''Monostroma'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of marine

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

(

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

) in the family Monostromataceae. As the name suggests, algae of this genus are monostromatic (single cell layered). '' Monostroma kuroshiense'', an algae of this genus, is commercially cultivated in

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

for the edible product "hitoegusa-nori" or "hirohano-hitoegusa nori", popular

sushi is a traditional Japanese dish made with , typically seasoned with sugar and salt, and combined with a variety of , such as seafood, vegetables, or meat: raw seafood is the most common, although some may be cooked. While sushi comes in n ...

wraps. ''Monostroma''

oligosaccharides An oligosaccharide (; ) is a saccharide polymer containing a small number (typically three to ten) of monosaccharides (simple sugars). Oligosaccharides can have many functions including cell recognition and cell adhesion. They are normally presen ...

with

degree of polymerization The degree of polymerization, or DP, is the number of structural unit, monomeric units in a macromolecule or polymer or oligomer molecule. For a homopolymer, there is only one type of monomeric unit and the ''number-average'' degree of polymeriza ...

6 prepared by agarase digestion from ''Monostroma nitidum''

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...

have been shown to be an effective prophylactic agent during ''

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

'' and ''

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, an ...

'' tests against Japanese encephalitis viral infection. The sulfated oligosaccharides from ''Monostroma'' seem to be promising candidates for further development as antiviral agents. The genus ''Monostroma'' is the most widely cultivated genus among green

Classification

Species-level classification within this genus is quite problematic and no consensus exists among algal taxonomists. This genus is oftentimes referred as "''Gayralia''", however ''Gayralia'' and ''Monostroma'' are congeneric. A number of monostromatic algal species have been removed from this genus, including Kornmannia, Ulvopsis and Capsosiphon. Currently accepted working-classification of monostromatic green algae is provided as a figure. A taxonomic field-identification dichotomous key for this genus is available

Genetics

Largest phylogeographic assessment of this genus yet conducted in SW

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

revealed existence of

sympatric speciation Sympatric speciation is the evolution of a new species from a surviving Common descent, ancestral species while both continue to inhabit the same geographic region. In evolutionary biology and biogeography, ''sympatric'' and ''sympatry'' are ter ...

in a panmictic population; the first report of sympatric speciation in algae

Ecophysiology, cultivation and life cycle

A number of peer-reviewed scientific literature exists on the

ecophysiology Ecophysiology (from Greek , ''oikos'', "house(hold)"; , ''physis'', "nature, origin"; and , '' -logia''), environmental physiology or physiological ecology is a biological discipline that studies the response of an organism's physiology to envir ...

of this algal genus. Natural and cultivated sexually reproducing environmental samples, as well as sexually reproducing and serendipitously discovered asexually reproducing

ecotype Ecotypes are organisms which belong to the same species but possess different phenotypical features as a result of environmental factors such as elevation, climate and predation. Ecotypes can be seen in wide geographical distributions and may event ...

s of monostromatic green alga from Tosa Bay, Japan are conspecific (belong to the same species). Patterns of seasonal fluctuations in its thallus lengths were

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

specific and recur annually. Both appearance and decay of thalli were earlier at high saline habitats, suggesting that salinity positively influences either maturation of

sporophyte A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...

s or senescence of

gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the se ...

s. Results from life cycle, thallus ontogeny, gametangial ontogeny and phylogenetic analyses suggest that this algal genus is evolutionarily affiliated in the order Ulotrichales. Type of life cycle is not a valid diagnostic character for the species circumscription in Monostromataceae

Reproduction and sex-ratio

Gametogenesis in this alga occurs in discontinuous patches along the frontal apex and the

gametes A gamete ( ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. The name gamete was introduced by the Ge ...

release synchronously in a posterior faced linear fashion by the dehiscence of gametangial sheath, leading to the thallic disintegration. The overall primary

sex ratio A sex ratio is the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. However, many species deviate from an even sex ratio, ei ...

of this alga is about 1:1 which is likely to reflect Fisherian selection.Bast, F., Hiraoka, M., & Okuda, K. 2009. Spatiotemporal Sex Ratios of a Dioecious Marine Green Alga: Monostroma latissimum (Kützing) Wittrock. International Journal on Algae., 11: 141-150.

Culinary use

In Korea, edible ''Monostroma'' species such as ''Monostroma nitidum'' are called '' parae'' (), and eaten as a ''

namul ''Namul'' () refers to either a variety of edible greens or leaves or seasoned herbal dishes made of them. Wild greens are called ''san-namul'' (), and spring vegetables are called ''bom-namul'' (). On the day of Daeboreum, the first full moo ...

'' vegetable. In Japan, dried '' Monostroma kuroshiense'' called aonori is used to season dishes such as

takoyaki Takoyaki ( or ) is a ball-shaped Japanese snack made of a wheat flour-based batter (cooking), batter and cooked in a special molded pan. It is typically filled with minced or diced octopus as food, octopus (''tako''), tempura scraps (''tenkasu' ...

and okonomiyaki. In Okinawa, it is used in a soup called āsa nu ushiru.

References

{{Taxonbar, from=Q3321261 Ulvophyceae genera Ulotrichales