液质联用技术评估汞接触污染蟾蜍泌酥中蟾蜍甾烯水平

目的:运用液质联用技术研究重金属汞皮肤接触中华大蟾蜍后生理状态及泌酥中蟾蜍甾烯水平变化,为中药蟾酥品质评价提供参考。方法:配制不同质量浓度的氯化汞溶液(0.5,0.75,1.0 g·L~(-1))对蟾蜍进行半静水式处理,观察其生理状态,且在30 d后收集蟾蜍耳后腺分泌液,进一步采用液相-质谱联用技术测定蟾蜍泌酥中游离型蟾蜍甾烯的水平,结合Hem I热图软件进行数据分析。结果:氯化汞接触明显影响蟾蜍泌酥中蟾蜍甾烯水平,和正常组比较,低质量浓度(0.5 g·L~(-1))汞污染组有20种蟾蜍甾烯水平明显上调,其中有12个物质发生1.5倍变化。而中质量浓度(0.75 g·L~(-1)),高质量浓度(1.0 g·L~(-1))污染组分别有15,13种物质发生下调,且大部分为中低脂溶性蟾蜍甾烯(异沙蟾毒精、去乙酰华蟾毒精等)。结论:重金属汞污染对蟾蜍甾烯水平有潜在影响,且随着浓度的升高呈现明显降低趋势。     

Realized niche shift during a global biological invasion

Accurate forecasts of biological invasions are crucial for managing invasion risk but are hampered by niche shifts resulting from evolved environmental tolerances (fundamental niche shifts) or the presence of novel biotic and abiotic conditions in the invaded range (realized niche shifts). Distinguishing between these kinds of niche shifts is impossible with traditional, correlative approaches to invasion forecasts, which exclusively consider the realized niche. Here we overcome this challenge by combining a physiologically mechanistic model of the fundamental niche with correlative models based on the realized niche to study the global invasion of the cane toad Rhinella marina. We find strong evidence that the success of R. marina in Australia reflects a shift in the species’ realized niche, as opposed to evolutionary shifts in range-limiting traits. Our results demonstrate that R. marina does not fill its fundamental niche in its native South American range and that areas of niche unfilling coincide with the presence of a closely related species with which R. marina hybridizes. Conversely, in Australia, where coevolved taxa are absent, R. marina largely fills its fundamental niche in areas behind the invasion front. The general approach taken here of contrasting fundamental and realized niche models provides key insights into the role of biotic interactions in shaping range limits and can inform effective management strategies not only for invasive species but also for assisted colonization under climate change.Understanding the factors that limit species’ geographic ranges has long stood as a fundamental goal in ecology (1) and is critical for making robust predictions of species’ range shifts as a result of climate change and biotic exchange. Niche theory (2) argues that species’ ranges are limited by physiological tolerances (which define the fundamental niche), as well as biotic interactions and dispersal barriers (which further constrain the fundamental niche to the realized niche), but the relative roles of these factors in shaping range limits remain poorly understood. Standard approaches to range prediction are based on correlations between species'' observed distributions and climate (i.e., the realized niche) (3, 4), and thus confound the influences of abiotic and biotic constraints on species’ ranges.Range shift projections based on correlative models also assume that species’ niches (both realized and fundamental) are conserved through space and time (3, 5, 6). However, there is growing evidence to suggest that species can undergo rapid niche shifts in novel environments (7–9) through either evolved environmental tolerances (fundamental niche shifts) (10, 11) or release from dispersal barriers or biotic constraints (realized niche shifts) (12, 13). Understanding whether such niche shifts are widespread in nature not only is important for validating the use of correlative models in climate change and invasive species impact assessments but also has implications for understanding patterns of community assembly and speciation (14, 15).Invasive species frequently experience release from biotic interactions and dispersal barriers in their invaded ranges (4, 12, 16), and thus provide model systems for investigating the degree to which niches are spatially and temporally conserved. Current approaches for examining niche shifts in invasive species primarily rely on comparisons of climates occupied by species in their native and invaded ranges (6, 7, 17, 18). However, such correlative comparisons fail to differentiate between the influences of adaptation after introduction and biotic interactions and dispersal barriers that are absent in a species’ invaded range. Here we present an approach that helps resolve this issue by integrating correlative niche models with mechanistic biophysical predictions of the fundamental niche (19). Biophysical models incorporate links between climate and an organism’s functional traits and are developed independent of a species’ current distribution. The biophysical approach thus provides a prediction of where a species can survive and reproduce in the absence of biotic interactions and dispersal limitations (19). We apply this mechanistic approach to investigate whether the invasion of Australia by the cane toad (Rhinella marina, formerly Bufo marinus) has been facilitated by a shift in the species’ realized or fundamental niche. Since its introduction to Australia in 1935 as a biological control agent, R. marina has expanded its range to include more than 1.2 million km² of the continent (20). This large-scale invasion has been facilitated by thermal acclimation (21, 22), as well as evolutionary shifts in locomotor performance (23). Have the environmental tolerances of toads evolved as well?     

The Effects of the Toxic Cyanobacterium Limnothrix (Strain AC0243) on Bufo marinus Larvae

Limnothrix (strain AC0243) is a cyanobacterium, which has only recently been identified as toxin producing. Under laboratory conditions, Bufo marinus larvae were exposed to 100,000 cells mL⁻¹ of Limnothrix (strain AC0243) live cultures for seven days. Histological examinations were conducted post mortem and revealed damage to the notochord, eyes, brain, liver, kidney, pancreas, gastrointestinal tract, and heart. The histopathological results highlight the toxicological impact of this strain, particularly during developmental stages. Toxicological similarities to β-N-Methylamino-l-alanine are discussed.     

密度与饲料对中华蟾蜍蝌蚪生长发育的影响

该研究分析了4个不同的饲养密度和5种饲料对中华蟾蜍Bufo gargarizans蝌蚪生长发育的影响,以确定最适养殖密度和饲料种类。在饲养密度实验中,中华蟾蜍蝌蚪分别饲养在200,500,1 000,2 000只/m~2的不同密度条件下;在饲料种类实验中,将中华蟾蜍蝌蚪分为5组,分别用5种不同饲料喂食。每隔7 d测量和记录1次蝌蚪的体重、头体长、尾长和死亡个数。结果表明:饲养密度试验和饲料种类试验中,中华蟾蜍蝌蚪临近变态时(变态前)和变态后的成活率分别为68.7%~96.3%,5.7%~36.0%;饲养密度对蝌蚪变态前的成活率没有显著影响,中华蟾蜍蝌蚪在最适养殖密度1 000只/m~2时,蝌蚪具有较大的体重和成活数量;饲料种类对蝌蚪变态前的成活率没有显著影响,喂食饲料Ⅱ(37.9%粗蛋白和5.7%粗脂肪),Ⅳ(25.1%粗蛋白和4.0%粗脂肪)和Ⅴ(鸡蛋黄)的蝌蚪均具有较大的体重,这3种饲料均为中华蟾蜍蝌蚪较为适宜的饲料,人工养殖具体采用何种饲料,可根据饲料的易得性和成本进行选择与组合。     

鸟类动物家鸡和哺乳类动物家兔之间及两栖纲动物蟾蜍和硬骨鱼类鲤鱼之间血红蛋白互作的研究

目的:研究鸟类动物家鸡和哺乳类动物家兔之间、两栖纲动物蟾蜍和硬骨鱼类鲤鱼之间血红蛋白(hemoglobin,Hb)的相互作用.方法:淀粉-琼脂糖混合凝胶薄层电泳.结果:家鸡和家兔Hb之间在"穿过"、"兜过"实验电泳过程中出现扭曲现象;蟾蜍和鲤鱼Hb之间在"穿过"、"兜过"实验电泳过程中未出现扭曲现象.结论:家鸡和家兔Hb之间可发生相互作用,而蟾蜍和鲤鱼Hb之间未发生相互作用.     

Sodium transport across toad epithelia

Summary Short circuit current across abdominal skin and urinary bladder, were measured on epithelia taken from animals which were adapted to either distilled water or 400 mOsm NaCl. Syntocinon and Amiloride were used to achieve maximal stimulation and maximal inhibition respectively. The Amiloride-sensitive component of Na-transport, thus obtained, almost diminished in skin, but only 30% reduced in the urinary bladder from 400 mOsm adapted animals as compared to preparations from distilled water adapted animals. The differential response of the two epithelia is attributed to the regular moulting which is found for the skin but not with the bladder.     

干蟾皮中蟾毒内酯类成分的提取工艺研究

目的 探讨干蟾皮中蟾毒内酯类成分的最佳提取工艺.方法 通过正交试验法考察乙醇体积分数、乙醇用量、提取时间、提取次数对干蟾皮中蟾毒内酯类成分提取效果的影响,并以酯蟾毒配基和华蟾酥毒基的总量-总毒基量为考察指标,采用超高效高压液相色谱-紫外检测器检测.结果 最佳提取工艺为以10倍量80%乙醇提取2次,每次2 h.结论 所优选出的提取工艺方法可行、稳定、合理.     

Antiproliferative activity and new argininyl bufadienolide esters from the “cururú” toad Rhinella (Bufo) schneideri

Ethnopharmacological relevance

Toads known as “cururú” (Rhinella schneideri) have been used in the Brazilian Pantanal and Paraguayan Chaco wetlands to treat erysipelas and cancer. The aim of the study was to assess the antiproliferative effect of the venom obtained from Rhinella schneideri and to identify its constituents by spectroscopic and spectrometric methods.

Materials and methods

The venom was obtained by gentle pressing the parotid glands of the toads. The dry crude drug was analyzed by HPLC–MS–MS and chromatographed on Sephadex LH-20 to obtain purified compounds and fractions for spectroscopic analysis. The venom and fractions were evaluated for antiproliferative activity towards normal human lung fibroblasts (MRC-5) and four human cancer cell lines: gastric epithelial adenocarcinoma (AGS), lung cancer (SK–MES-1), bladder carcinoma (J82) and promyelocytic leukemia (HL-60).

Results

From the Rhinella schneideri venom, 29 compounds were isolated and/or identified by spectroscopic and spectrometric means. Three known alkaloids and five argininyl diacids were identified in the complex mixture by HPLC–MS–MS. Nine out of fifteen argininyl diacid derivatives of the bufadienolides bufalin, marinobufagin and telocinobufagin are reported for the first time and four argininyl diacids are described for the first time as natural products. The venom and the fractions 9–13 showed a remarkable antiproliferative effect, with IC₅₀ values in the range 0.019–0.022, 0.035–0.040, 0.028–0.064, 0.042–0.056 and 0.044–0.052 µg/mL for MRC-5, AGS, SK-MES-1, J82 and HL-60 cell lines, respectively. Under the same experimental conditions, IC₅₀ values of the reference compound etoposide were 2.296, 0.277, 1.295, 1.884 and 1.059 µg/mL towards MRC-5, AGS, SK-MES-1, J82 and HL-60 cells, respectively.

Conclusions

The venom showed a strong antiproliferative effect towards human cancer cells and presented a high chemical diversity in its constituents, supporting its use as anticancer agent. These findings encourage further work on the chemistry and bioactivity of South American toad venoms.     

中国大陆首例广州管圆线虫病区流行病学的调查

本文报告1984年10月在广东省徐闻县友好农场首例广州管圆线虫病区进行的流行病学调查。家鼠、褐云玛瑙螺、足襞蛞蝓、黑眶蟾蜍的感染率分别为28.57%(4/14)、33.83%(158/467)、29.19%(54/185)、4.76%(2/42)。并对徐闻县地理概况和人群进行了调查(生活习惯、卫生习惯、病史回顾、血涂片检查末梢血液嗜酸性粒细胞)。对于人群感染不多的原因,作者从感染途径(皮肤感染)、感染方式(食螺方式)进行了探讨。本调查资料为当地群众防治本病提供资料。     

Amiloride inhibits the vasopressin-induced increase in epithelial water permeability

The vasopressin (VP)-induced increase in water permeability in high-resistance, amphibian epithelia is not altered by the abolition of net Na⁺ flux caused by amiloride added to the apical bathing medium. In this work we looked at the effects on water transport of amiloride added to the serosal medium at a concentration (10^–3 M) known to inhibit Na⁺/H ⁺ exchange. In urinary bladders of Bufo marinus, amiloride partially blocked the hydrosmotic response to VP. A similar inhibition was found with cyclic adenosine 5-monophosphate (cAMP) or serosal hypertonicity. We hypothesized that this effect of amiloride could be due to an inhibition of Na⁺/H⁺ and/or Na⁺/Ca²⁺ antiporters present in the epithelial basolateral membrane and looked at the effects of the diuretic in Na⁺-free media. A similar degree of inhibition of water flow was still found, thus showing that amiloride acts on a cell target other than the antiporters. In toad skin, amiloride did not inhibit the hydrosmotic response to VP and to isoproterenol; however the response to high K⁺ was significantly reduced. Among the amiloride cell targets described so far, adenylate cyclase and protein kinase A appear to be the best candidates to explain the inhibition of the hydrosmotic response reported here. Direct measurements of intracellular cAMP are needed however to substantiate this hypothesis.