Incorporation of macromolecules into the salivary cells ofDipteran larvae

Zusammenfassung Autoradiographisch wurde festgestellt, dass sich injizierte DNS mit der DNS der polytonen Chromosomen verbindet und in die Zellkerne der Speicheldrüse eingebaut wird.     

Assimilation of ammonia and growth of biotin deficient Aspergillus nidulans.

Biotin deficiency in Aspergillus nidulans has been found to increase the uptake of ammonium ions, associated with a marked increase in the activity of NADP-linked glutamate dehydrogenase, which is found to be the major route of ammonia assimilation in this culture. The results obtained are discussed with respect to the growth of Aspergillus nidulans during biotin deficiency.     

Chiasmate type of meiosis in the roachNauphoeta cinerea (Oliver) (Fam: Blattidae)

Résumé Nauphoeta cinerea est un des Cafards chez lesquels le chiasma de la méiose a été nettement observé. Ce cas vient à l'appui de l'assertion deSuomalainen selon laquelle des chiasmas se présenteraient sous une forme soit «cachée» soit «visible» chez tous les Cafards. La «méiose sans chiasma» queJohn etLewis supposent existes au moins chezP. americana n'est pas non plus confirmée par nos recherches.

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I wish to thank one of the research scholars of the Department, Mr. V. L.Kallapur, for sparing readily some specimens of the roach for my work. Constructive criticisms by my colleague Dr. R. M.Patil are also acknowledged.     

Involvement of nitric oxide in the reflex relaxation of the stomach to accommodate food or fluid.

The fundus of the guinea-pig stomach actively dilates in response to low increases in intragastric pressure. This physiological response, now called adaptive relaxation, accommodates the intake of liquid or food. It is independent of external innervation, resistant to ganglion blockade, but reflex in origin. The nerves involved are neither adrenergic nor cholinergic in nature. Non-adrenergic, non-cholinergic (NANC) nerves have now been recognized in many parts of the gastrointestinal tract and have recently been linked with release of nitric oxide (NO) on electrical stimulation. Here we show that adaptive relaxation in isolated stomach of the guinea pig is mediated by a NANC neurotransmitter substance indistinguishable from NO derived from L-arginine. This is substantiated by inhibition of adaptive relaxation by NG-monomethyl-L-arginine or N omega-nitro-L-arginine methyl ester, both inhibitors of NO synthesis, and by methylene blue, an inhibitor of soluble guanylate cyclase. There are two distinct neuronal pathways signalling NO-dependent adaptive relaxation, as evidenced by tetrodotoxin sensitivity. The first is a local reflex arc, the afferent fibres of which sense changes in intragastric pressure. The second is stimulated by an agonist for ganglionic nicotinic receptors. Thus, the functional significance of NO release from NANC nerves in the stomach is to bring about adaptive relaxation through a reflex response to increases in intragastric pressure.     

Assimilation of ammonia and growth of biotin deficientAspergillus nidulans

Summary Biotin deficiency inAspergillus nidulans has been found to increase the uptake of ammonium ions, associated with a marked increase in the activity of NADP-linked glutamate dehydrogenase, which is found to be the major route of ammonia assimilation in this culture. The results obtained are discussed with respect to the growth ofAspergillus nidulans during biotin deficiency. J. D. Desai gratefully acknowledges the receipt of a research fellowship from the Government of India, Department of Atomic Energy, Bombay.     

Regulation of ammonia uptake in aspergillus nidulans.

The ammonia uptake in A. nidulans was found to be linear for about 20 min, and was proportional up to 1.5 mg/ml dry cell density. The transport of ammonia does not involve energy. Normal and biotin deficient A. nidulans showed an identical Km-values of 10.26 X 10(-5) M ammonia for uptake. The uptake of ammonium ion has been shown to be regulated by the intracellular concentration of ammonia.