Despite expression in embryonic visceral mesoderm, H2.0 is not essential for Drosophila visceral muscle morphogenesis.

H2.0, a homeobox gene identified by homology to the Sex combs reduced homeobox of Drosophila, is expressed in all the cellular precursors of the visceral musculature. By analogy to the essential function of most other known homeobox genes in determining the fate of cells where they are expressed, we hypothesized that mutation of H2.0 would disrupt gut muscle development. In this paper, we show that a small deletion, which eliminates H2.0, has no detectable effect on normal gut morphogenesis, visceral muscle actin organization, or larval peristalsis.     

Myelination of Neuronal Cell Bodies when Myelin Supply Exceeds Axonal Demand

1. Download high-res image (192KB)
2. Download full-size image

     

Plasmid DNA in Streptococcus cremoris Wg2: Influence of pH on Selection in Chemostats of a Variant Lacking a Protease Plasmid

Cleared lysates of a proteolytic (Prt⁺) strain and a naturally occurring non-proteolytic (Prt⁻) variant of Streptococcus cremoris Wg2 contain equal amounts of covalently closed circular plasmid DNA. An analysis of this plasmid DNA by agarose gel electrophoresis revealed the presence of at least five different plasmid species in the Prt⁺ strain and only three plasmid species in the Prt⁻ variant. Curing studies with acriflavine indicated that a 16-megadalton plasmid determined proteolytic activity in the Prt⁺ strain. In energy-limited chemostats inoculated with both strains it was observed that the Prt⁺ strain was replaced by the Prt⁻ variant. This effect was most apparent when the pH of the culture was fixed at a value above 6.3. No selection for the Prt⁻ variant was observed at pH 5.9. Since the two types of organisms contain equal amounts of plasmid DNA, it was concluded that the energy gain of the Prt⁻ variants at pH values above 6.0 probably has to be found in protein synthesis rather than in plasmid DNA synthesis.     

Tissue distribution of EDTA encapsulated within liposomes containing glycolipids or brain phospholipids.

Multilameller liposomes were prepared with various asialoglycolipids, gangliosides, sialic acid, or brain phospholipids in the liposome membrane and with ethylenediaminetetraacetic acid (EDTA) encapsulated in the aqueous compartments. The liposomes containing glycolipids or sialic acid were prepared from a mixture of phosphatidylcholine, cholesterol, and one of the following test substances: galactocerebroside, glucocerebroside, galactocerebroside sulfate, mixed gangliosides, monosialoganglioside GM1, monosialoganglioside GM2, monosialoganglioside GM3, disialoganglioside GD1a, or sialic acid. The liposomes containing brain phospholipids were mixtures of either sphingomyelin and cholesterol or a brain total phospholipid extract and cholesterol. Distributions of 14C-labeled EDTA were determined in mouse tissues from 15 min to 6 h or 12 h after a single injection of liposome preparation. Liver uptake up encapsulated EDTA was lowest from all liposome preparations containing sialic acid or sialogangliosides, regardless of the amount of sialic acid moiety present or the identity of the particular ganglioside; highest uptake of encapsulated EDTA by liver was from liposomes containing galactocerebroside or brain phospholipids. Lungs and brain took up the largest amounts of EDTA from liposomes containing sphingomyelin and lesser amounts from liposomes containing GD1a. Use of mouse brain phospholipid extract to prepare liposomes did not increase uptake of encapsulated EDTA by the brain. EDTA in liposomes containing monosialogangliosides, brain phospholipids, galactocerebroside, or sialic acid was taken up well by spleen and marrow. Highest thymus uptake of encapsulated EDTA was from liposomes containing GD1a. These results demonstrate that inclusion of sialogangliosides in liposome membranes decreases uptake of liposomes by liver, thus making direction of encapsulated drugs to other organs more feasible. Liposomes containing glycolipids also have potential uses as probes of cell surface receptors.     

The insect‐focused classification of fruit syndromes in tropical rain forests: An inter‐continental comparison

We propose a new classification of rain forest plants into eight fruit syndromes, based on fruit morphology and other traits relevant to fruit‐feeding insects. This classification is compared with other systems based on plant morphology or traits relevant to vertebrate fruit dispersers. Our syndromes are based on fruits sampled from 1,192 plant species at three Forest Global Earth Observatory plots: Barro Colorado Island (Panama), Khao Chong (Thailand), and Wanang (Papua New Guinea). The three plots differed widely in fruit syndrome composition. Plant species with fleshy, indehiscent fruits containing multiple seeds were important at all three sites. However, in Panama, a high proportion of species had dry fruits, while in New Guinea and Thailand, species with fleshy drupes and thin mesocarps were dominant. Species with dry, winged seeds that do not develop as capsules were important in Thailand, reflecting the local importance of Dipterocarpaceae. These differences can also determine differences among frugivorous insect communities. Fruit syndromes and colors were phylogenetically flexible traits at the scale studied, as only three of the eight seed syndromes, and one of the 10 colors, showed significant phylogenetic clustering at either genus or family levels. Plant phylogeny was, however, the most important factor explaining differences in overall fruit syndrome composition among individual plant families or genera across the three study sites. Abstract in Melanesian is available with online material.     

Root herbivory in vitro: Interactions between roots and aphids grown in aseptic coculture

Summary An in vitro coculture system has been established to study interactions between roots and aphids. Eight aphid species (Aphis spiraecola P., Trama rara M., Macrosiphum euphorbiae S., Rhopalosiphum padi L., Sitobion avenae F., Rhopalosiphum maidis F., Metopolophium dirhodum W., and Pemphigus populivenae F.) were reared on six species of hairy root cultures, Carthamus tinctorius L. cv N10, Tagetes patula L., Trichosanthes cucumerina L. var anguina, Hyoscyamus muticus L., Nicotiana tabacum L., and Beta vulgaris L. subsp. vulgaris. All species of aphids survived on root cultures for at least 2 d. Three cocultures have been maintained aseptically for periods ranging from 2 mo. to over 2 yr. The coculture of R. padi on C. tinctorius cv N10 (N10-Rp) was used to study morphological and biochemical responses of roots under aphid herbivory. Aphid herbivory caused browning of cultures, reduced root vegetative growth, and increased production of polyacetylenes in C. tinctorius cv N10 roots. Our results suggest that this coculture system may improve our understanding of interactions between aphids and plant roots.     

The structural and functional workings of KEOPS

KEOPS (Kinase, Endopeptidase and Other Proteins of Small size) is a five-subunit protein complex that is highly conserved in eukaryotes and archaea and is essential for the fitness of cells and for animal development. In humans, mutations in KEOPS genes underlie Galloway–Mowat syndrome, which manifests in severe microcephaly and renal dysfunction that lead to childhood death. The Kae1 subunit of KEOPS catalyzes the universal and essential tRNA modification N⁶-threonylcarbamoyl adenosine (t⁶A), while the auxiliary subunits Cgi121, the kinase/ATPase Bud32, Pcc1 and Gon7 play a supporting role. Kae1 orthologs are also present in bacteria and mitochondria but function in distinct complexes with proteins that are not related in structure or function to the auxiliary subunits of KEOPS. Over the past 15 years since its discovery, extensive study in the KEOPS field has provided many answers towards understanding the roles that KEOPS plays in cells and in human disease and how KEOPS carries out these functions. In this review, we provide an overview into recent advances in the study of KEOPS and illuminate exciting future directions.     

A Comparative Plasmonic Study of Nanoporous and Evaporated Gold Films

Previously, we have reported that nanoporous gold (NPG) films prepared by a chemical dealloying method have distinctive plasmonic properties, i.e., they can simultaneously support localized and propagating surface plasmon resonance modes (l-SPR and p-SPR, respectively). In this study, the plasmonic properties of NPG are quantified through direct comparison with thermally evaporated gold (EG) films. Cyclic voltammetry and electrochemical impedance spectroscopy experiments reveal that the NPG films have 4–8.5 times more accessible surface area than EG films. Assemblies of streptavidin–latex beads generate p-SPR responses on both NPG and EG films that correlate well with the bead density obtained from scanning electron microscopy (SEM) images. A layer-by-layer assembly experiment on NPG involving biotinylated anti-avidin IgG and avidin, studied by l-SPR and SEM, shows that the l-SPR signal is directly linked to the accessibility of the interior of the NPG porosity, an adjustable experimental parameter that can be set by the dealloying condition and time. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.