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Characterization of Na+-dependent and system a-independent polyamine transport in normal human erythrocytes
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F L U O R I D E I N D U C E D C H A N G E S DURING LIZARD TAIL R E G E N E R A T I O N . P.K.HIRADHAR AND B. SURESH D e p t t . of B i o s c i e n c e s 0 South G u j a r a t U n i v e r s i t y , Surat 395 007 INDIA
CHARACTERIZATION OF NA+-DEP~qDENT AND SYSTEM AINDEP~qDENT POLYAMINE TRANSPORT IN NORMAL HUMAN ERYI~ROCYTES Khan, N.A., V. Quemener and J.-Ph. Moulinoux. Dept. of Cell Biology, Central Hospital of the University (CHU) of Rennes I, Faculty of Medicine, 35043 Rennes Cedex (France).
E p i m o r p h i c r e g e n e r a t i o n of t a i l in l i z a r d s o f f e r s an a t t r a c t i v e model s y s t e m to e x a m i n e t h e d e v e l o p m e n t a l p o t e n t i a l - o f an a p p a r a n t l y s t a b l e a d u l t o r g a n i z a t i o n . Local and s y s t e m i c factors regulate the restitutive activities. Additional influence is exerted by various environmental, fluctuations. This study evaluates influence of sodium fluoride (NaF) on r e g e n e r a t i n g t a i l of t h e g e k k o n i d lizard, Hemidactylus flaviviridis. Orally administered sub-lethal NaF c o n c e n t r a t i o n s caused stage specific alterations. Lower doses accelerated t h e wound h e a l i n g and s u b s e q u e n t p r o g r e s s of r e g e n e r a t i o n , w h i l e the higher ones p r o l o n g e d i n i t i a l e v e n t s of t h e p r o c e s s or s o m e t i m e s b l o c k e d f u r t h e r p r o g r e s s . R e f l e c t i o n of s u c h l o c a l ( c a u d a l ) e v e n t s c o u l d be s e e n in t h e c i r c u l a t i n g blood cell p o p u l a t i o n s ; and microscopic and m e t a b o l i c p r o f i l e of t h e h e p a t i c t i s s u e . A d o s e - d e p e n d e n t d u a l i n f l u e n c e on r e g e n e r a t i o n can be a s c r i b e d to f l u o r i d e .
The biochemical properties of polyamine transport have been studied in normal human red blood cells (RBC) by measuring the uptake of *4CSpermidine under various experimentally imposed pharmacological conditions. Spermidine (Spd) uptake appeared to be a sodium dependent process. Iso-osmotieally replacement of Na+ with choline chloride in the assay medium resulted in the decrease of Spd uptake. Gramieidin, a channel former ionophore, and valinom¥cin, an ionophore specific for K+ions, inhibited the Spd uptake process suggesting that a membrane potential across the plasma membrane is required for Spd uptake. Inhibition of Spd uptake by A23187, a Ca ++ iono~ore, which allows permeation of Ca++ and M g ~ , further alludes towards the dissipation of the membrane potential required for the Spd uptake process. N-ethylmaleimide or p-chloromercuribenzene sulfonate also abolished the Spd uptake indicating that sulfhydryl groups may be important for the uptake of Spd. Preloading the RBC with Na+-dependent System A or other amino acids do not affect the Spd uptake process significantly and this further suggests that the process of Spd transport is not regulated by these amino acids. Other polyamines (putrescine and spermine) inhibited the Spd uptake in a competition inhibition assay where putrescine exhibited higher inhibitory effect than spermine. Preincubation of RBC for 36 hours with MGBG inhibited the Spd uptake while, interestingly, preincubation of RBC with DFMO, an irreversible inhibitor of ornithine decarboxylase, in the same conditions did not affect the mechanism of Spd uptake. The initial velocities of Spd uptake were 15 times higher at 37°C than those at 0°C. Arrhenius energy of activation (Ea) of Spd uptake was 15.20#0.60 Cal/mol.
145 SOME PROBLEMS OF MARSUPIAL ONTOGENY Klima, M. Anatomical Institute, J.W. GoetheUniversity, Frankfurt am Main, F.I~G. Based on investigations in the Embryological collection (viz. the Hill Collection) from the Hubretht Laboratory, Netherlands Institute for Developmental Biology (Utrecht), the external morphology and the early development of the shoulder girdle and sternum in marsupials were studied. More than I00 serial sections of ii species were investigated and represent the most complete source material ever compiled for such a purpose. For the first time it has been possible to describe the morphogenesls of the marsupial breast-shoulder apparatus not only through single developmental stages, but also as a c o n t i n u a l process. The breast-shoulder a p p a r a t u s f o r m s a c o m p a c t a r c h in the intrauterine embryos and in the neonates, respectively. In the pouch young, this arch is reduced soon after birth. This early formation on a skeletal base is made possible by the fact that in marsupial embryogenesis some ancestral structures persist that are encountered in reptiles and in monotremes, but not in advanced placentals. This genetically determined early embryonic condition is preserved up to the time of birth and plays a role in the active movements of the forelimbs in neonates during birth.
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F L U O R I D E I N D U C E D C H A N G E S DURING LIZARD TAIL R E G E N E R A T I O N . P.K.HIRADHAR AND B. SURESH D e p t t . of B i o s c i e n c e s 0 South G u j a r a t U n i v e r s i t y , Surat 395 007 INDIA
CHARACTERIZATION OF NA+-DEP~qDENT AND SYSTEM AINDEP~qDENT POLYAMINE TRANSPORT IN NORMAL HUMAN ERYI~ROCYTES Khan, N.A., V. Quemener and J.-Ph. Moulinoux. Dept. of Cell Biology, Central Hospital of the University (CHU) of Rennes I, Faculty of Medicine, 35043 Rennes Cedex (France).
E p i m o r p h i c r e g e n e r a t i o n of t a i l in l i z a r d s o f f e r s an a t t r a c t i v e model s y s t e m to e x a m i n e t h e d e v e l o p m e n t a l p o t e n t i a l - o f an a p p a r a n t l y s t a b l e a d u l t o r g a n i z a t i o n . Local and s y s t e m i c factors regulate the restitutive activities. Additional influence is exerted by various environmental, fluctuations. This study evaluates influence of sodium fluoride (NaF) on r e g e n e r a t i n g t a i l of t h e g e k k o n i d lizard, Hemidactylus flaviviridis. Orally administered sub-lethal NaF c o n c e n t r a t i o n s caused stage specific alterations. Lower doses accelerated t h e wound h e a l i n g and s u b s e q u e n t p r o g r e s s of r e g e n e r a t i o n , w h i l e the higher ones p r o l o n g e d i n i t i a l e v e n t s of t h e p r o c e s s or s o m e t i m e s b l o c k e d f u r t h e r p r o g r e s s . R e f l e c t i o n of s u c h l o c a l ( c a u d a l ) e v e n t s c o u l d be s e e n in t h e c i r c u l a t i n g blood cell p o p u l a t i o n s ; and microscopic and m e t a b o l i c p r o f i l e of t h e h e p a t i c t i s s u e . A d o s e - d e p e n d e n t d u a l i n f l u e n c e on r e g e n e r a t i o n can be a s c r i b e d to f l u o r i d e .
The biochemical properties of polyamine transport have been studied in normal human red blood cells (RBC) by measuring the uptake of *4CSpermidine under various experimentally imposed pharmacological conditions. Spermidine (Spd) uptake appeared to be a sodium dependent process. Iso-osmotieally replacement of Na+ with choline chloride in the assay medium resulted in the decrease of Spd uptake. Gramieidin, a channel former ionophore, and valinom¥cin, an ionophore specific for K+ions, inhibited the Spd uptake process suggesting that a membrane potential across the plasma membrane is required for Spd uptake. Inhibition of Spd uptake by A23187, a Ca ++ iono~ore, which allows permeation of Ca++ and M g ~ , further alludes towards the dissipation of the membrane potential required for the Spd uptake process. N-ethylmaleimide or p-chloromercuribenzene sulfonate also abolished the Spd uptake indicating that sulfhydryl groups may be important for the uptake of Spd. Preloading the RBC with Na+-dependent System A or other amino acids do not affect the Spd uptake process significantly and this further suggests that the process of Spd transport is not regulated by these amino acids. Other polyamines (putrescine and spermine) inhibited the Spd uptake in a competition inhibition assay where putrescine exhibited higher inhibitory effect than spermine. Preincubation of RBC for 36 hours with MGBG inhibited the Spd uptake while, interestingly, preincubation of RBC with DFMO, an irreversible inhibitor of ornithine decarboxylase, in the same conditions did not affect the mechanism of Spd uptake. The initial velocities of Spd uptake were 15 times higher at 37°C than those at 0°C. Arrhenius energy of activation (Ea) of Spd uptake was 15.20#0.60 Cal/mol.
145 SOME PROBLEMS OF MARSUPIAL ONTOGENY Klima, M. Anatomical Institute, J.W. GoetheUniversity, Frankfurt am Main, F.I~G. Based on investigations in the Embryological collection (viz. the Hill Collection) from the Hubretht Laboratory, Netherlands Institute for Developmental Biology (Utrecht), the external morphology and the early development of the shoulder girdle and sternum in marsupials were studied. More than I00 serial sections of ii species were investigated and represent the most complete source material ever compiled for such a purpose. For the first time it has been possible to describe the morphogenesls of the marsupial breast-shoulder apparatus not only through single developmental stages, but also as a c o n t i n u a l process. The breast-shoulder a p p a r a t u s f o r m s a c o m p a c t a r c h in the intrauterine embryos and in the neonates, respectively. In the pouch young, this arch is reduced soon after birth. This early formation on a skeletal base is made possible by the fact that in marsupial embryogenesis some ancestral structures persist that are encountered in reptiles and in monotremes, but not in advanced placentals. This genetically determined early embryonic condition is preserved up to the time of birth and plays a role in the active movements of the forelimbs in neonates during birth.
$44