黑藻早期个体发育的研究

对黑藻（Hydrilla verticillata）个体发育中的胚胎发育（从合子到种子胚）和种苗发育（从种子到种苗）进行了研究。发现沉水植物黑藻与挺水植物泽泻（Alisma orientale）在胚柄只有1～2个细胞、种子胚苗端发达根端未分化、萌发后根端始分化、分生区之上产生根环与下胚轴毛、初生根短命等特点上基本相同,并对这些特点进行了讨论。     

镉在黑藻叶细胞中的亚显微定位分布及毒害效应分析

Aquatic plants are known to accumulate and bioconcentrate heavy metals. In this study, aquatic vascular plant Hydrilla verticillata (L.f.) Royle was cultivated in water containing elevated concentrations of cadmium (up to 10 mg/L) for 7 d, the accumulation, subcellular distribution, ultrastructural localization, chemical form, toxic effects on mineral nutrient absorption of cadmium, photosynthesis rate and respiration rate were studied. It was found that H. verticillata fronds was able to accumulate cadmium, the bioconcentration factor was 193-307; subcellular fraction analysis revealed that cadmium major accumulated in cell wall (61.66%-52.00%) with decrease trends, the content of Cd enhanced in soluble fraction and remained stable in organelles, with the augment of pollutant concentration. The Cd levels occurred in different parts of leaf cell with the following sequence: cell wall > soluble fraction > organelles. Ultrastructural localization of cadmium with sulfide-silver method showed that Cd appeared in cell wall, chloroplast, nucleus and vacuole. Sequential extraction indicated that the ratio of different cadmium chemical form was different markedly, of which NaCl extractable Cd was predominated as compared with the other 5 forms; which could be seen in the following order: F(NaCl) > F(HAc) >F(Water) > F(Ethanol) > F(HCl) > F(Residue). The mineral nutrient absorption was also affected by cadmium stress, it increased the absorption of Ca, Mn, Cu, and Fe; but reduced that of P and K. Cd had a strong inhibitive effect on photosynthesis rate and respiration rate. The results suggested that the toxic symptoms of plant showed an evident correlation between dose and effect; the ultrastructural damage was closely related to the distribution of Cd. The conclusion could be reached that the death of plant was resulted from destruction of structure foundation of physiological function, unbalance of ion equilibrium and disorder of physiological metabolism.     

Zinc supplementation imparts tolerance to arsenite stress in Hydrilla verticillata (L.f.) Royle

The present study was aimed to analyze the effects of external Zn supply on arsenic (As) toxicity in Hydrilla verticillata (L.f.) Royle. The plants were exposed to arsenite (AsIII; 10 μM) with or without 50 and 100 μM Zn. The level of As accumulation (μg g^?1 dw) after 2 and 4 days was not significantly affected by Zn supply. The plants showed a significant stimulation of the thiol metabolism (nonprotein thiols, cysteine, glutathione-S-transferase activity) upon As(III) exposure in the presence of Zn as compared to As(III) alone treatment. Besides, they did not experience significant toxicity, measured in terms of hydrogen peroxide and malondialdehyde accumulation, which are the indicators of oxidative stress. The minus Zn plants suffered from oxidative stress probably due to insufficient increase in thiols to counteract the stress. Stress amelioration by Zn supply was also evident from antioxidant enzyme activities, which came close to control levels with increasing Zn supply as compared to the increase observed in As(III) alone treatment. Variable Zn supply also modulated the level of photosynthetic pigments and restored them to control levels. In conclusion, an improved supply of Zn to plants was found to augment their ability to withstand As toxicity through enhanced thiol metabolism.     

Cu、Zn在黑藻叶片中的富集及其毒理学分析

本文以分布广泛的沉水植物———黑藻为研究对象,在人工模拟的含不同浓度的Cu、Zn污水中培养7d,研究了Cu、Zn在黑藻体内的富集及部分毒理学影响。研究表明:黑藻对Cu和Zn都有较强的富集作用,黑藻叶片中的Cu、Zn含量都随介质中金属浓度的增大而呈增长趋势,统计分析都达到极显著正相关(RCu=0.9875,P<0.01;RZn=0.9990,P<0.01)。但黑藻对Cu、Zn吸收和积累能力(以富集系数表示)不同:对Cu的富集系数为571—1328;对Zn的富集系数为346—830。这表明黑藻对Cu的吸收能力大于Zn,而富集系数随外界浓度的增大而下降,则说明较低处理浓度更有利于黑藻对金属元素的吸收。逐步提取法分析表明黑藻体内Cu是2%醋酸提取态最多,而Zn是以1mol/L的NaCl溶液提取态占优势。各结合形态的含量多少依次为:Cu:FHAc>FHCl>FNaCl>FWater>FEthanol>FResidue;Zn:FNaCl>FHAc>FHCl>FEthanol>FResidue>FWater。激光共聚焦扫描显微镜观察结果显示Cu、Zn污染后黑藻叶片自发荧光范围变窄,峰值变小,平均强度减小。扫描电镜和透射电镜观察发现,黑藻叶细胞形态和结构发生了较明显的变化,主要表现为:细胞壁扭曲,细胞变形;细胞核核仁解体,染色质凝集,核膜断裂;叶绿体类囊体膨胀,被膜破裂;线粒体嵴数目减少,线粒体呈空泡状。结果表明,Cu、Zn在黑藻叶中富集得越多,造成的毒害越重,剂量效应非常明显。     

太湖生态修复植物黑藻的化学成分研究

黑藻Hydrilla verticillata(L.f.)Royle是应用于太湖的生态修复的一种沉水植物,本文首次从环境修复植物黑藻Hydrilla verticillata(L.f.)Royle全草的提取物中分离得到7个化合物,根据质谱和红外光谱数据分别鉴定为12-羟基十二酸(1)、11,14-二十碳二烯酸(2)、β-谷甾醇乙酸酯(3)、β-谷甾醇(4)、棕榈酸乙酯(5)、1,14-十四碳二酸(6)和6,10,14-三甲基-2-十五酮(7),其中1、4、5、7为生物活性物质。     

Allelopathic influence of Hydrilla verticillata (L.F.) Royle on the distribution of Ceratophyllum species

Ceratophyllum demersum L. and C. muricatum Chamisso are not found to grow together with Hydrilla verticillata (L.f.) Royle in India. An experimental study shows that Hydrilla is allelopathic to the two species of Ceratophyllum and inhibits their growth. Thus, the distribution of Ceratophyllum species is limited by the presence of Hydrilla.     

Genetic diversity of the submerged macrophyte Hydrilla verticillata (L. f.) Royle in a river system in Japan

The genetic diversity of Hydrilla verticillata was studied in the Kako River system, Hyogo Prefecture, southwestern Japan, including some of its tributaries. Sex expression (monoecy or dioecy), ploidy level (diploid or triploid), and isoenzyme phenotypes were investigated for plant samples collected from 51 sites along the water course. Monoecious plants occurred at 10 sites and dioecious plants at 47 sites. Among dioecious plants, diploid and triploid plants occurred at 1 and 46 sites, respectively. Seven multienzyme phenotypes (MEPs) were recognized by electrophoretic analysis among dioecious triploid plants. The distribution pattern of nine biotypes based on sex expression, ploidy level, and MEPs suggested the possibility of ecological differentiation among different biotypes. The implications of genetic diversity demonstrated in this study were discussed in relation to the conservation strategy of biodiversity in a river system. Received: April 12, 1999 / Accepted: July 7, 1999     

黑藻对水体和沉积物理化性质的改善和营养元素的去除作用

通过人工模拟实验,研究了不同种植密度(50、100和150株/ m2)的黑藻(Hydrilla verticillata)对富营养湖泊水体和沉积物理化性质的改善和营养元素的去除作用。结果表明：种植黑藻能显著提高水体溶解氧(DO)和沉积物的氧化还原电位(Eh), DO由3.95mg/L提高到10.42mg/L;沉积物Eh提高了58.6-109.4mV。黑藻的生长有效地降低了水体和沉积物中的氮、磷含量,水体中TP降低了38.9%-57.1%;NH4+-N的含量降低了90.2%; 沉积物中TN的含量比试验前中期降低了70.0%。50、100和150株/ m2 三个种植密度间对水质和沉积物的改善效果差异不明显,说明当单位面积生物量达到一定程度后改善效果也趋于饱和,故在富营养湖泊的植被恢复中种植密度不宜过大。     

Influence of photoperiod on vegetative propagule production in three turion-producing races of Hydrilla verticillata (L.f.) Royle

Three races of hydrilla observed to only produce turions were evaluated for photoperiod effects on propagule production. Greatest production was under shortdays (I 0-h). These races from Japan and Poland produced both turions and turion-like tubers under longday photoperiods (I 6-h) but production was most efficient under shortdays. Increased propagule production under shortdays may be compensation for decreasing photosynthetic activity at higher latitudes. Production appears only to be limited by temperature.     

Environmental conditions and phosphorus removal in Florida lakes and wetlands inhabited by Hydrilla verticillata (Royle): implications for invasive species management

Hydrilla verticillata is considered the most problematic aquatic plant in the United States. In south Florida, Hydrilla dominance has also been documented in treatment wetlands. This paper characterizes (1) environmental conditions which favor Hydrilla growth and (2) understand its nutrient removal capability. Despite its occurrence over a wide range of environmental conditions, Hydrilla abundance increased with increasing pH, alkalinity, total P and total N, and decreased with water depth in selected Florida lakes. No relationship was found between color, Secchi depth and Hydrilla abundance. In several Hydrilla-dominated lakes, mean total P concentration (126 μg/l) at inflow was reduced to 106 μg/l at outflow. The maximum inflow total P concentration in a lake with positive nutrient reduction was 148 μg/l. Total P removal efficiency by Hydrilla-dominated lakes and wetlands was comparable to or higher than systems dominated by emergent and other submerged plants. Mean total P settling rates for lakes and a constructed wetland dominated by Hydrilla were estimated at 19 and 34 m/year, respectively, which were higher than or comparable to similar systems dominated by other aquatic plants. Results from this study suggest that reduction of Hydrilla from constructed wetlands will not likely improve nutrient removal performance.     

Native flora and fauna response to removal of the weed Hydrilla verticillata (L.f.) Royle in Lake Tutira

Hydrilla has been in New Zealand since the 1960s and formed major infestations in four lakes in the Hawkes Bay region. Challenges to controlling hydrilla in New Zealand have included a lack of tools and the changing responsibilities of local management agencies. A grass carp field trial was initiated in 1988 in the smallest of the hydrilla infested lakes to assess the feasibility of eradicating hydrilla. After the main hydrilla beds were consumed, regrowth from tubers still occurred for a further 12 years. In 2008, grass carp were released into the remaining three hydrilla-infested lakes in a central government led response to eradicate hydrilla. This paper describes the changes in the flora and fauna in the largest of these lakes, Lake Tutira, following the introduction of grass carp and the removal of the hydrilla weed beds. Annual surveys of aquatic vegetation and macroinvertebrates in the lake from 2008 to 2012 have shown that, following the removal of the hydrilla weed beds by 2010, there was a shift in grass carp grazing to marginal emergent plants, and a general increase in the distribution of the native plant vegetation, although there was some evidence of a decline in charophyte abundance. Macroinvertebrate diversity was maintained although there were changes in the relative abundance of taxa linked to changes in the littoral vegetation.     

底质营养盐负荷对轮叶黑藻生长和光合荧光特性的影响

在实验室条件下,研究了用不同营养盐负荷底泥作为底质培育的轮叶黑藻(Hydrilla verticillata(L.f)Royle)的生长的效应,结果表明,在上覆水TN/TP为20-50,TP变化范围在0.03-0.05mg/L内,底质磷相对释放速率为0.33mg/(m.2d)时培育的轮叶黑藻生长最好。轮叶黑藻对环境有较强的适应性,培育期间各组光合荧光参数Fv/Fm,qP,ETRmax随培养时间均明显的升高;在非最佳生长条件下轮叶黑藻能通过自身光合荧光参数qN的升高,耗散掉过剩的光能,来对自身进行保护。     

不同浓度氨氮对轮叶黑藻的生理影响

在实验室条件下,比较研究了不同浓度（0.5、1、2、4、8、16mg/L）的氨氮（NH4＋-N）对沉水植物黑藻（Hydrilla verticillata）的生理生化影响,测定了黑藻生物量、叶绿素、可溶性糖、蛋白质含量和过氧化物酶（POD）、超氧化物歧化酶（SOD）、谷氨酰氨合成酶（GS）的活性变化。实验结果表明低浓度的氨氮（0.5、1、2mg/L）对轮叶黑藻的生长稍有促进作用,但培养液中氨氮浓度超过4mg/L时,黑藻的相对生长率（R）明显下降,当浓度达到16mg/L时,黑藻在20多天内全部死亡。在低浓度氨氮条件下,黑藻叶绿素和可溶性糖含量随氨氮浓度增加呈上升趋势,当培养液中氨氮浓度超过4mg/L时,叶绿素和可溶性糖含量在第24、32、40天取样时较对照组明显降低。低浓度氨氮处理组（0.5、1、2mg/L）的蛋白质含量先下降后又上升,而对照组的蛋白质含量一直在上升,高浓度氨氮处理组（8、16mg/L）的蛋白质含量则呈明显下降趋势。POD、SOD和GS活性变化趋势基本一致,在高浓度氨氮条件下增加显著,并表现为先上升再下降的格局,在第16天或第24天达到最大值。研究结果提示在富营养化条件下氨氮氨氮条件下增加显著,并表现为先上升再下降的格局,在第16天或第24天达到最大值。研究结果提示在富营养化条件下氨氮浓度的升高将影响其生理功能,过高浓度的氨氮对轮叶黑藻是一种逆境胁迫,可抑制其生长甚至导致植物死亡。轮叶黑藻对氨氮浓度变化虽有一定耐性,但耐性会随时间延长而变弱。     

Influence of photoperiod on tuber production in various races of Hydrilla (Hydrilla verticillata)

The potential for asexual reproduction throughproduction of tubers was evaluated in various races ofan International Hydrilla [Hydrilla verticillata (L.f.)Royle] germplasm collection. Interracecomparisons were made under both shortday and longdayphotoperiods in environmental growth chambers. Allthe races evaluated produced rates varying from91-7182 tubers per sq m of production under shortdayconditions. Tuber production occurred under longdayphotoperiods in several races. Under propertemperature conditions, all the monoecious racescurrently established in the U.S. appear capable oftuber production throughout the year.     

Lanthanum- and cerium-induced oxidative stress in submerged Hydrilla verticillata plants

Oxidative stress was induced in 10-day treated with lanthanum and cerium Hydrilla verticillata plants. Low 10 μM concentrations did not exert harmful effects. The plants treated with higher concentrations showed higher H₂O₂ content and lower chlorophyll and soluble protein contents as compared to control plants. At the same time, malondialdehyde content rose with increasing concentrations of La and Ce. As La and Ce concentrations increased, superoxide dismutase and catalase activities declined progressively, while peroxidase activity increased. Proline content decreased slightly at 10 μM La or Ce and then rose with higher concentrations. The results indicated that La and Ce caused oxidative damage as evidenced by increased lipid peroxidation and decreased chlorophyll and protein levels. Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 5, pp. 781–785. The text was submitted by the authors in English.     

黑藻花粉粒形态结构的观察

为了研究沉水植物特殊的生物学特性,观察了水鳖科黑藻(Hydrilla verticillata)花粉粒的光学显微镜和电子显微镜的形态与结构,其花粉粒的壁极薄且极易破裂,无萌发孔,内含许多淀粉粒。在自然状态下,无法完整保存其干燥的花粉粒。     

黑藻花粉粒形态结构的观察

为了研究沉水植物特殊的生物学特性 ,观察了水鳖科黑藻 (Hydrillaverticillata)花粉粒的光学显微镜和电子显微镜的形态与结构 ,其花粉粒的壁极薄且极易破裂 ,无萌发孔 ,内含许多淀粉粒。在自然状态下 ,无法完整保存其干燥的花粉粒。     

The effect of arsenic on pigment composition and photosynthesis in Hydrilla verticillata

The present study evaluated the effects of 100 and 500 μM arsenate (Na₂HAsO₄) on pigment composition and photosynthesis in Hydrilla verticillata (L.f.) Royle. Arsenic accumulation increased in concentration and duration dependent manner. The maximum accumulation [568 μg(As) g^?1(d.m.)] was observed at 500 μM concentration and 96-h exposure. This concentration led to a significant decline in chlorophyll a content and PS II efficiency during the whole experiment, and in chlorophyll b and carotenoids after 96 h, but no significant changes in photosynthetic pigments were noticed at 100 μM arsenate. Net photosynthetic rate, electron transport rate, and water use efficiency declined whereas transpiration rate increased, and stomatal conductance and photochemical quenching did not show any effect or increased. The content of reactive oxygen species increased and content of reduced ascorbate declined at 500 μM arsenate in comparison to the control.