Table 6
-
The
data for artery (A) or vein (V) identity of each active intersegmental vessel
in each of six different wild-type zebrafish embryos on days 2, 3, 4, 5, 6 and
7 post-fertilization. Assignment of artery or vein identity was made based on
two criteria: first, direction of flow of blood cells transiting the segment
and second, whether the segment was connected ventrally to the posterior
cardinal vein or to the dorsal aorta. If blood cells could not be observed
transiting through the segment and/or connection to the dorsal aorta or
posterior cardinal vein could not be verified, vessel identity was recorded as
‘undetermined’ (no entry present). Generally, conclusive determination of
vessel connection could not be made in the absence of blood cell flow. A final
‘definitive’ or ‘composite’ (C) arterial (A) or venous (V) assignment was made
if an intersegmental vessel maintained a solely venous or solely arterial
identity on at least 3 of these days and was otherwise of undetermined
identity, or if the intersegmental maintained its identity from day 4 onwards.
When intersegmental vessels on both right (R) and left (L) sides were
functional at an intersegment, A-V identity of each was determined and listed.
When only one intersegmental was functioning, the particular side that vessel
was present on could not be definitively determined using the microscopic assay
employed, and the vessel position was listed as unknown (?).
Table 7
-
The
definitive or composite vessel identities are listed for each fish in the
Tables S1-S6. Our assignment criteria take into account that intersegmental
vessels initiate circulation asynchronously, even as late as day 4 or even 5,
and that intersegmental vessels also occasionally temporarily stop carrying
blood cell flow altogether, resuming circulation at a later point. Where vessel
identity could be conclusively determined to have switched over the course of
our observations, the entries in these tables are highlighted in pink (this
occurred only five times out of a total of 159 intersegments for which data are
compiled).
Table 8
-
Using
the composite data on A-V identities in these six fish, we performed
nearest-neighbor or next-nearest neighbor analyses to determine the correlation
between vessel identity in spatially juxtaposed intersegments. We determined
the ‘average’ identity of nearby intersegmental vessels in segments immediately
adjacent to intersegmental arteries or intersegmental veins, on one or both
sides of the trunk. This analysis was only performed for those intersegments in
which the identity of ALL neighbors was known. We also determined the ‘average’
identity of vessels in the next-closest adjacent segments. Again, this analysis
was only performed for those intersegments in which the identity of ALL next-nearest
neighbors was known.
Table 9
-
A
statistical analysis of our data set was performed by modeling the stochastic
(random) transitions between consecutive ordered pairs of intersegmental
vessels, i.e., L(k),R(k) to L(k+1),R(k+1) where each L(k),R(k) can be (V, V),
(V, A), (A, V) or (A, A). We combined the data for all six fish. A total of 118
transitions were observed. The table below shows the frequency and number (in
parentheses) of each of the 16 possible transitions between consecutive ordered
pairs. Using log likelihood models, we tested several hypotheses against these
data. A-V identities on the left and right sides of the fish do not appear to
be independent (P=0.002), but there is no evidence of asymmetry
between the left and right sides of the fish (P=0.81). Furthermore, the ordered pairs of vessels at each myoseptal
position cannot be treated as unordered (P=0.004). As the table indicates, there is a strong tendency to make
transitions that preserve the left-right balance of the number of veins and
arteries. For example, the ordered pair (V, A), is 2.5 times more likely to
transition to the reverse (A, V) than to the same (V, A).
