Cytological informations of the family Meliaceae suggest 9, 10, 11, 12, 13 and 14 as basic numbers. Numbers have evolved from lower to higher. In Melieae 14 is the basic number. In old Trichilieae the numbers are 9-14, which show different ploidy levels, including aneuploids. Carapa and Xylocarpus are similar in karyology and should be placed as Carapeae near Swietenieae, not with Melieae or Trichilieae. Cedreleae show a wide range of variation 12×2 to 14×4 and a highly advanced chromosome morphology. Calodecaryia (some species), Azadirachta, Dysoxylum, Aphanamixis, Aglaia, Amoora, Sandoricum are primitive and Naregamia, Nymania, Calodecaryla (some species), Lansium, Carapa, Xylocarpus, Capuronianthus, Swietenia, Cedrela and Toona are advanced.
Chromosomes involved in three translocation lines in a 6-rowed barley variety K 12 were identified by studying the meiosis in the hybrids between the translocation lines and Burnham's translocation testers. The chromosomes identified were 1-4 (line 3047), 1-3 (line 3103) and 4-7 (line 3104).
Changes in nuclear dry mass (NDM), nuclear area (NA), and nuclear structure in outer epidermal cells of white onion were determined at 15-min intervals during 45 min in distilled water. Three pretreatments of onion leaf bases were used: no exposure, exposure to ambient atmosphere for 24 hr, and exposure for 48 hr. Non-exposed epidermal cells mounted in distilled water lost NDM during the first 15 min, but NDM in cells of leaf bases exposed for 24 and 48 hr remained unchanged. With all three treatments, NA decreased significantly during 45 min; moreover, the nuclear outline underwent striking changes involving the formation of perinuclear vacuoles and pycnosis. Prior exposure of a leaf base resulted in an increase in the number of perinuclear vacuoles initially and a more rapid disappearance of these vacuoles after 30 and 45 min in distilled water.
Giemsa bands after the urea-treatment technique and the DNA replication patterns by 3H-thymidine autoradiography are compared in the same metaphase cells by the application of two different procedures, with particular reference to the intensity and distribution of the labeling patterns and the Giemsa bands. It was found that chromosome regions bearing dark Giemsa bands showed the late replication. Exceptions to this are the late labeling X-chromosome (XL) in the female cells and areas near the centromeres on chromosome No. 9.
1. Karyological investigation has been made in five taxa of Charophytes, collected from paddy fields, ditches and ponds of Darbhanga (India) 2. n=35 and n=49 in the genus Chara while n=21 in the genus Nitella are new to science 3. n=7 and n=36 are also new chromosome counts for the taxa under investigation 4. n=7 and n=3 appear to be the ancestral basic chromosome numbers for Chara and Nitella respectively. 5. Acetocarmine technique, as devised by Godward (1948), has been employed throughout the course of investigations
This study involves the description and comparison of the ultrastructure of pollen in the cleistogamous and chasmogamous flowers of Viola sp. It shows that the divergences become more important at the end of the ontogeny. In the mature pollen grains of cleistogamous flowers, the starch in the plastids is always abundant and the pulverization of dictyosomes into microvesicles is not very important. At maturity, the pollen grains of chasmogamous flowers show leucoplastids and numerous microvesicles of Golgi apparatus.
The author presents the chromosome numbers and detailed chromosome morphology of 7 species of the genus Solidago (Asteraceae), the majority of which were collected from the Province of Nova Scotia in Eastern Canada. The somatic chromosomes of Solidago are uniformly characterized by small size (range in length: 2.02 to 2.93 microns) and possess predominantly sub-median to median types of centromeres. The karyotype is generally of the asymmetrical type in which chromosome form a graded series without exhibiting a marked break. Meiotic chromosomes show a regular bivalent formation during diakinesis and at other stages and a normal disjunction at anaphase, suggesting a lack of, or a low degree of interbreeding among these and related species of Solidago. The high degree of pollen fertility observed in these species corroborates this statement. It is concluded that owing to its general uniformity, chromosome morphological data is likely to be of greater value in clarifying the taxonomic status of the higher categories of the family Asteraceae than in differentiating related diploid or polyploid species.
The distribution of RNA in the spermatogenic cells of D. virilis was studied by staining with azure B. All the spermatogenic cells with the exception of the spermatozoa were found to be rich in RNA. Most of this RNA was probably associated with ribosomes in the cytoplasm. The nucleolus of the meiotic prophase stages contained RNA and showed changes in its staining intensity, size shape, and location within the nucleus during the growth stage of the primary spermatocytes. These changes were probably associated with the various metabolic activities occurring in the spermatogenic cells. The nucleoli of the spermatids were much smaller than that of the meiotic prophase stages and stained less intensely.
Populations of three Agropyron species and one Agrohordeum species were sampled over a two year period at four native prairie sites of Minnesota and North Dakota. Diakinetic analysis revealed a diploid chromosome number of 28 in all species except A. repens which had a diploid number of 42. The mean chiasma frequencies for A. repens, A. trachycaulum, A. dasystachyum and Agrohordeum macounii were 1.95, 1.93, 1.60 and 0.71. Agropyron repens is an autoallopolyploid where diploidization has been extensive. Agropyron dasystachyum and A. trachycaulum are allotetraploids whereas Agrohordeum macounii is a recent intergenomic hybrid. Structural chromosome aberrations during meiosis were primarily due to those form homology differences. These occurred as lagging and unoriented chromosomes and as micronuclei at various stages. Structural aberrations at various stages were correlated to each other significantly or highly significantly in all but the Agrohordeum species. The fertility levels were influenced negatively at high significant levels in all species with the exception of Agrohordeum by the average meiotic aberration rate. Quartet survival did not display any clear trend on its influence to fertility levels. A stepwise backward multiple regression indicated that the least amount of experimental error occurred in procuring metaphase II and quartet data for aberration rates, and thus they accounted for most variance in fertility.
Mean chiasma frequency at diakinesis has been studied in two inbred lines of radish (Raphanus sativus L. var. radicola Pers), namely LS-337/24 (I12) and LS-337/25 (I12), and their F1, F2 and backcross hybrids. The number of chiasmata per cell was significantly less in the inbred lines (homozygotes) than in their F1, hybrid (heterozygote). F2 hybrid plants, raised from a single plant of F1 hybrid, demonstrated a wide distribution for this character, as would be expected with polygenic control. The value of mean chiasma frequency in F2 hybrid occupied an intermediate position between the lines and the F1 hybrid. Backcross hybrids also showed a marked decline in chiasma frequency when compared to F1, indicating a clear influence of respective inbred lines on this character. It has been concluded that the optimum level of chiasma frequency is a function of heterozygosity of genes and that its distribution is controlled polygenically. The genetic system regulating the formation and distribution of chiasmata in radish has also been discussed.
The present study deals with the effects of X-rays, gamma-rays on the karyology of some selected taxa of charophyta, antheridia having being exposed to radiations. Species of Nitella viz., N. opaca (n=6), N. flagelliformis (n=9) and N. acuminata (n=18) and four of Chara viz., C. fibrosa (n=14), C. globularis var. virgata (n=14), C. setosa (n=28) and C. zeylanica var. diaphora f. oerstidiana (n=42) were employed as experimental materials in various irradiation experiments. X-ray and gamma-ray doses ranged from 100 to 2000 rads. The materials in each case, after exposure to required amount of radiation, were transferred to fresh culture medium and were examined cytologically at varying periods of time. In all experiments controls were maintained. The qualitative changes that were observed in all the taxa with both types of radiations to a greater or lesser extent were: stickiness and of clumping of chromosomes at metaphase and anaphase, chromosome erosion, chromatid gaps, chromosome and chromatid breaks at metaphase and anaphase, anaphase bridges, laggards, unequal grouping of chromosomes, unequal separation, ring chromosomes and rarely, formation of micronuclei. The quantitative estimates of affected cells, based on percentages of those showing chromosome breakage at metaphase and anaphase and cells showing anaphase bridges, showed that levels of radiosensitivity of different taxa differed. The chromosomes of N. opaca having the lowest chromosome number (n=6) and of N. flagelliformis (n=9) with longest chromosomes seem to be more sensitive in comparison to other taxa, while C. zeylanica, with highest chromosome number in the series (n=42) as also with shortest chromosomes, was found to be more radioresistant of all the taxa investigated. However, charophyte taxa in the present study were shown to be more sensitive to radiations as compared with many other algal taxa belonging to other groups investigated earlier. The irradiation studies lend further support to the now more widely held view that Charophyta constitute a very distinctive group amongst algae. The generally held view that algae in general are more resistant to radiations in comparison to higher plants does not seem to apply to the members of Charophyta. On the basis of the present study it has been shown that the chromosomes of N. opaca and N. flagelliformis are as sensitive as to radiations as those of higher plants. The results obtained in the study were adequately discussed.
The experimental materials that were subjected to UV light are antheridium of N. opaca, N. flagelliformis and C. fibrosa, collected from local ponds of Varanasi district. The exposure time of UV ranged from 1 mt to 4 mt (3.06×103ergs/mm2 to 12.24×103ergs/mm2). The cytological effects under each experiment were quantitatively and qualitatively estimated at metaphase and anaphase stages. The qualitative changes were very much similar to those found with X-rays and gamma-rays. A comparative assessment of chromosomal effects on Tradescentia by earlier workers and of those on charophyte taxa recorded in the present study revealed more or less similar radioresponse to UV light.
Irradiation of rhizomes of Nymphaea rubra by 2, 3 and 4 krad of gamma rays induced morphological and cytological changes. The 5 krad and higher doses were found to be lethal. Morphological changes concerning floral and vegetative parts of irradiated plants mostly belonged to the primary effects of radiation and were unstable. However, change from toothed to entire margin of leaf, numerical alterations in petals and stamens, induction of narrower or twisted petals with obtuse tips, changes in the contour of androecium and intensity of colour of petals were stable. Cytological alterations included formation of interchange multiples, fall in chiasma frequency and aberrations of chromosomes in the irradiated plants. Pollen fertility decreases after irradiation, and those treated with 3 and 4 krad became completely sterile.
Three categories of compound yolk bodies are formed during oogenesis of Cybister guaerini. The yolk of the first category originates from precursors at cortical ooplasm and is composed of carbohydrate, protein and RNA. The yolk of the second category originates from mitochondria and is composed of protein and RNA. The yolk of the third category develops de novo and contains protein, acid mucopolysaccharide and RNA.
S. irideus showed some variations of the chromosome number around the mode at 2n=60, as a result of increasing and decreasing the number of chromosomal arms (NF) probably through the meiotic non-disjunction. S. trutta fario was found to possess a well individualized chromosome complement, such as 2n=80 and NF=104. It differs from the complement of the original species, S. trutta, by the number of chromosome arms. The increase of the NF is caused by the presence of 1-2 supplementary pairs of meta- or submetacentric chromosomes, probably produced through duplication processes.
The pairing of standard B chromosomes in rye plants with a small iso B or deficient B chromosome in addition to several standard B chromosomes, viz., the 2 stB+1 siB plant, the 2 stB+1 defB plant and the 4 stB+1 defB plant, was observed in comparison with the 2 to 5 stB plants and with the 2 stB+1 liB plant. Frequencies of the pairing of standard B chromosomes in the former three plants were considerably lower than those in the latter plants. This indicates that the presence of the small iso B or the deficient B chromosome reduces the amount of pairing between standard B chromosomes. This may be due to the deficience of a special distal segment of the long arm of the standard B chromosome.
Cytological effects of three growth substances namely, Gibberellic acid (GA), Indole-butyric acid (IBA), and 2, 4-Dichlorophenoxyacetic acid (2, 4-D) were studied on root tip mitosis of Vicia faba treated with 10 and 50 ppm concentrations and 3, 6 and 12 hours durations. GA enhanced cell division while 2, 4-D and IBA inhibited it and were more toxic than GA. Main effects at chromosomal level were chromosome breakage, bridge formation, C-mitosis, micronuclei formation, stickiness and chromosome condensation.
A standard salivary chromosome map for Anopheles (Cellia) philippinensis has been constructed and presented. A comparison of the banding pattern in the salivary chromosomes of A. philippinensis with those already investigated elsewhere has been made. A few characters in the band sequence have been observed to exist in almost all the species of the subgenus Cellia, thus, reflecting a possible evolution of various species from a common ancestral form.
The fine structural morphology of polyphosphate bodies is described after a variety of fixation and post-staining procedures. Glutaraldehyde fixation alone or in combination with osmium tetroxide provides the best preservation of polyphosphate bodies. Post-staining in uranyl acetate and lead citrate alone or in combination seems to extract polyphosphate bodies to varying degrees. Three morphological types of polyphosphate bodies are described; electron dense, porous, and those having an electron transparent center with an electron dense periphery. The effect of fixation, post-staining and electron beam on these bodies is described. Thick sections (0.5, μm) observed at 100 KV also reveal these three morphologies. The authors suggest that investigators should observe unstained glutaraldehyde fixed sections to determine if polyphosphate bodies are present in their material.
The present investigation deals with morphological and cytological studies of a radiation induced tetraploid Capsicum annuum. The tetraploid was characterized by stunted growth, presence of thick, large leaves with larger stomata and increase in size and number of floral organs. Occurrence of varying numbers of quadrivalents, trivalents and univalents was observed in addition to bivalents. Lagging chromosomes seen at anaphase in varying numbers resulted in the formation of micronuclei in the tetrads. About 72% of the pollen produced were aborted. The polyploid was completely sterile with extremely poor fruit setting. The fruits were devoid of seeds.
The karyotypes of two subspecies of the cutthroat trout series, Salmo clarki, were determined from anterior kidney cells. One subspecies, S. c. clarki, the “coastal” cutthroat, has 2n=68 chromosomes (36 meta- or submetacentrics and 32 acrocentrics). The other subspecies, S. c. henshawi, one of the many forms of “inland” cutthroat, has 2n=64 chromosomes (40 meta- or submetacentrics and 24 acrocentrics). The fundamental arm number in both subspecies was estimated at 104. Evidently, chromosomal fusions or dissociations have played a major role in the chromosomal evolution of S. clarki.
A spherical body was found in the chloroplast of protonema of Pogonatum inflexum Lindb., Musci. Usually, it is one per chloroplast and about lμm in diameter. It locates in the center of each chloroplast. The spherical bodies showed strong basophile and were solubilized by TCA. They disappeared, when the protonema was grown in phosphorous-deficient medium. In addition to these facts, by the histochemical observations the spherical bodies are concluded to be a polyphosphate body.