Biology subjects

Aljiboury, A. A.

Publications and source records attributed to Aljiboury, A. A..

4 recordsLinked to original sources

bioRxiv2022

Rab8-, Rab11-, and Rab35-dependent mechanisms coordinating lumen and cilia formation during Left-Right Organizer development

An essential process during Danio rerios left-right organizer (Kupffers Vesicle, KV) development is for the majority of developing KV cells to form a motile cilium that extend into the KV lumen. Left-right beating of motile cilia within the KV lumen directs fluid flow to establishment the embryos left-right axis. However, when KV cells start to form cilia and how cilia formation is coordinated with KV lumen formation has not been examined. We identified that nascent KV cells form cilia at their centrosomes at random intracellular positions that then move towards a forming apical membrane containing cystic fibrosis transmembrane conductance regulator (CFTR). Using optogenetic clustering approaches, we found that Rab35 positive membranes recruit Rab11 to modulate CFTR delivery to the apical membrane, which is required for lumen opening, and subsequent cilia extension into the lumenal cavity. Once the intracellular cilia reach the CFTR positive apical membrane, Arl13b-positive cilia extend and elongate in a Rab8 dependent manner into the forming lumen once the lumen reaches an area of 300 m2. These studies demonstrate the need to acutely coordinate Rab8, Rab11, and Rab35-mediated membrane trafficking events to ensure appropriate timing in lumen and cilia formation during KV development.

cell biology↗

bioRxiv2022

Pericentriolar matrix integrity relies on cenexin and Polo-Like Kinase (PLK)1

Polo-Like-Kinase (PLK) 1 activity is associated with maintaining the functional and physical properties of the centrosomes pericentriolar matrix (PCM). In this study, we use a multimodal approach of human cells (HeLa) and zebrafish embryos in parallel to phylogenic analysis to test the role of a PLK1 binding protein, cenexin, in regulating the PCM. Our studies identify that cenexin is required for tempering microtubule nucleation and that a conserved C-terminal PLK1 binding site between humans and zebrafish is needed for PCM maintenance through mediating PLK1-dependent substrate phosphorylation events. PCM architecture in cenexin-depleted zebrafish embryos was rescued with wild-type human cenexin, but not with a C-terminal cenexin mutant (S796A) deficient in PLK1 binding. We propose a model where cenexins C-terminus acts in a conserved manner in eukaryotes, excluding nematodes and arthropods, to anchor PLK1 moderating its potential to phosphorylate PCM substrates required for PCM maintenance and function.

cell biology↗

bioRxiv2021

Fitness and mating consequences of variation in male allocation in a wind pollinated plant

In hermaphrodites, the allocation of resources to each sex function can influence fitness through reproductive success and mating success. In wind pollinated plants, sex allocation theory predicts that male fitness increases linearly with investment of resources into male function. However, there have been few empirical tests of this prediction. We experimentally manipulated allocation to male function in Ambrosia artemisiifolia (common ragweed) in a field experiment and measured mating success using genetic assays. We investigated the effects of various morphological traits and flowering phenology on male fitness, and on male and female mate diversity. Our results provide evidence for a linear relation between allocation to male function and fitness. We find earlier onset of male flowering time increases reproductive success, while later onset flowering time increases the probability of mating with diverse individuals. This research is among the first empirical studies testing the prediction of linear male fitness returns in wind pollinated plants. Our results provide insight into the large investment into male function by wind pollinated plants and temporal variation in sex allocation.

evolutionary biology↗

bioRxiv2020

PLK1- and PLK4-mediated asymmetric mitotic centrosome size and positioning in the early zebrafish embryo.

Factors that regulate mitotic spindle positioning have been elucidated in vitro, however it remains unclear how a spindle is placed within the confines of extremely large cells. Our studies identified a uniquely large centrosome structure in the early zebrafish embryo (246.44{+/-}11.93m2 mitotic centrosome in a 126.86{+/-}0.35m diameter cell), whereas C. elegans centrosomes are notably smaller (6.75{+/-}0.28m2 mitotic centrosome in a 55.83{+/-}1.04m diameter cell). During early embryonic cell divisions, cell size changes rapidly in C. elegans and zebrafish embryos. Notably, mitotic centrosome area scales closely with changing cell size compared to changes in spindle length for both organisms. One interesting difference between the two is that mitotic centrosomes are asymmetric in size across embryonic zebrafish spindles, with the larger mitotic centrosome being 2.14{+/-}0.13-fold larger in size than the smaller. The largest mitotic centrosome is placed towards the embryo center in a Polo-Like Kinase (PLK) 1 and PLK4 dependent manner 87.14{+/-}4.16% of the time. We propose a model in which uniquely large centrosomes direct spindle placement within the disproportionately large zebrafish embryo cells to orchestrate cell divisions during early embryogenesis.

cell biology↗