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1.
A breakthrough in transgenic Arabidopsis thaliana research was the development of the floral dip transformation protocol, a simple and reliable method of obtaining transformants,
T1 transgenic lines, at high efficiency while avoiding the use of tissue culture. However, the traditional protocol (a “sterile”
method) of obtaining T2 transgenic lines has not evolved along with improvements in transformation technology as it continues to be laborious and
time-consuming. In this study, we report on the development of an improved protocol (a “nonsterile” method) for selecting
and growing A. thaliana transformants (T2 transgenic lines) resistant to kanamycin under nonsterile conditions. This protocol involves the use of a simple yet specialized
device that will aid in solium selection of T2 transgenic lines that can be rapidly grown in a hydroponic system. The “nonsterile” method reduces labor and time involved
as compared to the “sterile” method; moreover, it is easy to set up and maintain. This method may also be applicable to other
selecting agents, and perhaps to other plants. 相似文献
2.
We recently classified 23 bacteria into two types based on their complete genomes; “S-type” as represented by Staphylococcus aureus and “E-type” as represented by Escherichia coli. Classification was characterized by concentrations of Arg, Ala or Lys in the amino acid composition calculated from the
complete genome. Based on these previous classifications, not only prokaryotic but also eukaryotic genome structures were
investigated by amino acid compositions and nucleotide contents. Organisms consisting of 112 bacteria, 15 archaea and 18 eukaryotes
were classified into two major groups by cluster analysis using GC contents at the three codon positions calculated from complete
genomes. The 145 organisms were classified into “AT-type” and “GC-type” represented by high A or T (low G or C) and high G
or C (low A or T) contents, respectively, at every third codon position. Reciprocal changes between G or C and A or T contents
at the third codon position occurred almost synchronously in every codon among the organisms. Correlations between amino acid
concentrations (Ala, Ile and Lys) and the nucleotide contents at the codon position were obtained in both “AT-type” and “GC-type”
organisms, but with different regression coefficients. In certain correlations of amino acid concentrations with GC contents,
eukaryotes, archaea and bacteria showed different behaviors; thus these kingdoms evolved differently. All organisms are basically
classifiable into two groups having characteristic codon patterns; organisms with low GC and high AT contents at the third
codon position and their derivatives, and organisms with an inverse relationship. 相似文献
3.
Theoretically, complete rejuvenation of mature trees should occur through somatic embryogenesis, however, this has not been
extensively studied. The main objective of the present study was to increase the efficiency of in vitro clonal propagation
for mature Quercus robur (100–300 years old), by induction of somatic embryogenesis as rejuvenation step prior to establishment of shoot culture through
micropropagation of somatic embryo-derived plantlets. Shoot culture lines of “mature” origin were established from epicormic
shoots of two centenarian oak genotypes (Sainza and CR-0) and maintained by axillary shoot proliferation. Embryogenic lines
were also initiated from epicormic leaf explants of the same genotypes and maintained by secondary somatic embryogenesis.
Although the frequency of somatic embryo conversion into plantlets was low in pedunculate oak, shoot culture lines could be
established and maintained by axillary branching from several germinated somatic embryos. For each genotype and shoot culture
line of the two origins (mature tree and somatic plantlets), shoot multiplication rate and elongation as well as rooting ability
parameters were compared. Compared with “mature-origin” shoot cultures and after more than one year propagation in vitro,
shoot lines established from somatic plantlets produced a significantly higher proportion of elongated, rootable shoots (from
26.0–31.6 to 36.8–40.5%) with increased rooting ability (from 3.3–45.6% to 23.2–89.8%). In the case of 300-year-old Sainza
genotype such a high organogenic capacity was similar to shoot cultures initiated from basal sprouts. Basal sprouts are considered
as “mature” material that retains juvenile characteristics compared with epicormic shoots forced from crown branches. Somatic
embryogenesis only slightly improved plant regeneration of shoot cultures from basal sprouts, thus validating their use as
“juvenile control”. The present results provide evidence that some rejuvenation occurred during the process of somatic embryogenesis
and resulted in improved shoot growth and rooting of somatic embryo-derived culture compared with “mature” shoot culture.
The results reported in this study might be useful in embryogenic systems with low plant conversion rates. The proposed experimental
model might also be useful in finding molecular markers of plant ontogeny. 相似文献
4.
This paper deals with information transfer from the environment and “self”-organization in open, nonlinear systems far from
thermodynamic equilibrium — in the presence of either non-stationary phase jitter noise, or amplitude stationary noise. By
“self”-organization we mean here the progressive formation within the system of sequential, ordered (coherent) relationships
between appropriate dynamical variables-like for example, the phase differences between the oscillating components of the
system. We take up (in Section II) the classical Laser as a specific example and examine in detail the influence of phase
jitter noise in the mode (phase) locking process. We find—as expected—that phase fluctuations in the cavity cause degradation
of the coherent behaviour (i.e. increase the entropy) of the system — which, however, levels off, or saturates with time.
Further (in Section III) we examine systems where the number of self-sustained oscillating components may vary with time in
such a way that the maximum entropy of the system increases faster than the overall instantaneous entropy. We put forth the
hypothesis that in such cases — because of the increase of the redundancy — the system gets organized not just in spite of,
but merely because of the presence of Noise. Possible applications in biological systems (especially concerning a model of
cerebral organization) are briefly discussed. It is understood here, that the system has to display some preliminary dynamical
structure before the organizing procedure takes over. What happens afterwards is the subject of this paper. 相似文献
5.
Masazumi Mitani 《Primates; journal of primatology》1986,27(4):397-412
Japanese monkeys often exchange the particular vocal sound, “coo,” especially when they feed or move as a group. It was considered
that the “coo” sound had no positive social meaning, perhaps because the “coo” sound network and its function were hidden
behind other behavioral observations. For identification of the vocalizer only from hearing the “coo” sound, three phonetic
values, i.e., the “fundamental,” “duration,” and “formants,” plus other characteristics were used as indices of voiceprints. The results indicated that these were effective for identifying
the vocalizer in two-thirds of the adults in the study troop which was composed of 12 adults and 16 immature members. The
“coo” sound exchange network among the troop members (adults) was drawn on the basis of the voiceprint identification. The
network showed three characteristics as follows: (1) matriarchs of the kin-groups frequently exchanged “coo” sounds with each
other; (2) the other females exchanged “coo” sounds mostly within their own kin-groups; and (3) males seldom participated
in the “coo” sound exchange. This suggests that “coo” sound exchange plays a central role for the matriarch of kin-groups
in binding each kin-group and, ultimately, in binding all members together into an organized troop. 相似文献
6.
“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
7.
Here, we have characterized four pH-dependent states: alkaline state, “B” (pH 9.0), native state, “N” (pH 7.4), acid-induced
state, “A” (pH 2.2) and molten globule state, “MG” (pH 1.8) of Rhizopus niveus lipase (RNL) by CD, tryptophanyl fluorescence, ANS binding, DLS, and enzyme activity assay. This “MG” state lacks catalytic
activity and tertiary structure but it has native-like significant secondary structure. The “R
h” of all the four states of RNL obtained from DLS study suggests that the molecular compactness of the protein increases as
the pH of solution decreases. Kinetic analysis of RNL shows that it has maximum catalytic efficiency at state “B” which is
15-fold higher than state “N.” The CD and tryptophanyl fluorescence studies of RNL on GuHCl and temperature-induced unfolding reveal that the “MG” state
is more stable than the other states. The DSC endotherms of RNL obtained at pH 9.0, 7.4, and 2.2 were with two transitions,
while at pH 1.8 it showed only a single transition. 相似文献
8.
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
9.
F. J. Gallego C. Benito 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(3):393-399
Aluminium (Al) tolerance in roots of two cultivars (“Ailés” and “JNK”) and two inbred lines (“Riodeva” and “Pool”) of rye
was studied using intact roots immersed in a nutrient solution at a controlled pH and temperature. Both the cultivars and
the inbred lines analysed showed high Al tolerance, this character being under multigenic control. The inbred line “Riodeva”
was sensitive (non-telerant) at a concentration of 150 μM, whereas the “Ailes” cultivar showed the highest level of Al tolerance
at this concentration. The segregation of aluminium-tolerance genes and several isozyme loci in different F1s, F2s and backcrosses between plants of “Ailés” and “Riodeva” were also studied. The segregation ratios obtained for aluminium
tolerance in the F2s analysed were 3 : 1 and 15 : 1 (tolerant : non-tolerant) while in backcrosses they were 1 : 1 and 3 : 1. These results indicated
that Al tolerance is controlled by, at least, two major dominant and independent loci in rye (Alt1 and Alt3). Linkage analyses carried out between Al-tolerance genes and several isozyme loci revealed that the Alt1 locus was linked to the aconitase-1 (Aco1), nicotinamide adenine dinucleotide dehydrogenase-2 (Ndh2), esterase-6 (Est6) and esterase-8 (Est8) loci, located on chromosome arm 6RL. The order obtained was Alt1-Aco1-Ndh2-Est6-Est8. The Alt3 locus was not linked to the Lap1, Aco1 and Ndh2 loci, located on chromosome arms, 6RS, 6RL and 6RL respectively. Therefore, the Alt3 locus is probably on a different chromosome.
Received: 18 March 1997 / Accepted: 21 March 1997 相似文献
10.
Role of secondary metabolites as defense chemicals against ice-ice disease bacteria in biofouler at carrageenophyte farms 总被引:1,自引:0,他引:1
Charles S. Vairappan Sangeetha P. Anangdan Kai Lee Tan Shigeki Matsunaga 《Journal of applied phycology》2010,22(3):305-311
Carrageenophyte farming is an expanding economical activity in North Borneo Island, Malaysia. During routine monitoring of
“ice-ice” disease and epiphyte outbreak at commercial farms, it was apparent that culture lines were heavily (60–80%) infested
with biofoulers, particularly Acanthophora spp. and Laurencia majuscula. However, only L. majuscula showed dominance and flourished even during “ice-ice” disease outbreak. Presence of chemical defense against seaweed pathogens
was investigated in two populations of L. majuscula collected from three major carrageenophyte farms in two districts; (A) Lohok Butun, Selakan Island, and Bum-Bum Island, in
Semporna district, and (B) Telutuh, Carrington Reef, and Balambangan Island, in Kudat district. The first population contained
elatol (1), and iso-obtusol (2), and, second population contained (Z)-10,15-dibromo-9-hydroxy-chamigra-1,3(15),7(14)-triene (3) and (E)-10-15-dibromo-9-hydroxy-chamigra-1,3(15),7(14)-triene (4), as their antibacterial metabolites. All four metabolites showed highly selective inhibition against “ice-ice” disease bacteria
compared to human pathogens at 30 μg disk−1. In addition, seasonal variation of these compounds at two representative farms (Selakan Island [P-1] and Balambangan Island
[P-2]) revealed a 120–170% increase in concentration during “ice-ice” disease outbreak. Microscopy of fresh specimens showed
the presence of corps en cerise, which is the synthesis and storage site of halogenated metabolites at superficial cortical cells, branch tips, and trichoblasts.
This suggests the importance of these metabolites as defense chemicals against “ice-ice” disease bacteria in L. majuscula that grows on seaweed culture lines. 相似文献
11.
Date palm (Phoenix dactylifera L.) is one of the most important domesticated fruit trees in the Near East and North African countries. This tree has been,
for several decades, in serious threat of being completely destroyed by the “Bayoud” disease caused by Fusarium oxysporum f. sp. albedinis. In this study, 18 Syrian date palm cultivars and four male trees were analyzed according to the identity of mitochondrial
plasmid-like DNAs. A PCR strategy that employs plasmid-like DNAs-specific primer pair was used. These primers amplify a product
of either 373-bp or 265-bp that corresponds to the S- (Bayoud-susceptible) or the R-plasmid (Bayoud-resistant), respectively. Generated data revealed that only six cultivars (“Medjool”, “Ashrasi”, “Gish Rabi”,
“Khineze”, and yellow- and red-“Kabkab”) have the S-plasmid, suggesting their susceptibility to the fusariosis, while the remaining 12 cultivars and the four male trees contain
the R-plasmid, suggesting their resistance to the fusariosis. The PCR process applied here has been proved efficient for the rapid
screening for the presence of the S and R DNAs in Syrian date palm. PCR markers developed in this study could be useful for the screening of date palm lines growing
in the field. The availability of such diagnostic tool for plasmid characterization in date palm would also be of great importance
in establishing propagation and breeding programs of date palm in Syria. 相似文献
12.
The dikaryon #5026 (A2B2)+#5132 (A7B7) of the basidiomyceteCoprinus macrorhizus was treated with ultraviolet light (UV),N-methyl-N′-nitro-N-nitrosoguanidine (NG), and 5-bromouracil (BU) in order to induced developmental variations in fruiting. Among a total of
11,383 isolates, 742 were homokaryons. Fruiting test was made with the remaining 10,641 dikaryotic isolates, of which 1,594
showed abnormality in basidiocarp development. Both UV and NG were very efficient in inducing such variations, but BU was
not. The induced variations were classified into seven basic types as follows: 1) “knotless”, in which hyphal knots, the first
sign of fruiting, do not differentiate; 2) “primordiumless,” in which hyphal knots are formed, but no further development
occurs; 3) “maturationles”, in which primordia are formed, but the maturation of primordia into adult fruit bodies does not
occur; 4) “elongationless”, in which the elongation of stipe is blocked, and a basidiocarp with a very short stipe is produced;
5) “expansionless,” in which pilei do not expand normally; 6) “sporeless,” in which the formation of basidiospores is blocked
and albinic pilei bearing none or only a small amount of spores are produced; and 7) “autolysisless,” in which the autolysis
of pilei does not appear to occur. It has been noticed that the four steps of maturation, i.e. stipe elongation, pileus expansion,
spore formation, and perhaps pileus autolysis, can proceed independently. Compound types of variations such as “elongation-expansionless,”
“elongation-sporeless,” “expansion-sporeless,” and “elongation-expansion-sporeless” were also induced. UV treatment induced
maturationless at the highest rate, while NG treatment sporeless.
Contributions from the Division of Plant Morphology, Department of Biology, Faculty of Science, Okayama University. No. 117. 相似文献
13.
Madoka Y Kashiwagi T Hirotsu N Ishimaru K 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,116(5):603-612
Rice (Oryza sativa L.) chromosome segment substitution lines (CSSLs), in which chromosomal segments of the Indian landrace “Kasalath” replace
the corresponding endogenous segments in the genome of the Japanese premium rice “Koshihikari”, are available and together
cover the entire genome. Chromosome regions affecting a trait (CRATs) can be identified by comparison of phenotypes with genotypes of CSSLs. We detected 99 CRATs for 15 agronomic
or morphological traits. “Kasalath” had positively acting alleles in 53 CRATs. Its CRATs increased panicle number per plant
by up to 23.3%, grain number per panicle by up to 30.8%, and total grain number by up to 15.1%, relative to “Koshihikari”.
CRATs were identified for grain size (grain thickness and width), with positive effects of about 5.0%. A CRAT on chromosome 8
almost doubled the weight of roots in uppermost soil layers compared to “Koshihikari”. Additionally, “Kasalath” possessed
CRATs for higher lodging resistance (reduction in plant height and increase in stem diameter). In some cases, multiple CRATs
were detected in the same chromosome regions. Therefore, CSSLs with these chromosome segments might be useful breeding materials
for the simultaneous improvement of multiple traits. Five CRATs, one for plant height on chromosome 1, one for stem diameter
on chromosome 8, and three for heading date on chromosomes 6, 7, and 8 overlapped with the corresponding QTLs that already
had been mapped with back-crossed inbred lines of “Nipponbare” and “Kasalath”. In both “Koshihikari” CRATs and “Nipponbare”
QTLs, “Kasalath” had similar effects.
Both Y. Madoka and T. Kashiwagi have contributed equally to this article. 相似文献
14.
José Antonio Campoy David Ruiz José Egea David Jasper G. Rees Jean Marc Celton Pedro Martínez-Gómez 《Plant Molecular Biology Reporter》2011,29(2):404-410
Time of flowering was studied during 3 years in a BC1 apricot progeny of 73 seedlings derived from a cross between the F1
selection “Z506-07” (“Orange Red” × “Currot”) and the Spanish cultivar “Currot”. Results indicated a quantitative inheritance
of flowering time in apricot with an influence of juvenility and environmental conditions (chill accumulation) on the evaluation
and expression of this trait. Genetic maps consisting of 11 linkage groups for both parents representing the eight chromosomes
of apricot were developed using 46 apricot and peach simple sequence repeat (SSR-microsatellites) markers and were used for
the identification of quantitative trait loci (QTL). QTL analysis for flowering time allowed the identification of one significant
QTL on the linkage group 5 (G5) of “Z506-07”, and explaining most of the phenotypic variation. Two microsatellite loci (UDAp-423r
and AMPA-105) were found to be tightly linked to this important agronomic trait. Finally, we discuss the stability of the
QTL described during the 3 years of the study and the development of efficient marker-assisted selection strategies applied
to apricot and other Prunus breeding programs. 相似文献
15.
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
16.
The effects (and interaction) of two solution concentrations of Mg (50, 500, μM) and two of K (250, 4250 μM) on the growth of micropropagated plants of “F. 12/1” and “Colt” were investigated using a flowing solution culture system.
Magnesium inflow and growth of “Colt” and “F. 12/1” were inhibited to a similar extent by an increased concentration of K
in the nutrient solution. However, the consequences of this inhibition were different. Reduced inflow of Mg in “F. 12/1” caused
Mg deficiency symptoms at high and low concentrations of K, whereas this only occurred with a combination of high K concentration
and low Mg concentration in “Colt”. The distribution of dry matter within the plant was significant in determining susceptibility
to Mg deficiency. Since “F. 12/1” has a smaller root:shoot ratio than Colt it is unable to sustain the same concentration
of Mg in leaves as “Colt” irrespective of external K concentration. The molar ratio of K:Mg in soil solutions should remain
<8.5:1 in order to ensure maximum growth of “F. 12/1” and “Colt”.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
17.
Field grown foliage from the resistant soybean [Glycine max (L.) Merrill] breeding line GAT “81–327” and the susceptible cultivar “Ransom” was used to rear unparasitized larvae of the
soybean looper (SBL),Pseudoplusia includens (Walker), and larvae parasitized byCopidosoma truncatellum (Dalman). SBL larvae, whether parasitized or not, consumed more foliage when fed “Ransom”. Unparasitized larvae reared on
“81–327” had longer developmental times and suffered greater mortality than unparasitized larvae reared on “Ransom”. Parasitization
of SBL larvae byC. truncatellum increased total foliage consumption of both soybean lines. Parasitized larvae reared on the resistant “81–327” weighed less
and yielded fewer parasitoid adults.
Résumé Des larves dePseudoplusia includens (Walker) parasitées ou non parCopidosoma truncatellum (Dalman) ont été nourries des feuilles de deux lignées de soja [Glycine max (L.) Merrill] l'une, GAT “81–327” résistante et l'autre, “Ransom” sensible. Les larves deP. includens qu'elles soient parasitées ou non consommaient plus de feuillage lorsqu'elles étaient nourries de la lignée “Ransom”. Les larves non parasitées élevées sur “81–327” avaient un cycle de développement beaucoup plus long et un taux de mortalité beaucoup plus élevé que les larves non parasitées élevées comparativement sur feuilles de “Ransom”. Par contre, les larves parasitées manifestaient une consommation accrue du feuillage des deux lignées de soja. Les larves parasitées élevées sur les feuilles de la variété résistante GAT “81–327” pesaient moins et produisaient moins également de parasites adultes.相似文献
18.
Pedersen PL 《Journal of bioenergetics and biomembranes》2007,39(1):1-12
This introductory article to the review series entitled “The Cancer Cell’s Power Plants as Promising Therapeutic Targets”
is written while more than 20 million people suffer from cancer. It summarizes strategies to destroy or prevent cancers by
targeting their energy production factories, i.e., “power plants.” All nucleated animal/human cells have two types of power
plants, i.e., systems that make the “high energy” compound ATP from ADP and P
i
. One type is “glycolysis,” the other the “mitochondria.” In contrast to most normal cells where the mitochondria are the
major ATP producers (>90%) in fueling growth, human cancers detected via Positron Emission Tomography (PET) rely on both types
of power plants. In such cancers, glycolysis may contribute nearly half the ATP even in the presence of oxygen (“Warburg effect”).
Based solely on cell energetics, this presents a challenge to identify curative agents that destroy only cancer cells as they
must destroy both of their power plants causing “necrotic cell death” and leave normal cells alone. One such agent, 3-bromopyruvate
(3-BrPA), a lactic acid analog, has been shown to inhibit both glycolytic and mitochondrial ATP production in rapidly growing
cancers (Ko et al., Cancer Letts., 173, 83–91, 2001), leave normal cells alone, and eradicate advanced cancers (19 of 19)
in a rodent model (Ko et al., Biochem. Biophys. Res. Commun., 324, 269–275, 2004). A second approach is to induce only cancer
cells to undergo “apoptotic cell death.” Here, mitochondria release cell death inducing factors (e.g., cytochrome c). In a
third approach, cancer cells are induced to die by both apoptotic and necrotic events. In summary, much effort is being focused
on identifying agents that induce “necrotic,” “apoptotic” or apoptotic plus necrotic cell death only in cancer cells. Regardless
how death is inflicted, every cancer cell must die, be it fast or slow. 相似文献
19.
Kevin J. Painter 《Bulletin of mathematical biology》2009,71(5):1117-1147
Chemotaxis, the guided migration of cells in response to chemical gradients, is vital to a wide variety of biological processes,
including patterning of the slime mold Dictyostelium, embryonic morphogenesis, wound healing, and tumor invasion. Continuous models of chemotaxis have been developed to describe
many such systems, yet few have considered the movements within a heterogeneous tissue composed of multiple subpopulations.
In this paper, a partial differential equation (PDE) model is developed to describe a tissue formed from two distinct chemotactic
populations. For a “crowded” (negligible extracellular space) tissue, it is demonstrated that the model reduces to a simpler
one-species system while for an “uncrowded” tissue, it captures both movement of the entire tissue (via cells attaching to/migrating
within an extracellular substrate) and the within-tissue rearrangements of the separate cellular subpopulations. The model
is applied to explore the sorting of a heterogeneous tissue, where it is shown that differential-chemotaxis not only generates
classical sorting patterns previously seen via differential-adhesion, but also demonstrates new classes of behavior. These
new phenomena include temporal dynamics consisting of a traveling wave composed of spatially sorted subpopulations reminiscent
of Dictyostelium slugs. 相似文献
20.
Sadanand A. Dhekney Zhijian T. Li Dennis J. Gray 《In vitro cellular & developmental biology. Plant》2011,47(4):458-466
Cisgenic engineering involves isolation and modification of genetic elements from the host genome, which are reinserted to
develop plant varieties with improved characteristics. As a first step toward production of fungal-disease resistant cisgenic
grapevines, the Vitis vinifera thaumatin-like protein (vvtl-1) gene was isolated from “Chardonnay” and reengineered for constitutive expression. Embryogenic cultures of “Thompson Seedless”
were initiated from leaves and transformed with Agrobacterium to regenerate cisgenic VVTL-1 plants. Cisgene presence and copy number were confirmed by PCR and quantitative real-time PCR.
Protein expression was measured using ELISA. Among the plant lines tested, two exhibited a 7–10 day delay in powdery mildew
disease development during greenhouse screening and decreased severity of black rot disease in field tests. Berries exhibited
a 42.5% reduction in sour-bunch rot disease incidence compared to non-transformed controls after 3 wk of storage at room temperature.
Although plants recovered in this study contain viral promoters and reporter/marker genes, this is the first report of a cisgenic
approach to obtain broad-spectrum fungal-disease resistance in genetically engineered grapevine. 相似文献