Cytogenetical and biochemical investigations of common oak (Quercus robur L.) were applied in order to find suitable markers in bioindication of oak populations. In cytogenetical analyses the chromosome aberration and mitotic index were recorded. Chromosome banding, B-chromosomes, location and number of nuclear organizer regions were indicated using Giemsa C-banding method, fluorescence staining and silver impregnation. In biochemical analyses SDS-electrophoresis of soluble proteins and isoelectric focusing of isoperoxidases were used.

A plant test system by the classification of chromosome aberration in the root tip meristems of young spruce plants (Picea abies (L.) Karst.) has been used to study the environmental influence on the genetic material of trees at natural sites and under defined conditions of greenhouses and open-top chambers. All our results suggest that this plant test system is a valuable tool in environmental monitoring.

Annual research has proven that the level of the so called natural cytogenetic damage to Norway spruce in Slovenia has been correctly estimated at 8. The results of cytogenetic bioindication calculated in accordance with this level show that average cytogenetic damage in the period from 1985 to 1992 enable us to determine environmental influences on the expression of cytogenetic damage.

The analysis of the frequencies of chromosome breaks and gaps on the pike - Esox lucius L. individuals from different locations collected in two consecutive years, were showed the highest values that were above the level of spontaneous (under the level of 3%) changes. Frequences of changes in fish Esox lucius L. were higher than the level of the presumed critical zone (3.0-3.5%) at locality of Danube by Visnjica and within the zone by Grocka. In consecutice years in river Tamis by Pancevo, both obtained values of chromosomal changes in this fish also were above the critical zone. Physicochemical water analyses were shown high level of organic contamination and concentration of phenols above MDK values for the 1st, 2nd water categories which argued obtained cytogenetic results. The localities obviously has a risk of being permanent or periodical contaminated with genotoxic agents.

The analysis of breaks and gaps frequences in the fish species Alburnus alburnus from different localities of rivers Kolubara, Sava and Danube, were showed the highest values that were above the presumed critical zone (3.0-3.5% of changes). At some of localities examined in May and October 2008, these values were much more elevated that the level of spontaneous changes normally seen in the controls in laboratory animals and in fish of relatively clean waters. Results that were obtained for these localities indicate to periodical or permanent contamination with genotoxic agents.