Basic Structure and Function of Mites

2011 ◽  
pp. 13-34
2011 ◽  
Vol 1808 (2) ◽  
pp. 580-588 ◽  
Author(s):  
Gerhard Thiel ◽  
Dirk Baumeister ◽  
Indra Schroeder ◽  
Stefan M. Kast ◽  
James L. Van Etten ◽  
...  

1995 ◽  
Vol 7 (4) ◽  
pp. 847 ◽  
Author(s):  
C Gagnon

With very few exceptions, the basic structure of the 9+2 axoneme has been well preserved over a very long period of evolution from protozoa to mammais. This stability indicates that the basic structural components of the axoneme visible by electron microscopy, as well as most of the other unidentified components, have withstood the passage of time. It also means that components of the 9+2 axoneme have sufficient diversity in function to accommodate the various types of motility patterns encountered in different species of flagella. Several of the 200 polypeptides that constitute the axoneme have been identified as components of the dynein arms, radial spokes etc. but many more remain to be identified and their function(s) remain to be determined. Because this review deals with the regulation of flagellar movement at the axonemal level, it does not include regulation of flagella by extracellular factors unless these factors have a direct action on axonemal components. In this context, it is very important firstly to understand the structural components of the axoneme and how they influence and regulate axonemal movement. Different primitive organisms are mentioned in this review since major breakthroughs in our understanding of how an axoneme generates different types of movement have been made through their study. Despite some variations in structure and function of axonemal components, the basic mechanisms involved in the regulation of flagella from Chlamydomonas or sea urchin spermatozoa should also apply to the more evolved mammalian species, including human spermatozoa.


2007 ◽  
Vol 293 (5) ◽  
pp. H2667-H2679 ◽  
Author(s):  
Charlotte Hwa ◽  
William C. Aird

In 1628, William Harvey provided definitive evidence that blood circulates. The notion that blood travels around the body in a circle raised the important question of how nutrients pass between blood and underlying tissue. Perhaps, Harvey posited, arterial blood pours into the flesh as into a sponge, only then to find its way into the veins. Far from solving this problem, Marcello Malpighi's discovery of the capillaries in 1661 only added to the dilemma: surely, some argued, these entities are little more than channels drilled into tissues around them. As we discuss in this review, it would take over 200 years to arrive at a consensus on the basic structure and function of the capillary wall. A consideration of the history of this period provides interesting insights into not only the central importance of the capillary as a focus of investigation, but also the enormous challenges associated with studying these elusive structures.


2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Toshio Takahashi ◽  
Masayuki Hatta

The peptide-signaling molecules (<50 amino acid residues) occur in a wide variety of invertebrate and vertebrate organisms, playing pivotal roles in physiological, endocrine, and developmental processes. While some of these peptides display similar structures in mammals and invertebrates, others differ with respect to their structure and function in a species-specific manner. Such a conservation of basic structure and function implies that many peptide-signaling molecules arose very early in the evolutionary history of some taxa, while species-specific characteristics led us to suggest that they also acquire the ability to evolve in response to specific environmental conditions. In this paper, we describe GLWamide-family peptides that function as signaling molecules in the process of muscle contraction, metamorphosis, and settlement in cnidarians. The peptides are produced by neurons and are therefore referred to as neuropeptides. We discuss the importance of the neuropeptides in both developmental and physiological processes in a subset of hydrozoans, as well as the potential use as a seed compound in drug development and aspects related to the protection of corals.


2014 ◽  
pp. 1134-1144 ◽  
Author(s):  
J.S. Barbieri ◽  
K. Wanat ◽  
J. Seykora

2007 ◽  
Vol 127 (11) ◽  
pp. 2516-2524 ◽  
Author(s):  
Gülistan Meşe ◽  
Gabriele Richard ◽  
Thomas W. White

2007 ◽  
Vol 5 ◽  
pp. 27-54 ◽  
Author(s):  
Jerry T. Ball

A bi-polar theory of the structure and function of nominals and clauses is presented in which a specifier, functioning as a referential pole, and a head, functioning as a relational pole, combine to form a referring expression. The theory applies to both object referring expressions, in the case of nominals, and situation referring expressions, in the case of clauses. The bi-polar theory is contrasted with X-Bar Theory — a uni-polar theory in which the head uniquely determines the type of the larger expression in which it occurs. Uni-polar theories adopt a strong notion of endocentricity, which is rejected in the bi-polar theory, where both the specifier and the head make significant and meaningful contributions to the larger expressions in which they occur. The bi-polar theory is also contrasted with Langacker’s conception of the basic structure and function of nominals and clauses.


Sign in / Sign up

Export Citation Format

Share Document