Comparative gene expression in brain regions of human alcoholics

The mesocorticolimbic system is the reward centre of the brain and the major target for drugs of abuse including alcohol. Neuroadaptive changes in this region are thought to underlie the process of tolerance and dependence. Recently, several research groups have searched for alcohol-responsive genes using high-throughput microarrays and well-characterized human post-mortem material. Comparison of data from these studies of cortical regions highlights the differences in experimental approach and selection of cases. However, alcohol-responsive gene sets associated with transcription, oxidative stress and energy production were common to these studies. In marked contrast, alcohol-responsive genes in the nucleus accumbens and the ventral tegmental area are primarily associated with changes in neurotransmission and signal transduction. These data support the concept that, within cortical regions, changes in gene expression are associated with alcoholism-related pathology. In the dopaminergic tract of the mesocorticolimbic system, alcohol-responsive gene sets suggest long-term neuroplastic changes in synaptic transmission.

Cryopreservation of spermatozoa of black marlin, Makaira indica (Teleostei : Istiophoredae)

As a first step towards the development of a method for the cryopreservation of black marlin spermatozoa, this study investigated the effect of dimethylsulfoxide (DMSO) concentration and pellet size on post-thaw spermatozoal motility. Spermatozoa were recovered from the spermatic duct of testes retrieved post-mortem from four adult black marlin caught in the Coral Sea spawning grounds of Australia. Undiluted spermatozoa. were stored on ice for 4 to 10 hours during transport to shore, then evaluated for motility after activation in seawater (1:10 v:v). Spermatozoa were prepared for cryopreservation in pellets by extension (1:3 v:v) in a defined fish Ringer's solution to give two final DMSO concentrations of 2.5% or 5.0%. Diluted spermatozoa were frozen directly on a dry ice block in pellet sizes of either 0.25 ml or 0.50 ml. Frozen pellets were thawed in a water bath at 40 degrees C for 60 seconds and assessed for post-thaw motility following activation in seawater. Spermatozoa recovered within 50 minutes of death and chilled on ice for 4 to 10 hours showed a mean (+/- SEM) motility immediately following activation of 91.6 +/- 7.9%. 50% of the spermatozoa remained motile for approximately 4 to 5 minutes. Following cryopreservation; mean motility declined significantly across all cryoprotectant and pellet size combinations (P < 0.001) but spermatozoa frozen in 2.5% DMSO showed higher motility than those frozen in 5.0% DMSO (P = 0.014). Pellet size had no effect on post-thaw motility (P = 0.179).

Latest developments in the microarray analysis of human brain mRNA

Microarrays are used to monitor the expression of thousands of gene transcripts. This technique requires high-quality RNA, which can be extracted from a variety sources, including autopsy brain tissue. Most nucleic acids and proteins are reasonably stable post mortem. However, their abundance and integrity can exhibit marked intraand inter-subject variability, so care must be taken when comparisons between case-groups are made. We will review issues associated with the sampling of RNA from autopsy brain tissue in relation to various ante- and post-mortem factors.