视黄酸对赤子爱胜蚓再生头尾轴形成的影响

为了探讨视黄酸对蚯蚓再生的影响,用视黄酸处理了从不同部位剪切的蚯蚓体段．观察其存活率、重量和再生长度的变化。结果表明,有头无尾的体段存活率受视黄酸影响较小,而无头有尾的处理受视黄酸影响较大;视黄酸处理后30d,各处理再生长度和存活率均小于对照;视黄酸对蚯蚓再生有明显影响,能延迟和干扰再生,影响头部的形成。视黄酸影响蚯蚓再生的作用方式可能是通过干扰前后体轴的形成,从而影响蚯蚓再生图式形成。     

异化Fe(Ⅲ)还原酶促反应及调控机制的研究进展

异化Fe(Ⅲ)还原菌不是分类学上的概念,它具有系统发育及环境来源多样性的特点。与其他大多数的电子受体不同,在近中性pH值条件下,Fe(Ⅲ)的溶解度很低,通常以不溶性的Fe(Ⅲ)氧化物的形式存在。目前,对微生物如何获得和还原不溶性Fe(Ⅲ)的机理仍缺乏系统的了解。以希瓦氏菌和地杆菌为例,本文综述了3种异化Fe(Ⅲ)还原的酶促反应机制及其分子调控机理：异化Fe(Ⅲ)还原菌与Fe(Ⅲ)氧化物直接接触机制、电子穿梭体的作用机制、铁载体作用机制,多种膜蛋白特别是多血红素的细胞色素蛋白参与微生物的异化Fe(Ⅲ)还原过程,并形成复杂的调控网络。此外,本文也对异化Fe(Ⅲ)还原酶促反应及其分子调控机理将来的研究方向进行了展望,以期对这一重要的生化过程有更为全面的认识。     

Substrate-induced Changes in Protease Active Site Conformation Impact on Subsequent Reactions with Substrates

Enzymatic catalysis of biochemical reactions is essential to all living systems. The “lock and key” and “induced fit” models were early contributions to our understanding of the mechanisms involved in the reaction between an enzyme and its substrate. However, whether a given substrate-induced conformation is rigid or remains flexible has not yet been determined. By measuring the enzyme activity and intrinsic fluorescence of a nonspecific Eisenia fetida protease-I with different chromogenic substrates, we show that in subsequent reactions of protease with substrates, both the “lock and key” and “induced fit” mechanisms are used depending on the degree of conformational change required. Chromozym-Th- or chromosym-Ch-induced protease conformations were unable to bind chromozym-U. The chromosym-U-induced protease conformation remained flexible and could be further induced by chromozym-Th and chromozym-Ch. When low concentrations of guanidine HCl were used to disturb the conformation of the enzyme, only small changes in intrinsic fluorescence of the chromozym-Th-induced protease were detected, in contrast to the native enzyme whose intrinsic fluorescence markedly increased. This indicates that the substrate-induced enzyme was relatively rigid compared with the native protease. Utilizing a lock and key mechanism for secondary substrate reactions may have adaptive value in that it facilitates high efficiency in enzymatic reactions.     

Development of a modified vermireactor for efficient vermicomposting: a laboratory study

Waste has become an index of growth. Utilization of waste materials for productivity purposes is important for both economic and environmental reasons. Vermicomposting is an important aspect as it converts waste to wealth. In this context, a modified vermireactor in place of the conventional vermireactor for efficient vermicomposting has been developed.

In the conventional low- and high-rate vermireactors, the space for vermicomposting is reduced due to the thick layer of vermibed at the bottom of the reactor, thus a small amount of worm casts is produced. In the modified vermireactors there was only a thick moist cloth at the bottom in place of the thick vermibed which allowed a comparatively large quantity of organic waste to be vermicomposted as compared to conventional vermireactors. Laboratory studies showed that the modified vermireactor performed better than the conventional vermireactor in average vermicast produced and mg castings l⁻¹ (digester volume) day⁻¹. The study further showed that only the volume of the vermireactor was responsible for the high yield of worm casts.     

Vermicomposting of mixed solid textile mill sludge and cow dung with the epigeic earthworm Eisenia foetida

This paper reports the results of a study of vermicomposting with Eisenia foetida of solid textile mill sludge mixed with cow dung in different ratios in a 90 days composting experiment. Vermicomposting resulted in significant reduction in C:N ratio and increase in TKN. Total K and Ca were lower in the final cast than the initial feed mixture. Microbial activity measured as dehydrogenase activity increased up to 75 days and decreased on further incubation. Total P was higher in the final product than the initial feed mixture. Total heavy metal contents were lower in the final product than initial feed mixture. Solid textile mill sludge can be potentially useful as raw substrate in vermicomposting if mixed with up to 30% cow dung (on dry weight basis). The growth and cocoon production of the worm species in different feed mixtures were also investigated.     

Evidence of lipofuscin and melanin in the brown body of the earthworm Eisenia fetida andrei

By means of histochemical and electron-microscopic techniques, two pigments were identified in the brown body of the earthworm Eisenia fetida andrei. Lipofuscin, often called the aging pigment, was the more abundant pigment and the first to be synthesized. Melanin was also found but was only present in the mature brown body. A computer-assisted image analysis was used to quantify the relative abundance of the two pigments at different stages of the formation of the brown body. A previous study showing phenoloxidase activity in the coelomocytes and the present demonstration of the ability of these cells to produce reactive oxygen systems when agglutinated can be correlated with the simultaneous presence of the two pigments in the brown body. The physiological significance of pigment synthesis by brown bodies is discussed with respect to the immune response in earthworms.     

Neurochemical characterization of nervous elements innervating the body wall of earthworms (Lumbricus, Eisenia): immunohistochemical and pharmacological studies

The distribution and chemical neuroanatomy of nervous elements and certain pharmacological–physiological characteristics of the innervation of the body wall in earthworms are described. Solitary sensory bipolar cells can be found among the epithelial cells. These bipolar cells contain serotonin, tyrosine hydroxylase, histamine, gamma-amino-butyric acid (GABA), Eisenia tetradecapeptide, proctolin or rhodopsin in various combinations. In the body wall, the plexus submuscularis is composed of nerve fibres only, whereas the plexus subepithelialis and muscularis also contain solitary nerve cells. These cells display histamine, GABA or neuropeptide Y immunoreactivity. The fibres of the three plexuses are reactive to serotonin, histamine, Eisenia tetradecapeptide, proctolin, GABA and neuropeptide Y antibodies. FMRFamide-immunoreactive fibres of the plexus muscularis originate from the central nervous system, whereas axons containing the other studied molecules are derived from both peripheral and central structures. High pressure liquid chromatography assays have revealed serotonin, dopamine and histamine in the body wall. Contractions of the body wall musculature can be elicited with serotonin and FMRFamide. Serotonin-evoked contractions are suppressed by the application of GABA. Serotonin acts both directly on the muscle cell receptors and indirectly through initiating transmitter release from the nervous elements, whereas the FMRFamide-induced contractions seem to be mediated through the muscle cell receptors only. The pharmacological profiles of the serotonin and GABA receptors resemble those of the vertebrate 5-HT₃ and GABA_B receptor types. Our findings indicate that both the sensory and efferent system of the annelid body wall operate by means of a variety of neuroactive compounds, suggesting a complex role of signalling systems in the regulation of this organ.This work was supported by the Hungarian Scientific Research Fund (OTKA; grant nos. T 34106 and T 34160). Márta Wilhelm is in receipt of a János Bolyai Scholarship.     

Molecular cloning and characterization of cDNA encoding fibrinolytic enzyme-3 from earthworm Eisenia foetida

Earthworm fibrinolytic enzyme (EFE), a multi-com-ponent protease purified from some earthworm breeds,belongs to serine protease family with fibrinolytic activity[1]. It has been used in prevention and treatment of cardiacand cerebrovascular diseases in Ch…     

三种兽药添加剂对土壤赤子爱胜蚓的毒理学研究

喹乙醇、阿散酸和土霉素是应用极广的兽药添加剂,在畜牧业的发展中起着特殊的作用,但其使用不当或过量使用会给环境带来很大危害.采用土壤中的重要生物赤子爱胜蚓作为生物材料,分别研究了喹乙醇、阿散酸和土霉素对赤子爱胜蚓的急性毒性和对赤子爱胜蚓体腔细胞DNA的损伤.结果表明,喹乙醇溶液法LC₅₀>2000mg·L^-1,滤纸法LC₅₀>5.71×10^-2mg·cm^-2,而阿散酸和土霉素在所设最大受试剂量内没有毒性.单细胞凝胶电泳试验结果表明,阿散酸没有引起蚯蚓体腔细胞DNA明显损伤;喹乙醇和土霉素均能引起一定程度的DNA损伤,中、高剂量组与阴性对照相比有极显著差异(P<0.01).因此,有必要加强对以上兽药添加剂,特别是喹乙醇和土霉素的管理,控制用药时间和剂量,以确保人体健康和环境安全.     

Toxicity and Bioaccumulation of Petroleum Mixtures with Alkyl PAHs in Earthworms

The toxicities of three oil products with boiling-point ranges representative of petroleum hydrocarbons were tested on earthworms (Eisenia fetida) to investigate the correlation between bioaccumulated concentrations of polycyclic aromatic hydrocarbons (PAHs) and toxicity. The toxicities to earthworms were in the sequence: kerosene > diesel > bunker-C. After 14 days, the LC50s of the soils contaminated with kerosene, diesel, and bunker-C were 1079, 9135, and 15,609 mg/kg, respectively. Analysis of the body residue concentrations of PAHs in the earthworms showed that the accumulation of alkyl PAHs predominated that of the 16 priority PAHs. Principal component analysis (PCA) identified 12 PAHs, including four alkylated naphthalenes, as the oil constituents that affected mortality in the kerosene-contaminated soil. For the diesel-contaminated soil, eight PAHs were identified, including dibenzothiophene. It was not clear which compounds affected mortality in the bunker-C soil. Across the three series, biota-to-soil accumulation factors (BSAFs) ranged from 10^–2.05 to 10^3.98, and generally increased as the hydrophobicity (K_ow) or molecular weight of the alkyl PAHs increased. The toxicity endpoints of each oil product can be used as reference values in the risk assessment of soils contaminated with petroleum, and individual PAHs screened out have implications for future toxicity assessment of petroleum hydrocarbons.