Molecular identity and heterogeneity of Trichomonad parasites in a closed avian population.

Columbids (pigeons and doves) are the primary host of Trichomonas gallinae, the flagellate protozoon which causes avian trichomoniasis, a widespread, often lethal disease. Although predominantly apathogenic, the organism is paradigmatic for the study of strain-specific virulence, with some strains causing greater than 75% mortality and epizootic die-offs in wildlife populations. In recent years, research on this important emerging pathogen has been neglected and genetic variation within the parasite has not hitherto been investigated.

The pot1+ homologue in Aspergillus nidulans is required for ordering mitotic events.

Orderly progression through mitosis is essential to reduce segregation errors in the cell's genetic material. We have used a cytological screen to identify a mutant that progresses through mitosis aberrantly and have cloned the complementing gene, nimU, which encodes a protein related to Pot1 and other telomere end-binding proteins. We show that loss of nimU function leads to premature mitotic spindle elongation, premature mitotic exit, errors in chromosome segregation, and failure to delay mitotic exit under conditions that normally evoke the mitotic spindle checkpoint response.

Dynamic distribution of BIMG(PP1) in living hyphae of Aspergillus indicates a novel role in septum formation.

Mutation of bimG, the major protein phosphatase 1 gene in Aspergillus nidulans, causes multiple cell cycle and hyphal growth defects that are associated with overphosphorylation of subcellular components. We have used functional translational fusions with the green fluorescent protein (GFP) to show that BIMG has at least four discrete locations within growing hyphae. Three of these locations, the hyphal tip, the spindle pole body and the nucleus, correlate with previously known requirements for bimG(PP1) in mitosis and hyphal growth and are highly dynamic.

A type 2A protein phosphatase gene from Aspergillus nidulans is involved in hyphal morphogenesis.

A PCR-based approach, using degenerate oligonucleotide primers, was used to isolate fragments of two genes encoding type 2A protein phosphatases from the filamentous fungus, Aspergillus nidulans. The complete genomic sequence of one of these genes, pphA, was isolated and characterised. The pphA gene was predicted to encode a 329-residue protein which is about 85% identical to mammalian protein phosphatase 2A.

The expression of D-cyclin genes defines distinct developmental zones in snapdragon apical meristems and is locally regulated by the Cycloidea gene.

Three D-cyclin genes are expressed in the apical meristems of snapdragon (Antirrhinum majus). The cyclin D1 and D3b genes are expressed throughout meristems, whereas cyclin D3a is restricted to the peripheral region of the meristem, especially the organ primordia. During floral development, cyclin D3b expression is: (a) locally modulated in the cells immediately surrounding the base of organ primordia, defining a zone between lateral organs that may act as a developmental boundary; (b) locally modulated in the ventral petals during petal folding; and (c) is specifically repressed in the dorsal stamen by the cycloidea gene.