Oogenesis involves a novel nuclear envelop remodeling mechanism in Schmidtea mediterranea.

The cell nuclei of Ophisthokonts, the eukaryotic supergroup defined by fungi and metazoans, is remarkable in the constancy of their double-membraned structure in both somatic and germ cells. Such remarkable structural conservation underscores common and ancient evolutionary origins. Yet, the dynamics of disassembly and reassembly displayed by Ophisthokont nuclei vary extensively.

Quantifying Cell Proliferation Through Immunofluorescence on Whole-Mount and Cryosectioned Regenerating Caudal Fins in African Killifish.

The African killifish is an attractive research organism for regeneration- and aging-related studies due to its remarkably short generation time and rapid aging. Dynamic changes in cell proliferation are an essential biological process involved in development, regeneration, and aging. Quantifying the dynamics of cell proliferation in these contexts facilitates the elucidation of the attendant underlying mechanisms.

Multispectral Filter Array Design by Optimal Sphere Packing.

Multispectral imaging (MSI) collects a datacube of spatio-spectral information of a scene. Many acquisition methods for spectral imaging use scanning, preventing its widespread usage for dynamic scenes. On the other hand, the conventional color filter array (CFA) method often used to sample color images has also been extended to snapshot MSI using a Multispectral Filter Array (MSFA), which is a mosaic of selective spectral filters placed over the Focal Plane Array (FPA).

Molecular characterization of a flatworm Girardia isolate from Guanajuato, Mexico.

Planarian flatworms are best known for their impressive regenerative capacity, yet this trait varies across species. In addition, planarians have other features that share morphology and function with the tissues of many other animals, including an outer mucociliary epithelium that drives planarian locomotion and is very similar to the epithelial linings of the human lung and oviduct. Planarians occupy a broad range of ecological habitats and are known to be sensitive to changes in their environment.

Enhanced lipogenesis through Pparγ helps cavefish adapt to food scarcity.

Nutrient availability varies seasonally and spatially in the wild. While many animals, such as hibernating animals or migrating birds, evolved strategies to overcome periods of nutrient scarcity, the cellular mechanisms of these strategies are poorly understood. Cave environments represent an example of nutrient-deprived environments, since the lack of sunlight and therefore primary energy production drastically diminishes the nutrient availability.

Hox genes regulate asexual reproductive behavior and tissue segmentation in adult animals.

Hox genes are highly conserved transcription factors renowned for their roles in the segmental patterning of the embryonic anterior-posterior (A/P) axis. We report functions for Hox genes in A/P tissue segmentation and transverse fission behavior underlying asexual reproduction in adult planarian flatworms, Schmidtea mediterranea. Silencing of each of the Hox family members identifies 5 Hox genes required for asexual reproduction.

Vertebrate diapause preserves organisms long term through Polycomb complex members.

Diapause is a state of suspended development that helps organisms survive extreme environments. How diapause protects living organisms is largely unknown. Using the African turquoise killifish (), we show that diapause preserves complex organisms for extremely long periods of time without trade-offs for subsequent adult growth, fertility, and life span.

Systemic RNA Interference in Planarians by Feeding of dsRNA Containing Bacteria.

RNA interference (RNAi) is currently the only method available in planaria for assessing the function of particular genes. We describe here a method for performing body-wide gene knockdown, relying on dsRNA production in bacteria and subsequent delivery to planaria by feeding a liver-bacteria mixture. This method is ideal for screening many genes in parallel, in a cost-effective and reliable manner.

Whole-Mount BrdU Staining with Fluorescence In Situ Hybridization in Planarians.

Detection of cell proliferation based on the incorporation of 5'-bromo-2'-deoxyuridine (BrdU) has become a standard approach for studying stem cell and progenitor cell populations in developing and adult tissue. In this chapter, we describe three BrdU administration methods for planarians and a staining protocol combining BrdU detection with whole-mount fluorescence in situ hybridization (FISH). Collectively, these protocols enable the combined analysis of BrdU-incorporation and endogenous gene expression, as for example during lineage tracing applications.

Planarian High Molecular Weight DNA Isolation by Spooling.

High-quality large molecular weight genomic DNA is important for genomic studies. Most commercial available genomic DNA purification kits have failed to generate high molecular weight DNA of sufficient quality from planarians. Here, we describe a simple and efficient genomic DNA isolation method, which has worked for several different planarian species, including Schmidtea mediterranea.

Culturing Planarians in the Laboratory.

Planaria, particularly Schmidtea mediterranea and Dugesia japonica, are now established as research organisms in many laboratories across the life sciences community. Planarians are cheap and easy to keep in the lab. This chapter provides techniques and guidelines for establishing and maintaining a planarian colony.

Planarians and the History of Animal Regeneration: Paradigm Shifts and Key Concepts in Biology.

Regeneration has captured human imagination for much of recorded history. Its sociological influence is evident in ancient and modern folklore, art, politics, and even language. In many ways, the study of regeneration helped establish the field of biology as a legitimate scientific discipline.

Widespread maintenance of genome heterozygosity in Schmidtea mediterranea.

Loss of heterozygosity through inbreeding or mitotic errors leads to reductions in progeny survival and fertility. Loss of heterozygosity is particularly exacerbated in geographically isolated populations, which are prone to inbreeding depression and faster rates of extinction. The regenerative capacities of the hermaphroditic biotype of the planarian Schmidtea mediterranea allowed us to perform a systematic genetic test of Mendelian segregation and study the loss of heterozygosity in the Spiralian superclade in general and planarians in particular.

Embryonic origin of adult stem cells required for tissue homeostasis and regeneration.

Planarian neoblasts are pluripotent, adult somatic stem cells and lineage-primed progenitors that are required for the production and maintenance of all differentiated cell types, including the germline. Neoblasts, originally defined as undifferentiated cells residing in the adult parenchyma, are frequently compared to embryonic stem cells yet their developmental origin remains obscure. We investigated the provenance of neoblasts during embryogenesis, and report that neoblasts arise from an anarchic, cycling population wholly responsible for production of all temporary and definitive organs during embryogenesis.

Head regeneration in hemichordates is not a strict recapitulation of development.

Background: Head or anterior body part regeneration is commonly associated with protostome, but not deuterostome invertebrates. However, it has been shown that the solitary hemichordate Ptychodera flava possesses the remarkable capacity to regenerate their entire nervous system, including their dorsal neural tube and their anterior head-like structure, or proboscis. Hemichordates, also known as acorn worms, are marine invertebrate deuterostomes that have retained chordate traits that were likely present in the deuterostome ancestor, placing these animals in a vital position to study regeneration and chordate evolution.

Unravelling a can of worms.

Understanding the evolutionary relationships between species could help researchers select better model organisms to study in the laboratory.