Purple tange

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Purple tange
Porphyra purpurea, from Helgoland, Herbarium Arch

Porphyra purpurea ,
from Helgoland, Herbarium Arch

Systematics
without rank: Archaeplastida
Department : Red algae (Rhodophyta)
Class : Bangiophyceae
Order : Bangiales
Family : Bangiaceae
Genre : Purple tange
Scientific name
Porphyra
C. Agardh

The purple tange ( Porphyra ), also called Porphyrtange , are a genus of red algae in the order of the Bangiales . They are found around the world on the coasts of the sea and are widely used as food and also in the cosmetics industry.

description

The purple rods have a leaf-like, flat, membranous thallus that is purple, purple-red, red-brown or greenish-purple to black-olive in color. It usually consists of only one cell layer (rarely two layers). The shape of the thallus flap is different and ranges from rounded to linear, the size from a few millimeters to three meters. The thallus surface is somewhat slippery, the edge is usually smooth, often wavy, wrinkled or heavily wrinkled. The seaweed is attached to the ground with an adhesive disc, from which the flap arises directly or with a short stalk.

Development cycle

Microscopic image: areas with spermatangia (light) and with zygotospores (dark)

The development cycle of the purple wrack was elucidated by the British algae researcher Kathleen Mary Drew-Baker in 1949 on Porphyra umbilicalis . The visible flap of the thallus is the gametophyte . The male and female gametes are formed on the same or on different specimens at the edge of the thallus ( monocyte or diocyte ). The male gametes arise in yellowish-white packages ( spermatangia ). The female gametes (with or without trichogyne) divide several times after fertilization and form packets of zygotospores, the number of which is species-specific.

These spores are released and germinate into microscopic, branched cell threads, which are called the conchocelis stage because they were previously thought to be a separate genus of algae. The conchocelis cell threads settle on the calcareous shells of mussels or barnacles and anchor themselves in them. At certain temperatures and day lengths, the conchospores are formed on thicker side branches, from which the flat purple tangs grow again. The meiosis can take place both in Conchosporangium, in the released Conchospore or until the scale Thalluslappen, this is then a "genetic chimera " of diploid and haploid cells.

Occasionally, vegetative reproduction occurs through asexual spores, which form new thallus lobes without fertilization.

Occurrence

Porphyra umbilicalis (right) and Porphyra purpurea (front left) at low tide in the Heligoland tidal flats

The purple orange are widespread on the sea coasts worldwide and are found in polar, temperate and tropical seas. Most species (center of diversity ) are found in the North Pacific .

They colonize the coasts from the upper intertidal zone to the flat sublittoral and grow on stones or epiphytically on larger algae. The leaf lobes only survive one summer or winter, depending on the species. The thready conchocelis stage is probably persistent.

Systematics

The first scientific description was in 1824 by Carl Adolph Agardh (In: Systema Algarum , p. 190). The type species is Porphyra purpurea . Within the red algae is Porphyra a very original genre, it has the easiest previously known plastids - genome .

In order to distinguish the species, microscopic features are usually necessary. If the location and location are known, some species can also be identified with the naked eye.

According to molecular biological investigations, the very species-rich genus turned out to be polyphyletic , i.e. it consisted of non-closely related species that had developed simple thallus lobes in convergent development . Therefore, many previous Porphyra species were separated into the genera Boreophyllum , Clymene , Fuscifolium , Lysithea , Miuraea , Pyropia and Wildemania in 2011 (see article Bangiales ). The following economically important species no longer belong to Porphyra :

  • Pyropia yezoensis (Ueda) MSHwang & HGChoi , ( Syn. Porphyra yezoensis Ueda )
  • Pyropia tenera (Kjellman) N. Kikuchi, M.Miyata, MSHwang & HGChoi , (Syn. Porphyra tenera Kjellman )
  • Pyropia columbina (Montagne) WANelson , ( Syn.Porphyra columbina Montagne )

According to AlgaeBase, the genus Porphyra in the narrower sense comprises around 58 species (August 2018).

Porphyra linearis
Porphyra vulgaris

use

Sushi wrapped in purple tang (nori)

Almost all types of the purple rod ( porphyra in the broader sense, including pyropia ) are used as food . A mixture of several species is often harvested. Over a million tons of fresh matter are harvested every year. In Japan, purple tangerines are known as “ nori ”, where Pyropia yezoensis and Pyropia tenera in particular are cultivated industrially on a large scale. In China “Zicai” and “Haidai ” are consumed , in Korea “ Gim / Kim ”. Pyropia columbina is eaten as "Luche" in Chile and as "Karengo" in New Zealand. In England and Ireland, Porphyra umbilicalis and related types of Porphyra are called "Laver" or "Sloke" and are used in traditional cuisine.

The culture of purple barrels began in Tokyo Bay around 1700 . The yield varied greatly from year to year until the generation change and thus the importance of the conchocelis stage, which is only visible with the microscope, was recognized. Today this generation is specially bred and the culture systems are inoculated with it.

The nutritional value of the purple rod lies in its high protein content . About 75% of the proteins and carbohydrates can be used by human digestion, which is a lot for algae. In addition to a lot of protein, Porphyra umbilicalis also contains vitamins A, C, E and B, minerals and polyunsaturated omega-3 fatty acids . This species is also used as an additive for pet food.

The use of purple rods in the cosmetics industry is of further economic importance : Porphyra umbilicalis is used as a natural UV protection in sun creams , against light-induced skin aging and for skin care .

Individual evidence

  1. ↑ a b c d e Wolfram Braune: Marine algae. A color guide to the common benthic green, brown and red algae of the world's oceans . Ruggell: Gantner, 2008, ISBN 978-3-906166-69-8 , pp. 266-268.
  2. ↑ a b c d e f g h Michael D. Guiry in Michael D. Guiry, GM Guiry: Porphyra - In: Algaebase - World-wide electronic publication, National University of Ireland, Galway, http://www.algaebase.org / search / genus / detail /? genus_id = o1032c123ec5363d1 . Retrieved August 23, 2018.
  3. ↑ P. Kornmann, PH Sahling: Sea algae from Helgoland - Benthic green, brown and red algae. Biological Institute Helgoland, Hamburg 1983, ISSN  0017-9957 , pp. 262-264.
  4. ^ Judith E. Sutherland et al .: A new look at an ancient order: generic revision of the Bangiales (Rhodophyta) . In: Journal of Phycology 47 (5), 2011, pp. 1131-1151. doi : 10.1111 / j.1529-8817.2011.01052.x
  5. ↑ Michael Guiry: Nori Cultivation , The Seaweed Site: information on marine algae, accessed November 12, 2015.
  6. ↑ Seaweed Industry Association - Pyropia columbina ( Memento of the original from September 9, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed November 12, 2015. @1@ 2Template: Webachiv / IABot / www.seaweedindustry.com
  7. ^ Robert Edward Lee: Phycology . 5th edition, Cambridge University Press, Cambridge 2018, p. 110.
  8. ↑ Michael Guiry: Seaweed as Human Food , The Seaweed Site: information on marine algae, accessed November 12, 2015.
  9. ↑ a b Seaweed Industry Association - Porphyra umbilicalis ( Memento of the original from September 9, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed November 12, 2015. @1@ 2Template: Webachiv / IABot / seaweedindustry.com

Web links

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