The populations of A. mentula from the Gulf of Naples, the Plymouth Sound and the west coasts of Scotland possess the same number of chromosomes, n=9. Like other species of the family Ascidiidae, A. mentula is characterized by pale and sticky oocyte bivalents, haploid number n=9, metacentric and submetacentric chromosomes only and embryonic mitoses where an anatelophase stage can be described. In common with all ascidians, A. mentula shows somatic pairing of homologous chromosomes and precocious distancing of daughter kinetochores in embryonic chromosomes. The only karyological character which differentiates A. mentula from other ascidians is the banding pattern revealed in stretched prophase chromosomes of early embryos.
The results reported here show that different PL treatments of different durations inhibit cell division and growth of lateral roots of Vicia faba. This inhibition is concentration dependent and is reversible only after treatments with low concentrations of PL. Experiments with radioactive precursors of DNA, RNA and protein show that their incorporation is inhibited by PL treatments. This indicates an inhibition of DNA, RNA and protein synthesis. Because of the positive charge of PL and negative charge of DNA, it is likely that they form a complex which inhibits the use of DNA as primer for DNA and RNA synthesis. This would result in inhibition of cell division and root growth.
Chlorophytum arundinaceum Baker (Liliaceae), collected from Bangladesh, was found to have i) 2n=4x=40 chromosomes and regular formation of 20 IIs in ca. 97% PMCs, ii) one ring quadrivalent and 18 IIs in 1.49% PMCs, iii) nearly regular disjunction at anaphases excepting a few cells showing one or more laggards and iv) only a few (1.49%) aneuploid (2n+2=42) PMCs. The plant seems to be an allotetraploid, also heterozygous for a reciprocal translocation between two nonhomologous chromosomes. The new basic number, x=10, is new for the genus and also for the tribe Asphodeleae.
Cytological data of 42 W. Himalayan taxa of Cyperaceae is presented. Nine species, Kyllinga triceps (n=48), Cyperus amabilis (n=19), C. cuspidatus (n=56), C. niveus (n=36), C. procerus (n=52), Scirpus erectus (n=37), Eriophorum comosum (n=26), Carex filicina (n=21) and C. nubigena (n=52) are investigated for the first time. New chromosome numbers have been reported in thirteen species, namely, Kyllinga monocephala (n=62), Pycreus capillaris (n=43), Cyperus compressus (n=48), C. corymbosus (n=54), C. difformis (n=18), C. distans (n=29), C. flavidus (n=8), C. haspan (n=18), C. iria (n=64), C. rotundus (n=48), Fimbristylis diphylla (n=5), Carex melanantha (n=24), and C. stenophylla (n=30). Base numbers x=14 and x=26 have been suggested for the genera Scirpus and Eriophorum respectively. The original base number for the family appears to be x=5, other numbers having been secondarily derived through aneuploidy and/or transverse breakage of chromosomes in genera possessing diffuse centromere. This latter feature may account for the small size of chromosomes in these taxa and also for the disparity in size of chromosomes in the genera constituting the family. The two cytological races in each of the three species Pycreus sanguinolentus (n=24, 25), Eleocharis palustris (n=7, 8), and Fimbristylis dichotoma (n=5, 10) did not show any significant morphological differences from one another except for slight variation in size of the inflorescence, and hence do not merit any different status.
Studies on normal meiosis and meiotic abnormalities in Aloe barbadensis have been carried out in detail explaining a high percentage of sterility in the pollen grains. A detailed karyomorphology from pollen mitosis is also presented. The failure of fruit-set is presumed to be because of high pollen sterility (58.3%) and self-incompatibility.
I developed a method for counting somatic chromosomes in embryo squash preparations of the parthenogenetic psocid Liposcelis bostrychophilus Badonnel. Numerous cells have been counted and the consistent somatic chromosome number is 16. This agrees with the diploid count for a sexual species in the same suborder. This somatic count differs from a previously reported meiotic count of 18 for L. bostrychophilus (Goss 1954). Application of the embryo squash method to the parthenogenetic psocid Lepinotus reticulatus Enderlein indicates a somatic chromosome number of 18. The counts for both species are in the normal diploid range for psocids based on testis material.
Karyotype and meiosis in diploid (2n=10) and tetraploid (2n=20) populations of Fimbristylis ovata (Burm. f.) Kern have been investigated. The 2 populations show only cytological differences, and are not associated with any absolute morphological difference.
Chromosomes being long, vary considerably within different metaphase plates, in length and proportion of arms or segments. Therefore mean values of segmental lengths of 20 chromosomes of each type of each strain has been considered in preparing the idiogram. Occurrence of a large number of chromosomal biotypes of L. odoratus, each having distinct chromosome morphology, suggests an important role of structural alteration by deletion, translocation, etc., in the evolution of different strains.
Cutting and removal of onion bulb scale epidermis injured those cells at and near the cut margin, as evidenced by rapid nuclear pycnosis. Quantitative interferometry revealed that pycnotic nuclei were 41.3% of normal in nuclear area (x. s.), 133.3% of normal in dry mass per unit area, and 51.5% of normal in nuclear dry mass.
Hinsichtlich der UV-Strahlenstich-Wirkung auf die Protoplasmaströmung wurden bisher noch keine Untersuchungen durchgeführt. Vorliegende Arbeit befaßt sich mit der Wirkung sehr kleiner UV-Strahlenbündel von 900 und 2500μm2 mit dem Strahlungsschwerpunkt bei 312, 6 nm auf die normale Rotationsströmung in den Wurzelhaaren der Gerste (Hordeum vulgare L.) unter dem Einfluß verschiedener chemischer Behandlungen. Es wurden zwei Versuchsreihen durchgeführt. Zur Untersuchung der Schutzwirkung von D-Glukose, myo-Inosit (10-3M) und ATP (10-3 und 10-5M) wurden die Wurzelhaare 30 Minuten vorbehandelt und anschließend 80 bzw. 120 Sekunden UV-bestrahlt. Die Reparaturwirkung der Testlösungen wurde durch die kontinuierliche chemische Behandlung nach erfolgter Bestrahlung untersucht. Die Versuche ergaben, daß myo-Inosit und insbesondere D-Glukose eine betonte Schutzwirkung ausüben, während ATP eine bedeutende Rolle als Reparaturfaktor spielt.
Ce travail étudie les modalités de production des réserves protéolipidiques par les cellules du gamétophyte femelle du Ginkgo biloba. Dès le début du mois de septembre, une strate à protéolipides et amidon apparaît. L'étude en cytologie électronique montre qu'elle est composée de 2 types cellulaires qui ne se distinguent que par la présence ou l'absence de ribosomes libres et le nombre des mitochondries. La signification de ces 2 types cellulaíres est discutée (2 catégories de cellules ou deux étapes de l'ontogénie d'un seul type). Le cytoplasme des cellules renferme des organites, limités par une simple membrane, où s'accumulent des produits de nature protéolipidique, comme l'ont montré des digestions par la protéase et la lipase. Ces organites sont en relation avec des travées du réticulum endoplasmique garnies de ribosomes. Ces structures sont semblables à celles décrites dans l'albumen de diverses espèces d'Angiospermes. Toutefois, chez le Ginkgo biloba, la production de protéolipides commence bien avant la maturation du gamète femelle.
A technique is described for staining both mitotic and meiotic chromosomes of rice. Important features are: comparatively long fixation; elimination of hydrolysis for root tip chromosomes; and phase-contrast microscopy. The chromosomes stain deeply, the amount being varied to suit any particular purpose by using different strengths of the stain. The technique brings out the morphological features of the chromosomes in their greatest detail.
Chiasma frequency at PMCs was studied in two successive generations of Aegilops speltoides, the one consisting of six populations, the other of four families. Each family was the progeny of a single plant taken from the corresponding population of the first generation. The analysis of data showed significant differences to exist between populations and between families, as well as between plants within populations and families. Among the overall material three subgroups were recognised. The first one, including two populations and the corresponding families, displayed the lowest inter- and intraplant variation of chiasma frequency in both generations, but a more asymmetrical pattern of chiasma distribution was found in families. The next group, represented by one population-family system, dimorphic by constitution, showed similar variability in population and family, with regards to chiasma frequency. The distribution of chiasmata has proven partly similar, including the same proportion of the predominant bivalent type. The third category was the most variable, containing a B-carrying class, in which mean chiasma frequency differed significantly between the two generations, being lower in B-family. The suggestion is that B chromosomes, when accumulated, exert a reducing effect on chiasma formation.
Mitosis in the root-tips of Hydrocleis nymphoides occurs throughout day and night with interphase and prophase always predominating and showing a negative correlation with each other. Except for interphase, all the stages are generally more frequent during the day. High temperatures appear to boost interphase and prophase stages whilst low temperatures boost metaphase, anaphase and telophase.
Cytological investigations were carried out in 17 orchid taxa from Kashmir. Listera kashmeriana, and Habenaria digitata were cytologically unrecorded earlier. Aneusomaty was observed in Neottia listeroides. Goodyera repens exists as 2 morphologically indistinct aneuploid cytotypes whereas for Spiranthes sinensis, Herminium angustifolium, Habenaria edgeworthii, Orchis latifolia and Satyrium nepalense, it is presumed that these probably occur only at higher ploidy levels in Kashmir Hills. Following karyotypes were established: Cypripedium cordigerum: K (2n)=20=4Em8Fm4Fa4Gm Cephalanthera ensifolia: K(2n)=34=14Am8Bm6Ba2Da2Ea2Fa Epipactis gigantea: K(2n)=40=2Aa20Bm2Ca2Cm6Dm4Ea2Em2Fa Neottia listeroides: K(2n)=40=4Bm20Cm2Ca6Dm4Da2EmEa Listera kashmeriana: K(2n)=42=6Bm2Ba12Cm2Ca16Dm2Da Goodyera repens: K(2n)=30=14Am16Bm Setyrium nepalense: K(n)=82=14Am68Bm
The fertility of 53 haploids of Capsicum annuum L. was determined. The haploids, derived from twin seedlings, were highly male-sterile but all produced seeds following crosses with pollen from diploids. The numbers of seeds per fruit varied from none to eight. Irregular distribution of the seeds, together with male-sterility, disclosed that spontaneous diploid branches did not develop in the haploids. The origin of the seeds is attributed to the sporadic failure of function of one division during meiosis. As a result of atypical meiosis in haploids, deviations in chromosome number and structure have been reported in the offspring of haploids of other species. An average of one seed per hand-pollinated haploid fruit of pepper was obtained. This degree of female fertility should permit the accumulation of useful cytogenetic variants in this species.
Seven interchange trisomics were isolated from the progeny of interchange heterozygotes T1-4, T3-7 and T2-6. Their morphology, sterility and cytology were studied. On the basis of the morphological characters, the trisomics were classified into five types namely, bush, slender, pale, robust and purple.
A comparative study of the male meiosis in the rose cultivar ‘Pink Parfait’ and its two, Deep and Light pink flowered mutants was conducted. ‘Pink Parfait’ was found to be a segmental allotetraploid. The frequency of univalents and quadrivalents at metaphase I was higher in the mutants. Anaphase I revealed a higher incidence of lagging chromosomes in Deep pink mutant and an increased frequency of chromosome bridges in both the mutants. The deleterious effects of radiations were evident from the higher percentage of chromosomal aberrations and pollen sterility found in mutants as compared with the control.
Pollen and spikelet sterility in F2 populations of three indica×indica crosses and three indica×javanica crosses were studied. The most sterile of the F2 plants from three crosses were examined cytologically. The most common indications of structural hybridity at pachynema were loose pairing, partial pairing, and reciprocal translocations. Univalents, quadrivalents, aneuploid chromosome numbers, and fragments were observed at diakinesis and metaphase I in all three crosses. Unsplit bivalents, unequal or late disjunctions of chromosomes, laggards, and anaphase bridges were found at anaphase I and telophase I. Moreover, a variety of nonchromosomal aberrations was found at each meiotic stage. The wide array of meiotic aberrations suggests both structural hybridity and complex gene interactions.
The morphological and cytogenetic features of the natural and artificial hybrids between tetraploid H. jubatum (2n=28) and hexaploid H. parodii (2n=42) have been studied. The hybrids, which were pentaploid, approached in quantitative morphological traits the parental species which contributed a higher number of genomes (H. parodii). The meiosis was highly irregular and variable. The average cell had about half of its chromosomes as univalents, slightly less than half were forming bivalents and the few remaining, multivalent associations (III, IV, very occasionally V). Electrophoresis of seed proteins revealed that homology of fractions in both parental species is not high (coefficient of similarity=47.82%). Chromosome pairing probably results from both allo- and autosyndesis. In contrast to the not too close phylogenetic relation of both species as revealed by morphology, chromosome behaviour in the hybrid and protein homology, the crossability of both species is rather high.
1. Cytomorphic and cytochemical studies were made on the adrenal cortex and medulla in the garden lizard, Calotes versicolor at 4, 24, 72 and 120 hr stages following a single intramuscular injection of reserpine (0.8 mg/100 g body wt.). 2. The concentration of the total catecholamines in general as well as noradrenaline in particular, and the total catecholamine-containing as well as noradrenaline-containing areas became reduced at 4 and 24 hr stages, but remained similar to those in the corresponding controls at 72 and 120 hr stages. Significant alteration in the average nuclear volume did not occur at any of the selected experimental periods. These findings indicated that reserpine induced initial depletion of the stored noradrenaline (and adrenaline?) but did not lead to any remarkable activation of the adrenomedullary cells. 3. The ascorbic acid concentrations in the adrenocortical cells in most or all of the experimented lizards decreased at 4 and 24 hr stages but remained along the control level of concentrations at subsequent periods (72 and 120 hr). The average nuclear volume of these cells increased significantly at 24 hr stage only. These findings indicated that reserpine stimulated adrenocortical activity that persisted at the initial experimental stages (4 and 24 hr) and subsequently attained the control level of activity.
1. Karyotypes of 6 jute (Corchorus) species are worked out. Detailed measurements of chromosomes are given. Karyotype formula for each species is given on the basis of measurements in this genus. 2. Evolution seems to be divaricate but intricate also.
1. Based on chromosome counts of more than 1000 cells from 231 plants in the Tôhoku District, Anemone Hepatica var. japonica is determined to be diploid with a basic number x=7. 2. Utilizing the Levan, Fredga and Sandberg (1964) definition of chromosome types, the chromosome complement consists of 2 pairs of M, 4 pairs of m and 1 pair of t chromosomes, among which the t chromosomes have satellites (Figs. 1, 2, 3). 3. No karyotypic difference was found between the two forms, f. magna and f. variegata. 4. 10 morphological variations, i.e., 3 basic homomorphic pairs, 3 intermediate and 4 derivative heteromorphic pairs from the basic ones, have been recognized for the seventh satellite chromosome pair (Fig. 4, Table 4). 5. On the basis of analyzing the morphological variation of the seventh satellite chromosome pair among 7 populations, it is apparent that 2 basic types (1, 2) and the intermediate and the derivative types of them (1-2, 1', 1-0, 2-0) dominate over the other types (3, 1-3, 2-3) (Fig. 17, Table 4). 6. Supernumerary chromosomes are not uncommon among the populations in the Tôhoku District; the frequency of plants with supernumerary chromosomes is sometimes high (Fig. 18, Table 5). 7. Intra- and inter-individual numerical variation of supernumerary chromosomes is observed in some populations (Table 6).
A new air drying technique combined with ASG banding has enabled the construction of detailed karyotypes for two species of butterfly, Pieris brassicae L. and Polyommatus icarus Rott. Primary constrictions (primary centromeres) at early mitotic metaphase are clearly visible on chromosomes before they become highly condensed, suggesting that the chromosomes are not holokinetic for the entire cell cycle. Primary centromeres were not seen at meiosis. Confirmation that the female is the heterogametic sex was obtained, and size comparison and banding patterns indicate that the sex chromatin body in the female interphase cells is a heteropycnotic X chromosome. The sex chromosome pair in these species is heteromorphic. In a third species Pieris napi L. which also has heteromorphic sex chromosomes in the female, achiasmatic bivalents were seen in oocyte meioses. Chiasmata were found, however, in the male meiotic cells of all three species.
A detailed cytological analysis of different genera of the family Cruciferae has been carried out in order to find out the role of structural differences in the phylogeny of Brassica and the allied genera. The genera studied grow wild and cultivated throughout India. The present study reveals that several chromosome numbers exist within the group of Brassica. But inspite of difference in chromosome number that there is a relationship between different genera, is quite obvious as evidence from the karyotype. The basic chromosome number for Brassica which has been assumed to be 6 is probable and intricate relationship between different genomes of this group has been suggested. The new chromosome number of Senebiera pinnatifida has been noted as n=8. An interesting correlation between diploid and polyploid species along with their ecology has been observed in Cardamine hirsuta collected from different altitude of the Himalayas has been discussed. A particular type of cytotype has been observed in Nasturtium indicum with n=12 to 24 chromosomes. The presence of 12 chromosomes in the genus Nasturtium may suggest that in the tribe Arabideae too, the basic type should be 6 as in Brassiceae. On the basis of previous and present observation, it has been claimed that aneuploidy and diminution in chromosome size have played a significant role in evolution. But such diminution must have occurred within each of the tribes independently evolving from a common basic type. The lower or higher numbers might have had their origin from such a basic set and the diversification in number and structure of chromosomes must have evolved in parallel lines from a common basic ancestor.
Three stable aneuploids 2n=80, 82, 84 were isolated from the colchiploid N. umbratica-megalosiphon. No morphological differences were detected between these aneuploids. Meiotic irregularities were recorded in the first few generations and reduced as the generations advanced. It was concluded that the phenotypic characters were fixed at the F1 level itself and the addition of excess chromosomes to the F1 complement had no visible effect on the phenotype. The above aneuploids support Goodspeed's postulate (1954).
Studies were made on the fine structure of chromosomes by using both ultrathin sections and whole mounts of chromosomes in the pollen mother cells of Tradescantia reflexa. Chromatin threads of 100Å, 300Å, 1000Å and 3000Å were seen in the chromosomes. The 300Å-chromatin thread seems to be the basic thread of the chromosome. The 1000Å-chromatin thread consists of at least four 300Å-chromatin threads and the 3000Å-chromatin thread (chromonema) is formed by coiling of 1000Å-chromatin thread. The 300Å-chromatin thread is formed by coiling of a 100Å-chromatin thread, consisting of DNA-histone complex. The DNA double helices may be encircled with, or embedded in histone. The constitution of the DNA-double helices enveloped in histone is discussed.
C-mitotic activity of colchicine and crude extract obtained from G. superba was tested and C-mitotic potency was scored according to the system proposed by Greenberg et al. (1966). It was observed that 100, 75 and 50 ppm solutions of Gloriosa colchicine induced C-mitotic and C. tumor reactions. While crude extract at lower concentration (2.5% of dried rhizome powder) gave very promising results in inducing C-mitosis but higher dosages (5, 10, 15 and 20% of dried powder) were lethal and prevented mitotic initiations and normal course of mitoses in the dividing tissue. The roots with C-tumors when returned to water resumed their further growth. Therefore, it is concluded that Gloriosa colchicine has similar micro and macroscopic effects to that produced from colchicine obtained from Colchicum autmunale Linn.
In Japan, two types of P. distichum were observed. One is a clone with 2n=40 and the other with 2n=60. At MI of PMCs, chromosome configurations resulting from RT-heterozygote were observed. Low fertility in seed may result from above chromosome configurations at MI as univalent, trivalent and tetravalent showing RT-heterozygote.
1. Mature hybrids were raised from P. mungo _??_ × P. calcaratus _??_ cross by culturing the embryonic axes of the hybrid seeds in nutrient solution with 4 per cent sucrose. 2. The F1 plants resembled one or the other parent in some characters and were intermediate between them in others. These plants had an average pollen fertility of 0.7 per cent and did not set pod. 3. In F1, the average chromosome configuration per cell at MI was 0.05IV+4.24II+13.32I. One quadrivalent was noted in 5.1 per cent of cells. Dicentric bridges with acentric fragments were noted in 3.3 per cents of cells at AI. Dicentric bridges were observed in 4.7 per cent of cells at AII. At pachytene, some loosely paired bivalents with terminal and interstitial differential segments were noticed. 4. Colchicine induced amphidiploid (AI generation) plants had an average of 81.0 per cent fertile pollen and they produced few pods with viable seeds. 5. The role of hybrid inviability, weakness and sterility as isolating barriers has been discussed. The hybrid sterility is segregational in nature. The significance of structural alterations in speciation has been discussed.
1. Meiotic and pollen development studies have been carried out in a garden variety of aloe. 2. Meiosis is extremely abnormal resulting in 87.19% pollen sterility. 3. Laggards in various number, anaphasic bridges, precocious separation of chromosomes and chromosomal arms, a single PMC giving from 4-8 microspores (polyspory) with one or more supernumerary nuclei and cytomixis are some of the abnormalities during meiosis I and II. 4. Flowering is infrequent and from cytological and morphological studies the plant appears to be an interspecific hybrid between Aloe abyssinica and Aloe ferox.
1. Cytological investigations have been made in Chara hydropitys collected from Darbhanga (India). 2. A normal chromosomal count of n=14 is obtained in this species. 3. An aneuploid number, n=8, is reported in this species which appears to be a new record. 4. On the basis of available data in hand, n=8 is the lowest aneuploid number recorded in any Charophyte. 5. n=8 serves to demonstrate the potential variability of construction of functional genome in the genus Chara and the tribe Chareae. 6. Godward's (1948) Schedule is followed throughout the course of cytological investigations.
The action of four proteolytic enzymes viz. trypsin, pepsin, pronase and collagenase, on the chromosomes of living microsporocytes of Rhoeo discolor was studied. Continuous observation for a period of 4 hours indicated that the solvents in which the various enzymes are dissolved had a little effect on the chromosome morphology, which can be minimized by making the solution isotonic with sucrose. All the enzymes are finally capable of producing distinct dissolution of the chromosomes, but the intermediate steps towards dissolution are different. On the basis of specificity of the enzymes, it has been concluded that histones are responsible for coiling of chromosomes and nonhistones play an important part as a ligand macromolecule.
The mitotic activity of bovine lymphocyte cultures was used as a measure of the cytotoxicity of the synthetic estrogen, diethylstilbestrol diphosphate (DESdp). Phytohemagglutinin stimulated cultures from three unrelated crossbred steer calves matched for age and weight were divided into dose and time treatments. DESdp was added to the cultures for the entire 72 hour culture period, the last 48 or the last 24 hours at one of the following concentrations: 2.5×10-5, 2.5×10-6, 2.5×10-7, 2.5×10-8, or 2.5×10-9 M. Mitotic indices between animals were not significantly different. The duration of treatment had no significant influence on the rate of cell division but the DESdp concentration produced highly significant differences (P<0.01) in the percent of cells undergoing mitosis. Analysis of dose group means failed to demonstrate a linear dose response in mitotic index depression.
The karyotype and chromosome behavior of C. capitata were studied both in mitosis and meiosis. The chromosome number is 12 (n=6), and includes two pairs of metacentric chromosomes, two pairs of submetacentric and two pairs of subtelo-centric chromosomes. The sex chromosomes are well differentiated in size, and the X chromosome is typified by a secondary constriction. The somatic chromosomes display somatic association, which can be relaxed by colchicine. Spermatogenesis is typically chiasmatic, suggesting that recombination occurs in the male. The study was supported in part by the Israel National Council for Research and Development.