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This study provides the first molecular phylogeny of the social wasp subgenus Polistella (Hymenoptera: Vespidae: Polistes) from Vietnam. Fragments of the mitochondrial COI and 16S rRNA genes were used to reconstruct the phylogenetic trees among 38 Polistes species plus two out-group species (Vespa soror du Buysson and Ropalidia fasciata (Fabricius)). Our results support the existence of several species-groups, including two that are congruent with the previous stigma and Stenopolistes groups defined on the basis of morphology. Moreover, we recovered a clade including the stigma group and the two species P. humilis and P. variabilis that was sister to all other species of Polistella. However, the results also challenged the definition of other groups of Polistella based on morphological data, as well as the definition of two species: P. brunus and P. affinis. This first study calls for further analyses including morphological characters to clarify the taxonomy and the classification of the group.  相似文献   
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Weaning represents the transition of mammalian life from maternal dependence to independence in both energetics and behavior. The length at weaning (Lw) is determined by the maternal investment during gestation and lactation. It affects calf survival and impacts on the long‐term persistence of species, but the measurement is not readily obtainable for many cetaceans. A general linear model and residual correlation were used to explore the correlations between the published Lw and five other life history traits of cetaceans, including female asymptotic length (Lx), length at birth (Lb), lactation period (LP), gestation period (GP), and calving interval (CI). Lx was a significant confounding parameter on the other five traits. By eliminating the confounding Lx, ANCOVA revealed that baleen whales (Mysticeti) and toothed cetaceans (Odontoceti) had comparable Lw. By residual correlation, which factors the confounding Lx, Lw was significantly correlated with Lb but not with GP, LP, and CI. After Lb was further eliminated, convergent Lw in cetaceans could still be observed. Therefore, we proposed a generic expression Lw= 1.239Lx0.877, which allows us to further estimate Lw of undocumented cetacean species.  相似文献   
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Lipopolysaccharide (LPS) activates innate immune responses through TLR4·MD-2. LPS binds to the MD-2 hydrophobic pocket and bridges the dimerization of two TLR4·MD-2 complexes to activate intracellular signaling. However, exactly how lipid A, the endotoxic moiety of LPS, activates myeloid lineage cells remains unknown. Lipid IVA, a tetra-acylated lipid A precursor, has been used widely as a model for lipid A activation. For unknown reasons, lipid IVA activates proinflammatory responses in rodent cells but inhibits the activity of LPS in human cells. Using stable TLR4-expressing cell lines and purified monomeric MD-2, as well as MD-2-deficient bone marrow-derived macrophages, we found that both mouse TLR4 and mouse MD-2 are required for lipid IVA activation. Computational studies suggested that unique ionic interactions exist between lipid IVA and TLR4 at the dimerization interface in the mouse complex only. The negatively charged 4′-phosphate on lipid IVA interacts with two positively charged residues on the opposing mouse, but not human, TLR4 (Lys367 and Arg434) at the dimerization interface. When replaced with their negatively charged human counterparts Glu369 and Gln436, mouse TLR4 was no longer responsive to lipid IVA. In contrast, human TLR4 gained lipid IVA responsiveness when ionic interactions were enabled by charge reversal at the dimerization interface, defining the basis of lipid IVA species specificity. Thus, using lipid IVA as a selective lipid A agonist, we successfully decoupled and coupled two sequential events required for intracellular signaling: receptor engagement and dimerization, underscoring the functional role of ionic interactions in receptor activation.  相似文献   
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Ethylene, a gaseous plant hormone, is responsible for the initiation of reproductive development in pineapple. Reproductive development can be forced in pineapple (Ananas comosus var. comosus) throughout the year with ethylene. Inhibition of natural flowering initiation with aviglycine [(S)-trans-2-amino-4-(2-aminoethoxy)-3-butenoic acid hydrochloride], an inhibitor of ethylene biosynthesis, provides evidence that reproductive development in response to cold stress and short daylength is also in response to ethylene production. We studied the effect of cold treatment of pineapple on ethylene production and flower induction by applying a short-term cold stress to stem apices. Shoot apices of pineapple treated with ice crystals also produced twice as much ethylene as did those of control plants and significantly more than was produced by “D” leaf basal tissue. Moreover, pineapple plants treated four times with ice crystals or ice water were induced to flower under field conditions and the forcing efficiency, as evaluated by the percentages of inflorescence emergence and fruit harvest, was comparable to forcing with calcium carbide (CaC2) and ethephon. In another field experiment two applications of a 1.0% solution of CaC2 or 0.15% ethephon applied at 48 h intervals was sufficient to force reproductive development of ‘Tainon 17’. Furthermore, 0.5 or 1.0% solutions of CaC2 supplemented with 0.5% activated charcoal (AC) significantly improved the forcing effectiveness of CaC2. This could/would make it possible to reduce the number or concentration, or both, of CaC2 required to effect forcing in pineapple.  相似文献   
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α–Epithelial catenin (E-catenin) is an important cell–cell adhesion protein. In this study, we show that α–E-catenin also regulates intracellular traffic by binding to the dynactin complex component dynamitin. Dynactin-mediated organelle trafficking is increased in α–E-catenin−/− keratinocytes, an effect that is reversed by expression of exogenous α–E-catenin. Disruption of adherens junctions in low-calcium media does not affect dynactin-mediated traffic, indicating that α–E-catenin regulates traffic independently from its function in cell–cell adhesion. Although neither the integrity of dynactin–dynein complexes nor their association with vesicles is affected by α–E-catenin, α–E-catenin is necessary for the attenuation of microtubule-dependent trafficking by the actin cytoskeleton. Because the actin-binding domain of α–E-catenin is necessary for this regulation, we hypothesize that α–E-catenin functions as a dynamic link between the dynactin complex and actin and, thus, integrates the microtubule and actin cytoskeleton during intracellular trafficking.  相似文献   
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The microtubule-associated protein 1B (MAP1B) locus has been mapped in close proximity to spinal muscular atrophy (SMA) on chromosome 5q13. We have identified a second microsatellite within a MAP1B intron, which increases the heterozygosity of this locus to 94%. Two unambiguous recombination events establish MAP1B as a closely linked, distal flanking marker for the disease locus, while a third recombinant establishes D5S6 as the proximal flanking marker. The combination of key recombinants and linkage analysis place the SMA gene in an approximately 2-cM interval between loci D5S6 and MAP1B. Physical mapping and cloning locate MAP1B within 250 kb of locus D5S112. The identification and characterization of a highly polymorphic gene locus tightly linked to SMA will facilitate isolation of the disease gene, evaluation of heterogeneity, and development of a prenatal test for SMA.  相似文献   
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