This report describes a Chlamydomonas reinhardtii mutant that lacks Rubisco activase (Rca). Using the Ble R (bleomycin resistance) gene as a positive selectable marker for nuclear transformation, an insertional mutagenesis screen was performed to select for cells that required a high-CO 2 atmosphere for optimal growth. The DNA flanking the Ble R insert of one of the high-CO 2 -requiring strains was cloned using thermal asymmetric interlaced-polymerase chain reaction and inverse polymerase chain reaction and sequenced. The flanking sequence matched the C. reinhardtii Rca cDNA sequence previously deposited in the National Center for Biotechnology Information database. The loss of a functional Rca in the strain was confirmed by the absence of Rca mRNA and protein. The open reading frame for Rca was cloned and expressed in pSL18, a C. reinhardtii expression vector conferring paromomycin resistance. This construct partially complemented the mutant phenotype, supporting the hypothesis that the loss of Rca was the reason the mutant grew poorly in a low-CO 2 atmosphere. Sequencing of the C. reinhardtii Rca gene revealed that it contains 10 exons ranging in size from 18 to 470 bp. Low-CO 2 -grown rca1 cultures had a growth rate and maximum rate of photosynthesis 60% of wild-type cells. Results obtained from experiments on a cia5 rca1 double mutant also suggest that the CO 2 -concentrating mechanism partially compensates for the absence of an active Rca in the green alga C. reinhardtii.The green alga Chlamydomonas reinhardtii is an excellent model to study photosynthetic processes. Although it is very difficult to maintain higher plant photosynthetic mutants, C. reinhardtii cells that are unable to perform photosynthesis can be grown heterotrophically on acetate. Furthermore, the C. reinhardtii nuclear, mitochondrial, and chloroplastic genomes can be genetically manipulated to produce mutant phenotypes (Lefebvre and Silflow, 1999; Rochaix, 2002). A random insertional mutagenesis screen was performed to generate C. reinhardtii mutants that were unable to grow optimally in a low-CO 2 atmosphere (Colombo et al., 2002). From the mutants generated, some exhibited a high fluorescence phenotype, whereas others were obligate heterotrophs that died in the light. Approximately onehalf of the selected transformants required high CO 2 for optimal growth and grew slowly in a low-CO 2 atmosphere. In the higher plant Arabidopsis, Somerville and Ogren (1982) performed a similar screen where they isolated mutants that required high levels of atmospheric CO 2 for growth. Several Arabidopsis mutants with defects in photorespiratory carbon and nitrogen metabolism were isolated. One Arabidopsis mutant isolated in that screen exhibited a reduced affinity of the carboxylation reaction for CO 2 and a much lower in vivo activity of ribulose 1,5-bisphosphate (RuBP) carboxylase . Later studies determined that had isolated a Rubisco activase (Rca) mutant that contained a guanine to adenine transition at the 5Ј splice junction of intron three (Salv...

The unicellular green alga Chlamydomonas reinhardtii acclimates to a low-CO2 environment by modifying the expression of a number of messages. Many of the genes that increase in abundance during acclimation to low-CO2 are under the control of the putative transcription factor Cia5. C. reinhardtii mutants null for cia5 do not express several of the known low-CO2 inducible genes and do not grow in a low-CO2 environment. Two of the genes under the control of Cia5, Ccp1 and Ccp2 , encode polypeptides that are localized to the chloroplast envelope and have a high degree of similarity to members of the mitochondrial carrier family of proteins. Since their discovery, Ccp1/2 have been candidates for bicarbonate uptake proteins of the chloroplast envelope membrane. In this report, RNA interference was successful in dramatically decreasing the abundance of the mRNAs for Ccp1 and Ccp2 . The abundance of the Ccp1 and Ccp2 proteins were also reduced in the RNAi strains. The RNAi strains grew slower than WT in a low-CO2 environment, but did not exhibit a mutant carbon concentrating phenotype as determined by the cells' apparent affinity for dissolved inorganic carbon. Possible explanations of this RNAi phenotype are discussed.

In patients with long and complex SFA occlusion unsuitable for transfemoral recanalization, a radial-pedal strategy can overcome revascularization obstacles.

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We present the case of a patient with a history of aortobifemoral grafting who presented with left lower extremity ischemic rest pain. Aortofemoral angiography was performed through a left radial access and showed a long, calcified total occlusion of the left superficial femoral artery (SFA) and a subtotal popliteal occlusion. The popliteal artery and SFA were crossed retrogradely through a 4-Fr anterior tibial access; the retrograde devices went subintimally and did not reenter at the common femoral level. Subsequently, the radial access was used for antegrade subintimal crossing and dilatation of the SFA, which allowed reentry of the retrograde devices (radial-tibial reverse controlled antegrade-retrograde tracking [CART]). The SFA was then successfully treated retrogradely with orbital atherectomy and drug-coated balloon angioplasty, through a 4-Fr equivalent tibial sheath. © 2017 Wiley Periodicals, Inc.