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.     

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.     

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.     

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.     

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.     

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。     

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.     

A Novel Rickettsia Species Detected in Vole Ticks (Ixodes angustus) from Western Canada

The genomic DNA of ixodid ticks from western Canada was tested by PCR for the presence of Rickettsia. No rickettsiae were detected in Ixodes sculptus, whereas 18% of the I. angustus and 42% of the Dermacentor andersoni organisms examined were PCR positive for Rickettsia. The rickettsiae from each tick species were characterized genetically using multiple genes. Rickettsiae within the D. andersoni organisms had sequences at four genes that matched those of R. peacockii. In contrast, the Rickettsia present within the larvae, nymphs, and adults of I. angustus had novel DNA sequences at four of the genes characterized compared to the sequences available from GenBank for all recognized species of Rickettsia and all other putative species within the genus. Phylogenetic analyses of the sequence data revealed that the rickettsiae in I. angustus do not belong to the spotted fever, transitional, or typhus groups of rickettsiae but are most closely related to “Candidatus Rickettsia kingi” and belong to a clade that also includes R. canadensis, “Candidatus Rickettsia tarasevichiae,” and “Candidatus Rickettsia monteiroi.”     

Carrageenan from Eucheuma striatum (Schmitz) in Bacteriological Media

The use of carrageenan from the red alga Eucheuma striatum as a possible substitute for bacteriological agar was investigated. The carrageenan medium was compared with several commercially available media in terms of both their physical properties and the colony characteristics of 16 microorganisms grown on the media.     

New Nitrogen-Fixing Microorganisms Detected in Oligotrophic Oceans by Amplification of Nitrogenase (nifH) Genes

[This corrects the article on p. 3444 in vol. 64, PMID: 9726895.].     

Distinct Yellowfin Tuna (Thunnus albacares) Stocks Detected in Western and Central Pacific Ocean (WCPO) Using DNA Microsatellites

The yellowfin tuna, Thunnus albacares (Bonnaterre, 1788), covers majority of the Philippines’ tuna catch, one of the major fisheries commodities in the country. Due to its high economic importance sustainable management of these tunas has become an imperative measure to prevent stock depletion. Currently, the Philippine yellowfin tuna is believed to be part of a single stock of the greater WCPO though some reports suggest otherwise. This study therefore aims to establish the genetic stock structure of the said species in the Philippines as compared to Bismarck Sea, Papua New Guinea using nine (9) DNA microsatellite markers.DNA microsatellite data revealed significant genetic differentiation between the Philippine and Bismarck Sea, Papua New Guinea yellowfin tuna samples. (FST = 0.034, P = 0.016), which is further supported by multilocus distance matrix testing (PCoA) and model-based clustering (STRUCTURE 2.2).With these findings, this study posits that the yellowfin tuna population in the Philippines is a separate stock from the Bismarck Sea population. These findings add evidence to the alternative hypothesis of having at least 2 subpopulations of yellowfin tuna in the WCPO and calls for additional scientific studies using other parameters to investigate this. Accurate population information is necessary in formulating a more appropriate management strategy for the sustainability of the yellowfin tuna not only in the Philippines but also in the WCPO.