Leaf sheath cuticular waxes on bloomless and sparse-bloom mutants of Sorghum bicolor

Leaf sheath cuticular waxes on wild-type Sorghum bicolor were approximately 96% free fatty acids, with the C28 and C30 acids being 77 and 20% of these acids, respectively. Twelve mutants with markedly reduced wax load were characterized for chemical composition. In all of the 12 mutants, reduction in the amount of C28 and C30 acids accounted for essentially all of the reduction in total wax load relative to wildtype. The bm2 mutation caused a 99% reduction in total waxes. The bm4, bm5, bm6, bm7 and h10 mutations caused more than 91% reduction in total waxes, whereas the remaining six mutants, bm9, bm11, h7, h11, h12 and h13, caused between 35 and 78% reduction in total wax load. Relative to wild-type, bm4 caused a large increase in the absolute amount of C22, C24 and C26 acids, and reduction in the C28 and longer acids, suggesting that bm4 may suppress elongation of C26, acyl-CoA primarily. The h10 mutation increased the absolute amounts of the longest chain length acids, but reduced shorter acids, suggesting that h10 may suppress termination of acyl-CoA elongation. The bm6, bm9, bm11, h7, h11, h12 and h13 mutations increased the relative amounts, but not absolute amounts, of longer chain acids. Based on chemical composition alone, it is still uncertain which genes and their products were altered by these mutations. Nevertheless, these Sorghum cuticular wax mutants should provide a valuable resource for future studies to elucidate gene involvement in the biosynthesis of cuticular waxes, in particular, the very-long-chain fatty acids.

Near-isogenic lines of maize differing for glycinebetaine

A series of near-isogenic glycinebetaine-containing and -deficient F8 pairs of Zea mays L. (maize) lines were developed. The pairs of lines differ for alternative alleles of a single locus; the wild-type allele conferring glycinebetaine accumulation is designated Bet1 and the mutant (recessive) allele is designated bet1. The near-isogenic lines were used to investigate whether glycinebetaine deficiency affects the pool size of the glycinebetaine precursor, choline, using a new method for glycinebetaine and choline determination: stable isotope dilution plasma desorption mass spectrometry. Glycinebetaine deficiency in maize was associated with a significant expansion of the free choline pool, but the difference in choline pool size was not equal to the difference in glycinebetaine pool size, suggesting that choline must down-regulate its own synthesis. Consistent with this, glycinebetaine deficiency was also associated with the accumulation of the choline precursor, serine. A randomly amplified polymorphic DNA marker was identified that detects the bet1 allele. In 62 F8 families tested the 10-mer primer 5'-GTCCTCGTAG produced a 1.2-kb polymerase chain reaction product only when DNA from Bet1/bet1 or bet1/bet1 lines was used as template. All 26 homozygous Bet1/Bet1 F8 families tested were null for this marker.

Chemically Induced Cuticle Mutation Affecting Epidermal Conductance to Water Vapor and Disease Susceptibility in Sorghum bicolor (L.) Moench

Analysis of Sorghum bicolor bloomless (bm) mutants with altered epicuticular wax (EW) structure uncovered a mutation affecting both EW and cuticle deposition. The cuticle of mutant bm-22 was about 60% thinner and approximately one-fifth the weight of the wild-type parent P954035 (WT-P954035) cuticles. Reduced cuticle deposition was associated with increased epidermal conductance to water vapor. The reduction in EW and cuticle deposition increased susceptibility to the fungal pathogen Exserohilum turcicum. Evidence suggests that this recessive mutation occurs at a single locus with pleiotropic effects. The independently occurring gene mutations of bm-2, bm-6, bm-22, and bm-33 are allelic. These chemically induced mutants had essentially identical EW structure, water loss, and cuticle deposition. Furthermore, 138 F2 plants from a bm-22 x WT-P954035 backcross showed no recombination of these traits. This unique mutation in a near-isogenic background provides a useful biological system to examine plant cuticle biosynthesis, physiology, and function.

Betaines of alfalfa : characterization by fast atom bombardment and desorption chemical ionization mass spectrometry

Leaf tissue of alfalfa (Medicago sativa L.) was found to contain prolinebetaine, pipecolatebetaine, hydroxyprolinebetaine, and glycinebetaine. As n-butyl esters, these chemical species exhibit molecular cations at mass/charge ratio (m/z) 200, 214, 216, and 174, respectively, when analyzed by fast atom bombardment mass spectrometry. The underivatized betaines exhibit protonated molecular ions at m/z 144, 158, 160, and 118, respectively, when analyzed by desorption chemical ionization mass spectrometry. Extensive (>45-fold) genotypic variation for hydroxyprolinebetaine level was identified in alfalfa. Because a significant inverse correlation between prolinebetaine and hydroxyprolinebetaine levels was observed among 15 alfalfa genotypes evaluated, it is possible that these compounds may be derived from a common intermediate. Birdsfoot trefoil (Lotus corniculatus L.) contained prolinebetaine, but only traces of glycinebetaine, pipecolatebetaine, and hydroxyprolinebetaine. Red clover (Trifolium pratense L.) lacked prolinebetaine, pipecolatebetaine, and hydroxyprolinebetaine, but contained appreciable levels of both glycinebetaine and trigonelline. Trigonelline was not detectable in the leaf tissue of any alfalfa genotype or cultivar evaluated.

Betaine deficiency in maize : complementation tests and metabolic basis

Maize (Zea mays L.) is a betaine-accumulating species, but certain maize genotypes lack betaine almost completely; a single recessive gene has been implicated as the cause of this deficiency (D Rhodes, PJ Rich [1988] Plant Physiol 88: 102-108). This study was undertaken to determine whether betaine deficiency in diverse maize germplasm is conditioned by the same genetic locus, and to define the biochemical lesion(s) involved. Complementation tests indicated that all 13 deficient genotypes tested shared a common locus. One maize population (P77) was found to be segregating for betaine deficiency, and true breeding individuals were used to produce related lines with and without betaine. Leaf tissue of both betaine-positive and betaine-deficient lines readily converted supplied betaine aldehyde to betaine, but only the betaine-containing line was able to oxidize supplied choline to betaine. This locates the lesion in betaine-deficient plants at the choline --> betaine aldehyde step of betaine synthesis. Consistent with this location, betaine-deficient plants were shown to have no detectable endogenous pool of betaine aldehyde.

Kinetics of NH(4) Assimilation in Zea mays: Preliminary Studies with a Glutamate Dehydrogenase (GDH1) Null Mutant

In higher plants it is now generally considered that glutamate dehydrogenase (GDH) plays only a small or negligible role in ammonia assimilation. To test this specific point, comparative studies of (15)NH(4) (+) assimilation were undertaken with a GDH1-null mutant of Zea mays and a related (but not strictly isogenic) GDH1-positive wild type from which this mutant was derived. The kinetics of (15)NH(4) (+) assimilation into free amino acids and total reduced nitrogen were monitored in both roots and shoots of 2-week-old seedlings supplied with 5 millimolar 99% ((15)NH(4))(2)SO(4) via the aerated root medium in hydroponic culture over a 24-h period. The GDH1-null mutant, with a 10- to 15-fold lower total root GDH activity in comparison to the wild type, was found to exhibit a 40 to 50% lower rate of (15)NH(4) (+) assimilation into total reduced nitrogen. Observed rates of root ammonium assimilation were 5.9 and 3.1 micromoles per hour per gram fresh weight for the wild type and mutant, respectively. The lower rate of (15)NH(4) (+) assimilation in the mutant was associated with lower rates of labeling of several free amino acids (including glutamate, glutamine-amino N, aspartate, asparagine-amino N, and alanine) in both roots and shoots of the mutant in comparison to the wild type. Qualitatively, these labeling kinetics appear consistent with a reduced flux of (15)N via glutamate in the GDH1-null mutant. However, the responses of the two genotypes to the potent inhibitor of glutamine synthetase, methionine sulfoximine, and differences in morphology of the two genotypes (particularly a lower shoot:root ratio in the GDH1-null mutant) urge caution in concluding that GDH1 is solely responsible for these differences in ammonia assimilation rate.

Development of two isogenic sweet corn hybrids differing for glycinebetaine content

A hybrid of sweet corn, Zea mays L. (;1720'; Rogers Brothers Seed Co.), was found to be comprised of glycinebetaine-positive and glycinebetaine-deficient individuals in a 1:1 mixture. This phenomenon was traced to segregation for a single, nuclear, dominant gene determining leaf glycinebetaine content within the female inbred parent of this hybrid. Selection for homozygous recessive (glycinebetaine-deficient) and homozygous dominant (glycinebetaine-positive) genotypes of the female inbred parent enabled production of two isogenic versions of hybrid ;1720' differing with respect to a single copy of the dominant allele, by mating these female parent selections with the common homozygous recessive (glycinebetaine-deficient) male parent. These two isogenic hybrids are shown to differ by a factor of 300- to 400-fold in glycinebetaine titer of young expanding leaves of salinized plants, but exhibit no striking differences in the levels of free amino acids or the level of N-methylnicotinic acid (nicotinic acid betaine; trigonelline). The only significant difference between the two hybrids in terms of amino acid composition was found to be in the level of alanine under nonsalinized conditions. The betaine-deficient hybrid exhibited a 14% lower alanine level than the betaine-positive hybrid. Betaine deficiency was not associated with altered stress-induced accumulation of amino acids such as proline, serine, and asparagine plus aspartate, attesting to the high specificity of the genetic difference between these isogenic hybrids with respect to betaine accumulation. This germplasm offers unique opportunities to test whether a single dominant allele determining stress-induced betaine accumulation capacity influences stress resistance in maize.

Genotypic Variation for Glycinebetaine among Public Inbreds of Maize

Screening of a range of public maize (Zea mays L.) inbred lines for glycinebetaine (betaine) content over two growing seasons (1987 and 1988), using fast atom bombardment mass spectrometry, has identified 19 public inbred lines which all exhibit low betaine levels (<100 nanomoles per gram fresh weight). These include common inbreds such as A188, A619, B37, H95, N6, and Oh43. Several inbreds exhibit high betaine levels (3000 to 10000 nanomoles per gram fresh weight); in these strongly betaine-positive inbreds, betaine levels tended to be, on average, 1.38-fold greater in the 1988 growing season presumably in part due to field water deficits experienced during the drought of 1988. Where several different sources of the same inbred line were available (including cytoplasmic male sterile and restored lines of A632, B37, B73, Oh43, and WF9), betaine levels were found to be similar when the inbreds were tested in the same environment. Because W22-R/r-X1 was found to be strongly betaine-positive, it should be possible to map the putative recessive gene(s) determining betaine deficiency to specific chromosome(s) from monosomics resulting from crosses between W22-R/r-X1 and betaine-deficient lines.

Imaging of the nontraumatic acute abdomen

Plain-film radiography of the abdomen is often the first-line imaging modality used for the patient in the ED. It is capable of demonstrating abnormal locations of gas, abnormal viscera, calcifications and foreign material, and skeletal and lower lung pathology. PFR findings may aid in the decision to proceed to other modalities. Contrast studies have a limited role in the ED but may be necessary to diagnose disease inadequately visualized by PFR, as in the case of perforated duodenal ulcer, missed on PFR in approximately 15 per cent of cases. Ultrasound is most useful in the ED for obstetric and gynecologic illness, as well as disorders of the hepatobiliary system. Nuclear medicine studies can be very useful for GI bleeding and inflammatory conditions but may not always be as available or convenient as other modalities. CT has very broad usefulness. Angiography is very useful for locating bleeding sites, especially in the large bowel, and for determination of mesenteric arterial patency in suspected mesenteric ischemia. Finally, MRI, which has enormous potential, is not funded by many third-party payment plans for use in emergencies, and must overcome certain obstacles before it assumes common usage in the ED.

Amino Acid Metabolism of Lemna minor L. : IV. N-Labeling Kinetics of the Amide and Amino Groups of Glutamine and Asparagine

A serious limitation to the use of N(O,S)-heptafluorobutyryl isobutyl amino acid derivatives in the analysis of (15)N-labeling kinetics of amino acids in plant tissues, is that the amides glutamine and asparagine undergo acid hydrolysis to glutamate and aspartate, respectively, during derivatization. This led us to consider an alternative procedure (G Fortier et al. [1986] J Chromatogr 361: 253-261) for derivatization of glutamine and asparagine with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide in pyridine. Gas chromatography-mass spectrometry (electron ionization) yielded fragment ions (M-57) of mass 417 and 431 for the [(14)N]asparagine and [(14)N]glutamine derivatives, respectively, suitable for monitoring unlabeled, single-(15)N- and double-(15)N-labeled amide species from the ion clusters at mass to charge ratio (m/z) 415 to 423 for asparagine, and m/z 429 to 437 for glutamine. From separate analyses of the specific isotope abundance of the amino-N groups of asparagine and glutamine as their N-heptafluorobutyryl isobutyl derivatives, the specific amide-[(15)N] abundance of these amino acids was determined. We demonstrate that this approach to (15)N analysis of the amides can yield unique insights as to the compartmentation of asparagine and glutamine in vivo. The ratios of unlabeled:single-(15)N:double-(15)N-labeled species are highly diagnostic of the relative sizes and turnover of metabolically active and inactive pools of the amides and their precursors. Kinetic evidence is presented to indicate that a significant proportion (approximately 10%) of the free asparagine pool may be metabolically inactive (vacuolar). If the amide group of asparagine is derived exclusively from glutamine-amide, then asparagine must be synthesized in a compartment of the cell in which both glutamine-amide and aspartate are more heavily labeled with (15)N than the bulk pools of these amino acids. This compartment is presumably the chloroplast. The transaminase inhibitor aminooxyacetate is shown to markedly inhibit amino acid synthesis; several amino acid pools accumulated in the presence of aminooxyacetate and [(15)N]H(4) (+) are (14)N-enriched and must be derived primarily from protein turnover.

Preliminary Genetic Studies of the Phenotype of Betaine Deficiency in Zea mays L

Glycinebetaine-deficient inbreds of Zea mays do not exhibit a general deficiency of nitrogenous solutes; the total free amino acid levels of betaine-deficient lines are not significantly less than those of inbreds which exhibit >100-fold higher betaine levels. Betaine-deficient inbreds are characterized by extremely low betaine: total free amino acid ratios (<0.0015). Highly significant correlations are demonstrated between the expected mid-parent and observed betaine:amino acid ratios of 30 hybrids of known pedigree. In 12 hybrids constructed from a betaine-deficient male parent (inbred 1506), the observed betaine:amino acid ratios of the hybrids are proportional to the betaine:amino acid ratios of the female parents (r = 0.83). Two hybrids, 1146 x 1074 and 1146 x 1506, were chosen for further genetic analysis. The common female parent (1146) and inbred 1074 both exhibit betaine:amino acid ratios of 0.090, a value which is approximately 90-fold greater than the betaine:amino acid ratio of inbred 1506. Hybrid 1146 x 1074 exhibits almost exactly twice the betaine:amino acid ratio of hybrid 1146 x 1506. If inbred 1506 is homozygous recessive for a single nuclear gene responsible for the phenotype of betaine deficiency, and if inbreds 1146 and 1074 are homozygous dominant for this allele, then this twofold difference in betaine:amino acid ratio must be associated with the homozygous dominant and heterozygous conditions, respectively, for 1146 x 1074 and 1146 x 1506. Evidence is presented from both greenhouse and field evaluations of F(2) populations of these hybrids that a single nuclear recessive gene is most likely responsible for the phenotype of betaine-deficiency in inbred 1506. Approximately 25% of the F(2) segregants from 1146 x 1506 exhibited extremely low betaine:amino acid ratios (<0.0015), whereas 0% of the F(2) segregants from 1146 x 1074 exhibited this phenotype. The segregation patterns with respect to betaine:amino acid ratio suggest a 1:2:1 segregation ratio for homozygous recessive:heterozygous:homozygous dominant individuals within the 1146 x 1506-F(2) population.

Determination of Betaines by Fast Atom Bombardment Mass Spectrometry : Identification of Glycine Betaine Deficient Genotypes of Zea mays

A rapid, sensitive, and selective method for the determination of betaines is described and discussed. The method entails derivatizing the quaternary ammonium compounds to increase their sensitivity to detection by fast atom bombardment mass spectrometry. Sensitivity of detection increases markedly as the length of the carbon chain of the alcohol used to esterify the betaine carboxylic acid group is increased (C4 > C3 > C2 > C1 > C0). The lower limit of detection of glycine betaine as the n-propyl ester is 0.05 nanomole per microliter of glycerol. Betaine aldehyde can be readily derivatized to the di-n-butyl or di-n-propyl acetal derivatives which exhibit lower limits of detection of about 5 picomoles and 10 picomoles per microliter of glycerol, respectively. Accurate quantification of these compounds is accomplished by the use of deuterium labeled internal standards or quaternary ammonium compound homologs of distinct mass. Methods for the synthesis of these internal standards are reported. Some applications of these methods are illustrated with stable isotope tracer studies on the kinetics of metabolism of choline to betaine aldehyde and glycine betaine in spinach leaf discs, and the identification of several Zea mays genotypes which appear deficient in glycine betaine. Tracer studies with deuterium labeled betaine aldehyde suggest that the deficiency of glycine betaine in one sweet corn hybrid is probably not due to a deficiency in the capacity to oxidize betaine aldehyde.

The traumatized scrotum. Ultrasound evaluation

Testicular salvage rates are improved markedly when surgical correction of a ruptured tunica albuginea is performed within 72 hours after a scrotal injury. The authors studied 11 patients who had suffered various types of blunt or penetrating trauma to the scrotum. The importance of ultrasound for the evaluation of the traumatized scrotum and detection of a testicular rupture is stressed. The spectrum of abnormalities that may be present after a scrotal injury is described.

Measurement of loss and output numerical aperture of optical fiber splices

An ensemble of optical fiber splices has been evaluated to determine how source launching conditions and length of fiber between the source, splice, and detector affect the splice loss and far field output NA. The loss of a splice is strongly dependent upon the energy distribution and NA of the beam at the input of the splice. For the range of NA's considered, the splice loss varied by 0.5 dB. The average NA at the output of the ensemble of splices was greater than its corresponding input NA by as much as 12%. The splice appears to act as a transformer converting the input energy distribution into one at the output that contains a greater amount of its energy in higher order modes. As a consequence of this, the loss of a fiber following the splice in a long transmission path is greater than the loss the fiber would exhibit if measured with steady state excitation conditions.

Delay distortion characteristics of optical fiber splices

The delay distortion characteristics of optical fiber splices are evaluated. Two 1.35-km graded index fibers with different transmission characteristics were each bisected and spliced together to determine how longitudinal and transverse displacement of fibers in a splice affect the delay distortion characteristics of a transmission path. The transmission characteristics of both the optical source and the fibers used play an important role in determining how delay distortion is affected by splice misalignment. The first fiber exhibited a great deal of mode mixing and a very small increase in delay distortion as the fibers were offset in the splice. In contrast, the second fiber exhibited very little mode mixing, but increased markedly in delay distortion as the fibers in the splice were displaced.

Multigroove embossed-plastic splice connector for joining groups of optical fibers

To install and maintain successfully an optical fiber communications system, techniques for splicing individual and groups of optical fibers under field conditions must be developed. In this paper a technique for splicing groups of optical fibers with a one piece multigroove embossed plastic connector is described. Using 132-microm multimode fibers with 94-microm core diameters, the average transmission loss of the splice joints measured was 0.12 dB with a standard deviation of 0.11 dB and a range of loss values from 0.0 dB to 0.53 dB.