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A clonal culture of Pfiesteria piscicida and new environmental isolates are used to describe the growth characteristics, feeding and factors contributing to the encystment and germination of the organism in both laboratory and environmental samples.

Research has been conducted on Pfiesteria piscicida. The construction of genomic DNA library from the clocally cultured P. piscicida and the characterization of nontranscribed spacer and large subunit of rRNA are discribed.

Abstract Background Dependences on addictive substances are substantially-heritable complex disorders whose molecular genetic bases have been partially elucidated by studies that have largely focused on research volunteers, including those recruited in Baltimore. Maryland. Subjects recruited from the Baltimore site of the Epidemiological Catchment Area (ECA) study provide a potentially-useful comparison group for possible confounding features that might arise from selecting research volunteer samples of substance dependent and control individuals. We now report novel SNP (single nucleotide polymorphism) genome wide association (GWA) results for vulnerability to substance dependence in ECA participants, who were initially ascertained as members of a probability sample from Baltimore, and compare the results to those from ethnically-matched Baltimore research volunteers. Results We identify substantial overlap between the home address zip codes reported by members of these two samples. We find overlapping clusters of SNPs whose allele frequencies differ with nominal significance between substance dependent vs control individuals in both samples. These overlapping clusters of nominally-positive SNPs identify 172 genes in ways that are never found by chance in Monte Carlo simulation studies. Comparison with data from human expressed sequence tags suggests that these genes are expressed in brain, especially in hippocampus and amygdala, to extents that are greater than chance. Conclusion The convergent results from these probability sample and research volunteer sample datasets support prior genome wide association results. They fail to support the idea that large portions of the molecular genetic results for vulnerability to substance dependence derive from factors that are limited to research volunteers.

Abstract Background Classical genetic studies indicate that nicotine dependence is a substantially heritable complex disorder. Genetic vulnerabilities to nicotine dependence largely overlap with genetic vulnerabilities to dependence on other addictive substances. Successful abstinence from nicotine displays substantial heritable components as well. Some of the heritability for the ability to quit smoking appears to overlap with the genetics of nicotine dependence and some does not. We now report genome wide association studies of nicotine dependent individuals who were successful in abstaining from cigarette smoking, nicotine dependent individuals who were not successful in abstaining and ethnically-matched control subjects free from substantial lifetime use of any addictive substance. Results These data, and their comparison with data that we have previously obtained from comparisons of four other substance dependent vs control samples support two main ideas: 1) Single nucleotide polymorphisms (SNPs) whose allele frequencies distinguish nicotine-dependent from control individuals identify a set of genes that overlaps significantly with the set of genes that contain markers whose allelic frequencies distinguish the four other substance dependent vs control groups (p < 0.018). 2) SNPs whose allelic frequencies distinguish successful vs unsuccessful abstainers cluster in small genomic regions in ways that are highly unlikely to be due to chance (Monte Carlo p < 0.00001). Conclusion These clustered SNPs nominate candidate genes for successful abstinence from smoking that are implicated in interesting functions: cell adhesion, enzymes, transcriptional regulators, neurotransmitters and receptors and regulation of DNA, RNA and proteins. As these observations are replicated, they will provide an increasingly-strong basis for understanding mechanisms of successful abstinence, for identifying individuals more or less likely to succeed in smoking cessation efforts and for tailoring therapies so that genotypes can help match smokers with the treatments that are most likely to benefit them.

The ichthyocidal activity of Pfiesteria pisciscida dinospores in a controlled laboratory setting, using the standard aquarium bioassay format, to gain insight into possible icthyocidal mechanisms is examined. The vitro exposure of fish larvae to clonal Pfiesteria pisciscida indicates that fish mortality was directly proportional to the dinospore cell density.

In a screen for cell wall defects in Saccharomyces cerevisiae, we isolated a strain carrying a mutation in the Cdc28-activating kinase CAK1. The cak1 P212S mutant cells exhibit multiple, elongated and branched buds, β(1,3)glucan-poor regions of the cell periphery and lysed upon osmotic shock after treatment with the chitin synthase III inhibitor Nikkomycin Z. Ultrastructural examination of cak1 P212S mutants revealed a thin, uneven cell wall and marked abnormalities in septum formation. In all of the above aspects, the cak1 P212S mutants are similar to previously described cla4 mutants, suggesting that the cell wall defects are common to mutants with hyperpolarized growth. In cak1M P212S mutants, chitin accumulates all over the surface of the cells and glucan synthase activity is located preferentially to the tips of elongated buds. We conclude that the cell wall weakness in cak1 P212S mutants is caused by hyperpolarized secretion of glucan synthase and lack of reinforcement of the lateral cell walls. Showing that the defect depends at least in part on Cdc28, the cak1 P212S hyperpolarized growth phenotype can be suppressed by a Cak1-independent Cdc28-allele. The results underline the importance of a minor cell wall component, the chitin of lateral walls, for the integrity of the cell in a stress situation. [ABSTRACT FROM AUTHOR]

Association genome scanning is of increasing interest for identifying the chromosomal regions that contain gene variants that contribute to vulnerability to complex disorders, including addictions. To improve the power and feasibility of this approach, we have validated "10k" microarray-based allelic frequency assessments in pooled DNA samples and have used this approach to seek allelic frequency differences between heavy polysubstance abusers and well characterized control individuals. Thirty-eight loci contain SNPs that display robust allele frequency differences between abusers and controls in both European- and Africa n- American samples. These loci identify an alcohol/acetaldehyde dehydrogenase gene cluster and genes implicated in cellular signaling, gene regulation, development, "cell adhesion," and Mendelian disorders. The results converge with previous linkage and association results for addictions. Pooled association genome scanning provides a useful tool for elucidating molecular genetic underpinnings of complex disorders and identifies both previously understood and previously unanticipated mechanisms for addiction vulnerability. [ABSTRACT FROM AUTHOR]