Ca<Superscript>2+</Superscript> channel currents of cortical neurons from pure and mixed cultures

Voltage-gated Ca²⁺ channels (VGCCs) are key regulators of many neuronal functions, and involved in multiple central nervous system diseases. In the last 30 years, a large number of injury and disease models have been established based on cultured neurons. Culture with serum develops a mixture of neurons and glial cells, while culture without serum develops pure neurons. Both of these neuronal-culture methods are widely used. However, the properties of Ca²⁺ currents in neurons from these two cultures have not been compared. In this study, we cultured rat cortical neurons in serum-containing or -free medium and then recorded the Ca²⁺ channel currents using patch-clamp technique. Our results showed that there were significant differences in the amplitude and activation properties of whole-cell Ca²⁺ channel currents, and of non-L-type Ca²⁺ channel currents between the neurons from these two culture systems. Our data suggested that the difference of whole-cell Ca²⁺ currents may result from the differences in non-L-type currents. Understanding of these properties will considerably advance studies of VGCCs in neurons from pure or mixed culture.     

Ubiquitin-proteasome system components are upregulated during intestinal regeneration

The ubiquitin proteasome system (UPS) is the main proteolytic system of cells. Recent evidence suggests that the UPS plays a regulatory role in regeneration processes. Here, we explore the possibility that the UPS is involved during intestinal regeneration of the sea cucumber Holothuria glaberrima. These organisms can regenerate most of their digestive tract following a process of evisceration. Initially, we identified components of H. glaberrima UPS, including sequences for Rpn10, β3, and ubiquitin-RPL40. Predicted proteins from the mRNA sequences showed high degree of conservation that ranged from 60% (Rpn10) to 98% (Ub-RPL40). Microarrays and RT-PCR experiments showed that these genes were upregulated during intestinal regeneration. In addition, we demonstrated expression of alpha 20S proteasome subunits and ubiquitinated proteins during intestinal regeneration and detected them in the epithelium and connective tissue of the regenerating intestine. Finally, the intestinal regeneration was altered in animals treated with MG132, a proteasome inhibitor. These findings support our contention that proteasomes are playing an important role during intestinal regeneration.     

等渗Ca(NO3)2和NaCl胁迫对黄瓜幼苗生长及渗透调节物质含量的影响

采用营养液培养方法,以耐盐性较弱的‘津春2号’黄瓜品种为试材,研究了等渗Ca(NO3)2和NaCl胁迫对黄瓜幼苗生长、根系电解质渗透率、根系活力、Na+和K+含量及渗透调节物质含量的影响。结果显示:(1)在84mmol.L-1 NaCl和56mmol.L-1 Ca(NO3)2等渗胁迫下,黄瓜幼苗鲜重和干重均显著下降,且NaCl处理下降的幅度大于等渗Ca(NO3)2处理。(2)NaCl主要通过对黄瓜根系的伤害来抑制植株生长,表现为根系活力下降、根系质膜透性增大、Na+大量积累、K+含量显著下降、Na+/K+明显上升,最终导致根冠比下降;而Ca(NO3)2处理对根系质膜透性、K+含量、Na+/K+的影响均小于NaCl胁迫,且根系活力和根冠比上升,但Ca(NO3)2胁迫后叶片含水量和渗透调节能力均小于NaCl胁迫。(3)NaCl胁迫条件下,黄瓜幼苗内渗透调节物质以可溶性糖为主,而Ca(NO3)2胁迫以可溶性蛋白为主。研究表明,NaCl胁迫对黄瓜幼苗的伤害大于等渗Ca(NO3)2,NaCl主要通过破坏根系质膜结构影响植株生长,而Ca(NO3)2主要通过引起地上部生理干旱来影响植株生长。     

刺参“腐皮综合症”致病菌LNUB415的分离及防治的初步研究

从大连海域患“腐皮综合症”的养殖刺参肠道中分离纯化到1株优势细菌LNUB415,经人工回接感染试验确定其对刺参具有较强的致病性.经形态学、生理生化和16S rDNA序列分析,该菌被初步鉴定为蜡样芽胞杆菌(Bacillus cereus).从多种具有免疫增强作用的中草药中筛选到抑菌效果最好的黄连,可使刺参死亡率降低30％.     

低氧胁迫下黄瓜根系细胞壁结合态多胺氧化酶活性变化及测定方法的确立

提出了细胞壁上PAO检测方法,并对低氧胁迫下黄瓜根系细胞壁结合态PAO的灵敏性、pH值范围、底物依赖性以及取样部位进行了测定。结果表明,检测时取根中部或基部为好,提取液pH值为6．5,启动底物为Spm或Put Spd Spm。低氧处理后PAO活性一开始下降,在第3天时处于上升趋势,第8天达最大值,此后虽下降,但一直高于对照,与游离态PAO活性变化趋势一致,但活性要高10倍以上,表明PAO活性绝大部分定位于细胞壁上。     

土壤水分对温室春黄瓜苗期生长与生理特性的影响

以津优1号黄瓜为试验材料．研究了土壤不同水分含量对温室春黄瓜苗期生长与生理特性的影响。结果表明,在土壤水分为田间持水量90％时．黄瓜幼苗长势健壮,茎粗大,根系活力强,叶绿素含量和光合速率高．与其它处理差异显著,说明土壤含水量过高或过低均不利于培育黄瓜壮苗。株高和叶面积随土壤含水量的升高而增加;细胞汁液浓度随土壤含水量的升高而降低．且对植株水分状况反应十分敏感,可以用来作为判断植株水分盈亏状况的生理指标。     

Life-table study of Anagrus atomus, an egg parasitoid of the green leafhopper Empoasca decipiens, at four different temperatures

The objective of our study was to assess thepotential of the egg parasitoid Anagrusatomus L. (Hymenoptera: Mymaridae) for controlof the greenhouse leafhopper Empoascadecipiens Paoli (Homoptera: Cicadellidae). Theegg-adult development time, survivorship andreproduction of A. atomus were evaluatedat four constant temperatures (16, 20, 24 and28°C). Developmental time ranged from33.6 days at 16°C to 13.3 days at 28°C. Based on a linear regression ofdevelopment rate on temperature the lowerthreshold was estimated at 8.39°C. Anagrus atomus required 263.2 degree-days tocomplete its development from egg to adult. Theegg-adult survival rate and the sex ratio weresignificantly lower at 28°C than at theother three temperatures tested. The intrinsicrate of increase (r _m) variedsignificantly between all four temperatures.The potential of A. atomus to attackdifferent host ages was additionallyinvestigated. Host eggs were parasitizedthroughout their development but rate ofparasitism was reduced in host eggs older thansix days. The number of eggs parasitized waspositively density dependent but the rate ofparasitism decreased with increasing hostdensity. A maximum rate of parasitism of 62.5%was recorded. The potential impact of the eggparasitoid on the population dynamics of E. decipiens is discussed.     

黄瓜花粉母细胞减数分裂及其雄配子体发育的细胞学研究

以南方型和北方型两个生态型黄瓜为材料,用改良的染色和制片方法,较为系统的研究了黄瓜花粉母细胞(PMC)减数分裂及其雄配子体的发育过程。结果表明：①黄瓜减数分裂属于同时型胞质分裂,双线期染色体具有明显的交叉节并呈现出较易识别的棒状或环状形态,在末期Ⅰ和末期Ⅱ有多核仁和核仁融合现象;②在四分体时期的小孢子成十字交叉形(decussate type),而非四边形(isobilateral type);③雄配子体发育过程中观察到两核居中期的特殊现象,在核居中期小孢子只有一层壁,而在核靠边期小孢子出现了两层壁;④黄瓜的成熟花粉粒属于两核花粉粒。     

Quantal Characteristics of Synaptic GABA Release under Conditions of Stimulation of Single Synaptic Terminals of Cultured Cortical Cells of the Rat

We studied evoked inhibitory postsynaptic currents (eIPSC) using local electrical stimulation of single presynaptic terminals of cultured rat neocortical neurons. According to pharmacological and kinetic properties, these currents were qualified as GABA_A-activated. Using autocorrelation analysis of distributions of the eIPSC amplitudes, which were in all cases polymodal, we examined quantal characteristics of the above eIPSC. These results were compared with the values of quantal parameters (N, p, Q, and m) of the current families obtained using approximation by binomial distribution. Amplitude histograms of spontaneous miniature IPSC recorded under conditions of the minimum quantal release of the neurotransmitter were normal (close to Gaussian) with the mode within a 10 pA range, which is very close to analogous parameters calculated using autocorrelation and binomial techniques.