Analysis of environmental factors regulating the gonadal cycle in a tropical pond turtle,Lissemys p. granosa (Schoepff.)

Zusammenfassung Nachweis, dass die SchildkröteLissemys p. granosa in der freien Natur zyklische Veränderungen ihrer Gonadenaktivität bei beiden Geschlechtern zeigt, wobei Umweltbedingungen wie Tageslänge, Temperatur und Luftfeuchtigkeit die Rhythmik beeinflussen und regulieren dürften.     

A note on the fowler's solution of the lane-emden equation of index 3

Zusammenfassung FürFowler's Lösung der Lane-Emden-Gleichung von Index 3 wird der Gültigkeitsbereich erweitert.     

One-sided sexual isolation betweenDrosophila takahashii andDrosophila pseudotakahashii

Summary In order to elucidate the phylogenetic relationships betweenD. takahashii andD. pseudotakahashii, 2 closely related allopatric species, sexual isolation was studied by the male-choice method. The present data indicate that there is a one-sided mating preference between these species. On a basis of the results, their evolutionary sequence is discussed.We are indebted to Dr I. R. Bock, Australia, and Dr O. Kitagawa, Japan, for kindly providing the live cultures. Thanks are due to the Head of the Zoology Department, B.H.U. for the provision of laboratory facilities and to the C.S.I.R., New Delhi, India, for awarding a Post-doctoral fellowship to Y.N.D.     

Use of arrow-root powder in starch gel electrophoresis

Summary The arrow-root powder is used in electrophoresis as an alternative to potato starch. Its use is quite economical and this starch can be easily hydrolysed in any laboratory.The author is indebted to Dr M. M. Goil, Prof. & Head of the Department and Dr R. K. Sharma, Professor of Zoology, for their invaluable suggestions and help in various ways.     

Endogenous gibberellins and amylase activity in tall and dwarf strains of rice (Oryza sativa)

Summary 2 tall and 7 dwarf strains of rice were sprayed with 0 or 40 g ml^–1 GA₃, 4 dwarf strains responded to exogenous GA₃, and showed a markedly lower endogenous gibberellin content than the tall strains, while 2 dwarf strains did not respond to GA₃ application and had considerably higher endogenous gibberellin levels than the tall ones. Amylase activity in germinating seeds showed a significant negative correlation with the endogenous gibberellin content.     

Level of marker enzymes in spermatogenesis on administration of PGF2a in rats

Summary Intrapertioneal administration of PGF_2a in rats significantly increased testicular acid phosphatase (p<0.05), decreased hyaluronidase (p<0.05), whereas the activities of 5-nucleotidase, N-acetyl-B-glucosaminidase, B-galactosidase and uridine diphosphatase remained unaffected.Acknowledgment. We are grateful to Dr D. Sundaresan, for his interest in the study and to Mr B. M. Sharma for technical assistance.     

Serum iron level of the common Indian frogRana tigrina Daud.

Summary A study extending over a period of 2 years has been made on serum iron level of common Indian frogR. tigrina. Serum iron averages 99.4 g/100 ml in female and 92.60 g/100 ml in males. The serum iron concentration is relatively high from May to October. Starvation has been found to decrease the serum iron level from the 16th day onwards.Acknowledgment. Thanks are due to Professor Dr M. M. Goil, Head of the Zoology Department for guidance and help in various ways and to Professor Dr R. K. Sharma for valuable suggestions.     

Electronic structure of the iron-based superconductor LaOFeP

The recent discovery of superconductivity in the iron oxypnictide family of compounds has generated intense interest. The layered crystal structure with transition-metal ions in planar square-lattice form and the discovery of spin-density-wave order near 130 K (refs 10, 11) seem to hint at a strong similarity with the copper oxide superconductors. An important current issue is the nature of the ground state of the parent compounds. Two distinct classes of theories, distinguished by the underlying band structure, have been put forward: a local-moment antiferromagnetic ground state in the strong-coupling approach, and an itinerant ground state in the weak-coupling approach. The first approach stresses on-site correlations, proximity to a Mott-insulating state and, thus, the resemblance to the high-transition-temperature copper oxides, whereas the second approach emphasizes the itinerant-electron physics and the interplay between the competing ferromagnetic and antiferromagnetic fluctuations. The debate over the two approaches is partly due to the lack of conclusive experimental information on the electronic structures. Here we report angle-resolved photoemission spectroscopy (ARPES) of LaOFeP (superconducting transition temperature, T(c) = 5.9 K), the first-reported iron-based superconductor. Our results favour the itinerant ground state, albeit with band renormalization. In addition, our data reveal important differences between these and copper-based superconductors.     

Alzheimer’s disease: the impact of age-related changes in reproductive hormones

Two classes of ovarian steroids, estrogens and progestins, are potent in protecting neurons against acute toxic events as well as chronic neurodegeneration. Herein we review the evidence for neuroprotection by both classes of steroids, provide plausible mechanisms for these potent neuroprotective activities and indicate the need for further clinical trials of both estrogens and progestins in protection against acute and chronic conditions that cause neuronal death. Estrogens at concentrations ranging from physiological to pharmacological are neuroprotective in a variety of in vitro and in vivo models of cerebral ischemia and brain trauma as well as in reducing key neuropathologies of Alzheimers disease. While the mechanisms of this potent neuroprotection are currently unresolved, a mitochondrial mechanism is involved. Progestins have been recently shown to activate many of the signaling pathways used by estrogens to neuroprotect, and progestins have been shown to protect against neuronal loss in vitro and in vivo in a variety of models of acute insult. Collectively, results of these animal and tissue culture models suggest that the loss of both estrogens and progestins at the menopause makes the brain more vulnerable to acute insults and chronic neurodegenerative diseases. Further clinical assessment of appropriate regimens of estrogens, progestins and their combination are supported by these data.