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41.
Sequence analysis of cohesive ends of the actinophage RP3 genome and construction of a transducible shuttle vector 总被引:2,自引:0,他引:2
Abstract The sequence of the cohesive ends of actinophage RP3 DNA has been determined. As with all other phages of Gram-positive bacteria that have been studied sofar, RP3 DNA has 3'-protruding ends. A shuttle cosmid has been constructed containing this cos area which can be efficiently transduced by phage RP3 to host cells of Streptomyces rimosus . 相似文献
42.
G. Hardarson F. A. Bliss M. R. Cigales-Rivero R. A. Henson J. A. Kipe-Nolt L. Longeri A. Manrique J. J. Peña-Cabriales P. A. A. Pereira C. A. Sanabria S. M. Tsai 《Plant and Soil》1993,152(1):59-70
Field experiments were performed in Austria, Brazil, Chile, Colombia, Guatemala, Mexico and Peru as part of an FAO/IAEA Co-ordinated Research Programme to investigate the nitrogen fixing potential of cultivars and breeding lines of common bean (Phaseolus vulgaris L.). Each experiment included approximately 20 bean genotypes which were compared using the 15N isotope dilution method. Great differences in nitrogen fixation were observed between and within experiments, with average values of 35% N derived from atmosphere (% Ndfa) and highest values of 70% Ndfa being observed. These values which were larger than had been reported previously for common bean, were observed only when environmental factors were favorable. Therefore, common bean lines are available, which can support high biological nitrogen fixation. These can be used either directly as cultivars for production or in breeding programmes to enhance nitrogen fixation in other cultivars. 相似文献
43.
M. D. H. M. William R. J. Peña A. Mujeeb-Kazi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,87(1-2):257-263
Sixty Triticum tauschii (Aegilops squarrosa, 2n=2x=14, DD) accessions were evaluated for the variability of high-molecular-weight (HMW) glutenins, gliadins and isozymes of seed esterase, -amylase and glucose-phosphate isomerase. Wide variability was observed for HMW-glutenins and gliadins. The implications of unique HMW-glutenin alleles for quality parameters are discussed. Isozyme evaluations indicated more variability for the Est-D
t
5 locus as compared to the Est-D5 of bread-wheat. The polymorphism for -Amy-D
t
1 was less than that of -Amy-D1. Similar to the bread-wheat situation, Gpi-D
t
1 showed no polymorphism. The variability observed with the traits evaluated can be readily observed in T. turgidum x T. tauschii synthetic hexaploids (2n=6x=42, AABBDD) suggesting that T. tauschii accessions may be a rich source for enhancing the genetic variability of T. aestivum cultivars. 相似文献
44.
Carles Ibáñez Nuno Caiola José Barquín Oscar Belmar Xavier Benito-Granell Frederic Casals Siobhan Fennessy Jocelyne Hughes Margaret Palmer Josep Peñuelas Estela Romero Jordi Sardans Michael Williams 《Global Change Biology》2023,29(5):1248-1266
Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two–three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries. 相似文献
45.
Hui Yang Seth M. Munson Chris Huntingford Nuno Carvalhais Alan K. Knapp Xiangyi Li Josep Peñuelas Jakob Zscheischler Anping Chen 《Global Change Biology》2023,29(8):2351-2362
Negative extreme anomalies in vegetation growth (NEGs) usually indicate severely impaired ecosystem services. These NEGs can result from diverse natural and anthropogenic causes, especially climate extremes (CEs). However, the relationship between NEGs and many types of CEs remains largely unknown at regional and global scales. Here, with satellite-derived vegetation index data and supporting tree-ring chronologies, we identify periods of NEGs from 1981 to 2015 across the global land surface. We find 70% of these NEGs are attributable to five types of CEs and their combinations, with compound CEs generally more detrimental than individual ones. More importantly, we find that dominant CEs for NEGs vary by biome and region. Specifically, cold and/or wet extremes dominate NEGs in temperate mountains and high latitudes, whereas soil drought and related compound extremes are primarily responsible for NEGs in wet tropical, arid and semi-arid regions. Key characteristics (e.g., the frequency, intensity and duration of CEs, and the vulnerability of vegetation) that determine the dominance of CEs are also region- and biome-dependent. For example, in the wet tropics, dominant individual CEs have both higher intensity and longer duration than non-dominant ones. However, in the dry tropics and some temperate regions, a longer CE duration is more important than higher intensity. Our work provides the first global accounting of the attribution of NEGs to diverse climatic extremes. Our analysis has important implications for developing climate-specific disaster prevention and mitigation plans among different regions of the globe in a changing climate. 相似文献
46.
P. Rizzu E. A. Lindsay C. Taylor H. O’Donnell A. Levy P. Scambler A. Baldini 《Mammalian genome》1996,7(9):639-643
We have identified and cloned a gene, ES2, encoding a putative 476 amino acid protein with a predicted M
r
of 52,568. The gene is localized within the DiGeorge/Velocardiofacial syndrome locus on 22q11.2 and is deleted in all the
patients in which a deletion within 22q11 could be demonstrated, with the exception of one patient. ES2 is expressed in all
the tissues studied. Sequence comparison showed identity with five ESTs and at the amino acid level the sequence was highly
similar to, and collinear with, a hypothetical C. elegans protein of unknown function. Mutation analysis was performed in 16 patients without deletion, but no mutation has been found.
The cDNA sequence is conserved in mouse and is localized on MMU16B1-B3, known to contain a syntenic group in common with HSA
22q11.2.
Received: 25 March 1996 / Accepted: 15 May 1996 相似文献
47.
Summary Taurine which has antioxidant effects is also known to have effects on cell proliferation, inflammation and collagenogenesis. The aim of this study was to investigate the effect of taurine on incisional skin wounds.The mice incised on the dorsal area were divided into control and experimental groups. Saline was injected intraperitoneally to half of the animals in the control group and locally applied to the other half. Fifty mM taurine solution was given intraperitoneally to the first half of the experimental animals and locally to the second half of the experimental group.After four days of treatment, malondialdehyde (MDA) and histamine levels as well as the tensile strength of the wound tissue were measured. Structural alterations in epidermis and dermis were histologically evaluated.The locally administreated taurine significantly increased wound tensile strength by decreasing the MDA and histamine levels and prevented the degranulation of the mast cells. These observations suggest that taurine may be useful on wound healing. 相似文献
48.
49.
Oligonucleotide primer-directed mutagenesis is a useful molecular biological tool, which is invalubable for the study of the structure/function relationships in proteins and for the creation of mutant proteins possessing modified or novel biological activities. Mutagenesis studies in which a site-saturation approach is employed require a high-efficiency mutagenesis procedure, which will generate a population of mutated molecules containing an even distribution of all possible amino acid changes, or a subset thereof. This article describes such a mutagenesis technique and discusses the adaptations that are necessary to perform sitesaturation mutagenesis. 相似文献
50.
Rapid withdrawal of females from males at the end of the copulatory sequence (prior to male dismounting) characterizes several
primate species. The purpose of this paper is to make a preliminary investigation into possible functional aspects of these
“copulatory darts.” Two hypotheses are proposed; (1) females use darts to aid competing males to locate the source of copulation
calls; and (2) females dart in order to promote re-mating with the same male. Both hypotheses postulate that darts may thus
enhance male-male competition, although acquisition of other benefits may be the primary drive to darting according to the
re-mating hypothesis. Using data from 157 copulations collected from six females spread across four groups in a wild population
of chacma baboonsPapio cynocephalus ursinus, darting behaviour is described. Within females, darting distance is highly variable. Darting distance is greatest at the
time of ovulation (and maximal sexual swelling), and there is some evidence that darting may also be more frequent, and cover
greater distances, when the mating male is adult rather than juvenile. While darting behaviour appears unrelated to the presence
or absence of ejaculation, it tends to correlate positively with the duration of the female copulation call. These preliminary
results are consistent with a mediating role in male-male competition and therefore provide support for both hypotheses. 相似文献