Non‐symbiotic nitrogen fixation during leaf litter decomposition in an old‐growth temperate rain forest of Chiloé Island,southern Chile: Effects of single versus mixed species litter

Heterotrophic nitrogen fixation is a key ecosystem process in unpolluted, temperate old‐growth forests of southern South America as a source of new nitrogen to ecosystems. Decomposing leaf litter is an energy‐rich substrate that favours the occurrence of this energy demanding process. Following the niche ‘complementarity hypothesis’, we expected that decomposing leaf litter of a single tree species would support lower rates of non‐symbiotic N fixation than mixed species litter taken from the forest floor. To test this hypothesis we measured acetylene reduction activity in the decomposing monospecific litter of three evergreen tree species (litter C/N ratios, 50–79) in an old‐growth rain forest of Chiloé Island, southern Chile. Results showed a significant effect of species and month (anova , Tukey's test, P < 0.05) on decomposition and acetylene reduction rates (ARR), and a species effect on C/N ratios and initial % N of decomposing leaf litter. The lowest litter quality was that of Nothofagus nitida (C/N ratio = 78.7, lignin % = 59.27 ± 4.09), which resulted in higher rates of acetylene reduction activity (mean = 34.09 ± SE = 10.34 nmol h^?1 g^?1) and a higher decomposition rate (k = 0.47) than Podocarpus nubigena (C/N = 54.4, lignin % = 40.31 ± 6.86, Mean ARR = 4.11 ± 0.71 nmol h^?1 g^?1, k = 0.29), and Drimys winteri (C/N = 50.6, lignin % = 45.49 ± 6.28, ARR = 10.2 ± 4.01 nmol h^?1 g^?1, k = 0.29), and mixed species litter (C/N = 60.7, ARR = 8.89 ± 2.13 nmol h^?1g^?1). We interpret these results as follows: in N‐poor litter and high lignin content of leaves (e.g. N. nitida) free‐living N fixers would be at competitive advantage over non‐fixers, thereby becoming more active. Lower ARR in mixed litter can be a consequence of a lower litter C/N ratio compared with single species litter. We also found a strong coupling between in situ acetylene reduction and net N mineralization in surface soils, suggesting that as soon N is fixed by diazotroph bacteria it may be immediately incorporated into mineral soil by N mineralizers, thus reducing N immobilization.     

大鼠胰腺发育过程中AFP动态表达的意义

目的:探索大鼠胰腺发育过程中AFP动态表达的意义.方法:采用高密度寡核苷酸芯片对胚胎12.5天(E12.5)、E15.5、E18.5、初生和成年大鼠胰腺进行基因转录水平分析.结果:AFP显著高表达于E18.5大鼠胰腺,AFP在胚胎期的动态表达趋势与胰腺功能细胞标志物以及可能介导AFP促细胞增殖效应的有关信号系统成员的表达趋势一致.结论:AFP在大鼠胰腺发育过程中动态表达的生物学意义可能在于参与胰腺发育调控.     

Ecological, morphological and allozymic differentiation between diploid and tetraploid knapweeds (Centaurea jacea) from a contact zone in the Belgian Ardennes

In the northeastern part of Belgium, the Centaurea jacea complex shows extensive morphological variation and is represented by a diploid (2 n = 22) and a tetraploid (2 n = 44) cytotype. Polysomic inheritance of allozyme markers in the tetraploids, suggesting autopolyploidy, is here demonstrated for the first time. In order to test whether the two cytotypes occupy distinct habitats and possess different gene pools, patterns of allozymic and morphological variation were investigated in relation to ploidy level and site characteristics in 26 populations from the Belgian Ardennes. The two cytotypes showed a parapatric distribution, the diploids occurring at higher elevations (mostly above 500 m) than the tetraploids (mostly below 500 m). Three mixed populations were found near the contact zone of the two cytotypes. Within the mixed populations no triploid plant and no evidence for gene flow between cytotypes were found, despite widely overlapping flowering periods. The two cytotypes can be distinguished on the basis of morphological traits and enzymatic gene pools. The congruence of morphological and allozymic variation with chromosome numbers suggests a secondary contact between the two cytotypes with limited gene flow between them. The origin and persistence of the parapatric distribution are discussed.     

Cord blood–derived cytokine-induced killer cells combined with blinatumomab as a therapeutic strategy for CD19+ tumors

Background

Cytokine-induced killer cells (CIKs) are an advanced therapeutic medicinal product (ATMP) that has shown therapeutic activity in clinical trials but needs optimization. We developed a novel strategy using CIKs from banked cryopreserved cord blood units (CBUs) combined with bispecific antibody (BsAb) blinatumomab to treat CD19⁺ malignancies.

Localization of sources of thalamic inputs into the sensorimotor cortex in the rabbit using retrograde axonal transport technique

It was shown that the rabbit sensorimotor cortex received afferent fibers from neurons located in the specific, nonspecific, and association thalamic nuclei using the retrograde axonal transport technique. The distribution, dimensions, and shape of the somata of relay neurons spread through the thalamic nuclei were analyzed. The total number of neurons sending out thalamo-sensorimotor-cortical fibers was calculated and the coordinates of loci with the highest density of these cells in each thalamic nucleus were identified. Multipolar and stellate cells with somata measuring 12–20 µm and 10–15 µm in diameter, respectively, prevailed amongst relay neurons. Amongst the specific nuclei, the majority of afferent fibers are sent out by the ventrolateral, ventral anterior, and anterior ventral nuclei. A comparable number of afferent fibers are sent out by the mediodorsal and paracentral nuclei; these split up among the association nuclei and paracentral nuclei, respectively. It is suggested that afferents from many different groups of thalamic nuclei are essential for the sensorimotor cortex to participate in thalamocortical interaction.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 19, No. 1, pp. 87–94, January–February, 1987.     

Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+/K+ homeostasis

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na⁺] and [K⁺] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na⁺‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the cheesmaniae alleles) and 157‐17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K⁺] and the [Na⁺]/[K⁺] ratio in leaf and stem but not for [Na⁺] arising a disagreement with the corresponding RIL population. Their association with leaf [Na⁺] and salt tolerance in tomato is also discussed.