Host-seeking behaviour of tracheal mites (Acari: Tarsonemidae) on honey bees (Hymenoptera: Apidae)

The behaviour of the endoparasitic tracheal mite, Acarapis woodi (Rennie) on honey bees (Apis mellifera L.) is a challenge to observe because of its small size. Through a microscope, we videotaped this mite's movement on young bees, dead bees and bees exposed to vegetable oil. Previous studies have shown that solid vegetable oil decreases mite infestations in a bee colony. We hypothesized that the oil alters mite behaviour to the detriment of the parasite, thus helping to safeguard the host. Habitat-seeking behaviour, identified as necessary for mites to locate a new host environment, was disrupted on both dead and oil-treated bees. Questing behaviour, which is associated with transfer between hosts, increased significantly on the dead and oily bees. The behaviours of mites were significantly different between all three treatments (x ²=494.96, p<0.001 on dead bees and x ²=851.11, p<0.001 on oily bees). Both questing and seeking behaviours were significantly different on each of the thoracic treatments (F _2,66=7.88, p<0.001 and F _2,66=21.28, p<0.001) and mite questing behaviour was not altered between males and females on live or oily bees (F _1,22=0.25, p<0.62), but habitat seeking was (F _1,22=7.42, p<0.012). The male questing and habitat-seeking behaviours were observed. We conclude that oil-treated bees gained protection from habitat-seeking mites because the normal behaviour of the mites seeking an oviposition site is interrupted.     

In situ treatment of Hamilton Harbour sediment

To enhance the biodegradation of organic contaminants, approximately 18.5 tonnes of oxidant (calcium nitrate) and 5 tonnes of nutrients were injected into sediments of the Dofasco Boatslip, Hamilton Harbour. In the laboratory 78% and 68% of the oil (TPHs) and polynuclear aromatic hydrocarbons (PAHs), respectively biodegraded in 197 days. In the 1992 treatment in the Ddofasco Boatslip, biodegradation of organic contaminants varied from 79% for low molecular weight compounds (BTXs), to 25/15 of the 16 priority pollutant PAHs. At first biodegraduation of large molecular weight PAHs resulted in the production of naphthalene (from 280 g/g to 549 g/g). In the 1993 treatments, 94% of the naphthalene, and 57% of the TPHs biodegraded. The in situ biotreatment of organic contamination takes time but for some sites the significantly lower cost relative to dredging and confinement makes in situ treatment a viable alternative.     

Regionalisation of cell fate and morphogenetic movement of the mesoderm during mouse gastrulation

The developmental fate of cells in the epiblast of early-primitive-streak-stage mouse embryos was assessed by studying the pattern of tissue colonisation displayed by lac Z-expressing cells grafted orthotopically to nontransgenic embryos. Results of these fate-mapping experiments revealed that the lateral and posterior epiblast contain cells that will give rise predominantly to mesodermal derivatives. The various mesodermal populations are distributed in overlapping domains in the lateral and posterior epiblast, with the embryonic mesoderm such as heart, lateral, and paraxial mesoderm occupying a more distal position than the extraembryonic mesoderm. Heterotopic grafting of presumptive mesodermal cells results in the grafted cells adopting the fate appropriate to the new site, reflecting a plasticity of cell fate determination before ingression. The first wave of epiblast cells that ingress through the primitive streak are those giving rise to extraembryonic mesoderm. Cells that will form the mesoderm of the yolk sac and the amnion make up a major part of the mesodermal layer of the midprimitive-streak-stage embryo. Cells that are destined for embryonic mesoderm are still found within the epiblast, but some have been recruited to the distal portion of the mesoderm. By the late-primitive-streak-stage, the mesodermal layer contains only the precursors of embryonic mesoderm. This suggests that there has been a progressive displacement of the midstreak mesoderm to extraembryonic sites, which is reminiscent of that occurring in the overlying endodermal tissue. The regionalisation of cell fate in the late-primitive-streak mesoderm bears the same spatial relationship as their ancestors in the epiblast prior to cell ingression. This implies that both the position of the cells in the proximal-distal axis and their proximity to the primitive streak are major determinants for the patterning of the embryonic mesoderm. © 1995 Wiley-Liss, Inc.     

精制蚕蛹油中碱液和过氧化值的控制

作者采用碱皂化的方法来达到精炼蚕蛹油的目的。实验表明,碱的浓度以１０％￣１３％比较合适,超碱量必须视酸值大小,通过小样试验来确定。精制油的过氧化值与皂化后中性油的洗涤温度、洗涤次数及搅拌速度有密切关系,必须严格控制。     

人胎胸腺细胞的异质性荧光及其与T淋巴细胞分化阶段关系的形态学研究

以７６９０－Ｘｕ荧光染色法结合ＷｕＴ３、ＷｕＴ４、ＷｕＴ８致敏红细胞花环实验观察经胸腺细胞分层液分离所得高密度亚群和低密度亚群人胎胸腺细胞的异质性荧光及其膜分化抗原ＣＤ３、ＣＤ４、ＣＤ８的表达。结果表明：不同胎龄胎儿胸腺细胞悬液呈现相似形态和相似分布特征的８种异质性荧光的细胞,其中,墨黑核细胞和桔红核细胞分布于两密度亚群,表型为ＣＤ３－ＣＤ４－ＣＤ８－;少数深蓝核和蓝核细胞分布于低密度亚群．表型为ＣＤ３＋,属成熟的胸腺细胞;大多数深蓝核和蓝核细胞、灰蓝核细胞、灰黄核细胞及部分淡桔黄核细胞分布于高密度亚群,表型为ＣＤ３－、ＣＤ４＋、ＣＤ８＋,为处于中间发育阶段的胸腺细胞。推测这些细胞胞核由深蓝、蓝、灰蓝、灰黄到淡桔黄的荧光光谱的偏移可能与中间发育阶段所发生的生物及理化变化有关。     

无色素腺棉籽蛋白粉与棉子油的制备

低棉酚棉籽为高蛋白含油的植物资源,适宜于水溶法制备油及蛋白粉,出油率一般可达９５％。     

Chemotype pattern differentiation of Thymus pulegioides on different substrates

Relationships between soil chemistry and population chemotype structure of Thymus pulegioides have been studied. The analysis of correlations suggest that an increased carbonate content in soil decreases the chemotype diversity of a population (as calculated by use of the Shannon index): the proportion of linalool chemotype plants rises and that of the phenol chemotype plants declines. In addition, the chemotype diversity decreases with increasing frequency of linalool chemotype, and increases with increase of carvacrol chemotype.     

The ‘World Prodigy’ oil spill in Narragansett Bay,Rhode Island: acute effects on macrobenthic crustacean populations

On June 26,1989, the tanker World Prodigy ran aground just outside the mouth of the West Passage of Narragansett Bay, Rhode Island, USA. About 922 metric tons of No. 2 fuel oil were released into the water and drifted over a total area of about 120 sq miles. Three days after the spill only a small fraction of the oil remained.The effects on macrobenthic crustaceans within the first five weeks after the spill were studied at five stations with a varying degree of oil exposure, including one control site never reached by oil from the spill. Significant differencies between these stations were noted for total amphipod abundance, the amphipod genus Ampelisca and ostracods (retained on a 0.3 mm mesh), but not for amphipods of the genus Corophium. At the most heavily impacted station (23 µg oil g^–1 sediment dry weight), the total amphipod abundance, dominated by Ampelisca verrilli, decreased by 86% within the first two weeks after the spill. Decreases in total amphipod abundance significantly larger than at the control site were noted also at two other stations, one of which with only trace amounts of oil detected in the sediment. The amphipod populations at these sites were dominated by juvenile specimens.These findings confirm the extreme sensitivity to oil pollution of amphipods and ostracods, noted in earlier field and experimental studies.     

Mass transfer limitation of sulfate in methanogenic aggregates

The role of mass transfer limitation of sulfate as a factor governing the competition between sulfate reducing and methane producing bacteria in methanogenic aggregates was theoretically evaluated by the calculation of steady-state sulfate microprofiles using a reference set of parameters obtained from the literature. The shooting method was used as a numerical technique for solving the mathematical model. The effect of the parameters on mass transport limitation was tested by varying each reference value of the parameters with a factor of 3. Sulfate limitation within granules prevailed at moderate (0.1 kg m(-3)) and low sulfate concentrations in the bulk liquid, at high maximum sulfate utilization rates (3.73 x 10(-5) kg SO(4) (2-) kg(-1) VSS S(-1) or biomass concentrations (40 KG VSS m(-3)), and in large aggregates (radius of 7.5 10(-4) m). The effective diffusion coefficient of sulfate and the affinity constant were less determinative for the penetration depth of sulfate within a granule. (c) 1994 John Wiley & Sons, Inc.     

Interacting effects of pH,aluminium and base cations on growth and mineral composition of the woodland grasses Bromus benekenii and Hordelymus europaeus

The influence of base cation concentrations on pH and aluminium sensitivity of the woodland grasses Bromus benekenii and Hordelymus europaeus was studied in flowing solution culture experiments. Plants were exposed to low pH (3.9, experiment 1) and Al concentrations of 19 and 37 M (experiment 2) at two base cation (Ca+Mg+K) levels, all within the ranges measured in natural forest soil solutions. Elevated base cation concentrations ameliorated both H and Al toxicity, as indicated by increased root and shoot growth. In the third experiment, interactions between pH (4.3 and 4.0) and Al (0 and 19 M) were investigated. It was shown that the combined toxicity effects of H and Al were not greater than the separate H or Al effects. Tissue concentrations of base cations and Al increased with increasing concentrations in the solution, but were also influenced by the base cation : Al ratio. Relating the experimental evidence with the composition of forest soil solutions suggests an important role of soil pH and Al in controlling the distribution of the two species. Growth conditions also differ at various soil depths. Concentrations of free cationic Al were higher and base cation concentrations lower at 5–10 cm than at 0–5 cm soil depth. Increasing base cation concentrations may protect roots from both H and Al injury during periods of drought when concentrations of most elements increase in the soil solution, whereas molar ratios between base cations, H and Al remain unchanged.