English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background   Volvox carteri  f.  nagariensis  is a model taxon that has been studied extensively at the cellular and molecular level. The most distinctive morphological attribute of  V. carteri  f.  nagariensis  within  V. carteri  is the production of sexual male spheroids with only a 1:1 ratio of somatic cells to sperm packets or androgonidia (sperm packet initials). However, the morphology of male spheroids of  V. carteri  f.  nagariensis  has been examined only in Japanese strains. In addition,  V. carteri  f.  nagariensis  has heterothallic sexuality; male and female sexes are determined by the sex-determining chromosomal region or mating-type locus composed of a > 1 Mbp linear chromosome. Fifteen sex-specific genes and many sex-based divergent shared genes (gametologs) are present within this region. Thus far, such genes have not been identified in natural populations of this species.    Results  During a recent fieldwork in Taiwan, we encountered natural populations of  V. carteri  that had not previously been recorded from Taiwan. In total, 33 strains of this species were established from water samples collected in Northern Taiwan. Based on sequences of the internal transcribed spacer 2 region of nuclear ribosomal DNA and the presence of asexual spheroids with up to 16 gonidia, the species was clearly identified as  V. carteri  f.  nagariensis . However, the sexual male spheroids of the Taiwanese strains generally exhibited a 1:1 to > 50:1 ratio of somatic cells to androgonidia. We also investigated the presence or absence of several sex-specific genes and the sex-based divergent genes  MAT3m ,  MAT3f  and  LEU1Sm . We did not identify recombination or deletion of such genes between the male and female mating-type locus haplotypes in 32 of the 33 strains. In one putative female strain, the female-specific gene  HMG1f  was not amplified by genomic polymerase chain reaction. When sexually induced, apparently normal female sexual spheroids developed in this strain.    Conclusions  Male spheroids are actually variable within  V. carteri  f.  nagariensis.  Therefore, the minimum ratio of somatic cells to androgonidia in male spheroids and the maximum number of gonidia in asexual spheroids may be diagnostic for  V. carteri  f.  nagariensis .  HMG1f  may not be directly related to the formation of female spheroids in this taxon.    Electronic supplementary material  The online version of this article (10.1186/s40529-018-0227-9) contains supplementary material, which is available to authorized users.

Morphology, taxonomy and mating-type loci in natural populations of Volvox carteri in Taiwan