Bacterial removal of chromium (VI) and (III) in a continuous system

The capacity of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to reduce different concentrations of hexavalent chromium in shake flask cultures has been investigated. A. ferrooxidans reduces 100% of chromium (VI) at concentrations of 1, 2.5 and 5 ppm, but in the presence of 10 ppm only 42.9% of chromium (VI) was reduced after 11 days of incubation. A. thiooxidans showed a lower capacity to reduce this ion and total reduction of chromium (VI) was only obtained for concentrations of 1 and 2.5 ppm, whereas 64.7% and 30.5% was reached for 5 and 10 ppm, respectively, after 11 days. A continuous flow mode system was subsequently investigated, in which A. thiooxidans was immobilized on elemental sulphur and the acidic medium obtained was employed to solubilize chromium (III) and to reduce chromium (VI) present in a real electroplating waste [30% of chromium (III) and 0.1% of chromium (VI)]. The system enabled the reduction of 92.7% of hexavalent chromium and represents a promising way to treat this type of waste in the industry.     

Lasioglossum (Dialictus) tenax (Sandhouse) (Hymenoptera: Halictidae) as a solitary sweat bee

Summary Nine nests ofLasioglossum (Dialictus) tenax were excavated near Calgary, Alberta, Canada over a time period encompassing the entire brood production period in 1988. Each nest contained a maximum of one active adult female, nest productivity peaked in mid July, protandry was noted and no significant size difference between foundresses and the earlier emerging females was detected. These data suggest that this species is solitary. These results are compared with data for the sympatrically nesting eusocial speciesL. (D.) laevissimum.     

Temperature response of trehalase from a mesophilic (Neurospora crassa) and a thermophilic (Thermomyces lanuginosus) fungus

The purified trehalases of the mesophilic fungus, Neurospora crassa, and the thermophilic fungus, Thermomyces lanuginosus, had similar temperature and pH optima for activity, but differed in molecular weight, electrophoretic mobility and Michaelis constant. At lower concentration, trehalases from both fungi were inactivated to similar extent at 60°C. While purified trehalase of T. lanuginosus was afforded protection against heat-inactivation by proteinaceous protective factor(s) present in mycelial extracts, by bovine serum albumin and by casein, these did not afford protection to N. crassa trehalase against heat inactivation. Both trehalases exhibited discontinuous Arrhenius plots with temperature of discontinuity at 40°C. The activation energy calculated from the slope of the Arrhenius plot was higher for the T. lanuginosus enzyme. The plots of apparent K _m versus 1/T for trehalases of N. crassa and T. lanuginosus were linear from 30° to 60°C.The results show that purified trehalases of the mesophilic and the thermophilic fungus are distinct. Although, these exhibit similar thermostability of their catalytic function at low concentration, distinctive thermal stability characteristics of thermophilic enzyme become apparent at high protein concentration. This could be brought about in the cell by the enzyme itself, or by other proteins.     

Experimental Exposures of Boreal Toads (Bufo boreas) to a Pathogenic Chytrid Fungus (Batrachochytrium dendrobatidis)

One of the major causes of worldwide amphibian declines is a skin infection caused by a pathogenic chytrid fungus (Batrachochytrium dendrobatidis). This study documents the interactions between this pathogen and a susceptible amphibian host, the boreal toad (Bufo boreas). The amount of time following exposure until death is influenced by the dosage of infectious zoospores, duration of exposure, and body size of the toad. The significant relation between dosage and the number of days survived (dose-response curve) supports the hypothesis that the degree of infection must reach a particular threshold of about 10⁷–10⁸ zoosporangia before death results. Variation in air temperature between 12°C and 23°C had no significant effect on survival time. The infection can be transmitted from infected to healthy animals by contact with water containing zoospores; no physical contact between animals is required. These results are correlated with observations on the population biology of boreal toads in which mortalities associated with B. dendrobatidis have been identified.     

Daphnia (Ctenodaphnia) hispanica sp. nov., a new daphnid (Cladocera) from Spain

Daphnia (C.) hispanica n. sp. has thoracic limbs of A D. (C.) atkinsoni type and is very similar toD. chevreuxi Richard, 1896. With this speciesD. (C.) hispanica shares the presence of a soft accessory seta on the outer side of the trunk of the first thoracic limb, apparently unique among the genusDaphnia. Although other morphological characteristics are very similar in this two species, a detailed comparison reveals that they can easily be separated as different species. The most useful features in differentiating both species are:D. (C.) hispanica has a dorsal crest in the head, its rostrum is longer, its accesory seta of the first thoracic limb is more developed, the juveniles are not helmeted and its male postabdomen lacks individual denticles on the anal and preanal margin.The new species is, up to now, restricted to Spain and inhabits the temporary and low mineralized waters of the steppe regions.     

Pearl bodies of Cayratia japonica (Thunb.) Gagnep. (Vitaceae) as alternative food for a predatory mite Euseius sojaensis (Ehara) (Acari: Phytoseiidae)

On the young leaves, shoots, and buds of Cayratia japonica (Thunb.) Gagnep. (Vitaceae), we observed nutritious bodies called pearl bodies and hypothesized that they are utilized by generalist predators as alternative foods. Some ambulate organisms consume pearl bodies in the wild and the predatory mite Euseius sojaensis (Ehara) (Acari: Phytoseiidae) was considered as a primary candidate. Pearl bodies promoted E. sojaensis settlement on C. japonica leaves and E. sojaensis could prey on the phytophagous mite Tetranychus kanzawai Kishida (Acari: Tetranychidae) when the predators settle on a leaf before the prey. In addition, the presence of pearl bodies did not reduce predation of E. sojaensis on T. kanzawai. This was seemingly because food quality of T. kanzawai was higher than pearl bodies. These results implied that pearl bodies on C. japonica leaves are utilized by E. sojaensis as alternative foods.     

Comparison of auditory sense organs in parasitoid Tachinidae (Diptera) hosted by Tettigoniidae (Orthoptera) and homologous structures in a non-hearing Phoridae (Diptera)

The dipteran parasitoids Therobia leonidei and Homotrixa alleni (Tachinidae) use acoustic cues to locate their calling tettigoniid (Ensifera, Orthoptera) hosts. The sexually dimorphic tympanal organs of both fly species are located at the prosternum. For comparison a homologous chordotonal organ in the non-hearing fly Phormia regina, Meigen (Phoridae) is also described. The scolopidial sense organs of the ears have approximately 180 sensory cells in Th. leonidei and 250 cells in H. alleni. Interspecific analysis indicates that the cell number and arrangement might be genus specific in Tachinidae. The mononematic scolopidia, each with one sensory cell, are of different sizes and insert at the tympanal membrane. Large scolopidial units (diameter of sensory cells up to 50 μm) extend longitudinally from the centre of the sensory organ towards the ligament, whereas small units (sensory cell diameter up to 10 μm) are arranged sequentially within the sensory organ. This arrangement is discussed to be a possible basis for frequency discrimination. The ultrastructure of the scolopidia is similar in the hearing and non-hearing flies. In both groups, the majority of scolopales has a diameter from 2 to 2.9 μm, although hearing species have additionally wider scolopales. The homologous chordotonal organ of Ph. regina consists of approximately 55 sensory cells of uniform direction. The data are discussed in comparison to the ears of other Diptera.     

Ecology of Potamanthus myops (Walsh) (Ephemeroptera: Potamanthidae) in a Michigan stream (USA)

The ecology of Potamanthus myops (Potamanthidae) was examined for a one year period in a central Michigan fourth order stream. Lowest nymphal densities (4.7 m^-2) occurred in mid-summer after adult emergence, while highest densities were found during late summer and fall (68.0 m^-2 and 66.2 m^-2) after the new cohort had hatched. Biomass was the inverse of density with highest values, 67.7 mg m^-2, just prior to peak adult emergence in June and lowest in late summer (16 mg m^-2). Nymphs maintained a contagious spatial distribution with k values ranging between 0.19 and 1.40. P. myops nymphs fed mostly on detritus (96.8%), placing them in the collector-gatherer functional group. Nymphs were always found in erosional zones associated with rock substrate. Nymphs used their mandibular tusks for positioning themselves beneath rocks, while also appearing to use them for defensive purposes.     

The tapetum inSchizaea pectinata (Schizaeaceae) and a comparison with the tapetum inPsilotum nudum (Psilotaceae)

A combination tapetum consisting of a cellular, parietal component and a plasmodial component occurs inSchizaea pectinata. A single, tapetal initial layer divides to form an outer parietal layer which maintains its cellular integrity until late in spore wall development. The inner tapetal layer differentiates into a plasmodium which disappears after the outer exospore has developed. In the final stages of spore wall development, granular material occurs in large masses and is dispersed as small granules throughout the sporangial loculus. No tapetal membrane develops. Comparisons are drawn with the combination tapetum found inPsilotum nudum.     

Tool use by a red howler monkey (Alouatta seniculus) towards a two-toed sloth (Choloepus didactylus)

Among New World monkeys, spontaneous tool use and object manipulation are commonly descirbed inCebus species only. We report here an occurrence of tool manipulation by a wild male red howler monkey (Alouatta seniculus), observed using a stick to softly but repeatedly hit a two toed sloth (Choloepus didactylus) resting in the same tree. The ecological context of this unusual behavior for this quiet species generally showing very little manipulative propensity is discussed.     

Relationship between Contents of Chlorophyll (a+b) (SPAD values) and Nitrogen of Some Temperate Grasses

In a field experiment the chlorophyll (a+b) (SPAD readings) and nitrogen contents of three grass species (Festuca arundinacea Schreb., Lolium perenne L., and Lolium multiflorum Lam.) and three intergeneric hybrids of Festuca pratensis Huds. × Lolium multiflorum Lam. and Festuca arundinacea Schreb. × Lolium multiflorum Lam. were measured. Close relationships were found between SPAD readings and nitrogen leaf content (r ² = 0.873^** 0.491^** and 0.938^**) for the 1^st, 2^nd, and 3^rd cut, respectively. SPAD readings and N contents were closely correlated (r = 0.836^**) confirming that SPAD measurements could be used in grass selection and/or breeding for high N concentration in herbage. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sedum surculosum andS. jaccardianum (Crassulaceae) share a unique 70 bp deletion in the chloroplast DNA trnL (UAA)-trnF (GAA) intergenic spacer

TrnL (UAA)-trnF (GAA) chloroplast DNA spacer sequences of three species ofMonanthes, Sedum surculosum (=Monanthes atlanticum) andS. jaccardianum were compared.S. surculosum, the systematic position of which has been disputed ever since its discovery, shares a phylogenetically highly significant 70 bp deletion withS. jaccardianum. In addition to this large deletion the two Moroccan species ofS. ser.Monanthoidea differ in three more indels as well as in four nucleotide substitutions from the species ofMonanthes. These data render strong support for the monophyly ofS. ser.Monanthoidea andMonanthes. Spacer length in seven species and one subspecies ofMonanthes is relatively uniform.     

Pollination by a hugging mechanism inVigna vexillata (Leguminosae-Papilionoideae)

The pollination ofVigna vexillata (Leguminosae-Papilionoideae) by a carpenter bee,Xylocopa gualanensis (Hymenoptera-Anthophoridae) was studied in a secondary vegetation in Costa Rica. The bees were observed foraging onV. vexillata only in early mornings. Visits on individual flowers lasted about 7–8 seconds. Flower—pollen vector interactions are described and illustrated. By its pressure on the left-hand wing- and keel-petal in the asymmetrical flower, the weight of the bee causes the upper bearded part of the style along with the upper free parts of the stamens to slip out of the rigid keel-beak, hugging the bee over the dorsal part of its head and thorax. The occurrence of nototribic pollination inVigna and related genera is discussed.     

Aurantiosporium,a new genus forUstilago subnitens (Ustilaginales)

A new genus,Aurantiosporium Piepenbring, Vánky & Oberwinkler (Ustilaginales), is proposed for the smut speciesUstilago subnitens Schröter & Hennings onScleria melaleuca Reichb. The soral morphology, teliospore development, the ultrastructure of the teliospore wall and teliospore germination ofAurantiosporium subnitens, studied on collections from Costa Rica, are described for the first time. The character set ofA. subnitens including intercellular teliospore development, spores in irregular groups and light coloured spore walls with numerous layers in TEM is neither known fromUstilago norCintractia nor any other smut species.Part 113 in the series Studies inHeterobasidiomycetes from the Botanical Institute, University of Tübingen.     

Peratanthe is a synonym of Nertera (Rubiaceae, Anthospermeae)

The two species ofPeratanthe, a genus allegedly endemic to the greater Antilles, are shown to be entirely within the variation range ofNertera granadensis (L.f.) Druce var.granadensis, a widespread, often weedy species.     

Role of cooperative H(+)/e(-) linkage (redox bohr effect) at heme a/Cu(A) and heme a(3)/Cu(B) in the proton pump of cytochrome c oxidase

It is a pleasure to contribute to the special issue published in honor of Vladimir Skulachev, a distinguished scientist who greatly contributes to maintain a high standard of biochemical research in Russia. A more particular reason can be found in his work (Artzabanov, V. Y., Konstantinov, A. A., and Skulachev, V. P. (1978) FEBS Lett., 87, 180–185), where observations anticipating some ideas presented in my article were reported. Cytochrome c oxidase exhibits protonmotive, redox linked allosteric cooperativity. Experimental observations on soluble bovine cytochrome c oxidase are presented showing that oxido-reduction of heme a/Cu_A and heme a ₃/Cu_B is linked to deprotonation/protonation of two clusters of protolytic groups, A₁ and A₂, respectively. This cooperative linkage (redox Bohr effect) results in the translocation of 1 H⁺/oxidase molecule upon oxido-reduction of heme a/Cu_A and heme a ₃/Cu_B, respectively. Results on liposome-reconstituted oxidase show that upon oxidation of heme a/Cu_A and heme a ₃/Cu_B protons from A₁ and A₂ are released in the outer aqueous phase. A₁ but not A₂ appears to take up protons from the inner aqueous space upon reduction of the respective redox center. A cooperative model is presented in which the A₁ and A₂ clusters, operating in close sequence, constitute together the gate of the proton pump in cytochrome c oxidase.Translated from Biokhimiya, Vol. 70, No. 2, 2005, pp. 220–230.Original Russian Text Copyright © 2005 by Papa.This revised version was published online in April 2005 with corrections to the post codes.     

Vanda longitepala (Orchidaceae): a new species from Burma

Summary   Vanda longitepala, a new species of orchid from northern Burma is described and discussed.     

Validating a Peruvian Scelochilus (Orchidaceae: Oncidiinae)

Scelochilus crucicornibus, which had been mentioned in the literature as a nomen nudum, is described and illustrated.