高油玉米花粉直感效应与伴侣杂交种的选配研究

以20个优良的普通玉米杂交种为母本,以含油量不同的10个高油杂交种为父本,配制200个杂交当代组合,旨在通过分析杂交当代粒重和油分直感的表现,研究品质性状在杂交当代的表现规律,探讨高油玉米杂交种与普通玉米杂交种配套种植的最佳方式。结果表明,普通玉米杂交种与高油玉米杂交种杂交当代籽粒主要表现为:油分显著增加、百粒重增加不明显;父母本间在这2个性状上互作不显著,但农大62×187、农大62×931和沈单16×961等少数组合杂交当代百粒重有所增加。综合考虑油分、产量、父母本株高、开花期和生育期等性状后,筛选出了适合东北春玉米区和华北夏玉米区种植的不同伴侣杂交种组合,并对伴侣杂交种选育的一些原则进行了讨论。     

Structures of the bacterial ribosome in classical and hybrid states of tRNA binding

During protein synthesis, the ribosome controls the movement of tRNA and mRNA by means of large-scale structural rearrangements. We describe structures of the intact bacterial ribosome from Escherichia coli that reveal how the ribosome binds tRNA in two functionally distinct states, determined to a resolution of ~3.2 angstroms by means of x-ray crystallography. One state positions tRNA in the peptidyl-tRNA binding site. The second, a fully rotated state, is stabilized by ribosome recycling factor and binds tRNA in a highly bent conformation in a hybrid peptidyl/exit site. The structures help to explain how the ratchet-like motion of the two ribosomal subunits contributes to the mechanisms of translocation, termination, and ribosome recycling.     

双低杂交油菜与常规油菜主要经济性状分析

通过分析得到:杂交油菜平均产量极显著高于常规油菜平均产量。对杂交油菜产量贡献最大的为每角粒数(x11),其次为一次分枝结角数(x7),千粒重(x12)和二次分枝结角数(x8)对产量的贡献较小。对常规油菜产量贡献最大的为一次分枝结角数(x7),其次为每角粒数(x11),再次为千粒重(x12)和主轴角果数(x6),二次分枝结角数(x8)作用甚微。     

Hemoglobin switching in sheep and goats: occurrence of hemoglobins A and C in the same red cell

Sheep and goats switch from the synthesis of hemoglobin A (alpha(2)beta(2)(A)) to hemoglobin C (alpha(2)beta(2)(C)) when made anemic. We have demonstrated the existence of the asymmetrical hybrid hemoglobin, alpha(2)beta(A)beta(C), in the circulating red cells of anemic sheep. These erythroid cells, therefore, synthesized both A and C hemoglobin simultaneously. Thus, the switch appears to be mediated by selective gene expression rather than by a clonal or cellular selective mechanism.     

Lack of abnormal hemoglobins in Alaskan Eskimos,Indians, and Aleuts

In an examination of the blood of 708 Eskimos, 200 Aleuts, and 44 Indians in Alaska for abnormal types of hemoglobin, only normal hemoglobin A was detected. It may be concluded that abnormal hemoglobins in these races are rare if they occur at all.     

Globin composition and synthesis of hemoglobins in developing fetal mice erythroid cells

Fetal mouse erythropoiesis proceeds initially in yolk-sac blood islands (8 to 12 days) and, subsequently, in liver (12 to at least 16 days). Yolksac cells synthesize three hemoglobins, Hb E(I), Hb E(II) and Hb E(III). Hb E(I) has x- and y-globin chains; Hb E(II) has alpha and y; HB E(III), alpha and z. No detectable beta-globin is formed in these cells. Liver erythroid cells form only adult hemoglobin, composed of alpha- and beta-chains.     

The normal function of a speciation gene, Odysseus, and its hybrid sterility effect

To understand how postmating isolation is connected to the normal process of species divergence and why hybrid male sterility is often the first sign of speciation, we analyzed the Odysseus (OdsH) gene of hybrid male sterility in Drosophila. We carried out expression analysis, transgenic study, and gene knockout. The combined evidence suggests that the sterility phenotype represents a novel manifestation of the gene function rather than the reduction or loss of the normal one. The gene knockout experiment identified the normal function of OdsH as a modest enhancement of sperm production in young males. The implication of a weak effect of OdsH on the normal phenotype but a strong influence on hybrid male sterility is discussed in light of Haldane's rule of postmating isolation.     

Defect in phosphorylation of insulin receptors in cells from an insulin-resistant patient with normal insulin binding

Mononuclear blood cells were obtained from a patient with type A insulin resistance. The cells showed a normal ability to bind iodine 125-labeled insulin. Analysis of solubilized insulin receptors from the patient's cells revealed a defect in insulin-stimulated tyrosine kinase activity, which is closely associated with the receptor itself. The enzyme failed to phosphorylate the insulin receptor and showed a markedly reduced ability to phosphorylate exogenously added substrates. It appears that receptors from this insulin-resistant patient have a defect distal to the insulin-binding site (the alpha subunit of the receptor). The defect could be located in the beta subunit, which has an adenosine triphosphate-binding site, or in another receptor component that transfers a signal of insulin binding into kinase activity. This dissociation between the normal binding and the defective protein kinase component of the insulin receptor represents the first biochemical defect of the receptor distal to ligand binding.     

超级杂交稻Ⅱ优明86高产高效栽培措施的优化模型

运用最优设计,对 优明86进行移栽叶龄、密度和施N量3项栽培措施研究,建立产量、净收入与3项栽培措施的回归模型.分析了栽培措施对产量、净收入的影响,结果表明,3项措施对产量、净收入均有影响.经微机模拟,筛选出高产高效的技术措施:5.43-5.52叶移栽,每公顷插秧22.70-23.73万丛,施纯N量150.8-153.8kg.     

Oxygen isotopes: experimental vapor fractionation and variations in tektites

High-temperature (about 2800 degrees C) vapor fractionation of a silicate glass that originally contained 82 percent by weight of SiO(2) resulted in a decrease of the silica content to 45 percent. Oxygen isotope analyses show that the O(18)/O(16) ratio increased from 13.80 per mil in the starting material to 14.47 and 15.03 per mil in the residuum. This suggests that bediasites, which also exhibit an increase in this ratio with decreasing content of silica, have been subjected to a process of vapor fractionation.     

Oxygen activation and reduction in respiration: involvement of redox-active tyrosine 244

Cytochrome oxidase activates and reduces O(2) to water to sustain respiration and uses the energy released to drive proton translocation and adenosine 5'-triphosphate synthesis. A key intermediate in this process, P, lies at the junction of the O(2)-reducing and proton-pumping functions. We used radioactive iodide labeling followed by peptide mapping to gain insight into the structure of P. We show that the cross-linked histidine 240-tyrosine 244 (His240-Tyr244) species is redox active in P formation, which establishes its structure as Fe(IV) = O/Cu(B)2+-H240-Y244. Thus, energy transfer from O2 to the protein moiety is used as a strategy to avoid toxic intermediates and to control energy utilization in subsequent proton-pumping events.     

肥力对冬小麦顺序和非顺序衰老茎同化物积累和转运的影响

【目的】研究在适肥和高肥水平下,顺序和非顺序衰老茎顶三叶和地上器官同化物积累及转运特性,为阐明小麦叶片非顺序衰老的生理生化机制提供理论指导。【方法】以生育后期(05-16)非顺序衰老发生率较高的小麦品种温麦19、豫麦19和兰考矮早8为材料,设高肥(尿素225kg/hm2,磷酸二氢铵337kg/hm2,春季追施尿素112kg/hm2)和适肥(尿素150kg/hm2,磷酸二氢铵225kg/hm2,春季追施尿素75kg/hm2)2个肥力水平,在小麦扬花期(04-22)、叶色倒置现象发生时期(05-16)和成熟期,分别采集参试小麦品种正置茎和倒置茎,测定2个肥力水平下顶三叶的绿叶面积及其叶片、叶鞘、地上营养器官、穗和籽粒的干质量,比较正置茎和倒置茎顶三叶各指标的差异。【结果】在适肥和高肥条件下,参试小麦品种正置茎绿叶面积均表现为旗叶倒二叶倒三叶,而倒置茎绿叶面积表现为倒二叶旗叶倒三叶。正置茎旗叶干物质积累量与倒二叶接近,均大于倒三叶;倒置茎倒二叶干物质积累量显著大于旗叶和倒三叶。正置茎和倒置茎顶三叶叶鞘干物质积累量均表现为旗叶叶鞘倒二叶叶鞘倒三叶叶鞘。正置茎地上营养器官花前同化物转运量、转运率和对籽粒的贡献率均大于倒置茎,而正置茎地上营养器官花后同化物转运量和对籽粒的贡献率均低于倒置茎。倒置茎籽粒千粒质量均显著高于正置茎。与适肥水平相比,高肥水平可以延缓叶片衰老,增加营养器官干物质积累量,减少营养器官花前同化物向籽粒的转运,提高千粒质量。【结论】在高肥和适肥条件下,参试小麦品种均有叶片非顺序衰老的发生,且生育后期小麦叶片的非顺序衰老有利于籽粒的充实。     

Nuclear Activation Analysis: Recent developments in the technique and its inherent attributes give promise of wide applicability

Nuclear activation analysis-whether with instrumental or radiochemical procedures, manual or automatic systems-seems destined for an important place in analytic chemistry. Experience will determine the best choice of activating particles and the best detectors, or it may even lead to the development of entirely new techniques. But it seems evident that nuclear activation analysis will increasingly satisfy the need for precise, sensitive, and rapid elementary analysis, and will do so at relatively low cost.