Earthquake Ampsan Francisco Ciencia (VI): Dark motives

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You're right. I'm Emma, the maid of Mr. Brunshart. Oh, do not worry about the luggage: Otto will take you to the guest room.

(Before reading further, please, you must see this video ¬ ¬ U)

The maid accompanied the womanLXC

Following the presentations and a brief chat with all members of the family, and given the hour, Amos Brunshart Jessica Fletcher suggested teaching rooms of the house before dinner. When told that the meats were ready, the millionaire accompanied his friend to the main dining room, and made her take a seat while he went to get more appropriate clothing. One after another came straggling into the room the wife, son and daughter. Emma, the maid, and had served the dinner, but not his master did not appear. Apparently, it is often distracted by anything and lose track of time, so it was not unusual tardbroil to appear. Anna, wife, suggested they begin to eat all, which they did. In the kitchen, the service also set out to do the same.

But tonight he was back too. Sylvie, the daughter of Mr. Brunshart, decided to go get it. But soon came a cry from the young. Everyone was running into the room Brunshart ... where he lay in bed, they discovered the lifeless body of millionaire.

(Which, I must say, holds the record for having more than five minutes to JessicaFletcher at home and have not yet died ¬ ¬ U)

Given the involvement of the rest of those present, Otto, Butler, ran to call the authorities. Police arrived shortly and, as the darkening of the lips of man, it was determined that the cause of death was asphyxiation, likely blocking the airway with an object . After examining the crime scene under the watchful gaze of Jessica Fletcher and its many questions and accusations, the police failed to find any evidence. Hair and cellular desquamationthat the Lord had always treated with respect, and always paid them the day I played. Otto had years of service to the Brunshart, and Emma had come when the Lord visited the orphanage where he had grown and carried. The driver had been hired recently, and thanks to this job was able to pull up their children.

The family did not seem to raise suspicions. First, the Ames fortune came largely from his wife, so that the economic motive was discarded. Even si those who would inherit the fortune were the children, "murdered him had not been too much," said the wife.

the end, everyone decided to retreat to their rooms. But that last comment from the wife, together with statements of service, had a light bulb suddenly turned on in the mind of Jessica Fletcher. A sly, had sneaked into the bedrooms of various family members and had recovered had loose hair brush or on the beds. He also asked the service ifcould you provide a sample of cells from your face rubbed in the inside of the cheek with a swab cotton. If his suspicions were true, it would be easy to unmask the culprit ...

1.

chain reaction (PCR)

For you were calling the insane asylum to such entry, it will have served to give you

The technique takes into account that

DNA polymerase requires two things to replicate: a mold and an end 3 ' free on which to start. Thus, the following excerpts, the first is not replicable (missing both), while the second one it is, because, say, DNA polymerase can "fill" the hole is missing:

5 ' - TAAGTCCCTGTGTTACTAG -

3'

ue join one of the chains and offer an end 3 'free by which the polymerase can begin copying. Moreover, the idea is to use two primers, with extremes 3 '

looking in opposite directions, which will serve to amplify what you have between them.

Here are the different stages in which the technique is based cartoons to be understood, because if not the horror ¬ ¬ U

0) Obtaining samples

EvI, blue lines, and the primers are red arrows to indicate which way "look."

3) Elongation Here comes into play and DNA polymerase . If you look, the construction has been offered that you need to copy polymerase: a mold (blue) and an end for which start (red arrowhead). Often used DNA polymerase

thermophilus bacteria called aquaticus

, known as Taq polymerase because it withstands high temperatures like we have throughout the process. This time, for 1-1.5 minutes at 72 º C , we allow the enzyme to do its function. Taking the bases that we have added to the PCR tube, and magnesium, necessary to perform well, "fills the gap:

When finished filling, what remains is a new copy of each of

chains, which, if you look, we already have 2 and 1, copies of the fragment of interest. CHT

MLXC The grace of all, these three steps automatically by the cycler, are repeated about 30 or 40 times. In the second cycle, for example, and the following happens (and we will take him only one of the two copies that have shaped us, otherwise we never ^ ^ U will have to guide you through the colors):

And the third:

We see that after the third cycle we just amplify cortito fragment corresponding to the area interests us. Given that the expansion as the first and second cycle will be a small minority, we can say that each cycle we multiply by 2 the number of copies of the region of interest we have.

Thus, 30 cycles of PCR, will have billions of copies from one original copy! This is, of course, the main use of this technique from a tiny amount of DNA (for example, a single cell or few of them on a hair), can amplify a region often n of interest. Most appropriateLante see what regions of interest of concern.

2. DNA electrophoresis in agarose gel

DNA electrophoresis in agarose is a molecular biology technique that allows us to separate different fragments DNA long as they are.

The agarose

is a type of sugar that is capable of polymerizing. Thus,A is a molecule that has a negative electrical charge

. Therefore, under the action of an electric field will be able to move toward the positive the same as in the case of the magnets. And it will.

After loading the gel, cover and is connected to the mains (for the spouts you see in the picture). Gradually, the DNA sample is migrating through the gel towards the positive pole of the basin. However, as the agarose gel is a sponge, following things happen:

- The shorter pieces of DNA , being smaller, can squeeze better through the pores of the gel and, therefore, faster

advance.

- The pieces of DNA

longer, to be larger, have more difficult to slip and, therefore, move more and more

l

ent.

After a while, we pieces of DNA separated by size . Using a special dye, radioactive compounds or phosphors, we can see how far they have come our fragments, and visualized on the gel blandiblub that dark bands. Thus, the typical appearance of an electrophoresis gel run after it:

- The CHTMTC, CAA, CA, etc, etc), even in the unlikely event that two people were available for the same number of repetitions of one of them does not necessarily have the same number in another repetitive sequence.

b) The number of repeats is inherited . Since

receive one chromosome of each type of father and one from the mother, we have a number of repetitions from this and another of the latter.

In outline form, consider the individuals A and B. Suppose there are two hypothetical VNTR, one of them in a certain region & OverhaulVNTR are very low.

[E]: Certain hereditary diseases are caused by an uncontrolled expansion of these VNTR. For example, the average person has to 5 to 50 repetitions of a VNTR (CGG) of chromosome X, but those affected by fragile X syndrome

that number is 200. Other such diseases include Huntington disease

the myotonic dystrophy, or Friedreich's ataxia .

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Now we should be able some technique to visualize what are the VNTR length of each individual , because although the schemes we see clearly, this is not looking at him to discover U ¬ ¬ face indeed: We will need to load a agarose gel electrophoresis can be viewed.

In these cases, patterns are used VNTR of which we know the number of repetitions, provided by commercial companies - , &ur tale of intrigue (which I hope, like me, you have not forgotten that we still hung ¬ ¬ U).

Without losing a moment, Jessica locked the door of his room, sat on the bed and opened ; her purse. Took him a thermocycler, a Cuba electrophoresis, several bottles of chemical reagents and PCR tubes. Never left home without them. It was also a white coat that her friend, the lovely Maggie Thompson, Had given him at a tea party in Cabot Cove who organized the previous spring.

Cautiously submitted hair samples and buccal mucosa in a manner to extract the DNA. When he had completed, introduced the liquid in small tubes of PCR, with primers for a VNTR of chromosome 13 and other substances required for the chain reaction. After that, the thermal cycler programmed for 30 cycles of denaturation-hybridization-extension, which would take him an hour. Meanwhile, the diligent wife and room & imp; nbsp;

Can not sleep, dear? - Asked Mrs. Fletcher with incisive innocence. Is it remorse for killing her husband will not let you sleep? -

what is based to make such accusations? And besides, what proof do you have? Angry and shocked, "said the wife of the deceased. -

No sketch of the members of the family, which had scored VNTR repeats in every person. After apologizing for having taken the liberty of analyzing their genetic material, and with a "do not understand what you mean by this," Jessica Fletcher began to explain what he had discovered.

- The number of repeats of a VNTR is hereditary, my dear. Thus, any child should have a repetition of the father and the other of the madre. But one thing is obvious. And you do not watch very closely: None of their children are also Amos. None of them has neither the 3 nor to the 7 repetitions Amos inherited from his father and mother, respectively, but both have their reps of 5 and 2. Probably had this planned from the beginning: to kill her husband and married again, after the mourning of rigor, with her lover, the biological father of their children. Maybe it was taking advantage of a mother and be recognized as a feisty widow who managed to overcome the terrible murder of her husband. After all, for you Amos has always been an opportunist who fell in love with his fortune m & aacute; s to you, but there was nothing further from reality.

Blinded by the truth and afraid to go to jail, the black widow rushed against the elderly. Regardless, unfortunately for her, which at that moment the police arrived. After the arrest, the "children" Amos had to fit the truth. Jessica Fletcher was again packed, saddened by the death of his friend (who had obviously led to jinx herself ¬ ¬ U). At the exit, Emma, the maid, helped him with his bags. -

I am sure that Mr. also thanks you, wherever you are. We must find a new home to serve, but I doubt that any did serve me as Mr. ...

- You'll see how yes, dear. - Jessica Fletcher said. And if they found nothing, Evelyn, the pastry of Cabot Cove, was looking for an apprentice of the trade ...

The girl smiled, and Jessica went into the car for the airport. For a moment, cast a last glance at the girl who took leave from the front door.

A last look at the only true daughter of Amos Brunshart who were in the house.

Well, that's all. I hope you liked the story, invented at a time while studying for an exam in entering this kind of thing ¬ _ ¬ UY yes, technically this has been a fanficmp; iacute; to the pattern repeats VNTRs submit the alleged parents and children cases. With a single VNTR can say "that sure is not the parent," but not "that yes it is ": it would take 4 or 5 studies VNTRs of different chromosomes and see the matches.

I must also comment

other applications of the VNTR:

-

study of forensic samples: To determine the blood of a victimesteem is really yours.

-

tissues Study: To demonstrate that cells of a patient are normal, or if, after tumor, have changed. - detection of diseases related to expansion of VNTR : The average person has fewer repetitions (short fragments) and the patient has excessive (very long fragments).

Well, it is