Studies on Nipponnemertes Friedrich (Nemertini, Hoplonemertini). II. Taxonomy of Nipponnemertes pulcher (Johnston) and Some Other Species

The synonymity of some Amphiporus species is discussed. Amphiporus falklandicus Wheeler, 1934, A. pusillus Punnett, 1903, Nipponnemertes bergendali (Gering, 1912), N. danae (Friedrich, 1957) and Wheeler's specimens of A. gerlachei Burger, 1904 and A. lecointei Burger, 1904 are found to be synonymous with N. pulcher , while A. mesosorus Verrill, 1892, A. arcticus Punnett, 1901 and A. thompsoni Punnett, 1901 are separated from the discussion of synonymity with this species. A summary of the knowledge of the geographical distribution of N. pulcher is given. The species A. africanus Wheeler, 1940, A. magnus Punnett, 1903, A. marioni Hubrecht, 1887, A. schollaerti Wheeler, 1934 and A. scoresbyi Wheeler, 1934 are transferred to the genus Nipponnemertes Friedrich, 1968.     

Adaptable gene‐specific dye bias correction for two‐channel DNA microarrays

DNA microarray technology is a powerful tool for monitoring gene expression or for finding the location of DNA‐bound proteins. DNA microarrays can suffer from gene‐specific dye bias (GSDB), causing some probes to be affected more by the dye than by the sample. This results in large measurement errors, which vary considerably for different probes and also across different hybridizations. GSDB is not corrected by conventional normalization and has been difficult to address systematically because of its variance. We show that GSDB is influenced by label incorporation efficiency, explaining the variation of GSDB across different hybridizations. A correction method (Gene‐ And Slide‐Specific Correction, GASSCO) is presented, whereby sequence‐specific corrections are modulated by the overall bias of individual hybridizations. GASSCO outperforms earlier methods and works well on a variety of publically available datasets covering a range of platforms, organisms and applications, including ChIP on chip. A sequence‐based model is also presented, which predicts which probes will suffer most from GSDB, useful for microarray probe design and correction of individual hybridizations. Software implementing the method is publicly available.     

Different forms of phototropic response induced by microbeam irradiation of discrete regions of an organ

Abstract Continuous unilateral microbeam (1 mm) irradiation of coleoptiles of Avena saliva L. produces growth responses in non-irradiated regions of the organ. Irradiation of the apex is followed by differential growth which commences in the apical zone, but then moves in a basipetal direction and results in positive curvature. Irradiation of the base also results in differential growth which commences at the apex and moves basipetally. However, the growth differential in this case results in negative curvature. The results of basal irradiation suggest the likely occurrence of acropetal transmission of the phototropic signal. The rate of movement of this signal is faster than the documented rate of auxin transport.     

Organotypic Culture of Human Skin to Study Melanocyte Migration

An ex vivo model system was developed to investigate melanocyte migration. Within this model system, melanocytes migrate among other epidermal cells in the epibolic outgrowth of skin explants. This process is initiated by loss of contact inhibition of epidermal cells at the rim of the explants and by locally produced chemotactic factors. Punch biopsies provided explants of reproducible diameter. Optimal culture conditions include medium consisting of Dulbecco's Minimal Essential Medium containing 10% inactivated normal human serum and placement of explants epidermal side up at the air-liquid interphase. Within 7 days, epidermal cells completely surround the explant. Approximately 3 days after the onset of keratinocyte migration, melanocytes distribute themselves within the newly formed epidermis. Throughout the 7-day culture period, melanocytes and keratinocytes show maintenance of subcellular morphology, and the dermo-epidermal junction remains intact. Melanocyte migration was quantified using immunoperoxidase staining in combination with light microscopy and computer-aided image analysis. Preliminary results using the model system to compare migration in control and nonlesional vitiligo skin indicate that no inherent migration defect is responsible for impaired repigmentation of vitiligo lesions. The organotypic culture model system allows for investigations on melanocytes within their environment of autologous epidermal and dermal components, closely resembling in vivo circumstances in human skin.