Cytogenetic investigations in Cladophora

Abstract

The cells of Cladophora are multinucleate. Mitosis and meiosis are of the classical type. Different kinds of abnormal meiosis have been observed. Probably the nuclear membrane persists during the divisions. A clear zone, with an evident demarcation against the cytoplasm, is usually seen around the chromosomes at metaphase. Generally there is an alternation of generations. Parthenogenetical development of biflagellate zooids occurs. The haploid zooids give rise to plants, in which haploid nuclei are predominant in the vegetative cells. Before the formation of zooids there is a diploidisation of the nuclei. Meiosis then takes place and biflagellate zooids are produced. The basic chromosome number is x = 6. Usually homologous chromosomes are paired in the prophase and metaphase of mitosis. Three different classes of chromosome length have been distinguished – small, medium and large. Many species representing one or other of the three classes occur. Aneuploid and euploid nuclei appear occasionally. Aneuploid species have not been observed. Polyploid series, on the other hand, are found in most of the species. 1970 Hereditas