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Calendar . Subjects 2002

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Insects: Common fruitfly (Drosophila melanogaster).

Frontal view of the head of the ca. 2mm long fly, which swarms around ripe fruit in summer. Because of the giant chromosomes that are found in its larva and the frequent occurence of natural mutations, fruit flies are a favorite object of genetic study.

Scanning Electron Microscope, magnification 140:1
Insects: diptera: tsetse fly (Glossina spec.).

Transmits African sleeping sickness in human beings. The infectious stages of the Trypanosoma are injected into the skin with the saliva of the tse-tse fly when sucking. The minimum period for Trypanosoma development in the fly is about 20 days at medium tropical temperatures. A once infected fly remains infectious for the rest of its life (about 6 month).

Scanning Electron Microscope, magnification 25:1
Insects: butterflies: peacock butterfly (Inachis io).

Under strong enlargement the very filigree structure of the scales on butterfly wings is revealed. The scales allow light and radiant heat to penetrate while acting as inward insulation. The longitudinal ribbing of the scales causes the metallic shiser. The roof-shingle-like structure is striking.

Scanning Electron Microscope, magnification 260:1
Botany: transverse section of leaf, (cryofracture) black hellebore (Helleborus niger)

The black hellebore or Christmas rose has typical, dorsiventral leaves, i.e., front and back differ. The anatomical structure is clearly recognizable in the cross-section. The whole leaf is encapsulated by the cuticle (intense green), a covering that the under-lying epidermis cells form themselves by secreting hardening procutin. Embedded in the epidermis (brownish) are the stomata that permit CO2 intake and transpiration. Hairs are also formed by epidermis cells. (Protection against evaporation and radiation). Between the upper and lower epidermis is the mesophyll, which is divided into the palisade and spongy (lacunose) parenchyma. The palisade parenchyma (light green) is rich in chloroplasts (photosynthesis), the rod-shaped cells being closely clustered at right angles to the leaf surface. Intercellular spaces ensure gas exchange. The spongy parenchyma (dark green) has numerous intercellular spaces. The cells serve to remove assimilates to the vascular bundles (bluish) in this layer, and ensure gas exchange with the environment through the stomata. In the vascular bundle (blue-gray) water and nutrients are transported.

Scanning Electron Microscope, magnification 190:1
Zoology: worms: leech (Hirudo medicinalis).

The leech is one of the annelids, or segmented worms. They are blood-sucking, external parasites with suckers at both ends. They live in fresh water, and attack both cold-blooded and warm-blooded animals. Medical applications: for varicose veins and rheumatic diseases, and to regulate blood flow in the case of limb grafting (e.g. re-attached fingers). The leech produces the anticoagulant agent hirudin.

Scanning Electron Microscope, magnification 30:1
Zoology: insects: ant, antenna.

Ants communicate by means of their antennae. They palpate their conspecifics in rapid rhythmic progression. To permit optimum mobility, the feelers are attached by a ball-and-socket joint.

Scanning Electron Microscope, magnification 620:1
Viruses: T-phages on E. coli.

Phages sit on the bacterium and introduce their DNA. In the photo 3 different stages of infection are to be seen. Viruses have no metabolism at their own. They insert their DNA in other cells in order to use theit metabolism, thus imposing their own reproduction. There are 16 different phages known for E. coli.

Transmission Electron Microscope, magnification 126,000:1
Arachnida: Ticks: Rocky Mountain Wood Tick(Dermacentor andersoni).

The picture shows the mouthparts of an adult animal, seen from below. Ticks pass through 3 stages of development to the mature animal, and in each phase they have a different host animal (e.g., mouse, hare, human being, big game), of which they suck the blood. Ticks of the dermacentor type are often carriers rickettsias (bacteria), which can cause spotted fever (rickettsiosis), leading to death in 70% of cases.

Scanning Electron Microscope, magnification 150:1
Viruses: Filoviridae: Marburg Virus.

The name is derived from its filament-shaped appearance. It was discovered in 1967 as an extremely dangerous pathogen causing hemorrhagic fever (laboratory personnel in Marburg, Frankfurt, Belgrade). The infection leads to death within a few days. Course of the disease: heavy diarrhea, vomiting, internal bleeding through distruction of tissue. The mortality rate is well over 50%. No treatment is yet known.

Transmission Electron Microscope, magnification 120,000:1
Botany: Marigold (Calendula officinalis).

Pistil and petal. The flower contains active substances: essential oils, carotinoids, glycosides, resins, fats, waxes. Application as ointment: for wound healing, vein disorders, inflammation of the lymph vessels. As infusion for female complaints.

Scanning Electron Microscope, magnification 52:1
Botany: onion, root apex (Allium cepa), anaphase.

The picture shows a secretion through the root apex of an onion. A large number of active nuclei are to be seen. The final stage of a chromosome division - the anaphase - is visible in the center of the picture, the chromosomes are being drawn apart. On the left is a prophase, here the chromosomes are being disentangled. The surrounding nuclei are mostly in the incipient division stage, from interphase to prophase.

Light microscope, bright field, magnification 630:1
Insects: crab louse, pubic louse (Pthirus pubis).

Crab lice are biting-sucking insects. The picture shows an adult and a young animal. The animals cling to a hair with their characteristic legs. Crab lice are predominantly to be found in pubic hair, hardly ever in head hair. Mostly transmitted during sexual intercourse, they can survive only about 12 hours without host.

Scanning Electron Microscope, magnification 40:1
Bacteria: Enterobacteriaceae: intestinal bacterium (Escherichia coli).

E. coli ist ein wichtiges Darmbakterium. Es kann als Erreger von Harnwegs-, Gallenwegs-, Wund-, Apendix- und ähnlichen Infekten auftreten. Die Infektion erfolgt über Nahrung und Trinkwasser. Schmierinfektionen sind möglich. Behandlung: Chemotherapie und spezifischer Penicilline. E. coli ist ein in der Gentechnologie sehr häufig verwendetes Bakterium.

Transmission Electron Microscope, magnification 25,000:1
© copyright O. Meckes & N. Ottawa, eye of science
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