Chemical Constituents from Starfish Asterias rollestoni

Aim To investigate novel bioactive and structural metabolites from marineorganisms. Methods Column chromatography in association with semi-preparative HPLC were used for theisolation of compounds. 1D and 2D NMR, IR, UV, and MS were employed for structure elucidation.Results From the butanol fraction of the 95% EtOH extract of the starfish Asterias rollestoni, a newcompound N^7 -2'-deoxypseudoxanthosine (1), along with sixteen known compounds, 2'-0-methyl-inosine(2), 2'-deoxyinosine (3), 2'-0-methylguanosine (4), inosine (5); thymine (6), uracil (7), thymidine(8), deoxyuridine (9), 2'-0-methyluridine (10), ( ― )-(1S, 3S)-1-methyl-1, 2, 3,4-terrahydro-β-carboline-3-carboxyl-ic acid (11), ( ― )-(1R, 3S)-1-methyl-1, 2, 3,4-tetrahydro-β-carboline-3-carboxylic acid (12) , ( ― )-(3S)- 1, 2, 3,4-tetrahydro-β-carboline-3-carboxylic acid (13), L-tryptophan (14), L-phenylalanine (15), 3-carboxyindole (16), and p-hydroxybenzoic acid (17) , have been isolated. Conclusion Compound 1 is a newnatural product, and compounds 8, 9 and 10 are isolated from natural sources for the first time, andthe known compounds except 14 and 15 are first reported from starfish Asterias rollestoni.

A New Asterosaponin from the Starfish Culcita novaeguineae

A new asterosaponin named novaeguinoside A, along with a known saponin, asteronyl pentaglycoside sulfate, was isolated from the starfish Culcita novaeguineae. The new compound was identified to be sodium 6α-O-{β-D-fucopyranosyl-(1→2)-β-D-fucopyranosyl-(1→4)-[β-D- quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-β-D-quinovopyranosyl}-5α-pregn-9(11)-en- 20-one-3β-yl-sulfate by extensive spectral analysis and chemical evidence.

A new polyhydroxysteroidal glycoside from the starfish Anthenea chinensis

A new polyhydroxysteroidal glycoside, （20R,24R）-16-O-（4-O-methyl-2-acetamido-2-deoxy-β-D-galactopyranosyl）-24-ethyl- 5α-cholest-8（14）-en-313,613,713,16α-tetrol （anthenoside A, 1）, was isolated from the starfish Anthenea chinensis. Its structure was elucidated by extensive spectral analysis and chemical evidences. 1 exhibited significant cytotoxicity against human tumor K-562, BEL-7402 and U87MG cells.

Patterns and Cellular Mechanisms of Arm Regeneration in Adult Starfish Asterias rollestoni Bell

To understand the mechanisms of starfish regeneration, the arms of adult starfish Asterias rollestoni Bell were amputated and their regeneration patterns and cellular mechanisms were studied.It was found that cells in the outer epidermis and inner parietal peritoneum near the end of the stump began to dedifferentiate 4 d after amputation. The dedifferentiated cells in the outer epidermis proliferated,migrated to the wound site and formed a thickened pre-epidermis which would then re-differentiate gradually into ma-ture epidermis.The new parietal peritoneum formed on the coelomic side of wound might be from the curvely elongated parietal peritoneum, resulting from the dedifferentiated and proliferated cells by extension. Afterwards, the proliferated cells made the outer epidermis and inner parietal peritoneum invaginate into the interior dermis and formed blastema-like structures together with induced dedifferentiated dermal cells. Most interestingly, the arm regeneration in A. rollestoni was achieved synchronously by de novo arm-bud formation and growth, and arm-stump elongation. The crucial aspects of arm-bud formation included cell dedifferentiation, proliferation and migration, while those of arm-stump elongation included cell dedifferentiation, proliferation, invagination, and arm-wall-across blastema-like structure formation. The unique pattern and cellular mechanisms of amputated arm regeneration make it easier to understand the rapid regeneration process of adult starfish. This study may lay solid foundations for the research into mo-lecular mechanisms of echinoderm regeneration.

Feeding Broodstocks Different Starfish Diets Affect Growth and Survival of Larvae of Trumpet Shell(Charonia lampas sauliae Reeve 1844)

Trumpet shell(Charonia lampas sauliae)(Mollusca, Heterogastropoda, Cymatidae) has extensive economic value. Studies on the artificial larval development of C. lampas sauliae for aquaculture utilization have become especially important due to the finite natural resources. In the present study, the growth and survival rate of the larvae of C. lampas sauliae broodstocks fed three types of starfish diets, Asterina pectinifera Müller & Troschel 1842, A. amurensis Lütken 1871 and their mixture were compared. The larval size increased gradually between day 10 and day 20 after hatching at 15℃ and 20℃. No difference was found in body size and specific growth rate(SGR)(two-way ANOVA; P > 0.05). However, during transition from trochophore to veliger stage 20 days after hatching, significant increases in larval survival and growth rates were observed. The maximum survival rate was observed on day 10. The mean survival rate was 0.463, 0.730 and 0.515 at 15℃, and 0.369, 0.713 and 0.444 at 20 when ℃ A. pectinifera, A. amurensis and their mixture were fed, respectively. The SGR and survival rate of the larvae were definitely influenced by the diets(P < 0.05), and the effect of A. amurensis alone was higher than that of A. pectinifera alone and their mixture.

A Bionic Starfish Adsorption Crawling Soft Robot

A variety of soft wall-climbing robots have been developed that can move in certain patterns.Most of these soft robots can only move on conventional surfaces and lack adaptability to complex surfaces.Improving the adaptability of soft robots on complex surfaces is still a challenging problem.To this end,we study the layered structure of the starfish tube foot and the valve flap structure in the water vascular system,and use an ultrasonic stress detector to study the stiffness distribution of the arm structure.Inspired by the motion of the starfish,we present a bionic soft wall-climbing robot,which is driven by two groups of pneumatic feet and achieves body bending through active adaptation layers.We design the structure of the foot to flex to provide driving force,and there are suction cups at the end of the foot to provide suction.The soft foot has a simple structure design,adapts to a variety of surfaces,and does not damage the surface of the substrate.Variable stiffness layers achieve stiffness changes by the principle of line blocking.The Central Pattern Generator theory is introduced to coordinately control the multiple feet of the robot.After experiments,we verify the adaptability of the soft robot to curved surfaces.The research may provide a reference for the design and development of crawling soft robots on complex surfaces.

Total Synthesis of Starfish Cyclic Steroid Glycosides.Part 2,Model Synthesis via Intramolecular Etherification

Comprehensive Summary Sepositoside A(1)is a prototypical cyclic steroid glycoside bearing a hybrid 16-membered ring composed of the steroid skeleton and a 1,2-trans-linked trisaccharide.Herein,we report an expedient access toward two simplified analogues,in which the strained 16-membered ring is constructed via Au(I)-catalyzed intramolecular addition of alcohol to epoxide.A similar macroetherification in relevant steroid trisaccharides has been intensively examined,however,failed to furnish the macrocyclic skeleton of Sepositoside A.

Total Synthesis of Starfish Cyclic Steroid Glycosides.Part 3,Formal Total Synthesis of Luzonicosides A and D

Comprehensive Summary Luzonicosides A(1)and D(2)are the major saponins isolated from pacific starfish Echinaster Luzonicus,featuring a sterically congested 16-membered ring which is formed by bridging the C3 and C6 of a 3β,6β-dihydroxy-Δ7-ene steroid with a 1,2-trans-linked linear trisaccharide via glycosidic and ether bonds,respectively.Here,we describe a formal total synthesis of starfish cyclic steroid glycosides 1 and 2.The synthetic route is highly modular and versatile,involving construction of the 16-membered macrocycles via Au(I)-catalyzed intramolecular glycosylation,highly efficient installation of unsaturated sugar moieties with ortho-hexynylbenzoates,elaboration of glucuronic acid unit via post-oxidation,and a de novo synthesis of the ether-linked pyranose unit.

Total Synthesis of Starfish Cyclic Steroid Glycosides.Part 1,Synthesis of the Aglycone and Attempts at Installation of the Sugar Units

Comprehensive Summary Sepositoside A(1)is the major and first cyclic steroid glycoside isolated from starfishes,which features a strained 16-membered ring formed by tethering C3 and C6 of the steroid aglycone with a linear trisaccharide.We conceived a convergent synthetic plan in which sepositoside A was disconnected into a disaccharide and a steroid-glucose hybrid ether.The desired 3β,6β-dihydroxy-Δ7,8-23-one aglcyone was readily prepared from dehydroepiandrosterone in 12 steps.The etherification of the 6β-hydroxy-Δ7,8-steroid with a variety of hexopyranoside-C6-electrophiles and CO_(2)-extrusion of a steroid-pyranose hybrid carbonate were extensively studied;however,formation of the desired steroid-pyranose etherate linkage has not been successful.Model studies on theβ-selective installation of the(1→2)-linked disaccharide onto the steroidal C3β-OH with the corresponding disaccharideα-imidates were also examined,however,formation of theα-glycosides prevailed.The present results force us to explore alternative approaches to construct the steroid-pyranose etherate linkage and stepwise assembly of the glycans en route to the starfish cyclic steroid glycosides,which will be presented in two articles that follow.

西沙海域长棘海星潜在鱼类捕食者鉴定

长棘海星的暴发对我国乃至印度−太平洋海域的珊瑚礁造成了严重的破坏。鱼类捕食者被认为是控制长棘海星种群暴发的重要因素,但我国对于可捕食长棘海星的鱼类的研究尚属空白。通过采集西沙5个长棘海星暴发礁区的珊瑚礁鱼类,利用PCR技术检测了鱼肠道内容物中的长棘海星DNA,并与已报道的长棘海星鱼类捕食者进行了比较分析。结果显示,本次调查共捕获了62尾鱼,共23科36属50种。在4种鱼的肠道内容物中检测到长棘海星DNA,分别是颊吻鼻鱼(Naso lituratus)、网纹宅泥鱼(Dascyllus reticulatus)、三叶唇鱼(Cheilinus trilobatus)和赤鳍裸颊鲷(Lethrinus erythropterus)。其中颊吻鼻鱼、三叶唇鱼和赤鳍裸颊鲷为首次报道的长棘海星潜在捕食者。本研究首次鉴定了我国长棘海星潜在鱼类捕食者种类,为开发长棘海星早期防控技术提供了重要参考。

Novel porous starfish-like Co3O4@nitrogen-doped carbon as an advanced anode for lithium-ion batteries

A Co-based metal-organic framework （Co-MOF） with a unique three-dimensional starfish-like nanostructure was successfully synthesized using a simple ultrasonic method. After subsequent carbonization and oxidation, a nanocomposite of nitrogen-doped carbon with a Co3O4 coating （Co3O4@N-C） with a porous starfish-like nanostructure was obtained. The final hybrid exhibited excellent lithium storage performance when evaluated as an anode material in a lithiumion battery. A remarkable and stable discharge capacity of 795 mAh·g^-1 was maintained at 0.5 A·g^-1 after 300 cycles. Excellent rate capability was also obtained. In addition, a full Co3O4@N-C/LiFePO4 battery displayed stable capacity retention of 95% after 100 cycles. This excellent lithium storage performance is attributed to the unique porous starfish-like structure, which effectively buffers the volume expansion that occurs during Li^＋ insertion/deinsertion. Meanwhile, the nitrogendoped carbon coating enhances the electrical conductivity and provides a buffer layer to accommodate the volume change and accelerate the formation of a stable solid electrolyte interface layer.

南海长棘海星物种有效性探讨

南海长棘海星暴发已严重威胁到该海域珊瑚礁生态系统健康,乃至整个南海生物多样性。针对南海长棘海星拉丁学名混用、中文名不统一的现状,我们采集了中沙群岛济猛暗沙海域长棘海星样品,结合长棘海星此前物种分类和分布的研究结果,对南海长棘海星物种有效性进行探讨。结果表明:所有长棘海星序列明显分为4个类群,各类群间遗传距离范围为0.087 5~0.104 7,达到了种间差异水平。南海长棘海星与长棘海星的太平洋种聚类到一起,实为太阳长棘海星(Acanthaster solaris),与其余3个种存在明显的种间差异。太阳长棘海星中2个支系间的遗传距离为0.005 3,在COⅠ基因层面属于种内差异。南海长棘海星物种有效性的研究结果为后续开展其遗传特征与适应性机制、种群分布与扩散机制、种群暴发机制等内容的研究提供科学依据。

Antibacterial activity of starfish Stellaster equestris from Southeast Coast of India

Objective:To isolate and characterize the antibacterial compounds from starfish Stellaster equestris(S.equestris).Methods:The whole body was extracted with high polar and medium polar solvents such as methanol and ethanol.The antibacterial activity has been tested against human bacterial pathogens using standard disc diffusion method.Results:The starfish S.equestris was collected from Mudasalodai,southeast coast of India.the maximum zone inhibition[(9.7±0.3)mm]against Escherichia coli(E.coli)and Vibrioparahaemolyticus at 100%concentration and minimum was Staphylococcus aureus[(4.0±0.6)mm].The crude ethanol extract showed maximum zone of inhibition in E.coli[(9.70±0.33)mm]and the lowest concentration exhibited the minimum inhibition activity against all bacterial pathogens.The fractions showed the maximum inhibition zone in Klebsiella oxytoca(5.00±0.82 mm),Salmonella typhi(S.typhi)(5.00±0.82)and Staphylococcus aureus[(3.0±2.3)mm].One way ANOVA analysis of antibacterial activity showed no significant difference at 0.05%level(P>0.05).The crude ethanol extract showed the minimum inhibitory concentration against E.coli(100%),Klebsiella pneumoniae The present investigation exhibited that the crude methanol extract showed the minimum inhibitory concentration against Klebsiella pneumonia,Proteus mirabilis,S.typhi,Staphylococcus aureus and Vibrio cholerae at 100%whereas E.coli was at 75%concentration.No bacterial growth was observed against Klebsiella oxytoca at 100%concentration.Conclusions:(75%),S.typhi(100%)and Vibrio cholerae(100%).The fraction exhibited equestris have remarkable antimicrobial activities against human bacterial pathogens.Further fraction has been characterised by using GC-MS and ^(1)H and ^(13)NMR spectroscopy analysis.The result of the present study indicates that the crude and fractions of starfish S.

Studies on antioxidant properties of starfish Luidia maculata(Muller&Troschel,1842)off Parangipettai,Southeast coast of India

Objective:To investigate the antioxidant properties of starfish Luidia maculata.Methods:The crude ethanol extract was partially purified using liquid-liquid partition and size exclusion chromatography.The antioxidant properties of partially purified fractions were determined using the following methods:determination of total phenolic content,DPPH radical scavenging assay,hydrogen peroxide radical scavenging assay and reducing power assay.Results:Among the five fractions,collected fraction 3,4 and 5 exhibited antioxidant potential.Total phenolic content was high(360μg GAE/g)in fraction 3.In DPPH assay,fraction 3 showed the highest IC_(50)value 0.27 mg/mL and hydrogen peroxide scavenging assay showed the highest IC_(50)value of 0.07 mg/mL in fraction 5.Whereas,fraction 3 showed the highest absorbance(0.3)in reducing power assay when compared to fraction 4 and 5.Conclusions:In conclusion,the present study shows the extract of starfish Luidia maculata(F3)possesses good antioxidant activity.

一种多浮体铰接式波浪能装置的运动分析与俘获特性研究

基于线性势流理论,利用总模态法对多浮体铰接波浪能装置“海星号”在波浪中的运动开展水动力学系数计算;然后基于矢量力学建立多浮体刚体运动学方程,并结合几何约束条件开展动态响应计算,获得最优俘获效率和最优负载阻尼;最后比较并分析“海星”波浪能装置的多浮体俘获效率,获得“海星”多浮体做功的俘获特性。研究表明:“海星”波浪能装置的多浮体四向迎波设计可拓宽装置最优俘获频带宽度,提高装置整体俘获效率;正向迎波与背向迎波俘获波浪能方式相比,小周期情况下,正向吸波浮体俘获效率较高,随着周期增大,正向吸波浮体俘获效率开始降低,背向吸波浮体俘获效率开始增大,极大周期情况下,正向吸波浮体和背向吸波浮体俘获效率趋于一致且趋近于零。

常见海洋动物皂苷生物活性的研究进展

皂苷是一类甾体或三萜的糖苷类化合物,以疏水性三萜或甾醇为主链,亲水性碳水化合物链是皂苷的特征[1]。皂苷主要可以分类为甾体皂苷、三萜皂苷、螺甾皂苷和呋甾皂苷[2]。皂苷广泛分布于高等植物中,许多中草药如人参、甘草、柴胡和桔梗等的主要有效成分都含有皂苷[3],由于皂苷具有多种生物活性,其在制药、食品和营养保健品等行业领域占有重要地位[4-6]。

生物天敌暴发导致珊瑚礁退化的高分遥感监测与分析——以南海太平岛为例

珊瑚生物天敌黑皮海绵、长棘海星在世界范围内暴发严重威胁珊瑚礁生态健康,然而目前珊瑚礁领域尚缺乏生物天敌暴发后对珊瑚礁地貌类型影响的定量研究。文章利用太平岛珊瑚生物天敌黑皮海绵、长棘海星2次暴发事件前后,覆盖太平岛2016—2022年的26期Sentinel-2遥感影像,结合高分辨率GF-2(PMS)遥感影像和卫星遥感影像地理信息系统Google Earth平台中的数据,开展中国南海太平岛珊瑚礁地貌类型遥感影像分类实验,对密集珊瑚沉积区、稀疏珊瑚沉积区、珊瑚丛生区、沙坪、浅礁前斜坡等珊瑚礁地貌类型演变进行特征分析。结果表明:1)结合专家解译知识和支持向量机(Support Vector Machine,SVM)分类算法开展的太平岛珊瑚礁地貌类型分类,最高总体精度和Kappa系数分别为96.46%和0.94。2)在2种珊瑚生物天敌暴发期间,太平岛的珊瑚礁丛生区、密集珊瑚沉积区、稀疏珊瑚沉积区等珊瑚礁地貌类型面积有显著下降;黑皮海绵暴发后对密集珊瑚沉积区影响最大,其面积减少72.92%;长棘海星暴发后对珊瑚丛生区影响最大,其面积减少59.17%。3)2016—2022年,太平岛珊瑚礁退化率高于恢复率,其中2017年3—6月珊瑚礁退化率最高,为23.88%;在2017年6—9月珊瑚礁恢复率最高,为18.03%。

基于改进Mask R-CNN的海参和海星的检测算法

目的:为了提高水下复杂环境下检测海参和海星等水下目标物的鲁棒性。方法:提出了基于改进Mask R-CNN的海参和海星实例分割算法,该算法以Mask R-CNN结构为主框架,将Swin Transformer主干网络代替Mask R-CNN原本的ResNet卷积神经网络;同时采用Water-Net网络对海参和海星实例数据集进行图像增强;最后采用Soft-NMS的方法替换经典的NMS算法。结果:在本文自己标定的数据集上进行实验,与改进前Mask R-CNN相比,本文算法检测框检测mAP可达到70.6%,提升6.4%;实例分割mAP达到了69.2%,提高了4.7%,并且正确率收敛于97%。结论:与其他主流目标检测算法相比较,本文提出的方法具有更高的检测精度,在水下目标检测任务上更加具有优势。