Cowpea, Vigna unguiculata (L.) Walp., is an important crop for many developing countries. Its potential cannot be fully achieved due to scarse resistance to pathogens. Source of resistance are present in wild gene pool, therefore, the introduction of genes for valuable traits from wild species to Vigna unguiculata faced an obstacle due to crossability barriers between species. The study of the chromosomal morphology could be useful in a modern plant breeding approach of cowpea. Recently the use of image analysis system to the karyotyping of plant species with few chromosomes has allowed the production of detailed karyotypes employed for interspecific comparisons. Twelve species belonging to four different subgenera and to six sections according to Marechal et al. (1978) were analysed by image analysis system. The karyomorphological parameters were utilised for computing karyosimmetry according to Stebbins (1971).
Weeping lovegrass, Eragrostis curvula (Schrad.) Nees, is an important apomictic forage grass for semiarid regions. The aim of this work was to study the effect of in vitro culture in the mitotic and meiotic behaviour of regenerated weeping lovegrass plants. Thirty two plants were obtained from in vitro culture of inflorescences segments in MS medium with different concentrations of BAP (0.01, 0.1, 1, 2, 5 mg-1) and 2, 4-D (1, 2, 4, 6, 8 mg-1). Ten of these plants were taken at random in order to determine the chromosome number and analyze the meiotic behaviour. In the regenerated plants it was possible to observe mixoploidy and meiotic disturbances like alterations in chromatin condensation, meiocytes degeneration, diminution in pollen mother cells and pollen grains quantity, abnormal pairing, bridges and fragments and no pollen formation. Because the apomictic nature of this grass and the uniformity of this cultivar, stable genetic variability that involve phenotypical and biochemical traits due to karyological variation could be potentially used for crop improvement.
The spontaneous occurrence of a triploid is reported in Manihot esculenta Crantz collected in Sapé-PB, Brazil. Mitotic analysis showed a stable chromosome number of 2n=54, with chromosome size and morphology very similar to the diploid species. The chromosome behavior in meiosis was irregular in the metaphase-anaphase I, with occurrence of uni, bi and trivalents. The average number of univalents per cell was 7.2. In the tetrad stage, a higher number of micronuclei were found, resulting in almost 100% of abnormal tetrads and pollen sterility. Triploid was also characterized by having larger and fewer stomata than diploid species.
Anopheles splendidus Koidzumi is an important species due to its highly variable prevalence. The cytogenetic investigations were carried out on a mountain population of this species collected from Solan (H.P.) located at an altitude of 1200 m. The standard polytene chromosome map was produced and compared with the map produced for its population prevalent in the plains near Chandigarh. The standard banding pattern of X-chromosome and the autosomal arms 2R, 2L, 3R and 3L presented homologies to a considerable extent, as nearly 80% of the DNA rich bands were comparable in the two populations. However, both differ with respect to the incidence of paracentric heterozygous inversions in the autosomes, while the X-chromosome was free from any such structural alterations. The adaptive significance of the genomic changes has been discussed in the light ofecological differences in their habitats.
The cytotaxonomical characteristics of the four species Pinctada margaritifera (Linne 1758), P radiata (Leach 1814), Barbatia fusca (Bruguiere 1789), B. tenella (Reeve 1844) were studied using karyotype analysis. The diploid chromosome numbers of these four species are 28 (FN=48), 26 (FN=44), 38 (FN=42) and 36 (FN=44) respectively. The karyotype of Pinctada margaritifera is consisting of five pairs metacentric, two pairs submetacentric, three pairs subtelocentric and four pairs acrocentric chromosomes; while the karyotype of Pinctada radiata composed of five pairs metacentric, two pairs submetacentric, two pairs subtelocentric and four pairs acrocentric chromosomes; Barbatia fusca have karyotype containing of two pairs metacentric and seventeen pairs acrocentric chromosomes and; the karyotype of Barbatia tenella contains of four pairs metacentric and fourteen pairs acrocentric chromosomes. To the best of author knowledge, these results are reported for the first time in Egypt.
The maned wolf, Chrysocyon brachyurus, is a vulnerable species of the Canidae family inhabiting tall grass savannas and grasslands of central South America. Few ecological and genetical studies have been conducted on this canid. From a cytogenetic viewpoint, the karyotype of C. brachyurus is closely similar to that of the domestic dog (Canis familiaris) although both species differ each other in the diploid number and fundamental number (2n=76 and FN=78; 2n=78 and FN=80, respectively). In the present study, different chromosome banding methods (G, C, Ag-NOR and base-specific fluorochrome staining) were used for a better chromosome characterization of C. brachyurus. Additionally, some aspects of the chromosome evolution of Canidae were also discussed.
The karyotypes of C. incana, C. holosericea (section Chrysocalycinae), C. brevidens, C. lanceolata, C. pallida (section Hedriocarpae), C. juncea, C. paulina, C. stipularia (section Calycinae), C. retusa, C. spectabilis and C. virgulata subsp. grantiana (section Crotalaria) were analyzed. All the species are 2n=16, except for C. incana, which is 2n=14, C. paulina and C. stipularia, which are 2n=32. The chromosome similarity of some species correlates with morphologic characteristics within the sections. The data suggests a decrease in chromosome size and a lower karyotype symmetry index in the species which have more advanced characteristics in the genus.
18S ribosomal RNA gene (rDNA) loci were mapped on chromosomes of Paris tetraphylla A. Gray, P. verticillata M. v Bieberstein and P. polyphylla Smith, Liliaceae by using fluorescence in situ hybridization (FISH). The 18S rDNA probes were prepared from the interphase nuclei by the method during the polymerase chain reaction (PCR). Chromosome numbers of all the examined plants were 2n=10. Haploid genomes of P. tetraphylla and P. verticillata were consisted of three metacentric chromosomes, a submetacentric chromosomes and an acrocentric satellite chromosome. One 18S rDNA locus was detected at the second constriction of the acrocentric chromosome. On the other hand, a haploid genome of P. polyphylla was consisted of three metacentric chromosomes and two acrocentric chromosomes. Two 18S rDNA loci were detected at the second constriction of both acrocentric chromosomes.
This paper deals with the chromosome numbers (somatic or sporophytic and gametic) of some wild species of the Kuwaiti flora. All species were collected from the wild except Plantago lanceolata, which was cultivated. Some values are reported for the first time. The species and their respective chromosome numbers are as follows : Anthemis deserti 2n=18, Atractylis carduus 2n=20, Calendula arvensis 2n=36, 44, Koelpinia linearis 2n=54, 36, Launaea capitata 2n=18, L. mucronata 2n=16, Picris babylonica 2n=10, Reichardia tingitana 2n=16, Senecio glaucus 2n=20, Sonchus oleraceus 2n=32, Astragalus hauarensis 2n=48, A. schimperi 2n=16, Lotus halophilus 2n=14, 28, Medicago laciniata 2n=16, Plantago amplexicaulis 2n=10, P. boissieri 2n=10, P. ciliata2n = 10, P. coronopus 2n= 10, P. lanceolata 2n= 12, P. ovata 2n =8. Karyotype analysis of P. babylonica, R. tingitana, P. boissieri, and P. ciliata is shown.
The standard photographic maps of five blackfly species from northern Thailand : i.e., Simulium (Nevermannia) caudisclerum, S. (Simulium) fenestratum, S. (S.) nakhonense, S. (S.) rufibasis and S. (Montisimulium) sp. G were constructed from larval salivary gland polytene chromosomes and are described herein. All the five species have three pairs of chromosomes (2n=6) which are arranged from the longest to the shortest. Chromosome I of all species are metacentric while most of the chromosome II and III are submetacentric. The centromeric regions of all chromosomes of S. (S.) nakhonense and S. (S.) rufibasis were expanded whereas the heavy centromeric bands were presented in S. (N) caudisclerum, S. (S.) fenestratum and S. (M.) sp. G. The nucleolar organizer of S. (N.) caudisclerum, S. (S.) fenestratum, S. (S.) nakhonense and S. (M.) sp. G is situated near the centromeric band of chromosome I. On the other hand, S. (S.) rufibasis has the nucleolar organizer on chromosome II. The Balbiani ring and double bubble are located near the tip of short arm of chromosome III in all species except for S. (S.) fenestratum, in which they are detected on chromosome II. Moreover, two types of B chromosomes and pseudochromocenters were also found in some larvae of S. (S.) nakhonense. There are no inversion polymorphisms detected in wild populations of these species. The five Simulium species have specific and fixed standard banding sequences which are different among species, although some banding sequences in chromosome arm IIIS show homology.
Melatonin (MLT) and two structurally related compounds, 5-methoxytryptamine (5MT) and 5-methoxytryptophol (5ML), are formed in Saccharomyces cerevisiae in high concentrations. Depending on conditions, levels can attain several ng/mg protein, sometimes more than 10 (MLT, 5MT) or 20 (up to >100 : 5ML) ng/mg. Starvation in salt medium leads to a drop in all methoxyindoles below detection thresholds. After 4h in salt, reincubation in growth medium restores high levels. Addition of tryptophan, serotonin or N-acetylserotonin to starved cells also elevates MLT and 5MT. Exogenous MLT (50 or 100μM) causes 5MT to rise above 700ng/mg protein within 0.5h, whereas same concentrations of exogenous 5MT lead to >90->300ng MLT/mg. Therefore, MLT can be synthesized via the most common pathway from tryptophan to N-acetylserotonin as a direct precursor, and is deacetylated to 5MT; biosynthesis of MLT by N-acetylation of 5MT is a secondary pathway.
The behavior of the vegetative nucleus during pollen grain development and germination in Tropaeolum majus was examined using epifluorescence microscopy stained with 4', 6-di-amidino-2-phenylindole (DAPI). The vegetative nucleus exhibited gradual elongation and overall length association with the simultaneously elongated generative cell during pollen development. The elongated vegetative nucleus and generative cell in the mature pollen grains appeared in a paired structure that was stable against physically squashed pollen rupture. Electron microscopy showed that the ultrastructural relationship between the vegetative nucleus and the generative cell was discontinuous with rough endoplasmic reticulum (RER) often located in the interface and Golgi bodies appeared remarkably around the generative cell. However, the vegetative nucleus became spherical after pollen hydration and the association between the vegetative nucleus and the generative cell disintegrated markedly during pollen germination. These results suggest that the elongation of the vegetative nucleus and the physical association between the vegetative nucleus and the generative cell in the pollen grains of T majus may play an important role in pollen, especially the generative cell development.