scholarly journals Localization of actin and myosin for the study of ameboid movement in Dictyostelium using improved immunofluorescence.

1984 ◽  
Vol 99 (3) ◽  
pp. 894-899 ◽  
Author(s):  
S Yumura ◽  
H Mori ◽  
Y Fukui
Keyword(s):  
Developmental Stages ◽  
Contact Region ◽  
The Other ◽  
Cell Cortex ◽  
Cortical Region ◽  
Cell Periphery ◽  
Specific Staining ◽  
Posterior Cortex ◽  
Other Hand ◽  
Overlay Technique

The distribution of actin and myosin in Dictyostelium amebae at different developmental stages was studied by improved immunofluorescence ("agar-overlay" technique). Both were localized at the cortical region of amebae in all early developmental stages. In amebae with polarized morphology, bright fluorescence with antiactin was seen in the anterior pseudopode. The cortex in the posterior end was also stained with antiactin. On the other hand, very specific crescent-shaped staining with antimyosin was seen at the posterior cortex. In cells in contact with each other, actin was concentrated at the contact region, whereas myosin was localized specifically in the cortex on the other side of the contact region. At the aggregation stage, when monopodial amebae migrate forming streams, actin staining was seen all around the cell periphery, with intense fluorescence in the anterior pseudopode. On the other hand, specific staining of myosin was seen only at the posterior cortex. The cleavage furrow of cells performing cytokinesis displayed distinct myosin staining, and this staining represented the filamentous structure aligned in parallel to the axis of constriction. These findings indicate that myosin staining reflects the portion of the cell cortex where contraction occurs and the motive force of ameboid movement is generated at the posterior cortex of a migrating cell.

OnBraula coecaNitsch and its affinities

Parasitology ◽  
1942 ◽  
Vol 34 (1) ◽  
pp. 88-100 ◽  
Author(s):  
A. D. Imms
Keyword(s):  
Developmental Stages ◽  
Degenerative Change ◽  
Instar Larva ◽  
The Other ◽  
Divergent Evolution ◽  
Hormone Activity ◽  
Other Hand ◽  
Close Relationship

The developmental stages ofBraula coecaare described. The larva is an inquiline living in a tubular burrow which it makes by mining on the inner side of the capping of the honey cells in the comb of the hive bee. It is meta-pneustic and bears characteristic anterior and posterior girdles of sensoria.The pupa is apparently unique among Cyclorrhapha in that it is enclosed within the unmodified cuticle of the 3rd instar larva, no puparium being formed. It is suggested that this feature is a degenerative change owing to the cessation of a particular phase of hormone activity.The similarity of form and structure shown by the larvae ofBraulaand of the Chamaemyiidae (Ochthiphilidae) is indicative of a fundamentally close relationship. Their imagines on the other hand have undergone widely divergent evolution.

scholarly journals STUDIES ON CELL DEFORMABILITY

1966 ◽  
Vol 30 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Leonard Weiss
Keyword(s):  
Electrophoretic Mobility ◽  
Proteolytic Enzymes ◽  
The Other ◽  
Cell Periphery ◽  
Cell Deformability ◽  
Other Hand ◽  
Sarcoma 37 ◽  
Cellular Deformability ◽  
Murine Sarcoma

Murine sarcoma 37 ascites cells were treated with the proteolytic enzymes, trypsin and chymotrypsin, after which cellular deformability and electrophoretic mobility were measured. It was shown that incubation with trypsin increased the ease with which the cells could be deformed without changing electrophoretic mobility, and that diisopropylfluorophosphate (DFP)-trypsin was inactive, a fact which suggests that trypsin-sensitive peptide linkages help to maintain the "tension" at the cell periphery. On the other hand, chymotrypsin reduced cellular electrophoretic mobility without appreciably altering deformability. This suggests that, although chymotrypsin-sensitive bonds do not contribute to "tension," they are in some way associated with charged groups at the cell periphery.

Valve morphogenesis in selected centric diatoms

Botany ◽  
2020 ◽  
Vol 98 (12) ◽  
pp. 725-733
Author(s):  
Irena Kaczmarska ◽  
James M. Ehrman ◽  
Nickolai A. Davidovich ◽  
Olga I. Davidovich ◽  
Yulia A. Podunay
Keyword(s):  
Sexual Reproduction ◽  
Developmental Stages ◽  
The Other ◽  
Centric Diatom ◽  
Silica Layer ◽  
Valve Development ◽  
Centric Diatoms ◽  
Unique Mode ◽  
Other Hand ◽  
Taxonomic Affiliation

The traditional taxonomic affiliation of the diatom Ardissonea crystallina (C. Agardh) Grunow has been recently questioned, as it exhibits a mixture of polar centric and araphid pennate characters. Overall valve architecture and mode of sexual reproduction suggest that araphid pennates are its closest relatives. On the other hand, recovered molecular phylogenies consistently place it among the polar centrics. Our investigation of the earliest stages of valve morphogenesis, formation of the basal silica layer, adds to the argument that A. crystallina is indeed a polar centric diatom. We compared developmental stages in A. crystallina with unequivocally centric diatoms (non-polar Hyalodiscus stelliger and polar Biddulphia tridens) and published literature for araphid pennates and determined that A. crystallina has evolved an apparently unique mode of valve development. The significance of valve morphogenesis in better understanding diatom evolution and diversification is discussed.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

ON THE OTHER HAND

1961 ◽  
Vol 6 (6) ◽  
pp. 222-223
Author(s):  
Edwin G. Boring
Keyword(s):  
The Other ◽  
Other Hand
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