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61.
Dr. Gisela Baumann R. Theiler-Hedtrich Prof. Dr. R. Casper 《Journal of Phytopathology》1988,122(4):372-375
Apple mosaic virus and raspberry bushy dwarf virus were detected by ELISA in plantlets of red raspberry still growing in vitro. The plantlets were derived from explants which were excised from plants infected by either of the viruses mentioned. Detection by ELISA of prune dwarf virus in 4-month-old in vitro cultures of sour cherry was reported earlier. Thus, application of ELISA to tissue cultured plants in vitro seems to be an appropriate method for early detection of virus-infected plant cultures. 相似文献
62.
Daniel J. Cox William R. Carter Linda A. Gonder-Frederick William L. Clarke Stephen L. Pohl 《Applied psychophysiology and biofeedback》1988,13(3):201-217
Self-management of insulin-dependent diabetes mellitus (IDDM) is dependent on a negative feedback loop of blood glucose (BG) fluctuations, which in turn directs treatment decisions to maintain normal BG. Although this feedback is typically accomplished by self-monitoring of blood glucose (SMBG), SMBG has limitations, and patients often rely on what their BG feels like. Two studies were performed to evaluate whether patients could learn to more accurately feel/discriminate their BG on the basis of internal cues or internal plus external BG cues. In Study I, BG Awareness Training significantly improved pre- to posttreatment BG estimation accuracy, relative to a control group. Study II replicated BG Awareness Training efficacy in improving BG estimation accuracy. Improvement in estimation accuracy was related only to initial accuracy; those who were initially less accurate improved the most. This improvement was represented in a 31% reduction in dangerous BG estimation errors and a 9% increase in accurate estimates. Resulting estimations were, however, still significantly less accurate than SMBG at the end of training.This research was supported by NIH grants AM282880, AM24177, AM22125, and RR00847 and by the Ames Company. The authors express their appreciation for the contribution made by trainers Leslie Butterfield and Linda Zimbelman, by the nursing staff at the University of Virginia's Clinical Research Center and the Diabetes and Nutrition Unit, and by Dr. James May from the Medical College of Virginia in soliciting subjects. We would also like to thank Andrea Snyder for her assistance. 相似文献
63.
64.
Structural interactions of actin filaments and endoplasmic reticulum in honeybee photoreceptor cells
Otto Baumann 《Cell and tissue research》1992,268(1):71-79
Summary Fluorescent phallotoxins and heavy meromyosin were used to reveal the organization of the actin cytoskeleton in honeybee photoreceptor cells, and the relationship of actin filaments to the submicrovillar, palisade-like cisternae of the endoplasmic reticulum (ER). Bundles of unipolar actin filaments (pointed end towards the cell center) protrude from the microvillar bases and extend through cytoplasmic bridges that traverse the submicrovillar ER. Within the cytoplasmic bridges, the filaments are regularly spaced and tightly apposed to the ER membrane. In addition, actin filaments are deployed close to the microvillar bases to form a loose web. Actin filaments are scarce in cell areas remote from the rhabdom; these areas contain microtubule-associated ER domains. The results suggest that the actin system of the submicrovillar cytoplasm shapes the submicrovillar ER cisternae, and that the distinct ER domains interact with different cytoskeletal elements. 相似文献
65.
Three species of anoxygenic phototrophic heliobacteria, Heliobacterium chlorum, Heliobacterium gestii, and Heliobacillus mobilis, were studied for comparative nitrogen-fixing abilities and regulation of nitrogenase. Significant nitrogenase activity (acetylene reduction) was detected in all species grown photoheterotrophically on N2, although cells of H. mobilis consistently had higher nitrogenase activity than did cells of either H. chlorum or H. gestii. Nitrogen-fixing cultures of all three species of heliobacteria were subject to switch-off of nitrogenase activity by ammonia; glutamine also served to switch-off nitrogenase activity but only in cells of H. mobilis and H. gestii. Placing photosynthetically grown heliobacterial cultures in darkness also served to switch-off nitrogenase activity. Dark-mediated switch-off was complete in lactate-grown heliobacteria but in pyruvate-grown cells substantial rates of nitrogenase activity continued in darkness. In all heliobacteria examined ammonia was assimilated primarily through the glutamine synthetase/glutamate synthase (GS/GOGAT) pathway although significant levels of alanine dehydrogenase were present in extracts of cells of H. gestii, but not in the other species. The results suggest that heliobacteria, like phototrophic purple bacteria, are active N2-fixing bacteria and that despite their gram-positive phylogenetic roots, heliobacteria retain the capacity to control nitrogenase activity by a switch-off type of mechanism. Because of their ability to fix N2 both photosynthetically and in darkness, it is possible that heliobacteria are significant contributors of fixed nitrogen in their paddy soil habitat. 相似文献
66.
Insertional inactivation of a gene which controls expression of vancomycin resistance on plasmid pHKK100 总被引:8,自引:0,他引:8
Sandra Handwerger Linda Discotto Jane Thanassi Michael J. Pucci 《FEMS microbiology letters》1992,92(1):11-14
Expression of inducible high level vancomycin resistance (Vmr) in enterococci appears to require other plasmid-encoded genes in addition to the previously described structural genes vanA and vanH. Tn917 mutagenesis was used to identify such a region in the Vmr plasmid pHKK100. Insertional inactivation of a 693-bp open reading frame upstream from vanH resulted in complete loss of Vmr. This putative 26,642-Da protein has been designated VanR. 相似文献
67.
David A. Patton Linda H. Franzmann David W. Meinke 《Molecular & general genetics : MGG》1991,227(3):337-347
Summary We have previously isolated and characterized over 90 recessive mutants of Arabidopsis thaliana defective in embryo development. These emb mutants have been shown to differ in lethal phase, extent of abnormal development, and response in culture. We demonstrate in this report the value and efficiency of mapping emb genes relative to visible and molecular markers. Sixteen genes essential for embryo development were mapped relative to visible markers by analyzing progeny of selfed F1 plants. Embryonic lethals are now the most common type of visible marker included on the linkage map of Arabidopsis. Backcrosses were used in several cases to orient genes relative to adjacent markers. Three genes were located to chromosome arms with telotrisomics by screening for a reduction in the percentage of aborted seeds produced by F1 plants. A restriction fragment length polymorphism (RFLP) mapping strategy that utilizes pooled EMB/EMB F2 plants was devised to increase the efficiency of mapping embryonic lethals relative to molecular markers. This strategy was tested by demonstrating that the biol locus of Arabidopsis is within 0.5 cM of an existing RFLP marker. Mapping embryonic lethals with both visible and molecular markers may therefore help to identify large numbers of genes with essential functions in Arabidopsis. 相似文献
68.
Ellen M. Johnson Linda S. Schnabelrauch Barbara B. Sears 《Molecular & general genetics : MGG》1991,225(1):106-112
Summary A bovine tRNA gene cluster has been characterized and the sequences of four tDNAs determined. Two of the tDNAs could encode tRNASer
IGA, one tDNASer
UGA, and the fourth tRNAGln
CUG. The three serine tDNAs representing the UCN codon isoacceptor family are almost identical. However, the sequence of the tDNASer
TGA differs from a previously sequenced bovine tDNASer
TGA at 12 positions (ca. 14%). This finding suggests that in the bovine genome, two subfamilies of genes might encode tRNASer
UGA. It also raises the possibility that new genes for a specific UCN isoacceptor might arise from the genes of a different isoacceptor, and could explain previously observed differences between species in the anticodons of coevolving pairs of tRNAsSer
UCN. The gene cluster also contains complete and partial copies, and fragments, of the BCS (bovine consensus sequence) SINE (short interspersed nuclear element) family, six examples of which were sequenced. Some of these elements occur in close proximity to two of the serine tDNAs. 相似文献
69.
Bacillus sphaericus as a mosquito pathogen: properties of the organism and its toxins. 总被引:1,自引:0,他引:1
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In the course of sporulation, Bacillus sphaericus produces an inclusion body which is toxic to a variety of mosquito larvae. In this review we discuss the general biology of this species and concentrate on the genetics and physiology of toxin production and its processing in the midgut of the larval host. The larvicide of B. sphaericus is unique in that it consists of two proteins of 51 and 42 kDa, both of which are required for toxicity to mosquito larvae. There is a low level of sequence similarity between these two proteins, which differ in their sequences from all the other known insecticidal proteins of Bacillus thuringiensis. Within the midgut the 51- and 42-kDa proteins are processed to proteins of 43 and 39 kDa, respectively. The conversion of the 42-kDa protein to a 39-kDa protein results in a major increase in toxicity; the significance of the processing of the 51-kDa protein is not known. In contrast to the results with mosquito larvae, the 39-kDa protein is alone toxic for mosquito-derived tissue culture-grown cells, and this toxicity is not affected by the 51-kDa protein or its derivative, the 43-kDa protein. Comparisons of larvae from species which differ in their susceptibility to the B. sphaericus toxin indicate that the probable difference resides in the nature of the target sites of the epithelial midgut cells and not in uptake or processing of the toxin. A similar conclusion is derived from experiments involving tissue culture-grown cells from mosquito species which differ in their susceptibility to the B. sphaericus toxin. 相似文献
70.