Development of an immunoassay to detect insect contamination of microalgal products

While the insect fragment count is currently the primary test used for assessing insect contamination of food products, this technique is very problematical for assaying microalgal materials. An account is given of a new immunoassay technique,which is based on an enzyme-linked immunosorbent assay(ELISA) detection of insect myosin and which provides a rapid and convenient means of quantitatively determining the amount of insect contamination in algal product samples with a high degree of replicability. Up to 30 samples can be tested in duplicate in 2.5–3 h. Experiments were carried out with a variety of common contaminant insects of algal products, using various life stages, including Corixidae, Ephydridaeand Chironomidae using both Spirulina (Arthrospira) and Chlorella as typical algal materials. As little as one insect per 50 g sample can readily be detected, with excellent correlation (r² = 0.99) between the number of insects present and the color produced. A matrix analysis to determine the ruggedness of the immunoassay was carried out following the protocols of the AOAC International and established that minor departures in seven variables from the standard assay resulted in no substantial differences. The insect myosin assay offers a quantitative and reliable means for assessing insect contamination of algal materials and should be considered for adoption as a standard method for this type of product. This revised version was published online in August 2006 with corrections to the Cover Date.     

HPLC-analysis of algal pigments: comparison of columns,column properties and eluents

The effects of columns (Nucleosil C₁₈ODS, MZ-PAH, YMC-PACK C₃₀), column properties (inner diameters of 4 mm, 3 mm and 2 mm, pore-width 10 nm and 30 nm) and eluents (methanol, acetonitrile, acetone, water) were tested on the separation of algal pigments. The length of columns was 250 mm and particle size was 5 μm. Flow rates and gradients were adjusted to optimize peak separation; remaining chromatographic conditions were kept constant. The resolution of chromatographic systems was tested with pigment standards and various algal cultures. Total flow rate and retention times decreased with decreasing inner diameter, whereas pressure, sensitivity and peak-width increased. Pore width had negligible effects on the chromatographic separation of pigments under the test conditions. Only with acetonitrile as eluent were all the taxonomically important pigments resolved adequately: zeaxanthin (Cyanophyceae), lutein (Chlorophyceae), fucoxanthin (Bacillariopyceae), alloxanthin (Cryptophyceae), peridinin (Dinophyceae).     

Bryophyte evolution and geography

The three extant Divisions comprising the bryophytes extend, as fossils, well back into Palaeozoic time. Bryophyte origin is part of the rise of terrestrial, vascularized, plants with sporopollenin-walled spores in the Silurian. Before the end of Carboniferous time, bryophyte lines were widely present. Separation of Gondwana and Laurasia by the Permian Tethys Sea and subsequent widespread desert episodes fragmented an already diversified bryoflora subjecting it to intense selective pressure. The cool, mesic climate of southern Gondwana provided a refugium for austral bryophytes. Warmer and drier climates of the Permo-Triassic Laurentian-Laurasia favoured drought-adapted or niche-specific groups creating marked systematic discontinuities. The Angaran wet, probably cool, temperate region provided refuge for basic stock for much of today's rich holarctic and wet ‘tropical’ bryofloras. Climatic changes, correlated with tectonic events and the rise of angiosperms, opened habitats favourable for a diversity explosion. Despite demonstrated potential for long-distance dispersal, modern distributions are mostly linked with total floras or establishment on islands prior to niche saturation. Remnants of Gondwanan bryoflora persist in high southern latitudes as disjunctions with the possibility that the folded ranges of the African Cape have been an insular fragment at higher latitudes becoming attached shortly after angiosperm diversification. Floras of southern India and east Africa have common features but the Himalayan flora shows evidence that the Gondwanan flora of the Indian plate was lost during the movement through desert and tropical latitudes; neotropical and palaeotropical floras are distinctive. Much of the northern Australian bryoflora is recently Malesian-derived while the southeast shows strong austral influence and commonality with New Zealand. Tropical Pacific island floras are mostly Malesian-derived but with both holarctic and austral elements present as in Hawaii and the Society Islands. Holarctic bryoflora is circum-polar with temperate areas of Euro-American and far eastern elements floristically bound by disjunct and vicariad species. Kroeber Coefficients of Correlation differ as Pacific island floras are compared and Guttman-Lingoes Smallest Space Coordinates indicates floristic subgroups within Polynesia. Although these and other mathematical treatments yield potentially promising results, the methods are yet unrefined and there is some uncertainty whether characteristics of numbers or of organisms are implicit in the summations.     

Comparison of a lipophilic cation and microelectrodes to measure membrane potentials of the giant-celled algae,Chara australis (Charophyta) andGriffithsia monilis (Rhodophyta)

Summary The vacuolar equilibrium potential of the lipophilic cation TPMP⁺ (triphenyl methyl phosphonium) in the giant algaeChara australis andGriffithsia monilis was directly measured. The TPMP⁺ equilibrium potential was approximately 100mV less negative than the measured vacuolar electrical potential. Thus TPMP⁺ does not act as a probe of the vacuolar electrical potential and appears to be extruded against an electrochemical gradient. Measurement of the plasmalemma equilibrium potential of TPMP⁺ showed that extrusion of TPMP⁺ apparently occurred at both the tonoplast and plasmalemma inChara and at the plasmalemma inGriffithsia. It is concluded that TPMP⁺ cannot be used as a membrane potential probe inChara orGriffithsia.     

Absolute configuration of heteroxanthin and diadinoxanthin

The absolute configurations of heteroxanthin ((3S,5S,6S,3′R)- 7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,5,3′,6′-tetrol) ex Euglena gracilis and of diadinoxanthin ((3S,5R,6S,3′R)-5,6-epoxy-7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,3′-diol) from the same source have been established by chemical reactions, hydrogen bonding studies, ¹H NMR and CD. Two previously unknown carotenoids (artefacts?) from Trollius europaeus, assigned the structures (3S,5S,6S,3′S,5′R,6′R)-6,7-didehydro-5,6,5′,6′-tetrahydro-β,β -carotene-3,5,6,3′,5′-pentol and its 5R epimer, served as useful models.     

MEASUREMENTS OF PHYTOPLANKTON-PROTEIN CONTENT WITH THE HEATED BIURET-FOL1N ASSAY1,2

The heated biuret-Folin method for determining protein consistently measures 90% of the total nitrogen of filtered algae samples as protein-N without the need of mechanical disruption as long as the heating period in biuret is 100 min at 100 C. Data indicate this protein assay measures total protein on all species tried and for naturally occurring mixtures of species plus detritus. Dilute algal suspensions with as little as 0.05 μg-atom particulate protein N.liter ^-1 can he concentrated by fltration on glass fiber filters to 1.0 μg-atom particulate protein-N per filter, the optimal amount of sample for a 5 ml volume of biuret. The filtered algae samples can be stored for several weeks frozen before assaying, if necessary.     

A reappraisal of the Palaeopantopoda with description of a species from the Jurassic

The Devonian fossil Palaeoisopus appears, in the light of recent evidence from newly found specimens, to be much nearer extant pycnogonids than previously surmised. The fossil record of the Pycnogonida is extended to the Jurassic on the basis of a long overlooked Solenhofen example. Most of the specimens ascribed to the common Solenhofen Phalangites cannot be pycnogonids, but it is possible that we are dealing with a complex of superficially similar fossils. A revision of the classification of the fossil pycnogonids (Order Palaeopantopoda) is suggested in the light of this new material.     

Shoreline algal wash as a factor in reed decline in Lake Constance-Untersee

This paper assesses the chemical and mechanical impact of algal wash (Cladophora, Spirogyra, Chara) upon the lakeside reed belt (Phragmites australis) using field mapping methods, bioassays with Scenedesmus acutus in batch culture, and field experiments. Heavy mats of filamentous algae are correlated with a reduction in number of the outermost reed stalks. The water pressed from decaying heaps of Cladophora and Spirogyra reduced the growth rate of Scenedesmus significantly, but mats from Chara did not. It is assumed that the toxic substance is an organic compound. In field experiments the detrimental effect could not be clearly evidenced. The reasons for this are discussed. It is concluded that mechanical impact is of major importance.     

Predominance of picoplankton and nanoplankton in eutrophic Calder Lake

A study was conducted to examine factors regulating the biomass of algal picoplankton in Calder Lake, a small eutrophic lake in southern New York state. A particular focus was a current paradigm which suggests that larger cells may dominate in nutrient-rich waters, while smaller cells may predominate only in oligotrophic waters. Over two years, phytoplankton biomass consisted predominantly (74% on average) of very small organisms; nanoplankton (<20 to 2 µm: 39%) and picoplankton (<2 µm to 0.2 µm: 35%), despite the presence of surface blooms of colonial cyanobacteria (Microcystis aeruginosa, Anabaena limnetica), and dense metalimnetic populations of the dinoflagellate Ceratium hirundinella. This dimictic system is characterized by relatively high levels of total P (max = 85, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmiEayaara% aaaa!3702!\[\bar x\] = 9.7 µg P/L), inorganic P (max = 26, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmiEayaara% aaaa!3702!\[\bar x\] = 4.5 µg P/L), and total inorganic N (max = 285, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmiEayaara% aaaa!3702!\[\bar x\] = 85 µg P/L), but larger forms were rarely the most abundant. Unlike some marine systems, greater abundance of algal picoplankton was not associated with deeper strata (low light), or warmer temperatures. Data suggest that midsummer nutrient limitation, especially P-limitation, favors the development of pico- and nanoplankton in the limnetic zone of eutrophic lakes.     

Organization of macroalgal assemblages in the Northeast Pacific: the assumption of homogeneity and the illusion of generality

Evidence for the geographic generality of the causes of intertidal zonation and the indirect effects of a keystone predator, the sea otter, on subtidal kelp assemblages was examined. Most research on intertidal algal assemblages has been done at a few protected sites where zonation is distinct. Surveys of wave-exposed intertidal sites in central and northern California show that assemblage structure is highly variable. This indicates that our present understanding of assemblage organization, including the effects of mussel-algal interactions, may not be widely applicable. Surveys of kelp forest habitat along the entire coast of California suggest that deforestation by sea urchins is uncommon in the absence of sea otters. These examples indicate that the generality of commonly accepted causes of algal assemblage structure in the Northeast Pacific may be an illusion based on assumptions of environmental homogeneity.