Chromosomal homology in southern Akodon

Summary Differential staining (G and C) of southern South AmericanAkodon are presented.A. olivaceus, A. longipilis andA. sanborni all have the same karyotype (2n=52, NF=58). A virtually identical band sequence is observed. This situation is interpreted using the canalization model of chromosomal evolution which stresses an optimum karyotype for each adaptive zone. Despite the high degree of conservation of the chromosome structures, the specific status of these species is supported by maintenance of distinctness when they occur in areas of sympatry.The research was partially supported by Proyecto de Investigación I-78-86, Dirección de Investigación, Universidad Austral de Chile and Programa Especial de Citogenética, U. de Chile sede Norte, Santiago, Chile.     

Identification of raffinose in honeydew

Summary The presence of small amounts of raffinose in the honeydew of 6 aphid species was demonstrated by means of TLC and GLC after invertase hydrolysis. The method allows the detection of this sugar even in the presence of a high percentage of melezitose.Work carried out under a C.N.R. grant.     

In vitro amiodarone protein binding and its interaction with warfarin

Summary The binding of amiodarone to human plasma protein and to bovine serum, albumin was studied by three different methods, ultracentrifugation, equilibrium dialysis and fluorescence spectroscopy. The fraction of amiodarone bound to plasma protein amounted to 96.3%. The changes in the binding properties of 1-anilino-naphthalene-8-sulfonate for bovine serum albumin using warfarin and amiodarone as independent inhibitors were analyzed in terms of binding site specificity. The findings indicated that amiodarone and warfarin have two different binding sites on bovine serum albumin, so a noncompetitive inhibition mechanism was indicated. On the basis of our data we cannot exclude other mechanisms of interaction besides direct displacement of one drug by another; nevertheless, metabolite interference between amiodarone and coagulation cofactors may better explain the enhancement of warfarin's pharmacological action in association with amiodarone.This work was partially funded by the CNR (National Research Council, Rome, Italy), Program on Clinical Pharmacology and Rare Diseases. The authors would like to thanks Drs E. Marzi and E. riva for their help.     

Presence of presumptive interdigitating cells in the spleen of the natterjack,Bufo calamita

Summary The periphery of splenic lymphoid follicles, an area rich in reticulum fibers, contains presumptive interdigitating cells characterized by low electron density, scantiness of cytoplasmic organelles, abundant surface foldings and, sometimes, electrondense granules of unknown significance.     

The use of dipeptide-p-nitranilides for the study of aminopeptidase specificity.

The use of dipeptide-p-nitranilides for the study of 2 placental aminopeptidases separated on Sephadex G200 helped in establishing some regular features of their specifities. The high-molecular (320,000 daltons) one prefers Phe in position P'1 to Leu, whereas the lower-molecular aminopeptidase (145,000 daltons) prefers Leu. The high-molecular aminopeptidase splits very slowly the N-terminal Leu when Gly is in adjacent position. Leu-Gly-p-NA is therefore an inhibitor of this AP.     

Formation of lipoperoxide in isolated sciatic nerve by chinoform-ferric chelate.

Effects of chinoform and chinoform-ferric chelate on formation of lipoperoxide in isolated sciatic nerve were investigated. Free chinoform did not increase the lipoperoxide level, while chinoform-ferric chelate significantly increased it. Assuming that the lipoperoxide formed denatures the associated protein in the nerve, the effect of chinoform-ferric chelate could explain, at least partly, the demyelination of nerve tissues caused by massive doses of chinoform.     

Altered expression of securin (Pttg1) and serpina3n in the auditory system of hearing-impaired Tff3-deficient mice

Introduction

Tff3 peptide exerts important functions in cytoprotection and restitution of the gastrointestinal (GI) tract epithelia. Moreover, its presence in the rodent inner ear and involvement in the hearing process was demonstrated recently. However, its role in the auditory system still remains elusive. Our previous results showed a deterioration of hearing with age in Tff3-deficient animals.

Results

Present detailed analysis of auditory brain stem response (ABR) measurements and immunohistochemical study of selected functional proteins indicated a normal function and phenotype of the cochlea in Tff3 mutants. However, a microarray-based screening of tissue derived from the auditory central nervous system revealed an alteration of securin (Pttg1) and serpina3n expression between wild-type and Tff3 knock-out animals. This was confirmed by qRT-PCR, immunostaining and western blots.

Conclusions

We found highly down-regulated Pttg1 and up-regulated serpina3n expression as a consequence of genetically deleting Tff3 in mice, indicating a potential role of these factors during the development of presbyacusis.