外显子与内含子序列分维的双碱基研究

引入碱基间的关联,研究了外显子和内含子序列以双碱基为单位的分维,我们发现在这种情况下,外显子和内显子序列在短程和中程存在自相似性并分别定义了这两个区域的分维。结果表明,短程的分维值Ｄｇ一般比中程的Ｄｍ大,外显子的两个分维值比内含子大。我们改变双联体的位相而分维却不变,这反映出在双联体基础上,外显子的不规则性大于内含子,短程的不规则性大于中程,外显子和内含子序列对以２为周期的结构没有位相的特异性。     

Embryogenesis and plant regeneration of spinach (Spinacia oleracea L.) from hypocotyl segments

A system for somatic embryogenesis and plant regeneration of spinach from hypocotyl segments has been established. Callus was induced on solid media supplemented with 8.5–15.0 mg.l⁻¹ of indole-3-acetic acid and 3.46–34.64 mg.l⁻¹ gibberellic acid. Callus was then subcultured on different media (solid or liquid) with or without IAA, or continuously maintained on the initiating media. Somatic embryos were obtained in subcultures on IAA-containing media as well as in long-term cultures on initiating media. The best results were achieved in liquid subcultures. About 60% of plantlets survived after transplanting in pots.     

Biochemical and Physiological Responses of Cucumis sativus Cultivars to Different Combinations of Low-Temperature and High Humidity

Low-temperature and high humidity are typical environmental factors in the plastic tunnel and solar greenhouse during the cold season that restricts plant growth and development. Herein, we investigated the impact of different combinations of low-temperature and high humidity (day/night: T1 15/10 °C?+?95%, T2 12/8 °C?+?95%, and T3 9/5 °C?+?95%) along with a control (CK 25/18 °C?+?80%) on cucumber cultivars viz: Zhongnong37 (ZN37: resistant) and Shuyanbailv (SYB: sensitive). The low-temperature and high humidity stresses increased electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and intercellular concentration of carbon dioxide (Ci), and reduced morphological indices, relative water content (RWC), net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (E) and leaf pigments in both cultivars as compared to control (CK). Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were decreased in cv. SYB under stress conditions as compared to cv. ZN37. Low-temperature and high humidity treatments showed an increase in proline and soluble protein content in cv. ZN37 as compared to cv. SYB. Abscisic acid (ABA) and jasmonic acid (JA) were augmented while indole-3-acetic acid (IAA), zeatin (ZT), zeatin riboside (ZR), and gibberellic acid (GA) were decreased in both cultivars. Under T3 (9/5 °C?+?95%), Pn, protoporphyrin, and ZT were extremely decreased by 71.3%, 74.3%, and 82.4%, respectively, in cv. SYB compared to control. Moreover, principal component analysis (PCA) based on physiochemical traits confirmed that cv. ZN37 had the strongest correlation with antioxidant enzymes, proline, and soluble protein content than cv. SYB under low-temperature and high humidity treatments. Our results suggest that a stress-tolerant cultivar mitigates stress damage in cucumber transplants by regulating photosynthetic efficiency, antioxidant capacity and hormonal profile when compared to a stress-sensitive cultivar.

     

Effects of Mechanized,Deep Application of Slow-Release Fertilizer on Yield and Nitrogen,Phosphorus, and Potassium Utilization of Direct-Seeded Rice

Compared with the standard method of manual fertilizer broadcasting (MFB), mechanized hill-drilling direct-seeding with deep application of slow-release nitrogen fertilizer (MHDDF) is an efficient method to integrate both fertilization and seeding. However, there are few studies that combine the use of slow-release fertilizer with MHDDF. We sought to explore the combined effect of MHDDF with slow-release fertilizer on rice yield and nitrogen, phosphorus, and potassium utilization, compared to MFB. We compared three different MHDDF methods (D30: 450 kg ha^?1, D40: 600 kg ha^?1, D50: 750 kg ha^?1), with one MFB method (B50: 750 kg ha^?1), and one control (CK: 0 kg ha^?1). We found that the yield of all MHDDF method was higher than that of both the MFB method. Yield was the highest in the D50 treatment and was 14.14–46.03% higher than that in B50 treatment. Biomass accumulation, nutrient accumulation, and nutrient use efficiency were similarly higher in MHDDF method than both MFB and CK. Compared to B50, the D50 treatment increased nitrogen recovery efficiency by 170.53–231.50%, phosphorus recovery efficiency by 480.00–724.25%, and potassium recovery efficiency by 201.55–169.59%. Overall, we found that combining MHDDF with slow-release fertilizer was an effective method to increase rice yield and nutrient use efficiency compared with MFB.

     

PDGF-AA activates AKT and ERK signaling for testicular interstitial Leydig cell growth via primary cilia

Testes control the development of male reproductive system. The testicular interstitial Leydig cells (Leydig cells) synthesize testosterone for promoting spermatogenesis and secondary sexual characteristics. Type A platelet-derived growth factor (PDGF-AA) is one of the most important growth factors in regulating Leydig cell growth and function. Knockout of PDGF-AA or its congenital receptor PDGFR-α leads to poor testicular development caused by reducing Leydig cell numbers, supporting PDGF-AA/PDGFR-α signaling regulates Leydig cell development. Primary cilium is a cellular antenna that functions as an integrative platform to transduce extracellular signaling for proper development and differentiation. Several receptors including PDGFR-α are observed on primary cilia for initiating signaling cascades in distinct cell types. Here we showed that PDGF-AA/PDGFR-α signaling promoted Leydig cells growth, migration, and invasion via primary cilia. Upon PDGF-AA treatment, AKT and ERK signaling were activated to regulate these cellular events. Interestingly, active AKT and ERK were detected around the base of primary cilia. Depletion of ciliary genes (IFT88 and CEP164) alleviated PDGF-AA-activated AKT and ERK, thus reducing Leydig cell growth, migration, and invasion. Thus, our study not only reveals the function of PDGF-AA/PDGFR-α signaling in maintaining testicular physiology but also uncovers the role of primary cilium and downstream signaling in regulating Leydig cell development.     

日本大萝卜引种栽培研究

本文报道日本大萝卜引种栽培的试验结果,并为推广这一蔬菜新品种提供了有效的栽培技术措施。     

儿童最大有氧活动能力的发展特征

本文报告了我国４６３名１０－１９岁儿童青少年的最大有氧活动能力的发展特征。在青春早期,男女童的最大吸氧量绝对值均随年龄增长而增加,男童由１．７５升／分增至３．１０升／分,女童由１．４４升／分增至２．０７升／分,女童增长较少;以后女童即稳定于这一水平,男童仍略有增长。按身高及按最大心率计标的相对值与其有相似的特征。按体重和瘦体重计算的相对值,在男女童都未见随年龄增长的规律。男童ＶＯ２ｍａｘ绝对值及各     

PHD2基因在鲸类低氧信号通路中的功能

为研究鲸类低氧适应的分子机制,文章克隆了不同低氧耐受能力的3个鲸类物种,抹香鲸(Physeter macrocephalus)、白鲸(Delphinapterus leucas)和长江江豚(Neophocaena phocaenoids asiaeorientalis)的脯氨酸羟化酶2(PHD2)。通过对其序列进行分析,发现3个物种PHD2的氨基酸序列非常保守。通过对这3个物种的PHD2的功能进行探究发现:3个物种的PHD2在常氧情况下均可以降解3个物种的HIF-α(包括HIF-1α和HIF-2α)蛋白,而在低氧(O₂浓度小于2%)情况下,PHD2则无法明显降解HIF-α蛋白。在常氧下,鲸类的PHD2降解HIF-α是依赖于识别鲸类的HIF-1α上LTLLAP和LEMLAP,HIF-2α的LAQLAP和LETLAP氨基酸片段,推测PHD2是通过对HIF-α序列中的脯氨酸位点进行羟基化修饰后,被VHL-E3泛素连接酶复合体所识别,发生泛素化降解。而在低氧条件下,PHD2的活性受到抑制HIF-α不能被VHL-E3泛素连接酶复合体识别,发生降解。研究对3种不同低氧耐受能力...     

有机框架材料在多肽富集的应用

生物医药领域近年来发展迅猛,多肽类药物因其生物学活性高、毒性小、生物相容性好等优势,在肿瘤治疗、细胞活性模拟、抗体检测等领域展开广泛应用,多肽的检测分析也成为研究的一大热点。传统的色谱法、溶剂沉淀法、离心超滤法和固相萃取法对多肽能够展现富集效果,但富集的效率往往不够理想。近年来,以有机框架材料为代表的纳米材料,在气体吸附、荧光、传感和催化等领域展开了广泛应用。有机框架材料凭借着独特的结构尺寸,成为了一类理想的生物吸附剂。由于其具有表面可修饰性,能够大大提高对多肽的富集效率。本文着重介绍近5年来金属-有机框架材料（metalorganic frameworks,MOFs）和共价-有机框架（covalent-organic frameworks,COFs）在多肽富集中的应用。