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21.
L.Charles Dickinson James C.W. Chien 《Biochemical and biophysical research communications》1973,51(3):587-592
Single crystals of horse CoHb were obtained by reduction of CoHb+ crystals with dithionite. Epr measurements showed that the g? and Coà tensors are both axial and share the same principal axis systems. Of the four subunits, the “heme” normals of C? and d? subunits ãb?plane 29 ± 1° from b?; they have the same orientation as the hemes in methemoglobin. The normals of “hemes” à and B? are 47 above the ãb? plane as compared to 16° in methemoglobin. 相似文献
22.
Larval tobacco hornworms,Manduca sexta (L.), of 2 different colonies were exposed to parasitism by the gregarious endoparasitoid,Cotesia congregata (Say). A comparison was made of parasitoid larval, pre-pupal, and pupal mortality, female and male dry weight and larval
development time. In general, “Maryland” hornworms were more suitable hosts than “North Carolina” hornworms. Although the
presence of dietary nicotine increased parasitoid mortality in individuals reared from hornworms of both colonies, the effect
was more severe among individuals parasitizing the North Carolina hornworms.
Scientific contribution No. 8125, article No. A-5066 of the Maryland Agricultural Experiment Station, Department of Entomology. 相似文献
23.
马桑菌株的生物学特性 总被引:3,自引:0,他引:3
对从湖北、四川、云南等地采集的尼泊尔马桑(Coriaria nepalensis Wall.)根瘤中分离的20株内生菌纯培养物所进行的研究表明,其形态均具有弗兰克氏菌属的特征。在粗细不一的分枝菌丝体上有泡囊和孢囊,有的还有串珠状结构的菌丝体。不同菌株在液体培养基上生长速度很不一致;菌丝体多呈絮状或颗粒状沉淀,个别还呈薄膜状沉淀;绝大多数菌株的菌丝体具有不同色调的色素;在S培养基中大多数都能产生可溶性色素。上述这些培养特征常因培养基成分和培养方式的不同而有差异。大多数菌株的胞壁组分属Ⅱ型,少数菌株为Ⅲ型;全细胞糖型变化很大,20个菌株可划分为6个糖型,而且绝大多数糖型与已知弗兰克氏菌有所不同。此外,有65%的菌株还具有明显的抗菌活性。 相似文献
24.
不同生境区稻田节肢动物群落相似性分析 总被引:1,自引:0,他引:1
根据不同生境区稻田节肢动物群落系统调查结果,应用组平均聚类分析法及主成分分析法,讨论节肢动物群落的相似(相异)性问题。结果表明:生境条件及管理措施的差异对群落的结构影响较为明显,不同生境区的稻田节肢动物群落,都能在一定距离取值时聚合成一类,而水稻品种对此影响较小。主成分分析结果由二维图表达已基本满足要求。结果说明大八镇生境区稻田节肢动物群落与岗列镇生境区稻田节肢动物群落差异较大,分别列于两个极端。海陵镇生境区稻田介于两者之间,而与岗列镇生境区稻田节肢动物群落重叠。与聚类分析结果有所差异。这可能与主成分分析法损失部分信息有关。 相似文献
25.
Eric Dufour Paul Robert Dominique Bertrand Tomasz Haertlé 《Journal of Protein Chemistry》1994,13(2):143-149
Fourier transform infrared spectroscopy has been applied to investigate the secondary structural changes of-lactoglobulin in water/ethanol mixtures. The studies were carried out at two differentpHs and at high protein concentrations. The spectra were recorded using an attenuated total reflection cell. The amide I band of-lactoglobulin in water reveals large amounts of intra extended-sheet structure. About 20% ethanol,-lactoglobulin unfolds and-strand formation is observed.-Helices are built up by increasing the ethanol concentration up to 30%. In 50% ethanol,-lactoglobulin gels providing the apparent pH are neutral. The secondary structural changes of-lactoglobulin were observed on the similarity maps obtained by Principal Component Analysis. 相似文献
26.
The invasion kinetics ofhobo transposable element in theDrosophila melanogaster genome was studied byin situ hybridization on the polytene chromosomes. Six independent lines ofDrosophila melanogaster flies that had been previously transformed by microinjection of the pHFL1 plasmid containing a completehobo element were followed over 50 generations. We observed thathobo elements were scattered on each of the chromosome arms, with more insertion sites on the 3R arm. The total number of insertion sites remains quite small, between four and six, at generation 52. On the 2R arm, a short inversion appeared once at generation 52. Most of the integration sites reported here were already described for several transposons but some of them appear to be hotspots forhobo elements. 相似文献
27.
Multivariate morphometrics and allometry in a polymorphic ant 总被引:1,自引:0,他引:1
28.
PrP accumulation in the brains of mice infected with scrapie takes several different forms: amyloid plaques, widespread accumulation
in neuropile, and perineuronal deposits. PrP is also sometimes detected within microglia and in or around astrocytes. There
are dramatic and reproducible differences between scrapie strains in the relative prominence of these changes and their distribution
in the brain. Depending on the scrapie strain, PrP pathology is targeted precisely to particular brain areas, often showing
a clear association with identifiable groups of neurons. These results suggest that PrP changes are primarily associated with
neurons, and that different scrapie strains recognize and selectively replicate in different populations of neurons. Immunostaining
at the ultrastructural level demonstrates an association of PrP with neurite plasmalemma, around amyloid plaques, and in areas
of widespread neuropile and perineuronal accumulation. It is probable that PrP is encoded by theSinc gene, which controls the incubation period of scrapie in mice. Studies using the intraocular infection route show that theSinc gene controls the onset rather than the rate of replication, suggesting that PrP may be involved in cell-to-cell spread of
infection. The accumulation of PrP at the surface of neurons is consistent with such a role. 相似文献
29.
Celery (Apium graveolens L. var Dulce) is a high value crop affected at different growth stages by a variety of nutrient disorders. Each nutrient concentration can be corrected for its dependence on concentrations of other nutrients by recognizing plant composition as a closed system whose components add up to one. New variables z
i are computed as logratioed values of individual nutrients, where each nutrient concentration is corrected for the geometric mean of all nutrient concentrations. The z
i are used together with principal component analysis (PCA) to relate celery composition to yield, deficiency symptoms and quality parameters. A survey of commercial celery fields suggested that (1) celery growth is most often limited by P and N deficiencies associated with Fe toxicity; (2) K uptake is most likely to become limiting when the crop reaches 15 cm in height; (3) blackheart incidence can be traced to low levels of K and Mg in external petioles, and (4) cracked stem incidence is related to low B when the crop is 30 cm in height. 相似文献
30.
Robert de Lorimier Sigurd M. Wilbanks Alexander N. Glazer 《Plant molecular biology》1993,21(2):225-237
R-phycocyanin II (RPCII) is a recently discovered member of the phycocyanin family of photosynthetic light-harvesting proteins. Genes encoding the and subunits of RPCII were cloned and sequenced from marine Synechococcus sp. strains WH8020 and WH8103. The deduced amino acid sequences of RPCII were compared to two other types of phycocyanin, C-phycocyanin (CPC) and phycoerythrocyanin (PEC). These three types vary in the composition of their covalently bound bilin prosthetic groups. In terms of amino acid sequence identity RPCII is highly homologous to CPC and PEC, suggesting that the known three-dimensional structures of the latter two are representative of RPCII. Thus the amino acid residues contacting the three bilins of RPCII could be inferred and compared to those in CPC and PEC. Certain residues were identified among the three phycocyanins as possibly correlating with specific bilin isomers. In overall sequence RPCII and CPC are more homologous to one another than either is to PEC. This probably reflects functional homology in the roles of RPCII and CPC in the transfer of light energy to the core of the phycobilisome, a function not attributed to PEC. The genomes of Synechococcus sp. strains WH8020, WH8103 and WH7803 share homologous open reading frames in the vicinity of RPCII genes. The nucleotide sequence extending 3 from RPCII genes in strain WH8020 revealed two open reading frames homologous to components of an CPC phycocyanobilin lyase. These open reading frames may encode a lyase specific for the attachment of phycoerythrobilin to RPCII. 相似文献