The paper describes in detail the course of meiosis in the cytoplasmic pollen sterile plants C. annuum L. The occurrence of meiotic irregularities which are one of the causes of the pollen abortion was studied in the pollen sterile mother and in three hybrid combinations with non restors of the sterility. The course of the irregular meiosis is determined by the nuclear factors ms susceptible to the hereditary constitution of plasmon.
The chromosome behavior during spermatogenesis of the goat, Capra hircus Linn., has been reinvestigated following hypotonic Earle's treatment technique. The regular process of meiosis in this species has already been reported by Makino (1943) following squash technique, with very little information about chiasmata during division. In this study, a detail account of chiasma formation in each and every autosomal bivalent at diplotene stage and their movement towards terminalisation in different stages of first meiosis have been represented with the remark of average number of chiasmata per cell and per bivalent. Also, this observation differs from previous author, who noticed a spindle fibre attachment between the X and Y during first meiotic division, whereas it has been found here the distinct formation of a chiasma between the X and Y and the homologous part is the minute short arm of X and one of the arms of small metacentric Y.
The diploid chromosome number of Nala lividipes is 40 with an XY sex-mechanism, the highest number thus far reported in Dermaptera. Meiosis is orthodox and typically dermapteran. The X and Y chromosomes are derived from a single positively heteropycnotic body found in the interphase of the primary spermatocyte. First division is reductional and the second division is equational for sex chromosomes. Evolution of chromosome number and the sex mechanism in the dermaptera are discussed.
Observations are presented on the cytology of chlamydospore germination and sporogenesis in Protomyces macrosporus Unger. A resting chlamydospore contains 50 or more diploid nuclei. The chlamydospore on germination produces a thinwalled vesicle and the nuclei become arranged along the periphery of the vesicle. Meiotic division of these nuclei results in the formation of quartets. Radial septation takes place enclosing a nucleus in each cell, which develops into a uninucleate haploid spore. Two chromosomes appear to be the haploid number (n=2) in the complerhent of the species. Taxonomic aspects of the genus Protomyces in the fam. Protomycetaceae are discussed in light of these observations.
The ultrastructure of nuclear membrane and cytoplasmic lamellae have been studied at meiotic prophase in the microsporocytes of Lilium in vivo and in vitro in presence and absence of mitomycin C. Meiocytes were fixed in glutaraldehyde and OsO4 and sections were stained in uranyl acetate and lead citrate. The nuclear pores have been found to be octagonal in shape with eight microcylinders. The pore complexes are probably detached from the nuclear wall during the breakdown of the latter. At diffused stage in the mitomycin treated meiocytes triple layered unit membranes have been seen to form cytoplasmic lamellae. Two structural components, small dense granules and exceedingly thin filaments, have been seen always to be associated with these lamellae. These lamellae stain basophilic. They later arrange into stacks and change over to tubular ellipsoid forms. Sometimes these threelayered unit membranes have been seen to dissociate from chromatin at the time of the breakdown of the nuclear wall. The significance of the formation of these cytoplasmic lamellae has been discussed. The author thanks Prof. J. Straub, Dr. I. Anton-Lamprecht for their interest in this study and to Mrs. S. Sen, Miss B. Meyer and Mr. D. Bock for help. Financial grants from Alexander von Humboldt Stiftung and MaxPlanck-Gesellschaft are acknowledged gratefully.
Teliospore germination, cytology and development of Entyloma eleocharidis Pavgi and Singh parasitic on Eleocharis plantaginea R. Br. have been described. The diploid nucleus migrates in the promycelium during teliospore germination and divides. The first division being reductional, is followed by an equational one. Some of the meiotic divisional stages havee been described and the haploid chromosome complement (n=5) determined. Several aberrations in the teliospore germination and nuclear behaviour are observed and their repercussions discussed. Sporidial development, conjugation. and subsequent development of parasitic mycelium and teliospores in the host indicate that E. eleocharidis possesses a diplobiontic and haplo-diplobiontic life cycle pattern. Possible consequences of the ecological factors influencing the life cycle of the pathogen are indicated.
A synthetic bread wheat (T. durum cv. Carleton×Aegilops squarrosa) was crossed with T. durum cv. Carleton, the pentaploid F1 (AABBD; 2n=35) being backcrossed to Carleton. Among the backcross progeny, eight haplosomic (2n=29) groups were identified. Although it was not possible to relate each to a D genome chromosome, four were established as markers of individual chromosomes. One character, brown chaff, appeared to be determined by complementary genes on two chromosomes. The same characters could be identified among the aneuploids with more than 29 chromosomes and related to particular chromosomes by the isolation of the respective haplosomics.
A comparative and comprehensive report is given on the distribution of chromaffin and nonchromaffin cells in the lower vertebrates by means of iodate and chromaffin tests. Whatever be the distribution of these two types of cells, there is a gradual tendency for a close proximity between adrenaline cells from the chromaffin tissue and the nonchromaffin cells. This seems to support the claim that the nonchromaffin cells provide glucocorticoids to the adrenaline synthesizing mechanism in adrenaline cells. The increase and decrease respectively in adrenaline and noradrenaline from fishes to mammals is supported by the corresponding increase and decrease in adrenaline and noradrenaline cells. The possible evolutionary implications of these findings are discussed.
The effect of colchicine, mercaptoethanol, and nitrogen mustards on the pollen mother cells of Lilium have been studied at the electron microscopic and the light microscopic levels. The treatment of PMCs with colchicine induced the inhibition of the spindle activity, which was caused by the dissociation of chromosomal fibers. The colchicine-treated chromosomal fibers showed a number of granules corresponding to the precursors of elemental fine fibrils of the fiber. Therefore, no chromosomal fibers remain to induce the chromosome movement at anaphase. The inhibition of spindle activity induced by mercaptoethanol was similar to that by colchicine, but the ultrastructural changes of chromosomal fibers caused by the former were different from those by the latter. The chromosomal fibers treated with mercaptoethanol became sticky and could not act normally. Cytological effects of alkylating agent, nitrogen mustard, were lethal inducing chromosome breakage, stickiness in nuclei, and extreme alveolation of the cytoplasm. The authors would like to thank Professor Emeritus B. Wada and Professor N. Tanaka, University of Tokyo, for their helpful criticism of the manuscript. This work was supported by the grant from the Ministry of Education of Japan.
This constitutes a report on the occurrence of spermatization in Cyclotheca kamatii Visw. and Ananth. (Mycrothyriaceae) of a unique type not so far reported in literature except a recent report by Tilak in Phyllachora actinodaphnes. The mechanism involved is distinct from the previously reported phenomenon releasing the spermatia through the adjoining ascocarp initial through a basal canal and bringing about the diploidisation of the ascogonial cells. The entire process is thus brought about within the host unlike the normal process so far reported and compares very well with the one reported by Tilak in Phyllachora actinodaphnes. The type of sexuality may be described as hermaphroditic in view of the occurrence of the two compatible gametangia within the same stroma. The writer is grateful to Prof. M. N. Kamat for his kind interest and guidance and to the Secretary, C. S. I. R., New Delhi, for award of a Research Fellowship.
The caryotype of H. bicolor and H. igneum coincides in number and morphology (2n=16); satellites are born by submetacentric chromosomes at the fourth couple. In some cells of H. bicolor small satellites were found at the second couple, as heterozygotic character.
The authors report the sex chromatin analysis carried out in the opossum Didelphis paraguayensis Oken 1816. Animals of both sexes possess distinct chromocenters or sexual vesicles in interphase nuclei and even an heteropycnotic chromosome during prophase. These findings are more evident in females than in males, which is interpreted on the basis of size differences of sex chromosomes between both sexes. It is concluded that for Didelphis paraguayensis the sex chromatin is formed by a condensed X chromosome in females, and for an allocyclic part or even the whole Y chromosome in the males. The different frequencies of Barr bodies and drumsticks between males and females are significant, after various statistical tests, which allows their use to achieve the diagnosis between sexes.
In Pennisetum typhoides the B-chromosomes are smaller than the smallest A-chromosomes of the set and usualty lie at the periphery of the metaphase plate at mitosis. There is variation in the number of B's in the cells of the same root tip as also in the pollen mother cells of the same anther, flower and inflorescence. At pachytene the centromere was observed to be subterminal, the entire short arm is heterochromatic and the long arm has a short proximal heterochromatic region followed by light staining euchromatic region with eight chromomeres distributed along its whole length. B's regularly pair among themselves and when present in numbers of 3 or 4 form multivalents at diakinesis and metaphase I. They exhibit non-disjunction and precocious division at anaphase I, in the pollen mother cells. The differences between the B's present in this material and the accessories reported by Powell and Burton (1966) have been discussed.
1. Using specific stain techniques, almost negative reaction for glycogen and positive reactions for acid and alkaline phosphatases, PAS-reactive substances, basophilic substances, cystine, arginine, mucoprotein, bound lipids and zinc are observed in the hypothalamo-neurohypophysial system of the lizard Calotes versicolor. 2. The PAS-reactive substances are probably mucoprotein-lipoprotein complex. 3. The significance of the positive reaction for arginine and zinc in the neurosecretory system is discussed in the light of current finding on their relationships with the neurosecretory substances.
The karyotypes in Agra (North India) and Quilon (South India) populations of Xenochrophis piscator are 8 VS+2 rods+28 dots and 10 VS+6 rods+20 dots, respectively. There are less important differences in mitotic and meiotic details too. A hypothetical mechanism has been envisaged whereby, such changed karyotypes with distinct polymorphism arose. It is felt that within Agra karyotype of Xenochrophis certain structural changes took place either because of advantageous mutation or cumulative effect of countless generations, subsequent fusions led to the evolution of Quilon karyotype. Analysis of variance of chiasma frequency in both the populations reveals that inspite of chromosomal repatterning recombination index has not been altered much. The revision of systematics data in this species seems necessary.
Mitochondria of the two species of Allomyces, viz., A. javanicus, and A. moniliformis were investigated. Various forms of mitochondria were present in varying proportions. In isotonic solutions of NaCl, the mitochondria disintegrated into granules, but in hypertonic saline solution cells were plasmolysed at first but recovered later on. Mitochondria in such cells changed their shape, fragmented, became vesiculated and disappeared. In 0.5M sucrose solution, they quickly fragmented into small spheres, averaging 1 micron in diameter. Temperature of 10°±1° to 45°C had seemingly no effect on mitochondria. At higher temperatures, viz., 50°C, the mitochondrial movement ceased and at 75°C they broke up into beads and disappeared. Mitochondrial orientation was determined by the direction of cytoplasmic streaming. Small granules as normal mitochondria were stained red after 48 to 72 hours with tetrazolium chloride of 0.005 per cent concentration. Higher concentrations were lethal. Mitochondria were stained supravitally with Janus green B Hoechst as sky blue colour and reduction of the dye was observed after sometime. Amongst all the fixatives tested, Regaud's formol-bichromate was found to be the most successful.