The chromosomes of 4 carnivorous species were prepared and karyotyped from a bone marrow. 3 species from family Canidae including the Red Fox (Vulpes vulpes), the domestic dog (Canis familiaris) and a wild dog (Lycaon pictus) have a diploid chromosome numbers and fundamental numbers of, 2n=38 and FN =72, 2n=78 and FN=80, 2n=38 and FN=68, respectively while the diploid number and fundamental number of Domestic cat (Felis catus) which belongs to the family Felidae are 2n=38 and FN=72. Although the 3 species of V. vulpes, L. pictus and F. catus have the 2n=38, they are clearly different in their chromosome morphology and G-banded karyotypes.
The genotoxic effect of lead acetate in male mice was investigated as measured by sister chromatid exchange (SCE), chromosomal aberration analysis in both somatic (bone-marrow) and germ cells (spermatocytes) and the sperm morphology assay. Intraperitoneal treatment with the lowest tested dose (25 mg kg-1 b.wt.) had no genotoxic effects at all points of treatment and its effect was the same as the control (non-treated). Lead acetate was found to be potent inducer of SCE's at the doses 50 and 100 mg kg-1 b.wt. where the mean frequency of SCE's reached 12.09 ±0.62/cell compared with 12.52±0.52 for mitomycin C (positive control). Lead acetate at the doses 50, 100, 200, 400 mg kg-1 b.wt. (single i.p.) increased the percentage of chromosomal aberrations significantly in mice bone-marrow as well as in mice spermatocytes. The intensity of the effect is a function of lead concentration. Moreover repeated dose treatment show higher percentage of chromosomal aberrations than single dose treatment. Morphological sperm head abnormalities increased significantly after treatment with the doses 50 and 100 mg kg-1 b.wt. with a dose dependent relationship indicating a specific genotoxic effect of lead acetate on testis with the higher dose (100 mg kg-1 b.wt.). In conclusion the results suggest that lead acetate is genotoxic at relatively high doses.
An analysis was made of C-banded karyotype of Acanthoscelides obtectus (Say) from Slovakia (Central Europe). The results indicate that the chromosome number is 2n=20 (the ancestral number for bruchid beetles). The males possess XY type of the sex-chromosome mechanism. The sex-chromosome mechanism in the females is, however, XX type. 5 pairs of autosomes are metacentric, 3 pairs are submetacentric and 1 pair is subtelocentric. The X chromosome is submetacentric and the Y subtelocentric. The sex chromosomes are the smallest elements of the set. The examined karyotype shows only pericentromeric position of constitutive heterochromatin in all autosomes and the sex chromosomes X and Y.
Wild samples of larvae of 6 new fruit fly species belonging to the Bactrocera dorsalis complex have been temporarily designated as species I, J, K, L, M and N, based on cytological evidence. The flies are also morphologically distinguishable as adults. The larvae of these species seem to specifically infest fruits of different host plants. Cytological examination of larvae of these new species has revealed distinct patterns of metaphase karyotypes on the basis of different amounts and distribution of constitutive heterochromatin in sex chromosomes and autosomes. Thus the mitotic karyotype of species I is somewhat similar to that of B. dorsalis and is classified into Group 1. On the other hand, species L, M and N exhibit mitotic karyotypes of Group 4 showing specific patterns of heterochromatin in the centromeric regions of the X chromosome. Species J and K show a general feature of the mitotic karyotype of Group 3, which exhibits distinctive patterns of heterochromatin in sex chromosomes. These findings support the important role of constitutive heterochromatin in karyotypic evolution of these members of the B. dorsalis complex. Such a gross difference in heterochromatin is also a useful tool in cytotaxonomic study of closely related species of the fruit flies of Thailand.
The cytogenetic analysis of Brachygalaxias gothei, B. bullocki and their hybrids showed differences in the number of biarmed and monoarmed chromosomes, as like as, in their c-banding patterns. The basic karyotype consists in 2n=40 with a FN=58 in B. gothei, and 66 in B. bullocki, and 2n= 38 + 1 and FN =51 in the hybrids. B. bullocki presents a larger quantity of constitutive hete-rochromatin than B. gothei, and present a polymorphism in the location of one pair of NOR. The taxonomic status of B. gothei is discussed in relation of chromosome results and the hybrid sterility.
A number of interchanges (>100) were induced with the help of gamma rays in a lentil cultivar (PL 639). Trisomics were also available in the progeny of one interchange heterozygote (T35); these were found to be trisomic for one of the two chromosomes involved in the interchange. For the identification and isolation of interchange homozygotes from the progeny of each interchange heterozygote, several progeny plants exhibiting 7 bivalents were crossed to normal plants. The resulting hybrids showing an association of 4 chromosomes were marked and their parental lines (that were progeny of interchange heterozygotes) were identified as interchange homozygotes. By using this approach, 15 interchange homozygotes were isolated. For the purpose of assembly of an interchange tester set, chromosomes involved in each of a number of interchanges were identified through intercrossing and karyotype analysis. 7 of the above 15 interchange homozygotes were subjected to intercrossing followed by meiotic analysis of hybrids. These 7 interchange stocks could be arranged in following three groups : (i) A set of 3 interchanges (T1, T11, T29) designated as Ta-b. (ii) Another set of 3 interchanges (T2, T3, T17) designated as Tc-d. (iii) A solitary interchange (T5) designated as Te-f. Further, for the identification of interchanged chromosomes in each of the interchange of the above tester set and in 7 other interchanges, their corresponding interchange homozygotes were subjected to simple karyotype analysis. In 4 of the 7 interchange homozygotes of the tester set, the interchanged chromosomes could be identified through altered chromosome morphology due to exchange of unequal chromosome segments. The results of intercrossing and karyotype analysis for chromosome identification were comparable and no discrepancy was observed. The altered chromosome morphology was also observed in the following 5 interchange homozygotes (not included in the tester set) : T9, T14, T15, T25, T44.
In the present study six specimens of Triportheus paranaensis from the Paraná river, in Corrientes (Argentina) were analyzed. All the specimens showed 2n=52 chromosomes with a karyotype formula composed of 24 M +22 SM +4 ST +ZZ (M/M) in males or ZW (M/SM) in females. The constitutive heterochromatin pattern was similar to those of other Triportheus species previously analyzed. Two chromosome pairs with NORs were detected. One of these is located in the telomeric region of a metacentric chromosome pair. This position was unreported for any other Triportheus species, constituting a chromosome marker for the species. The comparative analysis between our results and the available in the literature suggests that the karyotype diversification of the group would have mainly produced by chromosome pericentric inversions and translocations. These structural changes in addition to duplications and translocations of the nucleolar organizer regions, could have modified the karyotype formula preserving the diploid chromosome number.
Karyotypes of 34 species referred to 9 genera of 6 tribes and 4 subfamilies of Tenthredinidae are reported. Variation in karyotypes at different taxonomic levels is discussed. The haploid chromosome numbers are shown to range from 6 to 20 in the species studied whereas they range from 5 to 22 in the family as a whole. An ancestral chromosome number for Tenthredinidae is suggested to lie between n=6 and n=10. Some genera are discussed in terms of karyotype diversity. Possible pathways, in which karyotype evolution has proceeded in these genera and in Tenthredinidae as a whole, are discussed.
Chromosomal analysis of the 5 marine species, Cypraea pulchra (Gary 1824), C. isabella (Linnaeus 1758), C. turchus (Lamark 1810), C. carneola (Linnaeus 1758) and C. caurica (Linnaeus 1758) have been studied. The diploid chromosome number and fundamental number (FN) of these 5 species are 2n=52 (FN=66), 2n=56 (FN=64), 2n=64 (FN=70), 2n=70 (FN=86) and 2n=72 (FN=92) respectively. To the best of the authors knowledge, these results are reported for the first time in Egypt.
The genetic control of aposporous apomixis in Paspalum was investigated by determination of the reproductive mode of the progeny from a cross of the sexual, self-incompatible tetraploid, P. ionanthum by the facultative apomict, P. cromyorrhizon. One hundred and sixty-nine progeny were assessed using embryological analysis, of these, 127 were shown to produce aposporous embryo sacs whilst 42 were completely free giving a ratio of 3.02/1. Fourteen plants of the aposporous group showed a high level of female sterility and may be considered as being members of the non-aposporous group which would alter the ratio to 2.02/1. Selfing of the female parent produced 120 caryopses of which only 25 gave rise to flowering plants. Six of the latter showed occasional aposporous embryo sac formation. Cytological analyses of meiosis indicates that any interpretation of the genetic ratios must take into account disomic or tetrasomic inheritance in P. ionanthum and tetrasomic with random chromatid assortment in P. cromyorrhizon. On this basis the observed phenotypic ratios can be accommodated within a genetic model of the sexual female parent being of the genotype AAAa if tetrasomy applies or Aa if disomy, whilst the apomitic male is Aaaa. In this situation apospory requires the presence of at least two doses of the recessive allele together with a single copy of the wild type allele, homozygous recessive genotypes will be non-viable. Alternatively, a model of one dominant gene controlling apospory together with lethality of gametes carrying two copies of the gene may account for the results.
Chromosomal study was carried in the dividing root-tip cells of Cannabis sativa (Family : Cannabinaceae). The diploid chromosome number of this species is 2n=20. Karyotype analysis reveals that all the 9 chromosomes in female somatic cells are metacentric and 1 chromosome is submetacentric whereas the X and Y chromosome in male cells is sub-metacentric. The Y chromosome is longer than X chromosome. The third pair bears the satellite.
Karyological studies on 16 species of Vicia L., including 10 species from the Egyptian flora are presented. Chromosome counts are observed for two species for the first time (2n=10 in V cinerea and V nigra). A diploid number of 2n=10 (x=5) has been found in 4 species, 2n=12 (x=6) in 2 species and 2n=14 (x=7) was recorded in 10 species V. hirsuta was found to have 2 B-chromosomes. The karyotype in the examined species is more or less symmetric. However, considerable variations exist in chromosome size among the species studied. The results of the present study con-firm that x=7 may be considered the basic number in the genus.
Zamia angustifolia, Z. integrifolia, Z. pumila and Z. pygmaea had the common chromosome number of 2n= 16 and the common karyotype which consisted of 12 median-, 2 submedianand 2 subterminal-centromeric chromosomes. The 4 species showed commonly the CMA-positive band in the centromeric region of 2 median-, 2 submedian-and 2 subterminal-centromeric chromosomes. In contrast, Z. furfuracea, Z. loddigesii, Z. skinneri and Z. vazquezii had commonly the chromosome number of 2n=18 and 10 median-and 2 submedian-centromeric chromosomes in karyotype but exhibited 6 different chromosomes from each other. Zamia furfuracea and Z. loddigesii displayed the CMA-positive band in the centromeric region of 8 median-and 6 acro-centromeric chromosomes. Zamia skinneri performed the CMA-positive band in the centromeric region of 4 acro-and 2 terminal-centromeric chromosomes, while Z. vazquezii performed the CMA-positive band in the centromeric region of 4 median-and 6 terminal-centromeric chromosomes. Zamia muricata had the chromosome number of 2n=23 differed from that of the previous count, the karyotype which consisted of 7 median-and 16 acro-centromeric chromosomes and the CMA-positive band in the centromeric region of 4 median-and 16 acro-centromeric chromosomes. Then, the 9 species of Zamia studied exhibited unclear DAPI-positive bands near the centromeric region of most of their chromosomes. By comparison, the closely related Ceratozamia mexicana had the chromosome number of 2n=16 and the CMA-positive band at the terminal region of 6 chromosomes.
In order to investigate the difference of changeability in chromosome number and structure between two pairs of homologous chromosomes in Haplopappus gracilis callus, karyotype analyses of a number of metaphase chromosome spreads were carried out. More than 90% of cells examined showed chromosome number, 2n=4 as same as normal controls, however the cells with the same karyotype as normal controls decreased to 52.8%, in total. Change rate of centromeric position increased as culture period became long from early to late. Centromeric transposition rate became high in the callus of low growth rate. Change rate of centromeric position of the 2nd chromosomes which have satellites was about 2.5 to 3 times higher than that of the 1st chromosomes in all the concentrations and periods. The 2nd chromosomes of normal controls are subterminal chromosome type, but the majority of changed 2nd chromosome in callus cells was submedian chromosome type. This may probably due to breakage of the long arm of the 2nd chromosome and suggests the existence of breakpoint (s) in the long arm of the 2nd chromosome.
Three callus lines from 3 Allium fistulosum L. cultivars (Kaori, Fresh, Wede) and their regenerated plantlets were examined to elucidate the relationship between chromosomal aberration and morphogenetic capacity. In these callus lines, 9 karyotypes that were altered numerically and/or structurally were found in addition to the normal diploid karyotype (type S) identical to that of the mother plant. Structurally changed karyotypes occurred as a result of deletions and/or translocations. Of these, the occurrence of dicentric chromosomes arising through deletions and translocations between 2 al chromosomes was high. In regenerated plantlets from the callus lines, 3 structurally and/or numerically altered karyotypes were found in addition to the type S karyotype. Plantlets regenerated from callus cells were induced via shoot formation and subsequent root formation.