This is the first heteromorphic nucleolar organizer regions (NORs) and chromosome analysis of Rolland's demoiselle (Chrysiptera rollandi). Kidney cell samples were taken from five male and five female fish. Mitotic chromosome preparations were prepared directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of C. rollandi was 2n=46, and the fundamental number (NF) was 50 in both males and females. The types of chromosomes were 2 large submetacentric, 2 large telocentric, 2 medium acrocentric, 32 medium telocentric, and 8 small telocentric chromosomes. In addition, the short arm of acrocentric chromosome pair 2a and the long arm of telocentric chromosome pair 6a (non-homologous chromosome) showed clearly observable NORs heteromorphic (2a6a) in both sexes and chromosome size was not related to sex. The karyotype formula for C. rollandi was: 2n (diploid) 46=L2sm+L2t+M2a+M32t+S8t
Here we report natural autotetraploid and chromosomal characteristics in the subfamily Botiinae from Northeast Thailand. Kidney cell samples were taken from tiger botia (Syncrossus helodes), red-finned loach (Yasuhikotakai modesta), silver botia (Y. lecontei) and skunk botia (Y. morleti). The mitotic chromosome preparation was prepared directly from kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the tetraploid chromosome numbers of S. helodes, Y. modesta, Y. lecontei and Y. morleti were 4n (natural autotetraploid)=100 for all species, and the fundamental numbers (NF) were 122 for all species. The presences of metacentric, submetacentric, and telocentric chromosomes were 12-10-78 for all species. No cytologically distinguishable sex chromosome was observed. The nucleolar organizer regions (NORs) were observed at the region adjacent to the short arms of a pair of submetacentric chromosome for all species. These results show the evolutionary relationship between species of loach fish from Thailand. The karyotype formula was deduced as: S. helodes (4n=100): L8m+L4sm+M4m+M4sm+M26t+S2sm+S52t Y. modesta (4n=100): L10m+L8sm+L22t+M2m+M2sm+M50t+S6t Y. lecontei (4n=100): L10m+L8sm+L22t+M2m+M2sm+M50t+S6t Y. morleti(4n=100): L12m+L10sm+L66t+M12t
Chromosomal characteristics of nucleolar organizer regions/NORs and karyological analysis of the Tokay gecko (Gekko gecko) from Khon Kaen Province, northeast Thailand was studied. Gecko chromosome preparations were conducted by squash technique from bone marrow and testis. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa's solution. The results showed that the number of diploid chromosomes is 2n=38, while the fundamental number (NF) is 50 in both males and females. The types of chromosomes were 2 large metacentric, 4 large submetacentric, 4 large telocentric, 6 medium telocentric, 4 small metacentric, 2 small acrocentric, and 16 small telocentric chromosomes. NORs are located at the secondary constriction to the telomere on long arm of the largest telocentric chromosome pair 4. There are no sex differences in karyotypes between males and females. We found that during metaphase I the homologous chromosomes showed synapsis, which can be defined as 19 ring bivalents and 19 haploid chromosomes (n=19) at metaphase II as a diploid species. The karyotype formula is as follows: 2n (38)=L2m+L4sm+L4t+M6t+S4m+S2a+S16t
Among the most important environmental stresses, drought is the most significant stress affecting crop production. Effects of drought stress on the morphological parameters of plants are well studied and understood, but studies on the effect of drought stress on the chromosomal biology of plants are scarce. Therefore, the present study was conducted to study the effect of drought stress on the chromosomal biology of the drought-resistant green manure crop Sesbania cannabina. The present experimentation was conducted at the Department of Botany, University of Allahabad. Dry and healthy seeds of Sesbania cannabina variety ND-1 were soaked in distilled water and used for sowing in experimental pots to raise the population. After 15 days, seedlings were exposed to drought stress for different time durations (viz., 10, 15 and 20 days). On the onset of budding, young floral buds were fixed in carnoy's fixative and were used for cytological studies. Cytological studies clearly showed the chromotoxic behaviour of drought stress.
Indiscriminate disposal of electronic wastes (e-wastes) in Nigeria is on the increase. The release of hazardous substances from these wastes may have harmful consequences on the environment and public health. This study was designed to investigate the potential in vivo genetic and reproductive toxicity of e-waste contaminated underground (well) waters obtained from Alaba International and Computer Village electronic markets in Lagos, Nigeria, using the murine micronucleus (MN), sperm morphology and sperm count assays. The animals were exposed orally via free drinking of the water for one to five weeks. MN analysis showed a concentration-dependent induction of micronucleated polychromatic erythrocytes across the treatment groups. Assessment of sperm shape showed a significant increase in sperm abnormalities with significant decrease in mean sperm count in treated groups. The presence of Pb, Cu, Cr, and Cd in the tested samples is believed to contribute significantly to these observations. The results are indications that e-waste contaminated well water is capable of inducing somatic and germ mutation in living cells, and should be of public health concern in countries with risk of e-waste exposure.
F1 hybrid plants are raised following crossing between cultivar I (male parent; tall, branched, light yellow flower, oblong conical fruit, round seeds) and cultivar II (female parent; dwarf, unbranched, yellow flower, ovoid spindle capsular fruit, reniform seeds) of Abelmoschus moschatus (L.) Medik (Family: Malvaceae; common name—musk mallow; yielding ambrette oil of commerce). Reciprocal crossings yield only small-sized fruits with dusty and abortive seeds. The F1 hybrid plants resemble the female parent for qualitative traits except the calyx color, while the quantitative traits mostly are either lower or intermediate to the parent. The hybrid shows 42.86% normal pairing of chromosomes (2n=72; 36 II formation) at metaphase I, which is rather less than either of the parents (82.86% and 86.11%). However, pollen fertility and viability (lugol's iodine and aniline blue) are comparable in the plant types. Molecular analyses following the use of RAPD (random amplification of polymorphic DNA) markers reveal distinctiveness between parents as well as authenticate trueness of the raised hybrid line. Based on different genetic efficiency parameters, the RAPD markers, namely, OPA 01, OPA 02, OPA 10, OPB 02, OPB 04, OPB 05, OPB 08, OPC 03 and OPC 10 are found to be efficient and effective and may be utilized for molecular screening of A. moschatus germplasms including hybrid(s).
Solanum lycopersicum Mill. is a model plant for biological approaches and includes accessions with great agronomic relevance, such as the ‘Santa Cruz Kada Gigante'. For development of new S. lycopersicum accessions, in vitro tissue culture has proved relevant, contributing to the establishment of germplasm banks and breeding programs. In spite of the vast amount of tissue culture research already carried out in S. lycopersicum, in vitro polyploidization is still emerging. Thus, this study aimed to induce polyploid plantlets from ‘Santa Cruz Kada Gigante' from shoot tip explants. This accession presented 2n=2x=24 chromosomes and 2C=2.00 picograms of nuclear DNA. Hence, no preexisting variation was identified, and ‘Santa Cruz Kada Gigante' was considered appropriate for in vitro polyploidization. This procedure provided tetraploid (4x) and mixoploid (2x/4x and 2x/4x/8x) plantlets, which were identified by flow cytometry (FCM) and multiplied in vitro. Based on these results, the tissue culture procedure provided polyploid ‘Santa Cruz Kada Gigante' plantlets, which represent a new source of variability for breeding programs of S. lycopersicum.
The genus Amorphophallus Blume ex Decne. is represented by 18 species and seven varieties in India out of which 11 species and three varieties are endemic to the country. The present paper provides a comparative account of morphology and karyology of recently described three varieties, viz. Amorphophallus commutatus var. anmodensis Sivad. & Jaleel, A. commutatus var. anshiensis Punekar et al. and A. commutatus var. wayanadensis Sivad. & Jaleel. The somatic chromosome number 2n = 26 is reported for all the three taxa.
The mulberry is an economically important crop, cultivated for its foliage to rear the silkworm Bombyx mori L. Its chromosome number varies from 2n = 28 to 2n = 308 with ploidy level from x to 22x. In the present investigation, three triploid mulberry varieties, namely, S41, S1635 and BC2–59, have been analyzed for detailed meiotic studies. Based on the chromosome configuration and other meiotic behaviour, x = 14 has been considered as the basic number of the genus. Meiosis was highly irregular. Various anomalies, such as the occurrence of two nucleolus, association of single trivalent with nucleolus, unequal separation and precocious movement of chromosomes, laggards, and occurrence of multivalents, have been observed. The low pollen fertility and seed set may be due to genic or physiological causes.
In this study, we confirmed the chromosome forms for M. montis-koyae (2n=18) and M. urticifolia (2n=18 and 2n=27). The chromosome count of 2n=27 is a new count for this species. These two counts reveal the basic chromosome number of x=9, which then becomes 2n=18. Thus, 2n=18 M. urticifolia is a diploid plant, and 2n=27 M. urticifolia is a triploid plant. The somatic chromosome complement was formulated as 2n=18=7m+9sm+2st. As such, the second longest chromosome pair is heteromorphic with long arms of different lengths. Notably, meiotic chromosomes at metaphase I showed nine bivalent chromosomes with terminal associations. In addition, pollen fertilities showed a range of 65.4–97.0%, while the karyotype was formulated as 2n=27=13m+14sm. Meiotic chromosomes at diakinesis and metaphase I had univalent, bivalent and trivalent chromosomes, and pollen fertilities showed a range of 2.3–29.0%. Thus, the triploid species is a segmental allotriploid plant. Both polyploid forms of M. urticifolia occurred widely in Japan.
Cytogenetic and reproductive assays were carried out on a population of annatto (Bixa orellana) of Southeastern Brazil. The reproductive data indicate that B. orellana is self-compatible but preferentially alogamous and entomophylous. No apomictic fruits were obtained from emasculated flowers. Fruits formed exclusively by self-pollination were smaller and had fewer seeds than those obtained by open pollination, highlighting the importance of pollination for annatto seed production. The meiotic process was analyzed and some abnormalities observed resulted in only some sterile pollen (1.9%) with no significant reduction of fertility. The cytogenetic studies showed the haploid chromosome number n=7 and the diploid number 2n=14, with a remarkable bimodal karyotype. FISH with 45S rDNA and 5S rDNA probes showed that these loci do not occur in synteny. Both probes hybridized in the proximal regions of the short arm of pair 1 (45S) and pairs 4 and 6 (5S). One pair of 5S rDNA sites presented larger signals in FISH than the other pair. These karyological features suggest that fusion of chromosomes and amplification of DNA segments played an important role in karyotype evolution of B. orellana.
During the present course, population-based meiotic studies were carried out on five species of genus Anemone from selected localities of Himachal Pradesh in the Western Himalayas (India). Varied intraspecific morphotype and B-chromosome were reported in A. obtusiloba. Impaired male meiosis was noted in all populations of A. obtusiloba, A. polyanthes, A. rivularis, A. tetrasepala, and A. vitifolia. These anomalous species were marked with meiotic abnormalities in the form of cytomixis, chromosomal stickiness, unoriented bivalents, formation of laggards and bridges resulting in abnormal microsporogenesis, and production of heterogeneous-sized fertile pollen grains along with reduced pollen fertility.
Taraxacum officinale (common dandelion; Asteraceae) was first noted as an introduced plant in Japan in 1904 (Makino 1904). Currently, this species grows in plains and mountainous habitats throughout Japan, from Hokkaido to Ryukyu. The present study collected 3,941 individuals from 108 sites (on average, 36.5 plants per population) throughout the Japanese archipelago, and examined their somatic chromosome counts. We found that Japanese T. officinale is a polyploid complex (x=8) composed of triploid (3x) (2n=24) and tetraploid (4x) (2n=32) individuals. We also found that 3x T. officinale is distributed throughout Japan, from Hokkaido to Okinawa, whereas 4x tetraploid T. officinale is limited to Honshu, Shikoku and Kyushu. Karyotypes were examined for 37 individuals that were used in the plants examined for their chromosome numbers (Table 2). This yielded a total of eight forms of 3x T. officinale and four forms of 4x T. officinale. Previously, 2n=24+2B chromosomes and 2n=26 chromosomes have been reported for Japanese T. officinale. However, these were considered miscounts due to erroneous recognition of satellite bodies as two B chromosomes or two chromosomes of the two large satellites in some races of 3x T. officinale with large satellites. Taraxacum officinale has hundreds of apomictic microspecies worldwide. Our study reveals that some races in both 3x and 4x T. officinale can be differentiated according to their karyotypes.
Four specimens of the genus Allium, viz. A. tuberosum, A. cepa (Local), A. cepa (Indian large bulb) and A. cepa (Indian small bulb), were cytogenetically studied. In addition, DNA fingerprinting by using RAPD was also carried out to make a phylogenetic dendrogram. Allium tuberosum was found to possess 2n=32 chromosomes. On the other hand, 2n=16 chromosomes were observed in the other three specimens. The four specimens showed distinct centromeric formulae, which were 16m+12sm+4ac in Allium tuberosum, 10m+4sm+2ac in A. cepa (Local), 8m+8sm in A. cepa (Indian large bulb) and 9m+7sm in A. cepa (Indian small bulb). This result indicated that Allium tuberosum and A. cepa (Local) possessed more heterogeneous karyotypes. Satellites were found in Allium tuberosum, A. cepa (Indian large bulb) and A. cepa (Local) in different stains. In A. cepa (Indian small bulb), heteromorphicity in respect of centromeric position indicated the occurrence of a deletion at the short arm of the respective chromosome. The four specimens of Allium have distinct CMA- and DAPI-banding patterns. The number, location, intensity and percentage of GC- and AT-rich repeats were different in these specimens. With the help of CMA- and DAPI-banding it was possible to mark certain chromosomes specific for each specimen. Each specimen showed characteristic RAPD fingerprinting. The unique RAPD fragments could be used as markers for the respective specimens. The karyotype and RAPD data did not support the large bulb specimen as an autopolyploid of the small bulb specimen, but rather found maximum similarity between the two specimens. Moreover, the karyotype data of A. tuberosum obtained in this study was different from earlier reports, and thus needs a peer revision of its taxonomic status.
Four specimens of Garlic (Allium sativum L.), viz., Local monocloved, Local multicloved, Indian multicloved and a wild specimen (a tribal specimen locally called Joldong), were compared karyotypically by differential staining with orcein, CMA and DAPI. In addition, DNA fingerprinting was carried out by using RAPD. The wild specimen was found to possess 2n=32 chromosomes while the other three specimens had 2n=16 chromosomes with more or less similar total length of 2n chromosome complement. The four specimens showed distinct centromeric formulae, i.e. 12m+4sm in Local monocloved, 8m+8sm in Local multicloved, 10m+6sm in Indian multicloved and 26m+6sm in the wild specimen. In Local monocloved, a unique structure in a pair of sub-metacentric chromosomes revealed the occurrence of homozygous paracentric inversion. The four specimens of Allium sativum L. have distinct CMA- and DAPI-banding patterns. Asymmetric banding patterns in homologue members indicated minute chromosomal alterations. The two entirely DAPI fluoresced chromosomes were found in only the Local monocloved specimen. These chromosomes were unique and thus could be used as marker chromosomes for this specimen. Each specimen showed characteristic RAPD fingerprinting. The unique RAPD fragments could be used as markers for the respective specimens. Differential karyotype analysis did not support to consider the multicloved specimens as autotetraploid of the monocloved, inspite of having gigas features. The wild specimen showed a completely different karyotype than the other three specimens. It was placed alone in a separate cluster on the basis of RAPD analysis with highest genetic distance. Therefore, a thorough investigation is necessary to elucidate the taxonomic status of this wild specimen.