Artificial triploids were raised in Luffa echinata by crossing colchicine induced tetraploids with diploids. The triploid plants were gigas in nature and had morphological features intermediate between diploid and tetraploid. Meiosis was characterised by the presence of a high frequency of trivalents and univalents. These triploid plants are being inter crossed with the diploids used in our breeding programme to establish the heterogamety of sexes in this particular species, thereby to explore the genetic basis of dioecism.
1. The cytological effect of papaverine hydrochloride, which is an alkaloid found in the opium was studied on mitosis of Allium cepa root tips. 2. Papaverine hydrochloride induced a wide range of abnormalities. The most effect was exerted on both metaphase and anaphase C-metaphase, C-anaphase, non-congression, diagonal anaphase, chromosome and chromatide bridges, lagging of chromosomes, micronuclei and multinucleated cells were observed. 3. Papaverine hydrochloride is the only one amongst the alkaloids of opium which caused a high increase in MI after long period of treatment with some low concentrations.
Oenothera suzukiana R. Jean et R. Linder, die wir Herrn Professor Tokio SUZUKI aus Ooita widmen, ist eine Oenothera der Untergattung Oenothera, Sektion Hookeri. Sie wurde bei Koyaguchi, im Norden des Kii-Hanto Gebirges, Provinz Wakayama, gefunden. Diese Oenothera zeichnet sich durch folgende Merkmale aus: hohe Staude, besonders an der Basis verzweigt; Stiele hellgrün, in der oberen Hälfte rot getupft, kurzhaarig; Blatt oval bis länglich-lanzettlich, spitz, weissnervig, auf der dorsalen Seite fein behaart; Infloreszenz aufrecht mit auswärts gebogenen Brakteenspitzen; Blütenknospen sehr gross, wegen der Länge des Hypanthiums (4cm.), etwas kleiner als bei Oe. Jamesii; Kronblätter 4cm. fang; Blüte mässig langgrifflig. Das Pollenbild zeigt zwei Kõrnerklassen: die normalen lebenden Kõrner and die leeren Kõrner (20%). Das Diakinesebild der männlichen Meiocyten zeigt einen Ring von acht Chromosomen und drei Bivalenten. (Latainiche Diagnose am Schluss). Die chromosomal-strukturellen und die genetischen Merkmale bestätigen, dass Oenothera suzukiana der Sektion Hookeri zugehört. Die Komplexe, die sich in der Meiosis aufspalten, nennen wir nippovelans and hantohookeri. Sie sind zugleich im Pollen and in den Eizellen aktiv. Die Chromosomenformel ist folgende: -nippovelans: 5.8 9.10 7.6 12.11 1.4 2.3 13.14 - hantohookeri: 8.9 10.7 6.12 11.5 1.4 2.3 13.14 Die zwei Komplexe sind strukturell der Oe. hookeri T. und G., forma Johansen sehr nahe, deren Genom als primär betrachtet wird. Phenotypisch sind die zwei Komplexe in den meisten F1-Hybriden nicht unterscheidbar. Nur in einigen F1-Typen ist der hantohookeri-Phenotyp durch ein breiteres Blatt, eine Kängere Blütenknospe and eine grössere Blüte (Kronblatt 3, 5-4, 5cm. lang) gekennzeichnet. Dagegen zeigt der nippovelans-Phenotyp ein lanzettliches Blatt, eine kürzere Blütenknospe und eine kleinere Blüte (Kronblät-ter zwischen 2, 5 und 3, 5cm. lang). Die Genom/Plastom Kombination gehört dem AA/I Typus an, der die Hookeri Sektion charakterisiert. Ausserdem ergibt nippovelans mit velans eine inkompatible Kombination, die einer homozygotischen Kombination ähnlich ist. Die Analyse der Oe. suzukiana führt zu der phytogeographischen Schlus-sfolgerung die den nordamerikanischen Kontinent als Genzentrum für die Untergattung Oenothera bestätigt.
Ectopic pairing in the salivary chromosomes of Anopheles stephensi Liston is being reported for the first time in mosquitoes. The pairing involves bands located at different regions of the same chromosomal arm (2R) as well as inbetween two different arms (2R and 3R). The origin and nature of such bands has also been discussed.
A study of the sex chromatin in the buccal smears of 197 girls from Kashmir (India)-100 Kashmiri Pandits and 97 Kashmiri Muslims-is carried out to know the frequency of the sex chromatin in this rare small population, distributing in the cold climate area; 5, 000 feet high. The range of the sex chromatin was found to be 0.0% to 40.0% in Kashmiri pandits, and 10.0% to 37% in Kashmiri Muslims, with the average frequency of 20.88%±0.64%, and 19.31%±0.54%, respectively. Of six abnormal cases observed, five were doubted to be mosaics showing single and double sex chromatin masses; three were suffering from acidity. The sixth abnormal case was chromatin negative. The data of Kashmiri Pandits and Kashmiri Muslims shows statistically non-significant difference (.80>p>.70).
G- and C-band patterns for 11 species of New World Myotis are herein described. The karyotypes have remained highly stable during the evolution of this group, all species studied possess 2n=44 with four pairs of biarmed autosomes and a biarmed X. The only variation encountered is the size of the Y chromosome and chromosome 25, which is typically a minute a arocentric but in some species is a metacentric. The variation in both the Y and number 25 chromosomes is due to differing amounts of C-band positive heterochromatin. Three species of American “long-eared” Myotis appear to be karyotypically derived. A nomenclatural system is proposed for vespertilionid chromosomes in which each autosomal arm is numbered and each band is numbered beginning at the centromere. There are more than 200 bands identifiable in the G-band karyotype of Myotis.
Meiotic studies in 14 taxa belonging to 13 species and 7 genera of the family Urticaceae have been carried out from the hills of Darjeeling (E. Himalayas). Seven species marked* in Table I have been investigated for the first time and new chromosome numbers are discovered for another 4 species marked † in the same table. Evolution of basic chromosome numbers in the family is briefly discussed.
An extensive cytological investigation of the endosperm of Haemanthus katherinae revealed the following. The endosperm is basically triploid (3n=27) even though it becomes mixoploid by increasing incidence of endopolyploidy with advancing maturity. This endopolyploidy is caused by mitotic inhibition either at prophase or metaphase. Spontaneous chromosome aberrations were very frequent especially in degenerating endosperm. Also the inflammation of chromosomes causing stickiness, unique unravelling of chromosomes into extremely long hair like structures, nuclear polymorphism, amitosis and nucleolar fragmentation were salient features of degenerating endosperm. It is concluded that the above abnormalities may be causing spontaneous fruit abortion in Haemanthus katherinae.
Pachytene pairing in relation to pollen fertility was studied in five cultivars of cassava. The two highly pollen fertile clones showed only normal pachytene and later meiotic divisions were also normal. However, in the partially pollen fertile clones different pachytene abnormalities like non-pairing, deletion, duplication and inversion were found in different chromosomes. In C1-1443 as many as five bivalents showed aberrant pachytene pairing. Though there was a slight reduction in chiasma frequency, later divisions were normal. Based on the extent of pachytene abnormalities in different clones, reduction in chiasma frequency, meiotic sequence and normal tapetum development and microsporogenesis, it is concluded that pachytene behaviour had a statutory role in determining the ultimate pollen fertility in cassava.
Chiasma frequencies were determined following seed irradiation of three varieties of H. annuus. Histograms of chiasma frequencies between nuclei, show differences between the controls of the three varieties studied. Differing varietal response to radiation was indicated at high doses with a marked reduction in chiasma frequency with dose in one variety and a tendency in this direction in the two others, as shown by the slopes of the regression lines for Xta on dose. Reduction in the mean chiasma frequency is found to be associated with decline in the mean squares within nuclei. There is a lack of correlation between different bivalents of the nucleus both in the control and irradiated material and this, as in other plants, is found to be associated with the symmetrical nature of the karyotype in this plant.
The inheritance of chromosome deficiency and duplication was studied in two mono-trisomic lines of oat Arena sativa L. The mono-trisomics were produced by crossing two different monosomic lines with a line, tetrasomic for an unidentified chromosome. The constitution of the progenies of the two mono-trisomic lines was determined by studying chromosome pairing at metaphase I. The inheritance of the deficiency and duplication in mono-trisomic lines was determined by the transmission of the deficiency in the respective monosomics and the duplication in the trisomic. The ability of aneuploid gametes to function was dependent on their chromosome constitution. Restoration of the haploid number of chromosomes did not improve the competitive ability of the pollen if the haploid number involved a deficiency and a duplication. Male gametes which were nullisomic and disomic for a particular chromosome were at a selective disadvantage in competition with haploid gametes. Since the chromosomes involved in the two original monosomic lines did not belong to the same homoeologous group as the chromosome in the tetrasomic line, there was no indication of compensation at the gametic level. Nevertheless, it was possible to isolate the nulli-trisomic lines from the progeny of both mono-trisomic lines. Nulli-tetrasomic genotypes of nulli I, II, IV, VI, VIII, IX and X with the unidentified tetrasome were compared, but revealed no morphological compensation as they were extremely weaker than 43 and 44-chromosome type plants. No compensation in these genotypes indicates that the chromosomes involved in the parental monosomic and tetrasomic lines do not belong to the same homoeologous group.
When kept at 4°C for 24h, growing cells of Micrasterias crux-melitensis lost their septa or cell walls which had separated the cells into two daughter cells, forming binucleate cells. These binucleate cells grew into double cells, each of which consisted of a middle section and two side sections. Five types of multiplication for the double cells were observed; two normal cells and a double cell were produced from a double cell in the first type; a normal cell, an anucleate cell and a double cell in the second type: two presumably anucleate cells and a double cell in the third type; an apparently normal cell and a triple cell in the forth type; and a quadri cell in the fifth type. These five types originated from different distributions of daughter nuclei in the daughter cells. When the middle section of a double cell was very small, no daughter half cells were formed from the middle section, though the middle section had two nuclei in it. The anucleate cell and the effect of the position of the nucleus upon the growth of daughter half cells are discussed.
Cytological studies in 49 taxa belonging to 27 genera and 39 species of grasses from the plains and hills of North India have been carried out. One species Agropyron striatum has been cytologically investigated for the first time and new chromosome numbers have been made available for 8 more species. These species are: Agrostis semiverticillata (n=21), Helictotrichon virescens (n=21), Dactyloctenium aristatum (n=20), D. sindicum (n=10), Festuca modesta (n=7), Sporobolus.fimbriatus (n=27), Oryzopsis munroi (n=12), and Paspalidium flavidum (2n=44). Accessory chromosomes have been reported for the first time in Phleum himalaicum, Agropyron striatum, Polypogon fugax and phalaris minor.
Three indices were used to classify oral cells from foals and their dams. These were: Cell Development Index; Karyopycnotic Index; and Maturation Index. Cells were classified on the relative sizes and nuclear traits using epiflourescence ultra-violet and phase contrast microscopy. Five mares were studied. The 7, 000 cells evaluated over a four-month period showed the highest percentages of cells observed in smears were anucleate (about 80%) and the next highest were intermediate cells with oval nuclei (15%). There was a seasonal trend in that intermediate cells decreased from about 27% in May to 11% in August while anucleate cells increased over that period from 67 to 85%, respectively. About 4, 000 cells from five foals showed the highest percentages of cells observed in smears were anucleate (about 49%) and intermediate cells with oval nuclei (about 41 %). As foals became older, the percentages of intermediate cells with oval nuclei decreased while anucleate cells increased. These changes were rapid, often within one week. We cannot explain either of these exfoliation changes.
Electron microscope observations were made with green, light-green, and yellow leaf tissues of the soybean mutant Ym18. The ultrastructure of chloroplasts from green plants was not influenced markedly by temperature (19°C or 29°C) or illuminance (22 klx or 87 klx). Disruptions of chloroplast grana stacks were observed in yellow plants grown at 29°C with illuminance of 22 klx. At 19°C and illuminance of 22 kix, yellow plants had isolated grana stacks, separation of the lamellae, and increased numbers of osmiophilic bodies per chloroplast. Light-green leaf sectors were found to be mixtures of tissue layers with either normal chloroplasts or aberrant chloroplasts. At 29°C and illuminance of 87 klx, yellow plants had no starch grains or grana stacks. The lamellar system was restricted to long parallel lamellae with only occasional overlaps. The presence of lamellar whorls was assumed to be a possible indication of plastid degeneration. Major and minor element composition of leaf tissue was similar throughout the three genotypes, eliminating deficiency of these elements as a possible major cause for the different phenotypes.
Relative DNA of onion bulb scale inner epidermis was 2.21 times that of outer epidermis. DNA correlated well with nuclear dry mass, nuclear area, and nuclear dry mass per unit area. A relationship of these characteristics to development through cell size is postulated.
The effects of the insecticide O-4-brome-2, 5 -dichloro-phenyl O-methyl phenylthiophosphonate “Leptophos” has been studied on: root-mitosis, seed-germination, root- and shoot-lengths of Vicia faba. Two types of treatments were conducted: seed-soak and root-treatments. Both treatments affected a significant percentage of abnormal mitoses. Seed-soak treatments for 48 and 72 hours affected marked inhibition of cell division. Disturbed prophases, meta- and anaphases (where the chromosomes spread irregularly in the cell) comprised the main type of the observed anomalies. Lagging chromosomes and chromosome fragmentation were also observed. Soaking the seeds in a saturated solution of Leptophos for 72 hours caused marked inhibition of root- and shoot-growth, which was attributed to the inhibition of cell division.
The present study deals with an interesting nucleus of a freshwater Indian dinoflagellate which is designated here as Gymnodinium sp. NBG 76. Chromosomes appear as small dots or short rods and are too many to be counted for their exact numbers. However, an estimate of 514±10 chromosomes was made from suitable preparations. The presence of rod-shaped chromosomes and uniform condensation of the latter even at interphase reflect on its dinocaryotic nature. The unusual nuclear structure of this taxon has been discussed in relation to the dinokaryotic nuclei met with in other taxa.
The cytological effects of paper mills effluents on somatic cells of Allium cepa were presented. The cytological effect decreased by decreasing the concentration of the effluents. Disturbed metaphase, anaphase and telophase, occurrence of binucleate and tetranucleate cells comprised the most dominant types of abnormalities. Clumping of chromosomes, contracted chromosomes, pleiomorphic and micronuclei formation, cell vacuolation and polyploid cells are found less frequently. The c-mitotic effect and other abnormalities may be due to the action of alkalies, acids and bleaching agents present in the paper mill effluents.
The comparative results of karyotypic investigations of murine leukemia cells L1210 growing in vivo and in vitro are presented. The frequency of normal chromosomes in both lines differs as follow: in the in vivo line monosomia of chromosomes of pairs 4, 17, and 19 is frequent, while the in vitro derivate shows monosomia or even complete absence of chromosome X. Both lines have two chromosomal markers characteristic for leukemia L1210. Further, the parent line had two metacentric markers, one of them come from 5-12 fusion, being common to both lines, whereas the other from 9-marker M4 which is exclusive in in vivo cells.
Four Japanese members of Chionographis were investigated karyologically. Both C. japonica and C. koidzumiana had 2n=24 chromosomes, while C. japonica var. kurohimensis and C. japonica var. hisauchiana had 2n=44 and 2n=42 chromosomes, respectively. In the interphase nuclei, many small heteropycnotic segments, the number of which surpassed frequently the somatic chromosome number of each species, were observed. The chromosomes at early prophase had also many small precociously condensed segments, showing the beaded configuration. The chromo-somes at metaphase lay flat on the equatorial plane, and had no particular structure suggesting the presence of a localized kinetochore. The sister chromatids at ana-phase underwent a parallel disjunction. These observations of the chromosomes at metaphase and anaphase have suggested that the somatic chromosomes of all the species studied are holokinetic (holocentric). Relationships between the species were also discussed briefly from a karyological standpoint.
Fluorescence analysis of the karyotypes of two species of Encephalartos has revealed the presence of considerable amounts of heterochromatin. The heterochromatin is present mainly on two of the chromosome pairs, in one of which it is associated with the nucleolar organising regions. The significance of the heterochromatin is discussed relative to the highly specialised nature of cycad species.