Dr Lalji Singh - CCMB

able to infer generic affinities among different species/genera of crocodilians,
which are in agreement with the consensus phylogeny reconstructed using
various other approaches together. This observation is of great importance as it
establishes, for the first time, the potential utility of this molecular technique in
the study of evolutionary relationships of plants and animals. Dr Lalji Singh is
presently using this for wild life preservation and better management of
endangered species in our zoos and also for identification and isolation of
genes for useful characters in silkworm races. This technology is also being
used for medical diagnosis.
3. Studies on molecular basis of sex determination
Isolation of highly conserved sex chromosome-specific satellite DNA, 'Bkm', from the
female Indian snake, the Banded Krait, made the beginning of the understanding of
the molecular basis of sex-determination, which is one of the most important
unsolved problems in modern biology. Now, this has also become the basis of our
understanding of sex-reversal in humans. For the first time, Dr Lalji Singh and his
colleagues have reported a unique case of sex reversal of an individual who has the
47,XXY chromosome constitution but a female phenotype. This finding of the
occurrence of XXY female with normal SRY, ZFY and SOX9 genes testifies the
involvement of other gene(s) in sex determination.
4. Sex and germ cell-specific Bkm-binding protein
Bkm sequences in snakes, Bkm-associated Y-specific sequences p102d(2) in
human and M34 in mouse, are interspersed amongst other sequences along the
entire length of the sex-determining chromosomes. The consensus sequence in
these sex chromosome specific repeats is the conserved tetranucleotide repeat
GATA component of Bkm. Dr Singh and his associates have purified a sex- and
germ-cell-specific protein from snake ovary, which specifically binds GATA repeats
of Bkm. This may be the potential signal responsible for the decondensation
(activation) of the sex-determining chromosome. In silkworm Bombyx mori BKMbinding
protein (BBP) is expressed predominantly in pupal ovary suggesting its
probable role in bringing about coordinated conformational changes in chromatin to
activate genes present in associated chromosomal domains.
5. Wildlife Conservation- Genetic variation in Asiatic lions and Indian tigers
Previous reports suggested that Asiatic lions and tigers in India are highly inbred and
exhibit very low levels of genetic variation. Dr Singh and his colleagues' analyses on
these species have shown much higher degree of polymorphism than reported.
Analysis of 38 Asiatic lions, which exist as a single population in the Gir Forest
Sanctuary in India, revealed an average heterozygosity of 25.82%. In Indian tigers,
microsatellite analysis and multilocus fingerprinting on a population of 22 individuals
revealed a heterozygosity of 22.65%. Microsatellite analysis has enabled the
identification of the pure Asiatic lions from the hybrids. Similar analysis of hair
samples enabled them to identify hybrids of Indian and Siberian tigers. Microsatellite
analysis was performed on 50-125 years old skin samples from museum specimens.
Their results show similar levels of genetic variability as in the present population
(21.01%). Studies of Asiatic lions and tigers have further helped in identifying
individuals with high genetic variability which can be used for conservation breeding
programmes. Recently Dr Singh’s group isolated highly polymorphic microsatellite
loci from a partial genomic library of the Asiatic lion, which show much higher levels
of variation.
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