I think there is a problem in my understanding on the numbering used
for base pairs in a chromosome. Can you please clarify my query? In short,
the query is "Whether the negative strand of a chromosome is numbered in
ascending order just like the positive strand, or in the descending order?"

To be descriptive, the bases in the positive strand is numbered as
[1-2-3-...-maximum_chromosome_length]. Is the complementary negative
strand also numbered in databases like this or as
[maximum_chromosome_length- ... -3-2-1]?

I have retrieved a sequence from the base 1 to 100 in positive
strand of chr 1 and also the same from negative strand and I have seen
that they are completely different.

Because either the numbering is:
+ strand: 1 2 3 ... x
- strand: 1 2 3 ... x

or is:
+ strand: 1 2 3 ... x
- strand: x ... 3 2 1

Which one is correct? what are you using?

> Hi Tapas,
>
> My apologies - the browser is looking for default values to enter into
> the position text box. The link below should work for hg18,
> chr6:1000-1500:
>
> http://genome.ucsc.edu/cgi-bin/hgc?g=getDna&i=mixed&c=chr6&l=999&r=1500&db=hg18
>
> Best,
> Mary
> ---------------------
> Mary Goldman
> UCSC Bioinformatics Group
>
> On 6/24/10 4:57 PM, Tapas Bhadra wrote:
>> Sir,
>>      Thanks for your reply. But when I am trying to go into the site it
>> shows that "hashMustFindVal: 'c' not found " in that page.
>>
>>     Pleaes reply at your earliest convenience.
>>
>>     Thanking you,
>>                                         Tapas Bhadra,
>>                                         Senior Research Fellow,
>>                                         Indian Statistical Institute,
>>                                         Kolkata,
>>                                         India
>>
>>
>>
>>> Hi Tapas,
>>>
>>> Whether you obtain the DNA sequence through our downloads page or the
>>> "DNA" button in the blue bar when you are viewing an assembly, it
>>> always
>>> defaults to the positive strand. The easiest way to get DNA for a short
>>> sequence, such as the one you mentioned in your email, is to use the
>>> "get DNA" feature (http://genome.ucsc.edu/cgi-bin/hgc?g=getDna). Simply
>>> type in the coordinates and click the "get DNA" button. Note that you
>>> can also get DNA from the negative strand by clicking the "reverse
>>> complement" check box.
>>>
>>> I hope this answers this question and both of your questions that were
>>> emailed to our team yesterday. Please feel free to contact the mail
>>> list
>>> again if you require further assistance.
>>>
>>> Best,
>>> Mary
>>> ------------------
>>> Mary Goldman
>>> UCSC Bioinformatics Group
>>>
>>> On 6/24/10 4:33 AM, Tapas Bhadra wrote:
>>>
>>>> Dear Sir,
>>>>      I am a research fellow at the Indian Statistical Institute,
>>>> Kolkata,
>>>> India.
>>>>
>>>> I have downloaded the sequences of all the chromosomes. Can you please
>>>> inform me that if I need sequences from 1000bp to 1500bp of chr 6 from
>>>> +ve
>>>> strand and also from 1000bp to 1500bp of chr 6 from -ve strand, then
>>>> how
>>>> will I obtain those information. Will they be same?
>>>>
>>>> Is your database strand specific? If yes then which strand it
>>>> annotates
>>>> for the sequence and for this strand specific database how will we
>>>> obtain
>>>> sequential information from the reverse strand?
>>>>
>>>> Pleaes reply at your earliest convenience.
>>>>
>>>>     Thanking you,
>>>>                                        Tapas Bhadra,
>>>>                                        Senior Research Fellow,
>>>>                                        Indian Statistical Institute,
>>>> Kolkata,
>>>>                                        India
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>>>>
>>>> _______________________________________________
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>>>
>>>
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