Use of fluorescent lectin binding to distinguish Teladorsagia circumcincta and Haemonchus contortus eggs, third-stage larvae and adult worms

Lectin binding to carbohydrates on parasite surfaces has been investigated as a method of distinguishing adult worms, eggs and sheathed and exsheathed L3 of Teladorsagia circumcincta and Haemonchus contortus, economically important abomasal parasites in temperate climates. Both species were maintained as pure laboratory cultures of field isolates from New Zealand. Each of the four life cycle stages could be distinguished by the binding of at least one lectin: adult worms by Sambucus nigra agglutinin (SNA); eggs by peanut agglutinin (PNA), ConcavalinA and Lens culinaris agglutinin (LCA); exsheathed L3 by Griffonia simplicifolia-I lectin (GSL-I) and Lotus tetragonolobus lectin (LTL) and sheathed L3 by Aleuria aurantia lectin (AAL). The whole surface of both adult T. circumcincta and H. contortus strongly bound lectins specific for N-acetylglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), mannose and fucose, but the two species could be distinguished by SNA binding only to T. circumcincta. Eggs could be distinguished by the binding of mannose-specific PNA to H. contortus and GalNAc-specific LCA and PSA to T. circumcincta eggs. GalNAc, GlcNAc and mannose lectins bound to the cuticle and over the excretory pores of a large proportion of sheathed L3 of both species, but only the H. contortus surface had exposed fucose or sialic acid complexes. The distinguishing lectin for sheathed L3 was AAL, which did not bind to T. circumcincta, but bound weakly to the head region of all fresh H. contortus and to 50–90% after 3 months storage. The cuticle of exsheathed L3 was unresponsive to all 19 lectins, and any binding was restricted to the head and tail regions. L3 exsheathed after 2–4 months storage could be distinguished by the binding of GSL-I and LTL to H. contortus but not to T. circumcincta. Lectin binding could be a useful adjunct in identifying L3, but lacked the consistency to be definitive, whereas it could be further developed as a practical method of distinguishing parasitic nematodes at other stages in the life cycle, particularly the eggs

Projekt AAI, Auswirkungen der automatischen Informationsverarbeitung. Arbeitsvorhaben 3: Computerunterstuetzte Produktionsvorbereitung 2. Zwischenbericht

SIGLETIB: AC 9335 (Zwi2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Ecophysiology of photosynthesis in macroalgae

Macroalgae occur in the marine benthos from the upper intertidal to depths of more than 200 m, contributing up to 1 Pg C per year to global primary productivity. Freshwater macroalgae are mainly green (Chlorophyta) with some red (Rhodophyta) and a small contribution of brown (Phaeophyceae) algae, while in the ocean all three higher taxa are important. Attempts to relate the depth distribution of three higher taxa of marine macroalgae to their photosynthetic light use through their pigmentation in relation to variations in spectral quality of photosynthetically active radiation (PAR) with depth (complementary chromatic adaptation) and optical thickness (package effect) have been relatively unsuccessful. The presence (Chlorophyta, Phaeophyceae) or absence (Rhodophyta) of a xanthophyll cycle is also not well correlated with depth distribution of marine algae. The relative absence of freshwater brown algae does not seem to be related to their photosynthetic light use. Photosynthetic inorganic carbon acquisition in some red and a few green macroalgae involves entry of CO2 by diffusion. Other red and green macroalgae, and brown macroalgae, have CO2 concentrating mechanisms; these frequently involve acid and alkaline zones on the surface of the alga with CO2 (produced from HCO3-) entering in the acid zones, while some macroalgae have CCMs based on active influx of HCO3-. These various mechanisms of carbon acquisition have different responses to the thickness of the diffusion boundary layer, which is determined by macroalgal morphology and water velocity. Energetic predictions that macroalgae growing at or near the lower limit of PAR for growth should rely on diffusive CO2 entry without acid and alkaline zones, and on NH 4+ rather than NO3- as nitrogen source, are only partially borne out by observation. The impact of global environmental change on marine macroalgae mainly relates to ocean acidification and warming with shoaling of the thermocline and decreased nutrient flux to the upper mixed layer. Predictions of the impact on macroalgae requires further experiments on interactions among increased inorganic carbon, increased temperature and decreased nitrogen and phosphorus supply, and, when possible, studies of genetic adaptation to environmental change. © 2012 Springer Science+Business Media B.V