共查询到20条相似文献,搜索用时 0 毫秒
1.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes. 相似文献
2.
3.
Stefano Fenoglio Tiziano Bo José Manuel Tierno de Figueroa Manuel Jesus López-Rodríguez Giorgio Malacarne 《Hydrobiologia》2008,607(1):11-16
Demographic responses of a commensal annelid of freshwater crayfish, Stratiodrilus aeglaphilus, to a sublethal organic enrichment were tested. Censuses of the S. aeglaphilus population were performed every 3 days during a 27 days period. The demographic variables were estimated using a quadratic
programming method. Population growth rate (λ) was 1.0230 in the control, and 0.9145 in the organic enrichment treatment,
it was indicating positive growing and decrease, respectively. Decomposition analysis showed an antagonistic response of the
demographic parameters to organic enrichment, with negative contributions from eggs and juveniles stasis and growing probabilities,
and positive contributions from adults survival and fecundity. After the organic enrichment, the positive effect on adults
could not compensate the adverse effect on the early stages, thus causing a reduction of the population density of S. aeglaphilus.
Handling editor: D. Dudgeon 相似文献
4.
Mature osteoclasts, multinucleated giant cells responsible for bone resorption, are terminally differentiated cells with a
short life span. Recently, we have demonstrated that osteoclast apoptosis is regulated by ERK activity and Bcl-2 family member
Bim. In this paper, we summarize the methods we used to study osteoclast apoptosis in vitro and in vivo. Using adenovirus and retrovirus vectors, we were able to introduce foreign genes into osteoclasts and examine their effects
on osteoclast survival in vitro. In addition, we established the modified methods for in situ hybridization and BrdU labeling of bone sections from mice
to study osteoclast survival in vivo. The detailed methods described here could be useful for studying the biological process in bone. 相似文献
5.
Abstract
Numerous miniature inverted repeat transposable elements (MITEs) are present in the rice genome but their transposition mechanisms
are unknown. In this report, we present evidence that two novel MITE families may have arisen from Mutator-related transposable elements and thus may use a transposition mechanism similar to that of Mutator elements. Two families of novel MITEs, namely, MDM-1 and MDM-2, were identified by searching for MITEs nested with Kiddo, a previously identified MITE family. MDM-1 and MDM-2 bear hallmarks of Mutator elements, such as long terminal inverted repeats (LTIRs), 9-bp target-site duplications (TSDs), and putative transposase
binding sites. Strikingly, the MDM-1 family has a 9-bp terminus identical to that of a rice Mutator-like element (MULE-9) and the MDM-2 family has an 8-bp terminus identical to that of the maize autonomous Mutator element MuDR. A putative transposase homologous to MURA protein is identified for the MDM-2 family. Thus, these two novel MITE families, with a total copy number of several hundred in rice, are designated Mutator-derived MITEs (MDMs). Interestingly, sequence decay analysis of MDM families revealed a number of insertion site duplications (ISDs) in the alignment gaps, and widespread historical nesting
events are proposed to account for the existence of these ISDs. In addition to its value for discovering new MITEs, the nesting
analysis approach used in this study simultaneously identifies MITE insertion polymorphisms. 相似文献
6.
New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora:
Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii
,
Rumex densiflorus var. pycnanthus
,
R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage. 相似文献
7.
An early flowering mutant plant of Eucalyptus grandis with normal vegetative growth was found in a nursery in northern Brazil. This mutant plant flowers at approximately 90 days
from germination. A cross between a wild-type (normal flowering) tree and the mutant was carried out, generating a progeny
of 88 individuals where early flowering segregated in an approximate 1:1 ratio. A genome scan with 100 microsatellite markers
distributed across the genome was carried out using bulk segregant analysis (BSA) on two contrasting bulks of 15 plants each.
Linkages (LOD>3.0) with a major effect early flowering quantitative trait locus (QTL) were detected and confirmed by a full
scale cosegregation analysis for markers EMBRA27, EMBRA60, EMBRA164, EMBRA158, EMBRA91, and EMBRA65. A localized linkage map
involving the six loci and the early flowering QTL named Eucalyptus early flowering 1 (Eef1) was constructed belonging to linkage group #2 in the existing microsatellite reference map. The Eef1 locus was mapped between markers EMBRA27 and EMBRA164, with distances of 21.8 and 6.4 cM, respectively. In introgression
experiments, these two markers could be successfully used with an expected precision of 98% to select plants carrying the
Eef1 mutant allele, assuming no recombination interference in the genomic segment. Early flowering could be a very useful trait
both in breeding as well as experimental genetics of Eucalyptus. 相似文献
8.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
9.
Noel H. Holmgren 《Brittonia》2018,70(1):115-139
A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations. 相似文献
10.
Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner.
The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate
larvae Galleria
mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host. 相似文献
11.
Tropilaelaps
mercedesae is a serious ectoparasite of Apis
mellifera in China. The aim of this study was to investigate the infestation rates and intensity of T. mercedesae in A. mellifera in China, and to explore the relative importance of climate, district, management practices and beekeeper characteristics
that are assumed to be associated with the intensity of T. mercedesae. Of the 410 participating apiaries, 379 apiaries were included in analyses of seasonal infestation rates and 352 apiaries
were included in multivariable regression analysis. The highest infestation rate (86.3%) of T. mercedesae was encountered in autumn, followed by summer (66.5%), spring (17.2%) and winter (14.8%). In autumn, 28.9% (93) of the infested
apiaries were in the north (including the northeast and northwest of China), 71.1% (229) were in the central and south (including
east, southeast and southwest China), and 306 apiaries (82.9%) were co-infested by both T. mercedesae and Varroa. Multivariable regression analysis showed that geographical location, season, royal jelly collection and Varroa infestation were the factors that influence the intensity of T. mercedesae. The influence of beekeeper’s education, time of beekeeping, operation size, and hive migration on the intensity of T. mercedesa was not statistically significant. This study provided information about the establishment of the linkage of the environment
and the parasite and could lead to better timing and methods of control. 相似文献
12.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
13.
Lucentini Livia Vercillo Francesca Palomba Antonella Panara Fausto Ragni Bernardino 《Conservation Genetics》2007,8(3):757-759
A non-invasive genetic approach has been recently employed in the population genetics of wild species, using faeces that could
be easily collected, particularly of elusive or endangered species. However, faeces of pine (Martes martes) and beech marten (M. foina) can be morphologically similar and could be confused with those of polecat (Mustela putorius) and red fox (Vulpes vulpes). On this basis, a rapid, simple and inexpensive RFLP protocol using a cytochrome b (Cyt b) gene fragment of mtDNA, isolated from faecal samples, was performed to distinguish the above-mentioned species. 相似文献
14.
Synopsis We studied territorial behaviour of the acanthurid surgeonfish Acanthurus sohal and pomacentrid damselfish Plectroglyphidodon leucozona on fringing reefs in Ras Mohammed National Park, Red Sea, Egypt. We investigated trespass times, the number of agonistic acts, their intensity and the agonism elicited (number agonistic acts/total trespass time) for all intruders. Five families (Pomacentridae, Chaetodontidae, Acanthuridae, Labridae and Scaridae) were dominant among the 14 we recorded in our study sites. Seven species belonging to four families were resident inside A. sohal territories. Of the other 66 species we observed, 45 are intruders. The territory-holder did not react equally agonistically toward all these intruders. A. sohal showed a high number of agonistic acts against conspecifics and the parrotfish Cetoscarus bicolor. The intensity of the agonistic encounters, however, showed a different picture, with a low level for conspecifics and C. bicolor, respectively. A. sohal showed a high degree of agonistic intensity toward only one parrotfish, Chlorurus sordidus. The highest values of Agonism elicited were recorded against Scarus ghobban, followed by Siganus rivulatus and Zebrasoma desjardinii . Despite these high values, the intensity was relatively weak. The territories of A. sohal were large (average 12.5m2); those of P.leucozona were ca. 20 times smaller (average 0.6m2). A. sohal spent most of their time swimming (patrolling) along the territory border, stopping briefly to feed on algae. On the other hand, P. leucozona spent most of their time swimming and sheltering. 相似文献
15.
16.
Kurtzman CP 《Antonie van Leeuwenhoek》2011,100(3):455-462
Ogataea
parapolymorpha sp. n. (NRRL YB-1982, CBS 12304, type strain), the ascosporic state of Candida
parapolymorpha, is described. The species appears homothallic, assimilates methanol as is typical of most Ogataea species and forms hat-shaped ascospores in asci that become deliquescent. O. parapolymorpha is closely related to Ogataea
angusta and Ogataea
polymorpha. The three species can be resolved from gene sequence analyses but are unresolved from fermentation and growth reactions
that are typically used for yeast identification. On the basis of multiple isolates, O. angusta is known only from California, USA, in association with Drosophila and Aulacigaster flies, O. parapolymorpha is predominantly associated with insect frass from trees in the eastern USA but O. polymorpha has been isolated from various substrates in the USA, Brazil, Spain and Costa Rica. 相似文献
17.
Notocactus scopa cv. Soonjung was subjected to in planta Agrobacterium tumefaciens-mediated transformation with vacuum infiltration, pin-pricking, and a combination of the two methods. The pin-pricking combined with vacuum infiltration (20-30 cmHg for 15 min) resulted in a transformation efficiency of 67-100%, and the expression of the uidA and nptII genes was detected in transformed cactus. The established in planta transformation technique generated a transgenic cactus with higher transformation efficiency, shortened selection process, and stable gene expression via asexual reproduction. All of the results showed that the in planta transformation method utilized in the current study provided an efficient and time-saving procedure for the delivery of genes into the cactus genome, and that this technique can be applied to other asexually reproducing succulent plant species. 相似文献
18.
19.
20.
Fernanda Laroza Paganelli Eliana Gertrudes de Macedo Lemos Lúcia Maria Carareto Alves 《World journal of microbiology & biotechnology》2011,27(4):773-778
Polyhydroxyalkanoates (PHAs) are hydroxyalkanoate polymers that are produced and accumulate by many kinds of bacteria. These
polymers act as an energy store for bacteria. Polyhydroxybutyrate (PHB) is the most studied polymer in the PHA family. These
polymers have awakened interest in the environmental and industrial research areas because they are biodegradable and have
thermoplastic qualities, like polypropylene. In this work, we analyzed the PHB production in Bradyrhizobium sp., Rhizobium leguminosarum bv. phaseoli, and Rhizobium huautlense cultured with two different carbon sources. We did biochemical quantification of PHB production during the three phases of
growth. Moreover, these samples were used for RNA extraction and phbC gene expression analysis via real-time PCR. The bacteria showed different manner of growth, PHB accumulation and phbC gene expression when different quantity and quality of carbon sources were used. These results showed that under different
growth media conditions, the growth and metabolism of different species of bacteria were influenced. These differences reflect
the increase or decrease in PHB accumulation. 相似文献