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41.
42.
Charles R. Ill Tammy Brehm Bjorn K. Lydersen Rachel Hernandez Karen G. Burnett 《In vitro cellular & developmental biology. Plant》1988,24(5):413-419
Summary Studies with Human x Human (HxH), Human x Mouse (HxM), and Mouse x Mouse (MxM) hybridomas have enabled us to define specific
factors that affect hybridoma growth in a species-specific manner. Three transferrins and three lipophilic iron chelates have
been tested for their ability to support hybridoma proliferation and antibody production. The results of these studies demonstrate
that HxH hybridomas do not respond to bovine transferrin a+ concentrations up to 100 μg/ml and are approximately 100-fold less responsive to mouse transferrin than to human transferrin.
HxM and MxM hybridomas respond equally to human or mouse transferrin but are 100-fold less sensitive to bovine transferrin.
An antibody to the human transferrin receptor inhibited the growth-promoting activity of human or mouse transferrin on HxH
hybridomas but was ineffective on HxM hybridomas. This semonstrated the functionality of the human transferrin receptor in
HxH hybridomas and that human, mouse, and bovine transferrin were interacting through the mouse transferrin receptor in HxM
hybridomas. HxH and HxM hybridomas respond similarly to three different iron chelates exhibiting 80 to 110% of the growth
response to human transferrin. MxM hybridomas fail to respond to the iron chelates at similar concentrations, suggesting that
the human genome present in the other hybridoma species confers a unique ability for utilizing iron when delivered in this
form. 相似文献
43.
Sasha N. Zill S. Faith Frazier John Lankenau Karen Jepson-Innes 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(6):761-772
Summary The use of the locust (Schistocerca americana) hindleg in postural control was examined in animals that stood on a repeatedly swayed vertical substrate. Myograms were recorded from leg muscles and the angle of the femoro-tibial joint was monitored photographically. Two discrete strategies were observed,; in compensatory reactions the hindleg was held in place, while in flexion reactions, the leg was moved, most often to complete flexion of the femoro-tibial joint. Tightly coupled, rhythmic bursting occurred in the flexor and levator muscles of the leg during compensatory reactions. Bursting was initiated repeatedly when the substrate was being pulled away from the animal. Bursting was correlated with subsequent decreases in the rate of change of the femorotibial joint angle. Compensatory and flexion reactions occurred preferentially in different ranges of joint angles: most often, compensatory reactions occurred in the midrange, while flexion reactions were elicited in the extremes of joint angle. These differences may be due to the mechanical advantages of the tibial muscles and the leg may be moved to full flexion because of a locking mechanism of the flexor muscle tendon. These reactions are compared with known reflexes of hindleg proprioceptors and contrasted with similar responses of vertebrates. 相似文献
44.
Infraciliature, morphogenesis and life cycle of Endosphaera terebrans (Suctoria, Tokophridae) 总被引:1,自引:0,他引:1
The morphology, infraciliature, and life cycle of Endosphaera terebrans, a suctorian endocommensal of peritrichs, have been studied with the aid of silver impregnation. The life cycle of Endosphaera terebrans begins with infection of the host cell by a small larva. The swarmer has a pointed needle-like cellular projection and two rings of cilia. The swarmer penetrates the the peritrich, loses the cilia, and then matures into an adult. The infraciliature of the adult form has four rows of barren kinetosomes that lack kinetodesmal fibers. By endogenous budding, a migratory larva is produced that leaves the host cell through the peristomial disc and that can infect other peritrichs. 相似文献
45.
Grande Karen D.; Bender Michael L.; Irwin Brian; Platt Trevor 《Journal of plankton research》1991,13(1):1-16
In vitrorates of gross and net oxygen production were measuredas a function of light intensity in some plankton communitiescollected from Bedford Basin, Nova Scotia, and in a monoclonalculture of Synechococcus. The rate of gross oxygen productionwas measured by a technique in which the stable oxygen isotope,18O, serves as a photosynthetic tracer Net oxygen productionwas measured by automated Winkler technique. The rate of communityrespiration in the light was then determined by the differencebetween gross and net rates of oxygen production. In the naturalpopulations examined, neither gross nor net oxygen productionrates were significantly inhibited at the highest light intensitymeasured (500800 µE m2 s1) In a samplein which the dark respiration rate was small relative to themaximal rate of production [Pmax;sensu Platt et al (1980) JMar. Res., 38, 687701] the rates of lightrespiration were 3 times greater. In two other communities,with high rates of dark respiration relative to Pmaxthe ratesof light respiration were closer to rates of darkrespiration. In the Synechococcus clone, both gross and netoxygen production rates were inhibited at high light intensities.Rates of light respiration were found to varyas a function of light intensity. The greatest rates of respirationwere measured in samples incubated at light intensities thatwere just saturating (100 µE m2 s1). Therates of 14C production were also measured as a function oflight intensity The photosynthetic quotients, based on 14C productionrates and gross oxygen production rates, average 1 9 相似文献
46.
R Mu?oz R Iglesias J M Ferreras F J Arias M A Rojo T Girbés 《Cellular and molecular biology, including cyto-enzymology》1991,37(7):671-677
Long-term ingestion of sublethal n-butanol doses by rats led to a noteworthy increase in the resistance of in vitro brain ribosomal function to the acute inhibitory action of ethanol and isopropanol. Withdrawal of n-butanol did not change this adaptation process immediately. The step affected seems to be the elongation of polypeptide chains. The dependence of in vitro translation on incubation temperature was affected by the adaptation process, the translation system of chronic animals being less stimulatable than that of control animals at low temperature. 相似文献
47.
The AXB and BXA set of recombinant inbred mouse strains 总被引:1,自引:1,他引:0
Jan D. Marshall Jian-Long Mu Yin-Chai Cheah Muriel N. Nesbitt Wayne N. Frankel Beverly Paigen 《Mammalian genome》1992,3(12):669-680
The recombinant inbred (RI) set of strains, AXB and BXA, derived from C57BL/6J and A/J, originally constructed and maintained at the University of California/San Diego, have been imported into The Jackson Laboratory and are now in the 29th to 59th generation of brother-sister matings. Genetic quality control testing with 45 proviral and 11 biochemical markers previously typed in this RI set indicated that five strains had been genetically contaminated sometime in the past, so these strains have been discarded. The correct and complete strain distribution patterns for 56 genetic markers are reported for the remaining RI strain set, which consists of 31 living strains and 8 extinct strains for which DNA is available. Two additional strains, AXB 12 and BXA 17, are living and may be added to the set pending further tests of genetic purity. The progenitors of this RI set differ in susceptibility to 27 infectious diseases as well as atherosclerosis, obesity, diabetes, cancer, cleft palate, and hydrocephalus. Thus, the AXB and BXA set of RI strains will be useful in the genetic analysis of several complex diseases. 相似文献
48.
49.
Maria Zeydel Karen Puglia Mahboubeh Eghbali Jane Fant Sam Seifter Olga O. Blumenfeld 《Cell and tissue research》1991,265(2):353-359
Summary In the heart of the adult rat, fibroblasts are mainly responsible for the synthesis and deposition of the collagenous matrix. Because these cells in vitro may serve as an important model system for studies of collagen metabolism in heart tissue, we have cultured and characterized rat-heart fibroblasts from young adult and old animals. Conditions included use of media of different compositions with and without addition of ascorbate. Cell used were either cultured directly from fresh tissues or thawed previously frozen cells. Cultured cells were studied with respect to growth properties, morphology and ultrastructure and patterns of collagen. Heart fibroblasts generally resembled fibroblasts cultured from other tissues, but were more like skeletal muscle fibroblasts in that they deposited, in addition to type I collagen, type IV collagen and laminin. The fibroblasts showed a typical appearance in phase-contrast microscopy and electron microscopy. In the case of cells grown with added ascorbate, aligned collagen fibrils in the extracellular matrix showed a periodicity typical of type I collagen. The deposition of type I collagen occurred only in medium supplemented with ascorbate, and in that circumstance increased as a function of time past confluence; this was independent of the age of the animal from which the cells were obtained or of other changes of medium composition studied. Immunofluorescence studies with specific antibodies revealed that the cells deposited types I and IV collagens, laminin and fibronectin. In contrast to the case of type I collagen, the deposition of type IV collagen occurred in cells grown either with or without ascorbate. Direct observation of type IV collagen is consistent with the previous finding of type IV mRNA in cardiac fibroblasts in situ and in freshly isolated populations of these cells. 相似文献
50.
Jadwiga Jaruzelska Karen Friis Henriksen Flemming Güttler Olaf Riess Krzysztof Borski Nikolaus Blin Ryszard Slomski 《Human genetics》1991,86(3):247-250
Summary The incidence of phenylketonuria (PKU) in the western part of Poland is 1 in 5000 live births. Restriction fragment length polymorphism (RFLP) haplotypes at the phenylalanine hydroxylase locus have been analysed in 46 Polish families with PKU. Among 43 fully-informative families 16 RFLP haplotypes were identified. Haplotype 2 is the most frequently (62%) associated with Polish PKU alleles, and the codon 408 mutation is in complete linkage disequilibrium with this haplotype in Poland. This finding is in agreement with observations in other eastern European countries (German Democratic Republic, Czechoslovakia, and Hungary) and in contrast to the genotype distribution observed in western European countries. The present observation suggests the spread of classical PKU, due to the codon 408 mutation associated with haplotype 2, from east to west in European populations. Perhaps more important for genetic counselling, 62% of all PKU chromosomes in the Polish population can now be detected using only one mutantspecific oligonucleotide probe. 相似文献