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Author Topic: Can Frozen Sperm, Bacteria be defrosted and then refrozen ?  (Read 6689 times)

Offline neilep

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Dear All,


Credit BBC




As ewe may or may not know, sperm, bacteria etc can be frozen for later use.....does this also mean that once defrosted they can be frozen again and then defrosted over and over ?

I assume the survival rate is not 100% but was just wondering how many times they could go through the process !


Thanks


Neil
Frozen Sperm and Bacteria Enquirer






« Last Edit: 04/04/2008 15:23:28 by neilep »


 

Offline Seany

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Well atleast it seems to work.. but I'm not sure whether it can be frozen and defrosted infinite number of times..

The baby girl born using frozen sperm from father killed by cancer FOUR years ago

http://www.dailymail.co.uk/pages/live/femail/article.html?in_article_id=538429&in_page_id=1879
 

Offline Seany

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How is the sperm actually frozen?

Frozen sperm must be stored in extremely cold temperatures (-196 F), but in order to insure that the fewest possible sperm are damaged(So I am assuming here that few sperms do get damamged, but not much is following this specific procedure!), the freezing must be gradual. Generally, the following procedure is followed:


1. If the sperm hasn't been previously tested, a comprehensive semen analysis should be performed on the first specimen in order to give you a complete picture of your sperm quantity and quality. Make sure that your sperm bank conducts a thorough semen analysis before banking. This will give you significant information on the quality of the sperm.


2. Each subsequent specimen is analyzed prior to freezing to assess total number of moving sperm.


3. Immediately after the specimen is analyzed, it is divided into smaller batches and transferred into vials for freezing. A special compound (a cryoprotectant) is added to aid the freezing process.


4. The test tubes are gradually frozen in liquid nitrogen vapor. After 30-60 minutes they are transferred into liquid nitrogen tanks for permanent frozen storage.


5. After a minimum of 48 hours have elapsed from the time of the initial freezing, an initial "test sample" is thawed and tested again to ascertain from each specimen how well the sperm survived the freezing. After the banking is complete, the results may be sent to you, as well as possibly discussed with your primary care physician. This information will be important to determine which specimen vials to thaw for an insemination.

Each sample is stored in its own specially marked storage unit. Some cryobanks split the specimens, storing half of any individual's specimens in two separate nitrogen tanks in case of tank malfunction. Some may actually store the two tanks on separate physical sites in case of an unforeseeable disaster to the building in which a tank is stored. The nitrogen tanks are checked daily for temperature and liquid nitrogen leakage.




So I am assuming here that it can be defrosted a good number of times, but not infinite!!
 

Offline neilep

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #3 on: 04/04/2008 15:24:16 »
So , they don't just whack it in the freezer section at Iceland then ?
 

Offline JnA

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #4 on: 04/04/2008 16:01:45 »
Yes, but motility and quality decreases at each refreeze.
Studies have shown that after a first, second, and third thawing cycles the ratios of motile:nonmotile viable sperm were 1:1, 1:4, and 1:7, respectively.


When 'they' freeze semen they usually will divide it into batches, so several fertilisation attempts can be made from the one sample.

This depends on the reason for freezing and availability of fresh samples.

 

Offline Make it Lady

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #5 on: 04/04/2008 16:39:27 »
So , they don't just whack it in the freezer section at Iceland then ?

Next to the ice pops.
 

Offline MayoFlyFarmer

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #6 on: 04/04/2008 17:41:18 »
So , they don't just whack it in the freezer section at Iceland then ?

This is an example of a post that I totally don't get do to living on this side of the pnd.

Is Whack" brit-slang for sell?  And is "Iceland" a chain of grocerie stores over there???
 

Offline Make it Lady

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #7 on: 04/04/2008 17:56:17 »
Whack is to 'put into' in a slap dash manner. Iceland is a supermarket selling mainly frozen food. Oh and ice pops are frozen Popsicles.
 

Offline MayoFlyFarmer

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #8 on: 04/04/2008 18:07:00 »
To answer your question neil, it really depends on the cell type.  Pretty much any type of cell can be frozen and revived, but they don't all respond the same to the process.

You mentioned bacteria, they can actually be frozen (and thawed and frozen and thawd, etc. too for that matter) very easily.  You can actually just stick them in the freezer and walk away and they'll be fine.  No special procedure needed. its a colder freezer than your typical house-hold freezer, (-80C vs. -20C) that we store them in, but they are such tough little cells, they pretty much survive anything.

Eukariotic cells (including human) are a different nature though.  They have to be frozen down just right of you want viable cells when you thaw them out.  They make special containers and machines that very accurately drop the temperature at a rate of 1 degree C per minute.  Any faster or slower than that and you get ice crystals forming from the water inside and around the cells that act like tiny little knives and shred the cells' membranes.  They then need to be stored in liquid nitrogen tanks.  You also have to freeze them in a chmical called DMSO (dimethylsulfoxide) that helps the cells withstand the freezing and thawing processes, but is very toxic to them when they are at room-temperature, so it has to be added RIGHT BEFORE freezing them, and removed AS SOON as they are thawed.

Any cell that can be frozen, and then revived could technically be re-frozen and re-revived.  However as you pointed out, you do lose a good percentage of your cells even under careful freezing conditions.  Some types of human cells can grow and divide in culture.  Some of them that we work with in the lab have been modified so that they can divide infinite times in culture.  The way that we deal with these cells is thaw them out wehn we need them, use them, grow more up when we're running low, and then freeze them down to store.  However, even some of these cells change some of their characteristics after multiple rounds of freeze/grow/thaw (or passages as we refer to that whole cycle), you we have to be careful to try and freeze down several vials at the earlier stages, and only use those early passages for aplications when we need cells with those properties that can be effected by this.  Obviously, cells (such as sperm) that don't grow in culture, or even cells that only divide a limited number of times in culture, can't be repeatedly frozen and thawed.  Not because its not possible, but because you lose so many of them with every round, and there's no way to expand them in between.  So they are typically frozen down in one big batch, and thawed as they are needed.  Obviously, they are a much more precious resource than a cell line that can be expanded infinetly. 

hope that sheds some light on the topic.  I'm going to go thaw out a bacterial stock that I froze down a couple months ago and need again today.  :)
 

Offline MayoFlyFarmer

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #9 on: 04/04/2008 18:07:52 »
Whack is to 'put into' in a slap dash manner. Iceland is a supermarket selling mainly frozen food. Oh and ice pops are frozen Popsicles.

yeah, we have ice pops here.  they are a type of popssicle that somes in a long plastic tube/bag instead of on a stick.
 

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Can Frozen Sperm, Bacteria be defrosted and then refrozen ?
« Reply #9 on: 04/04/2008 18:07:52 »

 

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