Characterization of third chromosome dominant alpha-methyl dopa resistant mutants (Tcr) and their interactions with l(2)amd alpha-methyl dopa hypersensitive alleles in Drosophila melanogaster

In Drosophila melanogaster two alleles at the Third chromosome resistance locus (Tcr; 3-39-6) were isolated in a screen of EMS mutagenized third chromosomes for dominant resistance to dietary alpha-methyl dopa, alpha-MD, a structural analogue of DOPA. Both alleles of Tcr are recessive lethals exhibiting partial complementation. Almost half (48.3%) of the Tcr40/Tcr45 heterozygotes die as embryos but some survive past adult eclosion. Both the embryonic lethal phenotype and the adult phenotype suggest that Tcr is involved in cuticle synthesis. Tcr mutants suppress the lethality of partially complementing alleles at the alpha-MD hypersensitive locus, l(2)amd. The viability of Tcr40/Tcr45, however, is not increased by the presence of a l(2)amd allele. The possibility that the Tcr and l(2)amd mutations reveal a catecholamine metabolic pathway involved in cuticle structure is discussed.     

The Genetics of Dopa Decarboxylase in DROSOPHILA MELANOGASTER I. Isolation and Characterization of Deficiencies That Delete the Dopa-Decarboxylase-Dosage-Sensitive Region and the α-Methyl-Dopa-Hypersensitive Locus

A detailed cytogenetic investigation of 16 overlapping deficiencies in the 36C-40A region on the left arm of the second chromosome (2L) in Drosophila melanogaster is reported. These deficiencies permit a localization of both the dopa-decarboxylase-dosage-sensitive region and the α-methyl-dopa-hypersensitive locus, l(2)amd, to the same region, 37B10-37C7.     

Interactive effects of water stress and xylem-limited bacterial infection on the water relations of a host vine

Xylella fastidiosa, a xylem-limited bacterial pathogen that causes bacterial leaf scorch in its hosts, has a diverse and extensive host range among plant species worldwide. Previous work has shown that water stress enhances leaf scorch symptom severity and progression along the stem in Parthenocissus quinquefolia infected by X. fastidiosa. The objective here was to investigate the mechanisms underlying the interaction of water stress and infection by X. fastidiosa. Using the eastern deciduous forest vine, P. quinquefolia, infection and water availability were manipulated while measuring leaf water potentials (psi(L)), stomatal conductance (g(s)), whole shoot hydraulic conductance (K(h)), per cent xylem embolism, and xylem vessel dimensions. No significant differences in any of the physiological measurements were found between control and infected plants prior to drought. Drought treatment significantly reduced psi(L) and g(s) at all leaf positions throughout the day in late summer in both years of the study. In addition, infection significantly reduced psi(L) and g(s) in the most basal leaf positions in late summer in both years. Whole shoot hydraulic conductance was reduced by both low water and infection treatments. However, per cent embolized vessels and mean vessel diameter were affected by drought treatment only. These results imply that the major effect of infection by X. fastidiosa occurs due to reduced hydraulic conductance caused by clogging of the vessels, and not increased cavitation and embolism of xylem elements. The reduced K(h) caused by X. fastidiosa infection acts additively with the water limitation imposed by Drought stress.     

Analysis of ethanol–glucose mixtures by two microbial sensors: application of chemometrics and artificial neural networks for data processing

Although biosensors based on whole microbial cells have many advantages in terms of convenience, cost and durability, a major limitation of these sensors is often their inability to distinguish between different substrates of interest. This paper demonstrates that it is possible to use sensors entirely based upon whole microbial cells to selectively measure ethanol and glucose in mixtures. Amperometric sensors were constructed using immobilized cells of either Gluconobacter oxydans or Pichia methanolica. The bacterial cells of G. oxydans were sensitive to both substrates, while the yeast cells of P. methanolica oxidized only ethanol. Using chemometric principles of polynomial approximation, data from both of these sensors were processed to provide accurate estimates of glucose and ethanol over a concentration range of 1.0–8.0 mM (coefficients of determination, R²=0.99 for ethanol and 0.98 for glucose). When data were processed using an artificial neural network, glucose and ethanol were accurately estimated over a range of 1.0–10.0 mM (R²=0.99 for both substrates). The described methodology extends the sphere of utility for microbial sensors.     

Selective inhibition of antimycin A-insensitive respiration in Ustilago maydis and Ceratocystis ulmi

Sporidia of Ustilago maydis and conidia of Ceratocystis ulmipossess an antimycin A and azide-tolerant electron transportpathway which apparently diverts electrons to O₂ from some pointon the substrate side of the antimycin A block. The alternatepathway (induced by 0.5 µg/ml antimycin A or 5x10^–4M sodium azide) supports a respiratory rate 1.5–2 timesthat of the normal system, but has a terminal oxidase with alower than normal affinity for O₂. A similarly high respiratoryrate in U. maydis is supported by the normal pathway when uncoupledby 4 µg/ml of 4,5-dichloro-2-trifluoromethylbenzimidazole,but a high affinity for O₂ in this case indicates that the normalterminal oxidase is utilized. Respiration by the normal pathway in both fungi is only slightlyor moderately inhibited by 1.5x10^–3 M benzohydroxamicacid (BHAM) and 5x10^–4 M 8-hydroxyquinoline. The alternatepathway in U. maydis, however, is inhibited as much as 84 and92% respectively by these two compounds, while alternate respirationin C. ulmi can be inhibited as much as 86 and 76% respectively.BHAM, 8-hydroxyquinoline, 2-pyridinethiol-1-oxide, a,a'-dipyridyl,carboxin, and diphenylamine inhibit alternate respiration ata site on the alternate pathway which is not part of the normalelectron transport system. Antimycin A and azide-insensitiverespiration found in U. maydis and C. ulmi closely resemblesinhibitor insensitivity noted in several fungi and some higherplants. Such an alternate respiratory pathway may be an earlystep in the evolution of oxidative phosphorylation. (Received June 27, 1972; )     

Intergenic suppression of the black mutation of Drosophila melanogaster

Summary Five X-linked, recessive alleles were isolated which suppress both the pupal and adult coloration phenotypes of the black mutation. Electron micrographs of shed puparia revealed that the aberrant sclerotization of the black cuticle is also suppressed. Amino acid analysis indicated that suppression is associated with an increased concentration of -alanine, an amino acid known to be deficient in black. The suppressor locus mapped at the tip of the X, to the right of scute, and intragenic complementation was observed among the alleles.     

Pseudo-halogen sugar derivatives: Synthesis and hofmann-rearrangement reactions; 6-O-[2-(N,N-dichlorocarbamoyl)-ethyl]-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose

6-O-[2-(N,N-Dichlorocarbamoyl)ethyl]-1,2:3,4-di- O-isopropylidene-α-d-galactopyranose, a highly reactive pseudo-halogen, was conveniently prepared in 97% yield by addition of sodium hypochlorite to an aqueous acidic (pH <2) solution of 6-O-(2-carbamoylethyl)-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose. Mild, reductive dechlorination or alkaline hydrolysis readily converted the nonpolar N,N-di-chloroamide sugar derivative into the corresponding water-soluble N-monochloroamide form. Hofmann rearrangement of the N-chloroamide group provides a synthetic route to novel binary sugar-derivatives having carbamoyl, ureylene, and allophanoyl linkages. Structural proof for the pseudo-halogens and their Hofmann-rearrangement products was obtained from i.r., ¹H-n.m.r., mass-spectral, and chemical data.