Crystal and molecular structure of 6,2'-anhydro-1-beta-D-arabinofuranosylctyosine.

The crystal and molecular structure of the title compound has been determined by X-ray diffraction method. The compound crystallizes in monoclinic system with the space group P2₁ and Z=2; the unit cell dimensions are a=10.491, b=7.255, c=6.858 A and β=103.55°. The structure was refined to an R-index of 0.051. The glycosyl torsion angle X_CN is 111.4° (syn-anti) and the arabinose ring forms an exo-conformation, in which C(4′) is displaced by 0.61 A out of the plane of remaining four atoms. The orientation of the C(5′)O(5′) bond is the gauche-gauche as similar as that found frequently in many nucleosides.     

A synthesis of 3′,4-́dideoxykanamycin B

3′,4′-Dideoxykanamycin B, the kanamycin B derivative that is active against resistant bacteria, was prepared from kanamycin B viaN-tosylation, 3′,4′-O-sulphonylation, 3′,4′-unsaturation, and hydrogenation. The unsaturated intermediate was obtained from the 3′,4′-di-O-sulphonyl derivatives by the action of sodium iodide in N,N-dimethylformamide; if zinc dust was added in this reaction, aziridine derivatives were formed, Removal of the tosyl group was successfully performed by using sodium in ammonia-ethylamine.     

Conformational analysis of polynucleotides. I. The favorable left-handed helical model for the poly(8,2''-S-cycloadenylic acid) with high anti conformation.

1) Energy calculations have shown that poly (8,2'-S-cycloadenylic aicd) can form left-handed helices owing to the high anti conformation. 2) Two favorable left-handed helices are characterized by axial translation per residue (Z=4.3 and 3.6A) and by rotations per residue (theta= 40 degrees and -25 degrees). 3) The proposed helical models might be stable in aqueous solution and is well explicable of the optical property of this compound.     

A case report of Turner's syndrome with ring X chromosome.

A case of Turner's syndrome with short stature and 45, XO/46, XXr mosaicism in chromosome study was presented. With special emphasis on endocrinological study, the size of the breasts was normal in contrast to the poor development of the breasts in most of types of Turner's syndrome. She showed normal thyroid function, slightly low level of urinary 17-OHCS, decreased 17-KS, poor response in metopirone test and poor response of HGH to insulin.     

The generation of large pyroninophilic cells in the lymphoid tissues of rats infused with cell-free lymph.

The thoracic duct of Wistar strain rats was cannulated during 5 days for studying the effect of selective lymphocyte depletion on the lymphoid tissue. A technique for the continuous infusion of cell-free lymph, whole lymph of Eagle's medium to the rat with the thoracic duct fistula is described in detail. The prolonged drainage of lymph from rats was followed by lymphopenia, sever atrophy of lymphoid tissues and the depletion of small lymphocytes in the thymus-dependent areas of spleen and lymph nodes. The infusion of cell-free lymph into the drained rat resulted in the recovery of the weight of lymphoid tissues and in the massive proliferation and accumulation of large cells with prominent nucleoli and intensely pyroninophilic cytoplasm in the lymphocyte depleted areas of the peripheral lymphoid tissues and thymic cortex. There was histological evidence that the large pyroninophilic cells developed well in the spleen and tended to localize preferentially around the periarteriolar region through the marginal zone bridging channels to the red pulp. The infusion of Eagle's medium was found ineffective in restoring the weight of the lymphoid tissues and in bringing about the proliferation of lymphoid cells. The rats infused with whole lymph showed almost similar findings biologically and histologically to those of sham-operated rats.     

Remarkable retardation of the senecence of tobacco leaf disks by cordycepin, an inhibitor of RNA polyadenylation

The antibiotic cordycepin (3'-deoxyadenosine), a known specificinhibitor of nucleic acid synthesis and polyadenylation of RNA,remarkably retarded decrease in the chlorophyll and proteincontents of senescing tobacco leaf disks. The effectivenessof cordycepin, at its optimum concentration (ca. 4 x 10^–5M), was 53% as effective as a cytokinin, benzyladenine at 10^–6M. Adenosine and 2'-deoxyadenosine had no anti-senescence action. (Received May 29, 1975; )     

Site‐specific rapid deamidation and isomerization in human lens αA‐crystallin in vitro

Recent studies have suggested that the isomerization/racemization of aspartate residues in proteins increases in aged tissues. One such residue is Asp151 in lens‐specific αA‐crystallin. Although many isomerization/racemization sites have been reported in various proteins, the factors that lead to those modifications in proteins in vivo remain obscure. Therefore, an in vitro system is needed to assess the mechanisms of modifications of Asp under various conditions. Deamidation of Asn to Asp in proteins occurs more rapidly than isomerization/racemization of Asp, although the reaction passes through the same intermediate in both pathways. Here, therefore, we replaced Asp151 in human lens αA‐crystallin with Asn by using site‐directed mutagenesis. The recombinant protein was expressed in Escherichia coli and used to investigate the deamidation/isomerization/racemization of Asn151 after incubation at 50°C for various durations and under different pH. After incubation, the mutant αA‐crystallin was subjected to enzymatic digestion followed by liquid chromatography–MS/MS to evaluate the ratio of modifications in Asn151‐containing peptides. The Asp151Asn αA‐crystallin mutant showed rapid deamidation to Asp with the formation of specific Asp isomers. In particular, deamidation increased greatly under basic conditions. By contrast, subunit–subunit interactions between αA‐crystallin and αB‐crystallin had little effect on the modification of Asn151. Our findings suggest that the Asp151Asn αA‐crystallin mutant represents a good in vitro model protein to assess deamidation, isomerization, and the racemization intermediates. Furthermore, our in vitro results show a different trend from in vivo data, implying the presence of specific factors that induce racemization from L‐Asp to D‐Asp residues in vivo.     

Allelopathic effects of the revegetation species Juniperus sabina L. in semiarid areas of China

Landscape and Ecological Engineering - Juniperus sabina L. is a native evergreen conifer of the Mu Us Sandy Land. It has prostrating stems that can prevent sand shifting and is an important...