Observations on the fine structure and development of the spindle at mitosis and meiosis in a marine centric diatom (Lithodesmium Undulatum)

1970 ◽  
Vol 6 (1) ◽  
pp. 131-156
Author(s):  
IRENE MANTON ◽  
K. KOWALLIK ◽  
H. A. VON STOSCH
Keyword(s):  
Living Cells ◽  
Slight Variation ◽  
Centric Diatom ◽  
Serial Sections ◽  
Spindle Microtubules ◽  
Physical Forces ◽  
First Time ◽  
Mitosis And Meiosis ◽  
Chromosome Movements ◽  
Different Parts

Numerical information with respect to spindle microtubules in serial sections of 3 cells at metaphase of the first meiotic division has been compiled and illustrated sufficiently to supplement the previous accounts with respect to both longitudinal and transverse views. At the equator the microtubules of the spindle are united laterally into bundles, the number of bundles being of the same order as that encountered at a premeiotic mitosis, though there is slight variation from cell to cell. The number of microtubules is greater than that at mitosis in a normal spermatogonium, though the distribution in different parts of the spindle is qualitatively similar. Stages of anaphase have been illustrated for the first time and shown to involve at least types of physical forces mediating chromosome movements of various kinds. The later stages of cytokinesis have been timed and are illustrated from living cells and from sections. The relation of the spindle to the cord which unites the separating protoplasts towards the end of cytokinesis has been traced in outline. The cord itself is shown to contain micro- tubules in limited number and it is therefore not the whole spindle. The interpretation of these findings is discussed in a preliminary way.

Observations on the Fine Structure and Development of the Spindle at Mitosis and Meiosis in a Marine Centric Diatom (Lithodesmium Undulatum)

1970 ◽  
Vol 7 (2) ◽  
pp. 407-443
Author(s):  
IRENE MANTON ◽  
K. KOWALLIK ◽  
H. A. VON STOSCH
Keyword(s):  
Centric Diatom ◽  
Serial Sections ◽  
Late Prophase ◽  
Haploid Chromosome Number ◽  
Male Gametogenesis ◽  
Common Time ◽  
Precursor Material ◽  
Mitosis And Meiosis ◽  
Meiosis I ◽  
Unusual Shape

The second meiotic division is shown to be of critical importance for interpretation of structures and events already seen at other divisions. The development of flagellar bases at interkinesis is demonstrated in relation to precursor material seen to accumulate near each pole at meiosis I. The name ‘paracentrosome’ is suggested for this material, which is used up in forming the flagellar bases and spindle precursor. The spindle at late prophase, metaphase and telophase II is shown to resemble those of other divisions except that it is consistently smaller; this fact is numerically demonstrated from serial sections of metaphase II cells. The greatly reduced size and unusual shape of the polar plates present in addition to flagellar bases at metaphase II suggest that these are in a sense equivalent structures with a mutually competitive relation to the paracentrosome. Preliminary observations with the light microscope on the relatively large nuclei of oogonia during meiosis I have shown that the haploid chromosome number is not less than 19 nor more than 23 and that chromatid separation in relation to the kinetochores at anaphase I is normal; the bearing of these findings on interpretation of the spindle is discussed. Comparisons with other organisms are carried out in a preliminary way and the investigation ends with a résumé of the more important externally visible events in male gametogenesis adjusted to a common time scale in the course of one day.

Observations on the Fine Structure and Development of the Spindle at Mitosis and Meiosis in a Marine Centric Diatom (Lithodesmium Undulatum)

1969 ◽  
Vol 5 (1) ◽  
pp. 271-298
Author(s):  
IRENE MANTON ◽  
K. KOWALLIK ◽  
H. A. VON STOSCH
Keyword(s):  
Fine Structure ◽  
Chromosome Structure ◽  
Centric Diatom ◽  
Serial Sections ◽  
Ground Plan ◽  
Living Culture ◽  
Full Discussion ◽  
Two Stages ◽  
Mitosis And Meiosis ◽  
Spindle Structure

Various cytoplasmic phenomena, including spindle structure and development during prophase of the first meiotic division, are described and illustrated. The living culture is represented by a timed sequence of photographs continuing those previously published with respect to mitotic stages in the same filament. The meiotic preliminaries include the so-called swelling phase, by which the parental frustule is forced open, liberating the contained spermatocytes. This occurs during pachytene on evidence of chromosome structure which is illustrated. A spindle precursor is shown to be present before opening of the frustule; this resembles structurally the mitotic equivalent though the ground plan is oblong instead of square. Growth of the precursor continues until after opening of the frustule, when the spindle itself begins to be laid down. Two stages of developing spindles during the later prophases are illustrated by sections cut in three planes and by serial sections. Preliminary comparisons are made with metaphase I and with mitosis, both qualitatively and quantitatively, but a full discussion is deferred pending completion of the record for the later meiotic stages.

Status of Family Fissidentaceae in Gujarat

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
D.G. Shah ◽  
D.N. Mehta ◽  
R.V. Gujar
Keyword(s):  
Distinct Species ◽  
The State ◽  
The Other ◽  
Land Plants ◽  
Reproductive Structures ◽  
The Family ◽  
The Status ◽  
Vegetative Characters ◽  
First Time ◽  
Different Parts

Bryophytes are the second largest group of land plants and are also known as the amphibians of the plant kingdom. 67 species of bryophytes have been reported from select locations across the state of Gujrat. The status of family fissidentaceae which is a large moss family is being presented in this paper. Globally the family consists of 10 genera but only one genus, Fissidens Hedw. has been collected from Gujarat. Fissidens is characterized by a unique leaf structure and shows the presence of three distinct lamina, the dorsal, the ventral and the vaginant lamina. A total of 8 species of Fissidens have been reported from the state based on vegetative characters as no sporophyte stages were collected earlier. Species reported from the neighboring states also showed the absence of sporophytes. The identification of different species was difficult due to substantial overlap in vegetative characters. Hence a detailed study on the diversity of members of Fissidentaceae in Gujarat was carried out between November 2013 and February 2015. In present study 8 distinct species of Fissidens have been collected from different parts of the state. Three species Fissidens splachnobryoides Broth., Fissidens zollingerii Mont. and Fissidens curvato-involutus Dixon. have been identified while the other five are still to be identified. Fissidens zollingerii Mont. and Fissidens xiphoides M. Fleisch., which have been reported as distinct species are actually synonyms according to TROPICOS database. The presence of sexual reproductive structures and sporophytes for several Fissidens species are also being reported for the first time from the state.

Carbon dots derived from Fusobacterium nucleatum for intracellular determination of Fe3+ and bioimaging both in vitro and in vivo

2021 ◽  
Author(s):  
Lijuan Liu ◽  
Shengting Zhang ◽  
Xiaodan Zheng ◽  
Hongmei Li ◽  
Qi Chen ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Fusobacterium Nucleatum ◽  
Living Cells ◽  
First Time ◽  
Fluorescent Carbon Dots ◽  
Fluorescent Carbon

Fusobacterium nucleatum has been employed for the first time to synthesize fluorescent carbon dots which could be applied for the determination of Fe3+ ions in living cells and bioimaging in vitro and in vivo with excellent biocompatibility.

Shilpakar Mahasabha in Colonial Uttarakhand: Subjective Representation of Collective Self

2021 ◽  
pp. 2455328X2110267
Author(s):  
Isha Tamta
Keyword(s):  
Caste System ◽  
Educational Institutions ◽  
Mutual Aid ◽  
British Raj ◽  
Collective Self ◽  
Lower Castes ◽  
Colonial Government ◽  
First Time ◽  
Subjective Representation ◽  
Different Parts

The caste system in India got transformed as a consequence of the policies of the British Raj. The introduction of the census under the colonial government, among other things, made the most direct impact because for the first time the castes have been enumerated with great details. As a result, castes immediately not only organized themselves but also formed caste associations in order to get their status recorded in the way they thought was honourable to them. Caste associations emerged over the period to pressurize the colonial administration to improve their rank in the census. This process was especially prevalent among the lower castes in different parts of India. Shilpakar Mahashaba was a case in point in Uttarakhand. Shilpakar Mahasabha claimed new advantages from the state like reservations (quotas) in educational institutions and in the civil service. Subsequently, they also became mutual aid structures. Shilpakar Mahasabha founded schools and hostels for the children of Shilpakars and led a sort of co-operative movement. Some have argued that caste associations acted like a collective enterprise with economic, social and political objectives for their caste.

Profesorowie Uniwersytetu Jagiellońskiego: Władysław Chłopicki i Władysław Reiss oraz ich powiązania rodowe, czyli o Krupniczej nieco inaczej

2021 ◽  
Author(s):  
Maria Przybyszewska
Keyword(s):  
Military Leaders ◽  
Family Ties ◽  
Politics And Science ◽  
Tenement House ◽  
The Family ◽  
History Of ◽  
Individual Decisions ◽  
First Time ◽  
Different Parts

The history of the inhabitants of the house at 5 Krupnicza Street in Krakow inspired to write this book, the aim of which is to present the history of two families who came to Krakow from different parts of Poland. The „Pod Matką Boską” tenement house, which has become a life haven for so many generations of Reiss and Chłopicki, including medical professors associated with the Jagiellonian University, is the basis of a much wider story about the intertwining of human lives. Thanks to these circumstances, we restore memory, and we often realise for the first time how far fates of families intertwine and connect with each other. Reaching deeply into the family roots, we not only find numerous family ties, but also appreciate their importance. We also understand better how history influences the course of life and how individual decisions can influence the course of events. The pages of this book will include wellknown and distinguished figures, who have their place in the history of politics and science, as well as doctors, military leaders, politicians. There will be also room for those who cared about family and public matters without publicity, serving current and everyday matters, but without whom great things could not have been fulfiled.

scholarly journals Dynamic nanoscale morphology of the ER surveyed by STED microscopy

2018 ◽  
Vol 218 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Lena K. Schroeder ◽  
Andrew E.S. Barentine ◽  
Holly Merta ◽  
Sarah Schweighofer ◽  
Yongdeng Zhang ◽  
...  
Keyword(s):  
Living Cells ◽  
Stimulated Emission ◽  
Membrane Structures ◽  
Spatiotemporal Resolution ◽  
Sted Microscopy ◽  
Superresolution Microscopy ◽  
Structure And Dynamics ◽  
First Time ◽  
Nanoscale Dynamics ◽  
Conventional Light Microscopy

The endoplasmic reticulum (ER) is composed of interconnected membrane sheets and tubules. Superresolution microscopy recently revealed densely packed, rapidly moving ER tubules mistaken for sheets by conventional light microscopy, highlighting the importance of revisiting classical views of ER structure with high spatiotemporal resolution in living cells. In this study, we use live-cell stimulated emission depletion (STED) microscopy to survey the architecture of the ER at 50-nm resolution. We determine the nanoscale dimensions of ER tubules and sheets for the first time in living cells. We demonstrate that ER sheets contain highly dynamic, subdiffraction-sized holes, which we call nanoholes, that coexist with uniform sheet regions. Reticulon family members localize to curved edges of holes within sheets and are required for their formation. The luminal tether Climp63 and microtubule cytoskeleton modulate their nanoscale dynamics and organization. Thus, by providing the first quantitative analysis of ER membrane structure and dynamics at the nanoscale, our work reveals that the ER in living cells is not limited to uniform sheets and tubules; instead, we suggest the ER contains a continuum of membrane structures that includes dynamic nanoholes in sheets as well as clustered tubules.

Molecular identification of cyst-forming nematodes (Heteroderidae) from Iran and a phylogeny based on ITS-rDNA sequences

Nematology ◽  
2003 ◽  
Vol 5 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Zahra Tanha Maafi ◽  
Sergei Subbotin ◽  
Maurice Moens
Keyword(s):  
Phylogenetic Analyses ◽  
Species Level ◽  
Its Rdna ◽  
Heterodera Avenae ◽  
Published Data ◽  
Rdna Sequences ◽  
First Time ◽  
Group Species ◽  
High Support ◽  
Different Parts

Abstract RFLP and sequences of ITS-rDNA of 45 populations of cyst-forming nematodes collected from different parts of Iran were analysed and identified as representatives of 21 species. Eight enzymes generated RFLP for all studied populations. Comparison of RFLP profiles and sequences of the ITS regions with published data confirmed the presence of Heterodera avenae, H. filipjevi, H. glycines, H. hordecalis, H. latipons, H. schachtii and H. trifolii in Iran. RFLP patterns and ITS sequences for H. elachista, H. turcomanica, H. mothi and C. cacti were obtained for the first time in this study. Heterodera humuli, H. goettingiana, H. fici, H. elachista, H. turcomanica and Cactodera cacti are recorded for the first time in Iran. These results correspond with morphological and morphometric identification of the populations. Several populations were not identified at the species level and are attributed to Heterodera sp.; some of these may correspond to new species. Twenty-one new sequences from Iranian cyst-forming nematodes and 36 known sequences were used for the phylogenetic analyses. The cyst-forming nematodes formed several clades corresponding to their morphological features. Heterodera mothi and H. elachista clustered with high support with other Cyperi group species and H. turcomanica formed a moderately to highly supported clade with the Humuli group.

scholarly journals Non-linear evolution of the resonant drag instability in magnetized gas

2019 ◽  
Vol 485 (3) ◽  
pp. 3991-3998 ◽  
Author(s):  
Darryl Seligman ◽  
Philip F Hopkins ◽  
Jonathan Squire
Keyword(s):  
Linear Theory ◽  
Coherent Structures ◽  
Magnetic Energy ◽  
Density Fluctuations ◽  
Linear Evolution ◽  
Drag Forces ◽  
Non Linear ◽  
Magnetohydrodynamic Simulations ◽  
First Time ◽  
Different Parts

Abstract We investigate, for the first time, the non-linear evolution of the magnetized ‘resonant drag instabilities’ (RDIs). We explore magnetohydrodynamic simulations of gas mixed with (uniform) dust grains subject to Lorentz and drag forces, using the gizmo code. The magnetized RDIs exhibit fundamentally different behaviour than purely acoustic RDIs. The dust organizes into coherent structures and the system exhibits strong dust–gas separation. In the linear and early non-linear regime, the growth rates agree with linear theory and the dust self-organizes into 2D planes or ‘sheets.’ Eventually the gas develops fully non-linear, saturated Alfvénic, and compressible fast-mode turbulence, which fills the underdense regions with a small amount of dust, and drives a dynamo that saturates at equipartition of kinetic and magnetic energy. The dust density fluctuations exhibit significant non-Gaussianity, and the power spectrum is strongly weighted towards the largest (box scale) modes. The saturation level can be understood via quasi-linear theory, as the forcing and energy input via the instabilities become comparable to saturated tension forces and dissipation in turbulence. The magnetized simulation presented here is just one case; it is likely that the magnetic RDIs can take many forms in different parts of parameter space.

scholarly journals Lungworm infections in dogs from Central Europe

2018 ◽  
Vol 63 (No. 8) ◽  
pp. 367-372 ◽  
Author(s):  
V. Cabanova ◽  
Z. Hurnikova ◽  
M. Miterpakova ◽  
K. Dirbakova ◽  
A. Bendova ◽  
...  
Keyword(s):  
Case Report ◽  
Zinc Sulphate ◽  
Conventional Pcr ◽  
Travel History ◽  
Baermann Technique ◽  
High Prevalence ◽  
Flotation Method ◽  
Zinc Sulphate Solution ◽  
First Time ◽  
Different Parts

Angiostrongylus vasorum and Crenosoma vulpis are parasites in the respiratory tract of domestic and wild carnivores. Recently, an increasing number of lungworm infections in dogs has been recognized in Europe. In this report, the results of the first copro-epidemiological study of A. vasorum and C. vulpis in dogs from Slovakia are presented. The Baermann technique and the modified flotation method with zinc sulphate solution (specific gravity 1.2) was used for lungworm detection. In addition, conventional PCR was performed for species confirmation. The majority of lungworm infections were found in the eastern part of the country. A relatively high prevalence (4.13%) of A. vasorum was detected in different parts of Slovakia. Infection was detected most frequently incidentally in asymptomatic dogs. Within this study, crenosomosis was detected for the first time in dogs from Slovakia. Since one infected dog had no travel history, the case is considered autochthonous. An autochthonous case report of angiostrongylosis in a Hanoverian hound puppy from central Slovakia is also described.

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