NEW MURID RODENTS FROM THE LATE CENOZOIC OF YUSHE BASIN, SHANXI

<正> As scientific collaborators of the Chinese-American joint project "Neogene Rocks and Faunas, Yushe Basin, Shanxi, PRC", the present authors, with William R. Downs, Northern Arizona University, sampled the Yushe microfauna in the fall of 1987 and 1988. The fossil temains were retrieved by surface collection and by wet-sieving bulk quantities of sediment.     

TNF-alpha-induced cell death in ethanol-exposed cells depends on p38 MAPK signaling but is independent of Bid and caspase-8

Alcoholic liver disease is associated with an increase in the number of necrotic and apoptotic liver parenchymal cells. Part of this injury is mediated by TNF-alpha. Ethanol exposure sensitizes cells to the cytotoxic effects of TNF-alpha. This may be due, in part, to the increased propensity of the mitochondria in ethanol-exposed cells to induction of mitochondrial permeability transition (MPT) by various agents, including the proapoptotic protein Bax. This idea is supported by the observation that increased cell death induced by TNF-alpha in ethanol-exposed cells was dependent on development of the MPT. In the present study, we elucidate the pathways through which ethanol exposure enhances TNF-alpha induction of the MPT and the resulting cytotoxicity. Specifically, ethanol-exposed cells display caspase-8- and Bid-independent cell killing during TNF-alpha treatment. Moreover, the ethanol-enhanced pathway is dependent on p38 MAPK signaling, which brings about caspase-3 activation, mitochondrial depolarization, accumulation of cytochrome c in the cytosol, and the translocation of Bax to the mitochondria. Additionally, ethanol-exposed cells display a blunting of TNF-alpha-induced Akt activation and Bcl-2 antagonist of cell death phosphorylation that may account, in part, for the increased sensitivity of the mitochondria to Bax-mediated damage.     

Binding dynamics of structural nucleoporins govern nuclear pore complex permeability and may mediate channel gating

The nuclear pore complex (NPC) is a permeable sieve that can dilate to facilitate the bidirectional translocation of a wide size range of receptor-cargo complexes. The binding of receptors to FG nucleoporin docking sites triggers channel gating by an unknown mechanism. Previously, we used deoxyglucose and chilling treatments to implicate Nup170p and Nup188p in the control of NPC sieving in Saccharomyces cerevisiae. Here, we report that aliphatic alcohols increase the permeability of wild-type and nup170Delta NPCs. In conjunction with increases in permeability, aliphatic alcohols, deoxyglucose, and chilling trigger the reversible dissociation of several nucleoporins from nup170Delta NPCs. These results are consistent with the hypothesis that NPC gating occurs when molecular latches composed of FG repeats and structural nucleoporins dissociate.     

Yeast nucleoporins involved in passive nuclear envelope permeability

The vertebrate nuclear pore complex (NPC) harbors an approximately 10-nm diameter diffusion channel that is large enough to admit 50-kD polypeptides. We have analyzed the permeability properties of the Saccharomyces cerevisiae nuclear envelope (NE) using import (NLS) and export (NES) signal-containing green fluorescent protein (GFP) reporters. Compared with wild-type, passive export rates of a classical karyopherin/importin (Kap) Kap60p/Kap95p-targeted NLS-GFP reporter (cNLS-GFP) were significantly faster in nup188-Delta and nup170-Delta cells. Similar results were obtained using two other NLS-GFP reporters, containing either the Kap104p-targeted Nab2p NLS (rgNLS) or the Kap121p-targeted Pho4p NLS (pNLS). Elevated levels of Hsp70 stimulated cNLS-GFP import, but had no effect on the import of rgNLS-GFP. Thus, the role of Hsp70 in NLS-directed import may be NLS- or targeting pathway-specific. Equilibrium sieving limits for the diffusion channel were assessed in vivo using NES-GFP reporters of 36-126 kD and were found to be greater than wild-type in nup188-Delta and nup170-Delta cells. We propose that Nup170p and Nup188p are involved in establishing the functional resting diameter of the NPC's central transport channel.     

Overexpression of <Emphasis Type="Italic">AP1-</Emphasis>like genes from <Emphasis Type="Italic">Asteraceae</Emphasis> induces early-flowering in transgenic <Emphasis Type="Italic">Chrysanthemum</Emphasis> plants

Chrysanthemum is one of the most important commercial cut flowers in the world. Early-flowering cultivars are required to produce quality chrysanthemum flowers with a lower cost of production. To shorten the vegetative growth phase of chrysanthemum, three AP1-like genes from Asteraceae were constitutively overexpressed in 80 independent transgenic chrysanthemum lines. All lines were characterized by PCR and RT-PCR and demonstrated that overexpression of compositae AP1-homologs in transgenic chrysanthemum under long-day conditions had no effect on plant development compared to non-transgenic controls. Conversely, under short-day conditions, transgenic plants commenced bud initiation 2 wk earlier than non-transgenic chrysanthemum plants. Subsequently, transgenic chrysanthemum flowers showed color earlier and resulted in full opening of inflorescences 3 wk prior to non-transgenic control plants. These results open new possibilities for genetic improvement and breeding of chrysanthemum cultivars.     

Ecological distribution and niche segregation of sibling species: the case of bean beetles, Acanthoscelides obtectus Say and A. obvelatus Bridwell

Abstract.  1. Molecular techniques have greatly added to the number of known sympatric cryptic species in insects. Ecological differences between these newly distinguished species are little explored, but niches often appear to overlap strongly. These cases are good models for exploring new ideas about species coexistence and community structure.
2.  Acanthoscelides obtectus and A. obvelatus are two sister species of bean bruchids, which have been confused until the last decade. One important ecological difference between them has emerged, however: A. obtectus is multivoltine and now distributed worldwide, whereas A. obvelatus is univoltine and restricted to Mesoamerica. Where their ranges overlap, the two species share the same host plants and larvae can sometimes complete development in the same seed.
3. The analysis of 27 622 Mexican individuals of the two species in 2001-2002 and 2002-2003 indicates that their niches overlap, but are differentiated with respect to altitude and the kind of beans (wild vs. domesticated). The principal patterns in their relative abundance in different habitats, and at different seasons, were constant from one year to the next.
4. As sympatry of these species seems to be of recent origin, the observed niche differentiation may not have evolved in response to competition, but could instead be the consequence of physiological differences, evolved independently in each species in allopatry, that pre-adapted them for different altitudes and kinds of resources.
5. The combination of biological and historical factors thus appears to allow these two sibling species to coexist in sympatry, despite their broadly overlapping ecological niches.     

Increased nuclear envelope permeability and Pep4p-dependent degradation of nucleoporins during hydrogen peroxide-induced cell death

The death of yeast treated with hydrogen peroxide (H(2)O(2)) shares a number of morphological and biochemical features with mammalian apoptosis. In this study, we report that the permeability of yeast nuclear envelopes (NE) increased during H(2)O(2)-induced cell death. Similar phenomena have been observed during apoptosis in mammalian tissue culture cells. Increased NE permeability in yeast was temporally correlated with an increase in the production of reactive-oxygen species (ROS). Later, after ROS levels began to decline and viability was lost, specific nuclear pore complex (NPC) proteins (nucleoporins) were degraded. Although caspases are responsible for the degradation of mammalian nucleoporins during apoptosis, the deletion of the metacaspase gene YCA1 had no effect on the stability of yeast nucleoporins. Instead, Pep4p, a vacuolar cathepsin D homolog, was responsible for the proteolysis of nucleoporins. Coincident with nucleoporin degradation, a Pep4p-EGFP reporter migrated out of the vacuole in H(2)O(2)-treated cells. We conclude that increases in ROS and NPC permeability occur relatively early during H(2)O(2)-induced cell death. Later, Pep4p migrates out of vacuoles and degrades nucleoporins after the cells are effectively dead.     

Anti-herpesvirus activities of Pseudomonas sp. S-17 rhamnolipid and its complex with alginate

The rhamnolipid biosurfactant PS-17 and its complex with the polysaccharide alginate, both produced by the Pseudomonas sp. S-17 strain, were studied for their antiviral activity against herpes simplex virus (HSV) types 1 and 2. They significantly inhibited the herpesvirus cytopathic effect (CPE) in the Madin-Darby bovine kidney (MDBK) cell line. The investigations were carried out according to the CPE inhibition assay protocol. The suppressive effect of the compounds on HSV replication was dose-dependent and occurred at concentrations lower than the critical micelle concentration of the surfactant. The 50% inhibitory concentration (IC50) of rhamnolipid PS-17 was 14.5 microg/ml against HSV-1 and 13 microg/ml against HSV-2. The IC50 values of the complex were 435 microg/ml for HSV-1 and 482 microg/ml for HSV-2. The inhibitory effects of the substances were confirmed by measuring the infectious virus yields with the multicycle virus growth experimental design as well: deltalog CCID50 of 1.84-2.0 against the two types of herpes simplex viruses by rhamnolipid PS-17 (20 microg/ml), and a strong reduction of the HSV-2 virus yield under the effect of the alginate complex at a concentration of 450 microg/ml. The results indicate that rhamnolipid PS-17 and its alginate complex may be considered as promising substances for the development of anti-herpetic compounds.     

The Study of the Metal-Binding Region in Human Growth Hormone Using Immobilized Metal Ion Affinity Gel-Electrophoresis

The zinc(II)-binding affinities of recombinant human growth hormone and two its mutants, 14–33 and 14–95, were studied using Immobilized Metal Ion Affinity Gel-electrophoresis (IMAG). The mutant hormones, composed of polypeptide chain segments of the human and porcine growth hormones, lacked His18, which may be crucial for binding of the intact hormone to the transition metal ions. The mutations did not affect the affinity of human growth hormone to immobilized zinc ions; the structural analysis implied that the human growth hormone contains two IDA–Zn(II) potential sorption sites formed by amino acid residues His21, Asp171, and Glu174 and/or His18 and Glu174.