Heavy Metal Toxicity and Iron Chlorosis

1. The toxicity of copper, nickel, cobalt, zinc, chromium, andmanganese to mustard was studied in water culture, utilizingeither the ionic form or the EDTA chelate of the metal in thepresence of either ferric chloride or ferric EDTA. 2. In presence of ferric chloride the activity of the metalsin producing chlorosis was as given above, i.e. in the orderof stability of their chelates. In the presence of ferric versenate,toxicity of the ionic metal was much reduced. The metal chelatesgave very little indication of toxicity with either form ofiron. 3. It was found that the ratio of total phosphorus to totaliron was higher in chlorotic plants than in green plants, irrespectiveof which metal was causing the toxicity. 4. Copper could be demonstrated in the phloem cells of the rootusing bis-cyclohexanone-oxalydihydrazone as histochemical reagent.It is postulated that transport of iron probably takes placein the phloem as an active process. 5. It would appear that as a major part of the iron in plantcells is attached to nucleo- or phospho-proteins, the heavymetals must be similarly attached to phospho-proteins.     

重金属污染对蛙蟾类毒性的研究进展

基于近20年的大量相关资料,综述了重金属对蛙蟾类毒性影响方面的研究,介绍了实验动物和实验方法,综合了重金属对蛙蟾类在形态、器官、组织、细胞和分子水平上毒害的主要表现,从重金属致毒过程、环境因素、物种、发育、重金属积累、联合毒性等角度初步分析了重金属对蛙蟾毒性大小的影响因素和毒性作用的主要机理,归纳了蛙蟾的几种抗毒/解毒/避毒反应,对开展进一步的研究提出建议.     

五种重金属离子对克氏原螯虾（Procambarus clarkiai）的急性毒性作用研究

采用静水生物法、充气和恒温法研究了5种重金属离子对克氏原螯虾的急性毒性作用,并以直线内插法得出了24 h、48 h、72 h和96 h的半致死量（LD50）.研究结果表明：重金属离子的毒性顺序由大到小依次为：Hg2＋、Cd2＋、Cu2＋、Pb2＋和Zn2＋.根据毒性分级标准,5种重金属离子对克氏原螫虾均为高毒物,其安全质量浓度依次为：0.0143 mg/L、0.0322 mg/L、0.0401 mg/L、0.1995 ms/L和0.2795 mg/L.以浓度对数和死亡率进行回归分析,分别得出了5种重金属离子对螯虾24 h、48 h和96 h的回归方程.     

Metal resistances of Chlorophyta from rivers polluted by heavy metals

SUMMARY. Two-hundred isolates, comprising 87 species of Chlorophyta, were obtained from sites along the Rivers Hayle and Gannel. which drain the ancient mining region of Cornwall. All isolates were tested for sensitivity to copper, lead, zinc and cadmium. In general, isolates were resistant to the metals normally present in their habitats. However, the distribution of metal sensitivities of the algae from a given site was broad; the effect of metal pollution was to shift the median response of a population toward higher metal resistance. Resistant algae of two general classes were identified: some normally sensitive species were metal-tolerant, presumably through genetic adaptation; other species were metal-resistant even when isolated from a non-polluted habitat. Many isolates of both types displayed multiple-resistances or co-tolerances. For example, copper tolerant isolates from high copper sites tended to be also lead resistant; however, algae from high lead sites were usually very copper sensitive. Zinc and cadmium resistances also were correlated among isolates from both zinc-polluted and non-polluted sites. General metal-insensitivity seemed to be common, particularly among gelatinous Chlamydomonas and Gloeococcus species. Thus, several evolutionary strategies appear to coexist among algae from metal polluted environments.     

霉菌吸附重金属离子的研究进展

介绍了目前国内外采用霉菌吸附分离废水中重金属离子的研究情况,总结了不同霉菌的吸附能力,讨论了霉菌吸附重金属离子的影响因素、机理以及固定化技术,最后展望了霉菌吸附重金属的发展趋势.     

Prasiolales (Chlorophyta) von Helgoland

In their natural habitats, some representatives of Prasiolales are regularly, or often, washed by waves; others are sprayed with sea-water only occasionally, or not at all. In correspondance to this ecological grouping, species require marine or freshwater media respectively for optimal growth in cultures. The halophilic group consists ofPrasiola stipitata andRosenvingiella constricta. Though not analysed in detail, morphological characters and behaviour in cultures suggest that several different species are united under the namePrasiola stipitata. Rosenvingiella constricta, new for Helgoland and thus far reported only twice in Europe, is a dioecious haplont; both meiosis and genotypic sex-determination occur in the germinating zygote. The parenchymatous “Gayella-stage” ofRosenvingiella polyrhiza proved to be male and female gametangia, producing spermatozoids and non-motile eggs respectively. Fertile threads were extremely rare in natural material and — contrary toRosenvingiella constricta — did not occur in cultures, so the life cycle could not be elucidated.Prasiola calophylla is frequently associated withRosenvingiella polyrhiza. The life cycle includes heteromorphic asexual generations, the spores of the leafy thallus giving rise to unicellular aplanosporangia.Prasiola furfuracea reproduces only by spores. Samples ofRosenvingiella polyrhiza frequently containPrasiolopsis in addition to a number of other Chlorophyceae. Consequently, it is easy to appreciate that previous investigators came to erroneous conclusions about life histories and biological relations in studies based only on field material.     

Inhibition of Urease from Seeds of Water-melon (Citrullus vulgaris) by Heavy Metal Ions

Urease from the seeds of water melon was found to be inhibited by heavy metal ions like copper, lead, nickel and cobalt. The order of effectiveness of these metals as inhibitors was Cu²⁺ > Pb²⁺ > Ni²⁺ > Co²⁺. The inhibition by these ions was noncompetitive. Time — dependent interaction of urease with nickel and cobalt exhibited a biphasic inhibition behaviour in which approximately half of the initial activity was lost rapidly (within 2 min) and remainder in a slow phase. The inhibition was largely irreversible, hence could not be reversed by dialysis. These observations are suggestive of half-and-half distribution of — SH groups on the native enzyme resulting urease into asymmetric oligomeric molecule.     

Ostreobium quekettii (Codiales,Chlorophyta)

The shell-inhabiting, marine algaOstreobium quekettii Bornet & Flahault is a distinct species reproducing by zoospores with four flagella. Sporangium formation and the development of zoospores are described. The material obtained from Helgoland (North Sea) is assumed to be identical with the type specimen from the French Atlantic coast.O. quekettii is said to be of worldwide distribution; in the absence of further information, it must be doubted whether other finds reported to belong to this species are identical with the type species.     

Fungal Pathogen of Cladophora glomerata (Chlorophyta)

A strain of Acremonium kiliense (Fungi Imperfecti) produced a water-soluble, dialyzable, heat-stable agent that rendered Cladophora glomerata (Chlorophyta) chlorotic and inhibited its growth.     

Phylogenetic position of the Sphaeropleaceae (Chlorophyta)

 The complete 18S rRNA gene sequences of four Sphaeroplea C.A. Agardh strains (Sphaeropleales, Sphaeropleaceae), two Atractomorpha Hoffman strains (Sphaeropleales, Sphaeropleaceae) and two Ankyra Fott strains (Chlorococcales, Characiaceae) were determined and subjected to phylogenetic analyses. The analyses indicated that all these taxa belong to a monophyletic lineage (Sphaeropleaceae) and are related to a group of chlorophycean algae comprising autosporic taxa and taxa that reproduce by zoospores which are characterized by directly opposed basal bodies. The taxonomic assignment of the Sphaeropleaceae as a family within the Sphaeropleales (Chlorophyta, Chlorophyceae) is discussed. Received December 22, 2000 Accepted September 25, 2001     

Arbuscular Mycorrhizae Effects on Heavy Metal Uptake by Corn

Maximizing uptake of soil-borne metals into plants is important for successful phytoremediation. Arbuscular mycorrhizae (AM) have been shown previously by our group to sequester metals in the roots of plants and prevent translocation to the shoot. If AM colonization of roots can be reduced, it may be possible to increase metal uptake into plants, thus increasing the efficiency of phytoremediation. The fungicide Benomy® was applied to a Pb-contaminated soil and seeded to corn (Zea mays). Because soil pH affects metal solubility, two pHs were also examined. Colonization of roots by AM was significantly decreased by application of Benomyl to soil, but only at the higher soil pH. Benomyl increased the concentration of several elements, including Pb, in shoots. However, the total Pb content in the shoot decreased due to the reduced shoot weight associated with Benomyl application.

     

Composition and Calcium Binding Properties of the Water Soluble Polysaccharides in the Calcareous Alga Halimeda opuntia (L) (Chlorophyta,Udoteaceae)

The mucilages of this alga contain acid polysaccharides, some of which are Ca binding. After deproteinization and gel filtration the residue of the aqueous algal extract has the composition: 2% complexed protein, 3–4% Ca, 0.4–0.5% SiO₂, 0.03–0.04% Al, ∼ 0.005% Fe, rest: polysaccharide. The molecular weights of the major and minor polysaccharide fractions are approximately 5000 and 200000 respectively (Sephadex). Uronic acid and O-ester sulfate give a total of 0.25 μequiv. H⁺/mg polysaccharide whereas the Ca binding capacity is 2.1 μequiv./mg polysaccharide. Ca complexing of the dibasic polyacid is restricted to the low molecular species and involves the 2 acidic and unidentified nonacidic groups. The complexing strength of the polysaccharide for Ca is similar to succinate. These Ca binding polysaccharides may play a role in algal calcification.     

Typification of species of Codium (Bryopsidales, Chlorophyta) described by Okamura

Type specimens of six species of Codium described by Okamura are illustrated, including the holotype of Codium barbatum and lectotypes of Codium coactum, Codium intricatum, Codium pugniforme, Codium saccatum, and Codium subtubulosum. All species are currently recognized except C. pugniforme, which is indistinguishable from the previously described Codium spongiosum Harvey, Codium subtubulosum was abandoned by Okamura in favor of the previously described Codium divaricatum Holmes, but because of the prior existence of C. divaricatum (C. Agardh) Biasoletto, C. subtubulosum is the correct name for this species.     

杨桃对土壤重金属元素的吸收与富集

通过对廉江市杨桃（Averrhoa carambola）绿色食品基地不同土质、不同树龄的土壤样品及果实样品重金属元素Cd、Hg、Cu、Pb、As、Cr含量的检测,分析杨桃果实对土壤重金属元素的吸收与富集作用。结果表明：①果园土壤pH≤5．50,为酸性土壤,杨桃果园土壤和鲜果中的重金属含量均符合我国水果绿色食品生产的质量要求;②杨桃对土壤重金属的吸收因土壤质地和重金属元素的种类不同而异;③杨桃对重金属元素的富集,以Cd元素为最强,富集系数高达0．947,各种重金属的富集系数按大小排序为：Cd（0．947）〉Hg（0．098）〉Cu（0．023）〉Pb（0．003）〉As（0．001）：Cr（0．001）。     

The concept of the genus Ulothrix (Chlorophyta) strengthened by comparative cytology

The revelation of the ultrastructure of the pyrenoid, flagellar apparatus and mitosis/cytokinesis in the green algal genus Ulothrix, in its traditional broad sense, resulted in the assignment of species to three newly defined green algal classes. The largest group consisting of 11 species (including the type species Ulothrix tenuissima) is classified in the Ulvophyceae, the species U. verrucosa and U. crenulata are transferred to the genus Klebsormidium in the Charophyceae while Ulothrix species with pointed apical cells (e.g. U. belkae) appear to belong to the Chlorophyceae. It is shown that cytokinesis in Ulothrix sensu stricto may vary from a strict furrowing mechanism in U. mucosa to a pattern in which the centripetal ingrowth is combined with a cell plate-like structure in U. palusalsa and U. zonata. Based on the growth habit, the type of life history and the ultrastructural features pertaining to cytokinesis and the flagellar apparatus, phylogenetic trends are suggested for the Ulotrichales sensu lato.     

浒苔(Enteromorpha prolifera)藻体发育的显微观察

通过显微镜观察以及石蜡切片法观察了浒苔属浒苔藻体的发育过程,阐述了浒苔从孢子释放到形成成熟藻体这一发育过程的显微特征。结果表明:浒苔孢子由成熟体细胞分化发育而成,每个成熟体细胞可形成10～30个孢子;孢子首先分裂为2细胞结构,2细胞具有明显的极性,基细胞发育成为假根,顶端细胞不断进行横分裂形成丝状体;丝状体顶端以下细胞通过纵分裂形成管状叶状体,顶端细胞始终保持横分裂;纵分裂分为切向分裂与径向分裂,切向分裂增加管状叶状体管周细胞数从而使管体增大,径向分裂形成管外壁突起细胞,最终发育为分枝;管状叶状体管腔内部有绒毛状的突起及糖蛋白成分的网架结构;当管状叶状体管周细胞达到30～50h,管腔内部突起消失,网架结构收缩拉紧,管壁细胞贴近形成片状叶状体;整个浒苔藻体始终保持极性发育。     

Isolation,Growth, Ultrastructure,and Metal Tolerance of the Green Alga,Chlamydomonas acidophila (Chlorophyta)

An acidophilic volvocine flagellate, Chlamydomonas acidophila (Volvocales) that was isolated from an acid lake, Katanuma, in Miyagi prefecture, Japan was studied for growth, ultrastructural characterization, and metal tolerance.

Chlamydomonas acidophila is obligately photoautotrophic, and did not grow in the cultures containing acetate or citrate even in the light. The optimum pH for growth was 3.5-4.5. To characterize metal tolerance, the toxic effects of Cd, Co, Cu, and Zn on this alga were also studied. Effective metal concentrations, which limited the growth by 50%, EC₅₀ were measured, after 72h of static exposure. EC₅₀s were 14.4 μM Cd²⁺, 81.3 μM Co²⁺, 141μM Cu²⁺, and 1.16 mM Zn²⁺ for 72 h of exposure. Thus, this alga had stronger tolerance to these metals than other species in the genus Chlamydomonas.