Showing papers on "Holothuria published in 2006"

The reproductive biology of a new species of sea cucumber, Holothuria (Mertensiothuria) arenacava in a Kenyan marine protected area : the possible role of light and temperature on gametogenesis and spawning

Abstract: The sea cucumber Holothuria arenacava was discovered in the Mombasa marine reserve in 1997 and described by Samyn et al. (2001). The reproductive biology of this holothurian was investigated in order to (1) characterize the reproductive pattern, (2) examine the relationship among environmental parameters including temperature, light and lunar period, and (3) examine the relationship between the reproductive pattern and feeding of this new species. The gonad index method and microscopic examination of gonads was used to analyze samples collected for a period of 13 months. H. arenacava displayed an annual reproductive cycle with gametogenesis commencing in July during the south-east monsoons, when temperature and light intensity are lowest along the Kenyan coast. Gonad growth peaked in February–March at the end of the north-east monsoons when temperatures and light reach their annual maxima along the Kenyan coast. The higher correlation between light intensity and gonad growth (r=93) than temperature (r=0.71), coupled with the fact that temperatures continued to drop for a month after gametogenesis had already commenced, suggests that light intensity and not temperature is the cue for the onset of gametogenesis in this species. Spawning was synchronized between females and males and occurred during a short period between March and May (inter-monsoonal period) when both temperature and light intensity decrease along the Kenyan coast. Male and female gonad indices showed significant variation with lunar day and no lunar periodicity was observed in this sea cucumber. The sex ratio of the population of H. arenacava was skewed towards significantly more females than males, and females were significantly larger and had larger gonads and gonad indices than males. These life history strategies including spawning during a short discrete period, more and larger females that have larger gonads (i.e., typically more fecund), and spawning just prior to the peak in phytoplankton concentrations, a time that is probably more favorable for larval development, may serve to increase the reproductive success of this sea cucumber.

Nobilisides A - C, three new triterpene glycosides from the sea cucumber Holothuria nobilis.

Abstract: Three new triterpene glycosides, named nobilisides A ( 1), B ( 2) and C ( 3), were isolated from the sea cucumber Holothuria nobilis Selenka. Their structures were deduced by extensive spectral analysis and chemical evidence. Compounds 1 and 3 are non-sulfated monoglycosides while 2 is a sulfated diglycoside. The presence of two conjugated double bonds [22 E,24-diene and 7,9(11)-diene] in the aglycone of 1 is a rare structural feature among sea cucumber glycosides, while 2 and 3 possess the same 22,25-epoxy moiety as their side chains. All three glycosides exhibited significant cytotoxicity against human tumor cell lines.

Structure and cytotoxicity of a new lanostane-type triterpene glycoside from the sea cucumber Holothuria hilla

Abstract: A new triterpene glycoside, hillaside C (1), was isolated from the sea cucumber Holothuria hilla Lesson, which is found in the South China Sea, and its structure has been elucidated by spectral analysis (ESI-MS and NMR) and chemical transformations. Four known compounds, holothuria A, thymine, uracil, and cholesterol, were also obtained. Compound 1 exhibited significant cytotoxicity against eight human tumor cell lines (A-549, MCF-7, IA9, CAKI-1, PC-3, KB, KB-VIN, and HCT-8) with IC50 values in the range of 0.15-3.20 microg/ml.

Population dynamics of holothuria (holothuria) tubulosa and holothuria (lessonothuria) polii of an algerian posidonia oceanica meadow

Abstract: Deposit-feeder holothurians represent a major component of Posidonia oceanica (L.) Delile ecosystems. They actively contribute to the turnover of organic matter by ingesting materials in the detritus layer. The evolution of the biomass/density ratio was investigated for two aspidochirotid species Holothuria (H.) tubulosa (Gmelin, 1978) and Holothuria (L.) polii (Rowe, 1969). Quantitative samples were seasonally collected from March 2001 to February 2002, at 3 m depth in two Algerian contiguous shallow stations. The data collected in each season were statistically compared between stations, species and seasons. A significant difference between species was demonstrated in both stations. However, for both species, the biomass/density ratios exhibited a maximum in summer and a minimum in fall. The minimum value of the biomass/density ratio may be interpreted as an indication of recruitment. The mean abundance of Holothuria (L.) polii was significantly lower in the polluted station than in the unpolluted station. The data collected confirm the importance of Holothuria (L.) polii as an indicator of the pollution. Key-words: echinoderms, population dynamics, seagrass, pollution, Algerian basin.

Two new triterpene glycosides from sea cucumber Holothuria nobilis

Abstract: Objective Triterpene glycosides were expected to be isolated from the sea cucumber Holothuria nobilis.Methods The crude saponins of sea cucumber were desulfated with pyridine-dioxane(1∶1),the desulfated products were separated by multi-chromatography to afford two compounds.Results On the basis of chemical methods and spectral evidences,especially 2D NMR and ESI-MS technologies,these two compounds were identified as 3-O-(3-O-methyl-β-D-glucopyranosyl(1→3)-β-D-quinovopyranosyl(1→4)-β-D-quinovopyranosyl(1→2)-β-D-xylopyranosyl)-holosta-9-ene-3β,12α,17α,25β-tetraol(Ⅰ),named as nobiliside 1a;3-O-(3-O-methyl-β-D-glucopyranosyl(1→3)-β-D-xylopyranosyl(1→4)-β-D-quinovopyranosyl(1→2)-4′-O-sulfate-β-D-xylopyranosyl)-holosta-22,25-epoxy-9-ene-3β,12α,17α,25β-triol(Ⅱ),named as nobiliside 2a.Conclusion Two compounds are new triterpene glycosides.

A New Record of Sea Cucumber (Holothuroidea: Aspirochirotida) from Jejudo Island, Korea

Abstract: Holothuria pericax Selenka, 1867 belonging to the family Holothuriidae in the order Aspirochirotida of the subclass Aspidochirotacea is new to Korean fauna. This species was redescribed with figures based on the specimen collected at 16 m deep in north-west Munseom, Seogwipo. A key to the genus was presented. Fifteen species of holothuroids have so far been reported in Jejudo Island of Korea.

Predator Defense Mechanisms in Shallow Water Sea Cucumbers (Holothuroidea)

Abstract: The various predator defense mechanisms possessed by shallow water sea cucumbers were surveyed in twelve different species and morphs. While many defense mechanisms such as the presence of Cuverian tubules, toxic secretions, and unpalatability have been identified in holothurians, I hypothesized that the possession of these traits as well as the degree to which they are utilized varies from species to species. The observed defense mechanisms were compared against a previously-derived phylogeny of the sea cucumbers of Moorea. Furthermore, I hypothesized that while the presence of such structures is most likely a result of the species’ placement on a phylogenetic tree, the degree to which they utilize such structures and their physical behavior are influenced by their individual ecologies. The presence of a red liquid secretion was restricted to individuals of the genus Holothuria (Linnaeus 1767) however not all members of the genus exhibited this trait. With the exception of H. leucospilota, which possessed both Cuverian tubules and a red secretion, Cuverian tubules were observed in members of the genus Bohadschia (Ostergren 1896). In accordance with the hypothesis, both the phylogenetics and individual ecology appear to influence predator defense mechanisms. However, even closely related species of similar ecology may differ considerably.

An investigation on pathogenic micro - organisms of paracentrotus lividus and holothuria polii (echinodermata) mediterranean sea egypt.

Abstract: icrobiological studies of two echinoderms, the Sea Urchin, Paracentrotus lividus and the Sea cucumber, Holothuria polii from Abu-Qir region of Alexandria Mediterranean coast, were conducted during July 2005. The isolates revealed Gram-positive bacteria from the gonads of the sea urchin and two types of pathogenic fungi from its digestive tract. On the other hand, no isolates were detected from the sea cucumber. The effect of the isolated microorganisms was discussed.

Phylogenetic analysis of sea cucumbers (Echinodermata: Holothuroidea) in Malaysia as inferred from Cytochrome C Oxidase I MtDNA

Abstract: Diverse species of sea cucumber (Echinodermata: Holothuroidea) were documented in Malaysia. Their abundance benefits the Malaysians in traditional and modern medicinal industry as well as in food processing industry. Previously, the identification of sea cucumber species in Malaysia was done mainly based on morphological characters. Among the characters used were the shapes of ossicles, body shapes and colour, shapes of tentacles, the existence and shapes of papillae. However, the morphological approaches were unsuccessfully unravelled the problematic taxonomic status of sea cucumbers as there are unidentified and unknown species present throughout Malaysia to date. As an alternative approach to verify the species status inferred from morphology, molecular ecology analyses were incorporated in this study to examine the phylogenetic relationship between and among selected species of sea cucumbers from Malaysia by using cytochrome c oxidase I (COI) mitochondrial DNA (mtDNA) gene. Three genera were selected namely Holothuria and Stichopus from order Aspidochirotida, and genus Molpadia from order Molpadiida. Polymerase Chain Reaction (PCR) gave the desired products of amplified COI mtDNA region with length of approximately 510 bp. After the multiple sequence alignment, partial sequences of COI mtDNA gene ranging from 488 bp to 489 bp were utilized for further analyses. 22 ingroups of sea cucumbers and one outgroup represented by Diadema setosum were included in the reconstruction of neighbour-joining (NJ) tree and maximum parsimony (MP) tree. Base frequency and genetic distance based on Kimura-2 parameter model were also calculated prior to the reconstruction of phylogenetic tree. Basically, both types of phylogenetic trees suggest the paraphyly of Holothuria and Stichopus due to the clustering of four Stichopus horrens individuals together with Holothuria species. Apart from that, Molpadia species seems genetically close to the main group of genus Holothuria and Stichopus horrens. The phylogenetic results were also supported by the data from genetic distance. Overall, the above findings strongly suggest that the grouping and classification at species and higher level as inferred from COI mtDNA gene are unresolved, requiring further molecular ecology studies to be done in the near future.