Distribution of organic and inorganic carbon in tissues containing calcium carbonate by secondary ion emission microanalysis]

The differences of emissivity of secondary ions at masses 12 (C+ and C-), 24 (C2-) and 26 (C2H2- or CN-) of organic moitie and CO3Ca of semi thin sections of egg shell of quail allow the distinction between organic and inorganic carbon on images obtained with Secondary Ion Mass Spectroscopy. There differences of emissivity do not correspond only to the difference of concentration but to the difference of ionic yield. The emissivity at mass 26 (C2H2- or CN-) is higher than those obtained at mass 24 (C2-) in glycoproteinic material (rich in Nitrogen) and lower in the embedding material (Araldite, poor in Nitrogen). This result indicates that the ion present at mass 26 could by CN- rather than C2H2-.     

Nuclear pores. can they expand and contract to regulate nucleocytoplasmic exchange?

Summary Recent evidence has revived the idea that translocation of macromolecules between nucleus and cytoplasm may be regulated via expansion and contraction of the entire diameter of the nuclear pore complex. The present investigation does not support this hypothesis.Acknowledgments. We are indebted to Dr J.H.M. Willison for discussion of his and Dr Rajaraman's results before their publication. We also wish to thank Dr C. Thurston, Dr D.H. Williamson and Dr K. Lambert for providing some of the specimens used in this investigation. N.J. Severs acknowledges the support of the Science Research Council and the Cancer Research Campaign.     

氧化铈介孔材料的研究进展

随着对介孔材料的深入研究,CeO2介孔材料因其大比表面积、规则的孔道结构和对金属的高分散性等独特的性能而备受关注。本文详细地论述了介孔CeO2的合成机理与方法,简要地介绍了介孔CeO2的性质和在燃料电池电极以及催化上的应用。最后展望了介孔CeO2的发展前景。     

Immunostimulating lipopeptide,LtriP (RP 56142): Comparison of the effect on hepatic cytochrome P 450 modulation and radioprotection in male and female of three mouse strains

The sex-dependent effect of lauroyl-L-Ala-D--Glu-L,L-A₂pmNH₂ (LtriP, RP 56142) on hepatic microsomal cytochromes P 450 (cyt P 450) was studied in three mouse strains NMRI, C3H/OuJ and C3H/HeJ. In NMRI and C3H/OuJ, strains which are responsive to bacterial lipopolysaccharides (LPS-responsive), regardless of the sex of the mouse, significant decrease in the amount of cyt P 450 was observed after LtriP treatment, with a concomitant reduction in ethoxyresorufin-O-deethylase (cyt P 450 1A-dependent) and 7-ethoxycoumarin-O-deethylase activities. This was not seen in C3H/HeJ (LPS-hyporesponsive) mice. These effects may be related to LtriP-dependent cytokine induction, since neither LtriP nor LPS stimulated interleukin-1 (IL-1) secretion by C3H/HeJ macrophages. 11- and 12-hydroxylations (11- and 12-OH) of lauric acid were compared in C3H/OuJ and C3H/HeJ mice. LtriP depressed the total enzymatic conversion of lauric acid in the two strains without modification of the 11/12-OH ratio for C3H/OuJ or male C3H/HeJ mice. However, in females C3H/HeJ mice this decrease was particularly significant and concerned especially the 12-OH activity (a marker of cyt P450 4A family). Although males of the three strains were more sensitive to irradiation than females, LtriP exerted a sex-independent radioprotection on NMRI and C3H/OuJ mice. Its radioprotective effect was illustrated by the preservation of all the enzymatic activities studied in treated NMRI mice, contrary to irradiated control animals. In contrast, for the C3H/HeJ strain, males were not protected by LtriP treatment and, furthermore, females showed a marked sensitization to irradiation.The effects in CH3/HeJ strain implicate LtriP in the control of cyt P 450 induction and of sensitivity to irradiation independently of IL-1 induction.     

Splenic B-cell activation in lipopolysaccharide-non-responsive C3H/HeJ mice by lipopolysaccharide ofPorphyromonas gingivalis

Porphyromonas gingivalis 381 lipopolysaccharide (LPS) definitely exhibited mitogenic activity in purified B-cells, separated from spleens of LPS-responsive C3H/HeN mice and LPS-non-responsive C3H/HeJ mice by using a magnetic cell sorting system. The mitogenic activity induced byP. gingivalis LPS was incompletely inhibited by polymyxin B.P. gingivalis LPS also induced a higher production of interleukin-6 (IL-6) in splenic B-cells of C3H/HeN mice as compared withEscherichia coli LPS. Furthermore,P. gingivalis LPS, but notE. coli LPS, induced definite IL-6 production in C3H/HeJ mice.P. gingivalis LPS increased tyrosine, serine/threonine phosphorylation of proteins with various major induced bands in splenic B-cells of both C3H/HeN and C3H/HeJ mice. Additionally, radioiodinatedP. gingivalis LPS, similarly toE. coli LPS, bound to a 73-kDa protein on C3H/HeJ as well as C3H/HeN B-cells. ThusP. gingivalis LPS may activate B-cells of C3H/HeJ as well as C3H/HeN mice via the LPS-specific binding protein on the cells.     

The effects of brain monoamine depletion on p-chlorophenyl-alanine-induced hypothermia

Summary I.p. administration of p-chlorophenylalanine produced a fall in rectal temperature in rats. The hypothermia was attenuated after pretreatment of the animals with 5,6-dihydroxytryptamine, but was unaffected after pretreatment of the animals with 6-hydroxydopamine.This work was supported by grants from the National Science Council (Republic of China) and J. Aron Charitable Foundation (USA). The authors are grateful to Dr C.Y. Chai, Dr T.H. Yin, Dr H.H. Lu and Mr C.C. Wei for their advice and support.     

Synthesis of juvenile hormones in vitro by the corpora allata of 5th stage larva of Locusta migratoria migratorioides (R and F) (Insecta, Orthopteroida)]

Corpora allata of Locusta migratoria 5th stage larvae synthesize J.H.1, J.H.2 and J.H.3 in vitro. The C.A. of insects of different ages exbit different rates of J.H. synthesis. J.H.1 and J.H.2 synthesis is less than 1 ng/48 h/gland. During the same time the J.H.3 production may be as much as 25.6 ng/gland. J.H. synthetic activity is the same between right and left C.A. The release of J.H. from the C.A. occurs immediately following synthesis. These results are compared with in vivo haemolymphatic J.H. levels.     

热压烧结ZrB2／B4C陶瓷材料的组织与性能

以B4C、C、ZrO2为主要原料,采用反应热压法制备ZrB2／B4C陶瓷材料。通过对ZrB2／B4C陶瓷材料的显微组织及力学性能的综合分析,发现第二相ZrB2含量为20wt％时,材料具有较好的综合力学性能,相对密度为99．3％,维氏硬度为36．1GPa,抗弯强度为533．3MPa,断裂韧性为6．95MPa·m^1/2,比纯B4C陶瓷材料的性能均有所提高。材料为穿晶和沿晶断裂的混合断裂模式。     

Lack of participation of cytoplasmic choline in the synthesis of acetylcholine in the striatal synaptosomes of the rat]

Synaptosomes prepared from Rat striatum were loaded with (14C) choline at 0 degrees C in the course of a 60 min. preincubation. After the removal, by washing, of the extracellular molecules, synaptosomes were incubated 5 min. at 37 degrees C in the presence of (3H) choline. The measurement of the amounts of (3H) ACh and of (14C) ACh formed allowed us to conclude that the acetylation of the molecules of choline was directly coupled to their passage through the synaptosomal membrane.     

A rapid method of following the spontaneous regression of experimental leukemias

Summary Transplantation of virus and chemically induced leukemias from C3H/He-mgxAKR/F₁ hybrid mice into C3H/He-mg males induced leukemias in the latter, which was followed by a spontaneous regression of the disease within a few days. The regression of leukemia could easily be followed by measuring the changes in the pyruvate kinase activity of para-aortic lymph node cells.     

合成对乙酰氨基苯磺酰氯的新工艺

为了减少氯磺酸的用量,提高对乙酰氨基苯磺酰氯(P ASC)的收率,提出一种新的 P ASC合成工艺,即溶剂法 ClSO3H/PCl5联合氯磺化生产工艺.以乙酰苯胺为原料,通过氯磺酸磺化、五氯化磷氯化,合成 P ASC.在氯磺化过程中引入溶剂,并在反应后期加入助剂,用正交实验确定了最佳的反应条件及原料配比:n(乙酰苯胺)∶n(氯磺酸)∶n(五氯化磷)∶n(助剂)=1.0∶2.0~2.3∶1.0~1.3∶0.1.实验结果表明:新工艺降低了氯磺酸的用量58%,且相同成本条件下的收率比传统工艺提高10~12%     

High molecular transport proteins for JH-III in insect hemolymph

Summary Using two independent techniques, ultracentrifugation in a KBr-gradient, and native pore polyacrylamide gel electrophoresis in combination with [³H]-epoxyfarnesyldiazoacetate photoaffinity labeling, we showed that in the hemolymph ofPeriplaneta americana, and probably also inLeptinotarsa decemlineata JH-III binds to the lipophorin, whereas inLocusta migratoria JH-III binds to a different protein.     

Absorption of double labeled (glycerol 3H-linoleic acid 14C) native bile by phosphatidylcholines]

Double-labeled bile ([U. 3H glycerol] [1. 14C linoleic acid])--in which about 70% of labeling 14C and 80% of labeling 3H of total lipids were borne by phosphatidylcholines (PC), (isotopic ratio of these PC was equal to 1)--was introduced into the duodenum of test Rats, some of them with a bile fistula. As low amounts of the hydrolysis products of biliary PC were found in the intestinal lumen, a higher hydrolysis must occur further (brush border, enterocyte ?) because, in the mucosa, the highest labeling 14C was present as triglycerides and PC have an isotopic ratio 3H/14C higher than 1. As in the lumen the isotopic ratio 3H/14C of PC was higher than 1 and increased with the time elapsed, this finding suggests that mucosal PC were added to biliary PC (secretion or desquamation ?) unless these modifications were due to luminal micro-organisms. As test Rat bile was poorly labeled a very weak enterohepatic circulation of biliary diunsaturated PC may exist.     

Architecture and functional properties of the CFTR channel pore

The main function of the cystic fibrosis transmembrane conductance regulator (CFTR) is as an ion channel for the movement of small anions across epithelial cell membranes. As an ion channel, CFTR must form a continuous pathway across the cell membrane—referred to as the channel pore—for the rapid electrodiffusional movement of ions. This review summarizes our current understanding of the architecture of the channel pore, as defined by electrophysiological analysis and molecular modeling studies. This includes consideration of the characteristic functional properties of the pore, definition of the overall shape of the entire extent of the pore, and discussion of how the molecular structure of distinct regions of the pore might control different facets of pore function. Comparisons are drawn with closely related proteins that are not ion channels, and also with structurally unrelated proteins with anion channel function. A simple model of pore function is also described.     

Three classes of C2H2 zinc finger proteins

C2H2 zinc finger proteins probably comprise the largest family of regulatory proteins in mammals. Most zinc fingers bind to a cognate DNA. In addition to DNA, many of the proteins also bind to RNA or protein, and some bind to RNA only. The binding properties depend on the amino acid sequence of the finger domains and of the linker between fingers, as well as on the higher-order structures and the number of fingers. C2H2 zinc finger proteins contain from 1 to more than 30 figures. Based on the number and the pattern of the fingers, most of the proteins can be classified into one of three groups: triple-C2H2, multiple-adjacent-C2H2, and separated-paired-C2H2 finger proteins. In contrast to proteins with triple-C2H2 fingers, proteins with multiple-adjacent-C2H2 fingers can bind multiple, different ligands. Proteins with a number of separated-paired fingers bind to the target by means of only a single pair.     

第一性原理研究高压下单轴压缩硝基甲烷的结构性质

运用第一性原理方法,计算研究了在0～40GPa压强范围内硝基甲烷键长的变化研究和固态硝基甲烷结构性席随属强的变化。研究发现,在低于20GPa时所有的键变化都比较小,在2～30GPa时被压缩,在30-40GPa时又被拉伸。在40GPa高压下,几乎所有的键都处于拉伸状态,只剩下部分N-O键被压缩。此外,C—H键在压强下的拉伸与甲基的转动和原予闯电荷的转移有关。在30GPa时H原子的电荷转移到C和N原予,而甲基的转动使得分子间的距离变小。逮使得C—H键较弱而容易拉伸。     

Vitellogenesis in the air breathing fish,Channa punctatus (Bloch)

Summary Two types of yolk develop in the oocyte ofChanna punctatus. The carbohydrate yolk, which develops from the material present in the ooplasm, breaks up for the use of the growing oocyte before ovulation takes place. The proteid yolk, developing from the extraoocytic material, finally crams the fully mature oocyte, perhaps to participate in the process of embryogenesis.Acknowledgments. The authors are grateful to Professor C.C. Das, for his encouragement and the laboratory facilities. The award of a U.G.C. junior fellowship to one of us (U.R.A.) by the Berhampur University is thankfully acknowledged.     

Scientific Governance in Britain 1914–79

John Harrison (1693–1776) is regarded as the father of chronometry. During his lifetime, he relentlessly pursued one of humankind's greatest and oldest challenges—that of finding the longitude at sea. In succeeding (according to the rules dictated by an Act of Parliament), he bequeathed to humankind the most accurate portable timekeeper the world had ever seen. It is a remarkable fact that his timekeeper, known today as H4, remains more accurate than the majority of expensive mechanical wristwatches manufactured today. Such accuracy required novel approaches to address the various difficulties that befall all mechanical watches, and Harrison overcame many of these with his own innovations. The reduction or elimination of friction is one such problem with clocks and watches, and from an early age Harrison demonstrated his mastery in this subject. This is typified by his choice of woods in his early clocks, and in later clocks by his ‘grasshopper’ escapement. In the 1750s, Harrison's attention switched from clocks to watches, necessitating a hardwearing, low friction material to be found for the pallets in the escapement of his timekeepers. He found these properties in diamond, and in utilizing this to great effect in H4's escapement, he became one of the first people to use diamond as a high-tech material. This paper describes a scientific investigation into the diamond pallets of H4 using Raman microscopy, X-ray diffraction and optical microscopy, to elucidate why diamond was used rather than a more conventional jewel such as ruby, and to gain some insight into how Harrison might have achieved their unconventional morphology. From the evidence presented here, together with evidence collected from primary sources, it is shown that his use of diamond as a hard, low friction material was nothing other than extraordinary, and should be regarded in the same high esteem as his other technological gifts to the world.     

Histoautoradiographic study of two target organs (epididymis and femoral glands) after injection of 3H testosterone in a non-mammalian vertebrae, the viviparous lizard]

After 3H testosterone injection into castrated males of the Lizard Lacerta vivipara, the radioactive compound is detected by radioautography of epididymis, femoral glands, gut and liver. Between 1 hr. 30 min. to 12 hrs. of retention the 3H material concentrates progressively into nuclei of the glandular cells of epididymis and femoral organs although no particular concentration occurs in gut and liver cells. This submammalian model is consistent with those previously described for mammals.     

A simple method for determination of the proportion of 2C and 4C cells in a dormant embryo

Summary Pea embryos grown in the presence of 2.5 mM hydroxyurea from the beginning of imbibition showed a mitotic peak the height of which was considerably less than that of the control, material. Soon after the mitotic peak, there was a complete cessation of mitosis in the treated material. The extent of suppression of mitosis during the first post-dormancy cell cycle caused by hydroxyurea has been used to obtain an estimate of the relative proportion of 2C and 4C cells in the embryo.