BACKGROUND: The family Trypanosomatidae encompasses parasitic flagellates, some of which cause serious vector-transmitted diseases of humans and domestic animals. However, insect-restricted parasites represent the ancestral and most diverse group within the family. They display a range of unusual features and their study can provide insights into the biology of human pathogens. Here we describe Vickermania, a new genus of fly midgut-dwelling parasites that bear two flagella in contrast to other trypanosomatids, which are unambiguously uniflagellate. RESULTS: Vickermania has an odd cell cycle, in which shortly after the division the uniflagellate cell starts growing a new flagellum attached to the old one and preserves their contact until the late cytokinesis. The flagella connect to each other throughout their whole length and carry a peculiar seizing structure with a paddle-like apex and two lateral extensions at their tip. In contrast to typical trypanosomatids, which attach to the insect host's intestinal wall, Vickermania is separated from it by a continuous peritrophic membrane and resides freely in the fly midgut lumen. CONCLUSIONS: We propose that Vickermania developed a survival strategy that relies on constant movement preventing discharge from the host gut due to intestinal peristalsis. Since these parasites cannot attach to the midgut wall, they were forced to shorten the period of impaired motility when two separate flagella in dividing cells interfere with each other. The connection between the flagella ensures their coordinate movement until the separation of the daughter cells. We propose that Trypanosoma brucei, a severe human pathogen, during its development in the tsetse fly midgut faces the same conditions and follows the same strategy as Vickermania by employing an analogous adaptation, the flagellar connector.
The shape and form of the flagellated eukaryotic parasite Leishmania is sculpted to its ecological niches and needs to be transmitted to each generation with great fidelity. The shape of the Leishmania cell is defined by the sub-pellicular microtubule array and the positioning of the nucleus, kinetoplast and the flagellum within this array. The flagellum emerges from the anterior end of the cell body through an invagination of the cell body membrane called the flagellar pocket. Within the flagellar pocket the flagellum is laterally attached to the side of the flagellar pocket by a cytoskeletal structure called the flagellum attachment zone (FAZ). During the cell cycle single copy organelles duplicate with a new flagellum assembling alongside the old flagellum. These are then segregated between the two daughter cells by cytokinesis, which initiates at the anterior cell tip. Here, we have investigated the role of the FAZ in the morphogenesis of the anterior cell tip. We have deleted the FAZ filament protein, FAZ2 and investigated its function using light and electron microscopy and infection studies. The loss of FAZ2 caused a disruption to the membrane organisation at the anterior cell tip, resulting in cells that were connected to each other by a membranous bridge structure between their flagella. Moreover, the FAZ2 null mutant was unable to develop and proliferate in sand flies and had a reduced parasite burden in mice. Our study provides a deeper understanding of membrane-cytoskeletal interactions that define the shape and form of an individual cell and the remodelling of that form during cell division.
- MeSH
- buněčná membrána MeSH
- cytokineze MeSH
- cytoskelet metabolismus MeSH
- flagella fyziologie ultrastruktura MeSH
- interakce hostitele a parazita * MeSH
- Leishmania růst a vývoj ultrastruktura MeSH
- leishmanióza parazitologie MeSH
- morfogeneze * MeSH
- myši inbrední BALB C MeSH
- myši MeSH
- protozoální proteiny genetika metabolismus MeSH
- Psychodidae parazitologie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Spermiogenesis in the progenetic spathebothriidean cestode Diplocotyle olrikii has been examined using transmission electron microscopy (TEM) for the first time. Along with the typical features of spermatozoon cytodifferentiation (e.g., the electron-dense material in the apical region of the differentiation zone in the early stage of spermiogenesis, the intercentriolar body which is composed of three electron-dense plates and two electron-lucent zones, the orthogonal development of the two flagella, a flagellar rotation, proximo-distal fusion, the presence of two pairs of electron-dense attachment zones), new for the Eucestoda is detection of the formation of two types of free flagella during spermiogenesis in progenetic D. olrikii, exhibiting either standard 9 + '1' trepaxonematan pattern, or atypical 9 + 0 structure. Various combinations of these two types of flagella resulted in the production of three types of male gametes during spermiogenesis in this spathebothriidean cestode. The first type is represented with the two axonemes of the 9 + '1' structure; the second type exhibits two different axonemes, i.e., one with 9 + '1' and the other of 9 + 0 pattern; and the third type has two axonemes with atypical 9 + 0 structure. The occurrence of three sperm types in progenetic D. olrikii is associated with typical spermiogenesis and has never been described previously in the Platyhelminthes. We suppose that heteromorphism of male gametes in D. olrikii might be linked to progenesis, i.e., the programmed sexual maturation detected during the larval/developmental stage of an organism.
- MeSH
- axonema metabolismus MeSH
- Cestoda fyziologie MeSH
- flagella fyziologie MeSH
- spermatogeneze fyziologie MeSH
- spermie cytologie MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Though bivalve mollusks are keystone species and major species groups in aquaculture production worldwide, gamete biology is still largely unknown. This review aims to provide a synthesis of current knowledge in the field of sperm biology, including spermatozoa motility, flagellar beating, and energy metabolism; and to illustrate cellular signaling controlling spermatozoa motility initiation in bivalves. Serotonin (5-HT) induces hyper-motility in spermatozoa via a 5-HT receptor, suggesting a serotoninergic system in the male reproductive tract that might regulate sperm physiology. Acidic pH and high concentration of K+ are inhibitory factors of spermatozoa motility in the testis. Motility is initiated at spawning by a Na+-dependent alkalization of intracellular pH mediated by a Na+/H+ exchanger. Increase of 5-HT in the testis and decrease of extracellular K+ when sperm is released in seawater induce hyperpolarization of spermatozoa membrane potential mediated by K+ efflux and associated with an increase in intracellular Ca2+ via opening of voltage-dependent Ca2+ channels under alkaline conditions. These events activate dynein ATPases and Ca2+/calmodulin-dependent proteins resulting in flagellar beating. It may be possible that 5-HT is also involved in intracellular cAMP rise controlling cAMP-dependent protein kinase phosphorylation in the flagellum. Once motility is triggered, flagellum beats in asymmetric wave pattern leading to circular trajectories of spermatozoa. Three different flagellar wave characteristics are reported, including "full", "twitching", and "declining" propagation of wave, which are described and illustrated in the present review. Mitochondrial respiration, ATP content, and metabolic pathways producing ATP in bivalve spermatozoa are discussed. Energy metabolism of Pacific oyster spermatozoa differs from previously studied marine species since oxidative phosphorylation synthetizes a stable level of ATP throughout 24-h motility period and the end of movement is not explained by a low intracellular ATP content, revealing different strategy to improve oocyte fertilization success. Finally, our review highlights physiological mechanisms that require further researches and points out some advantages of bivalve spermatozoa to extend knowledge on mechanisms of motility.
- MeSH
- druhová specificita MeSH
- energetický metabolismus MeSH
- flagella fyziologie MeSH
- mlži fyziologie MeSH
- motilita spermií fyziologie MeSH
- spermie cytologie fyziologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Motility is a characteristic function of the male gamete, which allows spermatozoa to actively reach and penetrate the female gamete in organisms with internal and external fertilization. Sperm motility is acquired under the control of many extrinsic and intrinsic factors and is based on a specialized structure of the sperm flagellum called "axoneme". An overview of how the sperm flagellum is organized, and it operates to support cell motility is presented, with special focus on the molecular mechanisms and factors involved in the development, maintenance and control of motility. Data obtained in aquatic organisms with external fertilization, such as sea urchins, ascidians or fishes are critically analyzed because they constitute model species on which most of the present day understanding of sperm motility function is based. In most animal species, sperm motility is dependent on a long appendage called flagellum. Flagella are essential organelles found in most eukaryotic cells; their basic structure is the axoneme, which consists of a scaffold of microtubules and is responsible for movement in an autonomous manner if ATP-energy is present. Flagellar beat propels the cell through the medium which surrounds sperm cells and is responsible of the translational drive of spermatozoa. The present paper includes: (1) an introduction to typical sperm morphology and ultrastructure in most aquatic species, (2) the motility apparatus or axoneme of the spermatozoa: the axoneme, (3) the structural and biochemical composition of the axoneme, (4) the axonemal motor or dynein, and its operation, (5) the regulation of motility at axoneme and cell membrane levels, including several effectors such as Ca2+ ions, (6) biophysical features of the wave propagation mechanism in motile spermatozoa, (7) the energy production and consumption, and (8) the building of a flagellum. Flagellar beating in aquatic animals is illustrated using several examples in figures and video-clips. These types of data are also used for computer simulation of various aspects of the modulation of sperm motility of marine animals.
Leishmania kinetoplastid parasites infect millions of people worldwide and have a distinct cellular architecture depending on location in the host or vector and specific pathogenicity functions. An invagination of the cell body membrane at the base of the flagellum, the flagellar pocket (FP), is an iconic kinetoplastid feature, and is central to processes that are critical for Leishmania pathogenicity. The Leishmania FP has a bulbous region posterior to the FP collar and a distal neck region where the FP membrane surrounds the flagellum more closely. The flagellum is attached to one side of the FP neck by the short flagellum attachment zone (FAZ). We addressed whether targeting the FAZ affects FP shape and its function as a platform for host-parasite interactions. Deletion of the FAZ protein, FAZ5, clearly altered FP architecture and had a modest effect in endocytosis but did not compromise cell proliferation in culture. However, FAZ5 deletion had a dramatic impact in vivo: Mutants were unable to develop late-stage infections in sand flies, and parasite burdens in mice were reduced by >97%. Our work demonstrates the importance of the FAZ for FP function and architecture. Moreover, we show that deletion of a single FAZ protein can have a large impact on parasite development and pathogenicity.
- MeSH
- buněčná membrána metabolismus MeSH
- cilie genetika fyziologie ultrastruktura MeSH
- delece genu MeSH
- endocytóza MeSH
- flagella genetika fyziologie ultrastruktura MeSH
- interakce hostitele a parazita MeSH
- Leishmania genetika patogenita fyziologie ultrastruktura MeSH
- mezibuněčné spoje MeSH
- myši MeSH
- protozoální proteiny genetika metabolismus MeSH
- Psychodidae parazitologie MeSH
- virulence genetika MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Spermiogenesis in progenetic and adult stages of Archigetes sieboldi Leuckart, 1878, a tapeworm parasitic in oligochaetes and fish respectively, has been examined using transmission electron microscopy and cytochemical staining for glycogen. General pattern of spermiogenesis is essentially like that of other caryophyllideans, i.e., apical dense material in the zone of differentiation in the early stages of spermiogenesis, rotation of free flagellum and a flagellar bud, and proximo-distal fusion. Interestingly, rotation of a free flagellum and flagellar bud to the median cytoplasmic process (MCP) has been observed unconventionally at > 90° only in progenetic stages. Typical striated roots associated with the centrioles occur rarely in A. sieboldi, and only in form of faint structures in advanced stages of spermiogenesis. In contrast to most caryophyllideans studied to date, penetration of the nucleus into the spermatid body has started before the fusion of the free flagellum with the MCP. This feature has been reported rarely but exclusively in the family Caryophyllaeidae. The unipartite mature spermatozoon of A. sieboldi is composed of one axoneme of the 9 + '1' trepaxonematan pattern with its centriole, parallel nucleus, and parallel cortical microtubules which are situated in a moderately electron-dense cytoplasm with glycogen particles. An unusual arrangement of cortical microtubules in the two parallel rows in region I of the spermatozoon is described here for the first time in the Caryophyllidea. Ultrastructural data on spermiogenesis and the spermatozoon in A. sieboldi from tubuficids and carp are compared and discussed with those in other caryophyllideans and/or Neodermata.
- MeSH
- axonema ultrastruktura MeSH
- barvení a značení MeSH
- buněčné jádro fyziologie MeSH
- Cestoda ultrastruktura MeSH
- cestodózy veterinární MeSH
- flagella fyziologie MeSH
- glykogen analýza MeSH
- kapři parazitologie MeSH
- nemoci ryb parazitologie MeSH
- spermatidy cytologie ultrastruktura MeSH
- spermatogeneze fyziologie MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Trypanosomes are masters of adaptation to different host environments during their complex life cycle. Large-scale proteomic approaches provide information on changes at the cellular level, and in a systematic way. However, detailed work on single components is necessary to understand the adaptation mechanisms on a molecular level. Here, we have performed a detailed characterization of a bloodstream form (BSF) stage-specific putative flagellar host adaptation factor Tb927.11.2400, identified previously in a SILAC-based comparative proteome study. Tb927.11.2400 shares 38% amino acid identity with TbFlabarin (Tb927.11.2410), a procyclic form (PCF) stage-specific flagellar BAR domain protein. We named Tb927.11.2400 TbFlabarin-like (TbFlabarinL), and demonstrate that it originates from a gene duplication event, which occurred in the African trypanosomes. TbFlabarinL is not essential for the growth of the parasites under cell culture conditions and it is dispensable for developmental differentiation from BSF to the PCF in vitro. We generated TbFlabarinL-specific antibodies, and showed that it localizes in the flagellum. Co-immunoprecipitation experiments together with a biochemical cell fractionation suggest a dual association of TbFlabarinL with the flagellar membrane and the components of the paraflagellar rod.
- MeSH
- duplikace genu MeSH
- flagella fyziologie MeSH
- fylogeneze MeSH
- geneticky modifikované organismy MeSH
- myši inbrední C57BL MeSH
- proteinové domény MeSH
- protozoální proteiny chemie genetika imunologie metabolismus MeSH
- Trypanosoma brucei brucei genetika patogenita fyziologie MeSH
- trypanozomóza africká parazitologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Cepacia syndrome (CS) is a fatal septic condition that develops in approximately 20% of cystic fibrosis (CF) patients chronically infected with the Burkholderia cepacia complex (Bcc). The most common causative agent is Burkholderia cenocepacia, a clinically dominant Bcc species that contains the globally distributed epidemic strain sequence type 32 (ST32). Using microarrays, we compared the transcriptomes of ST32 isolates from the bloodstream at the time of CS with their sputum counterparts recovered 1 to 2 months prior to the development of CS. Global gene expression profiles of blood isolates revealed greater activities of the virulence genes involved in the type III secretion system, the bacterial exopolysaccharide cepacian, and quorum sensing, while reduced expression was demonstrated for flagellar genes. Furthermore, a nonmotile phenotype (as evaluated by a swimming motility assay) was identified in blood isolates from 6 out of 8 patients with CS; this phenotype was traceable to 24 months prior to the onset of CS. Loss of motility was not observed in any of the 89 ST32 isolates recovered over the course of chronic infection from 17 patients without CS. In conclusion, the gene expression of Bcc bacteria disseminated during CS has been elucidated for the first time. This study demonstrated marked differences at the transcriptome level between isogenic ST32 isolates that are attributable to the stage and site of infection. The finding of a nonmotile B. cenocepacia isolate may serve as a warning sign for the development of CS in the near future.
- MeSH
- bakteriemie mikrobiologie MeSH
- biogeneze organel * MeSH
- Burkholderia cenocepacia genetika fyziologie MeSH
- cystická fibróza komplikace mikrobiologie MeSH
- dospělí MeSH
- flagella genetika fyziologie MeSH
- infekce bakteriemi rodu Burkholderia mikrobiologie MeSH
- krev mikrobiologie MeSH
- lidé MeSH
- lokomoce MeSH
- mikročipová analýza MeSH
- prognóza MeSH
- retrospektivní studie MeSH
- sputum mikrobiologie MeSH
- stanovení celkové genové exprese * MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
In the present study, for the first time in fish spermatozoa, we describe the precise chronology of motility initiation of sterlet (sturgeon) sperm from completely immotile flagella to regular full wave propagation. The successive activation steps were investigated by high-speed video microscopy, using specific experimental situation, where sperm motility initiation was delayed in time up to several seconds (10 ± 2.68 seconds). Starting from fully immotile, the flagellum shows some trembling for a brief period, soon followed by appearance of the first real bend (so-called "principal bend") with a large wave amplitude 4.28 ± 0.65 μm, then by the "reverse bend," the latter presenting a lower (P < 0.05) wave amplitude (1.14 ± 0.32 μm). This couple of first bends formed at the basal region begins to propagate toward the flagellar tip but gradually fades when reaching the midflagellum, wherein consequently the sperm cell remains nonprogressive. This behavior repeats several times until a stage where the amplitude of the reverse bend gradually reaches a value similar that of the principal bend: The larger amplitude of this couple of bends finally leads to sustain a real "takeoff" of the sperm cell characterized by a full flagellar wave propagation generating an active forward displacement similar to that occurring during regular steady state motility (several seconds after activation). Starting from the earliest stages of motility initiation, the wave propagation along the flagellum and formation of new waves proceeded in a helical manner leading to a 3-dimensional rotation of the whole spermatozoon. Eventually, we estimated that the time period needed from the activation signal (contact with fresh water) to full wave propagation ranges from 0.4 to 1.2 seconds.
- MeSH
- flagella fyziologie MeSH
- motilita spermií * MeSH
- ryby fyziologie MeSH
- spermie cytologie fyziologie MeSH
- vodní hospodářství MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
