[Effects of kainic acid that damages the marginal division of rat striatum on hippocampal long-term potentiation].

OBJECTIVE: To investigate the relationship between the marginal division (MrD) of the striatum and other brain regions associated with learning and memory. METHODS: Long-term potentiation (LTP) was induced by high-frequency stimulation of the perforant path-dentate gyrus, and changes in hippocampal LTP after destruction of the marginal division with kainic acid were observed. RESULTS: High-frequency stimulation of the perforant path produced significant increases in the peak amplitudes of the population spike (PS) in normal rats and those receiving saline treatment. In rats with damaged MrD, the increase in PS and the excitatory postsynaptic potential were less obvious compared with normal or saline-treated rats, indicating that the LTP of the hippocampus was attenuated by damage of the MrD. CONCLUSION: Damage of the MrD impacts the LTP formation in the hippocampus.

[Effects of hypoxia on AChE and NADPH-d levels in the marginal division and learning and memory functions of rats].

OBJECTIVE: To observe the pathological changes and changes in acetylcholinesterase (AChE) and reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) levels in the marginal division (MrD) following hypoxia, and explore the relation of hypoxia to damages of learning and memory functions. METHODS: Hypoxia models were established in 40 SD rats by treatment with the mixture of 8% oxygen and 92% nitrogen 5 times daily for 5 consecutive days, and the sham-hypoxia group was constituted by 10 rats receiving normal oxygen supply in the same manner as above. Another 10 untreated rats were used as normal control. The rats completing the hypoxia induction procedures were subjected to Y-maze test before their brain sections, along with those of the rats in the other 2 groups, were prepared for HE staining and immunohistochemical staining. RESULTS: AChE immunohistochemical results of the normal control group revealed numerous AChE-positive fibers and some positive cells in the striatum where the MrD was more lightly stained than the other regions. In the rats with hypoxia, however, the MrD was more intensely stained in comparison with the control, but the stain in other regions of the striatum did not manifest any significant differences between the groups. The MrD of normal rats possessed more NADPH-d-positive cells, all spindle-shaped, than the other regions of the striatum, and hypoxia did not result in morphological changes of the cells but significant reduction of their quantity occurred. CONCLUSION: Hypoxia may cause reduction of the learning and memory functions of rats and gives rise to alterations of AChE and NADPH-d staining patterns in the MrD. The MrD is more vulnerable to hypoxia as evidenced by more obvious changes in AChE and NADPH-d staining in the MrD than in the other regions of the striatum, which may be associated with the impairment of the learning and memory functions by hypoxia.

Immunocytochemical study of the marginal division in human striatum.

OBJECTIVE: To demonstrate the existence of the marginal division in human stritum. METHODS: The cytoar-chitecture and distribution of the neurotransmitters in human fetal striatum were studied using Nissl staining and immuno-cytochemistry. RESULTS: In the sections with Nissl staining, a distinct fusiform cell zone was observed between the putamen and the globus pallidus of the human striatum. The long axes of these neurons in this region stretched dorsoventrally in parallel with the border between the putamen and the globus pallidus. Numerous L-ENK-, NT-, SOM-and SP-positive fibers and a few L-ENK-and NT-positive cells were found in the marginal division. CONCLUSION: For the first time we demonstrate that human also have the marginal division in the striatum which is similar to that of the mammals as the rats, cats and monkeys

[Characteristics of ammonium N and nitrate N accumulation in dryland soil in relation with wheat yield].

A total of eleven field trials in Yongshou, Shaanxi Province and seven in Luoyang, Henan Province were conducted with two treatments (without N as control and with 150 kg N x hm(-2) addition). The wheat biomass and seed yield were determined, and so were the nitrate and ammonium N concentrations in five layers (0-20, 20-40, 40-60, 60-80, 80-100 cm) at each trial site. Results showed that soil ammonium concentrations in the two provinces were very low while nitrate N concentrations were relatively high. Soil nitrate N occupied 91% of the total mineral N, and exhibited the same trend as the total mineral N in reflecting soil N supplying capacity. Without N application, the cumulative nitrate N amounts in the 0-40, 0-60, 0-80 and 0-100 cm layers in Yongshou were significantly correlated with wheat biomass and seed yield while no such correlation existed in Luoyang. With N addition, the relations of cumulative nitrate N of the different layers to wheat biomass and yield were greatly declined in Yongshou whereas those of Luoyang were changed to be negative. The yield increases were significantly correlated with the amount of nitrate N accumulated in the 0-80 and 0-100 cm layers of the two sites under N addition. Wheat mainly depended on nitrate N from the 0-20 cm layer at seedling stage, 0-40 cm at reviving, and 0-60 cm at elongation stages, and could utilize 0-100 cm nitrate N at maturity. After wheat harvest, the concentration of ammonium N was not significantly different from the initial value while that of nitrate N greatly decreased.

[Effects of soil moisture before sowing and nitrogen fertilization on winter wheat yield and water use on Weibei Plain of Loess Plateau].

A five-year site-specific experiment was carried out on the Weibei Plain of Loess Plateau in Shaanxi Province of northwestern China to study the effects of soil moisture regime before sowing (SMBS) and nitrogen fertilization on the grain yield and water use of winter wheat. On the basis of applying 100 kg x hm(-2) of P2O5, five nitrogen fertilization levels (0, 80, 160, 240, and 320 kg N x hm(-2)) were installed, and took the precipitation in the five years into consideration. In the study area, there was a linear correlation between the precipitation in summer (from July to September) and the SMBS, with an increment of 0.6 mm SMBS per 1 mm precipitation. For a stable or high wheat yield, the SMBS should be kept around 550 mm, and the precipitation in summer should be around 370-390 mm. In the years with adequate precipitation (> 386 mm) in summer, the SMBS in present winter wheat growth season less decreased by the increase of the nitrogen fertilization rate in previous growth season. However, in the years with less precipitation in summer (< 350 mm), the SMBS in present winter wheat growth season decreased significantly by 9-17 mm when the nitrogen fertilization rate in previous growth season was increased by each 100 kg N x hm(-2). In addition to SMBS, adequate precipitation in key growth stages was another important factor to ensure the wheat yield in dryland area because 1 mm SMBS could produce 10.6-11.4 kg x hm(-2) of wheat grain, and 1 mm precipitation occurred in the key growth stages could lead to more grain yield as high as 30.6-33.1 kg x hm(-2). Variation analysis showed that nitrogen fertilization rate affected the utilization degree of SMBS by winter wheat, while SMBS controlled the allocation and transportation of dry matter from vegetative parts to grain.

[Utilization rate of fertilizer N and dynamic changes of soil NO3(-)-N in summer maize field in semi-humid area of Northwest China].

A field experiment on manual loessial soil was conducted to study the dynamic changes of NO3(-)-N in soil profile, utilization rate of fertilizer N, and relationships between N application rate and soil residual N accumulation during the growth period of summer maize under different N application rates (0, 45, 90, 135, and 180 kg hm(-2)). The results showed that in the whole growth period of summer maize, the NO3(-)-N concentration in the soil profile was the highest in 0-20 cm layer, and increased with increasing N application rate. The NO3(-)-N concentration in 0-60 cm soil layer changed significantly, but no significant change was observed in 60-100 cm soil layer. In the growth season of summer maize, soil NO3(-)-N accumulation presented a fluctuated decreasing trend due to the N uptake by crop and the precipitation. The N utilization rate (NUR) increased with increasing N application rate when the application rate was less than 135 kg hm(-2), but tended to decrease when the application rate exceeded 135 kg hm(-2). With the increase of N application rate, the N agronomy efficiency (NAE) decreased but the N physiology efficiency (NPE) increased. There was a significant positive correlation between soil residual N accumulation and N application rate (R2 = 0.957**, n = 5). The grain yield under N application was significantly higher than that without N application (P <0.05), and there existed a significant positive correlation between grain yield and N application rate (R2 = 0.934**, n = 5). In our experiment, the optimal application rate of fertilizer N was 135 kg hm(-2), which could harmonize the relationship between economic benefits and environment.

[Relationships of microbial biomass carbon and nitrogen with particle composition and nitrogen mineralization potential in calcareous soil].

Taking 25 surface soil samples of calcareous soil with greater difference in fertility on Loess Plateau as test materials, this paper studied the relationships of soil microbial biomass carbon (B(C)) and nitrogen (B(N)) with soil nitrogen mineralization potential (N(0)), total nitrogen (TN), organic carbon (OC), and particle composition. The results showed that B(C) and B(N) had significant positive correlations with TN and OC, suggesting that B(C) and B(N) were highly related with soil fertility and could be used as biological indices of soil quality. B(C) and B(N) were highly correlated with N(0), with the correlation coefficient being 0.741 and 0.665, respectively (P < 0.01). B(C), B(N), TN, OC and N(0) all had significant positive correlations with physical clay (< 0.01 mm) but negative correlations with physical sand (> 0.01 mm), and had significant positive correlations with the ratio of physical clay to physical sand, indicating that soil organic matter was mainly combined with physical clay to form soil organic-mineral complexes.