Seasonal Variations in Absorption and Metabolism of Carbon-14 Labelled Arginine in Intact Apple Stem Tissue

At intervals through the year a study was made of the absorption and metabolism of arginine-C 14(U) which had been perfused into the wood of apple stem internodes. Absorption was greater during the period May to September than at any other time of the year. The metabolic breakdown of arginine took place only after absorption but the products found varied widely with season. From the analyses it is concluded that arginine is metabolized by the Krebs-Henseleit cycle at all times of the year, in addition to which during the period from May to August there are other pathways in operation that result in a more extensive breakdown so that all the N in arginine becomes available for new growth.     

Characteristics of Nasal-Associated Lymphoid Tissue (NALT) and Nasal Absorption Capacity in Chicken

As the main mucosal immune inductive site of nasal cavity, nasal-associated lymphoid tissue (NALT) plays an important role in both antigen recognition and immune activation after intranasal immunization. However, the efficiency of intranasal vaccines is commonly restricted by the insufficient intake of antigen by the nasal mucosa, resulting from the nasal mucosal barrier and the nasal mucociliary clearance. The distribution of NALT and the characteristic of nasal cavity have already been described in humans and many laboratory rodents, while data about poultry are scarce. For this purpose, histological sections of the chicken nasal cavities were used to examine the anatomical structure and histological characteristics of nasal cavity. Besides, the absorptive capacity of chicken nasal mucosa was also studied using the materials with different particle size. Results showed that the NALT of chicken was located on the bottom of nasal septum and both sides of choanal cleft, which mainly consisted of second lymphoid follicle. A large number of lymphocytes were distributed under the mucosal epithelium of inferior nasal meatus. In addition, there were also diffuse lymphoid tissues located under the epithelium of the concha nasalis media and the walls of nasal cavity. The results of absorption experiment showed that the chicken nasal mucosa was capable to absorb trypan blue, OVA, and fluorescent latex particles. Inactivated avian influenza virus (IAIV) could be taken up by chicken nasal mucosa except for the stratified squamous epithelium sites located on the forepart of nasal cavity. The intake of IAIV by NALT was greater than that of the nasal mucosa covering on non-lymphoid tissue, which could be further enhanced after intranasal inoculation combined with sodium cholate or CpG DNA. The study on NALT and nasal absorptive capacity will be benefit for further understanding of immune mechanisms after nasal vaccination and development of nasal vaccines for poultry.     

A Technique for Studying the Adsorption, Absorption and Metabolism of Amino Acids in Intact Apple Stem Tissue

Solutions of amino acids are introduced rapidly into the xylem of short lengths of stem. At sampling the intact stem is first perfused with a salt solution to remove the amino acids still reversibly adsorbed by cation exchange. This fraction of the applied amino acids is thus distinguished from that absorbed into the tissues which is subsequently extracted from the disintegrated stem by aqueous ethanol. The potential value of this technique is discussed and illustrated with some results using carbon-14 labelled amino acids in apple stems.     

SO(2) Effect on Photosynthetic Activities of Intact Sugar Maple Leaves as Detected by Photoacoustic Spectroscopy

Short-term (4 hours) effect of different concentrations of SO₂ fumigation on in vivo photochemical activities of sugar maple (Acer saccharum Marsh.) leaves was investigated using photoacoustic spectroscopy. The relative quantum yield of O₂ evolution (ratio of O₂ signal to the photothermal signal) and photochemical energy storage are increased by 0.05 microliter per liter of SO₂. This increase is more pronounced in 5 to 7 year old saplings than in 3 month old seedlings. Both oxygen-relative quantum yield and energy storage of seedlings are inhibited by increased concentrations of SO₂ and the inhibition is concentration dependent. The inhibition is greater in seedlings than in saplings at 2 microliters per liter of SO₂, indicating the more susceptible nature of seedlings. The present study indicates a concentration dependent differential effect of SO₂ on photochemical activities of sugar maple leaves.     

Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRAS) of fibrinogen adsorbed on metal and metal oxide surfaces

We have investigated the possibilities of using Infrared Reflection Absorption Spectroscopy in the study of the interaction of proteins with metal surfaces. Structural information can be obtained since the infrared radiation at the metal surface interacts only with dipole transition moments perpendicular to the metal surface. Fibrinogen spontaneously adsorbed from solution onto gold, titanium and aluminum was used as model systems. The infrared studies were carried out on dried protein films. The amide I bands of fibrinogen adsorbed on the metal surfaces shift towards higher frequencies (ca. 20 cm-1) relative to the same band in buffer solution. The magnitude of these shifts indicates that conformational change of the protein occurs upon adsorption on metal surfaces. The change in conformation of the fibrinogen also can partly be due to one week of drying at room temperature. The amide I and amide II bands show a slightly different behaviour in terms of frequency and intensity for each metal-protein system studied. The side chains appeared to be more substrate sensitive than the peptide group. Orientational effects were observed for a number of side-chain related groups.     

Deconvoluting Protein (Un)folding Structural Ensembles Using X-Ray Scattering,Nuclear Magnetic Resonance Spectroscopy and Molecular Dynamics Simulation

The folding and unfolding of protein domains is an apparently cooperative process, but transient intermediates have been detected in some cases. Such (un)folding intermediates are challenging to investigate structurally as they are typically not long-lived and their role in the (un)folding reaction has often been questioned. One of the most well studied (un)folding pathways is that of Drosophila melanogaster Engrailed homeodomain (EnHD): this 61-residue protein forms a three helix bundle in the native state and folds via a helical intermediate. Here we used molecular dynamics simulations to derive sample conformations of EnHD in the native, intermediate, and unfolded states and selected the relevant structural clusters by comparing to small/wide angle X-ray scattering data at four different temperatures. The results are corroborated using residual dipolar couplings determined by NMR spectroscopy. Our results agree well with the previously proposed (un)folding pathway. However, they also suggest that the fully unfolded state is present at a low fraction throughout the investigated temperature interval, and that the (un)folding intermediate is highly populated at the thermal midpoint in line with the view that this intermediate can be regarded to be the denatured state under physiological conditions. Further, the combination of ensemble structural techniques with MD allows for determination of structures and populations of multiple interconverting structures in solution.     

Plasma and Tissue Levels of Trimethoprim in The Rainbow Trout,Salmo Gairdneri,After Absorption From Fresh and Salt Water

This is a comparative study of uptake of trimethoprim from 1) fresh water, 2) salt water after 7 days of adaption and 3) salt water without previous adaptation. The rate and extent of absorption were found to vary significantly. The salt water adapted group reached a plasma concentration of approx. 1 µg/ml after 10 h, the unadapted salt water group after 24 to 48 h and the fresh water group did not reach this concentration. The results are discussed in relation to the non-ionic diffusion theory and to the alterations taking place in euryhaline species of fish during adaptation to salt water.     

磷酸肌酸对新生鼠缺氧缺血性脑损伤线粒体功能的影响

目的:探讨外源性磷酸肌酸(PCr)在缺氧缺血性脑损伤中对线粒体功能的影响。方法:将96只七日龄Wistar新生鼠随机分为四组,分别为A假手术组、B生理盐水对照组、C磷酸肌酸小剂量干预组、D磷酸肌酸大剂量干预组,每组24只。除假手术组外其余三组动物制成HIBD模型,并在术前1h分别给予生理盐水、小剂量磷酸肌酸、大剂量磷酸肌酸腹腔注射,24h后取脑,观察脑组织线粒体内三磷酸腺苷(ATP)、还原型谷胱甘肽(GSH)以及丙二醛(MDA)的含量变化。结果:外源性磷酸肌酸干预后脑组织中线粒体内ATP、GSH、MDA含量与盐水对照组相比具有差异性(P<0.05)。结论:外源性磷酸肌酸可以改善线粒体能量代谢,减轻脂质过氧化,保护脑组织。     

Tissue Hemoglobins in Bivalvia (Mollusca)

Distribution and properties of tissue hemoglobins in bivalves are reviewed. The mollusk gills are given particular attention; data on their functions, relative weight, and surface area as well as the content, properties, and functional importance of gill hemoglobin are reviewed.     

Cellulose Detected in the Stalk of Protostelium irregularis (Eumycetozoea)1

The stalk of Protostelium irregularis (Eumycetozoea) has been studied with light and electron microscopy and selected-area electron diffraction. The stalk is positively birefringent and fibrillar. Diffraction patterns obtained from stalks indicate that crystalline cellulose I is one component of the stalk.     

Persistent truncus arteriosus in a rhesus monkey (Macaca mulatta)

A 47-day-old female rhesus macaque (Macaca mulatta) was examined because of a severe holosystolic heart murmur (grade 5/6) and signs of congestive heart failure. Results of physical examination, thoracic radiography, and cardiac ultrasonography confirmed an advanced stage of congestive heart failure. Due to the animal's age and clinical signs of disease, a congenital heart defect was suspected. Necropsy revealed a rare congenital heart defect known as persistent (common) truncus arteriosus.     

Complexes of (dG-dC)20 with Mn2+ Ions: A Study by Vibrational Circular Dichroism and Infrared Absorption Spectroscopy

Abstract

The B-Z transition of the synthetic oligonucleotide, (dG-dC)₂₀, induced by Mn²⁺ ions at room temperature, was investigated by absorption and Vibrational Circular Dichroism (VCD) spectroscopy in the range of 1800–800 cm^?1. Metal ion concentration was varied from 0 to 0.73 M Mn²⁺ (0 to 8.5 moles of Mn²⁺ per mole of oligonucleotide phosphate, [Mn]/[P]). While both types of spectra showed considerable changes as the Mn²⁺ concentrations were raised, differences between the two were often complementary in their expression and extent, those displayed by VCD being more clearly evident due to the inversion of the opposite helical sense from the right-handed to the left-handed conformation. The main phase of the transition occurred in the metal ion concentration between 0.8?1.1 [Mn]/[P]. Gradual changes that took place in the spectra were interpreted in terms of simultaneous processes that depended on metal ion concentration, namely B-Z transformation, binding of Mn²⁺ to phosphates and to nitrogen bases, and partial denaturation. Below～0.6 [Mn]/[P], only a small portion of the oligonucleotide adopted the Z conformation within a 3 hour period, whereas conversion was completed in the same time interval for concentrations between 0.9?1.2 [Mn]/[P]. At [Mn]/[P] > 1.7, complete transition to the Z-form took place immediately on adding Mn²⁺. Applying VCD spectroscopy in combination with conventional infrared absorption proved most useful for corroborating changes in the absorption spectra, and for detecting in an unique manner, not attainable by absorption methods, conformational changes that lead to the inversion of the helical sense of the oligonucleotide.     

太赫兹(THz)光谱在生物大分子研究中的应用

太赫兹(THz)辐射是一种新型的远红外相干辐射源,近年来,在生物大分子研究中得到了广泛的应用,特别是在生物分子的结构和动力学特性等方面有着巨大的应用潜力.结合THz光谱的特点,介绍了利用THz光谱对蛋白质、糖类及DNA等生物大分子的探索研究,以及THz技术在测定水环境与生物分子相互作用等方面的应用.探讨了该技术在生物学领域应用中有待解决的问题及发展前景.     

Silver Impregnation of Degenerating Axon Terminals in the Central Nervous System: (1) Technic. (2) Chemical Notes

A new silver technic, tested on the brain of the rat, is described, especially suitable for demonstrating terminal degeneration within the central nervous system. It is a modification of the Glees method, designed to avoid use of tap water in preparing solutions. Some of the chemical principles underlying the process of reductive liberation of metallic silver from ammoniacal silver nitrate solutions are discussed.     

基于真空LHPEF结合胰蛋白酶降解猪血红蛋白

在真空及低压高频脉冲（LHPEF）条件下,结合胰蛋白酶降解猪Hb,利用高效凝胶色谱、Native-PAGE蛋白电泳及紫外扫描来测定其降解效果。结果：在37℃温度下,1.88 V、200 kHz的LHPEF处理猪Hb,电导率为3.45326 ×10^5 μs/cm（对照组为0.645×10^4 μs/cm）。紫外扫描曲线图中的真空LHPEF胰蛋白酶降物中有8个特征吸收峰,而对照组中为6个吸收峰,Native- PAGE蛋白质电泳图中有13个明显色带,而对照组中只有6个色带,高效凝胶色谱图中的特征吸收峰为48个,对照组中7个特征吸收峰。