Behavioural examination of the infrared sensitivity of rattlesnakes (Crotalus atrox)

Pitvipers (Crotalinae) and boid snakes (Boidae) possess highly sensitive infrared (IR) receptors. The ability of these snakes to image IR radiation allows the assessment of the direction and distance of an IR source (such as warm-blooded prey) in the absence of visual cues. The aim of this study was to determine the behavioural threshold of snakes to an IR stimulus. A moving IR source of constant size and temperature was presented to rattlesnakes (Crotalus atrox) at various distances (10–160 cm) from their snout. The snakes’ responses were quantified by measuring distinct behavioural changes during stimulus presentation (head jerks, head fixed, freezing, rattling and tongue-flicking). The results revealed that C. atrox can detect an artificial IR stimulus resembling a mouse in temperature and size up to a distance of 100 cm, which corresponds to a radiation density of 3.35 × 10⁻³ mW/cm². These behavioural results reveal a 3.2 times higher sensitivity to IR radiation than earlier electrophysiological investigations.     

A novel phospholipase A2 from Agkistrodon blomhoffii ussurensis venom: Purification,proteomic, functional and structural characterizations

A phospholipase A₂ was isolated from the snake venom of Chinese Agkistrodon blomhoffii Ussurensis by column chromatography using DEAE Sephadex A-50 ion-exchange chromatography, Sephadex G-75 gel filtration chromatography and Mono Q ion-exchange chromatography, and designated as Akbu-PLA₂. It showed an average molecular mass of 13,980 ± 3 amu determined by MALDI TOF mass spectrometry. Protein identification results from HPLC-nESI-MS/MS analysis indicated that the Akbu-PLA₂ was a new snake venom acidic PLA₂. Seven peptides were sequenced from Akbu-PLA₂ by HPLC-nESI-MS/MS analysis. Sequencing alignment indicated that Akbu-PLA₂ shared homolog peptides of phospholipases A₂ from the venoms of Gloydius ussurensis, Gloydius halys, Gloydius halys (halys viper), Deinagkistrodon acutus and Agkistrodon halys Pallas. Akbu-PLA₂ has an optimum hydrolytic activity temperature of ∼45 °C. The intrinsic fluorescences of Tyr and Trp residues of Akbu-PLA₂ showed emission wavelengths red-shifted by 13.6 and 1.6 nm from those of free Tyr and Trp, respectively. Akbu-PLA₂ was shown to contain one Ca²⁺ per monomer by ICP-AES measurement. The Ca²⁺ ion was found to be critical for both the hydrolytic activity and the structure of Akbu-PLA₂. Ca²⁺ increased the emission fluorescence intensity and the hydrophobicity of the environment of Akbu-PLA₂. The hydrolytic activity of Akbu-PLA₂ was accelerated due to the addition of Ca²⁺ ion by enhancing the substrate binding. However, a protein component with the molecular weight two-fold relative to that of Akbu-PLA₂ was found to be difficult to eliminate for the purification of Akbu-PLA₂. HPLC-nESI-MS/MS detected the same peptides from it as from Abku-PLA₂, which indicated that it should be a homodimer of Akbu-PLA₂. A proteomic approach, 2D SDS-PAGE coupled to HPLC-nESI-MS/MS, supported the co-existence of the Akbu-PLA₂ monomer and dimer in the crude snake venom. Results from the combination of phosphoprotein and glycoprotein specific stains combined with the HPLC-nESI-MS/MS method indicated that both the Akbu-PLA₂ monomer and dimer were both phosphorylated and glycosylated. The addition of exogenous Ca²⁺ ion was found to be able to promote the dimer formation of Akbu-PLA₂. We conclude that a novel PLA₂ was successfully obtained. The systemically biochemical, proteomic, structural and functional characterization results from Akbu-PLA₂ reveal new threads and provide valuable inputs for the study of snake venom phospholipases A₂.     

Synthesis, biological, and theoretical evaluations of new 1,2,3-triazoles against the hemolytic profile of the Lachesis muta snake venom

The current treatment used against envenomation by Lachesis muta venom still presents several side effects. This paper describes the synthesis, pharmacological and theoretical evaluations of new 1-arylsulfonylamino-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid ethyl esters (8a–f) tested against the hemolytic profile of the L. muta snake venom. Their structures were elucidated by one- and two-dimensional NMR techniques (¹H, APT, HETCOR ¹J_CH and ⁿJ_CH, n = 2, 3) and high-resolution electrospray ionization mass spectrometry. The series of triazole derivatives significantly neutralized the hemolysis induced by L. muta crude venom presenting a dose-dependent inhibitory profile (IC₅₀ = 30−83 μM) with 1-(4′-chlorophenylsulfonylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid ethyl ester (8e) being the most potent compound. The theoretical evaluation revealed the correlation of the antiophidian profile with the coefficient distribution and density map of the Highest Occupied Molecular Orbitals (HOMO) of these molecules. The elucidation of this new series may help on designing new and more efficient antiophidian molecules.     

Reproductive patterns and secondary production of <Emphasis Type="Italic">Gammaropsis japonicus</Emphasis> (Crustacea,Amphipoda) on the seagrass <Emphasis Type="Italic">Zostera marina</Emphasis> of Korea

It is essential to know the nutrient limitation status of biofilms to understand how they may buffer uptake and export of nutrients from polluted watersheds. We tested the effects of nutrient additions on biofilm biomass (chlorophyll a, ash free dry mass (AFDM), and autotrophic index (AI, AFDM/chl a)) and metabolism via nutrient-diffusing substrate bioassays (control, nitrogen (N), phosphorus (P), and N + P treatments) at 11 sites in the Upper Snake River basin (southeast Idaho, USA) that differed in the magnitude and extent of human-caused impacts. Water temperature, turbidity, and dissolved inorganic N concentrations all changed seasonally at the study sites, while turbidity and dissolved inorganic N and P also varied with impact level. Chl a and AI on control treatments suggested that the most heavily impacted sites supported more autotrophic biofilms than less-impacted sites, and that across all sites biofilms were more heterotrophic in autumn than in summer. Nutrient stimulation or suppression of biofilm biomass was observed for chl a in 59% of the experiments and for AFDM in 33%, and the most frequent response noted across all study sites was N limitation. P suppression of chl a was observed only at the most-impacted sites, while AFDM was never suppressed by nutrients. When nutrient additions did have significant effects on metabolism, they were driven by differences in biomass rather than by changes in metabolic rates. Our study demonstrated that biofilms in southeast Idaho rivers were primarily limited by N, but nutrient limitation was more frequent at sites with good water quality than at those with poor water quality. Additionally, heterotrophic and autotrophic biofilm components may respond differently to nutrient enrichment, and nutrient limitation of biofilm biomass should not be considered a surrogate for metabolism in these rivers. Handling editor: D. Ryder     

不同滤波方法对超声图像分割的影响

采用各向异性滤波方法以及Gabor滤波方法对乳腺肿瘤超声图像进行处理,再使用snake方法以及levelset方法在设置相同参数的条件下,对过滤的图像分别进行分割。试验结果表明,不同的滤波方法在分害4目标图像的收敛度,边缘圆滑度及整体轮廓提取效果都有较大影响,为分割图像选取适当的滤波器提供了参考。     

Analysis of the subproteomes of proteinases and heparin‐binding toxins of eight Bothrops venoms

Viperid snakes show the most complex snake‐venom proteomes and offer an intriguing challenge in terms of understanding the nature of their components and the pathological outcomes of envenomation characterized by local and systemic effects. In this work, the venom complexity of eight Bothrops species was analyzed by 2‐DE, and their subproteomes of proteinases were explored by 2‐D immunostaining and 2‐D gelatin zymography, demonstrating the diversity of their profiles. Heparin, a highly sulfated glycosaminoglycan released from mast cells, is involved in anti‐coagulant and anti‐inflammatory processes. Here, we explored the hypothesis that heparin released upon envenomation could interact with toxins and interfere with venom pathogenesis. We first identified the Bothrops venom subproteome of toxins that bind with high‐affinity for heparin as composed of mainly serine proteinases and C‐type lectins. Next, we explored the Bothrops jararaca toxins that bind to heparin under physiological conditions and identified a relationship between the subproteomes of proteinases, and that of heparin‐binding toxins. Only the non‐bound fraction, composed mainly of metalloproteinases, showed lethal and hemorrhagic activities, whereas the heparin‐bound fraction contained mainly serine proteinases associated with coagulant and fibrinogenolytic activities. These data suggest that heparin binding to B. jararaca venom components in vivo has a minor protective effect to venom toxicity.     

Identification and characterization of a phospholipase A2 from the venom of the Saw-scaled viper: Novel bactericidal and membrane damaging activities

Phospholipase A₂ (PLA₂), a common toxic component of snake venom, has been implicated in various pharmacological effects. In this study, a basic myotoxic PLA₂, named EcTx-I was isolated from Echis carinatus snake venom by using gel filtration on Superdex G-75, and reverse phase HPLC on C18 and C8 Sepharose columns. PLA₂, EcTx-I was 13,861.72 molecular weight as estimated by MALDI-TOF (15 kD by SDS-PAGE), and consisted of 121 amino acid residues cross-linked by seven disulfide bonds. The N-terminal sequences revealed significant homology with basic myotoxic PLA₂s from other snake venoms. The purified PLA₂ EcTx-I was evaluated (250 μg/ml) for bactericidal activity of a wide variety of human pathogens against Burkholderia pseudomallei (KHW&TES), Enterobacter aerogenes, Escherichia coli, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus. EcTx-I showed strong antibacterial activity against B. pseudomallei (KHW) and E. aerogenes among the tested bacteria. Other Gram-negative and Gram-positive bacteria showed only a moderate effect. However, the Gram-positive bacterium E. aerogenes failed to show any effect on EcTx-I protein at tested doses. The most significant bacteriostatic and bactericidal effect of EcTx-I was observed at MICs of >15 μg/ml against (B. pseudomallei, KHW) and MICs >30 μg/ml against E. aerogenes. Mechanisms of bactericidal and membrane damaging effects were proved by ultra-structural analysis. EcTx-I was able to induce cytotoxicity on THP-1 cells in vitro as well as lethality in BALB/c mice. EcTx-I also induced mild myotoxic effects on mouse skin, but was devoid of hemolytic effects on human erythrocytes up to 500 μg/ml. It is shown that the toxic effect induced by E. carinatus venom is due to the presence of myotoxic PLA₂ (EcTx-I). The result also corroborates the hypothesis of an association between toxic and enzymatic domains. In conclusion, EcTx-I displays a heparin binding C-terminal region, which is probably responsible for the cytotoxic and bactericidal effects.     

广东象头山国家级自然保护区蛇类多样性及保护研究

目的了解广东象头山国家级自然保护区蛇类多样性现状,探讨保护区蛇类资源的有效保护对策。方法采用访问调查和野外样带调查相结合的方法。结果该保护区现已纪录蛇类有5科45种,占中国已纪录蛇类物种数的22．0％,占广东省已纪录蛇类物种数的46．4％,区系组成以东洋界华中区和华南区共有种为主,占82．2％。保护区有国家Ⅰ级重点保护野生动物蚺双带亚种（蟒蛇）（Python molurus bivittatus）,以及舟山眼镜蛇（Najaatra）、眼镜王蛇（Ophiophagus hannah）、灰鼠蛇（Ptyas korros）和滑鼠蛇（Ptyas mucosus）等15种重要经济蛇类。结论广东象头山国家级自然保护区蛇类物种多样性十分丰富,但长期过度猎捕和栖息地遭破坏导致保护区一些蛇类种群数量明显减少,需加强保护。本文针对保护区蛇类保护问题提出5点建议。     

Time-course of lipid peroxidation in different organs of mice treated with Echis pyramidum snake venom

This study examined the effect of Echis pyramidum (EP) venom on time-course of lipid peroxidation in different vital organs of mice. Adult male Swiss albino mice were injected with EP venom (2 mg/kg, i.p.); control mice received vehicle alone (normal saline). Mice were killed at 1, 3, 6, 12, and 24 h post-envenomation. The liver, lung, kidney, heart, and brain (cerebrum and cerebellum) were collected for the estimation of malondialdehyde (MDA), an index of lipid peroxidation. The results of this study showed that a single injection of EP venom caused a significant lipid peroxidation in all the organs studied. The onset of lipid peroxidation was as early as 1 h and persisted for several hours, suggesting an important role of oxidative stress in the cytotoxicity of EP venom.     

蛇胸腺胚胎发育的组织学研究

该文应用光镜、电镜和细胞计数技术对胚胎发育期虎斑颈槽蛇胸腺的发育分化进行了研究。在胚胎发育１１期,胸腺原基内出现前淋巴细胞。从胚胎发育１２期至出生前（１６期）,淋巴细胞不断增殖分化,小淋巴细胞逐渐增多,而淋巴母细胞和中淋巴细胞逐渐减少。胸腺皮质和髓质形成于１６期。巨噬细胞以及肌样细胞和胸腺ＡＰＵＤ细胞分别形成于胚胎发育１４期和１５期,随后数量有所增加,分别分布于胸腺皮质和髓质。