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1.
Fungal Biol ; 123(2): 109-116, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30709516

RESUMO

This study reconstructs early stages of Rozella allomycis endoparasitic infection of its host, Allomyces macrogynus. Young thalli of A. macrogynus were inoculated with suspensions of R. allomycis zoospores and allowed to develop for 120 h. Infected thalli at intervals were fixed for electron microscopy and observed. Zoospores were attracted to host thalli, encysted on their surfaces, and penetrated their walls with an infection tube. The parasite cyst discharged its protoplast through an infection tube, which invaginated the host plasma membrane. The host plasma membrane then surrounded the parasite protoplast and formed a compartment confining it inside host cytoplasm. The earliest host-parasite interface within host cytoplasm consisted of two membranes, the outer layer the host plasma membrane and the inner layer the parasite plasma membrane. At first a wide space separated the two membranes and no material was observed within this space. Later, as the endoparasite thallus expanded within the compartment, the two membranes became closely appressed. As the endoparasite thallus continued to enlarge, the interface developed into three membrane layers. Thus, host plasma membrane surrounded the parasite protoplast initially without the parasite having to pierce the host plasma membrane for entry. Significantly, host-derived membrane was at the interface throughout development.


Assuntos
Allomyces/ultraestrutura , Fungos/ultraestrutura , Interações Hospedeiro-Parasita/fisiologia , Microscopia Eletrônica/métodos , Esporos Fúngicos/ultraestrutura , Membrana Celular/ultraestrutura
2.
J Exp Biol ; 221(Pt 2)2018 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-29170260

RESUMO

Complex sensory systems often underlie critical behaviors, including avoiding predators and locating prey, mates and shelter. Multisensory systems that control motor behavior even appear in unicellular eukaryotes, such as Chlamydomonas, which are important laboratory models for sensory biology. However, we know of no unicellular opisthokonts that control motor behavior using a multimodal sensory system. Therefore, existing single-celled models for multimodal sensorimotor integration are very distantly related to animals. Here, we describe a multisensory system that controls the motor function of unicellular fungal zoospores. We found that zoospores of Allomyces arbusculus exhibit both phototaxis and chemotaxis. Furthermore, we report that closely related Allomyces species respond to either the chemical or the light stimuli presented in this study, not both, and likely do not share this multisensory system. This diversity of sensory systems within Allomyces provides a rare example of a comparative framework that can be used to examine the evolution of sensory systems following the gain/loss of available sensory modalities. The tractability of Allomyces and related fungi as laboratory organisms will facilitate detailed mechanistic investigations into the genetic underpinnings of novel photosensory systems, and how multisensory systems may have functioned in early opisthokonts before multicellularity allowed for the evolution of specialized cell types.


Assuntos
Allomyces/fisiologia , Quimiotaxia , Fototaxia , Esporos Fúngicos/fisiologia , Sensação
3.
ACS Chem Biol ; 11(2): 452-9, 2016 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-26674547

RESUMO

The basal fungus Allomyces macrogynus (A. macrogynus) produces motile male gametes displaying well-studied chemotaxis toward their female counterparts. This chemotaxis is driven by sirenin, a sexual pheromone released by the female gametes. The pheromone evokes a large calcium influx in the motile gametes, which could proceed through the cation channel of sperm (CatSper) complex. Herein, we report the total synthesis of sirenin in 10 steps and 8% overall yield and show that the synthetic pheromone activates the CatSper channel complex, indicated by a concentration-dependent increase in intracellular calcium in human sperm. Sirenin activation of the CatSper channel was confirmed using whole-cell patch clamp electrophysiology with human sperm. Based on this proficient synthetic route and confirmed activation of CatSper, analogues of sirenin can be designed as blockers of the CatSper channel that could provide male contraceptive agents.


Assuntos
Allomyces/química , Canais de Cálcio/metabolismo , Cálcio/metabolismo , Feromônios/química , Feromônios/farmacologia , Espermatozoides/efeitos dos fármacos , Humanos , Masculino , Feromônios/síntese química , Espermatozoides/metabolismo
4.
Fungal Genet Biol ; 47(8): 713-20, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20452449

RESUMO

Allomyces macrogynus, a true fungus, produces zoosporangia which discharge uninucleate zoospores after cytoplasmic cleavage. Binucleate zoosporangia of A. macrogynus were induced and examined to understand the basic principles of cytokinesis associated with the multinucleate zoosporangia. Development of cleavage membranes was visualized by constructing three dimensional models based on electron micrographs and confocal images. Cleavage membranes on the cleavage plane showed asymmetric ingression from the cortex, but cleavage of cytoplasm was completed by the fusion of cleavage membranes with plasma membrane. Also, the position of the cleavage plane was continuously rotated until settled at the last stage. These studies suggest that the positions of the numerous cleavage planes within a multinucleate zoosporangium are continuously adjusted during development of cleavage membranes. The final settlement of cleavage planes would define the exact boundary of cleavage planes and the expansion of cleavage membranes toward the boundary could complete the cleavage of cytoplasm.


Assuntos
Allomyces/crescimento & desenvolvimento , Citocinese , Esporos Fúngicos/crescimento & desenvolvimento , Allomyces/citologia , Imageamento Tridimensional , Microscopia Confocal , Microscopia Eletrônica , Esporos Fúngicos/citologia
5.
Gene ; 457(1-2): 25-34, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20214955

RESUMO

Allomyces arbuscula, a primitive chytridiomycete fungus, has two Ca(2+)-dependent cysteine proteases, the CDP I and CDP II. We have cloned and analyzed the nucleotide sequence of CDP II gene and domain structure of the protein. Blast analysis of the sequence has shown that the protein belongs to a newly described member of caspase superfamily protein, the metacaspase, a CD clan of C14 family cysteine protease, we hence-forth name it as AMca 2 (Allomyces metacaspase 2). Southern hybridization studies have shown that the gene exists in a single copy per genome. The transcriptional analysis by Northern hybridization has confirmed our previous results that the protein is developmentally regulated, i.e. present in active growth phase but disappears during nutritional stress which also induces reproductive differentiation, indicating that the protein promotes cell growth, not death. The recombinant gene product expressed in Escherichiacoli has all the catalytic properties of native enzyme, i.e. sensitivity to protease inhibitors and substrate specificity. There is an absolute requirement of Ca(2+) for the activation of catalytic activity and the presence of R residue at the cleavage site (P1 position) in the substrate. The presence of a second basic residue, either R or K, in the P2 position strongly inhibits the catalytic activity which is stimulated by the presence of P and to a lesser extent G at this site. Peptide substrates with D at the cleavage site are not recognised and therefore not cleaved. The enzyme activity is inhibited by EDTA-EGTA, cysteine protease inhibitors and a specific peptide inhibitor Ac GVRCHCL TFA, but not by E64, although a potent inhibitor of cysteine proteases.


Assuntos
Allomyces/enzimologia , Allomyces/genética , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/fisiologia , Allomyces/crescimento & desenvolvimento , Allomyces/metabolismo , Sequência de Aminoácidos , Cisteína Endopeptidases/química , Cisteína Endopeptidases/metabolismo , Dosagem de Genes , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade , Especificidade por Substrato
6.
Curr Biol ; 19(5): R208-10, 2009 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-19278637

RESUMO

The development of our eyes is owed in part to ancestral structures which functioned in phototaxis. With the origin of bilateral annelid larva, two eyes co-evolved with neurons to improve phototaxis performance.


Assuntos
Evolução Biológica , Movimento Celular , Olho , Luz , Allomyces/citologia , Allomyces/metabolismo , Animais , Chlamydomonas/citologia , Chlamydomonas/metabolismo , Larva/citologia , Larva/fisiologia , Células Fotorreceptoras de Invertebrados/fisiologia
7.
Gene ; 424(1-2): 33-9, 2008 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-18721866

RESUMO

The mitochondrial genome of the chytrid Blastocladiella emersonii was sequenced and annotated, revealing the complete set of oxidative phosphorylation genes and tRNAs/rRNAs necessary for the translation process. Phylogenetic reconstructions reinforce the proposal of the new phylum Blastocladiomycota. Evidences of gene duplication due to inserted elements suggest shared susceptibility to gene invasion/exchange between chytrids and zygomycetes. The gene content of B. emersonii is very similar to Allomyces macrogynus but the content of intronic and changeable elements is much lower suggesting a stronger resistance to this kind of exchange. In addition, a total of 401 potential nuclear transcripts encoding mitochondrial proteins were obtained after B. emersonii EST database scanning using Saccharomyces cerevisiae, Homo sapiens and Arabidopsis thaliana data as probes and TargetP tool to find N-terminal mitochondrial signal in translated sequences.


Assuntos
Blastocladiella/genética , DNA Fúngico/genética , DNA Mitocondrial/genética , Adenina , Allomyces/genética , Blastocladiella/classificação , Códon/genética , DNA Fúngico/isolamento & purificação , Biblioteca Gênica , Genoma Fúngico , Fases de Leitura Aberta , Filogenia , Timina
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