Activation of wheat chloroplast sedoheptulose bisphosphatase: a continuous spectrophotometric assay

A new continuous spectrophotometric assay for sedoheptulose 1,7-bisphosphatase, applied to studies of the activation and steady-state kinetics of the wheat enzyme, is described. The assay enzyme sequence couples the formation of sedoheptulose 7-phosphate to the oxidation of NADH. The recycling of the reaction substrate enables measurements to be made at essentially constant substrate concentrations. Activation of wheat chloroplast sedoheptulose 1,7-bisphosphatase required a reducing agent and could be described by a first-order rate constant. The rate of activation was greatly increased in the presence of Mg²⁺ and sedoheptulose 1,7-bisphosphate. The K_m of the activated enzyme for sedoheptulose 1,7-bisphosphate. and its S_0.5 for Mg²⁺ were found to be 13.3 μm and 1.6 mm respectively. A high recovery method for purifying wheat chloroplast sedoheptulose 1,7-bisphosphatase is also detailed.     

Cell patterning in branched and unbranched fruiting bodies of the cellular slime mold Polysphondylium pallidum

Cell patterning, the percentage of spores and stalk cells, was measured in branched and unbranched asexual fruiting bodies of Polysphondylium pallidum. Unlike D. discoideum, where small and large fruiting bodies are more stalky than average-sized fruiting bodies, the overall cell patterning was the same in branched and unbranched fruiting bodies of all sizes in P. pallidum. Light greatly increased the numbers of fruiting bodies in P. pallidum per unit area (or decreased aggregation territory size) so that most fruiting bodies formed in the light were small and unbranched. By contrast, light had little effect on the cell patterning of P. pallidum, although there was a slight increase in the percentage of stalk cells in the light compared to the dark. This indicates that the mechanisms governing light sensitivity of aggregation territory size and cell patterning have different components in P. pallidum. The accuracy of cell patterning of individual branches of branched fruiting bodies was so imprecise as to leave doubt that patterning is occurring at the branch level. Individual whorls of branched fruiting bodies had a greater percentage spores (90%) than whole fruiting bodies (78%) and the cell patterning was relatively imprecise. Only in whole fruiting bodies was the spore:stalk ratio highly correlated. These findings are consistent with cell pattern determination operating at the whole aggregate level, rather than at the individual whorl or branch level in P. pallidum.     

寄主植物对棉铃虫越冬蛹抗寒能力的影响

通过对滞育蛹过冷却点的测定 ,初步明确寄主对棉铃虫Helicoverpaarmigera的越冬抗寒性有影响 ,幼虫取食棉花时产生的滞育蛹的过冷却点低于取食玉米的滞育蛹的过冷却点 ,即前者的抗寒能力高于后者 ;但用Bt棉喂养后的棉铃虫滞育蛹抗寒能力下降     

环磷酰胺辅助化疗对不同年龄乳腺癌患者卵巢功能的损伤情况及机制研究

目的:以月经变化情况及血清激素水平为观察指标,探讨环磷酰胺辅助化疗方案对绝经前不同年龄段乳腺癌患者卵巢功能的损伤情况及可能的机制研究.方法:收集2017年1月至2018年12月期间在我院接受环磷酰胺辅助化疗的绝经前乳腺癌患者77例.患者年龄范围为26-48岁,并按年龄分为两组:≤ 35岁组为16例;＞35岁组为61例....     

Deep body and surface temperature responses to hot and cold environments in the zebra finch

Global warming increasingly challenges thermoregulation in endothermic animals, particularly in hot and dry environments where low water availability and high temperature increase the risk of hyperthermia. In birds, un-feathered body parts such as the head and bill work as ‘thermal windows’, because heat flux is higher compared to more insulated body regions. We studied how such structures were used in different thermal environments, and if heat flux properties change with time in a given temperature. We acclimated zebra finches (Taeniopygia guttata) to two different ambient temperatures, ‘cold’ (5 °C) and ‘hot’ (35 °C), and measured the response in core body temperature using a thermometer, and head surface temperature using thermal imaging. Birds in the hot treatment had 10.3 °C higher head temperature than those in the cold treatment. Thermal acclimation also resulted in heat storage in the hot group: core body temperature was 1.1 °C higher in the 35 °C group compared to the 5 °C group. Hence, the thermal gradient from core to shell was 9.03 °C smaller in the hot treatment. Dry heat transfer rate from the head was significantly lower in the hot compared to the cold treatment after four weeks of thermal acclimation. This reflects constraints on changes to peripheral circulation and maximum body temperature. Heat dissipation capacity from the head region increased with acclimation time in the hot treatment, perhaps because angiogenesis was required to reach peak heat transfer rate. We have shown that zebra finches meet high environmental temperature by heat storage, which saves water and energy, and by peripheral vasodilation in the head, which facilitates dry heat loss. These responses will not exclude the need for evaporative cooling, but will lessen the amount of energy expend on body temperature reduction in hot environments.     

NH4 : NO3 nutrition influence on biomass productivity and root respiration of poplar and willow clones

Nitrogen fertilization often improves the yield of intensively managed, short‐rotation coppices. However, information of N nutrition form on the growth of common species and clones used for biomass production is limited. Thus, this study aims at evaluating N form effects on the growth of two Salicaceae clones. Cuttings of the poplar clone Max 4 (Populus maximovizcii × P. nigra) and the willow clone Inger (Salix triandra × S. viminialis) were fertilized in a pot experiment with four ratios of nitrate (NO₃^?) to ammonium (50%, 62.5%, 75% and 87.5% NO₃^? balanced with ammonium (NH₄⁺) to constant total N) for one growing season and under stable soil pH. Plants were harvested for analysis of biomass and morphology of leaves, stem and roots. Respiration of fine and coarse roots (RR) was determined and related to biomass growth. Salix cv. Inger accumulated more total dry matter than Populus cv. Max 4. In both Salicaceae clones, the total biomass was significantly influenced by the nitrate ratio and greatest in plants fertilized with 50% NO₃^? of the total N supply. Both clones possess a different leaf and root morphology, but no significant influence of the NO₃^? ratio on the morphology was found. Fine RR rates differed significantly between clones, with significantly greater fine RR in Max 4; 87.5% NO₃^? fertilization increased the fine RR. Fine RR and total accumulated plant biomass were closely related. Our study is the first to show the tremendous influence of fine root respiration, especially including the carbon‐intensive reduction of NO₃^? to NH₄⁺, on the aboveground growth of Salicaceae clones. Ways to improve yield in SRC are thus to lower the assimilate consumption by fine roots and to match fertilization regimes to the used clones or vice versa.     

Pear scab resistance QTLs via a European pear (Pyrus communis) linkage map

Pear scab caused by Venturia pyrina is an economically important disease throughout the world and can cause severe crop loss in susceptible cultivars. The varying range of susceptibility to pear scab in F1 populations has made it possible to identify quantitative trait loci (QTLs). Ninety-five seedlings derived from the cross ‘Abbè Fétel’ (AF) × ‘Max Red Bartlett’ (MRB) were evaluated for scab resistance in greenhouse tests, with 39% being classified as resistant, 33 as moderately susceptible and 28 as highly susceptible. Amplified fragment length polymorphisms (157) and simple sequence repeats (41) were used to construct two maps, one of 908.1 cM (AF) and the other of 879.8 cM (MRB). The analysis of the resistance data collected made it possible to identify two major QTLs on linkage groups 3 and 7 associated with resistance to V. pyrina. Both QTLs explained 88% of the phenotypic variance and the log of odds values were higher than 10, suggesting the involvement of two major genes in pear scab resistance. L. Pierantoni and L. Dondini have contributed equally to this work.     

An exact test for the association between the disease and alleles at highly polymorphic loci with particular interest in the haplotype analysis

The association analysis between the disease and genetic alleles is one of the simple methods for localizing the susceptibility locus in the genes. For revealing the association, several statistical tests have been proposed without discussing explicitly the alternative hypotheses. We therefore specify two types of alternative hypotheses (i.e., there is only one susceptibility allele in the locus, and there is an extension or shortening of alleles associated with the disease) and derive exact tests for the respective hypotheses. We also propose to combine these two tests when the prior knowledge is not sufficient enough to specify one of these two hypotheses. In particular, these ideas are extended to the haplotype analysis of three-way association between the disease and bivariate allele frequencies at two closely linked loci. As a by-product, a factorization of the probability distribution of the three-way cell frequencies under the null hypothesis of no three-way interaction is obtained.