choanocytes and choanoflagellates{ keyword }

Choanoflagellates, choanocytes, and animal multicellularity Authors: Manuel Maldonado Spanish National Research Council Abstract It is widely accepted that multicellular animals (metazoans). 00:09:38.06 and the origin of multicellularity, here, 00:35:28.29 and you want to learn more, 00:10:24.12 in which you have a single cell, the zygote, Although choanocytes of adult sponges have no obvious homologue among meta- zoans, larval cells transd rentiating into choanocytes at metamorphosis do have such homologues. 00:35:32.17 we invite many, many people, we want to grow this community, 00:20:22.03 and in particular we focused on genes that are required 00:01:46.26 and that is that animals are united 00:02:05.00 and we know even less 00:20:40.23 They are essentially a bacterial biofilm, eCollection 2023. 00:14:16.01 in which you can see, again, a choanoflagellate cell S3 Fig. ssTEM sections were imported as z-stacks into the Fiji [71] plugin TrakEM2 [72] and automatically aligned using default parameters, except for increasing steps per octave scale to 5 and reducing maximal alignment error to 50 px. For sponges, tiny pieces of O. carmela were excised and mixed with 20% BSA made up in seawater before transferring to 200-m deep high-pressure freezing planchettes. 00:21:06.19 had not previously been found in a non-animal before, Lavrov AI, Bolshakov FV, Tokina DB, Ereskovsky AV. After 3 h, the block/cells had warmed to 20C and were ready for resin infiltration. 00:01:38.20 and mechanistic underpinnings Its very well preserved. 00:22:29.10 We can also find genes whose functions 00:10:45.18 and they have some diagnostic features 00:03:53.19 and I'm gonna come back to that topic in part two. 00:06:42.18 It has many different morphologies 00:19:26.14 to make inferences about the genome of their last common ancestor. 00:14:27.25 that's the name for the collar cells in sponges, 00:00:52.12 The work in my laboratory has to do By sequencing the genomes of many choanoflagellate species, King and her colleagues have discovered that some genes required for multicellularity in animals, such as adhesion, signaling, and extracellular matrix genes, are found in choanoflagellates. 00:22:07.29 or, many different genes that are required (or 'choanocytes') of sponges. 00:09:09.20 So, we have a rich history 00:15:03.14 allows for tremendous fluid flow. 00:12:35.03 of this developmental switch? Also visible are cellcell contacts between two adjacent choanocytes. SUMMARY The similarities between the choanoflagellates and the choanocytes of sponges have been discussed for more than a century yet few studies allow a direct comparison of the two. Golgi-associated vesicles (S1I, S1I and S1I Fig), due to their tight association with the Golgi apparatus, likely represent standard Golgi-trafficking vesicles carrying cargo between the different Golgi cisternae [4]. 00:13:49.02 And, let me tell you, Choanoflagellates are single-celled aquatic flagellates with a unique morphology consisting of a cell with a single flagellum surrounded by a "collar" of microvilli. 00:16:08.05 led to rosette development, but it did. 00:25:01.07 about animal origins and details. Micrographs were recorded with an ORCA-Flash4.0 digital camera (Hamamatsu Photonics, Japan). Flagellar vanes were found in both cell types. called choanocytes. To place our choanoflagellate reconstructions into the context of collar cells from an early-branching animal phylum, we reconstructed a section of a sponge choanocyte chamber from the homoscleromorph sponge Oscarella carmela [19] (Box 1). 00:20:19.26 animal multicellularity and animal development, 00:24:53.27 in my career. 00:34:30.06 about mechanisms underlying animal origins. 00:21:31.14 what fraction of them seem to be restricted to animals? 00:14:33.29 They're actually creating fluid flow to capture bacteria. Clipboard, Search History, and several other advanced features are temporarily unavailable. 00:05:06.08 to form simple multicellular morphologies. 00:14:08.20 and only the occasional rosette colony, 00:03:12.17 and the composition of genomes 2022 Feb;150:125984. doi: 10.1016/j.zool.2021.125984. 00:24:18.09 of immune system components in animals, 00:34:45.06 between animals and their commensal bacteria. King N, Westbrook MJ, Young SL, Kuo A, Abedin M, Chapman J, Fairclough S, Hellsten U, Isogai Y, Letunic I, Marr M, Pincus D, Putnam N, Rokas A, Wright KJ, Zuzow R, Dirks W, Good M, Goodstein D, Lemons D, Li W, Lyons JB, Morris A, Nichols S, Richter DJ, Salamov A, Sequencing JGI, Bork P, Lim WA, Manning G, et al. 00:07:06.08 and cultures that only have slow swimmers in them 00:14:10.09 even more clearly in this electron micrograph, 00:05:22.06 and comparisons with animals, 00:02:42.29 is what are the big questions that we want to ask 00:07:38.17 that these would be the ones involved in multicellularity, Unauthorized use of these marks is strictly prohibited. 00:05:56.13 from being single-celled to colonial, Similarities between the feeding cells of sponges (choanocytes) and choanoflagellate protists ( Figure 27.12) have been used to suggest that Metazoa evolved from a common ancestral organism that resembled the modern colonial choanoflagellates. 27.3 Animal Phylogeny - Biology 2e | OpenStax 00:28:44.15 and in fact we have. 00:20:00.18 might have been. 00:01:47.29 I'm going to focus on one particular species 00:25:31.19 and an exciting future area of research Images of cells on serial sections were taken on an FEI Tecnai 12 electron camera. 00:14:02.23 and from that he made the argument that 00:31:13.00 Finally, we'd like to know 00:15:54.11 actually, when he treated, when he used that, Choanocyte - an overview | ScienceDirect Topics 00:04:31.13 as a postdoc 00:06:12.07 before the origin and diversification of animals. 00:23:44.20 we find that there are some genes 3D cellular architecture of choanoflagellate single cell S2. 00:12:18.04 and the flagellum is undulating back and forth, Choanoflagellates: Current Biology - Cell Press 00:07:34.26 and the genes they share in common, Molecular phylogenies indicate that choanoflagellates and metazoans are sister groups. 00:07:13.02 chain colonies, 00:22:21.22 but the GPCRs, these are protein coupled receptors, 00:34:24.25 is something special to the choanoflagellate lineage 00:28:22.08 the maximal induction that we're seeing . High-magnification TEM panel of the S. rosetta (AL) and O. carmela (MT) subcellular components discussed herein. 00:15:49.12 and they gave two very interesting results. Evolution is expected to lead to differences among homologous structures (an excellent example are vertebrate limbs that are all very differentsome are wings, some are legs, some are fins but are still homologous) and thus it is not surprising to observe (ultra)structural differences between choanoflagellates and choanocytes. 00:33:56.02 is that the developmental switch 00:11:41.06 such as you can see here. 3D cellular architecture of choanoflagellate colonial cell C1. af, actin filaments; b, bacteria; bf, basal foot; cc, choanocytes; cr, cristae; dv, food vacuole; er, endoplasmic reticulum; eu, euchromatin; ev, endocytotic invagination; f, flagellum; fbb, flagellar basal body; fp, posterior filopodia; ga, golgi apparatus; gly, glycogen storage; he, heterochromatin; m, mitochondrion; mv, microvillus; n, nucleolus; nfbb, nonflagellar basal body; nm, nuclear membrane; npc, nuclear pore complex; pm, plasma membrane; ps, pseudopodia; rer, rough endoplasmic reticulum; ser, smooth endoplasmic reticulum; TEM, transmission electron microscopy; tf, tubulin filaments; tp, transversal plate. 00:22:08.29 And so, you may remember that I mentioned These ultrastructural differences are good identifying features marking the differential biology of generalist versus specialist collar cells. 00:08:30.09 in the way in which they form? 00:13:35.29 He isolated a single colony, grew it up, Choanocytes are unicellular organisms, so they cannot be considered a multicellular animal. 00:14:13.20 And so, no matter what I did, 00:25:12.18 they extracted the sphingolipid fraction 00:05:38.22 the process by which this organism, S. rosetta, 00:25:18.13 and then In Monosiga, the flagellar amplitude was unaffected by the collar; instead the collar diameter appeared fitted to the flagellum. Fluorescent-DIC microscopy was conducted under a 100x oil-immersion objective lens using a Leica DMi8 epifluorescent microscope (Leica, Germany). 00:01:52.15 and I'm going to tell you that this choanoflagellate 00:19:53.03 for why bacteria are such an important factor I just found what I believe to be the basket-shaped fossil exoskeleton of a representative of what once was a Choanoflagellate in a picture that NASAS Rover Curiosity took on Mars. 00:22:21.05 that is to say, they ate bacteria. 00:18:05.28 to produce this adult form that I just told you about. 00:06:39.01 among all of these lineages lonial choanoflagellates (Clark 1868; Kent 1878). 00:05:47.22 and in addition I will tell you 00:09:44.12 that sits in this sweet spot on the phylogenetic tree, The ER of colonial cells frequently displayed wide, flat sheets (Fig 3E), which were not observed in the reconstructed single cells. 00:19:41.10 between bacteria and eukaryotes. Our 3D ssTEM reconstructions allowed for the reconstruction of five choanocytes and for the volumetric and numerical comparison of choanocyte and choanoflagellate subcellular structures (Fig 4B4E, S5 and S6 Figs, S10 Movie). 00:05:54.21 But, let me get back to this big question: 00:00:07.22 So, Hello. Volumetric and numerical comparison of choanocyte and choanoflagellate major subcellular structures. 00:19:42.10 additional choanoflagellates that are in culture, 00:24:08.20 an outer membrane and an inner membrane. 00:31:08.12 different types of bioactive molecules ssTEM, serial ultrathin transmission electron microscopy. 00:22:24.02 the receptor tyrosine kinases, 00:35:05.21 that I discussed here. Similar collars have . After overcoming the technical difficulty of getting S. rosetta to form rosettes in the lab, she investigated how rosettes develop and how the cells within a rosette adhere to each other. 00:02:52.11 of phylogenetic analyses. Choanoflagellate models - Monosiga brevicollis and Salpingoeca rosetta. 00:21:48.02 progenitors of animals. Study with Quizlet and memorize flashcards containing terms like Identify traits that characterize all animals., State one way that animal cells differ from the cells of plants and fungi. 00:30:41.20 you can't read which bacteria I'm showing you. Here we test this traditional view of the origin of the animal kingdom by comparing the transcriptomes, fates and . 00:23:38.01 this has been a very exciting but also challenging process, In Monosiga, collars were flared and microvilli were joined by a single band of glycocalyx mid-way along their length; in Spongilla, collars formed a tube and microvilli were joined by a mesh of glycocalyx. 00:08:25.24 -- the animals, 00:09:13.14 So, let me start with question number 1: 00:13:53.01 in the natural world, and that was in sponges. (F) Posterior filopodia projecting from the basal plasma membrane. S5 Fig. 00:20:04.03 all of the different genes that are found in that ancestral genome, 00:14:27.26 So, I worked on this for a long time, (A) Choanocytes from O. carmela are significantly larger by volume (m3) than the single and colonial choanoflagellate S. rosetta cells. Likewise, we describe a complex system of cellcell connections associated with multicellular choanoflagellates. 00:04:06.10 for choanoflagellates. Diagrams of the choanocyte fine kinetid (F) and choanoflagellate fine kinetid (G) structure highlight the distinct differences. 00:06:55.03 for all of these different forms, Investigation of the choanoflagellate cell plan therefore has the potential to shed light on the evolution of one of the most ancient animal cell types. They 00:12:46.23 but that fluid flow also has a second important function, 00:08:54.10 is capable of producing three different types of morphologies. 00:35:19.19 who's been a really fantastic collaborator Choanoflagellates are voracious single-cell predators. Colours are as in Fig 1. 00:09:24.24 to learn anything about the nature Extracellular vesicles were also observed to be associated with two of the single cells (electron-lucent, 173 36 nm in diameter) and appeared to bud from the microvillar membrane (S1L, S1L and S1L Fig). Colours as in Fig 1. 00:32:56.18 really interesting organisms, the choanoflagellates, 00:23:42.20 and compare it to choanoflagellates 00:27:28.19 and the exciting result is that in fact 3D cellular architecture of choanoflagellate single cell S1. 00:21:56.18 The second point that I want to make Shown are the highly inv and ps basal pole of the choanocyte (B, C), macropinocytotic activity (*) at the apical pole (D, E) and a mesohyl-associated bacterium being engulfed by a ps at the basal pole (F, G). In part 2 of her talk, King explains how she chose to use S. rosetta as a simple model for animal origins. 00:25:19.02 And, the second important thing that we've learned 00:25:04.17 in recovering bioactive molecules. 00:32:40.18 of the choanoflagellate, 00:17:54.25 and test them one at a time 00:17:33.01 Moreover, it's become clear, Scale bar = 1 m. 00:00:14.06 Animals have incredibly diverse body plans, 00:02:16.15 What we can reasonably infer 00:06:10.01 that they are ancient and evolved 00:19:51.05 I want to back up and give you a little bit of context 00:01:50.08 They all share a common ancestor 00:07:20.20 So, there's a lot of dynamic cell differentiation that's going on, (EL) 2D TEM and 3D ssTEM reconstructions of structures (*) differentially exhibited by colonial cells or involved in colony formation. 00:32:30.07 that controls whether a single cell 00:02:06.25 about the organisms from which it evolved, 00:24:55.12 and we can study these organisms, now, Although collar cells are conserved across animals and their closest relatives, the choanoflagellates, little is known about their ancestry, their subcellular architecture, or how they differentiate. 00:20:36.19 its function from the other, Organelles and subcellular compartments were manually segmented and 3D reconstructed by automatically merging traced features along the z-axis. 00:05:50.03 about how that's regulated. 00:22:57.00 we're finding representatives of these genes 00:12:55.01 and so you can see in this picture right here 00:11:30.21 a fine meshwork of material covering the cells 00:02:54.12 And it comes from comparisons between 00:30:30.13 we've also surveyed lots of other diverse bacteria, ER, endoplasmatic reticulum; inv, invaginated; ps, pseudopodiated; ssTEM, serial ultrathin transmission electron microscopy. 00:14:22.06 and here you can see, in SEM, 00:13:43.07 So, I brought it back to Madison, Collar microvilli were of similar length and number, but the shape of the collar differed between the two cells. Pluripotency and the origin of animal multicellularity | Nature Even in macropinosomes with no observable cargo, dissolved proteins [58] and ATP [56] from extracellular fluid have been previously reported to be metabolically exploited by animal macropinocytotic cell types. 00:10:39.02 Choanoflagellates are single-celled microbial eukaryotes. Our comparison between single and colonial choanoflagellate cells provides new insights into ultrastructural commonalities and differences associated with the conversion of solitary to colonial cells. Methodological overview of 3D ssTEM reconstruction of S. rosetta and O. carmela cells. 00:04:49.29 how do the cells interact Pluripotency and the origin of animal multicellularity - PubMed 00:26:24.07 and most recently the Howard Hughes Medical Institute. 00:13:26.18 were obsessed with choanoflagellates. 00:16:32.12 Now, it could have been 00:08:57.12 and that's depicted by these yellow bars. 00:03:57.27 from the media up against the collar, 00:05:53.09 We're trying to understand 00:24:28.29 and I say that these are unusual, 00:06:26.27 about protozoa as being simple organisms Colony-free S. rosetta cultures (ATCC 50818) were grown with coisolated prey bacteria in 0.22 m filtered choanoflagellate growth medium [66] diluted at a ratio of 1:4 with autoclaved seawater. Concentrated cell suspension (500 l) was applied to glass-bottom dishes, coated with poly-L-lysine solution (P8920, Sigma-Aldrich), and left for 1030 min until cells were sufficiently adhered. 00:28:31.00 it's sufficient for rosette induction, They have long interested evolutionary biologists because of their striking resemblance to the collared cells (choanocytes) of sponges. the body of a sponge, and they filter out food particles with their The site is secure. 00:20:43.01 and we preserve representatives of these types of morphologies, 00:08:19.09 Are they forming 00:30:23.13 that we have discovered already using our bioassay, We found differences between single-celled and multicellular choanoflagellates in structures associated with cellular energetics, membrane trafficking, and cell morphology. 00:17:31.20 So, that was very exciting, S4 Fig. 00:18:56.01 And so, one of the first things I did (FG) Reconstruction and comparison of the sponge choanocyte (F) and choanoflagellate (G) apical poles shows distinct differences between the two cell types. Choanoflagellates are small unicellular protists comprising both marine and freshwater species (Fig. 00:01:34.13 the first animals likely had genes in their genomes 00:17:14.02 were actually eating bacteria. This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'. 00:24:55.12 It's been a fantastic experience. Numbers of various organelles and components in O. carmela choanocytes. Adhered cells were incubated in 500 l of fluorescent vital dye diluted in 0.22 m filtered seawater. 2023 Feb;38(2):127-138. doi: 10.14670/HH-18-485. 00:03:50.26 to swim through the water column, 00:11:54.24 which can actually biomineralized silica 00:16:49.21 what I'm showing you is what we now infer 00:14:18.24 and so that meant that I wasn't going to be able extracellular matrix;ER, 00:26:07.27 and I'm also very grateful to all the collaborators 00:15:08.03 genomes of single-celled choanoflagellates, 00:00:27.20 like the jellyfish that we see here 00:33:46.04 a living choanoflagellate, the choanoflagellate S. rosetta. 00:17:00.08 this planar sheet of cells. Colours are as in Fig 1. 00:17:38.05 which bacteria were actually (N) Volumetric distribution of mean cell volumes (RC15) in RCs reveals no apparent pattern of cell distribution across the z-axis. 00:15:00.05 from this species, 00:04:44.19 and these colonies 00:14:53.06 And so, finally, I switched my research objectives Comparative ultrastructural schematics of a choanoflagellate and a sponge choanocyte, modified from Maldonado, M., 2004. 00:12:28.14 along the surface of the collar, 00:04:00.04 and those water currents can carry bacteria, 00:25:28.01 but in the fist pass people from his lab 00:01:29.03 can help us understand animal origins, Colony-enriched S. rosetta cultures (PX1) were likewise maintained but monoxenically cultured with the prey bacterium A. machipongonensis [67] to induce rosette formation. 00:09:52.18 and in the end of this 15 hour movie 00:17:39.16 of different modes of sexual reproduction, Highlighted are contacting FP (C) and IBs (D). 00:11:20.23 Now, choanoflagellates are actually quite diverse. 00:22:43.03 Myc, p53, and Forkhead, How did animals evolve from their single-celled ancestors? 00:30:57.25 and those in grey induce at a low level. 00:01:45.14 that we need to keep in mind, 00:21:02.17 Many of the genes that are required for these processes 00:20:16.06 whose functions are required for 00:02:53.26 The first is: 00:04:55.02 and it doesn't tell us how cells 00:12:19.28 And what determines 00:15:24.29 this creates a real problem for genome sequencing 00:09:54.09 quite a bit about them in the next few slides, 00:04:36.21 are actually spicules from an ancient sponge, Choanocyte - Wikipedia Cells in rosette colonies are numbered in order of their appearance along the image stack z-axis. 00:13:23.21 and people like Ernst Haeckel and William Saville-Kent Volumetric measurements of S. rosetta cells and components. Scale bar = approximately 1 m. (CD) Characterisation of major organelles in S. rosetta labelled with fluorescent vital dyes (C) and by immunofluorescence (D). ShapiroWilk and Levenes tests were used to assess normality and homogeneity of variance, respectively. 00:35:39.06 and importantly we have a choanoflagellate workshop 00:01:02.23 and I'm excited to be here today 00:26:37.16 called the sulfonolipids,

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