The diversity of gas vesicle genes in Planktothrix rubescens from Lake Zürich

Abstract

) shows that strains of the GV3 genotype produce gas vesicles with a higher critical pressure than those of GV1 and GV2. A PCR survey of 185 clonal cultures of P. rubescens isolated from Lake Zu $ rich revealed that 3 isolates were of genotype GV1, 73 were of GV2 and 109 were of GV3. The PCR technique was used to distinguish the gas vesicle genotype, and thence the associated critical-pressure phenotype, of single filaments selected from lakewater samples. Sequence analysis of the 16S rDNA and of regions within the operons encoding phycoerythrin, phycocyanin and Rubisco confirmed that these strains of Planktothrix form a tight phylogenetic group.

The daily integral of growth by Planktothrix rubescens calculated from growth rate in culture and irradiance in Lake Zürich

“…In these calculations we used the growth-rate coefficients for Pla 9316 rather than those for Pla 9303 (Table 1) ; a recent survey has shown that filaments with the same genotype (GV2) as strain Pla 9316 were commonly found in Lake Zu$ rich, whereas those with the same genotype (GV1) as Pla 9303 were rarely encountered (Beard et al, 1999). The potential growth rates for each depth and time on the first day of the study, 10 July 1995, were calculated by transferring the data on I Z \I !…”

Elucidation of the gas vesicle gene clusters in cyanobacteria of the genusArthrospira(Oscillatoriales, Cyanophyta) and correlation with ITS phylogeny

“…The deduced amino acid product of ORF1 (151 residues) is similar to the N-terminal part of GvpC 20 of Planktothrix rubescens BC-Pla 9316 (Beard et al, 1999). Parts of ORF2, designated gvpC1 0 and gvpC2 0 (Fig.…”

“…The newly designed Arthrospira primers are indicated by their respective letters and numbers, but the prefix ArGVP (see Table 1) is omitted. Primers U5 0 and U3 0 correspond to the universal degenerate gvpA primers GVPA-5 0 and GVPA-3 0 of Beard et al (1999), respectively. The sequence of this 1683-bp region was obtained by sequencing clone D1683 (Supplementary Table 1).…”

“…Amplification products obtained with primers GVPA-5 0 and GVPA-3 0 (Beard et al, 1999) and ArGVPA1 and ArGVPC2 were cloned prior to sequencing using the StrataClone TM PCR Cloning Kit (Stratagene, USA). Recombinant clones containing the desired insert were identified by single-colony PCR.…”

“…Isolates of Planktothrix also differ by exhibiting different combinations of three length variants of the gvpC gene: gvpC 16 , gvpC 20 and gvpC 28 . Based on the gvpA and gvpC copy numbers, and the combination of the three gvpC length variants in their gvpA-C gene cluster(s), strains of P. agardhii and P. rubescens exist as six or more different GV genotypes (Beard et al, 1999(Beard et al, , 2000(Beard et al, , 2002. GvpA and gvpC are not the only genes involved in gas vesicle formation.…”