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101.
Probiotics and Antimicrobial Proteins - Dietary Lactobacillus acidophilus ATCC 4356 was used to relieve the impacts of aflatoxin B1 toxicity on the performances of Liza ramada. The control diet was...  相似文献   
102.
We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.  相似文献   
103.
Polar solvents induce terminal differentiation in the human promyelocytic leukemia cell line HL-60. The present studies describe the functional changes that accompany the morphologic progression from promyelocytes to bands and poly-morphonuclear leukocytes (PMN) over 9 d of culture in 1.3 percent dimethylsulfoxide (DMSO). As the HL-60 cells mature, the rate of O(2-) production increase 18-fold, with a progressive shortening of the lag time required for activation. Hexosemonophosphate shunt activity rises concomitantly. Ingestin of paraffin oil droplets opsonized with complement or Ig increases 10-fold over 9 d in DMSO. Latex ingestion per cell by each morphologic type does not change significantly, but total latex ingestion by groups of cells increases with the rise in the proportion of mature cells with greater ingestion capacities. Degranulation, as measured by release of β-glucuronidase, lysozyme, and peroxidase, reaches maximum after 3-6 d in DMSO, then declines. HL-60 cells contain no detectable lactoferrin, suggesting that their secondary granules are absent or defective. However, they kill staphylococci by day 6 in DMSO. Morphologically immature cells (days 1-3 in DMSO) are capable of O(2-) generation, hexosemonophosphate shunt activity, ingestion, degranulation, and bacterial killing. Maximal performance of each function by cells incubated in DMSO for longer periods of time is 50-100 percent that of normal PMN. DMSO- induced differentiation of HL-60 cells is a promising model for myeloid development.  相似文献   
104.
Alkaloid profiles of root and shoot cultures, seedlings and mature plants were analysed by capillary GLC and GLC-MS. beta-Carboline alkaloids, such as harmine, harmaline dominate in normal and root cultures transformed by Agrobacterium rhizogenes, as well as in roots and fruits of the plant. In shoots, flowers and shoot cultures quinoline alkaloids such as peganine, deoxypeganine, vasicinone and deoxyvasicinone widely replace the beta-carboline alkaloids. In root cultures, the formation of beta-carboline alkaloids can be induced by methyljasmonate and several other elicitors indicating that these alkaloids are part of the reactive chemical defence system of Peganum harmala.  相似文献   
105.
We describe here a computational morphology-based approach to the investigation of possible causes of chromatin alterations in sperm. A comprehensive set of state-of-the-art and geometric measures are computationally extracted from toluidine blue stained images and analyzed to infer the possible processes leading to normal and abnormal chromatin formation while seeking a possible taxonomy of chromatin alterations and their influence on sperm head morphology. Using this methodology, we have identified higher chromatin fragility at some specific points of the sperm head. Despite the lack of correlation between morphologies of sperm head and chromatin structure, four main morphological types of chromatin alterations in bull spermatozoa have been identified and their possible causes discussed.  相似文献   
106.
The invasive ant species Wasmannia auropunctata displays both ecologically dominant and non‐dominant populations within its native range. Three factors could theoretically explain the ecological dominance of some native populations of W. auropunctata: (i) its clonal reproductive system, through demographic and/or adaptive advantages; (ii) its unicolonial social organization, through lower intraspecific and efficient interspecific competition; (iii) the human disturbance of its native range, through the modification of biotic and abiotic environmental conditions. We used microsatellite markers and behavioural tests to uncover the reproductive modes and social organization of dominant and non‐dominant native populations in natural and human‐modified habitats. Microsatellite and mtDNA data indicated that dominant and non‐dominant native populations (supercolonies as determined by aggression tests) of W. auropunctata did not belong to different evolutionary units. We found that the reproductive system and the social organization are neither necessary nor sufficient to explain W. auropunctata ecological dominance. Dominance rather seems to be set off by unknown ecological factors altered by human activities, as all dominant populations were recorded in human‐modified habitats. The clonal reproductive system found in some populations of W. auropunctata may however indirectly contribute to its ecological dominance by allowing the species to expand its environmental niche, through the fixation over time of specific combinations of divergent male and female genotypes. Unicoloniality may rather promote the range expansion of already dominant populations than actually trigger ecological dominance. The W. auropunctata model illustrates the strong impact of human disturbance on species’ ecological features and the adaptive potential of clonal reproductive systems.  相似文献   
107.
1. A heterogeneous habitat structure can have a profound impact on foraging carnivorous arthropods. In the present study, we examined which elements of complex vegetation structure influence the searching movement of a parasitoid model organism. 2. Previous field work showed that tall and dense vegetation reduces the parasitism success of the eulophid egg parasitoid Oomyzus galerucivorus while the probability of host egg deposition increased close to plant tips. 3. In laboratory bioassays, dried grass stems were arranged according to the natural situation in different setups. The wasps' walking time on stems increased with increasing stem height and density. High stem density decreased the walking time of the parasitoids on the ground and an increased stem height reduced the propensity to fly to the ground. Connectivity had a minor positive effect on the number of stem contacts, but considerably reduced the number of wasps reaching the upper part of grass stems by two‐thirds. 4. Thus, although enhanced vegetation complexity enhances walking activity of the parasitoids in the vegetation, laying eggs at the tip of long grass stems in dense vegetation can be an adaptive strategy for the host, as it maximises the number of connections between plant parts to cross by parasitoids before reaching the host. The connection points disorient the wasps, which lose time, reverse their direction or fly away.  相似文献   
108.
Attention and the detectability of weak taste stimuli   总被引:1,自引:1,他引:1  
Marks  LE; Wheeler  ME 《Chemical senses》1998,23(1):19-29
Subjects detected weak solutions of sucrose or citric acid under conditions in which attention was directed toward one of the tastants or the other. Detection thresholds were measured using an adaptive, forced-choice procedure, with a three-down one-up rule, which computer simulations suggest should be more reliable than the popular two-down one-up rule. The thresholds were modestly but systematically lower for attended tastants than for unattended ones. Similar results have been reported in other sense modalities, including vision (greater sensitivity to stimuli presented to attended versus unattended spatial locations) and hearing (greater sensitivity to stimuli presented at attended versus unattended sound frequencies). Taken together, the findings are consistent with a general hypothesis regarding attention in sensory systems: gains or losses in detectability occur when a central attentional mechanism (or, conceivably, a preattentive mechanism) selectively and preferentially monitors signals arising from particular subsets of peripheral neural inputs.   相似文献   
109.
Overexpression of CD70 has been documented in a variety of solid and hematological tumors, where it is thought to play a role in tumor proliferation and evasion of immune surveillance. Here, we describe ARGX-110, a defucosylated IgG1 monoclonal antibody (mAb) that selectively targets and neutralizes CD70, the ligand of CD27.   ARGX-110 was generated by immunization of outbred llamas. The antibody was germlined to 95% human identity, and its anti-tumor efficacy was tested in several in vitro assays. ARGX-110 binds CD70 with picomolar affinity. In depletion studies, ARGX-110 lyses tumor cells with greater efficacy than its fucosylated version. In addition, ARGX-110 demonstrates strong complement-dependent cytotoxicity and antibody-dependent cellular phagocytosis activity. ARGX-110 inhibits signaling of CD27, which results in blocking of the activation and proliferation of Tregs. In a Raji xenograft model, administration of the fucosylated version of ARGX-110 resulted in a prolonged survival at doses of 0.1 mg/kg and above. The pharmacokinetics of ARGX-110 was tested in cynomolgus monkeys; the calculated half-life is 12 days. In conclusion, ARGX-110 is a potent blocking mAb with a dual mode of action against both CD70-bearing tumor cells and CD70-dependent Tregs. This antibody is now in a Phase 1 study in patients with advanced malignancies expressing CD70 (NCT01813539).  相似文献   
110.
Zayed A  Packer L 《Heredity》2007,99(4):397-405
Strong evidence exists for global declines in pollinator populations. Data on the population genetics of solitary bees, especially diet specialists, are generally lacking. We studied the population genetics of the oligolectic bee Lasioglossum oenotherae, a specialist on the pollen of evening primrose (Onagraceae), by genotyping 455 females from 15 populations across the bee's North American range at six hyper-variable microsatellite loci. We found significant levels of genetic differentiation between populations, even at small geographic scales, as well as significant patterns of isolation by distance. However, using multilocus genotype assignment tests, we detected 11 first-generation migrants indicating that L. oenotherae's sub-populations are experiencing ongoing gene flow. Southern populations of L. oenotherae were significantly more likely to deviate from Hardy-Weinberg equilibrium and from genotypic equilibrium, suggesting regional differences in gene flow and/or drift and inbreeding. Short-term N(e) estimated using temporal changes in allele frequencies in several populations ranged from approximately 223 to 960. We discuss our findings in terms of the conservation genetics of specialist pollinators, a group of considerable ecological importance.  相似文献   
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