Handbook of 16S rDNA Sequencing: The Past and the Present

The basic concept of 16S rDNA

16S rDNA is one of most useful and most commonly used molecular clocks in the systematic classification of bacteria. It has few species but large content (about 80% of bacterial RNA content). Its molecular size is moderate and exists in all organisms. Its evolution has been smooth and is highly conservative in structure and function. It is known as “bacterial fossil”. In most prokaryotes, rDNA has multiple copies, and the copy number of 5S, 16S, and 23S rDNA is the same. 16S rDNA is moderately sized, about 1.5Kb, which can reflect the differences between various strains, and can be easily obtained by sequencing technology, so it is widely accepted by bacteriologists and taxonomists. In short, 16S rDNA is universal, conservative, moderately sized and has variable zone.

To be more specific, this article summarizes its features as follows:

1. 16S rRNA is ubiquitous in prokaryotes. rRNA is involved in the process of protein synthesis. Its function is essential to any organism, and it remains unchanged during the long course of biological evolution. It can be seen as a time clock for biological evolution.

2. In 16S rRNA molecule, it contains both highly conserved sequence regions and moderately conserved and highly variable sequence regions, so it is suitable for the study of various biological phylogenetic relationships with different evolutionary distances.

3. The relative molecular weight of 16S rRNA is moderate, about 1540 nucleotides, which is convenient for sequence analysis.

4. The variable region sequence varies from bacteria to bacteria, and the constant region sequence is basically conserved. Therefore, primers can be designed by using the constant region sequence to amplify the 16S rDNA fragment, and the difference between the variable region sequences can be used for different genus and strains. Based on this, the bacteria were classified and identified.

16S structure

The 16S rRNA gene sequence includes 9 variable regions and 10 conserved regions. The conserved region sequence reflects the genetic relationship between species, while the variable region sequence reflects the differences between species.

Figure 1. 16S rRNA gene sequence

Strain identification based on 16S full-length (first generation sequencing)

Object: pure colonies that have been cultivated

Technology: first generation sequencer 3730

Process: Nucleic Acid Extraction –> Gene Amplification –> Product Purification –> Sequencing Reaction –> Sequence Alignment


Graph LR


Nucleic Acid Extraction–>Gene Amplification


Gene amplification–>product purification


Product purification–>sequencing reaction


Sequencing reaction–>sequence alignment

Commonly used primer sequence by 16S full length (see Table 1):

Table 1. Commonly used primer sequence by 16S full length

Reagent cost: about $15

Advantages: it can assist routine strain identification methods, such as microscopic morphology and culture characteristics as well as physical and chemical properties, including nutrient type, carbon and nitrogen source utilization capacity, various metabolic reactions, enzyme reactions and serological reactions, etc., to improve the accuracy of strain identification.

Disadvantages: it can only be used for pure bacteria!

Bacterial structure analysis based on 16S (Next-generation sequencing)

Objects: clinical samples (such as feces, cerebrospinal fluid, blood, urine, etc.), environmental samples (soil, sewage, etc.)

Technology: second-generation sequencers, such as Hiseq and Miseq from Illumina, Ion Torrent from Thermo, and 454 from Roche (discontinued)

Process: Genomic DNA –> Sample Quality Control –> PCR Amplification Database –> Library Quality Control –> Illumina Hiseq2500/Miseq Sequencing –> Raw Data –> Data Quality Control –> High Quality Data –> Bioinformatics Analysis

Some commonly used primer sequences are listed in Table 2.

Table 2. Primer selection table for specific 16S rRNA gene region to be amplified

Reagent cost: about $15 ~ $60/sample, determined by the use of consumable grade and labor costs.

Advantages: By detecting the sequence variation and abundance of 16S rDNA, the classification and abundance of bacteria is revealed in the sample, obtaining sample species classification, species abundance, population structure, phylogenetic evolution, community comparison, etc., which can be used for detection of unknown clinical samples and finding pathogens.


(1) Limited by the read length of the second-generation sequencing, currently only two of the nine variable regions of 16S can be measured, generally the V3-V4 region. Therefore, for the resolution of the flora, some strains can only be distinguished to the genus level.

(2) Lack of SOP experimental program. Different experimental factors have a greater impact on the experimental results.

(3) The 16S metagenomics can also be used for functional studies, but not accurate, compared to the WGS metagenomic sequencing.

The Future of 16S: Third Generation Sequencing

Pacbio sequencing technology for 16S metagenomics has been published. A reference article: High-resolution phylogenetic microbial community profiling.

9 variable areas are tested on the machine, with high resolution and high accuracy, which is more suitable for unknown pathogen detection and other scientific research applications in clinical samples.

Unfortunately, due to unresolved sample pooling and other reasons, its price remains high.

About author:

As a leading provider of NGS services and a partner of Illumina, CD Genomics offers a portfolio of solutions for metagenomics sequencing. 16S/18S/ITS amplicon sequencing is characterized by cost-efficiency, high-speed and practicability to help you identify and investigate the microbial community. With over 10 years of experience, we can totally meet your project requirements and budgets in the exploration of microbial biodiversity.

creep in plastic materials

In material sciences, creep is sometimes referred to as cold flow. In this regard, the difference between plastics and other materials is that plastics display time-dependent viscoelastic behavior. Viscoelastic behavior is the property of a material to display both viscous and elastic characteristics when undergoing deformation. It can result from long-term exposure to high levels of stress that are still beneath the yield strength or yield point of the material. The yield strength or yield point of a material is the property defined as the stress at which that material begins to deform permanently. Deformation refers to any change in the shape of an object due to an applied force or a change in temperature. The first instance can be the result of tensile forces, sometimes called pulling forces, compressive forces (pushing forces), or shear, bending or torsion (twisting). Deformation is often described as “strain”. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible.

Types of Creep
There are various kinds of creep. Nabarro-Herring creep is a form of diffusion creep that is strongly temperature dependent. Coble creep is a second form of diffusion-controlled creep. It is still temperature dependent but not as much as the Nabarro-Herring creep. Harper-Dorn creep has been observed in aluminum, lead and tin systems as well as some ceramics, ice and some solders. The first two types of creep are grain size dependent while the Harper-Dorn creep is dislocation-motion dependent.

Stages of Creep
Creep is one of the most commonly studied long-term property tests performed. Creep does not happen suddenly, but rather results as an application of stress over the long term. Creep is therefore a time dependent deformation. There are three stages of creep. In the first stage, referred to as “Primary Creep,” the strain rate is at first relatively high, but slows over time. In Secondary Creep, the creep occurs at a relatively uniform rate and is called at this point “creep strain rate”. Finally, Tertiary Creep occurs at an accelerated creep rate and ends when the material breaks or ruptures.

Rate of Deformation
There are several functions of a material that determine the rate of deformation. These include the properties of the material, exposure time, exposure temperature and the structural load that is applied. In fact, depending on the amount of stress applied, how long it is applied, the temperature and the applied structural load, the deformation may be so large that a component can no longer perform in the application for which it is designed. A turbine blade would be one example. The creep may be so great that over time the blade will make contact with the casing, causing the blade to fail. Creep may not result in a failure mode. It can be desirable in concrete because it relieves tensile stress that could result in cracking.

Find more information about plastic mold injection technique view here: China Plastic Injection Molding

Mineral Makeup – Why Use Mineral Cosmetics?

Liquid makeup is so yesterday. These days, women the world over are wearing the new “hot” product – mineral makeup.

Those who haven’t converted, however, might be unclear on the concept. What’s all the fuss about anyway? Isn’t putting minerals on your face a bit odd?

Mineral cosmetics and makeup is hot for a reason. There are many benefits to using this natural product on your skin, which we’ll outline here.



First, many women are attracted to the all-natural quality of mineral makeup. The makeup is composed of minerals that are extracted from the earth. They are first pulverized into a powered form; they are also sterilized so they are safe to use.

The makeup is a combination of zinc oxide, titanium dioxide and micronized minerals. There are no chemicals (which is a common cause of irritation and inflammation in the skin). Mineral makeup also naturally contains iron.

Unlike many liquid makeup types, mineral makeup contains no talc, perfumes or dyes.

This natural element is one of the main reasons that women are attracted to mineral makeup. It’s one more way to bring the natural in and leave the chemicals out.


One of the top reasons women give for wearing mineral cosmetics is the look they get from the makeup. Specifically, mineral makeup is soft, and provides the skin with a natural glow.

Rarely will women who use mineral makeup get a heavy, overdone look to their skin. Often, it appears they aren’t wearing makeup at all. Because the makeup is so light and airy, it also feels like nothing is on the skin.

Skin care

Women concerned about their skin are also attracted to mineral makeup because its natural state ensures that it doesn’t clog pores or dry skin out.

Unlike liquid makeup, natural makeup and cosmetics is suitable for all skin types. You don’t have to shop for the “oily” skin makeup, or the makeup that’s best for dry skin. Mineral makeup is naturally the best makeup for all skin types.


Applying mineral and natural makeup is generally easier than applying liquid makeup. There is no line of demarcation to worry about and applying the makeup is as simple as applying the makeup to a brush and applying to the face.

Many women like that they can mix a few shades to get the perfect shade for their skin. And if it’s summer, they can add a slightly darker makeup to the mix and get the right shade, while in winter, they can keep it lighter, all without having to change makeup for the seasons.

Long-term benefits

Finally, using natural makeup can provide long-term benefits to the wearer. Many people believe that mineral makeup is naturally better for the skin than other kinds of makeup, so it’s believed that your skin will have fewer problems with dryness, oiliness or other irritations.

Most mineral cosmetic makeup brands also have a natural SPF, so your skin is also provided from both UVB and UVA rays.

There are many benefits to using mineral makeup beyond looking pretty.

Maybe you are interested in testing product for free, here is a big chance, view more: Test Makeup Products Free

Super Matte Top Coat from BeautyBigBang

Hey lovelies! I just reviewed a cotton claw by BeautyBigBang a few minutes ago, and now it is time to review a matte top coat from BeautyBigBang.

Now, I did not wear the following mani for longer than 2 hours, so I cannot speak on how long this matte top coat lasts. Therefore, I’m not going to give this product a “My rating” since wear-time is a part of that rating. I just haven’t gotten into wearing matte manis, so if you guys want to know how long a mani lasts with this matte top coat, let me know in the comments below. Other than that, let’s get into the swatch and review!

*The following swatches are applied over ÜNT Ready for Takeoff and topped with Glisten & Glow Top Coat BEFORE applying the matte top coat. Chocolate Praline Layered Cake was used as the base color.

Super Matte Top Coat (SKU: 66330)

Matte Nail Polish Top Coat

Description: Use this matte top coat to turn any nail polish color to a dull flat matte finish.

Application: Smooth application, not streaky, & easy to use brush. No white specs were left behind (that’s a spec of glitter on my index nail; it wasn’t from the matte top coat).

Availability: Available now.

Drying time: 1-2 minutes.

Price: $3.59 USD

Overall thoughts: This matte top coat nail polish gives a really nice finish, and I will definitely use it for future swatches. If you’re a matte lover, I highly recommend this matte top coat.

Chrome nails: How to do it at home – in 6 easy steps!

Are you also obsessed with mirror nails or chrome nails? They are so shiny that I can’t get enough! Luckily enough it’s very easy to get the true mirror chrome finish at home. I will show you how to get this eye-catching trend in six easy steps.

To get started with this chrome nails tutorial, you do, however, need some products. But don’t be afraid, all the steps are simple. And with all the material included, this is still cheaper than going to the salon – especially considering that you can use the products again and again.

How to do Chrome nails at home – in 6 easy steps!

What you need

Gel polish*
Base Coat
Chrome nail powder
UV- or LED Lamp
Top Coat

*In this tutorial I have used Lackryl. It’s a new Swedish acrylic polish that has everything in one bottle. You don’t need to apply base coat, primer and top coat – but you can, of course, use traditional gel polish as well. If you, however, come across Lackryl I would definitely recommend it as it’s makes everything even easier and faster.

But as it’s not available to the rest of the world yet, I will describe all the steps for gel polish instead.

Chrome Nails Tutorial – DIY: Kromnaglar
Before you begin: Start with prepping your nails

Before we start this tutorial you need to have clean nails. So take the time to cut, file and shape your nails. Once you have the basic shape to your nail, use a cuticle stick to push back any skin off your nail plate.

1. Buff your nails

Gels does not stick to “shiny” so gently buff your nails with a buffer.

2. Clean away the nail dust

Use a soft brush to remove the nail dust.

Chrome Nails Tutorial – DIY: Chromenaglar
3. Apply a thin layer of polish

So as I’m using Lackryl I only apply Lackryl in this step. But if you are using a gel polish you need to first apply a primer, let it dry, then apply a base coat and cure it before you apply your gel polish. Two things to keep in mind is to apply a very thin layer of any gel and to keep a small distance away from the edge of your nail.

4. Cure under UV or LED lamp

Follow the gel polish manufacturers instruction and cure your nails in the light for the recommended time. Repeat with a second coat.

Lackryl Pale Rose Akrylnagellack
This is how my nails looked like after 60 seconds, having applied one coat of the color Pale Rose from Lackryl.

Chrome Nails Tutorial – DIY: Chromenaglar med Lackryl
5. Apply the chrome pigment

Now to the really fun part! Use a little applicator (usually comes with the chrome pigment) and wipe the chrome nail powder across the nail until the nail begins to reflect light. This step is really hypnotizing. It’s almost a pity that it goes so fast to get the mirror finish on all nails.

Chrome Nails Tutorial – DIY: Kromnaglar
The chrome pigments are just so cool. Even though they cover the whole polish, feel free to experiment with the pressure and create different effects or an ombre look with your applicator.

Chrome Nails Tutorial – DIY: Chromenaglar med Lackryl
6. Apply your top gel coat

Apply a thin layer of a top coat and cure it in the lamp. Some gels leave a sticky layer on after curing the top gel. If this is the case, simply take a cotton ball dipped in isopropyl alcohol and wipe over the sticky surface.

Finish off your chrome gel manicure by applying a cuticle oil and massaging in some hand cream to get that extra salon finish.

Done and done! You now have some really eye-catching nails that will last for around a month.


10 Common Acne Myths

1. Do facials work in targeting acne and removing acne scars? A Bella Skin Care spokesman said that regular salon treatment helps by controlling sebum production, healing existing acne scars and minimizing pores. Dr Chee Yew Wen, medical director of Wen & Weng Medical Group said that for mild acne, facials do help, depending on what beauty salons do.

For instance, micro dermabrasion and mild chemical peels can help unclog pores. Depressed scars, however, are harder to improve and require stronger lasers done by doctors. Extraction should be reserved only for comedones (Blackheads and whiteheads). Moderate to severe acne, especially of pimple are inflamed and contain pus, should be treated by doctors where oral medication is usually required.

2. Does blotting frequently worsen acne as it encourages more oil to be produced in the skin? Whether you blot or not, the body will still produce oil in the skin. “It’s not scientifically proven that blotting frequently encourages more oil to be produced. Its all right to blot.

3. Should pimples, blackheads and whiteheads be extracted? Extracting pimples is a no-no as the pressure applied to the skin may extend inflammation to other areas of the skin. You can extract blackheads using a blackhead extractor but you have to ensure the extractor is placed at an angle that is 90 degrees to the skin surface.

4. Does washing your face more often get rid of acne? It depends on what you use. If you have a lot of whiteheads and blackheads, choose something which contains alpha hydroxy acids (AHAs). If you have inflamed acne with bumpy skin, use a cleanser which can kill bacteria. Simple washing twice a day is more than enough. Over-washing in fact can worsen acne.

5. Does tanning help to clear up acne? Tanning only mask acne by evening out the skin color temporarily. Skin may become dry and irritated after a tan which can prompt an acne outbreak. If you go under the sun a lot, use a sunscreen with a sun protection factor of at least 15, and which is non-comedongenic, that is, which does not tend to clog pores.

6. Will eating foods like chocolate or peanuts cause an acne outbreak? Medically speaking, no, have i have observe peculiar instances in individual cases. Test yourself. If you get a breakout 10 times out of 10 when you eat a certain item, cut it out.

7. Does stress cause acne? Stress can worsen acne through the release of increased levels of hormone which form the adrenal glands which in turn over-stimulate the oil glands.

8. Can you wear make-up if you have acne? It is best to stick with established brands. Its also advised to use non-comedogenic make-up.But if you have make-up on, it is important to thoroughly remove it later as make-up can clog pores. i recommend using mineral-based make-up which is less comedogenic. There have been cases of vicious cycles where the more acne a person gets, the more she tries to cover it up with make-up and the more make-up blocks the pores. If you have to wear make-up, don’t wear it for prolonged periods.

9. Does having large pores mean you will have acne? Large pores refer to the pore size and are unrelated to having pimples or acne, although enlarged pores generally mean the person is susceptible to oil skin conditions and is prone to acne outbreaks. People who have acne tend to have larger pores so the condition goes hand in hand.

10. Does sex or masturbation cause acne? All the doctors I spoke to said there was no data to suggest that sex or masturbation causes acne.

Get rid of acne forever, try this Acne Extractor Kit

A Brief Overview of Various Types of Stunning Nail Designs

nail art supplies online
nail art supplies online

If you want to improve the look and appearance of your nails, it is vital that you should try out one of the best nail designs successfully. If you have purchased items, there is possibility that you will be able to create nail designs in the best possible way. If you wish to avoid certain things that can make your hands feel uneasy or if you assume that they can be easily removed whenever they stuck to your clothes, it is vital to remember that there are still other items that you may use at any point of time.

It is vital to remember that you are able to create nice prints on them with the help of a brush. Plus, you can also buy special paints that contain colorful particles and silver foils. If you buy one such thing, it is vital that you should apply a top coat and that you can have a wonderful effect with it. In fact, you are able to create them even if you are unable to draw properly and if you have just started to draw these body parts in the best possible way. This article will highlight on a few such designs that you can create on your own for exclusive decoration.

If you want to create the impact of sunset on these body parts it is advisable that you should mix the orange colored polish with the one with black color effectively. You can also use red color or even pink colored polish on their top for wonderful impact.

If you want to make a floral pattern, then it is advisable that you should use gold polish in order to get desirable results. It is also important to remember that you can also use black polish for this purpose.

You can create wonderful nail design on the white colored paint in the best possible way. You should be able to put on a top coat effectively and your entire effect may be wasted within a short period of time.

If you want to create a sponge effect on these body parts, it is vital that you should use three colours of polishes effectively. Once you complete this task, it is important that you should use top coat as much as you can and that you should be able to seal it in the best possible way.

If you wish to create a nail design that looks similar to that of cup cake, it is vital that you should use a brush, beads, rhinestones and other relevant items. Plus, you may need to use your toothpick in order to create it to the best of your ability.

If you are able to draw beautiful patterns on these body parts it is vital that you should develop one such thing with the help of acrylic paints as well as brush only.

You will be able to make nice shapes with the help of this kind of item in the best possible way. If you want, you can use special plates in order it as quickly as possible. In order to develop this type of effect, it is vital that you should use a sponge and stencil whenever you need.

In order to create rainbow nail design, it is important that you should buy the relevant tools as quickly as possible. You can use dotting tools in order to draw clouds and other beautiful patterns. Plus, you can use special glitter strippers in order to draw rainbows in the best possible way.

Choosing Your Makeup Brushes

Unicorn-Inspired Brushes

 (Photo by: Unicorn Makeup Brushes Set )

You’ll find that most sets of eyeshadow and blushes come with an applicator brush, but these aren’t as useful as a set of real high quality makeup brushes. The tiny brushes you get with most makeup wear out quickly and aren’t that great for applying the makeup. A good set of professional-grade makeup brushes are probably less expensive than you think and are a sound investment.

There are several different options to consider when trying to choose the right makeup brushes. No applicator arsenal is complete without a large brush for powdered makeups. These types of makeup brushes feature a round, thick brush with soft bristles that are designed for applying makeup evenly over the entire face.

A large powder brush should be used as a bronzer, it is sometimes confused with the similar but smaller blush brush. A blush brush is the optimal size for targeted application to specific areas of the face. If you try to use a large powder brush to apply blush you may end up with color in spots you don’t want. A good brush blush will give you both the control and coverage you need.

Most brushes are designed for applying makeup to one’s eyes. Your basic eyeshadow brush tends to have a square shape to the bristles making it perfect for applying to the eyelid and the brow.

When you want to use a variety of makeup affects on the eyes you’ll want to use an angled brush so that you can precisely apply color to the eyelid crease and the outer corners of the eyes. A brush with finer tip is great for applying either eyeliner or a thin line of eyeshadow right above the eyelashes for a stunning look.

You’ll also want to look for brushes that are made with natural fibers, these will not fall apart as easily and will be easier on the skin. Wash your makeup brushes in warm water with suds every few weeks, this will eliminate any dead skin cells or makeup residue that has built up.

You’ll also want to keep makeup brushes in a clean bag or container in an environment that is free of moisture, store them somewhere they won’t be crushed by other products. If any of the brushes in your set wear out they won’t be expensive to replace either. A good set of makeup brushes will do wonders for how you apply makeup without breaking the bank!

The secrets of a business woman


(Photo by:White Matte Nail Polish)

I work in a bank and as you can probably guess I am required to keep certain company rules concerning my behavior and appearance. Luckily I use manicure as stress relief. My favorite hobbies are dancing and beach walks, manicure joined them just a few years ago, when my beautician, who up to that moment had only cleaned and shaped my nails, offered to draw on them. Until then I had only worn single color nail polish, mainly burgundy, so I was impressed by what this girl did to my nails. As I was watching her work I thought to myself, this can’t be very difficult. I decided to give it a try. It turned out not as easy as I supposed it to be. Fortunately I have the ability to write with both hands, so this made drawing my own nails a little bit easier. After a while it occurred to me that if I use materials and tools for finer figures, my nails will look much better.

Where do you get manicure ideas?

Lots of places! The best place of all is probably the internet, because it abounds with so many patterns that we can never use them all in a single lifetime. If you are a creative person and like to be original, you can come up with your own patterns. This is not as hard as it sounds, because the world around us reveals new ideas at every step, you just have to be more observant. When you look at the things around you with the perspective of manicure, you will find many things that will look good on your nails. This way you can also decorate your clothes – t-shirts, pants, etc.

How do you realize your ideas at home?

You cannot do it without the right tools. I use very thin permanent markers. They are very practical, can be found in almost every color and using them you can make very precise drawings, but you always have to use a clear top coat of polish.

What colors do you prefer?

Colors are subjective to personal preference. Aside from my own personal preference I choose the colors to use on my nails according to my outfit and the degree of formality of the event I’m preparing for. As a business woman, I can’t often afford to wear the bright vibrant colors I love so much, but I find replacements. More often than not I use a neutral color for base anyway.

What kind of manicure would you give yourself for Christmas?

My favorite Christmas details are stars and bells. Combined with glitter they help set the festive mood. Christmas tree shapes are also nice, but that’s according to me. You can find your own way to express your holiday spirit.

Clever Solution For Broken Nail

fix broken nail

It can happen to all of us – a broken nail. It is painful and ugly, in other words: Beauty disaster, especially when you just have managed to grow long nails.

Today I will show you how to fix a broken nail, without the need of cutting it down. Take a look at the steps:

  1. First you will need a few things:

  • an instant glue;

  • nail file;

  • small piece of tissue;

  • top nail file;

  • base coat;

  • colored nail polish.

2. First, file the top layer of the nail with the top file in order to create a proper surface for the glue. This way it will stick better.

3. Then apply a little bit of the glue on and in the crack and apply the tissue immediately. Apply another layer of glue on the tissue and adjust the crack in order to become smooth and strong.

4. Now shape your nails the way you do usually.

5. Apply base coat and then cover them with colored nail polish in order to hide the crack.

6. Secure the color with a gel-ish top coat. It is stronger than the regular one.

All done! Your nails are fixed and strong now.

If you want to prevent the nails from breaking too often, you have to choose the oval nail shape – it is the most stable one. While the square nail shape breaks often, because the corners are pointy and the chance of hitting these corners is too big.

No matter which nail shape you choose to achieve, just make sure that you are grooming your nails often in order to look good and professional. No one likes ugly and cracked nails and nail polish. This one time a guy in the bus station told me that my nails are ugly and I felt awful, so make sure that doesn’t happen to you by spending enough time on maintaining beautiful nails.

Don’t forget to visit us for more useful tips and great ideas. Have fun!