Parasitoid pressure and the radiation of a gallforming group (Cecidomyiidae: Asphondylia spp.) on creosote bush (Larrea tridentata)

Summary We tested the Enemy Impact Hypothesis, which predicts that communities of one tropic level are organized by the tropic level above. In the case of gallforming insect communities, the hypothesis predicts that gall morphology will diverge, minimizing the number of parasitoids shared among species. We used the monophyletic group of gallforming cecidomyiids (Asphondylia spp.) on creosote bush (Larrea tridentata) to test this hypothesis, predicting that species with thicker gall walls should exclude species of parasitoids with shorter ovipositors and have lower levels of parasitism. Of 17 parasitoid species reared from Asphondylia galls on creosote bush, 9 accounted for over 98% of parasitism. Seven of these 9 species had ovipositors long enough to penetrate 10 of 13 gall morphs measured. There was no significant relationship between gall wall thickness and number of associated parasitoid species (r ²=0.01, P>0.05, n=13). There was no relationship between gall wall thickness and types of parasitoid species colonizing galls: parasitoids with the shortest ovipositors colonized all types of gall morphs and were dominant members of the parasitoid assemblages in galls with the thickest walls. Ultimately, there were no significant differences in percent parasitism among Asphondylia species, regardless of gall wall thickness. We found no difference in numbers of associated parasitoids or percent parasitism in galls with different textures (e.g. hairy versus smooth), different locations on the plant or different phenologies. Our results suggest that enemy impact has not influenced the diversity of this gall community. Gall wall thickness, phenology, location on the plant and surface structure do not appear to influence the distribution of parasitoid species. Other explanations are offered to account for diversity in gall morphology among these species.     

Homozygous paracentric inversion 12 in a mentally retarded boy: a case report and review of the literature

Summary A mentally retarded male was found to be homozygous for a paracentric inversion of the long arm of chromosome 12(inv(12)(q21.1q23.2)). His parents, who are first cousins, and his phenotypically normal younger brother are inversion heterozygotes. Homozygous structural rearrangements are discussed and cases of paracentric inversions, including a further nine previously unpublished, are reviewed.     

Multiangle light-scattering analysis of murine teratocarcinoma cells.

Stem cells of the mouse testicular teratocarcinoma are capable of giving rise in vivo and in vitro to a wide variety of cell and tissue types representative of each embryonic germ layer. Multiangle light-scattering measurements in a flow system have been made on these stem cells and on a variety of their differentiated derivatives. This technique is capable of distinguishing the stem cells from parietal yolk sac cells, visceral yolk sac cells, neuronal cells and squamous cells. However, multipotential stem cells cannot be distinguished from stem cells that are restricted in their development to a single pathway.     

Inactivation of template-directed misfolding of infectious prion protein by ozone

Misfolded prions (PrP(Sc)) are well known for their resistance to conventional decontamination processes. The potential risk of contamination of the water environment, as a result of disposal of specified risk materials (SRM), has raised public concerns. Ozone is commonly utilized in the water industry for inactivation of microbial contaminants and was tested in this study for its ability to inactivate prions (263K hamster scrapie = PrP(Sc)). Treatment variables included initial ozone dose (7.6 to 25.7 mg/liter), contact time (5 s and 5 min), temperature (4°C and 20°C), and pH (pH 4.4, 6.0, and 8.0). Exposure of dilute suspensions of the infected 263K hamster brain homogenates (IBH) (0.01%) to ozone resulted in the in vitro destruction of the templating properties of PrP(Sc), as measured by the protein misfolding cyclic amplification (PMCA) assay. The highest levels of prion inactivation (≥4 log(10)) were observed with ozone doses of 13.0 mg/liter, at pH 4.4 and 20°C, resulting in a CT (the product of residual ozone concentration and contact time) value as low as 0.59 mg · liter(-1) min. A comparison of ozone CT requirements among various pathogens suggests that prions are more susceptible to ozone degradation than some model bacteria and protozoa and that ozone treatment may be an effective solution for inactivating prions in water and wastewater.     

Cross reactivity of human beta2-microglobulin with human granulocyte colony-stimulating activity.

Effects of antisera to human beta2-microglobulin (beta2 m) on factors able to stimulate colony formation in culture by human granulopoietic progenitor cells were investigated. The colony-stimulating activity (CSA) present in media conditioned by cultures of human peripheral leukocytes was suppressed by treatment with anti-beta2m. This inhibition was not due to a direct effect on the granulopietic progenitor cells; controls to test for cytotoxicity and for noncytotoxic inhibition of the progenitor cells by anti-beta2m yielded negative results. These experiments provide evidence for a relationship between human CSA and beta-microglobulin, and suggest a possible analogy between molceules involved in the in vitro regulation of granulopoiesis and products of the major histocompatibility gene complex.     

Carbon Oxysulfide Is an Inhibitor of Both CO(2) and HCO(3) Uptake in the Cyanobacterium Synechococcus PCC7942

Carbon oxysulfide (COS) was reinvestigated as an inhibitor of active inorganic carbon transport in cells of Synechococcus PCC7942 adapted to growth at low inorganic carbon. COS inhibited both CO₂ and HCO₃⁻ transport processes in a reversible (in the short term) and mixed competitive manner. The inhibition of COS was established using both silicone oil centrifugation experiments and O₂-evolution studies. The K_i for COS inhibition was 29 micromolar for CO₂ transport and 110 micromolar for HCO₃⁻ transport. These results support a model of inorganic carbon transport with a central CO₂ pump and an inducible HCO₃⁻ utilizing accessory protein which supplies CO₂ to the primary pump.     

Reactions of zoo visitors to free-ranging monkeys

This study assessed the potential of two types of primate exhibit both for enhancing zoo visitors' interest, knowledge, and enjoyment and for promoting conservation education. Visitors' reactions to a free-ranging group of cotton-top tamarins were compared with their responses to caged tamarins in three ways: 1) timing how long visitors spent at each exhibit, 2) recording the comments made by visitors about the exhibits, and 3) asking visitors to respond to questionnaires about the two exhibits. The results showed that the free-ranging group of tamarins provoked wider comment from members of the public than caged groups and that visitors were willing to spend much more time looking for and watching monkeys in trees than monkeys in cages. Visitors felt that improvements in the animals' welfare were obtained from allowing them to live free in the trees, thought that they could learn more from such groups than from caged animals, and enjoyed seeing the free-ranging tamarins more than the monkeys in cages. These results suggest that developing more naturalistic zoo exhibits can have considerable benefits not only for the animals involved, but also for public education in conservation issues. © 1994 Wiley-Liss, Inc.     

N-Methyl-d-Aspartate Receptor Proteins NR2A and NR2B Are Differentially Distributed in the Developing Rat Central Nervous System as Revealed by Subunit-Specific Antibodies

Abstract: We have identified the regional distributions and developmental expression of NMDA-receptor proteins NR2A and NR2B in rat CNS, using two subunit-specific affinity-purified polyclonal antibodies that recognize NR2A and NR2B. In western blots of cells transfected with NR2A or NR2B cDNAs, and of brain homogenates, each antibody detects a single predominant 172-kDa protein corresponding to its homologous subunit. Both subunits are glycoproteins that are enriched in synaptic membranes. In adult rat CNS, NR2A and NR2B are enriched in cortex and hippocampus but are present in other forebrain regions. In hindbrain, NR2A is present at low levels but NR2B is barely detectable. These subunits are differentially expressed in postnatal CNS development. In cortex and striatum, NR2A is absent at birth but expression increases thereafter, whereas NR2B is expressed at nearly adult levels during forebrain development. In hindbrain, low levels of NR2A are present throughout development, whereas NR2B is expressed only transiently in the first postnatal weeks. These results suggest that native NMDA receptors are modulated by NR2A and NR2B in adult forebrain but not appreciably in hindbrain. In contrast, during early postnatal development, NR2B may have a more dominant role than NR2A in modulating NMDA receptors throughout the CNS. Thus, transient changes in NMDA-receptor function may occur during maturation of certain neuronal and/or glial populations via differential expression of NR2A and NR2B subunits.