8 results match your criteria: "The Netherlands. m.k.richardson@biology.leidenuniv.nl[Affiliation]"

Background: Regeneration is the replacement of lost or damaged tissue with a functional copy. In axolotls and zebrafish, regeneration involves stem cells produced by de-differentiation. These cells form a growth zone which expresses developmental patterning genes at its apex.

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Background: The explosive radiation and diversification of the advanced snakes (superfamily Colubroidea) was associated with changes in all aspects of the shared venom system. Morphological changes included the partitioning of the mixed ancestral glands into two discrete glands devoted for production of venom or mucous respectively, as well as changes in the location, size and structural elements of the venom-delivering teeth. Evidence also exists for homology among venom gland toxins expressed across the advanced snakes.

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Wilhelm His Sr. and the development of paraffin embedding.

Pathologe

November 2021

Institute of Biology, IBL, Sylvius Laboratorium, Leiden University, Sylviusweg 72, 2333BE, Leiden, The Netherlands.

Paraffin histology is one of the most important and commonly-used laboratory techniques in diagnostic histopathology. The discovery of paraffin embedding is often attributed to the pathologist Edwin Klebs. Klebs was following the lead of Stricker, who embedded embryos in a mixture of hot stearin and white beeswax.

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Rationale: The endocannabinoid system (ECS) comprises the cannabinoids anandamide and 2-arachidonoylglycerol and the cannabinoid receptors 1 and 2 (Cnr1 and Cnr2). The function of these receptors in relation to zebrafish larval behavior is poorly understood, even though the zebrafish larva has become a versatile animal model in biomedical research.

Objectives: The objective of the present study is to characterize the function of Cnr1 and Cnr2 in relation to behavior in zebrafish.

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Snake genome sequencing is in its infancy-very much behind the progress made in sequencing the genomes of humans, model organisms and pathogens relevant to biomedical research, and agricultural species. We provide here an overview of some of the snake genome projects in progress, and discuss the biological findings, with special emphasis on toxinology, from the small number of draft snake genomes already published. We discuss the future of snake genomics, pointing out that new sequencing technologies will help overcome the problem of repetitive sequences in assembling snake genomes.

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A phylotypic stage for all animals?

Dev Cell

May 2012

Institute of Biology Leiden, Leiden University, Sylvius Laboratory, Sylviusweg 72, 2333 BE, Leiden, The Netherlands.

A new study in this issue of Developmental Cell (Levin et al., 2012) uses comparative transcriptomics and reveals a stage in nematode development that is enriched for developmental patterning genes. The molecular profile of this phylotypic stage shows similarities with those of vertebrates and flies.

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Developmental anatomy of lampreys.

Biol Rev Camb Philos Soc

February 2010

Institute of Biology, Leiden University, Kaiserstraat 63, 2311GP Leiden, The Netherlands.

Lampreys are a group of aquatic chordates whose relationships to hagfishes and jawed vertebrates are still debated. Lamprey embryology is of interest to evolutionary biologists because it may shed light on vertebrate origins. For this and other reasons, lamprey embryology has been extensively researched by biologists from a range of disciplines.

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The tetrapod limb provides several examples of heterochrony-changes in the timing of developmental events. These include species differences in the sequence of skeletal chondrogenesis, in gene transcription in the developing limbs, and in the relative time at which forelimb and hind limb buds develop. Here, we examine (i) phylogenetic trends in limb heterochrony; (ii) changes in developmental mechanisms that may lead to heterochrony; and (iii) the possible role that heterochrony plays in generating adaptive traits.

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