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1.
Kang SK Lee DH An HJ Park JH Yun SH Moon YE Bang JW Hur Y Koo DH 《Molecules and cells》2008,26(3):319-322
Little is known about the chromosomal variability and polymorphism existing in mitotic chromosomes of Citrus, mainly due to lack of reliable chromosomal markers and small chromosome size. To test the hypothesis of chromosomal polymorphism and provide the foundation of the genome organization in the Citrus cultivars, we have developed molecular cytogenetic markers for 13 Citrus species collected from Jeju island, Korea. In this study, we demonstrated that the chromosomal locations of cytogenetic markers are quite variable and extremely polymorphic, in contrast to the previous studies. The data obtained in this study will be of utmost importance in cytological systematics and karyotyping of the Citrus species. 相似文献
2.
Citrus, a key insect eggshell protein 总被引:1,自引:0,他引:1
Molecular aspects of chorion synthesis in insects have been studied deeply in species with meroistic ovaries. Information available in insects with panoistic ovaries is principally structural whereas molecular information in these species is scarce. This paper seeks to balance the above situation by describing a novel chorion gene, Citrus, from the cockroach Blattella germanica, a phylogenetically basal hemimetabolan insect with reproduction regulated by juvenile hormone and with panoistic ovaries. During previous work we discovered a series of novel genes which were specifically expressed during chorion formation in B. germanica. One of them, herein named Citrus, was peculiar due to its high copy number and its very transient expression. In the present paper we characterize Citrus in terms of structure and function. The most prominent structural feature is that the protein contains a motif which is repeated 33 times encompassing almost all the sequence. By using RNAi techniques we have demonstrated that Citrus is a key player in the building of the endochorion of B. germanica eggs. 相似文献
3.
The volatile composition of fruit from four Citrus varieties (Powell Navel orange, Clemenules mandarine, and Fortune mandarine and Chandler pummelo) covering four different species has been studied. Over one hundred compounds were profiled after HS-SPME-GC-MS analysis, including 27 esters, 23 aldehydes, 21 alcohols, 13 monoterpene hydrocarbons, 10 ketones, 5 sesquiterpene hydrocarbons, 4 monoterpene cyclic ethers, 4 furans, and 2 aromatic hydrocarbons, which were all confirmed with standards. The differences in the volatile profile among juices of these varieties were essentially quantitative and only a few compounds were found exclusively in a single variety, mainly in Chandler. The volatile profile however was able to differentiate all four varieties and revealed complex interactions between them including the participation in the same biosynthetic pathway. Some compounds (6 esters, 2 ketones, 1 furan and 2 aromatic hydrocarbons) had never been reported earlier in Citrus juices. This volatile profiling platform for Citrus juice by HS-SPME-GC-MS and the interrelationship detected among the volatiles can be used as a roadmap for future breeding or biotechnological applications. 相似文献
4.
The diversification of Citrus clementina Hort. ex Tan., a vegetatively propagated crop species. 总被引:13,自引:0,他引:13
Clementines, due to their high quality, are one of the most important cultivated citrus mandarins. As in the case of sweet orange and satsuma mandarins, genetic variability within this species is minimal when analyzed by molecular markers, because the existing varieties have not been obtained through hybridization, but through the selection of spontaneous mutations affecting traits of agronomic interest. This would explain, at least in part, the greater diversity for agronomic traits when compared to the variability for molecular markers. Another possible (nonexclusive) reason is that the types of molecular marker used are not focused on the kind of molecular change mainly involved in the origination of new clementine cultivars; i.e., are all sources of variation equally involved in the diversification of these plants? To answer this question, different kinds of markers based on primers of random sequence, simple sequence repeats, and retrotransposon sequences that may reveal point mutations, and somatic recombination and transposon activity, respectively, were used to compare the level of variability among 24 clementine varieties. Their ISSR, RAPD, and AFLP analysis provided only two polymorphic bands, distinguishing just two varieties. No variability was found by SSRs, i.e., no new allele arising through somatic recombination was detected. Instead, the amplification of sequences adjacent to retrotransposons yielded a higher number of polymorphisms (14.6 vs 2.4% for the previous mentioned marker types). Two geographical distant groups, one from North Africa and the other from Spain, have evolved in agreement with polymorphisms based on IRAP markers anchored to, at least, two different Copia-like retrotransposon sequences. Therefore, this study suggests that the DNA of this type of mobile elements is evolving faster than the DNA of other markers in this clonal lineage. 相似文献
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6.
Terrestrial tardigrades are often found in the lichens and mosses growing on trees and rocks. The assertion that tardigrades
in these habitats are very patchy in their distribution has rarely been backed by quantitative sampling. This study assesses
spatial variability in tardigrade populations inhabiting small patches (0.1 cm2 to over 5 cm2) of moss and lichen on trees and rocks at three sites in the United States of America. Tardigrades were collected from four
replicate rocks in the Ouachita Mountains of Arkansas, with 30 lichen patches collected on two adjacent boulders and 20 moss
patches on a second pair of boulders. In Fort Myers and in Citrus Springs, Florida, 30 lichen patches per tree were collected
from two pairs of trees. The tardigrades in each sample were extracted, mounted, identified, and counted. The variation in
tardigrade abundance among lichen or moss patches within rocks or trees was very high; the only consistent pattern was that
very small patches usually lacked tardigrades. Tardigrade diversity and abundance also varied greatly within sites when lichens
and mosses of the same species from different rocks and trees were compared (in the most extreme case one tree had numerous
individuals of two tardigrade species present while the other had almost no tardigrades). The results of this quantitative
sampling support the assertion that tardigrades are very patchy in distribution. Given the considerable time investment required
for the quantitative processing of tardigrade samples, this high spatial variability in tardigrade diversity and abundance
requires that researches testing ecological hypotheses about tardigrade abundance check variability before deciding how many
samples to take. 相似文献
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9.
Ethyl methanesulfonate is a chemical mutagen, which is currently being
used in plant breeding, to increase genetic variability in genes of agronomic interest, of species useful in agriculture. It primarily causes single base point mutations
by inducing guanine alkylation, resulting in GC to AT transitions. Its effect is different between clones of a genotype and between genotypes of the same species.
This review presents the results obtained in recent research, where its effect on
plant tissues, callus, and cells in suspension has been evaluated. Changes in the
phenotypic expression of somaclonal variants were reported, involving morphology, production of secondary metabolites, changes in metabolic routes of resistance, tolerance to stress, increased seed yield, among others. In addition, this
review compiles the doses and guidelines to consider before using this mutagen,
which can serve as a guide for future trials in deciding the response variables, the
type of plant explants and the selection of the study model. Mutant lines have
allowed plant breeders to have a collection of plants with different characteristics,
in places where the cultivar does not have its center of origin. It is important to
note that it is still necessary to continue evaluating the heritability of mutations
and their behaviour in the environment where they will be established, in order
to obtain new varieties of plants that can be cultivated with uniformity in their
genetic response. 相似文献
10.
Estimates of DNA and protein sequence divergence: an examination of some assumptions 总被引:5,自引:3,他引:2
Some of the assumptions underlying estimates of DNA and protein sequence
divergence are examined. A solution for the variance of these estimates
that allows for different mutation rates and different population sizes in
each species and for an arbitrary structure in the initial population is
obtained. It is shown that these conditions do not strongly affect
estimates of divergence. In general, they cause the variance of divergence
to be smaller than a binomial variance. Thus, the binomial variance that is
usually assumed for these estimates is safely conservative. It is shown
that variability in the mutation rate among sites can have an effect as
large as or larger than variability in the mutation rate among bases.
Variability in the mutation rate among bases and among sites causes the
number of substitutions between two sequences to be underestimated. Protein
and DNA sequences from several species are collected to estimate the
variability in mutation rates among sites. When many homologous sequences
are known, standard methods to estimate this variability can be used. The
estimates of this variability show that this factor is important when
considering the spectrum of spontaneous mutations and is strongly reflected
in the divergence of sequences. Smaller variability is found for the third
position of codons than for the first and second codon positions. This may
be because of less selective constraints on this position or because the
third position has been saturated with mutations for the sequences
examined.
相似文献
11.
Rafael de Grenade Robert Krueger Gary Paul Nabhan Micheline Cariño Olvera 《Economic botany》2014,68(3):266-282
The spring-fed mission oases of the Baja California peninsula, Mexico, hold several species, varieties and unique hybrids of heritage citrus, which may represent valuable genetic resources. Citrus species first arrived to the peninsula with the Jesuit missionaries (1697-1768), and new varieties were introduced during the colonial and rancho periods following the mission era. These heritage trees are grown in field and house gardens as ornamental, fruit and shade trees. Commercial citrus varieties introduced from the United States have become a strong source of economic revenue for peninsula agriculturalists. A few of the peninsula oases support commercial citrus groves, though these are primarily found in the broader valleys of the peninsula where groundwater is tapped for irrigation. The isolated environments of the mission oases and surrounding ranches have facilitated propagation of unique citrus types, and these have stabilized through integration into the cultural practices of the region. We identify and document citrus of the peninsula oases to serve as a baseline for those interested in the cultural ecology of citrus and citrus genetic resources. 相似文献
12.
Zhu Li-Wu 《植物分类学报:英文版》1988,26(5):353-361
Soluble proteins were extracted from mature leaves of 83 citrus biotypes. Their
protein patterns were obtained by acrylamide gel electrophoresis. The similarity of the protein
patterns among the samples was calculated by computer according to the principle and methods of numerical taxonomy.
The similarity comparison was made between different species and varieties included in
the Swingl’s system. The distance coefficients of similarity (DCS) is 2.13 between species in
the genus Citrus, 0.927 in Poncirus and 0.617 among Fortunella species. The DCS of biotypes
in Citrus limon, C. paradisi and C. sinensis are zero, and those in C. grandis and C. reticulata
are 0.656 and 0.863 respectively. There is no difference among satsuma mandarin, Tankan and
King mandarin, which are considered respectively as a good species in Tanaka’s system.
Ancestors of some biotypes. whose origin was unknown berore, are postulated in this work.
Jiang Bai Shang Cheng is probably a hybrid between C. junos Tanaka and mandarin, rough
lemon may be a hybrid of mandarin with citron or lime, but not with lemon. Some so-called
lemon biotypes are not in the same cluster as true lemon (Eureka or Lishon). The biotypes.
of sour orange, all of which are scattered in the phenetic tree of cluster analysis (PTCA), might
have been derived from different ancestors.
In the PTCA the evolutionary tendency from Poncirus to Macroacrumen in the citrus plants
may be found on the basis of the DCS of different genera, sections and subsections respectively with the subsection Macroacrumen.
The present author considers that if Fortunella is recognized as true genus, Cephalocitrus
should also be an acceptable genus. The position of Fortunella in the PTCA is between the
sections Cephalocitrus and Aurantium, but it does not represent its position in the phylogeny.
Taking comprehensive data into consideration it appear to be more reasonable to place C. ichangensis, as member of Papeda originated in the subtropics, in the section Papeda. 相似文献
13.
The role of CBF transcriptional activators in two Citrus species (Poncirus and Citrus) with contrasting levels of freezing tolerance 总被引:2,自引:0,他引:2
Citrus species are considered cold sensitive, yet Poncirus trifoliata , an interfertile Citrus relative, is extremely cold tolerant and can survive freezes at −20°C when fully cold acclimated. To better understand the molecular basis of this difference in freezing tolerance, C-repeat-binding factors (CBFs) from P. trifoliata and Citrus paradisi (grapefruit) were isolated and characterized. Based on our results, P. trifoliata and C. paradisi do contain a CBF pathway for cold-regulated gene expression, and similar to other species, they both appear to contain small CBF families. The nucleotide and amino acid sequences of PtCBF1 and CpCBF1 are highly homologous. However, differences in cold-induced expression were observed. PtCBF1 accumulates both earlier and to higher levels than CpCBF1 . Furthermore, CORc115 , a cold-induced group II LEA gene, also accumulates earlier and to higher levels in P. trifoliata in response to cold temperatures. The regulatory region of CORc115 contains a putative C-repeat/dehydration-responsive element that is specifically recognized and bound by PtCBF, indicating that CORc115 is a target of PtCBF1. This study provides the first evidence of a correlation between CBF expression (timing and quantity) and the degree of cold tolerance in two closely related species with wide differences in cold tolerance. The importance of using Poncirus and Citrus , two non-model organisms, to address new questions about the CBF pathway is illustrated, as these results provide novel evidence that the CBF expression pattern may play an important role in the notable difference in cold tolerance between these two related species. 相似文献
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15.
Somatic mosaicism and variable expressivity 总被引:3,自引:0,他引:3
For more than 50 years geneticists have assumed that variations in phenotypic expression are caused by alterations in genotype. Recent evidence shows that 'simple' mendelian disorders or monogenic traits are often far from simple, exhibiting phenotypic variation (variable expressivity) that cannot be explained entirely by a gene or allelic alteration. In certain cases of androgen insensitivity syndrome caused by identical mutations in the androgen receptor gene, phenotypic variability is caused by somatic mosaicism, that is, somatic mutations that occur only in certain androgen-sensitive cells. Recently, more than 30 other genetic conditions that exhibit variable expressivity have been linked to somatic mosaicism. Somatic mutations have also been identified in diseases such as prostate and colorectal cancer. Therefore, the concept of somatic mutations and mosaicism is likely to have far reaching consequences for genetics, in particular in areas such as genetic counseling. 相似文献
16.
Evolution of the differential regulation of duplicate genes after polyploidization 总被引:11,自引:0,他引:11
Summary In the 50 million years since the polyploidization event that gave rise to the catostomid family of fishes the duplicate genes encoding isozymes have undergone different fates. Ample opportunity has been available for regulatory evolution of these duplicate genes. Approximately half the duplicate genes have lost their expressions during this time. Of the duplicate genes remaining, the majority have diverged to different extents in their expression within and among adult tissues. The pattern of divergence of duplicate gene expression is consistent with the accumulation of mutations at regulatory genes. The absence of a correlation of extent of divergence of gene expression with the level of genetic variability for isozymes at these loci is consistent with the view that the rates of regulatory gene and structural gene evolution are uncoupled. The magnitude of divergence of duplicate gene expressions varies among tissues, enzymes, and species. Little correlation was found with the extent of divergence of duplicate gene expression within a species and its degree of morphological conservatism, although species pairs which are increasingly taxonomically distant are less likely to share specific patterns of differential gene expression. Probable phylogenetic times of origin of several patterns of differential gene expression have been proposed. Some patterns of differential gene expression have evolved in recent evolutionary times and are specific to one or a few species, whereas at least one pattern of differential gene expression is present in nearly all species and probably arose soon after the polyploidization event. Multilocus isozymes, formed by polyploidization, provide a useful model system for studying the forces responsible for the maintenance of duplicate genes and the evolution of these once identical genes to new spatially and temporally specific patterns of regulation. 相似文献
17.
C S Giometti M A Gemmell S L Nance S L Tollaksen J Taylor 《The Journal of biological chemistry》1987,262(26):12764-12767
A computerized search for the appearance of heritable mutations (as indicated by changes in protein expression) was conducted on three sets of mice, whose sires had been either untreated, exposed to 3 gray units of gamma radiation, or treated with 150 mg/kg ethylnitrosourea. Proteins from the livers of approximately 800 mice were separated by two-dimensional electrophoresis, and abundances were measured by using image analysis techniques. Heritable mutations were detected by the appearance of new proteins or by the quantitative decrease in abundance of normally occurring proteins. Measurements of the variability of the protein abundance indicate that at least 48 proteins are consistent enough to be used in searches when mutations are expected to result in a 50% reduction in the normal amount of protein. New proteins were found in four offspring from ethylnitrosourea-treated mice, and in each case a nearby spot was found to be significantly diminished. These mutations were confirmed in subsequent generations. A computer-assisted search detected three of these mutations on the basis of the abundance decrease alone. These results indicate that two-dimensional electrophoresis can be used to detect mutations reflected as quantitative changes in protein expression, provided that the proteins to be monitored are quantitatively stable when samples from different individuals are compared. 相似文献
18.
Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) is sporadically captured in the Rio Grande Valley of Texas. Although its preferred hosts are in the Sapotaceae family, several varieties of Citrus, including grapefruit and oranges are listed as alternate hosts. Although Mexican fruit fly, Anastrepha ludens (Loew), is known to be a major pest of Citrus, doubt exists as to the status of Citrus as a breeding host for A. serpentina. To evaluate the host status of commercial Citrus for A. serpentina we compared oviposition and development with that of A. ludens under laboratory conditions with 'Rio Red' grapefruit (Citrus paradisi MacFayden) and 'Valencia' oranges [Citrus sinensis (L.) Osbeck] in different stages of maturity. Both fly species oviposited in early season fruit in which the eggs and larvae died in the fruit albedo. Survival of either species to the adult stage occurred in later season grapefruit. In oranges, no A. serpentina larvae survived compared with 150 A. ludens surviving to adults. Survival on both Citrus species was much lower for A. serpentina, only approximately 5% of eggs eclosed into larvae in grapefruit compared with approximatley 50% for A. ludens. In oranges approximately 16% of A. serpentina eggs eclosed compared with approximately 76% for A. ludens. In grapefruit, only one fourth as many A. serpentina larvae survived to the adult stage compared with A. ludens. Additional experiments were performed in a greenhouse on small, caged trees of la coma (Sideroxylon celastrinum H.B.K.), a Texas species of Sapotaceae. The A. serpentina females readily oviposited into these berries and normal adults emerged. The present low incidence of the adults, coupled with the high mortality during development of the larvae, suggests that Texas citrus is unlikely to support a breeding population of A. serpentina. 相似文献
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