首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.

Background

Acute toxicity testing were carried out the freshwater swamp shrimp, Macrobrachium nipponense, as the model animal for the semiconductor applied metals (gallium, antimony, indium, cadmium, and copper) to evaluate if the species is an suitable experimental animal of pollution in aquatic ecosystem.

Results

The static renewal test method of acute lethal concentrations determination was used, and water temperature was maintained at 24.0 ± 0.5°C. Data of individual metal obtained from acute toxicity tests were determined using probit analysis method. The median lethal concentration (96-h LC50) of gallium, antimony, indium, cadmium, and copper for M. nipponense were estimated as 2.7742, 1.9626, 6.8938, 0.0539, and 0.0313 mg/L, respectively.

Conclusions

Comparing the toxicity tolerance of M. nipponense with other species which exposed to these metals, it is obviously that the M. nipponense is more sensitive than that of various other aquatic animals.  相似文献   

2.
Tenuazonic acid (TA) is a phytotoxin produced by a fungal pathogen of rice, Pyricularia oryzae. We have synthesized and characterized the metal complexes of TA with copper (II), iron (III), nickel (II), and magnesium (II). The stoichiometry of the complexes determined by microanalysis and mass spectroscopy (D/CI) are Cu(II)TA2, Fe(III)TA3, Ni(II)TA2, and Mg(TA)2. Voltammograms of Fe(III)TA3, and Cu(II)TA2 in methanolic solutions confirmed this stoichiometry. Ni(II)TA2 paramagnetism and visible absorption data suggest an octahedral geometry. Fe(III)TA3 showed a characteristic visible absorption at 450 nm. Addition of Fe(III)Cl3 and Mg(II)Cl2 did not reverse the toxicity of NaTA to rice and bacterial cells, showing that this toxicity is not due to the privation of the cells of these metals essential for cell growth.  相似文献   

3.
Engel MS 《ZooKeys》2011,(148):171-184
Forty-eight family-group names are identified for insects among the Isoptera (termites), representing a nearly 19% increase since the last compilation less than 10 years ago. Accordingly, these names are newly catalogued, including various updates from the original summary. The name Reticulitermitidae is recognized as a nomen nudum while Caatingatermitinae is newly considered a nomen invalidum, and neither is available in zoological nomenclature. A catalogue of the suprafamilial names for Isoptera is appended. The name Xylophagodea is formally proposed for the Isoptera + Cryptocercidae clade.  相似文献   

4.
5.
The compound 4,7-diphenyl-1,10-phenanthrolinedisulfonic acid (BPDS) has been found to be very useful in studying Fe uptake by plants, because it forms a large charged complex that is not absorbed. The quantity of BPDS bound to metals in hydroponic solutions can be estimated from calculations using formation constants of BPDS complexes. These formation constants were used in an earlier experiment to predict the availability of Cu to corn plants. In the experiment, bioassays indicated that Cu was not as phytoavailable in the BPDS-added solutions as predicted by chemical equilibrium calculations. To determine sources of error in this prediction, metal and proton BPDS formation constants were reevaluated at 25 degrees C and 0.10M ionic strength. The CaBPDS formation constant was determined by direct measurement of CaBPDS3 formation and was shown to be approximately 1.0; a value much less than that reported before. Formation constants for the HBPDS, H(BPDS)2, and H(BPDS)3 beta 1, beta 2, and beta 3 complexes were, respectively, 5.05 +/- 0.044, 7.44 +/- 0.019, and 9.33 +/- 0.28. The BPDS sulfonic acid group pKs were less than 1.0, not 2.8 as has been reported. The FeBPDS3 complex determined by ligand competition with EDTA (ethylenediaminetetraacetate) was 20.24 +/- 0.08. Copper and Zn constants were determined using the method of corresponding solutions. The CuBPDS, CuBPDS2, and CuBPDS3 beta 1, beta 2, and beta 3 constants were, respectively, 9.76 +/- 0.08, 15.9, and 20.9. The ZnBPDS, ZnBPDS2, and ZnBPDS3 beta 1, beta 2, and beta 3 constants were, respectively, 6.43 +/- 0.07, 10.7 +/- 5.4, and 17.3 +/- 0.8. Results indicated that BPDS affinity to metals was similar to that of its parent compound, phenanthroline, and that errors in published formation constants caused erroneous predictions of Cu phytoavailability used in an earlier experiment.  相似文献   

6.
5-Hydroxymethylcytosine (5-hmC) generated by ten-eleven translocation 1–3 (TET1–3) enzymes is an epigenetic mark present in many tissues with different degrees of abundance. IL-1β and TNF-α are the two major cytokines present in arthritic joints that modulate the expression of many genes associated with cartilage degradation in osteoarthritis. In the present study, we investigated the global 5-hmC content, the effects of IL-1β and TNF-α on 5-hmC content, and the expression and activity of TETs and isocitrate dehydrogenases in primary human chondrocytes. The global 5-hmC content was found to be ∼0.1% of the total genome. There was a significant decrease in the levels of 5-hmC and the TET enzyme activity upon treatment of chondrocytes with IL-1β alone or in combination with TNF-α. We observed a dramatic (10–20-fold) decrease in the levels of TET1 mRNA expression and a small increase (2–3-fold) in TET3 expression in chondrocytes stimulated with IL-1β and TNF-α. IL-1β and TNF-α significantly suppressed the activity and expression of IDHs, which correlated with the reduced α-ketoglutarate levels. Whole genome profiling showed an erasure effect of IL-1β and TNF-α, resulting in a significant decrease in hydroxymethylation in a myriad of genes including many genes that are important in chondrocyte physiology. Our data demonstrate that DNA hydroxymethylation is modulated by pro-inflammatory cytokines via suppression of the cytosine hydroxymethylation machinery. These data point to new mechanisms of epigenetic control of gene expression by pro-inflammatory cytokines in human chondrocytes.  相似文献   

7.
 Aquatic plants are well known for their high degree of phenotypic plasticity in vegetative structures, particularly leaves. Less well understood is the extent to which their sexuality can be modified by environmental conditions. Here we investigate gender plasticity in the European clonal monoecious aquatic Sagittaria sagittifolia (Alismataceae) to determine how floral sex ratios may vary with plant size and inflorescence order. We sampled two populations from aquatic habitats in East Anglia, U.K. and measured a range of plant attributes including ramet size and the number of female and male flowers per inflorescence. The two populations exhibited similar patterns of phenotypic gender, despite contrasting patterns of total allocation to female and male flower number. Plants produced male-biased floral sex ratios but female flower number increased from the first to the second inflorescence whereas male flower number decreased. Size-dependent gender modification occurred in both populations, but the patterns of allocation to female flower production differed between the two populations. Our results are consistent with the view that monoecy is a sexual strategy that enables plants to adjust female and male allocation in response to changing environmental conditions. Received September 16, 2002; accepted October 23, 2002 Published online: March 20, 2003  相似文献   

8.
Ferris CD  Schmidt BC 《ZooKeys》2011,(149):31-37
Comparison of the types of Ixala klotsi (Sperry) and Pterospoda nigrescens (Hulst) shows that they are the same species, with Ixala klotsi a synonym of Pterospoda nigrescens. A lectotype of Selidosema nigrescens is designated, and the types of Selidosema nigrescens and Ixala klotsi are illustrated. Male and female habitus and genitalia of Pterospoda nigrescens are illustrated.  相似文献   

9.
A series of ternary complexes between adenosine 5′-triphosphoric acid (ATP), 2, 2′-bipyridyl, and the transition metal ions manganese(II), cobalt(II), copper(II), and zinc(II) in the ratio 1:1:1 have been prepared. The solid compounds are crystalline and can be formulated as [M(II)-H2ATP-2, 2′-Bipyridyl]2·4H2O (MATPbipy).X-ray powder patterns show them to be all isomorphous. Potentiometric titrations in aqueous solutions are in agreement with the presence of two ionizable protons. Ultraviolet and visible spectra, epr, and magnetic susceptibility measurements suggest that the metal ions have a high-spin distorted octahedral coordination. From infrared spectra it can be deduced that ATP coordinates to the metal only through the oxygen atoms of the phosphate groups.These compounds, which are particularly stable towards hydrolysis, form possible models for ATP transport in biological fluids.  相似文献   

10.
 The pollination biology of Musella lasiocarpa (Franch.) C. Y. Wu ex H. W. Li, a monotypic genus in the banana family (Musaceae) endemic to southwestern China, was investigated. Floral phenology, nectar production, and flower visitors were observed, measured, and recorded. Bagging experiments and comparative breeding system studies were carried out at different study sites and in different seasons. Our results revealed four important aspects of the reproductive biology of Musella. 1) This species blooms year round, but most flowering is concentrated from February to August. The longevity of female flowers is greater than that of male flowers and opening of both types of flowers occurs at anytime during the day, but is concentrated in the morning. 2) Although nectar is produced uniformly while flowers are open, the nectar volume and rate of female flowers are significantly higher than that of male flowers. 3) Insects, such as bumblebees (Bombus eximius and B. montivolans), honeybees (Apis cerana and A. florea), and wasps (Vespa mandarinia) are the primary floral visitors and show a preference for female flowers. 4) Both fruit and seed set are pollinator-limited at both study sites. A comparison of the floral biology and pollination characteristics among the three genera in the banana family suggests that insect pollination has played an important role in the reproductive isolation and breeding system evolution of Musella. Received February 14, 2002; accepted March 26, 2002 Published online: November 22, 2002 Addresses of authors: Aizhong Liu, W. John Kress (correspondence, e-mail: kress.john@nmnh.si.edu), Botany, MRC-166, United States National Herbarium, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington DC 20013-7012, USA. Hong Wang, De-Zhu Li (dzl@public.km.yn.cn), Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China.  相似文献   

11.
Frankliniella occidentalis, a serious pest of agricultural crops, is difficult to manage because chemical and biological control measures frequently fail to affect F. occidentalis in their preferred microhabitats. Parasitism by the host-specific, entomopathogenic nematode Thripinema nicklewoodi may provide a much-needed alternative to current control strategies. Infection does not cause death of the host; rather, the result is sterilization that leads to suppression of F. occidentalis populations. We describe a simple rearing method and the results from studies aimed at providing details on its biology-both essential first steps to examining its biological control potential. All F. occidentalis life stages are susceptible to infection, but to varying degrees (most susceptible to least susceptible): female pupae, second instar larvae, first instar larvae, male pupae, adult females, adult males. Nematodes emerge from female and male F. occidentalis for approximately 15 and 9 days, with approximately 14 and 7 nematodes emerging per day, respectively. Females and males are short-lived outside of the host, with mean survival rates ranging between 7 and 86 hours. Transmission does not occur in the soil but rather on or within plant structures that are preferred microhabitats visited by F. occidentalis. Results from a dose-response study suggest that augmentative applications of T. nicklewoodi may be useful to generate increased infection rates and subsequent suppression of F. occidentalis populations.  相似文献   

12.
13.
报道了中国兰科植物一新记录种,即无量山石豆兰(Bulbophyllum pinicola)。对其进行了特征描述并与相似种Bulbophyllum acutiflorum做了对比,并提供了彩色照片。无量山石豆兰的萼片披针形,先端渐尖,花瓣三角状披针形,先端渐尖,唇瓣稍向外下弯而易与相似种区分。  相似文献   

14.
Meloidogyne morocciensis n. sp. is described from specimens parasitic on peach rootstock from Morocco. This species exhibits a combination of morphological characters similar to M. arenaria, M. incognita, and M. javanica. The perineal pattern of females is oval to squarish with a moderately high to high dorsal arch, and widely spaced, smooth striae; lateral lines are absent. The stylet, 16.5 μm long, has transversely ovoid, set-off knobs. Males have a set-off, annulated head region. The large, rounded labial disc is distinctly demarcated from the crescent-shaped medial lips; lateral lips are absent. The robust stylet, 24.6 μm long, has large, rounded knobs that taper slightly posteriorly. Mean second-stage juvenile (J2) length is 401 μm. The set-offhead region has incomplete annulations; the lip structures are dumbbell shaped. The stylet, 12.3 μm long, has rounded knobs that slope posteriorly. The J2 tail, 52.6 μm long, has irregularly sized annules in the posterior region and ends in a bluntly rounded tip. Tomato, tobacco, pepper, and watermelon are good hosts; cotton and peanut are not hosts. Meloidogyne morocciensis n. sp. reproduces by mitotic parthenogenesis and has a somatic chromosome number of 47-49. Its esterase phenotype is identical with the three-banded phenotype (A3) of M. arenaria.  相似文献   

15.
16.
黄翠莹  孟开开  郭剑强  陈昉  廖文波  凡强 《广西植物》2020,40(10):1429-1437
该文报道了在广东丹霞山发现的报春苣苔属一新种——黄进报春苣苔(Primulina huangjiniana),并对其进行了描述。该新种与同属物种短序报春苣苔(P. depressa)最为相似,但两者在形态特征上能够很好地区别:黄进报春苣苔具有更短的、长2.5~6 mm的苞片(vs. 短序报春苣苔具有长15~30 mm的苞片,顺序下同); 花萼裂片等长(vs. 不等长),花丝基部附近膝状突起,中部以上具腺毛(vs. 于中部膝状突起且无毛); 柱头倒三角形,深2裂成2线形裂片(vs. 片状,稍2浅裂,裂片为三角形),侧膜胎座(vs. 中轴胎座)。加上该新种在内,丹霞山目前共记录有6种报春苣苔属植物,其中丹霞小花苣苔(P. danxiaensis)和该新种均为丹霞地貌特有植物。黄进报春苣苔目前在丹霞山的两个地方有发现,成年植株不超过200株,根据IUCN红色名录标准,属于极危种。  相似文献   

17.
贾泽峰  李健  杨梦竹 《广西植物》2017,37(2):231-233
该文报道了文字衣科(Graphidaceae)地衣一广西新记录属——炭刺文衣属(Carbacanthographis).该属主要特征是子囊盘面闭合,果壳炭化,盘唇具白色粉霜层,类缘丝具疣,子囊孢子砖壁型或横隔双透镜型,I-或微I+.枯炭刺文衣,标本采自广西金秀圣堂山,该种特征是线盘明显、盘被两侧炭化、子囊孢子无色砖壁型、孢子大小(12.5-20)×(5-7.5)μm、地衣体含有水杨嗪酸.该属是中国稀有属,迄今仅有1种报道.该种首次在内陆自然环境中发现,这对于炭刺文衣属及其类群的区系研究、物种保护和利用具有很重要的意义.  相似文献   

18.
The DEG/ENaC gene family of ion channels is characterized by a high degree of structural similarity and an equally high degree of diversity concerning the physiological function. In humans and rodents, the DEG/ENaC family comprises 2 main subgroups: the subunits of the epithelial Na+ channel (ENaC) and the subunits of the acid sensing ion channels (ASICs). The bile acid-sensitive channel (BASIC), previously known as BLINaC or INaC, represents a third subgroup within the DEG/ENaC family. Although BASIC was identified more than a decade ago, very little is known about its physiological function. Recent progress in the characterization of this neglected member of the DEG/ENaC family, which is summarized in this focused review, includes the discovery of surprising species differences, its pharmacological characterization, and the identification of bile acids as putative natural activators.  相似文献   

19.
 The structure of and the calcium distribution in the ovary-ovule transmitting tracts of Crocus were examined by using conventional and antimonate fixation methods for electron microscopy, and fluorescence microscopy as well. The ovarian locules are bordered with epidermal cells and transmitting cells. The epidermal cells are extensively cutinized, and the cytoplasm is rich in the organelles and vesicles prevalently engaged in thickening the exposed wall. The transmitting cells have uncutinized walls with numerous labyrinthine ingrowths, and the cytoplasm is rich in organelles and vesicles engaged in the secretion of the extracellular matrix (e.m.). The micropylar tissue of the ovule consists of largely vacuolated cells with scarcely structured cytoplasm, the e.m. appears to be of gametophytic origin. Both the ovary and ovule e.m. have a glycosidic and proteinic nature, and are rich in loosely bound Ca2+ ions. In the embryo sac, Ca2+ ions are concentrated in one synergid. The results are discussed in relation to the guided growth of pollen tubes. Received April 9, 2002; accepted July 9, 2002 Published online: November 28, 2002 Addresses of the authors: Giuseppe Chichiriccò (e-mail: Chichiri@univaq.it), Dipartimento di Scienze Ambientali, University of L'Aquila, Via Vetoio, I-67100 L'Aquila, Italy. Anna Maria Ragnelli, Pierpaolo Aimola, Dipartimento di Biologia di Base ed Applicata, University of L'Aquila, Via Vetoio, I-67100 L'Aquila, Italy.  相似文献   

20.
在室内研究了不同环境变量(如食物、温度、光周期和不同光波长)下银胶菊杂草Parthenium hysterophorus L.的食叶昆虫和生物防治因子银胶菊叶甲Zygogramma bicolorata Pallister 的生命表。不同发育阶段的该种叶甲取食银胶菊不同部位时,取食花的甲虫死亡率指标Kappa值最低,其次是取食叶片和茎;而取食花时甲虫世代存活率最高。温度显著影响主要发育阶段该种叶甲的死亡率和存活率。27℃下饲养的未成熟期甲虫的Kappa值最低,其次是30, 25, 20 和35℃。世代存活和存活率表现相同的趋势。不同光周期显著影响死亡率,在14L∶10D (长日照)下世代存活最好,其次是 12L∶12D (昼夜相等), 10L∶14D (短日照), 24L∶0D (连续光照) 和0L∶24D (连续黑暗)。甲虫对不同波长光的反应上,在白光(广谱)下Kappa值最低,世代存活率最高,其次是黄光(λ≈570 nm)、蓝光 (λ≈475 nm) 和红光(λ≈650 nm)。卵的死亡率最高。不同发育阶段的甲虫在27℃长日照白光下用银胶菊花饲养最佳。死亡率趋势具有严格和显著的阶段特异性,表现出内在的存活效应,与研究的因素无关。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号