Poly(U)-directed peptide-bond formation from the 2′(3′)-glycyl esters of adenosine derivatives

Summary The self-condensation of 2(3)-O-glycyl esters of adenosine, adenosine-5-(O-methylphosphate) and P₁, P₂-diadenosine-5-pyrophosphate in 6.2 mM solutions at pH 8.0 and -5°C in the presence of 12.5 mM poly(U) yields approximately 3 times as much diketopiperazine as reactions without poly(U). As the concentration of 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate is decreased from 6.2 mM to 1.5 mM the yield of diketopiperazine in the presence of poly(U) decreases slightly from 6.6% to 5.2%, whereas, in the absence of poly(U) the yield of diketopiperazine decreases substantially from 2.4% to 0.75%. The enhanced yield of diketopiperazine that is attributed to the template action of poly(U) is temperature dependent and is observed only at temperatures below 10°C (5°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) and below 23°C (15°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate. The absence of a template effect at high temperatures is attributed to the melting of the organized helices. The hydrolysis half-lives at pH 8.0 and -5°C of 2(3)-O-(glycyl)-adenosine, 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate), 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate, and 5-O-(glycyl)-adenosine in the presence of poly(U) are substantially larger than their half-lives in the absence of poly(U). The condensation of 2(3)-O-(glycyl)-adenosine yields 5% of 5-O-(glycyl)-adenosine in the presence of poly(U) compared to 0.7% in the absence of poly(U).Abbreviations DKP diketopiperazine - (gly)₂ glycylglycine - (gly)₃ glycylglycylglycine - AppA-gly 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - Ado-2(3)-gly 2(3)-O-(glycyl)-adenosine - Ado-5-gly 5-O-(glycyl)-adenosine - Boc-gly N-tert-butyloxycarbonylglycine - AppA P₁, P₂-diadenosine-5-pyrophosphate - MepA adenosine-5-(O-methylphosphate) - AppA-Boc-gly 2(3)-O-(Boc-glycyl)-P₁, P₂-diadenosine-5-pyrophosphate - Ado-5-Boc-gly 5-O-(Boc-glycyl)-adenosine - Ado-2(3)-Boc-gly 2(3)-O-(Boc-glycyl)-adenosine     

Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

Nicotiana chloroplast genome

Summary Using the existing restriction map and probes from wheat and pea ct-DNA, seven protein genes have been localized in the chloroplast genome of N. tabacum. On the clock-like map, the location of each gene is indicated by its time zone: the 15.2 kD polypeptide of the cytochrome b/f complex at 315, cytochrome f at 430, LS of RuBPCase at 450, both and subunits of ATP synthase at or near 500, proton-translocating subunit of ATP synthase at 820, subunit of ATP synthase at 840 and the 32 kD protein at 930. The genome organization of Nicotiana chloroplast DNA is similar to spinach.     

The sensitivity of head and neck squamous cell carcinomas to tumor necrosis factor-α

Sensitivities to recombinant human tumor necrosis factor- (TNF-) and chemotherapeutic agents (cisplatin, peplomycin, methotrexate) were evaluated in 20 tumor cells of head and neck squamous cell carcinomas, using a dye uptake method. Also, numbers of TNF receptors of these tumor cells were measured by Scatchard plot analysis. There was no relationship between the number of TNF- receptors and the sensitivity to TNF-. Furthermore, there was no correlation between the sensitivity to TNF- and that to chemotherapeutic drugs, nor between the sensitivity to TNF- and the clinical response to chemotherapy including of cisplatin and peplomycin. The sensitivity to TNF- was higher in poorly differentiated carcinomas than in well differentiated ones.Abbreviations BSA Bovine serum albumin - CDDP Cisplatin - 5-Fu 5-fluorouracil - IC50 Inhibition concentration 50 - MTX Methotrexate - PLM Peplomycin - TNF- Tumor necrosis factor-     

6′-Mercaptoguanosine-resistance is related with purF gene encoding 5′-phosphoribosyl-1′-pyrophosphate amidotransferase in inosine-5′-monophosphate overproducing Brevibacterium ammoniagenes

From the gene library constructed with the chromosomal DNA of 6-mercaptoguanosine (MGS)-resistant strain Brevibacterium ammoniagenes IPR-1, a DNA fragment which conferred MGS-resistance to the wild-type strain B. ammoniagenes ATCC6872 was cloned. The purF gene encoding 5-phosphoribosyl-1-pyrophosphate amidotransferase was identified from this fragment and its nucleotide sequence was determined. Wild type purF gene was also cloned by polymerase chain reaction using chromosomal DNA of ATCC6872 as the template and its sequence was determined. Two nucleotides, 583 A and 1065 A, of MGS-resistant purF gene had been changed from 583 G and 1065 G by mutagenesis, respectively. Both changes at position 583 and 1065 were proved to be responsible for MGS-resistance by site-directed mutagenesis.     

The effect of the crossability loci Kr1 and Kr2 on fertilization frequency in hexaploid wheat x maize crosses

Summary Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes Highbury (kr1, Kr2) and Chinese Spring (Hope 5B) (kr1, kr2) were crossable with Seneca 60 maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in Chinese Spring (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.     

The production of haploid wheat plants from wheat x maize crosses

Summary Hybrid embryos from hexaploid wheat x maize crosses rapidly lose the maize chromosomes to produce haploid wheat embryos. Such embryos almost always aborted when left to develop on the plant, and only 1 was recovered from 2440 florets (0.17% of the expected number). Embryos had greater viability in spikelet culture, 47 (26.5% of the expected number) being recovered from 706 ovaries. Thirty-two of these embryos germinated to give green plants, 31 of which were haploid (21 wheat chromosomes) and 1 of which was euploid (42 wheat chromosomes). Spikelet culture enabled 17.1% of the expected number of embryos to be recovered as haploid plants, a 100-fold improvement on allowing embryos to develop in vivo. Ten haploid plants of Chinese Spring (kr1, kr2), 13 plants of Chinese Spring (Hope 5A) (kr1, Kr2), and 8 of Hope (Kr1, Kr2) were recovered. The potential of wheat x maize crosses for wheat haploid production and for gene transfer from maize to wheat is discussed.     

High-level Expression of Maize <Emphasis Type="Italic">γ</Emphasis>-zein Protein in Transgenic Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)

Primers were developed for 118 microsatellites isolated from grape (Vitis vinifera) genomic libraries enriched for (AC)n repeats. Only one microsatellite sequence matched other grape SSR-sequences in the GeneBank database. Genotyping was carried out in the parental lines and four offspring of two pseudo-test-cross populations, Cabernet Sauvignon x Seyval and Chardonnay x Bianca, and a further six other grape genotypes (V. vinifera Sultanina, Merlot, Syrah, Müller-Thurgau, Vitis Regent and V. riparia Gloire de Montpellier). A total of 108 microsatellites showed easily scorable alleles and 100 of them segregated according to a configuration suitable for mapping in either cross. A further 8 SSRs, although unsuitable for mapping in those crosses, showed polymorphism in the other genotypes tested. This set of markers was used, along with 75 microsatellites of other repeat-types, to fingerprint 46 offspring of the cross Chardonnay x Bianca. For each full-sib, individual heterozygosity and distance in repeat units between pairs of alleles at each locus (mean d²) were calculated as a tool for predicting highly outbred recombinant individuals. Six microsatellites with segregation ratios significantly distorted towards the lack of homozygous sibs were identified and mapped to linkage groups LG 3 and LG 5. Estimation of heterozygosity at genome-wide level and genotyping at loci for which homozygous sibs are discriminated against are discussed for marker-assisted background selection in outcrossing grapevines.     

One-bond carbon-proton coupling constants: Angular dependence in β-linked oligosaccharides

Summary The angular dependence of¹J_C,H in model compounds related to -linked oligosaccharides has been established by FPT INDO quantum chemical calculations. Values calculated for models of (1 1)-, (1 2)-, (1 3)- and (1 4)-linked disaccharides were compared, and the effect of the orientation of HO-2 elucidated. The angular dependence of¹J_C,H on the torsional angles ^H and ^H and the solvent dielectric constant (s) was characterized in the form:¹J_C,H = A cos2+B cos + C sin2 + D since + E + Fe. The¹J_C,H values, measured by DEPT methods for C-1-H-1 and C-X-H-X in cellobiose, cyclic trisaccharide and hexopyranoses were used to adjust the calculated angular dependences. Based on the occurrence of the conformers for agarobiose, neoagarobiose, mannobiose and methyl -xylobioside, the thermodynamically averaged <¹J_C,H > values were calculated. The results obtained (<¹J_C-1,H-1 > 162.4, <¹J_{C-4, H-4} > 147.6 Hz for methyl -xylobioside; <¹J_C-1,H-1 > 162.4 and <¹J_C-4,H-4] > 147.6 Hz for mannobiose; <¹J_C-1,H-1 > 162.8 Hz for neo agarobiose and <¹J_C-1,H-1 > 163.2 Hz for agarobiose) agree well with the experimental values of 162.7, 147.5, 160.4, 147.2, 160.9 and 165.7 Hz, respectively.     

Nuclear and cytoplasmic gene control of resistance to loose smut (Ustilago tritici (Pers.) Rostr.) in wheat (Triticum aestivum L.)

Summary Using disomic chromosome substitution lines based on the susceptible wheat cultivar Chinese Spring, loose smut resistance of wheat cultivars Hope and Thatcher was shown to be conferred in each case by a single dominant major gene carried on chromosome 7 A (Hope) or 7 B (Thatcher). Partial resistance was determined by genes on an additional eight Hope or seven Thatcher chromosomes, and similarities were evident between the partial resistance genotypes ofHope and Thatcher. Chinese Spring exhibited a mean infection value of approximately 50%, indicating a significant level of partial resistance, which was found to be due, in part, to genes on the homoeologous chromosome arms 1 As, 1 Es and 1 Ds, and to cytoplasmic genes. Substitution of the Chinese Spring nucleus into the cytoplasm of Aegilops squarrosa, Ae. variabilis or Ae. mutica resulted in increased susceptibility to Ustilago tritici. Several alloplasmic lines of the resistant wheat cultivars Selkirk and Chris exhibited race-specific susceptibility to U. tritici.     

Exact solutions for chemical bond orientations from residual dipolar couplings

New methods for determining chemical structures from residual dipolar couplings are presented. The fundamental dipolar coupling equation is converted to an elliptical equation in the principal alignment frame. This elliptical equation is then combined with other angular or dipolar coupling constraints to form simple polynomial equations that define discrete solutions for the unit vector(s). The methods are illustrated with residual dipolar coupling data on ubiquitin taken in a single anisotropic medium. The protein backbone is divided into its rigid groups (namely, its peptide planes and C frames), which may be solved for independently. A simple procedure for recombining these independent solutions results in backbone dihedral angles and that resemble those of the known native structure. Subsequent refinement of these - angles by the ROSETTA program produces a structure of ubiquitin that agrees with the known native structure to 1.1 Å C rmsd.     

Characterization of Na,K-ATPase genes in Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>) and comparative genomic organization with rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

A combination of molecular and in silico approaches was employed to assemble a survey of Na, K-ATPase genes contained in the ancestrally tetraploid genome of the Atlantic salmon (Salmo salar). Molecular characterization of genomic clones coding for the subunit revealed two single genes (1a and 2) and two pairs of presumably homeologous genes (1b/i-ii and 1c/i-ii). Each of the six genes showed high sequence similarity to isoforms previously isolated from rainbow trout and extensive structural differences relative to putative orthologs in the human genome. In silico analysis of expressed sequence tag (EST) collections indicated that at least five (1a, 1b, 1c, 2, and 3) and four (1a, 1b, 2, and 3b) subunit isoforms are expressed in Atlantic salmon. Meiotic linkage analysis further showed that Na, K-ATPase genes are dispersed throughout the salmon genome, with the exception of two multigene clusters on linkage groups AS-22 and AS-28. Duplicate gene copies for the isoform 1b were assigned to linkage groups with multiple homeologous anchors (AS-22 and AS-23), while 2 duplicates suggested a new homeologous affinity between AS-05 and AS-28. In addition, the comparison of linkage arrangements with rainbow trout also showed that the genomic organization of Na, K-ATPase genes is consistent with the evolutionary conservation of syntenic chromosome regions between these species.Electronic Supplementary Material Supplementary material is available for this article at .     

On the subsarcolemmal localization of phenazine ethosulfate-linked α-glycerophosphate dehydrogenase activity in pigeon pectoralis white muscle fibres

Summary In this study frozen sections of avian striated muscles were incubated for mitochondrial -glycerophosphate dehydrogenase (-GPD) reaction, and the effect of menadione, phenazine methosulfate (PMS) or phenazine ethosulfate (PES) as intermediate electron acceptors was evaluated. Under histochemical conditions, PMS or PES-linked -GPD reaction was poor in the chicken posterior latissimus dorsi and chicken pectoralis muscles. However, PMS or PES-linked -GPD reaction was present characteristically in ths subsarcolemmal mitochondria of the broad white fibres of the pigeon pectoralis muscle only; the subsarcolemmal mitochondria of the narrow red fibres lacked such a reaction pattern. The above reaction pattern, however, differed when compared with the menadione-linked -GPD reaction. The present histochemical evidence suggests the existence of an inherent heterogeneity in the mitochondrial populations of the different avian striated muscle fibres studied.     

A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.     

Donor tissue and culture condition effects on mesophyll protoplasts of Medicago sativa

Mesophyll protoplasts were produced from clones of two cultivars of Medicago sativa, Rangelander and Regen S. Protoplasts from the Regen S clone generally gave rise to calli while those from the Rangelander clone would undergo direct embryogenesis. Effects of plant growth conditions, donor tissue pretreatment and protoplast culture conditions on mesophyll protoplast production and subsequent development patterns were investigated. The major factor determining whether or not mesophyll protoplasts would be produced from either of the clones was the pretreatment in water of shoots excised from the donor plants. Pretreatment in water containing growth regulators did not alter protoplast production or development in the Regen S clone. Pretreatment of the Rangelander clone shoots with abscisic acid or naphthaleneacetic acid was slightly beneficial to embryo production while pretreatment with benzylaminopurine was detrimental. Altered leaf morphology induced by growth condition changes did not affect mesophyll protoplast production or subsequent development patterns when shoots were pretreated in water. Culture of protoplasts in liquid droplets or solid agar medium increased low density protoplast survival and subsequent embryo production in the Rangelander clone.     

Ganglioside-cholera toxin interactions: a binding and lipid monolayer study

Summary On t.l.c. plates ¹²⁵I-cholera toxin binds to a disialoganglioside tentatively identified as GD_lb with about 10 times less capacity than to ganglioside GM₁. Binding of labeled toxin to both gangliosides was abolished in presence of excess amounts of unlabeled B subunit. Ganglioside extracts from human or pig intestinal mucosa showed toxin binding to gangliosides GM₁ and GD_1b. In ganglioside-containing lipid monolayers the penetration of the toxin was independent of the ganglioside binding capacity.Abbreviations GM₂ Gal-NAc14Gal(3-2NeuAc)14G1c1Cer - GM₁ Gal3Ga1-NAc14Gal(32NeuAc)14G1c11Cer - GD_1a NeuAc23Ga113Gal-NAc14Gal(32NeuAc)14G1c11Cer - GD1b Gall3Gal-NAcl4Gal(32NeuAc82NeuAc)14Glc11Cer - GT_1b NeuAc23Ga113Ga1-NAcal4Gal(3-2NeuAc82NeuAc)14G1c11Cer - dpPC 1,2-hexadecanoyl-sn-glycero-3-phosphocholine - dpPE 1,2-hexadecanoyl-sn-glycero-3-phosphoethanolamine     

Cytogenetic analysis of structural rearrangements in three varieties of common wheat,Triticum aestivum

Summary The winter wheat varieties Starke and Cappelle Desprez and the spring wheat Chinese Spring were analysed for structural chromosome rearrangements that resulted in the formation of multivalents in F₁ hybrids. The analyses were carried out using hybrids involving euploids, monosomic and ditelosomic stocks, and double-monotelodisomic constructs. The study confirmed that Cappelle Desprez differs from Chinese Spring in a reciprocal translocation between chromosomes 5B and 7B (Riley et al. 1967); a translocation involving chromosomes 3B and 3D could not be verified. Furthermore, the analysis showed that Starke differs from Chinese Spring in a reciprocal translocation between chromosomes 7A and 7D. Both translocations have a coefficient of multivalent realisation of about 0.84. Further multivalents in euploid Starke, in euploid and some aneuploid stocks of Cappelle Desprez, and in euploid as well as various types of aneuploid hybrids between all three varieties could nearly all be explained hypothesizing that chromosome 2B of both Starke and Cappelle Desprez is a duplication-deficiency chromosome. In the hypothesis a part of the long arm of 2B is missing and replaced by a duplicated part of the long arm of chromosome 2D. The multivalents of this rearrangement showed an average coefficient of realisation of about 0.09.Sven Ellerström died in December 1985     

Is repetitive DNA involved in male gametogenesis ofNarcissus papyraceus?

Summary The male gametophyte of the Spermatophyta is of particular interest when studying quantitative modifications of repetitive DNA which accompany plant differentiation. In fact, this well documented system offers the opportunity to investigate the phenomenon at the nuclear level. In particular, it permits comparison between single haploid nuclei which, though derived from the same mitotic division, have different, well-defined morphological and functional processes. The aim of the present work was to investigate the behaviour of repetitive DNA during male gametogenesis inNarcissus papyraceus. By the use of A+T and G+C specific fluorochromes (DAPI and Chromomycin A₃), and by in situ DNA digestion with appropriate restriction endonucleases (Eco RI and Hae III), it is shown that during the course of gametogenesis, generative and vegetative nuclei behave differently with respect to particular sections of the genome. Characteristic agglomerations of specific A+T rich DNA sequences can be observed, localized by the two distal ends of the spindle-shaped generative nucleus. The surface area occupied by the agglomerations differs significantly at the ends in all observed cases. The above agglomerations are present in most of the generative nuclei and are probably composed of repetitive DNA sequences. Some embryological questions are discussed in the light of these results.Abbreviations DAPI 4,6-diamidino-2-phenylindole - Eco RI Eco RI with star activity (N/AATTN) Dedicated to Prof. E. Battaglia on the occasion of his 75th birthday     

The “Bantu Clinic”: A Genealogy of the African Patient as Object and Effect of South African Clinical Medicine, 1930–1990

This paper is about power, medicine andthe identity of the African as a patient of westernmedicine. From a conventional perspective and asencoded in the current quest for wholeness thatcharacterises South African biomedical discourse, theAfrican patient – like any other patient – has alwaysexisted as an authentic and subjectified being, whosetrue attributes and experiences have been denied bythe mechanistic, reductionistic and ethnocentricpractices of clinical medicine. Against this liberalhumanist perspective on the body as ontologicallyindependent of power, this paper offers a Foucaultianreading of the African patient as – like any otherpatient – contingent upon the force relations immanentwithin and relayed through the clinical practices ofbiomedicine. A quintessential form of disciplinarymicro-power, these fabricate the most intimaterecesses of the human body as manageable objects ofmedical knowledge and social consciousness to makepossible the great control strategies of repression,segmentation and liberation that are the usual focusof conventional investigations into the place andfunction of medicine in society. Since the 1930s whenthe African body first emerged as a discrete object ofa secular clinical knowledge, these have repeatedlytransformed the attributes and identity of the Africanpatient, and the paper traces this archaeology ofSouth African clinical perception from then until the1990s to show how its quest for wholeness is not anend point of discovery or liberation, but merelyanother ephemeral crystallization of socio-medicalknowledge in a constantly changing force field ofdisciplinary power.     

An elongated segment of DNA observed between two human α globin genes

Summary Detailed restriction enzyme analysis of the DNA from a Chinese female showed that one of her chromosomes had a >17.5 kb deletion of DNA, including the , 2, and 1 globin genes, which is present in many Southeast Asians with an -thalassemia-1 chromosome. Her normal chromosome had the expected cluster of -like globin genes (5----2-1-3), but the segment of DNA between the two globin genes was elongated by some 0.5–0.7 kb. Analyses of various restriction sites suggested that this normal variant of the human globin gene complex is due to a crossover between a normal chromosome with () and a chromosome with an -thalassemia-2 (–^3.7) and an -21-hybrid gene.