A Morphologic and Genetic Study of Gonium Pectorale

Stein, Janet R.

doi:10.1002/j.1537-2197.1958.tb12219.x

Cited by 72 publications

(40 citation statements)

References 15 publications

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“…The names of the two mating types of G. pectorale (plus and minus) were assigned arbitrarily (Stein 1958), and since we show here that the MT À loci of both G. pectorale and C. reinhardtii carry the MID gene, we have chosen to continue with this usage. Four strains of G. pectorale were used here: Kaneko3 (minus) and Kaneko4 (plus), originating from Okinawa Prefecture, Japan (Yamada et al 2006), and Mongolia 4 (minus) and Mongolia 1 (plus).…”

Section: Experimental Organisms and Culture And Mating Methodsmentioning

confidence: 99%

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Identification of the Minus-Dominance Gene Ortholog in the Mating-Type Locus of Gonium pectorale

et al. 2008

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The evolution of anisogamy/oogamy in the colonial Volvocales might have occurred in an ancestral isogamous colonial organism like Gonium pectorale. The unicellular, close relative Chlamydomonas reinhardtii has a mating-type (MT) locus harboring several mating-type-specific genes, including one involved in mating-type determination and another involved in the function of the tubular mating structure in only one of the two isogametes. In this study, as the first step in identifying the G. pectorale MT locus, we isolated from G. pectorale the ortholog of the C. reinhardtii mating-type-determining minus-dominance (CrMID) gene, which is localized only in the MT À locus. 39-and 59-RACE RT-PCR using degenerate primers identified a CrMID-orthologous 164-amino-acid coding gene (GpMID) containing a leucine-zipper RWP-RK domain near the C-terminal, as is the case with CrMID. Genomic Southern blot analysis showed that GpMID was coded only in the minus strain of G. pectorale. RT-PCR revealed that GpMID expression increased during nitrogen starvation. Analysis of F 1 progeny suggested that GpMID and isopropylmalate dehydratase LEU1S are tightly linked, suggesting that they are harbored in a chromosomal region under recombinational suppression that is comparable to the C. reinhardtii MT locus. However, two other genes present in the C. reinhardtii MT locus are not linked to the G. pectorale LEU1S/MID, suggesting that the gene content of the volvocalean MT loci is not static over time. Inheritance of chloroplast and mitochondria genomes in G. pectorale is uniparental from the plus and minus parents, respectively, as is also the case in C. reinhardtii.

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Section: Experimental Organisms and Culture And Mating Methodsmentioning

confidence: 99%

“…Heterothallic sexuality in G. pectorale with two mating types, plus and minus, was studied by Schreiber (1925) and Stein (1958). Although only one (plus) of the two conjugating isogametes of C. reinhardtii has a tubular mating structure (TMS), both isogametes of G. pectorale extend a TMS toward the other (Nozaki 1984;Nozaki and Itoh 1994).…”

mentioning

confidence: 99%

Identification of the Minus-Dominance Gene Ortholog in the Mating-Type Locus of Gonium pectorale

et al. 2008

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“…(Coesel, 1988;Ichimura, 198 1, 1985;Ichimura et al, 1987;Lippert, 1967), Cosmarium spp. (Starr, 1959), Gonium pectorale Miiller (Stein, 1958), Pandorina morum Bory (Coleman, 1959), Eudorina spp. (Goldstein, 1964), and Volvulina steinii Playfair (Carefoot, 1966), while no sexual isolation was observed in Platydorina caudata Kofoid (Harris et al, 1969).…”

Section: Allopatry and Sytnpatrymentioning

confidence: 99%

“…Although about six morphospecies have been described in the isogamous colonial green algal genus Gonium (Nozaki et al, 1994), extensive biosystem-4 atic studies are focused on only G. pectorale, which is known to be distributed world-wide (Coleman et al, 1994;Sako et al, 1991;Stein, 1958Stein, , 1965Stein, , 1966aStein, , 1966bStein et al, 1976). At present, we have very limited biogeographic information of the other species (Nozaki, 1993;Pocock, 1955;Pringsheim, 1959;Watanabe, 1977).…”

Section: Gonium Pectorale Millermentioning

confidence: 99%

“…Stein (1958) has first reported sexual isolation between certain strains from the United States, but her further investigations to cover more wide geographic areas turned out to be rather unsatisfactory as to concluding whether or not the populations studied might be divided into two or more sexually isolated groups (Stein, 1965). Degrees of sexual isolation or compatibility were variable among the strains studied.…”

Section: Gonium Pectorale Millermentioning

confidence: 99%

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2. Genome rearrangement and speciation in freshwater algae

Ichimura

1996

Hydrobiologia

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Speciation problems are reviewed in the context of biogeography of fresh-water algae. Currently accepted species concept in phycology is based on morphological characters, and according to this concept, most freshwater algal species are considered cosmopolitan. This implies whether they have a highly efficient means of dispersal or their morphological characters are very static through a long evolutionary time. Recent studies of reproductive isolation show that some biological species of fresh-water algae are not so static or may not have such a high power of dispersal means, though some are indeed very static in morphological characters. The life cycle of most freshwater algae is composed of a vegetative cycle of growth and reproduction and a sexual cycle of gametic fusion and meiosis in the zygote, which forms a dormant spore-like structure. Since any freshwater habitat is ephemeral in terms of evolutionary time scale, each species has a capacity of forming germlings from a dormant cell in order to recycle its life history. The genome of freshwater algae, therefore, contains various coadapted gene systems, at least two, for the vegetative and for the sexual cycle. Homothallism and heterothallism are two contrasting mating systems that represent two opposing ways of life to harmonize antagonism between the vegetative stage of growth and reproduction and the sexual and dormant stage. Geographic and ecological distribution, polyploidy, and sex determination are discussed in conjunction with sexual and postzygotic isolating mechanisms.

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A twelve-step program for evolving multicellularity and a division of labor

2005

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The volvocine algae provide an unrivalled opportunity to explore details of an evolutionary pathway leading from a unicellular ancestor to multicellular organisms with a division of labor between different cell types. Members of this monophyletic group of green flagellates range in complexity from unicellular Chlamydomonas through a series of extant organisms of intermediate size and complexity to Volvox, a genus of spherical organisms that have thousands of cells and a germ-soma division of labor. It is estimated that these organisms all shared a common ancestor about 50 +/- 20 MYA. Here we outline twelve important ways in which the developmental repertoire of an ancestral unicell similar to modern C. reinhardtii was modified to produce first a small colonial organism like Gonium that was capable of swimming directionally, then a sequence of larger organisms (such as Pandorina, Eudorina and Pleodorina) in which there was an increasing tendency to differentiate two cell types, and eventually Volvox carteri with its complete germ-soma division of labor.

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A Morphologic and Genetic Study of Gonium Pectorale

Cited by 72 publications

References 15 publications

Identification of the Minus-Dominance Gene Ortholog in the Mating-Type Locus of Gonium pectorale

Identification of the Minus-Dominance Gene Ortholog in the Mating-Type Locus of Gonium pectorale

2. Genome rearrangement and speciation in freshwater algae

A twelve-step program for evolving multicellularity and a division of labor

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