Showing papers in "Naturwissenschaften in 1974"

Effects of ionizing radiation on mammalian cells

Abstract: Soon after the discovery of ionizing radiation its beneficial and damaging effects on human health were noticed and scientists became interested in the physical interactions of radiation energy with living material and the resulting biological effects. Since that time environmental and accidental exposure to ionizing radiation has become a threat to the general population. In this article recent progress in the radiobiology of rapidly dividing mammalian cells in culture is discussed. Special emphasis is placed on the lethal, mutagenic and carcinogenic effects of ionizing radiation. These detrimental effects of ionizing radiation result, for the most part, from damage induced in the nuclear deoxyribonucleic acid (DNA). The formation and repair of radiationinduced breakage of one or both strands of the double stranded DNA helix and of damage to the heterocyclic nucleic acid bases are actively being investigated in mammalian cells. While important progress has recently been made, most of the DNA lesions produced in situ in the cell have not been chemically identified. The relation of the DNA damage to the impairment by ionizing radiation of the cellular functions leading to cell death, mutation and malignant transformation remains unknown.

Identification of the Iron-Ligand Vibration of Oxyhemoglobin

Abstract: obse rva t ion t h a t l eadt rea ted h u m i c acids t end to form dist inc t ive aggregates , whereas u n t r e a t e d h u m i c acids do not . The obse rved d i sappea rance of the b road carboxyl ic-ac id shoulder a t 2 700 to 2 300 cm -~ and t he increased ca rboxy la t e abso rp t ion a t 1 400 to t 380 cm -1 revealed t h a t lead fo rms sa l ts w i th acid ca rboxyl groups , t h u s ind ica t ing t h a t lead f ixa t ion b y h u m i c acids involves qu i te d i f ferent t ypes of b inding. A fu r t he r e x p e r i m e n t showed t h a t p H condi t ions s t rong ly inf luence lead f ixa t ion (Table 2), t h u s conf i rming the resu l t s ind ica ted above. This jus t i f ies t he a s s u m p t i o n tha t , a t low pH, g roups of low ac id i ty t ake less pa r t in lead f ixat ion. L ead sa l ts fo rmed unde r these condi t ions are t h u s more polar and more readi ly ionized.

On the precipitation of aragonite on the surface of marine bacteria.

Abstract: The precipitation of Ca carbonates via microbial activity has been demonstrated for terrestrial and marine environments [1 4], yet it was not known whether precipitation takes place inside the cell, on the cell surface, or in the immediate environment of bacteria, and whether it is possible to attribute fossil carbonates to microbial origin. During extended experiments with marine heterotrophic bacteria we have studied the initial phases of crystallization in some detail. Culture control, X-ray analyses, light and scanning electron microscopy and electron-probe analyses have yielded the following results: marine heterotrophic bacteria and fungi will precipitate aragollite and other carbonates (Mg calcite and monohydro calcite) under aerobic and anaerobic, agitated and noll-agitated conditions at pH 6.9 to 8.7 from seawater of different qualities when organic matter is added in concentrations between 0.0t and 0.1%. The following nutrients were tested: Na acetate, Na lactate, asparagine, alanine, peptone, glucose and homlogenized blue-green algae. All these can occur in this range of concentrations in marine sediments. The precipitation of aragonite needles and microcrystalline aragonite was observed on the cell surfaces after 36 h of cultivation (Fig. t). Very soon the bacteria were ensheathed by aragonite needles. The needles grow both, parallel and perpendicular to the cell surface, but prefer the cell as initial crystallization site. The dissolution or mechanical disruption of such aggregates (Fig. I b) after 36 to 90 h of cultivation, yields intact but often deformed and inflated bacterial ceils which recover after t0 to 30 mill by osmoregulation. After 4 to 7 days the carbonate aggregates are much larger (50500 ~zm). When these aggregates are dissolved, they yield only dead ceils and amorphous organic matter. Unless the initial steps of carbonate precipitation are controlled, it is impossible to discriminate between bacterial precipitates (Fig. I), illorganic precipitates [5], or precipitates originating from macroorganisms [6]. The late stages of microbial carbonate precipitat ion--namely those from agitated cultures--yield aggregates identical to those described previously [7]. The so-called \"Weizenkorntyp\" (wheat-grain type) has frequently been observed in beachrock environments and algal laminites of the gulf of Aqaba, always together with bacteria and early phases of aragonite precipitation. The laboratory experiments thus indicate that these aggregates may have a common bacterial origin. I acknowledge the aid of the SEM groups of the Universities of G6ttingen, Bonn and Hamburg, and the assistance of E. Gavish and G. MiJlller in X-ray analyses. Part of the work was supported via Grant Kr 333/6-8 of the DFG.

Testicular involution in short photoperiods inhibited by melatonin.

Abstract: I t ha s been sugges ted t h a t me la ton in is the an t i gonado t roph i c h o r m o n e of t he pineal b o d y [1, 2]. The ac t iv i ty of the enzy m es involved in t he syn thes i s of m e l a t o n i n N a e e t y l t r a n s f e r a s e , and h y d r o x y i n d o l O m e t h y l t r a n s f e r a s e is inhib i ted b y l ight [3, l] which sugges t s t h a t me la ton in m i g h t be the h o r m o n e effective in sho r t -day condi t ions . Such speculat ions are suppor t ed by the f indings t h a t me l a ton in g iven to an ima l s in win te r inh ib i ted t he s t i m u l a t i n g effect of long pho toper iods in th ree m a m m a l i a n species wi th c learcut photoperiodic reac t ions : weasel [4], ferre t [5], and D j u n g a r i a n h a m s t e r [6]. To fur ther t e s t th i s hypo the s i s i t was necessa ry to ob ta in i n fo rma t ion on the effect of me la ton in on an ima l s in s u m m e r . Adu l t males of the D j u n g a r i a n h a m s t e r Phodopus sungorus were used. The e x p e r i m e n t was s t a r t ed on 10 J u n e ; all an ima l s were ini t ia l ly in s u m m e r condit ion, as asce r ta ined b y pa lpa t ion of t he tes tes [6]. Three groups, each of 9 or t0 an imals , were placed in a l ightproof c h a m b e r and exposed to long photoper iods (16 h i l lumina t ion /24 h) ; th ree o the r g roups in a s imi lar c h a m b e r were exposed to shor t pho toper iods (8 h i l lumina t ion / 24 h). H a m s t e r s in group M received an i m p l a n t of m e l a t o n i n in beeswax (mela tonin : beeswax -t : 10, we igh t of to ta l i m p l a n t approx . 34 rag; for deta i ls of m e t h o d see [6]) a t t he beg inn ing of the e x p e r i m e n t and s u b s e q u e n t l y 5 t imes a t week ly in t e rva l s . Group C received i m p l a n t s of beeswax only; g roup U was left un t r ea t ed . In addi t ion, 6 p inea lec tomized (PE) h a m s t e r s were exposed to t he shor t photoper iod. These an ima l s received s h a m implan t s . Af te r 2 m o n t h s all an ima l s were sacrificed and the we ig th of t e s tes and accessory g lands was de te rmined . E x p o s u r e to shor t pho toper iods induced dras t ic i nvo lu t ion of t es tes and accessory g lands (Fig. I), b u t on ly in i n t ac t controls t h a t h a d no t received mela ton in . Con t r a ry to e x p e c t a t i o n , me l a ton in did no t induce s t rong regress ion of t e s tes and accessory g lands in h a m s t e r s exposed to long photoper iods , b u t i n s t ead inhib i ted the effect of shor t photoper iods . In long pho toper iods me la ton in h a d litt le inf luence as compa red w i th t he two control groups. I n t he an ima l s t r ea t ed wi th me l a to n in no difference could be de tec ted be tween t he two l igh t regimes. The effect of me l a ton in t h u s resembled t h a t of p inea lec tomy, which also inhib i ted t he ac t ion of shor t photoper iods , as expec ted f rom earlier repor t s [7]-

Evidence for an innate magnetic compass in garden warblers

Abstract: I t h a s been d e m o n s t r a t e d t h a t var ious m i g r a t o r y bird species use t he m a g n e t i c field for d i rect ion f inding [L 21, b u t so far i t h a s no t been k n o w n w h e t h e r th is o r ien ta t ion m e c h a n i s m will develop in b i rds depr ived of celestial cues. W e examined w h e t h e r t he noc tu rna l ac t iv i ty of garden warblers (Sylvia bori~t), h a n d r a i s e d w i t h o u t seeing the sun or t he s tars , would show direct ional t endenc ies in the no rma l m i g ra t o ry di rect ion of th i s species. The expe r imen t a l b i rds were t a k e n f rom thei r nes ts in sou th west G e r m a n y (4 birds) and s o u t h e r n F in land (2 birds) a t an age of 4 to 5 days , before the i r eyes h a d opened, and ra ised as descr ibed earlier C3-1T h e y were housed in a shaded av ia ry wi th opaque wails t h a t al lowed t he na t u r a l day l igh t to en te r b u t p r even t ed the bi rds from seeing the s u n or the s tars . At the beg inn ing of A u g u s t t h e y were t r ans fe r red to an indoor room and kep t there in ind iv idua l cages unde r a c o n s t a n t dai ly photoperiod of 12 h. In bo t h t he av i a ry and t he indoor room, t he local m a g n e t i c field of ea r th was close to normal . Or ien ta t ion t es t s were pe r fo rmed f rom ear ly A u g u s t unt i l la te November . The bi rds were tes ted irL closed rooms in the local m a g n e t i c field (0.48 Gauss , a N = 360 ~ 64 ~ Incl.) Octagona l recording cages wi th $ radia l perches were used [4]. The freq u e n c y of ac t iva t ion of the va r ious perches served as t he crite r ion for direct ional preferences. All t e s t s wi th more t h a n 20 perch ac t iva t ions per n i gh t were inc luded in t he analysis . For s ta t i s t ica l eva lua t ion the Rayle igh T es t was used ~5]The expe r imen t a i procedure , t he reg is t ra t ion , and the s ta t i s t ica l t r e a t m e n t were as descr ibed in E4]. The expe r imen ta l b i rds showed suff ic ient noc t u rna l ac t iv i ty in 23 t e s t n igh t s ; the re was a s igni f icant (p < 0.0t) direct ional preference towards 2 1 7 ~ SW (Fig. t), which cor responds well to t he m i g r a t o r y d i rec t ion of E u r o p e a n ga rden warblers as k n o w n f rom r ing ing recoveries [6, 7~. The resu l t s show t h a t hand ra i s ed warblers t h a t have never see~ t he s ta rs or t he s u n can develop an or ien ta t ion s y s t e m enabl ing t h e m to es tab l i sh the i r no rma l m i g r a t o r y direction. I t appears t h a t th is non-v i sua l o r i en ta t ion sy s t em, which we know f rom o ther expe r i men t s to be the magne t i c compass [2, g], can m a t u r e w i thou t connec t ion to visual i n fo rma t ion ; i.e., i t does n o t require learn ing processes based on celestial cues. We therefore conclude t h a t t he abi l i ty to es tabl i sh the appropr ia te m i g r a t o r y di rect ion wi th reference to the m a g n e t i c field and the use of t he m a g n e t i c compas s is i nna t e in ga rden warblers .

Dendritic secretion: A way for the neuron to communicate with the vasculature

Abstract: W e are i nves t iga t ing neurop lasmic t r a n s p o r t in t he dendr i tes of m a m m a l i a n m o t o n e u r o n s [t, 2]. W e found t h a t acetylchol ines terase (ACHE) is an excel lent m a r k e r subs t ance for th i s t ype of t r a n s p o r t [3]. I t s ac t iv i ty can be d e m o n s t r a t e d cy tochemical ly a t the e lec t ron microscopic level [4]. The specif ic i ty of t he reac t ion is e s tab l i shed b y u s i ng inhib i tors of nonspecific chol inesferases , e.g. e thopropazine , i so-OMPA, and b y control expe r i men t s wi th t he specific A C h E inhib i tor B W 2 8 4 C 5 1 or t he i r reversible inh ib i to r D F P . The occurrence of diffusion a r t e fac t s du r ing f ixa t ion is exc luded b y the use of c ryos t a t sect ions of unf ixed mater ia l . In addi t ion, A C h E ac t iv i ty is d e m o n s t r a t e d l igh t microscopical ly b y two o ther t e chn iques [5, 6] and i t is found in the s ame vascu la r and neurona l loca t ions as wi th the Lewis and Shu te technique. In nerve cells the enzyme first occurs in the rough endop lasmic r e t i cn lum (r-ER) and is t h e n t r a n s p o r t e d in to the processes of t he neurons . I n t he nuc leus of the facial nerve in ra t s and gu inea pigs, e n z y m e ac t iv i ty in the dendr i tes of the m o t o n e u r o n s can be seen associa ted wi th tubu la r -ves i cu la r s t ruc tu res . These s t ruc tu re s represen t mie ro tubn les as well as c is ternae of t he s m o o t h endop lasmic re t i cu lum. As judged f rom the locat ion of t he reac t ion product , t he enzym e appears b o u n d to t he ex te rna l surface of the dendr i t ic m e m b r a n e , par t icu lar ]y the p o s t s y n a p t i c site. The reac t ion p roduc t can be found f r equen t ly in the synap t i c cleft (Fig. 1 a). U n d e r cer ta in expe r imen ta l condi t ions, e.g. 2 or 3 weeks af ter a x o t o m y of t he facial nerve ill gu inea pigs, e n z y m e ac t iv i ty also appears in the capillaries of t h e facial nuc leus [7]. E lec t ron mic roscopy ha s d e m o n s t r a t e d t h a t t he e n z y m e ac t iv i ty in t he capillaries is located in t he b a s e m e n t m e m branes . There is no A C h E ac t iv i ty in the r E R of the endothel ial cells, ind ica t ing t h a t t hese cells are no t capable of syn thes i z ing ACHE. Thus , t he e n z y m e m u s t or iginate f rom a source o ther t h a n the endothel ia l ceils. In the area u n d e r s t u d y the facial m o t o n e u r o n s are the on ly source of ACHE. Therefore, it m u s t be pos tu l a t ed t h a t the e n z y m e is re leased f rom the dendr i tes by m e a n s of a h i the r to u n k n o w n m e c h a n i s m which we could like to call \" d e n d r i t i c sec re t ion\" . On t h e basis of our e lectron microscopic obse rva t ions i t is ev iden t tha t , following a x o t o m y , A C h E appears ill t h e ext race l lu lar space a n d t h e n arr ives a t the b a s e m e n t m e m b r a n e s of the capillaries. The b a s e m e n t m e m b r a n e s are composed of polyionic g lycoprote ins and mucopolysacchar ides , which are p robab ly able to ca tch charged macromolecu les f loa t ing in the ext race l lu lar space, e.g. ACHE. Once the macromolecu les are t r apped in the b a s e m e n t m e m b rane t h e y can be t a k e n up by microp inocy tos i s in to the endothel ia l cells. We have observed va r ious t ypes of ACHEposi t ive p inocyto t ic vesicles on the endothe l ia l in ter face of the b a s e m e n t m e m b r a n e . All t r ans i t iona l s tages can be seen, f rom b u d s to s ta lked vesicles and p inched-off vesicles. This obse rva t ion indica tes t he capabi l i ty of the endothe l ia l cells to incorpora te mate r ia l p roduced and released by the neurons . The p h e n o m e n o n observed here in an expe r imen t a l s i t ua t i on seems also to occur unde r n o r m a l condi t ions . AChE-pos i t ive capil laries can be seen no rma l ly in cer ta in a reas of t he brain, e.g. in the cerebel lum and t he inferior olive of the r abb i t [8], in t he c ingula te region and in t he media l t h a l a m u s of ra t s [9] and in t he area s u b p o s t r e m a of t he cat [t0]. In s u m m a r y , we h a v e observed a complex t r ans loca t ion of ace ty lchol ines te rase f rom the neurona l pe r ika ryon to the dendri tes . After pas s ing the dendr i t ic m e m b r a n e , t he e n z y m e enters t he extracelIular space and reaches the b a s e m e n t m e m b r a n e s of t he capillaries, f rom where i t can be t a k e n up b y microp inocy tos i s into the endothel ia l cy top la sm. ACh E m a y no t be the on ly subs t ance m o v i n g a long th is p a t h w a y , as it is conceivable t h a t i t m a y also be used by o ther specific subs t ances which could ac t as signals. Thus , i t seems likely t h a t we have d e m o n s t r a t e d a p a t h w a y f rom the nerve cell to the endothel ia l cells t h a t enables the neu ron to c o m m u n i c a t e wi th the vascu la tu re .

Identifizierung und Metabolisierbarkeit von polychlorierten Biphenylen

Abstract: P r g p a r a t i o n wurde der e twa 83 p p m Bor e n t h a l t e n d e Molybd g n d r a h t ( ~ 0,6 ram) bei t 900 ~ t5 m i n gegliiht, d a n n u n t e r fl i issigem St ickstoff gebrochen u n d die Bruchfl / iche im R E M bei 20 kV B e s c h l e u n i g u n g s s p a n n u n g n n t e r s u c h t . Die D r a h t probe war bevo rz ug t in te rkr i s ta l l in gebrochen, n u r vereinzel t t r a t t r anskr i s ta l l ine r Spa l tb ruch auf, An den Korng renzen in der Niihe der Drah tobe r f lgche k o n n t e n Blgsehen yon e twa 1 2 b~m D u r c h m e s s e r beobach t e t werden. Die Bliischengr6Be n i m m t m i t der E n t f e r n u n g yon der Drah tobe r f lgche rasch ab, sie be t rgg t bei e twa 20 btm unge fgh r 5000 K und is t im D r a h t inneren kleiner als die Anf l6sungsgrenzen des Ras t e re l ek t ronen mikroskopes (etwa 200 A). Der Einflul3 so kleiner Porert auf die V e r s e t z u n g s b e w e g u n g bei p las t i scher V e r f o r m u n g und auf den Rekr i s t a l l i s a t ionsvorgang is t sehr au sgep rgg t [t] und dtirfte auch die W i r k u n g fe ins ter fes ter Dispers ionen fiber t ref fen [2]. Dies iiuBert sich im S in te rmolybd i in auch bei sehr kle inen Borgeha l t en in einer s t a r k e n K o r n w a c h s t u m s h e m m n n g , in einer ge r i ch te ten Sekundi i r -Rekr i s ta l l i sa t ion u n d in einer E r h 6 h u n g der Kr iechfes t igke i t des Reinmeta l les . Eine entsp rechende W i r k u n g yon MikroIeg ie rungszusg tzen an Bor is t auch bei W o l f r a m nachgewiesen worden [3] u n d bei ande ren kubisch r a u m z e n t r i e r t e n Metal len wie TantaI , Niob, V a n a d i u m u .a . zu e rwar ten . Bei ande ren Metal len k 6 n n t e n Gasb lgschen bi ldende Dopmi t t e l ~ihnlich wirken, wobei die S tabi l i tg t der Bli ischen u n d ihr T h e r m o d i f f u s i o n s v e r h a l t e n ein Kr i t e r i um fi~r ihre W i r k s a m k e i t sind.

Social units and hermaphroditism in a pomacentrid fish

Abstract: hen der H 6 r b a h n an Mannigfa l t igke i t z u n i m m t , l i nden sich dor t keine ne rv6sen E l e m e n t e mi t der gleichen oder einer ve rbesse r t en Frequenzspez i f i t~ t wieder wie auI der Rezeptor ebene. Als L 6 s u n g des besonderel l Problems , welches ill d e m , ,Feh len\" einer zel l t ra len R e p r e s e n t a t i o n der per ipber aufg e n o m m e n e n F r e q u e n z u n t e r s c h i e d e liegt, wird eine Arbei t s h y p o t h e s e vorgeschlagen. Die V e r m u t u n g , dab die per iphere F r eque l l zun t e r s che i dung bei der L a u b h e u s c h r e c k e auf t y m p a ha ler Resol lanz be ruh t , wird du rch den an der Grille [3] u n d an der en t f e rn t ve rwa l ld ten W a n d e r h e u s c h r e c k e [4] geff ihr ten Nachweis best i i t igt . Der iResonanzmechan i smus wird aber im wesel l t l ichen zur a l lgemeinen Empf i l ld l ichkei t ss te igeru l lg des k le inen u n d dahe r wellig Schallellergie a u f n e h m e n d e n T y m pana lo rgans genu tz t . Zugle ich schr&nkt die schmale Band brei te der R e z e p t o r n e u r o n e n den EinfluB yon St6rungeI1 du rch t h e r m i s c h e s R a u s c h e n ein (vgl. Eb]). Auf den fo lgenden S ta t ionen der H6rbah l l wird die F requenzd i f f e renz ie rung illtegrier t , wogegen die e rh6h te abso lu te In tens i t&tsempf indl ichkei t ausgewer t e t wird.

Induction of pancreas tumours by di-isopropanolnitrosamine

Abstract: Verzweigung; wie fa r o l faktor ische Sensil len t yp i s ch [4, 5, 6], sche in t hier n i ch t vorzul iegen, so dab j e d e m Sens i l lum 20-25 resp. 4 0 5 0 Sinneszel len zuzuo rdnen s ind (Fig. 2c, d). 4. Die St /~bchenhaare s t ehen in Gruppen vorwiegend an den d is ta len t a r sa l en Segmen tg renzen . Ih re F e i n s t r u k t u r is t noch n i ch t gekl/irt. Die d f lnnwand igen H a a r e und die St /~bchenhaare s ind n u t au f den vorderen Segmen t en zu f inden. Re in mechanorezep to r i sche Sensil len w u r d e n auf d e m T as t e r n i ch t fes tgeste l l t ; die be iden Dend r i t en an der Haa rbas i s der B o r s t e n h a a r e bes i tzen aber ausgepr/~gte Tubula rkSrper , wie sie ft~r mechanorezep tor ische Dend r i t en t yp i s ch s ind [7].

Towards three-dimensional "electron microscopy" at atomic resolution.

Abstract: The fact that the electron microscope has exceeded the power of resolution of the light microscope by several orders of magnitude has given an extraordinary stimulus to nearly all branches of the natural sciences. National and international scientific congresses on electron microscopy demonstrate tha t this stimulus still operates today, nearly 40 years after the first working electron microscope was constructed by E. Ruska and B. v. Borries. The theoretical limit of resolution of a conventional electron microscope equipped with magnetic fields of rotational symmet ry as lenses is between 2 and 3 A. A fundamental theorem [t~ shows that this limit cannot be passed, at least with the use of the conventional accelerating voltages between 50 and 100 kV. This limit is not set by diffraction, as in light microscopy. (The limit of resolution due to diffraction would be of the order of 0.02 A.) Complicated magnetic systems containing several components with nonrotational symmet ry have been proposed to give higher resolution I2, 31, but no such system has yet been built because the overall mechanical, electrical, and magnetical stabili ty required is 1 to 2 orders of magnitude greater than what is necessary in a conventional round lens. Such difficulties perhaps explain why the problem of \" imaging a toms\" has hitherto been seen mainly as a problem of instrumentation. Would the development of electron microscopy along the lines of light microscopy toward atomic resolution provide a solution to the problem ? We shall show in this paper that this is not the case.

Implantable bio-electrochemical power sources.

Abstract: Biogalvanic and biofuel cells may prove to be long-lasting electrochemical power sources for electronic devices to be implanted in the human body. Endogenous substances like oxygen and glucose are utilized to generate power in these cells. In vitro both types of ceils produce enough power to drive cardiac pacemakers. The in-vivo performance of biogalvanic cells needs to be improved; tests with biofuel cells in vivo are still in the preliminary stages. The present stage of development of these cells is reviewed.

Tracking of moving objects by the fly Musca domestica

Abstract: Crus tacea s ind eill wicht iges E l e m e n t der Bioz6nose im subte r ranel l Grundwa sse r ( L i m n o p s a m m o n ) . Un te r i hnen h a b e n s ich Synca r ida als wertvol le b iogeographische Indika tore l l erwiesen : Wi r glaubell , dab sie in diesem Milieu berei ts sei t dem Pa laeozo ikum leben. Als s t r eng s teno l imnische Organ i smen mi t ger inger ak t ive r wie pass iver Ausbre i tungs f~h igke i t m u g die PrXsenz dieser mikroskop isch kleinell Birebse auf alien Blont inenten u n d I

Lumineszenzthermochromie, ein vergessenes Phänomen

Abstract: Cuprous halides react with various nitrogen bases to form compounds which are fluorescent at room temperature and change their fluorescence colour reversibly on cooling with liquid nitrogen. The term \"fluorescence thermochromism\" has been proposed for this phenomenon. Very few details about the mechanism have been known, since there seems to be no difference in the crystal structure of samples at low temperatures and at room temperature. Cuprous iodide reacts with pyridine and hexamethylenetetramine to form a mixed fluorescent compound, ~'~3 CuI.(CH2)6N 4. 2 CsHsN, which is not thermochromic, although both nitrogen components can react separately with copper iodide to form thermochromic compounds.

Lead Fixation by Iron Oxides

Abstract: t. Ashby, E. C., Smith, ~ . ]3.: J. Amer. Chem. Soc. 86, 4363 (1964) 2. Guggenberger, L. J., Rundle, R. E.: ibid. 86, 5344 (1964) 3. Stucky, G., Rundle, R. E.: ibid. 85, 1002 (1963) 4. Weiss, E.: Chem. Ber. 98, 2805 (1965) 5Paradies, H. H., G6rbing, H. : Angew. Chem. 81,293 (t 969); Angew. Chem., int. Ed. 8,279 (t969) 6. Wibaut, J. P., Proost, W.: Recueil Trav. Chim. Pays-Bus 59, 97I (1940) 7. Ashby, E. C., Backer,-VV. E.: J. Amer. Chem. Soc. 85, t l g (1963) 8. Paradies, H. H. : Chem. Ber. (im Druck)

The miocene desiccation of the Mediterranean and its climatical and zoogeographical implications

Abstract: That a basin covering millions of square kilometers and lying thousands of meters below sea level should become desiccated seems to be an improbable event. Yet a synthesis of all available data from drill cores and from land geology left us with no other alternative except this improbable event did indeed take place five million years ago, not only once but ten times or more during the million-year interval of the Messinian Stage. A presentation of detailed geological evidence is included in the Initial Reports of the Deep Sea Drilling Projects cruise to the Mediterranean, only a brief summary of our arguments has been given in this article. Meanwhile the implications of the Mediterranean desiccation on paleoclimatology and zoogeography remain still largely unexplored. It is hoped that our colleagues in other disciplines of natural sciences might explore the value of the desiccated-deep-basin model as a working hypothesis to explain some of their own puzzles.

Synthese und Kristallstrukturen von T1FeS 2 und T1FeSe 2

Abstract: Caldera de los Marteles (lat 27 ~ 57' 25\" N, long t 1 ~ 50' 40\" V~r), La Calderil la (lat 27 ~ 57' 40\" N, long 1t ~ 52' 30\" W), and Caldera de B a n d a m a Oat 28 ~ 02' N, long 1 t ~ 46' ~u are th ree p r o m i n e n t cra ters of Recen t age on Gran Canar ia fo rmed by p h r e a t o m a g m a t i c e rup t ions accompan i ed b y subs idence . E leva t ion (crater bo t tom) above sea level, d i ame t e r and p resen t dep th to p re -e rup t ion sur face are, in me te r s : Marteles (t458, 550, 84), Calderil la (1765, 200, 60), B a n d a m a (2t7, 750, t40). All c ra te rs are r i m m e d b y 5-50 m th i ck f low-deposi ted and air-fail pyroclas t ics of acc identa l rock f r a g m e n t s and juveni le s ideromelane , over la in or i n t e rbedded wi th ves icu la ted ash, lapilli, and spa t te r . Depos i t ion of beds d o m i n a t e d b y accidenta l f r a g m e n t s was m a i n l y b y base surge, as ev idenced by the following fea tures : concent r ic d i s t r ibu t ion along cra ter r ims b u t con f inemen t to val leys f a r the r away ; p las te r ing of s t i cky ma te r i a l aga ins t obstacles and val ley walls; poor sor t ing; lowangle c rossbedding; absence of i m p a c t sags b e n e a t h large blocks. Addi t iona l evidence of t he presence of wa te r and /o r s t e a m is p rov ided by the a b u n d a n c e of dense s ideromelane Iapilli, acc re t ionary and a rmored lapilli, ves icu la ted tuf ts , and d i scon t inons bedding. The smal les t crater , Calderilla, has a t h i ck tu f f r ing wi th juveni le exceeding acc identa l f r agmen t s , m a x i m u m block size being less t h a n 50 cm, wi th good sor t ing a n d ex t r eme th i cken ing on t he downwi nd side ( trade wind di rec t ions a s s u m e d cons tan t ) . The ini t ial c ra te r fo rmed a t t h e edge of a smal l p l a t eau where a s t r e a m flowed down the r im. The th i ck tuf f r ing h a d blocked off and d iver ted r u n n i n g surface water , so t h a t a 80 m h i gh spa t te r , b o m b and l ava cone fo rmed di rect ly a f te rwards , 250 m d o w n s t r e a m (SE) f rom the init ial crater , p robab ly above the s ame fissure. Marteles is s i t ua t ed in l ine wi th five o ther e rup t ive centers a long a f i s s u r e o r en-echelon sets of f i s s u r e s t o t a l l i n g 2.5 k m in length . The five o the r e rup t ive centers h a v e emi t t ed vesicu la ted ash, spa t t e r and /o r l ava flows and form low cones, all s i t ua t ed on h igh m o u n t a i n tops or h igh p la teaus . P roduc t s f rom all s ix centers overlap, ind ica t ing n e a r s y n c h r o n o u s ac t iv i ty . Marteles, a deep circular c ra ter r i m m e d b y basesurge deposits , fo rmed r igh t in t he cen te r of a s teep-s ided val ley (Barranco de Guayadeque) . This s t rong ly sugges t s t h a t sur face wa te r ga ined access to a m a g m a t i c h e a t source when a f issure opened in the s t r e a m valley, leading to powerful p h r e a t o m a g m a t i c e rup t ions (blocks are up to 2 m in d iameter) . A dwind l ing wa te r supp l y due to u p s t r e a m blocking b y depos is ts f rom th i s a nd o ther pa r t s of t he act ive f issure caused the fo rma t ion of \" a g g l u t i n a t e Iapill i\", sub rounded , only s l ight ly vesicular lapilIi con ta in ing cores of c o u n t r y rock. Such an i n t i m a t e m i x t u r e of m a g m a wi th c o u n t r y rock is found a t m a n y o ther m a a r s (H.-U. Schmincke , unpubl . ) and is t h o u g h t to be due to v io lent c h u r n i n g in t he m a g m a c h a m b e r w h e n the cra ter is par t ia l ly open, r o u n d i n g being effected du r ing u p w a r d gas t r anspor t . F ina l ac t iv i ty a t Marteles resul ted in ves icu la ted ash and lapilli, sugges t ing comple te b locking of wa te r access. Bandama--studied in reconna i ssance o n l y i s no t inside a deep va l ley and m a y owe i ts f o rma t ion to the con tac t of g r o u n d r a the r t h a n sur face wa t e r wi th m a g m a , a sugges t ion fu r t he r suppor t ed b y t he g rea t dep t h of t he crater . T he v o l u m e of i ts pyroclas t ics is larger t h a n t h a t of t he o ther two craters , and m a x i m u m block size exceeds 2 In.

Energiekonservierung in der photosynthetischen Membran der Chloroplasten

Abstract: Evidence for a sidedness of photosynthetic electron flow in the thyfakoid membrane is evaluated and a zigzag scheme is proposed for photosynthetic electron transport from water to NADP across the membrane. There appear to be two native energyconserving sites in noncyclic photophosphorylation and only one in photoreductions by photosystem II. Artificial energy-conserving sites are proposed to operate in photoreductions by photosystem I and in certain cyclic photophosphorylation systems. A stoichiometry of about 0.6 ATP/2e is assumed per energy-conserving site, i.e.t.33 ATP/2e in noncyclic photophosphorylation.

Endogenous temporal control of migratory restlessness in warblers

Abstract: I t h a s been d e m o n s t r a t e d t h a t var ious m i g r a t o r y bird species use t he m a g n e t i c field for d i rect ion f inding [L 21, b u t so far i t h a s no t been k n o w n w h e t h e r th is o r ien ta t ion m e c h a n i s m will develop in b i rds depr ived of celestial cues. W e examined w h e t h e r t he noc tu rna l ac t iv i ty of garden warblers (Sylvia bori~t), h a n d r a i s e d w i t h o u t seeing the sun or t he s tars , would show direct ional t endenc ies in the no rma l m i g ra t o ry di rect ion of th i s species. The expe r imen t a l b i rds were t a k e n f rom thei r nes ts in sou th west G e r m a n y (4 birds) and s o u t h e r n F in land (2 birds) a t an age of 4 to 5 days , before the i r eyes h a d opened, and ra ised as descr ibed earlier C3-1T h e y were housed in a shaded av ia ry wi th opaque wails t h a t al lowed t he na t u r a l day l igh t to en te r b u t p r even t ed the bi rds from seeing the s u n or the s tars . At the beg inn ing of A u g u s t t h e y were t r ans fe r red to an indoor room and kep t there in ind iv idua l cages unde r a c o n s t a n t dai ly photoperiod of 12 h. In bo t h t he av i a ry and t he indoor room, t he local m a g n e t i c field of ea r th was close to normal . Or ien ta t ion t es t s were pe r fo rmed f rom ear ly A u g u s t unt i l la te November . The bi rds were tes ted irL closed rooms in the local m a g n e t i c field (0.48 Gauss , a N = 360 ~ 64 ~ Incl.) Octagona l recording cages wi th $ radia l perches were used [4]. The freq u e n c y of ac t iva t ion of the va r ious perches served as t he crite r ion for direct ional preferences. All t e s t s wi th more t h a n 20 perch ac t iva t ions per n i gh t were inc luded in t he analysis . For s ta t i s t ica l eva lua t ion the Rayle igh T es t was used ~5]The expe r imen t a i procedure , t he reg is t ra t ion , and the s ta t i s t ica l t r e a t m e n t were as descr ibed in E4]. The expe r imen ta l b i rds showed suff ic ient noc t u rna l ac t iv i ty in 23 t e s t n igh t s ; the re was a s igni f icant (p < 0.0t) direct ional preference towards 2 1 7 ~ SW (Fig. t), which cor responds well to t he m i g r a t o r y d i rec t ion of E u r o p e a n ga rden warblers as k n o w n f rom r ing ing recoveries [6, 7~. The resu l t s show t h a t hand ra i s ed warblers t h a t have never see~ t he s ta rs or t he s u n can develop an or ien ta t ion s y s t e m enabl ing t h e m to es tab l i sh the i r no rma l m i g r a t o r y direction. I t appears t h a t th is non-v i sua l o r i en ta t ion sy s t em, which we know f rom o ther expe r i men t s to be the magne t i c compass [2, g], can m a t u r e w i thou t connec t ion to visual i n fo rma t ion ; i.e., i t does n o t require learn ing processes based on celestial cues. We therefore conclude t h a t t he abi l i ty to es tabl i sh the appropr ia te m i g r a t o r y di rect ion wi th reference to the m a g n e t i c field and the use of t he m a g n e t i c compas s is i nna t e in ga rden warblers .

Zur elektronenmikroskopisch dreidimensionalen Rekonstruktion eines Objektes

Abstract: u einiger Zeit wurde die Rekonstruktion der Struktur eines dre.idimensionalen Objektes aus einer Anzahl yon gegeneinander verschwenkten elektronenmikroskopischen Aufnahmen vorgeschlagen [ t --3] . Die Fouriertransformierten-Theorie der Rekonstruktion wurde in [4] entwickelt. Eine im Prinzip v611ig analoge Ableitung enth~ilt auch [5]. Inzwischen hat es sich herausgestellt, dal3 das Problem der dreidimensionalen Rekonstruktion aus Projektionen schon vor den elektronenmikroskopischen Arbeiten ftir die Radiologie (Bestimmung des Modells eines menschlichen KSrpers aus R6ntgendurchstrahlungen) und die Radioastronomie bearbeitet worden war. Auf die entsprechenden mathematischen Arbeiten die meist die unmittelbare Rekonstruktion im Ortsraum zum Ziele hatten kann in diesem Zusammenhang nicht eingegangen werden.

Effect of lead ions on chlorophyll synthesis.

Abstract: Seeds of Avena sativa were grown in the dark in wet vermiculite at 22/sup 0/C. When the seedlings were 16 days old, the primary leaf was cut into pieces. These leaf pieces were put 25-ml Erlenmeyer flasks in 10 ml glycylglycine with and without PbCl/sub 2/, and preincubated in the dark for 1 h. The flasks were held for 72 h at 21/sup 0/C in a water bath, illuminated at 7000 lux, and shaken 40 times a minute. Chlorophyll was extracted and the content of chlorophyll a and chlorophyll b determined. Synthesis of both types of chlorophyll was reduced in proportion to the increasing amounts of lead ions. Even concentrations as low as 50 ..mu..M PbCl/sub 2/ had a statistically significant effect. At lower concentrations (0-500 ..mu..M) synthesis of chlorophyll b was inhibited to a greater extent than that of chlorophyll a; at higher concentration the chlorophyll a and chlorophyll b were about the same. 7 references, 1 figure.

Radiography with protons

Abstract: The technique of X-radiography is of very great practical importance in medicine and industry, neutron radiography is becoming an accepted tool for solving special problems but proton radiography is almost unknown. A major reason why the latter has lagged behind is that as far as applications are concerned a proton beam is rather an expensive luxury. However there are certain properties of proton radiography which give it advantages over the established techniques and the present paper will t ry to show what these advantages are and how they arise from the physical processes of the interaction of protons with matter. First it should be mentioned that certain liberties will be taken here with the definition of 'proton radiography' . Firstly the discussion will not be confined solely to protons but will include other ions such as alpha particles where appropriate. Although the term ' radiography ' implies the production of a visual image modern practice allows that the image may also consist of a matrix of numbers obtained by electronic measurements. Finally it should be made clear that there are several types of proton radiography and the reason for this will be seen by contrasting the behaviour of beams of X-rays and protons passing through matter. Fig. I a shows the familiar way in which the intensity of a parallel beam of X-rays falls exponentially as it passes through a solid material. The case illustrated is of t35-keV X-rays in iron. The graph represents the average behaviour of a beam of X-rays in which each individual X-ray passes through the material without loss of energy or change of direction until it suffers a single atomic interaction which either absorbs it or scatters it away from its original direction with reduced energy. The general rule for interaction of the X-rays is that the probability increases greatly with the atomic number of the material and is greater for lowenergy X-rays than for high-energy ones. In an Xradiograph the variations in internal structure of the specimen lead to intensity variations in the transmitted X-rays and in the darkness of photographic image. This simple description may be related to many of the advantages and disadvantages of X-radiographs. Because of its reliance on an exponential absorption curve normal X-radiography is seldom sensitive [t] to changes in specimen thickness less than 1%, although production of the image by xerography E2] instead of on film can give an improvement on that figure. The fact that X-rays basically travel in straight lines except when they are scattered is a vital property in giving images with good definition and also makes it possible to perform micro-radiography with a few ~m resolution [3] by use of a point X-ray source. The X-rays which are scattered in the specimen produce a background which worsens the contrast of the radiograph. The strong dependence of X-ray absorption on atomic number (Z) is usually an important source of contrast although it can sometimes have an adverse effect, particularly when the requirement is to observe low Z features in the presence of higher Z materials. Although a beam of protons passing through a specimen suffers attenuation in much the same way as do X-rays, except that in this case the scattering mechanism is nuclear, more important for the purpose of radiography are the multiple interactions with the atomic electrons which remove energy although they do not seriously deflect the protons. In Fig. I b we see how an individual proton entering iron at t 00 MeV loses energy at an increasing rate over its range of 14 mm. Fig. t c shows how the proton energy loss varies with distance. Because of the statistical nature of the energy-loss process not all protons in the beam have exactly the same range and Fig. t a shows the spread in range with most of the protons travelling between t3.5 and 14.5 mm in iron. The distribution of ranges is roughly a Gaussian with in this case a maximum at t4 mm and FWHM of about 0.4 mm [41. Fig. t a also shows that the gradual loss of intensity due to nuclear scattering removes about t0% of the protons from a t 00-MeV beam and of course this effect