Form and function of the glycocalyx on free cell surfaces

1974 ◽  
Vol 268 (891) ◽  
pp. 55-66 ◽  
Keyword(s):  
Free Cell ◽  
Surface Coat ◽  
Cell Surfaces ◽  
Cell Coat ◽  
Fresh Tissue ◽  
Functional Roles ◽  
Form And Function ◽  
Freeze Etching ◽  
Coat Layer ◽  
And Function

Selected examples of the glycocalyx or cell coat on rickettsiae, bacteria, amoebae, sea-urchin eggs and the cat intestinal microvilli are illustrated and their functional roles are discussed. The differences in the form of various surface coats are noted; while many surface components are truely extraneous expendable coatings, others are so firmly attached that they seem to be a permanent part of the cell. The fuzzy surface coat on the cat intestinal microvilli have been considered in some detail and some new observations on the form of the glycocalyx are presented. The enteric surface coat is not readily visualized in fractured surface replicas of glycerinated tissue but fixed cells frozen in distilled water when replicated after freeze-etching reveal a flamboyant array of a filamentous meshwork attached to the microvilli. This fuzzy coat layer is at least twice as thick in the freeze-etched preparations when compared to thin sectioned material. Fresh tissue frozen without fixation or glycerin treatment did not have a thick fuzzy coat. In its place a thin amorphous blanket-like layer was found.

scholarly journals Reproductive Ontogeny and the Evolution of Morphological Diversity in Conifers and Other Plants

2019 ◽  
Vol 59 (3) ◽  
pp. 548-558 ◽  
Author(s):  
A B Leslie ◽  
J M Losada
Keyword(s):  
Morphological Evolution ◽  
Morphological Diversity ◽  
Developmental Rate ◽  
Reproductive Organs ◽  
Developmental Trajectory ◽  
Evolutionary Significance ◽  
Developmental Patterns ◽  
Functional Roles ◽  
Form And Function ◽  
And Function

Abstract Biologists often study morphological evolution through form and function relationships. But biological structures can perform multiple functional roles, complicating efforts to understand the evolutionary significance of any one relationship. Plant reproductive organs perform multiple roles in a sequence, however, which provides a unique opportunity to understand how structures evolve to meet multiple functional demands. Using conifers as a study group, we discuss how a shared developmental trajectory links the performance of sequential functional roles. Variation in development among lineages can underlie morphological diversity; pollination-stage seed cones in Pinaceae conifers function similarly but show diverse forms reflecting differences in developmental rate. As cones develop further, the morphologies that they use to perform later functional roles are influenced by the specific developmental patterns used to meet earlier demands, which may ultimately limit morphological diversity. However, we also show how selective pressures relating to the final functional stage (seed dispersal) may influence cone anatomy and morphology over all previous stages, highlighting the complex linkages among form, function, and development. We end by discussing the potential relationships between functional ontogeny and morphological disparity in plant reproductive structures more broadly, suggesting that the complex functional roles associated with seed plant reproduction probably underlie the high disparity in this group.

scholarly journals Intermediate filaments and the initiation of desmosome assembly.

1985 ◽  
Vol 101 (2) ◽  
pp. 506-517 ◽  
Author(s):  
J C Jones ◽  
R D Goldman
Keyword(s):  
Cell Surface ◽  
Intermediate Filaments ◽  
Ultrastructural Localization ◽  
Free Cell ◽  
Cell Protein ◽  
Epidermal Keratinocytes ◽  
Cell Contact ◽  
Cell Surfaces ◽  
Primary Mouse ◽  
And Function

The desmosome junction is an important component in the cohesion of epithelial cells, especially epidermal keratinocytes. To gain insight into the structure and function of desmosomes, their morphogenesis has been studied in a primary mouse epidermal (PME) cell culture system. When these cells are grown in approximately 0.1 mM Ca2+, they contain no desmosomes. They are induced to form desmosomes when the Ca2+ level in the culture medium is raised to approximately 1.2 mM Ca2+. PME cells in medium containing low levels of Ca2+, and then processed for indirect immunofluorescence using antibodies directed against desmoplakins (desmosomal plaque proteins), display a pattern of discrete fluorescent spots concentrated mainly in the perinuclear region. Double label immunofluorescence using keratin and desmoplakin antibodies reveals that the desmoplakin-containing spots and the cytoplasmic network of tonofibrils (bundles of intermediate filaments [IFB]) are in the same juxtanuclear region. Within 1 h after the switch to higher levels of Ca2+, the spots move toward the cell surface, primarily to areas of cell-cell contact and not to free cell surfaces. This reorganization occurs at the same time that tonofibrils also move toward cell surfaces in contact with neighboring cells. Once the desmoplakin spots have reached the cell surface, they appear to aggregate to form desmosomes. These immunofluorescence observations have been confirmed by immunogold ultrastructural localization. Preliminary biochemical and immunological studies indicate that desmoplakin appears in whole cell protein extracts and in Triton high salt insoluble residues (i.e., cytoskeletal preparations consisting primarily of IFB) prepared from PME cells maintained in medium containing both low and normal Ca2+ levels. These findings show that certain desmosome components are preformed in the cytoplasm of PME cells. These components undergo a dramatic reorganization, which parallels the changes in IFB redistribution, upon induction of desmosome formation. The reorganization depends upon both the extracellular Ca2+ level and the establishment of cell-to-cell contacts. Furthermore, the data suggests that desmosomes do not act as organizing centers for the elaboration of IFB. Indeed, we postulate that the movement of IFB and preformed desmosomal components to the cell surface is an important initiating event in desmosome morphogenesis.

scholarly journals The Form and Function of PIEZO2

2021 ◽  
Vol 90 (1) ◽  
pp. 507-534
Author(s):  
Marcin Szczot ◽  
Alec R. Nickolls ◽  
Ruby M. Lam ◽  
Alexander T. Chesler
Keyword(s):  
Shear Stress ◽  
Ion Channels ◽  
Molecular Level ◽  
Sensory Biology ◽  
Mechanical Stimuli ◽  
Functional Roles ◽  
Form And Function ◽  
The Past ◽  
And Function ◽  
Sense Of Touch

Mechanosensation is the ability to detect dynamic mechanical stimuli (e.g., pressure, stretch, and shear stress) and is essential for a wide variety of processes, including our sense of touch on the skin. How touch is detected and transduced at the molecular level has proved to be one of the great mysteries of sensory biology. A major breakthrough occurred in 2010 with the discovery of a family of mechanically gated ion channels that were coined PIEZOs. The last 10 years of investigation have provided a wealth of information about the functional roles and mechanisms of these molecules. Here we focus on PIEZO2, one of the two PIEZO proteins found in humans and other mammals. We review how work at the molecular, cellular, and systems levels over the past decade has transformed our understanding of touch and led to unexpected insights into other types of mechanosensation beyond the skin.

scholarly journals Microbiomes In Natura : Importance of Invertebrates in Understanding the Natural Variety of Animal-Microbe Interactions

mSystems ◽  
2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Jillian M. Petersen ◽  
Jay Osvatic
Keyword(s):  
Human Life ◽  
Diverse Range ◽  
Functional Roles ◽  
Form And Function ◽  
Group Interest ◽  
Invertebrate Animals ◽  
Microbe Interactions ◽  
Almost All ◽  
And Function ◽  
Development And Evolution

ABSTRACT Animals evolved in a world teeming with microbes, which play pivotal roles in their health, development, and evolution. Although the overwhelming majority of living animals are invertebrates, the minority of “microbiome” studies focus on this group. Interest in invertebrate-microbe interactions is 2-fold—a range of immune components are conserved across almost all animal (including human) life, and their functional roles may be conserved. Thus, understanding cross talk between microbes and invertebrate animals can lead to insights of broader relevance. Invertebrates offer unique opportunities to “eavesdrop” on intricate host-microbe conversations because they tend to associate with fewer microbes. On the other hand, considering the vast diversity of form and function that has evolved in the invertebrates, they likely evolved an equally diverse range of ways to interact with beneficial microbes. We have investigated only a few of these interactions in detail; thus, there is still great potential for fundamentally new discoveries.

scholarly journals Nuclear actin: to polymerize or not to polymerize

2006 ◽  
Vol 172 (4) ◽  
pp. 495-496 ◽  
Author(s):  
Wilma A. Hofmann ◽  
Primal de Lanerolle
Keyword(s):  
Structural Properties ◽  
Fluorescence Recovery After Photobleaching ◽  
Fluorescence Recovery ◽  
Nuclear Actin ◽  
Functional Roles ◽  
Form And Function ◽  
And Function

The form and function of actin in the nucleus have been enigmatic for over 30 years. Recently actin has been assigned numerous functional roles in the nucleus, but its form remains a mystery. The intricate relationship between actin form and function in the cytoplasm implies that understanding the structural properties of nuclear actin is elementary to fully understanding its function. In this issue, McDonald et al. (p. 541) use fluorescence recovery after photobleaching (FRAP) to tackle the question of whether nuclear actin exists as monomers or polymers.

The Fine Structure of Glycocalyx in Human Spermatozoa. A High Resolution Cytochemical Study

1973 ◽  
Vol 31 ◽  
pp. 640-641
Author(s):  
P. Hernández-Jáuregui ◽  
A. Sosa ◽  
A. González Angulo
Keyword(s):  
Negative Charge ◽  
Iron Hydroxide ◽  
Human Spermatozoa ◽  
Surface Coat ◽  
Cell Surfaces ◽  
Colloidal Iron ◽  
Cytochemical Study ◽  
Specific Permeability ◽  
Extracellular Glycoprotein ◽  
Mammalian Spermatozoa

Glycocalyx is the name given by Bennett to the extracellular glycoprotein coat present in some cell surfaces. It appears to play an important role in cell properties such as antigenicity, cell adhesivity, specific permeability, and ATP ase activity. In the sperm this coat can be directly related to such important phenomena as capacitation and fertilization. The presence of glycocalyx in invertebrate spermatozoa has already been demonstrated. Recently Yanagimachi et al. has determined the negative charges on sperm surfaces of mammalian spermatozoa including man, using colloidal iron hydroxide. No mention was made however of the outer surface coat as composed of substances other than those confering a negative charge. The purpose of this work was therefore to determine the presence of a glycocalyx in human spermatozoa using alcian blue and lanthanum staining.

Scanning tunneling microscopy (STM) of DNA and RNA

1989 ◽  
Vol 47 ◽  
pp. 34-35
Author(s):  
Patricia G. Arscott ◽  
Gil Lee ◽  
Victor A. Bloomfield ◽  
D. Fennell Evans
Keyword(s):  
Molecular Structures ◽  
Inorganic Materials ◽  
Resolving Power ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Form And Function ◽  
Dna And Rna ◽  
Calf Thymus ◽  
And Function ◽  
The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

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