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141.
Robert B. Kirkpatrick Zahida Parveen Presley F. Martin 《Genesis (New York, N.Y. : 2000)》1994,15(2):188-200
A transient expression assay has been used to investigate the cause of a tissuespecific position effect on Adh expression from a transgene insertion in Drosophila. A 15.4-kb genomic clone containing the 3.2-kb Adh insert along with flanking regions of genomic DNA is expressed in this assay in a tissue-specific pattern resembling the abnormal expression pattern of the position effect. The 3.2-kb Adh insert is expressed normally without the flanking sequences. A silencer element is located upstream of the Adh gene within a 2-kb fragment that acts in both orientations and at a distance of at least 6.5 kb from the larval Adh promoter to suppress ADH expression in a nontissue specific fashion. The DNA sequence of the 2-kb fragment indicates that it is a noncoding region. A 17-bp sequence is repeated within this region and may be associated with the silencer activity, since subclones from the 2-kb fragment, each containing one of the repeated regions, both retain full silencer activity. This silencer fails to suppress expression from an α1-tubulin promoter-LacZ fusion construct or an hsp70 promoter-Ach fusion construct. In addition to the silencer, another element is located downstream of the Adh gene that produces a higher level of anterior than posterior midgut expression. These results suggest that the 5′ silencer and the 3′ element act together to create the tissue specific pcsition effect characteristic of the GC-1 line. © 1994 Wiley-Liss, Inc. 相似文献
142.
InhibitionofAcrosomalEnzymesbyGossypolIsRelatedtoItsAntifertilityActionYUANYu-ying;(袁玉英)ZHANGYan-lin;(张燕林)SHIQi-xian(石其贤)(Zhe... 相似文献
143.
白化病的遗传流行病学研究 总被引:5,自引:0,他引:5
本文应用分离分析和血缘分析方法,对山东省100余万人群遗传病调查中发现的37个白化病核心家系进行了分析。结果表明:白化病存在遗传异质性,为多基因常染色体隐性遗传,最小基因数为8,平均基因频率为0.0023,群体中致病基因携带者频率为0.0383;近亲结婚大大提高白化病的患病率。 相似文献
144.
本文以加杨(Populus Canadensis),I—214(Populus euramericana(Dode)Guinier CV—214),中保14等杨树密度试验(1988—1991)为依据,分析了初植密度、竞争对生长的抑制作用,阐述了合理密度、合理密度范围、缓冲作用、上限合理密度线的形成过程。指出在双对数图上,上限合理密度线遵从Logistic分布(1nw=K/1+e(0.732·lnN-2.429),呈左侧伸展的S型曲线。该曲线可划分为近似于lnw一lnN直线的上中下三部分,其中间部分直线式的斜率为-1.5左右,称作合理密度直线式。对密度与生长的动态作了分析、概述与讨论。 相似文献
145.
HBIG,无环鸟苷,干扰素联合对慢性乙型肝炎抗病毒效应观察 总被引:1,自引:0,他引:1
本文报道血清HBV复制标志阳性的慢乙肝54例,随机分为治疗组及对照组各27例进行HBIG、无环鸟苷、干扰素联合近、远期抗病毒效应观察。治疗组为无环鸟苷第一周按25~20mg/kg/d计后改17~15mg/kg/d×53天,共60天;人白细胞干扰素1×106U肌注每周3次×4周,后改1.0×106U肌注每周2次×6周,共10周;HBIG400U肌注隔日1次,共10周,对照组仅给予一般“保肝”药物。其中治疗组18例,对照组19例进行治后半年到2年追踪观察,结果近、远期HBcAg、DNAP、HBV-DNA阴转率治疗组均高于对照组,其中治疗组近、远期HBcAg,HBV-DNA阴转率均达40%以上,明显高于对照组(P<0.05~0.01),治疗组近、远期各有4例及2例HBsAg阴转,而对照组则无一例阴转,从近、远期综合抗病毒效应观察,治疗组全阴率分别为33.3%、44.4%,而对照组分别为3.79%及0%,P<0.01,治疗组无明显毒副反应。对比单用无环鸟苷,全阴率31.8%;无环鸟苷加干扰素两药联合全阴率37.5%,均有所提高,达到44.4%,值得进一步研究。 相似文献
146.
四种动物病毒的细胞培养及血凝检测的比较研究李天宪,赵林,罗怡珊,冯锋(中国科学院武汉病毒研究所,武汉430071)关键词细小病毒,细胞培养,细胞病变,血凝试验云豹肠炎病毒(LPV)、水貂肠炎病毒(MEV)、犬肠炎病毒(CPV)和猫泛白细胞减少症病毒(... 相似文献
147.
The wind cooling effect determines wind chill equivalent-temperatures, which may be rather different to actual temperature. In a windy region such as Patagonia, this difference may reach a magnitude and persistence to become an important bioclimatic element. This paper quantifies the wind cooling effect in Patagonia by the presentation of equivalent isotherms as an adaptation of the usual isotherm maps to the regional bioclimatic environment. It is concluded that due to seasonal variations in wind speed, the annual equivalent temperature range is smaller than the actual temperature range, thus increasing oceanic features, from a thermal viewpoint, of the Patagonian climate.«Les vents que chassent, à travers une échancrure de la Cordillère des Andes, les hautes pressions du Pacifique, s'étranglent et s'accelèrent dans un étroit couloir de cent kilomètres de front, en direction de l'Atlantique, et raclent tout sur leur passage».Antoine de Saint-Exupéry «Un sens à la vie» (1956) 相似文献
148.
The populations of Gelidium canariensis (Grunow) Seoane-Camba from the Canary Islands were analyzed for genetic variability by isozyme electrophoresis in 1989 and 1990. Each population was divided into sporophytic and gametophytic subpopulations. Twenty-three to 27 putative alleles corresponding to 22 gene loci were analyzed. Sev-enteen loci were monomorphic in all six subpopulations, and five were polymorphic in at least one subpopulation. Significant deviations from Hardy-Weinberg equilibrium were found. The amount of genetic variability (percentage of polymorphic loci, mean number of alleles per locus, and average gene diversity) of haploid subpopulations was lower than that of diploid subpopulations. No correlation between genetic distance and geographical distance was found. Low genetic differentiation between sporophytic and gametophytic subpopulations of the same locality was obsewed in two populations. The low genetic diversity and genetic differentiation suggest that the genetic structure of the populations of G. canariensis from the Canary Islands is due to a combination of founder effects and the predominance of asexual reproduction. Initial differences in gene frequencies may have persisted because of insufficient time to reach a higher level of differentiation. 相似文献
149.
In the polytene nuclei of germ-line cells (ovarian pseudonurse cells) of Drosophila melanogaster females mutant for otu
11 (ovarian tumor), the pericentric heterochromatin is much more abundant than in somatic salivary gland cells. This is due to the degree of heterochromatin compaction (and consequently the level of underreplication) being lower in the nurse cells than in the salivary gland cells. The lower level of compaction probably results in a very low degree of position effect gene inactivation in the ovarian nurse cells. 相似文献
150.
Johannes P. van Dijken Ruud A. Weusthuis Jack T. Pronk 《Antonie van Leeuwenhoek》1993,63(3-4):343-352
An overview is presented of the steady- and transient state kinetics of growth and formation of metabolic byproducts in yeasts.Saccharomyces cerevisiae is strongly inclined to perform alcoholic fermentation. Even under fully aerobic conditions, ethanol is produced by this yeast when sugars are present in excess. This so-called Crabtree effect probably results from a multiplicity of factors, including the mode of sugar transport and the regulation of enzyme activities involved in respiration and alcoholic fermentation. The Crabtree effect inS. cerevisiae is not caused by an intrinsic inability to adjust its respiratory activity to high glycolytic fluxes. Under certain cultivation conditions, for example during growth in the presence of weak organic acids, very high respiration rates can be achieved by this yeast.S. cerevisiae is an exceptional yeast since, in contrast to most other species that are able to perform alcoholic fermentation, it can grow under strictly anaerobic conditions.Non-Saccharomyces yeasts require a growth-limiting supply of oxygen (i.e. oxygen-limited growth conditions) to trigger alcoholic fermentation. However, complete absence of oxygen results in cessation of growth and therefore, ultimately, of alcoholic fermentation. Since it is very difficult to reproducibly achieve the right oxygen dosage in large-scale fermentations, non-Saccharomyces yeasts are therefore not suitable for large-scale alcoholic fermentation of sugar-containing waste streams. In these yeasts, alcoholic fermentation is also dependent on the type of sugar. For example, the facultatively fermentative yeastCandida utilis does not ferment maltose, not even under oxygen-limited growth conditions, although this disaccharide supports rapid oxidative growth. 相似文献