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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   

3.
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   

4.
Morphology, biomass accumulation and allocation, gas exchange, and chlorophyll fluorescence were compared for one-year-old seedlings of Salix psammophila and Artemisia ordosica, two dominant desert species, in response to two water supplies (equivalent to 315.0 mm for present precipitation in growing season and to 157.5 mm for future decreasing precipitation) during 105 d. For both species, photochemical efficiency of photosystem 2 (Fv/Fm), net photosynthetic rate, transpiration rate, stomatal conductance, biomass accumulation in different organs, tree height, number of leaves, and leaf area were reduced in response to the decrease in water supply. For both species, instantaneous water use efficiency was not affected by the water deficit. However, diurnal patterns of gas exchange and biomass allocation were affected in different ways for the two species, with notably a decrease in specific leaf area and an increase in root : shoot ratio for S. psammophila only. Overall, S. psammophila was more responsive to the decreasing precipitation than A. ordosica.  相似文献   

5.
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   

6.
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   

7.
Miniaturization is an evolutionary process that is widely represented in both invertebrates and vertebrates. Miniaturization frequently affects not only the size of the organism and its constituent cells, but also changes the genome structure and functioning. The structure of the main heat shock genes (hsp70 and hsp83) was studied in one of the smallest insects, the Megaphragma amalphitanum (Hymenoptera: Trichogrammatidae) parasitic wasp, which is comparable in size with unicellular organisms. An analysis of the sequenced genome has detected six genes that relate to the hsp70 family, some of which are apparently induced upon heat shock. Both induced and constitutively expressed hsp70 genes contain a large number of introns, which is not typical for the genes of this family. Moreover, none of the found genes form clusters, and they are all very heterogeneous (individual copies are only 75–85% identical), which indicates the absence of gene conversion, which provides the identity of genes of this family in Drosophila and other organisms. Two hsp83 genes, one of which contains an intron, have also been found in the M. amalphitanum genome.  相似文献   

8.
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   

9.
Summary   Funastrum rupicola Goyder, a new species of Apocynaceae: Asclepiadoideae from Bolivia, is described and illustrated. The conservation status of this species is assessed.  相似文献   

10.
The social organization of Chinese water deer was studied in a zoological park. Most adults lived together in the mixed zone, although other habitats were available. The overlap between individual areas was largest in females. In the mating season alone, less than half of the males established territories which overlapped in small spots where most encounters occurred. Females travelled freely throughout the entire available area, but non-territorial males stayed between the territories. Except in males during mating season, very few physical contacts other than sniffing took place between individuals regardless of age, sex or status. Each animal lived alone and did not show attraction or aggressiveness towards congeners. Grouping was temporary with no durable link between individuals, not even between mothers and daughters older than 5 months. The solitary life of individuals on a common ground and the establishment of seasonal territories make the water deer unique among ruminants. The species appears to be no more social than the water chevrotain, an “ancient” species. This fits well with other characteristics of the species.  相似文献   

11.
A new Dactylella species, Dactylella alba was isolated from the ascospores of Orbilia alba collected in Wenshan County, Yunnan Province, China. Conidiophores were either not branched or occasionally branched, bearing divergent sterigmata on the tip with single conidium on each. Conidia were elongated ellipsoids, 1–2 septate, mostly 1 septate. By combining the ITS sequence with morphological characteristics, a new anamorphic species is described and illustrated together with its teleomorph.  相似文献   

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Seol E  Jung Y  Lee J  Cho C  Kim T  Rhee Y  Lee S 《Plant cell reports》2008,27(7):1197-1206
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   

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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   

16.
To elucidate the physiological adaptation of Escherichia coli due to cra gene knockout, a total of 3,911 gene expressions were investigated by DNA microarray for continuous culture. About 50 genes were differentially regulated for the cra mutant. TCA cycle and glyoxylate shunt were down-regulated, while pentose phosphate (PP) pathway and Entner Doudoroff (ED) pathway were up-regulated in the cra mutant. The glucose uptake rate and the acetate production rate were increased with less acetate consumption for the cra mutant. To identify the genes controlled by Cra protein, the Cra recognition weight matrix from foot-printing data was developed and used to scan the whole genome. Several new Cra-binding sites were found, and some of the result was consistent with the DNA microarray data. The ED pathway was active in the cra mutant; we constructed cra.edd double genes knockout mutant to block this pathway, where the acetate overflowed due to the down-regulation of aceA,B and icd gene expressions. Then we further constructed cra.edd.iclR triple genes knockout mutant to direct the carbon flow through the glyoxylate pathway. The cra.edd.iclR mutant showed the least acetate production, resulting in the highest cell yield together with the activation of the glycolysis pathway, but the glucose consumption rate could not be improved. Dayanidhi Sarkar and Khandaker Al Zaid Siddiquee have contributed equally.  相似文献   

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18.
T. Oda  C. Tanaka  M. Tsuda 《Mycoscience》2002,43(1):0081-0083
Amanita concentrica sp. nov. is described from an evergreen broad-leaved forest of Chiba Prefecture with Castanopsis cuspidata var. sieboldii and Quercus glauca. The fungus is a medium to large, white to yellowish-white mushroom characterized by many pyramidal warts on pileus, striate margin of pileus, distinct ascending concen-tric rings at upper part of stipe bulb, and inamyloid basidiospores. It is considered to belong to the section Amanita. Received: March 30, 2001 / Accepted: October 1, 2001  相似文献   

19.
Sphaerellothecium stereocaulorum sp. nov., Stigmidium beringicum sp. nov., Stigmidium stereocaulorum sp. nov. and goniocysts are described on Stereocaulon species from the northern Holarctic. Endococcus nanellus is reported new to Alaska and Mongolia. Taxonomical novelties Sphaerellothecium stereocaulorum Zhurb. & Triebel, Stigmidium beringicum Zhurb. & Triebel, Stigmidium stereocaulorum Zhurb. & Triebel.  相似文献   

20.
Plants have evolved several defense mechanisms, including resistance genes. Resistance to the root-knot nematode Meloidogyne incognita has been found in wild plant species. The molecular basis for this resistance has been best studied in the wild tomato Solanum peruvianum and it is based on a single dominant gene, Mi-1.2, which is found in a cluster of seven genes. This nematode attacks fiercely several crops, including potatoes. The genomic arrangement, number of copies, function and evolution of Mi-1 homologs in potatoes remain unknown. In this study, we analyzed partial genome sequences of the cultivated potato species S. tuberosum and S. phureja and identified 59 Mi-1 homologs. Mi-1 homologs in S. tuberosum seem to be arranged in clusters and located on chromosome 6 of the potato genome. Previous studies have suggested that Mi-1 genes in tomato evolved rapidly by frequent sequence exchanges among gene copies within the same cluster, losing orthologous relationships. In contrast, Mi-1 homologs from cultivated potato species (S. tuberosum and S. phureja) seem to have evolved by a birth-and-death process, in which genes evolve mostly by mutations and interallelic recombinations in addition to sequence exchanges.  相似文献   

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