Article Figures & Tables
Figures
- Fig. 1.
Larval and adult heart contractions in Anopheles gambiae. (A) Larval restraint technique for brightfield intravital video recording of heart contractions. Larvae were restrained in water that was pooled between two stacks of coverslips. (B) Brightfield image of the larval abdomen showing that the heart (arrowheads) is located between the dorsal longitudinal tracheal trunks (arrows). (C) Graphical representation of larval heart contractions, where each peak represents a contraction. Contractions from the middle third of the 60 s recording are magnified in the lower graph. All larval contractions propagate in the anterograde direction. (D) Adult restraint technique for brightfield intravital video recording of heart contractions. Adults were cold-anesthetized and pins were placed through non-vascular portions of the wings and over the neck. (E) Brightfield image of the adult abdomen showing the heart (arrowheads). (F) Graphical representation of adult heart contractions, where each peak represents a heart contraction. Contractions from the middle third of the 60 s recording are magnified in the lower graph. Unshaded and shaded areas represent periods of anterograde and retrograde heart contraction, respectively.
- Fig. 2.
Larval and adult heart contraction rates. Heart contraction rates were quantified in larvae and adults after receiving no treatment (naïve), a needle wound (injury), an injection with PBS, or an injection with 2 μm fluorescent microspheres in PBS. Across all comparisons, larvae displayed lower heart rates than adults (two-way ANOVA, P<0.0001), but treatment did not affect heart rates (P=0.6725). Whiskers denote the s.e.m.
- Fig. 3.
Larval and adult hemolymph flow velocity. (A) Diagrammatic representation (dorsal view; anterior on top) of intracardiac hemolymph flow in larvae (left) and the adult abdomen (middle and right). Hemolymph inside the larval heart is only propelled in the anterograde direction (AG; red arrow) whereas hemolymph is propelled across the adult heart in both anterograde (red arrow) and retrograde (RG; blue arrow) directions. (B) Diagrammatic representation (ventral view) of extracardiac hemolymph flow in the larval ventral abdomen, showing that hemolymph only moves in the retrograde direction (blue arrows). (C) Hemolymph velocity in the heart of larvae and adults, as determined by the tracking of neutral density fluorescent microspheres. Intracardiac (anterograde) hemolymph in larvae travels significantly more slowly than intracardiac (anterograde and retrograde) hemolymph in adults. (D) Extracardiac retrograde hemolymph flow in the ventral abdomen of larvae. In larvae, extracardiac flow is significantly slower than intracardiac flow. For box plots, the center line marks the median, the box marks 50% of the data, and the whiskers mark 90% of the data.
- Fig. 4.
Larval and adult heart structure. All images are fluorescence micrographs of specimens treated with Alexa Fluor conjugated phalloidin, which labels muscles green. (A) Image of the larval dorsal thorax and abdomen showing that the dorsal vessel extends the length of the body along the dorsal midline and is subdivided into an abdominal heart (arrows) and a thoracic aorta (arrowheads). The dashed line delineates the thoraco-abdominal junction. (B) A portion of the larval abdomen illustrated in panel A, magnified to show the heart (arrows) and associated alary muscles (e.g. arrowheads). The larval heart is flanked on either side by large swim muscles that approach the heart at ~45 deg angles. (C) High magnification view of two segments of the larval heart (arrows) showing the spiral arrangement of cardiomyocytes, the dorsal longitudinal tracheal trunks (T) and the alary muscles (arrowheads). Also visible along the surface of the heart are numerous pericardial cells. (D) Adult dorsal abdomen showing the heart (arrows), which runs the length of the abdomen along the dorsal midline. (E) A portion of the adult abdomen magnified to show the heart (arrows) and the extensive alary muscles (arrowheads). All images are oriented with anterior on top. Scale bars: A and D, 500 μm; B and E, 200 μm; C, 100 μm.
- Fig. 5.
Larval and adult abdominal ostia. Phalloidin stained larval (A–C) and adult (D–F) hearts showing the location and structure of the ostia. (A) Larval ostia (arrows) are located on the lateral sides of the heart in between and dorsal to a pair of enlarged pericardial cells (arrowheads). (B) Ostia (arrows) are oriented towards the anterior of the organism as they extend into the lumen of the vessel. (C) Each ostium (arrows) is composed of a pair of cardiomyocytes (nuclei are labelled blue with Hoechst 33342; circles). (D) Adult ostia (arrows) are located on the lateral sides of the heart near the posterior of each alary muscle pair. Pericardial cells are present but are not labelled. (E) Ostia (arrows) are oriented towards the anterior of the organism as they extend into the lumen of the vessel. (F) Each ostium is composed of two cardiomyocytes (nuclei are labelled blue; circles). Note how the ostia extend into the lumen of the vessel (arrows). All images are oriented with anterior at the top, and the abdominal sutures are marked with a dashed line. Scale bars: A and D, 50 μm; B, C, E and F, 50 μm.
- Fig. 6.
Larval hemolymph flow patterns and entry through the eighth abdominal segment incurrent openings of the heart. Diagrammatic representation (lateral view) of hemolymph flow in larvae. Hemolymph enters the dorsal vessel (green) at the posterior terminus of the heart in the eighth abdominal segment and travels rapidly in the anterograde direction (red arrow) before exiting the aorta near the head. After exiting the aorta, hemolymph flows slowly in the extracardiac hemocoel in the retrograde direction (blue arrows) and then re-enters the dorsal vessel via a pair of incurrent openings at the posterior terminus of the heart. This diagrammatic representation was constructed after visualizing the movement of fluorescent microspheres that had been injected into the hemocoel. The bottom of the image displays the percentage of microspheres that enter the heart through the ostia and the percentage of microspheres that enter the heart through the incurrent openings located at the posterior terminus of the heart (Wilcoxon matched pairs test, P<0.0001). The ostia and incurrent openings are labelled with continuous arrows and the thoraco-abdominal ostia are labelled with a dashed arrow.
- Fig. 7.
Larval and adult posterior heart structure. (A–C) Image series showing, in increasing magnification, phalloidin staining of the larval posterior incurrent openings of the heart. The posterior terminus of the larval heart ends in the anterior portion of the eighth abdominal segment, lies between the dorsal longitudinal tracheal trunks (T), and is supported by two incomplete pairs of alary muscles (white arrowheads). The posterior terminus of the larval heart contains two incurrent openings (arrows) that contain a muscular tether (yellow arrowhead) that attaches the heart to the abdominal wall. (D–F) Series of fluorescence (D,E) and brightfield (F; same specimen as E) images showing that the posterior terminus of the larval heart is also attached to an extensive network of thin tracheoles called the tracheal tufts (TT), which extend from a location near the posterior base of the dorsal longitudinal tracheal trunks (T). (G–I) Image series showing, in increasing magnification, phalloidin staining of the adult posterior excurrent openings of the heart. The posterior terminus of the adult heart ends in the anterior portion of the eighth abdominal segment and is supported by two incomplete pairs of alary muscles (white arrowheads). The posterior terminus of the adult heart contains two excurrent openings (arrows) that contain a muscular tether (yellow arrowhead) that attaches the heart to the abdominal wall. All images are oriented with anterior at the top. Scale bars: A, D and G, 100 μm; B, E, F and H, 50 μm; C and I, 20 μm.
- Fig. 8.
Larval aorta structure. (A) Phalloidin staining of muscle showing the anterior portion of the abdominal heart (arrows), the thoraco-abdominal junction (dashed line), the ostial pair at this junction (circles), the dorsal longitudinal tracheal trunks (T), the thoracic aorta (arrowheads), prominent trachea that attach to the aorta (yellow arrows), and the bulbous chamber of the aorta (yellow arrowhead). (B–D) Series of images showing the anterior bulbous chamber of the aorta. (B) The aorta forms a dense neck region posterior to the bulbous chamber (arrow), which widens significantly into a bulbous chamber before narrowing once again into a thin muscular siphon (arrowhead), where hemolymph passes through prior to emptying into the head. (C,D) The aorta, depending on the contraction state of the heart, varies greatly in shape, widening in response to a heart contraction (C) and narrowing during relaxation (D). (E–G) Series of images showing the structure of the thoraco-abdominal junction. (E) The diamond-shaped thoraco-abdominal junction displays a knot-like arrangement of cardiomyocytes in both left- and right-handed helical orientations and contains two ostia (circles). (F) The regular left-handed helical arrangement of heart cardiomyocytes (bottom arrow) differs from the irregular arrangement of both left- and right-handed helices in aorta cardiomyocytes (top arrow). The ostia at the thoraco-abdominal junction can be seen as invaginations (circles) in the cardiac muscle. (G) Each ostium at the thoraco-abdominal junction contains paired cardiomyocyte nuclei (blue; circles) that lie at the periphery of the heart lumen. All images are oriented with anterior at the top. Scale bars: A, 100 μm; B–G, 50 μm.
Article navigation
Related articles
Cited by...
More in this TOC section
Similar articles
Other journals from The Company of Biologists
Predicting the Future: Species Survival in a Changing World
Read our new special issue exploring the significant role of experimental biology in assessing and predicting the susceptibility or resilience of species to future, human-induced environmental change.
Big Biology Podcast - Hollie Putnam and coral bleaching
Catch the next JEB-sponsored episode of the Big Biology Podcast where Art and Marty talk to Hollie Putnam about the causes of coral bleaching and the basic biology of corals in the hope of selectively breeding corals that can better tolerate future ocean conditions.
Read Hollie's Review on the subject, which is featured in our current special issue.
Stark trade-offs and elegant solutions in arthropod visual systems
Many elegant eye specializations that evolved in response to visual challenges continue to be discovered. A new Review by Meece et al. summarises exciting solutions evolved by insects and other arthropods in response to specific visual challenges.
Head bobbing gives pigeons a sense of perspective
Pigeons might look goofy with their head-bobbing walk, but it turns out that the ungainly head manoeuvre allows the birds to judge distance.