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51.
The ternary transformation system: constitutive virG on a compatible plasmid dramatically increases Agrobacterium-mediated plant transformation 总被引:5,自引:0,他引:5
This paper describes a so-called ternary transformation system for plant cells. We demonstrate that Agrobacterium tumefaciens strain LBA4404 supplemented with a constitutive virG mutant gene (virGN54D) on a compatible plasmid is capable of very efficient T-DNA transfer to a diverse range of plant species. For the plant species Catharanthus roseus it is shown that increased T-DNA transfer results in increased stable transformation frequencies. Analysis of stably transformed C. roseus cell lines showed that, although the T-DNA transfer frequency is greatly enhanced by addition of virGN54D, only one or a few T-DNA copies are stably integrated into the plant genome. Thus, high transformation frequencies of different plant species can be achieved by introduction of a ternary plasmid carrying a constitutive virG mutant into existing A. tumefaciens strains in combination with standard binary vectors. 相似文献
52.
Grützner F Deakin J Rens W El-Mogharbel N Marshall Graves JA 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2003,136(4):867-881
The first specimen of platypus (Ornithorhynchus anatinus) that reached Britain in the late 18th century was regarded a scientific hoax. Over decades the anatomical characteristics of these unique mammals, such as egg laying and the existence of mammary glands, were hotly debated before they were accepted. Within the last 40 years, more and more details of monotreme physiology, histology, reproduction and genetics have been revealed. Some show similarities with birds or reptiles, some with therian mammals, but many are very specific to monotremes. The genome is no exception to monotreme uniqueness. An early opinion was that the karyotype, composed of a few large chromosomes and many small ones, resembled bird and reptile macro- and micro-chromosomes. However, the platypus genome also features characteristics that are not present in other mammals, such as a complex translocation system. The sex chromosome system is still not resolved. Nothing is known about dosage compensation and, unlike in therian mammals, there seems to be no genomic imprinting. In this article we will recount the mysteries of the monotreme genome and describe how we are using recently developed technology to identify chromosomes in mitosis, meiosis and sperm, to map genes to chromosomes, to unravel the sex chromosome system and the translocation chain and investigate X inactivation and genomic imprinting in monotremes. 相似文献
53.
A large-subunit mitochondrial ribosomal DNA sequence translocated to the nuclear genome of two stone crabs (Menippe) 总被引:1,自引:0,他引:1
Two DNA sequences that appear to be homologous to large-subunit
mitochondrial ribosomal RNA genes have been identified in the stone crabs
Menippe mercenaria and M. adina. Amplification from whole genomic DNA by
polymerase chain reaction (PCR) with oligonucleotide primers based on
conserved portions of large-subunit mitochondrial rRNA genes consistently
amplified two products of similar length (565 and 567 bp). These products
differed at 3% of their nucleotide bases, and could be distinguished by a
HindIII site. Only one of these sequences (designated the A sequence) was
detected by PCR in purified mitochondrial DNA. The other (designated the B
sequence) hybridized to total genomic DNA at a level consistent with a
nuclear genome location. It is unlikely that the type B product would have
been recognized as a nuclear copy by examination of its sequence alone.
This is the first report of a mitochondrial gene sequence translocated into
the nuclear genome of a crustacean.
相似文献
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Rainer Ignetik Michael A. B. Deakin Chris Fandry 《Bulletin of mathematical biology》1981,43(3):361-370
The irreversible Michaelis-Menten scheme may be reduced to a pair of autonomous first-order differential equations. The phase-plane
behaviour of these is investigated. 相似文献
57.
Stoats are significant predators of native fauna in New Zealand. They occur in many habitat types and consume a wide range of prey. The diet of stoats in the Tasman River, South Canterbury, was studied by analysis of scats and den contents. Analysis of 206 scats showed that stoats ate mainly lagomorphs, birds and invertebrates. Minor components included mice, lizards, fish and hedgehogs. Stoats ate more birds in spring than in autumn, and female stoats ate more invertebrates than did males. The contents of 219 dens collected in the same area at the same time provided further information. Birds and lagomorphs occurred at high frequency in dens, and other components were minor. Remains in dens were larger than in scats and allowed identification of many more prey items to species level. Den contents revealed a potentially substantial impact of stoats on threatened shorebirds locally; this impact was not detected by analysis of scats. 相似文献
58.
Observed effects of inorganic phosphate (P(i)) on active isometric muscle may provide the answer to one of the fundamental questions in muscle biophysics: how are the free energies of the chemical species in the myosin-catalyzed ATP hydrolysis (ATPase) reaction coupled to muscle force?. Pflugers Arch. 414:73-81) showed that active, isometric muscle force varies logarithmically with [P(i)]. Here, by simultaneously measuring electron paramagnetic resonance and the force of spin-labeled muscle fibers, we show that, in active, isometric muscle, the fraction of myosin heads in any given biochemical state is independent of both [P(i)] and force. These direct observations of mechanochemical coupling in muscle are immediately described by a muscle equation of state containing muscle force as a state variable. These results challenge the conventional assumption mechanochemical coupling is localized to individual myosin heads in muscle. 相似文献
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