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41.
James H. Asher Jr. Ronald W. Harrison Robert Morell Melisa L. Carey Thomas B. Friedman 《Genomics》1996,34(3):285
Waardenburg syndrome type 1 is caused by mutations inPAX3.Over 50 humanPAX3mutations that lead to hearing, craniofacial, limb, and pigmentation anomalies have been identified. APAX3mutant allele, segregating in a family, can show reduced penetrance and variable expressivity that cannot be explained by the nature of the mutation alone. TheMus musculus Pax3mutationSpd(Splotch-delayed, Pax3[formula]), coisogenic on the C57BL/6J (B6) genetic background, produces in heterozygotes a white belly spot with 100% penetrance and very few other anomalies. By contrast, manySpd/+ BC1progeny [F1♀Spd/+ (♀Spd/+ B6× ♂ +/+Mus spretus) × ♂ +/+ B6] exhibit highly variable craniofacial and pigmentary anomalies. Of the BC1Spd/+ progeny, 23.9% are estimated to be nonviable, and 32.1% are nonpenetrant for the white belly spot. The penetrance and expressivity of theSpd/+ genotype are controlled in part by the genetic background and the sex of the individual. A minimum of two genes interact withSpdto influence the craniofacial features of these mice. One of these genes may be either X-linked or sex-influenced, while the other is autosomal. TheA-locus (Agouti) or a gene closely linked toAalso plays a role in determining craniofacial features. At least one additional gene, possibly theA-locus or a gene linked toA,interacts withSpdand determines the presence and size of the white belly spot. The viability of BC1mice is influenced by at least three factors:Spd,A-locus alleles or a gene closely linked to theA-locus, and the sex of the mouse. These BC1mice provide an opportunity to identify genes that interact with and modify the expression ofPax3and serve as a model to identify the genes that modify the expression of humanPAX3mutations. 相似文献
42.
Ronald J. Prokopy Ratana Poramarcom Manon Sutantawong Ranu Dokmaihom Jorge Hendrichs 《Journal of Insect Behavior》1996,9(1):133-142
Oriental fruit flies,Bactrocera dorsalis, cultured in the laboratory for six generations, were released when 12–14 days old in an orchard of nonfruiting host trees that were furnished with either food and water, nonpunctured host fruit, punctured host fruit, or no resources. Nearly all flies of both sexes, all sexual behavior of males, and all mating pairs were observed on trees with fruit. Moreover, on trees with fruit, nearly all flies of both sexes, nearly all sexual behavior of males, and nearly all mating pairs occurred on the fruit itself rather than on the foliage or branches. In a subsequent test, both sexes were found to be strongly attracted to the odor of host fruit. For a polyphagous species of a tropical tephritid, these findings are the first to show a high level of male aggregation and a high amount of male sexual behavior on the fruit of host trees. Findings are discussed in relation to current knowledge of tephritid mating behavior. An additional quality-control test for laboratory cultured males used in the sterile insect technique of fly management is recommended. 相似文献
43.
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45.
Cells of the Upper and Lower Epidermis of Barley (Hordeum vulgare L.) Leaves Exhibit Distinct Patterns of Vacuolar Solutes 总被引:3,自引:0,他引:3 下载免费PDF全文
Vacuolar saps were extracted from individual, anatomically uniform cells of the upper (adaxial) and lower (abaxial) epidermis of the third leaf of barley (Hordeum vulgare L.) using a modified pressure probe. Saps (volume 80-200 pL) were sampled at various times between 3 d before and 7 d after full-leaf expansion and were analyzed for their osmolality and their concentrations of NO3-, malate, CI-, K+, and Ca2+. The osmolalities of upper and lower epidermis both increased with time but were similar to each other. In young leaves, K+ and Ca2+ were evenly distributed between the two epidermal layers, but as the leaf aged, the upper epidermis accumulated high (40-100 mM) Ca2+, whereas cells of the lower epidermis accumulated K+ instead. Nitrate concentration was 100 to 150 mM higher in the upper than in the lower epidermis, whereas CI- was 50 to 120 mM higher in the lower epidermis. These differences did not depend on the leaf developmental stage. The uneven distribution of epidermal NO3- and CI- was maintainedover a wide range of epidermal sap concentrations of these ions and was not affected by NO3- or CI- starvation or by an increase in the light intensity from 120 to 400 [mu]mol m-2 s-1. However, the latter did cause a decrease in epidermal NO3- and the appearance and accumulation of epidermal malate, particularly in the upper epidermis. The physiological implications of the results for solute storage in leaves and for the pathways of ion distribution to the epidermis are discussed. 相似文献
46.
Alexander A. DiIorio Pamela J. Weathers Ronald D. Cheetham 《Applied microbiology and biotechnology》1993,39(2):174-180
Transformed root tissue of Beta vulgaris (Detroit Dark Red) was permeabilized to stimulate the release of intracellularly stored betanin without adverse affects on tissue viability as measured by biomass accumulation. Product release of up to 15% (w/w) was achieved by heat treatment at 42°C for 45 min with minimal effect on viability. Higher levels of product release were obtained with increasing temperature and exposure, but at the expense of viability. Viability was measured by comparing dry weight increases of permeabilized tissue 3 days after treatment vs non-permeabilized tissue over the same time interval. Recovery of heat-treated tissue was improved by addition of CaCl2 (20 mm for 10 min) post-heat treatment. Betanin release up to 15% was also obtained at ambient temperature (25°C) by addition of up to 20 mm (NH4)2SO4 in the presence of 1 mm ethylenediaminetetraacetic acid (EDTA).
Correspondence to: A. A. DiIorio 相似文献
47.
Interest among researchers in the diagnosis, aetiology, prevention, and treatment of root caries has increased substantially over the past two decades. However, there are some fundamental problems impeding the advancement of the field which remain to be addressed and resolved. A universally acceptable definition of root caries is not yet available. The relationship of root caries to coronal caries has not been established. The underlying disease process is still not clearly understood. The optimal utilisation of preventive/therapeutic agents for the treatment or prevention of root caries has not been determined. New treatment materials and preventive agents have not yet been tested in controlled clinical trials. These are a few of the issues and problems which we address in this paper. 相似文献
48.
Borislav S. Stanchev James Doughty Charles P. Scutt Hugh Dickinson Ronald R.D. Croy 《The Plant journal : for cell and molecular biology》1996,10(2):303-313
The pollen coatings of both Brassica oleracea and Brassica napus contain a small family of basic 6–8 kDa proteins which are released on to the stigmatic surface on pollination. Following partial amino-acid sequencing of one of these pollen coat proteins (PCPs), PCR primers were constructed to isolate the PCP sequence from anther mRNA using RT-PCR. A cDNA was obtained which, in Northern hybridization experiments, revealed a characteristic pattern of expression during late stages of anther development. Interestingly, in situ hybridization revealed expression of this sequence to be confined to the cytoplasm of the trinucleate pollen grains: no signal was detected in the tapetum. Southern hybridization experiments have shown the gene ( PCP1 ) to be a member of a large family of between 30 and 40 PCP genes in the genome of Brassica oleracea , Surprisingly, RFLP experiments showed reduced copy number (one to two copies) in some of the F2 segregants, perhaps resulting from the clustering of PCP sequences. PCP1 contains a single intron and encodes a small, basic peptide 83 amino acids in length featuring a hydrophobic signal peptide sequence separated from the more hydrophilic, cysteine-rich mature protein. The central part and C-terminal region of the peptide contain a characteristic and invariant pattern of eight cysteines which show clear homology with a number of other anther-specific genes; the remainder of the sequence shows little similarity to other sequences on the data bases. The product of PCP1 is a member of a large family of similar proteins, some of which have been demonstrated to bind specifically to S-locus glycoproteins, but does not appear to be genetically linked to the S-locus . 相似文献
49.
Goupille Ronald E.; Smith April E.; Toida Toshihiko; Linhardt Robert J. 《Glycobiology》1997,7(2):231-239
Porcine intestinal mucosal heparan sulfate was exhaustivelydepolymerized on a large scale using beparin lyase II (heparinaseII) or heparin lyase III (heparitinase, EC 4.2.2.8
[EC]
). The oligosaccharidemixtures formed with each enzyme were fractionated by low pressuregel permeation chromatography. Size-uniform mixtures of disaccharides,tetrasaccharides, and hexasaccharides were obtained. Each size-fractionatedmixture was then purified on the basis of charge by repetitivesemipreparative strong-anion-exchange high-performance liquidchromatography. This approach has led to the isolation of 13homogenous oligosaccharides. The purity of each oligosaccharidewas demonstrated by the presence of a single peak on analyticalstrong-anion-exchange high-performance liquid chromatographyand reversed polarity capillary electrophoresis. The structuresof these oligosaccharides were established using 500 MHz one-and two-dimensional nuclear magnetic resonance spectroscopy.Three of the thirteen structures that were solved were novelwhile the remaining 10 have been previously described. All ofthe structures obtained using heparin lyase III contained a 相似文献
50.
Hanger Christopher C.; Presson Robert G. Jr.; Okada Osamu; Janke Steven J.; Watkins John J.; Wagner Wiltz W. Jr.; Capen Ronald L. 《Journal of applied physiology》1997,82(4):1283-1289
Hanger, Christopher C., Robert G. Presson, Jr., Osamu Okada,Steven J. Janke, John J. Watkins, Wiltz W. Wagner, Jr., and Ronald L. Capen. Computer determination of perfusion patterns in pulmonarycapillary networks. J. Appl. Physiol.82(4): 1283-1289, 1997.Individual pulmonary capillaries are notsteadily perfused. By using in vivo microscopy, it can readily bedemonstrated that perfusion continually switches between capillarysegments and between portions of the network within a single alveolarwall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching between capillary segments in the absence of hemodynamic changes in large upstream vessels suggests that capillary perfusion patterns could be random. Tocalculate the probability that perfusion patterns could occur bychance, it is necessary to know the total number of possible perfusionpatterns in a given capillary network. We developed a computer programthat can determine every possible perfusion pattern for any givencapillary network, and from that information we can calculate whetherperfusion of individual segments in the network is random. With theresults of the computer program, we have obtained statistical evidencethat some capillary segments in a network are nonrandomly perfused. 相似文献