Decay rates and nitrogen dynamics of decomposing watercress (Nasturtium officinale R.Br.)

We examined the decomposition of watercress in the laboratory at 10° and 20 °C, and in the field. Rates varied from 0.058 g g^?1 day^?1 in the laboratory to 0.115 g g^?1 day^?1 in the field. There was a rapid generation of particles of size <500 µm. It is thought that washout of these from the litterbags in the field accounted for high field decomposition rate. Formation of dissolved nitrogen compounds during decomposition followed a time series from NH _inf4 ^sup+ to NO _in2 ^sup? to NO _inf3 ^sup? withdissolved organic nitrogen accumulating at the end of decomposition. Ammonification rates were 480 and 657 g NH₄-N g^?1 (dry wt) day^?1 and nitrification rates on the decomposing tissue were 640 and 571 µg NO₃-N g^?1 (dry wt) day^?1 at 10° and 20 °C respectively. Fifty-six per cent of the initial plant N was regenerated as NO₃-N 21% as DON and 25% remained as refractory particulate N.     

The effect of different nutrient concentrations on the growth rate and nitrogen storage of watercress (Nasturtium officinale R. Br.)

The mechanisms that allow broadly distributed aquatic plants to inhabit variable resource environments are unclear, yet understanding these mechanisms is important because broad environmental tolerance is often linked to invasiveness in terrestrial and aquatic plants. In an experimental stream, we examined the effects of different nutrient concentrations on the growth rate, biomass, and foliar nutrient concentrations of a cosmopolitan and potentially invasive aquatic plant, Nasturtium officinale (R. Br.). Nasturtium seedlings were grown under six nutrient treatment levels ranging from 0.64 μm N:0.09 μm P to 1531 μm N:204.13 μm P, for 8 weeks. Absolute and relative growth rates, and biomass of seedlings increased along a gradient of increasing nutrient concentrations but the effect of nutrient concentration was dependent on growing time. Seedling biomass varied among nutrient treatments in weeks 4 through 8 of the experiment, but did not differ in week 2. By week 8, the two highest nutrient treatments had greater biomass than the two lowest nutrient treatments. Foliar nitrogen concentration increased, whereas carbon concentration and C:N ratios decreased in response to increasing nutrients. Nasturtium grows slowly in nutrient-poor conditions but rapidly increases its growth, biomass accrual, and nitrogen storage as conditions become nutrient-rich. The response of Nasturtium to enhanced nutrient conditions may indicate how aquatic nuisance species successfully invade and dominate plant communities in streams, where resources often vary both temporally and spatially.     

Growth and bioaccumulation characteristics of watercress (Nasturtium officinale R. BR.) exposed to cadmium,cobalt and chromium

Abstract

The aim of this study is to determine the effects of Cd, Co and Cr on the growth of watercress (Nasturtium officinale) and to determine the bioaccumulation properties of these heavy metals by the plant. N. officinale individuals were exposed to different concentrations of Cd, Co and Cr for 72 h. Relative growth rates (RGR) and bioconcentration factor (BCF) ratios were calculated for each metal concentration. RGR values of plants exposed to Co slightly increased in lower concentrations, but then decreased again. In contrast, RGR values of plants exposed to Cd and Cr decreased linearly. Significant positive relationships were observed among the concentrations of Cd, Co and Cr in N. officinale and in the culture solution. BCF ratios were highest for plants exposed to Co, and lowest for plants exposed to Cr. The most efficient uptake of Cd, Co and Cr occurred at the external solution concentrations at 0.5, 0.5 and 10 mM, respectively.     

The shredding activity of gammarids facilitates the processing of organic matter by the subterranean amphipod Niphargus rhenorhodanensis

1. The functional feeding group approach has been widely used to describe the community structure of benthic invertebrates in relation to organic matter resources. Based on this functional framework, positive interactions between feeding groups (especially shredders and collector‐gatherers) were postulated in the River Continuum Concept. However, relationships with organic matter have been poorly documented for invertebrates living in the hyporheic zone. 2. We hypothesised that the common subterranean amphipod Niphargus rhenorhodanensis would feed on fine particulate organic matter (FPOM), which is more abundant than coarse particulate organic matter (CPOM) in hyporheic habitats, and should be favoured by the occurrence of shredders that produce FPOM from CPOM. 3. We used laboratory experiments to quantify leaf litter processing by N. rhenorhodanensis and a common shredder, the surface amphipod Gammarus roeselii. We estimated rates of feeding and assimilation (using nitrogen stable isotopes) of the two species separately and together to reveal any potential shredder–collector facilitation between them. 4. Measured leaf litter mass loss showed that N. rhenorhodanensis did not act as a shredder, unlike G. roeselii. Organic matter dynamics and ¹⁵N/¹⁴N ratios in tissues of niphargids indicated that N. rhenorhodanensis was a collector‐gatherer feeding preferentially on FPOM. We also found a positive influence of the gammarid shredders on the assimilation rate of N. rhenorhodanensis, which fed on FPOM produced by the shredders, supporting the hypothesis of a positive interaction between surface shredders and hyporheic collector‐gatherers.     

Protective effect of Nasturtium officinale R. Br and quercetin against cyclophosphamide-induced hepatotoxicity in rats

Molecular Biology Reports - Cyclophosphamide (CPA) is used in the management of autoimmune conditions and malignant illnesses. However, its therapeutic use is limited because of its severe side...     

Auxin-like Growth Activity of 3-Phenylpropionitrile from Water-Cress (Nasturtium officinale R. Br.)

Solutions of 3-phenylpropionitrile (PPN) and 3-phenylpropionicacid (PPA) exhibited auxin-like plant growth activity by stimulatingelongation of sections cut from wheat coleoptiles and garden-cresshypocotyls. Elongation of sugar-beet hypocotyl sections wasstimulated by PPA but not by PPN. Although PPA stimulated elongationof pea-epicotyl sections after 19 h incubation, most concentrationsof PPN did not show activity until 70 h. PPN generally stimulatedadventitious root formation on hypocotyls of garden-cress andsugar-beet, and on epicotyls of pea seedlings whereas dilutesolutions of PPA were inactive and concentrated solutions weretoxic. Steam distillates of water-cress plants contained a substancewith auxin-like growth activity and chromatographic propertiessimilar to PPN. Nasturtium officinale R. Br. water-cress, 3-phenylpropionitrile, 3-phenylpropionic acid, auxins     

Assessment of salt tolerance of Nasturtium officinale R. Br. using physiological and biochemical parameters

Nasturtium officinale R. Br. seedlings were treated with a range of NaCl concentrations (0, 50, 100 and 150 mM) for 21 days after seedling emergence. Physiological analysis based on growth and mineral nutrition, showed a substantial decrease in leaf dry matter with 150 mM NaCl treatment. The growth decrease was correlated with nutritional imbalance and a reduction in potassium accumulation and transport to the leaves. At the same time, we noted an increase in leaf sodium and chloride accumulation and transport. Salt tolerance of N. officinale under 100 mM NaCl was associated with osmotic adjustment via Na⁺ and Cl^? and the maintenance of high K⁺/Na⁺ selectivity. Salt decreased carotenoid content more than chlorophylls and also disturbed membrane integrity by increasing malondialdehyde content and electrolyte leakage. At 150 mM NaCl, an increase in antioxidant enzyme-specific activities for superoxide dismutase, catalase and guaiacol peroxidase occurred in concert with a decrease in ascorbic acid, polyphenol, tannin and flavonoid content. These results indicate that N. officinale can maintain growth and natural antioxidant defense compounds such as, vitamin C, carotenoids, and polyphenols, when cultivated in 100 mM NaCl, but not at higher salt levels.     

Effects of oil on the amphipod Gammarus oceanicus

The effects of a number of oils (one crude and two refined products) were tested under various conditions on larvae and adults of the amphipod Gammarus oceanicus. Acute toxicity tests were performed, as well as long-term bioassays. Larvae were found to be several hundred times more sensitive to the oils than the adults during acute exposure. A number of sublethal effects appeared during long-term bioassays. The adults showed impaired swimming performance, decreased tendency to precopulate, impaired light reaction and decreased production of larvae. Decreased growth was found among larvae during chronic exposure to crude oil. Delayed mortality occurred among adults after a short-term exposure to crude oil with a long recovery period.     

Influence of NaCl on Productivity and Fluorescence Parameters of Nasturtium officinale R. Br. and Its Relevance to Artificial Closed Ecosystems

Russian Journal of Plant Physiology - Productivity values, sodium accumulation in aboveground biomass, and photosynthetic indices of watercress (Nasturtium officinale) leaves were investigated...     

Amphipod (Gammarus minus) responses to predators and predator impact on amphipod density

Recent theoretical work suggests that predator impact on local prey density will be the result of interactions between prey emigration responses to predators and predator consumption of prey. Whether prey increase or decrease their movement rates in response to predators will greatly influence the impact that predators have on prey density. In stream systems the type of predator, benthic versus water-column, is expected to influence whether prey increase or decrease their movement rates. Experiments were conducted to examine the response of amphipods (Gammarus minus) to benthic and water-column predators and to examine the interplay between amphipod response to predators and predator consumption of prey in determining prey density. Amphipods did not respond to nor were they consumed by the benthic predator. Thus, this predator had no impact on amphipod density. In contrast, amphipods did respond to two species of water-column predators (the predatory fish bluegills, Lepomis macrochirus, and striped shiners, Luxilus chrysocephalus) by decreasing their activity rates. This response led to similar positive effects on amphipod density at night by both species of predatory fish. However, striped shiners did not consume many amphipods, suggesting their impact on the whole amphipod “population” was zero. In contrast, bluegills consumed a significant number of amphipods, and thus had a negative impact on the amphipod “population”. These results lend support to theoretical work which suggests that prey behavioral responses to predators can mask the true impact that predators have on prey populations when experiments are conducted at small scales. Received: 21 March 1997 / Accepted: 15 December 1997     

The influence of light on the growth of watercress (<Emphasis Type="Italic">Nasturtium officinale</Emphasis> R. Br.)

In stream ecosystems, the growth of aquatic primary producers is affected by spatial and temporal variations in the riparian canopy, which can influence the availability of light resources. Aquatic plants can acclimate to low light environments by employing a suite of morphological or physiological mechanisms to increase light capture or photosynthetic efficiency. Some species may also use alternate types of propagules to colonize environments with heterogeneous light environments. In a greenhouse experiment we examined the morphological and physiological response of watercress (Nasturtium officinale R. Br.) to a gradient of increasing light levels, which ranged from 7% ambient light to full sunlight. We also determined if watercress seedlings and vegetative fragments differed in their growth response to increasing light levels. Total biomass and root biomass of seedlings and vegetative fragments decreased with decreasing light levels. The difference in plant biomass across treatments was due to morphological changes in total canopy area and leaf area, both of which increased with decreasing light levels. Seedlings and vegetative fragments did not differ in their response to light availability, but vegetative fragments had higher final biomass as a result of higher initial biomass. Physiological acclimation to low light levels appears to be of secondary importance for watercress as the concentrations of total chlorophyll, chlorophyll a, chlorophyll b, and chlorophyll a:b did not differ among light levels or between seedlings and vegetative fragments. Seedlings and vegetative fragments grown under high light levels had a greater percentage of carbon and a lower percentage of nitrogen than plants grown under low light conditions. The results of this study indicate that watercress displays considerable morphological plasticity and acclimates to low light conditions primarily by increasing leaf area and canopy surface area. There is no evidence that the type of watercress propagule (seedling vs. vegetative fragment) imparts any growth advantage in low light environments and watercress grown from either type of propagule showed no differences in their morphological or physiological responses to varying light regimes. Handling editor: S. M. Thomaz     

Biodegradation of C.I. Acid Blue 92 by Nasturtium officinale: Study of Some Physiological Responses and Metabolic Fate of Dye

The present study was conducted to evaluate the potential of aquatic vascular plant, Nasturtium officinale, for degradation of C.I. Acid Blue 92 (AB92). The effect of operational parameters such as initial dye concentration, plant biomass, pH, and temperature on the efficiency of biological decolorization process was determined. The reusability of the plant in long term repetitive operations confirmed the biological degradation process. The by-products formed during biodegradation process were identified by GC-MS technique. The effects of the dye on several plant physiological responses such as photosynthetic pigments content and antioxidant enzymes activity were investigated. The content of chlorophyll and carotenoids was significantly reduced at 20 mg/L of the dye. The activities of superoxide dismutase and peroxidase were remarkably increased in the plant root verifying their importance in plant tolerance to the dye contamination.     

温度对海洋底栖端足类日本大螯蜚(Grandi-dierella japonica)存活、生长和发育的影响

日本大螯蜚（ Ｇｒａｎｄｉｄｉｅｒｅｌｌａ ｊａｐ ｏｎｉｃａ）生长发育的适温范围为 ２０～２６℃。不同发育期耐受温度范围不同,刚孵化幼体温度下限为１１℃,上限为３２℃,以后随着幼体发育,其对低温的适应力逐渐增强。雄性个体对极限温度的忍耐力低于雌性。在耐受温度范围内,幼体的生长发育随着温度的提高而加快。研究结果表明,日本大螯蜚实验室培养温度宜选择在２０～２６℃,用其进行的沉积物急性和慢性毒性生物检验的实验温度均宜选择在 ２０℃。     

Effects of culture medium composition and PEG on hyperhydricity in Dendrobium officinale

Hyperhydricity is a physiological disorder during plant tissue culture that seriously affects regeneration and micropropagation. In this study, Dendrobium officinale plantlets were cultured on solid Murashige and Skoog (MS) medium supplemented with plant growth regulators and various concentrations of sucrose, agar, and polyethylene glycol (PEG)-6000 to explore the effect of osmotic stress on hyperhydricity. The results show that low concentrations of sucrose or agar, as well as PEG-6000 at various concentrations, significantly increase the hyperhydric rate of D. officinale, whereas high concentrations of sucrose or agar did not. Furthermore, high concentrations of PEG-6000 significantly increase total water content, free-water content, relative electrical conductivity, and peroxidase (POD) activity of D. officinale plantlets, whereas they significantly decrease bound-water content, proline content, soluble protein content, soluble sugar content, and superoxide dismutase (SOD) activity. These results indicate that PEG-6000 disrupts the antioxidant system and water metabolism in D. officinale plantlets, as well as increases cell membrane permeability, which might be the key factors for the occurrence of hyperhydricity in this species.

     

大黄蒽醌提取物对饲养建鲤生长的影响

将750尾建鲤(Cyprinus carpio var.jian)随机分成5组。一组为对照组,投喂基础日粮。另外4组为实验组,投喂的基础日粮中分别添加0.5%、1.0%、2.0%、4.0%大黄蒽醌提取物。连续投喂70d后,测定鱼的生长、免疫相关因子、肠道菌数量及肉质等。结果表明,与对照组相比,添加大黄蒽醌提取物提高了鱼体增重率、饲料转化效率、溶菌酶活性、一氧化氮浓度、超氧化物歧化酶活性,促进了肠道有益菌增加,抑制有害菌生长,降低了丙二醛含量及鱼体死亡率,但是与大黄蒽醌提取物的添加水平不成线性关系;其中1.0%实验组肝胰脏溶菌酶与超氧化物歧化酶活性最高,血清丙二醛含量最低;2.0%实验组增重率、血清一氧化氮浓度与超氧化物歧化酶活性、肝胰脏一氧化氮浓度、肠道乳酸杆菌数量最高;添加1.0%~2.0%大黄蒽醌提取物显著提高了肌肉粗脂肪含量。因此,添加1.0%~2.0%大黄蒽醌提取物能改善肠道的微生态平衡,提高机体免疫机能,改善肉质,促进鱼体生长。     

铁皮石斛和百令胶囊对老年SD大鼠肠道菌群的影响

目的 探讨铁皮石斛和百令胶囊对自然衰老SD大鼠肠道菌群组成和多样性的影响.方法 选取自然衰老SD雄性大鼠30只随机分为5组,分别为铁皮石斛高(400 mg/kg)、中(200 mg/kg)、低(100 mg/kg)剂量组及百令胶囊组(40 mg/kg)、空白对照组,每组6只,对各组大鼠连续灌胃8周.在灌胃结束后,取各组...     

Multiple density dependence in two sub-populations of the amphipod Monoporeia affinis: a potential for alternative equilibria

Possible mechanisms for differences in population densities and dynamics were investigated in the amphipod Monoporeia affinis at two deep sites in the northern Bothnian Sea. The two sites were sampled yearly for 10 years. Average sizes, growth and mortality of the different age-classes were estimated from the cohort structure of the two populations. Laboratory experiments also investigated the ability of the common predatory isopod Saduria entomon to cause densitydependent (DD) mortality of the prey M. affinis. At site A, 43 m depth, the average density of M. affinis was twice as high as at site B, 81 m depth. The fluctuations in density were asynchronous between the two sites. Recruitment and subadult sizes of Monoporeia affinis were density dependent at both sites. The main functional difference between the two populations seemed to be the DD mortality of the 1 + cohort that occurred only at the low-density site B. A corresponding DD mortality was found in the predation experiments at densities of 1 + m. affinis corresponding to those found at site B. The potential importance of the predator was also indicated by a significant negative correlation between the biomass of S. entomon and the rate of change in M. affinis density in the field. The similarities in the abiotic factors between the two sites suggested that differences in carrying capacity should be small. The results could be explained by the predation regulation hypothesis for the low-density population at site B, while at site A M. affinis seemed to be regulated by intra-specific competition and limited by predation. It is suggested that in this simple predator-prey system there is potential for the existence of alternative equilibria.