Comparison of the two rupicolous nightjars: the Afrotropical Freckled Nightjar Caprimulgus tristigma and the Neotropical Blackish Nightjar C. nigrescens

The Freckled Nightjar Caprimulgus tristigma and the Blackish Nightjar C. nigrescens are widespread and common within their rupicolous habitat, in the Afrotropics and Neotropics respectively, and may therefore be considered as successful in their adaptation to this habitat, a niche that has not been exploited by any other nightjar species. However, apart from a plumage pattern that matches a rocky substrate, their known life histories provide no common factors to explain this adaptive success. The factors that they do share are common to most other nightjars. While they nest and roost on rocks, their breeding biology is remarkably different. The contrasts and lack of convergence are surprising, and suggest that these two species are not as closely related as their current congeneric status implies. This is supported by recent molecular studies that place the African and South American Caprimulgus species in different well-supported clades.     

The importance of N-linked glycoproteins and dolichyl phosphate synthesis for fusion of L6 myoblasts.

Myoblasts fuse to form multinucleated myotubes, one of the early steps in the formation of multinucleated muscle fiber. The fusion reaction is accompanied by biochemical differentiation resulting in the expression of a variety of enzyme activities and macromolecules, particularly creatine phosphokinase. The fusing myoblast is thus an excellent system for use in studies on the molecular basis of cellular recognition. This report focuses on the role played by glycoproteins in this process. It was found that alteration of cell-surface glycoproteins, using oligosaccharide-processing inhibitors that interfered with the synthesis of the high-mannose type of N-linked oligosaccharide, resulted in the inhibition of both the fusion reaction and biochemical differentiation as determined by measurement of creatine phosphokinase. Ketoconazole, compactin, and lovastatin, which affect dolichol and cholesterol biosynthesis, were also potent fusion inhibitors. These observations, coupled with earlier studies on the characterization of fusion-defective myoblast cell lines defective in glycoprotein biosynthesis, point to the importance of surface glycoproteins in cellular recognition in L6 myoblasts.     

An ultrastructural study of abscission zone cells with special reference to the mechanism of enzyme secretion

Summary The ultrastructural changes which occur during the foliar abscission ofImpatiens sultani Hook. andColeus blumei Benth. have been described. In both cases fracture of the separation zone results from a modification of the wall and cleavage along the line of the middle lamella. This process starts at the corners of the cells and in regions rich in plasmodesmata.During the period of wall breakdown, cellular integrity is maintained and the membrane degradation described by others was not observed. Plasmolysis studies confirmed that the separation zone cells retained their selective permeability characteristics until well after wall fracture. Quantitative data are presented to show that there is an increase in the frequency of rough endoplasmic reticulum, dictyosomes and dictyosome vesicles during the period when wall-hydrolyzing enzyme secretion is occurring. These changes are interpreted as reflecting an increase in demand for the secretory machinery of the endomembrane system. The possible involvement of plasmodesmata in this process is also discussed.     

Calanoid copepod biogeography in New Zealand

The distribution of four calanoid copepod species of Boeckella in New Zealand are mapped and described. An explanation of their distribution patterns based on panbiogeographic methods is compared to an explanation based on dispersalist concepts. The panbiogeographic explanation is simpler, and is consistent with explanation of distribution patterns among other genera of plants, invertebrates, amphibians and birds. This revised version was published online in July 2006 with corrections to the Cover Date.     

TET2 is a component of the estrogen receptor complex and controls 5mC to 5hmC conversion at estrogen receptor cis-regulatory regions

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