D-threo-tetrahydrobiopterin is synthesized via 1'-oxo-2'-D-hydroxypropyl-tetrahydropterin in Dictyostelium discoideum Ax2

The biosynthesis of D-threo-tetrahydrobiopterin (DH4, tetrahydrodictyopterin) in Dictyostelium discoideum Ax2 was investigated through the mutant disrupted in the gene encoding sepiapterin reductase (SR) by insertional inactivation. The mutant cells, being completely devoid of SR protein, showed 18.1% of L-erythro-tetrahydrobiopterin (BH4) and 0.6% of DH4 productions in the wild type cells. The mutant cells were also identified to excrete D- and L-sepiapterin, which were presumed to originate from intracellular 1'-oxo-2'-D-hydroxypropyl- and 1'-oxo-2'-L-hydroxypropyl-tetrahydropterin (H4-pterin), respectively. Furthermore, in a coupled assay with Dictyostelium SR, the mutant cell extract exhibited a novel enzyme activity converting 6-pyruvoyltetrahydropterin to 1'-oxo-2'-D-hydroxypropyl-H4-pterin. These results are clear demonstration of the in vivo synthesis of DH4 via 1'-oxo-2'-D-hydroxypropyl-H4-pterin as well as an alternative synthesis of BH4 and DH4 in the complete absence of SR.     

Responses of medullary neurons to microstimulation of the "locomotor strip" in cats

Synaptic responses of medullary neurons to stimulation of the bulbar locomotor strip with a current of about 20 µA were studied by an extracellular recording method in mesencephalic cerebellectomized cats. The mean latent period of response of 177 neurons was 3.2 msec. Neurons in which synaptic responses appeared were located in both the lateral and the medial parts of the reticular formation, but short-latency responses were recorded predominantly in the lateral part. In response to a single stimulus 32% of neurons generated a discharge of 2–4 spikes. "Respiratory" neurons were not excited by stimulation of the locomotor point. The results indicate that neurons of the locomotor strip may have an excitatory action not only on each other, but also on neurons located medially. The possible mechanisms of the spread of activity to the superior cervical segments of the spinal cord are discussed.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 13, No. 3, pp. 275–282, May–June, 1981.     

Neurons of upper cervical segments responding to stimulation of the bulbar locomotor strip

Synaptic responses of single neurons to stimulation of the bulbar "locomotor strip" were recorded extracellularly from superior cervical segments in mesencephalic cats. With a strength of stimulation of about 30 µA these responses usually had a latent period of 2–7 msec and they arose in neurons located at a depth of between 2 and 4 mm from the dorsal surface (Rexed's laminae V–VIII). These neurons could not be excited antidromically by stimulation of the lumbar or lower cervical segments. However, antidromic responses could be evoked by stimulation of a region located 3–5 mm caudally to the site of recording. It is suggested that neurons of segments C2 and C3 excited by stimulation of the locomotor strip are components of a cell column along which activity spreads polysynaptically in the direction of spinal stepping generators.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 11, No. 3, pp. 245–253, May–June, 1979.     

A One-Pot Preparation of 1-Benzyl-2′-deoxyinosine from ionized 2′-Deoxyinosine

Abstract

A simple and one step synthetic method for the formation of 1-benzyl-2′-deoxyinosine was developed by direct benzylation of ionized 2′-deoxyinosine. Treatment of 2′-deoxyinosine, in the presence of NaOH, with benzyl bromide in 2, 2, 2–trifluoroethanol (TFE) or N, N–dimethylaetamide (DMA) gave 1-benzyl-2′-deoxyinosine in 35% and 80% yields, respectively.     

Towards a general life-history model of the superorganism: predicting the survival,growth and reproduction of ant societies

Social insect societies dominate many terrestrial ecosystems across the planet. Colony members cooperate to capture and use resources to maximize survival and reproduction. Yet, when compared with solitary organisms, we understand relatively little about the factors responsible for differences in the rates of survival, growth and reproduction among colonies. To explain these differences, we present a mathematical model that predicts these three rates for ant colonies based on the body sizes and metabolic rates of colony members. Specifically, the model predicts that smaller colonies tend to use more energy per gram of biomass, live faster and die younger. Model predictions are supported with data from whole colonies for a diversity of species, with much of the variation in colony-level life history explained based on physiological traits of individual ants. The theory and data presented here provide a first step towards a more general theory of colony life history that applies across species and environments.     

Prevalence of human herpesvirus-6B in Korean hematopoietic stem cell transplantation recipients

Human herpesvirus-6 (HHV-6) is a major pathogen associated with diseases of recipients of hematopoietic stem cell transplants (HSCT). We have isolated HHV-6 in Korean HSCT recipients and carried out a prospective investigation of its prevalence. We obtained peripheral blood from HSCT recipients who had signs of HHV-6 infection. Cord blood mononuclear cells (CBMC) and Sup-T1 cells were used to culture the HHV-6. Indirect immunofluorescence assays (IFA), and the polymerase chain reaction (PCR) were employed to detect HHV-6. The prevalence of HHV-6 infection in HSCT recipients was calculated on the basis of the PCR results. HHV-6 was isolated from four clinical samples. After culturing the HHV-6 in CBMC, the standard strain and the four clinical isolates were propagated in Sup-T1 cells. The infected cells became grossly enlarged and multinucleate after 7-21 days. The virus was identified primarily on the basis of the morphological changes of the cultured cells, and confirmed by specific IFA with monoclonal antibody to HHV-6. HHV-6 was detected in each sample by PCR with primers specific for the major immediate early gene. Sequencing of the standard strain and PCR products confirmed identification of the HHV-6B variant. By PCR we detected 415 instances of HHV-6 in 3966 samples (14.6% of peripheral blood mononuclear cells and 6.3% of sera), and HHV-6 DNAemia was most frequent from the second to the fourth week after HSCT.     

Tetrahydropteridine deficiency impairs mitochondrial function in Dictyostelium discoideum Ax2

A putative cellular function of tetrahydropteridines (l-erythro-tetrahydrobiopterin and d-threo-tetrahydrobiopterin) was investigated in Dictyostelium discoideum Ax2 using a mutant disrupted in the gene encoding sepiapterin reductase (SR). The SR mutant, which produces about 3% of tetrahydropteridines if compared to wild-type, was elucidated to have several functional defects related to mitochondria and oxidative stress: retarded growth, poor spore viability, impaired mitochondrial function, and increased susceptibility to oxidative stress induced by hydroxylamine or cumene-hydroperoxide. However, the physiological defects were almost completely rescued by extrachromosomal expression of Dictyostelium SR. The results strongly suggested that tetrahydropteridines in Dictyostelium are associated with mitochondrial function, probably via direct protection against oxidative stress.     

Mobile phase compositions for ceramide III by normal phase high performance liquid chromatography

Ceramide III was prepared by the cultivation ofSaccharomyces cerevisiae. Ceramide III was partitioned from the cell extracts by solvent extraction and analyzed by Normal Phase High Performance Liquid Chromatography (NP-HPLC) using Evaporative Light Scattering Detector (ELSD). We experimentally determined the mobile phase composition to separate ceramide III with NP-HPLC. Three binary mobile phases of n-hexane/ethanol,n-hexane/Isoprophyl Alcohol (IPA) andn-hexane/n-butanol and one ternary mobile phase ofn-hexane/IPA/methanol were demonstrated. For the binary mobile phase ofn-hexane/ethanol, the first mobile phase composition, 95/5 (v/v), was step-increased to 72/23 (v/v) at 3 min. In the binary mobile phase, the retention time of ceramide III was 7.87 min, while it was 4.11 min respectively in the ternary system, where the mobile phase composition ofn-hexane/IPA/methanol, 85/7/8 (v/v/v), was step-increased to 75/10/15 (v/v/v) at 3 min. However, in the ternary mobile phase, the more peak area of ceramide III was observed.