Morphological Studies in Diapensiaceae. I. Chromosome Number and Microspore Development in Pyxidanthera brevifolia Wells

1968 ◽  
Vol 95 (6) ◽  
pp. 653 ◽  
Author(s):  
John D. Reynolds
Keyword(s):  
Chromosome Number ◽  
Microspore Development ◽  
Morphological Studies

Chromosome studies in 2n = 14 and 2n = 16 types of Medicago murex

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 159-163 ◽  
Author(s):  
A. Mariani ◽  
E. Falistocco
Keyword(s):  
Chromosome Number ◽  
Plant Morphology ◽  
C Banding ◽  
Morphological Studies ◽  
Staining Techniques

Karyological and morphological studies of Medicago murex with 2n = 16 and 2n = 14 chromosomes were undertaken. Analysis of the somatic chromosomes, using both conventional staining techniques and C-banding, showed that the 2n = 14 karyotype derived from the 2n = 16 karyotype. Plant morphology of the two types differs in relation to the characters of the leaves, florets, and pods. Attempts to obtain hybrids between the two types were completely unsuccessful. From these results it appears that the two M. murex types are not as closely related as has been usually considered and that they should be regarded as two different species.Key words: Medicago murex, chromosome number, C-banding.

CYTOGENETIC STUDIES IN AMARANTHUS: I. CYTOLOGICAL ASPECTS OF SEX DETERMINATION IN DIOECIOUS SPECIES

1959 ◽  
Vol 37 (3) ◽  
pp. 413-417 ◽  
Author(s):  
William F. Grant
Keyword(s):  
Chromosome Number ◽  
Sex Determination ◽  
Chromosome Numbers ◽  
Somatic Chromosome ◽  
Pollen Grain ◽  
Somatic Chromosome Number ◽  
Dioecious Species ◽  
Absolute Size ◽  
Morphological Studies ◽  
Cytogenetic Studies

Cytological observations are contained in this report on four dioecious species of Amaranthns, two of which were formerly included in the genus Acnida. The species studied are A. arenicola, A. palmeri, A. tamariscinus, and A. tuberculatus. Three of these species have a diploid chromosome number of 32, whereas A. palmeri has a somatic chromosome number of 34. A single spontaneous triploid (2n = 48) female plant was found in collections of A. tamariscinus and a tetraploid (2n = 64) male plant in collections of A. tuberculatus. A fifth species, A. australis, has previously been reported as having 32 somatic chromosomes. The chromosome numbers for half the dioecious species of Amaranthus have now been determined. Detailed observations on the dividing chromosomes of these species in mitosis, in meiosis, and in the first division of the nucleus in the pollen grain have been made and have failed to distinguish heteromorphic chromosomes which might be associated with sex determination. The small size of the chromosomes has made detailed morphological studies impractical and there is no marked difference in absolute size of the chromosomes between species. Since haploid numbers of 16 and 17 are found in both monoecious and dioecious species, it would seem that the aneuploid condition in Amaranthus arose early and hybridization within the genus has resulted in promoting the genie condition which has been necessary for the expression of the dioecious condition.

The taxonomy and distribution in eastern Canada of Polygonum arenastrum (4x = 40) and P. monspeliense (6x = 60), introduced members of the P. aviculare complex

1981 ◽  
Vol 59 (12) ◽  
pp. 2744-2751 ◽  
Author(s):  
J. McNeill
Keyword(s):  
Chromosome Number ◽  
Single Species ◽  
Sensu Stricto ◽  
The Other ◽  
Eastern Canada ◽  
Uniform Size ◽  
Chromosome Races ◽  
Morphological Studies ◽  
Distinguishing Features ◽  
Polygonum Arenastrum

The introduced nonmaritime knotweeds have generally been regarded in North America as comprising a single species called P. aviculare L. In recent years cytological and morphological studies have suggested that at least two chromosome races are present and that certain morphological features are correlated with chromosome number. There have been, however, discrepancies in the reports of the distribution and relative abundance of the two races. Studies of the morphology and cytology of introduced knotweeds in eastern Canada confirm the existence of two groups that are recognizable at species rank, and establish that the most common knotweeds in open habitats, e. g., along roadsides and sidewalks, are tetraploid plants distinguishable from their hexaploid relatives by the relatively uniform size of their leaves, the short and narrow free portion of the perianth segments, and by one side of the fruit being very much narrower than the other two. These plants are referable to P. arenastrum Boreau. This species is compared with the heterophyllous hexaploid, usually called P. aviculare sensu stricto, or, if that is considered a nomen ambiguum, P. monspeliense Pers. A table of distinguishing features, illustrations of the two species, and maps of their distribution in eastern Canada are provided.

An investigation of chromosome numbers in the genus Brachiaria (Poaceae: Paniceae) in relation to morphology and taxonomy

1987 ◽  
Vol 65 (11) ◽  
pp. 2297-2309 ◽  
Author(s):  
G. P. Basappa ◽  
M. Muniyamma ◽  
C. C. Chinnappa
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Indian Subcontinent ◽  
Base Number ◽  
Chromosome Races ◽  
Morphological Studies

Determinations of chromosome number and morphological studies of 260 populations, belonging to 32 taxa, of the genus Brachiaria from the Indian subcontinent reveal that all sexually reproducing taxa have no chromosome races. Six agamic taxa, viz., B. brizantha var. brizantha (n = 27), B. brizantha var. ciliata (n = 18), B. decumbens (n = 18), B. hybrida (n = 27), B. mutica (n = 18), and B. setigera var. albistyla (n = 14), have consistently shown uniformity in chromosome numbers, based on x = 7, 8, and 9. Brachiaria setigera var. setigera, a genetically unstable apomict, is the only taxon that tends to have a heteroploid series (n = 16, 17, 18, 21, and 32). The population of B. setigera var. setigera with n = 17 is based on a secondary base number of x = 17. There are 6 diploids, 20 tetraploids, 5 hexaploids, and 3 octoploids in the genus. Aneuploidy and triploidy are characteristically absent in the genus, although their plausible existence in the B. setigera complex cannot be ruled out. In several species certain previously reported chromosome numbers that deviate from the present study are found to be the result of erroneous identifications or the result of taxonomically complex situations such as those found in B. brizantha, the B. distachya complex, and the B. ramosa complex.

Fine Structural Localization of Acyltransferases Involved in Lipid Synthesis in Intestinal Mucosa.

1970 ◽  
Vol 28 ◽  
pp. 54-55
Author(s):  
R. J. Barrnett ◽  
J. A. Higgins
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Lipid Synthesis ◽  
Mucosal Cell ◽  
Structural Localization ◽  
Morphological Studies ◽  
Mucosal Cells ◽  
Initial Appearance ◽  
Sh Group ◽  
Hydrolysis Of ◽  
Intestinal Mucosal Cells

The main products of intestinal hydrolysis of dietary triglycerides are free fatty acids and monoglycerides. These form micelles from which the lipids are absorbed across the mucosal cell brush border. Biochemical studies have indicated that intestinal mucosal cells possess a triglyceride synthesising system, which uses monoglyceride directly as an acylacceptor as well as the system found in other tissues in which alphaglycerophosphate is the acylacceptor. The former pathway is used preferentially for the resynthesis of triglyceride from absorbed lipid, while the latter is used mainly for phospholipid synthesis. Both lipids are incorporated into chylomicrons. Morphological studies have shown that during fat absorption there is an initial appearance of fat droplets within the cisternae of the smooth endoplasmic reticulum and that these subsequently accumulate in the golgi elements from which they are released at the lateral borders of the cell as chylomicrons.We have recently developed several methods for the fine structural localization of acyltransferases dependent on the precipitation, in an electron dense form, of CoA released during the transfer of the acyl group to an acceptor, and have now applied these methods to a study of the fine structural localization of the enzymes involved in chylomicron lipid biosynthesis. These methods are based on the reduction of ferricyanide ions by the free SH group of CoA.

Chromic Acid Etching of Polyethylene

1973 ◽  
Vol 31 ◽  
pp. 72-73
Author(s):  
J. D. Muzzy ◽  
R. D. Hester ◽  
J. L. Hubbard
Keyword(s):  
Chromic Acid ◽  
Low Cost ◽  
Acid Etching ◽  
Crystalline Morphology ◽  
Bulk Specimen ◽  
Morphological Studies ◽  
Perfect Form ◽  
Molecular Length ◽  
Lamellar Texture ◽  
Cost Studies

Polyethylene is one of the most important plastics produced today because of its good physical properties, ease of fabrication and low cost. Studies to improve the properties of polyethylene are leading to an understanding of its crystalline morphology. Polyethylene crystallized by evaporation from dilute solutions consists of thin crystals called lamellae. The polyethylene molecules are parallel to the thickness of the lamellae and are folded since the thickness of the lamellae is much less than the molecular length. This lamellar texture persists in less perfect form in polyethylene crystallized from the melt.Morphological studies of melt crystallized polyethylene have been limited due to the difficulty of isolating the microstructure from the bulk specimen without destroying or deforming it.

Biological and Morphological Studies on Low-Leukemia-Strain Mice with Hodgkin's-Like Neoplasia Induced by Serial Cell-Free Transmission of Leukemic Organs of SJL/J Strain Mice

1968 ◽  
Vol 26 ◽  
pp. 210-211
Author(s):  
S. Fujinaga ◽  
K. Maruyama ◽  
C.W. Williams ◽  
K. Sekhri ◽  
L. Dmochowski
Keyword(s):  
Tissue Culture ◽  
Type A ◽  
Reticulum Cell ◽  
Type B ◽  
Viral Origin ◽  
Serial Transfer ◽  
Strain Mouse ◽  
Morphological Studies ◽  
Cell Neoplasm ◽  
Free Material

Yumoto and Dmochowski (Cancer Res.27, 2098 (1967)) reported the presence of mature and immature type C leukemia virus particles in leukemic organs and tissues such as lymph nodes, spleen, thymus, liver, and kidneys of SJL/J strain mice with Hodgki's-like disease or reticulum cell neoplasm (type B). In an attempt to ascertain the possibility that this neoplasia may be of viral origin, experiments with induction and transmission of this neoplasm were carried out using cell-free extracts of leukemic organs from an SJL/J strain mouse with spontaneous disease.It has been possible to induce the disease in low-leukemia BALB/c and C3HZB strain mice and serially transfer the neoplasia by cell-free extracts of leukemic organs of these mice. Histological examination revealed the neoplasia to be of either reticulum cell-type A or type B. Serial transfer is now in its fifth passage. In addition leukemic spleen from another SJL/J strain mouse with spontaneous reticulum cell neoplasm (type A) was set up in tissue culture and is now in its 141st serial passage in vitro. Preliminary results indicate that cell-free material of 39th tissue culture passage can reproduce neoplasia in BALB/c mice.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

Mast cell-nerve fiber interaction: Ultrastructural studies

1990 ◽  
Vol 48 (3) ◽  
pp. 428-429
Author(s):  
E.Y. Chi ◽  
M.L. Su ◽  
Y.T. Tien ◽  
W.R. Henderson
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Substance P ◽  
Nerve Fiber ◽  
Sensory Nerves ◽  
Ultrastructural Studies ◽  
Morphological Studies ◽  
Granulocyte Infiltration ◽  
Intracutaneous Injection ◽  
Recent Attention

Recent attention has been directed to the interaction of the nerve and immune systems. The neuropeptide substance P, a tachykinnin which is a neurotransmitter in the central and peripheral nervous systems produces tissue swelling, augemntation of intersitial fibrin deposition and leukocyte infiltration after intracutaneous injection. There is a direct correlation reported between the extent of mast cell degranulation at the sites of injection and the tissue swelling or granulocyte infiltration. It has previously been demonstrated that antidromic electrical stimulation of sensory nerves induces degranulation of cutaneous mast cells, cutaneous vasodilation and augmented vascular permeability. Morphological studies have documented a close anatiomical association between mast cells and nonmyelinated nerves, that contain substance P and other neuropeptides. However, the presence of mast cells within nerve fasicles has not been previously examined ultrastructurally. In this study, we examined ultrastructurally the distribution of mast cells in the nerve fiber bundles located in the muscular connective tissue of rat tongues (n=20).

Histochemical and Ultrastructural Studies of the Digestive Epithelium in a Gastropod Gametolytic Organ

1980 ◽  
Vol 38 ◽  
pp. 568-569
Author(s):  
R. L. Reeder ◽  
S. H. Rogers ◽  
W. A. Shannon
Keyword(s):  
Acid Phosphatase ◽  
Genital Tract ◽  
Reproductive Tract ◽  
Ultrastructural Level ◽  
Conclusive Evidence ◽  
Digestive Organ ◽  
Limited Information ◽  
Ultrastructural Studies ◽  
Morphological Studies

Numerous morphological studies have dealt with the spermatheca of pulmonate gastropods. This globular organ, which is attached to the female portion of the reproductive tract by a long duct in these monoecious animals, has had various functions ascribed to it. Recent histochemical demonstrations of deoxyribonuclease, ribonuclease, protease, and acid phosphatase have provided, however, conclusive evidence that it is a digestive organ for the degradation of superfluous sperm and genital tract secretions. Only limited information concerning the spermatheca is available at the ultrastructural level, a fact providing the stimulus for the present study of this organ in Sonorella santaritana, a desert mountain snail from Arizona.

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