Seeds of 2 cultivars viz., CSG-89.62 and KPG-59 of Cicer arietinum L. were subjected to four different concentrations i.e., 0.1%, 0.2%, 0.3% and 0.4% of ethylmethane sulphonate. Meiotic studies were carried out in the control as well as in the treated material. Different types of meiotic abnormalities such as stickiness, univalents, multivalents, unorientation of chromosomes, precocious separation of chromosomes at metaphase and bridges, laggards and unequal separation of chromosomes at anaphase were recorded. In general, the meiotic abnormalities increased along with the increase in concentration in both the cultivars. However, cultivar KPG-59 showed more chromosomal abnormalities as compared to cultivar CSG-89.62 at the same treatment.
In the present study, molecular genetic fingerprints for 7 Raphanus L. samples belonging to 2 species (Raphanus raphanistrum L. and Raphanus sativus L.) were carried out to elucidate relationships among these samples. Extracted DNA from fresh leaf samples was used to identify the molecular fingerprints. Fifteen 10-mer arbitrary oligonucleotide primers were initially used to establish their randomly amplified polymorphic DNA based on polymerase chain reaction (RAPD-PCR) fingerprints and to discriminate among them. Only 6 primers successfully generated reproducible polymorphic products. These primers are; UBC 43, 51, 66, 71, 77 and 91. The fingerprints generated by these primers revealed characteristic profiles for each Raphanus L. genotypes, in terms of number and position of RAPD bands. The results revealed that both the number and size of the amplified products varied considerably with the different primers. A sum of 66 polymorphic bands was generated by these primers in the Raphanus L. genotypes under study. A total of 20 unique bands were identified out of the polymorphic ones. These unique bands were used to discriminate among the studied Raphanus L. samples. Most samples of the studied Raphanus L. samples were discriminated by one or more unique bands.
Chromosomes of 6 bivalve species were studied from mitotic metaphases using cell suspension techniques. Among Family Mytilidae, Modiolus barbatus (Linnaeus 1758) has a diploid chromosome number of 2n=32 with 5 metacentric, 2 submetacentric, 5 subtelocentric and 4 telocentric chromosome pairs, Septifer excisus (Wiegmann 1837) has 2n=26 with 9 metacentric, 2 submetacentric, and 2 telocentric chromosome pairs and Septifer bilocularis (Linnaeus 1758) also has 2n=26 with 8 metacentric, 2 submetacentric and 3 subtelocentric chromosome pairs. Among Family Veneridae, Ruditapes decussatus (Linnaeus 1758) has 2n=38 with 6 metacentric, 5 submetacentric, 3 subtelocentric and 5 telocentric chromosome pairs, Circe scripta (Linnaeus 1758) has 2n=38 with 6 metacentric, 6 submetacentric, 4 subtelocentric and 3 telocentric chromosome pairs and Venus verrucosa (Linnaeus 1758) has also 2n=38 with 7 metacentric, 4 submetacentric, 4 subtelocentric and 4 telocentric chromosome pairs. These results are reported for the first time in Egypt.
Pepon and prostoplex, new drugs containing natural substances, are used in the treatment of prostatic disorders. The cytogenetic effects of these drugs were tested in mice's bone marrow and spermatocytes cells at two doses comparable to propose human therapeutic and double therapeutic doses. The results revealed that the total numbers of structural chromosomal aberrations in mice's bone marrow, with or without gap, were significantly increased at p<0.01 for pepon and at p<0.05 for prostoplex at therapeutic doses. Whereas at double therapeutic doses, the two drugs showed highly significant increases in the total numbers of structural chromosomal aberrations compared with controls. The frequency of total chromosomal aberrations in mice's spermatocytes was increased at significant level p<0.01 for both drugs at therapeutic doses. At double therapeutic doses, pepon and postoplex increased the total chromosomal aberrations in spermatocyte cells at highly significant level p<0.001. In conclusion, the cytogenetic analysis of pepon and prostoplex revealed that the two drugs have adverse effect on somatic and germinal materials at therapeutic dose. Also, our results are considered as a caution for the treatment with these two drugs at double therapeutic doses, which have mutagenic effect on somatic and germinal materials.
Male and female meiosis has been studied together for the first time in Nicotiana tabacum (2n=48) collected from 2 populations. Meiotic studies revealed differences in the behavior of chromosomes in the 2 sex cells i.e. pollen mother cells (PMCs) and embryo sac mother cells (EMCs) particularly with respect to frequency of chiasmata. Male sex cells (PMCs) showed a higher chiasmata frequency than female sex cells (EMCs) which show 14.33 and 11.48% reduction in chiasmata frequency in the 2 populations. The practical importance of female meiotic studies is discussed.
Eleven desirable macromutants namely, viridis (seedling colour as marker, increased seed protein content), broad leaf (high capsule number/plant), thick leaf and diffused branching (enhanced number of capsules with high amount of seed protein and fatty oil contents), early flowering (synchronous maturity, enhanced fatty oil content), white flower (marker trait), globular fruit (enhanced seeds/capsule with high oil content in seed), non-shattering capsule (intensed pigmentation on flowers as marker trait apart from the unique trait it possessed for breeders and farmers), dark reddish brown seed-coat I and II (high oil content) and bold seeded (high protein content) have been reported in sesame (Sesamum indicum L. var B-67) which were the outcome of induced chemical mutagenesis. Meiosis in control and mutants was nearly normal (13 bivalents at MI and 13/13 separation of chromosomes at AI mostly) with high pollen fertility (75.15 to 100.0%). All mutant traits were recessive to normal and excepting viridis (digenic) showed monogenic inheritance pattern.
In spite of a few tools, cytogenetical analyses have made important contributions to the understanding of natural populations' biodiversity. The fluency of some subjects can be limiting specially for early investigators of this area. Aiming to contribute to the understanding of karyotypic dynamics of species, and to elucidate its cytogenetics relationships as well, a dichotomyc key for the identification of sex chromosomes and chromosomal polymorphisms was developed. Profound analyses of karyotypic macrostructure can be done with this tool. However, relatively simple and routine data on the genome organization are needed.
Karyotypes of six species of Sorghum were analysed in detail. The karyomorphological features of S. intrans, S. propinquum, S. bicolor, S. purpureo-sericeum, S. halepense and S. sudanense showed close similarities at interspecific levels among species with 2n=20 and between species with 2n=40 chromosomes. The extent of chromosome morphology was critically evaluated on the basis of combination of karyotypic parameters like relative length, arm ratio, chromosome index and nucleolar organizers. The results brought out the existence of close similarities among the species notwithstanding the minor structural differences that existed within the species but within limits. The present study confirmed the validity and importance of karyotype analysis with different parameters in distinguishing even the lowest hierarchial level in the genus Sorghum.
The Rubia cordifolia extract showed a mitodepressive effect on the rate of cell division in bone marrow cells of Swiss male mice at all times of exposure and in almost all the concentrations studied compared with corresponding controls. This effect increased as the time of exposure increased. This reduction is attributed to the extract effect of inhibiting protein synthesis, suggesting probable effect of Rubia extract on the biosynthesis of certain amino acids as well as RNA synthesis. Following application of the lowest dose (25%), 24 h exposure was regarded the higher limit of time exposure in the experiments. After 24 h exposure and at the lowest dose 250 mg/ml (25%) the effect of Rubia extract started to decrease.
The effects of hydroxyurea (HU) and aphidicolin (APD) on cell cycle synchronization in cucumber root meristems were studied. A 10 times lower HU concentration was effective for cucumber synchronization compared to that used as a typical treatment in Vicia faba or Triticum aestivum, and the peak mitotic index (MI) was 5 h after inhibitor removal. Higher APD concentrations (15 μM and above) caused the accumulation of M phase cells, and the peak MI was 4 h after its removal. After release from the HU block, the use of Hoagland's nutrient solution on cell cycle synchronization resulted in a considerable increase in MI. The efficiency of colchicine was also very high, and cells at anaphase or telophase were observed at very low frequencies. The highest MI (39%) was obtained 4 h after an 18 h APD block at 15 μM followed by 0.05% colchicine treatment for 2 h. Our synchronizing procedure in C. sativus would be very helpful for flow-sorting of mitotic chromosomes, karyomorphological analysis, and genetic analysis.
Cytogenetic studies of 20 specimens of Apareiodon affinis (Pisces, Parodontidae) from Sapucai river, Minas Gerais State, Brazil, revealed distinct diploid numbers among sexes, the females showing 2n=55 and the males 2n=54 chromosomes, characterizing a multiple sex chromosome system of the ZZ/ZW1W2 type. The nucleolar organizing regions were located in a terminal position on the long arm of a subtelocentric pair 26, which was coincident with GC-rich heterochromatin after CMA3 staining. Constitutive heterochromatin was observed in the pericentromeric position of all chromosomes and in the terminal position of about 7 chromosome pairs. A comparison with the available data is presented.
The mitochondrion-dividing ring (MD ring) is an electron-dense annular structure at the isthmus of constricting mitochondria, which was first found in a primitive red alga Cyanidioschyzon merolae (Kuroiwa et al. 1993, 1995). However, there has been no evidence for its existence in other organisms. In the present study, mitochondrial division of a unicellular eustigmatophyte alga Nannochloropsis oculata was examined by transmission electron microscopy. Three-dimensional reconstruction of serial thin sections revealed the MD ring girdling the isthmus of the constricting mitochondria. This suggests that the MD ring is conserved in eustigmatophytes distant from rhodophytes in phylogeny.
In protoplast culture of the Louisiana iris species, Iris fulva (2n=42), N6 medium supplemented with 1 mg/l 2,4-D, 1 mg/l kinetin, 200 mg/l casein hydrolysate, 250 mg/l proline, 0.3 M glucose and 2.5 g/l gellan gum was suitable for cell division and colony formation. When colonies formed were transferred to plant growth regulator free MS medium, 61 plant lines were regenerated via somatic embryogenesis. Flow cytometric analysis revealed that leaf tissue of I. fulva consisted of 2C, 4C and 6C cells. Consequently, we identified this species as polysomatic in the genus Iris. Such polysomaty was also recognized in the suspension calli. Sixty one plant lines obtained by protoplast culture consisted of 25 diploid (41.0%), 1 triploid (1.6%), 29 tetraploid (47.5%) and 6 hexaploid lines (9.9%). In addition, chromosome analysis showed that somatic chromosome numbers of the diploid, hypertriploid and tetraploid lines were 2n=42, 67 and 84, respectively. On the other hand, all lines regenerated from suspension culture of I. fulva were diploid lines in contrast to the results from protoplast culture. Thus, it can be concluded that protoplast culture of this species is an efficient technique for production of polyploid plants.
Microsporogenesis and male gametophyte development of a Cucumis allotriploid from meiosis of PMCs to mature pollen grains were studied using light microscopy. Variable chromosome configurations, e.g. univalents, bivalents, trivalents, quadrivalents, etc. were observed in most PMCs of the allotriploid at MI. Chromosome lagging and bridges at anaphase resulted from irregular chromosome separation and asynchronization between C and H genomes were frequently observed as well, which led to formation of polyads and inviable gametes. However, there were still some PMCs in which the normal meiotic process could be accomplished to form the microspore tetrads via simultaneous cytokinesis. The arrangement of microspores in the tetrads was tetrahedral. Among those microspores, part of them (10%) could develop into fertile gametophytes with 2 cells and 3 germ pores through the following stages: single-nucleus early stage, single-nucleus late stage, 2-celled stage after pollen mitosis. A few 3-celled pollens were also observed. But most other microspores (90%) were sterile stopped at single-nucleus stage. The low fertility of male gametophytes was confirmed by the weak stainability and low germination rate.
To examine ploidy change in hyperploid cells after treatments of staurosporine (SS), an inhibitor of protein kinases, octaploid Meth-A cells were exposed to SS, and then the drug concentration was gradually reduced. Seventy cell clones were obtained from the cell population, and they were classified into 4 groups based on their DNA content corresponding to hexa-, octa-, dodeca- and hexadecaploid cells. Durations of G1, S and G2/M phases of the cells were almost the same as that of parent octaploid cells. The cell volumes of 6- and 12-ploid cells were not proportional to DNA content. It was concluded that polyploid Meth-A cells whose ploidy is not a power of 2 were produced from octaploid cells by SS treatments.
SDS-PAGE of seed protein bands profile was recorded in 22 individuals of 6 species of Onobrychis from 6 populations, including the Egyptian species and most representatives of Sect. Lophobrychis. The produced data, in addition to the available morphological, cytological and the geographical characters in the literature were analyzed by the NTSYS program package using the UPGMA clustering method. The interspecific variability within the species studied of the section Lophobrychis was discussed; the genetic and morphological differences between the Egyptian species were assessed.