F. G. Wallace

Bio: F. G. Wallace is an academic researcher from University of Minnesota. The author has contributed to research in topics: Flagellate & Kinetoplast. The author has an hindex of 13, co-authored 20 publications receiving 866 citations.

Developmental Stages of Trypanosomatid Flagellates: a New Terminology

Abstract: KNOWLEDGE of the structure and life cycles of the medically important Haemoflagellates of man and lower animals has increased during this century, and it became necessary to define the developmental stages of the leishmanias and trypanosomes in their mammalian and insect hosts. In the course of their cyclical development, flagellates of the genera Leishmania and Trypanosoma pass through stages comparable with those of the monogenetic Trypanosomatidae and so it has been customary to refer to them by names derived from those genera in which the corresponding stages are the most characteristic forms.

A Comparative Study of Kinetoplast Ultrastructure in the Trypanosomatidae

Abstract: SYNOPSIS. The kinetoplast and associated structures in Leishmanial tropica, Trypanosoma cruzi, T. lewisi, Herpeto-inonas culicis, H. muscarum and Crithidia fasciculata have been studied by electron microscopy of thin sections. The kinetoplast appears as a mitochondrion within which are antero-posteriorly oriented anastomosing fibers. In the three species parasitic in vertebrates there is a sharply delimited anterior zone where these fibers are thick and electron-dense. In the insect parasites the fibers form a looser network of approximately uniform density from anterior to posterior. The blepharoplast is the 9-fibered cylinder forming the base of the axoneme and extending below the base of the reservoir. A diffuse mass of electron-dense material surrounding this is the basal granule, visible also with the light microscope. The contractile vacuole appears in electron microsraphs as a clear area associated with Golgi material.

Guidelines for the Description of New Species of Lower Trypanosomatids1

Abstract: Morphological, cultural, and biochemical criteria that have been used in describing lower trypanosomatids, genera Blastocrithidia, Crithidia, Leptomonas, Herpetomonas, Rhynchoidomonas, and Phytomonas are reviewed. Kinetoplast structure, carbohydrate utilization, electrophoretic mobilities of isoenzymes, and kDNA fingerprinting are among the recommended criteria for species differentiation. Temperature, pH, and osmolarity tolerance are useful growth parameters. Generic placement may be assisted by the determination of nitrogenous excretion products and ornithine-arginine cycle enzymes.

Vectors of Plant Parasites of the Genus Phytomonas (Protozoa, Zoomastigophorea, Kinetoplastida)

Abstract: The occurrence of flagellated protozoa as internal parasites in plants was first reported by Lafont in 1909 who found them in the latex of Euphorbia pilulifera in Mauritius (78). From the start, hemipterans were suspected of transmitting these plant parasites. However, as described in this chapter, only in a few instances the vector role of phytophagous bugs has been experimentally evidenced.

A critical review on Chagas disease chemotherapy.

Abstract: In this "Critical Review" we made a historical introduction of drugs assayed against Chagas disease beginning in 1912 with the works of Mayer and Rocha Lima up to the experimental use of nitrofurazone. In the beginning of the 70s, nifurtimox and benznidazole were introduced for clinical treatment, but results showed a great variability and there is still a controversy about their use for chronic cases. After the introduction of these nitroheterocycles only a few compounds were assayed in chagasic patients. The great advances in vector control in the South Cone countries, and the demonstration of parasite in chronic patients indicated the urgency to discuss the etiologic treatment during this phase, reinforcing the need to find drugs with more efficacy and less toxicity. We also review potential targets in the parasite and present a survey about new classes of synthetic and natural compounds studied after 1992/1993, with which we intend to give to the reader a general view about experimental studies in the area of the chemotherapy of Chagas disease, complementing the previous papers of Brener (1979) and De Castro (1993).

Ecology of bats.

Abstract: 1 Roosting Ecology.- 1. Introduction.- 2. Day Roosts.- 2.1. Adaptations for Roosting.- 2.2. Roost Activities and Time Budgets.- 2.3. Roost Fidelity.- 3. Night Roosts.- 3.1. Resting Places.- 3.2. Feeding Perches.- 3.3. Feeding Roosts.- 3.4. Calling Roosts.- 4. Summary.- 5. References.- 2 Ecology of Bat Reproduction.- 1. Introduction.- 2. The Timing of Breeding Seasons.- 2.1. Effect of Variations in Latitude.- 2.2. Rainfall and Its Effect on Food Supply.- 3. Environmental Factors Affecting Specific Reproductive Events.- 3.1. Spermatogenesis and Androgenesis.- 3.2. Estrus and Ovulation.- 3.3. Mating.- 3.4. Delayed Fertilization.- 3.5. Pregnancy and Lactation.- 3.6. Environmental Factors Affecting the Growth and Survival of Young.- 3.7. Puberty and Subsequent Fertility and Fecundity.- 4. Summary.- 5. References.- 3 Growth and Survival of Bats.- 1. Introduction.- 2. Prenatal Growth and Development.- 2.1. Length of Gestation.- 2.2. Time and Synchrony of Parturition.- 2.3. Developmental State at Birth.- 2.4. Litter Size.- 3. Postnatal Growth and Development.- 3.1. Preflight..- 3.2. Postflight.- 4. Survival.- 4.1. Survival Analyses and Results.- 4.2. Survival Determinants.- 4.3. Survival Strategies.- 5. Summary.- 6. References.- 4 Evolutionary Alternatives in the Physiological Ecology of Bats.- 1. Introduction.- 1.1. The Significance of Physiology to the Ecology of Bats.- 1.2. The Significance of Bats for Physiological Ecology.- 2. The Energetics of Bats.- 2.1. Factors Determining the Energy Expenditure of Bats.- 2.2. Ecological Significance of Energetics for Bats.- 2.3. Energy Budgets.- 2.4. The Evolution of Bat Energetics.- 3. The Water Balance of Bats.- 3.1. Kidney Function.- 3.2. Balancing a Water Budget.- 4. Distributional Limits to Bats.- 4.1. Temperate Limits of Tropical Bats.- 4.2. Limits to Distribution in Temperate Bats.- 5. Summary.- 6. References.- 5 Ecological Aspects of Bat Activity Rhythms.- 1. Introduction.- 2. Methods for Recording the Activity of Bats.- 3. Activity Patterns and Timing of Flight Activity under Natural and Controlled Conditions.- 3.1. Activity Patterns.- 3.2. Arousal and Timing of Flight Activity.- 3.3. Light-Sampling Behavior.- 3.4. Influence of External Factors on Activity Rhythms.- 4. Activity Rhythms during Hibernation.- 5. The Endogenous Origin of Bat Activity Rhythms.- 5.1. Circadian Activity Rhythms.- 5.2. Susceptibility of Period to Exogenous Influences.- 5.3. The Phase Response of Circadian Activity Rhythms to Light Pulses.- 5.4. Entrainment of Circadian Rhythms.- 5.5. Range of Entrainment and Speed of Resynchronization.- 6. Ecological Adaptation of Circadian Systems and Evolutionary Aspects.- 7. Summary.- 8. References.- 6 Ecological Significance of Chiropteran Morphology.- 1. Introduction.- 2. The Trophic Niche.- 2.1. Flight and Wing Morphology.- 2.2. Jaw Morphology and Diet.- 2.3. Brain Size.- 2.4. General Morphology and Feeding.- 3. Morphology and Community Structure.- 3.1. Species Packing in Temperate versus Tropical-Bat Communities.- 3.2. Results from Principal-Components Analyses.- 4. Sexual Dimorphism.- 5. Geographic Variation.- 6. Summary.- 7. References.- 7 Echolocation, Insect Hearing, and Feeding Ecology of Insectivorous Bats.- 1. Introduction.- 2. Echolocation Calls.- 2.1. Call Structure.- 2.2. Intensity.- 2.3. Frequency.- 2.4. Pulse Repetition Rates.- 2.5. Harmonics,.- 2.6. Effective Range.- 3. Hearing and Insect Defense.- 4. Responses of Bats to Insect Hearing.- 5. Bats as Specialists.- 5.1. By Time.- 5.2. By Diet.- 5.3. By Foraging Strategy.- 5.4. By Space.- 5.5. By Morphology.- 5.6. As Rapid Feeders.- 6. Other Considerations.- 7. Summary.- 8. References.- 8 Foraging Strategies of Plant-Visiting Bats.- 1. Introduction.- 2. Food Availability and General Foraging Strategies.- 2.1. Food Availability.- 2.2. General Foraging Strategies.- 3. The Foraging Behavior of Plant-Visiting Bats.- 3.1. Food Habits and Diet Breadth.- 3.2. Foraging Behavior.- 3.3. Case Histories.- 4. Summary and General Conclusions.- 5. References.- 9 Coevolution between Bats and Plants.- 1. Introduction.- 2. Coupled Speciation.- 2.1. Evolutionary Origins of Frugivory and Nectarivory.- 2.2. Effects of Bats on Plant Diversification.- 2.3. Coupled Speciation through Coevolution?.- 3. Complex Coadaptations between Bats and Plants.- 3.1. Coadaptations:.- 3.2. Flexibility and Diffuse Coevolution.- 3.3. The Search for Order: Pollination and Dispersal Syndromes.- 4. Ecological Consequences of Bat-Plant Interactions.- 4.1. Variation in Effects.- 4.2. Demographic Effects?.- 4.3. Community Effects.- 5. Does Coevolution "Matter"?.- 6. Summary.- 7. References.- 10 Ecology of Insects Ectoparasitic on Bats.- 1. Introduction.- 2. LifeCycles.- 2.1. Patterns.- 2.2. Food and Feeding.- 2.3. Influence of Climate and Host Hibernation.- 2.4. Causes of Mortality.- 2.5. Number of Generations per Year.- 3. Host Associations.- 3.1. Introduction.- 3.2. Patterns.- 3.3. Reasons.- 4. Host Location and Dispersal.- 4.1. Locomotion.- 4.2. Initial Location and Transference between Hosts.- 5. Behavior on or Near the Host.- 5.1. Introduction.- 5.2. Patterns.- 5.3. Ectoparasites and Host Health.- 6. Population Dynamics.- 6.1. Introduction.- 6.2. Patterns and Limits.- 6.3. Age Structure.- 6.4. Sex Ratio.- 6.5. Changes in Abundance with Space and Time.- 7. Conclusions.- 8. Appendix.- 9. References.- Author Index.- Species Index.

Polymorphism and mitochondrial activity in sleeping sickness trypanosomes

Abstract: surface between the AB corner and the GH corner and are approximately related by the pseudo-dyad axis of symmetry named dyad 1 by Cullis et al. 4• However, the xenon atom in the oc-chain lies nearer the GH corner and thPt in the f3-chain closer to the AB corner. At first it might appear surprising that the xenon positions in the two chains are different from one another, and not the same as in myoglobin. The AB corners of the etand f3-chains differ in both the sequence and tho number of residues they contain, giving rise to structurally different environments. The amino-acid sequences in the GH corners are also different, though here the two chains are of equal length. It should also be noted that the amino-acid sequences of myoglobin• and haemoglobin are quite different. Any change in atomic distribution near a cavity could easily change the electronic interaction with xenon towards an energetically unfavourable state. The exact analysis of the xenon sites will have to await determination of the haemoglobin structure at high resolution. On the basis of Perutz's tentative atomic model of haemoglobin', the nearest neighbours of both xenon atoms are valine, leucine and pheny lalanine. This complex is presumably stabilized, as in myoglobin, by dipoleand quadrupole-induced dipole and quadrupole moments and London interactions. A theoretical investigation by Kittel and Shore8 of xenon polarizability has shown that the quadrupolar (as well as the dipolar) polarizability is particularly high, thus favouring binding in situations like this where one might not otherwise expect it. An analysis of the change in protein-bound water between haemoglobin and the haemoglobin-xenon complex by a microwave t echnique showed an increase of protein-bound water, due to the presence of xenon. Any attempts to demonstrate this directly by X-ray methods must also await the fina l analysis of haemoglobin at high resolution, but changes in the charge distribution caused by xenon atoms located close to the surface of the molecule could account for tho increase in bound water. I thank Dr. M. F. Porutz for his advice and use of his structural data of haemoglobin. This work was supported in part by the U.S. Public Health Service grant NB 03625 to R. M. Featherstone, chairman, Department of Pharmacology, University;,.of California Medical Center, San Francisco. 1 Schoenborn, B. P., Watson, H . C., and Kendrew, ;r, C., Nature, 207, 28 (1965). ' Cullen, S., and Cross, E., Scie11C