Transcriptional dynamics of gametogenesis in the green seaweed Ulva mutabilis identifies an RWP-RK transcription factor linked to reproduction

Background The molecular mechanism underlying sexual reproduction in land plants is well understood in model plants and is a target for crop improvement. However, unlike land plants, the genetic basis involved in triggering reproduction and gamete formation remains elusive in most seaweeds, which are increasingly viewed as an alternative source of functional food and feedstock for energy applications. Results Gametogenesis of Ulva mutabilis, a model organism for green seaweeds, was studied. We analyzed transcriptome dynamics at different time points during gametogenesis following induction of reproduction by fragmentation and removal of sporulation inhibitors. Analyses demonstrated that 45% of the genes in the genome were differentially expressed during gametogenesis. We identified several transcription factors that potentially play a key role in the early gametogenesis of Ulva given the function of their homologs in higher plants and microalgae. In particular, the detailed expression pattern of an evolutionarily conserved transcription factor containing an RWP-RK domain suggested a key role during Ulva gametogenesis. Conclusions Transcriptomic analyses of gametogenesis in the green seaweed Ulva highlight the importance of a conserved RWP-RK transcription factor in the induction of sexual reproduction. The identification of putative master regulators of gametogenesis provides a starting point for further functional characterization.

PENGARUH PENAMBAHAN TEPUNG RUMPUT LAUT HIJAU (Ulva lactuca L.) DAN TEPUNG SUKUN (Artocarpus altilis) TERHADAP KARAKTERISTIK FISIKOKIMIA DAN ORGANOLEPTIK MIE BASAH

ABSTRACTThis study aimed to determine the effect of breadfruit flour and green seaweed flour formulation on the physicochemical and organoleptic characteristics of wet noodles. This study used a completely randomized design (CRD) using the formulations of wheat flour, breadfruit flour and green seaweed flour M1 (70:28:2), M2 (70:26:4), M3 (70:24:6), and M4 (70:22:8). The results show that the formulation of breadfruit flour and green seaweed flour had a very significant effect on improving the organoleptic characteristics of color, aroma, taste, and texture of wet noodles. The best product based on the organoleptic assessment was found in the M4 formulation (70% wheat flour formulation, 22% breadfruit flour, and 8% green seaweed flour) with assessment scores of color, aroma, taste, and texture, reached 3.81 (like), 2.98 (slightly like), 2.92 (slightly like) and 3.84 (like), respectively. The chemical analysis shows that the best wet noodle product contaiend 57.68% water, 1.23% ash, and 0.09% crude fiber. The highest antioxidant activity was obtained in the M4 treatment, which reached 62.50%. Based on the results of the study, the wet noodle product with the formulation of breadfruit flour and green seaweed flour was preferred by the panelists and met the national standards for ash and water contents.Keywords: wet noodle, fermented cassava flour, breadfruit flourABSTRAKPenelitian ini bertujuan untuk menentukan pengaruh formulasi tepung sukun dan tepung rumput laut hijau terhadap karakteristik fisikokimia dan organoleptik mie basah. Penelitian ini menggunakan rancangan acak lengkap (RAL) dengan menggunakan formulasi tepung terigu, tepung sukun dan tepung rumput laut hijau M1 (70:28:2), M2 (70:26:4), M3 (70:24:6), M4 (70:22:8). Hasil penilaian menunjukan bahwa formulasi tepung sukun dan tepung rumput laut hijau berpengaruh sangat nyata terhadap peningkatan uji organoleptik warna, aroma, rasa dan tekstur mie basah. Berdasarkan penilaian organoleptik terdapat pada formulasi M4 (formulasi tepung terigu 70%, tepung ubi sukun 22%, dan tepung rumput laut hijau 8%) dengan skor penilaian terhadap karakteristik organoleptik warna 3,81 ( suka), aroma 2,98 (agak suka), rasa 2,92 (agak suka) dan tekstur 3,84 (suka). Nilai analisis kimia dari produk mie basah terbaik meliputi : kadar air 57,68%, kadar abu 1,23%, kadar serat kasar 0,09%. Aktivitas antioksidan tertinggi pada perlakuan M4 (terigu 70%: tepung sukun 22% : dan tepung rumput laut 8%) sebesar 62,50%. Berdasarkan hasil penelitian, produk Mie basah formulasi tepung sukun dan tepung rumput laut hijau dapat diterima (disukai) oleh panelis dan memiliki kadar abu dan kadar air yang telah memenuhi standar SNI.Kata kunci: mie basah, tepung sukun, tepung rumput laut hijau.

Pengaruh Penyimpanan Beku terhadap Karakteristik Kimia dan Fisik Caulerpa racemosa, Drip, dan Filtratnya

Caulerpa racemosa merupakan rumput laut hijau dengan kandungan air yang tinggi sehingga mudah mengalami kerusakan. Penyimpanan dalam suhu beku merupakan salah satu cara untuk memperpanjang masa simpan suatu produk. Namun, pembekuan produk juga dapat menyebabkan terjadinya berbagai perubahan yang tidak dikehendaki. Penelitian ini bertujuan untuk menganalisis pengaruh penyimpanan pada suhu beku terhadap karakteristik kimia dan fisik C. racemosa, drip, dan filtrat yang dihasilkan. Sampel berupa C. rasemosa disimpan dalam ruangan penyimpan beku (cold storage) dan diamati setiap minggunya hingga minggu ke-4. Parameter uji yang diamati meliputi rendemen, komposisi proksimat, kadar garam, uji warna (L*, a*, b*), dan viskositas, masing-masing pada C. racemosa yang ditiriskan, drip, dan filtrat C. racemosa. Hasil penelitian menunjukkan bahwa penyimpanan beku C. racemosa dapat mengurangi berat pada sampel akhir karena sebagian besar drip keluar setelah pelelehan/thawing, yaitu sekitar 77,88-84,81%. Karakteristik fisik maupun kimia C. racemosa yang disimpan selama 1 hingga 4 minggu tidak berbeda nyata antar waktu penyimpanan, namun berbeda nyata pada C. racemosa tanpa disimpan beku, yaitu pada kadar air, abu, dan garam.ABSTRACTCaulerpa racemosa is a green seaweed that has a high moisture content, so it is easily damaged. Frozen storage is one way to extend the shelf life of a product. However, freezing the product can cause various undesirable changes to occur. This study was aimed to analyze the effect of storage at freezing temperature on the chemical and physical characteristics of C. racemosa, drip, and the resulting filtrate. C. racemosa samples were stored in cold storage and observed every week until the 4th week. The test parameters observed were yield, proximate composition, salt content, color (L*, a*, b*), and viscosity on drained C. racemosa, drip, and C. racemosa filtrate. The results showed that frozen storage of C. racemosa could cause weight loss in the final sample because most of the drip came out after thawing, which was around 77.88 - 84.81%. Physical and chemical characteristics of C. racemosa stored for 1 to 4 weeks were not significantly different from unfrozen C. racemosa, i.e. water, ash, and salt content.

Molecular characterization of Caulerpa racemosa (Caulerpales, Chlorophyta) from Indonesia based on the Plastid tufA Gene

The green seaweed Caulerpa racemosa is a seaweed of high prospect that is being given emphasis by the Indonesian government. However, C. racemosa in Indonesia may include multiple species level-entity exhibiting morphological overlap and require molecular analysis for species identification. Molecular documentation of species richness of indigenous populations of C. racemosa is essential to underpin cultivar development and conservation of the species to avoid overharvesting. The present study aimed to determine the genetic diversity of C. racemosa and document the haplotype network of the specimens from four different locations (Bintan Island, Jepara, Takalar and Osi Island) using the chloroplast tufA gene. Twenty individuals from four areas were collected and amplified with the chloroplast-encoded gene tufA for species identification against publicly available data. The identification of C. racemosa based on the tufA gene showed that the species found in four locations were C. cylindracea (previously C. racemosa var. cylindracea), C. macra (previously C. racemosa var. macra), C. racemosa, and C. oligophylla (previously C. racemosa var. lamourouxii). This study records the existence of C. cylindracea in Takalar and Jepara, Indonesia for the first time. The most diverse C. racemosa species was in Osi Island, where the exploitation of this seaweed is very low. In contrast, the lowest number of C. racemosa varieties were found in Takalar, where exploitation is very high. There were only minor light variations of Caulerpa species in the tufA gene in four different sites with only four haplotypes found, and each haplotype corresponded to another species.

Massive Ulva Green Tides Caused by Inhibition of Biomass Allocation to Sporulation

The green seaweed Ulva spp. constitute major primary producers in marine coastal ecosystems. Some Ulva populations have declined in response to ocean warming, whereas others cause massive blooms as a floating form of large thalli mostly composed of uniform somatic cells even under high temperature conditions—a phenomenon called “green tide”. Such differences in population responses can be attributed to the fate of cells between alternative courses, somatic cell division (vegetative growth), and sporic cell division (spore production). In the present review, I attempt to link natural population dynamics to the findings of physiological in vitro research. Consequently, it is elucidated that the inhibition of biomass allocation to sporulation is an important key property for Ulva to cause a huge green tide.

Fighting SARS-CoV-2 with green seaweed Ulva sp. extract: extraction protocol predetermines crude ulvan extract anti-SARS-CoV-2 inhibition properties in in vitro Vero-E6 cells assay

Due to the global COVID-19 pandemic, there is a need to screen for novel compounds with antiviral activity against SARS-COV-2. Here we compared chemical composition and the in vitro anti- SARS-COV-2 activity of two different Ulva sp. crude ulvan extracts: one obtained by an HCl-based and another one by ammonium oxalate-based (AOx) extraction protocols. The composition of the crude extracts was analyzed and their antiviral activity was assessed in a cytopathic effect reduction assay using Vero E6 cells. We show that the extraction protocols have a significant impact on the chemical composition, anti- SARS-COV-2 activity, and cytotoxicity of these ulvan extracts. The ulvan extract based on the AOx protocol had a higher average molecular weight, higher charge, and 11.3-fold higher antiviral activity than HCl-based extract. Our results strongly suggest that further bioassay-guided investigation into bioactivity of compounds found in Ulva sp. ulvan extracts could lead to the discovery of novel anti-SARS-CoV-2 antivirals.

Characterization and analysis of the antidiabetic activities of sulphated polysaccharide extract from Caulerpa lentillifera

Caulerpa lentillifera is a type of green seaweed that is cultivated in tropical and subtropical areas. The objectives of this study were to determine the characteristics of the sulfated polysaccharides from C. lentillifera and evaluate its antidiabetic activity. In the initial process of this study, samples were macerated with ethanol (1:10). Then, the maceration residue was extracted with an accumulator at 75 °C for three hours. The crude extract yield was 4.16% based on weight seaweed. Ion chromatography purification with DEAE-Sepharose resin provided a yield of 14.8% of crude extract. The monomer analysis of C. lentillifera from the crude extract and purified extract revealed that galactose monomers were dominant and glucose was a minor component. The total carbohydrate and sulfate contents of purified C. lentillifera were higher than those of crude C. lentillifera. Bioactivity tests revealed that purified polysaccharides had higher antidiabetic activity against α-glucosidase enzyme than crude ones with IC50 values of 134.81± 2.0 µg/mL. Purified sulfated polysaccharides of C. lentillifera could potentially be used as an antidiabetic medication.