Genomic organization of mouse Dishevelled genes

We report the isolation and characterization of two new genomic loci corresponding to the mouse Dishevelled (Dvl) genes Dvl2 and Dvl3. The Dvl genes are homologs of the Drosophila dsh segment polarity gene, and are involved in the Wnt/wingless signal transduction pathway. Dvl2 and Dvl3 genomic clones were isolated from a mouse 129 strain λFIXII genomic library and have identical exon/intron organization to Dvll. All three Dishevelled genes span 15 exons and 14 introns and have a number of conserved splice junction sites.     

地高辛标记探针用于人白细胞基因定位

用地高辛标记探针在人染色体上进行了基因定位。使用了酶显色和荧光显色,两者得到了相同的定位结果,特异区阳性率分别为11.6％和19.8％’荧光显色特异性较高,说明基因定位效果受显示系统效率的影响,地高辛标记探针用于基因定位有比放射性探针、生物素探针更多的优越性。又讨论了几个影响效果的因素,提出以SDC代替甲酰胺洗涤;紫外照射于杂交前R显带方法能取得较好的基因定位效果。     

影响大肠杆菌中外源基因表达的因素

大肠杆菌已经被广泛地应用于表达各种外源基因,但是,不同的外源基因在表达效率上却有很大的差异,文章综述了影响大肠杆菌中外源基因表达的因素,这将有助于认识大肠杆菌中外源基因表达的规律,以便采取有效的方法提高外源基因在大肠杆菌中的表达效率．     

Inhibition of the HIV-1 and HIV-2 proteases by curcumin and curcumin boron complexes

Curcumin, a relatively non-toxic natural product isolated from Curcuma longa, is a modest inhibitor of the HIV-1 (1050 = 100 μM) and HIV-2 (IC₅₀ = 250 μM) proteases. Simple modifications of the curcumin structure raise the IC₅₀ value but complexes of the central dihydroxy groups of curcumin with boron lower the IC₅₀ to a value as low as 6 μM. The boron complexes are also time-dependent inactivators of the HIV proteases. The increased affinity of the boron complexes may reflect binding of the orthogonal domains of the inhibitor in intersecting sites within the substrate-binding cavity of the enzyme, while activation of the ,β-unsaturated carbonyl group of curcumin by chelation to boron probably accounts for time-dependent inhibition of the enzyme.     

羊角椒辣味物质成份分析

用紫外光谱法、红外光谱法和高效液相色谱法分析羊角椒中辣味物质纯度与组成,表明辣味物质由辣椒素、二氢辣椒素和降二氢辣椒素组成。     

WNT-mediated relocalization of dishevelled proteins

Summary TheWnt family of proto-oncogenes encodes secreted signaling proteins that are required for mouse development. TheDrosophila Wnt homolog, thewingless (Wg) segment polarity gene, mediates a signal transduction pathway in which the downstream elements appear to be conserved through evolution. One such element, thedishevelled gene product, becomes hyperphosphorylated and translocates to the plasma membrane in response to Wg (Yanagawa et al., 1995). We report here that the mouseDishevelle-1 (Dvl-1) andDishevelled-2 genes encode proteins that are differentially localized inWnt-overexpressing PC12 cell lines (PC12/Wnt). WhereasDvl-1 andDvl-2 proteins are limited to the soluble fraction of parental PC12 cells, PC12/Wnt cells display a subset ofDvl-1 protein associated with the membrane andDvl-2 protein with the cytoskeletal fraction. These results suggest a conserved role forDvl inWnt/wg signal transduction.     

Two-dimensional crystallization of avidin on biotinylated lipid monolayers.

Two-dimensional crystals of avidin were obtained on mixed lipid monolayers containing biotinylated lipids (N-biotinyl-dipalmitoyl-L-alpha-phosphatidyl ethanolamine and dioleoyl phosphatidyl choline) by specific interaction. Image analysis of electron micrographs of these crystals revealed p2 symmetry with the unit cell parameters a = 66 +/- 2 A, b = 68 +/- 1 A, and gamma = 121 +/- 4 degrees. The projection map showed, at a resolution of about 27 A, that the four subunits within one avidin molecule are separated into two parts. Comparison between avidin and streptavidin reveals that avidin molecule binds to the lipid monolayer in an orientation similar to that of streptavidin.     

Ventilation inhomogeneity in oleic acid-induced pulmonary edema

Tsang, John Y. C., Michael J. Emery, and Michael P. Hlastala. Ventilation inhomogeneity in oleic acid-inducedpulmonary edema. J. Appl. Physiol.82(4): 1040-1045, 1997.Oleic acid causes permeability pulmonaryedema in the lung, resulting in impairment of gas-exchange andventilation-perfusion heterogeneity and mismatch. Previous studies haveshown that by using the multiple-breath helium washout (MBHW)technique, ventilation inhomogeneity (VI) can be quantitativelypartitioned into two components, i.e., convective-dependent inhomogeneity (cdi) and diffusive-convective-dependent inhomogeneity (dcdi). Changes in VI, as represented by the normalized slope of thephase III alveolar plateau, were studied for 120 min in fiveanesthetized mongrel dogs that were ventilated under paralysis by aconstant-flow linear motor ventilator. These animals received oleicacid (0.1 mg/kg) infusion into the right atrium att = 0. MBHWs were done induplicate for 18 breaths every 40 min afterward. Three other dogs thatreceived only normal saline served as controls. The data show that,after oleic acid infusion, dcdi, which represents VI in peripheralairways, is responsible for the increasing total VI as lung wateraccumulates progressively over time. The cdi, which represents VIbetween larger conductive airways, remains relatively constantthroughout. This observation can be explained by increases in theheterogeneity of tissue compliance in the periphery, distal airwayclosure, or by decreases in ventilation through collateral channels.