Search

The aim of the present work was to explore the intriguing association of maternal folate regulator gene polymorphisms and mutations with the incidence of chromosome 21 nondisjunction and Down syndrome birth. We tested polymorphisms/mutations of DNMT3B and RFC1 genes for their association with meiotic errors in oocyte among the 1215 Down syndrome child-bearing women and 900 controls. We observed that 23 out of 31 variants of DNMT3B and RFC1 exhibited an association with meiosis II nondisjunction in maternal age-independent manner. Additionally, we have reported 17 novel mutations and 1 novel polymorphic variant that are unique to the Indian Bengali speaking cohort and increased odds in favour of meiosis II nondisjunction. We hypothesize that the risk variants and mutations of DNMT3B and RFC1 genes may cause reduction in two or more recombination events and also cause peri-centromeric single exchange that increases the risk of nondisjunction at any age of women. In silico analyses predicted the probable damages of the transcripts or proteins from the respective genes owing to the said polymorphisms. These findings from the largest population sample tested ever revealed that mutations/polymorphisms of the genes DNMT3B and RFC1 impair recombination that leads to chromosome 21 nondisjunction in the oocyte at meiosis II stage and bring us a significant step closer towards understanding the aetiology of chromosome 21 nondisjunction and birth of a child with Down syndrome to women at any age.

Mechanism for the generation of attractor in nonlinear systems with hidden attractor is still not understood completely. Since such systems do not possess all the requisite properties related to fixed points (sometimes they do not possess any fixed point at all), it is really difficult to apply usual logic for attractor generation. Under these circumstances we have applied the recent concept of competitive modes to such nonlinear systems. We show that a reasonable explanation can be obtained in this framework when these modes operate in a slightly different manner. In this connection we have introduced a new quantitative measure of competitiveness through the correlation between any two mode functions. Further analysis leads us to topological study of the various periodic and chaotic states with the help of symbolic dynamics and template structure.

Third-order nonlinear dynamical systems with attractors (one with no fixed point and the other with a stable fixed point) are conjugately coupled. It is observed that the combined system gives rise to nontrivial fixed points, and the corresponding long-time dynamics leads to amplitude death. On the other hand, if the coupled system starts from the neighborhood of these generated fixed points, there exists a very novel path to the generation of oscillations. Such a phenomenon is called rhythmogenesis. The characterization of such dynamics is done with the help of bifurcation diagrams and Lyapunov exponents. Another important outcome is an observed bifurcation with respect to the initial condition variation. This last phenomenon may be attributed to the fact that usual route to chaos is absent in the uncoupled system. In the second part of our paper, we have constructed the electronic circuit pertaining to the coupled system, collected the data via NI 6009 DAC, and have shown the existence of the amplitude death experimentally. The case of rhythmogenesis is done similarly, which only requires an extra circuit to fix the initial condition, and was devised in our earlier paper. It has been used to construct a new circuit to detect rhythmogenesis.

Effects of memristor on non-linear dynamical systems exhibiting chaos are analysed both form the view point of theory and experiment. It is observed that the memristive system has always fewer number of fixed points than the original one. Sometimes there is no fixed point in the memristive system. But its chaotic properties are retained. As such we have a situation known as hidden attractor because if it is a stable fixed point then the attractor does not evolve from its basin of attraction(obtained from its stable fixed point) or if there is no fixed point, the question of basin of attraction from fixed point does not arise at all [1, 2]. Our analysis gives a detailed accounts of properties related to its chaotic behavior. Important observations are also obtained with the help of electronic circuits to support the numerical simulations.

A new type of outer synchronization between two distinct networks, composed of different classes of oscillators is investigated with the help of open plus closed loop approach, proposed earlier by Jackson and Grosu. It is further assumed that all the members of the network differ in their parameter values. Asymptotic stability of the zero solution of the error equation is proved analytically. Numerical simulation reveals that the same type of members of the two networks gets synchronized.

The methanolic extract of Aloe vera L. gel was subjected to antioxidant guided fractionation with silica gel column chromatography to screen the potent fraction. The antioxidant capacities of different fractions were evaluated using DPPH radical scavenging assay and correlated with total phenol content. Total phenolic contents of different fractions were determined according to the Folin-Ciocalteu spectrophotometric method. The positive correlation was observed between DPPH radical scavenging assay and total phenolic contents indicating that phenolics in Aloe vera L. gel were fundamental contributor of antioxidant activity. Third pooled fraction was identified as potential fraction with highest antioxidant potential. This fraction indicated the presence of well resolved fluorescent components. Characteristic UV–vis absorption and HPLC analysis indicates that aloin take part in antioxidant potential attributed to aloe gel.

Synaptosomal-associated protein 25 (SNAP25) is an essential component for synaptic vesicle mediated release of neurotransmitters. Deficiencies or abnormal structure or function of SNAP25 protein, possibly arising through genetic variations in the relevant DNA code, has been suggested to play role in the pathology of several neurobehavioural disorders including Attention deficit Hyperactivity Disorder (ADHD) and a number of polymorphisms in the SNAP25 gene has been studied for association with the disorder. In the present investigation, for the first time association between ADHD and six SNAP25 polymorphisms, rs1889189, rs362569, rs362988, rs3746544, rs1051312, and rs8636 was explored in eastern Indian population. Subjects were recruited following the Diagnostic and Statistical Manual for Mental Disorders-IV. Genomic DNA isolated from peripheral blood leukocytes of ADHD probands (n = 150), their parents (n = 272) and ethnically matched controls (n = 100) was used for amplifying target sites. Data obtained were subjected to population- as well as family-based analyses. While case-control analysis revealed lack of any significant difference for alleles, family-based studies revealed a mild over transmission rs3746544 'T' and rs8636 'C' alleles (P = 0.05 and 0.03 respectively). Haplotypes formed between rs362569 "T", 362988 "G", rs3746544 "T", rs1051312 "T" and rs8636 "C" in different combinations showed statistically significant transmission to ADHD probands. Excepting rs3746544 and rs8636, all the tested sites showed very low linkage disequilibrium between them. Data obtained in this preliminary study indicates that rs3746544 'T' allele may have some role in the disease etiology in the studied Indian population.