Genome assemblies of the simultaneously hermaphroditic flatworms Macrostomum cliftonense and Macrostomum hystrix.

The free-living, simultaneously hermaphroditic flatworms of the genus Macrostomum are increasingly used as model systems in various contexts. In particular, Macrostomum lignano, the only species of this group with a published genome assembly, has emerged as a model for the study of regeneration, reproduction, and stem-cell function. However, challenges have emerged due to M.

Mating strategy predicts gene presence/absence patterns in a genus of simultaneously hermaphroditic flatworms.

Gene repertoire turnover is a characteristic of genome evolution. However, we lack well-replicated analyses of presence/absence patterns associated with different selection contexts. Here, we study ∼100 transcriptome assemblies across Macrostomum, a genus of simultaneously hermaphroditic flatworms exhibiting multiple convergent shifts in mating strategy and associated reproductive morphologies.

Large-scale phylogenomics of the genus Macrostomum (Platyhelminthes) reveals cryptic diversity and novel sexual traits.

Free-living flatworms of the genus Macrostomum are small and transparent animals, representing attractive study organisms for a broad range of topics in evolutionary, developmental, and molecular biology. The genus includes the model organism M. lignano for which extensive molecular resources are available, and recently there is a growing interest in extending work to additional species in the genus.

No evidence for strong cytonuclear conflict over sex allocation in a simultaneously hermaphroditic flatworm.

Background: Cytoplasmic sex allocation distorters, which arise from cytonuclear conflict over the optimal investment into male versus female reproductive function, are some of the best-researched examples for genomic conflict. Among hermaphrodites, many such distorters have been found in plants, while, to our knowledge, none have been clearly documented in animals.

Methods: Here we provide a quantitative test for cytonuclear conflict over sex allocation in the simultaneously hermaphroditic flatworm Macrostomum lignano.

Lineage-associated tracts defining the anatomy of the Drosophila first instar larval brain.

Fixed lineages derived from unique, genetically specified neuroblasts form the anatomical building blocks of the Drosophila brain. Neurons belonging to the same lineage project their axons in a common tract, which is labeled by neuronal markers. In this paper, we present a detailed atlas of the lineage-associated tracts forming the brain of the early Drosophila larva, based on the use of global markers (anti-Neuroglian, anti-Neurotactin, inscuteable-Gal4>UAS-chRFP-Tub) and lineage-specific reporters.

Using MARCM to study Drosophila brain development.

Mosaic analysis with a repressible cell marker (MARCM) generates positively labeled, wild-type or mutant mitotic clones by unequally distributing a repressor of a cell lineage marker, originally tubP-driven GAL80 repressing the GAL4/UAS system. Variations of the technique include labeling of both sister clones (twin spot MARCM), the simultaneous use of two different drivers within the same clone (dual MARCM), as well as the use of different repressible transcription systems (Q-MARCM). MARCM can be combined with any UAS-based construct, such as localized GFP fusions to visualize subcellular compartments, genes for rescue and ectopic expression, and modifiers of neural activity.

A multipotent transit-amplifying neuroblast lineage in the central brain gives rise to optic lobe glial cells in Drosophila.

The neurons and glial cells of the Drosophila brain are generated by neural stem cell-like progenitors during two developmental phases, one short embryonic phase and one more prolonged postembryonic phase. Like the bulk of the adult-specific neurons, most of glial cells found in the adult central brain are generated postembryonically. Five of the neural stem cell-like progenitors that give rise to glial cells during postembryonic brain development have been identified as type II neuroglioblasts that generate neural and glial progeny through transient amplifying INPs.

Early-born neurons in type II neuroblast lineages establish a larval primordium and integrate into adult circuitry during central complex development in Drosophila.

Background: The central complex is a multimodal information-processing center in the insect brain composed of thousands of neurons representing more than 50 neural types arranged in a stereotyped modular neuroarchitecture. In Drosophila, the development of the central complex begins in the larval stages when immature structures termed primordia are formed. However, the identity and origin of the neurons that form these primordia and, hence, the fate of these neurons during subsequent metamorphosis and in the adult brain, are unknown.

Multipotent neural stem cells generate glial cells of the central complex through transit amplifying intermediate progenitors in Drosophila brain development.

The neural stem cells that give rise to the neural lineages of the brain can generate their progeny directly or through transit amplifying intermediate neural progenitor cells (INPs). The INP-producing neural stem cells in Drosophila are called type II neuroblasts, and their neural progeny innervate the central complex, a prominent integrative brain center. Here we use genetic lineage tracing and clonal analysis to show that the INPs of these type II neuroblast lineages give rise to glial cells as well as neurons during postembryonic brain development.

Emx3 is required for the differentiation of dorsal telencephalic neurons.

emx3 is first expressed in prospective telencephalic cells at the anterior border of the zebrafish neural plate. Knockdown of Emx3 function by morpholino reduces the expression of markers specific to dorsal telencephalon, and impairs axon tract formation. Rescue of both early and late markers requires low-level expression of emx3 at the one- or two-somite stage.