水鳖科三种海草的染色体及其核型的研究(英文)

[目的]对采自海南黎安港的3种水鳖科海草—海菖蒲(Enhalus acoroides)、泰来藻(Thalassia hemprichii)和小喜盐草(Halophila minor)的染色体及其核型进行研究。[方法]采用海菖蒲和泰来藻的根尖及小喜盐草的腋芽为材料,采用常规压片法制备染色体玻片标本,并对其进行核型分析。[结果]海菖蒲和泰来藻的染色体数目为 2n=18,小喜盐草的染色体数目为2n=28,两者均未发现B染色体和随体;海菖蒲、泰来藻和小喜盐草的核型公式分别为K(2n)=18=12m+6sm,K(2n)=18=12m+6sm,K(2n)=28=16m+8sm+4st;按Stebbins的核型分类标准,海菖蒲和泰来藻的染色体属2A类型,小喜盐草为2B型。[结论]通过对3种海草核型进行比较发现,海菖蒲与泰来藻的核型差距很小,而它们与小喜盐草的核型差距较大,说明海菖蒲与泰来藻的亲缘关系更近。     

Cover and edge length to area ratio of seagrass (Thalassia testudinum) meadows in coral reef lagoons (Veracruz Reef System,Southwest Gulf of México)

• 1. Habitat loss and habitat fragmentation are usually correlated while habitat degradation may occur independently of them. Natural and anthropogenic disturbances increase the spatial fragmentation of seagrass meadows with unknown consequences on the vegetative development achieved by seagrass.
• 2. Cover and spatial fragmentation of Thalassia testudinum meadows in three coral reef lagoons of the Veracruz Reef System,VRS (SW Gulf of México) were quantified by analysing low‐altitude images acquired by photographic and digital video cameras from a helium‐filled blimp. Spatial fragmentation was quantified as the ratio of the length of meadow edge to meadow area. The number of blowouts (erosive gaps in seagrass meadows) was also recorded.
• 3. Meadow cover was negatively correlated with the length of meadow edge to meadow area ratio. The number of blowouts per ha of T. testudinum meadow was negatively correlated with meadow cover and positively with the length of meadow edge to meadow area ratio. Wave exposure is probably a main component of the processes determining the cover and spatial fragmentation of T. testudinum meadows in VRS.
• 4. Low cover and high spatial fragmentation of T. testudinum meadows in VRS are associated with low vegetative development of this seagrass species. Copyright © 2011 John Wiley & Sons, Ltd.

     

Seagrass on the edge: Land-use practices threaten coastal seagrass communities in Sabah, Malaysia

Seagrass meadows are susceptible to coastal environmental impacts and serve as early indicators of system-wide degradation. Two SeagrassNet monitoring sites were established in Sabah (Malaysia) in 2001 in the Tunku Abdul Rahman National Park: one a pristine, reference site and one anticipating impacts from nearby, ongoing waterfront development. At both sites, percent cover of all seagrass species declined significantly between 2003 and 2005. Water temperature, fine sediment and specific leaf biomass increased, while percent surface light intensity reaching the plants decreased. Evidence suggests that the temperature changes observed during the monitoring period were not sufficient to impact seagrasses; rather, the documented reduced subsurface light intensity caused the observed seagrass declines. Concomitantly, satellite imagery revealed a persistent sediment plume in these coastal waters associated with deforestation. SeagrassNet monitoring quickly documented seagrass losses and identified the causal environmental factor, providing timely information for management consideration.     

Molecular Networking Leveraging the Secondary Metabolomes Space of Halophila stipulaceae (Forsk.) Aschers. and Thalassia hemprichii (Ehrenb. ex Solms) Asch. in Tandem with Their Chemosystematics and Antidiabetic Potentials

The Red Sea is one of the most biodiverse aquatic ecosystems. Notably, seagrasses possess a crucial ecological significance. Among them are the two taxa Halophila stipulacea (Forsk.) Aschers., and Thalassia hemprichii (Ehrenb. ex Solms) Asch., which were formally ranked together with the genus Enhalus in three separate families. Nevertheless, they have been recently classified as three subfamilies within Hydrocharitaceae. The interest of this study is to explore their metabolic profiles through ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS/MS) analysis in synergism with molecular networking and to assess their chemosystematics relationship. A total of 144 metabolites were annotated, encompassing phenolic acids, flavonoids, terpenoids, and lipids. Furthermore, three new phenolic acids; methoxy benzoic acid-O-sulphate (16), O-caffeoyl-O-hydroxyl dimethoxy benzoyl tartaric acid (26), dimethoxy benzoic acid-O-sulphate (30), a new flavanone glycoside; hexahydroxy-monomethoxy flavanone-O-glucoside (28), and a new steviol glycoside; rebaudioside-O-acetate (96) were tentatively described. Additionally, the evaluation of the antidiabetic potential of both taxa displayed an inherited higher activity of H. stipulaceae in alleviating the oxidative stress and dyslipidemia associated with diabetes. Hence, the current research significantly suggested Halophila, Thalassia, and Enhalus categorization in three different taxonomic ranks based on their intergeneric and interspecific relationship among them and supported the consideration of seagrasses in natural antidiabetic studies.     

Interaction of Thalassia testudinum Metabolites with Cytochrome P450 Enzymes and Its Effects on Benzo(a)pyrene-Induced Mutagenicity

The aim of the present work was to evaluate the effects of Thalassia testudinum hydroethanolic extract, its polyphenolic fraction and thalassiolin B on the activity of phase I metabolizing enzymes as well as their antimutagenic effects. Spectrofluorometric techniques were used to evaluate the effect of tested products on rat and human CYP1A and CYP2B activity. The antimutagenic effect of tested products was evaluated in benzo[a]pyrene (BP)-induced mutagenicity assay by an Ames test. Finally, the antimutagenic effect of Thalassia testudinum (100 mg/kg) was assessed in BP-induced mutagenesis in mice. The tested products significantly (p < 0.05) inhibit rat CYP1A1 activity, acting as mixed-type inhibitors of rat CYP1A1 (Ki = 54.16 ± 9.09 μg/mL, 5.96 ± 1.55 μg/mL and 3.05 ± 0.89 μg/mL, respectively). Inhibition of human CYP1A1 was also observed (Ki = 197.1 ± 63.40 μg/mL and 203.10 ± 17.29 μg/mL for the polyphenolic fraction and for thalassiolin B, respectively). In addition, the evaluated products significantly inhibit (p < 0.05) BP-induced mutagenicity in vitro. Furthermore, oral doses of Thalassia testudinum (100 mg/kg) significantly reduced (p < 0.05) the BP-induced micronuclei and oxidative damage, together with an increase of reduced glutathione, in mice. In summary, Thalassia testudinum metabolites exhibit antigenotoxic activity mediated, at least, by the inhibition of CYP1A1-mediated BP biotransformation, arresting the oxidative and mutagenic damage. Thus, the metabolites of T. testudinum may represent a potential source of chemopreventive compounds for the adjuvant therapy of cancer.     

水鳖科3种海草的染色体及其核型的研究

[目的]对采自海南黎安港的3种水鳖科海草———海菖蒲(Enhalus acoroides)、泰来藻(Thalassia hemprichii)和小喜盐草(Halophilaminor)的染色体及其核型进行研究。[方法]采用海菖蒲和泰来藻的根尖及小喜盐草的腋芽为材料,采用常规压片法制备染色体玻片标本,并对其进行核型分析。[结果]海菖蒲和泰来藻的染色体数目为2n=18,小喜盐草的染色体数目为2n=28,两者均未发现B染色体和随体;海菖蒲、泰来藻和小喜盐草的核型公式分别为K(2n)=18=12m+6sm,K(2n)=18=12m+6sm,K(2n)=28=16m+8sm+4st;按Stebbins的核型分类标准,海菖蒲和泰来藻的染色体属2A类型,小喜盐草为2B型。[结论]通过对3种海草核型进行比较发现,海菖蒲与泰来藻的核型差距很小,而它们与小喜盐草的核型差距较大,说明海菖蒲与泰来藻的亲缘关系更近。     

海南新村湾泰来草形态和生理指标特征及环境影响因素

海草具有重要的生态系统服务功能,其形态和生理指标受到各种环境因素的影响。本研究在2019年对海南陵水新村湾泰来草(Thalassia hemprichii)海草床进行了6次采样调查,研究了一年内1月、3月、5月、7月、9月和11月的海草形态和生理特征,分析了环境因素对泰来草形态和生理特征的影响。结果显示,泰来草形态指标叶长、叶宽、根状茎直径、根长在不同月份间存在显著差异,叶长最大值和最小值分别出现在5月[(15.05±6.13) cm]和9月[(7.19±2.55) cm];叶宽最大值和最小值分别出现在11月[(11.93±1.68) mm]和9月[(8.73±1.96) mm];根状茎直径最大值和最小值分别出现在11月[(5.22±1.71) mm]和3月[(4.06±0.74) mm]。泰来草地下组织碳含量在不同月份间存在显著差异,最大值和最小值分别出现在11月[(31.23±0.94)%]和3月[(24.90±3.48)%]。相关性分析显示,海水温度与泰来草叶宽、地下组织碳含量呈显著正相关;盐度与叶长和根状茎长呈显著正相关,与地下组织碳含量呈显著负相关;海水pH与叶长、叶宽、地下组织碳含量和地下组织氮含量呈显著正相关。海水中的溶解无机氮、氨氮和硝酸氮对海草生理指标有显著影响。沉积物有机碳含量与叶长、叶宽和根状茎长呈显著负相关。研究表明,新村泰来草的生长受到温度、盐度、pH的影响较大,高营养盐水平可能对泰来草产生负面影响,应该限制该地区营养盐输入。本研究可为保护新村湾泰来草海草床以及修复受损海草床生态提供数据支撑和科学依据。 海南省近岸海洋生态环境过程与碳汇重点实验室 海南 三亚 572022