The anatomy and histology of the Malpighian tubules of Diatraea saccharalis larvae have been studied by stereoscope, light and scanning electron microscopy. Tubules lie between hindgut and mid-midgut; and may be subdivided into proximal, middle and distal region. Two ampullae inserted laterally before the pylorus show 2 tubules derived from each. One tubule bifurcates into 2 in the third abdominal segment; these loop backward to the hindgut to form the cryptonephridial system. Whereas larvae have 6 complete tubules, 3 on each side, histological analysis reveals 1 layer containing 2 cells, forming the lumen, microvilli at the top of cells, tracheae and tracheoles, and crystals in the tubule lumen, mainly in the middle and distal regions.
Cytomixis has been observed in pollen mother cells of Vicia faba. Of all eight sites plant materials were collected and investigated, cytomixis has been noted in six. Four of these sites recorded high percentage of cytomixis, where the two other sites show low concentration of this phenomenon. Cytomixis was observed to occur in forms of cytoplasmic connection and direct fusion. The first type is more frequent than second one. Both types of connections were observed in majority of stages of division. The amount of nuclear material transferred from cell to another was variable from small fragments to the entire complement based on the nature of connection. Abnormalities were observed in all sites investigated. Close relationship is clear between the percentage of this parameter and the percentage of cytomixis. The percentage of pollen fertility is clearly affected by cytomixis and abnormalities. Causes of cytomixis in the present study almost refer to environmental stress and pollution.
Chromosomal abnormalities in 55 AML patients from Orissa (India) were studied. Of them, 12 patients had only abnormal metaphases (AA), 41 patients had both normal and abnormal metaphases (AN) and the rest 2 patients exhibited only normal metaphases (NN). Basing on the number of chromosome all the patients were classified into 5 sub-groups like (1) normal diploidy with 46 chromosomes in 2 patients, (2) pseudodiploidy group with 46 chromosomes and some structural abnormalities in 4 patients, (3) hypodiploid group with <46 chromosomes in 37 patients, (4) hyperdiploidy-A group with 47 to 50 chromosomes in 8 patients and hyperdiploidy-B group with >50 chromosomes in 4 patients. Primary translocations like t(8, 21), t(1, 14), t(9, 22) were detected in 8, 1 and 7 patients respectively. In addition, secondary aberrations were also observed in 36 patients. These secondary aberrations were mostly unstable and nonclonal ones which were present singly or in various combinations. Maximum number of patients achieved complete remmission (CR) from AN subgroup (46.3%) hyperdiploidy-B group (100%), patients with t(8; 21) translocation (75%), patients with trisomy 22 and patients with no secondary aberrations. This study suggests that hyperdiploidy, t(8, 21), trisomy 8, presence of both normal and abnormal metaphases and absence of secondary aberrations are the favourable prognosticators while presence of only abnormal metaphases, presence of more than one secondary aberration, t(9, 22) translocation, hypodiploidy and monosomy 7 are unfavourable prognosticators.
Cytogenetic studies in 2 populations of Rhamdia quelen collected from the Taquarussu river and Maringá stream were carried out. Both populations showed diploid number 2n=58 chromosomes but differed in relation to the caryotype formulae (26M+20SM+6ST+6A, 26M+22SM+6ST+4A respectualy). Beside the Taquarussu population showed 1 to 4 metacentric B chromosomes. Different-sized of B chromosomes were reported: middle-sized were more frequent; large-sized ones were found in only one specimen. Maringá population showed karyotypic variation in 22% of the individual (26M+24SM+8ST), indicating the occurrence of structural rearrangements. Ag-NOR analysis revealed simple NOR system for both, although there were differences in the region's bearer pair type. C-banding results showed weak telomere or centromere markings in certain chromosomes and more evident bands in the NOR region and at the extremities of the 2 B chromosome types. Chromomycin A3 coloration revealed NOR to be CMA3 positive in the 2 populations and consequently rich in GC. B chromosomes are CMA3 negative.
The present report describes briefly the mitotic, polyneme and polytene chromosomal karyotype (2n=10) of the newly identified Indian specimen, Anatopynia spp. Based on our observations, cytogenetic implications involved were surmised with respect to the short and stumpy fifth element in the polytene complement.
The study involves the chromosomal constitution of advanced progenies of amphidecaploid Avena sativa and A. maroccana. Amphidecaploid 2n=10x=70 was raised from a pentaploid interspecific cross A. sativa×A. magna (Syn. A. maroccana). The selfed progenies of the amphiploid were scored for chromosomal constitution in A14, A15 and A16 generations. It was observed that while there was a general breakdown and loss of chromosomes over the generations, but at the same time stable polysomics with 2n=44, 46, 50, 52, 54, 60, 62, 64, 66 and 68 were isolated together with progenies having female parent number of 2n=6x=42 (A. sativa) and original decaploid number of 2n=10x=70. No progenies with less than 2n=6x=42 were recovered, although male parent happens to be a tetraploid with 2n=4x=28. A general reduction in the number of multivalents and consequent increase in bivalent configurations was observed from A0 to A16 generations.
Meiotic pairing association and chiasma frequency were studied in a gamma-ray induced primary trisomic of grass pea (Lathyrus sativus L.). The trisomic was identified by phenotypic abnormalities, early maturity and presence of an extra chromosome (2n+1=15), while occurrence of 7 bivalents was the usual feature in normal diploids (2n=14). In the trisomic, formation of a univalent was more common than that of a trivalent, although bivalent association was predominant. Ring bivalents appeared more frequently than chain or rod configurations. Terminalization of 2 chiasmata in the 2 arms may give rise to ring bivalent, while a single chiasma may terminalize to form a chain. In the trisomic, frequent occurrence of linear or frying pan configuration and occasionally Y-shaped trivalent formation indicated unmodified nature of the extra chromosome; this characterized it as a primary trisomic. Terminalization of chiasmata in both the arms of a chromosome involving its 2 homologous partners may result in linear configuration, while a chiasma in the distal end with another chiasma in the same arm may give rise to frying pan configuration, but an interstitial chiasma accompanied with another chiasma formed at the terminal position distal to former might form Y-shaped trivalent. Configuration of trivalent may thus be influenced by the number and position of chiasmata. Compared to normal diploids chiasma frequency reduced in the trisomic. More frequent occurrence of unequal anaphasic separation of chromosomes may be attributed to reduced pollen fertility in the trisomic.
In the present work, spermatogenesis was analyzed in 3 species of the genus Triatoma (T. platensis, T. proctata, T. tibiamaculata). Lacto-acetic orcein staining was used in order to investigate chromosomal meiotic behavior of these species. It allowed the identification of the T. tibiamaculata karyotype (20, X1X2Y), the observation that in T. protacta doesn't occur late migration of sexual chromosomes and corroborated knowledgments about holocentric chromosome nature.
In the present work 4C DNA amount has been determined in 3 species of Fabaceous genus Cyamopsis involving 14 accessions. At intraspecific level 10 collections of C. tetragonoloba, 2 collections each of C. senegalensis and C. serrata did not show any significant variation. Within the genus Cyamopsis, C. serrata possessing symmetrical karyotype is a primitive species with 20.35 pg of DNA and more advanced species having asymmetrical karyotype has 18.19 pg DNA and recently evolved cultivated crop species has 10.05 pg of DNA. Two fold DNA amount variation is apparent without any numerical changes in chromosome number, as all the Cyamopsis species share a common chromosome number of 2n=2x=14. Thus evolution of genome size within small African genus Cyamopsis has occurred through loss of DNA.
It is well known that after mixing gametes of two mating types of the green alga Chlamydomonas reinhardtii, intracellular cAMP concentration increases within 1 min, and zygotes are formed within 10 min. We have shown that within 10 min after the mixing, zys genes are expressed. In the present study, we isolated and determined the sequence for a zys3 genomic clone. Comparing this 5′ upstream region with those of zys1B and zys4, we detected putative AP-1-related elements including cyclic AMP responsive elements in three upstream gene regions.
Mitotic metaphase chromosomes of Crinum latifolium L., C. asiaticum L. and C. amoenum Roxb. (Fam.-Amaryllidaceae) were stained with orcein, CMA and DAPI. C. latifolium possessed 2n=33 chromosomes whereas the other two species had 2n=22 chromosomes. All these species showed 2 bright and thick CMA-positive bands at the intercalary regions of the long arms in 2 sub-metacentric chromosomes of group/pair VI. In addition, C. latifolium possessed another 2 CMA-positive bands 1 in each side of the centromere in a chromosome of group IX. After counter staining with DAPI, the intercalary CMA-banded regions of C. asiaticum and C. amoenum showed deep DAPI-negative bands. It indicates the possible presence of NORs. No DAPI-negative band was found in C. latifolium. In these 3 species 8–12 DAPI-positive bands were observed on various chromosomes. In C. asiaticum and C. amoenum these bands were located in the centromeric regions whereas in C. latifolium, most of the bands appeared in the long arms of respective chromosomes. The presence of 2n=33 chromosomes, the number and distribution of CMA and DAPI-bands, together with gigas features indicated that the specimen of C. latifolium studied is not an auotriploid, may be an allotriploid or a segmental one.
The chromosomes of the new species Schoenoplectus gemmifer and the allied S. mucronatus var. mucronatus and S. triangulatus were studied in culm-apex cells and root-tip cells. The mitotic metaphase chromosomes were small and dot-like. The chromosome number in culm-apex cells was stable and was observed to be 2n=74 in S. gemmifer, 2n=38 in S. mucronatus, and 2n=42 in S. triangulatus, respectively. Thus, it was confirmed that the new species S. gemmifer was cytologically different from both S. mucronatus and S. triangulatus. Inter- and intra-individual variations in chromosome number, mixoploidy and aneuploidy, were found in the root-tip cells of the three species. Chromosome number (2n) varied from 68 to 74 in S. gemmifer, 2n=32 to 39 in S. mucronatus and 2n=37 to 44 in S. triangulatus, respectively. This phenomenon is very rare and this is the first report in the genus Schoenoplectus.
The 2 close related genera Coffea and Psilanthus present few cytogenetic studies due to their chromosomal symmetry. In the present we studied cytogenetically 4 species of the Coffee Germplasm Bank of the IAC: Coffea brevipes, C. racemosa, Psilanthus bengalensis and P. travancorensis. For heterochromatic banding assays the fluorochromes CMA3 and DAPI were used. For FISH assays the probes pTa71 and pScT7 were used to detect 18S-5.8S-26S (NOR) and 5S rDNA sites respectively. None of the 4 species presented DAPI positive bands. C. racemosa and P. travancorensis presented 2 CMA3 positive band pairs while the other 2 species presented only 1. Only C. racemosa presented more than 1 pair of NOR sites. Although we observed remarkable cytological similarity between the studied species and genera, the analysis based on these cytogenetic markers contributed to karyological characterization of these species and provided more data to taxonomic discussion in the group.
The complete nuclear genome size of the red alga Cyanidioschyzon merolae, 1.5–2 μm in diameter, was determined as 16.5 Mbp by our Genome Project. Based on comparing data between the correct value and the size previously described, we considered simple molecular and cytological methods to identify the correct value for genome size. The results showed that the 16.4 Mbp by the vide-enhanced photon-counting method after DAPI staining rather than pulse field electrophoresis was the closest to the Genome Project value. We determined the genome size of Ostreococcus tauri as 0.6 μm in diameter by the VIM system after staining with DAPI and SYBR Green I. The results showed that the genome size of the alga is approximately 35 Mbp and larger than the 9.0–12 Mbp estimated by pulse-field electrophoresis, suggesting that cell size does not depend on genome size.
Cyanidioschyzon merolae is a unicellular red alga that lives in acidic hot springs. The genome sequence of C. merolae has been completely read, but a lack of transformation systems still limits its application in genetics. To choose an appropriate drug for use in selectable media, we examined the effects of seven antibiotics on the growth of C. merolae. Only cycloheximide, an inhibitor of protein synthesis, effectively inhibited the growth. We noticed that there was a population that could survive in the presence of cycloheximide and succeeded in isolating six cycloheximide-resistant clones. All these clones have the same single mutation in the ribosomal protein L29 gene that encodes a ribosomal protein.
The DNA content of individual mitochondrial nucleoids (mt-nucleoids) in the stationary-phase cells of the yeast Saccharomyces cerevisiae was quantitatively measured by a combination of DAPI-staining and use of a video-intensified microscope photon counting system (VIMPCS). The mt-nucleoids in the cells which were grown aerobically in AN medium contained, on average, 1.5 mitochondrial DNA (mtDNA) molecules per mt-nucleoid, and the mt-nucleoids that were isolated from these cells contained 1.1 mtDNA molecules per mt-nucleoid. In contrast, the giant mt-nucleoids that appeared in the cells grown anaerobically in the same medium contained, on average, 20.3 mtDNA molecules per mt-nucleoid, and the giant mt-nucleoids that were isolated from these cells contained, on average, 13.1 mtDNA molecules per mt-nucleoid. These results, together with the previous data, demonstrated that the DNA content of individual mt-nucleoids and the number of mt-nucleoids in a cell were distinctly changed by the culture conditions of the yeast cells, whereas the total mtDNA content per cell did not vary significantly when the culture conditions were changed.