Evolution of lateralized gustation in nematodes.

Animals with small nervous systems have a limited number of sensory neurons that must encode information from a changing environment. This problem is particularly exacerbated in nematodes that populate a wide variety of distinct ecological niches but only have a few sensory neurons available to encode multiple modalities. How does sensory diversity prevail within this neuronal constraint? To identify the genetic basis for patterning different nervous systems, we demonstrate that sensory neurons in the respond to various salt sensory cues in a manner that is partially distinct from that of the distantly related nematode .

Automated cell lineage reconstruction using label-free 4D microscopy.

Patterns of lineal descent play a critical role in the development of metazoan embryos. In eutelic organisms that generate a fixed number of somatic cells, invariance in the topology of their cell lineage provides a powerful opportunity to interrogate developmental events with empirical repeatability across individuals. Studies of embryonic development using the nematode Caenorhabditis elegans have been drivers of discovery.

Automated Cell Lineage Reconstruction using Label-Free 4D Microscopy.

Here we describe embGAN, a deep learning pipeline that addresses the challenge of automated cell detection and tracking in label-free 3D time lapse imaging. embGAN requires no manual data annotation for training, learns robust detections that exhibits a high degree of scale invariance and generalizes well to images acquired in multiple labs on multiple instruments.

Influence of environmental temperature on mouth-form plasticity in Pristionchus pacificus acts through daf-11-dependent cGMP signaling.

Mouth-form plasticity in the nematode Pristionchus pacificus has become a powerful system to identify the genetic and molecular mechanisms associated with developmental (phenotypic) plasticity. In particular, the identification of developmental switch genes that can sense environmental stimuli and reprogram developmental processes has confirmed long-standing evolutionary theory. However, how these genes are involved in the direct sensing of the environment, or if the switch genes act downstream of another, primary environmental sensing mechanism, remains currently unknown.

Steroid hormone pathways coordinate developmental diapause and olfactory remodeling in Pristionchus pacificus.

Developmental and behavioral plasticity allow animals to prioritize alternative genetic programs during fluctuating environments. Behavioral remodeling may be acute in animals that interact with host organisms, since reproductive adults and the developmentally arrested larvae often have different ethological needs for chemical stimuli. To understand the genes that coordinate the development and host-seeking behavior, we used the entomophilic nematode Pristionchus pacificus to characterize dauer-constitutive mutants (Daf-c) that inappropriately enter developmental diapause to become dauer larvae.

Evolution of neuronal anatomy and circuitry in two highly divergent nematode species.

The nematodes and populate diverse habitats and display distinct patterns of behavior. To understand how their nervous systems have diverged, we undertook a detailed examination of the neuroanatomy of the chemosensory system of . Using independent features such as cell body position, axon projections and lipophilic dye uptake, we have assigned homologies between the amphid neurons, their first-layer interneurons, and several internal receptor neurons of and We found that neuronal number and soma position are highly conserved.

A species-specific nematocide that results in terminal embryogenesis.

Nematode-insect interactions are ubiquitous, complex and constantly changing as the host and nematode coevolve. The entomophilic nematode is found on a myriad beetle species worldwide, although the molecular dynamics of this relationship are largely unknown. To better understand how host cues affect embryogenesis, we characterized the threshold of sensitivity to the pheromone ()-7-tetradecen-2-one (ZTDO) by determining the minimum exposure duration and developmental window that results in embryonic lethality.

The bacterial community of entomophilic nematodes and host beetles.

Insects form the most species-rich lineage of Eukaryotes and each is a potential host for organisms from multiple phyla, including fungi, protozoa, mites, bacteria and nematodes. In particular, beetles are known to be associated with distinct bacterial communities and entomophilic nematodes. While entomopathogenic nematodes require symbiotic bacteria to kill and reproduce inside their insect hosts, the microbial ecology that facilitates other types of nematode-insect associations is largely unknown.

A host beetle pheromone regulates development and behavior in the nematode Pristionchus pacificus.

Nematodes and insects are the two most speciose animal phyla and nematode-insect associations encompass widespread biological interactions. To dissect the chemical signals and the genes mediating this association, we investigated the effect of an oriental beetle sex pheromone on the development and behavior of the nematode Pristionchus pacificus. We found that while the beetle pheromone is attractive to P.

Conserved behavioral and genetic mechanisms in the pre-hatching molt of the nematode Pristionchus pacificus.

Background: During development, juvenile nematodes undergo four molts. Although the number of molts appears to be constant within the Nematoda, the timing of the first molt can occur either before or after hatching. A previous study indicates that, as in some parasitic nematode lineages, a pre-hatching juvenile stage also exists in Diplogastrid nematodes.

The cGMP signaling pathway affects feeding behavior in the necromenic nematode Pristionchus pacificus.

Background: The genetic tractability and the species-specific association with beetles make the nematode Pristionchus pacificus an exciting emerging model organism for comparative studies in development and behavior. P. pacificus differs from Caenorhabditis elegans (a bacterial feeder) by its buccal teeth and the lack of pharyngeal grinders, but almost nothing is known about which genes coordinate P.

RNAi mediated gene knockdown and transgenesis by microinjection in the necromenic Nematode Pristionchus pacificus.

Although it is increasingly affordable for emerging model organisms to obtain completely sequenced genomes, further in-depth gene function and expression analyses by RNA interference and stable transgenesis remain limited in many species due to the particular anatomy and molecular cellular biology of the organism. For example, outside of the crown group Caenorhabditis that includes Caenorhabditis elegans, stably transmitted transgenic lines in non-Caenorhabditis species have not been reported in this specious phylum (Nematoda), with the exception of Strongyloides stercoralis and Pristionchus pacificus. To facilitate the expanding role of P.

Dual roles of the bZIP transcription factor PERIANTHIA in the control of floral architecture and homeotic gene expression.

Flowers develop from floral meristems, which harbor stem cells that support the growth of floral organs. The MADS domain transcription factor AGAMOUS (AG) plays a central role in floral patterning and is required not only for the specification of the two reproductive organ types, but also for termination of stem cell fate. Using a highly conserved cis-regulatory motif as bait, we identified the bZIP transcription factor PERIANTHIA (PAN) as a direct regulator of AG in Arabidopsis.

Natural variation in Pristionchus pacificus insect pheromone attraction involves the protein kinase EGL-4.

The geographical mosaic theory of coevolution predicts that different local species interactions will shape population traits, but little is known about the molecular factors involved in mediating the specificity of these interactions. Pristionchus nematodes associate with different scarab beetles around the world, with Pristionchus pacificus isolated primarily from the oriental beetle in Japan. In particular, the constituent populations of P.

Species-specific recognition of beetle cues by the nematode Pristionchus maupasi.

The environment has a strong effect on development as is best seen in the various examples of phenotypic plasticity. Besides abiotic factors, the interactions between organisms are part of the adaptive forces shaping the evolution of species. To study how ecology influences development, model organisms have to be investigated in their environmental context.

The nematode Pristionchus pacificus (Nematoda: Diplogastridae) is associated with the oriental beetle Exomala orientalis (Coleoptera: Scarabaeidae) in Japan.

Pristionchus pacificus has been developed as a nematode satellite organism in evolutionary developmental biology. Detailed studies of vulva development revealed multiple differences in genetic and molecular control in P. pacificus compared to the model organism Caenorhabditis elegans.

Chemoattraction in Pristionchus nematodes and implications for insect recognition.

Nematodes and insects are the two dominant animal taxa in species numbers, and nematode-insect interactions constitute a significant portion of interspecies associations in a diversity of ecosystems. It has been speculated that most insects represent mobile microhabitats in which nematodes can obtain food, mobility, and shelter. Nematode-insect associations can be classified as phoretic (insects used for transportation, not as food), necromenic (insect used for transportation, then carcass as food), and entomopathogenic (insect is killed and used as food).

Pristionchus pacificus: a well-rounded nematode.

Nematodes pervade Earth's biosphere and occupy innumerable ecological niches. The role of Caenorhabditis elegans as a model for developmental processes has encouraged us to cultivate a second nematode, Pristionchus pacificus, as a comparative counterpoint to address questions in development, behavior and ecology in nematode evolution. We hope that this endeavor, now more than a decade underway, will allow us to project findings onto other comparative models for biological processes.

Cultivation of the rhabditid Poikilolaimus oxycercus as a laboratory nematode for genetic analyses.

Vulva formation is a paradigm for evolutionary developmental biology in nematodes. Not only do the number of vulval precursor cells (VPCs) differ between members in the Rhabditidae and Diplogastridae, they are also sculpted via different developmental mechanisms, either by cell fusion in most Rhabditidae or by programmed cell death in the Diplogastridae. In this context, the species Poikilolaimus oxycercus is the only known species in the family Rhabditidae to have a subset of the Pn.

Regulatory elements of the floral homeotic gene AGAMOUS identified by phylogenetic footprinting and shadowing.

In Arabidopsis thaliana, cis-regulatory sequences of the floral homeotic gene AGAMOUS (AG) are located in the second intron. This 3-kb intron contains binding sites for two direct activators of AG, LEAFY (LFY) and WUSCHEL (WUS), along with other putative regulatory elements. We have used phylogenetic footprinting and the related technique of phylogenetic shadowing to identify putative cis-regulatory elements in this intron.