Molecular cytogenetics is a branch of biology in which nucleic acid and other cytological molecules which being involve in genetic inheritance are studied.
In eukaryotes nucleus consist DNA as genetic material which have different components like chromatin, nucleosomes, histone etc.
Nucleolus also have important role. Various techniques are now available to measure the amount of genome, number and position of genes and many other such type of work for the research and applicability purposes.
Breeding programmes aiming at transferring desirable genes from one species to another through interspecific hybridization and backcrossing often produce monosomic and disomic addition as intermediate crossing products.
Such aneuploids contain alien chromosomes added to the complements of the recipient parent and can be used for further introgression programmes, but lack of homoeologous recombination and inevitable segregation of the alien chromosome at meiosis make them often less ideal for producing stable introgression lines.
Monosomic and disomic additions can have specific morphological characteristics, but more often do they need additional confirmation by molecular marker analyses and assessment by fluorescence in situ hybridization with genomic and chromosome specific DNA as probes.
Their specific genetic and cytogenetic properties make them powerful tools for fundamental research elucidating regulation of homoeologous recombination, distribution of chromosome specific markers and repetitive DNA sequences, and regulation of heterologous gene expression.
In above chapter it has been tried to present the major characteristics of such interspecific aneuploids highlighting their advantages and drawback for breeding and fundamental research.
Therefore present chapter is being prepared to enlighten the role of nucleus in genetics along with techniques of genetic engineering which are also helpful to improve the quality of plants of agricultural, horticultural importance.
C-value genomic content in a haploid cell which is related to genome size and varies organism to organism,
The Cot curve (an S-shaped curve) is obtained by plotting the fraction of single-stranded DNA remaining (C/C0) as a function of the logarithm of the product of the initial concentration and the elapsed time,
Eukaryotic DNA consists of at least three types of sequences nonrepetitive (unique-sequence DNA), moderately repetitive DNA, highly repetitive DNA,
Restriction techniques involve methods for locating specific DNA sequences, cutting DNA at precise locations, amplifying a particular DNA sequence, mutating and joining DNA fragments to produce desired sequences and procedures for transferring DNA sequences into recipient cells,
A multigene family involves members of a family of related proteins encoded by a set of similar genes. Multigene families are believed to have arisen by duplication and variation of a single ancestral gene,
In situ hybridization techniques locate specific nucleic acid sequences in cells or on chromosomes,
The ultimate goal of gene mapping is to clone genes, especially disease genes. Once a gene is cloned, we can determine its DNA sequence and study its protein product,
Computer programmes are very helpful to analyse the karyotype and chromosomal information,
Chromosome microdissection is a specialized way of isolating specific regions by removing the DNA from the band and making that DNA available for further study (microcloning),
Flow cytometry is very fast and informative, quantitative and qualitative analysis method which objects include chromosomes and nuclei,
Alien gene transfer is aiming to improve the crop quality by using the different properties of plant like heterosis, hybrid vigour etc.