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41.
Organogenic callus cultures of Solanum paludosum were obtained from root, hypocotyle and cotyledon explants of plantlets cultured in sterile conditions. These callus cultures developed multiple shoots which proliferated in Murashige and Skoog basal liquid medium. These multiple shoots produced solamargine, the main steroidal glycoalkaloid present in the unripe fruits.The optimization of the macronutrient composition of the liquid medium was performed by a method derived from the plant composition. This approach results in the establishment of an appropriate medium (SPOM medium) suitable for the improvement of both growth and solamargine production by multiple shoot cultures of S. paludosum. 相似文献
42.
Gavin R. Sills William Bridges Salah M. Al-Janabi Bruno W. S. Sobral 《Molecular breeding : new strategies in plant improvement》1995,1(4):355-363
Saccharum robustum Brandes & Jesw. ex Grassl has been suggested as the immediate progenitor species of cultivated sugarcane (S. officinarum L.) [4]. Chromosome pairing and assortment in these two species were previously studied by genetic analysis of single-dose DNA markers in parents in and 44 F1 progeny of a cross between euploid, meiotically regular 2n=80S. officinarum LA Purple andS. robustum Mol 5829 [2]. This same population was subsequently clonally propagated and evaluated in replicated trials for quantitative traits important to sugarcane breeders. Numbers of stalks, tasseled stalks, and stalks with smut, and the average diameter of two stalks were determined one day prior to harvest. At harvest, plant material from each plot was weighed and evaluated for pol (sucrose content) and fiber percentages. Clones were significantly different (P<0.01) for all traits analyzed. Associations of 83 single-dose arbitrarily primed PCR genetic markers with quantitative trait loci (QTL) of recorded traits was determined by single-factor ANOVA, and multiple regression. QTL analysis revealed markers significantly (P<0.05) associated with the expression of each trait analyzed. Markers associated with QTL after multiple regression were tested for digenic linear × linear epistatic interactions. The various multilocus models explained between 23% and 58% of the total phenotypic variation and 32% and 76% of the genotypic variation for the various traits. Digenic interactions were uncommon. Implications for marker-assisted selection in sugarcane and sugarcane domestication are discussed. 相似文献
43.
John E. Fox 《Molecular biotechnology》1995,3(3):249-258
The synthesis of large numbers of peptides can be very labor intensive and, if a conventional peptide synthesizer is used,
only small numbers of peptides can be produced within a reasonable time. The techniques described below can make large numbers
of different peptides simultaneously with varying degrees of mechanization, ranging from the wholly manual methods, to those
involving complete mechanization of the whole synthesis process. Most of the multiple synthesis methods are primarily intended
for small scale production ranging from microgram amounts up to a few tens of milligrams. All of the systems are economical
in use of solvents and reagents, enabling cost-effective synthesis. The techniques described can also be used to prepare peptide
libraries, containing several millions of peptide sequences, to enable the rapid screening of all possible permutations of
amino acids within short peptides. However, it is considered that multiple synthesis methods are not particularly suited where
extreme high purity or very long peptides are required. 相似文献
44.
There is little information addressing the phenomena of discrepancy between minimal inhibitory concentrations (MIC) and minimal lethal concentrations (MLC) values of amphotericin B (AMB) to clinical isolates of fungi. This study assessed in vitro activity of AMB against 70 clinical isolates of aspergilli: 30 strains ofAspergillus fumigatus, 20 strains ofAspergillus flavus and 20 strains ofAspergillus niger. Susceptibility tests were accomplished using a macro broth dilution procedure, with special emphasis on ascertainment of MLCs. AMB exhibited low MIC values against all clinical isolates. While we did not identify any AMB resistant isolates among 70Aspergillus spp. studied as judged by MIC levels, analysis of the data demonstrated a clear discrepancy between the MIC and MLC levels of AMB obtained against clinical isolates ofAspergillus spp. The MLC values of AMB were significantly higher than the MIC values with MIC 50 and MIC 90 of 0.29 and 0.5 µg/ml, respectively, at the second reading time, and MLC 50 and MLC 90 of 2.31 and 9.24 µg/ml, respectively (p<0.001). Additionally, minimal lethal concentrations in 36/70 (51%) of aspergillal isolates studied produced drug concentrations above those which can usually be sustained in patient plasma or tissue. 相似文献
45.
Ten soils collected from the major arable areas in Britain were used to assess the availability of soil sulphur (S) to spring
wheat in a pot experiment. Soils were extracted with various reagents and the extractable inorganic SO4-S and total soluble S(SO4-S plus a fraction of organic S) were determined using ion chromatography (IC) or inductively-coupled plasma atomic emission
spectrometry (ICP-AES), respectively. Water, 0.016 M KH2PO4, 0.01 M CaCl2 and 0.01 M Ca(H2PO4)2 extracted similar amounts of SO4-S, as measured by IC, which were consistently smaller than the total extractable S as measured by ICP-AES. The amounts of
organic S extracted varied widely between different extractants, with 0.5 M NaHCO3 (pH 8.5) giving the largest amounts and 0.01 M CaCl2 the least. Organic S accounted for approximately 30–60% of total S extracted with 0.016 M KH2PO4 and the organic C:S ratios in this extract varied typically between 50 and 70. The concentrations of this S fraction decreased
in all soils without added S after two months growth of spring wheat, indicating a release of organic S through mineralisation.
All methods tested except 0.5 M NaHCO3-ICP-AES produced satisfactory results in the regression with plant dry matter response and S uptake in the pot experiment.
In general, 0.016 M KH2PO4 appeared to be the best extractant and this extraction followed by ICP-AES determination was considered to be a good method
to standardise on. 相似文献
46.
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48.
药敏药片经临床对金黄色葡萄球菌、大肠埃希氏菌、铜绿假单胞菌等235株考核.表明药片工艺研究先进,药片与培养基结合牢固,无断裂、崩解,不渗出颗粒,抑菌圈呈同心园扩散.边缘清楚。药物含量均匀,释放度好。药片抑菌差仅1~3mm;而纸片抑菌差为2~12mm。药片变黑系数CV为2.71~4.21;而纸片CV为3.82~14.36。表明纸片片间差大,药片精密度明显好于纸片。 相似文献
49.
William L. Geary Ayesha I. T. Tulloch Euan G. Ritchie Tim S. Doherty Dale G. Nimmo Marika A. Maxwell Adrian F. Wayne 《Global Change Biology》2023,29(11):2953-2967
Ecosystem management in the face of global change requires understanding how co-occurring threats affect species and communities. Such an understanding allows for effective management strategies to be identified and implemented. An important component of this is differentiating between factors that are within (e.g. invasive predators) or outside (e.g. drought, large wildfires) of a local manager's control. In the global biodiversity hotspot of south-western Australia, small- and medium-sized mammal species are severely affected by anthropogenic threats and environmental disturbances, including invasive predators, fire, and declining rainfall. However, the relative importance of different drivers has not been quantified. We used data from a long-term monitoring program to fit Bayesian state-space models that estimated spatial and temporal changes in the relative abundance of four threatened mammal species: the woylie (Bettongia penicillata), chuditch (Dasyurus geoffroii), koomal (Trichosurus vulpecula) and quenda (Isoodon fusciventor). We then use Bayesian structural equation modelling to identify the direct and indirect drivers of population changes, and scenario analysis to forecast population responses to future environmental change. We found that habitat loss or conversion and reduced primary productivity (caused by rainfall declines) had greater effects on species' spatial and temporal population change than the range of fire and invasive predator (the red fox Vulpes vulpes) management actions observed in the study area. Scenario analysis revealed that a greater extent of severe fire and further rainfall declines predicted under climate change, operating in concert are likely to further reduce the abundance of these species, but may be mitigated partially by invasive predator control. Considering both historical and future drivers of population change is necessary to identify the factors that risk species recovery. Given that both anthropogenic pressures and environmental disturbances can undermine conservation efforts, managers must consider how the relative benefit of conservation actions will be shaped by ongoing global change. 相似文献
50.
To investigate why some species are dioecious and others monoecious, a data set of 14 morphological characters in 106 species ofElatostema was regressed onto mating system using partial multiple regression (controlling for subgeneric classification to avoid spurious associations). Morphology and mating system are significantly related (p = 0.05), and dioecious species tend to have large stipules, woody habit, and large leaves. The correlation of dioecy with large stipules is reported for the first time, but this character, like woodiness, is an indicator of plant size, suggesting a functional relationship of large plants (of the under-canopy) with dioecy. 相似文献