First Section: Amorphonostoc. Representatives of these sections are characterized by microscopic co

MATERIALS COLONY. The genus Nostoc is particularly characterized by the appearance of prominent education colonies are very different, but often permanent, form. In addition to these qualities genus is characterized by the gasification sare with threads inside the colony where the co sees only the perimeter of the colony, as well as spores that occur in bursts. filmkedjan Colonies are soft or hard, often very large. While young people have a globular shape, and later can have a different shape or colonies impersonal. Colonies filmkedjan were on the periphery of wrapped more or less soft periderm filmkedjan or without him. When moist colonies are usually dark olive green in color, although they may be almost yellow to brown. When dry usually turn black.
STUFF THE END. Stitches are all its length equal to the width or less narrow with heterociste. Built between filmkedjan the cylindrical, rarely barrel to almost spherical cells. Variations in size and shape of cells are sometimes obvious and within the same species, and do not represent a significant taxonomic character. filmkedjan Vegetative cells are usually blue-green or olive green color. Protoplasm contains filmkedjan 70% to 85% water. Stitches are usually in the colony density and without any schedules arranged, and rarely have a radial arrangement. Possess a thick mucous layer that in parts of the threads that are in the interior of the colony gasified and can be preserved in the end parts which are located in the peripheral filmkedjan parts of the colony. Some stitches are full in the central parts of the colony, so they can have a whole layer vanish in a homogeneous mass colonies. Trichomes that are found all along the peripheral parts of the colonies have fully preserved mucosal layer. Heterociste are intercalary, single or educate a series of several heterocista. Only when forming hormogonija heterociste can be found at the ends of trichomes. Akineti in trichomes usually allocated to build a series, and the rare individual. Usually ellipsoidal and slightly filmkedjan larger than vegetative cells. The representatives of the genus Nostoc trichomes akineti are usually found midway between the two heterociste. This is an important taxonomic character to distinguish the representatives of the genus Nostoc representatives of the genus Anabaena, in which akineti usually located near heterociste. An interesting phenomenon is that sometimes nearly all cell trichomes transformed into Akin. Hormogonije educate sporadically from any end of the colony. They may arise tearing končastog body, disintegration heterocisti, or akineta from which emerges a new hormogonija.
ECOLOGY. Most species of the genus Nostoc inhabits stagnant, slow-flowing or rarely moderately brzotekuće fresh water. Often found on different surfaces and objects in the water, often with epiphytic. Some representatives are also out of the water. The most commonly on wet surfaces, in soil, and sometimes as symbionts of plants or as fotobionti in lichen. To date, none of the species of the genus Nostoc is not recorded in the salty waters. Species of this genus are able to bind atmospheric nitrogen to participate in improving soil quality. Representatives of the genus Nostoc have a specific vegetative life cycle during which there are several characteristic phases. Some species of this genus are used in human food, since they contain proteins and vitamin C.
TAXONOMY. Although the genus is known almost 250 years and is now under the care made significant revisions. To date, approximately 200 known species within filmkedjan this genus, although it is assumed to be described many species as tropical filmkedjan and subtropical areas in general have not been studied nearly as far as this genus of blue-green prokaryotes. In older classification systems by several authors attempted to divide the fruit into smaller wholes. However, today's understanding of gender filmkedjan does not define additional categories within this genus, so this opinion filmkedjan accepts in this text. He also performed and differentiation of species in the lower categories filmkedjan by different authors in different ways. It should be borne in mind that many species were grown in laboratory conditions differ significantly from representatives of these species collected from natural habitats. Still being briefly explained the most famous attempt to divide the genus into sections which proposed Jelenkina. He 1938th as part of the genus Nostoc four different sections filmkedjan based on the morphology of colonies:
First Section: Amorphonostoc. Representatives of these sections are characterized by microscopic colonies or their clusters. Colonies rarely reach up to half a millimeter in diameter. Shrouded in the soft mucous layer called the periderm. Colonies are individual or flowing in large numbers in a faceless filmkedjan mass of mucous.
Second Section: Sphaeronostoc. Colonies representative of this section are mainly macroscopic and range 1-55 mm in diameter. Usually they are more or less spherical, rarely ellipsoid, and shrouded the hard periderm.
3rd Section: Nematonostoc. Representatives of these sections have a strong, fibrous slimy colonies that have macroscopic filmkedjan size and shrouded the hard periderm. Within filmkedjan this section differs only kind of nose