R.M. Cowling,D.M. Richardson & S.M. Pierce (eds.) 1977. Vegetation of Southern Africa.

We determined the role of bird dispersal in seed and seedling dynamics of the tree Kalopanax pictus from 7 years of observing seed rain and seedling emergence in a broad-leaved deciduous forest in central Japan. We also performed an experiment on the influence of seed pulp on germination of seeds of K. pictus. Seeds of this species can lie dormant for several years, and this causes rather constant yearly seedling emergence in spite of irregular seed production. The spatial distribution of the seedlings that emerged each year (maximum distance from nearest conspecific seed-bearing tree of 90 m) was wider than that of gravity-dispersed seeds (max. distance of 37 m), suggesting seed dispersal by birds in winter. Emerged seedling densities at sites over 20 m from the nearest conspecific seed-bearing tree were highest in the spring of 1991, about half a year after the largest seed fall of the observation period. However, emerged seedling densities within 20 m from seed-bearing trees were highest in 1992, 1.5 years after the largest seed fall. These field observations may be explained by the experimental results on the effects of seed pulp on germination. Intact seeds germinate slowly at low germination rates, while seeds without seed pulp germinate quickly at high germination rates. Fallen seeds with seed pulp thus appear to form a seed bank near seed sources (temporal dispersal), while seeds scattered by birds appear to increase the possibility of reaching the present safe sites in distant areas with quick germination (spatial dispersal).     

V.A.T.E.R. association and its limits

Comparative investigation of 92 cases of V.A.T.E.R. syndrome (4 personal cases) and 62 cases of caudal regression (Duhamel syndrome) (2 personal cases) are performed. There is much analogy between these two entities. Initial impairment would be an early dysfunction of mesoderm setting up located on esophagus in V.A.T.E.R. syndrome and on kidneys in Duhamel syndrome. Etiopathogenic factors remain unknown. Genetic counseling is good. Detection of only one mesodermal malformation leads to inquire other unnoticed anomalies (kidneys, heart, spine, alimentary duct).     

Robert Alexander Falla K.B.E., C.M.G., M.A., D.Sc., F.R.S.N.Z.

Abstract

On 23 February 1979 Sir Robert Falla collapsed and died at his home in Eastbourne. He was 77. His sudden death came as a great shock to his multitude of friends and colleagues, many of whom were still sharing with Sir Robert a deep sense of loss at the death on 31 May 1978, shortly after the couple's golden wedding anniversary, of his charming wife Molly.     

Species 30. Cisticola Robusta. Pl. XV.

With what has already been said of the bird in the Definition of the pair and the Key to species, robusta requires little farther introduction. Some peculiarities in the bird's moults will require particular attention later on, when it comes to defining the racial variation.     

Studies of metal-sugar complexes in the solid state by the 13C-n.m.r. c.p.-m.a.s. method

Several metal-sugar conjugates have been prepared. Chelate coordination complexes of copper(II) and zinc(II) were prepared from salicylaldimine ligands derived from combinations of methyl 3,4,6-tri-O-acetyl-2-amino-2-deoxy-β-d-glucopyranoside or 1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-β-d-glucopyranose and salicylaldehyde. Similar Schiff's bases were prepared from chitosan and complexed to copper(II). Cross-polarisation-magic angle spinning ¹³C-n.m.r. spectroscopy showed that paramagnetic ions have profound effects on the resolution obtainable and, at high concentration, result in broad, featureless spectra. In contrast, diamagnetic ions have little effect on the isotropic chemical shifts of the sugar chelates.     

Enzymes of the mandelate pathway in bacterium N.C.I.B. 8250

1. Bacterium N.C.I.B. 8250 was grown on dl-mandelate, benzyl alcohol, benzoyl-formate, benzaldehyde and benzoate and also on 2-hydroxy, 4-hydroxy, 3,4-dihydroxy and 4-hydroxy-3-methoxy analogues of these compounds. The enzymic complements of the cells were determined and the specificities of some of the enzymes examined. 2. Growth on mandelate or benzoylformate induces l-mandelate dehydrogenase, benzoylformate decarboxylase, benzyl alcohol dehydrogenase and a heat-stable as well as a heat-labile benzaldehyde dehydrogenase. Growth on benzyl alcohol or benzaldehyde induces benzyl alcohol dehydrogenase and the heat-labile benzaldehyde dehydrogenase. 3. The enzymes of the mandelate-to-benzoate pathway are non-specifically active on, and induced by, all the substituted analogues that support growth. 4. Benzoate oxidase is induced by growth on benzoate or on 2-hydroxybenzoate. 2-Hydroxybenzoate hydroxylase, 4-hydroxybenzoate hydroxylase and 4-hydroxy-3-methoxybenzoate O-demethylase are induced only by growth on homologous substrates. 5. The results of the investigation are discussed with regard to the possible regulation of the enzyme systems.     

Species 38. Cisticola Ruficeps. Pl. XVIII.

An easily recognized little bird in both of its very different seasonal dresses: one with no very near relative among the other species, but thoroughly Cirticoline from every point of view, alive or on the table: about the size of the Wood-Warbler (P. sibilatrix) , but with a shorter tail and much shorter wings, (totally different coloration), and in behaviour more like a bush-loving Sylvia , the Whitethroat (S. communis) for instance, only without any of that bird's aerial love-dances.     

P-cresol and 3,5-xylenol methylhydroxylases in Pseudomonas putida N.C.I.B. 9896.

Pseudomonas putida N.C.I.B. 9869, when grown on 3,5-xylenol, hydroxylates the methyl groups on 3,5-xylenol and on p-cresol by two different enzymes. 3,5-Xylenol methylhydroxylase, studied only in relatively crude extracts, requires NADH, is not active with p-cresol and is inhibited by cyanide, but not by CO. The p-cresol methylhydroxylase requires an electron acceptor and will act under anaerobic conditions. It was purified and is a flavocytochrome c of mol.wt. approx. 114,000 consisting of two subunits of equal size. The enzyme catalyses the hydroxylation of p-cresol (Km 16 micron) and the further oxidation of product, p-hydroxybenzyl alcohol (Km 27 micron) to p-hydroxybenzaldehyde. A different p-cresol methylhydroxylase of the flavocytochrome c type is induced by growth on p-cresol. It too was purified and has mol.wt. approx. 100,000, and again consisted of two equal-size subunits. The Km for p=cresol 3.6 micron and for p=hydroxybenzyl alcohol, 15 micron.     

A.M.A. Denver Meeting

This summary covers only a few of the many important subjects dealt with by the A.M.A. House of Delegates at its Denver meeting and is not intended as a detailed report on all actions taken.     

J. B. S. Haldane and the origin of life

In 1929 the British biologist John Burdon Sanderson Haldane published a hypothesis on the origin of life on earth, which was one of the most emblematic of the interwar period. It was a scenario describing the progressive evolution of matter on the primitive earth and the emergence of life. Firstly, this paper presents the main ideas put forward by Haldane in this famous text. The second part makes comparisons between Haldane and Alexander Ivanovitch Oparin’s ideas regarding the origins of life (1924). These two theories, apparently very similar, presented distinct conclusions. The third part focusses on Haldane’s reflections on the emergence of life during the 1950s and 1960s, and shows how they were linked to the recent developments of prebiotic chemistry and molecular biology.     

Meiosis in allopolyploid Crepis capillaris. II. Autotetraploids.

Meiotic chromosome pairing of autotetraploid Crepis capillaris was analysed by electron microscopy of surface-spread prophase I nuclei and compared with light microscopic observations of metaphase I chromosome configurations. Prophase I quadrivalent frequencies are high in all three tetrasomes. (A, D, and C) and partially dependent on chromosome size. At metaphase I quadrivalent frequencies are much lower and strongly dependent on chromosome size. There is no evidence for multivalent elimination during prophase I in this system, and the reduction in multivalent frequency at metaphase I can be explained by an insufficiency of appropriately placed chiasmata. The high frequencies of prophase I quadrivalents far exceed the two-thirds expected on a simple model with two terminal independent pairing initiation sites per tetrasome, suggesting that multiple pairing initiation occurs. Direct observations reveal relatively high frequencies of pairing partner switches (PPSs) at prophase I, which confirms this suggestion. The numbers of PPSs per tetrasome show a good fit to the Poisson distribution, and their positional distribution along chromosomes is random and nonlocalized. These observations favour a model of pairing initiation based on a large number of evenly distributed autonomous pairing sites each with a uniform and low probability of generating a PPS.     

Fungal fimbriae. I. Structure, origin, and synthesis.

Fine hair-like appendages on the cell walls of the another smut Ustilago violacea are described. These hairs are termed fimbriae because of their close similarity to the fimbriae (pili) found on certain Gram-negative bacteria. Cells of U. violacea may carry more than 200 fimbriae varying in length from about 0.5 mum to over 10 mum, and having a diameter of about 60-70 A. Some fimbriae produce knobs similar to those found on bacterial sex fimbriae. Log-phase cells are the most densely fimbriated, while stationary phase cells are devoid of fimbriae. The cells can be defimbriated by sonication, high-speed agitation, or centrifugation through a 40% sucrose solution. The fimbriae can regenerate in these defimbriated cells in about 1 h. This regeneration is inhibited by both cycloheximide and rifampin, but not by chloramphenicol and therefore appears to depend on de novo protein synthesis on cytoplasmic ribosomes. Similar long fimbriae are found on U. maydis and Leucosporidium (Candida) scottii. Short fimbriae, about 0.5 mum long, were found on all the other species of yeast-like fungi examined (Rhodotorula, Saccharomyces, Schizosaccharomyces, Hansenula, Lipomyces, Nadsonia, and Torulopsis spp.).     

F.t.-i.r. and laser-Raman spectra of cytosine and cytidine

Fourier-transform infrared (F.t.-i.r.) and laser-Raman spectra of cytosine and cytidine in the solid state have been recorded and assignments of the frequencies made. Comparison of the observed frequencies for cytosine with those for cytidine permits identification of the bands characteristic of the sugar on the one hand, and of the pyrimidine base on the other.     

E.s.r. of free radicals in irradiated uracil-beta-D-arabinofuranoside.

Electron-spin-resonance measurements have been made on single crystals of uracil-beta-D-arabinofuranoside, which were irradiated by 4-0 MeV electrons at 77 K. At low temperatures, two radicals have been identified, one attributed to a hydrogen abstraction from 05' in the sugar moiety and the other to a radical anion located on the pyrimidine ring. The former is very unstable and seems to act as a precursor to other unidentified radical species stable at 77K. At room temperature, the main resonance is due to hydrogen addition to C5 and is probably produced by protonation of the anion. This same radical is also produced by X-irradiation at room temperature.     

Calcium binding of troponin C. I. A potentiometric titration study.

Structural changes of troponin C on calcium binding were studied by hydrogen ion titration, circular dichroism, and fluorescence measurements. The potentiometric titration curves in the carboxyl region are shifted towards lower pH with calcium binding. The intrinsic pK of the carboxyl groups at the calcium binding sites decreases by 0.8 pK unit on calcium binding; on the other hand, magnesium ions have little effect on the intrinsic pK of the carboxyl groups. The intrinsic pK of the imidazole group is not affected by calcium binding. The value of w, an electrostatic interaction factor, is identical for calcium-free and calcium-bound troponin C and is about half of the value calculated assuming a compact sphere. The results of difference titration on the calcium binding indicate that the pH of troponin C solution increases on addition of CaCl2 up to 2 mol of Ca2+ per mol of troponin C and then decreases on further addition of CaCl2. The pH increase is depressed in the presence of MgCl2, in the low pH region, or at high ionic strength. The pH increase is also observed on addition of MgCl2. The ellipticity at 222 nm was measured under the same conditions as the difference titration measurements, and the relation between the pH change and the conformational change of troponin C on calcium binding is discussed based on the results obtained. The number of calcium binding sites and the binding constants estimated by analysis of these difference titration curves were in agreement with the results of Potter and Gergely (22). No magnesium binding site was observed. The tyrosine fluorescence measurements indicated that the binding site near tyrosine-109 is one of the high affinity sites.     

Channel-forming proteins. III. Colicins]

A brief review is devoted to the results of the study of molecular mechanism interaction between membrane-active colicins and membranes in model systems. The data on physical-chemical properties of colicins most studied, the relationship between the structure and the properties of ion channels formed by them in membranes are given. The characteristics of such channels, the dependence of their functioning on the composition of aqueous medium and on transmembrane potential are discussed in detail. The hypotheses on the structure of colicin channels and experimental data concerning the size of their water pore ane considered.     

Thrombin effects on osteoblastic cells. II. Structure-function relationships.

Thrombin has been shown to cause in vitro bone resorption and to stimulate osteoblastic cell proliferation, phosphoinositide turnover and cytosolic calcium levels. In the present study, the role of the active site of thrombin in its action on osteoblastic cells was investigated. Either hirudin or (4-amidinophenyl)methanesulfonyl fluoride inhibited, in a dose-dependent manner, the effects of thrombin on human osteoblast-like osteosarcoma cells (G292 and Saos-2 cell lines) and on normal rat calvarial osteoblastic cells. Thrombin-induced stimulation of cell proliferation, cytosolic calcium increases, and stimulation of phosphoinositide metabolism were concomitantly, and to a proportionally similar extent, inhibited. The inhibitors, when present in the absence of thrombin, did not affect the basal levels of cell functions. Both zeta-thrombin and gamma-thrombin, forms resulting from proteolytic cleavage of alpha-thrombin, were capable of stimulating the osteoblastic cells. These data indicate that thrombin's actions on osteoblast-like cells are dependent on the availability of its catalytic site.     

Automatic bioprocess control. 2. Implementations and practical experiences.

Our improved implementation for bioprocess control allows flexible responses to many process needs. It is based on computer equipment consisting of three hierarchically ordered levels. On the lowest level, a DDC slave computer handles setpoints and simple tasks generating the chemical and physical environment for the cells. It can be designed manually by the user or automatically by the supervisory computer on the second level. This provides for raw data organization, analysis and interpretation either to support personnel on line in decision making, to select predefined control strategies, or even to search for others. In the coordinating computer on the third level, common tasks of different supervisory computers (bioprocesses) are shared, saving money for the equipment. Tasks and concepts as well as experimental experiences are described to outline the capabilities of the configuration.     

The relationship between o.e.r., r.b.e. and number of fractions for X-ray- or neutron-induced skin damage.

The skin reactions in aerated and hypoxic mouse tails after single or fractionated doses of 250 kV X-rays or fast neutrons (6 MeV deuterons on beryllium) have been measured. The o.e.r. for one to sixteen fractions of X-rays remains constant, while that for one to ten fractions of neutrons decreases with increasing neutron fractionation and decreasing neutron dose/fraction. The o.e.r. for X-rays was 1.7, for single-neutron doses 1.4, and for ten fractions of neutrons 1.25. It was anticipated that the o.e.r. for neutron-induced damage would decrease further as neutron fractionation is increased because the contribution to damage from the highest LET components of dose, the alpha and heavy recoil particles, would increase relative to the lowe LET components. The r.b.e. values obtained for skin damage were higher at all neutron doses/fraction examined in this study on tails than all those previously obtained in studies on skin at other sites on four species. This may be due to the influence of hypoxia on the r.b.e. measurements in the mouse tail.