Gliding motility of Plasmodium merozoites

Plasmodium malaria parasites are obligate intracellular protozoans that use a unique form of locomotion, termed gliding motility, to move through host tissues and invade cells. The process is substrate dependent and powered by an actomyosin motor that drives the posterior translocation of extracellular adhesins which, in turn, propel the parasite forward. Gliding motility is essential for tissue translocation in the sporozoite and ookinete stages; however, the short-lived erythrocyte-invading merozoite stage has never been observed to undergo gliding movement. Here we show Plasmodium merozoites possess the ability to undergo gliding motility in vitro and that this mechanism is likely an important precursor step for successful parasite invasion. We demonstrate that two human infective species, Plasmodium falciparum and Plasmodium knowlesi, have distinct merozoite motility profiles which may reflect distinct invasion strategies. Additionally, we develop and validate a higher throughput assay to evaluate the effects of genetic and pharmacological perturbations on both the molecular motor and the complex signaling cascade that regulates motility in merozoites. The discovery of merozoite motility provides a model to study the glideosome and adds a dimension for work aiming to develop treatments targeting the blood stage invasion pathways.

Marine gregarine genomes illuminate current understanding of apicomplexan glideosome

Apicomplexans, parasite protists of a very wide diversity of metazoan hosts, are mostly known from species infecting human. Absence or limited data for basal lineages prevents a comprehensive view of evolutionary history and adaptive capacities of Apicomplexa. Here, we characterized the genome of the marine eugregarine Porospora gigantea, remarkable for the gigantic size of its vegetative feeding forms (trophozoites) and their speed of gliding movement, the fastest so far recorded for an Apicomplexa. Not a single but two highly related genomes named A and B were assembled. Highly syntenic, of similar size (9 Mb) and coding capacities (~5300 genes), they display a 10.8% divergence at nucleotide level corresponding to 16-38 My divergent time. Orthogroups analyses across 25 (proto)Apicomplexa including Gregarina niphandrodes showed that A and B are highly divergent from all other known apicomplexan species, revealing an unexpected diversity. These two related species branch in phylogenetic studies at the base of Cephaloidophoroidea, forming a new family in these crustacean gregarines. Gliding proteins data mining found a strong conservation of actin-related proteins, as well as of regulatory factors, within apicomplexan. In contrast, the conservation of core glideosome proteins and adhesion proteins appears to be highly variable among apicomplexan lineages, especially in gregarines. These results confirm the importance of studying gregarines to widen our biological and evolutionary view of apicomplexan parasites, to better apprehend species diversity and revise our understanding of the molecular bases of some key functions such as observed for the glideosome.

Proteogenomic Insights into the Physiology of Marine, Sulfate-Reducing, Filamentous Desulfonema limicola and Desulfonema magnum

The genus Desulfonema belongs to the deltaproteobacterial family Desulfobacteraceae and comprises marine, sulfate-reducing bacteria that form filaments and move by gliding. This study reports on the complete, manually annotated genomes of Dn. limicola 5ac10T (6.91 Mbp; 6,207 CDS) and Dn. magnum 4be13T (8.03 Mbp; 9,970 CDS), integrated with substrate-specific proteome profiles (8 vs. 11). The richness in mobile genetic elements is shared with other Desulfobacteraceae members, corroborating horizontal gene transfer as major driver in shaping the genomes of this family. The catabolic networks of Dn. limicola and Dn. magnum have the following general characteristics: 98 versus 145 genes assigned (having genomic shares of 1.7 vs. 2.2%), 92.5 versus 89.7% proteomic coverage, and scattered gene clusters for substrate degradation and energy metabolism. The Dn. magnum typifying capacity for aromatic compound degradation (e.g., p-cresol, 3-phenylpropionate) requires 48 genes organized in operon-like structures (87.7% proteomic coverage; no homologs in Dn. limicola). The protein complements for aliphatic compound degradation, central pathways, and energy metabolism are highly similar between both genomes and were identified to a large extent (69–96%). The differential protein profiles revealed a high degree of substrate-specificity for peripheral reaction sequences (forming central intermediates), agreeing with the high number of sensory/regulatory proteins predicted for both strains. By contrast, central pathways and modules of the energy metabolism were constitutively formed under the tested substrate conditions. In accord with their natural habitats that are subject to fluctuating changes of physicochemical parameters, both Desulfonema strains are well equipped to cope with various stress conditions. Next to superoxide dismutase and catalase also desulfoferredoxin and rubredoxin oxidoreductase are formed to counter exposure to molecular oxygen. A variety of proteases and chaperones were detected that function in maintaining cellular homeostasis upon heat or cold shock. Furthermore, glycine betaine/proline betaine transport systems can respond to hyperosmotic stress. Gliding movement probably relies on twitching motility via type-IV pili or adventurous motility. Taken together, this proteogenomic study demonstrates the adaptability of Dn. limicola and Dn. magnum to its dynamic habitats by means of flexible catabolism and extensive stress response capacities.

Simulation Analysis of the Aerodynamic Performance of a Bionic Aircraft with Foldable Beetle Wings in Gliding Flight

Beetles have excellent flight performance. Based on the four-plate mechanism theory, a novel bionic flapping aircraft with foldable beetle wings was designed. It can perform flapping, gliding, wing folding, and abduction/adduction movements with a self-locking function. In order to study the flight characteristics of beetles and improve their gliding performance, this paper used a two-way Fluid-Structure Interaction (FSI) numerical simulation method to focus on the gliding performance of the bionic flapping aircraft. The effects of elastic model, rigid and flexible wing, angle of attack, and velocity on the aerodynamic characteristics of the aircraft in gliding flight are analyzed. It was found that the elastic modulus of the flexible hinges has little effect on the aerodynamic performance of the aircraft. Both the rigid and the flexible wings have a maximum lift-to-drag ratio when the attack angle is 10°. The lift increased with the increase of the gliding speed, and it was found that the lift cannot support the gliding movement at low speeds. In order to achieve gliding, considering the weight and flight performance, the weight of the microair vehicle is controlled at about 3 g, and the gliding speed is guaranteed to be greater than 6.5 m/s. The results of this study are of great significance for the design of bionic flapping aircrafts.

Gliding motility of Plasmodium merozoites

SummaryPlasmodium malaria parasites use a unique form of locomotion termed gliding motility to move through host tissues and invade cells. The process is substrate-dependent and powered by an actomyosin motor that drives the posterior translocation of extracellular adhesins, which in turn propel the parasite forward. Gliding motility is essential for tissue translocation in the sporozoite and ookinete stages, however, the short-lived erythrocyte-invading merozoite stage has never been observed to undergo gliding movement. Here for the first time we reveal that blood stage Plasmodium merozoites use gliding motility for translocation in addition to host cell invasion. We demonstrate that two human infective species, P. falciparum and P. knowlesi, have distinct merozoite motility profiles reflective of divergent invasion strategies. The process is powered by a conserved actomyosin motor and glideosome complex and is regulated by a complex signaling pathway. This significantly enhances our understanding of merozoite-host interactions in malaria parasites.

MENINGKATKAN PEMBELAJARAN RENANG GAYA DADA DENGAN MENGGUNAKAN PART WHOLE METHOD UNTUK SISWA KELAS VIIIB SMPK FRATERAN CELAKET 21 MALANG

Abstrak: Penelitian ini bertujuan untuk mengetahui: (1) peningkatan keterampilan belajar siswa pada saat pembelajaran renang gaya dada menggunakan Part Whole Method Instrumen yang digunakan dalam penelitian ini, adalah lembar observasi, catatan lapangan, dan dokumentasi.Rancangan penelitian yang digunakan dalam penelitian ini adalah penelitian tindakan kelas (PTK). Melalui PTK ini dilaksanakan pembelajaran lempar lembing menggunakan pendekatan permainan.Subjek dalam penelitian tindakan kelas ini adalah siswa kelas VIII BSMPK Frateran Celaket 21 Malang semester genap tahun ajaran 2012-2013, yang berjumlah 30 siswa terdiri dari 19 siswa laki-laki dan 11 siswa perempuan.Data diperoleh peneliti dari pengamatan saat berlangsungnya proses pembelajaran terhadap 30 siswa sebagai subjek penelitian dengan menggunakan lembar observasi yang terdiri dari gerakan meluncur, gerakan kaki, gerakan tangan, gerakan mengambil nafas, dan koordinasi gerakan.Hasil penelitian menunjukan bahwa keterampilan siswa kelas VIII B SMPK Frateran Celaket 21 Malang mengalami peningkatan. Hasil observasi awal keterampilan adalah 50,36%, kemudian meningkat pada siklus I sebesar 13,27% atau menjadi 63,64%. Pada siklus II meningkat sebesar 19,3% atau menjadi 82,94%. Berdasarkan hasil penelitian dapat disimpulkan bahwa Part Whole Method pada pembelajaran renang gaya dada dapat meningkatkan keterampilan siswa kelas VIII BSMPK Frateran Celaket 21 Malang.Kata Kunci: meningkatkan keterampilan, pembelajaran, Part Whole Method, renang gaya dada. Abstract: This study aimed to determine: (1) increase students' learning skills when learning breaststroke swimming using Method Part Whole instrument used in this study, is the observation sheets, field notes, and documentation. The research design used in this study is action research (PTK). TOD is implemented through learning javelin permainan.Subjek approach in classroom action research is a class VIII BSMPK Frateran Malang Celaket 21 semester 2012-2013 school year, which amounts to 30 students consisted of 19 male students and 11 students perempuan.Data Researchers from the observations obtained during the learning process of the 30 students as research subjects by using the observation sheet which consists of a gliding movement, leg movements, hand gestures, the movement took a breath, and movement coordination. The results showed that the skills of students of class VIII B SMPK Frateran Celaket 21 Malang has increased. Results of initial observation skills is 50.36%, then increased in the first cycle of 13.27% to 63.64%. In the second cycle increased by 19.3% to 82.94%. Based on the results of this study concluded that Part Whole Method in breaststroke swimming lessons to improve skills of eighth grade students B SMPK Frateran Celaket 21 MalangKeywords: improving skills, learning, Part Whole Method, swimming breaststroke.

Linear motor driven-rotary motion of a membrane-permeabilized ghost in Mycoplasma mobile

Mycoplasma mobile exhibits a smooth gliding movement as does its membrane-permeabilized ghost model. This exceptionally prominent experimental system has allowed us to conclude that the energy source for M. mobile motility is adenosine triphosphate (ATP), and the gliding is largely comprised of repetitions of unitary steps of about 70 nm. In the present study, we show a new motility mode, in which the ghost model prepared with a high concentration of detergent exhibits directed rotational motions with a constant speed. With a rotational speed and viscous friction of a single ghost, the torque was estimated to be ∼30 pN nm at saturated [ATP]s. Although the origin of the rotation has not been conclusively settled, we found that rotary ghosts treated with sialyllactose, the binding target for leg proteins, were stopped. This result suggested that biomolecules embedded on the cell membrane nonspecifically attaches to the glass and works as a flexible pivot point, and the linear motion of the leg is a driving force for a rotary motion. This simple geometry exemplifies the new mechanism, by which the movement of a linear motor is efficiently converted to a constant rotation of the object on a micrometer scale.

MID-MOTION DEFORMATION OF MEDIAN NERVE DURING FINGER FLEXION: A NEW INSIGHT INTO THE DYNAMIC AETIOLOGY OF CARPAL TUNNEL SYNDROME

Carpal tunnel syndrome (CTS) exists in a spectrum of severity and symptoms with a dynamic component. We aim to study dynamic nerve-tendon interrelationships in normal and mild CTS wrists during a fist motion, with dynamic ultrasound. We observed that in normal wrists, the nerve arcs in an ulnar-volar direction and changes from a circular shape to a flat oval during motion. In CTS candidates, however, the curvature and distance of the nerve's path are reduced, while nerve shape remains relatively constant. In all candidates, the nerve is compressed against the flexor retinaculum, with the nerve subject to less compression in normal candidates as it moves dorsally into a recess. These findings suggest that besides mechanical compression from increased carpal tunnel contents alone, a decrease in nerve gliding movement may lead to CTS symptomatology. Furthermore, we identified that maximum nerve deformation occurs mid-motion, supporting the use of wrist splints for symptom relief.