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1.
Several unit-length minicircles from the kinetoplast DNA of Leishmania tarentolae were cloned into pBR322 and into M13 phage vectors. The complete nucleotide sequences of three different partially homologous minicircles were obtained. The molecules contained a region of approx. 80% sequence homology extending for 160–270 bp and a region unique to each minicircle. A 14-mer was found to be conserved in all kinetoplast minicircle sequences reported to date. The frequency distributions of various minicircle sequence classes in L. tarentolae were obtained by quantitative gel electrophoresis and by examination of the “T ladder” patterns of minicircles randomly cloned into M13 at several sites. By these methods we could assign approx. 50% of the total minicircle DNA into a minimum of five sequence classes. A sequence-dependent polyacrylamide gel migration abnormality was observed with several minicircle fragments both cloned and uncloned. The abnormality was dependent on the presence of a portion of the conserved region of the minicircle. 相似文献
2.
Masaru Kubota Ying-Wei Lin Keigo Hamahata Machiko Sawada Seiji Koishi Haruyo Hirota Yoshihiro Wakazono 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2000,470(2):21
The occurrence of a second neoplasm is one of the major obstacles in cancer chemotherapy. The elucidation of the genotoxic effects induced by anti-cancer drugs is considered to be helpful in identifying the degree of cancer risk. Numerous investigations on cancer patients after chemotherapy have demonstrated: (i) an increase in the in vivo somatic cell mutant frequency (Mf) at three genetic loci, including hypoxanthine–guanine phosphoribosyl-transferase (hprt), glycophorin A (GPA), and the T-cell receptor (TCR), and (ii) alterations in the mutational spectra of hprt mutants. However, the time required for and the degree of such changes are quite variable among patients even if they have received the same chemotherapy, suggesting the existence of underlying genetic factor(s). Accordingly, some cancer patients prior to chemotherapy as well as patients with cancer-prone syndrome have been found to show an elevated Mf. Based on the information obtained from somatic cell mutation assays, an individualized chemotherapy should be considered in order to minimize the risk of a second neoplasm. 相似文献
3.
A sap-transmissible virus, provisionally named Sri Lankan passion fruit mottle virus (SLPFMV), was isolated from Passiflora edulis f. flavicarpa and shown to induce leaf mottling and distortion in that host. The virus infected 23 species in five plant families with systemic infection being common in the Passifloraceae. Chenopodium amaranticolor was a good local lesion host and Passiflora foetida was a useful systemic host for purification. In P. foetida extracts, SLPFMV lost infectivity after 10 min between 70–75°C, 6–7 days at 20–23°C and at dilutions of 10--5 -W-6. The virus had flexuous, filamentous particles with a normal length of c. 841 nm. Two polypeptides of mol. wt c. 33 200 and 28 700 were detected in purified virus preparations, and a major species of double-stranded RNA (mol. wt 7.0 × 106), was detected in infected plants. Pinwheels, tubular and laminated inclusions were found in ultrathin sections of infected P. edulis f. plavicurpa and cylindrical inclusions were observed in epidermal strips. SLPFMV was transmitted by the aphids Myzus persicae, Aphis spiraecola, A. gossypü and A. cruccivora after brief acquisition feeds. SLPFMV reacted with antisera to several potyviruses including passion fruit woodiness virus, passion fruit ringspot virus, potato virus Y and watermelon mosaic virus 2 and thus, apparently, is a member of the potyvirus group. 相似文献
4.
Shape variations in the dentition and the cranium were analyzed for sevenSaguinus forms of the hairy-face tamarin by applying the factor analysis method. The results obtained for the dental and cranial measurements
were almost consistent with each other.
The magnitude of the difference in shape factors between theS. nigricollis group and theS. midas group is appreciably larger than that between the former group and theS. mystax group. If the ancestral geographic centre of origin is postulated as being within the region which is inhabited by the livingS. nigricollis group, the morphological distances between any pairs of groups correlate well with the geographic distances between them.
Concerning the dental and cranial morphologies, the physical changes in the three species group probably took place in two
directions; that is, from theS. nigricollis group to theS. mystax group, and from theS. nigricollis group to theS. midas group.
The forms belonging to each species group are more closely related to each other, with the exception ofS. imperator in theS. mystax group. The uniqueness ofS. imperator was clearly demonstrated by factor analysis and distance analysis. In theS. mystax group, although still hypothetical,S. imperator may have been related only through the basic ancestral stock toS. labiatus andS. mystax. 相似文献
5.
Shigeru Kumano Masashi Ihira Yasuo Maeda Misako Yamauchi Eiji Matsumoto Isao Matsuda 《Ecological Research》1990,5(2):221-235
Diatom assemblages of sediments obtained from three sites on Kushiro Moor were analyzed to investigate the Holocene sedimentary
history. The results showed that: 1) The Takkobu site was originally at the bottom of the paleo-Kushiro Bay, and after-wards
the paleo-Takkobu Lagoon developed, became sealed off, and changed to a freshwater lake. The succession to peat moor probably
began about 2000 yr B.P. at the Takkobu site. 2) The Tsurui site was originally at the bottom of the paleo-Kushiro Bay, then
changed to the paleo-Kushiro Lagoon and became peat moor as a result of the first Holocene regression, which finished about
3600 yr B.P. The site then returned to a brackish lake again, probably due to the second Holocene transgression between 3600
and 3000 yr B.P., thereafter passing through brackish lake and freshwater lake stages, and eventually becaming peat moor at
about 2000 yr B.P., 3) At the Chuo site, the second paleo-Kushiro Bay developed again as a result of the second Holocene transgression,
which finished about 3000 yr B.P. Thereafter, brackish or freshwater lakes, rivers, and then peat moor developed in the central
area of Kushiro Moor. 4) The second marine diatom zone (MD2 Zone), which indicates the second Holocene transgression, complete by about 3000 yr B.P., is detected only at the Chuo site
in the central area of Kushiro Moor. 相似文献
6.
Ravindra K. Malhotra Sanjiv V. Bhave Taruna D. Wakade Arun R. Wakade 《Journal of neurochemistry》1988,51(3):967-974
The effects of phorbol esters [phorbol 12,13-dibutyrate (PDB), 12-O-tetradecanoylphorbol 13-acetate (TPA), and phorbol 13-acetate] were investigated on the release of [3H]norepinephrine, 45Ca2+ accumulation, and protein kinase C activity in cultured sympathetic neurons of the chick embryo. Sympathetic neurons derived from 10-day-old chick embryo were cultured in serum-free medium supplemented with insulin, transferrin, and nerve growth factor. After 3 days, neurons were loaded with [3H]-norepinephrine and the release of [3H]norepinephrine was determined before and after electrical stimulation. Stimulation at 1 Hz for 15 s increased the release of [3H]-norepinephrine over the nonstimulation period. Stimulation-evoked release gradually declined with time during subsequent stimulation periods. Incubation of neurons in Ca2+-free Krebs solution containing 1 mM EGTA completely blocked stimulation-evoked release of [3H]-norepinephrine. Stimulation-evoked release of [3H]-norepinephrine was markedly facilitated by 3 and 10 nM PDB or TPA. The spontaneous release was also enhanced by PDB and TPA. The net accumulation of 45Ca2+ during stimulation of sympathetic neurons was increased by two- to fourfold in the presence of PDB or TPA. PDB at 1-100 nM produced a concentration-dependent increase in the activation of protein kinase C. PDB at 30 nM increased the activity of protein kinase C of the particulate fraction from 0.09 to 0.58 pmol/min/mg protein. There was no significant change in protein kinase C activity of the cytosolic fraction (0.14 pmol/min/mg versus 0.13 pmol/min/mg protein). The ratio of the particulate to cytosolic protein kinase C increased from a control value of 0.62 to 4.39 after treatment with 30 nM PDB. TPA (10 and 30 nM) also increased protein kinase C activity of the particulate fraction by six- to eightfold. Phorbol 13-acetate had no effect on protein kinase C activity, [3H]norepinephrine release, and 45Ca2+ accumulation. These results provide direct evidence that activation of protein kinase C enhances Ca2+ accumulation, which in turn leads to the facilitation of transmitter release in sympathetic neurons. 相似文献
7.
Theodore I. Grand 《Zoo biology》1992,11(1):3-15
This model of growth offers a quantitative definition for altricial and precocial newborns, makes muscular strength a benchmark for locomotor independence, and discriminates related genera as well as genera across major taxonomic divides. The model contrasts four theoretical conditions of the neonate (I, small brain, weak musculature; II, small brain, strong musculature; III, large brain, weak musculature; IV, large brain, strong musculature) with species from three orders of placental mammal. Each species exhibits a distinct mother-infant strategy from the altricial red panda cub (condition I) and the golden lion tamarin (condition III) to the precocial wildebeest calf (condition IV). The model proposes that early growth rates of brain and muscle correlate with nutrition, maternal effort during gestation and lactation, and parental care, whereas postnatal muscular growth correlates directly with adult body size and locomotor repertoire. An example of condition II (small brain, strong musculature) has not been found. This suggests that muscle does not grow in advance of the brain and that the brain acts as a pacemaker of growth. In order to increase our understanding of exotic species, noninvasive measures (body weight and length) and observations (opening of the eyes and ears, hair density, weaning, and the abilities to ther-moregulate and to move) should be supplemented with analysis of the differential tissue and organ growth. In both theoretical and practical ways analysis of deceased individuals contributes to the understanding of all species. 相似文献
8.
The effects of lithium (Li+) on the adenylyl cyclase and inositol phospholipid receptor signalling pathways were compared directly in noradrenergic and carbachol stimulated rat brain cortical tissue slices. Li+ was a comparatively weak inhibitor of noradrenaline-stimulated cyclic AMP accumulation with an IC50 of approx. 20 mM. By contrast, half-maximal effects of Li+ on inositol monophosphate (InsP) accumulation in [3H]inositol labelled tissue slices occurred at about 1 mM. A similar IC50 for Li+ of about 1 mM was also obtained for noradrenaline-stimulated accumulation of CMP-phosphatidate (CMPPA), a sensitive indicator of intracellular inositol depletion, in tissue slices that had been prelabelled with [3H]cytidine. The effect of myo-inositol (inositol) depletion on the prolonged activity of phosphoinositidase C (PIC) was examined in carbachol-stimulated corticol slices using a novel mass assay fro InsP. Exposure to a maximal dose of carbachol for 30 min in the presence of 5 mM Li+ caused a 10-fold increase in the level of radioactivity associated with the InsP fraction, but only a 2-fold increase in InsP mass. During prolonged incubations in the presence of both carbachol and Li+ the accumulation of InsP mass was enhanced if 30 mM inositol was included in the medium. The results are comptable with the inositol depletion hypothesis of Li+ action but do not support the concept that adenylyl cyclase or guanine nucleotide dependent proteins represent therapeutically relevant targets of this drug. 相似文献
9.
Claudio Nicolini Andrew S. Belmont Antonietta Martelli 《Cell biochemistry and biophysics》1986,8(2):103-117
Using HeLa S-3 cells synchronized by selective detachment, in this paper we report a parallel study of nuclear morphology
and autoradiography grain patterns between middle G1 and middle S phases: Our results show two distinct [3H]-thymidine labeling patterns. The first “peripheral” labeling pattern has a characteristic nuclear size distribution, in
contrast to the heterogeneous and varying size distributions of Feulgen-stained nuclei, and apparently is characteristic of
very early S phase. The sizes of the second labeling pattern—homogeneous or inhomogeneous grain distribution throughout the
nucleus—are equal or larger than the first and vary with S phase progression. Together, the corresponding nuclear sizes of
the labeled nuclei represent the larger extreme of nuclear areas, and the labeling index closely parallels the fraction of
nuclei with areas larger than the minimum size of the labeled nuclei. These results suggest a characteristic nuclear size
(reflecting unique intranuclear DNA distribution) as a necessary, if not sufficient, requirement for S phase initiation. Parallel
experimentation with rat liver cells—synchronized in vivo by partial hepatectomy and analyzed by thin section autoradiography—confirms
the existence of a peripheral labeling pattern in both the very early part and the very late part of S phase, which reconciles
our data with previous results and points to the fact that both initiation and termination sites for DNA replication are near
the nuclear periphery. 相似文献
10.
The araBAD operon of Salmonella typhimurium LT2. I. Nucleotide sequence of araB and primary structure of its product, ribulokinase 总被引:6,自引:0,他引:6
Hybrid plasmids containing the araBAD operon of Salmonella typhimurium LT2 were characterized by Southern blot and genetic analyses. The nucleotide sequence of araB was determined. The araB gene product, ribulokinase (EC 2.7.1.16), was purified and the results of amino acid composition analysis and partial amino acid sequence are in agreement with predictions from the DNA sequence. Ribulokinase is 569 amino acid residues long and has a calculated Mr of 61 793. Ribulokinase shares significant homology with xylulose kinase from Escherichia coli. Codon usage in the araB gene does not favor those codons which have intermediate codon-anticodon binding energy. 相似文献