''Dictyota bartayresiana'', commonly known as a forded sea tumbleweed, is a species of

brown alga Brown algae (singular: alga), comprising the class (biology), class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the ...

found in the tropical western Indo-Pacific region and the Gulf of Mexico. It contains chemicals that are being researched for possible use as

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

s, as

larvicide A larvicide (alternatively larvacide) is an insecticide that is specifically targeted against the larval life stage of an insect. Their most common use is against mosquitoes. Larvicides may be contact poisons, stomach poisons, growth regulators, o ...

s and as

cytotoxins Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cell ...

Description

''Dictyota bartayresiana'' grows to a height of , being anchored to the seabed by a variably-shaped holdfast surrounded by

rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be unic ...

s. The blades are flat and branch dichotomously. The thallus is wide below each junction and wide just above; the sections are long and have no midrib. The margins of the blade are entire and the tips rounded in young fronds and pointed in older ones. The sporangia are 125 to 140 µm in diameter.

Distribution and habitat

This seaweed is found in the tropical western central Pacific Ocean and the tropical western Atlantic Ocean, including the Gulf of Mexico. It occurs at depths down to about .

Research

Several

diterpene Diterpenes are a class of chemical compounds composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being ...

s and other

secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norm ...

s are present in ''D. bartayresiana''. The

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...

ic and

chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to ...

extracts of the seaweed exhibit antibacterial activity against ''

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...

'', ''

Shigella flexneri ''Shigella flexneri'' is a species of Gram-negative bacteria in the genus ''Shigella'' that can cause diarrhea in humans. Several different serogroups of ''Shigella'' are described; ''S. flexneri'' belongs to group ''B''. ''S. flexneri'' infecti ...

'' and ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aerugi ...

'', and the petroleum extract exhibits a similar effect against ''

Morganella morganii ''Morganella morganii'' is a species of Gram-negative bacteria.eMedicineMorganella infections/ref> It has a commensal relationship within the intestinal tracts of humans, mammals, and reptiles as normal flora. Although ''M. morganii'' has a wide ...

''. The methanolic extract is also effective as a

against the mosquito ''

Culex quinquefasciatus ''Culex'' is a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals. The diseases they vector include arbovirus infections such as West Nile virus, Japanese encep ...

'', and shows toxicity to the

nauplii Nauplius, Nauplia or Nauplios , may refer to : Greece-related * Nauplius (mythology), in Greek mythology, the son of Poseidon and Amymone, the father of Palamedes, and also the name of an Argonaut * Nauplia Nafplio ( ell, Ναύπλιο) is a ...

larvae of

brine shrimp ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia La ...

s, a proxy for

antitumour Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...

activity. This means that the seaweed shows promise as a broad spectrum antibacterial, a

and a cytotoxic substance. Further research is needed to identify the active ingredients responsible for these effects.

Ecology

The diterpenes contained in this alga are distasteful to fish, which avoid eating the seaweed. ''

Pseudamphithoides incurvaria ''Pseudamphithoides incurvaria'' is a species of amphipod crustacean in the family Ampithoidae. It is native to shallow water in the tropical western Atlantic Ocean where it creates a home for itself from fragments of the algae on which it feeds. ...

'', a species of

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

, feeds on the seaweed and builds a "domicile" from fragments of the fronds, and lives inside this. This casing deters potential fish predators from eating the amphipod.

References

{{Taxonbar, from=Q29890033 Dictyotaceae