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Hypnea

{{Short description|Genus of algae}}

{{technical|date=October 2014}}

{{Automatic taxobox

| image = Hypnea musciformis.jpg

| image_alt = Hypnea musciformis

| image_caption = Hypnea musciformis

| taxon = Hypnea

| authority = J.V.Lamouroux, 1813

| subdivision_ranks = Species

| subdivision = See text

}}

Hypnea is a genus of red algae, and a well known carrageenophyte (plant producing polysaccharide carrageenan).

Taxonomy and nomenclature

Hypnea is a genus of red seaweed under class Florideophyceae, order Gigartinales, and family Cystocloniaceae. There are 99 species listed on Algaebase with 78 being accepted taxonomically.M.D. Guiry in Guiry, M.D. & Guiry, G.M. September 26, 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on January 23, 2022. The genus was originally classified under family Hypneaceae,{{Cite book|last=Agardh|first=Jacob Georg|url=http://dx.doi.org/10.5962/bhl.title.1576|title=Species, genera et ordines algarum : seu descriptiones succinctae specierum, generum et rodinum, quibus algarum regnum constituitur / auctore Jacobo Georgio Agardh.|date=1848|publisher=apud C.W.K. Gleerum|location=Lundae|doi=10.5962/bhl.title.1576}} which was considered distinct from Cystoclonoiaceae on the basis of differences in their carposporophyte structure,Kylin H (1930) Über die entwicklungsgeschichte der Florideen. Lunds Univ Årsskr NF Avd 2:1–127Womersley HBS (1994) The marine benthic flora of southern Australia - Part IIIA - Bangiophyceae and Florideophyceae (Acrochaetiales, Nemaliales, Gelidiales, Hildenbrandiales and Gigartinales sensu lato). Australian Biological Resources Study, Canberra 508p and the shape of the thalli and cortical cells. Differences in carrageenan chemistry, with Hypneaceae species producing kappa-carrageenan and Cystocloniaceae producing lambda-carrageenan, was another reason for their distinction.{{Cite journal|last1=Chiovitti|first1=Anthony|last2=Kraft|first2=Gerald T.|last3=Bacic|first3=Antony|last4=Craik|first4=David J.|last5=Munro|first5=Sharon L. A.|last6=Liao|first6=Ming-Long|title=Carrageenans from Australian Representatives of the Family Cystocloniaceae (Gigartinales, Rhodophyta), with Description of Calliblepharis celatospora sp. nov., and Transfer of Austroclonium to the Family Areschougiaceae|date=1998|url=http://dx.doi.org/10.1046/j.1529-8817.1998.340515.x|journal=Journal of Phycology|volume=34|issue=3|pages=515–535|doi=10.1046/j.1529-8817.1998.340515.x|s2cid=86478056|issn=0022-3646|url-access=subscription}} However, these criteria were questioned and molecular analysis later showed that the two families had similar vegetative and reproductive characters.{{Cite journal|last1=Fredericq|first1=Suzanne|last2=Hommersand|first2=Max. H.|last3=Freshwater|first3=D. Wilson|date=1996|title=The molecular systematics of some agar- and carrageenan-containing marine red algae based on rbcL sequence analysis|url=http://dx.doi.org/10.1007/bf00047797|journal=Hydrobiologia|volume=326-327|issue=1|pages=125–135|doi=10.1007/bf00047797|s2cid=34794358|issn=0018-8158|url-access=subscription}}{{Cite journal|last1=Saunders|first1=Gary W|last2=Chiovitti|first2=Anthony|last3=Kraft|first3=Gerald T|date=2004-01-01|title=Small-subunit rDNA sequences from representatives of selected families of the Gigartinales and Rhodymeniales (Rhodophyta). 3. Delineating the Gigartinales sensu stricto|url=http://dx.doi.org/10.1139/b03-110|journal=Canadian Journal of Botany|volume=82|issue=1|pages=43–74|doi=10.1139/b03-110|issn=0008-4026|url-access=subscription}} Furthermore, it was proven that lambda-carrageenan and kappa-carrageen coexist within the Gigartinales order. This led to the two families being merged into simply Cystocloniaceae.

= Phylogenetics =

Phylogeography of Hypnea valentiae in India indicates that nuclear ribosomal DNA Internal transcribed spacer-1 (ITS1) sequences had 4.35 x 10-1 Tamura 3-parameter (T3P) pairwise distance between them, which indicate significant evolutionary differences accumulated over time.Bast, F. Bhushan, S. and John, A.A. 2014. Morphological and molecular assessment of native carrageenophyte Hypnea valentiae (Cystocloniaceae, Gigartinales) in Indian Subcontinent Phykos 44(1) 52-58 {{ISSN|0554-1182}} In comparison, T3P distance between related genera Kappaphycus and Eucheuma was 1.85 x 10–1. In phylogeny reconstruction using Bayesian inference, both the isolates formed a well-supported clade along with the only available accession of this genus at ITS1 locus, indicating affiliation of both the isolates in this genus. The isolate from the west coast was more basal in the phylogram, which suggests phylogenetically primitive position of this population. Newly generated DNA barcodes of the geographic isolates of this native carrageenophyte in this study is expected to be a key in tracing its further dispersal routes, either natural or deliberate. This is the first report on the comparative morphological and molecular assessment of Hypnea from India.

Morphology

File:Hypnea cf. pannosa.jpg

Hypnea is characterized by membranous or cartilaginous thalli which can be either erect or prostrate. The thallus features a main axis with an apex of varying shapes (straight, curved, tendril or bifurcated). Various forms of branching occur, with the irregular type being most common, with dichotomous or lateral branching occurring in some species. Thallus color is highly variable, with yellow, green, pink, red, brown and black being observed. Habitat type can influence thallus length, which varies from 0.5 to 50 cm.{{Cite journal|last1=Yokoya|first1=Nair S.|last2=Nauer|first2=Fabio|last3=Oliveira|first3=Mariana C.|date=2020-08-25|title=Concise review of the genus Hypnea J.V.Lamouroux, 1813|url=http://dx.doi.org/10.1007/s10811-020-02209-x|journal=Journal of Applied Phycology|volume=32|issue=6|pages=3585–3603|doi=10.1007/s10811-020-02209-x|s2cid=221310877|issn=0921-8971|url-access=subscription}} The habit of the thallus is used to divide species into two major groups: those with >10 cm thallus height, and those that measure between 2–3 cm. Like many other algal species, Hypnea exhibits a high degree of phenotypic plasticity and cryptic diversity which makes species difficult to distinguish from each other morphologically since they share many characters.{{Cite journal|last1=Yamagishi|first1=Yukimasa|last2=Masuda|first2=Michio|date=2000|title=A taxonomic revision of a Hypnea charoides-valentiae complex (Rhodophyta, Gigartinales) in Japan, with a description of Hypnea flexicaulis sp. nov.|url=http://dx.doi.org/10.1111/j.1440-1835.2000.tb00127.x|journal=Phycological Research|volume=48|issue=1|pages=27–35|doi=10.1111/j.1440-1835.2000.tb00127.x|issn=1322-0829|url-access=subscription}}{{Cite journal|last1=Nauer|first1=Fábio|last2=Guimarães|first2=Natália R.|last3=Cassano|first3=Valéria|last4=Yokoya|first4=Nair S.|last5=Oliveira|first5=Mariana C.|date=2014-10-02|title=Hypneaspecies (Gigartinales, Rhodophyta) from the southeastern coast of Brazil based on molecular studies complemented with morphological analyses, including descriptions ofHypnea edenianasp. nov. andH. flavasp. nov.|journal=European Journal of Phycology|volume=49|issue=4|pages=550–575|doi=10.1080/09670262.2014.981589|s2cid=83719031|issn=0967-0262|doi-access=free}}

Distribution

The genus is found in the Atlantic, Pacific, and Indian Oceans, with the Atlantic having the most species. In terms of countries, China has the most number of species although none are endemic. Other countries with many endemic species of Hypnea include South Africa, Australia, Japan, Indonesia, Mauritius, the Philippines, India, and Brazil. Hypnea musciformis has the widest geographical distribution.

Ecology

Hypnea is commonly present in various habitats, from intertidal and subtidal zones, as well as in sites with varying degrees of exposure. They can also be found growing as epiphytes on other organisms such as the brown alga Sargassum. The genus exhibits seasonal abundance which is highly influenced by similarly seasonal variations in light, temperature, and tidal levels.{{Cite journal|last1=Reis|first1=Renata Perpetuo|last2=Leal|first2=Marta Correa Ramos|last3=Yoneshigue-Valentin|first3=Yocie|last4=Belluco|first4=Frederico|date=2003|title=Efeito de fatores bióticos no crescimento de Hypnea musciformis(Rhodophyta - Gigartinales)|journal=Acta Botanica Brasilica|volume=17|issue=2|pages=279–286|doi=10.1590/s0102-33062003000200010|issn=0102-3306|doi-access=free}}

Life history

Hypnea exhibits a dioecious thallus and a triphasic life cycle consisting of two diploid phases and a haploid phase. The diploid carposporophyte releases carpospores that develop into a diploid tetrasporophyte which undergoes meiosis to form four haploid tetraspores which will form 50/50 male and female gametophytes. After fertilization of gametes, the carposporophyte is formed and the cycle begins again.{{Cite journal|last1=Nauer|first1=Fábio|last2=Ayres-Ostrock|first2=Lígia|last3=Amorim|first3=Ana Maria|last4=Santos|first4=Janaína Pires|last5=Chow|first5=Fungyi|last6=Plastino|first6=Estela M.|last7=Oliveira|first7=Mariana C.|date=2018-09-15|title=Life history, growth, and pigment content of two morphological variants of Hypnea pseudomusciformis (Gigartinales, Rhodophyta)|url=http://dx.doi.org/10.1007/s10811-018-1630-z|journal=Journal of Applied Phycology|volume=31|issue=2|pages=1271–1284|doi=10.1007/s10811-018-1630-z|s2cid=52279029|issn=0921-8971}}

Chemical composition

Carrageenans are abundant in the cell walls of some red algae, where they provide the thallus with additional flexibility to protect it from the impacts of herbivory, wave action, and desiccation. Environmental variables such as temperature, amount of rainfall, and salinity likely influence the yield and viscosity of the carrageenan.

Cultivation and utilization

Hypnea is cultivated in many tropical countries such as the Philippines, Brazil, Bangladesh, India and Vietnam for food and for their kappa- carrageenan extracts.Zemke-White W, Lindsey L, Masao Ohno M (1999) World seaweed

utilisation: an end-of-century summary. J Appl Phycol 11:369–376 After Eucheuma/Kappaphycus, it is the second most important source of carrageenan in the tropics, however it is only cultivated in experimental settings and not commercially. The technology needed to do this is still being developed and requires further investigation.{{Cite journal|last1=Pereira|first1=Stefany A.|last2=Kimpara|first2=Janaina M.|last3=Valenti|first3=Wagner C.|date=2020|title=A simple substrate to produce the tropical epiphytic algae Hypnea pseudomusciformis|url=http://dx.doi.org/10.1016/j.aquaeng.2020.102066|journal=Aquacultural Engineering|volume=89|pages=102066|doi=10.1016/j.aquaeng.2020.102066|s2cid=216379247|issn=0144-8609|url-access=subscription|hdl=11449/197085|hdl-access=free}} Most experimental cultivation activities have been done using Hypnea musciformis, and its highly variable morphology may be partly responsible for the inconsistency in the results of these experiments.ZubiaM, Olivier P, Thomas OP, Soulet S, Demoy-SchneiderM, Saulnier D, Connan S, Murphy EC, Tintillier F, Stiger-Pouvreau V, Petek S (2019) Potential of tropical macroalgae from French Polynesia for biotechnological applications. J Appl Phycol. {{doi|10.1007/s10811-019-01920-8}}{{Cite journal|last1=Pangestuti|first1=Ratih|last2=Getachew|first2=Adane Tilahun|last3=Siahaan|first3=Evi Amelia|last4=Chun|first4=Byung-Soo|date=2019-02-22|title=Characterization of functional materials derived from tropical red seaweed Hypnea musciformis produced by subcritical water extraction systems|url=http://dx.doi.org/10.1007/s10811-019-1754-9|journal=Journal of Applied Phycology|volume=31|issue=4|pages=2517–2528|doi=10.1007/s10811-019-1754-9|s2cid=71148038|issn=0921-8971|url-access=subscription}}

Carrageenan has a wide range of applications from food to pharmaceutical uses. The extracts of various Hypnea species have been investigated for their antiviral, antibacterial, antioxidant and antifungal properties.{{Cite journal|last1=Mendes|first1=Gabriella da Silva|last2=Bravin|first2=Isolda Cecília|last3=Yoneshigue-Valentin|first3=Yocie|last4=Yokoya|first4=Nair S.|last5=Romanos|first5=Maria Teresa Villela|date=2012|title=Anti-HSV activity of Hypnea musciformis cultured with different phytohormones|journal=Revista Brasileira de Farmacognosia|volume=22|issue=4|pages=789–794|doi=10.1590/s0102-695x2012005000054|issn=0102-695X|doi-access=free}}{{Cite journal|last1=Machado|first1=Levi Pompermayer|last2=Matsumoto|first2=Silvia Tamie|last3=Jamal|first3=Claudia Masrouah|last4=da Silva|first4=Marcelo Barreto|last5=da Cruz Centeno|first5=Danilo|last6=Neto|first6=Pio Colepicolo|last7=de Carvalho|first7=Luciana Retz|last8=Yokoya|first8=Nair S|date=2013-12-18|title=Chemical analysis and toxicity of seaweed extracts with inhibitory activity against tropical fruit anthracnose fungi|url=http://dx.doi.org/10.1002/jsfa.6483|journal=Journal of the Science of Food and Agriculture|volume=94|issue=9|pages=1739–1744|doi=10.1002/jsfa.6483|pmid=24255023|issn=0022-5142|url-access=subscription}}Heidarizadeh L, Mollataghi A, Saadat A, Mostoufi A, Mouradzadegun A, Seyednejad AS (2019) Phytochemical studies and their bioactivities of various crude extracts of red alga (Hypnea boergesenii). Basic Res J Microbiol 6:23–33

Known species

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References

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Category:Red algae genera

Category:Gigartinales