Browsing by Author "S.P. Ray-Chaudhuri"

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A comparative study of the chromosomes of birds
(Springer-Verlag, 1969) R. Ray-Chaudhuri; T. Sharma; S.P. Ray-Chaudhuri
Karyotype analysis and morphometric measurement of the chromosomes of eleven species of Indian birds are described. The unequivocal identification of W chromosome in the females of five species of the present investigation further strengthens the generalisation that, at least in Carinatae, the sex chromosome constitutions are of ZZ and ZW types in males and females respectively. - The chromosomes of different species of birds so far worked out in each order have been compared using quantitative methods and tentative conclusions have been drawn regarding chromosomal affinities between species of different taxonomic categories. © 1969 Springer-Verlag.
Chromosomes and the karyotype of the Pangolin, Manis pentadactyla L. (Pholidota-Mammalia)
(Birkhäuser-Verlag, 1969) S.P. Ray-Chaudhuri; T. Sharma; S. Pathak; L. Singh
[No abstract available]
Cysteamine protection of grasshopper chromosomes from x-ray-induced aberrations under aerobic and anaerobic conditions
(Informa Healthcare, 1962) S.P. Ray-Chaudhuri; J.P. Chaudhuri; S. Chatterjee
The effect of cysteamine pre-treatment on the frequency of x-ray-induced chromosome aberrations was determined under both aerobic and anaerobic conditions by counting the dicentric bridges in the first division meiotic anaphase of the grasshopper, Gesonula punctifrons. Under aerobic conditions in the cysteamine-treated animals 20·73 per cent bridges were scored as compared with 30-90 per cent in the controls. Under anaerobic conditions the scores were 5·35 per cent and 8·22 per cent in the treated and controls, respectively. Thus the degree of protection by cysteamine under both aerobic and anaerobic conditions was found to be more or less the same. The possible mode of protection has been discussed. © 1962 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
Evolution of sex-chromosomes and formation of W-chromatin in snakes
(Springer-Verlag, 1971) S.P. Ray-Chaudhuri; L. Singh; T. Sharma
The analysis of sex-chromosome complexes and formation of W-chromatin in 16 species of snakes of the families Boidae, Colubridae, Elapidae, and Hydrophiidae, reveal three very pertinent facts. First, the snakes exhibit various states of the differentiation of the Z and W chromosomes, apparently according to the evolutionary status of the families, being homomorphic in primitive families and well differentiated in highly evolved ones. Second, the demonstration of a heteropycnotic body in the interphase nuclei of the families of a large number of species of snakes has definitely shown that the nuclear sexing is possible not only in those species of snakes where the W chromosome is morphologically distinguishable from the Z, but also in those species where it is not so, but shows an asynchrony in the replicating pattern of W. It is suggested that development of allocycly rather than establishment of structural changes is the first step in the differentiation of the W from the Z in snakes. Third, the absence of coexistence of nucleolus and W-chromatin in a condensed state in the interphase nuclei of different tissues in a few species of snakes reported in this paper suggests that the W-chromatin is responsible for the synthesis of the nucleolus in these snakes. © 1971 Springer-Verlag.
Karyotypes of five indian species of microchiroptera
(1971) S.P. Ray-Chaudhuri; S. Pathak; T. Sharma
Taphozous melanopogon and T. l. longimanus (family Emballonuridae, have 2N = 42, Megaderma l. lyra (family Megadermatidae) has 2N = 54 and Hipposideros fulvus and H. a. ater (family Hipposideridae) have 2N = 32. The chromosomes of Megadermatidae and Hipposideri- dae have been studied for the first time. Interrelationships on the basis of available chromosome data and also the probable mechanisms of karyotype evolution in these Indian species of Microchiroptera are discussed. © 1971 Taylor & Francis Group, LLC.
Multiple sex-chromosomes in the common Indian Krait, Bungarus caeruleus Schneider
(Springer-Verlag, 1970) L. Singh; T. Sharma; S.P. Ray-Chaudhuri
The highly poisonous common Indian Krait, Bungarus caeruleus of the family Elapidae has 2n ♂=44 and 2n ♀=43. There is a sharp difference in size between macro and microchromosomes. The number of macrochromosomes is 24 in males and 23 in females whereas there are 20 microchromosomes in both the sexes. The difference in number of macro-chromosomes in the two sexes is explainable on the basis of translocation of a macro-autosome to the W chromosome resulting in a multiple sex-chromosome constitution of Z1Z1Z2Z2♂/Z1Z2W♀-types. Autoradiographic studies using H3-TdR show that the W is late replicating except for the translocated part which finishes its replication along with the macroautosomes. This is the first example of a multiple sex-chromosome complex in a vertebrate with female heterogamety. © 1970 Springer-Verlag.
Radioprotective effect of six chemicals against X-ray-induced genetic damage in D. melanogaster
(1973) Mercy Jacob; S.P. Ray-Chaudhuri
In Drosophila melanogater six chemicals were tested for radioprotectiveeffect against X-ray-induced genetic damage such as sex-linked recessive lethals and autosomal translocations using Oster's ring-X chromosome stock. A 2-day brood pattern was followed to score the damage induced at different spermatogenic stages separately. In all cases the chemicals were injected before X-irradiation. 10-mM solution of reduced glutathione (GSH) provided statistically significant protection against sex-linked recessive lethals in all broods. In translocation tests this chemical reduced the frequency in all broods but the result is not statistically significant. Cysteamine (MEA) did not show any protective effect but the frequency of lethals was slightly reduced in the first and fourth broods. 2-Aminoethyl isothiuronium Br·HBr (AET) showed a statistically significant protective effect when the data of the replicate experiments were pooled. Negative results were obtained for 5-hydroxytryptamine (5-HT) in sex-linked lethal tests. Aminoethyl phosphorothioate (AEPT) reduced the frequencies of both sex-linked lethals and autosomal translocations in all broods consistently but the results are not statistically significant. In tests for both lethals and translocations the reduction was largest in the stages with highest radiosensitivity. N(3-Aminopropyl)aminoethyl phosphorothioate (3AP-AEPT) gave no protection. © 1973.
Somatic chromosomes of the common palm civet, Paradoxurus hermaphroditus (Viverridae - carnivora)
(Birkhäuser-Verlag, 1966) S.P. Ray-Chaudhuri; P.V. Ranjini; T. Sharma
[No abstract available]
The genus drosophila (diptera: Drosophilidae) in andaman and nicobar islands, india
(1970) J.P. Gupta; S.P. Ray-Chaudhuri
Altogether 1276 flies, comprising eight species, were collected. One of them is new, D. (Sophophora) andamanensis, sp. nov. D. ficusphila Kikkawa and Peng and D. gracilis Duda are reported for the first time from India. © 1970 Taylor & Francis Group, LLC.
The W chromosome in the females of two Indian species of birds
(Springer-Verlag, 1966) S.P. Ray-Chaudhuri; R. Ray-Chaudhuri; T. Sharma
The heterogametic females of the jungle babbler, Turdoides s. striatus and red-breasted parakeet, Psittacula alexandri fasciata belonging to the orders Passeriformes and Psittaciformes respectively in the subclass Carinatae have ZW sex chromosomes. The W chromosomes in both the species are of the size of smaller macrochromosomes or larger microchromosomes and they are easily identified in both species. © 1966 Springer-Verlag.
W chromosome in the Indian water snake (checkered keel back)Natrix piscator (colubridae)
(Birkhäuser-Verlag, 1968) L. Singh; T. Sharma; S.P. Ray-Chaudhuri
[No abstract available]