Microtubule motors play key roles in cellular functions, such as transport, mitosis and cell motility. Fueled by ATP hydrolysis, they convert chemical energy into mechanical work, which enables their ...movement on microtubules. While their motion along the long axis of microtubules has been studied extensively, some motors display an off-axis component, which results in helical motion around microtubules and the generation of torque in addition to linear forces. Understanding these nuanced movements expands our comprehension of motor protein dynamics and their impact on cellular processes.
During mitosis, motor proteins and microtubule-associated protein organize the spindle apparatus by cross-linking and sliding microtubules. Kinesin-5 plays a vital role in spindle formation and ...maintenance, potentially inducing twist in the spindle fibers. The off-axis power stroke of kinesin-5 could generate this twist, but its implications in microtubule organization remain unclear. Here, we investigate 3D microtubule-microtubule sliding mediated by the human kinesin-5, KIF11, and found that the motor caused right-handed helical motion of anti-parallel microtubules around each other. The sidestepping ratio increased with reduced ATP concentration, indicating that forward and sideways stepping of the motor are not strictly coupled. Further, the microtubule-microtubule distance (motor extension) during sliding decreased with increasing sliding velocity. Intriguingly, parallel microtubules cross-linked by KIF11 orbited without forward motion, with nearly full motor extension. Altering the length of the neck linker increased the forward velocity and pitch of microtubules in anti-parallel overlaps. Taken together, we suggest that helical motion and orbiting of microtubules, driven by KIF11, contributes to flexible and context-dependent filament organization, as well as torque regulation within the mitotic spindle.
Synopsis
Kinesin motors are involved in organizing the mitotic spindle by cross-linking and sliding microtubules. This work shows that the sideways stepping of human kinesin-5, KIF11, causes helical motion of anti-parallel microtubules and orbiting motion of parallel microtubules.
KIF11 drives a right-handed helical motion of short microtubules around long, suspended microtubules in anti-parallel overlaps.
The microtubule-microtubule distance (i.e., motor extension) decreases with increasing sliding velocity.
KIF11 drives an orbiting motion of parallel microtubules at nearly full motor extension.
Altering the length of the KIF11 neck linker increases forward velocity and pitch of microtubules in anti-parallel overlaps.
Sideways stepping of human KIF11 causes helical and orbiting motions of microtubules that may contribute to flexible filament formation and mitotic spindle torque regulation.
Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in ...microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle.
The SUSD4 (Sushi domain-containing protein 4) gene encodes a complement inhibitor that is frequently deleted in 1q41q42 microdeletion syndrome, a multisystem congenital disorder that includes ...neurodevelopmental abnormalities. To understand SUSD4's role in the mammalian nervous system, we analyzed Susd4 knockout (KO) mice. Susd4 KO mice exhibited significant defects in motor performance and significantly higher levels of anxiety-like behaviors. Susd4 KO brain had abnormal “hairy” basket cells surrounding Purkinje neurons within the cerebellum and significantly reduced dendritic spine density in hippocampal pyramidal neurons. Neurons and oligodendrocyte lineage cells of wild-type mice were found to express Susd4 mRNA. Protein expression of the complement component C1q was increased in the brains of Susd4 KO mice. Our data indicate that SUSD4 plays an important role in neuronal functions, possibly via the complement pathway, and that SUSD4 deletion may contribute to the nervous system abnormalities in patients with 1q41q42 deletions.
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•Susd4 is expressed in neurons and oligodendrocyte lineage cells•Susd4 knockout mice have abnormal hippocampal and cerebellar neuronal morphologies•Susd4 knockout mice exhibit anxiety-like behaviors and impaired motor function•Susd4 knockout mice have elevated brain levels of the complement component C1q
Behavioral Neuroscience; Cellular Neuroscience; Components of the Immune System; Neuroscience
For several years the German healthy child clinics program has been a highly appreciated preventive measure and is subject to constant development. However, attendance depends on the families' ...sociodemographic situation. Findings are documented in a medical checkup booklet (the so-called Gelbes Heft). Currently, there is no procedure to use the data collected for epidemiological purposes nor to evaluate the pediatric prevention measures in Germany.
Between 2011 and 2016, we recruited 3480 study participants for our population-based cohort study LIFE Child in Leipzig. 90.6 % submitted their check-up booklets which were subsequently scanned, the data was digitalized and transmitted to a computerized form. Furthermore, data on social status (so-called Winkler-Index) were collected for each family using a structured questionnaire. The study population consisted of the families' oldest child for whom both data sets were available.
The transmission of data from the check-up booklets was time-consuming and cost-intensive due to large datasets, uncoded diagnoses as well as the necessity of trained employees for transferring often illegible handwriting. Early diagnostic tests for children enjoy a high level of acceptance among all social classes. With increasing age, attendance rate decreases gradually. Only 83 % of the population with a lower social status attend the U9 test. The documentation of diagnoses in the check-up booklets was implausible because the frequency fluctuated heavily between the different check-up time points. With only less than 2 %, the documentation of psychosocial difficulties in a child was particularly surprising
It is not possible to draw conclusions regarding the prevalence of target diseases from the frequency of documented findings in the check-up booklets. In order to make the data both comparable and evaluable, documentation must be digitalized in the future.
Scabies or mange is currently a common dermatosis in Germany and other countries, and should be more important in health policy. It affects a cross-section of society, including all age groups, from ...infants to the aged. Locals and people with a migration background both suffer from this highly contagious ectoparasite infection with excessive, predominately nocturnal itching. Clinical diagnosis represents a challenge for the experienced dermatologist due to the variety of dermatosis to be considered in the differential diagnosis. It is still unclear whether treatment failure or the recurrences observed everywhere are due to in vitro and in vivo resistance of the pathogen agent Sarcoptes scabiei against permethrin or ivermectin. Therapeutic errors seem to play a role as often not all direct contact persons are recorded and treated with antiscabious treatment. They form the reservoir for reinfections. In the event of repeated nonresponse to topical (permethrin) and/or oral antiscabious treatment, alternative topical preparations-benzyl benzoate or crotamiton-should be used. Combination with ivermectin is mandatory.
Abstract only
In defiance of the laws of traditional Mendelian inheritance, multigeneration epigenetic inheritance of changes in gene expression in response to the experience of parental generations ...has been widely observed in both plants and animals. The roundworm
Caenorhabditis elegans (C. elegans)
has emerged as a premier model system for the study of transgenerational epigenetic inheritance, and heritable, epigenetic effects on gene expression have been seen in response to a variety of environmental conditions. It has been hypothesized that worms might be particularly adept at epigenetic inheritance of acquired traits due to their abundant use of small RNA silencing pathways, which have been shown to mediate gene silencing phenomena that can be epigenetically inherited for tens of generations. Here we investigate whether a well‐studied learned behavior in the worm can be inherited, and whether small RNA‐mediated gene silencing plays a role in mediating learning
C. elegans
that have been infected by the pathogenic soil bacterium
Pseudomonas aeruginosa
(
P. aeruginosa,
strain PA14) learn to avoid this food source through a mechanism involving alterations in serotonin expression in specific chemosensory neurons. In this associative learning regimen, worms are trained on plates that contain both pathogenic PA14 and nonpathogenic
Escherichia coli
(
E. coli
). At adulthood, worms are assayed for their preference between PA14 and
E. coli
using a standard behavioral choice assay. Similar to what has been seen previously, we find that only 29% of trained worms choose PA14 over
E. coli,
whereas naïve worms (which have never been exposed to PA14) choose PA14 37% of the time (p<.01, one‐tailed t test). To determine whether this learned avoidance behavior can be inherited by subsequent generations, the F1 progeny of trained worms were raised on plates that contained only
E. coli
and tested in the choice assay at adulthood. 41% of these worms were found in the PA14 spot, which was not significantly different from naïve worms (p=0.21), suggesting that learned pathogen avoidance cannot be epigenetically inherited. Some previously reported cases of siRNA‐mediated epigenetic inheritance in worms required that animals be exposed to the initial silencing trigger for several generations before epigenetic inheritance was established. To ask whether multi‐generation infection to pathogen could result in inheritance of avoidance behavior, synchronized populations of worms were continuously grown in the presence of pathogen for 3, 5, and 7 generations. When we performed learning assays on F1 progeny of the third, fifth, and seventh generation trained worms, we again saw a lack of inheritance of pathogen avoidance. To test the hypothesis that siRNAs play a role in the pathogen avoidance behavior, we are performing learning assays on strains of
C. elegans
containing mutations that disrupt siRNA pathways. In addition, we are using immunofluorescence for serotonin and mRNA‐seq for genome‐wide analysis to ask whether sub‐phenotypic changes in gene expression can be inherited even in the absence of inheritance of the avoidance behavior. Although other studies have examined epigenetic inheritance of learned behaviors or changes in gene expression, few studies have examined both. Taken together, our experiments will address this important gap between gene expression and phenotype.
Zusammenfassung
Hintergrund
Kindervorsorgeuntersuchungen sind seit vielen Jahren eine geschätzte Präventionsmaßnahme und unterliegen einer ständigen Erweiterung. Die Inanspruchnahme hängt vom ...sozialen Status der Familien ab. Die Dokumentation erfolgt unter anderem im sogenannten Gelben Vorsorgeheft. Derzeit werden in Deutschland die erhobenen Daten nicht epidemiologisch genutzt oder die Präventionsmaßnahmen evaluiert.
Methoden
Zwischen 2011 und 2016 wurden innerhalb der populationsgestützten Kohortenstudie LIFE Child in Leipzig 3480 Probanden rekrutiert. 90,6 % der Teilnehmer legten ein Gelbes Vorsorgeheft vor. Diese Hefte wurden gescannt und in eine digitale Eingabemaske übertragen. Kenngrößen zum Sozialstatus wurden mittels Soziodemografiefragebogen erhoben, woraus der Winkler-Index berechnet wurde. Die Studienpopulation wurde aus jeweils dem ältesten Kind pro Familie mit beiden vorliegenden Datensätzen (n = 1964) gebildet.
Ergebnisse
Die Erfassung der Daten aus den Gelben Heften war zeit- und kostenintensiv. Dieser Aufwand ergab sich durch große Datenmengen, uncodierte Diagnosen sowie den Einsatz geschulter Mitarbeiter zum Übertragen der oftmals unleserlichen Handschriften. Die Auswertung der Inanspruchnahme zeigte insgesamt eine hohe Akzeptanz über alle Sozialschichten hinweg. Mit zunehmendem Lebensalter sanken die Teilnahmeraten ab. Zur U9 wiesen Probanden der unteren Sozialschicht die geringste Inanspruchnahme auf (83,0 %). Die Dokumentation der Zielkrankheiten im Gelben Heft war unplausibel. Die Häufigkeit der Angaben schwankte unerklärlich zu den verschiedenen Vorsorgezeitpunkten. Besonders diskrepant zeigte sich die Dokumentation von psychosozialen Auffälligkeiten, welche im gesamten Untersuchungszeitraum bei weniger als 2 % aller Probanden dokumentiert wurden.
Schlussfolgerung
Aus den Häufigkeiten der in den Gelben Heften dokumentierten Befunde lässt sich die Prävalenz der Zielkrankheiten nicht ableiten. Um die Gelben Hefte auswertbar machen zu können, muss die Dokumentation verbessert werden. Deshalb ist eine Digitalisierung der Vorsorgeuntersuchungsbefunde anzustreben.
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