Isolation of Oscillatoria spongeliae,the filamentous cyanobacterial symbiont of the marine sponge Dysidea herbacea

The tropical marine sponge Dysidea herbacea (Keller) (Dictyoceratidae: Dysideidae) is always found associated with the filamentous cyanobacterium (blue-green alga) Oscillatoria spongeliae (Schulze) Hauck (Cyanophyceae: Oscillatoriaceae), which occurs abundantly throughout the sponge mesohyl. Intact, metabolically active, trichomes of O. spongeliae were isolated from the sponge by chopping the sponge tissue with a razor blade and squeezing the trichomes into a seawater-based medium containing polyvinylpyrrolidone, bovine serum albumin, dithiothreitol, glycerol, KCl and Na₂CO₃. The isolated cyanobacteria were concentrated by centrifugation and then washed several times in fresh medium. The isolated O. spongeliae have photosynthetic rates which are similar to the intact sponge-alga association for periods of at least 6 h after isolation. Addition of sponge homogenate to the isolated cyanobacteria causes rapid cell lysis.     

Host specificity of the symbiotic cyanobacterium<Emphasis Type="Italic"> Oscillatoria spongeliae</Emphasis> in marine sponges,<Emphasis Type="Italic"> Dysidea</Emphasis> spp.

Marine sponges can host a variety of cyanobacterial and bacterial symbionts, but it is often unclear whether these symbionts are generalists that occur in many host species or specialists that occur only in certain species or populations of sponges. The filamentous cyanobacterium Oscillatoria spongeliae is found in the sponges Dysidea n. sp. aff. herbacea 1A and 1B, and similar cyanobacteria are found in D. n. sp. aff. granulosa. We amplified and sequenced sponge nuclear ribosomal DNA (rDNA) and cyanobacterial 16S rDNA from specimens of these three sponges. We then used these sequences to construct phylogenies for host sponges and their symbiotic cyanobacteria. Each of these three sponge species hosts a distinct cyanobacterial clade, suggesting a high degree of host specificity and potential coevolution between symbiotic cyanobacteria and their host sponges.     

Filamentous cyanophytes containing phycourobilin and in symbiosis with sponges and an ascidian of coral reefs

A study was made of the ultrastructure and pigment composition of filamentous cyanophytes living in symbiosis with several sponges and a colonial didemnid ascidian collected from the southern end of the Great Barrier Reef, Australia, between 1983 and 1986. The sponges were Dysidea herbacea Keller and several other encrusting sponges which have not been identified; the ascidian was Trididemnum miniatum Kott (1977). The cyanophyte Oscillatoria spongeliae (Shultz) Hauck was identified as the symbiont of several of the sponges, including D. herbacea. Two other unidentified Oscillatoria species were found in a bristly papillate sponge and in T. miniatum. Chlorophyll a, alone, was present in all the symbionts with the exception of T. miniatum, which contained the cosymbiont Prochloron and where chlorophyll b was also present. Two phycoerythrins were isolated by chromatography and chromatofocusing. Both resembled C-phycoerythrin, but one of the two carried the chromophore phycourobilin as well as phycoerythrobilin possibly on both the and subunits, which had apparent molecular masses of 18 and 20 kdaltons. No subunit was present. Ultrastructurally, the three Oscillatoria species were distinguished by an unusual type of parallel, longitudinal, thylakoid organisation; the arrangement was different in detail in each species.     

A brominated secondary metabolite synthesized by the cyanobacterial symbiont of a marine sponge and accumulation of the crystalline metabolite in the sponge tissue

The dictyoceratid marine sponge Dysidea herbacea (Keller, 1889) is common in shallow waters of the tropical Pacific Ocean. Polybrominated biphenyl ethers such as 2-(2,4-dibromophenyl)-4,6-dibromophenol (1) are characteristic secondary metabolites of some specimens of this sponge and may represent as much as 12% of the dry weight. We have found 1 to be deposited as conspicuous crystals throughout the sponge tissue. The dominant prokaryotic endosymbiont in the mesohyl of the sponge is a filamentous cyanobacterium (Oscillatoria spongeliae), although a vacuole-containing, heterotrophic bacterium is also present. The cyanobacteria were separated from the sponge cells and heterotrophic bacteria by flow cytometry. Coupled gas chromatography—mass spectrometry and proton nuclear magnetic-resonance spectroscopy revealed that the major brominated Compound 1 isolated from the intact symbiotic association is found in the cyanobacteria and not in the sponge cells or heterotrophic bacteria. This suggests that the production of the compound is due to the cyanobacterium, and not to the sponge or symbiotic heterotrophic bacteria, as had been suggested earlier.     

Comparative electrophysiological analysis of plant odor perception in females of threePapilio species

Summary Antennae of femalePapilio butterflies perceive many volatile plant constituents with widely differing, constituent-specific sensitivities. We compared the responses of threePapilio species to volatiles from host and non-host plants to assess species-specificity and the degree of evolutionary conservatism in olfactory responses.Since previous studies had demonstrated that the polar constituents in odor fromDaucus carota stimulate oviposition behavior inPapilio polyxenes, we collected headspace volatiles fromD. carota, Pastinaca sativa (both Apiaceae) andArtemisia dracunculus (Asteraceae) and separated the polar fraction of these volatiles by gas chromatography. GC-coupled electroantennograms (GC-EAG) were recorded from the speciesPapilio polyxenes, P. machaon hippocrates andP. troilus. In addition, the responses of the three species to five compounds known as generally occurring constituents of plant odor were recorded. The relative sensitivities for these compounds were nearly identical in all threePapilio species. The response spectra to the separated plant volatiles also showed considerable similarities among the species.From the limited set of GC peaks evoking a response in one of the species, 64% (D. carota), 44% (P. sativa) and 29% (A. dracunculus) also evoked a response in both of the other species. The responses of the two closely related Apiaceae feeders (P. polyxenes, P. m. hippocrates) to volatiles fromD. carota were more similar to each other than was either to the response ofP. troilus, which feeds on Lauraceae. However, this was not true for the responses to volatiles fromP. sativa. The least congruence among the three species was found in the responses to volatiles fromA. dracunculus, a non-host for all of them. The differences and similarities found in the response profiles of the threePapilio species are discussed with respect to evolutionary adaptation to host odor versus evolutionary conservatism in adaptation of olfactory receptors.     

Sterol production and phytosterol bioconversion in two species of heterotrophic protists, Oxyrrhis marina and Gyrodinium dominans

The kinetics and efficiency of sterol production and bioconversion of phytosterols in two heterotrophic protists Oxyrrhis marina and Gyrodinium dominans were examined by feeding them two different algal species (Rhodomonas salina and Dunaliella tertiolecta) differing in sterol profiles. R. salina contains predominantly brassicasterol (≅99%) and <2% cholesterol. The major sterols in D. tertiolecta are ergosterol (45–49%), 7-dehydroporiferasterol (29–31%) and fungisterol (21–26%). O. marina fed R. salina metabolized dietary brassicasterol to produce 22-dehydrocholesterol and cholesterol. O. marina fed D. tertiolecta metabolized dietary sterols to produce cholesterol, 22-dehydrocholesterol, brassicasterol and stigmasterol. G. dominans fed either R. salina or D. tertiolecta metabolized dietary sterols to make cholesterol, brassicasterol and a series of unknown sterols. When protists were fed R. salina, which contains cholesterol, the levels of cholesterol were increased to a magnitude of nearly 5- to 30-fold at the phytoplankton-heterotrophic protist interface, equivalent to a production of 172.5 ± 16.2 and 987.7 ± 377.7 ng cholesterol per mg R. salina carbon consumed by O. marina and G. dominans, respectively. When protists were fed D. tertiolecta, which contains no cholesterol, a net production of cholesterol by the protists ranged from 123.2 ± 30.6 to 871.8 ± 130.8 ng per mg algal C consumed. Cholesterol is not only the dominant sterol, but a critical precursor for many physiologically functional biochemicals in higher animal. As intermediates, these heterotrophic protists increase the amount of cholesterol at the phytoplankton–zooplankton interface available to higher trophic levels relative to zooplankton feeding on algae directly.     

Photoinhibition of Symbiodinium spp. within the reef corals Montastraea faveolata and Porites astreoides: implications for coral bleaching

It is speculated that differences in coral bleaching susceptibility may be influenced by the genotype of in hospite Symbiodinium and their differential responses to bleaching stressors. Photoinhibition of photosystem II (PSII), damage to the D1 (psbA) PSII reaction centre protein and production of reactive oxygen species by in hospite Symbiodinium are likely precursors of coral bleaching. In order to assess whether photorepair rates of in hospite Symbiodinium underlie the bleaching susceptibility of their hosts, photoinhibition (net and gross), photoprotection and photorepair rates were assessed in a bleaching-‘tolerant’ coral (P. astreoides) and a bleaching-‘sensitive’ coral (M. faveolata) using non-invasive fluorometric techniques and by blocking de novo synthesis of psbA. Previous studies using such techniques have demonstrated that in vitro Symbiodinium types ‘sensitive’ to bleaching stressors had reduced rates of photorepair relative to ‘tolerant’ Symbiodinum types. Our measurements demonstrated that Symbiodinium in the more bleaching tolerant P. astreoides had higher photorepair rates than Symbiodinium in M. faveolata. Higher repair rates in P. astreoides resulted in lower net photoinhibition relative to M. faveolata, where both corals exhibited similar susceptibility to photodamage (gross photoinhibition). Photoprotective mechanisms were observed in both corals; M. faveolata exhibited higher antennae-bed quenching than P. astreoides at low-light intensities, but at and above light-saturating intensities, which are different for each coral species, P. astreoides displayed more efficient non-photochemical quenching (Stern–Volmer quenching) of chlorophyll fluorescence than M. faveolata. Increased NPQ by P. astreoides at E/E _k ≥ 1 was not driven by antennae-bed quenching. The ability of in hospite Symbiodinium in P. astreoides to mitigate the effects of photoinhibition under high light conditions compared with Symbiodinium in M. faveolata, and their high repair capacity following photoinhibition, may be a key factor to consider in future bleaching studies and may underlie the relative bleaching tolerance of P. astreoides compared to M. faveolata.     

The sex pheromone of the grain aphid,Sitobion avenae (Fab.) (Homoptera,Aphididae)

Summary The sex pheromone of the grain aphid,Sitobion avenae (Fab.), is identified as (4aS,7S,7aR)-nepetalactone, for which specific olfactory cells are located in the secondary rhinaria of the male antenna. The related (1R,4aS,7S,7aR)-nepetalactol was not produced by females in significant amounts (ca 10,000-fold less than the nepetalactone), although cells in the male antenna were found that responded specifically to this compound. Behavioural activity in the linear track ol-factometer showed attraction of males to the nepetalactone, but not to the nepetalactol.     

Distribution,fate and persistence of organochlorine compounds formed during production of bleached pulp

The processes governing distribution of a xenobiotic compound discharged initially into the environment are discussed, and attention is drawn to (a) binding to organic matter in the sediment phase which affects both persistence and toxicity to biota and (b) the role of atmospheric transport for compounds of low water solubility and high vapour pressure. Important limitations in the use of sum parameters such as EOCI are pointed out. The important distinction between biodegradation and biotransformation is pointed out, and significant experimental determinants noted. Pathways for the aerobic metabolism of chlorophenolic compounds are discussed, and attention is drawn to the role of O‐methylation as an environmentally significant alternative to biodegradation. Evidence for the biodegradation of chlorinated aliphatic acids and hydrocarbons under both aerobic and anaerobic conditions is presented. Anaerobic metabolism of chlorophenolic compounds is discussed with respect to (a) de‐O‐methylation of chloroguaiacols, (b) dechlorination of chlorocatechols and (c) reduction of chlorovanillins. It is emphasized that current evidence provides a complex metabolic picture, and that only partial dechlorination may occur. Brief attention is given to the important issue of the persistence of chlorolignin, and attention drawn to technical issues which render this problem difficult of access by traditional procedures. Biohalogenation—particularly by fungi—is noted, though its quantitative contribution cannot be estimated at the moment. A number of important unresolved issues are underscored: (a) the problem of determining rates of microbial reactions which may be translated to environmental situations, (b) the cardinal role not only of the number of chlorine atoms in an aromatic compound but also the substitution pattern and (c) limitations in current understanding of the role of anaerobic bacteria in bringing about biodegradation and biotransformation.     

Chemopreventive effects of ellagic acid against genotoxicity induced by benzo(a)pyrene

Benzo(a)pyrene (B(a)P) is a commonly used indicator for polycyclic aromatic hydrocarbons (PAHs) contamination. The use of certain phytochemicals and some polyphenolic compounds proved to be effective in blocking PAH-induced effects. The aim of the present study was to examine the possible inhibitory effects of ellagic acid (EA), present in berries and nuts, against B(a)P-mediated toxicity using in vitro and in vivo test systems. In vitro method included the Ames test, using Salmonella typhimurium tester strain TA100. In vivo experiments were based on mouse bone marrow micronucleus (MN) assay and immunoblotting. EA produced a decrease in the number of revertant colonies against B(a)P in the Ames assay. Further, there was a reduction in the mean number of micronucleated polychromatic erythrocytes in the presence of EA in the co-treatment protocol of the MN test. Western blotting results showed downregulation of CYP450 isoform CYP1A1 which prevented bioactivation of B(a)P. Thus, the present study demonstrates antimutagenic role played by EA against the mutagenic activity of B(a)P in both in vitro and in vivo systems.     

Attraction of field-flying aphid males to synthetic sex pheromone

Summary Transparent plastic water traps, baited with the synthetic aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol or control lures, were placed in four semi-sheltered field sites at a height of 1.1 m. Although males of twenty-one aphid species were collected from the water traps, onlySitobion fragariae (Walker) was abundant. In total, 8 pheromone traps produced 102 males compared with only 10 males in 8 control traps. The sex pheromone released by sexual femaleS. fragariae was identified as the nepetalactone used in the lures. Aphid sex pheromones may be more species-specific than previously thought and the presence of a host plant is not essential for males to locate sexual females.     

Differences in productivities between the Great Australian Bight and the Gulf of Carpentaria,Australia, in summer

Phytoplankton standing crop (chlorophyll a) and primary productivity were recorded, and zooplankton biomass was estimated in the two large bays of Australia, the Great Australian Bight on the south coast (December, 1965) and the Gulf of Carpentaria on the north coast (December, 1968). In the Gulf of Carpentaria, the phytoplankton standing crop (average, 27.3 mg chlorophyll a m^-2) and primary productivity (average, 133.1 mg C m^-2 h^-1), as well as zooplankton biomass (average, 305.3 mg wet weight m^-3) are much higher than in the Great Australian Bight (12.1 mg chlorophyll a m^-2, 18.2 mg C m^-2 h^-1, 7.1 mg wet weight m^-3, respectively). The unexpectedly low productivity values in the Great Australian Bight are attributable to environmental conditions of this bay, which obtains neither replenishment of nutrients from the land nor receives upwelling of deep water.     

Sequestration of plant pyrrolizidine alkaloids by chrysomelid beetles and selective transfer into the defensive secretions

Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.     

镉胁迫对脊尾白虾的毒性效应研究

为揭示重金属镉对脊尾白虾的毒性效应,采用急性毒性实验方法,研究了不同浓度镉(Cd~(2+))对脊尾白虾(Exopalaemon carinicauda)血清氧化应激相关生理指标的活性以及肌肉组织中腺苷酸转移酶基因(ANT)和热激蛋白70基因(HSC70)表达水平的影响。共设置4个Cd2+浓度胁迫(0、0.0002、0.001、0.005 mmol·L~(-1)),分别在0、3、6、9、12、24、36、48、72和96 h共10个时间点对相关指标进行测定。结果显示:不同浓度镉胁迫下,脊尾白虾血清中H_2O_2含量、MDA含量和GSH含量均表现为先升高后降低的趋势,H2O2含量在胁迫3 h时即出现明显的升高,而MDA和GSH则均在9 h时出现升高趋势,表现为一定的滞后性。H2O2含量在0.005 mmol·L~(-1)胁迫3 h时出现峰值,MDA含量在0.005 mmol·L~(-1)胁迫9 h时出现峰值,GSH含量在0.001mmol·L~(-1)胁迫48 h时出现峰值,且均与对照组存在显著性差异(P0.05)。HSC70基因的表达量在不同浓度胁迫下均表现为先升高后降低的趋势,且均在24 h时达到峰值,具体表达量水平的顺序为:0.0002 mmol·L~(-1)0.001 mmol·L~(-1)0.005 mmol·L~(-1)。ANT基因的表达量在不同浓度下则均表现为明显的下调趋势。由此可见,急性Cd~(2+)胁迫不仅影响脊尾白虾的氧化应激相关生理指标,还影响机体内组成型HSC70及与能量传递有关的ANT基因的表达水平。     

取代苯酚类化合物抑藻活性的CoMFA模型

基于比较分子力场分析(CoMFA)方法建立20种取代苯酚类化合物抑藻活性(pI)的三维定量构效关系(3D-QSAR)。训练集中16个化合物用于建立预测模型,测试集5个化合物(含模板分子)作为模型验证。已建立的Co MFA模型的交叉验证系数(Q2)、非交叉验证系数(R2)分别为0.915、0.963,说明所建模型具有较强的稳定性和良好的预测能力。该模型中立体场、静电场贡献率依次为48.4%、51.6%,表明影响抑藻活性(pI)的主要因素是取代基的电荷分布,其次是取代基的疏水性和空间位阻。     

Diel changes in phytoplankton photosynthetic efficiency in Brackish waters

From 18 to 23 September 1974, investigations on the diel changes in phytoplankton were carried out in the Baltic Sea. Every 4 h, water samples were collected from 2 and 15 m, and PO₄, chlorophyll a, temperature, salinity, pH, phytoplankton composition and phytoplankton light photosynthesis relationship were determined. Continuous measurements of surface irradiance and some estimations of zooplankton were also made. P ^B (photosynthesis per unit chlorophyll a at low light levels of 2·10^-2 cal cm^-2 min^-1) revealed only random variation during the sampling period, i.e., 1.0 to 1.6 mg C (mg chlorophyll a)^-1 h^-1. P _m ^B (Light-saturated photosynthesis per unit of chlorophyll a) displayed pronounced diel fluctuations with the highest value of about 6 mg C (mg chlorophyll a)^-1 h^-1 around noon, and the lowest value of about 2.5 mg C (mg chlorophyll a)^-1 h^-1 during the night, during which latter period the value of P _m ^B was more or less constant. Reasons for the diel fluctuations are discussed, and an equation which describes these fluctuations is proposed. Using this equation, the daily phytoplankton production estimated in incubators by a previously described method can be corrected for the time of day at which samples are collected.     

立方体和八面体微/纳米氧化亚铜对大型水蚤(Daphnia magna)的氧化胁迫和生理损伤

为了实现特定的功能和应用,越来越多不同结构特性的纳米材料逐渐被人们精确合成。一些研究指出纳米材料的物理化学特性能够显著影响纳米材料对水生生物的毒性作用,但是对于不同特性的纳米氧化亚铜的毒性研究依然比较缺乏。本研究制备了2种不同形貌和结构的微/纳米氧化亚铜(micro/nano-Cu_2O)晶体,通过对大型水蚤(Daphnia magna)进行72 h的急性暴露实验,测定了大型水蚤体内还原型谷胱甘肽(GSH)的含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和钠/钾腺苷三磷酸酶(Na+/K+-ATPase)的活性变化。结果表明在2种不同特性的微/纳米氧化亚铜暴露体系中,大型水蚤体内Cu的积累量差别不大,但是不同结构的micro/nano-Cu_2O对大型水蚤抗氧化酶活性和钠/钾腺苷三磷酸酶活性影响存在差别。与立方体相比,八面体micro/nano-Cu_2O能够暴露更多的{111}面,并且其原子排列使其具有较高的表面能量,因此更容易在大型水蚤肠道内诱导产生活性氧(ROS)及溶出更多Cu2+,对大型水蚤产生更强的氧化胁迫和膜损伤。     

铜锈环棱螺室内实验条件优化

铜锈环棱螺作为一种新兴的潜在生态毒理学模式生物,适宜实验条件是开展其室内毒理学研究的基础。在人为控制条件下,初步探讨了饵料、水深、底质、密度和钙离子浓度养殖条件对铜锈环棱螺成体生长的影响,并进一步对麻醉条件进行了筛选(Mg Cl2·2H2O、乙醇、丁香酚、盐酸普鲁卡因和MS-222)。结果表明:当投喂冰鲜小球藻、密度6个·L-1水体积、水深10~15cm、泥土底质并且水中钙离子浓度30 mg·L-1时,铜锈环棱螺的体重增长最为明显。麻醉效果表明,Mg Cl2·2H2O对成螺的麻醉时间短并且伤害小,可作为实验用麻醉剂首选。以上研究结果为发展以铜锈环棱螺为模式生物开展环境(生态)毒理学研究奠定了基础。     

Structure of pathways in ecological networks: relationships between length and number

In ecosystems network, structure determines adjacent (direct) and non-adjacent (indirect) pathways over which energy, matter, and information can flow. The more pathways, the more possible ways the conservative substance can move in zero-sum transactions between network nodes that the pathways interconnect, and the more possible non-conservative, nonzero-sum relations can be secondarily derived from these. Structural analysis is a tool we employ, from a family of input–output methods for exploring zero- and nonzero-sum attributes of environmental networks, to count pathways of varying length between network nodes. In this paper, we examine the relationship between pathway length (k) and number (P_k) as determined by system size (n, number of nodes) and extent and pattern of connectance (C). We develop a measure (m_a) of pathway growth in numbers with increasing length, and then normalize this to the maximum rate possible (m_a/m_c) for a given system size. These measures apply to two pathway types—paths, m_a(0) and m_a(0)/m_c(0), which forbid adjacent node repetitions, and walks, m_a(1) and m_a(1)/m_c(1), which allow them. We find that network size has a curvilinear effect on the pathway number versus length relationship, and extent and pattern of connectance are convolved. Values computed for the paths and walks of three ecosystem models (oyster reef, freshwater marsh, and reservoir cove) are used to compare their pathway structure.     

黑斑蛙与非洲爪蟾蝌蚪急性毒性试验方法敏感性的比较

两栖动物蝌蚪急性毒性试验是评价化学品急性毒性的一种方法。以毒死蜱、乙草胺、重铬酸钾和全氟辛烷磺酸盐(PFOS)为测试物,比较了我国本土黑斑蛙(Rana nigromaculata)与国际通用种非洲爪蟾(Xenopus laevis)在蝌蚪急性毒性试验中的敏感性。结果发现：2类蝌蚪分别进行的11次试验中,空白对照组黑斑蛙蝌蚪死亡率(0.9%)远低于非洲爪蟾蝌蚪的死亡率(5.8%);重铬酸钾和PFOS对黑斑蛙蝌蚪的96 h-LC₅₀分别为34.0 mg·L^-1和81.0 mg·L^-1,而对非洲爪蟾蝌蚪的96 h-LC₅₀分别为51.6 mg·L^-1和92.1 mg·L^-1,显示黑斑蛙蝌蚪对这2种化学品的敏感性略高于非洲爪蟾蝌蚪;毒死蜱和乙草胺对黑斑蛙蝌蚪的96 h-LC₅₀分别为0.41 mg·L^-1和4.1 mg·L^-1,而对非洲爪蟾蝌蚪的96 h-LC₅₀分别为0.12 mg·L^-1和3.1 mg·L^-1,显示黑斑蛙蝌蚪对这2种化学品的敏感性略低于非洲爪蟾。鉴于2类蝌蚪对化学品的敏感性存在差异,且黑斑蛙蝌蚪的自然死亡率低,材料更易获得,笔者认为黑斑蛙蝌蚪比非洲爪蟾更适合作为蝌蚪急性毒性试验的材料,用于我国化学品环境管理中的毒性评价。