Page 60 - Mouse Molecular Genetics

Full Abstracts
Program number is above title. Author in bold is the presenter.
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knockout mice. Efforts are underway to employ lentivirus-mediated gene delivery method and test these findings in vivo in
arrhythmic Cry1-/-:Cry2-/- mice, at both tissue (SCN) and behavioral levels. Taken together, our results demonstrate that the
CRY1-PHR(313-426) domain is critical for clock function and functionally differentiates CRY1 from CRY2. These findings also
provide novel insights into functional evolution of photolyase/cryptochrome family of flavoproteins.
74
Evaluation of Genetic And Genomic Similarity of Inbred Strains of Mice Employing Microsatellite Markers. Mahadeo
Kumar
1
,
Sharad Kumar
1
,
Akshay Dwarakanath
1
,
Dinesh Purohit
1
,
Daya Shankar Upadhayay
2
. 1)
Animal Facility, CSIR-Indian
Institute of Toxicology Research, M. G. Marg. Lucknow, India; 2) Animal Facility, Central Drug Research Institute, Lucknow.
The present investigation details an assessment of genetic relationship among five inbred strains of mice i.e. Balb/c, C57BL/6,
AKR, NZB and AJ maintained at CDRI for long time since their inception to the country. The genomic DNA was extracted from
25
samples, five from each strain and processed by ten microsatellite markers for genotyping. Polymorphism was detected for all
these studied loci. Summed over these ten informative microsatellite loci, the number of detected alleles ranged from 2 to 5 per
locus. The microsatellite primers D1Mit17 and D4Mit54 were found to be the most informative, as they showed maximum
number of alleles (5) in the studied samples. The strain AKR showed the maximum genetic similarity (52.70%) with NZB, while
the Balb/c and AKR strain showed the least genetic similarity (10.21%) to C57BL/6 for the studied loci. A combined dendrogram
based on Neis genetic distance using UPGMA method was constructed, which revealed that black coat colour mice C57BL/6 and
NZB were clustered with AJ and AKR respectively. These results indicated that microsatellite markers are valuable marker for
study of geneology and evolutionary biology of different strains of mice.
75
Use of closely related mouse substrains to clone a QTL for psychostimulant response. Vivek Kumar
1,4
,
Gary Churchill
2
,
Fernando Pardo-Manuel de Villena
3
,
Joseph Takahashi
1,4
. 1)
Dept of Neuroscience, University of Texas Southwestern Medical
Center, Dallas, TX; 2) The Jackson Laboratory, Bar Harbor, ME, USA; 3) Dept of Genetics, UNC-Chapel Hill, Chapel Hill, NC,
USA; 4) Howard Hughes Medial Institute.
Identification of QTLs at the single gene or nucleotide level has been difficult due to low mapping resolutions achieved by
traditional F2 or N2 mapping approaches. Even when intervals are narrowed, frequently there are confounding numbers of
polymorphisms within the region of interest making identification of a single gene or nucleotide difficult. One alternative
approach is to use closely related mouse substrains that have high phenotypic but low genotypic variance. Due to the high degree
of relatedness between substrains, there should be limited polymorphisms within the QTL interval allowing for the identification
of the causal gene or even nucleotide. Here we use two C57BL/6 substrains, C57BL/6J from Jackson Labs and C57BL/6N from
NIH, to map and clone a QTL for psychostimulant response. We characterized the parental substrains, F1 and 250 segregating F2
progeny for open field, psychostimulant response and circadian behavior. Using bioinformatic analysis and the Mouse Diversity
Array, we developed a SNP marker panel that can be used to map QTLs between several C57BL/6 substrains including
C57BL/6Cr, C57BL/6Tac and C57BL/6NJ. This marker panel was used to genotype the F2 cross and map a single locus
mediating cocaine response (LOD = 6.4). Using next generation sequencing technology on the ABI SOLiD platform we
sequenced the entire genome of C57BL/6N. Surprisingly, there is only one non-synonomous polymorphism between C57BL/6N
and C57BL/6J within the 1.5 LOD support interval of the psychostimulant response QTL. Biochemical analysis reveals this
polymorphism destabilizes the protein leading to the behavioral difference between the two substrains. Our data will be of
interest to the general mouse community because embryonic stem cells from B6N are being used for the Mouse Knockout Project
and behavioral and genetic differences with the reference strain have not been thoroughly documented. Our approach will be of
interest to the QTL community since there are over 40 documented C57BL/6 substrains, including 20 that are commercially
available, and in addition there are large numbers of C3H/He, BALB/c, and DBA/2 substrains, many of which have known
phenotypic differences and become amenable to the approach we have piloted here.
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The regulation of gene expression in a cell via DNA- lipids complexes formation. Vasily V. Kuvichkin
.
Mechanisms of
Reception, Institute of Cell Biophysics, Russian Ac. Sci., Pushchino, Moscow oblast, Russian Federation.
We propose new mechanism of regulation of gene expression and consider the reason of many diseases as failure of such
regulation. The understanding of the nature of cancer is impossible without an accepting the basic role of DNA-lipids complexes
(
DLC). In accordance with our model (Kuvichkin, J. Membr. Biol., 241, 2011, 109-16) DLC are formed in the chromatin areas
with three-stranded hybrids: DNA- low molecular weight RNA (lmwRNA) at their interactions with the nuclear envelope. The
triple helix unwinds during interaction with nuclear membrane forming a classical R-loop: DNA-RNA hybrid and a single-
stranded DNA. The temperature of this transition is considerably lower than the temperature of DNA melting that result in the
preferential attachment of triple-stranded hybrids to the nuclear envelope.The number of DLC determinate the set of genes
attached to nuclear envelope. Single- stranded DNA in DLC is the site of transcription initiation. The result of such interaction is
nuclear pores which thereby serve as sites of initiation of transcriptions in a cell. Therefore, the attachments of any gene to a
nuclear envelope result in enhanced level of expression of this and neighboring genes. The structure of interphase chromatin
cannot be considered without taking into account its interaction with nuclear pores. Current models of nuclear architecture concur
that nuclei of multicellular organisms contain chromosome territories (CTs). DNA is attached to the nuclear pores, forming the
big intranuclear loops of DNA. As we proposed early, DNA-membrane complexes are site of transcription initiation. This means