Erich Zeeck

Reproductive behaviour ofNereis diversicolor (Annelida: Polychaeta)

Nereis diversicolor O. F. Müller, collected on the tidal flats of the Jadebusen (North Sea, FRG) in autumn 1987 and 1988, was exposed to different temperatures in the laboratory. Results indicated that maturation was induced by temperatures above 6°C; spawning in early spring was synchronized by raising temperatures after a period of low temperatures in winter, and occurred mainly at new and full moon. During reproduction the female stays inside the burrow; the male releases sperm in front of it; the resultant larvae remain in the tube for 10 to 14 d protected by the female.

Cysteine-glutathione disulfide, the sperm-release pheromone of the marine polychaete Nereis succinea (Annelida: Polychaeta)

Summary. In the marine polychaete Nereis succinea (Frey & Leuckart 1847) a sex pheromone was isolated from the coelomic fluid of sexually mature females and identified by NMR studies and independent synthesis. This pheromone is released by the females during reproduction together with eggs and coelomic fluid into the free water column and induces sperm release of surrounding males. Its structure was ascertained as L-cysteine-glutathione disulfide. It exhibited a response threshold of 0.6 · 10−7 M.

Induction of swarming ofNereis succinea

Nereis succinea (Frey and Leuckart, 1847), collected in 1987 from the Weser estuary, FRG, was exposed to different temperatures in the laboratory. Metamorphosis to heteronereid stages, as well as swarming at a minimum temperature of 12°C, was induced by raising temperatures around the time of the new moon. Lunar periodicity was illustrated under natural temperature-programs, and at 16°C. An abrupt increase in temperature caused swarming to occur at different times of the lunar cycle.

Direct graphite furnace atomic absorption spectrometric determination of metals in sea water : application of palladium modifiers and a fractal approach to their analytical support

Abstract Sea water, like other high-salinity matrices, causes severe interferences in the direct determination of metals by graphite furnace atomic absorption spectrometry (GFAAS), even when Zeeman-effect background corrections is applied. A method for eliminating these interferences by the application of mixed modifier system of ammonium oxalate and tetraamminepalladium(II) chloride is presented. In particular these modifiers optimize the direct GFAAS determination of lead and manganese. For cadmium, however, only ammonium oxalate should be used as a modifier. The geometry of the microdistribution of palladium on the palladium-conditioned graphite platform was investigated in order to elucidate possible stabilizing effects of palladium on the analytes which were observed with the different modifiers. Fractal characteristics of the palladium elemental distribution were ascertained by a scanning electron microscope-energy-dispersive x-ray spectrometer image box-counting analysis. The fractal dimension [ D B (0) = 1.77 ± 0.04 and 1.81 ± 0.04] and electron microscopic investigations indicated differences in the structure of palladium deposits on the platform. These variations in the palladium geometry affect the analytes to a certain extent.

Uric acid : The sperm-release pheromone of the marine polychaete Platynereis dumerilii

In the marine polychaete, Platynereis dumerilii, reproductive behavior in the two sexes is synchronized by the consecutive discharge of male and female sex-specific pheromones. After the female releases the eggs into the free water column, immediate fertilization is achieved by several males circling around the eggs emitting sperm clouds. We report the isolation and identification of the sperm-release pheromone present in the coelomic fluid of sexually mature females. Each step in isolation was guided by bioassay. Isolation methods included extraction and solvent partitioning and separation methods included ultrafiltration and high-performance liquid chromatography. Uric acid was identified as the sperm-release pheromone that is discharged by the female with release of the eggs. The threshold concentration for sperm release by males was determined as 0.6 μM.

Sex pheromones in marine polychaetes V: a biologically active volatile compound from the coelomic fluid of female Nereis (Neanthes) japonica (Annelida Polychaeta)

Abstract In Nereis japonica, mature individuals leave their burrows to spawn at night near to the water surface. This process is timed by environmental factors such as temperature, daylength and lunar cycle to result in simultaneous spawning of a given population. The swarming behaviour which ensues is controlled by a bouquet of sex pheromones. A volatile compound, the ketone 3,5-octadiene-2-one was isolated and chemically characterized from the coelomic fluid of ripe, swarming females of N. japonica. During the reproductive behaviour of this species the ketone elicits an increase of swimming activity. This nuptial dance is characterized by swimming in circles prior to the release of gametes into the free water column. In N. japonica, the 3,5-octadiene-2-one functions in a very similar way to the sex pheromone 5-methyl-3-heptanone previously described in a number of nereid species. 5-methyl-3-heptanone is not detectable in N. japonica and behavioural assays revealed no significant stimulation by addition of this substance but an abrupt decrease in swarming activity. The importance of species specificity of chemical signals during reproduction of closely related nereid polychaetes is discussed.

EFFECTS OF THE VOLATILE FRACTION OF CRUDE OIL ON SPAWNING BEHAVIOUR OF NEREIDS (ANNELIDA, POLYCHAETA)

Abstract Volatile organic substances (VOS) in the volatility range inclusive of n -nonane and n -dodecane were derived by fractionated distillation from crude oil (EKO-FISK, North Sea) and their effects examined on two polychaete species, Platynereis dumerilii and Nereis succinea . In behavioural bioassays, ripe male heteronereids of both species were induced to perform their characteristic spawning behaviour. Male heteronereids which had been swimming at the water surface searching for the females were induced to swim in narrow circles when 0.3 ppm VOS fractions were added. This nuptial dance results in the release of gametes into the free water without contact with females. In contrast, no behavioural effect was observed in females.

Inosine, L-glutamic acid and L-glutamine as components of a sex pheromone complex of the marine polychaete Nereis succinea (Annelida: Polychaeta)

Summary. Pheromones released by male marine polychaetes Nereis succinea (Frey & Leuckart 1847) initiate egg release in mature females. Here we describe isolation and identification of components of the egg release pheromone bouquet from the coelomic fluid of sexually mature males. Inosine, L-glutamic acid and L-glutamine are identified to be components. Inosine, an egg release component, has a response threshold that is reduced eightfold by simultaneous presentation 1 : 1 with L-glutamic acid or L-glutamine. A fourth substance in the bouquet is tentatively identified as guanosine. The natural relative concentrations of all members of the pheromone bouquet and their mutual influence must still be explored.

Sex pheromones in marine polychaetes: Steroids from ripe Nereis succinea ☆

A number of neutral marine steroids such as desmosterol, campesterol, brassicasterol, gorgosterol, and other trace steroids were isolated from the coelomic fluid of ripe Nereis succinea and checked for biological activity as sex pheromones on swarming specimens of Platynereis dumerilii and Nereis succinea. No significant influence of synthetic gorgosterol or a natural extract of gorgosterol or the other identified steroids on the swarming behavior was observed.

Volatile compound from the coelomic fluid of Nereis succinea: biological activity as sex pheromone

Summary Volatile compounds in the coelomic fluid of ripe Nereis succinea (Frey & Leuckart 1847) were isolated by using a closed loop stripping technique and identified by GC-MS. One major compound is the sex pheromone of the closely related species Platynereis dumerillii, 5-methyl-3-heptanone. This substance increases the swarming activity during the nuptial dance reproductive behaviour and induces the males to release a very small cloud of sperm.