The dynamics of interactions between Plasmodium and the mosquito: a study of the infectivity of Plasmodium berghei and Plasmodium gallinaceum, and their transmission by Anopheles stephensi, Anopheles gambiae and Aedes aegypti

Knowledge of parasite-mosquito interactions is essential to develop strategies that will reduce malaria transmission through the mosquito vector. In this study we investigated the development of two model malaria parasites, Plasmodium berghei and Plasmodium gallinaceum, in three mosquito species Anopheles stephensi, Anopheles gambiae and Aedes aegypti. New methods to study gamete production in vivo in combination with GFP-expressing ookinetes were employed to measure the large losses incurred by the parasites during infection of mosquitoes. All three mosquito species transmitted P. gallinaceum; P. berghei was only transmitted by Anopheles spp. Plasmodium gallinaceum initiates gamete production with high efficiency equally in the three mosquito species. By contrast P. berghei is less efficiently activated to produce gametes, and in Ae. aegypti microgamete formation is almost totally suppressed. In all parasite/vector combinations ookinete development is inefficient, 500-100,000-fold losses were encountered. Losses during ookinete-to-oocyst transformation range from fivefold in compatible vector parasite combinations (P. berghei/An. stephensi), through >100-fold in poor vector/parasite combinations (P. gallinaceum/An. stephensi), to complete blockade (>1,500 fold) in others (P. berghei/Ae. aegypti). Plasmodium berghei ookinetes survive poorly in the bloodmeal of Ae. aegypti and are unable to invade the midgut epithelium. Cultured mature ookinetes of P. berghei injected directly into the mosquito haemocoele produced salivary gland sporozoites in An. stephensi, but not in Ae. aegypti, suggesting that further species-specific incompatibilities occur downstream of the midgut epithelium in Ae. aegypti. These results show that in these parasite-mosquito combinations the susceptibility to malarial infection is regulated at multiple steps during the development of the parasites. Understanding these at the molecular level may contribute to the development of rational strategies to reduce the vector competence of malarial vectors.

Conservation of the expression of Dll, en, and wg in the eye-antennal imaginal disc of stalk-eyed flies

We studied the developmental basis of exaggerated eye span in two species of stalk-eyed flies (Cyrtodiopsis dalmanni and Sphyracephala beccarn). These flies have eyes laterally displaced at the end of eyestalks, and males have greatly exaggerated eye span, which they use as a sexual display. To investigate eye span development we have compared eye-antennal disc morphology and the expression of three key regulator genes of Drosophila head development, Distal-less (Dll), engrailed (en), and wingless (wg), in the stalk-eyed flies and Drosophila. We found great similarity in the basic division of the disc into anterior-antennal and posterior-eye portions and in the general patterning of Dll, en, and wg. Unexpectedly, our results showed that although the eye and antenna are adjacent in adult stalk-eyed flies, their primordia are physically separated by the presence of an intervening region between the anterior and posterior portions of the disc. This region is absent from Drosophila eye-antennal discs. We chose two stalk-eyed fly species that differed in the degree of eye-stalk exaggeration but surprisingly we found no corresponding difference in the size of the en-wg expression domains that mark the boundaries of the dorsal head capsule primordia. In summary, our expression data establish the regional identity of the eye-antennal disc and provide a framework from which to address the developmental genetics of hypercephaly.

Genetic variation for preadult viability in Drosophila melanogaster

The extent of genetic variation in fitness and its components and genetic variation's dependence on environmental conditions remain key issues in evolutionary biology. We present measurements of genetic variation in preadult viability in a laboratory-adapted population of Drosophila melanogaster, made at four different densities. By crossing flies heterozygous for a wild-type chromosome and one of two different balancers (TM1, TM2), we measure both heterozygous (TM1/+, TM2/+) and homozygous (+/+) viability relative to a standard genotype (TM1/TM2). Forty wild-type chromosomes were tested, of which 10 were chosen to be homozygous viable. The mean numbers produced varied significantly between chromosome lines, with an estimated between-line variance in log(e) numbers of 0.013. Relative viabilities also varied significantly across chromosome lines, with a variance in log(e) homozygous viability of 1.76 and of log(e) heterozygous viability of 0.165. The between-line variance for numbers emerging increased with density, from 0.009 at lowest density to 0.079 at highest. The genetic variance in relative viability increases with density, but not significantly. Overall, the effects of different chromosomes on relative viability were remarkably consistent across densities and across the two heterozygous genotypes (TM1, TM2). The 10 lines that carried homozygous viable wild-type chromosomes produced significantly more adults than the 30 lethal lines at low density and significantly fewer adults at the highest density. Similarly, there was a positive correlation between heterozygous viability and mean numbers at low density, but a negative correlation at high density.

Temperature shock during development fails to increase the fluctuating asymmetry of a sexual trait in stalk-eyed flies

The fluctuating asymmetry (FA) of bilateral traits is claimed to be a general indicator of environmental stress. Exaggerated sexual ornaments are thought to show elevated levels of FA and a greater response to stress than other traits. Previous work with stalk-eyed flies (Cyrtodiopsis dalmanni) has shown that the FA of the sexual trait (male eye stalks), wing length and wing width were unaffected by a continually applied food stress. Here we tested whether a transient stress (24-h heat shock at 31 degrees C during development) affected the FA of these traits. A second experiment tested the combined stresses of transient heat shock at 31 degrees C with continuous exposure to desiccation. In each experiment, temperature shock reduced the trait size, confirming that the treatments were stressful. However, stress had no effect on the FA of individual traits or the FA summed across all traits. Exposure to the combined stresses significantly elevated mortality and reduced trait size compared to the single-stress regime. However, FA did not differ significantly between flies from the two experiments. We found no evidence that FA in sexual and non-sexual traits reflects transient stress during the development of C. dalmanni.

Inbreeding changes the shape of the genetic covariance matrix in Drosophila melanogaster

The pattern of genetic covariation among traits (the G matrix) plays a central role in determining the pattern of evolutionary change from both natural selection and random genetic drift. Here we measure the effect of genetic drift on the shape of the G matrix using a large data set on the inheritance of wing characteristics in Drosophila melanogaster. Fifty-two inbred lines with a total of 4680 parent-offspring families were generated by one generation of brother-sister mating and compared to an outbred control population of 1945 families. In keeping with the theoretical expectation for a correlated set of additively determined traits, the average G matrix of the inbred lines remained proportional to the outbred control G matrix with a proportionality constant approximately equal to (1 - F), where F is the inbreeding coefficient. Further, the pattern of covariance among the means of the inbred lines induced by inbreeding was also proportional to the within-line G matrix of the control population with a constant very close to the expectation of 2F. Although the average G of the inbred lines did not show change in overall structure relative to the outbred controls, separate analysis revealed a great deal of variation among inbred lines around this expectation, including changes in the sign of genetic correlations. Since any given line can be quite different from the outbred control, it is likely that in nature unreplicated drift will lead to changes in the G matrix. Thus, the shape of G is malleable under genetic drift, and the evolutionary response of any particular population is likely to depend on the specifics of its evolutionary history.

The effect of transient food stress on female mate preference in the stalk-eyed fly Cyrtodiopsis dalmanni

The effect of transient nutritional stress (sucrose culture medium) on female mate preference was investigated in the stalk-eyed fly Cyrtodiopsis dalmanni. Two experimental treatments were run in parallel. In the first, female preference was initially tested on corn (standard medium) and subsequently on sucrose (novel medium). In the second, female preference was tested in the reverse order: sucrose then corn. Females fed on corn had stronger preferences for large-eyespan males than females fed on sucrose. Female age, experience or the order of exposure to culture media had no effects on the strength of preference. An additional experiment demonstrated that the sucrose diet reduced the number of developing and mature eggs. We discuss the adaptive significance of changes in female preference due to transient nutritional stress, and the effect of changes in female preference on the strength of sexual selection.

Selection on age at reproduction in Drosophila melanogaster: female mating frequency as a correlated response

We examined the effect of selection for age at reproduction on female mating frequency and fertility in female Drosophila melanogaster. Selection for increased age at reproduction (and hence increased lifespan) resulted in higher late life female mating frequencies, while females selected for younger ages at reproduction showed increased early life mating frequencies. These results indicate that the response to selection on age at reproduction has involved changes in the scheduling of female reproductive behavior.

Discovery of novel p-arylthio cinnamides as antagonists of leukocyte function-associated antigen-1/intracellular adhesion molecule-1 interaction. 1. Identification of an additional binding pocket based on an anilino diaryl sulfide lead

The interaction between leukocyte function-associated antigen-1 (LFA-1), a member of the beta(2)-integrin family of adhesion molecules, and intracellular adhesion molecule ICAM-1 (cd54) is thought to play a critical role in the inflammatory process. On the basis of an anilino diaryl sulfide screening lead 1, in combination with pharmacophore analysis of other screening hits, we have identified an adjacent binding pocket. Subsequently, a p-ethenylcarbonyl linker was discovered to be optimal for accessing this binding site. Solution-phase parallel synthesis enabled rapid optimization of the cinnamides for this pocket. In conjunction with fine-tuning of the diaryl substituents, we discovered a novel series of potent, nonpeptide inhibitors of LFA-1/ICAM-1 interaction, exemplified by A-286982 (28h), which has IC(50) values of 44 and 35 nM in an LFA-1/ICAM-1 binding assay and LFA-1-mediated cellular adhesion assay, respectively.

Condition-dependent signalling of genetic variation in stalk-eyed flies

Handicap models of sexual selection predict that male sexual ornaments have strong condition-dependent expression and this allows females to evaluate male genetic quality. A number of previous experiments have demonstrated heightened condition-dependence of sexual ornaments in response to environmental stress. Here we show that genetic variation underlies the response to environmental stress (variable food quality) of a sexual ornament (male eye span) in the stalk-eyed fly Cyrtodiopsis dalmanni. Some male genotypes develop large eye span under all conditions, whereas other genotypes progressively reduce eye span as conditions deteriorate. Several non-sexual traits (female eye span, male and female wing length) also show genetic variation in condition-dependent expression, but their genetic response is entirely explained by scaling with body size. In contrast, the male sexual ornament still reveals genetic variation in the response to environmental stress after accounting for differences in body size. These results strongly support the hypothesis that female mate choice yields genetic benefits for offspring.

Synaptotagmin VII regulates Ca(2+)-dependent exocytosis of lysosomes in fibroblasts

Synaptotagmins (Syts) are transmembrane proteins with two Ca(2+)-binding C(2) domains in their cytosolic region. Syt I, the most widely studied isoform, has been proposed to function as a Ca(2+) sensor in synaptic vesicle exocytosis. Several of the twelve known Syts are expressed primarily in brain, while a few are ubiquitous (Sudhof, T.C., and J. Rizo. 1996. Neuron. 17: 379-388; Butz, S., R. Fernandez-Chacon, F. Schmitz, R. Jahn, and T.C. Sudhof. 1999. J. Biol. Chem. 274:18290-18296). The ubiquitously expressed Syt VII binds syntaxin at free Ca(2+) concentrations ([Ca(2+)]) below 10 microM, whereas other isoforms require 200-500 microM [Ca(2+)] or show no Ca(2+)-dependent syntaxin binding (Li, C., B. Ullrich, Z. Zhang, R.G.W. Anderson, N. Brose, and T.C. Sudhof. 1995. Nature. 375:594-599). We investigated the involvement of Syt VII in the exocytosis of lysosomes, which is triggered in several cell types at 1-5 microM [Ca(2+)] (Rodríguez, A., P. Webster, J. Ortego, and N.W. Andrews. 1997. J. Cell Biol. 137:93-104). Here, we show that Syt VII is localized on dense lysosomes in normal rat kidney (NRK) fibroblasts, and that GFP-tagged Syt VII is targeted to lysosomes after transfection. Recombinant fragments containing the C(2)A domain of Syt VII inhibit Ca(2+)-triggered secretion of beta-hexosaminidase and surface translocation of Lgp120, whereas the C(2)A domain of the neuronal- specific isoform, Syt I, has no effect. Antibodies against the Syt VII C(2)A domain are also inhibitory in both assays, indicating that Syt VII plays a key role in the regulation of Ca(2+)-dependent lysosome exocytosis.

The variance in inbreeding depression and the recovery of fitness in bottlenecked populations

Theoretical analyses of inbreeding suggest that following an increased degree of inbreeding there may be a temporary recovery of fitness, because of selection either within or among inbred lineages. This is possible because selection can act more efficiently to remove deleterious alleles given the greater homozygosity of such populations. If common, recovery of fitness following inbreeding may be important for understanding some evolutionary processes and for management strategies of remnant populations, yet empirical evidence for such recovery in animals is scant. Here we describe the effects of single-pair population bottlenecks on a measure of fitness in Drosophila melanogaster. We compared a large number of families from each of 52 inbred lines with many families from the outbred population from which the inbred lineages were derived. Measures were made at the third and the 20th generations after the bottleneck. In both generations there was, on average, substantial inbreeding depression together with a highly significant variance among the inbred lines in the amount of fitness reduction. The average fitness of inbred lines was correlated across generations. Our data provide evidence for the possibility of recovery of fitness at two levels, because (i) the average fitness reduction in the F20 generation was significantly less than in the F3 generation, which implies that selection within lines has occurred, and (ii) the large variance in inbreeding depression among inbred lines implies that selection among them is possible. The high variance in inbreeding depression among replicate lines implies that modes of evolution which require a low level of inbreeding depression can function at least in a fraction of inbred populations within a species and that results from studies with low levels of replication should be treated with caution.

An assessment of the health communication job market across multiple types of organizations

This study seeks to answer three questions: (1) What is the employment outlook for health communication practitioners? (2) What specialized knowledge and skills should a competent health communication practitioner possess? and (3) How much academic training or professional experience is necessary to become a competent health communication practitioner? To this end, 104 employers of health communication practitioners, representing different types of large, medium, and small companies and organizations from various regions of the United States, were interviewed by telephone. The interview protocol was based on nine core health communication responsibilities identified by a working group of health communication academicians and practitioners. The study suggests a positive employment outlook, where those seeking jobs in health communication before the year 2000 could enjoy varied job opportunities in the wake of an anticipated moderate expansion in the field. Those with 1 to 10 years of experience are most in demand. While an undergraduate degree provides an academic background to perform most responsibilities, for six of the nine core responsibilities an advanced degree was preferred by at least one-third of respondents.

Human immune responses to the UK human anthrax vaccine

The IgG anti-protective antigen subclass antibody response of individuals who had been infected with anthrax was compared with that of healthy individuals immunized with the UK licensed anthrax vaccine. The predominant subclass in both groups was IgG1. In addition, IgG3 was seen in convalescent serum while vaccinees produced IgG2, IgG3 and IgG4 subclass. The significance of these results is discussed. Further work is required to determine the role of antibodies in mediating protective immunity in man.

Immune correlates of protection against anthrax

Bacillus anthracis protective antigen (PA) has been produced from a recombinant B. subtilis and its efficacy, when combined with the Ribi adjuvant (MPL-TDW-CWS) or alhydrogel, has been compared with that of the licensed UK human vaccine, in guinea pigs challenged with aerosolized Ames strain spores. Recombinant PA combined with the Ribi adjuvant performed as well as PA from B. anthracis cultures in previous reports (Ivins & Welkos 1986; Ivins et al. 1990; Turnbull et al. 1991; Jones et al. 1996; McBride et al. 1998) giving protection in 100% of animals exposed to the highest challenge dose of the Ames strain of B. anthracis that can be administered practically (retained lung doses of approximately 106 spores). In attempts at identifying markers of protection in immunized individuals, rPA in combination with the Ribi adjuvant induced a marker IgG2 response in guinea pigs with no significant differences in IgG1 levels when compared with other vaccine formulations (McBride et al. 1998). In BALBc mice, rPA with the Ribi adjuvant induced a higher IgG2a response compared with rPA with anhydrogel and the human vaccine. To examine the role of anti-PA-specific antibodies in protection, guinea pig sera is being passively transferred into guinea pigs and SCID mice, followed by protection. Similarly, B- and T-lymphocytes from immunized BALB/c mice are being separately and passively transferred into SCID mice with subsequent challenge. The neutralizing ability of the PA-specific antibodies is being studied using an in vitro macrophage lysis assay.

Correlated responses to selection on body size in Drosophila melanogaster

Correlated responses to artificial selection on body size in Drosophila melanogaster were investigated, to determine how the changes in size were produced during development. Selection for increased thorax length was associated with an increase in larval development time, an extended growth period, no change in growth rate, and an increased critical larval weight for pupariation. Selection for reduced thorax length was associated with reduced growth rate, no change in duration of larval development and a reduced critical larval weight for pupariation. In both lines selected for thorax length and lines selected for wing area, total body size changed in the same direction as the artificially selected trait. In large selection lines of both types, the increase in size was achieved almost entirely by an increase in cell number, while in the small lines the decrease in size was achieved predominantly by reduced cell size, and also by a reduction in cell number. The implications of the results for evolutionary-genetic change in body size in nature are discussed.

Aromatase overexpression and breast hyperplasia, an in vivo model--continued overexpression of aromatase is sufficient to maintain hyperplasia without circulating estrogens, and aromatase inhibitors abrogate these preneoplastic changes in mammary glands

To test directly the role of breast-tissue estrogen in initiation of breast cancer, we have developed the aromatase-transgenic mouse model and demonstrated for the first time that increased mammary estrogens resulting from the overexpression of aromatase in mammary glands lead to the induction of various preneoplastic and neoplastic changes that are similar to early breast cancer. Continued overexpression of aromatase that leads to increased breast-tissue estrogen contributes to a number of epigenetic changes in mammary tissue such as alteration in the regulation of genes involved in apoptosis, activation of genes involved in cell cycle and cell proliferation, and activation of a number of growth factors. Our current studies show aromatase overexpression is sufficient to induce and maintain early preneoplastic and neoplastic changes in female mice without circulating ovarian estrogen. Preneoplastic and neoplastic changes induced in mammary glands as a result of aromatase overexpression can be completely abrogated with the administration of the aromatase inhibitor, letrozole. Consistent with complete reduction in hyperplasia, we have also seen downregulation of estrogen receptor and a decrease in cell proliferation markers, suggesting aromatase-induced hyperplasia can be treated with aromatase inhibitors. Our studies demonstrate that aromatase overexpression alone, without circulating estrogen, is responsible for the induction of breast hyperplasia and these changes can be abrogated using aromatase inhibitors.

The changes in genetic and environmental variance with inbreeding in Drosophila melanogaster

We performed a large-scale experiment on the effects of inbreeding and population bottlenecks on the additive genetic and environmental variance for morphological traits in Drosophila melanogaster. Fifty-two inbred lines were created from the progeny of single pairs, and 90 parent-offspring families on average were measured in each of these lines for six wing size and shape traits, as well as 1945 families from the outbred population from which the lines were derived. The amount of additive genetic variance has been observed to increase after such population bottlenecks in other studies; in contrast here the mean change in additive genetic variance was in very good agreement with classical additive theory, decreasing proportionally to the inbreeding coefficient of the lines. The residual, probably environmental, variance increased on average after inbreeding. Both components of variance were highly variable among inbred lines, with increases and decreases recorded for both. The variance among lines in the residual variance provides some evidence for a genetic basis of developmental stability. Changes in the phenotypic variance of these traits are largely due to changes in the genetic variance.

Survey of clinical pharmacists' knowledge of appropriateness of antimicrobial therapy for upper respiratory infections and acute bronchitis

We conducted a survey to assess clinical pharmacists' recommendation of antibiotics for upper respiratory infections (URIs) and acute bronchitis. A random sample of 752 members of the American College of Clinical Pharmacy were mailed a multiple-choice survey that presented four examples consistent with clinical symptoms of the two disorders. Respondents were asked what treatment they would recommend for each example. The response rate was 59%. Pharmacists recommended antibiotics for the treatment of both URIs and acute bronchitis significantly more if patients' symptoms included discolored discharge or sputum as opposed to clear discharge. Those who were board certified were less likely than nonboard-certified pharmacists to recommend antibiotics for URIs with discolored discharge. Pharmacists who specialized in either ambulatory care or infectious disease were less likely than those in other specialties to recommend antibiotics for acute bronchitis with discolored sputum. Clinical pharmacists are similar to patients and physicians in their belief that antibiotics are appropriate for URIs and acute bronchitis with discolored discharge. Considering the role that pharmacists play as clinical consultants to physicians, greater efforts should be made to educate them regarding appropriate prescription of antibiotics.

Tolerance induction for islet transplantation

Type I diabetes is a systemic autoimmune disease. Although transplantation of pancreatic tissues restores glucose homeostasis, grafts are affected by acute and chronic rejection as well as re-occurrence of autoimmune destruction. One newly recognized promising strategy to interrupt these detrimental processes is hematopoietic chimerism induced by bone marrow transplantation (BMT). The application of hematopoietic chimerism has three domains in the treatment of Type I diabetes mellitus: (1) tolerance induction to pancreas or pancreatic islet grafts; (2) prevention of the re-occurrence of autoimmune processes in the graft; (3) prevention of the onset of overt diabetes once the pre-diabetic state is clearly identified. Unfortunately, conventional BMT is associated with significant morbidity and mortality due to graft-versus-host disease (GVHD), failure of engraftment and lethal conditioning. The risk of these complications cannot be justified in the treatment of non-malignant diseases including Type I diabetes. This chapter will outline potential strategies to achieve hematopoietic chimerism without the risk of deadly complications. With these strategies, it may be possible to apply hematopoietic chimerism in the treatment of Type I diabetes, both to induce tolerance to islet allografts as well as to intervene and interrupt the autoimmune process in its early stages.

Intellectual assessment of children with asymptomatic congenital cytomegalovirus infection

The findings of previous studies examining the neurocognitive development of children with clinically inapparent (asymptomatic) cytomegalovirus (CMV) infection have demonstrated mixed results. These studies have generally depended on small sample sizes (i.e., < 50). We examined the intellectual development of children with asymptomatic congenital CMV infection using a sample larger than previous studies. Two hundred and four cases aged 5 to 200 months were compared with 177 uninfected siblings ranging in age from 6 to 203 months. Parents were administered the Developmental Profile, a measure of developmental achievement. Children who were older than 30 months were administered an objective intelligence measure. Results of this study showed that children with asymptomatic congenital CMV infection do not demonstrate intellectual impairment, and that they perform similarly to uninfected siblings. Parents tended to overestimate their child's level of functioning regardless of whether the child had CMV infection.

The heterocyclic substituted pyridine derivative (+/-)-2-(-3-pyridinyl)-1-azabicyclo[2.2.2]octane (RJR-2429): a selective ligand at nicotinic acetylcholine receptors

The present report describes in vitro studies demonstrating that the heterocyclic substituted pyridine compound (+/-)-2-(3-pyridinyl)-1-azabicyclo[2.2.2]octane (RJR-2429) is extremely potent in activating human muscle nicotine ACh receptor (nAChR) (EC50 = 59 +/- 17 nM; Emax = 110 +/- 09% vs. nicotine). RJR-2429 is markedly less potent in activating nAChRs in the clonal cell line PC12, with EC50 = 1100 +/- 230 nM and Emax = 85 +/- 20% when compared with nicotine. The activation of a putative alpha 3 beta 4-containing nAChR in PC12 by RJR-2429 reveals a potency intermediate between nicotine and epibatidine (EC50 of 20,000 nM for nicotine and 30 nM for epibatidine). Dose-response curves for agonist-induced ileum contraction indicate that RJR-2429 is equipotent with nicotine, having an EC30 of approximately 2 microM. RJR-2429 binds with high affinity to alpha 4 beta 2 receptor subtype (Ki = 1.0 +/- 0.3 nM), and chronic exposure results in significant up-regulation of the high-affinity [3H]nicotine binding sites. In addition, RJR-2429 does not activate nAChRs present in rat thalamic preparations but is a potent inhibitor of this receptor subtype. It antagonizes nicotine-stimulated ion flux in thalamic synaptosomes with an IC50 of 154 +/- 37 nM. It also is a potent partial agonist at nAChRs mediating dopamine release from rat synaptosomal preparations (EC50 = 2 +/- 1 nM; Emax = 40%; epibatidine and nicotine have EC50 values of 0.4 and 100 nM, respectively). A model for the structure-activity profile of RJR-2429, nicotine and epibatidine was derived by molecular forcefield and quantum mechanics calculations and may provide important clues for the development of ligands selective for nAChR subtypes as probes in the life sciences or as potential therapeutic tools.