Photopolarization of Fucus zygotes is determined by time sensitive vectorial addition of environmental cues during axis amplification
نویسندگان
چکیده
Fucoid zygotes have been extensively used to study cell polarization and asymmetrical cell division. Fertilized eggs are responsive to different environmental cues (e.g., light, gravity) for a long period before the polarity is fixed and the cells germinate accordingly. First, it is commonly believed that the direction and sense of the polarization vector are established simultaneously as indicated by the formation of an F-actin patch. Secondly, upon reorientation of the zygote, a new polar gradient is formed and it is assumed that the position of the future rhizoid pole is only influenced by the latter. Here we tested these two hypotheses investigating photopolarization in Fucus zygotes by reorienting zygotes 90° relative to a unilateral light source at different time points during the first cell cycle. We conclude that fixation of direction and sense of the polarization vector is indeed established simultaneously. However, the experiments yielded a distribution of polarization axes that cannot be explained if only the last environmental cue is supposed to determine the polarization axis. We conclude that our observations, together with published findings, can only be explained by assuming imprinting of the different polarization vectors and their integration as a vectorial sum at the moment of axis fixation. This way cells will average different serially perceived cues resulting in a polarization vector representative of the dynamic intertidal environment, instead of betting exclusively on the perceived vector at the moment of axis fixation.
منابع مشابه
Cytoplasmic calcium gradients and calmodulin in the early development of the fucoid alga Pelvetia compressa.
The predicted existence of cytoplasmic Ca2+ gradients during the photopolarization of the zygotes of the brown algae, Pelvetia and Fucus, has proved to be difficult to establish, and the downstream targets of the putative gradients are not known. We have used quantitative microinjection of the long excitation wavelength Ca2+ indicator, Calcium Crimson, and of antibodies against calmodulin to in...
متن کاملF-actin marks the rhizoid pole in living Pelvetia compressa zygotes.
Spatial and temporal changes in F-actin during polarity establishment in Pelvetia compressa zygotes were investigated using vital staining with rhodamine phalloidin (RP). F-actin was localized to a patch in the cortex of young zygotes. When unilateral light was applied to induce a growth axis (photopolarization) in a population of zygotes, the cortical F-actin patches localized at the shaded po...
متن کاملCortical actin filaments form rapidly during photopolarization and are required for the development of calcium gradients in Pelvetia compressa zygotes.
Previous research has shown that cortical gradients of cytosolic Ca(2+) are formed during the photopolarization of Pelvetia compressa zygotes, with elevated Ca(2+) on the shaded hemisphere that will become the site of rhizoid germination. We report here that the marine sponge toxin, latrunculin B, which blocks photopolarization at nanomolar concentrations, inhibited the formation of the light-d...
متن کاملSpatial re-organisation of cortical microtubules in vivo during polarisation and asymmetric division of Fucus zygotes.
Fucus zygotes polarise and germinate a rhizoid before their first asymmetrical division. The role of microtubules (MTs) in orienting the first division plane has been extensively studied by immunofluorescence approaches. In the present study, the re-organisation of MT arrays during the development of Fucus zygotes and embryos was followed in vivo after microinjection of fluorescent tubulin. A d...
متن کاملCytochalasin treatment disrupts the endogenous currents associated with cell polarization in fucoid zygotes: studies of the role of F-actin in embryogenesis
We determined the distribution of F-actin in fucoid (Pelvetia, Fucus) embryos with nitrobenzoxadiazole-phallacidin, and studied the effect of cytochalasin upon the endogenous currents associated with cell polarization by using the vibrating probe. F-actin is not localized at the presumptive rhizoid immediately after experimental induction of the polar axis with a light gradient; however, a pref...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره 6 شماره
صفحات -
تاریخ انتشار 2015