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Fulltext Embryonic, larval, and early juvenile development of the tropical sea urchin, Salmacis sphaeroides (Echinodermata: Echinoidea)

Rahman MA, Yusoff FM, Arshad A, Shamsudin MN, Amin SM

ScientificWorldJournal, 2012;2012:938482.
PMID: 23055824 DOI: 10.1100/2012/938482

Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10(-5) dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition.

Matched MeSH terms: Sea Urchins/embryology*; Sea Urchins/growth & development*
Fulltext Effects of delayed metamorphosis on larval survival, metamorphosis, and juvenile performance of four closely related species of tropical sea urchins (genus Echinometra)

Rahman MA, Yusoff FM, Arshad A, Uehara T

ScientificWorldJournal, 2014;2014:918028.
PMID: 24624048 DOI: 10.1155/2014/918028

We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins, Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22-24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis.

Matched MeSH terms: Sea Urchins/classification; Sea Urchins/physiology*
Absence of postzygotic isolating mechanisms: evidence from experimental hybridization between two species of tropical sea urchins

Rahman MA, Uehara T, Arshad A, Yusoff FM, Shamsudin MN

J Zhejiang Univ Sci B, 2012 Oct;13(10):797-810.
PMID: 23024047

Two reef margin species of tropical sea urchins, Echinometra sp. C (Ec) and Echinometra oblonga (Eo), occur sympatrically on Okinawa intertidal reefs in southern Japan. Hybridization between these species was examined through a series of cross-fertilization experiments. At limited sperm concentrations, where conspecific crosses reached near 100% fertilization, both heterospecific crosses showed high fertilization rates (81%-85%). The compatibility of the gametes demonstrated that if gamete recognition molecules are involved in fertilization of these species, they are not strongly species-specific. We found that conspecific crosses reached peak fertilization levels much faster than did heterospecific crosses, indicating the presence of a prezygotic barrier to hybridization in the gametes. Larval survival, metamorphosis, and juvenile and adult survival of hybrid groups were nearly identical to those of their parent species. Hybrids from crosses in both directions developed normally through larval stages to sexually mature adults, indicating that neither gametic incompatibility nor hybrid inviability appeared to maintain reproductive isolation between these species. In adults, Ec×Ec crosses gave the highest live weight, followed by Eo (ova)×Ec (sperm), Ec (ova)×Eo (sperm), and Eo×Eo. Other growth performance measures (viz., test size, Aristotle's lantern length, and gonad index) of hybrid groups and their parental siblings showed the same trends. The phenotypic color patterns of the hybrids were closer to the maternal coloration, whereas spine length, tube-foot and gonad spicule characteristics, pedicellaria valve length, and gamete sizes showed intermediate features. Adult F(1) hybrids were completely fertile and displayed high fertilization success in F(1) backcrosses, eliminating the likelihood that hybrid sterility is a postzygotic mechanism of reproductive isolation. Conversely, intensive surveys failed to find hybrid individuals in the field, suggesting the lack or rarity of natural hybridization. This strongly suggests that reproductive isolation is achieved by prezygotic isolating mechanism(s). Of these mechanisms, habitat segregation, gamete competition, differences in spawning times, gametic incompatibility or other genetic and non-genetic factors appear to be important in maintaining the integrity of these species.

Matched MeSH terms: Sea Urchins/genetics*; Sea Urchins/growth & development; Sea Urchins/physiology*
Fulltext Seeded Growth Route to Noble Calcium Carbonate Nanocrystal

Islam A, Teo SH, Rahman MA, Taufiq-Yap YH

PLoS One, 2015;10(12):e0144805.
PMID: 26700479 DOI: 10.1371/journal.pone.0144805

A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.

Matched MeSH terms: Sea Urchins/chemistry*
Fulltext Coastal macroinvertebrate study in Penang Island, Malaysia

Chee, Su Yin, Sim, Yee Kwang

Trop Life Sci Res, 2016;27(11):39-44.
MyJurnal

Land reclamation in Penang began two decades ago and is still rampant with
large reclamation projects planned to be executed in the near future. The present study
provides the first information on effects of land reclamation in Penang towards the coastal
macroinvertebrates. This study assessed the abundance, diversity, and evenness of
coastal invertebrates assumed to be the foremost affected when land is reclaimed. Three
kinds of areas were focused on: reclaimed, unclaimed (adjacent to reclaimed), and
undisturbed. A total of 53 species of macroinvertebrates from 10 classes (Gastropoda,
Bivalvia, Polychaeta, Malacostraca, Maxillopoda, Echinoidea, Polyplacophora,
Branchiopoda, Scaphopoda, and Holothuroidea) were sampled. Reclaimed areas were
moderately rich in species averaging 11 species compared to 7 species in adjacent and
14 in undisturbed areas. Species richness was the highest in Teluk Aling (an undisturbed
area) with 22 species, and was the lowest in Gurney Drive (an adjacent area) with 2
species. The average species diversity and evenness on reclaimed land was the lowest
with values of 1.9974 and 0.5787, respectively. The diversity was higher by 5.07% in
adjacent areas and by 22.92% in undisturbed areas compared to reclaimed areas.
Species evenness was 29.75% higher in unreclaimed areas and 17.87% higher in
undisturbed areas compared to reclaimed areas. Land reclamation reduces species
diversity and evenness, and to a lesser extent, species richness.

Matched MeSH terms: Sea Urchins
Fulltext Phylogeography, colouration, and cryptic speciation across the Indo-Pacific in the sea urchin genus Echinothrix

Coppard SE, Jessop H, Lessios HA

Sci Rep, 2021 Aug 16;11(1):16568.
PMID: 34400682 DOI: 10.1038/s41598-021-95872-0

The sea urchins Echinothrix calamaris and Echinothrix diadema have sympatric distributions throughout the Indo-Pacific. Diverse colour variation is reported in both species. To reconstruct the phylogeny of the genus and assess gene flow across the Indo-Pacific we sequenced mitochondrial 16S rDNA, ATPase-6, and ATPase-8, and nuclear 28S rDNA and the Calpain-7 intron. Our analyses revealed that E. diadema formed a single trans-Indo-Pacific clade, but E. calamaris contained three discrete clades. One clade was endemic to the Red Sea and the Gulf of Oman. A second clade occurred from Malaysia in the West to Moorea in the East. A third clade of E. calamaris was distributed across the entire Indo-Pacific biogeographic region. A fossil calibrated phylogeny revealed that the ancestor of E. diadema diverged from the ancestor of E. calamaris ~ 16.8 million years ago (Ma), and that the ancestor of the trans-Indo-Pacific clade and Red Sea and Gulf of Oman clade split from the western and central Pacific clade ~ 9.8 Ma. Time since divergence and genetic distances suggested species level differentiation among clades of E. calamaris. Colour variation was extensive in E. calamaris, but not clade or locality specific. There was little colour polymorphism in E. diadema.

Matched MeSH terms: Sea Urchins/anatomy & histology; Sea Urchins/classification*; Sea Urchins/genetics
Fulltext Induction of Apoptosis by Acanthaster planci sp., and Diadema setosum sp., Fractions in Human Cervical Cancer Cell Line, HeLa

Chaudhry GE, Islamiah M, Zafar MN, Bakar K, Aziz N, Saidin J, et al.

Asian Pac J Cancer Prev, 2021 May 01;22(5):1365-1373.
PMID: 34048163 DOI: 10.31557/APJCP.2021.22.5.1365

Cancer is an uncontrolled multiplication of cells. The desire efficacy and severe toxicity of current anticancer drugs urge exploring and investigating a better alternative to existing chemotherapeutics. Natural products of marine origin are excellent sources of potential new drugs of enhanced biological activities.
OBJECTIVES: Thus, the cytotoxic effects along with investigating the mode of cell death exerted by fractions, AP-9, AP-THR, DS-8 and DS-9 fraction of Acanthaster planci, Diadema setosum sp., on the human cervical cancer cell line, HeLa.
METHODS: The cytotoxicity of fractions has determined by using an MTS assay. The early and late apoptosis was studied by using the High content Screening (HCS) instrument.
RESULTS: The four fractions produced effective cytotoxicity effects with IC50 values at 72hr of less than 20 μg/ml in the order of AP-9 > DS-9 > APTHR-9 > DS-8. The fraction s exhibited cytotoxicity via mediating apoptotic mode of cell death. The early apoptosis by exposure of phosphatidylserine to the outer leaflet of the plasma membrane and late apoptosis due to the presence of green stain (DNA fragmentation) in treated cells.
CONCLUSION: The potent bioactive compounds might be responsible for inducing apoptosis in cancer cells and, thus, the potential to be a successful candidate for exploring upcoming chemotherapeutic drugs.

Matched MeSH terms: Sea Urchins/chemistry*
Fulltext Structural, Optical and Antibacterial Efficacy of Pure and Zinc-Doped Copper Oxide against Pathogenic Bacteria

Khalid A, Ahmad P, Alharthi AI, Muhammad S, Khandaker MU, Rehman M, et al.

Nanomaterials (Basel), 2021 Feb 10;11(2).
PMID: 33578945 DOI: 10.3390/nano11020451

Copper oxide and Zinc (Zn)-doped Copper oxide nanostructures (CuO-NSs) are successfully synthesized by using a hydrothermal technique. The as-obtained pure and Zn-doped CuO-NSs were tested to study the effect of doping in CuO on structural, optical, and antibacterial properties. The band gap of the nanostructures is calculated by using the Tauc plot. Our results have shown that the band gap of CuO reduces with the addition of Zinc. Optimization of processing conditions and concentration of precursors leads to the formation of pine needles and sea urchin-like nanostructures. The antibacterial properties of obtained Zn-doped CuO-NSs are observed against Gram-negative (Pseudomonasaeruginosa,Klebsiellapneumonia,Escherichiacoli) and Gram-positive (Staphylococcusaureus) bacteria via the agar well diffusion method. Zn doped s are found to have more effective bacterial resistance than pure CuO. The improved antibacterial activity is attributed to the reactive oxygen species (ROS) generation.

Matched MeSH terms: Sea Urchins
Effect of copper and cadmium on three Malaysian tropical estuarine invertebrate larvae

Ramachandran S, Patel TR, Colbo MH

Ecotoxicol Environ Saf, 1997 Mar;36(2):183-8.
PMID: 9126437

Three species of tropical estuarine invertebrates were exposed to copper sulfate and cadmium chloride to investigate their potential as test specimens for sediment toxicity assays in the South-east Asian regions. The larvae of the reef sea urchin (Diadema setosum), the oyster (Crassostrea iradalei), and the mud crab (Scylla seratta Forskall) were used in the 48-hr assays with copper and cadmium as reference toxicants. In addition the sea urchin were tested for end point measurements at different stages of the larval development and a 60-min sperm bioassay. The study revealed that the sea urchin first cleavage, which is an assay end point and which takes place about 1 hr after fertilization, was the most sensitive stage for both toxicants, with copper being more toxic than cadmium. Sensitivity comparisons between the three invertebrate larvae revealed the mud crab zoea larvae to be most sensitive for cadmium with an LC50 value of 0.078 microgram/ml, while the sea urchin was more sensitive for copper, with EC50 values of 0.01 microgram/ml at the first cleavage stage and 0.04 microgram/ml at the pluteus larva stage. All the invertebrates tested gave responses that made them suitable test organisms for metal bioassays in the tropical estuarine environment.

Matched MeSH terms: Sea Urchins/drug effects
Antibacterial activity of ovary extract from sea urchin Diadema setosum

Marimuthu K, Gunaselvam P, Aminur Rahman M, Xavier R, Arockiaraj J, Subramanian S, et al.

Eur Rev Med Pharmacol Sci, 2015 May;19(10):1895-9.
PMID: 26044237

Sea urchin gonad is considered as a highly prized delicacy in several countries. It is also rich in valuable bioactive compounds including polyunsaturated fatty acids (PUFAs) and β-carotene. This study was undertaken to examine the antimicrobial properties of the ovary extract from sea urchin Diadema setosum against selected Gram-negative and Gram-positive bacteria.

Matched MeSH terms: Sea Urchins