seaweed-biotechnology

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5 Δεκ 2012 (πριν από 4 χρόνια και 9 μήνες)

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SEAWEED BIOTECHNOLOGY


Seaweed = macroal
g
a

Green: Chlorophyta

Red: Rhodophyta

Brown: Phaeophyta


Seaweed usage:

Food: as “vegetables” in many countries

Pharmaceuticals & Neutraceuticals


novel chemical compounds

Eg. Halogen
a
ted monoterpenes


Ochtodes secundiramea

Red alga Callophycus serratus


10 new molecular structures: potential to kill cancer cells, bacteria, HIV

Fertilizers: seaweed extracts, humic acids, kelp meals, amino acids, fulvic acid, compost


nutrient
source (macro & micro
-
nut
rients, plant growth hormones), eg.
m
ainly brown algae


contain several
polysaccharides: alginales

Bioremediation: heavy metal contamination such as Cu & Fe


toxic effects: generalized anaesthetic
effects on cell membrane, disruption of essential enzymes
, and displacement of essential ions. Eg.
Porphyra


Co and Cd uptake. Powder of green and red seaweed mixed with DDT
-
contaminated soil


80% toxic chemical disappeared in 6 weeks.

Hydrocolloids: agar, agarose, carrageenan, allginate


industries: fo
od, ph
armaceutical, cosmetic,
textile, photography, laboratorial usage
, etc.

Pigments: for industry

Ecology: supply of O2, primary producers

Traditional Chinese medicine: eg. Digenea simplex, Caloglossa leprieurii


antihelminths

Modern

Chinese
: 46 genera, >

100 species


for food, medicine, fertilizers, raw material in industry:
phycocolloids, mannitol, iodine, etc.


Biotechnology

Tissue & cell culture

Genetic manipulation


economic aspect

Plant propagation

e
g.
c
allus


bioprocess technology: production of h
igh value chemicals in pharmace
u
ticals,
neutraceuticals, etc.

Micropropagation techniques: cultivation, secondary metabolites prod
uction, genetic improvement,
sus
tainable development & utilization of seaweed

Clonal propagation & Selection of strains


Organ
ogenetic
p
otential of important seaweeds, eg. Chondrus, Gigartina, Gracilaria, Kappaphycus

Mass production, mariculture:

a. mass generation of planting material for tank
-
bubbling and field cultivation using fragments and cell
aggregates of apical meristem,

b. freeze
-
thawing of apical meristem tissues enabled the production of plantlets producing rhizoids: for
cultivation in

the sea.

Mass plantlets and tetraspores from fragments and cell aggregates of meristematic and
submeristematic tissue of Palmeria palmata.

Simple vegetative propagation of thallus segments (2


3 cm long) in laboratory culture


deals with
species non

re
sponsive to time and protoplast culture. Selection of elite germplasm is a continous
process and a substantial amount of harvest is utilized as seed material for subsequent cultivation.

Isolation of useful mutants for cultivation


successful as genetic variant cells in thallus


lead to
develop in vitro cell culture technology


Tissue Culture

Genetic engineering of crop plants

Micropropagation using tissue culture methods


large scale propagation of clones with superior traits

Cel
l suspension allow a very large number of cells to be screened simultaneously for a desired trait in a
reasonable time frame and reproducible manner.

Note: alteration of generations (haploid and diploid)


effective in genetic improvement. Haploid tissue
e
nable easy detection of mutants, subsequent chromosome doubling produces fertile individual
homozygous


pure breeding lines for selection and hybridization.

Methods:

Involve preparation of axenic explants and their cultures on solid agar medium enriched w
ith a range of
macro
-

and micronutrients, vitamins, sugar, plant growth regulators (auxins & cytokinins).

eg. Photo
-
bioreactors


advantage: enbale of continous, steady and defined production of high yields
of quality products

Type of study: callus formati
on, morphogenesis, role of plant growth in morphogenesis, role of carbon
source on callus development & growth, clonal propagation, etc.


Protoplast Biotechnology

Cells or tissues with specific cell wall treated with lytic enzymes


total removal of their
rigid and
complex polysaccharide cell walls

Enzymatic methods: seaweed exhibit a variety & complexity in their cell wall composition


combination of specific enzymes are needed to digest the cell wall.

Protoplasts research: to date 89 species, green: cell
ulase or in combination with macerozyme, brown
and red: alginase and agarase/carrageenase and cellulase


Factors affecting

Enzyme constituents, concentrations, pH, osmotic conditions and ionic strength of protoplast isolation
medium, incubation
temperature, physiological state and age of donor plant, and protoplast culture
medium and its culture conditions.

Function: seed stock for cultivation of green seaweed, stock for seedling (micro thalli): Ulva,
Monostroma, seeding and regeneration in laboa
ratory: Monostroma, Porphyra

Physiological studies: mechanism of inorganic carbon uptake in Chondrus crispus, Ulva rigida, Gracilaria
tenuestipitata
, O2 evolution rate to evaluate whether the isolated protoplasts are in the same
physiological state as cel
ls in an intact plant

Fusing protoplasts of different origins


produce novel somatic hybrids


study somatic cell genetics,
eg. Fusion of zoospores of Enteromorpha and Ulvaria


regeneration of intraspecific
-
parasexual hybrids


Genetic Transformation

eg.
Transient expression of the bacterial beta
-
glucoronidase gene (gus) in the carrageenan producing
red alga Kappaphycus alvarezii

Expressed sequence Tags (ESTs) from protoplasts and thalli


to identify the genes involved in cell wall
regeneration and stress

responses in Chondrus crispus and Laminaria digitata.

Method: using cDNA sequence

5 catagories:

a. those identical to a portion of a known gene

b. those with sequence similarity to a known gene

c. those which do not show sequence similarity but with stru
ctural similarity to one or more known
sequences

d. those which do not match anything in the database

e. those that can be deemed useless as they are either devoid or meaningful sequences or have
matched sequences of contaminating organisms


promoter selec
tion: 2 promoters have been used most often

1. NOS (nopaline synthase) from A. tumefaciens T
-
DNA

2. 35S from cauliflower mosaic virus (CaMV)

Promoter selection


efficiency of expression of foreign genes in transformants


Table 1. The timeline of seaweed r
esearch

Years

Activity/Research Highlights

1940s

Discovery of hydrocolloids from seaweed, seaweed biology, research on seaweed as
food

1952

First International Seaweed Symposium in Scotland

1960s


1970s

Taxonomic classificaion, biogeography and
ecophysiology of seaweeds

1980s


early 1990s

Mutant studies, seaweed cultivation and biotechnology, properties of hydrocolloids and
their applications in industries, drug discovery and bioactive compounds from seaweeds,
classical genetics

Mid 1990s

Gene
tic transformation and tissue culture, molecular phylogenetics, small
-
scale gene
cloning and characterization

1997

Introduction of EST approach in large
-
scale study on molecular genetics

2000s
-


Search of a model plant for large
-
scale genomic study, shi
ft to multi
-
disciplinary research

Source: Chan
et al
. 2005(?)