements. These results support our hypothesis that hosts use their nest associates to disproportionately decrease their risk of predation during spawning.

   This is the first study to show any mixed‐species fish spawning aggregation as a selfish shoal, and to identify bluehead chub as a selfish participant in the mutualistic reproductive interactions that they host.

    

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5. Zhuotingoxylon liaoi gen. et sp. nov., a silicified coniferous trunk from the Changhsingian (Permian) of southern Bogda Mountains, northwestern China

   https://doi.org/10.1002/gj.4189  

   Wan, Mingli ; Yang, Wan ; Wang, Keyu ; Liu, Lujun ; Wang, Jun ( June 2021 , Geological Journal)

   A silicified trunk,Zhuotingoxylon liaoiWan, Yang, Wang, Liu et Wang gen. et sp. nov., is described from the uppermost part of Guodikeng Formation in South Taodonggou section, Turpan–Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China. It is characterized by a solid pith, endarch primary xylem and pycnoxylic wood. The pith is composed of parenchyma and sclereids. Radial walls of primary xylem tracheids have spiral and scalariform thickenings. Secondary xylem consists of thick‐walled tracheids and parenchymatous rays. Uniseriate rounded pits with oval apertures are distributed on radial tracheidal walls separately. Cell walls of rays are homogeneous and smooth. Rays are 1–10 cells high in tangential section. Cross‐field pits are cupressoid. There are 1–4 bordered pits with slit‐like to oval apertures in each cross‐field. Based on the anatomical features of the pith and xylems, it is proposed that the new stem has a coniferous affinity. The new fossil stem adds to the knowledge of vascular plant diversity close to the Permian–Triassic boundary.

    

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