Integrons found in different locations have identical 5' ends but variable 3' ends.

The positions of the outer boundaries of the 5'- and 3'-conserved segment sequences of integrons found at several different locations have been determined. The position of the 5' end of the 5'-conserved segment is the same for six independently located integrons, In1 (R46), In2 (Tn21), In3 (R388), In4 (Tn1696), In5 (pSCH884), and In0 (pVS1). However, the extent of the 3'-conserved segment differs in each integron. The sequences of In2 and In0 diverge first from the conserved sequence, and their divergence point corresponds to the 3'-conserved segment endpoint defined previously (H.W. Stokes and R.M. Hall, Mol. Microbiol. 3:1669-1683, 1989), which now represents the endpoint of a 359-base deletion in In0 and In2. The sequence identity in In3, In1, In4, and In5 extends beyond this point, but each sequence diverges from the conserved sequence at a different point within a short region. Insertions of IS6100 were identified adjacent to the end of the conserved region in In1 and 123 bases beyond the divergence point of In4. These 123 bases are identical to the sequence found at the mer end of the 11.2-kb insertion in Tn21 but are inverted. In5 and In0 are bounded by the same 25-base inverted repeat that bounds the 11.2-kb insert in Tn21, and this insert now corresponds to In2. However, while In0, In2, and In5 have features characteristic of transposable elements, differences in the structures of these three integrons and the absence of evidence of mobility currently preclude the identification of all of the sequences associated with a functional transposon of this type.     

房室海绵化石的微机研究:性状演化

利用微机对房室海绵进行了１）属的清理工作，２）标准化术语的建立与属的标准化术语描述，３）建数据库，４）性状的统计分析。并发现了房室海绵出水管类型、房室排列方式、房室充填物类型、孔和管、体型和房室形态方面的六大演化趋向。     

Hydrogen cyanide synthesis and antifungal activity of the biocontrol strain Pseudomonas fluorescens In5 from Greenland is highly dependent on growth medium

Hydrogen cyanide (HCN) is a secondary metabolite produced by many antagonistic Pseudomonas species. In the present study, the gene cluster encoding HCN synthesis in a newly isolated Pseudomonas fluorescens strain, In5, from South Greenland was investigated. Sequence analysis showed that the Greenlandic hcn gene cluster comprises a novel hcn cluster. Transposon mutagenesis of strain In5 resulted in mutants In5-2E1 and In5-1H7 with no production of HCN, and mutant In5-6B9 with reduced HCN synthesis. In mutant In5-2E1, the transposon was inserted into the hcnC gene; in mutant In5-1H7, the Tn5 insertion was found in a region upstream of a putative malate:quinone oxidoreductase gene (mqo); and in mutant In5-6B9, the transposon disrupted a probable enoyl-CoA hydratase/isomerase gene. In vitro inhibition experiments with In5 (wild type) and In5-2E1 (mutant) showed that in nitrogen-rich Luria-Bertani medium, strain In5 but not the hcn mutant In5-2E1 produced HCN and inhibited the growth of hyphae of Rhizoctonia solani and Pythium aphanidermatum . In contrast, when cultivating the strains in the carbohydrate-rich potato dextrose medium, neither of the strains produced any HCN, and thus, they were unable to inhibit hyphal growth of fungi. These experiments strongly indicate that the synthesis of HCN is highly dependent on the growth medium used.     

Super Hybrid Rice Breeding in China：Achievements and Prospects

Hybrid rice has contributed greatly to the self-sufficiency of food supply In China. To meet the future demand for rice production, a national program on super rice breeding was established In China In 1996. The corresponding targets, breeding strategies and most significant advances are reviewed In this paper. New plant type models have been modified to adjust to various rice growing regions. In recognition of the Importance of applying parents with Intermediate subspecies differentiation In Increasing F1 yield, medium type parental lines were selected from populations derived from Inter-subspecies crosses with the assistance of DNA markers for subspecies differentiation. Results also indicate that a substantial increase of blomass Is the basis for further enhancement of the grain yield potential, and amelioration of leaf characteristics Is helpful In Increasing the photosynthetic rate. Thirty-four super hybrid rice varieties have been released commercially, growing In a total area of 13.5 million hm2 and producing 6.7 thousand million kg more rice In 1998-2005. Although remarkable progress has been made In super hybrid rice breeding In China, selections on the root system and Integration of more blotechnologlcal tools remain a great challenge.     

Distribution of phenylalanine ammonia-lyase in etiolated and far-red irradiated radish seedlings

Summary In dark-grown Raphanus seedlings, most of the PAL activity is found in roots where it increases sigmoidally during organ development. In hypocotyls, the dark increase of enzyme activity is linear with time. In cotyledons and hooks, dark activity is very low and remains constant. After onset of continuous far-red irradiation, an activity increase is observed in all parts of the seedling. In cotyledons and hooks, the increase is followed by a decrease. This is comparable to light-induced PAL activity described in other materials. In roots and hypocotyls, the initial increase is not followed by a decrease. In dark-grown roots and hypocotyls PAL activity is correlated to fresh weight augmentation. In no part of the seedling could a correlation be found between light-induced PAL activity and anthocyanin formation.     

A pachytene analysis of two male-fertile paracentric inversions in chromosome 1 of the mouse and in the male-sterile double heterozygote

Meiotic studies have been made at pachytene on two paracentric inversions in chromosome 1 of the mouse. Surface-spread preparations of primary spermatocytes have been analysed at the light microscope level in males heterozygous for the inversions In(1)1Rk and In(1)12Rk and in the double heterozygote In(1)1RK/In(1)12Rk. In singly heterozygous form, neither inversion produces any serious effect on male fertility. In the double heterozygote, spermatogenesis is arrested in the majority of cells at the spermatocyte stage and males are rendered totally sterile by azoospermia. In the double heterozygote, a complex loop, indicating the inversion bivalent, is found in 90% of pachytene cells analysed. In the In(1)1Rk/+ heterozygote, a looped bivalent was seen in 47 per cent of pachytene cells but in In(1)12Rk/+ no cells containing loops could be found. -80% of pachytene spermatocytes from the In(1)1Rk/In (1)12Rk double heterozygote showed apposition of the inversion bivalent to the sex bivalent. Such an association was rarely seen in pachytene cells of either of the fertile single heterozygotes. Spermatogenic failure in the double heterozygote may be related to interference, by the inversion bivalent, with X chromosome inactivation at meiotic prophase.     

Synapsis in single and double heterozygotes for partially overlapping inversions in chromosome 1 of the house mouse

Electron microscopic analysis of synaptonemal complexes (SC) in single and double heterozygotes for the partially overlapping inversions In(1)1Icg, In(1)1Rk and In(1)12Rk in the Chromosome 1 of the house mouse reveals a dependence of synapsis and synaptic adjustment on the size and location of the inversions and their interaction. In(1)1Icg contains the insertions of inverted repeats Is(HSR: 1C5)1Icg and Is(HSR: 1I)2Icg as well as inverted euchromatic region. The synaptic adjustment of the D loops by shortening of asynapsed parts of the lateral elements of SC belonging to the insertions occurs at late zygotene-early pachytene stage. After that the synaptic adjustment of the inversion loops takes place. A delay in adjustment was found in diheterozygotes In(1)1Icg/In(1)1Rk and In(1)1Icg/In(1)12Rk. Morphological alterations of the asynapted terminal segments of lateral elements preventing synaptic adjustment were found in single and double heterozygotes for In(1)1Rk and In(1)12Rk. Correspondence between the size of asynapted regions and the probability of association of XY and heteromorphic bivalents was revealed.     

Inhibition of peroxidase oxidation of aromatic amines by substituted phenols

Peroxidase-catalyzed oxidation of o-phenylene diamine (OPD) was competitively inhibited by trimethylhydroquinone (TMHQ), 4-tert-butylpyrocatechol (In5), and 4,6-di-tert-butyl-3-sulfanyl-1,2-dihydroxybenzene (In6). In6 was the most efficient inhibitor (Ki = 11 microM at 20 degrees C in 0.015 M phosphate-citrate buffer, pH 6.0). The effects of In5 and In6 were not preceded by periods of induction of OPD oxidation products (contrary to TMHQ). Peroxidase-catalyzed oxidation of tetramethylbenzidine (TMB) was non-competitively inhibited by In6 and 3-(2-hydroxyethylthio)-4,6-di-tert-butylpyrocatechol (In4), whereas o-aminophenol (OAP) acted as a mixed-type inhibitor. The effects of all three inhibitors were preceded by an induction period, during which TMB oxidation products were formed. Again, In6 was the most efficient inhibitor (Ki = 16 microM at 20 degrees C in 0.015 M phosphate-citrate buffer supplemented with 5% ethanol, pH 6.0). Judging by the characteristics of the inhibitors, taken in aggregate, it is advisable to use the pairs OPD-In5 and OPD-In6 in systems for testing the total antioxidant activity of biological fluids of humans.     

化学交联质谱技术的研究进展

化学交联质谱技术是解析蛋白质结构和研究蛋白质相互作用的重要工具。近5年以来,该技术在方法和应用上都取得了很大的进步。方法上,一方面可断裂交联剂与新型分离富集方法展现了较好的应用前景,另一方面更加高效的交联肽段搜索引擎和质量控制方法为交联质谱数据分析提供了有力的工具。应用上,一方面与冷冻电镜技术结合解析了大量蛋白质的结构,另一方面从研究蛋白质复合物的相互作用发展到研究全蛋白质组水平的相互作用网络。化学交联质谱技术在方法和应用上的蓬勃发展,体现了这一技术的重要作用。本文对化学交联质谱技术的各个环节进行了详细的综述,包括交联剂选择、交联反应、酶切、交联肽段富集、液质联用、交联肽段鉴定、质量控制和生物学应用,重点介绍了最近5年的研究进展。最后,讨论了化学交联质谱技术面临的挑战及未来的发展方向。     

The human Ia-associated invariant chain is synthesized in Ia-negative B cell variants and is not expressed on the cell surface of both Ia-negative and Ia-positive parental cells

The expression of Ia-associated human Invariant (In) chain glycoproteins was studied in the Raji B cells as well as in their RJ 2.2.5 Ia-negative derived variant cells by using a specific rabbit anti-human In chain antiserum. Two-dimensional gel electrophoresis of immunoprecipitates from either biosynthetically labeled or surface labeled cells were analyzed. In addition, flow microfluorometric analysis of stained cells was performed. The results indicate that the In chain is constitutively produced in the Ia-negative B cell variant. Moreover, it appears that several forms of In chain-related molecules, with different charges and distinct m.w. are equally expressed in Ia-positive and Ia-negative B cells. Finally, no evidence could be obtained that the In molecular family was expressed on the cell surface of Ia-positive Raji and Ia-negative RJ 2.2.5 cells.     

An indium:calcium phosphate colloid that specifically targets fibrin

The ability of indium to target fibrin in vitro was evaluated. The radionuclide ^114mIndium (^114mIn) was prepared as a soluble and colloidal (In:In) form, as well as, a mixed indium:calcium phosphate (In:CaP) colloid. Soluble ^114mIn was prepared by maintaining acid pH (50 mM HCl). Colloidal ^114mIn (In:In) was prepared under slightly basic conditions (50 mM Tris-Cl, pH 7.6). The mixed In:CaP colloid was prepared by incubation of ^114mIn with calcium (10 mM) and phosphate (250 M) under slightly basic conditions (50 mM Tris-Cl, pH 7.6). To assess fibrin binding, the three ^114mIn preparations were mixed with diluted human plasma (source of fibrinogen). Fibrin polymerization was initiated by addition of calcium (5 mM) and thrombin (0.5 U/ml). Following incubation (15 min, 37 °C), the fibrin matrix was condensed, removed from the reaction mixture, and washed briefly. Fibrin uptake of ^114mIn (soluble, colloidal, or In:CaP) was determined by gamma counting. Results demonstrated that soluble ^114mIn exclusively bound a plasma protein electrophoretically and immunologically identified as transferrin. Although both colloidal ^114mIn and ^114mIn:CaP bound fibrin, the mixed ^114mIn:CaP colloid demonstrated substantially higher fibrin binding activity (about 2-fold). The target of indium binding was confirmed as fibrin due to the presence of characteristic cross-linked – dimers (100 kDa) and -monomers (58 kDa) by SDS-PAGE. ^114mIn colloid and the mixed ^114mIn:CaP colloid demonstrated no ability to bind fibrins precursor, fibrinogen. ^114mIn:CaP fibrin binding was associated with formation of CaP, as evidenced by its dependence on phosphate concentration. The biocompatibility of CaP including its ability to bind ^114mIn and specifically target fibrin may be of potential value for diagnostic imaging studies to identify regions of occult vascular stenosis (i.e., atherosclerotic plaques, deep vein thrombosis, pulmonary embolus).In memoriam.     

Localization of type 8 17beta-hydroxysteroid dehydrogenase mRNA in mouse tissues as studied by in situ hybridization.

The enzyme type 8 17beta-hydroxysteroid dehydrogenase (17beta-HSD) selectively catalyzes the conversion of estradiol (E2) to estrone (E1). To obtain detailed information on the sites of action of type 8 17beta-HSD, we have studied the cellular localization of type 8 17beta-HSD mRNA in mouse tissues using in situ hybridization. In the ovary, hybridization signal was detected in granulosa cells of growing follicles and luteal cells. In the uterus, type 8 17beta-HSD mRNA was found in the epithelial (luminal and glandular) and stromal cells. In the female mammary gland, the enzyme mRNA was seen in ductal epithelial cells and stromal cells. In the testis, hybridization signal was observed in the seminiferous tubule. In the prostate, type 8 17beta-HSD was detected in the epithelial cells of the acini and stromal cells. In the clitoral and preputial glands, labeling was detected in the epithelial cells of acini and small ducts. The three lobes of the pituitary gland were labeled. In the adrenal gland, hybridization signal was observed in the three zones of the cortex, the medulla being unlabeled. In the kidney, the enzyme mRNA was found to be expressed in the epithelial cells of proximal convoluted tubules. In the liver, all the hepatocytes exhibited a positive signal. In the lung, type 8 17beta-HSD mRNA was detected in bronchial epithelial cells and walls of pulmonary arteries. The present data suggest that type 8 17beta-HSD can exert its action to downregulate E2 levels in a large variety of tissues.     

番茄受精作用及其间隔期的研究

利用常规石蜡切片法研究了番茄受精作用的全过程,具体研究结果为:(1)授粉后2 h,花粉粒在柱头上萌发;约2~4 h,花粉管长入柱头,且末端膨大;约8 h后,生殖细胞进入分裂期;并于约两小时后,分裂为两个精细胞。(2)约14 h,花粉管进入子房腔;约18~24 h,花粉管进入胚囊,破坏一个助细胞,并在其珠孔端释放两个精子;随后被释放的精子移到卵细胞与次生核附近。(3)授粉后约30 h精核进入卵细胞;约34 h,精核与卵核融合,并在卵核内出现分散的雄性染色质,进而出现雄性核仁;44~50 h,雌、雄性核仁融合,形成合子;合子的休眠期为10 h左右。60 h之后,合子分裂形成二细胞原胚。(4)约26 h,另一个精子的精核与次生核核膜相贴伏,随后与之融合;约30~34 h,次生核内出现分散的雄性染色质,随之出现雄性核仁;约38~42 h,雌、雄性核仁融合,形成初生胚乳核。约44 h后,初生胚乳核进行有丝分裂,形成两个胚乳细胞。番茄胚乳发育属于细胞型。初生胚乳核无休眠期。(5)精子与次生核的融合比与卵核的融合快。(6)番茄的受精作用属于有丝分裂前配子融合类型。     

Synapsis in single and double heterozygotes for partially overlapping inversions in chromosome 1 of the house mouse

Electron microscopic (EM) analysis of synaptonemal complexes (SC) in single and double heterozygotes for the partially overlapping inversions In(1)1Icg, In(1)1Rk and In(1)12Rk in chromosome 1 of the house mouse reveals that synapsis and synaptic adjustment are dependent on the size and location of the inversions and interaction between the latter. In(1)1Icg contains insertions of the inverted repeats Is(HSR;1C5)1Icg and Is(HSR;1D)2Icg and an inverted euchromatic region. Synaptic adjustment of the D-loops by shortening of the asynapsed segments of the lateral elements belonging to the insertions occurs at the late zytogene to early pachytene stage. Synaptic adjustment of the inversion loops takes place at early to late pachytene. A delay in adjustment was found in the double heterozygotes In(1)1Icg/In(1)1Rk and In(1)1Icg/In(1)12Rk. A correspondence between the lifespan of asynapsis in inverted regions and the probability of association of XY and heteromorphic bivalents was revealed.     

Chromosomal inversion polymorphism in Afrotropical populations of Drosophila melanogaster

When 41 populations from Africa (south of the Sahara) and Indian Ocean islands were analysed for their chromosomal inversion polymorphism, 34 rearrangements were found, including the four common cosmopolitans (In(2L)t, In(2R)NS, In(3L)P and In(3R)P), four rare cosmopolitans (In(2L)NS, In(3R)C, In(3R)Mo and In(3R)K) and six African polymorphic ('recurrent') endemics. Mean inversion frequencies per major autosome arm were positively and, generally, highly correlated to each other. There was no altitudinal nor latitudinal cline of inversion frequency, except for one African polymorphic endemic. Significant longitudinal clines were detected for In(2L)t, In(3L)P and In(3R)K; in all cases, inversion frequencies decreased eastward. Principal components analysis and ANOVA made it possible to distinguish three groups of populations. A high level of polymorphism was found in populations from west tropical Africa. The other low altitude populations from the mainland were moderately polymorphic, whereas the lowest levels of polymorphism were those of high altitude populations and of Indian Ocean islands. Moreover, some regional and local differentiation was also found. The frequency of unique autosomal inversions was not different from those found in Asia, Australia and America, but was significantly higher than that in Europe and North Africa. A West-East differentiation was also observed for the African polymorphic endemics. The present geographic pattern suggests a long, patchy evolution with restricted gene flow, followed by the modern period with numerous recent migrations linked to human transportation.     

An intronic signal for alternative splicing in the human genome

An important level at which the expression of programmed cell death (PCD) genes is regulated is alternative splicing. Our previous work identified an intronic splicing regulatory element in caspase-2 (casp-2) gene. This 100-nucleotide intronic element, In100, consists of an upstream region containing a decoy 3' splice site and a downstream region containing binding sites for splicing repressor PTB. Based on the signal of In100 element in casp-2, we have detected the In100-like sequences as a family of sequence elements associated with alternative splicing in the human genome by using computational and experimental approaches. A survey of human genome reveals the presence of more than four thousand In100-like elements in 2757 genes. These In100-like elements tend to locate more frequent in intronic regions than exonic regions. EST analyses indicate that the presence of In100-like elements correlates with the skipping of their immediate upstream exons, with 526 genes showing exon skipping in such a manner. In addition, In100-like elements are found in several human caspase genes near exons encoding the caspase active domain. RT-PCR experiments show that these caspase genes indeed undergo alternative splicing in a pattern predicted to affect their functional activity. Together, these results suggest that the In100-like elements represent a family of intronic signals for alternative splicing in the human genome.     

Preparation of liposomes entrapping a high specific activity of 111In3+-bound inulin

Targeting liposomes to specific tissues or cells require the unequivocal determination of the uptake of liposomes at the cellular level. The present report describes the preparation of liposomes entrapping a high specific activity of 111In3+-bound inulin, and the potential applications of a multiple labeling technique for characterizing the extent of uptake of liposomes by tissues or different cells in a given tissue in vivo. The labeling method involves the application of the technique of acetylacetone-mediated, ionophoric loading of 111In3+ into liposomes entrapping an inulin derivative to which a strong chelating agent, diethylenetriamine-pentaacetic acid (DTPA), is bound. Subsequent ionophoric removal of the weakly bound 111In3+ by incubating the previously 111In3+-loaded liposomes with 10 mM nitrilotriacetic acid and 100 microM tropolone at room temperature for 20 min results in the preparation of liposomes entrapping 111In3+-DTPA-inulin. Our method of preparation yields net efficiencies of converting 63-78% of the externally added 111In3+ to liposome-entrapped 111In3+-DTPA-inulin.     

Alterations in high-affinity binding characteristics and levels of opioids in invertebrate ganglia during aging: Evidence for an opioid compensatory mechanism

In Mytilus and Leucophaea the high-affinity binding site density is significantly lower in old animals than in young animals, whereas the low-affinity site density remains unchanged. In Mytilus the estimated met-enkephalin and met-enkephalin-Arg6-Phe7 levels are significantly higher in old than in young animals. In Leucophaea only the met-enkephalin level can be determined, and it is also higher in old animals. The decrease in the high-affinity binding site density and the corresponding increase in endogenous enkephalin levels suggest the existence of an opioid compensatory mechanism associated with the aging process. In Mytilus there is a demonstrated decrease with age in intraganglionic dopamine levels in response to applied opiates. In addition, the inhibition of dopamine-stimulated adenylate cyclase activity by opiates also decreases in older animals. In Leucophaea the sex difference in opioid binding densities diminishes with age.     

The subcellular localization of the carbohydrate epitope 3-fucosyl-N-acetyllactosamine is different in normal and reactive astrocytes.

The carbohydrate epitope 3-fucosyl-N-acetyllactosamine (CD15) is involved in cell-to-cell recognition processes in various tissues. In the present study the subcellular localization of CD15 was immunocytochemically studied in normal and pathological central nervous system fiber tracts of humans and rats. In normal human white matter of the brain, CD15 immunoreactivity was found on the cell surface of astrocytes and within the cytoplasm of oligodendrocytes. In freshly demyelinated lesions of two human diseases (central pontine myelinolysis and multiple sclerosis) strong cytoplasmic CD15 staining was observed in reactive astrocytes. In normal rats CD15 immunostaining was restricted to the surface of astrocytes. In crush-induced lesions of rat optic nerves, however, astrocytes showed a cytoplasmic localization of CD15, 4 and 6 days after injury. In conclusion, abnormal localization of CD15 in reactive astrocytes may be related to altered functional states of these cells during disease processes.     

Molecular biology and the diagnosis, epidemiology and pathogenesis of infectious diseases

In this short review, the impact of molecular biology on microbiology in general is described. Specifically, molecular biology is increasingly enlarging the available choice of methods for the diagnosis of microbial disease. In situ hybridization seems to be a particularly promising procedure. In epidemiology, an interesting facet is the high mutation rate of RNA viruses. In pathogenesis, molecular biology will help to elucidate pathways of infection and the targeting of pathogenic macromolecules within the cell and within an organism.