Komaki, S. | Search bioRxiv

bioRxiv2018

Live cell imaging of meiosis in Arabidopsis thaliana - a landmark system

Meiosis is essential for sexual reproduction and key to the generation of genetic diversity. To reveal the robustness of meiocyte differentiation and progression through meiosis, we have here established a live cell imaging setup to follow the dynamics of individual male meiocytes in Arabidopsis. Our method is based on the concomitant visualization of microtubules and a meiotic cohesion subunit that allowed following five cellular parameters: cell shape, nucleus position, nucleolus position, chromatin condensation and microtubule array. We find that the states of these parameters are not randomly associated and identify 11 states, referred to as landmarks, that occur much more frequently than closely related states, indicating that they are convergent points of meiotic progression. With this, the here-presented landmark system represents a novel method to analyze meiosis not only allowing a high-temporal dissection but also providing new criteria to evaluate mutants or environmental effects on meiosis.

cell biology↗

bioRxiv2017

The widespread misconception about the Japanese major biogeographic boundary, the Watase line (Tokara gap), revealed by bibliographic and beta diversity analyses

The biota of the Japanese Archipelago is divided into the Palearctic and Oriental realms by the Watase line (Tokara gap), a major biogeographic boundary of Japan. This boundary is generally placed between Akusekijima and Kodakarajima Islands of the Tokara Archipelago, and has been the subject of many biogeographic debates. However, despite being widely accepted, the position of the boundary is doubtful because of a lack of clear evidence. Here, to verify the definition and existence of the biogeographic boundary, we performed a documentary search and beta diversity analysis of multiple taxa. Our documentary search suggested that the Watase line (Tokara gap) should be put between Yakushima/Tanegashima and Amamioshima Islands, but recent references to it clearly deviate from its original definition, and that the placement of the boundary line between Akusekijima and Kodakarajima Islands is based on limited and biased evidence. Our beta diversity analyses found no common biogeographic boundary dividing the Tokara Archipelago into two realms, and showed that the beta diversity pattern of this region is explained by the areas and geographic distances of the islands in agreement with the general principles of island biogeography. The widespread misunderstanding of biogeography in this region could have been perpetuated by preconception and the citation of references without verification. Our study proposes that revision of the biogeography in the Tokara Archipelago, a gap region between the Palearctic and Oriental realms, is necessary and demonstrates the negative influence of preconception in biogeographic debate.

ecology↗