Structure and morphogenesis of the eggshell and micropylar apparatus in the olive fly, Dacus oleae (Diptera: Tephritidae)

The egg of the olive fly, Dacus oleae (Diptera, Tephritidae), is laid inside olives and the larva eventually destroys the fruit. The oocyte is surrounded by several distinct layers which are produced during choriogenesis. The chorion covering the main body of the egg outside of the vitelline membrane includes a "wax" layer, an innermost chorionic layer, an endochorion consisting of inner and outer layers separated by pillars and cavities similar to their counterparts in Drosophila melanogaster, as well as inner and outer exochorionic layers. The anterior pole is shaped like an inverted cup, which is chiefly hollow around its base and has very large openings communicating with the environment. Holes through the surface of the endochorion result from deposition of endochorionic substance around follicular cell microvilli. An opening at the apex of the cup provides an entrance for sperm entering the micropylar canal, which traverses the endochorion and continues into a "pocket" in a thickened vitelline protrusion. The micropylar canal is formed by deposition of endochorion and vitelline membrane around an elongated pair of follicular cell extensions. These extensions later degenerate and leave an empty canal about 5 microns in diameter and the narrower pocket about 1 micron in diameter. Respiration is thought to be facilitated by openings at the base of the anterior pole as well as by openings through the "plastron" around the main body of the shell.     

Production and characterization of gamma-polyglutamic acid nanoparticles for controlled anticancer drug release

Gamma-polyglutamic acid (gamma-PGA) is a hydrophilic, biodegradable, and naturally available biopolymer produced by a number of microbial species, most commonly, the Bacillaceae family. Its biological properties such as nontoxicity, biocompatibility, and nonimmunogenicity qualify it as an important biomaterial in drug delivery applications. This review focuses mainly on the development of gamma-PGA nanoparticles as drug delivery carriers for anticancer therapeutics. We discuss various techniques for the production and characterization of gamma-PGA nanoparticles and controlled-release strategies. We also present a brief overview of the tumor physiology that forms the basis for the development of various targeted drug delivery approaches in cancer chemotherapy.     

Proteolytic cleavage of pertussis toxin S1 subunit is not essential for its activity in mammalian cells

Background  

Pertussis toxin (PT) is an exotoxin virulence factor produced by Bordetella pertussis, the causative agent of whooping cough. PT consists of an active subunit (S1) that ADP-ribosylates the alpha subunit of several mammalian G proteins, and a B oligomer (S2–S5) that binds glycoconjugate receptors on cells. PT appears to enter cells by endocytosis, and retrograde transport through the Golgi apparatus may be important for its cytotoxicity. A previous study demonstrated that proteolytic processing of S1 occurs after PT enters mammalian cells. We sought to determine whether this proteolytic processing of S1 is necessary for PT cytotoxicity.     

Structural and biochemical analysis of the Leptinotarsa decemlineata (Coleoptera; Chrysomeloidea) crystalline chorionic layer

The developmental aspects of the Leptinotarsa decemlineata crystalline chorionic layer (CCL) morphogenesis, its composition and its supramolecular structure were studied. The mature Leptinotarsa decemlineata eggshell consists of the vitelline membrane and the CCL, while the follicle cell remnants following their degeneration after oogenesis completion constitute the outer chorionic layer. The vitelline membrane and the CCL layers are formed through continuous material deposition from the follicular epithelium, whereas the main morphogenic factor during most insect eggshell formation, namely the follicle cell and oocyte microvilli, are seemingly involved only in vitelline membrane formation. Analysis of the CCL morphogenesis showed that this layer is assembled from a fiber-like pre-crystalline material, which accumulates at the vitelline membrane-follicle cell interface. The mature CCL is about 1 microm thick and exhibits a periodicity of approximately 10 nm, while computer image analysis studies of thin-sectioned CCL revealed the existence of crystalline layers parallel to the CCL surface. Finally, SDS-PAGE-electrophoresis of purified CCLs showed that this crystalline layer is of a proteinaceous nature and is most likely composed of 3-5 polypeptides with a molecular weight ranging in between 28-60 kDa. Overall, these data exemplify for the first time the nature and supramolecular arrangement of a crystalline layer and its constituent molecules in Coleoptera.     

Rheology,oxygen transfer,and molecular weight characteristics of poly(glutamic acid) fermentation by Bacillus subtilis

Poly(glutamic acid) (PGA) is a water-soluble, biodegradable biopolymer that is produced by microbial fermentation. Recent research has shown that PGA can be used in drug delivery applications for the controlled release of paclitaxel (Taxol) in cancer treatment. A fundamental understanding of the key fermentation parameters is necessary to optimize the production and molecular weight characteristics of poly(glutamic acid) by Bacillus subtilis for paclitaxel and other applications of pharmaceuticals for controlled release. Because of its high molecular weight, PGA fermentation broths exhibit non-Newtonian rheology. In this article we present experimental results on the batch fermentation kinetics of PGA production, mass transfer of oxygen, specific oxygen uptake rate, broth rheology, and molecular weight characterization of the PGA biopolymer.