Band 39, Heft 1-2

From cell material of Cystobacter fuscus strain Cb 685 (Myxobacterales) the ceramides 2S ,3R-N-(2′R-hydroxy-15′-methylpalmitoyl)-17-methylsphinga-4E,8E-dienine (1), 2S.3R-N-(2′R-hydroxypalmitoyl)-17-methylsphinga-4E,8E-dienine (10), 2S ,3R-N-(2′R-hydroxy-15′-methyl)-17-methyl-4E-sphingenine (11) and 2S,.3R-N-(2′R-hydroxy-15′-methylpalmitoyl)-17-methylsphinganine ( 12) could be isolated, the structure elu cidation of which is being reported here. The carotenoid myxobactone could be identified as the main pigment.

From Clavariadelphus pistillaris and several Ramaria species a bitter substance, pistillarin, has been isolated which is responsible for the green colour reaction of the fruit-bodies with FeCl 3 . Its structure has been determined as N 1 ,N 8 -bis(3,4-dihydroxybenzoyl)spermidine (1).

Three isoflavonoid phytoalexins produced by the fungus or CuSO 4 -treated leaflets of Nissolia fruticosa have been identified as (+)-6aS; 1 la S-3.7-dihydroxy-9-methoxypterocarpan (nissicarpin). (+)-6 aS ; 1 la S-7-hydroxy-3,9-dimethoxypterocarpan (fruticarp in) and (+)-6a.S; 11 aS-3,7-dihydroxy-2,9-dimethoxypterocarpan (nissolicarpin).

6-Hydroxyflavones have been identified for the first time in the Iridaceae, in leaves of three Crocus species. Three new glycosides have been characterised: 6 -hydroxyluteolin 7- rhamnosylglucoside, scutellarein 7-glucoside and scutellarein 7-methyl ether 6 -glucoside, as well as two known glycosides: 6 -hydroxyluteolin 7-glucoside and 6 -hydroxyluteolin 7-methyl ether 6 - glucoside. 6 -Hydroxyluteolin and scutellarein glycosides have been found before in Bromeliaceae. Commelinaceae, Cyperaceae and Orchidaceae, but this is the first record of the respective 7-methylethers in the Monocotyledoneae. Acacetin and tricin have been identified as aglycones in C. laevigatus an d C. heuffelianus leaves, respectively and the occurrence of mangiferin confirmed in C. aureus leaves. Two of the major flavonol glycosides present in flowers of cultivated species were identified as kaempferol 3-sophoroside and kaempferol 3- rutinoside-7-glucoside. However none of the flavonoids identified appears to contribute to yellow petal colour in Crocus, which is probably entirely carotenoid-based.

A screening of 27 fern species (Filicopsida) out of 9 families revealed that 25 species were able to decarboxylate 1-leucine to 3-methylbutylamine (isoamylamine). The enzyme of Polvpodium vulgäre has partially been purified and characterisized. All attempts to solubilize it from acetone preparations failed; however, approx. 50% of total activity could be extracted from dry material in the presence of detergents at high concentration. The soluble enzyme was purified 132-fold. 1-Methionine was found the best substrate followed by norvaline, leucine, norleucine, isoleucine, homocysteine, valine. It has been confirmed that these substrates are decarboxylated by a single enzyme. The pH -optimum was at pH 5.0 (particulate preparation) and pH 4.5 (soluble enzyme). Decarboxylation is dependent on pyridoxal-5′-phosphate (PLP). A strictly substrate dependent coenzyme dissociation was observed which could largely be prevented by addition of 2-oxo-acids, such as glyoxylate or pyruvate. A podecarboxylase prepared by prolonged substrate incubation was found to be extremely labile at pH 4.5 but stable at pH 6.5. A comparison of the fernenzyme with bacterial valine decarboxylase (EC 4.1.1.14) and leucine decarboxylase of red algae revealed great similarities especially in substrate specificity. It is suggested to unify these activities as “aliphatic 1-amino acid decarboxylase”.

Umbelliferone and scopoletin are well utilized as precursors of puberulin, a 7-O-prenyl ether of isofraxidin elaborated by Agathosm a puberula Fourc. (Rutaceae). As ferulic, sinapic, and caffeic acids were all more poorly utilized than 4′-hydroxycinnamic (p-coumaric) acid, the partial biosynthetic route: 4′-hydroxycinnamic acid →→ um belliferone → aesculetin → scopoletin →→ puberulin is suggested as the major pathway. Prenylether formation apparently occurs at or beyond the scopoletin stage. The implication that ferulic acid does not participate in the formation of scopoletin from 4′-hydroxycinnamic acid is at variance with the known role of ferulic acid as a scopoletin precursor in tobacco.

Administration of sodium [1,2- 14 C 2 ]oxaloacetate and sodium [1- 14 C] acetate to Scilla maritima plants yielded labelled scillirosid. Asystematic degradation of scillirosid indicated that the 2 -pyrone ring of the bufadienolide is formed by the condensation of a pregnane derivative (derived from mevalonic acid via squalene) and one molecule of oxaloacetic acid.

The addition of an adsorbent (activated charcoal) to plant cell suspension cultures often decreases the growth rate, in a tobacco cell culture accom panied by alterations of protein content and cell size. All these effects can be reversed in part or even totally after pretreatment of the adsorbent with phytohormones.

When cell cultures of Ricinus communis are grown in light and with kinetin as the sole growth factor red cells are formed. The red pigmentation is due to the accumulation of rhodoxanthin which is the major carotenoid in these cultures. The identification of this retro-type carotenoid is based on electronic and mass spectra, on chemical transformation to zeaxanthin, and on comparison with an authentic sample. Rhodoxanthin is not present in any part of the intact plant. The major yellow carotenoid in the red cultures is lutein.

Susceptibilities to snake venom 5′;-nucleotidase (EC 3.1.3.5) have been evaluated for several 8-substituted analogues of 5′-GM P with varying populations of syn /anti conformations about the glycosidic bond. Improved syntheses of some of these are described, including direct chlorination of 5′-GMP to give 8-chloro-5′-GMP, a procedure which should be applicable to other purine nucleotides. The conformations of the various analogues were determined by means of 1 HNMR spectroscopy, with particular emphasis on the glycosidic bond conformations. All the 8-substituted derivatives of 5′-GM P were relatively poor substrates of 5 ′-nucleotidase. This was shown to result largely from steric effects and the nature of the 8-substituent, and consistent with a requirement for the anti conformation. Although ribose-5-phosphate was not a substrate, it was a weak inhibitor, and its inhibitory properties account in part for the weak inhibitory properties of the 8-substituted 5′-GMP, and other, analogues. Attention is drawn to the hitherto largely neglected differences in properties of 5′-nucleotidases from different sources and their relevance to the present findings.

N 1 Glycolylbiuret, pH-Effect N 1 glycolylbiuret has been identified as a radiation product of cytosine in aerated aqueous solution at pH 4.5. When varying the pH of the solution before irradiation from acidic values towards neutral ones. G value of N 1 glycolylbiuret reached a maximum at pH 4.5.

Soluble NADH dehydrogenase was purified to homogeneity from chemotrophically grown cells of Rhodopseudomonas capsulata by ammonium sulfate fractionation, AH -Sepharose 4B chromatography and FMN-Sepharose 6B affinity chromatography. The enzyme contains a single polypeptide chain of an apparent M, of 37000, suggesting that the subunit structure is different from that of the membrane-bound enzyme. The purified soluble NADH dehydrogenase requires flavin compounds, e.g., FMN, FAD and riboflavin, for activity. Addition of FMN and FAD. but not riboflavin, to the enzyme solution stabilized the enzyme. The pH optimum for activity was at 7.5. The enzyme was specific for NADH as an electron donor while NADPH was inert. Menadione, ferricyanide, cytochrome c and DCIP served as an electron acceptor. The M ichaelis constants for NADH. DCIP, FM N. and cytochrome c were 45, 2.9. 7.9 and 15 μM, respectively. Many properties of soluble NADH dehydrogenase were substantially different from those of the membrane-bound enzyme, suggesting different functions.

Biochemical aspects of circadian rhythms were studied using a long-day duckweed, Lemna gibba G3 cultured in short day condition (9 h light at 3800 lux followed by 15 h darkness), which was transferred in continuous light (LL) at the end (LL 0) of the last night period. With such a system I have previously reported a rhythm of affinity for NAD + of cytoplasmic NAD - dependent glyceraldehyde 3-phosphate dehydrogenase (Cyt-NAD -GPD ) 180° out of phase with that of affinity for NADP + of chloroplastic NADP-dependent GPD (Chl-NADP-GPD ) and that NADP + could increase in vitro the affinity for NADP + of Chl-NADP-GPD . I report here that NADP + can decrease in vitro the affinity for NAD + of Cyt-NAD -GPD as well, and furthermore, that the in vivo level of NADP + oscillates in phase with the rhythm of the affinity for NADP + of Chl-NADP-GPD. Moreover, I found the existence of mirror-image circadian rhythms, of comparable am plitudes, of in vivo levels of NAD + + NADH (total NAD) (with peaks, as the ones of Cyt-NAD - GPD. at LL 0 and 24) and of NADP + + NADPH (total NADP) (with peaks, as the ones of Chl-NADP-GPD, at LL 12 and 36). Consequently, a circadian rhythm in the rate of net in vivo production of total NADP (or NAD) might be expected 90° in advance of that in the level of total NADP (or NAD). Indeed. I found oscillations in the activities of NAD kinase and of NADP phosphatase with peaks occurring, respectively, at LL 6 and at LL 18. Moreover, in vitro treatments with EGTA (a Ca 2+ -chelator), chlorpromazine and W7 (both inhibitors of calmodulin) were able to both inhibit NAD kinase from its highest level of activity to its minimal one and activate NADP phosphatase from its lowest level of activity to its maximal one. I conclude, therefore, that the in vivo level of Ca 2+ -calmodulin could oscillate in phase with the rhythm of NAD kinase activity and induce the mirror-image circadian rhythms of activities of NAD kinase and of NADP phosphatase. I propose that the control sequence among the several circadian rhythms I studied could start with changes in Ca 2+ -calmodulin, then proceed through oscillations in NAD kinase and NADP phosphatase activities, leading to changes in NAD + , NADP + , and NADPH levels, which would themselves induce the Chl-NADP-GPD and Cyt-NAD -GPD rhythms.

Nitrate assimilation by Rhodopseudomonas capsulata AD2 was completely inhibited by ammonium only in young well illuminated cultures. At higher densities (A660 about 0.5) the addition of ammonium had no inhibitory effect, but the nitrate was only reduced to the level of nitrite, which appeared in the medium. Under both conditions the cellular level of nitrate reductase activity remained unaffected. In marked contrast to other R. capsulata strains both ammonium sensitive and insensitive cells could reduce nitrate in the light and in the darkness. In the light up to 90% of the reduced nitrate was assimilated, but in the dark the reduced nitrate was stoichiometrically excreted as nitrite. This behaviour was only shown by R. capsulata AD2 and BK5, while in other strains the nitrate assimilation was always completely inhibited by ammonium. The role of photosynthesis and respiration by the regulation of nitrate reduction is discussed.

Abtract Uptake-hydrogenase activity in the blue-green alga (cyanobacterium) Anabaena variabilis is dependent on the presence of nickel. Nickel depletion leads to an enhancement of net lightinduced hydrogen evolution, which is catalyzed by nitrogenase. Addition of nickel chloride to the culture reverses this effect by stimulating hydrogenase activity. Methylviologen/dithionitedriven hydrogen formation of permeabilized cells is decreased by nickel depletion.

Fluorescence measurements were performed with bean leaves and intact chloroplasts, which are characterized by a slow fluorescence decline. The fluorescence lifetime (ι) and the fluorescence relative quantum yield (φ) of intact chloroplasts, measured with the phase fluorometer, showed nearly proportional light-induced decrease with a halftime of ∼ 30 s, which was removed by 3-(3.4-dichlorophenyl)-1.1 -dimethylurea (DCMU), by 4.5,6,7-tetrachloro-2′-trifluoromethylbenzimidazole (TTFB). by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) at a low concentration and by gramicidin D. Simultaneously the slow light-induced increase in absorbance at 518 nm (ΔA 518 ), reflecting thylakoid membrane energization, was eliminated. The data on ι of intact chloroplasts are original, the other results agree with literature data. In leaves, the slow light-induced fluorescence decline, with ι dropping from ∼ 2 to ∼ 0.6 ns, was abolished by FCCP at a concentration of 5 μm. However, while ι was stabilized at a level close to the initial (maximum) one or somewhat higher, φ became close to the minimum value. Besides, the amplitude of ΔA 518 was lowered about three times. These effects seemed to be due to multiple action of FCCP as a protonophoric uncoupler and an electron transfer inhibitor. In the presence of another uncoupling agent, TTFB, which, besides, is a diuron-like inhibitor of the electron transfer in chloroplasts, we observed the light-dependent, but hardly linked to changes in membrane potential, great increase in ι of a leaf from ∼ 1.9 to ∼ 4 .3 ns, with φ decreasing slightly. Addition of DCMU together with FCCP to the incubation medium or infiltration of a leaf with DCMU alone stimulated the rise in ι only to ∼ 3 ns. The increase in ι of a leaf observed in the presence of FCCP and DCMU, and especially with TTFB, may be associated with protein conformation changes which (i) alter the lifetime of nanosecond recombination luminescence of the photosystem II and/or (ii) disturb excitation energy transfer from the light-harvesting chlorophyll a/b complex to other pigment-protein complexes.

The pH dependence of Fe(III)-amino acid complexes has been studied polarographically and by means of ESR spectroscopy. It could be shown that, at least, two complexes exist: one with a low molecular weight, ESR detectable at acid pH. and one with a high molecular w eight at alkaline pH, ESR non detectable. The half wave potential of Fe (III) is lowered by amino acid ligands. The redox interaction of the Fe(III)-amino acid complexes with vitamin C results in a decrease of the ascorbyl radical concentration. Ascorbic acid also forms a complex with Fe(III) as in­dicated by a polarographic half wave potential near -0.55 V vs. S.C.E. at pH 7.

The effects of the algicide PH 40-62 on photosynthetic reactions in spinach chloroplasts were studied. The compound proved to be an uncoupler of photophosphorylation, whereas inhibition of photosynthetic electron transport occurred at higher concentrations. The site of this inhibition was before photosystem II. The uncoupling effect was partially reversible. In a series of related compounds the uncoupling activity appeared mainly dependent on the lipophilic properties of the compounds but electronic effects also played a distinct role. Comparing these uncoupling data with those of some known series of uncouplers it appeared that lipophilicity determines the uncoupling activity in an identical way and a regression equation was found describing the uncoupling activities of 60 compounds belonging to four chemically different groups of com pounds.

Chloroplast Biogenesis, Inhibition of Chloroplast Replication, Sethoxydim. Sun-Type Chloroplast Sethoxydim not only blocks leaf growth and development of barley seedlings but also inhibits chloroplast biogenesis at all stages of development from proplastids to prochloroplasts, young and mature chloroplasts. Not only thylakoid synthesis, thylakoid multiplication and grana for­mation are affected, but also chloroplast replication. The chloroplasts of secondary leaves which before the sethoxydim application are in the stage of young, developing chloroplasts, remain in this differentiation stage when treated with sethoxydim. With their ultrastructural characteristics (e.g. lower stacking degree, higher proportion of exposed membranes, a lower thylakoid frequency etc.) they resemble sun-type chloroplasts. In the shoot meristem sethoxydim-treated plants contain only proplastids, whereas the plastids in the shoot meristem of control plants are already in the developmental stage between prochloroplasts to young chloroplasts. Mesophyll cells of sethoxydim-treated plants contain only one third of the chloroplasts found in the controls.

Three of the major soluble partitioned pools in the symbiotic cell, namely the host cell cytoplasm, the cytoplasm of the bacterial symbiont and the space between the two partners (the peribacteroid space) were assayed for selected enzymes. Whilst alanine dehydrogenase was found almost totally in the bacterial cell cytoplasm, other enzymes were more widely spread. Amongst these a-mannosidase, previously described as a vacuolar marker enzyme in eukaryotes, was found largely in the peribacteroid space. These results are discussed in relation to models of peribacteroid membrane biogenesis.

In the presence of 150(μ/ml of chloramphenicol, viability (dye exclusion test) of Ehrlich ascites tumor cells is not severely affected within 48 h; however the number of dead cells increases above this concentration; more than 10 mg/ml render all of the cells dye-positive within a culture period of 24 h. With the highest concentration tested (25 mg/ml) cells begin to lose viability 8 h after beginning of treatment. In the first passage in the presence of the antibiotic, proliferation of the cells is reduced by about 50%; in the second passage cell growth was about 65% that of controls. As is shown by flow cytometric analysis and BrdU-H33258 technique of flow cytometry, the reduction of proliferation in the second passage is caused by retardation of cell cycle progression of about 8 h; in the third passage the cell cycle is delayed by further 8 h as compared to controls. On recultivation in the third passage in the absence of the inhibitor an increase of cell number of about 75% of controls was observed. Lactate production and glucose uptake of the cells were stimulated by the inhibitor by about 20%; oxygen consumption was 60% that of controls after 24 h; however the ATP/ADP ratio of chloramphenicol treated cells was in the range of controls. Over a time period of 24 h the incorporation of [2- 14 C]thymidine is reduced to 34 ± 3%, incorporation of [2- 14 C]uridine was 88 ± 4% that of controls, incorporation of [U- 14 C]lysine was not significantly affected by 150 μg/ml of chloramphenicol; the same was found for the uptake of [2- 14 C]-α-aminoisobutyric acid. Electron micrographs of chloramphenicol treated cells reveal a high amplitude of swelling of all mitochondria with a translucent appearance of the inner compartment. The mitochondrial membranes remain largely intact but the number of cristae is drastically reduced.

Specific immune serum against photo-damaged DNA with the photoadducts of 8 -methoxypsoralen (8-MOP) was obtained. The antigenic determinant is a polynucleotide chain with a mono-photoadduct: a coumarin moiety of psoralen linked through a cyclobutane ring to the 5,6-bond of thymine. The specific rabbit antiserum was used in the immunofluorescence method, for the detection of photodamaged DNA in the kinetoplasts and nuclei of unicellular organisms Crithidia luciliae, in the nuclei of snap-frozen tissue of mammals, and in human blood lymphocytes. Detection by the immunofluorescence method was limited by psoralen availability in situ; the psoralen concentration should be in the range 0.05 -0.2 μg/cm 2 on specimens submitted to a topical application or about 1 μg/ml in cell suspension. The long-wave ultraviolet light (UV-A) exposure dose applied to the nuclei should exceed 1J/cm 2 .

Phospholipid, Bilayer, X-Ray Diffraction, Morphology, Dilaurylphosphatidylethanolam ine, Membrane Powder samples and oriented films of the synthetic phospholipid L-α-dilaurylphosphatidyl-ethanolamine (DLPE) were studied by X-ray diffraction over a wide range of hydration. Only small differences were found between the unit cell dimensions of DLPE powder and oriented-film specimens. These dimensions did not vary appreciably with hydration. In the multilayer DLPE structure, the molecules pack with polar groups parallel to the bilayer plane and hydro­ carbon chains perpendicular to it. Examination of oriented films by scanning electron microscopy gave information on the surface morphology. Complementary data on the lamellar packing of the molecules and the average thickness of the bilayers was provided by thin-section and shadow-cast preparations studied by transmission electron microscopy.

Large unilamellar vesicles were prepared by detergent removal from micelles containing phosphatidylcholine, phosphatidylethanolam ine and phosphatidylserine. Liposomes were then interacted with Megathura crenulata hemocyanin, a well studied channel former. Incubation of the resulting proteoliposomes on one side of a phosphatidylserine-containing planar bilayer under fusion conditions yielded strong current increases. Such increase is due to insertion of ionic channels from the liposomes into the planar bilayer. Studying the effects of Ba 2+ on the electrical properties of the channel we could show that the protein is always inserted into a bilayer during this process, i.e. fusion of proteoliposomes with the artificial membrane occurs. The strong non linearity of the current-voltage curve of the hemocyanin pore could be used as a probe of the extent to which fusion preserves the orientation of the channel through the bilayer.

Isolation of the Nuclear Membrane Insoluble Residue from G1 Arrested Cells and Immunological Comparison with the Corresponding Vertebrate Nuclear Fraction The Triton X-100 and High salt resistant residue of the nuclear envelope of Saccharomyces cerevisiae cells arrested in the G 1 phase of cell cycle with a mating pherom one was isolated. It showed the same electrophoretic protein pattern as the insoluble residue isolated from log-phase cells. Examination of nitrocellulose blots of nuclear protein fractions with antiserum raised against a vertebrate lamin failed to show any immunological cross-reaction.

The conductivity of normal and homozygous β-thalassemic erythrocyte suspensions has been measured over the frequency range from 5 KHz to 100 MHz in the temperature interval from 5 to 45 °C. The electrical parameters of the membrane, i.e., the capacitance CM and the conductance GM per unit surface have been calculated from an expression given by Hanai for the conductivity of a suspension of ellipsoidal particles covered with a shell. Some interesting differences between the normal and pathological state are evidentiated.

Two new cinnamoyl quinic acid esters were isolated from the methanolic extract of Meumathamanticum rhizome. They were identified as l-trans-O-caffeoyl quinic acid methyl ester and l-trans-O-feruloyl quinic acid methyl ester by the spectral data of the natural products and those of the acetylated derivatives.

Abtract The ratios of 13:9 isomers of the hydroperoxides produced during incubation of methyl linoleate with soybean lipoxygenase-1 were ca. 50:50 at pH 7.8 and ca. 70:30 at pHs 9.0 and 11.0, respectively. In striking contrast to the lipoxygenase-catalyzed hydroperoxidation of linoleic acid, the hydroperoxidation of methyl linoleate at pH 7.8 gave almost racemic 13-hydroperoxides and that at pHs 9.0 and 11.0 yielded methyl 13-L-hydroperoxylinoleate having low optical purities (L/D, ca. 45/30).

The main contribution to ESR spectra of lyophilized tissues of plant or animal origin usually is given by an anisotropic singlet, which is known to be caused at least in the majority of cases by the adsorption of an ascorbyl radical. Model systems have been in vestigated in order to discuss experimental parameters, which in fluence these spectra qualitatively and quantitatively.

Incubation of the Ca 2+ -ATPase in vanadate solutions leads to the formation of two-dimensional arrays in the sarcoplasmic reticulum membrane. Electron micrographic freeze fracture replicas show depressions on the inner leaflet for the first time. This indicates that the ATPase has moved perpendicular to the plane of the membrane. Our results also suggest that aggregation of the Ca 2+ -ATPase into the two-dimensional arrays occurs before they move into the membrane. These phenomena were observed as soon as 15 minutes after vanadate was added. The effects of vanadate appear to be completely reversible. When SR was incubated in the vanadate solutions and was then diluted into a buffer containing Ca 2+ and ATP, the ATPase activity was normal for up to several hours of incubation and only somewhat reduced after 3 days.

Mono-and bifunctional complexes of cis DDP and d-guanosine were isolated on Sephadex G-25. The presence of cysteine in incubation mixture resulted in the vanishing of bifunctional com plex of d-guanosine and the appearance of d-guanosine-cis DDP-cysteine complex in the eluted peak. It is also possible that the eluted peak contained no homogeneous product of the reaction.

Tetrahvmena cells treated with purified rabbit anti­ bodies to rat hepatocellular membrane exhibited a consider­ able increase in binding capacity on reexposure to the antibody 24 h later. Insulin binding was similarly enhanced by preexposure to the antibody, and vice versa, preex­ posure to insulin enhanced the later binding of rat liver receptor antibodies. This suggests that (1) the Tetrahymena and the rat possess similar insulin receptors, and (2) the receptor antibody is also able to induce imprinting for itself as well as for insulin. Concanavalin-A, noted for binding overlap with insulin, failed to induce imprinting either for insulin or for antibodies to receptors, whereas the latter did induce imprinting for Concanavalin-A.

Filamentous intranuclear crystals consisting of two sets of intersecting sheets are common in the intestinal epithelium. They are closely associated with chromatin granules but electron microscope cytochemistry using a modified Feulgen procedure did not show DNA in the crystal itself. Light microscope histochemical tests indicated that the crystals consist of protein.

Restriction patterns of mitochondrial DNAs (mtDNA) from different Oenothera berteriana and Oenothera odorata bastards are compared and the identity of mtDNA in hybrid forms with different com binations of nuclear, Filastid, and mitochondrial genom es has been determined, nheritance of m tDNA in these hybrids follows the pattern predicted by the genetic analysis. One hybrid is shown to nave a Oenothera berteriana nuclear and plastidal genom e with a mitochondrial genome of the Oenothera odorata type.

1-Nitropyrene-2-ol is not detectably mutagenic in the Salmonella test in the absence of mammalian activation. It is activated by the rat liver microsom e-containing preparation S9 and gives a mutagenic response similar to that of benzo(a)pyrene.

The chromophore of the visual pigment in different insect orders has been identified. The novel chromophore 3-hydroxy-retinal was found in Diptera and Lepidoptera, while in the other groups investigated retinal is the chromophore of the visual pigment.

Erythrocyte Survival. Osmotic Fragility, Fibrosarcom a Red cell survival studies in mice with benzo(a) pyrene [B(a)p]-induced fibrosarcoma indicate marked reduction in RBC 51Cr rW2. In contrast, the t w2 of erythrocytes from B(a)p injected but tumor-free mice was not declined. Increasing tumor burden resulted in increment in the severity of this disorder, and preincubation of normal red cells with tumor supernatant caused significant reduction (p < 0.05) in 51Cr t > /2 . It is suggested that the observed alteration in RBC life span may be due to the effect of tumor. Apparently, both intrinsic and extrinsic cellular defects could be implicated for this abnormality. However, the shortened survival cannot be attributed to altered osmotic fragility, since the erythrocytes of the fibro-sarcomatous mice were more resistant to hypotonic hemolysis in vitro. Abstract Red cell survival studies in mice with benzo(a) pyrene [B(a)p]-induced fibrosarcoma indicate marked reduction in RBC 51 Cr t 1/2 . In contrast, the t 1/2 of erythrocytes from B(a)p injected but tumor-free mice was not declined. Increasing tumor burden resulted in increment in the severity of this disorder, and preincubation of normal red cells with tumor supernatant caused significant reduction (p < 0.05) in 51 Cr t 1/2 . It is suggested that the observed alteration in RBC life span may be due to the effect of tumor. Apparently, both intrinsic and extrinsic cellular defects could be implicated for this abnormality. However, the shortened survival cannot be attributed to altered osmotic fragility, since the erythrocytes of the fibrosarcomatous mice were more resistant to hypotonic hemolysis in vitro.