Mutants of Volvox carteri affecting nitrogen assimilation

Huskey, Robert J.; Semenkovich, Clay F.; Griffin, Barbara E.; Cecil, Patricia O.; Callahan, Ann M.; Chace, Kenneth V.; Kirk, David L.

doi:10.1007/bf00271666

Cited by 21 publications

(7 citation statements)

References 22 publications

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“…The wild‐type Volvox carteri f. nagariensis strain Eve10 (female) (Starr, ; Starr, ; Adams et al , ; Kianianmomeni et al , ), which originates from Japan, was used to produce a nitrate‐reductase deficient ( nit A − ) descendant for transformation experiments. The nitA − descendant of Eve10 was generated by random mutagenesis and chlorate selection as previously described (Huskey et al , ; Harper et al , ; Adams et al , ). The obtained non‐revertible mutant strain, TNit‐1013 (Tian et al , ), contains a deletion of 1013 bp in the nit A gene and, therefore, is not able to grow in medium containing nitrate as the sole source of nitrogen.…”

Section: Methodsmentioning

confidence: 99%

Babo1, formerly Vop1 and Cop1/2, is no eyespot photoreceptor but a basal body protein illuminating cell division in Volvox carteri

Heyde

Hallmann

2020

The Plant Journal

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In photosynthetic organisms many processes are light dependent and sensing of light requires light-sensitive proteins. The supposed eyespot photoreceptor protein Babo1 (formerly Vop1) has previously been classified as an opsin due to the capacity for binding retinal. Here, we analyze Babo1 and provide evidence that it is no opsin. Due to the localization at the basal bodies, the former Vop1 and Cop1/2 proteins were renamed V.c. Babo1 and C.r. Babo1. We reveal a large family of more than 60 Babo1-related proteins from a wide range of species. The detailed subcellular localization of fluorescence-tagged Babo1 shows that it accumulates at the basal apparatus. More precisely, it is located predominantly at the basal bodies and to a lesser extent at the four strands of rootlet microtubules. We trace Babo1 during basal body separation and cell division. Dynamic structural rearrangements of Babo1 particularly occur right before the first cell division. In four-celled embryos Babo1 was exclusively found at the oldest basal bodies of the embryo and on the corresponding d-roots. The unequal distribution of Babo1 in four-celled embryos could be an integral part of a geometrical system in early embryogenesis, which establishes the anterior-posterior polarity and influences the spatial arrangement of all embryonic structures and characteristics. Due to its retinal-binding capacity, Babo1 could also be responsible for the unequal distribution of retinoids, knowing that such concentration gradients of retinoids can be essential for the correct patterning during embryogenesis of more complex organisms. Thus, our findings push the Babo1 research in another direction.

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Section: Methodsmentioning

confidence: 99%

Babo1, formerly Vop1 and Cop1/2, is no eyespot photoreceptor but a basal body protein illuminating cell division in Volvox carteri

Heyde

Hallmann

2020

The Plant Journal

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“…The wild-type Volvox carteri f. nagariensis strain Eve10 (female) originates from Japan and has been described earlier [ 51 – 53 ]. A nitrate reductase-deficient ( nit A − ) descendant of this strain was generated by random mutagenesis and chlorate selection as previously described [ 54 , 55 ]. This non-revertible mutant strain, TNit-1013, was used as a target in transformation experiments.…”

Section: Methodsmentioning

confidence: 99%

Two-component cyclase opsins of green algae are ATP-dependent and light-inhibited guanylyl cyclases

et al. 2018

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BackgroundThe green algae Chlamydomonas reinhardtii and Volvox carteri are important models for studying light perception and response, expressing many different photoreceptors. More than 10 opsins were reported in C. reinhardtii, yet only two—the channelrhodopsins—were functionally characterized. Characterization of new opsins would help to understand the green algae photobiology and to develop new tools for optogenetics.ResultsHere we report the characterization of a novel opsin family from these green algae: light-inhibited guanylyl cyclases regulated through a two-component-like phosphoryl transfer, called “two-component cyclase opsins” (2c-Cyclops). We prove the existence of such opsins in C. reinhardtii and V. carteri and show that they have cytosolic N- and C-termini, implying an eight-transmembrane helix structure. We also demonstrate that cGMP production is both light-inhibited and ATP-dependent. The cyclase activity of Cr2c-Cyclop1 is kept functional by the ongoing phosphorylation and phosphoryl transfer from the histidine kinase to the response regulator in the dark, proven by mutagenesis. Absorption of a photon inhibits the cyclase activity, most likely by inhibiting the phosphoryl transfer. Overexpression of Vc2c-Cyclop1 protein in V. carteri leads to significantly increased cGMP levels, demonstrating guanylyl cyclase activity of Vc2c-Cyclop1 in vivo. Live cell imaging of YFP-tagged Vc2c-Cyclop1 in V. carteri revealed a development-dependent, layer-like structure at the immediate periphery of the nucleus and intense spots in the cell periphery.ConclusionsCr2c-Cyclop1 and Vc2c-Cyclop1 are light-inhibited and ATP-dependent guanylyl cyclases with an unusual eight-transmembrane helix structure of the type I opsin domain which we propose to classify as type Ib, in contrast to the 7 TM type Ia opsins. Overexpression of Vc2c-Cyclop1 protein in V. carteri led to a significant increase of cGMP, demonstrating enzyme functionality in the organism of origin. Fluorescent live cell imaging revealed that Vc2c-Cyclop1 is located in the periphery of the nucleus and in confined areas at the cell periphery.Electronic supplementary materialThe online version of this article (10.1186/s12915-018-0613-5) contains supplementary material, which is available to authorized users.

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“…The lethality of bleomycin treatment is much more variable because of a precipitous decline in toxicity during early cleavage (Kirk et al 1987); bleomycin-induced Reg mutants studied here were isolated in experiments in which 40-90% lethality was observed. Chl R mutants were selected 24 hr postmutagenesis in liquid SVM containing 1.4 m~ chlorate (Huskey et al 1979b). For identification of Reg and Mes R mutants, organisms were plated in a thin layer of 0.375% SeaPlaque agarose (FMC Corp.) in SVM over a 1% Difco BactoAgar/SVM base.…”

Section: Mutagenesismentioning

confidence: 99%

Use of repetitive sequences to identify DNA polymorphisms linked to regA, a developmentally important locus in Volvox.

Harper¹,

Huson²,

Kirk³

1987

Genes Dev.

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The regA locus plays a centrally important role in Volvox development by preventing somatic cells from redifferentiating as germ cells; until now, approaches to cloning regA, as a preliminary to molecular analysis of its function, have been lacking. Here a novel approach is described that uses repetitive-sequence probes to rapidly identify restriction fragment length polymorphisms (RFLPs) linked to regA. Genomic DNA was cut with restriction enzymes having 4-base recognition sequences and then electrophoresed long enough to run most fragments off the gel; the remaining long (1-to 20-kb) fragments were resolved into numerous, reproducibly identifiable bands. On Southern blots of such preparations, six repetitive-sequence probes were used to identify 1232 bands, 24% of which were polymorphic between two closely related strains. Ninety-four RFLPs, for which inheritance patterns have been analyzed, fall into 36 "segregation groups," within which no recombination was observed in the limited progeny sample analyzed. Eight RFLPs cosegregated perfectly with alleles at the mating-type (rnt) locus. More significantly, four RFLPs exhibited linkage to the regA locus, providing a potential starting place for a chromosome walk designed to clone the locus.

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Mutants of Volvox carteri affecting nitrogen assimilation

Cited by 21 publications

References 22 publications

Babo1, formerly Vop1 and Cop1/2, is no eyespot photoreceptor but a basal body protein illuminating cell division in Volvox carteri

Babo1, formerly Vop1 and Cop1/2, is no eyespot photoreceptor but a basal body protein illuminating cell division in Volvox carteri

Two-component cyclase opsins of green algae are ATP-dependent and light-inhibited guanylyl cyclases

Use of repetitive sequences to identify DNA polymorphisms linked to regA, a developmentally important locus in Volvox.

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