The nucleus accumbens (NAc) is a primary brain reward region composed predominantly of medium spiny neurons (MSNs). In response to early withdrawal from repeated cocaine administration, de novo dendritic spine formation occurs in NAc MSNs. Much evidence indicates that this new spine formation facilitates the rewarding properties of cocaine. Early withdrawal from repeated cocaine also produces dramatic alterations in the transcriptome of NAc MSNs, but how such alterations influence cocaine's effects on dendritic spine formation remain unclear. Studies in non-neuronal cells indicate that actin cytoskeletal regulatory pathways in nuclei have a direct role in the regulation of gene transcription in part by controlling the access of co-activators to their transcription factor partners. In particular, actin state dictates the interaction between the serum response factor (SRF) transcription factor and one of its principal co-activators, MAL. Here we show that cocaine induces alterations in nuclear F-actin signaling pathways in the NAc with associated changes in the nuclear subcellular localization of SRF and MAL. Using in vivo optogenetics, the brain region-specific inputs to the NAc that mediate these nuclear changes are investigated. Finally, we demonstrate that regulated SRF expression, in turn, is critical for the effects of cocaine on dendritic spine formation and for cocaine-mediated behavioral sensitization. Collectively, these findings reveal a mechanism by which nuclear-based changes influence the structure of NAc MSNs in response to cocaine.

Novel species of microfungi described in the present study include the following from South Africa: Cercosporella dolichandrae from Dolichandra unguiscati, Seiridium podocarpi from Podocarpus latifolius, Pseudocercospora parapseudarthriae from Pseudarthria hookeri, Neodevriesia coryneliae from Corynelia uberata on leaves of Afrocarpus falcatus, Ramichloridium eucleae from Euclea undulata and Stachybotrys aloeticola from Aloe sp. (South Africa), as novel member of the Stachybotriaceae fam. nov. Several species were also described from Zambia, and these include Chaetomella zambiensis on unknown Fabaceae, Schizoparme pseudogranati from Terminalia stuhlmannii, Diaporthe isoberliniae from Isoberlinia angolensis, Peyronellaea combreti from Combretum mossambiciensis, Zasmidium rothmanniae and Phaeococcomyces rothmanniae from Rothmannia engleriana, Diaporthe vangueriae from Vangueria infausta and Diaporthe parapterocarpi from Pterocarpus brenanii. Novel species from the Netherlands include: Stagonospora trichophoricola, Keissleriella trichophoricola and Dinemasporium trichophoricola from Trichophorum cespitosum, Phaeosphaeria poae, Keissleriella poagena, Phaeosphaeria poagena, Parastagonospora poagena and Pyrenochaetopsis poae from Poa sp., Septoriella oudemansii from Phragmites australis and Dendryphion europaeum from Hedera helix (Germany) and Heracleum sphondylium (the Netherlands). Novel species from Australia include: Anungitea eucalyptorum from Eucalyptus leaf litter, Beltraniopsis neolitseae and Acrodontium neolitseae from Neolitsea australiensis, Beltraniella endiandrae from Endiandra introrsa, Phaeophleospora parsoniae from Parsonia straminea, Penicillifer martinii from Cynodon dactylon, Ochroconis macrozamiae from Macrozamia leaf litter, Triposporium cycadicola, Circinotrichum cycadis, Cladosporium cycadicola and Acrocalymma cycadis from Cycas spp. Furthermore, Vermiculariopsiella dichapetali is described from Dichapetalum rhodesicum (Botswana), Ophiognomonia acadiensis from Picea rubens (Canada), Setophoma vernoniae from Vernonia polyanthes and Penicillium restingae from soil (Brazil), Pseudolachnella guaviyunis from Myrcianthes pungens (Uruguay) and Pseudocercospora neriicola from Nerium oleander (Italy). Novelties from Spain include: Dendryphiella eucalyptorum from Eucalyptus globulus, Conioscypha minutispora from dead wood, Diplogelasinospora moalensis and Pseudoneurospora canariensis from soil and Inocybe lanatopurpurea from reforested woodland of Pinus spp. Novelties from France include: Kellermania triseptata from Agave angustifolia, Zetiasplozna acaciae from Acacia melanoxylon, Pyrenochaeta pinicola from Pinus sp. and Pseudonectria rusci from Ruscus aculeatus. New species from China include: Dematiocladium celtidicola from Celtis bungeana, Beltrania pseudorhombica, Chaetopsina beijingensis and Toxicocladosporium pini from Pinus spp. and Setophaeosphaeria badalingensis from Hemerocallis fulva. Novel genera of Ascomycetes include Alfaria from Cyperus esculentus (Spain), Rinaldiella from a contaminated human lesion (Georgia), Hyalocladosporiella from Tectona grandis (Brazil), Pseudoacremonium from Saccharum spontaneum and Melnikomyces from leaf litter (Vietnam), Annellosympodiella from Juniperus procera (Ethiopia), Neoceratosperma from Eucalyptus leaves (Thailand), Ramopenidiella from Cycas calcicola (Australia), Cephalotrichiella from air in the Netherlands, Neocamarosporium from Mesembryanthemum sp. and Acervuloseptoria from Ziziphus mucronata (South Africa) and Setophaeosphaeria from Hemerocallis fulva (China). Several novel combinations are also introduced, namely for Phaeosphaeria setosa as Setophaeosphaeria setosa, Phoma heteroderae as Peyronellaea heteroderae and Phyllosticta maydis as Peyronellaea maydis. Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.