The patterns and drivers of fungal decomposer succession

Soil fungi release up to three-fold more carbon dioxide (CO2) to the atmosphere than human activity through the decomposition of dead organic matter (i.e. litter) in soil. Ecologists have frequently observed a pattern of fungal community assembly during litter decomposition, wherein different fungal taxa dominate different stages of decay in individual ecosystems. However, we still lack a complete understanding of how these diverse fungal communities generate decomposition. My dissertation helps to fill this knowledge gap by elucidating the cross-ecosystem taxonomic patterns of fungal decomposer succession and identifying biological features that correlate with these lineage-specific patterns. I conducted a meta-analysis of fungal decomposer succession in 22 ecosystems to identify the taxonomic patterns that were consistent across ecosystems and test environmental correlates of those patterns. I found a phylogenetic signal to succession and observed that the relative abundance of Ascomycetes was negatively correlated with observed peak decay stage, the relative abundance of Zygomycetes was positively correlated with peak decay stage, and the relative abundance of Basidiomycetes remained relatively constant throughout decay. I also found that plant litter type and climate factors were correlates of peak decay stage. Next, I performed laboratory culture experiments to test two longstanding hypotheses: that innate potential activity of plant cell wall-degrading enzymes and intrinsic growth rate underlie organisms’ peak decay stage. I found that potential cellulase activity and growth rate correlated negatively with peak decay stage and that growth rate explained more than a third of the phylogenetic signal to peak decay stage. Finally, I completed a comparative genomics study of fungi that have different observed decay stages. I found that protein domains related to plant C-degrading enzymes and growth-related biochemical pathways are part of the biology that underlies the succession of fungi and that transcriptional regulation and stress response may also underlie succession. This dissertation generates novel insights into the biology that underlies fungal decomposer community turnover during plant litter decay. This work provides direction for future research into the drivers of the assembly of decomposer communities and has important implications for efforts to incorporate fungal biology into predictive models of decomposition and terrestrial C-cycle dynamics

One-pot three-step thioconjugate addition-oxidation-Diels–Alder reactions of ethyl propiolate

Ethyl propiolate undergoes one-pot three-step thioconjugate addition-oxidation-Diels–Alder cycloaddition when treated with a variety of thiols in the presence of catalytic base, meta-chloroperbenzoic acid, lithium perchlorate, and cyclopentadiene. The reaction of S‑aryl thiols is catalyzed by trialkylamines, and the reaction of aliphatic thiols requires catalytic alkoxide base. Yields of the major diastereomer of the conveniently functionalized bicyclic products range from 47 to 81% depending upon the thiol reactant, which compares favorably to yields observed when the entire synthesis is performed step by step

One-pot synthesis of (Z)-B-sulfonyl enoates from ethyl propiolate

B-Sulfonyl enoates may be synthesized through a one-pot two-step sequence from ethyl propiolate with good to excellent selectivity for the Z isomer. Trialkylamines catalyze thioconjugate additions of aryl thiols, and alkoxides catalyze the addition of aliphatic thiols. Addition of meta-chloroperbenzoic acid (mCPBA) and LiClO4 to the reaction mixture provides rapid access to the sulfonyl enoates. Yields of the pure Z isomer range from 51 – 90%

Shades of empire: police photography in German South-West Africa

This article looks at a photographic album produced by the German police in colonial Namibia just before World War I. Late 19th- and early 20th-century police photography has often been interpreted as a form of visual production that epitomized power and regimes of surveillance imposed by the state apparatuses on the poor, the criminal and the Other. On the other hand police and prison institutions became favored sites where photography could be put at the service of the emergent sciences of the human body—physiognomy, anthropometry and anthropology. While the conjuncture of institutionalized colonial state power and the production of scientific knowledge remain important for this Namibian case study, the article explores a slightly different set of questions. Echoing recent scholarship on visuality and materiality the photographic album is treated as an archival object and visual narrative that was at the same time constituted by and constitutive of material and discursive practices within early 20th-century police and prison institutions in the German colony. By shifting attention away from image content and visual codification alone toward the question of visual practice the article traces the ways in which the photo album, with its ambivalent, unstable and uncontained narrative, became historically active and meaningful. Therein the photographs were less informed by an abstract theory of anthropological and racial classification but rather entrenched with historically contingent processes of colonial state constitution, socioeconomic and racial stratification, and the institutional integration of photography as a medium and a technology into colonial policing. The photo album provides a textured sense of how fragmented and contested these processes remained throughout the German colonial period, but also how photography could offer a means of transcending the limits and frailties brought by the realities on the ground.International Bibliography of Social Science

GLOBAL ANALYSIS OF ADP-RIBOSYLATION SUBSTRATES AND A CASE STUDY OF POLY(ADP-RIBOSE) DEPENDENT UBIQUITINATION

Post-translational modifications (PTMs) are the covalent attachment of chemical groups onto proteins following protein synthesis. ADP-ribosylation refers to the addition of one or more ADP-ribose groups onto proteins, with roles in DNA damage, cellular stress response, chromatin organization, transcription, and protein stability. ADP-ribosylation is synthesized by ADP-ribosyltransferases, including a subfamily in humans commonly known as Poly(ADP-ribose) Polymerases (PARPs). The inhibition of some of these enzymes is currently a chemotherapeutic agent for several cancers, highlighting the importance of ADP-ribosylation in cellular functions and translational potential in the clinic. This thesis work began with a review of current methods to identify ADP-ribosylation sites on proteins and curation from the literature to compile the first publicly-available database of ADP-ribosylation substrates and sites. From this broad study, we performed a case study of the RNA binding protein Metastatic Lymph Node 51 (MLN51), of which its ADP-ribosylation serves as a signal for the addition of a second PTM – ubiquitin, which targets the protein for degradation through a mechanism known as Poly(ADP-ribose) dependent Ubiquitination (PARdU). In particular, this thesis work established MLN51 as a bona fide PARdU substrate and elucidated the necessary amino acid site for PARdU regulation. Finally, the last chapter discusses the remaining questions around PARdU substrates and enzymes involved and highlights several areas for future investigation of PARdU