Sperm storage influences the potential for spontaneous acrosome reaction of the sperm in the newt Cynops pyrrhogaster.

Sperm storage is supposed to influence sperm quality, although the details remain unclear. In the present study, we found that sperm stored in a sperm storage site, the vas deferens of Cynops pyrrhogaster, spontaneously undergo acrosome reaction following incubation in Steinberg's salt solution (ST). Percentages of acrosome-reacted sperm increased time-dependently to about 60% in 24 hr. The concentration of cyclic adenosine monophosphate (cAMP) was elevated after incubating sperm in ST, while dibutylyl cAMP induced an acrosome reaction. Chelating of extracellular Ca2+ suppressed the dibutylyl cAMP-induced acrosome reaction as well as spontaneous acrosome reaction in ST. These results suggest that cAMP elevation driven by Ca2+ influx can be a cue for spontaneous acrosome reaction. Relatively low Ca2+ concentration and pH in the vas deferens were sufficient to suppress spontaneous acrosome reaction within 1 hr. In addition, the cysteine rich secretory protein 2 gene was expressed in the vas deferens, indicating that it may be involved in the continuous suppression of spontaneous acrosome reaction. Sperm that underwent spontaneous acrosome reaction in ST was significantly increased when stored in the vas deferens for longer periods, or by males experiencing temperatures in excess of 12°C during hibernation conditions. Percentages of the spontaneously acrosome-reacted sperm were found to differ among males even though they were of identical genetic background. Taken together, C. pyrrhogaster sperm possess the potential for spontaneous acrosome reaction that does not become obvious in the vas deferens, unless promoted in correlation with sperm storage.

Distribution of serotonin and FMRF-amide in the brain of Lymnaea stagnalis with respect to the visual system.

Despite serotonin's and FMRF-amide's wide distribution in the nervous system of invertebrates and their importance as neurotransmitters, the exact roles they play in neuronal networks leaves many questions. We mapped the presence of serotonin and FMRF-amide-immunoreactivity in the central nervous system and eyes of the pond snail Lymnaea stagnalis and interpreted the results in connection with our earlier findings on the central projections of different peripheral nerves. Since the chemical nature of the intercellular connections in the retina of L. stagnalis is still largely unknown, we paid special attention to clarifying the role of serotonin and FMRF-amide in the visual system of this snail and compared our findings with those reported from other species. At least one serotonin- and one FMRF-amidergic fibre were labeled in each optic nerve, and since no cell bodies in the eye showed immunoreactivity to these neurotransmitters, we believe that efferent fibres with somata located in the central ganglia branch at the base of the eye and probably release 5HT and FMRF-amide as neuro-hormones. Double labelling revealed retrograde transport of neurobiotin through the optic nerve, allowing us to conclude that the central pathways and serotonin- and FMRF-amide-immunoreactive cells and fibres have different locations in the CNS in L. stagnalis. The chemical nature of the fibres, which connect the two eyes in L. stagnalis, is neither serotoninergic nor FMRF-amidergic.

Electron microscopy in Jamaica: applications and techniques

Although the electron microscope was developed about 60 years ago in Germany, its arrival and subsequent use in Jamaica are of considerably more recent date. In this paper, the principles of scanning and transmission electron microscopy (SEM & TEM) are briefly explained, and examples are given of the research done with the electron microscopes at the University of the West Indies (UWI), Mona Campus, Jamaica, especially over the last three years. Detailed descriptions of specimen preparation are provided for both SEM and TEM and particular emphasis is placed on the methodology used in our laboratory, as it sometimes differs from the routine followed in electron microscopy units of temperate countries. (AU)

Electron microscopy in Jamaica: applications and techniques

Although the electron microscope was developed about 60 years ago in Germany, its arrival and subsequent use in Jamaica are of considerably more recent date. In this paper, the principles of scanning and transmission electron microscopy (SEM & TEM) are briefly explained, and examples are given of the research done with the electron microscopes at the University of the West Indies (UWI), Mona Campus, Jamaica, especially over the last three years. Detailed descriptions of specimen preparation are provided for both SEM and TEM and particular emphasis is placed on the methodology used in our laboratory, as it sometimes differs from the routine followed in electron microscopy units of temperate countries.