scholarly journals A Surface Glycoprotein Indispensable for Gamete Fusion in the Social Amoeba Dictyostelium discoideum

2012 ◽  
Vol 11 (5) ◽  
pp. 638-644 ◽  
Author(s):  
Yoshinori Araki ◽  
Hideki D. Shimizu ◽  
Kentaro Saeki ◽  
Marina Okamoto ◽  
Lixy Yamada ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Sexual Reproduction ◽  
Dictyostelium Discoideum ◽  
Mating Type ◽  
Surface Glycoprotein ◽  
Sexual Cycle ◽  
Dependent Manner ◽  
Content Type ◽  
Social Amoeba ◽  
The Social

ABSTRACT Sexual reproduction is essential for the maintenance of species in a wide variety of multicellular organisms, and even unicellular organisms that normally proliferate asexually possess a sexual cycle because of its contribution to increased genetic diversity. Information concerning the molecules involved in fertilization is accumulating for many species of the metazoan, plant, and fungal lineages, and the evolutionary consideration of sexual reproduction systems is now an interesting issue. Macrocyst formation in the social amoeba Dictyostelium discoideum is a sexual process in which cells become sexually mature under dark and submerged conditions and fuse with complementary mating-type cells. In the present study, we isolated D. discoideum insertional mutants defective in sexual cell fusion and identified the relevant gene, macA , which encodes a highly glycosylated, 2,041-amino-acid membrane protein (MacA). Although its overall similarity is restricted to proteins of unknown function within dictyostelids, it contains LamGL and discoidin domains, which are implicated in cell adhesion. The growth and development of macA -null mutants were indistinguishable from those of the parental strain. The overexpression of macA using the V18 promoter in a macA -null mutant completely restored its sexual defects. Although the macA gene encoded exactly the same protein in a complementary mating-type strain, it was expressed at a much lower level. These results suggest that MacA is indispensable for gamete interactions in D. discoideum , probably via cell adhesion. There is a possibility that it is controlled in a mating-type-dependent manner.

scholarly journals Cooperation and conflict in the social amoeba Dictyostelium discoideum

2019 ◽  
Vol 63 (8-9-10) ◽  
pp. 371-382
Author(s):  
James M. Medina ◽  
P.M. Shreenidhi ◽  
Tyler J. Larsen ◽  
David C. Queller ◽  
Joan E. Strassmann
Keyword(s):  
Dictyostelium Discoideum ◽  
Fruiting Body ◽  
Sexual Cycle ◽  
Evolution Of Cooperation ◽  
Bacterial Symbionts ◽  
Spore Dispersal ◽  
Social Amoeba ◽  
The Social ◽  
The Relationship ◽  
Insight Into

The social amoeba Dictyostelium discoideum has provided considerable insight into the evolution of cooperation and conflict. Under starvation, D. discoideum amoebas cooperate to form a fruiting body comprised of hardy spores atop a stalk. The stalk development is altruistic because stalk cells die to aid spore dispersal. The high relatedness of cells in fruiting bodies in nature implies that this altruism often benefits relatives. However, since the fruiting body forms through aggregation there is potential for non-relatives to join the aggregate and create conflict over spore and stalk fates. Cheating is common in chimeras of social amoebas, where one genotype often takes advantage of the other and makes more spores. This social conflict is a significant force in nature as indicated by rapid rates of adaptive evolution in genes involved in cheating and its resistance. However, cheating can be prevented by high relatedness, allorecognition via tgr genes, pleiotropy and evolved resistance. Future avenues for the study of cooperation and conflict in D. discoideum include the sexual cycle as well as the relationship between D. discoideum and its bacterial symbionts. D. discoideum’s tractability in the laboratory as well as its uncommon mode of aggregative multicellularity have established it as a promising model for future studies of cooperation and conflict.

scholarly journals Identification of the Mating-Type (MAT) Locus That Controls Sexual Reproduction of Blastomyces dermatitidis

2012 ◽  
Vol 12 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Wenjun Li ◽  
Thomas D. Sullivan ◽  
Eric Walton ◽  
Anna Floyd Averette ◽  
Sharadha Sakthikumar ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Genetic Recombination ◽  
Sexual Cycle ◽  
Blastomyces Dermatitidis ◽  
Comparative Genomic ◽  
Dimorphic Fungi ◽  
Content Type ◽  
Long Time ◽  
Northern United States

ABSTRACTBlastomyces dermatitidisis a dimorphic fungal pathogen that primarily causes blastomycosis in the midwestern and northern United States and Canada. While the genes controlling sexual development have been known for a long time, the genes controlling sexual reproduction ofB. dermatitidis(teleomorph,Ajellomyces dermatitidis) are unknown. We identified the mating-type (MAT) locus in theB. dermatitidisgenome by comparative genomic approaches. TheB. dermatitidis MATlocus resembles those of other dimorphic fungi, containing either an alpha-box (MAT1-1) or an HMG domain (MAT1-2) gene linked to theAPN2,SLA2, andCOX13genes. However, in some strains ofB. dermatitidis, theMATlocus harbors transposable elements (TEs) that make it unusually large compared to theMATlocus of other dimorphic fungi. Based on theMATlocus sequences ofB. dermatitidis, we designed specific primers for PCR determination of the mating type. TwoB. dermatitidisisolates of opposite mating types were cocultured on mating medium. Immature sexual structures were observed starting at 3 weeks of coculture, with coiled-hyphae-containing cleistothecia developing over the next 3 to 6 weeks. Genetic recombination was detected in potential progeny by mating-type determination, PCR-restriction fragment length polymorphism (PCR-RFLP), and random amplification of polymorphic DNA (RAPD) analyses, suggesting that a meiotic sexual cycle might have been completed. The F1 progeny were sexually fertile when tested with strains of the opposite mating type. Our studies provide a model for the evolution of theMATlocus in the dimorphic and closely related fungi and open the door to classic genetic analysis and studies on the possible roles of mating and mating type in infection and virulence.

scholarly journals Presence and Functionality of Mating Type Genes in the Supposedly Asexual Filamentous Fungus Aspergillus oryzae

2012 ◽  
Vol 78 (8) ◽  
pp. 2819-2829 ◽  
Author(s):  
Ryuta Wada ◽  
Jun-ichi Maruyama ◽  
Haruka Yamaguchi ◽  
Nanase Yamamoto ◽  
Yutaka Wagu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aspergillus Oryzae ◽  
Mating Type ◽  
Genetic Manipulation ◽  
Gene Replacement ◽  
Soy Sauce ◽  
Sexual Cycle ◽  
Dependent Manner ◽  
Content Type ◽  
Mating Type Genes

ABSTRACTThe potential for sexual reproduction inAspergillus oryzaewas assessed by investigating the presence and functionality ofMATgenes. Previous genome studies had identified aMAT1-1gene in the reference strain RIB40. We now report the existence of a complementaryMAT1-2gene and the sequencing of an idiomorphic region fromA. oryzaestrain AO6. This allowed the development of a PCR diagnostic assay, which detected isolates of theMAT1-1andMAT1-2genotypes among 180 strains assayed, including industrialtane-kojiisolates. Strains used for sake and miso production showed a near-1:1 ratio of the MAT1-1 and MAT1-2 mating types, whereas strains used for soy sauce production showed a significant bias toward the MAT1-2 mating type. MAT1-1 and MAT1-2 isogenic strains were then created by genetic manipulation of the resident idiomorph, and gene expression was compared by DNA microarray and quantitative real-time PCR (qRT-PCR) methodologies under conditions in whichMATgenes were expressed. Thirty-three genes were found to be upregulated more than 10-fold in either the MAT1-1 host strain or the MAT1-2 gene replacement strain relative to each other, showing that both theMAT1-1andMAT1-2genes functionally regulate gene expression inA. oryzaein a mating type-dependent manner, the first such report for a supposedly asexual fungus.MAT1-1expression specifically upregulated an α-pheromone precursor gene, but the functions of most of the genes affected were unknown. The results are consistent with a heterothallic breeding system inA. oryzae, and prospects for the discovery of a sexual cycle are discussed.

scholarly journals Multiple Pathways to Homothallism in Closely Related Yeast Lineages in the Basidiomycota

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alexandra Cabrita ◽  
Márcia David-Palma ◽  
Patrícia H. Brito ◽  
Joseph Heitman ◽  
Marco A. Coelho ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Protein Interactions ◽  
Single Species ◽  
Phaffia Rhodozyma ◽  
Sexual Cycle ◽  
Natural Setting ◽  
Single Individual ◽  
Content Type ◽  
Heterothallic Species

ABSTRACT Sexual reproduction in fungi relies on proteins with well-known functions encoded by the mating type (MAT) loci. In the Basidiomycota, MAT loci are often bipartite, with the P/R locus encoding pheromone precursors and pheromone receptors and the HD locus encoding heterodimerizing homeodomain transcription factors (Hd1/Hd2). The interplay between different alleles of these genes within a single species usually generates at least two compatible mating types. However, a minority of species are homothallic, reproducing sexually without an obligate need for a compatible partner. Here, we examine the organization and function of the MAT loci of Cystofilobasidium capitatum, a species in the order Cystofilobasidiales, which is unusually rich in homothallic species. We determined MAT gene content and organization in C. capitatum and found that it resembles a mating type of the closely related heterothallic species Cystofilobasidium ferigula. To explain the homothallic sexual reproduction observed in C. capitatum, we examined HD protein interactions in the two Cystofilobasidium species and determined C. capitatum MAT gene expression both in a natural setting and upon heterologous expression in Phaffia rhodozyma, a homothallic species belonging to a clade sister to that of Cystofilobasidium. We conclude that the molecular basis for homothallism in C. capitatum appears to be distinct from that previously established for P. rhodozyma. Unlike in the latter species, homothallism in C. capitatum may involve constitutive activation or dispensability of the pheromone receptor and the functional replacement of the usual Hd1/Hd2 heterodimer by an Hd2 homodimer. Overall, our results suggest that homothallism evolved multiple times within the Cystofilobasidiales. IMPORTANCE Sexual reproduction is important for the biology of eukaryotes because it strongly impacts the dynamics of genetic variation. In fungi, although sexual reproduction is usually associated with the fusion between cells belonging to different individuals (heterothallism), sometimes a single individual is capable of completing the sexual cycle alone (homothallism). Homothallic species are unusually common in a fungal lineage named Cystofilobasidiales. Here, we studied the genetic bases of homothallism in one species in this lineage, Cystofilobasidium capitatum, and found it to be different in several aspects from those of another homothallic species, Phaffia rhodozyma, belonging to the genus most closely related to Cystofilobasidium. Our results strongly suggest that homothallism evolved independently in Phaffia and Cystofilobasidium, lending support to the idea that transitions between heterothallism and homothallism are not as infrequent as previously thought. Our work also helps to establish the Cystofilobasidiales as a model lineage in which to study these transitions.

scholarly journals A Novel Glycolipid Biosurfactant Confers Grazing Resistance upon Pantoea ananatis BRT175 against the Social Amoeba Dictyostelium discoideum

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Derek D. N. Smith ◽  
Arvin Nickzad ◽  
Eric Déziel ◽  
John Stavrinides
Keyword(s):  
Dictyostelium Discoideum ◽  
Opportunistic Infections ◽  
Pantoea Ananatis ◽  
Content Type ◽  
Social Amoeba ◽  
Host Interaction ◽  
Glycolipid Biosurfactant ◽  
The Social ◽  
Grazing Resistance ◽  
Opportunistic Human Pathogen

ABSTRACT The genetic factors used for host interaction by the opportunistic human pathogen Pantoea ananatis are largely unknown. We identified two genes that are important for the production of a biosurfactant that confers grazing resistance against the social amoeba Dictyostelium discoideum. We show that the biosurfactant, which exhibits cytotoxicity toward the amoebae, is a glycolipid that incorporates a hexose rather than rhamnose. The production of this biosurfactant may confer a competitive advantage in the environment and could potentially contribute to the establishment of opportunistic infections. Pantoea is a versatile genus of bacteria with both plant- and animal-pathogenic strains, some of which have been suggested to cause human infections. There is, however, limited knowledge on the potential determinants used for host association and pathogenesis in animal systems. In this study, we used the model host Dictyostelium discoideum to show that isolates of Pantoea ananatis exhibit differential grazing susceptibility, with some being resistant to grazing by the amoebae. We carried out a high-throughput genetic screen of one grazing-resistant isolate, P. ananatis BRT175, using the D. discoideum pathosystem to identify genes responsible for the resistance phenotype. Among the 26 candidate genes involved in grazing resistance, we identified rhlA and rhlB, which we show are involved in the biosynthesis of a biosurfactant that enables swarming motility in P. ananatis BRT175. Using liquid chromatography-mass spectrometry (LC-MS), the biosurfactant was shown to be a glycolipid with monohexose-C10-C10 as the primary congener. We show that this novel glycolipid biosurfactant is cytotoxic to the amoebae and is capable of compromising cellular integrity, leading to cell lysis. The production of this biosurfactant may be important for bacterial survival in the environment and could contribute to the establishment of opportunistic infections. IMPORTANCE The genetic factors used for host interaction by the opportunistic human pathogen Pantoea ananatis are largely unknown. We identified two genes that are important for the production of a biosurfactant that confers grazing resistance against the social amoeba Dictyostelium discoideum. We show that the biosurfactant, which exhibits cytotoxicity toward the amoebae, is a glycolipid that incorporates a hexose rather than rhamnose. The production of this biosurfactant may confer a competitive advantage in the environment and could potentially contribute to the establishment of opportunistic infections.

scholarly journals A Heat Shock Protein 48 (HSP48) Biomolecular Condensate Is Induced duringDictyostelium discoideumDevelopment

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Stephanie Santarriaga ◽  
Alicia Fikejs ◽  
Jamie Scaglione ◽  
K. Matthew Scaglione
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Dictyostelium Discoideum ◽  
Fruiting Body ◽  
Developmental Process ◽  
Cellular Stress ◽  
Content Type ◽  
Social Amoeba ◽  
Content Development ◽  
The Social

ABSTRACTThe social amoebaDictyostelium discoideum’s proteome contains a vast array of simple sequence repeats, providing a unique model to investigate proteostasis. Upon conditions of cellular stress,D. discoideumundergoes a developmental process, transitioning from a unicellular amoeba to a multicellular fruiting body. Little is known about how proteostasis is maintained duringD. discoideum’s developmental process. Here, we have identified a novel α-crystallin domain-containing protein, heat shock protein 48 (HSP48), that is upregulated duringD. discoideumdevelopment. HSP48 functions in part by forming a biomolecular condensate via its highly positively charged intrinsically disordered carboxy terminus. In addition to HSP48, the highly negatively charged primordial chaperone polyphosphate is also upregulated duringD. discoideumdevelopment, and polyphosphate functions to stabilize HSP48. Upon germination, levels of both HSP48 and polyphosphate dramatically decrease, consistent with a role for HSP48 and polyphosphate during development. Together, our data demonstrate that HSP48 is strongly induced duringDictyostelium discoideumdevelopment. We also demonstrate that HSP48 forms a biomolecular condensate and that polyphosphate is necessary to stabilize the HSP48 biomolecular condensate.IMPORTANCEDuring cellular stress, many microbes undergo a transition to a dormant state. This includes the social amoebaDictyostelium discoideumthat transitions from a unicellular amoeba to a multicellular fruiting body upon starvation. In this work, we identify heat shock protein 48 (HSP48) as a chaperone that is induced during development. We also show that HSP48 forms a biomolecular condensate and is stabilized by polyphosphate. The findings here identifyDictyostelium discoideumas a novel microbe to investigate protein quality control pathways during the transition to dormancy.

scholarly journals Amino Acid Repeats Cause Extraordinary Coding Sequence Variation in the Social Amoeba Dictyostelium discoideum

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e46150 ◽  
Author(s):  
Clea Scala ◽  
Xiangjun Tian ◽  
Natasha J. Mehdiabadi ◽  
Margaret H. Smith ◽  
Gerda Saxer ◽  
...  
Keyword(s):  
Amino Acid ◽  
Dictyostelium Discoideum ◽  
Sequence Variation ◽  
Social Amoeba ◽  
Coding Sequence ◽  
Amino Acid Repeats ◽  
The Social

scholarly journals Parasexuality and Ploidy Change in Candida tropicalis

2013 ◽  
Vol 12 (12) ◽  
pp. 1629-1640 ◽  
Author(s):  
Riyad N. H. Seervai ◽  
Stephen K. Jones ◽  
Matthew P. Hirakawa ◽  
Allison M. Porman ◽  
Richard J. Bennett
Keyword(s):  
Sexual Reproduction ◽  
Candida Tropicalis ◽  
Culture Conditions ◽  
Sexual Cycle ◽  
Chromosome Loss ◽  
Parasexual Cycle ◽  
Content Type ◽  
Ploidy Changes ◽  
Diploid Cells

ABSTRACTCandidaspecies exhibit a variety of ploidy states and modes of sexual reproduction. Most species possess the requisite genes for sexual reproduction, recombination, and meiosis, yet only a few have been reported to undergo a complete sexual cycle including mating and sporulation.Candida albicans, the most studiedCandidaspecies and a prevalent human fungal pathogen, completes its sexual cycle via a parasexual process of concerted chromosome loss rather than a conventional meiosis. In this study, we examine ploidy changes inCandida tropicalis, a closely related species toC. albicansthat was recently revealed to undergo sexual mating.C. tropicalisdiploid cells mate to form tetraploid cells, and we show that these can be induced to undergo chromosome loss to regenerate diploid forms by growth on sorbose medium. The diploid products are themselves mating competent, thereby establishing a parasexual cycle in this species for the first time. Extended incubation (>120 generations) ofC. tropicalistetraploid cells under rich culture conditions also resulted in instability of the tetraploid form and a gradual reduction in ploidy back to the diploid state. The fitness levels ofC. tropicalisdiploid and tetraploid cells were compared, and diploid cells exhibited increased fitness relative to tetraploid cellsin vitro, despite diploid and tetraploid cells having similar doubling times. Collectively, these experiments demonstrate distinct pathways by which a parasexual cycle can occur inC. tropicalisand indicate that nonmeiotic mechanisms drive ploidy changes in this prevalent human pathogen.

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