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101.
It is known that few wheat cultivars maintain their resistance to rust diseases for a long period of time, particularly when crop populations become genetically more uniform. A number of genetically diverse, so far unexploited, sources of rust resistance in the natural as well as mutagenized population of wheat cultivars were identified. Several of these genes were placed in agronomically superior well-adapted backgrounds so that they could be used as pre-breeding stocks for introducing genetic diversity for resistance in a crop population. Some of these stocks when employed as parents in several cross combinations in a breeding programme have generated a number of promising cultivars with diversity for resistance.Many presently grown wheats in India, near-isogenic lines each with Lr14b, Lr14ab, Lr30 and certain international cultivars were identified as possessing diverse sources of adult plant resistance (APR) to leaf rust. Prolonged leaf rust resistance in some of the Indian cultivars was attributed to the likely presence of Lr34 either alone or in combination with other APR components. Tests of allelism carried out in certain cultivars that continue to show adequate levels of field resistance confirm the presence of Lr34, which explains the role that this gene has played in imparting durability for resistance to leaf rust. Also, Lr34 in combination with other APR components increases the levels of resistance, which suggests that combination of certain APR components should be another important strategy for breeding cultivars conferring durable and adequate levels of resistance. A new adult plant leaf rust resistance source that seems to be associated with durability in Arjun has been postulated. Likewise, cultivars possessing Sr2 in combination with certain other specific genes have maintained resistance to stem rust.Further, non-specific resistances that were transferred across widely different genotypes into two of the popular Indian wheats provided easily usable materials to the national breeding programmes for imparting durable resistance to stripe rust. 相似文献
102.
For the first time a complete ostracode and trilobite fauna is described from the Dobrovitá Formation (Ordovician) of Perunica. In contrast to the trilobite fauna the ostracode fauna evidences close relations to both Armorica and Baltica. The trilobite fauna comprises 11 species out of 11 genera, the ostracode fauna comprises 15 (5 new) species out of 15 (1 new) genera. 相似文献
103.
104.
105.
Evaluation of mass spectrometric techniques for charaterization of engineered proteins 总被引:7,自引:0,他引:7
Roepstorff Peter Schram Karl H. Andersen Jens S. Rafn Kate Baldursson Trausti Krøll Jenny Poulsen Kjeld Knudsen Jens Kristiansen Karsten 《Molecular biotechnology》1995,3(1):1-7
A simple and versatile method of in vitro site-specific mutagenesis based on polymerase chain reaction (PCR) is described.
The complete method required the use of three oligonucleotide primers and two PCRs. The product of the first PCR was used
as one of the primers (megaprimer) in the second PCR. Essentially 100% of the final product incorporated the desired mutation.
The various aspects of the procedure and its application is described in detail. 相似文献
106.
Molecular dynamics simulations were carried out on an insulin crosslinked between the N-terminal A chain and the C-terminal B chain to form a so-called mini-proinsulin: N
-A1-N
-B29-diaminosuberoyl insulin (DASI). To investigate the influence of crosslinking on the dynamics of the insulin moiety, the bridge was removed from a transient DASI structure and simulation was carried on independently with the then unlinked (ULKI) as well as with the crosslinked species. The effects of crystal packing and quaternary interactions were checked by simulating both types of monomers and dimers known from the hexamer structure. All simulations were compared to previous ones of native insulin. DASI shows general similarity to the native simulations in most parts of the structure. Deviations are visible in the segments to which the bridge is directly connected, i.e. their flexibility is reduced. Upon removal of the bridge the ULKI simulations reapproach those of native insulin. The influence of the bridge spreads over the whole molecule, but all of its main structural features remain intact. The simulations suggest that the displacement of the C-terminal B chain of native insulin, considered important for receptor interaction, is prevented by the bridge, which also partially shields some binding residues. This is in accordance with the poor biological potency of A1-B29-crosslinked insulins.Abbreviations DASI-insulin(DASI)
bovineN
-A1-N
-B29-di-aminosuberoyl insulin
- ULK-insulin (ULKI)
Native beef insulin with the bridge of DASI removed 相似文献
107.
P. N. Joshi B. Biswal G. Kulandaivelu U. C. Biswal 《Radiation and environmental biophysics》1994,33(2):167-176
Response of senescing leaves of wheat seedlings to ultraviolet A (UVA) radiation (365 nm) has been examined. The results indicate that senescence-induced disorganization of thylakoid membrane, decline in carotenoid-to-chlorophyll energy transfer, and enhancement of lipid peroxidation are furthered by radiation. The senescence-induced decline in photochemical activity of photosystem II further declines on irradiation. UVA does not specifically alter any site other than those damaged by senescence. 相似文献
108.
Peter Giesbrecht Thomas Kersten Heinrich Maidhof Dominique Krüger Peter Blümel Harald Grob Jörg Wecke 《Archives of microbiology》1994,161(5):370-383
In log-phase cells of staphylococci, cultivated under high, non-lytic concentrations of penicillin G, there occurred a novel killing process hitherto hidden behind seemingly bacteriostatic effects. Two events are essential for the apprearance of this hidden death: (i) the failure of the dividing cell to deposit enough fibrillar cross-wall material to be welded together, and (ii) a premature ripping up of incomplete cross walls along their splitting system. Hidden death started as early as 10–15 min after drug addition, already during the first division cycle. It was the consequence of a loss of cytoplasmic constituents which erupted through peripheral slit-like openings in the incomplete cross walls. The loss resulted either in more or less empty cells or in cell shrinkage. These destructions could be prevented by raising the external osmotic pressure. In contrast, the conventional non-hidden death occurred only much later and exclusively during the second division cycle and mainly in those dividing cells, whose nascent cross walls of the first division plane had been welded together. These welding processes at nascent cross walls, resulting in tough connecting bridges between presumptive individual cells, were considered as a morphogenetic tool which protects the cells, so that they can resist the otherwise fatal penicillin-induced damages for at least an additional generation time (morphogenetic resistance system). Such welded cells, in the virtual absence of underlying cross-wall material, lost cytoplasm and were killed via ejection through pore-like wall openings or via explosions in the second division plane and after liberation of their murosomes, as it was the case in the presence of low, lytic concentrations of penicillin. Bacteriolysis did not cause any of the hitherto known penicillin-induced killing processes.Dedicated to Prof. Dr. Georg Henneberg on the occasion of his 85th birthday 相似文献
109.
Photosynthesis inhibition in algae (Chlorella) and plant (spinach) chloroplasts by quaternary ammonium salts of heptacaine {N-[2-(2-heptyloxyphenylcarbamoyloxy)-ethyl]-N-alkylpiperidinium
bromides} depended on the alkyl chain length of the alkyl substituent and showed good correlations with theoretical hydrophobic
fragment constants as well as with experimentally determined physico-chemical parameters, namely extraction constants and
surface activities.
Communicated by. Z. ŠESTáK 相似文献
110.
Manganese peroxidase as an extracellular enzyme is produced by the white rot fungusPhanerochœte chrysosporium under nutrient nitrogen or carbon limitation. The effect of nitrogen concentration on the activity of manganese peroxidase
was studied using ammonium nitrate andl-asparagine as nitrogen sources. The highest activity of the enzyme was observed in cultures grown in a medium containing
75 mg/L ammonium nitrate and 0.15 g/Ll-asparagine. Manganese peroxidase was not detectable in cultures grown in the presence 0.5 g/L ammonium nitrate and 1 g/Ll-asparagine. 相似文献