Behavioral responses of female oriental fruit flies to the odor of papayas at three ripeness stages in a laboratory flight tunnel (Diptera: Tephritidae)

Behavioral responses of adult female oriental fruit flies, Dacus dorsalisHendel, to the odor of papayas from three ripeness classes were studied using a threechoice flight tunnel bioassay. Laboratoryreared flies were allowed to respond freely to any of three papaya odors (mature green, colorbreak to one-fourth ripe, and one-half to full ripe) emanating from identical (spherical) fruit models. Five behaviors were measured in assessing the fly's relative attraction to the odors (number of landings), arrestment (total fly seconds on sphere), fly-fly interactions on the fruit model (maximum and modal fly density), and acceptance for oviposition (total eggs laid). Females showed no significant difference in total fly landings based on all age classes combined. Significant differences were noted among age classes. Females spent more total time on the sphere and showed a higher maximum density and modal fly density to ripe fruit than to green fruit odors. Ovipositional acceptance of fruit models based on the total number of eggs laid in a sphere was greater in response to the ripefruit odor than to the other two odor classes. Olfactorystimulated behavioral responses of females to the odor of ripe papayas were significantly different from the other ripeness classes for all behaviors at 8 days postemergence and then declined in 11-day-old flies. Behavioral responses were greater during the afternoon than in the morning. Observations of wild oriental fruit flies to papayas in the field indicated a preference for residing on riper fruit. The results of this study are discussed with regard to the role of olfactory inputs generated by the odor of ripening fruit on female attraction and oviposition behavior resulting in infestation of papayas by oriental fruit fly.     

Expression of aChlamydia anticarbohydrate single-chain antibody as a maltose binding fusion protein

A single-chain antibody fragment has been constructed for an antibody that binds to theChlamydia specific carbohydrate structure of the lipopolysaccharide. Single-chain protein was expressed and secreted into the periplasmic space ofE. coli as a fusion protein with the maltose binding protein. The fusion protein was purified in one step by virtue of its ability to bind to maltose. In a sandwich ELISA, the eluted protein boundChlamydia lipopolysaccharide, which demonstrates that the single-chain protein domain will function as part of a fusion protein. The expression of maltose binding fusion proteins into the periplasmic space could be used for production of other single-chain antibodies or protein fragments requiring appropriate folding and disulfide bond formation.     

Oxidation of Lignin-Related Aromatic Alcohols by Cell Suspensions of Methylosinus trichosporium

Cell suspensions of Methylosinus trichosporium oxidized the aromatic alcohols benzyl alcohol, vanillyl alcohol, and veratryl alcohol to the corresponding aldehydes, and with the exception of vanillyl alcohol, the aldehydes were further oxidized to the corresponding aromatic acids. No other transformation was observed, and the methoxyl moieties attached to the aromatic nucleus remained intact. More than 70% of the alcohol oxidized could be accounted for by aldehyde and/or acid. Investigation of the inhibitor kinetics of EDTA or p-nitrophenylhydrazine (specific for NAD⁺-independent methanol dehydrogenase in methylotrophs) on aromatic alcohol oxidation revealed noncompetitive inhibition in which the V_max was decreased but the K_m remained unchanged. The pattern of inhibition of aromatic alcohol oxidation matched that of methanol oxidation, and the K_m values for all of the substrates were similar (12 to 16 mM). The results indicate that the initial step in the oxidation of aromatic alcohols was similar to that for methanol, and because oxidation was incomplete (i.e., only the corresponding aldehyde or acid was produced), there may be some biotechnological advantages in using whole cells of methylotrophs to facilitate aromatic biotransformations.     

Appendix: Synthesis of N-acylglutathione derivatives by dimethylaminopyridine catalysis

A general procedure, involving 4-dimethylaminopyridine-catalysed acylation of the amino groups in the appropriate S-blocked glutathione, is reported for the preparation of N-blocked derivatives of glutathiones.     

Ultracytochemistry of cholera-toxin binding sites in ciliary processes

Summary Cholera toxin reduces the rate of formation of aqueous humor in concentrations (10^–11 M) that do not disturb the morphology of the aqueoushumor forming epithelial cells of the ciliary processes of the rabbit eye. The search for an endogenous mediator of aqueous-humor formation comparable to cholera toxin in its mode of operation prompted us to map the distribution of cell surface receptors for cholera toxin in the ciliary processes of the eyes of rabbits. Cytochemical studies were carried out with the use of conjugates of cholera toxin to fluorescein isothiocyanate (CT-FITC) and to horseradish peroxidase (CT-HRP), and of the B subunit of cholera toxin to horseradish peroxidase (B-HRP). Multiple fluorescent CT-FITC binding sites were observed on the outer nonpigmented epithelial layer near the crests of the processes. Processes incubated with CT-HRP in vitro showed surface staining of 30–40% of the nonpigmented epithelial cells. A prominent reaction product was observed along the basal and lateral plasma membranes of these cells. In vivo studies carried out after arterial infusion of B-HRP showed a reproducible dense reaction product between the apical surfaces of the pigmented epithelium (PE) and of the nonpigmented epithelium (NPE) facing each other. Aggregations of reaction product were observed with the electron microscope in the extracellular space between the apices of PE and NPE. The apical plasma membrane of the endothelium of the blood vessels near the crests of the ciliary processes was stained after either in vivo or in vitro exposure to peroxidase conjugates. These findings indicate that the cell-surface receptors which mediate the action of cholera toxin on aqueous humor formation are very likely localized in the apical plasma membranes of the epithelium of the ciliary processes.Supported in part by USPHS grant # EY-00237, the Connecticut Lions Eye Research Foundation, Inc., and Research to Prevent Blindness, Inc.     

Complete moles have paternal chromosomes but maternal mitochondrial DNA

Summary Complete hydatidiform moles contain only paternal chromosomes. To learn more of their origin, we used restriction endonuclease site polymorphisms found in the parental mitochondrial DNAs to demonstrate that moles contain exclusively maternal mitochondrial DNA. Thus, moles must arise from the fusion of one or two sperm with a mature but anucleate ovum.     

Maternal care in Gargaphia solani (Hemiptera: Tingidae)

We investigated the extent to which maternal behaviour exists in the lacebug Gargaphia solani as well as the adaptive relevance of maternal behaviour to predation, interspecific competition, feeding facilitation, and environmental heterogeneity. G. solani females aggressively defend their progeny against predators until maturity but provide no assistance in feeding, aggregating, or locating resources. In the absence of predators, nymphs suffer no ill effects if raised without their mother, but when nymphs are orphaned in normal field conditions only 3% survive to maturity. Such strong selection has given rise to maternal defensive behaviour that enables Gargaphia females to defend their progeny against predators.     

Localization of unassembled subunits of the mitochondrial ATPase in an assembly-defective yeast nuclear mutant

The yeast nuclear mutant, pet 936, has previously been shown to be defective in the assembly of a functional mitochondrial ATPase (Todd, R. D., McAda, P. C., and Douglas, M. G. (1979) J. Biol. Chem. 254, 11134-11141). In the present report, trypsin degradation and subunit-specific antibody binding have been used to localize subunits 1, 2, and 3 external to or associated with the outer aspect of the inner mitochondrial membrane in the mutant strain. A similar population of unassembled subunits was found in the parental strain as well. Isotope dilution experiments are compatible with those unassembled subunits being normal intermediates in the assembly pathway of the ATPase complex which are blocked from transport across the inner mitochondrial membrane in the mutant, pet 936.