Proximate composition and elemental analysis in soft tissues of freshwater mussels (<Emphasis Type="Italic">Anodonta anatina</Emphasis>) from the Chashma Lake,River Indus Pakistan

Background

Aquatic invertebrates are playing an important role in assessment of the water contaminants and also serve as a major component of food chain. Freshwater mussels are considered to be the good bioindicator species of aquatic environment and widely used to determine the metals load.

Methods

Proximate composition and elemental analysis were carried out in edible (foot, mantle) and non-edible portion (gills) of freshwater mussels (Anodonta anatina) harvested from various site of Chashma Lake, River Indus Pakistan.

Results

The nutritional components were varied among the studied portion and muscular foot found to be the best part for consumption. Protein and fat contents were significantly higher in foot (15.90±0.88%, 1.19±0.26%) as compared to mantle (10.78±2.24%, 0.27±0.09%) and gills (6.44±1.22%, 0.53±0.15%) respectively. For the macro minerals mantle had high concentration of Ca (46838±984 mg/kg), Na (2706±343 mg/kg), P (6921±1063 mg/kg) and Mn (7207±1046 mg/kg) as compared to foot.

Conclusions

Heavy metals (Cd, Cu, Cr) concentration in edible portions were lower than the permissible limit by WHO whereas the concentration of Pb was slightly higher than the recommended value that might be the risk for the consumers. Being filter feeder gills accumulated the high concentration of all the metals and found to be the key portion for biomonitoring studies. Freshwater mussels of Chashma Lake Indus River are the rich source of protein and all the other micro and macro minerals therefore could be used as an excellent source of food.

     

Gibberellin-like activity in suspensors of Tropaeolum majus L. and Cytisus laburnum L.

Gibberellins in the embryo-suspensor system have been considered so far only in Phaseolus coccineus. We present in this report the localization of gibberellin-like substances in the suspensors of Tropaeolum majus L. and Cytisus laburnum L. The total gibberellin activity (expressed as gibberellic-acid equivalent in the -amylase bioassay) in 2000 suspensors (106 mg fresh weight; FW) of C. laburnum and in 600 suspensors (236 mg FW) of T. majus were 50.9 g g^-1 FW and 8.9 g g^-1 FW respectively.Abbreviation GA gibberellin     

Arsenic precipitation in the bioleaching of enargite by Sulfolobus BC at 70 °C

Enargite (Cu₃AsS₄) was leached at 70°C by Sulfolobus BC in shake-flasks. The highest copper dissolution (52% after 550 h of leaching) was obtained with bacteria and 1 g l^–1 ferric ion. In the absence of ferric ion, Sulfolobus BC catalyzes the bioleaching of enargite through a direct mechanism after adhesion onto the mineral surface. In ferric bioleaching, arsenic precipitated as ferric arsenate and arsenic remained associated to the solid residues, preventing the presence of a high dissolved arsenic concentration in the leaching solution. About 90% inhibition of bacterial growth rate and activity was observed for dissolved arsenic concentrations above 600 mg l^–1 for As(III) and above 1000 mg l^–1 for As(V). Arsenic-bearing copper ores and concentrates could be leached by Sulfolobus BC in the presence of ferric iron due to the favourable precipitation of arsenic ion as ferric arsenate, avoiding significant bacterial inhibition.     

Dispersal and size fractionation of embryogenic callus increases the frequency of embryo maturation and conversion in hybrid tea roses

Plant regeneration from embryogenic cells of two Rosa hybrida cultivars, Kardinal and Classy, was increased by dispersing embryogenic callus in liquid medium for 3 h followed by size-fractionation to isolate proembryogenic masses that were smaller than 530 m. Dispersed callus of three cultivars, Kardinal, Classy, and Tineke, produced 61–135 cotyledonary-stage embryos/100 mg fresh weight (FW) as compared to intact callus that had not been dispersed, which produced only zero to three cotyledonary-stage embryos/100 mg FW. Over 500 cotyledonary-stage embryos/100 mg FW callus developed from proembryogenic masses of Kardinal, Classy, and Tineke following 2 months of culture on solidified Murashige and Skoogs basal salts medium supplemented with 0.25% activated charcoal. Cotyledonary-stage embryos of Classy that developed from both dispersed callus and fractionated cells of various sizes showed a significantly higher conversion frequency to plants (28%) than cotyledonary-stage embryos isolated from intact callus (9%). The highest conversion frequencies for Kardinal (50–58%) occurred from cotyledonary-stage embryos that developed from dispersed callus and from the fraction of cells smaller than 850 m.Abbreviations BAP 6-Benzyladenine - FeEDDHA Ferric ethylenediamine di(o-hydroxyphenylacetate) - FW Fresh weight - PEMs Proembryogenic masses - PGRs Plant growth regulatorsCommunicated by S.A. Merkle     

Population structure,shell morphology,age and condition of the freshwater mussel Hyridella menziesi (Unionacea: Hyriidae) from seven lake and river sites in the Waikato River system

Populations of the freshwater mussel Hyridella menziesi were compared from six lakes and one river site along the Waikato River system, North Island, New Zealand. Estimated densities ranged from several hundred per square metre in Lake Taupo to less than one per square metre in Lake Karapiro. Length-frequencies were similar at all sites, with unimodal distributions and a notable absence of any individuals less than 20 mm long. The extent of shell erosion varied from sites where most mussels had less than 1% of the right valve affected (i.e., Ohakuri & Karapiro), to Lake Aratiatia where most shells had erosion over 1–20% of their surface. Taupo and Ohakuri mussels showed an unusually high incidence (over 50%) of internal shell abnormalities (including dulling, deformities and protuberances). Canonical discrimination based on shell length, height, width and weight clearly separated Taupo and Ohakuri mussels from all other sites, and ANCOVA on morphological characteristics confirmed significant differences between sites. Physical condition indices (based on dry flesh weight per shell weight and shell volume) showed an increasing downstream trend, but this was not significantly correlated with food availability (i.e., chlorophyll a concentration) because of unexpectedly low condition in lakes Ohakuri and Karapiro. Length v. age relationships contained considerable scatter and did not show between-site differences. Measured differences in external erosion, internal shell abnormalities and morphology were attributed to physical, chemical and biological factors. Use of mussels for environmental monitoring must take these background differences into account.     

Commensals of Mytilus galloprovincialis in the Black Sea: Urastoma cyprinae (Turbellaria) and Polydora ciliata (Polychaeta)

The intensity of infection of the mussel Mytilus galloprovincialis Lamarck in the Black Sea by the turbellarian Urastoma cyprinae (Graff), which lives on its gills, was found to be higher in larger hosts, reaching a maximum in mussels of 50–70 mm length. Greater numbers occured in mussels inhabiting a silty bottom than in cultivated mussels suspended above the bottom. Over the period 1982–1987, U. cyprinae was most numerous in winter and especially so in years that were colder. The spionid polychaete Polydora ciliata (Johnston) also infects M. galloprovincialis, burrowing into the shell. Young spionids of up to 1 mm length occured in mussels with a shell length of 35 mm. Numbers of this commensal reached a maximum in mussels of intermediate size.     

The effect of seasonality on oxidative metabolism in Nacella (Patinigera) magellanica

We studied the seasonal variation on aerobic metabolism and the response of oxidative stress parameters in the digestive glands of the subpolar limpet Nacella (P.) magellanica. Sampling was carried out from July (winter) 2002 to July 2003 in Beagle Channel, Tierra del Fuego, Argentina. Whole animal respiration rates increased in early spring as the animals spawned and remained elevated throughout summer and fall (winter: 0.09 ± 0.02 μmol O₂ h^− 1 g^− 1; summer: 0.31 ± 0.06 μmol O₂ h^− 1 g^− 1). Oxidative stress was assessed at the hydrophilic level as the ascorbyl radical content / ascorbate content ratio (A / AH⁻). The A / AH⁻ ratio showed minimum values in winter (3.7 ± 0.2 10^− 5 AU) and increased in summer (18 ± 5 10^− 5 AU). A similar pattern was observed for lipid radical content (122 ± 29 pmol mg^− 1 fresh mass [FW] in winter and 314 ± 45 pmol mg^− 1 FW in summer), iron content (0.99 ± 0.07 and 2.7 ± 0.6 nmol mg^− 1 FW in winter and summer, respectively) and catalase activity (2.9 ± 0.2 and 7 ± 1 U mg^− 1 FW in winter and summer, respectively). Since nitrogen derived radicals are thought to be critically involved in oxidative metabolism in cells, nitric oxide content was measured and a significant difference in the content of the Fe–MGD–NO adduct in digestive glands from winter and summer animals was observed. Together, the data indicate that both oxygen and nitrogen radical generation rates in N. (P.) magellanica are strongly dependent on season.     

Associational resistance of fouled blue mussels (<Emphasis Type="Italic">Mytilus edulis</Emphasis>) against starfish (<Emphasis Type="Italic">Asterias rubens</Emphasis>) predation: relative importance of structural and chemical properties of the epibionts

Several epibiotic species reduce starfish (Asterias rubens) preference for the blue mussel Mytilus edulis in the Baltic. The aim of this study was to reveal whether this associational resistance was caused by structural or chemical aspects of the different epibionts. To assess structural epibiont effects, an in situ experiment was conducted with unfouled mussels and mussels equipped with artificial epibionts (dummies) exposed to natural predation by A. rubens. The chemically inert dummies closely matched the structural properties of the locally common epibionts Balanus improvisus (barnacle), Ceramium strictum (red alga), Halichondria panicea (sponge), and Laomedea flexuosa (hydrozoan). Starfish fed indiscriminately in all treatments. Chemical effects of epibionts on the attractiveness of mussels for A. rubens were investigated by incorporating freeze-dried epibionts or mussel tissue into Phytagel pellets at natural concentrations. Starfish were allowed to choose among these structurally similar but chemically different prey items in an in vitro experiment. The predators exhibited significant preferences among the food pellets, which closely matched their preferences for corresponding natural mussel–epibiont associations. Thus, chemical aspects of epibionts appear to play a larger role in this associational resistance than do structural aspects. Implications of these indirect interactions for benthic communities are discussed.Communicated by H.-D. Franke     

上海市食用菌重金属污染状况的研究

本文通过对上海不同区域的金针菇、蘑菇、平菇、鸡腿菇及香菇5种常见鲜食用菌进行实地抽样,采用微波消解前处理,电感耦合等离子体质谱法(ICP-MS)测定食用菌中铅(Pb)、砷(As)、汞(Hg)、镉(Cd)的含量,考察鲜食用菌的重金属污染状况.研究结果表明,不同食用菌中重金属的污染状况随其种类和地域的不同而呈现显著差异.As、Pb、Cd和Hg在食用菌中的平均含量分别为0.177 mg/kg、0.094 mg/kg、0.082 mg/kg和0.004 mg/kg,均低于GB 2762-2012《食品安全国家标准食品中污染物限量》中的限量标准,说明上海市售鲜食用菌的重金属含量总体上是安全的.但在这5种食用菌中,部分蘑菇样品中的砷残留存在安全风险,样品超标率为27.3%;但进一步研究表明,超标蘑菇样品中无机砷占总砷的比例仅为4.4%~6.3%,最高含量仅为0.370 mg/kg,以无机砷含量替代总砷含量进行考察,则这些样品也是食用安全的.虽然在不同地区的食用菌中,这4种重金属的含量有显著差异,但均低于国标限定值,说明在上海市不同地区出售的食用菌总体上是安全的,可以放心食用.     

Anthraquinones production,hydrogen peroxide level and antioxidant vitamins in Morinda elliptica cell suspension cultures from intermediary and production medium strategies

The effects of medium strategies [maintenance (M), intermediary (G), and production (P) medium] on cell growth, anthraquinone (AQ) production, hydrogen peroxide (H₂O₂) level, lipid peroxidation, and antioxidant vitamins in Morinda elliptica cell suspension cultures were investigated. These were compared with third-stage leaf and 1-month-old callus culture. With P medium strategy, cell growth at 49 g l^–1, intracellular AQ content at 42 mg g^–1 DW, and H₂O₂ level at 9 mol g^–1 FW medium were the highest as compared to the others. However, the extent of lipid peroxidation at 40.4 nmol g^–1 FW and total carotenoids at 13.3 mg g^–1 FW for cultures in P medium were comparable to that in the leaf, which had registered sevenfold lower AQ and 2.2-fold lower H₂O₂ levels. Vitamin C content at 30–120 g g^–1 FW in all culture systems was almost half the leaf content. On the other hand, vitamin E content was around 400–500 g g^–1 FW in 7-day-old cultures from all medium strategies and reduced to 50–150 g g^–1 FW on day 14 and 21; as compared to 60 g g^–1 FW in callus and 200 g g^–1 FW in the leaf. This study suggests that medium strategies and cell growth phase in cell culture could influence the competition between primary and secondary metabolism, oxidative stresses and antioxidative measures. When compared with the leaf metabolism, these activities are dynamic depending on the types and availability of antioxidants.Abbreviations AQ Anthraquinone - DW Dry cell weight - FW Fresh cell weight - G Intermediary medium - M Maintenance medium - MDA Malondialdehyde - P Production medium - ROS Reactive oxygen species - TBA Thiobarbituric acid - t_d Doubling time     

Effect of nutrient supply on growth of blue mussels (Mytilus edulis) in a landlocked bay

The growth of blue mussels (Mytilus edulis) was studied in the landlocked bay Hopavågen in central Norway for 3 years, of which in 2 years (1998 and 1999) nutrients were added to increase the primary production. Nutrients (N:Si:P) were added daily from May to October in 1998 (molar ratio 15:5:4.1) and 1999 (molar ratio 16:8:1). The doses of nutrients correspond to 0.4 and 0.8 g P l^–1 day^–1 in 1998 and 1999 respectively. The growth of blue mussels (Mytilus edulis) in 1997 was followed at four depths (1, 2, 4 and 7 m). In 1998 and 1999 growth was followed at 2 and 10 m depths at four locations in Hopavågen and at a control station outside on the coast. The nutrient supply in 1998 only slightly increased the algal biomass (chlorophyll a), whereas mean daily primary production during the summer remained at the same level as the previous year. The increased nutrient supply in 1999 caused a nearly 50 and 100% increase in mean summer biomass and daily primary production, respectively. The growth of blue mussels in Hopavågen in 1997 and 1998 was within the same size range during the summer. In 1999 the shell length of blue mussels kept at 2 m depth was significantly higher than in the previous year at end of the growth season. The recorded growth was also significant higher than for mussels at 2 m depth at the control station. No difference in shell length was observed on mussels grown at 10 m depth in Hopavågen and in the control stations in 1998 and 1999. A higher tissue content was found in blue mussels grown at 2 m depth in Hopavågen, both in 1998 and 1999 when compared to the control groups. At 10 m depth no differences were recorded.     

Size-selective predation by roach (Rutilus rutilus) on zebra mussel (Dreissena polymorpha): field stuides

Summary Studies of predation by roach (Rutilus rutilus) on zebra mussel (Dreissena polymorpha) in a large, eutrophic lake showed that there was a clearly marked size threshold ( 160 mm SL) above which roach began to feed on mussels. Roach preying on various sizes of mussels selected them in proportions different from their abundance and accessibility in the habitat. The mean size of mussels ingested by roach of 220 mm and larger, which fed predominantly on Dreissena, closely followed the pattern expected for a constant ratio of mean prey size to mean predator mouth size = 0.59. To explain the size selection we applied an optimal foraging approach, based on the ability of different-sized fish to crush (cost) mussels of different sizes, and hence crushing resistance, and energy contents (benefit). We found that fish smaller than 160 mm, which showed no inclination to eat Dreissena, would only be able to take small mussels with a very high cost/benefit ratio. The real switch to Dreissena would be expected in fish of 230–240 mm that could take most of their prey from highly profitable, numerous, and easily accessible size classes while keeping the mean prey size at the optimal level relative to mean predator mouth size.     

Heavy metal and arsenic accumulating fern species as potential ecological indicators in As-contaminated abandoned mines

Ferns are good ecological indicators of arsenic accumulation in contaminated abandoned mines. The rhizomes of ferns were analyzed for arsenic and other heavy metals using inductively coupled plasma-mass spectrometry. In addition, we examined the ribulose-bisphosphate carboxylase (rbcL) gene isolated from the indigenous species of ferns at the pithead, tailings and soil sites in the vicinity of the Myoungbong abandoned mine, Republic of Korea. A search of the GenBank database revealed that the predicted amino acid sequence of this gene was homologous with 99% of Pteridium aquilinum As-2 (EU476184), 99% of Deparia petersenii As-6 (EU476188), 97% of Deparia lobatocrenata As-8 (EU476190), and 98% of Deparia conilii As-7 (EU476189). High concentrations of heavy metals (arsenic, 17.6 mg/kg in rhizomes and 2690 mg/kg in soil; copper, 17.1 mg/kg in rhizomes and 40.7 mg/kg in soil; cadmium, 2.9 mg/kg in rhizomes and 12.2 mg/kg in soil; lead, 41.9 mg/kg in rhizomes and 135 mg/kg in soil; zinc, 27.0 mg/kg in rhizomes and 172 mg/kg in soil) were found in P. aquilinum As-2 (EU476184) from the Myoungbong mine area, which may play an important role as ecological indicators of the contaminated areas.     

Habitat selection by wintering tufted ducks with special reference to their digestive organ and to possible segregation between neighboring populations

Habitat selection by tufted ducks (Aythya fuligula), a diving duck which swallows benthic prey organisms, was studied during winter at two neighboring lagoons (Lakes Nakaumi and Shinji, Honshu, Japan) which differ strongly in their benthic fauna and in their diving duck densities. The ducks fed overwhelmingly on the dominant bivalve found in each of the two lagoons, the mussel Musculista senhousia in L. Nakaumi and the clam Corbicula japonica in L. Shinji. In general, however, the ducks probably preferred the mussels to the clams because of: (i) their high (2.9 times) calorific content for their weight; (ii) their high digestibility; (iii) their greater accessibility; and (iv) their shorter handling time. An average tufted duck (850 g) was estimated to require 1.3 kg of mussels or 3.8 kg of clams to meet their daily energy requirements. As a result, the two wintering populations were estimated to consume 4970 t mussels and 4770 t clams during a single wintering season, amounting to some 20% of the standing clam crop. Throughout the winter the average gizzard weight (37 g), and gizzard–body mass ratio (4.2%) of the Lake Nakaumi population were half those of the Lake Shinji population (73 g, 8.1%, respectively), despite their significantly similar nutritive body condition (% body lipid > 12%). The need to maintain a specialized gizzard mass in order to be able to cope with the different prey species results in little opportunity for sampling movements of birds between lakes/prey types and as a result two subpopulations of ducks are indicated to be segregated.     

Plant regeneration from protoplasts isolated from embryogenic calli of the forage legume<Emphasis Type="Italic"> Astragalus melilotoides</Emphasis> Pall.

An efficient and reproducible protocol is described for the regeneration of Astragalus melilotoides protoplasts isolated from hypocotyl-derived embryogenic calli. Maximum protoplast yield (11.74±0.6×10⁵/g FW) and viability (87.07±2.8%) were achieved using a mixture of 2% (w/v) Cellulase Onozuka R10, 0.5% (w/v) Cellulase Onozuka RS, 0.5% (w/v) Macerozyme R10, 0.5% (w/v) Hemicellulase, and 1% (w/v) Pectinase, all dissolved in a cell protoplast wash (CPW) salt solution with 13% (w/v) sorbitol. First divisions occurred 3–7 days following culture initiation. The highest division frequency (9.86±0.68%) and plating efficiency (1.68±0.05%) were obtained in solid-liquid medium (KM8P) supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid, 0.5 mg/l 6-benzylaminopurine (BA), 0.2 mg/l kinetin, 0.2 M glucose, 0.3 M mannitol and 500 mg/l casein hydrolysate. Upon transfer to MS medium with 0.5 mg/l -naphthaleneacetic acid and 1-2 mg/l BA, the protoplast-derived calli produced plantlets via somatic embryogenesis (56.3±4.1%) and organogenesis (21.6±0.6%). Somatic embryos or adventitious shoots developed into well-rooted plantlets on MS medium without any plant growth regulators or supplemented with 3.0 mg/l indole-3-butyric acid, respectively. About 81% of the regenerants survived in soil, and all were normal with respect to morphology and growth characters.Abbreviations BA: 6-Benzylaminopurine - CH: Casein hydrolysate - CPW: Cell protoplast wash - 2,4-D: 2,4-Dichlorophenoxyacetic acid - FDA: Fluorescein diacetate - IBA: Indole-3-butyric acid - KIN: Kinetin - MES: 2-(N-morpholino) Ethanesulphonic acid - NAA: -Naphthaleneacetic acidCommunicated by A. Altman     

Transformation of <Emphasis Type="Italic">Saussurea medusa</Emphasis> for hairy roots and jaceosidin production

Axenically grown Saussurea medusa plantlets were inoculated with four Agrobacterium rhizogenes strains, and hairy root lines were established with A. rhizogenes strain R1601 in N6 medium. PCR and Southern hybridization confirmed integration of the T-DNA fragment of the Ri plasmid from A. rhizogenes into the genome of S. medusa hairy roots. In N6 medium, maximum biomass of the hairy root cultures was achieved [8 g (dry weight) per liter; growth ratio 35-fold] after 21 days of culture. The amount of jaceosidin extracted from the hairy root cultures was 46 mg/l (production ratio of 37-fold) after 27 days of culture. The maximum jaceosidin content obtained using N6 medium was higher than that obtained with Modified White, MS or B5 medium. In N6 medium, the tip segments were more efficient for hairy root growth and jaceosidin production than the middle and basal regions of the root.Abbreviations AS Acetosyringone - BA Benzyladenine - cef Cefotaxime sodium - DW Dry weight - FW Fresh weight - HPLC High-performance liquid chromatography - IAA Indole-3-acetic acid - km Kanamycin - NAA -Naphthaleneacetic acid - SDS Sodium dodecyl sulfate     

Dynamics of the phycotoxin domoic acid: accumulation and excretion in two commercially important bivalves

Batch cultures of the toxigenic diatomNitzschia pungens Grunow f.multiseries Hasle were fed to blue mussels (Mytilus edulis) and deep sea Atlantic scallops (Placopecten magellanicus) to elucidate conditions under which domoic acid (DA) was accumulated and excreted (depurated). Mussels accumulated the toxin to a maximum level of 13 g g^-1, at rates of 0.21 to 3.7 g h^-1 g^-1, dry weight. Accumulation efficiency (the proportion of accumulated DA to estimated net uptake) ranged from 1–5%. The highest filtration rate of 1.71 h^-1 occurred at concentrations of 4–8 × 10⁶ Nitzschia cells 1^-1 with no formation of pseudofeces. Depuration rates between fed and starved mussels over a 2 h test period were the same. The depuration rate of domoic acid was about 17% d^-1 and did not account for the low uptake efficiencies, so it is suggested that most of the DA is lost from mussels in the solution during the feeding process. Domoic acid accumulation in mussels was dependent on the amount of toxin available, which in turn was a function of the density and growth phase of theNitzschia population. Changes in filtration rate withNitzschia concentration and depuration rate with time can account for the DA levels of mussels collected during toxic episodes in Cardigan Bay, Prince Edward Island, Canada in 1988 and 1989.Scallops accumulated DA (0.39–1.3 g h^-1 g^-1, more slowly than mussels, however, accumulation efficiencies ranged from 5–100%. Filtration rates remained relatively low and constant at 0.081 h^-1. Scallops retained domoic acid longer than mussels, a fact which must be considered in the marketing of whole scallops for human consumption.     

Studies on chitin and calcification in the inner layers of the shell of Anodonta cygnea

Summary An orthorhombic structure -chitin, probably in the form of a chitin-protein complex, was identified in the matrix of the shell of Anodonta cygnea by X-ray diffraction. Aragonite crystals of pseudohexagonal symmetry were also found by a Lauegram on the nacreous layer of the shell. The orthorhombic structure of these two compounds together with the identical reticular spacing d₁₁₀ corroborate, in Anodonta cygnea, the indirect chitin-aragonite relationships already suggested for molluscan shells.Observations with SEM in the inner surface of the shell showed CaCO₃ crystals with irregular geometrical shapes in spring and summer and regular geometrical shapes in autumn and winter. The more elaborate aspect appearing in winter corresponds to an accurate hexagonal shape. This suggests that the observed variability may depend on the balance between calcium and hydrogen ions in the extrapallial fluid.Abbreviations OME outer mantle epithelium - SEM scanning electron microscopy     

Annual winter water level drawdowns limit shallow‐water mussel densities in small lakes

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Exceptions in patterns of arsenic compounds in urine of acute promyelocytic leukaemia patients treated with As<Subscript>2</Subscript>O<Subscript>3</Subscript>

Arsenic trioxide (As(III) in solution) has been shown to be the most active single agent in combating acute promyelocytic leukemia (APL). It is metabolized and excreted via urine as monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and As(V), along with excess As(III). In our study eight APL patients were treated (intravenously) with 0.15 mg As₂O₃/kg/day. During the therapy As(III) and its metabolites were followed in pre- and post-infusion urine using HPLC for separation followed by on-line detection using hydride generation-atomic fluorescence spectrometry. Five patients had a normal excretion pattern of residual arsenic compounds in morning pre-infusion urine, with 15–25 % of As(III), 35–55 % of DMA, 25–30 % of MMA and 1–5 % of As(V), while three patients showed unexpected exceptions from typical excretion patterns of arsenic compounds (i) a high DMA/MMA ratio (factor 5.3), (ii) severe As(III) oxidation (10.2 % As(III) converted to As(V)) or (iii) the presence of an excessive amount of As(III) (average 30.4 % of total arsenic). Intriguing was the occurrence of post-infusion oxidation of As(III) to As(V) observed in almost all patients and being especially high (>40 %) in patient with increased residual As(V). Results indicate that arsenic metabolites patterns can be unpredictable. Observed high levels of un-metabolised As(III) are a warning signal for side effects and for routine determination of arsenic metabolites during first days of treatment. High or low percentages of MMA or DMA did not show any observable effect on treatment results, while clear presence of post-infusion As(V) supports theoretical claims of in vivo oxidation (detoxification) of As(III) to As(V) associated with various metabolic processes.