AFLP标记在两个芒果品种间杂交F_1代的多态性及分离方式

 本文利用 1 4对引物组合对 AFLP标记在两芒果品种间 ( Keitt× Tommy)杂交 F1代的多态性及分离方式进行的研究结果表明 ,AFLP标记在该 F1代群体中的多态性较高 ,分离位点出现的平均频率是 37.1 6%。分离方式有孟德尔分离、偏孟德尔分离及异常分离 3种方式。 3种分离位点出现的平均频率与数量分别为 2 1 .1 3%、1 49,1 5.74%、1 1 1 ,2 .2 7%、1 6,其中孟德尔分离位点占分离位点总数的 53.99%。该研究结果可为进一步利用该群体构建芒果 AFLP遗传图谱打下良好的工作基础并提供一定的理论依据。     

Factors Affecting the Use of Conservation Tillage in the United States

Conservation tillage was used on nearly 36% of planted hectares in 1996 in the U.S. This level has remained relatively unchanged since 1991. The use of conservation tillage varies by crop and is dependent on site-specific factors including soil sype, topsoil depth, and local climate conditions. A number of economic, demographic, geographic, and policy factors have affected the adsorption of conservation tillage. While it is not possible to quantify exactly the impact of these factors, it is clear that management complexities and profitability are key factors impeding the further adsorption of conservation tillage.     

The proportion of viruliferous individuals in field populations of Frankliniella occidentalis: Implications for tomato spotted wilt virus epidemics in tomato

Tomato spotted wilt tospovirus (TSWV) infected plants and western flower thrips (Frankliniella occidentalis Perg., WFT) adult population densities were monitored during 1993 and 1994 in field tomatoes in Northeastern Spain. The proportion of viruliferous WFT adults in field populations was quantified. A significant association has been found between early population densities of WFT adult thrips and final TSWV incidence for early transplanted tomato crops. In contrast, for late transplanted tomato crops, whereas similar high final disease incidences of TSWV could be attained, very low WFT adult population densities were always detected. The significantly higher infectious potential of WFT populations collected during the early growth stages of late transplanted tomatoes could be relevant for the TSWV incidences attained in spite of the low thrips numbers detected.     

AFLP标记在两个芒果品种间杂交F_1代的多态性及分离方式

本文利用14对引物组合对AFLP标记在两芒果品种间(Keitt×Tommy)杂交F1代的多态性及分离方式进行的研究结果表明,AFLP标记在该F1代群体中的多态性较高,分离位点出现的平均频率是37.16%.分离方式有孟德尔分离、偏孟德尔分离及异常分离3种方式.3种分离位点出现的平均频率与数量分别为21.13%、149,15.74%、111,2.27%、16,其中孟德尔分离位点占分离位点总数的53.99%.该研究结果可为进一步利用该群体构建芒果AFLP遗传图谱打下良好的工作基础并提供一定的理论依据.     

MYELOGRAPHY IN NEONATAL BOVINE CALVES

This study was undertaken to establish a protocol for myelography in the neonatal bovine calf. Five normal calves, one to five days old, were examined radiographically by myelography, using techniques recommended for the equine and canine. The contrast medium used was lopamidol, which was introduced through the foramen magnum under general anesthesia. When the protocol was established, several neonatal calves with partial or complete pareses were examined myelographically. Myelography revealed changes in the spinal canal and assisted in a definite diagnosis. No harmful effects were observed in the normal or abnormal calves during or after myelography. It was concluded that myelography is a valuable safe procedure for diagnosis of causes of paresis in neonatal calves.     

Irrigation influences on growth, yield, and water use of persimmon trees

A 3-year irrigation trial provided basic information on the response of persimmon (Diospyros kaki cv. Triumph) water use and development to irrigation levels. Constant experimental factors applied to recommended “baseline” crop factors resulted in ratios of irrigation (I) to FAO56 reference crop evapotranspiration (ET₀) ranging from 0.35 to 1.14. Vegetative and reproductive growth, sap flow, stem water potential (SWP), and local climate were monitored. An overall increase in yield and vegetative growth in response to irrigation was found, which suggests a potential yield increase for higher irrigation levels (40 tons/ha for annual irrigation of 1,000 mm). At high irrigation, the yield response curve levelled off and the marginal contribution of additional water declined. The up to threefold increase in number of fruits with irrigation, with no influence on natural abscission, suggests that differences in fruit quantities stem from response to irrigation at the earlier growth stages. Mean fruit size and fruit quality, as indicated by the ratio of rejected fruit, increased with irrigation up to I/ET₀ of ~0.8. Relative yield increased linearly with relative transpiration. However, post-harvest quality was not influenced. SWP, sap flow, and non-transpirable water fractions indicated that the seasonal irrigation tables were not well tuned. Initial adjustments were made during the final season of the experiment and a new table was developed based on our results. The new table should be a basis for further trials.     

Intersubject synchronization of cortical activity during natural vision

To what extent do all brains work alike during natural conditions? We explored this question by letting five subjects freely view half an hour of a popular movie while undergoing functional brain imaging. Applying an unbiased analysis in which spatiotemporal activity patterns in one brain were used to "model" activity in another brain, we found a striking level of voxel-by-voxel synchronization between individuals, not only in primary and secondary visual and auditory areas but also in association cortices. The results reveal a surprising tendency of individual brains to "tick collectively" during natural vision. The intersubject synchronization consisted of a widespread cortical activation pattern correlated with emotionally arousing scenes and regionally selective components. The characteristics of these activations were revealed with the use of an open-ended "reverse-correlation" approach, which inverts the conventional analysis by letting the brain signals themselves "pick up" the optimal stimuli for each specialized cortical area.     

Proteome half-life dynamics in living human cells

Cells remove proteins by two processes: degradation and dilution due to cell growth. The balance between these basic processes is poorly understood. We addressed this by developing an accurate and noninvasive method for measuring protein half-lives, called "bleach-chase," that is applicable to fluorescently tagged proteins. Assaying 100 proteins in living human cancer cells showed half-lives that ranged between 45 minutes and 22.5 hours. A variety of stresses that stop cell division showed the same general effect: Long-lived proteins became longer-lived, whereas short-lived proteins remained largely unaffected. This effect is due to the relative strengths of degradation and dilution and suggests a mechanism for differential killing of rapidly growing cells by growth-arresting drugs. This approach opens a way to understand proteome half-life dynamics in living cells.     

Growth dependency of wild,primitive and modern cultivated wheat lines on vesicular-arbuscular mycorrhiza fungi

Summary Mycorrhizal colonization and growth dependency were studied at a single rate of phosphorous application in wild and cultivated primitive and modern wheats, inoculated with Glomus intraradices Schenck & Smith. Mycorrhizal colonization found in Triticum timopheevii var. araraticum (AAGG) was higher than that found in the other tetraploid wheats (AABB). Mycorrhizal dependency was higher in representatives of the D genome donor — Aegilops squarrosa, compared with representatives of the A and possible B genome donors T. monococcum and Ae. sharonensis, Ae. longissima and Ae. speltoides, respectively. The nature of response to VAM in hexaploid wheat was controlled by factors of the A and B genomes which are epistatic over those located in the D genome. The high mycorrhizal colonization and dependency which was found in T. timopheevii var. araraticum may indicate special genomic affinity possessed by the G genome of wheat in VAM interaction. Based on the 27 wheat lines and species tested in this study only low correlation between G. intraradices colonization and its contribution to plant growth can be suggested.