dictyNews

Electronic Edition

Volume 48, number 1

January 21, 2022



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Abstracts

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Fractional 2´-O-Methylation in the ribosomal RNA of Dictyostelium 

discoideum supports ribosome heterogeneity in Amoebozoa



Jan Diesend, Ulf Birkedal, Jonas Kjellin, Jingwen Zhang, Kim Philipp 

Jablonski, Fredrik Söderbom, Henrik Nielsen and Christian Hammann



*Correspondence: [log in to unmask]

as of February 2022: 

[log in to unmask]





Scientific Reports, accepted



A hallmark of ribosomal RNA (rRNA) are 2´-O-methyl groups that 

are introduced sequence specifically by box C/D small nucleolar RNAs 

(snoRNAs) in ribonucleoprotein particles. Most data on this chemical 

modification and its impact on RNA folding and stability are derived 

from organisms of the Opisthokonta supergroup. Using bioinformatics 

and RNAseq data, we identify 30 novel box C/D snoRNAs in Dictyostelium 

discoideum, many of which are differentially expressed during the 

multicellular development of the amoeba. By applying RiboMeth-seq, we 

find 49 positions in the 17S and 26S rRNA 2´-O-methylated. Several of 

these nucleotides are substoichiometrically modified, with one displaying 

dynamic modification levels during development. Using homology-based 

models for the D. discoideum rRNA secondary structures, we localize 

many modified nucleotides in the vicinity of the ribosomal A, P and E sites. 

For most modified positions, a guiding box C/D snoRNA could be identified, 

allowing to determine idiosyncratic features of the snoRNA/rRNA 

interactions in the amoeba. Our data from D. discoideum represents the 

first evidence for ribosome heterogeneity in the Amoebozoa supergroup, 

allowing to suggest that it is a common feature of all eukaryotes.





Submitted by Christian Hammann [[log in to unmask]]

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Cell behaviors within a confined adhesive area fabricated using 

novel micropatterning methods



Tsukasa Nakatoh, Takuji OsakiI, Sohma Tanimoto, Md. Golam Sarowar 

Jahan, Tomohisa Kawakami, Kentaro Chihara, Nobuyuki Sakai, 

Shigehiko Yumura





Plos One, accepted

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0262632



In the field of cell and tissue engineering, there is an increasing demand 

for techniques to spatially control the adhesion of cells to substrates of 

desired sizes and shapes. Here, we describe two novel methods for 

fabricating a substrate for adhesion of cells to a defined area. In the first 

method, the surface of the coverslip or plastic dish was coated with 

Lipidure, a non-adhesive coating material, and air plasma was applied 

through a mask with holes, to confer adhesiveness to the surface. In the 

second method, after the surface of the coverslip was coated with gold 

by sputtering and then with Lipidure; the Lipidure coat was locally removed 

using a novel scanning laser ablation method. These methods efficiently 

confined cells within the adhesive area and enabled us to follow individual 

cells for a longer duration, compared to the currently available commercial 

substrates. By following single cells within the confined area, we were able 

to observe several new aspects of cell behavior in terms of cell division, 

cell–cell collisions, and cell collision with the boundary between 

adhesive and non-adhesive areas.





Submitted by Shigehiko Yumura [[log in to unmask]]

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VASP boosts protrusive activity of macroendocytic cups and drives 

phagosome rocketing after internalization



Sarah Körber and Jan Faix



Institute for Biophysical Chemistry, Hannover Medical School, 

Carl-Neuberg-Str.1, 30625 Hannover, Germany



European Journal of Cell Biology (EJCB)





Ena/VASP proteins are powerful actin polymerases that drive the 

processive elongation of actin filaments. Members of this protein family 

have been implicated in a variety of important cellular processes including 

axon guidance, cell migration and adhesion. However, the specific function 

of these proteins in macroendocytosis, comprising macropinocytosis and 

phagocytosis remain rather poorly understood. Here, we used the 

professional phagocyte Dictyostelium discoideum to address the function 

and dynamics of its only family member VASP in macroendocytosis. 

Confocal time-lapse imaging revealed that VASP localized prominently in 

a circumferential narrow band at the advancing rim of the phagocytic cup 

followed by its aperture-like convergence upon particle internalization. Loss 

of VASP resulted in substantial defects in both, macropinocytosis of bulk fluid 

and phagocytosis of yeast particles. Consistently, VASP-deficiency coincided 

with diminished speed of the protruding rim and an impaired internalization 

rate. Most intriguingly, after cup closure, VASP condensed at the distal side 

of internalized phagosomes and initiated localized de-novo actin assembly 

to propel the phagosome by an actin-rich comet deeper into the cell, 

resembling intracellular movement of rocketing Listeria cells. In line with 

these findings, travelled distance and speed of rocketing phagosomes in 

VASP-deficient cells were markedly impaired.

 

 

Submitted by Jan Faix [[log in to unmask]]

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[End dictyNews, volume 48, number 1]