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VCRPs, small cysteine-rich proteins, might be involved in extracellular signaling in the green alga Volvox.

ABSTRACT: The sex-inducer of the spherical green alga Volvox carteri is one of the most potent biological effector molecules known: it is released into the medium by sexual males and triggers the switch to the sexual cleavage program in the reproductive cells of vegetatively grown males and females even at concentrations as low as 10(-16) M. In an adult Volvox alga, all cells are embedded in an extensive extracellular matrix (ECM), which constitutes >99% of the volume of the spheroid. There exist no cytoplasmic connections between the cells in an adult alga, so any signal transduction between different cells or from the organism's environment to a reproductive cell must involve the ECM. Recently, a small cysteine-rich extracellular protein, VCRP, was identified in Volvox and shown to be quickly synthesized by somatic cells in response to the sex-inducer. Due to its characteristics, VCRP was speculated to be an extracellular second messenger from somatic cells to reproductive cells. Here a related protein, VCRP2, is presented, exhibiting a 56% amino acid sequence identity with VCRP. Two possible scenarios for signal transduction from the sex-inducer to the reproductive cell are discussed.

SUBMITTER: Hallmann A

PROVIDER: S-EPMC2634000 | biostudies-literature |

REPOSITORIES: biostudies-literature

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MicroRNAs in a multicellular green alga Volvox carteri

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2014-02-08 | GSE52345 | GEO

MicroRNAs in a multicellular green alga Volvox carteri

2014-02-08 | E-GEOD-52345 | biostudies-arrayexpress

Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri.

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| S-EPMC4416025 | biostudies-literature

Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri.

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| S-EPMC2993248 | biostudies-literature

Gene replacement by homologous recombination in the multicellular green alga Volvox carteri.

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| S-EPMC1774577 | biostudies-literature

Different regulations of cell-type transcription by UV-B in multicellular green alga Volvox carteri.

Project description:There is a scarcity of research reports on the effect of ultraviolet (UV)-B radiation on genome-wide transcriptional regulation in the multicellular green microalga including Volvox carteri (V. carteri). This microalga possesses only two cell types including mortal and motile somatic cells, as well as immortal and immotile reproductive cells. Therefore, the present study evaluated the effect of low-dose UV-B radiation on the cell-type-specific gene expression pattern of reproductive and somatic cells in an asexual life cycle of V. carteri using RNA sequence method. To this end, the separated reproductive and somatic cells were treated for 1 hour at an intensity of 0.056 mW/cm-2 UV-B radiation. Then, a transcriptome analysis was conducted between the UV-B and white light treated groups in either of the cell types. Based on differential gene expression analyses, no differentially expressed genes were found in reproductive cells under the treatment as compared to the control group. This type of cell maintained its steady state. However, treating the somatic cells with UV-B radiation led to at least 126 differentially expressed genes compared to the untreated control group. In addition, the results of a direct comparison demonstrated a restricted and wide response to UV-B radiation in somatic cells as compared to reproductive cells. Based on the results, UV-B radiation could be involved in cell-type-specific regulation of biological pathways.

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Gene silencing pathways found in the green alga Volvox carteri reveal insights into evolution and origins of small RNA systems in plants.

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Cell-type specific photoreceptors and light signaling pathways in the multicellular green alga Volvox carteri and their potential role in cellular differentiation.

Project description:The formation of multicellular organisms requires genetically predefined signaling pathways in various cell types. Besides differences in size, energy balance and life time, cell types should be enable to modulate appropriate developmental and adaptive responses in ever-changing surrounding environment. One of the most important environmental cues is light which regulates a variety of physiological and cellular processes. During evolution, diverse light-sensitive proteins, so-called photoreceptors, and corresponding signaling pathways have evolved, in almost all kingdoms of life, to monitor light continuously and adjust their growth and development accordingly. However, considering the fact that different cell types should be enable to trigger distinct light signaling pathways according to their needs, cell-type specific light signaling pathways are required to guarantee cell type-matched modulation of cellular and developmental processes in response to different light signals. The multicellular green alga Volvox carteri, which has only 2 cell types with clear division of labor, possesses cell-type specific photoreceptors and light signaling pathways which allow differential regulation of genes involved in various cellular and metabolic pathways in response to environmental light. The existence of cell-type specific light signaling pathways in multicellular organism like Volvox reflects an early development of cell-type specific signaling mechanisms during evolution to ensure maintenance of differentiation.

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Expanded male sex-determining region conserved during the evolution of homothallism in the green alga <i>Volvox</i>.

Project description:Male and female genotypes in heterothallic (self-incompatible) species of haploid organisms, such as algae and bryophytes, are generally determined by male and female sex-determining regions (SDRs) in the sex chromosomes. To resolve the molecular genetic basis for the evolution of homothallic (bisexual and self-compatible) species from a heterothallic ancestor, we compared whole-genome data from Thai and Japanese genotypes within the homothallic green alga Volvox africanus. The Thai and Japanese algae harbored expanded ancestral male and female SDRs of ∼1 Mbp each, representing a direct heterothallic ancestor. Therefore, the expanded male and female ancestral SDRs may originate from the ancient (∼75 mya) heterothallic ancestor, and either might have been conserved during the evolution of each homothallic genotype. An expanded SDR-like region seems essential for homothallic sexual reproduction in V. africanus, irrespective of male or female origin. Our study stimulates future studies to elucidate the biological significance of such expanded genomic regions.

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