QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online July 2, 2004
Journal of Experimental Biology 207, 2835-2844 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01089

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bjornsson, C. S. Articles by Huebner, E. Search for Related Content PubMed PubMed Citation Articles by Bjornsson, C. S. Articles by Huebner, E.

Extracellular H⁺ dynamics during oogenesis in Rhodnius prolixus ovarioles

C. S. Bjornsson¹ and E. Huebner^2,*

¹ Laboratory of Nervous System Disorders, Wadsworth Center, Albany, NY 12201-0509, USA
² Department of Zoology, University of Manitoba, Winnipeg, MB, Canada R3T 2N2

View larger version (142K): [in a new window]   Fig. 1. An illustration depicting the positions along adult ovarioles of different stages measured during a scan. As the connective stalk (see stage 4) and the anterior region of the T and T-1 follicle (stages 8–9) became more complex, additional points were introduced to include measurements of these dynamic and potentially interesting regions.

View larger version (137K): [in a new window]   Fig. 2. Examples of H+ influx and efflux. 2-D vectors were calculated from measurements taken near the ovariole and 10 µm away in the x- and y-axis, and superimposed over an image of the ovariole. Vectors were classified as influx if the vector traveled over the ovariole image (left), or as efflux if the vector traveled away from the ovariole (right). Ion concentration gradients are shown as red gradients representing influx (left) or efflux (right).

View larger version (78K): [in a new window]   Fig. 3. Mean extracellular H+ fluxes along adult Rhodnius ovarioles. (A) H+ flux magnitude and direction (influx/efflux) relative to position along ovariole and ovariole stage (N=10–18, shown in parentheses). The data for each ovariole stage, represented by fluctuating black lines running through the coloured region of the plot, are superimposed on each other making it difficult to show stage differences. However these are clearly discerned in a top view as seen in (B). The colour coding indicates H+ flux magnitude and direction, which is calibrated in B. Each vertical column on the surface plot corresponds to a specific point along the ovariole as indicated by the ovariole images. The leftmost column displays background noise. Horizontal rows display the average H+ flux for each ovariole stage (see Materials and methods). Prominent efflux occurs near the interfollicular stalks on either side of the T follicle. H+ efflux at the anterior stalk is greatest around stage 4 (early vitellogenesis) and declines gradually until stage 8 (late vitellogenesis) when it is significantly diminished. Stage-8 ovarioles were also characterized by the appearance of H+ influx along the anterior columnar epithelium of the T follicle.

View larger version (98K): [in a new window]   Fig. 4. Light micrograph of a stage-9 ovariole with corresponding extracellular H+ fluxes superimposed. H+ flux is indicated by red vectors, with length proportional to the flux magnitude. Vector angles are the result of summing x- and y-axis measurements. Vectors traveling away from the ovariole surface represent H+ efflux; vectors traveling over the ovariole are influx. The noise measurement is in the bottom left corner. Of interest is the H+ efflux near the forming chorion rim in late vitellogenic oocytes (asterisk), which remains throughout choriogenesis. Red scale bar, 100 fmol cm–2 s–1; black scale bar, 100 µm.

View larger version (122K): [in a new window]   Fig. 5. Light micrograph of a recently ovulated follicle with corresponding extracellular H+ fluxes superimposed. The chorionated oocyte was loosely contained by the follicular epithelium, and fell away from the ovariole during dissection. H+ efflux in the region of the rim is still present after ovulation (asterisk), suggesting follicle cells generate this H+ flux. Red scale bar, 100 fmol cm–2 s–1; black scale bar, 100 µm.

View larger version (142K): [in a new window]   Fig. 6. Light micrograph of the anterior portion of a T-1 follicle from a stage-9 ovariole with corresponding extracellular H+ fluxes superimposed. Additional measurements near the H+ efflux along the T-1/T-2 junction reveal that the efflux extends to the anterior pole of the T-1 follicle (asterisk). These follicle cells presumably are also involved in interfollicular stalk morphogenesis, and will ultimately form the columnar cells at the anterior pole of the follicle. Red scale bar, 100 fmol cm–2 s–1; black scale bar, 100 µm.

View larger version (98K): [in a new window]   Fig. 7. Light micrograph of a longitudinal section through the interfollicular stalk separating T-1 (top) and T follicle (bottom). The ovariole sheath is still intact. The three positions measured along the stalk are shown as red dots, from anterior (top) to posterior (bottom). Two groups of cells are present near the posterior stalk position: the stalk cells which are not dye-coupled to either adjacent follicle (a), and follicle cells which are coupled to the T oocyte (b). Semi-thin section stained with 1% Toluidine Blue in 1% Borax. Scale bar, 20 µm.