Associations among inbred lines of maize using electrophoretic,chromatographic, and pedigree data

Summary Associations among 17 Iowa Stiff Stalk Synthetic derived inbred lines of maize (Zea mays L.) were determined using multivariate and cluster analysis. Objectives were to assess the level of unique characterization among lines afforded by reversed-phase high-performance liquid chromatography (RP-HPLC) of zeins and starch gel electrophoresis of isozymes and to compare associations among lines revealed by biochemical and pedigree data. Isozymic data for 33 loci provided unique discrimination among 88% of the lines; 2 closely related lines were indistinguishable. Seventy-one percent of the lines could be uniquely and unambiguously identified by RP-HPLC. Biochemical data showed associations between lines that would be expected on the basis of pedigree. Nevertheless, different associations were revealed by allozymic and chromatographic data. Although these data permitted a high degree of unique identification, additional markers, covering a larger proportion of the genome, are needed to more adequately monitor similarities among genes that respond to selection during plant breeding.     

Variation in kafirin and alcohol-soluble glutelin chromatograms of sorghum inbred lines revealed by reversed-phase high-performance liquid chromatography

Summary Separations of kafirin and alcohol soluble glutelin proteins by reversed-phase high-performance liquid chromatography (RP-HPLC) from 7 inbreds and one hybrid of sorghum [Sorghum bicolor (L.) Moench] and one source of Johnsongrass [Sorghum halapense (L.) Pers.] were compared. Objectives were to assess the stability of protein profiles for seed sources produced at different locations and in different environments to examine the potential of RP-HPLC to provide genotypic profiles for sorghum. Analyses of variance data showed that levels of variation due to environments and locations were small; the majority of variation (93%) was among genotypes. Associations among inbreds revealed by multivariate and cluster analysis showed similarity with those that would be expected on the basis of pedigree. A chi-square analysis showed no deviation in the hybrid profile from the expected 21 ratio of peaks from the female and male inbred parents, respectively. Improvements in the ability to correctly assign common peaks are necessary before associations among numerous sorghum genotypes can be reliably demonstrated by analysis of data from reversed-phase high-performance liquid chromatography (RP-HPLC).     

Arabidopsis thaliana ‘extra-large GTP-binding protein’ (AtXLG1): a new class of G-protein

Heterotrimeric GTP-binding proteins, composed of , , and subunits, are involved in signal transduction pathways in animal and plant systems. In plants, physiological analyses implicate heterotrimeric G-proteins in ion channel regulation, light signaling, and hormone and pathogen responses. However, only one class of plant G genes has been identified to date. We have cloned a novel gene, Arabidopsis thaliana extra-large GTP-binding protein (AtXLG1). AtXLG1 appears to be a member of a small gene family and is transcribed in all tissues assayed: roots, leaves, stems, flowers, and fruits. The conceptually translated protein from AtXLG1 is 99 kDa, twice as large as typical G proteins. The carboxy-terminal half of the AtXLG1 protein has significant homology to animal and plant G proteins. This region includes a GTP-binding domain, a predicted helical domain, and an aspartate/glutamate-rich loop, which are characteristics of G's. Despite the absence of some of the amino acids implicated in GTP binding and hydrolysis by crystallographic and mutational analyses of mammalian G's, recombinant AtXLGl binds GTP with specificity. The amino-terminal region of AtXLGl contains domains homologous to the bacterial TonB-box, which is involved in energy transduction between the inner and outer bacterial membranes, and to zinc-finger proteins. Given the unique structure of AtXLG1, it will be of interest to uncover its physiological functions.     

Linear differentiation of cereal chromosomes

Summary Using the Giemsa technique of differential staining (the BSG test), we have studies the karyotypes and constructed the idiograms of T. aestivum L. var. Diamant and Chinese Spring, T. Monococcum L. v. hornemannii ssp. roles occidentali georgicum Dek., Aegilops squarrosa L. v. Meeyeri, T. aestivum. The karyotypes of Chinese Spring and Diamant differ drastically both in total structural heterochromatin content and its localization on the nine morphologically homeologous chromosomes. The rest of the twelve pairs of chromosomes showed no morphological similarity. This indicates considerable differences in the phylogeny of the varieties, and also an absence of unique karyotype in T. aestivum.Three chromosomes of Ae. Squarrosa are similar to those of Chinese Spring, yet, on the whole, the chromosomal structural specificity of the diploids studied is so high that we fail to understand the nature of the homology between common wheat and its supposed diploid ancestors.The role of introgression in the evolution of the genomes of Triticum and Aegilops, and also the meaning of the conjugation and BSG tests in resolving the phylogeny, is discussed.     

Oligomerization of deoxynucleoside-bisphosphate dimers: Template and linkage specificity

Evidence is presented that a poly(U) template selectively favors the oligomerization of the activated, 3–5 pyrophosphate-linked dimer pdAppdAp, in comparison with the 3–3 and 5–5 linked dimers. In the absence of poly(U), the 5–5linked dimer is the most reactive, and chains are formed which are more than 60 monomer units in length.Nucleic Acid-Like Structures V. For the previous paper in this series see Visscher and Schwartz (1988).     

Molecular characterization of β-thalassemia in Hungary

We have identified seven different -thalassemia mutations and one -thalassemia determinant (the Sicilian type) in 32 members of 17 Hungarian families. The most common mutation is the IVS-I-1 (GA) change; its high frequency is comparable to that observed in neighboring Czechoslovakia. Additional mutations are of Mediterranean origin. One rare mutation (initiation codonATGGTG) was identified as an independent mutation because of the absence of known polymorphisms in the -globin gene. One new frameshift at codon 51 (-C) was observed in a single individual; hematological data were as expected for a °-thalassemia heterozygosity.     

Mutant of Escherichia coli with unusual patterns of rpoB,C expression in response to rifampicin and acridine orange

Summary A mutation located near rpoB (89) in E. coli is responsible for unusual patterns of and (but not L7/L12) synthesis in response to the drugs rifampicin and acridine orange.     

Regulation of somatic embryogenesis in celery cell suspensions

The regulation of somatic embryogenesis in celery (Apium graveolens L.) was studied to determine means of increasing its efficiency. Highly embryogenic cell lines were achieved by inducing cell cultures from in vitro plants which were previously regenerated from somatic embryos (secondary cell lines). The early detection of embryogenic potential of new cell lines was found to be regulated by 2,4-dichlorophenoxyacetic acid, mannitol and culture duration. Less frequent subculturing allowed embryogenic potential to be expressed earlier. Increased synchronization of celery somatic embryos was induced by two means: adding abscisic acid to the regeneration medium; and segregating the embryos by sieving them through serial metal mesh screens. When abscisic acid was removed from the growth medium, its effects became quickly transient. Embryos of 1400 µm in size provided the best growth rate and uniformity.     

Tn1000 (γδ) insertions stabilize pBR322-derived recombinant plasmids in Escherichia coli

Tn1000 (or ) insertions in a pBR322-recombinant plasmid carrying the threonine operon (pBE) were obtained either spontaneously during chemostat cultivation (pBE-2) or selected during transconjugation (pBE-3 and pBE-4). The different insertion derivatives were tested for their stability in different host genetic backgrounds (in relation to threonine auxotrophy and recA function), various media composition (liquid or solid, rich or minimal) and growth temperatures (30°C, 37°C and 42°C). All the derivatives carrying the sequence, albeit increasing their size from 9.7 to 15.6 Kb, significantly enhanced segregational and structural plasmid stability in every condition tested.     

Qualitative Analysis of the Carbohydrate Composition of Apolipoprotein H

The specific binding of digoxigenin-labeled lectins to carbohydrate moieties is used to characterize the carbohydrate chains bound to apolipoprotein H. Our results show that apolipoprotein H is rich in sialic acid linked (2–6) to galactose or N-acetylgalactosamine. Sialic acid is not (2–3)-linked to galactose. Galactose is (1–4)-linked to N-acetylglucosamine and (1–3)-linked to N-acetylgalactosamine. High-mannose N-glycan chains are barely detectable. After N-glycosidase F treatment the molecular weight is substantially reduced. The main band is 32,500 daltons. Carbohydrate O-linked chains, which are mainly represented by sialic acid, are (2–6)-linked to galactose or N-acetylgalactosamine. Galactose is also organized in O-linked chains and it is (1–4)-linked to N-acetylglucosamine and (1–3)-linked to acetylgalactosamine. Biochemical analysis of carbohydrate structures reveals that no specific carbohydrate complex is bound to a single isoform.     

ggComp enables dissection of germplasm resources and construction of a multiscale germplasm network in wheat

Accurate germplasm characterization is a vital step for accelerating crop genetic improvement, which remains largely infeasible for crops such as bread wheat (Triticum aestivum L.), which has a complex genome that undergoes frequent introgression and contains many structural variations. Here, we propose a genomic strategy called ggComp, which integrates resequencing data with copy number variations and stratified single-nucleotide polymorphism densities to enable unsupervised identification of pairwise germplasm resource-based Identity-By-Descent (gIBD) blocks. The reliability of ggComp was verified in wheat cultivar Nongda5181 by dissecting parental-descent patterns represented by inherited genomic blocks. With gIBD blocks identified among 212 wheat accessions, we constructed a multi-scale genomic-based germplasm network. At the whole-genome level, the network helps to clarify pedigree relationship, demonstrate genetic flow, and identify key founder lines. At the chromosome level, we were able to trace the utilization of 1RS introgression in modern wheat breeding by hitchhiked segments. At the single block scale, the dissected germplasm-based haplotypes nicely matched with previously identified alleles of “Green Revolution” genes and can guide allele mining and dissect the trajectory of beneficial alleles in wheat breeding. Our work presents a model-based framework for precisely evaluating germplasm resources with genomic data. A database, WheatCompDB (http://wheat.cau.edu.cn/WheatCompDB/), is available for researchers to exploit the identified gIBDs with a multi-scale network.

ggComp is a genomic-based approach that enables multi-scale germplasm network construction and promotes germplasm resource utilization in crop breeding.     

Generation means analysis for productivity in two diverse peanut crosses

Summary Utilization of exotic germplasm resources for population improvement in peanut (Arachis hypogaea L.) has increased as the need to increase genetic diversity among peanut cultivars was recognized. Progeny of crosses of two unadapted germplasm lines (GP-NC 343 and FESR-11-P11-32) with an adapted cultivar (NCV11) of peanut were evaluated for the genetic factors influencing the inheritance of yield and fruit characters in crosses among diverse lines. Objectives were to (1) estimate the relative importance of additive and nonadditive genetic effects in the inheritance of yield and fruit characters in two diverse peanut crosses; (2) determine the proportion of exotic germplasm that gave the optimum combination of mean productivity and genetic variability for each of the crosses; (3) relate the results to theories regarding the transfer of desirable alleles from exotic germplasm into adapted breeding populations. Crosses and backcrosses were made to generate germplasm lines (ten generations) ranging from 0 to 100% exotic germplasm for each cross. The populations were evaluated in replicated field trials. Yield and six fruit characters were measured, and a weighted analysis of variance was conducted to determine if significant differences existed among generations. Generation means analyses were performed for each trait measured in each of the crosses using both three- and six-parameter models, which were tested for goodness-of-fit with a joint-scaling test. Significant differences were detected among generations for most traits measured in both crosses. Estimates of additive genetic effects were significant for pod weight and seed weight in cross 1 (NC-V11 x GP-NC 343) and for all traits in cross 2 (NC-V11 x FESR-11-P11-32) except seedpod ratio. Significant estimates of dominance effects were found for pod length, pod width, and pod weight in cross 1 and for pod length in cross 2. No significant estimates of digenic effects were observed in cross 1, whereas in cross 2 estimates of additive x dominance epistatic effects were significant for yield and pod length, while estimates of additive x additive effects were significant for seed number. Regression of trait means on generations showed a curvilinear response for all traits in cross 1 except seed weight, which gave a linear response. For all traits in cross 2, the relationship between productivity and proportion of unadapted germplasm was effectively linear. Based on generation means and variances, progeny from the first or second backcross generation to the recurrent parent should be expected to give an optimum combination of mean productivity and relative variability in the population.The research reported in this publication was funded in part by the North Carolina Agricultural Research Service     

Differential expression of enzyme activities initiating anoxic metabolism of various aromatic compounds via benzoyl-CoA

The regulation of the expression of enzyme activities catalyzing initial reactions in the anoxic metabolism of various aromatic compounds was studied at the whole cell level in the denitrifying Pseudomonas strain K 172. The specific enzyme activities were determined after growth on six different aromatic substrates (phenol, 4-hydroxybenzoate, benzoate, p-cresol, phenylacetate, 4-hydroxyphenylacetate) all being proposed to be metabolized anaerobically via benzoyl-CoA. As a control cells were grown on acetate, or aerobically on benzoate. The expression of the following enzyme activities was determined.Phenol carboxylase, as studied by the isotope exchange between ¹⁴CO₂ and the carboxyl group of 4-hydroxybenzoate; 4-hydroxybenzoyl-CoA reductase (dehydroxylating); p-cresol methylhydroxylase; 4-hydroxybenzyl alcohol dehydrogenase; 4-hydroxybenzaldehyde dehydrogenase; coenzymeA ligases for the aromatic acids benzoate, 4-hydroxybenzoate, phenylacetate, and 4-hydroxyphenylacetate; phenylglyoxylate: acceptor oxidoreductase and 4-hydroxyphenylglyoxylate: acceptor oxidoreductase; aromatic alcohol and aldehyde dehydrogenases.The formation of most active enzymes is strictly regulated; they were only induced when required, the basic activities being almost zero. The observed whole cell regulation pattern supports the postulate that the enzyme activities play a role in anoxic aromatic metabolism and that the compounds are degraded via the following intermediates: Phenol 4-hydroxybenzoate 4-hydroxybenzoyl-CoA benzoyl-CoA; 4-hydroxybenzoate 4-hydroxybenzoyl-CoA benzoyl-CoA; benzoate benzoyl-CoA; p-cresol 4-hydroxybenzaldehyde 4-hydroxybenzoate 4-hydroxybenzoyl-CoA benzoyl-CoA; phenylacetate phenylacetyl-CoA phenylglyoxylate benzoyl-CoA plus CO₂; 4-hydroxyphenylacetate 4-hydroxyphenylacetyl-CoA 4-hydroxyphenylglyoxylate 4-hydroxybenzoyl-CoA plus CO₂ benzoyl-CoA.     

Diel vertical migration and feeding rhythm of Daphnia longispina and Bosmina corexoni in Lake Toya, Hokkaido, Japan

Diel vertical migration (DVM) and diel feeding rhythm of two cladocerans, Daphnia longispina and Bosmina coregoni were investigated at the pelagic area of Lake Toya (Hokkaido, Japan) in May, August and October 1992. Both species performed nocturnal DVM. The amplitude of DVM, however, became smaller from May to October. Such seasonal variations in DVM could not be explained by light penetration and/or water temperature. The two species had a clear feeding rhythm; they fed at night in May and October but also after sunrise in August. These feeding rhythms appeared to be related to the light-dark cycle, but were not necessarily associated with their DVM. We suggest that the diel feeding rhythm and DVM are regulated independently by light cues.     

Oxygen consumption of Astyanax fasciatus (Characidae,Pisces): a comparison of epigean and hypogean populations

Synopsis The standard and routine oxygen consumptions of Astyanax fasciatus from one surface population (Rio Teapao) and three cave populations (Chica, Micos and Pachon caves: sAnoptichthys jordani, the Micosfish and Anoptichthys antrobius) were determined individually over 24 hours by the use of a flow-through respirometer and polarographic oxygen electrodes. The phylogenetically oldest Pachon fish had a significantly lower standard metabolic rate (0.230 ± 0.036 mg O₂ g^-1 h^-1) than the epigean Teapao fish, the hybrid Chica fish and the phylogenetically younger Micos fish (0.314 ± 0.081 mg O₂g-^-1h^-1, 0.284 ± 0.048 mg O₂g^-1h^-1, 0.277 ± 0.063 mg O₂g^-1h^-1). No significant differences could be determined among the latter three populations. A significant difference in routine metabolic rate existed only between the Pachon fish (0.309 ± 0.0.56 mg O₂g^-1h^-1) and the Teapao fish (0.415 ± 0.071 mg O₂g^-1h^-1). The Chica fish (0.356 ± 0.084 mg O₂g^-1h^-1) and the Micos fish (0.355 ± 0.080 mg O₂ g^-1h^-1) could not be separated from either the Teapao or the Pachon fish, but a decreasing trend from the surface population through the Chica and the Micos to the Pachon population was obvious. During a starvation period of 29 days the metabolic rate of epigean Teapao and hypogean Pachon fish decreased significantly by 32.5% and 34.8% (standard oxygen consumption rate) and 27.5% and 28.2% (routine oxygen consumption rate), respectively. Body mass loss during the starvation period was 16.3% for the Teapao fish and 9.5% for the Pachon fish.     

Genetic analysis and mapping of resistance to lettuce dieback: a soilborne disease caused by tombusviruses

A diverse collection of modern, heirloom and specialty cultivars, plant introduction (PI) accessions, and breeding lines of lettuce were screened for susceptibility to lettuce dieback, which is a disease caused by soilborne viruses of the family Tombusviridae. Susceptibility was evaluated by visual symptom assessment in fields that had been previously shown to be infested with Lettuce necrotic stunt virus. Of the 241 genotypes tested in multiple field experiments, 76 remained symptom-free in infested fields and were therefore classified as resistant to dieback. Overall, resistant genotypes were as prevalent among modern cultivars as in heirloom cultivars or primitive germplasm. Within modern germplasm, however, all crisphead (iceberg) cultivars were resistant, while all romaine cultivars were susceptible. Using enzyme-linked immunosorbent assay, tombusviruses were detected in leaves of some plants of resistant genotypes that were grown in infested fields, suggesting that symptom-free plants are not immune to viral infection. The inheritance of resistance was studied for Salinas, a modern iceberg cultivar, and PI 491224, the progenitor of recently released romaine germplasm with resistance to lettuce dieback. Resistance was conferred by a dominant allele at a single locus in both genotypes. The tombusvirus resistance locus from Salinas, Tvr1, was mapped in an intraspecific Lactuca sativa population to a location that corresponds to linkage group 2 on the consensus map of Lactuca. The largest cluster of resistance genes in lettuce, the Dm1/Dm3 cluster, is found on this linkage group; however, the precise position of Tvr1 relative to this cluster has not yet been determined. To our knowledge, Tvr1 is the first tombusvirus resistance gene identified for any plant host.Electronic Supplementary Material Supplementary material is available for this article at     

An escape from ‘the prisoner's dilemma‘

Conventional escapes from the paradox that noncooperation between two organisms may be rational, even when cooperation would yield a higher reward to each, are based on the mechanism of reciprocity; but an analytical model of foraging among oviposition sites reveals a more immediate rationale, namely, equivalence of selfishness and altruism. The resulting game is unconditionally the prisoner's dilemma if the players have perfect recognition; however, in the absence thereof and for three different parameter regimes, it yields either the prisoner's dilemma, or two evolutionarily stable strategies, or a unique cooperative ESS. Thus unrecognition can favor cooperation; and environments can exist in which cooperation persists, or even invades, without reciprocity. The results suggest that different mechanisms for cooperation may operate at different levels of neural complexity.     

Haplotyping and mapping a large cluster of downy mildew resistance gene candidates in sunflower using multilocus intron fragment length polymorphisms

Downy mildew (Plasmopara halstedii (Farl.) Berlese et de Toni) is a serious foliar pathogen of cultivated sunflower (Helianthus annuus L.). Genetic resistance is conditioned by several linked downy mildew resistance gene specificities in the HaRGC1 cluster of TIR-NBS-LRR resistance gene candidates (RGCs) on linkage group 8. The complexity and diversity of the HaRGC1 cluster was assessed by multilocus intron fragment length polymorphism (IFLP) genotyping using a single pair of primers flanking a hypervariable intron located between the TIR and NBS domains. Two to 23 bands were amplified per germplasm accession. The size of the included intron ranged from 89 to 858 nucleotides. Forty-eight unique markers were distinguished among 24 elite inbred lines, six partially isogenic inbred lines, nine open-pollinated populations, four Native American land races, and 20 wild H. annuus populations. Nine haplotypes (based on 24 RGCs) were identified among elite inbred lines and were correlated with known downy mildew resistance specificities. Sixteen out of 39 RGCs identified in wild H. annuus populations were not observed in elite germplasm. Five partially isogenic downy mildew resistant lines developed from wild H. annuus and H. praecox donors carried eight RGCs not found in other elite inbred lines. Twenty-four HaRGC1 loci were mapped to a 2-4 cM segment of linkage group 8. The multilocus IFLP marker and duplicated, hypervariable microsatellite markers tightly linked to the HaRGC1 cluster are powerful tools for distinguishing downy mildew resistance gene specificities and identifying and introgressing new downy mildew resistance gene specificities from wild sunflowers.     

TNF alpha is required for hypoxia-mediated right ventricular hypertrophy

Hypoxia has been shown to activate the pleiotropic cytokine TNF in the lung. TNF in turn, is known to induce pulmonary vasoconstriction. Additional effects of this cytokine in hypoxia mediated cardiopulmonary remodeling are poorly understood. To further evaluate the role of TNF in chronic hypoxia we exposed TNF null (TNF–/–) and wild-type mice to three weeks of hypobaric hypoxia (10% O₂). Equivalent erythocytosis (Hematocrit increased by 40%) developed in both genetic backgrounds. In contrast, right ventricular systolic pressure increased in response to three weeks of hypoxia in the wild-type mice ( 75%), yet was unaltered in the TNF–/– mice. Concomitantly right ventricular hypertrophy was attenuated in the TNF–/– mice (35 ± 5% increase) when compared to wild-type mice (124 ± 6% increase p < 0.001, n 20). Interestingly in both strains the lung wet weights increased to a similar degree in response to hypoxia. In conclusion, our data demonstrate that TNF is an integral autocoid in chronic hypoxia mediated right ventricular hypertrophy. Moreover, additional components of cardiopulmonary remodeling may be regulated by TNF signaling as suggested by the negligible right ventricular systolic pressure response to hypoxia in the absence of TNF.     

Cytogenetische Untersuchungen mit zwei N-substituierten Endoxanabkömmlingen an menschlichen Leukocyten in vitro

Summary Unlike cyclophosphamide (Endoxan^®, Cytoxan^®) N, N, N-tris-(2-chloroethyl)-N,O-propylene phosphoric acid ester diamide and N-(2-chloroethyl)-N-(2-chloroethyl)-N,-O-propylene phosphoric acid ester diamide induced chromosomal aberrations in human leukocytes in vitro. The majority of these lesions consisted of chromatid breaks, acentric fragments, and isochromatid breaks. Infrequently interchanges and ring chromosomes were observed. The percentage of metaphases with chromosomal damage increased exponentially, the mean breakage frequency per metaphase, however, rose approximately linearly with the applied concentration. A possible cleavage of the nitrogen-phosphorus bond and the breakdown of the inactive cyclic forms of the two investigated compounds in vitro is discussed.

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(Direktor: Klinik der Freien Universität Berlin)

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Herrn Professor Dr. Hans Frhr. von Kress zum 65. Geburtstag gewidmet.