Chromosomal dispositions were analyzed on the metaphase plate of tetraploid cotton (AADD). At metaphase, the two subgenomes, A and D, were separated in a radial pattern in which the small D subgenome chromosomes tended to concentrate at the center and the large A subgenome chromosomes were scattered about the periphery on the metaphase plate. Although the ordered chromosome arrangement was disturbed in an artificial hexaploid (AADDGG), the separation pattern could be recovered after the majority of the additional genome (GG) chromosomes were removed by backcrossing the artificial hexaploid with the tetraploid cotton (AADD). A similar genome separation phenomenon was also found in synthesized tetraploid cotton (AAGG). These results indicate that the genome separation pattern could be established immediately after tetraploid cotton formation and could be stably inherited in tetraploid cotton. Given the evidence of parental genome separation in other plants and animals, we speculated that genome separation might be a normal phenomenon in diploid and polyploid species. These finding will shed light on the chromosome conformation in plant cells. 相似文献
Introduction: Measuring the immediate changes in cells that arise from changing environmental conditions is crucial to understanding the underlying mechanisms involved. These changes can be measured with metabolic stable isotope fully labeled proteomes, but requires looking for changes in the midst of a large background. In addition, labeling efficiency can be an issue in primary and fully differentiated cells.
Area covered: Azidohomoalanine (AHA), an analog of methionine, can be accepted by cellular translational machinery and incorporated into newly synthesized proteins (NSPs). AHA-NSPs can be coupled to biotin via CuAAC-mediated click-chemistry and enriched using avidin-based affinity purification. Thus, AHA-containing proteins or peptides can be enriched and efficiently separated from the whole proteome. In this review, we describe the development of mass spectrometry (MS) based AHA strategies and discuss their potential to measure proteins involved in immune response, secretome, gut microbiome, and proteostasis as well as their potential for clinical uses.
Expert commentary: AHA strategies have been used to identify synthesis activity and to compare two biological conditions in various biological model organisms. In combination with instrument development, improved sample preparation and fractionation strategies, MS-based AHA strategies have the potential for broad application, and the methods should translate into clinical use. 相似文献
The ability of noble metal‐based nanoparticles (NPs) (Au, Ag) to drastically enhance Raman scattering from molecules placed near metal surface, termed as surface‐enhanced Raman scattering (SERS), is widely used for identification of trace amounts of biological materials in biomedical, food safety and security applications. However, conventional NPs synthesized by colloidal chemistry are typically contaminated by nonbiocompatible by‐products (surfactants, anions), which can have negative impacts on many live objects under examination (cells, bacteria) and thus decrease the precision of bioidentification. In this article, we explore novel ultrapure laser‐synthesized Au‐based nanomaterials, including Au NPs and AuSi hybrid nanostructures, as mobile SERS probes in tasks of bacteria detection. We show that these Au‐based nanomaterials can efficiently enhance Raman signals from model R6G molecules, while the enhancement factor depends on the content of Au in NP composition. Profiting from the observed enhancement and purity of laser‐synthesized nanomaterials, we demonstrate successful identification of 2 types of bacteria (Listeria innocua and Escherichia coli). The obtained results promise less disturbing studies of biological systems based on good biocompatibility of contamination‐free laser‐synthesized nanomaterials.
Isolated axes of Zea mays L. cvs CiV2 and CUZCO were imbibed for different periods of time, and free polysomes were extracted and analysed by centrifugation in a sucrose gradient. The amount of rRNA per axis was determined at different moments of germination. Polysome reassembly was practically completed by 8 h and 54% of the preformed ribosomes were found in the polysome fraction. An increase in the proportion of large polysomes was also observed during this period of germination. During the following period, the polysome content and the distribution of the various classes of polysomes remained unchanged. The time of appearance of newly synthesized ribosomes into the polysomes was investigated using axes germinated in the presence of [3H]-uridine. Centrifugal analysis of EDTA-dissociated polysomes and gel electrophoretic analysis of polysomal RNA showed that new ribosomes appeared into polysomes a few hours after completion of the initial polysome assembly. When released into the cytoplasm, the new ribosomes were preferentially incorporated into polysomes rather than stored as free ribosomes. 相似文献
Limited digestion of fructose 1,6-bisphosphatase with subtilisin produces an S-peptide with an about 60-residue peptide fragment that is non-covalently associated with the enzyme. The 60-residue peptide fragment con-sists of the most part of allosteric site for AMP binding. It could be separated from S-protein by gel filtration with a Sephadex G-75 column equilibrated with 9% formic acid. According to X-ray diffraction results the S-peptide consists of two α-helices without β-strand and the α-helix content is about 60% in the 60-residue-peptide fragment. When the enzyme is subjected to limited proteolysis with subtilisin, the secondary structure of the enzyme does not show a de-tectable change in CD spectrum. The CD spectra of the isolated S-peptide were measured under different concentra-tions. In the absence of GuHCl, S-peptide had 30% a-helix and 38.5% turn-like structure but had no β-strand, sug-gesting that the N-terminal 60-residue fragment, which is synthesized initially by ribosome, would fo 相似文献