Erythrodiplax is an American genus of dragonflies with a mainly neotropical distribution and with 19 species cited in Argentine. In this work 9 species have been chromosomically analyzed : E. atroterminata, E. connata fusca, E. corallina, E. lygaea, E. media, E. melanorubra, E. nigricans, E. ochraceae and E. umbrata. All of them, except E. media, have n=12+X in males, with a similar karyotype and meiotic behaviour. Bivalents decrease gradually in size, except for the small m bivalent, whose size varies among the species. The X chromosome in E. corallina, E. lygaea, E. nigricans and E. umbrata is twice as large as in the other 4 species. On the other hand, E. media has n=10+neo-XY, m chromosomes, and its karyotype characterizes by the presence of two large bivalents (being the largest the heteromorphic neo-XY). The genus Erythrodiplax presents a great karyotypic constancy, although polytypisms for the m chromosome size have been detected in E. atroterminata, E. connata fusca and E. umbrata, and for the sex chromosome determining system, in E. media. The chromosome rearrangements that probably originated these polytypisms, and their evolutionary importance are discussed.
Effectiveness on weed control and injury on sorghum plants were compared for herbicides atrazine and propazine which were applied at four different rates, 0.56, 1.1, 2.2 and 4.5kg/ha. It was found that both herbicides at rates above 2.2kg/ha reduced plant height but propazine caused less injury than atrazine. The majority of cytological aberrations observed during meiosis were multiple nucleoli detected in diplotene and early diakinesis cells and asynchronization of chromosome movement as noted in metaphase II and telophase II cells. Cells with lagging chromosomes and aneuploid cells were rare and should not hinder the used of these herbicides.
Forty-two G. herbaceum cultivars available in Iran National Gene Bank were analysed karyologically showing 2n=26 chromosome number. The cultivars varied with regard to number of SAT-chromosomes and chromosomes carrying secondary constrictions. Karyotypes were of symmetrical type having small chromosomes. Factorial analysis showed significant difference for both the cultivars as well as chromosomes. Cluster analysis using UPGMA, single linkage and complete linkage methods grouped the cultivars in six distinct clusters. Principal coordinate analysis supports the clustering results and principal component analysis showed that chromosomes 4 to 10 and long arms of the chromosomes 2, 8, 10 and 13 and short arms of the chromosomes 3, 7 and 8 are the most variable chromosomes/chromosome arms among the cultivars studied. Present work indicates genomic differences among diploid G. herbaceum cultivars of Iran which can be used in hybridization programs. Crossing of the cultivars placed in distant clusters are suggested.
The mieotic behavior of five populations of Centella asiatica from the southern region of Brazil was evaluated. A high incidence of irregularities occurred in all populations, especially irregular chromosome segregation, abnormal spindles, chromosome transfer among microsporocytes, and sticky chromosomes. These irregularities may be attributed in part to the large number of chromosomes detected in these populations (2n=54) suggesting hexaploidy, a phenomenon detected here for the first time in this species. The high pollen sterility and low seed production observed in these populations must be due to these irregularities.
Seven species of Australian Drosera were investigated for a comparative karyotype analysis with different banding schedules, namely Giemsa C-band fluorescent- (CMA- and DAPI-) bandings. Chromosome numbers of D. callistos (2n=28), D. scorpioides (2n=18), D. ericksonea (2n=28), D. pulchella (orange flower) (2n=15), D. scorpioides (2n=16) and D. spilos (2n=18) were reported here for the first time. All the taxa showed asymmetric karyotype in chromosome length. Bimodal karyotypes were observed in D. callistos, D. ericksonea, D. pulchella (pink flower) that perhaps resulted from interspecific hybridization. Sat-chromo-somes were found in D. callistos, D. petiolaris, D. pulchella (pink flower) and D. spilos. The appearance of satellites were strictly stain specific. Three chromosomes of D. pulchella (pink flower) and two chromosomes of D. scorpioides could be identified by their specific response to Giemsa stain. Fluorescent banding revealed that genomic DNA of D. callistos and D. scorpioides rich in AT base composition. A marked differences regarding chromosome numbers, orcein, C-banded and fluorescent banded karyotypes were observed between the two taxa of D. pulchella (pink flower and orange flower), thus needs apeer reinvestigation to elucidate their taxonomic position.
Mitotic chromosomes of seven South American species and two varieties of Lycium sect.Lycium were studied to clarify their taxonomic relationships and to assess the karyotype for possible insight into the evolution in the section. All species have 2n = 2x = 24. The chromosome numbers of L. infaustum and L. rachidocladum are reported for the first time and data on karyotype composition are mostly new. The generalized karyotype of the section shows it is highly symmetrical. The chromosomes are metacentric or submetacentric with the formula : 11 m + 1 sm. Microsatellites are present in chromosome pair #1 and are attached to the short arms. The section is karyotypically homogeneous. Cluster analysis using several cytological data and chromosomal identity index (CI) shows that most of the taxa are very close or even identical. There are no indications of major chromosomal rearrangements within the section. Karyotypic features obtained suggest that morphological differentiation in the group was not followed by chromosomal divergence.
Effect of hypoxia on the localization of intranucleolar DNA was examined in excised root tips of Vicia faba with immunoelectron microscopy using anti-DNA antibodies. In actively growing roots, the fibrillar centers (FCs) appeared as low electron-opaque patches. The immunoelectron microscopic study indicated that the FCs were heavily labeled and significantly strong label was also appreciated in the region around FCs. When excised root tips were subjected to a hypoxic condition which was attained by boiling distilled water for 10 min and sealed with “Parafilm” after cooling, area of the FCs relative to the whole area of nucleolus gradually increased with exposure time. At the 4th hr under hypoxia, chromatin-like compact fragments were sometimes seen in the developed FCs. These fragments were heavily labeled with anti-DNA antibodies as condensed chromatin. The label, on the other hand, extremely decreased in the region around FCs. Thus, evidence is presented suggesting that rDNA engaged in transcription deep in the DFC temporarily form condensed chromatin fragments in the FCs when the cells are exposed to hypoxia.
By means of selection, Trifolium incarnatum plants were produced showing down to x = 1.1 chloroplasts per guard cell of stomata. Only two apoplastidic cells were seen. It could be shown that for a regular allocation of chloroplasts to daughter cells and for preventing apoplastidic cells to occur in higher plants, no special apportioning mechanism is required, but a non-random, more even distribution of chloroplasts in the mother cells may be sufficient. Such a distribution exists in mature cells and probably in meristematic cells as well. Thus the minimal number necessary for continuity in higher plants would be two chloroplasts for one mother cell, at least in Trifolium. The coupling of chloroplast division with cell division as found in lower plants is no longer maintained.
A comparative study of the cold-sensitive H-segments and C-banded segments was made on chromosomes in three species of Japanese Trilliums. In T. kamtschaticum, C-band patterns of chromosomes differed from cold-treated ones in respect to the presence of centromeric and telomeric bands and thick intercalary bands on chromosomes C, D, and E. These were also confirmed in the C-band patterns of chromosomes after cold-treatment, except for chromosome E. Thus, it was elucidated that the chromosomes of this species have H-segments reactive to both cold treatment and C-banding staining and those reactive only to C-banding staining. Also, the location of intercalary H-segments reactive only to C-banding might be stable on chromosomes C and D, but variable on chromosome E in different karyotypes. In T. apetalon, the patterns of C-bands were similar to the cold-treated ones except for the occurrence of a few centromeric and telomeric bands and a granular intercalary band on chromosome D. In T. tschonoskii, both the patterns of C-bands in chromosomes and those after cold treatment were also similar to the cold-treated ones except for the presence of a telomeric band in chromosomes D and centromeric bands in chromosomes A and E. Thus, it is clear that the chromosomes of both species have only a few doses of other type (s) of heterochromatin besides the cold-sensitive heterochromatin. This contrasts with T. kamtschaticum.
Chromosomes of embryos developed from eggs of bitterling retained in the freshwater or the preservative solution before fertilization were analyzed. The percentage of gastrulation had a tendency to decrease, and an increase of chromosomal aberration was observed, in proportion as the time of retention of unfertilized eggs got longer. It is presumed that the retention of eggs is one of the main causes of the karyotype differentiation. Retention of eggs is necessary to be taken notice not only in the field of fisheries in which artificial fertilization is used frequently, but also in the field concerning the conservation of species.
Meiotic and mitotic chromosome numbers were determined for 14 taxa of Ferocactus. Chromosome numbers are reported for the first time for seven species, including two varieties of F. peninsulae, and chromosome counts were confirmed for an additional six species. All taxa investigated were diploid and have a basic chromosome number of x =11. Within the Cactaceae, Ferocactus appear to have the largest chromosomes. Meiotic figures in Baja Californian and Mexican mainland species failed to document hybridization at least for those populations investigated. The morphological homogeneity of chromosomes and the apparently consistent diploid condition throughout the genus suggest that chromosome evolution in Ferocactus is taking place at the molecular level.
Fluorescence in situ hybridization of an ultra-small red alga, Cyanidioschyzon merolae was performed using cytoplasmic rRNA as a probe for the first time. Sonication before fixing with glutaraldehyde was useful for in situ hybridization of this alga. rRNA was localized around cell nuclei. This method can be applied for the localization of mRNA in future studies.
Chromosomal analysis of the four Egyptian species, Agama savignii, Agama stellio, Utomastix aegyptius (Family Agamidae) and Eumeces schneideri (Family Scincidae) have been studied. The diploid chromosome number and fundamental number (FN) of A. savignii is 2n = 46 and FN = 46. The karyotype of this species have 12 pairs of uniarmed macrochromosomes and 11 pairs of microchromosomes. The diploid chromosome number and FN of A. stellio and U. aegyptius are 2n = 36, FN = 48 and 2n = 34, FN = 46, respectively. The karyotype of each species is composed of 6 pairs of biarmed macrochromosomes and either 12 pairs of microchromosomes as in A. stellio or 11 pairs of U. aegyptius. The diploid chromosome number and FN of E. schneideri is 2n = 32 and FN = 46. The karyotype consists of 10 pairs of biarmed macrochromosomes, 2 pairs of acrocentric macrochromosomes and 4 pairs of microchromosomes. No clear differences were observed in the sex chromosomes of both sexes. Comparison of the karyotypic data of these species had been discussed.
Meiotic chromosome configuration frequencies at diakinesis and metaphase I were tabulated in diploid and induced tetraploid Rosa laevigata Michx., diploid R. roxburghii Tratt., and tetraploid amphidiploids of R. laevigata with R. roxburghii and R. banksiae Ait. Numerical analysis of configuration frequencies suggests up to two-fold length variation between short and long chromosome arms in the diploids, and incomplete independence of chromosome arms during pairing and chiasma formation in the tetraploids. Since the sampled genomes pair homeologously in intersubgeneric amphidiploids, they are relatively closely related. The meiotic data collectively suggest that R. roxburghii should be classified in subgenus Rosa.