Asymmetry and integration of cellular morphology in Micrasterias compereana

Abstract

BackgroundUnicellular green algae of the genus Micrasterias (Desmidiales) have complex cells with multiple lobes and indentations, and therefore, they are considered model organisms for research on plant cell morphogenesis and variation. Micrasterias cells have a typical biradial symmetric arrangement and multiple terminal lobules. They are composed of two semicells that can be further differentiated into three structural components: the polar lobe and two lateral lobes. Experimental studies suggested that these cellular parts have specific evolutionary patterns and develop independently. In this study, different geometric morphometric methods were used to address whether the semicells of Micrasterias compereana are truly not integrated with regard to the covariation of their shape data. In addition, morphological integration within the semicells was studied to ascertain whether individual lobes constitute distinct units that may be considered as separate modules. In parallel, I sought to determine whether the main components of morphological asymmetry could highlight underlying cytomorphogenetic processes that could indicate preferred directions of variation, canalizing evolutionary changes in cellular morphology.ResultsDifferentiation between opposite semicells constituted the most prominent subset of cellular asymmetry. The second important asymmetric pattern, recovered by the Procrustes ANOVA models, described differentiation between the adjacent lobules within the quadrants. Other asymmetric components proved to be relatively unimportant. Opposite semicells were shown to be completely independent of each other on the basis of the partial least squares analysis analyses. In addition, polar lobes were weakly integrated with adjacent lateral lobes. Conversely, higher covariance levels between the two lateral lobes of the same semicell indicated mutual interconnection and significant integration between these parts.Conclusions Micrasterias cells are composed of several successively disintegrated parts. These integration patterns concurred with presumed scenarios of morphological evolution within the lineage. In addition, asymmetric differentiation in the shape of the lobules involves two major patterns: asymmetry across the isthmus axis and among the adjacent lobules. Notably, asymmetry among the adjacent lobules may be related to evolutionary differentiation among species, but it may also point out developmental instability related to environmental factors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0855-1) contains supplementary material, which is available to authorized users.

Review of the tribe Chilocorini Mulsant from Iran (Coleoptera, Coccinellidae)

“…Although various scale insects are primary hosts of Chilocorus (Escalona et al 2017), some species at least accept aphids as prey (Gordon 1985, Drea and Gordon 1990, Ślipiński 2007, Hodek and Honěk 2009). Nonetheless, there are some reports about some species of this genus, such as Chilocorus stigma (Say) which feed on some whitefly species, such as Aleurocanthus woglumi Ashby (Dowell and Cherry 1981, Hodek and Honěk 2009).…”

“…It is divided into two subfamilies: Microweiseinae and Coccinellinae. The subfamily Microweiseinae includes three tribes: Carinodulini, Microweiseini (including Sukunahikonini) and Serangiini (Escalona and Ślipiński 2012); the remaining taxa belong to the subfamily Coccinellinae (Seago et al 2011, Robertson et al 2015, Szawaryn et al 2015, Escalona et al 2017). …”

“…Although most members of Chilocorini are coccidophagous (Giorgi et al 2009, Escalona et al 2017), aphidophagy is also present in some species (Ślipiński and Giorgi 2006); so, the members of this tribe have the potential to be effective biological control agents of coccids and aphids (Drea and Gordon 1990, Ponsonby and Copland 1997). …”

Peer Review #2 of "Gynodioecy in the common spindle tree (Euonymus europaeus L.) involves differences in the asymmetry of corolla shapes between sexually differentiated flowers (v0.1)"

“…These transformations correspond to (1) identity, (2) reflections across horizontal and (3) vertical axes of symmetry (Fig. 2), and (4) reflection across both of these axes (Savriama et al, 2010;Savriama & Klingenberg, 2011;Klingenberg, 2015;Neustupa, 2017;Savriama, 2018). Note that the symmetry transformations no.…”

“…Manuscript to be reviewed variation from the midpoint represented by the ideally symmetric consensus configuration (Neustupa, 2017). Relative amounts of individual subspaces can be quantified by summing the variation spanned by PCs belonging to each of these subsets (Savriama, 2018).…”