Ecological clustering within a diverse minnow assemblage according to morphological,dietary and isotopic data

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Three new species of Dalechampia (Euphorbiaceae) from Venezuelan Guayana

Three new species ofDalechampia are described from the Guayanan region of Venezuela.Dalechampia attenuistylus belongs to sectionRhopalostylis and may be most closely related toD. parvibracteata Lanj.Dalechampia megacarpa belongs to sectionDioscoreifoliae, although it is not especially close to any species in the section.Dalechampia papillistigma is also an isolated member of sectionDioscoreifolieae.     

Ultrastructural localization of DNA in tissue culture cell nuclei by means of enzyme-gold and autoimmune sera-protein A-gold techniques

The post-embedding localization of DNA was investigated in cell nuclei by means of DNase I-gold and autoimmune sera-protein A-gold techniques. Using the former technique, gold particles were found mainly over euchromatin, nucleoli exhibit occasionally high labeling. In the latter technique, the use of the serum binding dsDNA confined the label mainly to condensed chromatin.     

Live imaging of <Emphasis Type="Italic">Drosophila</Emphasis>gonad formation reveals roles for Six4 in regulating germline and somatic cell migration

Background  

Movement of cells, either as amoeboid individuals or in organised groups, is a key feature of organ formation. Both modes of migration occur during Drosophila embryonic gonad development, which therefore provides a paradigm for understanding the contribution of these processes to organ morphogenesis. Gonads of Drosophila are formed from three distinct cell types: primordial germ cells (PGCs), somatic gonadal precursors (SGPs), and in males, male-specific somatic gonadal precursors (msSGPs). These originate in distinct locations and migrate to associate in two intermingled clusters which then compact to form the spherical primitive gonads. PGC movements are well studied, but much less is known of the migratory events and other interactions undergone by their somatic partners. These appear to move in organised groups like, for example, lateral line cells in zebra fish or Drosophila ovarian border cells.     

Transcript profiling reveals mechanisms for lipid conservation during diapause in the mosquito, Aedes albopictus

The Asian tiger mosquito, Aedes albopictus, is a medically important invasive species whose geographic distribution has expanded dramatically during the past 20 years, and one of the key elements of its success is its capacity to survive long distance transport as a diapausing pharate first instar larva, encased within the chorion of the egg. We report that pharate larvae entering diapause are larger and contain 30% more lipid than their nondiapausing counterparts. To improve our understanding of the molecular regulation of lipid metabolism during diapause, we assessed the relative mRNA abundance of 21 genes using qRT-PCR. Elevated expression of lipid storage droplet protein 2 during embryonic development likely contributes to the higher amounts of lipid we noted in diapausing individuals. The conservation of lipids during diapause is reflected in downregulation of genes involved in lipid catabolism, including lipase 2, lipase 3, lipase 4, acyl-CoA dehydrogenase 4, and isovaleryl-CoA dehydrogenase. Two genes involved in fatty acid synthesis and modification, Δ(9)-desaturase, and fatty acyl-CoA elongase, were both upregulated in diapausing pharate larvae, suggesting roles for their gene products in generating unsaturated fatty acids to enhance membrane fluidity at low temperatures and generating precursors to the surface hydrocarbons needed to resist desiccation, respectively. Together, the results point to substantial distinctions in lipid metabolism within the embryo as a consequence of the diapause program, and these differences occur both before the actual onset of diapause as well as during the diapause state.