Microscopy Solutions for Sample Preparation

Many disciplines – such as developmental biology, molecular biology, embryology, plant sciences and neurobiology – work with model organisms that often need special handling or preparation before further examinations such as genetic studies.

Model organisms can be bacteria, fungi, plants or animals. Ideally, model organisms should exhibit certain characteristics:

  • Share many genes with humans
  • Small size and easy to grow in the lab
  • Visible congenital traits
  • Sequenced genome available
  • Easy genetic manipulation
  • Genetically tractable
  • Short generation times and life cycle

Examples of common model organisms:

Caenorhabditis elegans

Caenorhabditis elegans germline. Acquired with ZEISS Celldiscoverer 7, sample courtesy of S. Köhler, EMBL, Heidelberg, Germany

Field of Study

Characteristics

  • Developmental biology
  • Molecular biology
  • Physiology
  • Pharmacology
  • Toxicology
  • Transparent throughout lifetime
  • Rapid generation time (3 days)
  • Easy to manipulate

Drosophila melanogaster

Two color image of drosophila embryo. Acquired with ZEISS Axio Zoom.V16
Two color image of drosophila embryo. Acquired with ZEISS Axio Zoom.V16

Field of Study

Characteristics

  • Genetics
  • Developmental biology
  • Neuroscience
  • Easy to grow and maintain
  • Short generation time (8-14 days)
  • 4 chromosome pairs
  • Easy to manipulate

Zebrafish

Zebrafish embryo in oblique transmitted light. Acquired with ZEISS Stemi 508
Zebrafish embryo in oblique transmitted light. Acquired with ZEISS Stemi 508

Field of Study

Characteristics

  • Embryology
  • Developmental biology
  • Molecular biology
  • Toxicology
  • Neurobiology
  • Share of 70% of genes with humans
  • Easy to breed
  • Transparant
  • Easy to manipulate

Xenopus laevis, Xenopus tropicalis

mHIP Xenopus where mRNA has been injected (Hedgehog Interacting Protein). Acquired with ZEISS SteREO Discovery. © Dr. Andres Collazo, Inner Ear Development Group, House Ear Institute, Los Angeles, USA
mHIP Xenopus where mRNA has been injected (Hedgehog Interacting Protein). Acquired with ZEISS SteREO Discovery.

Field of Study

Characteristics

  • Embryology
  • Developmental Biology
  • Cell Biology
  • Neurobiology
  • Embryos easily accessible
  • 10000 oocytes
  • Large oocytes/embryos
  • Eeasy to manipulate

Mus musculus

Mouse brain. Acquired with ZEISS Axio Zoom.V16
Mouse brain. Acquired with ZEISS Axio Zoom.V16

Field of Study

Characteristics

  • Neurobiology
  • Genetics
  • Genomics
  • Pharma
  • Clinical Research
  • Relatively short generation time (~10 weeks)
  • 99% homolog to humans
  • Disease model
  • Genetically tractable
  • Easy to manipulate

Rattus norvegicus

Cultured rat hippocampal neuron © Dr. Stefanie Kaech and Gary Banker, OHSU, Oregon, USA
Cultured rat hippocampal neuron

Field of Study

Characteristics

  • Neuroscience
  • Toxicology
  • Genetics
  • Gnomics
  • Pysiology
  • Disease model
  • Source for primary neurons
  • Larger organs

Axolotl

This axolotl forearm has been cleared in ethyl cinnamate. Acquired with ZEISS Lighsheet 7. Sample courtesy of W. Masselink, Tanaka lab, Research Institute of Molecular Pathology, IMP. Image courtesy of P. Pasierbek, K. Aumayr, IMP BioOptics, Vienna, Austria.

Field of Study

Characteristics

  • Regenerative medicine
  • Developmental biology

Can regenerate its

  • Tail
  • Limbs
  • Parts of its brain…

Arabidopsis thaliana

Arabidopsis root thread – DIC superimposed fluorescence
Arabidopsis root thread – DIC superimposed fluorescence

Field of Study

Characteristics

  • Developmental Biology
  • Cell Biology
  • Molecular Biology
  • Genetics
  • Plant Physiology
  • Small genome
  • 5 chromosome pairs
  • Many mutants
  • Easy to manipulate

C. elegans (a nematode), zebrafish Danio rerio and the fruit fly Drosophila melanogaster are widely used, respectively, in worm labs, zebrafish labs and fly facilities. These model organisms need to be routinely sorted, picked, counted, manipulated, dissected, imaged and monitored during their development stages (e.g. egg, embryo, larva …). Stereo or dissecting microscopes are indispensable tools for these tasks.

Microscope Requirements

There are two types of stereo microscopes – Greenough and Common Main Objective (CMO) – each with its own special characteristics. The CMO-type provides certain advantages over the Greenough-type, particularly when it comes to illumination, fluorescence capabilities, digital image documentation and ergonomics. Greenough stereo microscopes, however, are more compact, highly integrated and economical in price.

Scientists and technicians can be supported in their daily routines by a 3D stereoscopic view combined with a large free-working distance and ergonomic features. These microscopes are perfect for mechanical manipulation, sorting, and general sample preparation. Stereo or zoom microscopes are also used preferentially for fluorescence screening of modified genotypes (for example, through CRISPR/Cas9 mediated mutations) in transgenic studies using markers such as the green (GFP) or red (RFP) fluorescent protein. Combining a large field of view with high resolution will speed up this process significantly.
Dissecting microscopes are also widespread in neuroscience – say, when dealing with larger vertebrate animals such as rats, which often serve as a source of primary cell cultures.

Application Examples

C.elegans in Stemi 508 reflected light double arm gooseneck, brightfield
C.elegans in Stemi 508 reflected light double arm gooseneck, brightfield
ZEISS Stemi 508 greenough stereo microscope, tail of zebrafish embryo in oblique transmitted light
ZEISS Stemi 508 greenough stereo microscope, tail of zebrafish embryo in oblique transmitted light
Drosphyla embryos acquired with ZEISS Stemi 508
Drosphyla embryos acquired with ZEISS Stemi 508
Fruit Fly (Drosophila Melanogaster) Embryos
Fruit Fly (Drosophila Melanogaster) Embryos
Spider Crab (Macrocheira kaempferi) Embryos
Spider Crab (Macrocheira kaempferi) Embryos