A screening procedure was used to identify cell fusion (hyphal anastomosis) mutants in the Neurospora crassa single gene deletion library. Mutants with alterations in 24 cell fusion genes required for cell fusion between conidial anastomosis tubes (CATs) were identified and characterized. The cell fusion genes identified included 14 genes that are likely to function in signal transduction pathways needed for cell fusion to occur (mik-1, mek-1, mak-1, nrc-1, mek-2, mak-2, rac-1, pp2A, so/ham-1, ham-2, ham-3, ham-5, ham-9, and mob3). The screening experiments also identified four transcription factors that are required for cell fusion (adv-1, ada-3, rco-1, and snf5). Three genes encoding proteins likely to be involved in the process of vesicular trafficking were also identified as needed for cell fusion during the screening (amph-1, ham-10, pkr1). Three of the genes identified by the screening procedure, ham-6, ham-7, and ham-8, encode proteins that might function in mediating the plasma membrane fusion event. Three of the putative signal transduction proteins, three of the transcription factors, the three putative vesicular trafficking proteins, and the three proteins that might function in mediating cell fusion had not been identified previously as required for cell fusion.The process of cell-to-cell fusion plays a vital role in the life cycles of almost all multicellular organisms. Fertilization, the fusion of an egg and sperm, is a required cell-to-cell fusion event for sexually reproducing organisms. For vertebrates, cell fusion is a critical step in the development of muscle, placenta, and bone and plays an essential role in the formation of multinucleated giant cells in the immune system. Hyphal cell fusion plays an important role in the life cycle of Neurospora crassa and other filamentous fungi (1,6,12,24,38). During the life cycle of the filamentous fungus Neurospora crassa, cell fusions occur during at least three stages (12, 38). During sexual development, fertilization occurs as a protoperithecium (immature female mating structure) generates a trichogyne (long specialized hyphae) that chemotrophically grows toward a conidium (asexual spore) or hypha of the opposite mating type and undergoes cell fusion with it. During the germination of N. crassa conidia, the cells produce short, specialized thin hyphae called conidial anastomosis tubes (CATs), which mediate cell fusion between the germlings and generate an interconnected hyphal network (38,41). This process of cell fusion between conidia allows the cells to share resources and may be critical to the establishment of a colony under some environmental conditions. Cell fusions also occur during the growth of a vegetative N. crassa colony. A few millimeters behind the growing edge of the colony, specialized fusion hyphae are formed as branches from the vegetative hyphae. The fusion hyphae grow toward each other in a directed manner and undergo cell fusion to generate an interconnected hyphal network within the colony (18). Cytoplasm and organelles flow f...

Circulating tumor cell (CTC) number measured with the CellSearch® assay is prognostic for survival in metastatic castration-resistant prostate cancer (mCRPC) pre- and post-therapy. Using a standard operating protocol for sample collection, processing, and analysis, we compared detection rates of CellSearch® performed using FDA-cleared methodology with a second positive selection assay, AdnaTest®, and a non-selection polymerase chain reaction (PCR)-based (DDPCR) assay in 55 blood samples from 47 men with progressive mCRPC. AdnaTest requires processing within 4 hours of the draw and detects KLK3, PSMA, and EGFR transcripts in cells captured on magnetic beads. The DDPCR assay can be processed up to 7 days after a draw and detects KLK2, KLK3, HOXB13, GRHL2, and FOXA1 genes. AdnaTest and DDPCR were considered positive if at least 1 transcript was detected. AdnaTest detected CTCs in 34 samples (62%, 95% confidence interval [CI] 48%–75%), of which 23 (68%) had unfavorable CTC counts by CellSearch. A positive DDPCR result was seen in 38 cases (69%, 95% CI 55%–81%), including 24 (63%) with unfavorable CellSearch CTC counts. CellSearch found unfavorable CTC counts in 25 samples (45%, 95% CI 33%–58%). Sensitivities were similar between the AdnaTest and DDPCR assays, and both were more sensitive than CellSearch. Concordance probability estimates (possible values 0.5–1.0) associating the biomarker result with survival were similar: 0.77 (standard error [SE] = 0.07) for AdnaTest, 0.72 (SE = 0.08) for DDPCR, and 0.76 (SE = 0.06) for CellSearch. Overall detection rates between the AdnaTest and DDPCR assays were similar and both were superior to CellSearch. The DDPCR assay required the lowest blood volume, least on-site processing and longest stability for batch processing.