The daily mitotic cycle of the common onion, Allium cepa, comprises 54.14±1.07% interphase, 39.07±0.99% prophase, 2.39±0.26% metaphase, 1.56±0.26% anaphase, and 2.77±0.38% telophase on the average. Interphase always has the highest frequencies followed by prophase; and anaphase always has the lowest. Interphase and prophase are more predominant with the warm temperatures of the afternoons and evenings, but the other stages appear to be favoured most by the low morning temperatures. A highly significant and negative correlation exists between interphase and pro-phase frequencies, and also between telophase and interphase frequencies; the cor-relation between metaphase and anaphase frequencies, and also between anaphase and telophase frequencies, is also highly significant but positive. On the basis of these high correlation trends, regression equations for pairs of succesive mitotic stages have been proposed as perhaps distinctive of the Allium cepa mitotic cycle. There is however no significant correlation between prophase and metaphase frequencies.
A comparative study of microsporogenesis in male fertile and male sterile C. pallida was conducted. The developmental pattern for fertile microsporogenesis was compared with the developmental pattern in sterile plants to determine the time of microsporogenesis breakdown. The first abnormality was observed in the tapetal cells. Although normal tetrads were observed in male fertile plants, no tetrads were observed in the male sterile plants. It is suggested that sterility is due to differences in tapetal behaviour and failure of cytokinesis in male sterile type.
Feeding of ink-fed Tetrahymenas to Amoeba proteus cells has enabled a reliable qualitative and quantitative study of Amoebian phagocytosis. Pretreatment of the Amoebas with histamine resulted in an increase in the percentage of cells phagocytizing Tetrahymena, and in the number of Tetrahymenas phagocytized per cell as well. Apparently, the unicellular Amoeba is able to respond to histamine, a hormone of higher organisms, from which it follows that the effect of, and the response to, histamine, is presumabley universal in the animal kingdom. Microcinematographic analysis revealed no difference in the mechanism of tetrahymena endocytosis between Amoebas treated and not treated with histamine, but showed that pseudopodium formation and quantitative intake of Tetrahymenas in unit time tend to increase under the influence of histamine.
Karyotypic details, chromosome behaviour during male and female meiosis and the development of embryo sac in Vicia faba L. have been described. The details of female meiosis and the embryo sac development have been studied for the first time in this species using the squash technique. The chiasmata frequency in the male sporogenous cells of this species has been found to be more than that in the female sporogenous cells. The megaspore mother cell gets differentiated after the microspores are fully developed in its anthers. However, the dehiscence of the anthers is delayed and takes place only after the embryo sac of the same flower is fully developed. This ensures selfing in this species.
Mitomycine at high concentrations cause the splitting of the lymphocytic nuclei and inhibits the formation of the mitotic metaphase plates; at average concentrations and under the chosen conditions of experimentation, it determines various chromosomal abnormalities: stretchings, constrictions of the chromatides and even ruptures. The constrictions observed have an arrangement comparable to band systems, but without precise correspondence with the G and R labeling systems.
Detailed karyomorphology of three species of Kaempferia from South India has been studied, namely K. angustifolia (2n=36), K. rotunda (2n=44) and K. galanga (2n=54). Karyomorphological data indicate that karyotypes of all the three species are moderately asymmetrical (2A). Karyotype asymmetry has been more through structural rearrangement resulting in shift of centromere position. Chromosomal evolution in the genus is discussed in the light of available cytological findings. The data show that species of the genus constitute different basic series such as x=11, 12, 13 and 14 of which x=11 is most predominant. Polyploidy and aneuploidy at polyploid levels have been most operative among x=11 species. The present karyomorphological data showed that structural alternation of chromosomes also have played some role along with polyploidy in the evolution of the genus.
Three species of Tolypella Leonh. viz. 1, 2 and 3 have been cytologically investigated and their karyotypes have been worked out. The chromosome numbers in last two named taxa have been reported for the first time and hence are new to the science. In T. nidifica, present count is at variance with the previous report. Taxonomical distinction of taxa at hand has been discussed in the light of conclusions drawn from cluster analysis (by distance) on the basis of karyotypic data like chromosome number, total chromatin length, TF% and coefficient of variation.
The cytomorphological investigations of an induced polyploid of Hevea brasiliensis are given. The induced polyploid showed morphological variations like more leaf thickness, prominent veins and veinlets, varied number of leaflets and large floral parts. Mitotic studies have confirmed that the plant is a tetraploid with 2n=72 chromosomes. At metaphase I, besides bivalent formation, univalents, trivalents and quadrivalents were also observed. It supports the view of amphidiploid origin of Hevea brasiliensis.
Detailed somatic and meiotic studies in the two populations of Eclipta alba (L.) Hassk. of the family Compositae have been carried out. Collection of materials for cytogenetical studies has been made from their natural populations. In the populations Ea0776 and Ea1476, the karyotypic studies reveal that the haploid number is eleven. The two populations have different pairs of chromosome which varied in length. The karyotype of population Ea0776 is more asymmetrical. Meiotic studies in the two populations show the chromosome number as eleven and there is also both regular and irrregular meiosis. There are differences in the nature of chromosome association and chiasmata in these populations. Plasticity shown by a genotype when expressed is able to be altered by environmental influences.
During investigation of meiotic behaviour of wild triploid Colocasia antiquorum Schott, desynapsis as well as inversion heterozygosity were found in the same plant of a population. Partial pairing of chromosomes at diakinesis and lack of pairing at metaphase I were found. Variable number of univalents, viz., 42 and 14 were found in pollen mother cells at metaphase I. This stage also was characterized by pycnotic behaviour of chromosomes. Bridges with fragment at anaphase and telophase one and two indicated the presence of inversion heterozygosity. In addition to these, meiosis was also characterized by other different abnormalities.
The C-bands of Lathyrus sphaericus are present in the centromeric region of all the 14 chromosomes and the satellited region of the nucleolar pair. Orientation of interphase chromosomes is non-random and late anaphase arrangement of chromosomes is maintained up to next late prophase through interphase. At interphase, centromeric regions form a ring-like arrangement towards one pole and chromosomes remain polarised. The chromosomes may be present singly or 2-3 centro-meres may associate to form 5-7 centromeric masses. Regularity of spatial relationshipof chromosomes throughout the division cycle is indicated. Non-random arrangement of interphase chromosomes and organization of a structure like centromeric ring for maintaining the spatial relationship have been demonstrated.
Bleomycin at concentrations from 0, 1, 1 to 10μg/ml causes the following aberrations: gaps, breaks, stretchings, occurrence of acentric, dicentric, tricentric chromosomes. After ulrastructural level, abnormalities and despiralisation of the chromosome fiber are noted.
1. Vorliegende Untersuchungen zeigen, daß der Extrakt von Allium sativum mitosehemmend wirkt. Die native Substanz führt innerhaib von 24 Stunden zur Degeneration der Teilungsfiguren in Wurzelspitzen-Mitosen von Allium cepa var. ascalonicum mit anschließender Karyolyse. Diese Wirkung, die noch bei einer Verdünnung von 0.1% erzielt wird, beruht auf einer induzierten Pyknose (sticky-Effekt). 2. Im Vergleich zur Colchicin-Wirkung sind wesentliche Unterschiede feststellbar. So kommt es nicht zur typische Spindelblockade mit ihren speziellen Folgen. Die Spiralisierung der Chromosomen wird nur wenig beeinfluißt. In der Metaphase sind die Strukturen verklebt und verklumpt, bei Colchicin-Einwirkung hingegen zerstreut. Die Anaphase ist weitgehend unterbunden oder tritt mit zahlreichen Brücken auf.
Asynaptische Pflanzen von Allium cepa erwiesen sich als ein günstiges Ausgangsmaterial für die Erzeugung aneuploider Nachkommen. Im einzelnen wurden folgende Ergebnisse erzielt: 1. Der Samenansatz der asynaptischen Pflanzen kommt ausschließlich durch Bestäubung mit genetisch normalen Pollenkernen zustande. Die Samenproduktion ist sehr gering; sie lag bei etwa 5.10-3. Um eine trisome Pflanze zu erhalten, waren im Durchschnitt 6 asynaptische Mutterpflanzen erforderlich. 2. Ein Drittel alter Nachkommen der asynaptischen Mutterpflanzen sind Aneuploide. 3. Fast 50% der Aneuploiden sind entweder Trisome oder “triploide Trisome”, die aus der Anaphasen-Verteilung von 9:7 stammen. 4. Befruchtungschancen haben nur diejenigen as-Eizellen, die aus Verteilungen von 8:8, 9:7, seltener 10:6 oder 11:5 stammen. 5. Es wurden keine hypodiploiden Nachkommen mit weniger als 2n=16 gefunden. 6. Die Entstehung aneuploider Pflanzen mit einer größeren Zahl überzähliger Chromosomen ließ sich in Verbindung mit der Bildung von Restitutionskernen erklären. 7. Die zytologische Indentifizierung der überzähligen Chromosomen ist am einfachsten in MI/AI oder in der Metaphase der Pollenmitose.
New chromosome numbers and detailed cytology for seven weeds (Scrophulariaceae) from Bihar are reported here. First counts are reported for five species belonging to five different genera Centranthera tranquobarica n=15, Dopatrium junceum n=14, Limnophila indica n=16, Lindernia viscosa n=10 and Suterad issecta n=12 and new numbers are also reported for two species of one genus Lindernia i.e. Lindernia crustacea n=14 and Lindernia multiflora n=7. Meiosis in general was non-synchronized. And anomalies like univalent and multivalent formation, secondary association of chromosomes etc, have been observed in some pollen mother cells (PMCs) at metaphase 1. In most of the weeds pollen grains were found to be of variable size.
Two singly trisomics (2n=19) and one doubly trisomic (2n=20) were obtained in the open pollinated progeny of the colchicine induced hypertriploid (2n=30) of Chrysanthemum coronarium. Open pollinated progeny of one singly trisomic consisted of diploids only whereas the frequency of trisomics was rather low (12%) in the progeny of other trisomics. Trisomy is found to have no morphological effect. In about 50% of the PMCs, the extra chromosome constitutes a trivalent. In one singly trisomic, interchanges also involve the triple chromosome leading to the formation of multiple association of five and seven chromosomes.
Autotetraploidy was induced in the genus Capsicum annuum L., an economically important spice crop of considerable local importance. A few plants produced wrinkled fruits in the first generation with very few seeds in them and turned out to be desynaptic autotetraploid plants after cytological analysis. Pollen mother cells of the desynaptic autotetraploid showed either all or an overwhelming number of univalents. The bivalents included rod type and ring bivalents were very infrequent. The total absence of tri- and tetravalents was noteworthy. Failure of pairing between homologous chromosomes at prophase and metaphase I has been ascribed to desynaptic condition. Laggards were frequent and often formed small, supernumerary nuclei.
The effects of the aqueous extract of a popular variety zarda (processed tobacco used in betel) on the root meristems of Allium cepa Linn. were studied. While the higher concentrations (1.5% and 1%) of the extract were highly mitostatic, lower concentrations (0.75%, 0.5% and 0.25%) produced various types of chromosomal damage. The most conspicuous features were the stretching and fracture in the centromeric regions which became evident at metaphase. Various other abnormalities like clumped metaphases and anaphases, bridge connections at anaphase and pulverization of chromosomes leading to nuclear disintegration were also met with.
Cytological effects of solar eclipse (S⋅E⋅) of February 16, 1980, were investigated in root meristems of Allium cepa, A. sativum, Hordeum vulgate and Pisum sativum. The eclipse induced clastogeny mainly in the form of chromosome breakages, fragments at ana-telophase and fragmented nuclei. Other chromosomal aberrations included stickinesss, bridges, lagging chromosomes, lagging fragments, groupings, chromosome condensation and binucleate cells. Besides, S·E· also altered mitotic indices in all the test systems. With increase in the duration of recovery times a decrease in the frequency of aberrant cells was noticed. In combination treatments with cysteine, however, there was a sharp decline in the frequency of chromosomal anomalies and increase in the mitotic indices. Possible genetic implications of these results are discussed.
The duration of various stages of meiosis and spermiogenesis in the cat was estimated autoradiographically by using H3-thymidine. Leptotene and pachytene last for about 4, 00 and 15.50 days respectively. Zygotene is of shorter duration and is completed within 12 hours. The individual duration of stages from diplotene to metaphase-II is also extremely short and all these events succeed one another within 18 hours. Spermiogenesis lasts for at least 20.50 days. The total duration of meiosis and spermiogenesis never exceeds 41.25 days.
Cytogenetic effects of a fungicide, ediphenphos have been studied on the bone marrow chromosomes of mice in vivo. Dose, route and duration of exposure largely influence the aberration frequency. The chemical has been found to be mutagenic in the present test system.
A 16mm cinematographical analysis was made on the early process of culmination of Dictyostelium discoideum. The present study revealed that the stalk, formed at the top of cell mass, elongated down to the base. The head of the cell mass would then start an upward motion as soon as the tip of the stalk reached into the presumptive disk cells. The stalk pushed downward remarkably fast and it took only ten minutes for the tip of the stalk to reach the base. A combination of the pushing down of the wedge-like stalk and the motion of the sheath as if squeezing seemed to raise the cell mass. The disk was formed also by an downward motion of the sheath. The stalk becomes fixed, and a stable disk covered with the sheath was thus completed by this formative movement.
Spermiogenesis in Blattella germanica was examined by electron microscopy with conventional fixation methods and PTA-staining. Spermiogenesis was studied morphologically over the peroid of replacement of nuclear basic protein of somatic histone by sperm-specific arginine-rich protein. Before this time, 30nm chromatin fibers uncoil forming 10nm chromatin filaments. After the replacement, the chromatin recoils into 30nm chromatin fibers. The recoiled chromatin fibers are straight, unlike those before replacement of basic protein which are wavy. This difference in appearance may be due to the replacement of nuclear basic protein of somatic histone by arginine-rich protein or protamine, and differences in localization of these basic proteins in chromatin fibers.
In genetic studies on Anopheles minimus cytogenetic observations and hybridization tests were performed on 3 strains belonging to Anopheles minimus and their hybrids, in order to know cytotaxonomic informations and phylogenetic relationships among geographical populations of the species due to their morphological varieties. The results were revealed their homosequencial cytomorphology, especially in their banding sequencies of polytene chromosomes of both salivary glands and ovarian nurce cells. No naturally occurring polymorphism was described from the observations of each 50 slides of the 3 strains, one from Ishigaki Island, Japan other 2 from Kanchanaburi, Thailand; relating to them morphological varieties were also qualified among them. Complete synaptic salivary gland polytene chromosomes were observed among their F1 hybrids from 3 combinations of crosses among the strains. These chromosomal informations gave standarized polytene chromosome map and its description was made. Hybridization experiment among the 3 strains revealed some grades of postcoupuratory reproductive isolation-phenomenon between ISG strain and KCH-1 strain whereas not between ISG and KCH-2 one. The one was inviability of the F1 hybrid from reciprocal crosses between ISG and KCH-1.
When the spore of Equisetum arvense is immersed in 0.1 M KOH solution, the cytoplasm is colored yellow, and the colored matter is naturally extracted into the medium. After germination, the same coloration with KOH takes place in the basal cell of protonema but not in the apical cell. The colorecd matter was taken out from the spore with aceton followed by methanol and ether, then it was analyzed by paper-chromatography and by column-chromatography. The analyzed components were separately examined by use of UV absoption and IR absorption spectometries. As a result, the colored matter was identified to be consisting of gossypitrin and herbacitrin. Role of these two substances in the cell of Equisetum is not clear, while presumed to take part in regulation of morphogenesis.