Four types of yolk bodies develop during the oogenesis of Chrysocoris stollii: 1. Yolks, which originate from the Golgi bodies and are of fatty (triglycerides) nature. 2. Yolks, which originate from the nucleolar extrusions and are of carbohydrate-protein-RNA nature. 3. Yolks, which originate from the mitochondria and are of phospholipid-protein-RNA nature. 4. Yolks, which originate from the yolk precursors in the follicular epithelium and are of acid mucopolysaccharide-protein-RNA nature. The involvement of different ooplasmic organelles and follicular epithelium in the synthesis of these yolks has been discussed.
The effects of 2, 4, 5-tichlorophenol, 2, 4, 5-T, 2, 4-D, and 2, 4-dichlorophenol were studied on the meiosis, pollen viability and yield of Vicia faba plants. Two types of treatments were conducted: spray, and seed-soak-treatments. Plants were sprayed at two developmental stages when they were 15, and 35 days old. Spraying plants when they were 35 days old with the experimental agents effected a relatively higher percentage of abnormal PMCs than that induced when the plants were 15 days old. Soaking of seeds in the experimental agents before planting resulted in the lowest percentage of abnormal PMCs in comparison with the spray treatments. The most dominent types of abnormalities were: stickiness, lagging chromosomes, and chromosome fragmentation. Spraying plants when they were 35 days old with 2, 4, 5-T was the only treatment which effected a significant percentage of sterile pollen grains. Spraying plants when they were 15 days old was found to be the most effective treatment, where nearly all the used chemicals showed a significant effect either in the 1st or in the 2nd generation. All the used agents had no harmful effect on the yield, and their effect diminished in the 3rd generation.
An interspecific hybridisation between the two species S. indicum L. and S. melongena L. was attempted, and the occurrence of hybrid sterility was analysed based upon the cytological, morphological and genetical behaviour of F1, amphidiploid, F2 and back cross progenies. The hybrid sterility might be due to the nonsynchronisation of chromosomes at metaphase plate and controlled by genic factors. The non-reduction in chiasma frequency in the hybrid and the occurrence of free recombination in the hybrid derivatives precludes the possibilities of segmental difference between the parental chromosomes. The resulting amphidiploid of the hybrid (S. indicum L.×SM.34) did not restore fertility and this forms a very concrete proof in supporting the genic cause for the hybrid sterility. The occurrence of petaloid anthers in some of the male sterile segregants in the F2 and melongena backcross progenies also revealed that it was due to diplontic sterility. The fertility levels of F2 and back cross progenies ranged from 0-89 per cent with a continuous variation indicating the sterility must be governed by major genes withmo difiers involved. There are indications which revealed that the male and ovule sterility in this species cross must be governed by different independent non allelic genes or gene complexes.
Dry and presoaked seesd (6 and 12 hr) of Lens esculenta were irradiated with 1, 5, 10 and 15 kR X-rays and the effects of radiation were measured from the yield of induced chromosome aberrations observed in roots. The yield of X-ray induced aberrations increased linearly with the exposure. When seeds were presoaked before irradiation there was a remarkable increase in the yield of total aberrations still increasing at the longer presoaking time. Treatments of dry and 6 hr presoaked seeds with HA (0.1%/2 hr) resulted in chromosome breakage not restricted to the heterochromatic regions and influenced by the pH. Post-treatments of 1 and 5 kR X-irradiated seeds (presoaked) with HA (0.1%/2 hr) showed that the yield of aberrations in combined treatment was more than additive, the synergistic effect was depending on the dose of X-rays.
The histochemical constitution of pollen, pollen tubes and pistillar tissues of Triticum durum Desf. before, during and after pollination was studied in vivo. The polysaccharides, RNA, proteins, lipids and reducing sugars were determined. At all phases of development, stigmatic branches have very low concentrations of polysaccharides, reducing sugars and rich RNA and nuclear proteins. Lipids increase during pollination and decrease later during pollen tube growth. The germinating pollen grains have high concentrations of polysaccharides, RNA, proteins and lipids. However, these are decreased when the pollen tubes have grown to a considerable length. The pollen tubes in stigma and style contain high concentrations of polysaccharides, lipids, RNA and proteins, but reducing sugars were absent. It is inferred that these macromolecular substances play an essential role in bringing about the growth of pollen tube in the stigma and style in vivo.
The diploid number of chromosomes in Gonoplectus malayus and Phyllogonostreptus nigrolabiatus (Diplopoda: Myriapoda) is 15 and 24, respectively, with male heterogamety. Whereas the former shows XO-, the latter reveals XXO-type of sexdetermining mechanism. During meiosis, the sex-chromosome(s), move synchronously in Gonoplectus malayus and asynchronously in Phyllogonostreptus nigrolabiatus. The first meiotic division is reductional both for the autosomes and sex-chromosome (s). Deviations in the diploid and haploid number of chromosomes have been observed in both the species.
The present work deals with a study of cytological races in S. spontaneum L. from the plains of North-western India. Six cytotypes, C1, C2, C3, C4, C5, C6, have so far been identified with haploid chromosome numbers n=20, 21, 22, 27, 28 and 36 respectively. The cytotypes with n=21 and n=22 chromosomes are new reports. Chromosome mosaicism, desynapsis, non-congression of a few bivalents at the equatorial plate, multipolar spindle formation, lagging of univalents, bivalents, and anaphasic bridges are amongst the meiotic abnormalities observed. Karyotypes are described in three cytotypes, namely, C4 with 2n=40, C6 with 2n=54 and C1 with 2n=72+4f. It is concluded that intraspecific variations are due to both numerical and structural chromosomal alterations.
Two sorghum inbreds (Combine Kafir 60 and Combine 7078) and their F1 and F2 progenies were treated with atrazine, as a preemergence herbicide, at 3, 6, and 9lb/A (3.3, 6.6, and 10.0 kg/ha). Low frequencies of meiotic aberrations occurred in all treated populations; no aberrations were observed in control populations. Frequency of total aberrations seemed higher in the F1 than in the F2 or parental lines; irregularities seemed more frequent in Combine 7078 than in Combine Kafir 60. More common aberrations were aneuploidy, polyploidy, metaphase I univalents, and multinucleate cells; anaphase I bridges and telophase I laggards were less frequent. Significance of these findings is not clear. A primary cause for concern is that irregularities of the kind observed may enhance development of offtypes and thereby create problems of genetic instability in lines or cultivars. The possibility that atrazine has similar effects on weeds also is worrisome. On the other hand, observed abnormalities were rare and have not been shown to result in viable offtypes or to be associated with reduced genetic stability in treated populations. Results should not be interpreted as militating against the use of atrazine or similar herbicides but as indicating a need for further investigation of the effects of such chemicals on the reproductive mechanisms and genetic stability of plant populations.
Root tips of Allum cepa were treated with solutions containing 1000, 100, 10, 1 and 0, 1μg/ml of the mycotoxins patulin, rubratoxin B and diacetoxyscirpenol. The most striking damage was reduction of the mitotic index and metaphase arrest by all toxins and chromosomal aberrations, appearance of nuclei with two nucleoli as well as vacuolization of the cytoplasm under the influence especially of diacetoxyscirpenol which proved to be the most active toxin.
Occasional nuclei of inner onion epidermis cells were found to contain a structure which we believe to be an intranuclear vacuole. These structures appeared circular, homogenous, hyaline, sharply outlined and averaged approximately 35% of the thickness of the nucleus (assuming spherical form) but decreased the dry mass concentration through their part of the nucleus by approximately 56%. We conclude that these are elongate along the axis of the light path.
Chromosome aberrations induced by the treatment of gallic acid, in the root-tip cells of Vicia faba, have been investigated under the scanning electron microscopy. Specific effects were chromosome break and reunion. The type of effects was different from its derivatives such as ethyl gallate and n-propyl gallate, which induced binucleate cells. These different effects of chemicals seem to be related to the difference of constitutional formulas among these compounds. In the drawn out chromosome bridge induced by gallic acid, the ultrastructure of chromosome and its internal coiled structure can seen as spiral structure. The elementary fibrillar structure of chromosome is 300-500Å in width.
The karyotype and electrophoretic pattern of serum transferrin were examined in 18 black rats (Rattus rattus) from Kandy, Sri Lank (Ceylon). Ten rats (5_??_ and 5_??_) were karyotyped based on air drying from bone marrow cells and the consistent count of 2n=40 was obtained. The somatic complement contained one outstandingly large metacentric pair. The metacentric pair seemed to have resulted from the Robertsonian fusion of acrocentric pairs No. 11 and 12 which were present in the Asian type black rat. Four kinds of transferrin band, Tf-C1, Tf-C, Tf-D and Tf-E were demonstrated. There was detected no Asian type transferrin (Tf-R and Tf-N) in all rats examined. Evidence presented strongly suggests that the Ceylon black rat is not originated from the hybrid between the Asian (2n=42) and Oceanian type (2n=38), but is evolutionally transient type from the Asian type to the Oceanian.
The transfer cells in the minor veins of pea leaf develop papillate-type wall ingrowths, which appear to be polarized in the xylem transfer cells. The cytological features include: high density of ribosomes and rough endoplasmic reticulum, moderately developed chloroplasts, dictyosomes, large number of mitochondria, and microtubules in the proximity of plasmalemma. These features are discussed in relation to transfer cell function.
Localization of polysaccharides and phosphatases was studied by ultracytochemical methods during development of the Golgi apparatus in Tradescantia pollen. It was found that polysaccharides were present throughout the developmental processes of the organelle. In the early stage when the organelle is growing, the organelle contained a little amount of polysaccharides. Although reaction products for TPPase were found at the early stage, IDPase activity could not be detected in the organelle. In the later stage when the organelle produces secretory vesicles, the organelle accumulated a large amount of polysaccharides. Intense IDPase activity appeared in the organelle, but TPPase activity could no longer be detected.
In the cytogenetic type ABB of Scilla scilloides trivalents were observed, deviating from the standard pairing 9II+8I. Heteromorphic trivalents involving a large V-shaped chromosome which is characteristic of genome A and is lacking in genome B proved the intergenomic pairing. Similar homoeologous kinships between the genomes A (x=8) and B (x=9) were manifested in AAB and ABBB.
1. Among eight plants of Lilium japonicum sampled from a natural habitat, seven were normal, with 12II+0-4B's: mean number of small telocentric B-chromosomes was 1.86 per plant. Homologous two B's paired frequently with each other but not with ordinary chromosomes. From 1 to 7 chiasmata were formed at random with mean frequency of 3.44 per bivalent at MI. No remarkable difference between the plants with and without B's was found. Spontaneous aberrations such as altered bivalent with chromosome breakage and sister reunion, bridge and fragment, loop and fragment, bridge, acentric fragment, and trisomics were recorded with low frequency at MI and AI. 2. The remaining one plant was heterozygote for translocation, 1IV+10II, which is characterized by absence of ring-of-four multiple. The constant formation of 1 to 2 chiasmata was observed on both interstitital segments between kinetochore and break-point, the mean frequencies being 1.48 and 1.32 respectively for the segments. The relatively high frequency of interstitial chiasma should cause a reduction of fertility which makes the heterozygote disadvantageous for selection.
A number of diploid and polyploid species of wheat have been subjected to the condition of high temperature. The various temperature treatments have been found to induced formation of univalents in a number of Pollen mother cells of different varieties. The distribution of cells showing such univalents has been studied. It has been found that in almost all the plants, the distribution is of a poisson type. The significance of this type of distribution has been discussed.
Cytological and morphogenetical studies were conducted on the tissues obtained in vitro, from the mature embryo and endosperm of three mistletoes: Dendrophthoe falcata, Taxillus cuneatus and T. vestitus (Loranthaceae). Differentiation of shoot buds and haustoria was observed during repeated subcultures of the embryo and endosperm tissues (on a similar medium). Cytological preparations of the embryonal and endosperm callus, and organs differntiated therefrom, showed the diploid (2n=18) and triploid number (3n=27) of chromosomes, respectively. A cytological study of D. falcata (in vivo) indicated regular meiosis (n=9) during microsporogenesis. The developing embryo, endosperm, and fruit wall tissues exhibited constant chromosome numbers: 18, 27 and 18, respectively. The morphology as well as anatomy of diploid and triploid organs, differentiated in vitro, was more or less comparable.
The pentaploid hybrid, abbreviated N-5x (5x=2n=35, genome formula AABBD), between a natural common wheat, Triticum spelta var. duhamelianum (6x=2n=42, AABBDD) and an emmer wheat, T. durum var. melanopus (4x=2n=28, AABB) transmitted 2.64 D-chromosomes (chromosome belonging to the D genome) per fertilized female gamete. However, the pentaploid hybrid (S-5x) between a synthetic common wheat (amphiploid between T. durum cv. Golden Ball and Aegilops squarrosa; 6x=2n=42, AABBDD) and the same emmer wheat transmitted 1.23 D-chromosomes per fertilized female gamete. Both transmission rates were significantly lower than the theoretically expected rate (3.5 chromosomes/gamete). Cytological events occurring in meiosis in PMCs were investigated in detail in both pentaploid hybrids. In N-5x, 7.6 univalents per PMC were found at MI per PMC, and 67% of them formed lagging chromosomes at At (10.2/PMC). Most of these lagging chromosomes reappeared as laggards at All (9.76/tetrad), and about 40% of them eventually formed micronuclei at TII (3.95/tetrad). Only 6.1% of the laggards at At formed micronuclei at TI. Elimination of univalents from the nucleus, first as laggards and finally as micronuclei, fully explains the transmission rate of D-chromosomes in N-5x. In S-5x, however, 8.3 univalents per PMC were found at MI, and 46.4% of them formed laggards at At (7.7/PMC). Again, most appeared as laggards at All (6.82/tetrad), and about 38% of them formed micronuclei at TII (2.58/tetrad). The portion of At laggards forming micronuclei at TI was only 8.2%. In this pentaploid, univalent elimination should result in the transmission of 2.85 D-chromosomes/gametes. Reduction of the D-chromosome number by univalent elimination explains only 30% of the actual observed reduction. In S-5x, preferential fertilization of 14 and 15-chromosome gametes seems to play a more important role than does univalent elimination in determining the transmission rate of D-chromosomes. Finally, the segregation of transmission patterns of univalents (N-5x type vs S-5x type) was studied with four pentaploid hybrids recovered in the Bl generation, N-5x F1×emmer parent. Each of two B1 plants showed an N and S-5x type transmission pattern, while the remaining two were intermediate to the two F1 types. Since both parental types were recovered in a small B1 population, the transmission pattern of univalents seems to be controlled by major genes. However, they must number two or more, because the intermediate type also appeared in the B1 generation. The origin and evolutionary role of the genes controlling a high transmission rate of univalents were discussed.
Although it has been known that crossing-over does not take place in the male of Drosophila species, D. ananassae is a notable exception in which spontaneous crossing-over occurs in the male. The results of a study of crossing-over in the males of a Tonga strain (T15-4) of D. ananassae are described. Whether the synaptonemal complex is formed in pro-spermatocytes from testes of the T15-4 strain was examined by electron microscopy. The synaptonemal complex with typical tripartite structure which was seen in pro-oocytes could not be found. However, in leptotene and early zygotene cells, the axial filament which makes up the center of each chromosome was clearly observed. Furthermore, in zygotene cells, homologous chromosomes formed incomplete synapses with the aid of an imperfectly developed synaptonemal complex. It is considered, therefore, that male crossingover takes place between these imperfectly synapsed homologues, although its frequency is much lower than that seen in females.
Two agonadal intersex rabbits were studied cytogenetically. The Quinacrine fluorescence and Giemsa banding patterns of normal male rabbit mitotic chromp somes are described for the first time and compared with the propositi. Characteristic banding patterns which showed similarity in both techniques allowed homologous chromosomes to be identified with ease. The X and Y chromosomes fluoresced with Quinacrine mustard and stained with Giemsa like the cow and human X and Y. Inadequate functioning of male gonads at the appropriate time of differentiation of the accessory male structures coupled with inhibition of Mullerian derivatives must be postulated. The cause of this in the face of a normal chromosome constitution is not known, nor can it be derived from these two cases.