Band 38, Heft 11-12

Chromatographic investigations on Helichrysum bracteatum revealed the presence of three flavanones in the bracts. Two of them were the well known flavanones naringenin and erio- dictyol. The third flavanone was identified as the hitherto in nature unknown 5,7,3′,4′,5′- pentahydroxyflavanone. This was accomplished by chromatographic and spectrophotometric comparison with an authentic sample prepared from 3,4,5,2′,4′,6′-hexahydroxychalcone-2′- glucoside. Moreover, precursor experiments with suitable white flowering mutants of Matthiola incana and Antirrhinum majus also confirmed that the third compound was identical with 5,7,3′,4′,5′-pentahydroxyflavanone.

The flavones present in three European species of Silene section Elisanthe (Silene diclinis, S. heuffelii and S. marizii) have been identified. The flavones of these species were compared with the flavones present in the three remaining species of section Elisanthe in Europe (5. dioica, 5. noctiflora and 5. pratensis). It was found that isovitexine-7-O-glucoside is present in all these species. The other flavones. notably the 2′-O-glycosylated ones, show a distribution over the species. The presence of flavone glycosylating genes in 5. diclinis, S. heuffelii and S. marizii was tested by biochemical means. The results of this experiment show that the gene g-G. controlling the formation of isovitexin-7-O-glucoside, is the basic flavone glycosylating gene in European species of section Elisanthe. The other flavone glycosylation genes, g-X, gl, gl-A, gl-R, fg and Fg are not present in all specie

A major phytoalexin produced by the fungus-inoculated leaflets of Diphysa robinioides has been identified as the new isoflavonoid 5,7,2′,4′-tetrahydroxy-6-(3,3-dimethylallyl)isoflavanone (diphysolone). It is accompanied by smaller quantities of diphysolone-4′ (or 2′)-O-methyl ether (diphysolidone), and the known isoflavonoids 5,7,2′4′-tetrahydroxy-8-(3,3-dimethylallyljiso- flavanone (kievitone) and 5,7,2′-trihydroxy-4′-methoxyisoflavanone (ferreirin)

Cutting-up leaflets of Lupinus polyphyllus induces a rapid increase of quinolizidine alkaloid accumulation of up to 400% within 2 to 4.5 h. In contrast to the diurnal alkaloid formation, this reaction takes place both in the light and the dark and even at 4°C. The effect is reduced in chloramphenicol-treated samples but unimpaired in cycloheximide-treated assays. Since quinolizidine alkaloids constitute probably an important means of a chemical defense system of lupins against microbes and herbivores, the wound-induction of alkaloid accumulation is discussed as a defense responsf

Fourteen tryptophan analogues have been characterized with regard to their growth inhibitory effects on Catharanthus roseus cell cultures, their inhibitory effect on anthranilate synthetase, their incorporation into protein and their substrate affinity to tryptophan decarboxylase. The toxicity of 12 of the analogues was directly correlated with their inhibitory effect on anthranilate synthetase activity. None of the analogues was efficiently incorporated into protein. Only 4 of the analogues (4-methyl-, 4-fluoro-, 5-fluoro- and 5-hydroxytryptophan) were good substrates for tryptophan decarboxylase while all other analogues were rather poor substrates or were not converted at all. Alpha-methyltryptophan was a competitive inhibitor of tryptophan de­carboxylase

Cell lines of Catharcmthus roseus were selected for resistance to 4-methyltryptophan (4-MT) in order to get strains with increased activities of tryptophan decarboxylase (TDC). This enzyme may exert a decisive regulatory control in indole alkaloid biosynthesis. 4-Methyltryptophan is a substrate for TDC and is detoxified by this enzyme. All 4-MT resistant cell lines showed increased TDC activity (3-to 10-fold) and higher accumulation of tryptamine (3- to 5-fold). Two of these cell lines with increased TDC activity accumulated indole alkaloids in the growth medium, whereas in wild type cultures and other resistant cell lines this was not the case. All the cell lines obtained were not only resistant to 4-MT (20- to 70-times more than wild type cells) but were also cross-resistant to other tryptophan analogues which are not metabolized by TDC. Therefore the resistance was not only due to a better detoxification of the analogue. The selected cell lines also contained 2 to 6 times higher levels of ʟ-tryptophan but the feedback sensitivity of the anthranilate synthetase of the resistant cells was not alteref

It could be shown by the reduction of the spin label (1,14) located within DPPC vesicles, that Na-ascorbate and K-isoascorbate can permeate membranes. At physiologic pH value, these two compounds exist as electroneutral radicals with a cyclic side chain structure. Ascorbic acid and isoascorbic acid, on the contrary, can hardly permeate such an artificial membrane. Since the radical will cause lipid peroxidation, it must be modified prior to permeation. This can be done by GSH which changes the radical state but maintains the electroneutral bicyclic configuration

The nature o f the high spin ferric iron complex located at g = 4.3 has been investigated by means of electron spin resonance spectroscopy and polarography. It could be shown that two complexes each exist in the acid and alkaline pH region, and that the iron is bound to two histidines, three citric acids, and probably to one bicarbonate. These results agree well with previous findings according to which the ligand field o f iron should be com posed mainly o f oxygen and nitrogen atoms. Another low-field signal located at g = 3.6 appears in the pH range from 2 to 7 only and exhibits its maximum where the g = 4.3 signal has its minimum . Its exact nature is still unknown but it seems to represent some intermediate state of the ternary Fe 3+ - histidine-citric acid complex. When citric acid is used, the spin concentration seems to be always larger than in the case of ascorbic acid. Since the effect obtained with ascorbic acid and citric acid seems to be similar, it may be concluded that the biological function of both of the acids might be somehow related to each other

Enzymatic hydrolysis of waste papers in the presence of various vinyl compounds was carried out, and the addition of the compounds such as methyl methacrylate, styrene, and vinyl acetate increased glucose yield resulting from the acceleration of the rate of the enzymatic hydrolysis. The optimum conditions existed for the acceleration of the rate of the enzymatic hydrolysis. The magnitude of the acceleration effect appeared to be considerably depended on the nature of the compounds. The acceleration effect of the hydrophobic vinyl compounds was explained according to a dispersion and swelling action

A dissimilatory nitrite reductase from the facultatively phototrophic bacterium , Rhodopseudomonas palustris strain 1a1 was studied. A basic level of the enzyme (10 -50 mU/mg protein) was measured in dark, aerated and anaerobic, photosynthetic cultures. A marked derepression of enzyme synthesis occurred under conditions of oxygen limitation (200-300 mU/mg protein). The addition of nitrite (or nitrate) to the culture medium had only a slight effect on the maximal nitrite reductase titer of cells. The enzyme was purified from photosynthetically grown cells by precipitation with ammonium sulfate, gel filtration through Sepharose 6B and repeated chromatography on DE 52-cellulose. As estimated by gel filtration, the nitrite reductase had a molecular weight of about 120 000 ± 12 000 and yielded only one band (mol. wt. of about 68 000 ± 7000) in SDS-gel electrophoresis. The isoelectric point of the enzyme was at pH 5.1. Nitric oxide (NO) was identified as the reaction product of nitrite reduction. The enzyme also exhibited cytochrome c-oxidase activity and was active with chemically reduced viologen dyes, FMN and cytochrome c as electron donors. Highly purified nitrite reductase preparations contained 10 mol% of a c-type cytochrome. Trace metal analyses indicated the presence of Cu in the enzyme. Consistent with the detection of Cu was the finding that the Cu-chelator, diethyldithiocarbamate, strongly inhibited the nitrite reductase

Neocarzinostatin, a highly toxic antitum or protein containing an essential nonprotein chromophore, can be isolated and purified from culture filtrates of Streptomyces carzinostaticus. Usually a lengthy procedure of up to 60 h is necessary for the isolation, including several chromatographic steps partly under conditions which favour inactivation of the drug by release of chromophore. We describe a new method yielding practically clinical grade Neocarzinostatin from crude extracts in 20 min. This very fast and reproducible method was made possible by using a Mono Q anion exchange column filled with monodisperse gel material which has been recently developed

The synthesis of 15 N-labeled coprobiliverdin III, a bile pigment with four conjugated pyrrole nuclei and four carboxylic acid side chains, is described. Coprobiliverdin is structurally characterized by chemical and various spectroscopic methods (e.g. chromic acid degradation, UV-vis-, IR-, mass spectroscopy). The results of 15 N NMR studies reveal the potential value of this compound as a probe for structural interactions in biliproteins and as a reference for the future investigation of natural bile pigments deriving from coproheme

The circular dichroism of bilipeptides from Spirulina geitleri phycocyanin is strongly solvent and pH dependent. Maximum optical activity has been observed in aqueous solutions containing urea (8 ᴍ). In aqueous buffer, a sign reversal occurred upon the change from neutral to acidic pH; in methanolic solutions shows the optical activity a strong pH dependence both with respect to sign and magnitude. These findings have been rationalized by the presence of chrom ophorepeptide interactions, which are minimized in the presence of urea. M olecular orbital calculations indicate that the observed sign reversal is not necessarily due to a reversal of the chirality of the entire chromophore, but may also result from more localized conform ational changes

Two soluble acidic c-type cytochromes - c' and c-552 - were isolated by ion exchange :hromatography, gel filtration and ammonium sulfate fractionation. Cytochrome c' is a high-spir tochrome with maxima at 399 nm. 490 nm. and 634 nm in the oxidized form and at 550 nm. 15 nm and a characteristic shoulder at 434 nm in the reduced state. The best purity index obtained A 280 /A 399 ) was 0.35. Cytochrome c' is autoxidizable, has a molecular weight of 12 000 (estimate by sodium dodecylsulfate electrophoresis), a midpoint redoxpotential of + 10 mV and an iso­electric point at pH 4.0. The reduced cytochrome c' reacts with carbon monoxide. The reaction reversible. Cytochrome c-552 shows maxima at 552 nm, 523 nm and 417 nm in the reduced for ind at 408 nm in the oxidized state. The best purity index obtained (A 280 /A 408 ) was 0.94. "ytochrome c-552 has a molecular weight of 30 000 and an isoelectric point between pH 4.1 Zhromatium warmingii also contains a membrane-bound cytochrome c-552. During anaerobic sulfide oxidation, elemental sulfur and sulfate were formed at the same time. When all sulfide consumed by the cells, the remaining intracellular elemental sulfur was further oxidized to sulfate

High potential iron sulfur protein (HIPIP) of the purple sulfur bacterium Chromatium warmingii was purified to homogeneity by ion exchange chromatography, gel filtration and ammonium sulfate fractionation. The acidic protein was isolated in the reduced form. The best purity index (A 280 /A 388 ) obtained was 2.52, and 3.8 μmol of the protein was isolated out of 100 g wet cell material. The molecular weights estimated by sodium dodecylsulfate polyacrylamide gel electrophoresis and gel filtration through Sephacryl S-200 were 8 900 and 10 500, respec­tively. The protein has an isoelectric point at pH 3.6 for the reduced form and at pH 3.8 for the oxidized form, and a midpoint redox potential of +355 mV. One mol of HIPIP contains 4 mol nonheme iron and 4 mol acid-labile sulfur

The phycobiliproteids of cyanobacteria have two functions. They are accessoric pigments for the light-dependent photosynthetic electron transport, and, secondly, they are storage proteins. Cyanocyta korschikoffiana, the endocyanelle of Cyanophora paradoxa, a hardly adapted endocytobiotic cyanobacterium, is responsible for the photoautotrophy of the host flagellate. The biosynthesis of the phycobiliproteids takes place in the endocyanelles and is reversible. Under nitrogen starvation the phycobiliproteids were disintegrated again, in contrast to the carotenoids (and in a lower degree to chlorophyll), whose contents rem ain more constant in the cells, as shown by in vivo measurements. Therefore, it is concluded that sim ilar to the function in free living cyanobacteria the phycobiliproteids of C. paradoxa also serve as storage substances (“stress proteins”). This opinion is supported by experiments with chloramphenicol

It is not clear whether an endocytobiont is able to develop during a long evolution tim e only to an organelle like cell structure (defect mutant) with a high degree of m etabolic dependency or also to a perfect cell organelle with genetical dependency to the host nucleus (intercom partm ental translocation of proteins and/or gene transfer) in the sense of the Serial Endocytobiosis Hypothesis (SEH). Cyanocyta korschokoffiana, the endocyanelle of C. paradoxa, seems to be a very suitable object to answer this question. Therefore we have studied the influence of the translation inhibitors cycloheximide (CHI) and chloramphenicol (CA) on the biosynthetic behaviour of this cyanobacterial endocytobiont regarding the photosynthetic oxygen during 20 h developing and incubation time. After dilution with fresh culture medium the oxygen evolution of the control culture remains nearly constant, if it is related to the phycocyanin content, whereas it increases slowly to a constant level relating to the chlorophyll content (nearly 140-150% of the starting activity). CHI and CA show a rapid effect on the oxygen evolution. At the first 8 - 10 h the oxygen evolution of cultures treated with CA are hardly dim inished and remain more or less constant with regard to the starting activity, but that of cultures treated with CHI decreases strongly. After 24 h the CHI treated flagellate is photosynthetically inactive and far-reaching destroyed (microscopic observations), indicating that CHI has beside the inhibition effects on protein synthesis also secondary effects on the stability of membranes of C. paradoxa

To prove the extent to which the endocyanelle of C. paradoxa is autonomous with respect to the biosynthesis of its photosynthetic pigments, the degree, to which the translation inhibitors cycloheximide (CHI) and chloramphenicol (CA) influence the biosynthesis of carotenoids, was investigated by two methods (in vivo VIS-spectroscopy and photosynthetic l4 C-incorporation into the pigments). During the first 6 h (in vivo VIS-spectra) the probes treated with the inhibitors show a similar increase of the total carotenoid content as the control, thereafter the inhibition by CHI is increased significantly at approx. 50% (18 h), by CA somewhat lower. The [ 14 C]carbon- dioxide incorporation into β-carotene do not show any notable differences between the control culture and the cultures treated with inhibitors. Quite different to this observation is the behaviour of zeaxanthin. CHI shows an inhibition of 60% after 8 h, whereas CA accelerates the biosynthesis of zeaxanthin at +60% (to the control). Zeaxanthin has the same absolute concen­tration, but it was marked only ten times lower than β-carotene. The greater effect of CHI (in vivo VIS-spectra) should not be taken as a higher participation of the eukaryotic genome. In contrast that is only to ascribe to the inhibition of the photosynthetic activity, which is in the same order of magnitude. Additionally the behaviour of zeaxanthin seems to be more a sign for higher participation of the prokaryotic genome

The inhibition effects of CHI and CA on the biosynthesis of the tetrapyrrolpigments were measured with two methods (in vivo VIS-spectroscopy, for chlorophyll (Chi) and the phycochromoproteids, 14 C incorporation only for Chi). In the case of the Chl-biosynthesis both methods show the same results: a) In vivo VIS-spectroscopy demonstrates that the inhibition effect of CA manifests faster than that of CHI, b) during the 14 C incorporation into Chi chloramphenicol (CA) inhibits more than cyclohexim ide (CHI) in contrary to the behaviour of chloroplasts. It seems that the CHI caused decrease of 14 C incorporation into Chi can be ascribed to the decreased photosynthesis. The influence o f the antibiotics of the phycochrom oproteids is similar to that observed for chlorophyll. It is remarkable that under the influence of CHI the phycochromoproteid biosynthesis is significantly better than under CA influence, although CHI damages the consortium more than CA. That can be interpreted, as for chlorophyll, with a more endocytobiont coded phycochrom oproteid synthesis

Leaves, cotyledons, isolated chloroplasts and subplastid fractions (thylakoids and envelopes) of radish (Raphanus sativus L. cv. Saxa) and spinach (Spinacia oleracea L. cv. M atador) were assayed for their pigment and quinone content and com position. Virtually all the chlorophylls, carotenoids and quinones were contained in the thylakoids. Envelopes prepared by the method described contained very low amounts o f chlorophyll a and b, violaxanthin and neoxanthin, but no β-carotene, lutein, zeaxanthin and antheraxanthin. Among the quinones trace amounts of plastoquinone and a-tocopherol but no plastohydroquinone, a-tocoquinone and phylloquinone were detected. Presented data may be taken as evidence that in vivo the chloroplast envelope is not a location site of carotenoids and quinones as generally accepted. Possible im plications for the biosyntheses of quinones and pigments are discussed

Mixed monolayers containing chlorophyll a and dim yristoyllecithin (DML) have been investigated by simultaneous thermodynamic, fluorescence and absorption spectroscopic measurements. It has been shown that the solubility limit of chlorophyll a in the fluid, as well as in the solid lipid matrix, is above 20 mol%. This contrasts to previous findings for pheophytin a containing monolayers and indicates the existance of an interaction between the phospholipid head group and the central Mg atom. A fluorescence decrease on solidifying the monolayer was observed and it is suggested that it is due to an enhanced self quenching as a consequence of the reorientation of the porphyrin rings, accompanying the phase transition

Z-7-Dodecenyl acetate and Z-7-dodecenyl alcohol have been identified as sex pheromone components o f female Autographa gamma. This is the first time that Z-7-dodecenyl alcohol has been found in the natural pheromone of Plusiinae. When incorporated in pherom one traps of some Plusiinae species the alcohol is both synergist and inhibitor, thus being an important factor in sex isolation among sympatric Plusiinae species in Israel

Vanadate binding to sarcoplasmic reticulum vesicles results in the loss of the externally located high affinity calcium binding sites of the calcium transport ATPase. Conversely the occupation by calcium of the internally located low affinity sites in the vanadate enzyme complex leads to the release of vanadate. Since the total number of calcium binding sites is not diminished by vanadate binding but slightly increases we conclude that vanadate binding induces a transition of the enzymes external high to internal low affinity calcium binding sites. The transposition of external to internal calcium binding sites is accompanied by a definite change in the structure of the sarcoplasmic reticulum membranes. On vanadate binding the asymmetrically arranged electron dense protein particles become symmetrically distributed

In order to compare the kinetics of their enzymatic elimination from the DNA of liver, kidney, lung, and brain, the alkylation products O 4 -ethyl-2'-deoxythym idine (O 4 -EtdThd) and O 6 -ethyl- 2'-deoxyguanosine (O 6 -EtdGuo) were quantitated by competitive radioimmunoassay over a period of 48 h after a single pulse of the carcinogen N -ethyl-N-nitrosourea (EtNU ) applied i.p. to 10 and 28-day-old BDIX-rats. The content of O 4 -EtdThd in the DNA of all organs analyzed remained stable, while O 6 -EtdGuo (initially formed in DNA with 3 - 4 times higher frequency than O 4 -EtdThd) was rapidly removed from the DNA of liver, followed by lung and kidney, but persisted strongly in the DNA of brain. At 48 h after the EtNU -pulse, the O 4 -EtdThd content of liver DNA exceeded the O 6 -EtdGuo content by about a factor of 4. Since both O 6 -EtdG uo and O 4 -EtdThd are miscoding DNA lesions, the lack of enzymatic removal of O 4 -EtdThd is surprising in view of the apparent concern of cells to restore the integrity of the Opposition of guanine. Genetic consequences more specifically connected with the formation of O 6 -alkylguanine in DNA might be considered, e.g., possible alterations of gene expression via interference with enzymatic 5-cytosine methylation in 5'-CpG-3' sequences of newly replicated DNA

Single stranded DNA (ssDNA) in aqueous N 2 O-saturated solution was pulse-irradiated with electrons or irradiated under steady-state conditions with 60 Co-y rays. The conductivity increase after irradiation was measured as a function of concentration. pH, temperature, metal cation content and additives. The conductivity increase could be shown to be due to the release of associated counterions (Na + or H + ) as a result of the formation of chain breaks. At 28 mg 1 1 DNA ~ 8 sodium ions are liberated per 100 eV absorbed energy (G(Na + )= 8.3). On the basis of G value for single-strand breaks (ssb) of G(ssb) = 0.55, it is calculated that 8.3/0.55 = 15 sodium ions per strand break are set free. The release of Na + monitored by 23 Na-NMR at pH 7 as a function of dose corresponds to that of the conductivity increase. The rate of the conductivity increase does not depend on dose/pulse (range 2-20 J kg -1 ) and shows at least two components. The rate constant of the fast and dominant component is constant above pH 8.5 (A: = 38 s _ 1 , 20 °C) and increases linearly with proton concentration below pH 7. Values of 13kcal/mol for the activation energy and 5x 10" s _l for the frequency factor were obtained at pH 7.3. Addition of /7-benzoquinone (pBQ) increases the rate constant of the fast component proportionally to the concentration of pBQ. From these results the rate-determining step of the fast conductivity increase is concluded to be the splitting of DNA radicals. The pH dependence and the magnitude of the activation energy agree with results from low molecular weight model compounds for the C-4' mechanism; this mechanism involves a heterolytic splitting of the phosphoric acid ester bond starting from the 4' radical of DNA

Receptor potentials of Limulus ventral nerve photoreceptors were evoked in reproducible states of moderate light- and considerable dark adaptation (LA, DA) with light stimulus intensities from threshold to saturation values using a repeated flash sequence. With increasing light intensities latent period and time-to-peak shortened in the state of both LA and DA The decrease-time is prolonged by increasing stimulus intensities (LA and DA) and continues to rise even when the amplitude of the receptor potential is already saturated. The sigmoid response height vs. log stimulus intensity curve is shifted upon LA towards higher stimulus intensities, and its steepness is increased. LA prolongs latent period and time-to-peak at low light intensities; at high light intensities, however, the DA-values are longer. The decreasetime of the receptor potential is always shorter in the light-adapted state. The results are discussed according to the assumption that size and duration of the receptor potential are primarily determined by the distribution of bum p latencies. Changes of the receptor potential parameters are explained by changes of bum p size and of bum p latency distribution due to light adaptation.

In contrast to earlier reports, the major anthocyanin of carrot cells grown in tissue culture has been identified as cyanidin 3-(sinapoylxylosylglucosylgalactoside). It is thus the same as one of the major acylated pigments in the leaf and flower of the whole plant. Daucus carota is therefore not anomalous among higher plants in its anthocyaninsynthesising capacity in callus or shake culture

Cotyledons isolated from maturing seeds of Juglans regia incorporate supplied [ 15 N]-ammonia into serotonin (5-HT). A 15 N incorporation of about 9% into the indolic nitrogen of 5-HT is detectable by gas chromatographymass spectrometry following isolation of 5-HT by preparative HPLC. This 15 N incorporation supports the hypothesis that biosynthesis and accum ulation of 5-HT play a role in ammonia detoxification in maturing walnut seeds

The N-terminal sequence of porphobilinogen-synthase (EC 4.2.1.24) from bovine liver up to position 44 is given. After tryptic hydrolysis two N-terminal peptides with identical amino acid composition were isolated in the ratio 1:1. One peptide was blocked whereas the other one started with methionine and showed the same primary structure which had been estimated by automatical degradation of the enzyme. Four of the eight subunits of PBG-S have free methionine as N-terminal amino acid whereas the other half is blocked

The primary sequence of the prom inent Cucumis melo satellite DNA is presented. The cloned Hind III-repeat unit has a length of 352 bp and a GC-content of 56%. Within this sequence an inverted repeat of 9 bp, including a 286 bp loop, and one direct repeat are shown. Several open reading frames are possible following the sequence in both directions whose significance is not yet clear. The sequence has been compared with other highly repetitive DNA sequences of Sinapis alba and Scilla sibirica. The genomic satellite DNA exhibits an unusual behaviour in actinomycin D-CsCl gradients in comparison to ribosomal D NA

Head extracts of adult workers of the Brazilian stingless bee Scaptotrigona postica (Trigonini, Meliponinae: Apidae) were analysed for volatile substances by gas chrom atography/ mass spectroscopy. Individual worker bees performing clearly defined tasks and representing five age groups were collected. A total of 36 compounds was identified, 22 of which had not been previously described for a Trigona species. The major components are 2-heptanol, 2-tridecanone, 2-pentadecanone, Z-5-tetradecenylbutanoate and Z-7-hexadecenylbutanoate. 11 of the 36 compounds increase in concentration with age, but only 2 decrease. The other substances are present in more or less constant concentrations. These data are discussed assuming more complicated pheromone-m ediated interactions within an age-dependent polyethism between old workers acting inside and outside the nest than between young house bees

The mating pheromone of baker’s yeast, the a-factor, is a dodeca-/tridecapeptide, which is not antigenic by itself. It was coupled to succinylated thyroglobulin by the carbodiimide procedure to facilitate selective coupling of the a-factor mainly by its N-terminal region. Antibodies against this conjugate were raised in rabbits. After selective precipitation of the rabbit antiserum with succinylated carrier prior to the radial double diffusion test (Ouchterlony) specific antibodies against the coupled a-factor could be detected

The primitive metazoon, Trichoplax adhaerens (Placozoa), can easily be cultivated with Nauplius larvae of the brine shrimp, Artemia salina, killed by heating, as food organism