The taxonomy of multivalent orientation: six modes of alternate or one?

1984 ◽  
Vol 26 (3) ◽  
pp. 389-392 ◽  
Author(s):  
J. Sybenga
Keyword(s):  
Biological Significance ◽  
Taxonomic Status ◽  
Alternate Orientation

Unlike adjacent I and II, alternate I and II orientations of interchange and tetrasome quadrivalents can be considered extremes within one particular population of orientations (alternate) and thus lack sufficient distinction to justify a separate taxonomic status. Within the population up to six types may be distinguished, but the biological significance of this distinction is small.Key words: multivalent, alternate orientation, adjacent orientation, chiasmata.

scholarly journals Metaphase position and orientation of an interchange quadrivalent of Allium triquetrum: II. Changes in position with changes in percentage alternate orientation

1985 ◽  
Vol 45 (2) ◽  
pp. 199-203 ◽  
Author(s):  
Geoffrey K. Rickards
Keyword(s):  
Biological Significance ◽  
Orientation Data ◽  
Alternate Orientation ◽  
Interchange Heterozygote ◽  
Position And Orientation ◽  
Metaphase I

SummaryThe position and orientation of an interchange quadrivalent in flattened lateral views of metaphase I were studied in inflorescences of an interchange heterozygote of Allium triquetrum showing high, medium and low alternate orientation frequencies. As the overall frequency of alternate orientation changes in these different inflorescences so the positioning of the alternately oriented quadrivalents changes, in that it becomes more like that of the adjacent quadrivalents. The present data argue for the biological significance of the position/orientation data, and imply the presence of two components of alternately oriented quadrivalents with different positional characteristics.

Microstructural morphology of sphingolipid dispersions as investigated by freeze-fracture EM

1995 ◽  
Vol 53 ◽  
pp. 944-945
Author(s):  
Vitthal S. Kulkarni ◽  
Wayne H. Anderson ◽  
Rhoderick E. Brown
Keyword(s):  
Acyl Chain ◽  
Biological Significance ◽  
Freeze Fracture ◽  
Fatty Acyl ◽  
Fatty Acyl Moiety ◽  
Aqueous Dispersions ◽  
Head Groups ◽  
Lipid Species ◽  
Microstructural Morphology ◽  
Layer Chromatography

The biological significance of the sphingomyelins (SM) and monoglycosylated sphingolipids like galactosylceramides (GalCer) are well documented Our recent investigation showed tubular bilayers in the aqueous dispersions of N-nervonoyl GalCer [N-(24:lΔ15,cls) GalCer] (a major fatty acyl moiety of natural GalCer). To determine the influence of lipid head groups on the resulting mesophasic morphology, we investigated microstructural self-assemblies of N-nervonoyl-SM [N-(24:1 Δ15,cls) SM; the second most abundant sphingomyelin in mammalian cell membranes], 1- palmitoyl-2-nervonoyl phosphatidylcholine [PNPC] (the lipid species with the same acyl chain configuration as in N-(24: 1) GalCer) and also compared it with egg-SM by freeze-fracture EM.Procedures for synthesizing and purifying N-(24:1) GalCer, N-(24:1) SM, and PNPC have been reported . Egg-SM was purchased from Avanti Polar Lipids, Alabaster AL. All lipids were >99% pure as checked by thin layer chromatography. Lipid dispersions were prepared by hydrating dry lipid with phosphate buffer (pH 6.6) at 80-90°C (3-5 min), vigorously vortexing (1 min) and repeating this procedure for three times prior to three freeze-thaw cycles.

Ultrastructural Localization Study of Carcinoembryonic Antigen (CEA) in Gastric Cancer: Immunoelectron Microscopic Observation

1990 ◽  
Vol 48 (3) ◽  
pp. 252-253
Author(s):  
Dong Yuming ◽  
Yang Guanglin ◽  
Wu Jifeng ◽  
Chen Xiaolin
Keyword(s):  
Gastric Cancer ◽  
Intestinal Metaplasia ◽  
Cancer Cells ◽  
Microscopic Observation ◽  
Biological Significance ◽  
Ultrastructural Localization ◽  
Mucinous Carcinoma ◽  
Surface Glycoprotein ◽  
Tubular Adenocarcinoma ◽  
Pap Method

On the basis of light microscopic observation, the ultrastructural localization of CEA in gastric cancer was studied by immunoelectron microscopic technique. The distribution of CEA in gastric cancer and its biological significance and the mechanism of abnormal distribution of CEA were further discussed.Among 104 surgically resected specimens of gastric cancer with PAP method at light microscopic level, the incidence of CEA(+) was 85.58%. All of mucinous carcinoma exhibited CEA(+). In tubular adenocarcinoma the incidence of CEA(+) showed a tendency to rising with the increase of degree of differentiation. In normal epithelia and intestinal metaplasia CEA was faintly present and was found only in the luminal surface. The CEA staining patterns in cancer cells were of three types--- cytoplasmic, membranous and weak reactive type. The ultrastructural localization of CEA in 14 cases of gastric cancer was studied by immunoelectron microscopic technique.There was a little or no CEA in the microvilli of normal epithelia. In intestinal metaplasia CEA was found on the microvilli of absorptive cells and among the mucus particles of goblet cells. In gastric cancer CEA was also distributed on the lateral and basal surface or even over the entire surface of cancer cells and lost their polarity completely. Many studies had proved that the alterations in surface glycoprotein were characteristic changes of tumor cells. The antigenic determinant of CEA was glycoprotein, so the alterations of tumor-associated surface glycoprotein opened up a new way for the diagnosis of tumors.

The hydroid research of American naturalist Samuel F. Clarke, 1851–1928

1997 ◽  
Vol 24 (1) ◽  
pp. 19-36 ◽  
Author(s):  
DALE R. CALDER ◽  
LESTER D. STEPHENS
Keyword(s):  
Developmental Biology ◽  
Taxonomic Status ◽  
Doctoral Dissertation ◽  
Nominal Species ◽  
Marine Biological Laboratory ◽  
Spotted Salamander ◽  
Johns Hopkins University ◽  
American Naturalist ◽  
American Schools ◽  
American Society

Samuel Fessenden Clarke was the leading specialist on hydroids (phylum Cnidaria) in North America over the last quarter of the nineteenth century. During that period he published taxonomic papers on hydroids from both the Atlantic and Pacific coasts of the continent, from the Gulf of Mexico, and from the eastern Pacific off Central and South America. He also authored a section on hydrozoan biology for “The Riverside Natural History” series. Most of his papers on hydroids were published while he was in his twenties. Clarke described as new 61 nominal species, three nominal genera, and one nominal family, as well as two “varieties” of hydroids. A list of these, and their current taxonomic status, appears in the present work. Clarke consistently provided sound descriptions and locality data for all supposed new species, and drew accurate illustrations of most of them. His research on Hydrozoa, beyond alphataxonomy, was directed towards faunal distributions and the use of hydroid assemblages as biogeographic indicators. In addition to investigations on hydroids, Clarke carried out research on the developmental biology of amphibians and reptiles. His doctoral dissertation at Johns Hopkins University was based on the embryology of the “Spotted Salamander” (=Yellow-spotted Salamander), and he published a major paper on the habits and embryology of the American Alligator. Most of Clarke's career was devoted to academic duties at Williams College, Massachusetts, where he was recognized as a dedicated and inspiring teacher. He served the American Society of Naturalists in various capacities, including a term as its president, was an influential trustee of the Marine Biological Laboratory, Woods Hole, and promoted the study of science in American schools.

RIBONUCLEOPROTEIN PARTICLES CONTAINING mRNA and pre-mRNA

1973 ◽  
Vol 74 (Suppl) ◽  
pp. S130-S167 ◽  
Author(s):  
O. P. Samarina ◽  
E. M. Lukanidin ◽  
G. P. Georgiev
Keyword(s):  
Structural Organization ◽  
General Scheme ◽  
Biological Significance ◽  
Mrna Transport ◽  
Ribonucleoprotein Particles ◽  
Mrna Precursor

ABSTRACT This paper is a review of the data concerning the nature, structural organization, properties and biological significance of the particles, containing mRNA and pre-mRNA (precursor of mRNA), i. e., (1) nuclear pre-mRNA-containing particles (2) free cytoplasmic mRNP (ribonucleoproteins), or informosomes (3) polysome-bound mRNP. Some new data on the comparison of nuclear and cytoplasmic particles, the nature of poly A-containing structures, involvement of informofers in Adenovirusspecific RNA transfer are presented. The general scheme of mRNA transport from nucleus to cytoplasm is discussed.

Notes on the molecular taxonomy of the Proclossiana eunomia complex (Lepidoptera, Nymphalidae: Argynnini): analysis of DNA barcodes

2018 ◽  
Vol 8 (1) ◽  
pp. 222-232 ◽  
Author(s):  
R. V. Yakovlev ◽  
N. A. Shapoval ◽  
G. N. Kuftina ◽  
A. V. Kulak ◽  
S. V. Kovalev
Keyword(s):  
Body Size ◽  
Molecular Taxonomy ◽  
Taxonomic Status ◽  
Molecular Data ◽  
Coi Gene ◽  
Wing Pattern ◽  
Molecular Approach ◽  
Dna Barcodes ◽  
Morphological Differences ◽  
Proclossiana Eunomia

The Proclossiana eunomia (Esper, 1799) complex is currently composed of the several subspecies distributed throughout Palaearсtic region and North America. Despite the fact that some of the taxa have differences in wing pattern and body size, previous assumptions on taxonomy not supported by molecular data. Therefore, the identity of certain populations of this complex has remained unclear and the taxonomic status of several recently described taxa is debated. Here, we provide insights into systematics of some Palaearctic members of this group using molecular approach, based on the analysis of the barcoding fragment of the COI gene taking into account known morphological differences.

Recent Rapid Climate Changes in Antarctic and their Influence on Low Diversity Ecosystems

2010 ◽  
Vol 17 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Katarzyna J. Chwedorzewska
Keyword(s):  
Environmental Variables ◽  
Climate Changes ◽  
Biological Significance ◽  
Global Changes ◽  
Factors Affecting ◽  
Low Diversity ◽  
Main Factors ◽  
The Antarctic ◽  
High Diversity ◽  
Temperature Water

ABSTRACTThe geographic position, astronomic factors (e.g. the Earth’s maximum distance from the Sun during winter), ice cover and altitude are the main factors affecting the climate of the Antarctic, which is the coldest place on Earth. Parts of Antarctica are facing the most rapid rates of anthropogenic climate change currently seen on the planet. Climate changes are occurring throughout Antarctica, affecting three major groups of environmental variables of considerable biological significance: temperature, water, UV-B radiation.Low diversity ecosystems are expected to be more vulnerable to global changes than high diversity ecosystems

ECOLOGICAL SIGNIFICANCE OF PHEROMONES

2020 ◽  
Vol 6 (2) ◽  
pp. 64-68
Author(s):  
Nondira Khondhodjayeva ◽  
◽  
Nurmamat Rajabov ◽  
Keyword(s):  
Biological Significance ◽  
Ecological Significance ◽  
Definition Of

This article reveals the essence of the concept of "pheromones" and their biological significance. In the article variants of their application in agriculture for struggle against insects-pests are presented. The definition of term and classification of pheromones and their types are given: feromons of insects, feromons of fish, feromons of vertebrates, feromons of humans, fermons of plants, sexual feromons, anxiety feromons, trace feromons, epidemic feromons and their functions and significance for the representative's organism and the environment as a whole

The biological significance of mtNOS modulation

10.2741/2124 ◽  
2007 ◽  
Vol 12 (1) ◽  
pp. 1041 ◽  
Author(s):  
María, C. Carreras
Keyword(s):  
Biological Significance
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