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1.
The nature of somaclonal variation at the nucleotide sequence level was studied in rice cv. Nipponbare. First, we investigated genomic variations by using 2 molecular marker systems: RAPD (random amplified polymorphic DNA) and ISSR (inter-simple sequence repeat). This was followed by sequencing of selected bands that represented genomic variations, and pairwise sequence analysis taking advantage of the whole genome sequence of rice. In addition, transpositional activity of the active MITE, mPing, was analysed by locus-specific PCR amplifications. The 2-year-old calli and their regenerated plants, analysed with 24 RAPD and 20 ISSR primers, showed moderate levels of genomic variation (20.83% and 17.04%, respectively). To test whether DNA methylation plays a role in somaclonal variation, the calli were treated with 5-azacytidine, a chemical agent that reduces cytosine methylation by blocking the activity of DNA methyltransferase. Though dwarfism occurred in regenerants from treated calli (a hallmark of the drug treatment), there was only a slight increase in the frequency of somaclonal variation detected in the treated calli and their regenerated plants relative to untreated controls. The transposon mPing also remained immobile in both treated and untreated calli. Nevertheless, dendrograms constructed according to the Jaccard coefficient calculated by UPGMA of the ISSR bands revealed that the 5-azacytidine-treated and untreated somaclones were grouped into 2 distinct clusters, suggesting a possible indirect effect of the treatment on the genomic changes, depending on the marker used. Sequence analysis indicated a low level of variation (0.31%), with single-base-pair substitutions predominating. 相似文献
2.
“Candidatus Liberobacter,” the uncultured bacterium associated with citrus Huanglongbing (HLB) disease, is an α-Proteobacteria, and two species, “Candidatus L. africanum” and “Candidatus L. asiaticum,” have been characterized by sequence analysis of the 16S rDNA and β operon (rplKAJL-rpoBC) genes. These genes were isolated by PCR and random cloning of DNA from infected plants. However, this strategy is laborious
and allowed selection of only three Liberobacter DNA fragments. In this paper, we described isolation of additional genes
using Random Amplified Polymorphic DNA (RAPD). In total, 102 random 10-mer primers were used in PCR reactions on healthy and
Liberobacter-infected plant DNA. Eight DNA bands amplified from infected plant DNA were cloned and analyzed. Six of them were
found to be part of the Liberobacter genome by sequence and hybridization experiments. On these DNA fragments, four genes
were identified: nusG, pgm, omp, and a hypothetical protein gene. These results indicate that RAPD can be used to clone DNA of uncultured organisms.
Received: 14 September 1998 / Accepted: 6 October 1998 相似文献
3.
Four callus lines from immature embryos of a self-crossed maize (Zea mays L.) hybrid cultivar were selected for “high” (two lines) and “low” (two lines) polyamine (PA) levels. Each selected line
was exposed to culture media containing no (control) or 1% (0.171 m) NaCl and the relative growth rates were compared after subculture. Low-PA lines appeared to be tolerant to salt stress,
while high-PA lines were sensitive. Analysis of PA at the end of the subculture showed that treated calli of sensitive lines
had increased their putrescine content in comparison with their control, while putrescine remained constant in tolerant lines.
Callus lines were analysed by RAPD (random amplification of polymorphic DNA) markers. One polymorphism (550-bp band) was found,
demonstrating a genetic difference between the lines.
Received: 18 January 1997 / Revision received: 14 April 1997 / Accepted 15 July 1997 相似文献
4.
A. J. Monforte M. J. Asíns E. A. Carbonell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):706-713
A study of genotype-by-salinity interaction was carried out to compare the behavior of quantitative trait loci (QTLs) in
two F2 populations derived from crosses between the cherry tomato, Lycopersicon esculentum Mill. var. cerasiforme, and two wild relatives Lycopersicon pimpinellifolium (Jusl.) Mill. and Lycopersicon chesmannii f. minor (Hook. f.) Mull., grown at two environmental conditions (optimum and high salinity). QTLs for earliness and fruit yield could
be classified into four groups: “response-sensitive”, those detected only under control conditions or whose contribution significantly
decreased in salinity; “response-tolerant”, detected only in salinity or in which the direction of their additive effects
changed; “constitutive”, detected in both growing conditions; and “altered” QTLs, those where the degree of dominance changed
according to the presence or absence of salt. Epistatic interactions were also influenced by the salt treatment. This differential
allele effect at some (non-constitutive) QTLs induced by salt stress will make selection under an “optimum environment” unfruitful
for the “response-tolerant” QTLs. Similarly, selection under salinity will ignore “response-sensitive” QTLs. Given that salinity
is highly variable in the field, marker-assisted selection should take into account not only the “response-tolerant” but also
the “response-sensitive” QTLs although there might be cases where selection in some QTLs for both conditions is not feasible.
Comparing both populations, very few QTLs showed the same behavior.
Received: 5 August 1996 / Accepted: 25 October 1996 相似文献
5.
“Fairmount 1 thorny” (“FM1 thorny”) (a Rosa multiflora Thunb ex. J. Murr.) and a thornless sport of “FM1 thorny” (“Fairmount 1” (“FM1”)) were established in vitro to investigate
chimeral segregation under various levels of BA and to obtain a pure thornless rose. While the chimeral thornless sport was
expected to segregate in vitro and yield both thorny and thornless plantlets, “FM1 thorny” was to yield only thorny plants.
“FM1” segregated in vitro into its constituent genotypes and yielded thorny and thornless plantlets, suggesting that “FM1”
is chimeral. “FM1 thorny” produced only thorny plants in vitro. These results indicate that the “FM1 thorny” clone was not chimeral (pure thorny) and that the thornless regenerates of “FM1”
did not develop via somaclonal variation. There was a significant linear relationship between increasing BA concentration
and the percentage of thorny plants. Among a population of 690 tissue culture derived plants from all the BA experiments,
6 plants were classified as pure thornless plants 1 year later. 相似文献
6.
Masayoshi Maehata 《Ichthyological Research》2001,48(3):283-287
The mating behavior of the rock catfish Silurus lithophilus (Siluriformes: Siluridae), a species endemic to the Lake Biwa system, was observed from May to July in 1989–1994 along the
rocky shore of the lake's outlet, the Seta River. The mating behavior of S. lithophilus involved a certain behavioral sequence: “chasing,”“clinging,” and “enfolding” while “squeezing” by the male; and “circling”
by the spawned pair. The mating behavior of this species was basically similar to that of S. biwaensis, but greatly different from that of S. asotus, which spawns in running water (in ditches). The mating behavior of S. lithophilus (and S. biwaensis) might have developed as an adaptation to lentic environments such as the shores of the large river or the lake.
Received: October 25, 2000 / Revised: February 25, 2001 / Accepted: March 8, 2001 相似文献
7.
Noriko Nagata Chieko Saito Atsushi Sakai Haruko Kuroiwa Tsuneyoshi Kuroiwa 《Planta》1999,209(1):53-65
Organellar DNA in mature pollen grains of eight angiosperm species (Actinidia deliciosa Lindl., Antirrhinum majus L., Arabidopsis thaliana (L.) Heynh., Medicago sativa L., Musa acuminata Colla, Pelargonium zonale (L.) L'Hér, Petunia hybrida Vilm. and Rhododendron mucronatum (Blume) G. Don, in which the modes of organellar inheritance have been determined genetically, was observed by fluorescence
microscopy using Technovit 7100 resin sections double-stained with 4′,6-diamidino-2-phenylindole (DAPI) and 3,3′-dihexyloxacarbocyanine
iodide (DiOC6). The eight species were classified into four types, based on the presence or absence of organellar DNA in mature generative
cells: namely (1) type “m+p+”, which has both mitochondrial and plastid DNA (P. zonale), (2) type “m+p–”, which only has mitochondrial DNA (M. acuminata), (3) type “m−p+”, which only has plastid DNA (A. deliciosa, M. sativa, R. mucronatum), and (4) type “m−p−”, which has neither mitochondrial nor plastid DNA (A. majus, A. thaliana, P. hybrida). This classification corresponded to the mode of organellar inheritance determined by genetic analysis. The presence or
absence of mitochondrial and plastid DNA corresponded to paternal/biparental inheritance or maternal inheritance of the respective
organelle, respectively. When organellar DNA was present in mature generative cells (m+ or p+), the DNA content of the organelles
in the generative cells started to increase immediately after pollen mitosis one (PMI). In contrast, the DNA content of organelles
in generative cells decreased rapidly after PMI when organellar DNA was absent from mature generative cells (m− or p−). These
results indicate that the modes of inheritance (paternal/biparental inheritance or maternal inheritance) of mitochondria and
plastids are determined independently of each other in young generative cells just after PMI.
Received: 22 December 1998 / Accepted: 8 February 1999 相似文献
8.
Embryogenic calli were induced from leaf explants of coffee (Coffea canephora) on McCown's woody plant medium (WPM) supplemented with 5 μM N6–(2-isopentenyl)-adenosine (2-iP). These calli were co-cultured with Agrobacterium tumefaciens EHA101 harboring pIG121-Hm, containing β-glucuronidase (GUS), hygromycin phosphotransferase (HPT), and neomycin phosphotransferase
II genes. Selection of putative transgenic callus was performed by gradual increase in hygromycin concentration (5, 50, 100 mg/l).
The embryogenic calli surviving on medium containing 100 mg/l hygromycin showed a strong GUS-positive reaction with X-Gluc
solution. Somatic embryos were formed from these putative transgenic calli and germinated on WPM medium with 5 μM 2-iP. Regenerated
small plantlets with shoots and roots were transferred to medium containing both 100 mg/l hygromycin and 100 mg/l kanamycin
for final selection of transgenic plants. The selected plantlets exhibited strong GUS activity in leaves and roots as indicated
by a deep blue color. GUS and HPT genes were confirmed to be stably integrated into the genome of the coffee plants by the
polymerase chain reaction.
Received: 14 December 1998 / Revision received: 12 March 1999 / Accepted: 24 March 1999 相似文献
9.
Jaligot E Beulé T Rival A 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(8):1263-1269
The occurrence of "mantled" somaclonal variants (approx. 5%), which display alterations in floral organ structure, among populations of somatic embryo-derived oil palms ( Elaeis guineensis Jacq.) currently hampers any scaling-up of clonal plant micropropagation. As a first step towards the identification of abnormality-discriminating markers, we have screened a set of 27 oil palm cDNA probes for methylation-sensitive restriction fragment length polymorphisms (RFLPs) using callus genomic DNA digested with the isoschizomeric enzymes MspI and HpaII. Only two probes (CPHO62 and -63) were found to differentiate reproducibly in two different genotypic backgrounds between nodular compact calli (NCC) and fast-growing calli (FGC), which generate 5% and 100% "mantled" plantlets, respectively. Comparative analyses were then conducted on DNA from inflorescences and leaves of normal and abnormal adult regenerants. With both probes, the observed methylation patterns were strongly clone-dependent and monomorphic with respect to the phenotype of the regenerants, except for the type-specific banding pattern obtained with the CPHO62 probe on material from the LMC3 clonal offspring. The results presented here mirror the higher difference in genomic DNA methylation observed between normal and abnormal embryogenic calli when compared to more differentiated plant material. Moreover, they reinforce the paramount interest of NCC and FGC callus lines as a material of choice in the search for early epigenetic markers of the "mantled" somaclonal variation. The potential use of methylation-sensitive RFLPs for the early detection of somaclonal variation at early stages of the micropropagation process is discussed. 相似文献
10.
M. Morita A. Umemoto H. Watanabe N. Nakazono Y. Sugino 《Molecular & general genetics : MGG》1999,261(6):953-957
From a plasmid carrying the tnpA gene and one inverted repeat sequence (IR) of transposon Tn3, plasmids containing a structure characteristic of transposons, i.e., two IRs flanking a tnpA gene, were generated spontaneously in vivo. They appear to have arisen either through the formation of a “staggered” head-to-head
dimer or by so-called one-ended transposition. These putative transposons could indeed transpose to, or form cointegrates
with, a recipient plasmid. Based on these findings it is proposed that a primeval transposase gene and its target site evolved
first, and subsequently gave rise to a “fully-fledged” transposon by head-to-head dimerization or one-ended transposition.
Received: 30 October 1998 / Accepted: 1 April 1999 相似文献
11.
K. V. Kiselev A. P. Tyunin A. Y. Manyakhin Y. N. Zhuravlev 《Plant Cell, Tissue and Organ Culture》2011,105(1):65-72
DNA methylation is known to be involved in the regulation of plant development and defense mechanisms. However, there is a
general lack of data on the role of methylation in plant secondary metabolism. We have investigated the effect of a cytidine
analog, 5-azacytidine (azaC), which is known to block DNA methylation, on resveratrol biosynthesis and stilbene synthase (STS) gene expression in Vitis amurensis cultured cells. Resveratrol is a naturally occurring polyphenol that has been reported to exhibit a wide range of important
biological and pharmacological properties. We previously obtained a control cell line of V. amurensis (VV) as well as a rolB-transgenic cell line of V. amurensis (VB2) that has a higher level of resveratrol accumulation. In our experimental setup, the azaC-treated VV and VB2 calli produced
0.092% and 0.455% dry weight (DW) resveratrol, respectively. We found that treatment with 200 μM of azaC resulted in 1.9-
and 2.0-fold increases in resveratrol production in VV and VB2 calli, respectively. A quantitative real-time PCR assay for
STS gene expression in the azaC-treated VV and VB2 cells revealed that there were statistically increased expression levels of
VaSTS10 in VV calli and of VaSTS5, VaSTS6, and VaSTS10 in VB2 calli. These results demonstrate that azaC is able to increase resveratrol production in V. amurensis calli through a mechanism that involves the induction of STS gene expression. 相似文献
12.
M. H. Tixier P. Sourdille G. Charmet G. Gay C. Jaby T. Cadalen S. Bernard P. Nicolas M. Bernard 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(7):1076-1082
An intervarietal molecular-marker map was used for the detection of genomic regions influencing crossability between wheat
(Triticum aestivum L. em Thell) and rye (Secale cereale L.). Analysis of deviance and logistic marker-regression methods were conducted on data from doubled haploid lines from a
cross between “Courtot” and “Chinese Spring”. A major quantitative trait locus (QTL) involved in crossability, associated
with the marker Xfba367-5B, was detected on the short arm of chromosome 5B. An additional locus, Xwg583-5B, was indicated on the long arm of chromosome 5B. This minor QTL might correspond to Kr1 which was presumed to be the major gene controlling crossability. Another locus of the genome, Xtam51-7A on chromosome 7A, was significantly associated with this trait. Alleles of “non-crossability” were contributed by the non-crossable
cultivar “Courtot”. The three-marker model explains 65% of the difference in crossability between the two parents. The present
results are discussed in relation to those previously carried out to locate the Kr genes by using the telocentric mapping technique.
Received: 27 February 1998 / Accepted: 15 May 1998 相似文献
13.
This study analyzed genetic differences of 19 cultivars selected from somaclonal variants of Syngonium podophyllum Schott along with their parents as well as seven additional Syngonium species and six other aroids using amplified fragment length polymorphism (AFLP) markers generated by 12 primer sets. Among the 19 somaclonal cultivars, ‘Pink Allusion’ was selected from ‘White Butterfly’. Tissue culture of ‘Pink Allusion’ through organogenesis resulted in the development of 13 additional cultivars. Self-pollination of ‘Pink Allusion’ obtained a cultivar, ‘Regina Red Allusion’, and tissue culture propagation of ‘Regina Red Allusion’ led to the release of five other cultivars. The 12 primer sets generated a total of 1,583 scorable fragments from all accessions, of which 1,284 were polymorphic (81.9%). The percentages of polymorphic fragments within ‘White Butterfly’ and ‘Regina Red Allusion’ groups, however, were only 1.2% and 0.4%, respectively. Jaccard's similarity coefficients among somaclonal cultivars derived from ‘White Butterfly’ and ‘Regina Red Allusion’, on average, were 0.98 and 0.99, respectively. Seven out of the 15 cultivars from the ‘White Butterfly’ group and three out of six from the ‘Regina Red Allusion’ group were clearly distinguished by AFLP analysis as unique fragments were associated with respective cultivars. The unsuccessful attempt to distinguish the remaining eight cultivars from the ‘White Butterfly’ group and three from the ‘Regina Red Allusion’ group was not attributed to experimental errors or the number of primer sets used; rather it is hypothesized to be caused by DNA methylation and/or some rare mutations. This study also calls for increased genetic diversity of cultivated Syngonium as they are largely derived from somaclonal variants. 相似文献
14.
Cross-cultural studies have revealed broad quantitative associations between subsistence practice and demographic parameters
for preindustrial populations. One explanation is that variationin the availability of suitable weaning foods influenced the
frequency and duration of breastfeeding and thus the length of interbirth intervals and the probability of child survival
(the “weaning food availability” hypothesis). We examine the available data on weaning age variation in preindustrial populations
and report results of a cross-cultural test of the predictions that weaning occurred earlier in agricultural and pastoral
populations because dairy and cereal production increased the availability of easily digestible, nutrientrich foods appropriate
for weaning. We found that, contrary to predictions, supplementation with liquid foods other than breast milk was delayed
in agricultural populations relative to less agriculturally dependent ones and complementary feeding with solid foods was
delayed in pastoral populations relative to those less dependent on herding. Although the duration of breastfeeding was longer
in populations dependent on hunting, there was no qualitative evidence that such populations lacked foods appropriate for
weaning. The patterns observed suggest that the relationships between demography and subsistence observed among preindustrial
societies cannot be explained by the “weaning food availability” hypothesis. We discuss the implications for understanding
the mechanisms underlying prehistoric human demography, subsistence shifts, allocation to parenting and mating effort, and
the evolutionary implications of tradeoffs between diet and disease.
Earlier versions of this paper were presented at the 11th Annual Meeting of the Human Behavior and Evolution Society, Salt
Lake City, 5 June 1999 and the 4th International Anthropological Congress of Ales Hrdlička, Prague, Czech Republic, 4 September
1999.
Daniel Sellen is an assistant professor in the Department of Anthropology at Emory University; adjunct professor in the Department
of International Health, Rollins School of Public Health; and an Honorary Lecturer in the Public Health Nutrition Unit at
the london School of Hygiene and Tropical Medicine. His research interests are in nutritional ecology; the relations between
subsistence and demography; and the evolution and current diversity of young child feeding and caregiving practices. In addition
to work on demography among traditional populations, he has published “Age, Sex and Anthropometric Status of Children in an
African Pastoral Community” (Annals of Human Biology 27:1–21, 2000), “Polygyny and Child Growth in a Traditional Pastoral Society: The Case of the Datoga of Tanzania” (Human Nature 10:327–371, 1999), and “Growth Patterns among Seminomadic Pastoralists (Datoga) of Tanzania” (American Journal of Physical Anthropology 109:187–209, 1999).
Diana Smay is a graduate student in the Department of Anthropology, Emory University. Her research interests include bioarchaeology,
paleoepidemiology, the evolution of disease, and the behavioral determinants of paleodemography. Her dissertation work concerns
aspects of selective inclusion bias and short-term stress events in skeletal samples. 相似文献
15.
Kenichi Ohara Momoko Hotta Daisuke Takahashi Takashi Asahida Hitoshi Ida Tetsuya Umino 《Ichthyological Research》2009,56(4):373-379
The genetic diversity and relationship among four morphotypes of Rhinogobius sp. OR, Gobiidae (“Tōshoku,” “Shinjiko,” “Gi-tōshoku,” and “Shimahire”) were investigated with seven microsatellite DNA loci,
and amphidromy of these morphotypes was verified by strontium (Sr) and calcium (Ca) deposition in the otolith. Samples of
“Tōshoku,” “Shinjiko,” “Gi-tōshoku,” and “Shimahire” were collected from, respectively, three, three, two, and four locations
in Japan. Microsatellite analysis detected high genetic diversity (based on the number of alleles, allelic richness, and average
observed heterozygosity) in the “Tōshoku” and “Shinjiko” morphotypes relative to the “Shimahire” morphotype; the “Gi-tōshoku”
morphotype had an intermediate level of variation. Almost all pairwise F
ST values were significantly different from zero (P < 0.001), except between two populations of “Tōshoku.” Clear genetic independence was observed between the “Shinjiko” and
“Shimahire” morphotypes in the Maruyama River. A principle component analysis based on microsatellite data indicated that
the “Tōshoku,” “Shinjiko,” and “Gi-tōshoku” morphotypes were genetically similar. Furthermore, the three populations of “Tōshoku”
were closely related each other, and two of those collected from the Lake Biwa system were a single population. There was,
however, a high degree of genetic differentiation between “Shimahire” and the other morphotypes; moreover, there was high
genetic divergence among four populations of the “Shimahire” morphotype. Amphidromous migratory histories were indicated by
Sr:Ca ratios in two of three populations of the “Shinjiko” morphotype and in one of two “Gi-tōshoku” morphotypes, whereas
all populations of the “Shimahire” morphotype were freshwater residents. The large genetic divergence and low genetic diversity
in “Shimahire” are likely related to migration history. 相似文献
16.
Jiirgen -Friedrich Hake Ulrich Landwehr Andrea Schreiber 《The International Journal of Life Cycle Assessment》1998,3(4):182-183
In January 1997, the German Research Association (DFG) established a special research programme for an integrated analysis
of metallic resource flows. The programme is a joint interdisciplinary effort of the Technical University of Aachen and of
the Research Centre Jiilich. Apart from many other activities, a series of conferences is organised within this programme.
In October 1997, a first conference was held on “The Economics of Resource Flows: The Case of Aluminium”. In December 1997,
a second conference took place on “Life Cycle Assessment of Aluminium: Methods and Applications”. In April 1998 the third
workshop was held entitled “Methodological Aspects of a Resource-oriented Analysis of Material Flows”. The next conference
is planned for December 1998 on “Environmental related Aspects of Aluminium Production”. Finally, a conference on “Methods
for an Integrated Evaluation of Material Flows” is under consideration for 1999. 相似文献
17.
Evelin Ramóna Péli Nie Lei Tamás Pócs Zsanett Laufer Stefan Porembski Zoltán Tuba 《Central European Journal of Biology》2011,6(6):1065
Paper by Péli et al. “Ecophysiological responses of desiccation-tolerant cryptobiotic crusts” in Volume 6, Issue 5, 838–849 / October 2011; DOI:
10.2478/s11535-011-0049-1 contains incorrect graphic file inserted as Figure 6. The correct Figure 6, together with its caption
is presented below. 相似文献
18.
Marzia Miletto Roos Loeb A. Martjin Antheunisse Paul L. E. Bodelier Hendrikus J. Laanbroek 《Microbial ecology》2010,59(1):109-120
We studied the response of the sulfate-reducing prokaryote (SRP) communities to the experimental variation of salinity and
tide in an outdoor mesocosm setup. Intact soil monoliths were collected at two areas of the Haringvliet lagoon (The Netherlands):
one sampling location consisted of agricultural grassland, drained and fertilized for at least the last century; the other
of a freshwater marshland with more recent sea influence. Two factors, i.e., “salinity” (freshwater/oligohaline) and “tide”
(nontidal/tidal), were tested in a full-factorial design. Soil samples were collected after 5 months (June–October). Dissimilatory
(bi)sulfite reductase β subunit-based denaturing gradient gel electrophoresis (dsrB-DGGE) analysis revealed that the SRP community composition in the agricultural grassland and in the freshwater marshland
was represented mainly by microorganisms related to the Desulfobulbaceae and the Desulfobacteraceae, respectively. Desulfovibrio-related dsrB were detected only in the tidal treatments; Desulfomonile-related dsrB occurrence was related to the presence of oligohaline conditions. Treatments did have an effect on the overall SRP community
composition of both soils, but not on the sulfate depletion rates in sulfate-amended anoxic slurry incubations. However, initiation
of sulfate reduction upon sulfate addition was clearly different between the two soils. 相似文献
19.
Treatment of medullary thyroid carcinoma by combined expression of suicide and interleukin-2 genes 总被引:7,自引:0,他引:7
M. N. Soler G. Milhaud F. Lekmine F. Treilhou-Lahille D. Klatzmann S. Lausson 《Cancer immunology, immunotherapy : CII》1999,48(2-3):91-99
Inherited medullary thyroid carcinomas (MTC) are aggressive and resistant to conventional chemo- and radiotherapies. We evaluated
a novel strategy for treatment of MTC, combining “suicide” and interleukin-2 (IL-2) gene therapies. Tumors were produced in
Wag/Rij rats by orthotopic injection of the rMTC 6–23 cell line, and/or derivatives expressing the herpes simplex virus 1
thymidine kinase (HSV1-TK) gene (rMTC-TK). Ganciclovir, a nucleoside analog selectively transformed to a toxic metabolite
by HSV1-TK, totally eradicated rMTC-TK tumors in 60% of the animals. 1:1 rMTC and rMTC-TK mixed tumors were also strongly
inhibited by ganciclovir (P < 0.05), indicating the occurrence of an efficient “bystander” effect in vivo. Double labelling of rMTC cell membranes and
apoptotic nuclei revealed that, as with the TK+ cells, some TK− cells died by apoptosis. A 1:1 mixture of rMTC and rMTC-TK cells was administered to produce established tumors and then
rMTC cells, transfected to express the IL-2 gene (rMTC-IL2), were inoculated. Combined ganciclovir and IL-2 treatment improved
the inhibition of tumor growth compared to that following ganciclovir alone (86% compared to 54%, P < 0.05). This treatment also significantly enhanced macrophage activation and tumor infiltration by CD8+ and CD4+ T lymphocytes. These results open an avenue for combining suicide and immunoregulatory gene therapies for MTC management
in man.
Received: 1 October 1998 / Accepted: 1 January 1999 相似文献
20.
Methionine synthase reductase (MTRR) gene is involved in tumorigenesis by regulating DNA methylation through activation of methionine synthase (MTR). MTRR is polymorphic at nucleotide 66 (A-to-G) and the resulting variant enzyme has a lower affinity for MTR. The reported associations of MTRR A66G polymorphism with cancer risk are contradictory. Therefore, we performed a meta-analysis to better assess the associations,
including 18,661 cases and 27,678 controls from 35 studies. Crude ORs with 95% CIs were used to assess the strength of association
between the MTRR
A66G polymorphism and cancer risk. The pooled ORs were performed for homozygote model (GG vs. AA), heterozygote model (GG vs.
GA), recessive genetic model (GG vs. GA + AA), and dominant genetic model (GG + GA vs. AA), respectively. Overall, results
indicated that the G allele and GG variant genotypes were associated with a significantly increased cancer risk (G vs. A:
OR, 1.039; 95% CI, 1.009–1.078; homozygote model: OR, 1.094; 95% CI, 1.006–1.191). In subgroup analysis by ethnicity, significant
increased risks were found among Asians with G allele (G vs. A: OR, 1.063; 95% CI, 1.011–1.119; homozygote model: OR, 1.189;
95% CI, 1.055–1.341; recessive model: OR, 1.197; 95% CI, 1.068–1.341). For stratification analysis, the cancer types with
fewer than three studies were categorized into “other cancers”, and the results indicated that there was a significant elevated
cancer risk in “other cancers” in all genetic models, not in colorectal cancer, lymphoid leukemia or breast cancer. In summary,
our study suggests that the MTRR A66G polymorphism is a potential biomarker for cancer risk. 相似文献