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101.
102.
Li-Jun Yan Zhi-Guo Zhu Pei Wang Chao-Nan Fu Xi-Jin Guan Philip Kear Chun-Zhi Zhang Guang-Tao Zhu 《植物分类学报:英文版》2023,61(4):599-612
Common potato (Solanum tuberosum L.) and its wild relatives belong to Solanum section Petota. This section's phylogeny and species delimitation are complicated due to various ploidy levels, high heterozygosity, and frequent interspecific hybridization. Compared to the nuclear genome, the plastid genome is more conserved, has a haploid nature, and has a lower nucleotide substitution rate, providing informative alternative insights into the phylogenetic study of section Petota. Here, we analyzed 343 potato plastid genomes from 53 wild and four cultivated species. The diversity of sequences and genomes was comprehensively analyzed. A total of 24 species were placed in a phylogenetic tree based on genomic data for the first time. Overall, our results not only confirmed most existing clades and species boundaries inferred by nuclear evidence but also provided some distinctive species clade belonging and the maternally inherited evidence supporting the hybrid origin of some species. Furthermore, the divergence times between the major potato clades were estimated. In addition, the species discriminatory power of universal barcodes, nuclear ribosomal DNA, and whole and partial plastid genomes and their combinations were thoroughly evaluated; the plastid genome performed best but had limited discriminatory power for all survey species (40%). Overall, our study provided not only new insights into phylogeny and DNA barcoding of potato but also provided valuable genetic data resources for further systematical research of Petota. 相似文献
103.
The food intake, growth, food conversion ratio and survival of yearling pufferfish, Fugu obscurus Abe, were investigated under different water salinity conditions over a 54‐day period. Within the salinity regimes of 0 (freshwater), 8, 18, and 35‰, the food intake levels were 0.97%, 1.43%, 1.19% and 1.01%, respectively; food conversion ratios were 1.31, 1.93, 1.61 and 1.36, respectively; and specific growth rates were 0.41%, 1.15%, 0.84%, and 0.35%, respectively. The three data series were reduced with increasing salinity. However, the survival rates did not show the same tendencies, which were 80%, 100%, 100%, and 67%, respectively. There were significant differences among the treatments. In conclusion, the yearling pufferfish optimum culture salinity condition was about 8‰. 相似文献
104.
Zlatka Kostova Benjamin C Yan Saulius Vainauskas Roberta Schwartz Anant K Menon Peter Orlean 《European journal of biochemistry》2003,270(22):4507-4514
Saccharomyces cerevisiae Gpi3p is the UDP-GlcNAc-binding and presumed catalytic subunit of the enzyme that forms GlcNAc-phosphatidylinositol in glycosylphosphatidylinositol biosynthesis. It is an essential protein with an EX7E motif that is conserved in four families of retaining glycosyltransferases. All Gpi3ps contain a cysteine residue four residues C-terminal to EX7E. To test their importance for Gpi3p function in vivo, Glu289 and 297 in the EX7E motif of S. cerevisiae Gpi3p, as well as Cys301, were altered by site-specific mutagenesis, and the mutant proteins tested for their ability to complement nonviable GPI3-deleted haploids. Gpi3p-C301A supported growth but membranes from C301A-expressing cells had low in vitro N-acetylglucosaminylphosphatidylinositol (GlcNAc-PI) synthetic activity. Haploids harboring Gpi3p-E289A proved viable, although slow growing but Gpi3-E297A did not support growth. The E289D and E297D mutants both supported growth at 25 degrees C, but, whereas the E289D strain grew at 37 degrees C, the E297D mutant did not. Membranes from E289D mutants had severely reduced in vitro GlcNAc-PI synthetic activity and E297D membranes had none. The mutation of the first Glu in the EX7E motif of Schizosaccharomyces pombe Gpi3p (Glu277) to Asp complemented the lethal null mutation in gpi3+ and supported growth at 37 degrees C, but the E285D mutant was nonviable. Our results suggest that the second Glu residue of the EX7E motif in Gpi3p is of greater importance than the first for function in vivo. Further, our findings do not support previous suggestions that the first Glu of an EX7E protein is the nucleophile and that Cys301 has an important role in UDP-GlcNAc binding by Gpi3ps. 相似文献
105.
Yan B. Linhart 《Evolution; international journal of organic evolution》1988,42(5):1047-1064
The roles of intraspecific and interspecific competition in producing differentiation within populations of Veronica peregrina were studied in two populations under controlled, greenhouse conditions. In nature, each population spans an environmental gradient across the center and sides of a temporary, vernal pool in California. Individuals at the center are subjected to intense intraspecific competition produced by high densities (to 30 seedlings/cm2) generated by quasi-simultaneous germination (90% of seeds germinate in one week). Individuals at the periphery are subjected to interspecific competition with grasses, which shade out the Veronica 4–6 weeks after the onset of winter growth. I predicted that 1) when grown under immediate intraspecific competition in the greenhouse, offspring of plants from the central subpopulation (C) would perform better (i.e., grow larger and produce more seeds) than those from the periphery (P) and that 2) when grown under delayed interspecific competition provided by Agrostis tenuis and Lollium multiflorum, offspring of plants from the periphery would perform better than those from the center. Both predictions were confirmed. The center-periphery differences were pronounced and statistically significant in an undisturbed population (V-2), while in a population disturbed by yearly plowing (V-3), the differences tended to be consistent with those in V-2 but seldom significant. Distribution of variability tended to be positively skewed and/or leptokurtic in subpopulations grown under “foreign” competition (i.e., intraspecific for P plants and interspecific for C plants) but was normally distributed following exposure to “familiar” competition. Timing of competition affected many results. There were four additional significant differences between the central and peripheral subpopulations. 1) Germination rate: the faster rate in central plants can be advantageous under immediate intraspecific competition. The slower rate in peripheral plants can be advantageous under conditions of erratic and unpredictable soil moisture. 2) Response to nutrient competition: central plants were more sensitive to N-deficiency and peripheral plants were more sensitive to P-deficiency. 3) Allocation of biomass: central plants allocated a greater proportion of biomass to seeds, while peripheral plants allocated a greater proportion of biomass to leaves under all growing conditions. 4) Root elongation: at the seedling stage, central plants have longer roots, while at the adult stage, peripheral plants have longer roots (but not more root mass). Most components of this complex pattern of differentiation are interpretable in an adaptive context. Other results defy simple explanations and underline the importance of phenotypic plasticity, which was pronounced in the competition experiments. 相似文献
106.
Yan, Sheng, Pawel Sliwinski, and Peter T. Macklem.Association of chest wall motion and tidal volume responses during CO2 rebreathing.J. Appl. Physiol. 81(4):1528-1534, 1996.The purpose of this study is to investigate theeffect of chest wall configuration at end expiration on tidal volume(VT) response duringCO2 rebreathing. In a group of 11 healthy male subjects, the changes in end-expiratory andend-inspiratory volume of the rib cage (Vrc,E andVrc,I, respectively) and abdomen (Vab,E and Vab,I, respectively) measured by linearizedmagnetometers were expressed as a function of end-tidalPCO2(PETCO2). The changes inend-expiratory and end-inspiratory volumes of the chest wall(Vcw,E and Vcw,I,respectively) were calculated as the sum of the respectiverib cage and abdominal volumes. The magnetometer coils were placed atthe level of the nipples and 1-2 cm above the umbilicus andcalibrated during quiet breathing against theVT measured from apneumotachograph. TheVrc,E/PETCO2 slope was quite variable among subjects. It was significantly positive (P < 0.05) in fivesubjects, significantly negative in four subjects(P < 0.05), and not different fromzero in the remaining two subjects. TheVab,E/PETCO2slope was significantly negative in all subjects(P < 0.05) with a much smallerintersubject variation, probably suggesting a relatively more uniformrecruitment of abdominal expiratory muscles and a variable recruitmentof rib cage muscles during CO2rebreathing in different subjects. As a group, the meanVrc,E/PETCO2,Vab,E/PETCO2, andVcw,E/PETCO2slopes were 0.010 ± 0.034, 0.030 ± 0.007, and0.020 ± 0.032 l / Torr, respectively;only theVab,E/PETCO2 slope was significantly different from zero. More interestingly, theindividualVT/PETCO2slope was negatively associated with theVrc,E/PETCO2(r = 0.68,P = 0.021) and Vcw,E/PETCO2slopes (r = 0.63,P = 0.037) but was not associated withtheVab,E/PETCO2slope (r = 0.40, P = 0.223). There was no correlation oftheVrc,E/PETCO2 andVcw,E/PETCO2slopes with age, body size, forced expiratory volume in 1 s, orexpiratory time. The groupVab,I/PETCO2 slope (0.004 ± 0.014 l / Torr) was not significantlydifferent from zero despite theVT nearly being tripled at theend of CO2 rebreathing. Inconclusion, the individual VTresponse to CO2, althoughindependent of Vab,E, is a function ofVrc,E to the extent that as theVrc,E/PETCO2slope increases (more positive) among subjects, theVT response toCO2 decreases. These results maybe explained on the basis of the respiratory muscle actions andinteractions on the rib cage. 相似文献
107.
Ectopic ion channels developed locally at the injury site after nerve damage by light ligation around common sciatic nerve of the rats. Different channel types have different processes of formation, accumulation and degeneration. During the first three days after injury, mechanically activated channels that are modulated by Ca++ channel activities first appeared. As the nerve fibers begin to be excited by TEA, a blocker of K+ channels, suggesting that the accumulation of K+ channels, the responsibility of mechanically activated channels was declining. Onset of K+ channels was from the 3rd postoperative day and lasted up to the fiftieth day. This time course of K+ channel development was closely related to allodynia and hyperalgesia of neuropathic animal behaviour. The results suggest that chronic contraction injury induces a dynamic change in the ectopic mechanically activated channels and K+ channels at the injury site of nerve and there is an interchange in the development time courses of the mechanic 相似文献
108.
Mei-Ling Siu-Caldera Jeffrey W. Clark Anabela Santos-Moore Sara Peleg Yan Yun Liu Milan R. Uskokovi Surendra Sharma G. Satyanarayana Reddy 《The Journal of steroid biochemistry and molecular biology》1996,59(5-6)
1α,25(OH)2-16-ene-D3, a synthetic analog of the steroid hormone, 1α,25(OH)2D3, has great potential to become a drug in the treatment of leukemia and other proliferative disorders, because of its minimal in vivo calcemic activity associated with a potent inhibitory effect on cell growth. However, at present, the mechanisms through which 1α,25(OH)2-16-ene-D3 expresses its biological activities are still not completely understood. Our previous in vitro study in a perfused rat kidney indicated for the first time that 1α,25(OH)2-16-ene-D3 and 1α,25(OH)2D3 are metabolized differently. 1α,25(OH)2-24-oxo-16-ene-D3, an intermediary metabolite of 1α,25(OH)2-16-ene-D3 formed through the C-24 oxidation pathway, accumulated significantly in the perfusate when compared to 1α,25(OH)2-24-oxo-D3, the corresponding intermediary metabolite of 1α,25(OH)2D3. In a subsequent in vivo study, we also reported that 1α,25(OH)2-24-oxo-16-ene-D3 exerted immunosuppressive activity equal to its parent, without causing significant hypercalcemia. In order to establish further the critical role of 1α,25(OH)2-24-oxo-16-ene-D3, in generating some of the key biological activities ascribed to its parent, we performed the present in vitro study using a human myeloid leukemic cell line (RWLeu-4) as a model. Comparative target tissue metabolism studies indicated that 1α,25(OH)2-16-ene-D3 and 1α,25(OH)2D3 are metabolized differently in RWLeu-4 cells, and the differences were similar to the ones we previously observed in the rat kidney. The significant finding was the accumulation of 1α,25(OH)2-24-oxo-16-ene-D3 in RWLeu-4 cells because of its resistance to further metabolism. Biological activity studies indicated that both 1α,25(OH)2-16-ene-D3 and its 24-oxo metabolite produced growth inhibition and promoted differentiation of RWLeu-4 cells to the same extent, and these activities were several fold higher than those exerted by 1α,25(OH)2D3. In addition, the genomic action of each vitamin D compound was assessed in a rat osteosarcoma cell line (ROS 17/2.8) by measuring its ability to transactivate a gene construct containing the vitamin D response element of the osteocalcin gene linked to the growth hormone reporter gene. In these studies, both 1α,25(OH)2-16-ene-D3 and its 24-oxo metabolite exerted similar but potent transactivation activity which was several fold greater than that exerted by 1α,25(OH)2D3 itself. In summary, our results indicate that the production and slow clearance of the bioactive intermediary metabolite, 1α,25(OH)2-24-oxo-16-ene-D3, in RWLeu-4 cells contributes significantly to the final expression of the enhanced biological activities ascribed to its parent analog, 1α,25(OH)2-16-ene-D3. 相似文献
109.
微生物产生的木聚糖酶的功能和应用 总被引:19,自引:0,他引:19
术聚糖是一种异质多糖,主要由木糖和阿拉伯糖组成。微生物产生的木聚糖酶来源广泛,能将木聚糖水解为木寡糖和D-木糖。该酶具有极大的应用价值,如可用于纸浆的漂白以减少环境污染,也可将造纸工业及农业废料中的木聚糖转化为D-木糖。 相似文献
110.