William Trager: An Appreciation

SYNOPSIS. Additional information on host interactions with trypanosomatid membranes was obtained from studies of a monomorphic strain of Trypanosoma brucei harvested at peak parasitemia from intact and lethally irradiated rats. Pellets of trypanosomes were fixed briefly in glutaraldehyde and processed for thin section electron microscopy or freeze-cleave replicas. Observations of sectioned material facilitated orientation and comparison of details seen in replicas. Fracture faces of cell body and flagellar membranes as well as 3-dimensional views of the nuclear membrane were studied. Cell body membranes of 80% of the organisms from intact rats contained random arrays of intramembranous particles (IMP). Aggregated clusters of particles appeared on the fracture faces of 20% of the trypanosomes. Some of these membranes had nonrandomly distributed particles aligned in distinct rows on the outer fracture face of both cell body and flagellum. Many inner face fractures of the cell body membranes had a particle arrangement similar to the longitudinal alignment of cytoskeletal microtubules. No aggregated particle distribution was seen in membranes of trypanosomes harvested from lethally irradiated rats. Replicas of trypanosome pellets also had plasmanemes as a series of attached, empty, coated membrane vesicles. These structures were found in close association with, as well as widely separated from the parasites. The shedding of these vesicles and the variation of particles in cell body membranes are discussed in light of antibody-induced architectural and antigenic changes in surface properties of trypanosomatids. The convex face of the inner membrane of the nucleus also is covered with randomly arrayed particles. More IMP were observed on the inner than on the outer nuclear membranes. Images of nuclear pores were also seen. The importance of these structures in drug and developmental studies of trypanosomes is discussed. On fracture faces of the flagellar membrane there were miniature maculae adherentes, unique to the inner fracture face and occurring only at regions of membrane apposition between cell body and flagellum. Each cluster of particles exposed by the freeze-cleave method corresponds to an electron-dense plaque seen in thin section images. However, because of a unique fracture pattern, these plaques were not revealed on the apposing body membranes, as illustrated in thin sectioned organisms.     

Pentamidine Transport and Sensitivity in brucei-Group Trypanosomes*

SYNOPSIS. Sensitivity to pentamidine of bloodstream forms and culture forms of Trypanosoma brucei brucei, strains of this subspecies, and strains of T. brucei rhodesiense characteristically differs in vitro. Analyses of transport parameters for pentamidine uptake in these organisms show differences that correspond with drug sensitivity. Long slender bloodstream forms of T. b. brucei have a high affinity for the drug and high rates of uptake as indicated by K_m and V_max values for [³H]pentamidine transport. Although pentamidine and stilbamidine resistance is associated with dyskinetoplasty. this condition does not itself confer resistance to pentamidine nor does it affect pentamidine transport. However, drug-resistant strains show lower rates for pentamidine transport as does T. b. rhodesiense, which is characteristically less sensitive to the drug. Of all the forms and strains studied, procyclic trypomastigotes were least sensitive to pentamidine and had a remarkable ability to exclude the drug.     

Trypanosoma lewisi Infections in Normal Rats and in Rats Treated with Dexamethasone

SYNOPSIS. Administration of dexamethasone to rats infected with Trypanosoma lewisi resulted in the development of exceedingly large populations of trypanosomes which were fatal to their hosts. The elevated levels of parasitemia in treated rats early in infections were thought not to be a result of an increased reproductive rate. However, trypanosomes in treated rats 2 days postinfection did have a higher coefficient of variation in total length and a greater percentage of dividing forms than those observed from infected rats which were not given the drug. The course of infection may be markedly altered not only in intensity but also in length by this corticosteroid. It is suggested that dexamethasone administered at the levels recorded to rats infected with T. lewisi inhibits the production of ablastin and trypanocidal antibodies.     

Effect of malformin on the major constituents of Phaseolus vulgaris

Malformin inhibits wet and dry weight, nitrogen accumulation,and cell wall, RNA, DNA and protein synthesis in Phaseolus vulgaris.The relative proportion of dry matter and nitrogen in malformedtissues is increased in the ethanol soluble fraction and decreasedin the residue remaining after hydrolysis with 0.5 N HCl. Inhibitionof cell wall and protein synthesis was generally greater thaninhibition of nitrogen accumulation and RNA and DNA synthesis.The effects of malformin on the composition of P. vulgaris aresimilar to alterations in composition reported for ethylene,and opposite to those reported for gibberellic acid. ¹This research was supported by grant GB-7158 from the NationalScience Foundation and grant E-146-F from the American CancerSociety. ²Journal Paper No. 3509 of the Purdue Agricultural ExperimentStation. (Received October 23, 1968; )     

Comparison of different insecticides and fabrics for anti-mosquito bednets and curtains

Abstract. Various formulations of six insecticides (a carbamate and five pyrethroids), were impregnated into bednets and curtains made from cotton, polyester, polyethylene or polypropylene fabric. For bioassays of insecticidal efficacy, female Anopheles gambiae mosquitoes were made to walk on the fabrics for 3 min and mortality was scored after 24 h. The main concentrations tested were: bendiocarb 400 mg/m², cyfluthrin 30–50 mg/m², deltamethrin 15–25 mg/m², etofenprox 200 mg/m², lambda-cyhalothrin 5–15 mg/m² and permethrin 200–500 mg/m². Field trials in Tanzania used experimental huts (fitted with verandah traps) entered by wild free-flying Anopheles gambiae, An. funestus and Culex quinquefasciatus mosquitoes. Results of testing the impregnated fabrics in experimental huts showed better personal protection provided by bednets than by curtains. Permethrin cis:trans isomer ratios 25:75 and 40:60 were equally effective, and the permethrin rate of 200 mg/m² performed as well as 500 mg/m². Bioassay data emphasized the prolonged insecticidal efficacy of lambda-cyhalothrin deposits, except on polyethylene netting. Most of the impregnated nets (including the ‘Olyset’ net with permethrin incorporated during manufacture of the polyethylene fibre) and an untreated intact net performed well in preventing both Anopheles and Culex mosquitoes from feeding on people using them overnight in the experimental huts. Anopheles showed high mortality rates in response to pyrethroid-treated nets, but only bendiocarb treated curtains killed many Culex. Holed nets treated with either cyfluthrin (5 EW formulation applied at the rate of 50 mg a.i./m²) or lambda-cyhalothrin (2.5 CS formulation at 10 mg a.i./m²) performed well after 15 months of domestic use. Treatment with deltamethrin SC or lambda-cyhalothrin CS at the very low rate of 3 mg/m² gave good results, including after washing and re-treatment.     

The Extraction and Separation of Barley Glutelins and their Relationship to Other Endosperm Proteins

Procedures are described for the extraction of unmodified andalkylated barley glutelin fractions and their subsequent separationby sodium dodecyl sulphate-polyacrylamide gel electrophoresis.The resulting separations are considerably clearer and sharperthan those previously published. One major polypeptide is presentin the salt-soluble and glutelin fractions in varying proportionsdepending on whether or not the salt-soluble fraction is extractedin the presence of a reducing agent. There is also variationin the amount of contaminating hordein polypeptides in the glutelinsand this appears to depend not only on the conditions used toextract hordein but also those used to extract the salt-solublefraction. Finally, variation in the glutelin pattern also occurswhen different denaturing agents or reducing agents are used. ¹ Visiting Scientist, permanent address: U.S. Department ofAgriculture, Science and Education Administration, AgriculturalResearch, Dept. of Agronomy Univ. of illinois, 1102 S. GoodwinAve., Urbana, IL 61801, USA.     

Assessment of Management Techniques to Reduce Woodpecker Damage to Homes

Abstract: Woodpecker damage to homes and buildings is a widespread and locally severe problem in vertebrate pest control. Woodpeckers may cause an average of $300 (United States currency) in damage to affected houses, resulting in millions of dollars of property damage annually in the United States. However, there is no known, practical, consistently effective technique to prevent woodpecker damage. We tested the effectiveness of 6 woodpecker control techniques available commercially, used anecdotally by homeowners, and recommended by wildlife specialists in different Cooperative Extension publications. These deterrents included Prowler Owls, Irri-Tape^TM, the Bird Pro Sound System, Scare-Eyes (all manufactured by Bird-X, Inc., Chicago, IL), suet feeders, and roost boxes. We conducted our study in late spring and autumn during August 2003 through December 2004 in the Town of Ithaca, Tompkins County, New York, USA. We evaluated 16 homes with active woodpecker damage, and visited each house about 3 times per week to determine a rate of new woodpecker holes per day. We then placed a deterrent at the house and monitored the rate of new holes per day. Although none of the deterrents that we tested was completely successful in keeping woodpeckers from creating new holes in house siding, homes where Irri-Tape was installed exhibited the greatest reduction in woodpecker damage. Avoiding earth-tone stain and paint colors may be the best long-term solutions for preventing woodpecker damage in wooded areas. Homeowners should avoid using natural-colored stains, as brightly painted houses (white, light blue, pastels) were less likely to attract woodpeckers.     

Inhibition of crossed caudal interneurons by lateral interneurons in lamprey spinal cord during fictive locomotion

Templates of the membrane potential profiles from lateral (LI) interneurons and motoneurons during glutamate- and N-methyl-D-aspartate (NMDA)-induced fictive locomotion showed pronounced plateau phases. In contrast, crossed caudal (CC) interneurons had a less obvious and steeper plateau region that was followed by a clear notch coinciding with the end of the lateral interneuron plateau phase. These results indicate a significant inhibitory input from LI to CC interneurons.     

Discovery of the bot fly collection of Bracy Clark,with designation of lectotypes in Cuterebra

The story of the discovery and evaluation of an old bot fly collection as the long lost Bracy Clark collection is recounted. Clark's publications and the specimens are collated in detail. The bot material is listed, and lectotypes are designated for four species of North American Cuterebra.