Changes since the turn of the century in the fish fauna and the fisheries of the Oslofjord

Summary 1. The material for this study is drawn from two sources, (a) investigations of the fish fauna in the inner Oslofjord between 1897 and 1967, (b) fish landing statistics available since 1872 at the Oslo fish market.2. The investigations of the fish fauna reveal that 4 species of fish — 2 sharks and 2 arctic bullheads — have disappeared from the deep waters of the Oslofjord where they were known to exist in 1897. We assume that unfavourable conditions, great changes in temperature or lack of oxygen in the stagnant deep water to which these species belonged have been injurious to their propagation and survival.3. The annual fluctuations in the landed quantities of fish are great, but nevertheless there exists a marked decreasing trend since about 1930; total landings in recent years are less than 1/10 of what they were 30 or 40 years ago.4. The fluctuations in the landings of cod, herring and mackerel are studied in some detail. Three periods (of 20 to 22 years' duration) from 1872 to 1932 show increasing average landings of cod: 44, 57, and 74 tons respectively; in the period 1933 to 1955 landings decreased to an average of 16 tons per year. The effect of fluctuating year classes is discussed.5. The landings of herring and mackerel were very good between 1911 and 1919 or 1920 with a maximum of 1500 tons of herring and 800 tons of mackerel. In the following years there was a trend of decrease with a few years of moderately good landings. Mature mackerels are immigrating into the fjord for feeding and spawning, while mature herrings, to a major extent, are supposed to belong to a local stock. The highest landings of both species are due to extremely great catches of young fish, and the success of the fishery in any one year, therefore, dependent of a successful spawning and hatching one ort two years before.6. In conclusion, the attention is drawn to the fact that there are reasons to believe that the profuse growth of bacteria in the polluted waters seems to be injurious to the hatching of fish eggs and to the survival of fish larvae (Dannevig 1945,Oppenheimer 1955).

---

Veränderungen der Fischfauna und der Fischerei des Oslofjords seit der Jahrhundertwende

Kurzfassung Das Material zu dieser Untersuchung stammt aus zwei Quellen: (a) vier Untersuchungen über die Fischfauna des Oslofjords im Zeitraum zwischen 1897 und 1967, und (b) Statistiken für den Zeitraum von 1872 bis 1964 über die Fischmengen, die im inneren Oslofjord gefangen und an die Fischhalle in Oslo geliefert worden sind. Ein Vergleich der Resultate mit den vier Untersuchungen über die Fischfauna zeigt, daß vier Arten von Tiefwasserfischen aus dem inneren Oslofjord völlig verschwunden sind, nämlichEtmopterus spinax, Somniosus microcephalus, Artediellus uncinatus undIcelus bicornis, die beiden zuletzt genannten wahrscheinlich schon vor 1930. Eine Anzahl anderer Arten, die früher häufig waren, sind jetzt selten. Statistische Erhebungen über die im Oslofjord gefangenen Fische lassen erkennen, daß die Erträge seit den zwanziger und dreißiger Jahren stark zurückgegangen sind. Gleichzeitig hat die Zahl der Fischer abgenommen. Es wird die Schlußfolgerung gezogen, daß die Veränderungen des Oslofjords sich besonders in den letzten 30 Jahren für mehrere Fischarten als schädigend erwiesen haben. Diese Auffassung wird unterstützt durch die Untersuchungen vonDannevig (1945) undOppenheimer (1955), die gezeigt haben, daß die reiche Bakterienflora des Oslofjords für die Entwicklung der pelagischen Fischeier schädlich ist.

     

On the Origin and the Signal-Shaping Mechanism of the Fast Photosignal in the Vertebrate Retina

Fast photosignals (FPS) with R₁ and R₂ components were measured in retinas of cattle, rat, and frog within a temperature range of 0° to 60°C. Except for temperatures near 0°C the signal rise of the R₁ component was determined by the duration of the exciting flash. The kinetics of the R₂ component and the meta transition of rhodopsin in the cattle and rat retina were compared. For the analysis of the FPS it is presupposed that the signal is produced by light-induced charges on the outer segment envelope membrane that spread onto the whole plasma membrane of the photoreceptor cell. To a good approximation, this mechanism can be described by a model circuit with two distinct capacitors. In this model, the charging capacitance of the pigmented outer segment envelope membrane and the capacitance of the receptor's nonpigmented plasma membrane are connected via the extra- and intracellular electrolyte resistances. The active charging is explained by two independent processes, both with exponential rise (R₁ and R₂), that are due to charge displacements within the pigmented envelope membrane. The time constant τ₂ of the R₂ membrane charging process shows a strong temperature dependence that of the charge redistribution, τ_r, a weak one. In frog and cattle retinas the active charging is much slower within a large temperature range than the passive charge redistribution. From the two-capacitor model it follows for τ_r « τ₂ that the rise of the R₂ component is determined by τ_r, whereas the decay is given by τ₂. For the rat retina, however, τ₂ approaches τ_r at physiological temperatures and becomes <τ_r above 45°C. In this temperature range where τ₂ ≈ τ_r, both processes affect rise and decay of the photosignal. The absolute values of τ_r are in good accordance with the known electric parameters of the photoreceptors. At least in the cattle retina, the time constant τ₂ is identical with that of the slow component of the meta II formation. The strong temperature dependence of the meta transition time gives rise to the marked decrease of the R₂ amplitude with falling temperature. As the R₁ rise could not be fully time resolved the signal analysis does not yield the time constant τ₁ of the R₁ generating process. It could be established, however, within the whole temperature range that the decay of the R₁ component is determined by τ_r. Using an extended model that allows for membrane leakage, we show that in normal ringer solution the membrane time constant does not influence the signal time-course and amplitude.     

Primary production of the periphyton in the littoral of the Danube

Summary The gross primary production of periphyton, grown on artificial substrata in the littoral of the Danube, was measured by the light and dark bottle method from April 1970 to March 1971. The periphyton used for the measurements was sampled from various depths, in order to cover the production of the whole littoral. In connection with this, the littoral area was divided into four zones limited by the heights 600 to 200 cm, according to the local water level gauge. The highest localized zone A (500–600 cm) was inundated only at maximum water levels for rather short period of time, the deepest zone D (200–300 cm) was permanently flooded.The zone A showed an average periphyton primary production of 22.5, the zone B of 54.8, the zone C of 28.9 and the zone D of 9.1 mg O₂/dm²/day. When recalculated to periods when the individual zones were inundated, the annual production was as follows: in zone A: 0.94, zone B: 9.20, zone C: 7.29 and zone D: 3.06g O₂/dm². The highest primary production was always found in the zone just below the water level. Exceptions occurred only when this zone was inundated for a short time as a result of a temporary rise of the water level and the periphyton was insufficiently developed.In order to compare the values of primary production of periphyton obtained from shallower rivers, where the whole bottom is well illuminated, or from rivers that do not exhibit such frequent and extensive level oscillations as the Danube, average value calculated from results obtained from the zone closest to the water level at the time of measurements, were always used. These results represent a special zone following the water level changes which is called surface zone. Primary periphytic production in the surface zone was 43.8 mg O₂/dm²/day. For the annual period it corresponds to the value of 14.74 g O₂/dm². Efficiently of gross photosynthesis in this zone was on the average 1.72%.The height of the water level and the water temperature were higly correlated with gross periphytic production. Close relationships between chlorophyll a concent, biomass and gross primary production of periphyton were found.

---

Zusammenfassung Die Bruttoprimärproduktion des auf künstlichem Substrat im litoralen Bereich der Donau wachsenden Periphytons, wurde vom April 1970 bis zum März 1971, mit Hilfe der Hell-Dunkelflaschenmethode, gemessen. Das für die Messung herangezogene Periphyton wurde aus verschiedenen Tiefenzonen entnommen, um die Produktion der gesamten Uferzone festzuhalten. Im Zusammenhang damit wurde der litorale Bereich der Donau in 4 Zonen gegliedert, welche ihre Grenzen bei einem Pegelstand von 600–200 cm des Ortspegels hatten. Die höchste Zone A (500–600 cm) wurde nur bei den höchsten Wasserstanden und nur für kurze Zeit vom Wasser überflutet, die tiefste Zone D (200–300 cm) war dauernd unter Wasser.In der Zone A war die durchschnittliche Produktion des Periphytons 22,5 mg O₂/dm²/Tag, in Zone B 54,8 mg, in Zone C 28,9 mg und in Zone D 9.1 mg. Nach Berechnung für die Zeit, in der die einzelnen Zonen vom Wasser bedeckt waren war folgende Produktion in den einzelnen Zonen festzustellen: in Zone A 0,94 g O₂/dm², in Zone B 9,20 g, in Zone C 7,29 g und in Zone D 3,06 g. Die höchste Periphytonproduktion wurde jeweils in der Zone festgestellt, welche dem Wasserspiegel am nächsten war. Eine Ausnahme bildeten nur jene Fälle, in denen these Zone nach vorübergehender Erhöhung des Wasserspiegels erst kurze Zeit vom Wasser bedeckt war und das Periphyton ungenügend entwickelt war.Zum Vergleich mit den Werten der Primärproduktion des Aufwuchses aus seichteren Gewässern mit gut belichteter Sohle, oder aus Flüssen welche nicht so häufige und weitreichende Spiegelschwankungen aufweisen wie die Donau, wird in der vorgelegten Arbeit der Durchschnittswert aus den Ergebnissen der Zone verwendet, welche zur Zeit der Messungen dem Wasserspiegel am nächsten war. Diese Ergebnisse repräsentieren eine besondere Zone, welche den Schwankungen des Wasserspiegels folgt und von den Autoren durch den Begriff Oberflachenzone bezeichnet wird. Die Primärproduktion des Periphytons in dieser Oberflächenzone war 43,8 mg O₂/dm²/Tag. Dem entspricht im Jahresverlauf ein Wert von 14,74 g O₂/dm². Die Ausnützung der Sonnenenergie war in dieser Zone im Durchschnitt 1,72%.Von den Umweltfaktoren zeigt die Höhe des Wasserspiegels und die Wassertemperatur den engsten Zusammenhang mit der Höhe der Bruttoprimärproduktion des Periphytons. In kürzeren Zeitabschnitten, in denen es zu keinen raschen ausgeprägten Schwankungen des Wasserspiegels des Flusses kommt, wurde eine enge Abhängigkeit zwischen den Werten der Primärproduktion und dem a-Chlorophylgehalt und auch der Biomasse festgestellt.

     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

---

Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Comparison of the archaeal community in the fermentative compartment and faeces of the cow and the rabbit

The archaeal community in the fermentative compartment and faeces of the cow and the rabbit were compared by analysis capillary electrophoresis single-stranded conformation polymorphism (CE-SSCP) profiles of 16S rRNA genes. Ruminal and faecal contents were sampled in five cows for three weeks. Hard and soft faeces were collected in 14 rabbits for three consecutive weeks and cæcal contents were sampled in the third week. The archaeal community differed according to the host species (ANOSIM-R = 0.53 and 0.72 respectively for the comparison of the fermentative compartments and faeces; P < 0.001) and to the location within the digestive tract of both species (ANOSIM-R = 0.37, 0.52 respectively for the cow and the rabbit; P < 0.001). In both species, the archaeal community of the digestive tract was stable over weeks and varied very little between individual animals. The structure (NS) and the richness index (9.9 ± 2.7, 10.1 ± 3.1 respectively, NS) of the archaeal community were similar for the cæcal content and the soft faeces which permitted to use the latter as a representative indicator.     

Studies on the the Isoleucine Fermentation

Accumulation of L-isoleucine and L-valine was studied on 14 genera, 47 species and 110 strains of aerobic bacteria using bacterial type cultures. A large amount of L-isoleucine and a small amount of L-valine accumulated when 1% of DL-α-aminobutyric acid was added to the culture medium. As a rule, facultative aerobes such as Aerobacter, Erwinia, Serratia and Bacillus showed good accumulation. In the absence of α-aminobutyric acid, powerful L-isoleucine accumulators produced a large amount of L-valine, although the accumulation of L- isoleucine was scarcely observed under that condition. In the presence of α-aminobutyric acid, the accumulation of L-valine was generally suppressed, but in several strains, on the contrary, the accumulation increased as well as that of L-isoleucine. When DL-threonine was used instead of α-aminobutyric acid, the amount of L-isoleucine accumulated was not as high as that with α-aminobutyric acid in almost all strains except Serratia marcescens. It was concluded that a distinct relationship between bacterial genera or species and accumulation of L-isoleucine did not exist, that is, powerful accumulators were limited to special strains, and that the addition of α-aminobutyric acid was necessary for the accumulation of a large amount of L-isoleucine.     

From the heart of the world

From the Heart of the World—The Elder Brothers’ Warning. Director: Alan Ereira; camera: Bill Broomfield; editor: Horacio Queiro; sound: John Wills. 1990, color, 87minutes VHS‐NTSC, VHS‐PAL. English narration and subtitles. Distributed by BBC Enterprises, 80 Wood Lane, London W12 OTT; or Mystic Fire Video, 225 Lafayette Street, Suite 1206, New York 10012; sale only, £12 or $29.95 + $4.00 postage. Ereira, Alan, The Heart of the World. London: Jonathan Cape, 1990, bibliography, index, 288 pp., £15.99.     

BAYESian Approach to the Prediction of the Restricted Range in the Censored Samples from the Exponential Population

k independent samples 0, 1, 2,…,k – 1 (or stages 0, 1,…. k – 1) are available from the exponential population. Each of k – 1 samples, except the sample 0 are censored both above and below. Restricted range is defined as the difference between largest and the smallest among the available observations. Prediction of this restricted range at stage k (in the future sample k) on the basis of the restricted ranges at earlier 1, 2,…k – 1 stages is attempted by obtaining the predictive distribution of this range at stage k. Probability that the variance at stage k is smaller than that at stage k – 1, is evaluated along with the probability integral. An illustrative example is given with simulated samples.     

Principal component analysis of the relationship between the d-amino acid concentrations and the taste of the sake

We performed sensory evaluations on 141 bottles of sake and analyzed the relationship between the d-amino acid concentrations, and the taste of the sake using principal component analysis, which yielded seven principal components (PC1–7) that explained 100 % of the total variance in the data. PC1, which explains 33.6 % of the total variance, correlates most positively with strong taste and most negatively with balanced tastes. PC2, which explains 54.4 % of the total variance, correlates most positively with a sweet taste and most negatively with bitter and sour tastes. Sakes brewed with “Kimoto yeast starter” and “Yamahaimoto” had high scores for PC1 and PC2, and had strong taste in comparison with sakes brewed with “Sokujo-moto”. When present at concentrations below 50 μM, d-Ala did not affect the PC1 score, but all the sakes showed a high PC1 score, when the d-Ala was above 100 μM. Similar observations were found for the d-Asp and d-Glu concentrations with regard to PC1, and the threshold concentrations of d-Asp and d-Glu that affected the taste were 33.8 and 33.3 μM, respectively. Certain bacteria present in sake, especially lactic acid bacteria, produce d-Ala, d-Asp and d-Glu during storage, and these d-amino acids increased the PC1 score and produced a strong taste (Nojun). When d- and l-Ala were added to the sakes, the value for the umami taste in the sensory evaluation increased, with the effect of d-Ala being much stronger than that of l-Ala. The addition of 50–5,000 μM dl-Ala did not effect on the aroma of the sakes at all.     

Characterization of the composition of the aqueous humor and the vitreous body of the eye of the frog Rana temporaria L

This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations. To determine collagen, a spectral-fluorescent probe, cyanine dye, was used. The presence of collagen in AH of the frog was found at the first time. The total content of electron donors (ascorbic and uric acids, tryptophan, and tyrosine) in VB and HA was roughly estimated at ~ 1.5 × 10^− 4 mol/L. Both VB and AH absorb light in similar UV regions. The total protein and albumin contents in AH were found to be somewhat higher than those in VB. The uric acid content was at an equally low level in both intraocular media. It is supposed that the similarity of VB and AH compositions shown in this work is due to some exchange between VB and AH contents in the course of accommodation. The role of intraocular fluids in physiological functions of the eye and in protecting the retina against UV light is discussed.     

On the theory of the cardiovascular system

Most theoretical studies of the circulation have focussed on the transmission line properties of arteries. Only a small number of papers have dealt with the circulation as a closed (lumped) system with two pumps connected by the lesser and greater circulation (Beneken, inCirculatory Analog Computers, No. Holland Publ. Co., Amsterdam, 1963; Defares,et al., inCirculatory Analog Computers, No. Holland Publ. Co., Amsterdam, 1963; Grodins,Quart. Rev. of Biology,34, 93, 1959; Guyton,Cardiac Output and its Regulation, Saunders Publ. Co., New York, 1963). F. W. Cope's recent studies in this journal (Bull. Math. Biophysics,22, 19, 1960;23, 337, 1961;24, 137, 1962) deal with essentially the same questions, although here the circuit is not “closed”. We have attempted to extend the analysis of the areflex (closed) circulation. The complete study is reported elsewhere (Defares,et al., Acta Physiol, et Parmac. Neerl., 1963).     

The water characteristics of the Nile in the Sudan with a note on the effect of Eichhornia crassipes on the hydrobiology of the Nile

Summary The study of both the physical and chemical water characteristics of the Nile and its tributaries in the Sudan (south of Khartoum) was carried out. The main changes along the White Nile are due to tributary contribution especially that of the riverain swamps and River Sobat. The Gazal has no effect due to its negligible contribution to the White Nile. The influence of the Zeraf, although showing marked characteristics, is restricted to 50–80 km north its mouth. This is due to its low discharge and it is being diluted with the Sobat water.The study of Bahr el Gazal showed a significant longitudinal succession of this tributary where the water characteristics of its upper reaches differ considerably from those at Lake No. At the Gazal mouth a decrease in the dissolved phosphates, silicon, iron and chlorides takes place.The water of Bahr el Jebel, as it passes through the Zeraf, becomes enriched with nutrient salts which account for the dense plankton population of this tributary. As the water passes through the swamps at the sudd region depletion of its oxygen and sulphate content takes place. The characteristics of the water at the swamps affect the animal life and may be important factors in the distribution of animals living in these waters.The influence of Jebel Aulia dam on the water characteristics was studied and results show that significant modifications take place during the seasonal storage of water.The effect of the water hyacinth (Eichhornia crassipes Sol ms.) on the hydrobiology of the Nile was pointed out. The marked decrease of the nitrate nitrogen at Jebel Aulia basin may be partly attributed to its uptake by this plant; especially the reservoir provides ideal conditions for the spread of Eichhornia. The stunted growth of the water hyacinth was recorded at the upper reaches of Bahr el Gazal. This could not be explained due to the low salt content or low pH of the Gazal as Eichhornia is widely spread and shows maximum growth at the Sobat which has more or less the same salt content, pH, oxygen content and alkalinity.

---

Résumé Une étude des caractéristiques physiques et chimiques de l'eau du Nil et ses tributaires au Sudan (Sud de Khartoum) a été faite. Les changements principaux au long du Nil Blanc sont dues à la contribution des tributaires spécialement celle des marais et du fleuve Sobat. Le Gazal n'a pas d'effet étant donné sa contribution négligeable au Nil Blanc. Le Zaraf, malgre qu'il montre des caractéristiques marqués, a un effet limité à 50–80 kms au nord de son embouchure. Ceci est du à son faible écoulement et à son étendue avec l'eau du Sobat.L'étude de l'eau du Bahr el Gazal a montré une succession longidutinale de ses tributaires où les caractéristiques de l'eau de ses hautes ressources diffèrent de celle du lac No. A l'embouchure du Gazal se produit une réduction des phosphates diluées, silice, fer et chlorides. L'eau du Bahr el Jebel étant donné qu'elle passe dans le Zeraf enrich de sels nutritif qui alimentent le plankton dans ce tributaire. Quand l'eau passe dans les marais du Sud une dépletion de son contenu en oxygen et sulphates se présente. Les caractéristiques de l'eau des marais affectent la vie de l'animal et peuvent être d'importants facteurs dans la distribution des animaux qui vivent dans ces eaux.L'influence du Barrage de Jebel Aulia sur les caractéristiques a été étudiée et les résultats montrent des modifications signifiantes qui ont lieu durant l'emmagasinage de la saison.L'effet de l'Eichhornia crassipes Solms sur l'hydrobiologie du Nil a été remarqué. La diminution marquée du nitrogen au bassin de Jebel Aulia peut être attribuée à son absorbtion par cette plante surtout que le resérvoir fournit des conditions idéales pour l'étendue d'Eichhornia.La lente croissance de cette dernière plante a été remarquée aux hautes embouchures de Bahr el Gazal. Ceci ne peut pas être expliqué étant donnée la faible quantité de sel et au bas pH de l'eau de Gazal. Au Sobat où l'eau contient plus ou moins le même sel, pH, oxygen et alcalinité, l'Eichhorina est largement développé et s'accroit rapidement.

     

Dependence of the Composition of the Avermectin Complex of Streptomyces avermitilis on the Glucose Content in the Medium

The effects of the glucose concentration in the medium and O-methyl-L-threonine resistance on the ratio of components of the avermectin complex produced by Streptomyces avermitilishave been studied. Glucose deficiency increases the ratio of components A and ain the complex, while decreasing that of components 1. A mutation that renders the microorganisms resistant to O-methyl-L-threonine (an analogue of isoleucine) increases the ratio of components a in the complex, while decreasing that of components 1. The distribution of aand b in fractions 1and 2 remains constant: the values of the ratio a/b in the fractions amount, respectively, to 1 : 1 and 2 : 1. The relation of the variations in the composition of the avermectin complex to changes in the carbohydrate metabolism of the producer stain, underlain by availability of the source of carbon, is discussed.     

Influence of the stimulation of the dorsal hippocampus on the dorsal root potentials of the spinal cord in the cat

Rhythmic stimulation of the dorsal hippocampus causes a long-lasting (2–6 sec) depression of both the fast and the electrotonic dorsal root potentials. The depression depends on the intensity of the stimulation of the hippocampus and on the time interval between the stimulation of the hippocampus and the nerve. The sortest time interval producing the depression was within 15–20 msec. The action of afferent impulsation is depressed during both the ipsilateral and contralateral stimulation of the hippocampus. The stimulation of the fornix also exerts a depressing influence on the dorsal root potentials; however, it is not so prolonged as the stimulation of the hippocampus (500–600 msec).A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 1, No. 2, pp. 186–193, September–October, 1969.     

Role of the immune-response region of the B complex in the control of the graft-vs-host reaction in chickens

The relative importance of the B and IR regions of the chicken B complex were compared as to their role in the graft-versus-host (GVH) reaction. Spleen enlargement (splenomegaly) on 19-day-old embryos, inoculated 5 days earlier with immune competent leukocytes, served as the test for the GVH reaction. The B blood group locus was the marker of the B region, and the Ir-GAT gene was the marker of the immune response (Ir) region of the B complex, the major histocompatibility system (MHS) of chickens. The test stocks consisted of B¹B¹ GAT-Low (1-Low) and B¹⁹B¹⁹ Gat-High (19-High) birds of our S1 Leghorn line plus the recombinant genotypes B¹B¹ Gat-High (1-High) and B¹⁹B¹⁹ GAT-low (19-Low). A dosage of 0.1 ml of donor white blood cells was injected into each of 191 recipient embryos on day 14, and the spleens were removed and weighed on day 19. Of 16 combinations of (donor blood)-(host embryos), arranged with respect to the four genotypes listed above, four were compatible, e. g., (1-Low)-(1-Low). There were four incompatible combinations at the B locus, four at the GAT locus, and four at both the B and GAT loci. All 16 combinations were replicated. Results were expressed as a splenomegaly index (SI), that is, the ratio of incompatible to compatible spleen weights corrected for differences in embryo weight. If (SI-1) is greater than 0, the GVH reaction is considered positive within sampling errors. The mean (SI-1) indexes obtained were: incompatible at GAT-0.5±0.07; incompatible at B-1.34±0.10. Thus, both GAT and B contributed to the GVH reaction, but the B region was much stronger than the IR region. The results were strongly asymmetrical: maximal stimulation occurred when the host embryo was B¹⁹B¹⁹ GAT-high and donor leukocytes were B¹B¹ GAT-Low. The parental donor-host paired combinations gave stronger GVH reactions than did the recombinant pairs. Effects of incompatibilities at the two regions proved additive when compared with two-locus differences of parental genotypes. In general, the results proved that the IR region, as specifically defined by recombinants obtained in our S1 line of Leghorns, plays a significant, but minor, role in the GVH reaction compared with the region of the B complex identified with the B blood-group locus.     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Specificity of the chlorophyll-to-protein binding in the chlorophyll-protein complexes of the thylakoid

We tried to establish whether the chlorophyll-protein complexes of the thylakoid, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, originate from real entities existing in vivo, or are mere artifacts of the sodium dodecyl sulfate solubilization procedure. Making use of the finding that etiolated leaves exposed to periodic light form selectively the chlorophyll-protein complexes CPI and CPa, while after transfer to continuous light they form in addition the light-harvesting complexes (J. H. Argyroudi-Akoyunoglou, Z. Feleki, and G. Akoyunoglou, 1971, Biochem. Biophys. Res. Commun.45, 606–614; J. H. Argyroudi-Akoyunoglou and G. Akoyunoglou 1979, FEBS Lett.104, 78–84) we tried to see whether the latter complexes contain newly formed chlorophyll. We labeled the chlorophyll a formed in periodic light with δ-[¹⁴C]aminolevulinic acid, and determined the specific radioactivity of chlorophyll in the complexes formed before or after transfer to continuous light. We found that the light-harvesting complexes contain primarily newly formed and nonradioactive chlorophyll. The results suggest that (i) the chlorophyll a of CPI and CPa formed in periodic light does not exchange with that of the light-harvesting complexes formed after transfer to continuous light. (ii) The light-harvesting complexes formed after transfer to continuous light contain primarily newly formed chlorophylls a and b. (iii) The binding of chlorophyll to protein in the complexes is specific and not an artifact of the sodium dodecyl sulfate action. (iv) As the thylakoid membrane grows and differentiates, the chlorophyll synthesized binds on the apoproteins of the complexes in a stepwise manner.     

Central chemoreception in the region of the ventral respiratory group in the rat

Nattie, Eugene E., and Aihua Li. Centralchemoreception in the region of the ventral respiratory group in therat. J. Appl. Physiol. 81(5):1987-1995, 1996.We injected acetazolamide (AZ; 5 × 10⁶ M, 1 nl) into theregion of the ventral respiratory group (VRG) of anesthetized paralyzedventilated rats. Control injections (mock cerebrospinal fluid,n = 6, or the inactive AZ analogue 2-acetylamino-1,3,4-thiadiazole-5-sulfon-t-butylamide,n = 6) did not increase the integratedphrenic neurogram [phrenic nerve amplitude (PNA)]. The AZinjections produced a focal region of tissue acidosis with a radius < 300-400 µm and are used as a probe for sites of centralchemosensitivity. Injection location is determined by anatomicanalysis. Of 22 VRG injections of AZ, 14 increased the amplitude of thePNA over 15-90 min; 8 had no effect. In 17 cases, we measuredmedullary tissue pH at the injection center and/or at a distantsite and reaffirmed the size of the acidotic region produced by suchsmall AZ injections. Of injections with pH electrodes within300-400 µm of the injection center, all responders showed anacid pH; three nonresponders showed an acid pH, and one an alkaline pH.In a subgroup of five rats, at VRG sites with known respiratory effectsidentified by prior glutamate injection (10 nl, 100 mM), all subsequentAZ injections produced a PNA response. Simultaneous measurement of PNAand tissue pH responses at the injection center of eight rats did notshow a uniform correlation in time; initially, both changed with asimilar time course, but PNA recovered more quickly. We conclude that1) the region of the VRG containssites of ventilatory chemoreception,2) ineffective AZ injections doproduce a tissue acidosis but at sites with minimal impact onbreathing, and 3) tissuepH does not uniquely represent the chemoreceptor stimulus.

     

Parallel Computation of the Matrix of the Chemical Distances on the Connection Machine

Abstract

We report here the parallel implementation of an original algorithm allowing a fast calculation of the distance matrix D of a graph representing a given chemical structure (molecule, polymer, crystal, etc.). Our algorithm fits perfectly in the SIMD parallel architecture of the Connection Machines CM-200 as we shall show. After discussing the performances of the parallel evaluation of D, we will end with a relevant application concerning C₆₀ and C₇₀ fullerenes. The present study applies to a generic globally connected graph without any restriction on the local connectivity of each graph's vertex.     

Lymphotoxin: from the physiology to the regeneration of the thymic function

The members of the Tumor Necrosis Factor (TNF) superfamily, the ligand lymphotoxin α1β2 (LTα1β2) and its unique receptor lymphotoxin β receptor (LTβR), play a pivotal role in the establishment and regulation of the immune system by allowing a tight communication between lymphocytes and stromal cells. Recent advances using transgenic mice harboring a specific deletion of the Ltbr gene in distinct stromal cells have revealed important roles for LTβR signaling in the thymic function that ensures the generation of a diverse and self-tolerant T-cell repertoire. In this review, we summarize our current knowledge on this signaling axis in the thymic homing of lymphoid progenitors and peripheral antigen-presenting cells, the trafficking and egress of thymocytes, the differentiation of medullary thymic epithelial cells, and the establishment of central tolerance. We also highlight the importance of LTα1β2/LTβR axis in controlling the recovery of the thymic function after myeloablative conditioning regimen, opening novel perspectives in regenerative medicine.Subject terms: Immune cell death, T cells