PCR machines are a must-have in any life science research lab today. The global market of these devices has substantially grown in the past three decades with a large number of models with various characteristics. Table 1 lists the commonly used models and some of their important characteristics, some of the models are also discussed in detail below. A single PCR model cannot accommodate all the needs of the research community. A user can choose among many available options according to research goals, throughput needs and financial capacity. One of the first considerations is whether one should employ an endpoint PCR, q(rt)PCR or a digital PCR device. At present, however, an optimally configured rtPCR device meets the needs of most laboratories for day-to-day genomic applications.

The design of the rtPCR apparatus comes in different forms. Most systems use sample blocks with Peltier elements that accommodate tubes, tube strips or microtiter plates. This construction is prone to “edge effects”, achieving different temperatures in samples located on the periphery compared to the center of the block. There are many approaches to overcome this problem. Bio-Rad, in its CFX series, incorporated six independent thermal electric modules to monitor each sample during all phases of the run. Quiagen with Rotor-Gene series and Roche with LightCycler® 2.0, came up with a different solution, innovating the design of the apparatus to a form of a carousel. These systems spin the samples in a temperature controlled chamber, thereby achieving thermal uniformity.

Sample capacity is also of importance. LightCycler® 2.0 accommodates only 32 samples, while LightCycler®1536 can hold up to 1536 samples. Most devices, however, are adapted for 96-well or 384 well plates. A related issue is an option to interchange sample blocks to accommodate different sample sizes. Thermo Fisher’s QuantStudio 3 and 5 do not come with replaceable sample blocks, limiting the user to work with the predesigned format. A handy way to boost throughput and maintain sample size flexibility is networking multiple independently controlled devices onto the same computer. Eppendorf’s Mastercycler X 50 can connect up to 50 PCR systems in this manner.

The price of consumables is another point of consideration. Many companies produce so-called “closed systems”, requiring the use of specific reagents, kits or reaction vessels, produced by the same manufacturer as the PCR machine itself. Apart from often being pricey, this option greatly reduces flexibility in terms of general supply and experiment optimization. This is the case with most cyclers produced by Thermo Fisher Scientific (previously Applied Biosystems). On the other hand, a more reasonable price of the machinery itself can be negotiated for a closed system, as the user is highly dependent on the manufacturer’s consumables. Quiagen’s RotorGene series is an interesting option from this perspective, as it offers relatively inexpensive and highly reliable PCR devices with open chemistry platforms, but reaction vessels and maintenance costs come at a higher price.

Reaction speed is important; some models offer a 'Fast' option, further boosting throughput, permitting a standard rtPCR reaction to complete in about 30 minutes for a standard 96-well plate and 55 minutes for a 384 well plate.

Different systems also vary in multiplexing abilities. QuantStudio 7 and 12 can simultaneously detect as much as 21 target sequences in a single reaction, whereas Takara’s TP800 only detects two. Nowadays contemporary biotech companies compete with multiplexing capacities of devices they launch to the market, but in common use, multiplexing more than 4 targets is rarely necessary.

Compatibility with laboratory robotics is also an advantage of QuantStudio 6 Flex, Roche’s LightCycler 1536 and Thermo Fisher’s 7900HT, enabling a hands-free loading, unloading and data analysis.

Many of Bio-Rad’s devices, like iCycler, MyIQ, and the CFX series allow an opportunity to program a thermal gradient across the reaction block, thereby facilitating protocol optimization. Some systems like the iCycler even permit a side-by-side run of multiple protocols.

PCR systems may come as standalone units with a user interface or require external computer control. User-Friendly modern touchscreen interfaces are a convenient feature of Biometra’s TOne and Bio-Rad’s CFX Touch series. Systems also differ in software competence, the number of users and protocols they support, data storage, as well as networking options.

Last but not least, there’s the matter of budget. A simple PCR machine like Bio-Rad T100 thermal cycler has a list price of 4912 USD (with a promotional price of 2595 USD in the US) as of Jan 30, 2019. The cost of rtPCR systems ranges anywhere from 15,000$ for some RotorGene models to over 90,000$ for QuantStudio 12k. In sum, every PCR machine is a tradeoff between price and performance, and careful considerations should be taken to single out the appropriate system that meets the specific needs of each laboratory.

Thermo Fisher 7900HT represents a high-throughput, state-of-the-art real-time thermal cycler suitable for most genomic applications. The system block is interchangeable, accommodating standard 96-well and 384-well plates, but also Fast plates and a TaqMan® Low Density Array. The Fast option significantly reduces the run time, allowing for a reaction to take place in about 35 minutes for a 96-well plate and less than an hour for a 384 well plate. The loading and unloading of samples is fully automated, minimizing user intervention. The system simultaneously detects multiple fluorophores and can be utilized for gene expression level measurement, detection, and quantitation of pathogens and allelic discrimination assays. The high sample capacity, fast run time and ability to multiplex make this apparatus a good option for laboratories with high productivity demands. The hands-free sample management and substitutable block module contribute to flexibility experiment planning and management. On the other hand, like many Thermo Fisher’s products, this is a closed system that works only with specific consumables. The lack of a user interface and the need of an external computer also increases the device footprint.

Thermo Fisher 7500 Fast and Fast Dx are more recent modifications of the original 7500 model, supplied with a Fast module. Thermo Fisher 7500 Fast Dx meets the standards of Diagnostic Medical Devices Directive (98/79/EC), accrediting it for In vitro diagnostic purposes in Europe and the US. These systems accommodate a 96-well plate receiving data from five channels. As the device does not contain a user interface, a Notebook or Dell™ Tower computer is provided with the system. The accompanying HRM software is designed for a sophisticated melting curve analysis, reducing subjectivity in data interpretation. Thermo Fisher 7500 and subsequently upgraded versions support many applications, including gene expression analysis, pathogen quantitation and SNP genotyping. Thermo Fisher’s 7500 has lower multiplexing capacities and throughput than 7900HT, but in general, it is a reliable device for most purposes. As with previously described 7900HT, a closed system platform and the absence of an interface somewhat reduces the advantages of this system.

The Applied Biosystems 7300 is an affordable yet reliable qPCR device with a 4-color detection, fit for a wide range of genomic applications. It adapts a 96-well block which does not support a Fast run. It performs gene expression studies, pathogen detection, and quantitation and SNP genotyping. Data processing is made relatively simple and intuitive by a user-friendly software which can be further upgraded for advanced visualization, simultaneous analysis of multiple plates, correction of plate setup mistakes, and other beneficial features. This is a more economical apparatus than the aforementioned 7500 and 7900; however, the relatively low sample size, only four target multiplexing and lack of a Fast option make this device significantly lower in throughput.

StepOne is a simple, low throughput device, tailored for first-time users as well as trained ones. The basic apparatus setup and the accompanying software are user-friendly, making it perfect for lab bench newbies. It is adapted for a 48 well plate with standard run time. An intuitive user interface with an LCD touchscreen and a robust software makes the setup and usage of this device remarkably easy. The latest version of the software integrates data for High Resolution Melt analysis, detecting tiny differences in PCR melting curves. This is an inexpensive, precise device that meets most needs of a life science laboratory that is not challenged with high productivity demands. It is suitable for gene, miRNA, and protein expression analysis, SNP genotyping and translocation analysis. Another advantage of this system is a small footprint, making it a good choice for laboratories with low space capacities. StepOnePlus has similar properties but higher capacities, accommodating a 96-well Fast module and four color detection. Although user-friendly and affordable, a disadvantage of StepOne series is a lower sample and multiplexing capacity.

Thermo Fisher’s GeneAmp 9700 is a reliable endpoint PCR device with interchangeable system blocks, supporting a variety of well formats. Although it performs well for this generation of PCR systems, it is a reasonably robust and noisy machine, with an outdated interface and complicated software, but capable of networking and data management. It has been discontinued in 2015 and replaced with a modernized Proflex system.

The ProFlex system is a modern, cloud-enabled instrument with mobile app connectivity and equipped with a user-friendly touch-screen interface, It has various formats: a 96-well system, 2x96-well system, 2x384 well system or a 3x32 well system and with separate VeriFlex blocks, each having independent temperature control. Along with standard genomic applications, Proflex is also suitable for enzyme studies, restriction digests and other experiments with strict temperature requirements. On the flip side, this is only an endpoint PCR, not an rtPCR system, which significantly narrows down the range of applications.

Thermo Fisher QuantStudio 3 Real-Time PCR System is also a cost-effective benchtop instrument, available either as a stand-alone unit, or configured with a computer. It is a medium-throughput system, compatible with a 96-well 0.1ml or 0.2 ml plate. The user can program three independent temperature zones across the reaction block, allowing for a simultaneous run of several experiments. It has a simple software with no need to install or update, and an interactive touch-screen interface, making it a good choice for inexperienced users. The web-browser system configuration and wi-fi connectivity enable remote access, control, and analysis of experiments. QuantStudio3 can be utilized for a wide range of purposes, including gene, miRNA, noncoding RNA, and protein expression, SNP, mutation and copy number variation detection. The instrument is compact with a small footprint, optimizing bench top space. A minor shortcoming is a lack of flexibility, as the reaction blocks cannot be substituted, so the format of the device must be determined in advance, at the time of purchase. Later versions of this models include QuantStudio 5, QuantStudio 6 Flex, QuantStudio 7, QuantStudio 12k and QuantStudio 3D. The main improvements include an addition of a Fast and 384 well blocks and greater multiplexing abilities. QuantStudio 7 and 12k can detect up to 21 targets, QuantStudio 6 is compatible with laboratory robotics, while QuantStudio 3D performs digital PCR. The Flex series includes QuantStudio 6 Flex and QuantStudio 7 Flex equipped with interchangeable block modules.

In general, Thermo Fisher Scientific offers a palette of highly reliable PCR systems with various features and price ranges. On one side of the spectrum, the StepOne system is an economical, low throughput rtPCR system capable of 3 target multiplexing, supplied with an intuitive software ideal for unskilled users. On the other, cutting-edge 7900HT and QuantStudio 12k, high throughput systems offer a variety of advanced features, including high multiplexing capabilities, laboratory robotics and software competent for complex analysis. The Instrument Connect mobile app was recently developed to keep the user connected to the latest models at all times. A minor shortcoming of these instruments is that they are supported only by consumables produced by Thermo Fisher, thereby diminishing flexibility in general supply.

QuantStudio qPCR instruments can also be used to measure protein thermostability. For example, Alam MM et al measured the thermostability of Plasmodium falciparum protein kinase PfCLK3 with different ligands through differential scanning fluorimetry assays using Applied Biosystems QuantStudio 6 and Protein Thermal shift software [1].

Bio-Rads iCycler combined with an IQ detection system is a real-time PCR machine adapted to accommodate, 0.2-ml tubes, strips and 96-well plates, 0.5-ml tubes, and 384-well plates. It receives signals from four different fluorophores, allowing for simultaneous monitoring of multiple qPCR reactions. The upper block has a dual option, allowing for a substitution of a 96-well block with two 48 well blocks, permitting the run two independent protocols side by side in the same device. The 96-well block also has a gradient feature with eight temperature options for modulating annealing temperature. A small drawback is that only temperature intervals can be defined by the user, while the software designates the exact annealing temperature. This rtPCR system is a suitable option for a broad range of genomic applications and comes with a reasonable price for value ratio. A small shortcoming is a lack of a Fast option.

MyIQ is a single-color rtPCR device customized for detection of common green fluorophores like SYBR Green and FAM. It is superseded by IQ5 optimized for multiplexing, permitting up to 5 target gene analysis. The technology behind these systems guarantees a uniform temperature across the reaction block. Both MyIQ and IQ5 offer a temperature gradient feature, greatly facilitating protocol optimization. A temperature gradient spanning 25°C can be applied at any stage of the run in a single experiment. The accompanying IQ5 software offers advanced analysis, including comparison to multiple reference genes, and a direct comparison of over 5000 Ct values. The acquired data are directly exported to Microsoft Excel spreadsheets. A significant drawback of MyIQ is the absence of multiplexing; however, IQ5 is fit to handle everyday laboratory demands. Neither of these systems has a Fast option, resulting in prolonged run times compared to similar systems.

The DNA engine family encompasses five machines: DNA Engine Thermal Cycler, DNA Engine Dyad Thermal Cycler, Dyad Disciple Thermal cycler, DNA Engine Tetrad Thermal Cycler and the Dyad/Dyad Disciple Cycler Tandem. These cyclers have similar performances and differ mainly in the number of blocks they accommodate and the types of graphical interface. The one thing they have in common is the Alpha Units. These are interchangeable sample block/heat pump assemblies with sensors, meant for customizing the cyclers to meet specific needs. If more than one alpha unit is present, each can be controlled independently, allowing the run of multiple protocols. The DNA Engine family is also adapted for fast PCR protocols and 384-well plates, and can be controlled from a remote. The Moto Alpha Unit enables remote lid control and sealing. Real-time PCR cyclers from this family include DNA Opticon 2 System and The Chromo 4 detector. The DNA Opticon 2 System is a two-color system with a 96-well gradient alpha unit, while the Chromo 4 detector is designed for multiplexing. Bio rad’s DNA Engine family also offers an option of calculated temperature control mode. This feature recruits an algorithm that takes into account the sample volume and vessel type to bring each well rapidly to the desired temperature. The incubation periods are then calculated according to each well, not the whole reaction block, ensuring highly specific and accurate results. A downside of this system is a small display unable to show the entire program on the screen.

The CFX96 and CFX 384 have the same configuration, as they differ only in reaction plate capacity. These systems use patented technology to maintain temperature uniformity between samples. Six separately regulated thermal electric modules regulate temperature during all phases of a run, even while ramping. The system is capable of five target multiplexing and supports FRET assays. A thermal gradient can be set across the reaction block at any point of the run, speeding up protocol optimization. In 2011 Bio-Rad added touch screens to about 1000 products already on the market, thus introducing CFX96 and 384 Touch with similar performances. CFX96 Touch Deep Well was later introduced for in large volume reactions, supporting reaction volumes of up to 125µl. CFX Connect is a member of the same family, but unlike previously described models, does not hold a user interface, but requires a computer for manipulation. The detection system is designed to scan each sample separately, just above the well. This increases sensitivity and avoids detection crosstalk. A Fast scan option is also available, acquiring data only from the green channel, but duplexing and FRET experiments are also possible. The software is user-friendly and capable of difficult normalization options, like normalization to several reference genes, or normalization across multiple plates. A major benefit of the CFX series is the ability to maintain high-temperature uniformity while retaining the plate-based Peltier heating system. On the other hand, the inability to swap system blocks reduces flexibility concerning sample capacity. All devices from the CFX series are open systems, which is a huge advantage as original Bio-Rad consumables come at a high price.

A general feature of Bio-Rad’s systems is an advanced, easy to use software that can be installed on an unlimited number of computers. It also allows the setup of multiple user accounts. Plate setup can be done in Excel and imported into the program, while reports can also be exported to other applications like PowerPoint. Although intuitive and straightforward, the software allows some advanced features, like geometric normalization to multiple reference genes.

Roche 480 Lightcycler is a medium to high throughput benchtop instrument intended for general laboratory use. It works with a 96-well or a 384 well block. Very high sensitivity and an expanded excitation spectrum (390-710nm) appropriate for a wide range of probe formats are some of the hallmarks of this instrument. Five excitation and six emission filters are combined to enable detection of multiple target sequences and FRET experiments. A Fast option is also available, completing an rtPCR reaction in 40 minutes on a 384 well plate. Roche 480 Lightcycler is a reliable device, intended for gene expression and variation analysis, and data array validation. A weak point of the system is the provided software, which is slow at times and cannot be loaded onto a personal computer. Also, Lightcycler is a closed system platform, with somewhat expensive consumables.

Roche Lightcycler 1536 is an advanced version of Lightcycler 480, adjusted for extremely high throughput demands. It accomplishes 1536 rtPCR reactions in less than 50 minutes in very low reaction volumes, ranging from 0.5µl to 2µl per well. The manufacturer states that due to such small input volumes, the cost of reaction per data point decreases by 50%. The accompanying software is also adapted for high throughput needs. The machine comes with a few drawbacks. First of all, it is capable of only two-color multiplexing. Also, the large footprint of the device itself, plus the obligatory tower computer occupy a large portion of laboratory space. Lastly, very few research projects indeed require a throughput this high. Therefore, only laboratories with very special objectives and high sample number expectancy could benefit from this system.

Roch Lightcycler 2.0 is a Real-Time PCR system intended for in-vitro diagnostic purposes. Instead of reaction plates with wells, this cutting-edge system uses a carousel of thirty-two 20 µl or 100 µl reaction capillaries specially designed for swift thermal transfer. This unique technology uses fan driven air with a heating coil for temperature control instead of thermal blocks, ensuring temperature homogeneity and fast cycling. At the time of measurement, the sample carousel is rotated, positioning the capillaries optimally for optical reading. The provided software assembles and presents data in each cycle, enabling early termination or extension of the reaction, depending on signal strength. It is compatible with foodproof® rtPCR kits developed by BIOTECON, designed for a variety of applications in the food industry like detection of pathogens, including bacteria, viruses and fungi, allergens and GMO in a broad range of samples.

The Mx3005 and Mx3005P™ share the same unique optical scanning design, with a fiber optic head assuring uniformity in excitation light, detection time and detector distance. The scanning system moves along the 96-well block, thus avoiding signal variation, and eliminating the need for reference dye calibration. It receives data from four channels, and is suitable or multiplexing and FRET assays. Agilent has replaced the Mx3000p system with AriaMx, an integrated system for amplification, detection, and analysis. Accessories and consumables for Mx3000p will be available until 2020.

Mx3005p has an expanded excitation and detection wavelength spectrum compared to Mx3000 and an additional optical channel. It offers an option of selecting a set of five from the available eight filters, customizing the instrument to meet the user’s specific needs. These are both accurate, reliable and cost-effective instruments, applicable for gene expression and mutation analysis along with FRET experiments.

A shortcoming of these machines is a modest throughput capacity as they only work with a 96-well block. Also, the requirement of an internal reference dye reduces multiplexing options.

Eppendorf’s Mastercycler family encompasses a series of devices belonging to different generations. Among the things they have in common are a low power consumption, a touchscreen interface, excellent temperature control, and a flexible lid, allowing the cycler to work with consumables of different volumes. Mastercycler X50, Mastercycler Nexus, and Mastercycler Gradient come with a thermal gradient feature, allowing a simultaneous test of 12 different temperatures across the block. Ramping speed can also be adjusted, providing the user with even more control. Mastercycler Nexus supports the simultaneous run of two independent protocols. The Mastercycler X50 family consists of independently controlled and monitored eco units that can be networked onto a computer. Up to 50 units can be networked together with CycleManager X50 as a central controller, significantly boosting throughput. Low noise levels and small footprint make these devices friendly for laboratories with limited space.

Takara TP800 succeeded with TP860 is an rtPCR machine with a 96-well capacity, mostly intended for the Asian market. It reads signals from FAM, SYBR Green I, Rox and Texas red, and can simultaneously detect two target sequences. The machine is a medium throughput, low multiplexing machinery that is not available in the US or Europe.

Qiagen developed a family of rtPCR systems with a unique centrifugal configuration. This design achieves thermal uniformity by constantly spinning samples at 500 or 1000rpm. The rotor is interchangeable with capacity 36 or 72 reaction vessels, while Rotor gene 6000 also offers a higher throughput 96 vessel rotor. High-temperature uniformity eliminates the need for a passive ROX dye in each sample. Signal detection is highly reliable, as each sample is separately illuminated and measured, evading crosstalk. All samples are measured in one revolution. Both Rotor-gene 3000 and 6000 have multiplexing abilities, the first trailing four, and the second five targets. The systems are open chemistry platforms, compatible with different enzymes and virtually every fluorophore: Sybr-Green I, FAM, TET, JOE, VIC, HEX, ROX, TAMRA, CY3, CY3.5, CY5, CY5.5. Optic denaturation is a patented feature introduced specifically for Rotor-gene systems, granting an opportunity to monitor fluorescence during denaturation. After this step, the samples only need to be heated to reach the temperature of total denaturation, hence shortening run time.

In summary, these are reliable and affordable low to medium throughput systems suitable for most genomic applications. Quiagen has now introduced a Rotor-gene Q family following the same concept, but with somewhat better performances. It is currently the only system capable of deciphering the most challenging class IV SNPs. An obvious shortcoming of Rotorgene cyclers is the low throughput. Also, as the samples are heated and cooled by circulating air, the system is sensitive to external room temperature, so the laboratory that accommodates the device needs constant air-conditioning.

Fluidigm’s cutting edge integrated fluidic circuits (IFC), and Dynamic Array chip technology uses silicon chips with thousands of intertwining valves and channels performing rtPCR on a large scale in nanoliter volumes. The chip probes as many as 48 or 96 samples with the same number of assays producing a large number of results in only one reaction. The chip is designed to carefully combine the samples with the reagent cocktails by controlling the pressure in the fluidic valves. A typical rtPCR is executed in about 30 minutes. This system can be employed for a vast number of life-science applications, including mass cytometry, single-cell genomics and proteomics, and digital PCR. The instrument is an extremely high throughput system, achieving over 9000 data points in a single reaction. Nanoliter-scale reactions economize both sample and reagent expenditure, while IFC technology saves thousands of pipetting steps. Completely sealed reaction chambers on the chip alleviate the likelihood of contamination. This is a piece of mighty machinery, but it comes at a high cost. In the US the price of BioMark is 200,000 to 250,000 USD. The consumables are also expensive and non-reusable. A 12,765 data point chip is 360 USD, while the 48,770 chip is 720 USD, although the prices can go down if buying in bulk.

TOne thermal cycler is an affordable rtPCR device with an optimal price-to-value ratio. Besides a standard 96-well plate with a gradient option, it also accommodates a range of reaction vessel consumables, as well as an in-situ module for four microscopic slides. The system provides a high standard of temperature uniformity as well as high ramping rates. It has a 7-inch touch screen interface with user-friendly software. This is a solid device, convenient for diverse life-science applications, achieving low cost without compromising performance. Biometra TRIO has similar features but provides three independent sample blocks. Besides average throughput, Biometra’s customer support is abysmal in some countries.

Biotech companies around the world offer a range of PCR systems, each having advantages and shortcomings. For projects that have relatively low throughput needs but cope with budget concerns, StepOne or RotorGene 3 can be an acceptable option. Others, with high throughput requirements, both regarding sample capacity and multiplexing, may choose a costly Thermo Fisher 7900HT or QuantStudio 12. Labs that struggle with space shortage could benefit from Eppendorf’s Mastercycler. If a powerful, yet user-friendly software is decisive, one should definitively choose between some of Bio-Rad’s products. Hidden costs of closed system platforms like the ones produced by Thermo Fisher or Roche should also be taken into account. Customer service support and the availability of consumables are an issue in some countries, even for renowned brands. In all, when cherry-picking the proper thermal cycler that meets the needs of particular research, each machine should be carefully scrutinized to find an optimal balance between its merits and weak points.

Labome conducts surveys on reagents and instruments. PCR machines/thermal cyclers from formal articles were cataloged. Table 2 lists major suppliers and their main models cited in these publications. Three suppliers dominate the citations. They are Thermo Fisher, Bio-Rad (including brand MJ Research) and Roche. The most cited models are Thermo Fisher 7x000 series, iCycler/MyIQ from Bio-Rad, and LightCycler from Roche.

Thermo Fisher, over the years, obtained brands like Life Technologies, Invitrogen, and Applied Biosystems (ABI).

Chopra S et al performed quantitative RT-PCR with a QuantStudio 6 Flex real-time PCR system from Thermo Fisher [24]. Kulkarni S et al performed SYBR green qPCR analysis of CCR5AS and GAPDH transcripts with a Quantstudio 5 machine [25]. De Cecco M et al used ABI ViiA to study the involvement of L1 retrotransposon during cellular senescence [26]. A 7900 Fast Real Time PCR System was used to study Zfp521 [27], Hedgehog signaling pathway [28], USF1 [29], Erf2 [30], and CK2 kinase [31] and to study the mechanism by which the small molecule inhibitor of TGF-beta receptor I reverses beta cell de-differentiation [32], the distinct roles for wnt signalling in the specification of spinal cord and paraxial mesoderm identity [33], the mechanism by which the nuclear envelope protein MAN1 regulates clock [34], the role of type I interferons in the DC maturation after poly IC stimulation [35], the effect of the insulin signalling on the age-related sleep fragmentation in Drosophila [36], the role of transcription factor ZEB1 in the adipogenic gene regulatory network [37], the evolution of resistance to amphotericin B for Candida albicans [38]. 7500 Fast Real-Time PCR System was used to study miR-7 [39], and U6atac snRNA [40]. 7300 Real Time PCR System was used to study the role of radial glial progenitors in stabilizing nascent brain vascular network [41], the role of Dmxl2 in infertility associated with a loss of GnRH neurons in mouse [42], the function of eEF1A1 in transcription during heat shock response [43], and the functions of TAF7L in adipocyte differentiation [44].

StepOne RT-PCR or StepOnePlus PCR system was used to study the regulation of dopamine receptor 1 neurons in the dorsal striatum on food anticipatory circadian activity rhythms in mice [45], asymmetric cell cycle [46], the effect of the histone H3K23 methylation on DNA damage in pericentric heterochromatin during meiosis [47], the role of Pvr expression regulators in equilibrium signal control and maintenance of Drosophila blood progenitors [48], and Vav2 and Vav3 [49].

ABI 7000 cycler was used to study the mechanism of the glial responsiveness to axonal injury in Drosophila [50]. Other articles also cited the use of ABI's PCR apparatus [51].

Roche 480 Light cycler was used to study the role of Dectin-1 in anti-tumor responses [52], the regulation mechanism of the cell division by DidA in Caulobacter crescentus [53], the interaction between NK4 and Tbx1/10 in regulating cardiac versus pharyngeal muscle fate in the ascidian second heart field [54].

Roche LightCycler 2.0 was used to perform the real-time PCR in order to study the role of CDON in regulating tumor cell survival [55].

Other articles also cited Roche LightCyclers [56-58].

Kulkarni S et al performed SYBR green qPCR analysis of CCR5AS and GAPDH transcripts with a Viia7 machine [25]. Flaherty SE et al evaluated the expression of multiple genes in bone-marrow-derived macrophages with quantitative PCR using Bio-Rad DNA Engine Opticon 2 system instruments [15].

Bio-Rad CFX96 Real-time cycler was used to study the regulation mechanism of embryonic tissue separation by combinations of specific ephrin ligand/Eph receptor pairs [59], the mechanism by which the downy mildew effector attenuates salicylic acid-triggered immunity in Arabidopsis [60] and bilaterian head development [61]. Bio-Rad CFX 384 Real-Time PCR Detection System was used to perform qPCR in order to study the role of Dmxl2 in the infertility associated with a loss of GnRH neurons in mouse [42] and the role of wolbachia genes in Mutualism [62].

Bio-Rad Laboratories iQ5 Multicolor Real-Time PCR detection system was used to study Arabidopsis timing control [63]. Bio-Rad Chromo4 Real-Time PCR Detector was used to perform qPCR in order to explore the role of the cytoplasmic aggregation process in the molecular pathology of Huntington's disease [64].

Bio-Rad MyiQ Cycler was used to study the resemblance between the interspecific hybrids and piRNA effector-protein mutants in Drosophila [65], the virulence evolution of Mycoplasma gallisepticum [66], and the role of Lsd1 during blood cell maturation [67].

MJ Research thermal cyclers were cited for the research of Rad51p [68] and starch degradation in Arabidopsis [69].

Other articles cited Bio-Rad PCR instruments as well [70].

de Goffau MC et al detected bacterial 16S rRNA gene from human placental tissues with a SureCycler 8800 Thermal Cycler from Agilent Technologies [22]. Stratagene MX3000p qPCR machine was used to perform qRT-PCR to study the role of the BMP signaling pathway in setting the circadian period in PDF neurons in the adult brain [71] and Nodal and Lefty [72]. Stratagene Mx3005P Multiplex qPCR system was used to study the role of the mutant schengen3 in plant nutrient homeostasis [73], plant volatiles [74], the role of Etv2 in vascular development [75], temperature-responsive virulence change of Histoplasma capsulatum [76] and Stratagene Mx4000 QPCR system for the study of translating rhythms [77]. Other articles cited Stratagene Mx real-time thermocycler as well [78].

Eppendorf Mastercycler was used to perform PCR to investigate the regulation of wingless signaling on the degradation of armadillo/beta-catenin [79], engineered RNA modules [80], EIN2 processing and translocation [81], castration-resistant prostate cancer [82], and MCU gene [83].

Fluidigm BioMark real-time PCR system was used to perform qPCR to show that oscillator gene expression could be inhibited by TOC1 [84]. Qiagen Corbett Research Rotorgene 6000 Thermocycler was used to perform qPCR to show that honey bee virus diversity could be changed by parasitic Varroa [85] and its RG-3000A Real-Time PCR System was used to perform qPCR to study the role of the histone demethylase KDM3A in response to heat shock [86].

A PCR machine can be a part of an integrated system. For example, Kaya-Okur HS et al conducted on-chip PCR using the SMARTer ICELL8 Thermal Cycler within a SMARTer ICELL8 single-cell system from Takara Bio for single-cell CUT&TAG experiments [87]. |