Microsporidian Spore Discharge and the Transfer of Polaroplast Organelle Membrane into Plasma Membrane

Electron microscopic examinations of Glugea hertwigi and Spraguea lophii spores indicated the presence of a single plasma membrane; however, this membrane remained in the spore during the discharge of the sporoplasm from the spore. Although discharged spores retained the old plasma membrane, the extruded sporoplasms acquired a new plasma membrane. In order to determine where the new plasma membrane came from, we used two fluorescent probes with membrane affinities. The markers were tested on unfired and discharged spores. The probe, N-phenyl-1-naphthylamine (NPN), labeled the polaroplast membrane in addition to the apolar groups in the posterior vacuoles of unfired spores. After spore discharge, NPN label disappeared from the spore ghosts except for a slight fluorescence on residual plasma membranes. Much of the NPN-labeled membrane reappeared after spore discharge on the outer envelope of discharged sporoplasms. The probe chlorotetracycline (CTC) labeled calcium-associated membranes of spore polaroplasts. During spore discharge, the CTC fluorescence shifted from the polaroplast organelle of unfired spores to the outer envelope of discharged sporoplasms. These results indicate that the polaroplast organelle may provide the new plasma membrane for discharged microsporidian sporoplasms.     

Determination of Ki67 Growth Fraction and Oestrogen Receptors In Screen-Detected Breast Cancer Using Cytological Preparations

Oestrogen receptor (ER) status of 77 cases of screen-detected breast cancer has been determined using cytological preparations. In 48% ER status was positive, which was the same proportion as that formed in a control group of age-matched patients with symptomatic breast carcinoma. Since the screen-detected group contained more low grade tumours, the percentage of ER-positive cases would be expected to be higher. the reasons for the discrepancy are discussed. Ki67 score has been determined for 41 cases of screen-detected cancer. Ki67 score showed a positive correlation with histological tumour grade and a negative correlation with ER status. However, there was no correlation with tumour size or lymph node status. the Ki67 scores in the screen-detected cancers were essentially similar to those found in an age-matched symptomatic group, but the very low scores were only found in the screened group.     

Visual fields,foraging and collision vulnerability in Gyps vultures

The visual fields of vultures contain a small binocular region and large blind areas above, below and behind the head. Head positions typically adopted by foraging vultures suggest that these visual fields provide comprehensive visual coverage of the ground below, prohibit the eyes from imaging the sun and provide extensive visual coverage laterally. However, vultures will often be blind in the direction of travel. We conclude that by erecting structures such as wind turbines, which extend into open airspace, humans have provided a perceptual challenge that the vision of foraging vultures cannot overcome.     

Genetic differentiation amongst fragrant orchids (Gymnadenia conopsea s.l.) in the British Isles

Genetic variation was examined in five microsatellite loci to seek evidence of genetic differentiation and restricted gene flow that would support the taxonomic division of Gymnadenia into three species ( G. borealis , G. conopsea , and G. densiflora ). A total of 107 alleles was detected in 17 populations from England, Scotland, and Ireland. The mean expected heterozygosities ranged from 0.48 to 0.81. The differentiation in allele frequencies amongst populations that had been assigned to each taxon on the basis of morphology was sufficiently large to support the taxa as distinct species. Phylogenetic trees based on microsatellite allele frequencies, as well as assignment tests, supported the existence of three distinct groups with at least partial restriction of gene flow between them. There was substantial homozygote excess, leading to high F _IS estimates, for most loci in most populations. This is unlikely to have been a result of widespread null alleles, and more probably reflects a high level of inbreeding in G. conopsea . This inference requires further investigation. The implications of the results of this and other taxonomic studies for the conservation of Gymnadenia in Britain are discussed.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 349–360.