15.10.1973 Specialia 1233 In all animals subjected to PCS, the liver weight decreased markedly (Table). This liver 'atrophy' cor- responded to the general experience in this and other laboratories 1-~ and implied a well functioning PCS. 10 days after PCS, GGTP activity had increased tenfold and remained at this level throughout the period of observation. In the control group, the activity was almost undectable (Table). Our findings of very low activity of GGTP in normal adult rat livers are in agreement with earlier observa- tions 5,s-~~ In these animals GGTP activity may be found histochemically in the endothelial cells of pert- portal vessels, in bile ducts and in Kupffer cells, whereas virtually no activity can be detected in hepatocytes ~. The high enzyme activity ill certain rat hepatomas which contain glycogen, produce bile and have a high level of glucose-6-phosphatase 7, suggests that GGTP may be activated in parenchymatous liver cells during the carcinogenic process. This has been interpreted as a re-acquirement of a biochemical feature which pre- dominates in the fetus, but is repressed in the adult liver ~. The microscopical anatomy of the liver of shunted rats looks grossly normal~,~. Measurements of DNA content have suggested that the initial loss of liver mass is due more to a reduction in cell size rather than in cell number 13 Some observers noted a slight increase in the number of Kupffer cells 14. Even though we have no information about the histochemical distribu- tion of GGTP activity in shunted rats, the generally recognized minor morphological aIterations do not appear sufficient to explain the tenfold increase in en- zyme activity after PCS. The impressive elevation in hepatic GGTP-content could therefore be interpreted more reasonably in the context of the similar findings in neonatal liver and in chemically induced rat hepa- tomas. According to this view, ~the shunt consequences might be associated with derepression of an enzyme, normally present only in the embryonal liver. Further studies are required to demonstrate whether such a mechanism is limited to a few specific enzymes or re- presents a form of generalized hepatic immaturity after PCS. Zusammen/assung. In Leberhomogenaten yon Ratten mit einem portocavalen <~Shunt}> wurde gegeniiber un- behandelten Kontrolttieren eine zehnfache Vermehrung der Aktivit~it der y-Glutamyltranspeptidase festgestellt. Dieser Befund k6nnte als Derepression dieses Enzyms gedeutet werden, da iihnlich gesteigerte Enzymaktivi- t/iten bisher nur bet embryonalen Lebern und bet che- misch induzierten Hepatomen gemessen worden sind. J. P. COLOMBO and J. BIRCH]~R Chemisches Zentrallabor, Inselspital Berne, and Department o/ Clinical Pharmacology, University o/ Berne, CH-3010 Bern (Switzerland), 9 May 1973. 8 C. E. NEUBECK and C. V. SMYTHE, Arch. Biochem. 4, 443 (1944). 9 F. BINKLEY and D. NAKAMURA, J. biol. Chem. 173, 411 (1948). I0 j . A. GOLDBERG, O. 1~. FRIEDMAN, t~. P. PINEDA, E. ]~. SMITH, R. CHATTERJI, E. H. STEIN and A. M. RUTENBERG, Arch. Bioehem. 91, 61 (1960). 11 A. M. RUTENBERG, H. KIM, J. W. I~ISCHBEIN,J. S. HANKER, H. L. WASSERKRIJG and A. M. SELIGMAN, J. Histoehem~ Cytochem. 77, 517 (1969). n M. H. KYN and J. 13. CAVANAGH,Br. J. exp. Path. 5, 217 (1970). la B. FISHER, ]~. R. FISHER and S: LEE, Surg. Gynee. Obstet. 125, 1253 (1967). 14 p. OUDEA and H. BISMUTH, Path. 13iol. 73, 288 (1965). The Use of Alfalfa Residual, Juice for Production One of the most serious problems facing the world nowadays is the provision of an adequate diet for a rapidly increasing population. This can be especially observed in Latin America, where the protein shortage constitutes the main nutritional deficiencyL Under these circumstances, the developing of processes for conversion of waste materials into edible microbial foods is of para- mount importance. Several processes for tile obtention of leaf protein con- centrate have been reported ill the literature 2-4. DUring these processes, alfalfa residdal juice is obtained as a byproduct and the feasibility of its use for biomass production was the aim of the present investigation. Earlier results have been published elsewhere 5, 6 Materials and methods. The culture selected for its highest growth rate was Candida sp). The medium used in fermentation contained 0.5 g of K~HPO4/1 of alfalfa residual juice. Fermentation was conducted at 30~ and at a controlled pH of 5.0. The fermentor used throughout this study was a 14 1 total capacity (Fermentation Design Inc.) with a working volume of 9 t. Stirrer speed was of 400 rpm. Simple on-off controlwas used, arranged so that the dissolved oxygen partial pressure did not fall below 0.10 atm. Inoculum was grown in 250 ml Erlenmeyer flasks with 50 ml of medium, and incubation was for 1 day. Dry weight was determined gravimetrically after drying to constant weight the cell material at 100 ~ of Single-Cell Protein Approximately 33 mg of dried biomass was subjected to acid hydrolysis with 6N HC1 at ll0~ for 48 h. The hydrolysate was evaporated under vaccum to dryness and then resuspended in 20 ml of distilled water. This step was repeated 3 times and then the hydrolysate was taken up in a pH 3.1 sodium acetate-acetic acid buffer. The analysis for amino acid was carried out upon a 0.5 ml sample using a Hitachi Perkin-Elmer amino acid analyzer (Model KLA-3B). Tryptophane was determined by a colorimetric method 7. The amino acid content of soybean meal was also determined by the procedures mentioned above. Results and discussion. The stationary phase was practically attained after the 50th h of cultivation, as is shown in Figure la. The maximum productivity p was 1 E. ~V[ONTES, in Recursos Protetnicos en Acndric6 Latina (Eds. R. BRESSANI and IV[.BI~HAR;INCAP, Guatemala 1971), p. 110. J. E. MORRISON and N. W. PIRIE, J. Sci. Fd Agric. 12, 1 (1961). N. W. PIRtE, Science 152, 1701 (1966). 4 "R.. PARADA, Tests Profesional, IPN, M6xico (1968). O. PAREDES-L6PEZ and A. FERNANDEz-Arias, Yeast News Lett. 20, 39 (1972). 60. PAREDES-L6PEZ and A. FER~X~DEz-Arias, IX Int. Congr. Nutrition, Mexico City (1972). R. E. MILLER, J. Sci. Fd Agrie. 18, 381 (1967).