Cytogenetic Characterisation of Nattukuttai - A Non-descript Cattle Population of Tamil Nadu

Background: Nattukuttai is a small-sized cattle population, native to north-eastern districts of Tamil Nadu. In light of the ongoing research on genetic characterisation of cattle genetic resources of India, the present study was undertaken with the objective of cytogenetic characterisation of Nattukuttai cattle, which is imperative for its conservation and genetic implications to breeding programs. Methods: Blood samples from ten Nattukuttai cattle (five males and five females) were utilized to study the chromosome profile through short-term lymphocyte culture method. Good metaphase spreads were selected for estimation of the relative length, arm ratio, centromeric index and morphological index. Result: The diploid number was 60. All the 29 pairs of autosomes and Y-chromosome were acrocentric while X-chromosome was sub-metacentric. The mean relative length of autosomes ranged from 5.24 ±0.08 to 1.90±0.06. X-chromosome was the largest in the karyotype (5.64±0.12), while the Y-chromosome was the smallest (1.85±0.03). The arm ratio, centromeric index and morphological index were 1.98±0.02, 0.33±0.03 and 4.06±0.4 respectively. The study revealed that the chromosome architecture of Nattukuttai cattle was similar to that of other breeds of Zebu cattle.

Comparison of chromosomal architecture of Sahiwal and crossbred Sahiwal cattle

The karyological investigation using 16 purebred Sahiwal and 16 Jersey X Sahiwal cattle (8 males and 8 females of each genetic group) revealed the diploid chromosome number to be 60. All the 29 pairs of autosomes were acrocentric, while the X – chromosome was sub-metacentric in both the genetic groups. Acrocentric Y chromosome of Sahiwal differed from small submetacentric chromosome of Jersey X Sahiwal cattle in its morphology. The relative length of autosomes ranged from 1.74 ± 0.01 to 5.28 ± 0.02 in Sahiwal and from 1.72 ± 0.01 to 5.26 ± 0.02 in Jersey X Sahiwal crosses. X – Chromosome was the second largest chromosome in both the genetic groups. The contribution of X and Y chromosomes to the total genome were 5.07 and 1.99 per cent to the total genome in Sahiwal and 5.06 and 2.20 per cent in Jersey X Sahiwal cattle, respectively. The arm ratio, centromeric index and morphological index for the X-chromosome of Sahiwal and Jersey X Sahiwal cattle were 1.89, 0.35, 2.87 and 1.84, 0.36, 2.76, respectively. The arm ratio, centromeric index and morphological index for the Y-chromosome of Jersey X Sahiwal cattle were 1.63, 0.35 and 1.41, respectively.

A karyological study of the genus Pnigalio Schrank (Hymenoptera: Eulophidae): Assessing the taxonomic utility of chromosomes at the species level

We provide a karyological study of 12 species of the genus Pnigalio in an attempt to evaluate the taxonomic utility of karyotypes at the species level. For all species of Pnigalio examined the number of chromosome was 2n=12. Karyotype formulae presented mainly metacentric and submetacentric chromosomes, although a pair of acrocentrics or subtelocentrics, shorter than biarmed chromosomes, was present in some species. The analysis of karyotypes of Pnigalio showed frequent but not general interspecific variability of the chromosome traits. Although most of the studied species revealed concordance between morphological and karyological characters (centromeric index and relative length), two other categories have been identified: morphologically distinct species without reciprocal differences in karyotype structure, and morphologically similar species that strongly differ in chromosomal characters.

Comparative Analysis of Karyotypes from the Strezelecki Ranges Race of the Complex Eucalyptus globulus Labill. ssp. globulus (Myrtaceae) and a Population in Central-Southern Chile

Summary This study presents information on karyotypes of the Strezelecki Ranges race, referred to in previous studies as Jeerelangs (Victoria, Australia), of the complex Eucalyptus globulus. ssp globulus and another from Central- Southern Chile (Contulmo). The chromosomes counted (2n = 22) are fairly small-sized and found within the size ranges reported by other authors. The chromosome measurements, done with the Micromeasure program, indicate that the Strezelecki Ranges lineage has a relatively large genome (Total Chromosome Length = 8.94%) as compared to measurements of local lineages (Chile). This could be explained by genetic recombinations resulting from the successive hybridizations reported for this race. The data obtained for both lineages reveal a set of markedly metacentric chromosomes with a centromeric index between 0.44 and 0.46.

The Chromosome Complement of Procerodes Dohrni (Tricladida: Maricola)

A karyometric analysis of the diploid complement of Procerodes dohrni (Turbellaria: Tricladida) was carried out on mitoses from regenerative blastema. P. dohrni has seven pairs of homologous chromosomes. Chromosome lengths decrease gradually and homologous pairs cannot be grouped. With reference to centromere position, chromosomes 1, 2, 3, 4 and 6 are metacentric, their centrometric indices vary from 46·74 to 39·82, while chromosomes 5 and 7 are submetacentric, their centromeric index being 34·63 and 29·86 respectively.

The karyology of the genus Procerodes (Tricladida: Maricola) in British waters

A karyometric analysis of the diploid complement of two species of the genus Procerodes (Tricladida: Maricola), both from British waters, has been carried outThe diploid number of Procerodes littoralis, 2n = 14, was established on mitosis from regenerative blastema and the haploid number n = 7 from spermatocyte I stages. All the chromosomes are metacentric, their centromeric index varying from 47·91 in the chromosome 5 to 38·39 in the chromosome 4.