Brain vesicles

Bloomquist JR, Adams PM, Soderiund DM. 1986. Inhibition of gamma-aminobutyric acid-stimulated chloride flux in mouse brain vesicles by polychlorocycloalkane and pyrethroid insecticides. Neurotoxicology 7(3) 11-20. 

Gleitz J, Tosch C, Beile A, Peters T (1996b). The protective action of tetrodotoxin and (+/-)-kavain on anaerobic glycolysis, ATP content, and intracellular Na-i- and Ca2+ of anoxic brain vesicles. Neuropharmacology. 35(12) 1743-52. 

Tuma, P.L., Stachniak, M.C. and CoUins, C.A.J., 1993, Activation ofdynamin GTPaseby acidic phospholipids and endogenous rat brain vesicles. J.Biol.Chem. 268 17240-17246. 

Bloomquist JR, Soderlund DM. 1985. Neurotoxic insecticides inhibit GABA independent chloride uptake by mouse brain vesicles. Biochem Biophys Res Commun 133 37-43. 

The three respective brain vesicles are discernible as they are demarcated by a small notch between the forebrain and midbrain (the forebrain-midbrain junction) and the midbrain and hindbrain (the isthmus) (Fig. 7 brackets). At this time, the fourth ventricle is also present and undergoing expansion over the hindbrain. 

Roseth S, Fonnum F (1995) A study of the uptake of glutamate, gamma-aminobutyric acid (GABA), glycine and beta-alanine in synaptic brain vesicles from fish and avians. Neurosci Lett 183 62-66. 

Figure 1. Concentration-dependent inhibition of GABA-stimulated chloride flux in mouse brain vesicles by four cyclodienes. Redrawn from data in Ref. 15 (endrin, dieldrin) and Ref. 17 (12-ketoendrin, aldrin).

The avermectins have been shown to increase chloride conductance in invertebrate electrophysiological preparations (J, JA,25) and modulate the binding of several GABA receptor-ionophore ligands (9, 10), but the molecular mechanisms underlying their neurotoxicity remain poorly defined. Recently, Abalis e t al. (1 ) reported an avermectin Independent stimulation of chloride uptake in rat brain vesicles tnat... 

Erickson ]D, Eiden LE. Functional identification and molecular cloning of a human brain vesicle monoamine transporter. I Neurochem 1993 61 2314-231 7. 

Hgure 3. Basic structure of the vertebrate central nervous system. The CNS is derived from a hollow structure called the neural tube. It has two orthogonal axes, the circumferential axis and the longidudinal axis. Four distinct domains called the roof, alar, basal, floor plates are generated along the circumferential axis (A). The neural tube can also divided along the longitudinal axis into the spinal cord and the brain, which can be further divided into five brain vesicles, the telencephalon, the diencephalon, the mesencephalon, the metencephalon and the myelencephalon (B). 

Submerge the embryo in PBS, remove the adhering yoUc and cut away the extrae-mbryonic membranes with the ultrafine scissors. If the following analyses depend on the penetration of the embryo by in-situ probes or antibodies, it is advisable to pierce the hollow structures of the embryo, such as brain vesicle and heart, using the ultrafine scissors. 

Excision of brain vesicles from donor and host embryos Equivalent brain vesicles are excised microsurgically in the same way in stage-matched donors and recipients (see Note 17). The dorsal ectoderm is sht precisely at the limit between the nenral tissue and the cephalic mesenchyme on each side of the selected part of the brain. The neural epithehum is loosened from the cephahc mesenchyme, then cut out transversaUy at the chosen rostral and caudal levels, and finally severed from the underlying notochord. 

Exchange of brain vesicles The transfer of brain vesicles from the quail to the chick and vice versa (or from a mutant to a normal chick embryo) is made using a calibrated glass micropipet. The piece of neural tissue is inserted into the groove made by the excision, with the normal rostro-caudal and dorso-ventral orientation, and then adjusted (see Note 18). 

Modifications of the technique consist of orthotopic partial dorsal or dorsolateral grafts of brain vesicles (17,20-22). Heterotopic grafts have also been performed to study specific problems (20,23-25). 

Fig. 3. Scenario of the orthotopic graft of brain vesicles. (A) 12-somite chick embryo in ovo after injection of a solution of Indian ink under the blastoderm. Brain vesicles are well delineated. (B) Longitudinal incisions are made between the cephalic neural tube and the head mesenchyme to delimit the brain excision (arrows). (C) After a transversal section at the level of the mesencephalo-metencephalic constriction, the prosencephalon and the mesencephalon are separated from the head mesoderm and endoderm. The notochord (N) is then visible. (D) The excised chick brain vesicles are discarded. (E) The equivalent quail brain vesicles (Q) are grafted into the chick host. Pro prosencephalon Mes mesencephalon Met metencephalon S12 somite 12. A bar = 0.05 mm B, C, D, E bar = 0.05 mm.

Glass micropipets hand-drawn from Pasteur pipets are curved and calibrated according to use injection of liquids or transfer of pieces of tissues. Calibration of the micropipet according to the size of the rudiment to be transplanted (for instance, neural tube vs brain vesicle) is an important requirement. 

Transplantations of brain vesicles are made at the 12- to 14-somite stages, which are favorable for the following reasons Brain vesicles, still uncovered by the amnion, are clearly demarcated by constrictions in the absence of brain curvature the notochord is no longer strongly adherent to the ventral part of the neural epithelium at this level the neuroepithelium is not yet vascularized. Some neural aest cells and cephalic mesoderm are transferred along with the brain vesicles. Their presence does not interfere with the development of the brain, and presence of melanocytes in the head feathers of the chimera indicates the level of the brain graft. 

---