Cytohesins are cytoplasmic ErbB receptor activators.

Signaling by ErbB receptors requires the activation of their cytoplasmic kinase domains, which is initiated by ligand binding to the receptor ectodomains. Cytoplasmic factors contributing to the activation are unknown. Here we identify members of the cytohesin protein family as such factors. Cytohesin inhibition decreased ErbB receptor autophosphorylation and signaling, whereas cytohesin overexpression stimulated receptor activation. Monitoring epidermal growth factor receptor (EGFR) conformation by anisotropy microscopy together with cell-free reconstitution of cytohesin-dependent receptor autophosphorylation indicate that cytohesins facilitate conformational rearrangements in the intracellular domains of dimerized receptors. Consistent with cytohesins playing a prominent role in ErbB receptor signaling, we found that cytohesin overexpression correlated with EGF signaling pathway activation in human lung adenocarcinomas. Chemical inhibition of cytohesins resulted in reduced proliferation of EGFR-dependent lung cancer cells in vitro and in vivo. Our results establish cytohesins as cytoplasmic conformational activators of ErbB receptors that are of pathophysiological relevance.

[Long-lasting souvenir from Cameroon - Persistent, massive hypereosinophilia in amicrofilaremic infection with Loa loa]. / Langlebiges Souvenir aus Kamerun ­ persistierende, massive Hypereosinophilie bei amikrofilarämischer Infektion mit Loa loa.

INTRODUCTION: Diagnosis of a polysymptomatic, rare parasitosis requires collaboration of internal specialists, tropical disease specialists, parasitologists and dermatologists. HISTORY: The course of disease is shown in a 66-year-old woman who regularly travels to Cameroon and presented with remarkable hypereosinophilia and pruritus with urticarial swellings. FINDINGS AND DIAGNOSIS: Using interdisciplinary diagnostics based on travel history, symptoms and laboratory results an occult amicrofilaraemic Loa loa infection with immunological hyperreaction to the parasite antigen, reactive hypereosinophilia and high antibody titers was diagnosed. THERAPY AND COURSE: Anthelmintic therapy was inducted with ivermectin and diethylcarbamazine. Treatment with ivermectin alone resulted in a prompt regression of symptoms and decrease of eosinophil levels and antibody titers. CONCLUSIONS: Parasitic diseases like L. loa infections are extremely rare in Europe but should be considered as differential diagnosis at an early stage when patients present with appropriate travel history and clinical findings. There is a lack of standardized therapy and follow-up recommendations. A precise recording of all new diagnoses with therapy progress/response should be established in an international registry.

The influence of variable rates of inbreeding on fitness, environmental responsiveness, and evolutionary potential.

We manipulated experimental populations of the housefly (Musca domestica L.) under three inbreeding schemes (fast, slow, and punctuated) to partition out the influences of different means and variances in the rate of inbreeding, per generation, while controlling for the final level of inbreeding as a constant. One treatment used constant fast inbreeding (11% per generation; Ne = 4 for 4 generations), for a comparison to one that was consistently slow (3% per generation; Ne = 16 for 14 generations). The third followed a model for serial founder-flush events. Each founder-flush episode involved a one-generation pulse of fast inbreeding (Ne = 4) followed by two generations of very low (or no) inbreeding, yielding high intergenerational variation (i.e., for an average inbreeding rate of 4% per generation). Allozyme assays showed that we achieved the intended final inbreeding coefficient of about 37%. All inbreeding schemes decreased fitness levels in terms of egg-to-adult viability, development time, and male mating success relative to the outbred control. The consistently fast inbreeding protocol had more pronounced reductions in fitness, relative to the other two inbreeding schemes. In comparison to the fast and punctuated regimes, the consistently slow protocol preserved evolutionary potential (as assayed by the genetic divergence of subpopulations exposed to different environments) in egg-to-adult viability, and (albeit anecdotally) reduced the extinction probabilities, especially in a novel environment. The punctuated treatment did not optimize the potential for purge as predicted, but instead reduced fitness, evolutionary potential, and environmental responsiveness (as measured by genotype-by-environment interactions). This founder-flush treatment also had the highest extinction probabilities. Longer periods of population flush might be necessary to purge effectively in a punctuated scheme. We conclude that the rate of inbreeding, independent from the final level, can have important effects on population fitness, environmental responsiveness, and evolutionary potential.

Nonadditive genetic effects in animal behavior.

Heritabilities, commonly used to predict evolutionary potential, are notoriously low for behaviors. Apart from strong contributions of environmental variance in reducing heritabilities, the additive genetic components can be very low, especially when they are camouflaged by nonadditive genetic effects. We first report the heritabilities of courtship traits in founder-flush and control populations of the housefly (Musca domestica L.). We estimated the heritability of each male and female display through the regression of the courtships involving daughters and sons (with randomly selected mates) onto the "midparental" courtship values of their parents. Overall, the average heritability was significantly (P = .012) higher for the parent-daughter assays than for the parent-son assays. We attributed the low (even negative) heritabilities to genotype-by-environment interactions whereby the male's behavior is influenced by the "environment" of his mating partner's preferences for the display, generating epistasis through indirect genetic effects. Moreover, bottlenecked lines had up to 800% of the heritability of the controls, suggesting "conversion" of additive genetic variance from nonadditive components. Second, we used line-cross assays on separate populations that had been selected for divergence in mating behavior to identify dominance and epistasis through heterosis and outbreeding depression in courtship. Finally, our literature review confirms the prevalence of such low heritabilities (i.e., a conservative mean of 0.38) and nonadditive genetics in other behavioral repertoires (64% of the studies). We conclude that animal behavior is especially prone to the gamut of quantitative genetic complexities that can result in negative heritabilities, negative selection responses, inbreeding depression, conversion, heterosis, and outbreeding depression.

Genetic tools for studying adaptation and the evolution of behavior.

The rapid expansion of genomic and molecular genetic techniques in model organisms, and the application of these techniques to organisms that are less well studied genetically, make it possible to understand the genetic control of many behavioral phenotypes. However, many behavioral ecologists are uncertain about the value of including a genetic component in their studies. In this article, we review how genetic analyses of behavior are central to topics ranging from understanding past selection and predicting future evolution to explaining the neural and hormonal control of behavior. Furthermore, we review both new and old techniques for studying evolutionary behavior genetics and highlight how the choice of approach depends on both the question and the organism. Topics discussed include genetic architecture, detecting the past history of selection, and genotype-by-environment interactions. We show how these questions are being addressed with techniques including statistical genetics, QTL analyses, transgenic analyses, and microarrays. Many of the techniques were first applied to the behavior of genetic model organisms such as laboratory mice and flies. Two recent developments serve to expand the relevance of such studies to behavioral ecology. The first is to use model organisms for studies of the genetic basis of evolutionarily relevant behavior and the second is to apply methods developed in model genetic systems to species that have not previously been examined genetically. These conceptual advances, along with the rapid diversification of genetic tools and the recognition of widespread genetic homology, suggest a bright outlook for evolutionary genetic studies. This review provides access to tools through references to the recent literature and shows the great promise for evolutionary behavioral genetics.

Effect of Migration or Inbreeding Followed by Selection on Low-Founder-Number Populations: Implications for Captive Breeding Programs.

Using the housefly, Musca domestica (L), as a model system, we tested the ability of two extrems in the range of possible captive breeding protocols to yield sustainable populations following founding with low founder numbers. The protocols tested included two levels of migration as well as inbreeding followed by selection, each with appropriate controls. Each low-founder-number population was founded with two pairs of flies. The maximum migration scheme had 50% migration per generation, and the minimum migration populations experienced a migration rate of 2.5% per generation. The control level of migration was 0%. A fourth low-founder-number treatment was designed to test the effect of inbreeding followed by selection. Two sets of high-founder-number control groups were also derived from the stock population. Two fitness measures, viability and productivity of the populations, were recorded at the fifth generation. Populations in the minimum-migration and zero migration treatment groups had lower fitness than populations in any other treatment for both measures. Populations that experienced inbreeding and selection for high fitness levels, high levels of migration, or large high-founder-number populations were equally fit. These results demonstrate that a captive-breeding scheme that contains substantial levels of migration or inbreeding followed by selection can yield highly adapted populations. Efecto de la migración o intracruza seguido por la selección de poblacions originadas a partir de un número pequeño de fundadores.

Resumen: En este trabajo usamos a la mosca doméstica Musca domestica (L.) como un sistema modelo para examinar la habilidad de dos extremos en el espectro posible de protocolos para obtener poblaciones sustentables de especies cautivas luego de un evento fundador con un número bajo de fundadores. Los protocolos examinados incluyeron dos níveles de migración, asi como también intracruza seguid de selección, cada uno con controles apropiados. Cada población originada a partir de un número bajo de fundadores por fue fundada por dos pares de moscas. El esquema de mayor migración tuvo una tasa de migración del 50% generación y el mínimo experimentó una tasa de migración del 2.5% por generación. El nivel control de migración fue del 0%. Un cuarto tratamiento con un bajo número de fundadores fue diseñado para examinar el efecto la intracruza seguido de selección. También se obtuvieron a partir de la población original dos juegos de grupos de control con un alto número de fundadores. En la quinta generación se registraron dos medidas la condicíon, la viabilidad y la productividad de las poblaciones. Las poblaciones en los grupos con immigración baja o nula tuvieron una condición más baja que las poblaciones en cualquiera de los otros tratamientos para ambas medidas de condición. Las poblaciones que experimentaron intracruza y selección para niveles de condición altos, niveles altos de migración o un número de fundadores alto tuvieron la misma condición. Estos resultados demuestran que un esquema de cría en cautiverio que incluya niveles substanciales de migración o intracruza seguido de selección puede producir poblaciones altamente adaptadas.

Reversed selection responses in small populations of the housefly (Musca domestica L.).

We compared the efficacy of artificial and natural selection processes in purging the genetic load of perpetually small populations. We subjected replicate lines of the housefly (Musca domestica L.), recently derived from the wild, to artificial selection for increased mating propensity (i.e., the proportion of male-female pairs initiating copulation within 30 min) in efforts to cull out the inbreeding depression effects of long-term small population size (as determined by a selection protocol for increased assortative mating). We also maintained parallel non-selection lines for assessing the spontaneous purge of genetic load due to inbreeding alone. We thus evaluated the fitness of artificially and 'naturally' purging populations held at census sizes of 40 individuals over the course of 18 generations. We found that the artificially selected lines had significant increases in mating propensity (up to 46% higher from the beginning of the protocol) followed by reversed selection responses back to the initial levels, resulting in non-significant heritabilities. Nevertheless, the 'naturally' selected lines had significantly lower fitness overall (a 28% reduction from the beginning of the protocol), although lower effective population sizes could have contributed to this effect. We conclude that artificial selection bolstered fitness, but only in the short-term, because the inadvertent fixation of extant genetic load later resulted in pleiotropic fitness declines. Still, the short-term advantage of the selection protocol likely contributed to the success of the speciation experiment since our recently-derived housefly populations are particularly vulnerable to inbreeding depression effects on mating behavior.

Testing alternative methods for purging genetic load using the housefly (Musca domestica L.).

When a population faces long-term inbreeding, artificial selection, in principle, can enhance natural selection processes for purging the exposed genetic load. However, strong purge pressures might actually decrease fitness through the inadvertent fixation of deleterious alleles and allelic combinations. We tested lines of the housefly (Musca domestica L.) for the effectiveness of artificial selection to promote the adaptation to small population size. Specifically, replicate populations were held at average census sizes of 54 for nine generations or 30 for 14 generations while being subjected to artificial selection pressure for increased fitness in overall mating propensity (i.e., the proportion of virgin male-female pairs initiating copulation within 30 min), while also undergoing selection to create differences among lines in multivariate components of courtship performance. In the 14-generation experiment, a subset of the lines were derived from a founder-flush population (i.e., derived from three male-female pairs). In both experiments, we also maintained parallel non-selection lines to assess the potential for natural purging through serial inbreeding alone. Sub-populations derived from a stock newly derived from the wild responded to artificial selection for increased mating propensity, but only in the short-term, with eventual rebounds back to the original levels. Serial inbreeding in these lines simply reduced mating propensity. In sub-populations derived from the same base population, but 36 generations later, both artificial selection and serial inbreeding increased mating propensity, but mainly to restore the level found upon establishment in the laboratory. Founder-flush lines responded as well as the non-bottlenecked controls, so we base our major conclusions on the comparisons between fresh-caught and long-term laboratory stocks. We suggest that the effectiveness of the alternative purge protocols depended upon the amount of genetic load already exposed, such that prolonged periods of relaxed or altered selection pressures of the laboratory rendered a population more responsive to purging protocols.

The genetic architecture of house fly mating behavior.

This chapter summarizes several experimental approaches used to identify the effects of dominance, epistasis, and genotype-by-environment interactions in the genetic architecture of the mating behavior of the common house fly (Musca domestica L.). Quantitative genetic investigations of mating behavior hold special intrigue for unraveling the complexities of fitness traits, with applications to theory on sexual selection and speciation. Besides being well suited to large-scale quantitative genetic protocols, the house fly has a remarkably complex courtship repertoire, affording special opportunities for studies on communication, social interactions, and learning. Increased additive genetic variances for the courtship repertoire of experimentally bottlenecked populations provided evidence for the presence of dominance and/or epistasis. Negative genetic variances in these populations suggested genotype-by-environment interactions, where the environment is the mating partner. Line cross assays of populations that had been subjected to selection for divergent courtship repertoire confirmed that both dominance and epistasis have significant effects. These crosses also showed more directly that the expression of the male's genotype is dependent upon the preferences of his mating partner. Repeatability studies also detailed how males alter their courtship performances with successive encounters within and across females, such that the males learn to improve their techniques in securing copulations. A review of 41 animal behavior studies found that a wide range of traits and taxa have dominance, epistasis, and genotype-y-environment interactions, although house fly courtship may remain a unique model where learning is an intersexually selected trait. Future development of more sophisticated molecular techniques for the M. domestica genome will help unravel the underlying biochemical and developmental pathways of these quantitative genetic interactions for a more complete understanding of the processes of inbreeding depression, outbreeding depression, and pleiotropy.

AN ANALYSIS OF SELECTIONAL RESPONSE IN RELATION TO A POPULATION BOTTLENECK.

Selection for increased morphometric shape (ratio of wing length to thorax width) was compared between control (nonbottlenecked) populations and bottlenecked populations founded with two male-female pairs of flies. Contrary to neutral expectation, selectional response was not reduced in bottlenecked populations, and the mean realized heritabilities and additive genetic variances were higher for the bottlenecked lines than for the nonbottlenecked lines. Additive genetic variances based on these realized heritabilities were consistent with independent estimates of genetic variances based on parent-offspring covariances. Joint scaling tests applied to the crosses between selected lines and their controls revealed significant nonadditive components of genetic variance in the ancestor, which were not detected in the crosses involving bottlenecked lines. The nonbottlenecked lines responded principally by changes in one trait or the other (wing length or thorax width) but not in both, and regardless of which trait responded, larger trait size was dominant and epistatic to smaller size. Stabilizing selection for morphometric shape in the ancestor likely molded the genetic architecture to include nonadditive genetic effects.

MATING PROPENSITY AND COURTSHIP BEHAVIOR IN SERIALLY BOTTLENECKED LINES OF THE HOUSEFLY.

The efficacy of bottlenecks to stimulate divergence in courtship behavior and consequent premating isolation was tested by serial founder-flush episodes of three sizes (one, four, or 16 pairs) on a population of houseflies established in the laboratory from a single field population. After the fifth founder-flush episode, intraline and interline crosses were performed to detect divergence in mating propensities and patterns of assortative mating. Videotapings of intraline courtships for the bottleneck lines and the control were evaluated for changes in courtship repertoire. All bottleneck lines showed significant divergence from the control in male and/or female mating propensity and in courtship behavior. Divergence from the control was bidirectional for both male and female mating propensities as well as for courtship element utilization. Out of 15 tests for assortative mating between bottleneck lines and between bottleneck lines and the control, only two cases of positive assortative mating and one case of negative assortative mating were detected. Because some bottleneck lines showed increased courtship element utilization and because decreased courtship utilization in some bottleneck lines was related to higher male mating success, the mechanisms behind the Kaneshiro model (which is based upon ancestral females discriminating against bottleneck males that had "lost" courtship elements) were not supported in general. A partitioning effect of the bottlenecks upon the intrinsic variation in the ancestral population for courtship pattern appeared to explain a large component of the directions of divergence from the control. Still, the pattern of divergence of some bottleneck lines apparently was not constrained by the intercorrelation structure of courtship behaviors detected in the control. Because previous studies showed that the bottleneck lines had rebounded from inbreeding depression to fitness levels of the control, this study documents nondebilitating differentiation in the courtship repertoire that can account for divergent mating propensities and premating isolation.

EFFECT OF AN EXPERIMENTAL BOTTLENECK ON MORPHOLOGICAL INTEGRATION IN THE HOUSEFLY.

Three measures of multivariate integration were derived from both additive genetic covariance and correlation matrices estimated from parent-offspring covariances to investigate the effect of bottlenecks of different sizes on genetic integration of morphological traits in the housefly, Musca domestica L. Bottleneck lines were initiated with one, four, or 16 pairs of flies sampled from a natural outbred (control) population. Bottlenecks of intermediate size significantly increased the average genetic correlation among traits, resulting in nearly isomorphic variation among all traits in these lines. Single-pair bottlenecks significantly disrupted the trait interrelationships, and the suites of traits identified by principal components of the additive genetic correlation and covariance matrices for the control population were no longer evident in these bottleneck lines. The alteration of the genetic relationships among traits as a result of a bottleneck suggests that nonadditive components of genetic variation affecting these traits were present in the control line. We discuss the implications of nonadditive gene action, particularly epistasis, for speciation via bottlenecks.

DIVERGENT AMBULATORY AND GROOMING BEHAVIOR IN SERIALLY BOTTLENECKED LINES OF THE HOUSEFLY.

The extent of genome-wide restructuring predicted in bottleneck models of speciation is addressed in assays of non-reproductive behavior in lines of the housefly. After five serial founder-flush cycles of one of three sizes (1, 4, or 16 pairs), each bottleneck line showed significant differentiation from the outbred control in ambulatory levels and grooming sequences in videotaped records of precopulatory activity. Only one line (4-pair) showed overall lethargy which was associated to inbreeding depression in egg-to-adult viability, thus exemplifying a case of probable extinction due to bottlenecks. The two most hyperactive lines (1- and 16-pair) showed very similar directions of differentiation from the control in locomotor activity and grooming behavior, as well as in mating behavior evaluated from a separate study. This high congruence suggested that directional selection toward the phenotypic optima of the ancestor operated on the bottleneck populations and that a 10-fold difference in theoretical inbreeding coefficients did not affect the magnitude of response. The remaining two bottleneck lines showed some independence from these general trajectories, their divergence along minor axes of ancestral intercorrelation structure possibly being more important to the formation of new species. Significant perturbations of the thresholds for execution of grooming and locomotor movements suggested increased evolutionary potential for ritualization (i.e., sexual selection for adoption of non-reproductive behavior into courtship repertoire) due to bottlenecks.

QUANTITATIVE GENETIC ESTIMATES OF MORPHOMETRIC VARIATION IN WILD-CAUGHT AND LABORATORY-REARED HOUSEFLIES.

Quantitative genetic estimates of morphometric traits in the housefly, Musca domestica L, were made on parents captured in the wild or reared in the laboratory. Phenotypic variation of morphometric traits declined within the laboratory, but as the additive genetic component of variation also declined, there was no net change in ∗∗∗narrow-sense heritabilities of these traits across environments. Additive genetic variances were inflated only when wild-caught females were used as parents, suggesting that a maternal effect was present.

MULTIVARIATE PHENOTYPIC DIFFERENTIATION AMONG BOTTLENECK LINES OF THE HOUSEFLY.

Multivariate phenotypic differentiation in eight morphometric traits was examined in bottleneck lines of the housefly initiated with one, four, or 16 pairs of flies from a natural outbred population. Differentiation was assessed using a Mahalanobis' distance metric in units of additive genetic variance and covariance estimated from the ancestral population (i.e., generalized genetic distance). This distance metric was partitioned into contributions of size and shape to total distance. Bottleneck lines of all sizes diverged significantly from the ancestral line, but the direction of these shifts differed among the lines of different initial founding size. Those populations founded with single pairs diverged from the ancestral line mostly in shape; the 16-pair lines differentiated almost entirely in size, and the four-pair lines were intermediate in the relative contribution of shape to differentiation from the control. Bottlenecks serve to alter the genetic relationships among traits within the derived populations and in doing so could promote speciation by permitting differentiation of the populations along evolutionary trajectories less accessible to the base population.