Anadara Granosa Research Articles

Performance of a modified and intermittently operated slow sand filter with two different mediums in removing turbidity, ammonia, and phosphate with varying acclimatization periods

The present study investigated the utilization of blood clam shells as a potential substitute for conventional media, as well as the influence of the acclimation time on the efficacy of an intermittent slow sand filter (ISSF) in the treatment of real domestic wastewater. ISSF was operated with 16 h on and 8 h off, focusing on the parameters of turbidity, ammonia, and phosphate. Two media combinations (only blood clam shells [CC] and sand + blood clam shells [SC]) were operated under two different acclimatization periods (14 and 28 d). Results showed that SC medium exhibited significantly higher removal of turbidity (p < 0.05) as compared to CC medium (45.99 ± 26.84 % vs. 3.79 ± 9.35 %), while CC exhibited slightly higher (p > 0.05) removal of ammonia (23.12 ± 20.2 % vs. 16.77 ± 16.8 %) and phosphate (18.03 ± 11.96 % vs 13.48 ± 12 %). Comparing the acclimatization periods, the 28 d of acclimatization period showed higher overall performances than the 14 d. Further optimizations need to be conducted to obtain an effluent value below the national permissible limit, since the ammonia and phosphate parameters are still slightly higher. SEM analysis confirmed the formation of biofilm on both mediums after 28 d of acclimatization; with further analysis of schmutzdecke formation need to be carried out to enrich the results.

The transcriptomic and biochemical responses of blood clams (Tegillarca granosa) to prolonged intermittent hypoxia

The blood clam (Tegillarca granosa), a marine bivalve of ecological and economic significance, often encounters intermittent hypoxia in mudflats and aquatic environments. To study the response of blood clam foot to prolonged intermittent hypoxia, the clams were exposed to intermittent hypoxia conditions (0.5 mg/L dissolved oxygen, with a 12-h interval) for 31 days. Initially, transcriptomic analysis was performed, uncovering a total of 698 differentially expressed genes (DEGs), with 236 upregulated and 462 downregulated. These genes show enrichments in signaling pathways related to glucose metabolism, sugar synthesis and responses to oxidative stress. Furthermore, the activity of the enzyme glutathione peroxidase (GPx) and the levels of gpx1 mRNA showed gradual increases, reaching their peak on the 13th day of intermittent hypoxia exposure. This observation suggests an indirect protective role of GPx against oxidative stress. The results of this study make a significantly contribute to our broader comprehensive of the physiological, biochemical responses, and molecular reactions governing the organization of foot muscle tissue in marine bivalves exposed to prolonged intermittent hypoxic conditions.

Microplastics aggravate the bioaccumulation and corresponding food safety risk of antibiotics in edible bivalves by constraining detoxification-related processes

Characterized by a sessile filter-feeding lifestyle, commercial marine bivalves inhabiting pollution-prone coastal areas may accumulate significant amounts of pollutants, such as antibiotic residues, in their soft tissues and thus pose a potential threat to the health of seafood consumers. Microplastics are another type of emerging pollutant that are prevalent in coastal areas and have been reported to interact with common antibiotics such as enrofloxacin (ENR) and trimethoprim (TMP). Nevertheless, little is known about the impacts of MPs on the accumulation and corresponding food safety risk of antibiotics in edible bivalve species. Taking the frequently detected ENR, TMP, and polystyrene (PS)-MPs as representatives, the accumulation of above-mentioned antibiotics in three commercial bivalves with or without the copresence of MPs was assessed. In addition, the corresponding food safety risks of consuming antibiotic-contaminated bivalves were evaluated. Moreover, the impacts of these pollutants on detoxification-related processes were analyzed using the thick-shell mussel as a representative. Our results demonstrated that blood clams (Tegillarca granosa), thick-shell mussels (Mytilus coruscus), and Asiatic hard clams (Meretrix meretrix) accumulated significantly higher amounts of antibiotics in their bodies under antibiotic-MP coexposure scenarios. Although based on the target hazard quotients (THQs) and the margins of exposure (MoEs) obtained, the direct toxic risks of consuming ENR- or TMP-contaminated bivalves were negligible, the TMP residue accumulated in TMP-MP-coexposed mussels did surpass the maximum residue limits (MRLs) of the corresponding National Food Safety Standard of China, suggesting that other forms of potential risks should not be ignored. In addition, it was shown that the detoxification, energy provision, and antioxidant capacities of the thick-shell mussels were significantly hampered by exposure to the pollutants. In general, our data indicate that MPs may aggravate the accumulation and corresponding food safety risk of antibiotics in edible bivalves by disrupting detoxification-related processes, which deserves closer attention.

First report of Perkinsus olseni infections in blood cockles Tegillarca granosa on the south coast of Korea

The protozoan parasite Perkinsus olseni has become a focus of attention since it has been responsible for mass mortalities and economic losses in a wide range of bivalve hosts globally. The P. olseni host range along the south coast of Korea may extend beyond what was previously understood, and blood cockles in the Family Arcidae are also suggested to be potential hosts of P. olseni. In the present study, we applied histology and molecular techniques to identify Perkinsus sp. infections in the blood cockles Tegillarca granosa, which have been commercially exploited on the south coast of Korea for several decades. Histology and molecular techniques, including genus-specific immunofluorescence assay, species-specific fluorescence in situ hybridization, and phylogeny based on the ribosomal DNA internal transcribed spacer region revealed that T. granosa is infected by P. olseni, although the prevalence was low (0.5%). Histology revealed massive hemocyte infiltrations in the mantle, gill, and digestive gland connective tissues, indicating that the infection exerts negative impacts on the host cockles.

Seasonal variation in the abundance of microplastics in three commercial bivalves from Bandon Bay, Gulf of Thailand

This study investigated the abundance of microplastics in three commercial bivalves found at Bandon Bay. Spatial-temporal differences in the concentration of microplastics were evaluated during the dry and wet seasons. The results showed that the highest abundance of microplastics in oysters, blood cockles, and green mussels was observed in fishery and aquaculture areas during the dry season, with 1.42 particles/g (w/w), 1.01 particles/g (w/w) and 0.87 particles/g (w/w), respectively. Microplastics were more abundant during the dry season compared to the wet season (p < 0.05), with fibre being the predominant shape and black being the major colour of particles. Cellophane was the most common type of polymer in all bivalves. This result is an important reference for understanding the status of microplastics in three commercial bivalves during different seasons and in different human activities, which should aid in understanding the sources of microplastics in Bandon Bay.

Dietary supplementation of ark clams protects gut health and modifies gut microbiota in d-galactose-induced aging rats.

Ark clams, a seafood abundant in various nutrients, are widely consumed worldwide. This study aimed to investigate the protective benefits of two common ark clams in Korea, Scapharca subcrenata (SS) and Tegillarca granosa (TG), on gut health in d-galactose (d-gal)-induced aging rats. Thirty-two Wistar rats (11 weeks old) were randomly allocated into four groups: a CON group (normal diet + saline intraperitoneal (i.p.) injection), a CD group (normal diet + d-gal i.p. injection), an SS group (normal diet with 5% SS supplementation + d-gal i.p. injection), and a TG group (normal diet with 5% TG supplementation + d-gal i.p. injection). After 12 weeks of treatment, histopathological results showed that gut barrier damage was alleviated in rats of the SS and TG groups, as evidenced by increases in mucus layer thickness and goblet cell numbers. Meanwhile, the two groups supplemented with ark clams showed an evident reduction in oxidative stress biomarkers (malondialdehyde and protein carbonyl content levels in the colon) and an increase in the immune-related factor (immunoglobulin A level in the plasma) in rats. The 16S ribosomal RNA analysis revealed that SS and TG ark clams significantly increased the proliferations of Bacteroidetes at the phylum level and Parabacteroides at the genus level. Additionally, the levels of the three main short-chain fatty acids in the cecal contents were also significantly increased in the SS and TG groups. Our results indicated a potent preventive effect of SS and TG ark clams on d-gal-induced gut injury, suggesting that ark clams may be a promising dietary component for intervening in aging. © 2023 Society of Chemical Industry.

A genome-wide association study to identify the genes associated with growth-related traits in Tegillarca granosa

The blood clam Tegillarca granosa is a commercially important bivalve species that is extensively cultivated worldwide. However, understanding of the molecular mechanisms underlying the growth of this species remains limited. In this study, we conducted genome-wide association studies on the growth traits of T. granosa, including shell and body weight characteristics, using a population of 300 T. granosa individuals. Correlation analysis revealed strong positive associations among the growth traits, with the exception of dressing percentage, suggesting that selective breeding for any of these traits can contribute to overall growth enhancement in T. granosa. A total of 39 single nucleotide polymorphism (SNP) markers associated with the seven growth traits were identified. Further investigation led to the identification of 27 candidate genes located within a 100 kb region upstream or downstream of these SNPs, which are potentially involved in T. granosa growth. Enrichment analysis of the candidate genes highlighted the biological process of transmembrane transport and the pathways related to immune system function, protein family metabolism, and JAK-STAT signaling as potential contributors to T. granosa growth. Furthermore, we discovered a haploblock associated with shell width, and validated the differential expression of four genes (Vha26, Ptprt, Stat5b, and Kmt2c) between fast and slow growing groups, which may play important roles in the growth of T. granosa. Overall, our study presents valuable genetic resources and serves as a reference for future marker-assisted selection strategies for enhancing the growth performance of T. granosa.

A C-type lectin with a single carbohydrate-recognition domain (CRD) containing unique QPN/WDD motifs from Tegillarca granosa is involved in the innate immune defense

C-type lectins (CTLs), a superfamily of Ca2+-dependent carbohydrate-recognition proteins, serve as pattern recognition receptors (PRRs) in the immune response of many species. However, little is currently known about the CTLs of the commercially and ecologically important bivalve species, blood clam (Tegillarca granosa). In this study, a CTL (designated as TgCTL-1) with a single carbohydrate-recognition domain (CRD) containing unique QPN/WDD motifs was identified in the blood clam through transcriptome and whole-genome searching. Multiple alignment and phylogenetic analysis strongly suggested that TgCTL-1 was a new member of the CTL superfamily. Expression analysis demonstrated that TgCTL-1 was highly expressed in the hemocytes and visceral mass of the clam under normal condition. In addition, the expression of TgCTL-1 was shown to be significantly up-regulated upon pathogen challenge. Moreover, the recombinant TgCTL-1 (rTgCTL-1) displayed agglutinating and binding activities against both the gram-positive and gram-negative bacteria tested in a Ca2+-dependent manner. Furthermore, it was found that the in vitro phagocytic activity of hemocytes was significantly enhanced by rTgCTL-1. In general, our results showed that TgCTL-1 was an inducible acute-phase secretory protein, playing crucial roles in recognizing, agglutinating, and binding to pathogenic bacteria as well as modulating phagocytic activity of hemocytes in the innate immune defense of blood clam.

Marine mollusk biodiversity in Northeastern islands of Vietnam, impact factors and proposing conservation solutions

A biodiversity and water-quality monitoring campaign was conducted in the Northeastern archipelago of Vietnam, including Quang Ninh province and Hai Phong, in 2017–2018. Mollusks are selected as the critical proxy indicator, and water-quality parameters are tested against National acceptability standards. The study revealed that, despite declining trends over the past two decades, mollusks are still highly diverse, with 647 species belonging to 227 genera, 95 families, and five classes (76% of all the species identified in the Tonkin Gulf). Of these, 253 species of 39 families (39% of the whole stock) are of high economic value, supporting an active trade in the region and thousands of livelihoods. Several species (abalone, blood cockle, green mussel, pearl oysters, Pacific oysters, double-headed clams, Asian hard clams, white clams, and squids) are intensively farmed. However, aquaculture still needs to be derdeveloped as capture from the wild is preferred. Water quality is unexpectedly high despite impacting factors such as urban development, industry, mass tourism, and demographic increase, mainly within the limits of acceptability set by the Government. Salinity, pH, and temperature are compatible with marine life, and a limited impact is represented by dissolved nitrates and suspended hydrocarbons in suspension. Despite favorable conditions of the aquatic environment, biodiversity decline has been a steady trend over the past decade. The causes are the urban encroachment over the coastal tract, the intertidal spawning grounds, breeding grounds, and nurseries, overexploitation, IUU fishing, lack of management, and failed establishment of conservation areas and MPAs. Spawning and breeding grounds identification and demarcation, their participated co-management, investments in environmental protection, technologies, and capacity building, and promotion of aquafarming of marketable species are among the measures recommended to be implemented with priority, to relieve the pressure over the wild stock and promote regeneration. The role of science in monitoring and detecting environmental changes guiding the adoption of proactive measures to prevent depletion and stock collapse, is the pathway to the sustainability of resource use and human well-being.

PENGARUH PERSENTASE CAMPURAN SERAT DAUN NANAS DAN CANGKANG KERANG DARAH TERHADAP INOVASI PAPAN PARTISI PENYEKAT RUANGAN

Indonesia's increasing population is a crucial problem. According to the Central Bureau of Statistics (2021), Indonesia's population growth in 2020 will increase by 32.56 million people. In line with the need for housing in Indonesia, as a result the available land is decreasing, so many housing developments use partitions. However, partitions on the market still have many drawbacks. Utilization of pineapple leaf fiber as a substitute for fiber and blood clam shell waste as a substitute for cement is certainly a solution to this problem. Where pineapple leaf fiber has a carbon content such as 23.39% cellulose, 42.72% hemicellulose, and 4.03% lignin. Blood clam shells contain Sio2 of 8.252% and CaCO3 ranging from 66-98%. The purpose of this study was to determine the effect of the use of these two materials on the partition characteristics produced through physical tests and mechanical test. Samples were made in laboratory studies with variations of pineapple leaf fiber subs 0%;30%;70%;100% with the number of samples for each mold size being 3 samples. Through the results of tests that have been carried out, the best variation of pineapple leaf fiber substitution is the 70% variation. This test was also carried out by comparing several commercial partitions (gypsum, kalsiboard and GRC).

Rounded toothed pearl-shell mounds at Elizabeth River near Darwin, Northern Territory

As the most visible remains of past coastal economies across the coast of northern Australia, mounds of shell dominated by roughback cockles (Tegillarca granosa) have featured often in explanations for Late Holocene Indigenous subsistence strategies. Recently more detailed local and regional studies continue to build a picture of some variations to this dominance, which demonstrate the breadth of marine species exploited, the extensive ecological knowledge of past economies, and the persistence of cultural traditions in human societies. This paper describes one such study, of mounds composed predominantly of another species of bivalve, the rounded toothed pearl-shell (Isognomon ephippium), found on Larrakia Country near Darwin, Northern Territory.

Bivalvia assemblage in the estuary and mangrove of Belawan Waters, North Sumatra

Marine bivalves are aquatic organisms commonly found in the intertidal zone that frequently exposed to pollution and anthropogenic activities. The study aimed to determine the bivalvian diversity and its distribution pattern in Belawan Waters as one of the most polluted estuary area in North Sumatra. The study used purposive sampling in two sites, Station-1 was located at the mangrove forest in Kwala Besar and Station-2 was located at Bagan Belawan or human-exposed waters. The study documented seven species of bivalves with Solen sp. as the most abundant species (3.33 ind/m2) at Site-1 and Hiatula chinensis (7.44 ind/m2) at Site-2. The Shannon’s diversity index (H’) of bivalves in Belawan Waters was categorized as low level of divesity in both sites. The distribution pattern of Atrina pectinata, Lingula anatina, and Placuna sp. was randomly distributed while Anadara granosa, Solen sp., Hiatula chinensis and Tellina exerythra was clumped in the area based on the Morisita’s index. Bivalve diversity index was positively correlated with the physicochemical characteristics of Belawan waters, including pH, COD, TSS, and PO4, while TDS, BOD5, DO, Substrate Organic Content, salinity, and temperature were negatively correlated to the diversity.

The enlargement of painted spiny lobster (&lt;i&gt;Panulirus versicolor&lt;/i&gt;) uses different feed ingredients

Development of lobster cultivation activities in Muna regency relatively not optimal. Availability of feed is be expected to be an obstacle in the development of lobster cultivation. This Research aims to determine the effect of feed ingredients on growth and survival of spiny lobster (Panulirus versicolor). The Research was conducted in December 2017 to March 2018, located in Bahari Village, Towea District, Muna Regency, Southeast Sulawesi Province using a randomized block design with three levels of feed ingredients treatment namely treatment A = blood clam meat, treatment B = white shrimp and treatment C = trash fish. The results showed that the highest specific growth rate was obtained in treatment A which was 1.69 ± 0.09 %/day, then treatment C (1.13±0.09 %/day), and the in lowest treatment B (1.09±0,06 %/day). The highest absolute growth was obtained in treatment A of 606.67 ± 15,28 g/individual then treatment C was 336.67±15,28 g/individual and the lowest was in treatment B of 300.00±10.00 g/individual. Survival of sea lobster is 100% in all three treatments. Analysis of variance at the 95% confidence level (α0.05) showed that different feed ingredients had a significantly different effect on the daily growth rate, and the absolute growth of sea lobsters (P. versicolor).

Assessment of toxic metal pollution in Yueqing Bay and the extent of metal-induced oxidative stress in Tegillarca granosa raised in this water

Yueqing Bay is an important economic shellfish culture zone in Zhejiang Province, China. However, increased pollution in the water caused by toxic metals has led to the bioaccumulation of toxic metals in cockles such as Tegillarca granosa, and the consequence of toxic metal-associated toxicity in these animals. This study aimed to assess the concentration of toxic metals in the water and sediment in four different sites (Baisha, Qingjiang, Nanyue, and Wengyang) within Yueqing Bay and to evaluate the extent of metal bioaccumulation in T. granosa raised in the aquaculture farms located within the four sites, as well as the changes in biomarkers in T. granosa in response to the metals. The assessment was carried out at two different times of the year, January and July. The water and sediment samples taken from the aquaculture farms in Baisha (S1), Qingjiang (S2) and Nanyue (S3) were found to have a comprehensive toxic metal pollution index (Pc) <1, indicating that these farms were not polluted. However, the water and sediment samples taken from the aquaculture farm in Wengyang (S4) had a Pc between 1 and 2, indicating mild toxic metal pollution. The edible risk assessments (HQ) of T. granosa in all four farms were <1, and therefore, these cockles could be considered safe for human consumption. The toxic metal enrichment in T. granosa exhibited a strong correlation with the toxic metal content in the sediment. In all four farms, CAT and SOD activity levels in the visceral mass of T. granosa were higher than those found in the foot, and a significantly higher level of CAT activity was detected in July compared with January. Similarly, MDA and H2O2 contents in the visceral mass were also higher in July than in January. Tegillarca granosa individuals taken from S4 and S3 farms exhibited significantly higher levels of metallothionein (MT) mRNA and MDA compared with individuals from S1 and S2 farms. Furthermore, the levels of MDA and MT mRNA showed significant positive correlations with Cd, Cr, Hg, and Cu. Elevation of lipid peroxidation in these cockles coincided with increasing levels of endogenous antioxidants. The visceral mass of T. granosa and its MDA level could be used as a tissue indicator and a biochemical marker, respectively, for detecting toxic metal pollution. MT mRNA might also be used as a molecular marker of toxic metal pollution. The integrated biomarker response version 2 (IBRv2) values of the four aquaculture farms in Yueqing Bay showed the order S4 > S3 > S2 > S1, indicating that S4 had the most serious metal-induced stress. Furthermore, the IBRv2 values correlated with the Nemerow composite index (Pc) for all the cockles examined. Thus, as far as the contamination of aquaculture farms in Yueqing Bay by toxic metals is concerned, the aquaculture farm in Wengyang (S4) was mildly contaminated by toxic metals. However, the contamination was relatively low, presenting a low risk for the local population of T. granosa.

Spatial Distribution of Microplastic Contamination in Blood Clams (Anadara granosa) on the Jeneponto Coast, South Sulawesi

Spatial Distribution of Microplastic Contamination in Blood Clams (Anadara granosa) on the Jeneponto Coast, South Sulawesi

Risk Analysis of Microplastic Exposure Through Consumption of Anadara Granosa at Coastal Area

Risk Analysis of Microplastic Exposure Through Consumption of Anadara Granosa at Coastal Area

Genome-Wide Analysis of Family I84 Protease Inhibitor Genes in Three Bivalves Reveals Important Information About the Protein Family's Evolution.

Family I84 serine protease inhibitors are believed to be mollusk specific proteins involved in host defense. The molecular evolution of the family, however, remains to be understood. In this study, the genes of Family I84 protease inhibitors in 3 bivalves, Crassostrea gigas, Crassostrea virginica and Tegillarca granosa, were analyzed at the genomic level. A total of 66 Family I84 genes (22 in C. gigas, 28 in C. virginica and 16 in T. granosa) were identified from the 3 species. They distributed unevenly in the genomes involving 4 chromosomes in C. gigas and 5 chromosomes in C. virginica and T. granosa and some genes were tandemly duplicated. Most genes had 3 exons with 12 genes having 4 exons and 1 gene having 2 exons. All genes but 1 from C. gigas and 1 from T. granosa encoded peptides with a signal sequence at the N-terminus, and the properties of the predicted mature molecules were similar. Four conserved motifs were identified in the 66 amino acid sequences. Collinear analysis revealed higher collinearity between the 2 oyster species in general genes and in Family I84 genes. Phylogenetic analysis of the 66 genes with those previously reported from 3 other bivalves and 1 gastropod showed that Family I84 protease inhibitor genes from the same species tended to be grouped together in terminal branches of the constructed Maximum likelihood tree, but most internal nodes were poorly supported by the bootstrap values. In addition, differences in expression patterns between the genes of a same species were observed in the developmental stages and tissues of C. gigas and T. granosa. Moreover, the co-expression of genes within Family I84 and Family I84 genes with non-Family I84 were also detected in C. gigas and T. granosa. These results suggested that Family I84 protease inhibitor genes evolved by active duplications and structural and functional diversifications after the speciation of related mollusks, and the diversified protease inhibitor family was likely multifunctional.

Differences in the solubility of CaCO3 from blood clam shells and Ca(OH)2 as a candidate pulp capping material

Background: Calcium hydroxide (Ca(OH)2) is the gold standar in pulp capping treatment because the biocompatibility and capability to stimulate hard tissue formation and also antibacterial effect. However, this compound has the disadvantage of being easily soluble in saliva which will increase the risk of leakage in the cavity. Another alternative pulp capping material is calcium carbonate from blood clam shells. Blood clam shells contain 98% CaCO3, CaCO3 has low solubility and is difficult to dissolve in water due to the large ions on Ca2+ and CO32- so that the attractive force between these ions is very strong and finally H2O is not able to break down the CaCO3 compound to be dissolved. Purpose: Explained the differences in the solubility of calcium carbonate from blood clam shells and calcium hydroxide as candidates pulp capping materials. Methods: This research is a laboratory experimental study with a pretest-posttest control group design method. The samples consisted of 12 pieces of Ca(OH)2 and CaCO3 then divided into 2 groups and given treatment. Group 1 CaCO3 immersed in 1 day, group 2 Ca(OH)2 immersed in 1 day, group 3 CaCO3 immersed in 7 days, and group 4 Ca(OH)2 immersed in 7 days. Solubility is calculated according to the solubility formula. Data testing with Anova-Welch. Results: There was a significanly difference in the solubility rate between the CaCO3 dan Ca(OH)2 groups immersed for 1 day and 7 days on the Anova-Welch results (p&lt;0.05). Conclusion: The solubility of CaCO3 in blood clam shells is lower than the solubility in Ca(OH)2.)

Morphometric study of blood cockle (Anadara granosa) in Kendari Bay, Southeast Sulawesi

The cockle immerses in the substrate of the intertidal zone. Their conditions and growth factors are highly dependent on nutrients around the waters of Kendari Bay. Therefore, this study aims to determine the relationship between length, weight, and condition factors. The study was conducted in March 2016 to February 2017 at the intertidal zone of Kendari Bay. The samples were collected with a shovel in a 1x1 m square transect monthly. Furthermore, the length and weight of the shells were measured using a calliper and a digital scale with an accuracy of 0.5 cm and 0.001g, respectively. The cockle was oven-dried for 48 hours. Simple linear regression was used to analyze the relationship between length and weight, while the condition factors were examined using the Mann-Whitney test. The results showed that male and female cockle shells had b values in the negative allometric and isometric categories, which spread from the respective ranges of 2.31-3.06 and 2.21-3.23. The b values for males and females increased in March-September and then decreased in October-February. Meanwhile, the condition factors of male and female mussels based on size and time of observation were not significantly different and ranged from 3.24±1.33-7.07±0.43 and 2.94±0.54-6.63±1.09. The highest condition index was discovered in October, March, and August, respectively, while the lowest occurred in June and September.

Potential of nano hydroxyapatite synthesized from blood clam shells as a remineralizing agent after in-office bleaching

Introduction: The effect of bleaching on tooth structure is the loss of interprismatic substance which causes prism irregularities and changes in enamel morphology such as increased porosity and demineralization. This can be stopped by encouraging remineralization if the pH is neutralized and there are enough calcium and phosphate ions in the oral cavity. One agent that can be used to help the remineralization process is nano hydroxyapatite (nHA) which is a bioactive and biocompatible material for the natural mineral enamel. This study aims to determine change in the percentage of porosity, calcium, phosphate and hydroxyapatite synthesized from blood clam shells (Anadara granosa) and CPP-ACP as a positive control. Material and methods: The research design was a pre-post test control group design. Six maxillary first premolars were cut to the CEJ with a size of 5x5x2 mm then 40% hydrogen peroxide was applied. The first group was applied nHA synthesized from blood clam shells and the second group was applied CPP-ACP. Determination the percentage of porosity, calcium, phosphate and hydroxyapatite was carried out before and after bleaching and after aplication of remineralizing agent. Results: The study showed an decrease the porosity, calcium, phospate and increase hydroxyapatite precentage after sampel was applied to the remineralizating material nHA synthesized from blood clam shells and CPP-ACP. Conlusion: nHA results of blood clam shell synthesis has the potential to be used as an enamel remineralization agent after in-office bleaching.&#x0D; Key words: Blood clam shell, Casein Phosphopeptide-Amorphous Calcium Phosphate, In-office bleaching, Nano Hydroxyapatite