Patterns of Heat Stability Polymorphism at Acph Locus in Indian Natural Populations of Three Drosophila Species

Parkash, Ravi,Sharma, Manju,Sharma, Suman 한국유전학회 1991 Genes & Genomics Vol.13 No.4

Isofemale lines derived from Indian natural populations of Drosophila ananassae, D. takahashii and D. nepalensis were analysed through horizontal starch gel electrophoresis as well as post-electrophoretic heat denaturation technique for genetic variation at acid phosphatase locus. Allozymic data revealed nearly uniform patterns in D. takahashii and D. nepalensis populations while latitudinal variation was observed in D. ananassae. The contrasting patterns of allozymic variation in three Drosophila species concur with the niche-width variation hypothesis.

Perception of MBBS students to “flipped class room” approach in neuroanatomy module

Parkash Chand,Venkatesh S. Madhugiri,Raveendranath Veeramani 대한해부학회 2015 Anatomy & Cell Biology Vol.48 No.2

A flipped classroom is a learner centered approach in which the learner is responsible to attend the class with basic understanding of the subject to fully participate and engage in discussions. The aim of this study was to evaluate students’ perception of flipped classroom approach for neuroanatomy module and assess the impact on their performance and attitudes. The subject chosen to evaluate the flipped classroom model for first year medical students was clinical neuroanatomy. One hundred and thirty first year medical students participated in the study module. Students were divided into five groups and five case scenarios pertaining to various clinically relevant regions of the neuraxis, with varying anatomical complexity were generated. The pre- and post-tests were designed to specifically test the declared learning objectives of the session. The perception of the students regarding this model of teaching and learning was also evaluated. Eighty-six percent of students felt that the flipped classroom approach was better at fulfilling the stated learning objectives than the conventional didactic teaching, 92% felt that the work-sheet with questions provided prior to the class enabled a better understanding of the subject and 87% were of the opinion that the web sources with references kindled a greater interest to read as compared with didactic lectures. The paired t test showed highly significant differences between the pre and post-test scores. Student response to the flipped classroom structure was largely positive, indicating it to be an approach worth pursuing in future years.

Ethanol Tolerance and Adh Polymorphism in Indian Natural Populations of Zaprionus Indianus

Parkash, Ravi,Shamina,Vashist, Minakshi 한국유전학회 1992 Genes & Genomics Vol.14 No.4

Ten Indian geographical populations of Z.indianus collected along 20˚N latitudinal range, revealed significant clinal variation at the Adh locus and Adh^F allelic frequency correlated significantly with increase in latitude. The abundance of secondary alcohols in the southern Indian tropical and humid environment seemed to exert selective pressure favouring higher frequency of Adh^S allele in Z.indianus. Latitudinal patterns of ethanol utilization as well as ethanol tolerance were observed in the larval and adult individuals of ten geographical populations of Z.indianus. The parallel occurrence of latitudinal variation at the Adh locus as well as ethanol tolerance in colonising populations of Z.indianus could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.

Allozymic Polymorphism in Indian Colonising Natural Populations of Zaprionus Indianus

Parkash, Ravi,Yadav, J P 한국유전학회 1992 Genes & Genomics Vol.14 No.4

Twelve Indian natural populations of Z. indianus. collected along 22˚latitudinal range, were analysed electrophoretically for allozymic variation of seven gene-enzyme systems. Interestingly all the seven Est loci were found to be highly polymorphic in all the populations of Z. indianus. Except Mdh-2 all the fourteen loci revealed extensive polymorphism. The Indian continental populations of Z. indianus revealed higher genetic similarities on the basis of Nei's genetic indices. The genetic structure of Z. indianus populations were characterised by significantly higher values of genetic indices as compared with other sympatric colonising Drosophila species from India; extensive inter-populational genotypic as well as allelic frequency heterogeneity; and higher genic differentiation at all the loci. All the polymorphic loci in geographical populations of Z. indianus revealed latitudinal clines and changes in allelic frequencies were found to correlate with latitude. The patterns of genie differentiation in Z. indianus population were comparable to those of D. melanogaster populations from India and other continents. The occurrence of higher genetic variability in Z. indianus populations were in agreement with its habitat generalist or broad niche-width characteristics i. e. the species populations utilised diverse food resources and displayed adaptation to variable climatic conditions. Thus, the observed genic divergence patterns in colonising populations of Z. indianus could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.

Utilisation of Alcoholic Resources in Five Colonising Drosophilids from Himachal Pradesh , India

Parkash, Ravi,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3

Drosophila melanogaster, Zaprionus indianus and D. repleta revealed significantly higher ethanol and acetic acid tolerance levels as compared with D. kikkawai and D. immigrans. The parallel patterns of utilisation of other primary and secondary alcohols seem to be correlated with the concentrations of these metabolites found in natural food resources. The longevity effects of n-butanol (0.4 to 1.5%) were found to be significantly high in all the five drosophilids as compared to 2-butanol. The interspecific differences for resource utilisation are in agreement with niche-width hypothesis and seem to be adaptively maintained by natural selection mechanisms.

Latitudinal Differentiation in Alcoholic Utilisation and Desiccation - Starvation Tolerance in Drosophila Kikkawai Populations from India

Parkash, Ravi,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3

Indian geographical populations of D. kikkawai, collected along 20˚N latitudinal range, revealed significant genetic divergence not only of ethanol and acetic acid utilisation but also dessication and starvation tolerance. Latitudinal patterns of ethanol utilization (2.60 to 4.15%) and significantly higher acetic acid utilization (3.50 to 5.25%) were observed in adult individuals of seven geographical populations of D. kikkawai. Very low concentrations (upto 1%) of n-propanol and isopropanol served as resources while secondary alcohols were found to be toxic to D. kikkawai. populations. Thus, the northern and southern populations of D. kikkawai revealed divergence in the patterns of resource utilisation. The parallel occurrence of latitudinal genetic divergence for ethanol and acetic acid utilisation and for propanols in Indian populations of D. kikkawai could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian subcontinent. The observed genetic differentiation in desiccation(17 to 26 hrs) as well as starvation tolerance (92 to 129 hrs) in D. kikkawai populations suggest the role of climatic selection along the latitudinal transect.

ADH Polymorphism and Ethanol Tolerance in Some Drosophila Species from India

Parkash, Ravi,Sharma, Manju,Sharma, Suman 한국유전학회 1992 Genes & Genomics Vol.14 No.3

Seven Indian geographical populations of D. melanogaster and ten oriental Drosophila species were assayed electrophoretically for Adh genie variation. Except four Drosophila species, most species revealed monomorphism or occurrence of one most frequent (>96%) and one rare allele. The Indian geographical populations of D. melanogaster revealed significant clinal variation (3% for 1˚latitude) at Adh locus and Adh^F allelic frequency correlated significantly with increase in latitude. It was suggested that the abundance of secondary alcohols in the southern Indian tropical and humid environment might exert selective pressure favouring higher frequency of Adh^S allele. Patterns of ethanol utilisation as well as ethanol tolerance were analysed in larval and adult individuals of seven geographical populations of D. melanogaster and three Drosophila species. The D. melanogaster populations revealed latitudinal variation in ethanol tolerance along north-south axis while other Drosophila species showed interspecific divergence of ethanol tolerance levels. The parallel occurrence of latitudinal variation at Adh locus as well as ethanol tolerance in Indian geographical populations of D. melanogaster could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.

Allozymic Homogeneity in Indian Populations of Drosophila Busckii

Parkash, Ravi,Yadav, J P,Shamina 한국유전학회 1992 Genes & Genomics Vol.14 No.2

Allozyme polymorphism for nine gene-enzyme systems were studied through horizontal starch gel electrophoresis in isofemale lines derived from six Indian populations of D. busckii. Five autosomal loci coded for dimeric Aph, Odh, Mdh, Me and Ao phenotypes, and allelic variants were represented by segregating single-band variants. complex Acph patterns were controlled by a duplicate locus while polymorphic esterase loci coded for monomeric enzymes. However, Adh and α-Gpdh were controlled by a single locus each and homozygous strain depicted epigenetic two-banded phenotypes. The Indian geographical populations of D. busckii revealed allozymic similarity at all the loci examined. However, the extent of genic diversity was found to be significantly higher than those of U.S. populations. The available data on the patterns of genetic structure of Indian as well as U.S.populations of D. busckii concurred with that of D. simulans in respect of allozymic homogeneity, lack of geographical clinal variation and lack of adaptive flexibility to a range of climatic conditions. Thus, the allozymic uniformity observed in D. busckill might constitute a genetic strategy for this colonising species in respect of its limited niche-width for spatial climatic adaptations.

Latitudinal Variation at adh and est loci in Indian Populations of Two Colonizing Drosophilids

Parkash, Ravi,Yadav, J P,Shamina 한국유전학회 1992 Genes & Genomics Vol.14 No.1

Population samples of Drosophila melanogaster and Zaprionus indianus, collected along 20˚ latitudinal range of the Indian subcontinent, were analysed electrophoretically as well as with heat denaturation technique for patterns of allozymic variation at Adh and Est loci. The Adh^F and Est-6^S allelic frequencies in D. melanogaster; and Adh^F and Est-1^F allelic frequencies in Z, indianus were found to be positively and significantly correlated with increasing latitude. The consistency of the direction of geographical clinal variation across different drosophilids and among continental populations of D. melanogaster; and the occurrence of genie divergence at these loci provide evidence for balancing natural selection mechanisms to maintain such latitudinal allozymic variation in two different colonising species.

Allozyme Variation in Ten Indian Natural Populations of Drosophila Immigrans

Parkash, Ravi,Yadav, J P 한국유전학회 1991 Genes & Genomics Vol.13 No.4

Ten Indian natural populations of D. immigrans, collected along 12˚ longitudinal and 6˚latitudinal ranges, were analysed electrophoretically for allozymic variation of eight gene-enzyme systems. Adh, α-Gpdh, Sod and three Est loci were found to be monomorphic, Mdh locus revealed some geographical variation while overall patterns of genie variation at six other polymorphic loci depicted similarities. Nei's significantly higher values of genetic similarities between populations pairs and low values of Wright's fixation index (F_(ST)) revealed that Indian populations of D. immigrans are genetically homogeneous for the loci analysed. Such observations are consistent with narrow nich-width in terms of food resources and climatic adaptation of this species. However, statistical analysis of allopatric populations of D. immigrans suggest genic differentiation at most polymorphic loci. The available data on genetic structure of D. immigrans populations could be explained on the basis of migration as well as balancing natural selection mechanisms.