What’s in a rat?

The role of rodents in biomedical research is invaluable. Rodents, such as mice and rats, are the most commonly used mammals in biomedical research because of their anatomical, physiological and genetic similarities to humans. 

Scientists are able to genetically adapt mice to study a disease, for example by removing certain genes or by inserting (human) genes that are at the basis of certain disorders. For example, breast cancer can be simulated in mice to study the mechanisms of cancer and to test treatments. Mice and rats are also often used in behavioral studies to test, for example, treatments for memory loss in dementia.

Rodents are used in countless research areas, from cancer to immune diseases, heart disease, hypertension, metabolic and hormonal disorders, diabetes, obesity, osteoporosis, glaucoma, blindness, deafness, psychiatric disorders such as depression and schizophrenia, and neurodegenerative disorders such as Alzheimer's disease, Parkinson's and ALS.

The images taken with the new Moticam S6 camera show a cross-section with details through the upper body of the rat, just above the splice of the trachea into the two bronchi. The beautiful coup shows the various body parts in this cross section, some of which are indicated below.

With thanks to Cees Koopman, veterinarian.

© willemsmicroscope.com

You need a unique sample for your teaching lesson? Have a look into your rain gutter.

It’s real life: Sometimes the good things are closer than expected. Your rain gutter not only disposes the water from your roof, but also collects detritus from its colonizers such as mosses and lichens. It’s an extreme biotope: wet and cold in winter, even freezing, dry and hot in summertime. Only few microorganisms survive this extreme change.

One of them just recently came into spotlight. In April 2019 the Israeli space probe Beresheet* crashed onto the surface of the moon; 585kg of weight caused a small caldera. Aboard there were several thousands of Tardigrada, also known like Water Bears. As they had been transported in dried condition, and apparently no water seems to be available on the moon by fog or rain, the probability of life on the moon in 2020 still is quite low.

No need to travel so far to meet this astonishing group of animals. Take a sample of detritus from your rain gutter, if dry, first let it soak in rainwater. After a few days at room temperature it is time to check the water sample. Tardigrada may be fixed on the surface of moss leaves, so it makes sense to place a moss stem on the glass slide and to strip off the leaves by using two tweezers, one fixing the stem, one stripping off the leaves against the direction of growth.

A dead Tardigrada: Sectoral structure of body clearly visible.

Honey - Try to find out its origin

Honey is one of the oldest food products. Cave paintings from the stone age give witness of how the product of wild bees has been used as the first sweetener, containing lots of positive ingredients for a general healing effect.

Nowadays honey is part of the food industry with its profit orientated mechanisms. Price is an issue, and the cold hurled product needs careful attention and efforts for maximum quality.

The origin of a product in general is essential for tracing the manufacturing steps. Latest since BIO became a quality issue in food industry, foodstuff testing laboratories are looking for hints to find out the nectar and honeydew sources which are the basis of honey. Pollen residuals within the honey give a clear indication about the region of origin. In Europe, honey from Central America is widespread, but not always clearly indicated. Eastern Europe and China are playing an important role as honey producers.

Once the pollen is detected and allocated to a defined plant species, it is easy to debunk imposters. Pollen from tropic plants found in a honey sample declared as a Central European product – a microscope will be the necessary tool to find out. Brightfield illumination is the required method, Phase contrast is not optimal as the pollen grains clearly have a significant 3D dimension, too thick for applying this contrast method. Simple POL contrast may help to find the isolated pollen grains within the honey sample.

Some examples from the Middle European flora:

Leontodon spec.

A pest on grapes

Uncinula necator or powdery mildew, a basidiomycete, is a pest on grapes. Its septate hyphae forms a mycelium on the surface of the leaves similar to a spider web. Special hyphal branches, the haustoria, penetrate the host cells to absorb food substances, thereby weakening the grape and reducing the harvest.

A medicinal parasite

Mistletoe (Viscum album), sinkers in host tissue, longitudinal.

The evergreen, spherical shrub of about 1 m in diameter grows on different trees. As a semi-parasite the mistletoe assimilates with its leaf green. The sinkers of the mistletoe penetrate deep into the wood body of the host plants and withdraw only water and mineral salts from the host, but this causes the part above the infestation site to suffer. The opposite, oblong-ovate leaves evaporate only a little water due to their leathery texture.