The aim of the present contribution

The aim of the present contribution is to relate the
yield, chemical composition and physical properties of
agar with environmental factors and reproductive stages
along the year in order to contribute to a sustainable
commercial exploitation of Bahía Bustamante algal
resource.
MATERIALS AND METHODS
Sample collection
Gracilaria graciliswas collected between March 2006
and February 2008 from the subtidal in Bahía Bustamante (45°08′S, 66°32′W), Chubut Province, Argentina. Specimens were collected by SCUBA diving. The
sampling units were placed on four transects parallel
to the shore laid 100 m from each other and beginning 100 m away from the shore. On each transect
five square sampling units (0.25 m
2
) were located
at 100 m intervals. Each sampling unit was relocated by GPS, being latitude and longitude for the
first square sampling unit on each transect the following: 45°08.815′S, 66°29.107′W; 45°08.768′S,
66°29.142′W; 45°08.695′S, 66°29.190′W and
45°08.630′S, 66°29.198′W. For seasonal variation in
agar physico-chemical properties, at least 30 random
specimens from May 2006 (autumn), August 2006
(winter), October 2006 (spring) and January 2007
(summer) were sampled from inside each of the
square sampling units. Specimens corresponding to
each season were pooled, air dried and milled for
subsequent polysaccharide extraction.
Environmental physico-chemical variables
For each sampling site,in situ data of temperature,
salinity and pH were taken from the subsurface water.
Water samples were also collected for nutrient analysis,
keeping them refrigerated until arrival at the laboratory.
Nutrient concentrations were analyzed by colorimetric
techniques on a Technicon II autoanalyzer (Emeryville,
CA, USA), at the Marine Chemistry Laboratory of the
Instituto Argentino de Oceanografía (IADO). Nitrates,
nitrites and phosphates were determined as indicated
in Martín et al. (2010).
Polysaccharide extraction procedure
Previously milled random selected plants (10 g dry
weight) were mechanically stirred in water (1 L) at room
temperature (¥3) for 24 h. Room temperature extracts
were pooled (extract RTW). Extraction continued in: (i)
water (1 L) at 70°C (¥3) for 4 h (fractions W70.1–3) and
(ii) water (1 L) at 90°C (¥3) for 4 h (fractions W90.1–3).
After each extraction step, the residue was removed by
centrifugation and the supernatant was concentrated
and freeze-dried. Extracts obtained at room temperature
were thoroughly dialyzed using Spectra/Por tubing
(Spectrum Laboratories, Rancho Domínguez, CA, USA)
with a molecular weight cutoff of 3500 Da before freezedrying. Dialyses were performed during 48 h in running
tap water followed by 24 h dialysis in a closed system
against distilled water.
Composition of the products
Carbohydrate content was analyzed by the phenolsulfuric acid method (Duboiset al., 1956) without previous hydrolysis of the polysaccharide, using galactose
as standard. Sulfate was measured with the turbidimetric method of Dodgson and Price (1962) after hydrolysis of the samples with 1 M HCl for 4–5 h at 105–
110°C. The content of protein was estimated by the
method of Lowryet al. (1951).
Monosaccharide composition
Reductive hydrolysis of the polysaccharide samples
and further acetylation of the sugar mixtures were
performed as described by Stevenson and Furneaux
(1991).
Gas Liquid Chromatography (GLC) of alditol acetates
was carried out on a Hewlett-Packard 5890A Gas Chromatograph (Hewlett Packard, Avondale, PA, USA)
equipped with a flame-ionization detector and fitted
with a fused-silica column (0.25 mm i.d.¥ 30 m)
WCOT-coated with 0.20mm film of SP-2330 (Supelco,
Bellefonte, PA, USA). Chromatography of the alditol
acetates was carried out isothermally at 220°C. Nitrogen was used as carrier at a flow rate of 1 mL min
-1
. The
split ratio was 80:1. The injector and detector temperature was 240°C. Conversion of GLC areas to molar
basis was calculated according to the effective carbon
response theory (Sweet et al., 1975).
All data are expressed as means of duplicates.
Alkaline treatment and determination of
cyclizablea-galactose 6-sulfate units
One-pot alkaline treatment was carried out as described
by Navarro and Stortz (2003). The polysaccharide
(10 mg) was dissolved in water (5 mL) and NaBH4
(2 mg) was added. After 1 h, 5 M NaOH (1.7 mL) was
added and the solution heated at 80°C in a water bath.
According to previous results (Rodríguezet al., 2009),
the cyclization reaction was stopped after 5 h by neutralization with 4 M trifluoroacetic acid. The solvent
was evaporated-off and the residue derivatized to
the acetylated alditols according to Stevenson and
Furneaux (1991)

Hasil (Bahasa Indonesia) 1:

Tujuan dari kontribusi sekarang adalah untuk menghubungkanmenghasilkan, komposisi kimia dan sifat fisikagar-agar dengan faktor lingkungan dan tahap reproduksisepanjang tahun untuk berkontribusi berkelanjutaneksploitasi komersial Bahía Bustamante ganggangsumber daya.BAHAN DAN METODEPengambilan sampelGracilaria graciliswas dikumpulkan di antara Maret 2006dan Februari 2008 dari ngangkatan di Bahía Bustamante (45 ° 08′S, 66 ° 32′W), Provinsi Chubut, Argentina. Spesimen yang dikumpulkan oleh SCUBA diving. Thesampling unit ditempatkan pada empat dnegan paralelke pantai meletakkan 100 m dari satu sama lain dan mulai 100 m dari pantai. Pada setiap transectlima persegi sampling unit (0.25 m2) beradainterval 100 m. Setiap unit sampel dipindahkan oleh GPS, lintang dan bujur untukunit persegi sampling pertama pada masing-masing transect berikut: 45 ° 08. 815′S, 66 ° 29. 107′W; 45 ° 08. 768′S,66 ° 29. 142′W; 45 ° 08. 695′S, 66 ° 29. 190′W dan45 ° 08. 630′S, 66 ° 29. 198′W. Untuk variasi musimanagar sifat fisiko-kimia, minimal 30 acakspesimen dari Mei 2006 (musim gugur), Agustus 2006(musim dingin), Oktober 2006 (musim semi) dan Januari 2007(musim panas) sampel dari di dalam setiappersegi sampling unit. Spesimen yang sesuaiSetiap musim yang menggenang, udara kering dan digiling untukekstraksi polisakarida berikutnya.Variabel psiko-kimia lingkunganUntuk setiap situs sampling, data di situ suhu,salinitas dan pH diambil dari bawah permukaan air.Sampel air juga dikumpulkan untuk analisis gizi,menjaga mereka didinginkan sampai tiba di laboratorium.Konsentrasi nutrisi yang dianalisis oleh colorimetricteknik autoanalyzer Technicon II (Emeryville,CA, USA), di laboratorium kimia lautArgentino Instituto de Oceanografía (IADO). Nitrat,nitrit dan fosfat ditentukan seperti yang ditunjukkandi Martín et al. (2010).Prosedur ekstraksi polisakaridaSebelumnya giling tanaman dipilih acak (10 g keringberat) mekanis diaduk dalam air (1 L) di kamarsuhu (¥ 3) untuk ekstrak suhu kamar 24 h.yang terkumpul (ekstrak RTW). Ekstraksi terus: (i)air (1 L) pada 70° C (¥ 3) untuk 4 h (fraksi W70.1-3) dan(ii) air (1 L) pada 90° C (¥ 3) untuk 4 h (fraksi W90.1-3).Setelah setiap langkah ekstraksi, residu dipindahkan olehsentrifugasi dan supernatant yang terkonsentrasidan beku-kering. Ekstrak yang diperoleh pada suhu kamarbenar-benar dialyzed menggunakan tabung Spectra Por(Spektrum laboratorium, Rancho Domínguez, CA, Amerika Serikat)dengan berat molekul cutoff 3500 Da sebelum freezedrying. Dialyses dilakukan selama 48 jam dalam menjalankanair keran yang diikuti oleh 24 h dialisis dalam sistem tertutupterhadap air suling.Komposisi ProdukKandungan karbohidrat dianalisis dengan metode asam phenolsulfuric (Duboiset al., 1956) tanpa sebelumnya hidrolisis dari polisakarida, menggunakan galaktosasebagai standar. Sulfat diukur dengan metode turbidimetric Dodgson dan harga (1962) setelah hidrolisis sampel dengan HCl M 1 untuk 4-5 h pada 105-110° C. Kandungan protein diperkirakan olehmetode Lowryet al. (1951).Komposisi monosakaridaReduktif hidrolisis polisakarida sampeldan lebih lanjut acetylation campuran guladilakukan seperti yang dijelaskan oleh Stevenson dan Furneaux(1991).Gas cair kromatografi (GLC) dari alditol asetatdilakukan pada Hewlett-Packard 5890A Gas Chromatograph (Hewlett Packard, Avondale, PA, Amerika Serikat)dilengkapi dengan detektor api-ionisasi dan dipasangdengan kolom silika menyatu (0.25 mm i.d.¥ 30 m)WCOT dilapisi dengan film 0.20mm SP-2330 (Supelco,Bellefonte, PA, USA). Kromatografi alditolasetat dilaksanakan isothermally di 220° C. Nitrogen digunakan sebagai pembawa pada laju alir 1 mL min-1. Therasio Split adalah 80:1. Suhu injeksi dan detektor adalah 240° C. Konversi GLC daerah molardasar dihitung menurut karbon yang efektifrespon teori (manis et al., 1975).Semua data yang dinyatakan sebagai sarana duplikat.Perlakuan alkali dan penentuancyclizablea-galaktosa 6-sulfat unitSatu-pot alkali pengobatan dilakukan seperti yang dijelaskanNavarro dan Stortz (2003). Polisakarida(10 mg) dilarutkan dalam air (5 mL) dan NaBH4(2 mg) ditambahkan. Setelah 1 h, 5 M NaOH (1.7 mL) adalahditambahkan dan solusi dipanaskan pada 80° C dalam penangas air.Menurut hasil sebelumnya (Rodríguezet al., 2009),reaksi cyclization dihentikan setelah 5 h oleh netralisasi dengan 4 M trifluoroacetic asam. Pelaruttelah menguap dan residu derivatized untukalditols acetylated menurut Stevenson danFurneaux (1991)