A map of octopaminergic neurons in the Drosophila brain

The biogenic amine octopamine modulates diverse behaviors in invertebrates. At the single neuron level, the mode of action is well understood in the peripheral nervous system owing to its simple structure and accessibility. For elucidating the role of individual octopaminergic neurons in the modulation of complex behaviors, a detailed analysis of the connectivity in the central nervous system is required. Here we present a comprehensive anatomical map of candidate octopaminergic neurons in the adult Drosophila brain: including the supra‐ and subesophageal ganglia. Application of the Flp‐out technique enabled visualization of 27 types of individual octopaminergic neurons. Based on their morphology and distribution of genetic markers, we found that most octopaminergic neurons project to multiple brain structures with a clear separation of dendritic and presynaptic regions. Whereas their major dendrites are confined to specific brain regions, each cell type targets different, yet defined, neuropils distributed throughout the central nervous system. This would allow them to constitute combinatorial modules assigned to the modulation of distinct neuronal processes. The map may provide an anatomical framework for the functional constitution of the octopaminergic system. It also serves as a model for the single‐cell organization of a particular neurotransmitter in the brain. J. Comp. Neurol. 513:643–667, 2009. © 2009 Wiley‐Liss, Inc.     

Modular subdivision of mushroom bodies by kenyon cells in the silkmoth

In insects, olfactory information in the glomeruli of the antennal lobe, the first olfactory center, is transmitted to the lateral protocerebrum and the calyx of the mushroom body via projection neurons. In male silkmoths (Bombyx mori), arborization patterns in the calyx differ markedly between projection neurons that respond to sex pheromones and those that respond to general odors. However, little is known about the organization of the mushroom body's intrinsic neurons, called Kenyon cells (KCs), which receive the inputs from the projection neurons. We investigated the silkmoth mushroom body and identified four parallel subdivisions in the lobes and pedunculus by immunolabeling with antibodies against the catalytic subunit of protein kinase A in Drosophila melanogaster (DC0) and the neuromodulatory peptide FMRFamide. To further understand the detailed organization of the mushroom body, we performed extensive labeling of individual KCs. We identified four morphological types whose axonal projections corresponded to the subdivisions in the lobes, and found that each type of KC had a characteristic dendritic morphology in the calyx. These results show a correlation between the axonal projections of KCs in the lobes and dendritic morphology in the calyx, and indicate different functional roles for the subdivisions. J. Comp. Neurol. 513:315–330, 2009. © 2009 Wiley‐Liss, Inc.     

A recombinant West Nile virus envelope protein vaccine candidate produced in Spodoptera frugiperda expresSF+ cells

In this study, a recombinant truncated West Nile virus envelope protein antigen (rWNV-E) was produced in serum-free cultures of the expresSF+ insect cell line via baculovirus infection. This production system was selected based on its use in the production of candidate human and animal vaccine antigens. A defined fermentation and purification process for the rWNV-E antigen was established to control for purity and immunogenicity of each protein batch. The material formulated with aluminum hydroxide was stable for greater than 8 months at 4 °C. The recombinant vaccine candidate was evaluated for immunogenicity and protective efficacy in several animal models. In mouse and hamster WNV challenge models, the vaccine candidate induced viral protection that correlated with anti-rWNV-E immunogenicity and WNV neutralizing antibody titers. The rWNV-E vaccine candidate was used to boost horses previously immunized with the Fort Dodge inactivated WNV vaccine and also to induce WNV neutralizing titers in naïve foals that were at least 14 weeks of age. Furthermore, the vaccine candidate was found safe when high doses were injected into rats, with no detectable treatment-related clinical adverse effects. These observations demonstrate that baculovirus-produced rWNV-E can be formulated with aluminum hydroxide to produce a stable and safe vaccine which induces humoral immunity that can protect against WNV infection.     

Comprehensive phylogeny of apid bees reveals the evolutionary origins and antiquity of cleptoparasitism

Apidae is the most speciose and behaviorally diverse family of bees. It includes solitary, eusocial, socially parasitic, and an exceptionally high proportion of cleptoparasitic species. Cleptoparasitic bees, which are brood parasites in the nests of other bees, have long caused problems in resolving the phylogenetic relationships within Apidae based on morphological data because of the tendency for parasites to converge on a suite of traits, making it difficult to differentiate similarity caused by common ancestry from convergence. Here, we resolve the evolutionary history of apid cleptoparasitism by conducting a detailed, comprehensive molecular phylogenetic analysis of all 33 apid tribes (based on 190 species), including representatives from every hypothesized origin of cleptoparasitism. Based on Bayesian ancestral state reconstruction, we show that cleptoparasitism has arisen just four times in Apidae, which is fewer times than previously estimated. Our results indicate that 99% of cleptoparasitic apid bees form a monophyletic group. Divergence time estimates reveal that cleptoparasitism is an ancient behavior in bees that first evolved in the late Cretaceous 95 Mya [95% highest posterior density (HPD) = 87–103]. Our phylogenetic analysis of the Apidae sheds light on the macroevolution of a bee family that is of evolutionary, ecological, and economic importance.     

Equilibrium speciation dynamics in a model adaptive radiation of island lizards

The relative importance of equilibrium and nonequilibrium processes in shaping patterns of species richness is one of the most fundamental questions in biodiversity studies. If equilibrium processes predominate, then ecological interactions presumably limit species diversity, potentially through diversity dependence of immigration, speciation, and extinction rates. Alternatively, species richness may be limited by the rate at which diversity arises or by the amount of time available for diversification. These latter explanations constitute nonequilibrium processes and can apply only to biotas that are unsaturated or far from diversity equilibria. Recent studies have challenged whether equilibrium models apply to biotas assembled through in situ speciation, as this process may be too slow to achieve steady-state diversities. Here we demonstrate that speciation rates in replicate Caribbean lizard radiations have undergone parallel declines to equilibrium conditions on three of four major islands. Our results suggest that feedback between total island diversity and per-capita speciation rates scales inversely with island area, with proportionately greater declines occurring on smaller islands. These results are consistent with strong ecological controls on species richness and suggest that the iconic adaptive radiation of Caribbean anoles may have reached an endpoint.     

Phylogeny of European bat Lyssavirus 1 in Eptesicus isabellinus bats, Spain

To better understand the epidemiology of European bat lyssavirus 1 (EBLV-1) in Europe, we phylogenetically characterized Lyssavirus from Eptesicus isabellinus bats in Spain. An independent cluster of EBLV-1 possibly resulted from geographic isolation and association with a different reservoir from other European strains. EBLV-1 phylogeny is complex and probably associated with host evolutionary history.     

Early warning system for West Nile virus risk areas, California, USA

The Dynamic Continuous-Area Space-Time (DYCAST) system is a biologically based spatiotemporal model that uses public reports of dead birds to identify areas at high risk for West Nile virus (WNV) transmission to humans. In 2005, during a statewide epidemic of WNV (880 cases), the California Department of Public Health prospectively implemented DYCAST over 32,517 km2 in California. Daily risk maps were made available online and used by local agencies to target public education campaigns, surveillance, and mosquito control. DYCAST had 80.8% sensitivity and 90.6% specificity for predicting human cases, and k analysis indicated moderate strength of chance-adjusted agreement for >4 weeks. High-risk grid cells (populations) were identified an average of 37.2 days before onset of human illness; relative risk for disease was >39× higher than for low-risk cells. Although prediction rates declined in subsequent years, results indicate DYCAST was a timely and effective early warning system during the severe 2005 epidemic.     

Spatial patterns of aflatoxin levels in relation to ear-feeding insect damage in pre-harvest corn

Key impediments to increased corn yield and quality in the southeastern US coastal plain region are damage by ear-feeding insects and aflatoxin contamination caused by infection of Aspergillus flavus. Key ear-feeding insects are corn earworm, Helicoverpa zea, fall armyworm, Spodoptera frugiperda, maize weevil, Sitophilus zeamais, and brown stink bug, Euschistus servus. In 2006 and 2007, aflatoxin contamination and insect damage were sampled before harvest in three 0.4-hectare corn fields using a grid sampling method. The feeding damage by each of ear/kernel-feeding insects (i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs), and maize weevil population were assessed at each grid point with five ears. The spatial distribution pattern of aflatoxin contamination was also assessed using the corn samples collected at each sampling point. Aflatoxin level was correlated to the number of maize weevils and stink bug-discolored kernels, but not closely correlated to either husk coverage or corn earworm damage. Contour maps of the maize weevil populations, stink bug-damaged kernels, and aflatoxin levels exhibited an aggregated distribution pattern with a strong edge effect on all three parameters. The separation of silk- and cob-feeding insects from kernel-feeding insects, as well as chewing (i.e., the corn earworm and maize weevil) and piercing-sucking insects (i.e., the stink bugs) and their damage in relation to aflatoxin accumulation is economically important. Both theoretic and applied ramifications of this study were discussed by proposing a hypothesis on the underlying mechanisms of the aggregated distribution patterns and strong edge effect of insect damage and aflatoxin contamination, and by discussing possible management tactics for aflatoxin reduction by proper management of kernel-feeding insects. Future directions on basic and applied research related to aflatoxin contamination are also discussed.     

Spermatogonial stem cells: questions, models and perspectives

This review looks into the phylogeny of spermatogonial stem cells and describes their basic biological features. We are focusing on species-specific differences of spermatogonial stem cell physiology. We propose revised models for the clonal expansion of spermatogonia and for the potential existence of true stem cells and progenitors in primates but not in rodents. We create a new model for the species-specific arrangements of spermatogenic stages which may depend on the variable clonal expansion patterns. We also provide a brief overview of germ cell transplantation as a powerful tool for basic research and its potential use in a clinical setting.