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Landscape management has altered the population dynamics of many species residing in old growth ecosystems. As a result, fragmentations in residual old oak habitats in Sweden have led to the decline of endangered and long-lived polypores including the bright orange Hapalopilus croceus. Since little is known about this species, the aim was to investigate its growth, mating, and population biology using molecular and ecological methods. Specifically, what its growth patterns are, what its mating type is, and whether there is genetic variation among sampled populations in Sweden and the Baltic area. Fruiting body samples were collected from 34 localities in Sweden and 6 localities in neighboring Baltic States. Heterokaryotic mycelia were then cultivated from these samples and the genomes sequenced. 42 single-spore isolates from SLU's culture bank were also revived and cultured. These homokaryons were then crossed to determine mating type. Mating type was examined using morphological observations and calculated via mating matrix. To examine growth rate and establishment, H. croceus mycelia were grown in comparison to Fomitopsis pinicola mycelia. To explore the population biology, the potential for gene flow was analyzed among Swedish and Baltic isolates. As a result, H. croceus was found to be slow growing, exhibit a tetra polar mating type, and with limited genetic variation in the Baltic Sea area. Its slow growth could provide a possible insight into colonization strategy, whereas its multiallelic mating system could possibly increase outcrossing in the future. Minimal genetic variation could result from previous connectivity between oaks, where the fungus may have outbred readily and colonized more hosts, maintaining a more uniform genetic structure. However, recent habitat alteration has not been analyzed for this species, nor has community interaction among other fungi and fruiting dynamics. Thus, further examination of these factors would help expand this study and possibly provide conservation and management guidelines for future projects.

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Saccharomyces cerevisiae has developed mechanisms in order to survive harsh environmental conditions. This species responds to stresses such as ethanol, heat, and weak acid exposure via two well-characterized stress response pathways. These typically involve either the Hsf1p or the Msn2/4p transcriptional regulators. Recently, our lab has begun to characterize a member of the zinc cluster protein family: Asg1p (Activator of Stress Genes, systematic name: YIL130W), which is presumed to stimulate stress response genes independently of the Hsflp and Msn2/4p pathways. Previous work has revealed five target genes of Asg1p (HSP30, STP4, YER130C, TPO2, YRO2) thought to be involved in this novel stress response pathway. In this study, we attempted to better characterize the role of Asg1p and its target genes during stress induction. We first determined if the induction of certain Asg1p target genes by stress is strain specific. HSP30 induction by heat shock is specific to the W303 strain as shown by primer extension analysis. We then generated the deletion strains Deltaasg1 and Astp4 in W303. We observed a loss of induction of HSP30 in the Deltaasg1 deletion strain when cells were exposed to ethanol. This led us to believe that Asg1p does play a role in the stress response pathway. Also, we attempted to globally define the target sites of Asg1p in vivo on a genome-wide scale by combining Chromatin Immuno Precipitation with microarrays (ChIP-chip). We identified eight putative Asg1p target genes: YRO2, HSP78, ZRT2, ZRT1, MSN4, STP4, TPO2, and HSP30.

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