Mating behaviour and evidence for a female released courtship pheromone in the signal crayfish Pacifastacus leniusculus.

The mating behaviour of the signal crayfish, Pacifastacus leniusculus (Dana), has been categorised into seven distinct stages: orientation; contact; seizure; turning; mounting; spermatophore deposition; and dismounting. These categories were used in the development of a bioassay to test whether mature females release a sex pheromone during the breeding season to which males respond. Water conditioned by 1) mature females (MF water), 2) immature females (IF water) and 3) freshwater (C water), were injected through standard aquarium air-stones into tanks containing mature males. The behaviour of the male was recorded on video for 15 minutes before and after injection of each test water. The time that the males spent exhibiting the three behavioural categories of 'quiescent,' 'motile' and 'handling' of the air-stone, were recorded. 'Handling' of the air-stone included the mating behaviours of seizure, mounting, and spermatophore deposition onto the surface of the air-stone. Males exposed to MF water exhibited significantly increased levels of motile activity and handling behaviour, than males exposed to C water or IF water. These results demonstrate for the first time the presence of a sex pheromone, released during the breeding season by mature females, that stimulates courtship and mating behaviour in male P. leniusculus.

Factors influencing spawning and pairing in the scale worm Harmothoe imbricata (Annelida: Polychaeta).

Endocrine and environmental factors control reproduction of the polynoid scale worm Harmothoe imbricata. We confirmed that the rate of vitellogenesis was greater in winter specimens transferred from ambient regimes of photoperiod and temperature to a light:dark (LD) photoperiod of 16:8 at 10 degrees C and showed that the number of females spawning was significantly greater than for those transferred to LD8:16 at 10 degrees C. The endocrine mediation of this response was investigated using prostomium implantations. Significantly more LD8:16 females implanted with prostomia from LD16:8 conditioned females spawned than LD8:16 females implanted with LD8:16 prostomia. Females without prostomia failed to spawn. LD16:8 exposure may increase levels of a possible "spawning hormone" in the prostomium. Spawning proceeded in these LD16:8 females and allowed spawning to occur in LD8:16 females implanted with LD16:8 prostomia. In LD8:16 prostomia, titers of the spawning hormone reached the threshold in significantly fewer individuals, so that significantly fewer females implanted with LD8:16 prostomia spawned. Using Y-maze choice chambers, pair formation was shown to be under pheromonal control, with males being attracted to mature females but not to females carrying fertilized oocytes or to LD8:16 conditioned females. Production of this attraction pheromone can, therefore, be manipulated through photoperiodic control, suggesting a link between oogenesis, spawning, and pheromone production.

Making scents of sex underwater.

Sex and scents have long been associated. Musk, for example, is a sexual scent that has been used for many years in the perfume industry. In humans, the debate on the existence of sex pheromones continues, whereas in insects their role is well known. Through recent research, we are discovering that such chemicals are equally important in conveying sexual signals between aquatic animals.

Intermittent swimming in the spermatozoa of the lugworm Arenicola marina (L.) (Annelida: Polychaeta).

Motile spermatozoa of the polychaete Arenicola marina were observed to swim intermittently. On the basis of the behaviour of the flagellum, the quiescent periods can be classified into two main types. The first are those in which, although the generation of the flagellar wave appears to be initiated, its passage down the axoneme appears blocked. This results in the formation of an acute bend (of approximately 2.65 rad) in the proximal region of the flagellum with the remainder of the axoneme remaining straight. These have been termed Type I quiescent periods and are very similar to the "cane-shaped" configuration which has been described in the spermatozoa of some sea urchins. Sperm may also enter a Type II quiescent period, in which both the propagation and the generation of flagellar waves appears blocked. The flagellum of such sperm appears straight or slightly curved and they can remain in this configuration for several minutes. With increased intensity and duration of irradiation, the length of time spent in Type II quiescent period was increased significantly. Both types of quiescent period were (1) reduced in duration and frequency by deletion of calcium from artificial sea water (ASW); (2) either abolished or reduced in duration by the addition of 1 mM cadmium chloride to ASW. In addition, flagellar waveforms very similar to those displayed by spermatozoa in Type I quiescent periods could be induced (if only for a short time) by the addition of the divalent cation ionophore A23187 to ASW.(ABSTRACT TRUNCATED AT 250 WORDS)

The Role of Arachidonic Acid and Eicosatrienoic Acids in the Activation of Spermatozoa in Arenicola marina L. (Annelida: Polychaeta).

Partial purification of a sperm maturation factor (SMF) in the intertidal polychaete Arenicola marina has implicated arachidonic acid, an arachidonic metabolite, or a similar substance as the active factor from the prostomium. The effects of a number of 20-carbon fatty acids on inactive spermatozoa are investigated, and this reveals that only arachidonic acid and 8,11,14-eicosatrienoic acid cause sperm activation. The use of argentation thin-layer chromatography to separate fatty acids with varying degrees of unsaturation reveals a component in prostomial lipid extract, which co-migrates with eicosatrienoic acids. Investigations using cyclooxygenase and lipoxygenase result in a loss of sperm-activating properties of both prostomial extract and fatty acids. The use of cyclooxygenase and lipoxygenase inhibitors has no effect. Bovine serum albumin (BSA) reduces the sperm activating properties of both fatty acids and prostomial extract in a dose-dependant way. Additional purification procedures using: (a) organic solvents and aqueous buffers and (b) ODS silica cartridges, demonstrate that the active fraction of prostomial extract co-elutes at every step with the 8,11,14-eicosatrienoic acid standard. Gas chromatography of methyl esters of prostomial lipid extract reveals the presence of a peak with an identical retention time to the methyl ester of authentic 8,11,14-eicosatrienoic acid standard. The results described here provide strong evidence that the active SMF in prostomial homogenate is not a fatty acid metabolite but the parent acid 8,11,14-eicosatrienoic acid. These results could only be made unequivocal by full structural analysis using mass spectrometry and NMR following capillary gas-liquid chromatography.