Reproductive biology of the commercial sea cucumber <Emphasis Type="Italic">Holothuria spinifera</Emphasis> (Echinodermata: Holothuroidea) from Tuticorin,Tamil Nadu,India

The annual reproductive cycle of the commercial sea cucumber Holothuria spinifera was studied in Tuticorin, Tamil Nadu, India, from September 2000 to October 2001, by macroscopic and microscopic examination of gonad tubule, gonad index and histology of gametogenic stages, to determine the spawning pattern. The gonad consists of long tubules with uniform development. It does not confirm the progressive tubule recruitment model described for other holothurians. The maximum percentage of mature animals, gonad and fecundity indices, tubule length and diameter, with the observations on gonad histology, ascertained that H. spinifera had the peak gametogenic activity during September and October 2001 followed by a prolonged spawning period from November 2000–March 2001.     

Effects of temperature, salinity and pH on larval growth, survival and development of the sea cucumber Holothuria spinifera Theel

For large-scale seed production of sea cucumbers through a hatchery system, it is imperative to know the effects of environmental parameters on larval rearing. Auricularia larvae (48 h post-fertilization) were obtained from induced spawning of Holothuria spinifera and used in experiments to ascertain the effects of temperature, salinity and pH on the growth and survivorship of the larvae. The larvae were reared for 12 days at temperatures of 20, 25, 28 and 32 °C; salinities of 15, 20, 25, 30, 35 and 40 ppt; and pH of 6.5, 7.0, 7.5, 7.8, 8.0, 8.5 and 9.0. The highest survivorship and growth rate and fastest development of auricularia indicated that water temperature of 28–32 °C, salinity of 35 ppt and pH of 7.8 were the most suitable conditions for rearing larvae of H. spinifera.     

Cytotoxic and Apoptosis-Inducing Activity of Triterpene Glycosides from Holothuria scabra and Cucumaria frondosa against HepG2 Cells

The cytotoxic effects of thirteen triterpene glycosides from Holothuria scabra Jaeger and Cucumaria frondosa Gunnerus (Holothuroidea) against four human cell lines were detected and their cytotoxicity-structure relationships were established. The apoptosis-inducing activity of a more potent glycoside echinoside A (1) in HepG2 cells was further investigated by determining its effect on the morphology, mitochondrial transmembrane potential (Δψ_m) and mRNA expression levels of the apoptosis-related genes. The results showed that the number of glycosyl residues in sugar chains and the side chain of aglycone could affect their cytotoxicity towards tumor cells and selective cytotoxicity. 1 significantly inhibited cell viability and induced apoptosis in HepG2 cells. 1 also markedly decreased the Δψ_m and Bcl-2/Bax mRNA express ratio, and up-regulated the mRNA expression levels of Caspase-3, Caspase-8 and Caspase-9 in HepG2 cells. Therefore, 1 induced apoptosis in HepG2 cells through both intrinsic and extrinsic pathway. These findings could potentially promote the usage of these glycosides as leading compounds for developing new antitumor drugs.     

白沙参苗种中间培育关键参数研究

为了解决白沙参参苗个体小、抗逆性及抵御敌害生物的能力弱、成活率低、不利于增养殖的缺陷,研究了白沙参室内水泥池中间培育过程中的关键参数,并在最优条件下进行室内水泥池和室外池塘网箱的培苗,试验结束时测量参苗的体长和体重,计算成活率.结果表明,室内水泥池培育的关键技术参数如下:水温25～30℃,盐度25‰～35‰,培育密度2000～3000头/m2,光照强度2 000 lx.在上述最佳条件下,将体长0.3～0.5 cm、体重0.004 g的参苗16万尾,置于室内水泥池培育1个月后,参苗规格平均达到0.8～1 cm,存活率达到50％以上.然后将其转到室外网箱培养,更换网箱规格并及时疏苗,培育40 d时,参苗规格平均达到3 cm左右,存活率达到60％.     

Preliminary assessment of large‐scale co‐culture of sandfish (Holothuria scabra) with the Babylon snail (Babylonia areolata) in earthen ponds and in raceways

Holothuria scabra (sandfish) and Babylonia areolata were trialed in two large‐scale co‐culture experiments. Experiment 1 assessed co‐culture in 4 × 400 m² earthen ponds where Babylonia were cultured in a central pen at a density of 400 individuals/m² with sandfish occupying the remaining pond space at 1.1 individuals/m². Sandfish grew from 18.20 ± 6.67 g to 119.03 ± 17.74 g in 92 days and Babylonia (fed trash fish in both experiments) grew from 0.90 ± 0.38 g to 4.93 ± 1.44 g, but Babylonia growth was not increased in co‐culture compared to monoculture. Water and sediment quality varied between co‐culture and monoculture ponds. Neither showed clear improvement due to sandfish culture. Experiment 2 compared non‐segregated sandfish‐Babylonia co‐culture with Babylonia monoculture in 20 m² concrete raceways. Sandfish were cultured at 2 individuals/m² and Babylonia at 300 individuals/m². Sandfish grew up to 1.91 g.day^?1 with 100% survival. Babylonia weight gain was significantly greater in co‐culture raceways (3.35 ± 0.64 g over 61 days), which was double that of Babylonia in monoculture. Substrate total N was reduced by 20% in co‐culture compared with monoculture (p = .032). This provisional study of commercial scale sandfish‐Babylonia co‐culture demonstrates culture compatibility, providing a basis for further system development.     

Trial grow‐out culture of sea cucumber Holothuria scabra in sea cages and pens

Field trials were conducted to determine the effects of size, grow‐out period and site on the growth and survival of Holothuria scabra. Juveniles were reared in sea cages in two sites for 2 months during two different times of the year. Juveniles from Experiment 1 were subsequently grown in sea pens for 8 months in one site. The significantly lower survival particularly of the small‐sized group (<0.1 g) in Pilar is likely due to reduced water and sediment quality because of proximity to fish‐farming activities. The importance of grow‐out period was evident in the significant differences in weight increments in all size groups and biomass in the small‐sized group (P < 0.10) in Lucero during Experiment 2 when water temperature range and incidence of rainfall were higher. The decrease in the average weight of adults during the second half of the grow‐out period may be due to the interplay of the reduction in salinity, onset of sexual maturity and biomass exceeding carrying capacity in the pens. The estimated biomass threshold in the sea cages and pens in Lucero were 300 g m^?2 and 380 g m^?2 respectively. Implications of the results on the viability of small‐scale pen grow‐out culture are discussed.     

糙海参胚胎和幼体发育的形态观察

为提高糙海参育苗技术,研究描述了糙海参从受精卵发育到稚参的形态变化,在显微镜下测定了受精卵、胚胎和幼体的大小,确定了糙海参胚胎发育的过程。结果表明,通过利用阴干、流水刺激法对成熟亲参进行人工催产,得到大量的受精卵,其受精率为90%以上。糙海参胚胎和幼体发育可分为受精卵、卵裂期、囊胚期、旋转囊胚期、原肠期、初耳状幼体、中耳状幼体、大耳状幼体、樽形幼体和稚参等阶段;在平均水温29℃,平均盐度34条件下,糙海参受精卵经3 h发育形成囊胚,4 h进入旋转囊胚期,5 h进入原肠期,19 h完成胚胎发育变态为耳状幼体;并经过7 d的生长与发育进入樽形幼体;第15天变态为稚参。观察发现,多精入卵现象则会导致胚胎发育不正常,最终使胚胎发育停止并死亡。在糙海参幼体发育过程中,大耳状幼体期幼虫臂的大小及其球状体的形成均可作为判断其幼体发育健康状况的重要指标:幼虫臂越大,球状体出现率越高,其幼虫的变态率和成活率也越高。对比发现,位于糙海参尾部的突出结构——尾突,为仿刺参和新西兰刺参所没有,这一结构差异同时导致了其骨片位置也不同;并且,糙海参胚胎和幼体与其他种类的海参在发育时间上存在一定差异。     

玉足海参与凡纳滨对虾的混养效果

在室内条件下进行了玉足海参与凡纳滨对虾的混养实验,分析了单养与混养两种条件下养殖水体营养盐结构以及底质成分的变化,测定了对虾与海参的存活率与生长性能。结果显示,混养海参可以明显改变养殖系统的营养盐结构,可使水体中的磷酸盐和硝酸盐浓度有所升高,同时也可有效地控制系统中氨氮浓度。混养海参也可以大幅度地降低沉积物中有机质和硫化物含量,实验结束时混养组硫化物含量为(7.71±1.33)mg/kg,仅相当于单养组浓度的1/3。混养海参对对虾生长及存活具有明显的促进作用,其中混养组对虾体长特异增长率为(0.69±0.13)%/d,显著优于单养组(0.45±0.06)%/d;混养组对虾成活率可达72.5%±22.9%,显著高于对照组55.0%±17.5%。在混养系统内,对虾不会对海参的生存造成负面影响,海参能够有效地选择摄食和利用沉积物中的营养物质(对食物中有机质的同化率可达36.36%±13.79%),并以较快的速度生长。结果表明,在对虾养殖系统中混养玉足海参具有明显的环境与经济效益。本研究可为我国海水养殖业的可持续发展提供一定的科学依据。     

Structural Characterization and Heparanase Inhibitory Activity of Fucosylated Glycosaminoglycan from Holothuria floridana

Unique fucosylated glycosaminoglycans (FG) have attracted increasing attention for various bioactivities. However, the precise structures of FGs usually vary in a species-specific manner. In this study, HfFG was isolated from Holothuria floridana and purified by anion exchange chromatography with the yield of ~0.9%. HfFG was composed of GlcA, GalNAc and Fuc, its molecular weight was 47.3 kDa, and the -OSO₃⁻/-COO⁻ molar ratio was 3.756. HfFG was depolymerized by a partial deacetylation–deaminative cleavage method to obtain the low-molecular-weight HfFG (dHfFG). Three oligosaccharide fragments (Fr-1, Fr-2, Fr-3) with different molecular weights were isolated from the dHfFG, and their structures were revealed by 1D and 2D NMR spectroscopy. HfFG should be composed of repeating trisaccharide units -{(L-FucS-α1,3-)d-GlcA-β1,3-d-GalNAc_4S6S-β1,4-}-, in which sulfated fucose (FucS) includes Fuc_2S4S, Fuc_3S4S and Fuc_4S residues linked to O-3 of GlcA in a ratio of 45:35:20. Furthermore, the heparanase inhibitory activities of native HfFG and oligosaccharide fragments (Fr-1, Fr-2, Fr-3) were evaluated. The native HfFG and its oligosaccharides exhibited heparanase inhibitory activities, and the activities increased with the increase of molecular weight. Additionally, structural characteristics such as sulfation patterns, the terminal structure of oligosaccharides and the presence of fucosyl branches may be important factors affecting heparanase inhibiting activity.     

Food sources,digestive efficiency and resource allocation in the sea cucumber Holothuria forskali (Echinodermata: Holothuroidea): Insights from pigments and fatty acids

Various research projects in Europe and North Africa have recently intended to breed temperate holothurians to alleviate fishing pressure on natural populations. However, to date little is known about the nutritional requirements of East Atlantic and Mediterranean species. In this study, we propose a “natural population”‐oriented approach to characterize food sources, digestive efficiency and resources allocation based on the composition of pigments and fatty acids (FA) in gut contents and tissues (muscles, gonads and digestive tract walls) of wild individuals of the species Holothuria (Panningothuria) forskali (Delle Chiaje, 1823) sampled in Brittany (France). Our study reveals that neither green nor red algae enter the diet of H. forskali in spring and that the only fresh vegetal material found in gut contents is brown algae (very likely diatoms). The high nutritional quality of gut contents however contrasts with the detrital nature of the ingested food sources, suggesting that a trophic upgrading of organic matter occurs before digestion. In addition, unusual FA (i.e. only present in a few groups of living species) such as long‐chain monounsaturated FA (especially the FA 23:1ω9) were found in large proportions in muscles and gonad and their effect on sea cucumber fitness needs further investigation.