Band 39, Heft 11-12

Mouse lymph node lymphocytes are irradiated at different dose rates and the B-cell receptors to anti IgG are tested. The expression of receptors is inhibited by irradiation. It is shown that the effectivity of irradiation increases with decreasing dose rate suggesting that membrane damage may be important for situations of chronic irradiation or implant radiotherapy.

4,8-Dimethyl-11-isopropyl-6,8-dihydroxy-pentadeca-4,9-dien-14-on-1-al (3) was identified as a new natural product from tobacco. 3 was isolated from the surface gum of fresh tobacco. The spectral data, chemical properties and the synthesis 3 are given.

Extraction of fresh sporophores of the fungus Agaricus xanthodermus yields 4,4′-dihydroxy-azobenzene, phenol, p-quinol, and 4,4′-dihydroxybiphenyl. This is the first report of an azo compound arising endogenously in nature, while phenol, p-quinol and 4,4′-dihydroxybiphenyl have not previously been isolated from higher fungi. Phenol is present in fruitbodies in sufficiently high concentration to account for the toxicity of A. xanthodermus.

The accumulation of volatile flavour constituents in liquid cultures of three Kluyveromyces lactis strains was studied after cultivation on defined culture media containing glucose as carbon source, yeast extract, vitamines, and different additional nitrogen compounds. Besides short-chain alcohols and esters (fruit esters), 2-phenylethyl alcohol, phenylacetaldehyde, and 2-phenylethyl esters could be identified by gas chromatography and coupled gas chromatography-mass spectrometry. Although the composition of these compounds was qualitatively comparable within the three strains investigated, quantitative differences were significant and strain-dependent reactions to the culture medium could be observed.

Organelles found in the 1000 x g fraction of latex taken from Papaver somniferum have been shown to accumulate dopamine to the exclusion of other catecholamines. Dopamine accumula­ tion is both temperature and pH dependent and there is no evident requirement for ATP (1 mᴍ) or Mg 2+ (2mᴍ). The relatively high (4.37 mᴍ), specificity of dopamine uptake, and insensitivity to inhibitors distinguish papaver latex organelle dopamine uptake from catecholamine uptake by mammalian chromaffin granules.

A total of 28 strains of several species of Rhizobium were screened for the presence and regulation of the enzyme alkaline phosphatase. In contrast to all other species of Rhizobium, the activity of this enzyme was absent in R. trifolii. Different levels of alkaline phosphatase were observed in various species of Rhizobium. Both, species as well as strain specific differences were found in the level of alkaline phosphatase.

[4-(3-Bromoacetylpyridinio)-butyl]adenosine pyrophosphate as a structural analog of NAD + reacts covalently with the sulfhydryl groups of thiopropyl agarose. 10-20 μmol can be bound to 1 ml gel. Stabilization of the insoluble coenzym e is attained by treatment with sodium boro hydride (NaBH 4 ). This complex when applied to column chromatography, allow s the separation of various dehydrogenases as a result of their different complex stability coefficients. Alcohol dehydrogenase from liver, lactate dehydrogenase, and adenylate kinase, which all bind to the ADP-analog residues of the gel matrix, can thus be separated by different salt gradients. Alcohol dehydrogenase from yeast, however, does not form a complex and can easily be eluted from the column with phosphate buffer. Glyceraldehyde-3 phosphate and aldehyde dehydrogenases can be eluted by the addition of NAD + or NADH to the buffer. The uncharged 1,4-dihydropyridin ring of the reduced coenzyme produces a more stable complex with the dehydrogenases than the oxidized form.

Affinity resins with different spacer arms were synthesized analogues to the solid phase peptide synthesis using aminoethyl cellulose or carboxymethyl cellulose as matrix. The spacer arms could be varied in length and rigidity. Especially spacer arms consisting of poly am ino acids can be synthesized with a defined amount of amino acid residues specifically in the low molecular weight ranges. The method is also applicable to other matrices w hich are not susceptible to 1 ɴ HCl in glacial acetic acid, trethylamine, methylene chloride and dimethylformamide. The synthesis of affinity resins with different spacer arms for the purification of androgen receptors is described as an example of the method.

The method presented here enables the isolation of three monofunctional adducts. These are: platination of cytosine, adenine and guanosine. The three detected bifunctional complexes were: guanine N7 to N7, adenine N7 to N7 and adenine N7 to N1. A mixed bifunctional complex of guanine and adenosine and the product of polymerization of three adenines and two moieties of cis DDP were also detected. In the peak eluted separately from the guanine standard, no Pt was detected. The sample eluted in this peak had UV spectrum different from the standard and may represent the degraded product of guanine and polymerized Pt.

The production of platinated derivatives of nucleic acid bases resulting from the reaction of cis and trans DDP with DNA and chrom atin was studied. Bifunctional complex of guanine appeared to be the major product of the interaction of cis isomer with both DNA and chromatin, although other bifunctional adducts of A-Pt-G and A-Pt-A were also isolated. The main product of the interaction of trans DDP with DNA was a monofunctional adduct of guanine. Small amounts of the bifunctional complexes were also isolated. When ssDNA was incubated with trans DDP more bifunctional complexes appeared, what suggests that geometric constrains of double helix prevent formation of these complexes. Trans isomer reacts more easily with chromosomal proteins than cis DDP does. Therefore after the reaction of trans DDP with chromatin less platination occurs on DNA moieties.

The structure of the galactan isolated from the album in gland of Achatina fulica (African giant snail) was investigated by methylation analyses. The molecule is highly branched. The linkages of the exclusively present D-galactose are 1→3 and /or 1→6. From lectin binding studies it was learnt that the 1→3 linkages possess β-configuration. The anomeric configuration of the 1→6 linkage is unknown. A tentative structure of the galactan is proposed.

Radiolabeled manducin, which is the arylphorin (i.e. tyrosine-rich larval serum protein) of the tobacco hornworm Manduca sexta was prepared by in vivo biosynthesis from [U- 14 C]-ʟ-tyrosine. In order to see whether manducin is incorporated into the cuticle of developing pupae and participates in cuticle sclerotization, the radiolabeled protein was injected into late last larval instar larvae. Fractionation of the sclerotized pupal cuticle into a buffer soluble, acid soluble and acid insoluble fraction shows that up to 2.6% of peptidic tyrosine residues end up in the acid soluble portion. Another 0.5% are recovered from the acid insoluble fraction by combustion. Only 30% of peptidic tyrosine residues of manducin incorporated into the acid soluble fraction are recovered as tyrosine. The presence of radioactivity in the acid insoluble fraction suggests that peptidic tyrosine residues are transformed partly into melanin-like material. The in­corporation of manducin into the cuticle of pupae is also evident from immunological studies. Relative large quantities of radiolabeled acid insoluble melanine like material is also recovered from sclerotized cuticle after incorporation of radiolabeled tyrosine as well as tanning substrates N-acetyldopamine and N-β-alanyldopamine. Application of doubly labeled [7- 3 H,8- 14 C]-N-acetyldopamine shows a high loss of 3 H in the acid insoluble fraction. It is suggested that tanning agents form lignine-like polymers and that sclerotization results from copolymerization with peptidic tyrosine residues in the cuticle. Thus, the arylphorin manducin appears to be an important constituent of the sclerotization system in Manduca sexta.

Calf thymus histone octamer complexes were irradiated in the native state in N 2 O-saturated dilute aqueous solution (0.5 g/l, pH 9, [NaClO 4 ] = 1-4 mol/1) with 50 or 100 ns pulses of 16 MeV electrons or 60 Co-γ-rays. Tim e resolved light scattering measurem ents and optical ab­sorption measurements yielded the following: the octamers underwent a volume contraction due to intra-complex-crosslinking induced by the attack of OH-radicals. Crosslinking proceeded to a certain extent via 2 ,2′-biphenol coupling as inferred from product analyses.

Nitrate reductase from spinach (Spinacia oleracea L.) leaves, which had been inactivated in vitro by incubation with NADH and cyanide, was fully reactivated in minutes when irradiated in anaerobic conditions with red light in the presence of methylene blue. Both the rate and the extent of reactivation increased with light intensity (6 to 100 W·m -2 ) and dye concentration (1 to 10 μM). On the contrary, photoreactivation was completely abolished when NADH or ethylenediaminetetra-acetic acid were present during irradiation. We propose that methylene blue, when photo excited, exhibits a redox potential positive enough to reoxidise the CN - -re-duced molybdenum complex settled in the inactive enzyme, thus causing its reactivation. On the other hand, prolonged irradiation of nitrate reductase, under air and in the presence of methylene blue, promoted an oxygen-dependent irreversible inactivation of the two partial activities of the enzyme. This inactivation was markedly enhanced in 77% deuterated water and greatly prevented by azide, which indicates that singlet oxygen is the species primarily involved in the photooxidative inactivation of the enzyme.

Fluorescence detected ODMR measurements in zero field on the triplet state of the reaction center in whole cells of Rhodopseudomonas viridis, in reaction center solution and in reaction center crystals are reported. In solution and in the crystal a sign reversal of the F-ODMR signals is observed by variation of the wavelength of detection. The signs of the signals are interpreted with the Vredenberg-Duysens relation.

Etioplasts isolated from oat leaves that have received two 5 min illumination periods, spaced apart by a 90 min dark interval, are able to evolve oxygen. If this oxygen evolution is measured as consequence of short saturating light flashes a pattern is obtained which in agreement with the Kok-Joliot model shows a damped oscillation with a periodicity of four. As usual for most other systems the maximum flash yield is observed under the third flash. In continuous light such slightly greened etioplasts show a small oxygen gush. From our studies it appears that the second 5 min illumination period is obligatory for oxygen evolution. Omission of this period leads to a condition in which under flashes strictly no oxygen is evolved. In continuous light under these conditions no oxygen gush but rather an uptake is observed after onset of illumination. It appears that in greening etioplasts the flash pattern shows some peculiarities when compared to the normal green conditions. Thus, a flash sequence of a greening etioplast always shows a substantial positive amperometric signal under the first flash. The half time of the state which would belong to this signal is 3 to 4 min in a greening etioplast, isolated from leaves that have received 2 h light. In the course of greening this half time decreases continuously and reaches a normal and constant value of approx. 10 s in chloroplasts from green oat or etiochloroplasts that are prepared from leaves that have received 15 h of light. The result is discussed in terms of metastable S 3 which seems to be a property of the developing oxygen evolving system in greening oat leaves. In the greening system as we use it is shown for the first time that the photoenzyme protochlorophyllide chlorophyllide reductase is DCMU sensitive.

The O 2 yield under flash light illumination in preparations of Anacystis nidulans was examined in the presence of redox components such as ferricyanide and ferrocyanide. When ferricyanide (1 mᴍ) was added to the lyophilized, lysozyme treated and EDTA washed cells of A. nidulans the familiar Joliot-Kok oscillalion with maximum on the third flash and periodicity of four was observed (in the presence of added CaCl 2 and MnCl 2 ). However, when the ferricyanide con­centration was increased to about 8 mᴍ , a reduction of the O 2 evolution under flash illumination was observed, and an O 2 uptake could clearly be seen under the first and second flash. This O 2 uptake was inhibited by DCMU and o-phenanthroline, but was not influenced by KCN or salicylhydroxamic acid. As ferrocyanide was progressively added to 1 mᴍ ferricyanide, the oscillations faded out and the steady-state O 2 evolution decreased. Light would progressively increase the O 2 evolution and reduce the damping of the oscillations. Two patterns of O 2 evolution under short saturating light flashes were observed with these Anacystis preparations on first illumination in the presence of cations but in the absence of ferricyanide. One pattern corresponded to the typical pattern which has been repeatedly described in the literature, but the second pattern gave the indication of an initial “over-reduced” state of the photosystem II reaction center. With suitable procedures the two patterns were interchangeable. Moreover, the effect of ʟ-arginine on the flash pattern was examined. The results are discussed in connection with the possible dual function of the previously described flavin protein as an ʟ-amino acid oxidase and as a component of the O 2 evolving reaction center (E. K. Pistorius and H. Voss, Eur. J. Biochemistry 126,203-209 (1982)).

Application of elevated pressure (up to 1200 bars) results in a bathochromic shift of the absorption bands of photosynthetic pigments. The photosynthetic systems studied include: photosystem I particles, chloroplasts, acetone extracts of chloroplasts, AUT particles and light harvesting particles of Rh. sphaeroides, light harvesting particles of R26. Similar spectral changes are observed in all systems. The spectral shifts appear to be associated with pressure-induced changes in the local electric fields of the pigments, rather than changes in the index of refraction of the solvent.

The transfer of triplet excitation from chlorophyll to zeaxanthin in liposomes is a function of temperature and pigment concentration. At 525 nm both chlorophyll and zeaxanthin triplet states are observed. The result is a biphasic increase in absorption. The rise time of absorption by the chlorophyll triplet is much faster, than by the zeaxanthin triplet. With increasing temperature the contribution of absorption by zea­xanthin (relative to that of chlorophyll) at 525 nm increases, and its rise time gets faster. At high ratios of zeaxanthin to chlorophyll, temperature has less effect on both the rise time and absorption by the zeaxanthin triplet state. The chlorophyll triplet is measured at 780 nm. It decays faster with increasing temperature and or increasing ratio of zeaxanthin to chlorophyll. The results are interpreted in terms of: increasing fluidity of the lipid liposome with temper­ature, formation of zeaxanthin-chlorophyll complexes at high ratios of zeaxanthin and chloro­phyll, presence of different lipid phases in the liposome bilayer.

Intracytoplasmic membrane vesicles (chromatophores) isolated from Rhodopseudomonas capsulata cells were fused with liposomes by a pH transition procedure. Vesicles of lower density and higher lipid contents and larger diameter than chromatophores were obtained. Similar results were observed by Ca 2+ induced fusion and by the freeze-thawing method. Respiratory and light-induced electron transport were measured in chromatophores and fused vesicles. Light-induced reaction center bleaching was observed in all types of vesicles, whereas repiratory electron transport was substantially diminished by lipid incorporation. Ubiquinone 10 restored to some extent respiratory electron transport and oxidative phosphorylation and it modified the photophosphorylation kinetics under continuous light. Electrochromic carotenoid band-shift and the 9-aminoacridine fluorescence quenching indicate that the capacity of the fused vesicles to maintain an electrochemical proton gradient has not been substantially diminished. From the kinetics of 9-aminoacridine quenching an increased K + -permeability seems to be apparent.

A series of investigations on light induced thylakoid membrane conformational changes has been carried out using scattering changes measured either at 90° or 180° (transmittance changes) as criteria for changes in membrane structure upon illumination. These two phenomena were found to react similarly to a range of photosynthetic inhibitors, to changes in the ionic (Mg 2+ , H + ) concentration, and to have similar difference spectra. However, it was found possible to distinguish these two phenomena by the differences in the kinetics of the light induced rise times. This could be shown most clearly using an Aminco DW2 spectrophotometer with the measuring beam deflected through 90° by front face mirrors. The dark decay time of the two scattering changes was similar. These results are discussed in relation to the hypothesis that the light induced narrow angle 90° scattering response represents microconformational membrane changes in response to proton uptake, and the 180° scattering changes represent a mixed response including changes in the stacking of thylakoids.

Yield of streptolysin S (SLS) in streptococcal culture was considerably reduced by procaine, dibucaine, atropine or chlorpromazine at concentrations which scarecely affected production of an extracellular nuclease as well as the bacterial growth. Cerulenin was also inhibitory to SLS formation, but its effect was more pronounced on the nuclease production. By aerobiosis, amount of SLS produced into culture supernatant was increased significantly, whereas yield of the nuclease was rather unaffected.

The haemolytic activity of 5-n-alk(en)ylresorcinols is temperature dependent and correlated to their transition temperatures. The values of the parameters describing the 5-n-alk(en)yl-resorcinol-induced red blood cell lysis indicate strong affinity of the compounds to the membrane and their high lytic capacity. The affinity of the compounds for the membrane decrease with the increasing quantity of the molecules incorporated into the erythrocyte membrane and is much higher for saturated resorcinols than unsaturated ones. The amount of 5-n-alk(en)ylresorcinol molecules bound to the membrane at a hundred percent lysis is about eighty times and eleven times (for alkyl and alkenyl derivatives respectively) higher than at zero percent lysis. Estimated free energy of erythrocyte lysis was similar for alkyl and alkenyl derivatives of resorcinol provided the preparation of the resorcinolic suspensions above their transition temperatures.

The affinity of the sarcoplasmic reticulum transport ATPase for calcium and ATP is not affected by lipid depriviation while vanadate binding is completely abolished. Lipid substitution restores vanadate binding as well as the vanadate induced disappearance of the enzyme’s high affinity calcium and nucleotide binding sites. Nucleotide binding is simultaneously restored with the displacement of vanadate from the enzyme following the occupation of its low affinity calcium binding sites.

Vascular smooth muscle cells from rabbit arteries were grown in tissue culture and stimulated by DC impulses (1 mA, 1V, 10 Hz, 1 ms/imp). Scanning microscopic examination disclosed that in stimulated cultures the cell surface was enlarged by numerous microvilli. This was interpreted as being indicative of an increase in cell activity. Cellular metabolism was character­ized by analyzing the incubation medium for glucose, glutamate/glutamine, and lactate. When compared to unstimulated controls, stimulation caused an increase in the uptake of glucose and glutamine as well as an increased lactate production. The enhancing effect on metabolism was prevented when the “calcium antagonist” verapamil was present (5 × 10 -6 ᴍ). Although the exact mechanism by which DC stimulation influences the cells remains obscure, this finding indicates an important mediating role of Ca 2+ ions.

Juvenile hormone III, i.e. methyl 10,11-epoxy-3,7-dimethyl-2E,6E-dodecadienoate, was used for photoaffinity labelling of JH-binding proteins. Irradiation of haemolymph from Manduca sexta and Locusta migratoria in the presence of racemic [10- 3 H]JH-III results in covalent incorporation of up to 3.2% of the radioactivity into an acetone insoluble protein fraction. Resolution of the proteins by HPLC and by SDS-PAGE confirms the presence of radiolabelled JH-binding proteins. Proteins not involved in JH-binding in insect haemolymph are labelled photochemically with lower yields only. Thus, JH-III is a suitable natural ligand for photoaffinity labelling of high-affinity binding sites. Use of the natural hormone instead of a hormone analog bears the major advantage that the binding with a JH-binding protein will occur at specific sites.

The titer of juvenile hormone III (JH-III) has been determined by the use of combined gas chromatography-mass spectroscopy (GC-MS) in whole body extracts of the larvae, prepupae, pupae and adults of Drosophila hydei. A characteristic JH-III titer curve was established by use of the hormone derivatives. No other juvenile hormone homologs were detected. JH-III shows a broad peak maximum of about 30 pmol/g fresh weight during the last larval instar, whereas only traces of the hormone are detectable at pupariation. Prepupae and pupae exhibit about the same JH-III level. In older pupae and in the pharate adults there was no JH-III detectable but it reappeared soon after emergence. Low values of JH-III are found in young male and female flies. The JH contents rise to distinct peaks in older and reproductive adults, both in male and female animals.

The antifeedant and antimolting effects of azadirachtins A and B, and of a synthetic derivative, 7-acetyl-azadirachtin A were examined. Given through a blood meal, the effective dose (ED 50 ) for the antifeedant effect ranged from 25 to 30 μg/ml of blood for the three compounds. ATP, a phagostimulant, also given orally, reversed the antifeedant action of azadirachtin A. The ED 50 values for molt inhibition were 0.04, 0.015, and 0.45 (μg/ml of blood for azadirachtins A, B, and 7-acetyl-azadirachtin A, respectively. The mechanisms of feeding and molt inhibitions by azadirachtin A B, and its 7-acetyl-azadirachtin A derivative are discussed.

Pheromone-initiated sexual reproduction of Volvox carteri f. nagariensis is started by a “spontaneous” generation of sexual male spheroids at a rate of 10 -4 . As previously suggested, these males are mutants (sex c ) which become independent of pheromone-controlled sex-induction. Unequivocal evidence for a mutative event now comes from the observation that the sex c trait is transmitted through cell lineages during embryogenesis, thus confirming earlier morphological analysis, Mutation semms to be restricted to cell division, The high frequency of mutation points to a special enchacing mechanism for whick the possibility of a genome rearrangement is discussed.

The conductivity of human erythrocyte cells dispersed in various uni-univalent electrolyte solutions (NaCl, KCl, LiCl, CsCl; 0.15 ᴍ) have been measured in the frequency range from 10 KHz to 100 MHz at five temperatures between 5 and 45 °C. The results were analyzed in the light of the theory of conductivity polarization of a suspension of ellipsoidal particles covered with two confocal shells. Differences in the electrical parameters of the membrane between normal and homozygous β-thalassemic cells have been evidentiated.

A detailed analytical and numerical analysis of a simple reaction-diffusion model of the source of non-homogeneities and arrhythmias in an originally homogeneous reaction system is presented. Solution, bifurcation and evolution diagrams are used to describe the behaviour of the model. It is shown that under certain conditions steady and/or oscillatory nonhomogeneous states are the only stable solutions of the model. These phenomena are essentially not dependent on a particular reaction kinetics. A possible relevance to some biological situations is discussed.

The gorgonian Paragorgia arborea, collected in the Crozet Is. waters at a depth of 280 m during the cruise MD.30/BIOMASS of M/S “Marion Dufresne”, is shown, in what constitutes the first organic-chemical study of a Paragorgiidae, to possess three C 20 H 28 O 2 xeniolide diter­penoids, two of which are identical with those from a Corallium sp. of the Hawaii. The third xeniolide, arboxeniolide-1, is new as a naturally occurring compound.

Nineteen flavonoid aglycones have been identified from the external stem and leaf resin of Ericameria laricifolia by thin layer co-chromatography with authentic samples. Kaempferol, quercetin, apigenin, and their methyl ethers have been found, along with luteolin and 6-methoxy luteolin. It is suggested that future flavonoid chemosys-tematic studied of resin-exuding species would best focus on aglycones as opposed to glycosides.

It is generally accepted that oxygen diffuses according to the gradient of its partial pressure from the surface of the plants into the heterotrophic tissues through the inter­cellular spaces. The present experiments show evidence of an additional manifold higher oxygen supply due to a gas transport in leaved as well as leafless trees of Alnus glutinosa (L.) Gaertner. This gas transport is directed from the stems to the roots. It is driven by a thermo-osmotic pressurisation within the air space system of the stems, resulting from temperature gradients up to 3.6 K between the stem and the ambient air following the absorption of light energy by the brownish pigments of the bark. This gas phase phenomena appears to enable the alder-trees to survive and grow in wet soil resulting from a high water table or in waterlogged soil.

Keywords Under adequate experimental conditions calmodulin antagonists like compound 48/80 do not dissociate calcium uptake from the calcium -dependent ATP hydrolysis of skeletal muscle sarcoplasmic reticulum membranes but simultaneously inhibit both processes. Apart from the agent’s pump inhibiting effect, they interact with the caffeine sensitive calcium channel in the sarcoplasmic reticulum causing a rapid transient calcium release.

The principal component of the female sex pheromone of the European pine moth Dendrolimus pini L. (Lasiocampidae) was identified as (Z ,E)-5 ,7-dodecadienal by capillary gas chromatography, mass spectrometry, single receptor analyses, and field trapping tests. Traps initially baited with 1000 μg of (Z,E)-5,7-dodecadienal (>99%ZE) effectively monitored low D. pini populations over 6 weeks without rebaiting. Captures disappeared upon addition of ≧1% of either (E,Z)-5,7-dodecadienal or (Z,E)-5,7-dodecadienyl acetate, the key stimulants for additional receptor cell types located in male antennal hair sensilla.

Phosphatidylserine (PS), phosphatidylinositol (PIN) or phosphatidylglycerol (PGL) incubated with synaptosomal plasma membranes (SPM) of dog brain, stimulated adenylate cyclase. The enzyme activity showed a dramatic increase at around 1.6 μmol PS/mg protein, while use of higher concentrations led to inhibition of the activity with respect to the maximal percentage of stimulation. Moreover, PS stimulated the dopamine-sensitive adenylate cyclase. Solubilization of SPM by the detergent Lubrol-PX did not affect the enzyme activation induced by dopamine. The solubilization, also, showed that the enzyme activity does not change at any PS, PIN or PGL concentration used. These results indicate that acidic phospholipids do not directly act on adenylate cyclase, but indirectly, affecting the membrane fluidity probably. Such modifications of interactions through lipid-protein(s) of adenylate cyclase may have implications to physiological responses to hormones or/and neurotransm itters in the central nervous system.

Antibody against viral gp71 is effective therapeutically for high leukemic AKR mice if injected immediately after birth [1], No corresponding effect could be observed after inoculation later in life when the endogenous virus burden is already high. However, if antibody treatment was supplemented by the injection of pi5(E) antibody, a thera­peutic effect was observed even in older mice first treated at an age of 2 1 / 2 months. Those mice produced antibodies against viral surface proteins and appeared to be able to survive longer than control mice. Thus pi5(E) antibody might be able to overcome retroviral associated immuno­deficiency. This therapy may have implications for the treatment of the apparently retroviral induced aquired immunodeficiency syndrome (AIDS) of man.