By analyzing isolated Chlamydomonas basal bodies, we have been able to obtain the first reported proteomic analysis of the centriole.

Centrioles are intriguing cylindrical organelles composed of triplet microtubules. Proteomic data suggest that a large number of proteins besides tubulin are necessary for the formation and maintenance of a centriole's complex structure. Expansion of the preexisting centriole proteome from the green alga Chlamydomonas reinhardtii revealed additional human disease genes, emphasizing the significance of centrioles in normal human tissue homeostasis. We found that two classes of ciliary disease genes were highly represented among the basal body proteome: cystic kidney disease (especially nephronophthisis) syndromes, including Meckel/Joubert-like and oral-facial-digital syndrome, caused by mutations in CEP290, MKS1, OFD1, and AHI1/Jouberin proteins and cone-rod dystrophy syndrome genes, including UNC-119/HRG4, NPHP4, and RPGR1. We further characterized proteome of the centriole (POC) 1, a highly abundant WD40 domaincontaining centriole protein. We found that POC1 is recruited to nascent procentrioles and localizes in a highly asymmetrical pattern in mature centrioles corresponding to sites of basal-body fiber attachment. Knockdown of POC1 in human cells caused a reduction in centriole duplication, whereas overexpression caused the appearance of elongated centriole-like structures. Together, these data suggest that POC1 is involved in early steps of centriole duplication as well as in the later steps of centriole length control. INTRODUCTIONCentrioles are barrel-shaped structures composed of nine triplet microtubules. They are necessary for recruitment of pericentriolar material (PCM) to form a complete centrosome and they act as basal bodies during the formation of cilia and flagella. In most quiescent cells, centrioles move to and dock on the apical plasma membrane during ciliogenesis and provide a template for the extension of doublet microtubules, which make up the ciliary axoneme (Ringo, 1967;Sorokin, 1968;Snell et al., 1974;Vorobjev and Chentsov, 1982;Dawe et al., 2007). Centrioles that template cilia are known as basal bodies, and the proteins that compose them have received increased attention in recent years because of their role in ciliary diseases. Ciliary diseases, or ciliopathies, result in symptoms ranging from obesity and retinal degeneration to polydactyly and cystic kidneys (Pazour and Rosenbaum, 2002;Afzelius, 2004;Badano et al., 2006;Yoder, 2007;Marshall, 2008). Ciliopathies arise from mutations in not only ciliary genes but also in genes encoding proteins within the basal body (Ansley et al., 2003;Keller et al., 2005;Marshall, 2008). Proteomic analyses of centrioles from a number of diverse organisms reveal the presence of ciliary disease genes (Keller et al., 2005;Broadhead et al., 2006;Kilburn et al., 2007). Because having a properly anchored basal body is required for a functional cilium, mutations in any protein involved in the formation and maintenance of centriole or basal body integrity have the potential to lead to ciliary diseases.The structure of the centriole is complex and highly preci...

Characterizing Chlamydomonas The unicellular green alga, Chlamydomonas reinhardtii, is a powerful genetic model for the analysis of a variety of cellular functions. Critical assays for genetic analysis include those for the determination of mating type and for the positive identification of diploid organisms. Both types of assay can be hindered by technical obstacles. Zamora et al. (p. 534) describe a simple PCR-based method that simultaneously identifies both the mating type and ploidy of Chlamydomonas cells. In a single PCR, sequences specific to each of the two alleles of the mating type locus, mt+ and mt, are amplified by primers designed to produce PCR products of different sizes. Using this approach, the mating type alleles are readily distinguishable on a gel, and DNA from diploid cells is readily identified by the presence of two bands. The method is a significant improvement over existing methods and will become a valuable tool for the Chlamydomonas community.

This paper presents a fully integrated ultrasound system based on a single piezoelectric micromachined ultrasonic transducer (PMUT) monolithically fabricated with a 0.13 µm complementary metal oxide semiconductor (CMOS) process analog front-end circuitry. The PMUT consists of an aluminum nitride, AlN, squared device with 80 µm side that resonates at 2.4 MHz in liquid environment. The monolithic integration of the PMUT with the CMOS circuitry allows a reduction of the parasitic capacitance, a reduction of the electronic noise contribution and a clear improvement in the Signal-to Noise ratio (SNR ~ 27 dB better) compared to a non-integrated equivalent system. A pulse-echo experiment with the single PMUT-on-CMOS for transmitting and sensing simultaneously is demonstrated, ensuring a 17.3 dB SNR, higher than the minimal necessary for accurate fingerprint images, paving the way towards a pixel sized imaging system with no need of multiple simultaneous PMUTs transmitters. Consuming only 0.3 mW and getting an input-referred noise of 3.26 mPa/√Hz at 2.4 MHz, the proposed pulse-echo system achieves a competitive noise efficient factor in comparison with the state-of-the-art.

This paper presents an analog front-end transceiver for an ultrasound imaging system based on a high-voltage (HV) transmitter, a low-noise front-end amplifier (RX), and a complementary-metal-oxide-semiconductor, aluminum nitride, piezoelectric micromachined ultrasonic transducer (CMOS-AlN-PMUT). The system was designed using the 0.13-μm Silterra CMOS process and the MEMS-on-CMOS platform, which allowed for the implementation of an AlN PMUT on top of the CMOS-integrated circuit. The HV transmitter drives a column of six 80-μm-square PMUTs excited with 32 V in order to generate enough acoustic pressure at a 2.1-mm axial distance. On the reception side, another six 80-μm-square PMUT columns convert the received echo into an electric charge that is amplified by the receiver front-end amplifier. A comparative analysis between a voltage front-end amplifier (VA) based on capacitive integration and a charge-sensitive front-end amplifier (CSA) is presented. Electrical and acoustic experiments successfully demonstrated the functionality of the designed low-power analog front-end circuitry, which outperformed a state-of-the art front-end application-specific integrated circuit (ASIC) in terms of power consumption, noise performance, and area.

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Background: The role of centrioles in mitotic spindle function remains unclear. One approach to investigate mitotic centriole function is to ask whether mutation of centriole-associated proteins can cause genomic instability.

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