Quantitation of RNA polymerase subunits in Escherichia coli during exponential growth and after bacteriophage T4 infection

Summary A method was developed to measure the amounts of RNA polymerase subunits, , , and in crude extracts of Escherichia coli. The proteins were labelled by growing the cells in ³⁵S-sulphate containing media. For measuring and , the cell lysate was electrophoresed on 6% polyacrylamide gels containing SDS and the and bands cut out and counted. For measuring and , the cell lysate was co-electrophoresed with dansylated RNA polymerase on 8% polyacrylamide gels containing SDS. The fluorescent bands were cut out, the proteins eluted, and the and subunits further purified on polyacrylamide gels containing 8 molar urea.The results are: (1) is the subunit of the core RNA polymerase which is present in limiting amount. (2) The core enzyme, as measured by , constitutes a constant fraction of total cellular protein (0.9%), independent of the bacterial growth rate. (3) The subunit is made in excess and is probably regulated independently. (4) The subunit is present in 0.3–0.4 times the amount of the core enzyme. (5) All four subunits are fully conserved after bacteriophage T4 infection.     

γδ T-cell receptor repertoire in human peripheral blood and thymus

T-cell clones expressing the T-cell receptor (Tcr) were generated from peripheral blood lymphocytes (PBLs) and from a thymus sample. In the panel of ten thymus-derived clones, four Tcr phenotypes [as defined by the reaction of monoclonal antibodies (mAbs) directed against known V and V regions] were identified. All the clones lacked expression of the V3 V region, while seven clones were V1+ . V1 was found in combination with V9 or with undefined VVregions. In addition, two other Tcr phenotypes were identified on these clones: V9⁺ V1^– V3^– and V9^– V1^– V3^– One of the clones expressed CD4 and another was CD8positive. The remaining clones were CD4^– CD8^–. In the panel of 76 PBL-derived, Tcr-bearing clones, five Tcr phenotypes could be identified. In contrast to the thymus-derived clones, 30% of the clones were V3⁺ whereas V1 was expressed by a minority of the clones only. One clone was CD4-positive and approximately 30% of the clones were CD8-positive. Four of the five mAb-defined Tcr phenotypes could be identified on both thymus and PBL-derived T-cell clones. However, biochemical analysis of the Tcrs demonstrates differences in the usage of Ct- and C2-encoded y chains by T cells derived from the thymus and PBLs. The results therefore indicate that, at the clonal level, similarities and differences exist between the Tcr repertoires expressed in the thymus and by PBLs. Furthermore, they indicate that combinatorial Tcr heterogeneity is larger than has so far been described. The receptor diversity, combined with the potential of Tcr+ cells to express CD4 or CD8, indicates that these cells are a heterogeneous population that might mediate a number of immune functions.     

Conformation of the circular dumbbell d〈pCGC-TT-GCG-TT〉: Structure determination and molecular dynamics

Summary The circular DNA decamer 5-dpCGC-TT-GCG-TT-3 was studied in solution by means of NMR spectroscopy and molecular dynamics in H₂O. At a temperature of 269 K, a 50/50 mixture of two dumbbell structures (denoted L2L2 and L2L4) is present. The L2L2 form contains three Watson-Crick C-G base pairs and two two-residue loops in opposite parts of the molecule. On raising the temperature from 269 K to 314 K, the L2L4 conformer becomes increasingly dominant (95% at 314 K). This conformer has a partially disrupted G(anti)-C(syn) closing base pair in the 5-GTTC-3 loop with only one remaining (solvent-accessible) hydrogen bond between NH of the cytosine dC(1) and O6 of the guanine dG(8). The opposite 5-CTTG-3 loop remains stable. The two conformers occur in slow equilibrium (rate constant 2–20 s^–1). Structure determination of the L2L2 and L2L4 forms was performed with the aid of a full relaxation matrix approach (IRMA) in combination with restrained MD. Torsional information was obtained from coupling constants. Coupling constant analysis (³J_HH, ³J_HP, ³J_CP) gave detailed information about the local geometry around backbone torsion angles , , and , revealing a relatively high flexibility of the 5-GTTC-3 loop. The values of the coupling constants are virtually temperature-independent. Weakly constrained molecular dynamics in solvent was used to sample the conformational space of the dumbbell. The relaxation matrices from the MD simulation were averaged over r^–3 to predict dynamic NOE volumes. In order to account for the 1:1 conformational mixture of L2L2 and L2L4 present at 271 K, we also included S² factors and r^–6 averaging of the r^–3-averaged relaxation matrices. On matrix averaging, the agreement of NOE volumes with experiment improved significantly for protons located in the thermodynamically less stable 5-GTTC-3 loop. The difference in stability of the 5-CTTG-3 and 5-GTTC-3 loops is mainly caused by differences in the number of potential hydrogen bonds in the minor groove and differences in stacking overlap of the base pairs closing the minihairpin loops. The syn conformation for dC(1), favored at high temperature, is stabilized by solvation in the major groove. However, the conformational properties of the dC(1) base, as deduced from R-factor analysis and MD simulations, include a large flexibility about torsion angle .     

Plant regeneration via somatic embryogenesis in Styrian pumpkin: cytological and biochemical investigations

Somatic embryo formation was induced from cotyledon explants of Styrian pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) by using a solid MS medium supplemented with 16.11M NAA and 4.44M BA or 26.85M NAA and 13.32M BA. The callus proliferation was more efficient on medium supplemented with 26.85M NAA and 13.32M BA. In contrast, the embryogenic response was higher on medium with lower concentrations of growth regulators (16.11M NAA and 4.44M BA). The time needed for embryo induction did not depend on medium composition. Embryos in globular stage were transferred to three different maturation media, containing 2.89M GA₃ in combination with 0.54M NAA, 11.42M IAA and growth regulator-free medium. The germination rate was the highest when embryos were cultured on medium with 11.42M IAA. Plantlets grown on this medium achieved maturity suitable for transplantation into soil within 9 to 10weeks. The regenerated plants were successfully transferred into field and developed fertile flowers and set fruits. Biochemical analysis showed significant lower total glutathione levels among in vitro grown plantlets compared to seedlings grown in soil. When the plantlets were transferred into soil, they reached a normal size within a month and the glutathione concentration was comparable to seed-derived plants at the same developmental stage. Transmission electron microscopy was used to investigate possible differences in the ultrastructure of cells from callus cultures, and leaf cells of regenerated and seed-derived plants. Differences in the ultrastructure were found within chloroplasts which contained only single thylakoids, large starch grains and small plastoglobuli in callus cells in comparison to leaf cells, which possessed a well developed thylakoid system, small starch grains and large plastoglobuli.     

Bistability,switches and working memory in a two-neuron inhibitory-feedback model

It was reported earlier that an inhibitory-feedback network inspired by neostriatal circuitry may exhibit a bistable character and spontaneous switching phenomenon within the neuronal activity. In the presence of noise and external excitation, a few local neurons switch on and generate streams of impulses while other neurons remain quiescent. In time, the existing on neurons spontaneously switch off and other neurons switch on. In this paper we examine the nature of the bistability and switching phenomenon using a simple model consisting of two mutually inhibitory neurons. For nonspiking neuron model, described by a system of nonlinear differential equations, we present a simple bifurcation analysis, which follows the birth and annihilation of two stable fixed points when model parameters are varied. We show that both nonspiking and spiking models may have two stable states, but only spiking neurons exhibit switching. The mechanism of switching for model spiking neurons, described by an equivalent RC circuit with a number of currents, is analyzed using computer simulations. It is shown that switching can be described by a two-state Markov chain with one parameter, which depends on the set of model physiological parameters, such as duration of afterhyperpolarization (AHP), maximum and the time duration of inhibitory post-synaptic potentials (IPSP's) and amplitude of the neuron noise input. On and off states of the model can be rapidly changed by localized excitatory input and the network then sustains the pattern of on and off states. That is, such a network can be used as a programmable memory device. Our hypothesis is that biological neural networks exhibit switches in their evolution to low energy states and switches are essential for the load and readout of the temporary and long term memory.     

Evolution of parallel β/α-barrel enzyme family lightened by structural data on starch-processing enzymes

The parallel /-barrel domain consisting of eight parallel -sheets surrounded by eight -helices has been currently identified in crystal structures of more than 20 enzymes. This type of protein folding motif makes it possible to catalyze various biochemical reactions on a variety of substrates (i.e., it seems to be robust enough so that different enzymatic functionalities could be designed on it). In spite of many efforts aimed at elucidation of evolutionary history of the present-day /-barrels, a challenging question remains unanswered: How has the parallel /-barrel fold arisen? Although the complete sequence comparison of all /-barrel amino acid sequences is not yet available, several sequence similarities have been revealed by using the highly conserved regions of -amylase as structural templates. Since many starch-processing enzymes adopt the parallel /-barrel structure these enzymes might be useful in the search for evolutionary relationships of the whole parallel eight-folded /-barrel enzyme family.     

Plasma α- and γ-tocopherol have different pattern during normal human pregnancy

Plasma - and -tocopherol were monitored in pregnant women throughout healthy gestational periods and after delivery and were compared with that of non pregnant women. The mean plasma -tocopherol and -tocopherol concentrations in non pregnant Saudi women (15.2 ± 1.3 and 1.8 ± 0.2 ol/l respectively) were found within normal range. The maternal plasma -tocopherol level steadily increased reaching maximum level (19.1 ± 1.6 mol/l) at late gestation and then gradually decreased after delivery. On the contrary, the optimum level of -tocopherol (2.1 ± 0.2 mol/l) was at mid gestation, followed by a progressive decrease until one month after delivery (1.5 ± 0.1 ol/l). This study shows that the maternal plasma - and -tocopherol have different profiles that may be attributed to their different responses to the changes in maternal lipids during pregnancy.     

Effects of losartan on the collagen degradative enzymes in hypertrophic and congestive types of cardiomyopathic hamsters

The present study was undertaken to determine the effects of AT1 receptor blockade which occurred in response to losartan, on the extracellular matrix (ECM) degradation process in the Bio 14.6 (n = 12) and Bio 53.58 (n = 12) strains which are referred as models of hypertrophic and dilated cardiomyopathy, respectively. The administration of losartan (30 mg/kg/day) in hamsters from 10–20 weeks of age reduced the accumulation of the left ventricular collagen matrix in both of the Bio 14.6 and the Bio 53.58 strains. According to the RTPCR, the levels of mRNA for matrix metalloproteinase (MMP) and the tissue inhibitor of MMP (TIMP) were examined. MMP1, 2, 3, and 9 were more enhanced in both myopathic strains than in the control F1 strains. With losartan, the levels of MMP1, 2, 9, TIMP1 and 2 decreased in the both strains but those for MMP3 did not in Bio 14.6 strains. TIMP3 and 4 mRNA levels did not change in any of the experimental hamsters, whether treated or untreated with losartan. The Western blots also showed similar observations in the both strains as seen in mRNA expressions although MMP2 in the Bio 53.58 strains did not differ between treated and untreated with losartan. Although losartan has an inhibitory effect on collagen accumulation in the development of cardiomyopathy, MMPs (1, 2, 9) and TIMPs (1, 2) seem to be susceptible to responding to losartan in Bio cardiomyopathic hamsters.     

Metabolism of a phenylcoumaran substructure lignin model compound in ligninolytic cultures of Phanerochaete chrysosporium

The degradation of the phenylcoumaran substructure model compound methyl dehydrodiconiferyl alcohol by the white-rot wood decay fungus Phanerochaete chrysosporium was investigated using culture conditions optimized for lignin oxidation. Initial attack was in the cinnamyl alcohol side chain, which was oxidized to a glycerol structure. This was subsequently converted by loss of the two terminal carbon atoms, C and C, to yield a C-aldehyde structure, which was further oxidized to the C-acid compound. The next detected intermediate, a phenylcoumarone, was produced by double bond formation between C and C, and oxidation of the C-alcohol to an aldehyde group. Further oxidation of C to an acid yielded the next intermediate. The final identified degradation product was veratric acid. No products from the 5-substituted aromatic ring, and no phenolic products, were found. The initial glycerol-containing intermediate was a mixture of the threo and erythro forms, and no optical activity could be found, suggesting that its formation might have involved nonstereospecific C-C epoxidation followed by non-enzymatic hydrolysis of the epoxide.Abbreviations TLC thin layer chromatography - LDA lithium diisopropyl amide - DDQ 2,3-dichloro-5,6-dicyanobenzoquinone - MS mass spectrometry - UV ultraviolet spectroscopy     

Pollen tube extract supports the movement of actin filaments in vitro

Summary Muscle actin filaments labeled with rhodamine-phalloidin were observed to move on the surface coated with a crude extract of pollen tubes ofLilium longiflorum with an average velocity of 1.99±0.55 m/sec. The movement required both Mg²⁺ and ATP. These results indicate that the extract of pollen tubes contains a myosin-like translocatorAbbreviations ATP adenosine-5-triphosphate - DTT dithiothreitol - EGTA ethyleneglycol-bis-(-aminoethylether)N,N,N,N-tetraacetic acid - PIPES piperazine-N,N-bis-(2-ethanesulfonic acid) - PMSF phenylmethylsulfonyl fluoride     

ATP Synthases in the Year 2000: Evolving Views about the Structures of These Remarkable Enzyme Complexes

This introductory article briefly summarizes how our views about the structural features ofATP synthases (F₀F₁) have evolved over the past 30 years and also reviews some of our currentviews in the year 2000 about the structures of these remarkably unique enzyme complexes.Suffice it to say that as we approach the end of the first year of this new millinium, we canbe conservatively confident that we have a reasonably good grasp of the overall low-resolutionstructural features of ATP synthases. Electron microscopy techniques, combined with the toolsof biochemistry, molecular biology, and immunology, have played the leading role here byidentifying the headpiece, basepiece, central stalk, side stalk, cap, and in the mitochondrialenzyme, the collar around the central stalk. We can be reasonably confident also that we havea fairly good grasp of much of the high-resolution structural features of both the F₁ moietycomprised of fives subunit types (, , , , and ) and parts of the F₀ moiety comprised ofeither three (E. coli) or at least ten (mitochondria) subunit types. This information acquiredin several different laboratories, either by X-ray crystallography or NMR spectroscopy, includesdetails about the active site and subunit relationships. Moreover, it is consistent with recentlyreported data that the F₁ moiety may be an ATP driven motor, which, during ATP synthesis,is driven in reverse by the electrochemical proton gradient generated by the electron transportchain. The real structural challenges of the future are to acquire at high resolution completeATP synthase complexes representative of different stages of the catalytic cycle during ATPsynthesis and representative also of key regulatory states.     

Harzkonservierte fossile Vogelfedern aus der untersten Kreide

Zusammenfassung Harzkonservierte Fossilien ermöglichen bei Anwendung adäquater Methoden die morphologische Analyse der Feinmerkmale bis zur Auflösungsgrenze des Lichtmikroskops, Beobachtung in verschiedenen Ebenen und Richtungen, und somit konkrete Rückschlüsse auf die Wirkung und Bedeutung der Einzelelemente und des Gesamtgefüges.Eine so eingehende funktionsmorphologische Analyse mit Berücksichtigung der Positionsvariation (graduell verschiedene Gestaltung in gesetzmäßiger Abhängigkeit von der Lage innerhalb der Gesamtfeder) der Einzelelemente wie Abzweigungs-, Knick-, Neigungswinkel, Krümmung, Länge, Dicke, Querschnitt, Dichte, Differenzierungsgrad der verschiedenen Abschnitte von Rhachis, Rami, Radii inklusive Häkchen und Cirren wird erstmals für fossile Vogelfedern geliefert (hier als Abriß zu einer dokumentarisch und thematisch ausführlicheren Darstellung in Stuttgarter Beiträge zur Naturkunde).Diese Federn entstammen der untersten Unterkreide und sind damit nur relativ wenig jünger alsArchaeopteryx. Sie weisen extrem differenzierten Aufbau auf, der auf hohe flugtechnische und wärmeisolierende Leistungsfähigkeit schließen läßt.Die hier vorgelegten funktionsmorphologischen Ermittlungen an fossilen Körperkonturfedern mögen auch zu einer intensiveren Analyse der bis jetzt stark vernachlässigten Untersuchung ganz normaler Körperfedern rezenter Vögel anregen. Erst dann, nach umfassender Kenntnis ihrer Ausgestaltung innerhalb der verschiedensten rezenten Vogelgruppen, läßt sich überzeugend begründen, ob und wieweit die hier vorgelegten Federn dieses Unterkreide-Vogels noch ursprüngliche Elemente (Plesiomorphien) oder ihnen eigene Sonderbildungen (Autapomorphien) aufweisen; das gilt sowohl für morphologische wie für funktionelle Elemente der Gesamtstruktur.

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Resin-preserved fossil bird's feathers from the Lowermost Cretaceous

Summary Parts of some feathers, originating from a single bird, were discovered in our collections of Lower Cretaceous amber from the Lebanon mountains — which, in general, contains the oldest terrestrial microfossils preserved with all morphological details.These contour feathers of the trunk, which are nearly as old as Archaeopteryx (Lowermost Cretaceous: Neocomian/Uppermost Jurassic: Kimmeridigian) were studied with magnifications of 500–900 in several levels by a special technique. (In normal fossils, i.e., impressions, the granulation of the sediment and the fossil's bulky carbon remainders cause a blurred image even at a magnification of merely 100).Special emphasis was laid on the study of the individual elements' gradual variation, depending on the respective position within the total feather (position variation). Where appropriate, an analysis of lengths, quantity, degree of differentiation, angle of inclination, break, and branching, cross-sectional view, curvature, etc. of the rhachis, rami, distal and proximal radii, barbicles, hooklets, etc. were undertaken. [Through measurements of the depth of details the effects caused by a sloping position (apparent variation) may be precisely separated from the real variation.]On the basis of such a detailed knowledge of structure and relative position a thorough functional analysis of the single elements as well as the total system is given.Principal features: The production of plain stability in the feather's center, and of flexibility in its apical and lateral rims; dispersion of forces in case of pressure or a pulling load; function of the hooklets (which donot serve as an interlocking mechanism while the feather is in the normal resting position, but function with increasing braking action only when a neighboring ramus diverges to a precisely defined extent from its resting position) including the mechanism of their unhooking; devices for the avoidance of harmful hooking into contacted parts of other feathers; production of maximal stability by minimal air resistance, and of minute chambers (<0,00001 mm³) with still air for optimal heat isolation.Apart from this abstract, further information, accompanied by numerous figures, will be given in a later paper in Stuttgarter Beiträge zur Naturkunde.

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Veränderte Fassung eines am 11. 10. 1971 gehaltenen Vortrages auf der 83. Jahresversammlung der Deutschen Ornithologengesellschaft in Bonn.     

Der „biologische Aufstieg“ und seine Kriterien

Zusammenfassung Die Arbeit stellt die Frage nach den Kriterien des fossil belegten Biologischen Aufstiegs der Organismenwelt, d.h. derjenigen Vervollkommnung, die sich nicht innerhalb des Rahmens eines gegebenen Bauplans hält, wie die Anpassungsvervollkommnung, sondern über verschiedenrangige Baupläne hinweg zu höheren Typen führt, z.B. von den Fischen über die Amphibien und Reptilien zu den Säugern bzw. Vögeln. Ausführlich werden zwei Gruppen von Kriterien besprochen, ihr Inhalt dargelegt und ihre Eindeutigkeit zur Charakterisierung des Biologischen Aufstiegs untersucht. Die erste Gruppe umfasst die Kriterien der zunehmenden Differenzierung und harmonischeren Integration. Diese legen die morphologisch-physiologische Differenzierung oder genauer die Ganzheit der Organismen zugrunde, d.h. ihre Vielheit in der Einheit. Die zweite Kriteriengruppe, nämlich zunehmende Umweltunabhängigkeit und zunehmende individuelle Autonomie, geht von den Beziehungen des Organismus zur Umwelt und zu andern Lebensformen aus und betont die Subsistenz der Individuen, d.h. ihr grösseres oder geringeres Losgelöstsein oder ihre Selbständigkeit. Da nun Ganzheit und Subsistenz die entscheidenden Elemente einer biologischen Definition des Individuums sind, lässt sich sagen, dass der Biologische Aufstieg eines Organismus um so höher ist, je stärker seine Ganzheit und Subsistenz und damit sein Individuumsein ist.Eindeutigkeit kommt allen genannten Kriterien nicht zu. Die Gründe für ihre Unschärfe sind verschiedener Art. Zunächst gibt es noch keine eindeutige und vollständige Definition des biologischen Individuums, so dass sich nicht eindeutig umreissen lässt, was einem Organismus eine stärkere oder weniger starke Individualität verleiht. Dann sind die Linien, über die sich Vervollkommnungen vollziehen und von denen die eine innerhalb des Bauplans bleibt (Anpassungsvervollkommnung), die andere aber über ihn hinausführt (Biologischer Aufstieg) so innig und in so eigenartiger Weise miteinander verflochten, dass sie sich nicht sauber scheiden und in ihren charakteristischen Merkmalen genau beschreiben lassen. Jeder Vertreter eines Bauplans, ganz gleich von welcher Ranghöhe, ist nämlich notwendig in eine Umwelt eingepasst und irgendwie spezialisiert. Es gibt keine Typen mit reinen Bauplanmerkmalen, die nach keiner Richtung hin eine Anpassungsvervollkommnung, sondern nur Merkmale des Biologischen Aufstiegs aufweisen. Schliesslich kennen wir fossil nur die Entfaltung oder Ausgestaltung der Grossbaupläne des Tierreichs, nämlich des Wirbeltierstammes und der verschiedenen Gruppen der Wirbellosen, nicht aber das Interessanteste und Wichtigste, nämlich ihren Biologischen Aufstieg zu der organisatorischen Höhe, mit der sie sich im Silur bzw. im Kabrium bereits vorstellen. Das erst würde einen tieferen Einblick in das Wesen des Biologischen Aufstiegs vermitteln.

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Summary This article deals with the question of the criteria for the biological ascent (Biologischer Aufstieg) of the organic world, resting on fossil evidence. That is, of that improvement which is not only restricted to the framework of a given general structure (Bauplan) as is the improvement of adaptation, but which also leads beyond general structures (Baupläne) of differentiated levels to a higher type,e.g. from the fishes through the amphibians and reptiles to the mammals or birds. Two groups of criteria are discussed at length, their content exposed and their univocity for the characterisation of this biological ascent is examined. The first group includes the criteria of increasing differentiation and more harmonious integration. The basis for these is the morphological-physiological differentiation, or more exactly, the totality of the organisms,i.e., their variety-in-unity. The second group of criteria, increasing independence of environment and increasing individual autonomy, is derived from the relationships of the organism to its environment and to other living forms, and stresses the subsistence of individuals,i.e., their greater or lesser degree of independence or self-sufficiency. Now since totality and subsistence are the decisive elements in a biological definition of the individual, it may be said that the biological ascent of an organism is higher, the more perfect its totality and subsistence and therefore its individuality is.The criteria mentioned are not univocal. The reasons for this lack of clarity are varied. First of all, there is no univocal and complete definition of the biological individual, so that it cannot be exactly stated just what gives an organism a more or less perfect individuality. Then the lines, along which improvements are made, and according to which the one remains within the general structure (improvement of adaptation) and the other goes beyond the general structure (biological ascent), are so intimately and singularly bound together, that they cannot be cleanly distinguished, and their characteristic notes exactly described. For each representative of a general structure, regardless of its level, is necessarily fitted into an environment and somehow or other specialised. There are no types with only notes of the general structure which show in no direction an improvment of adaption, but only the signs of biological ascent. Finally, we only have fossil evidence for the development or deployment of the great general structures (Grossbaupläne) of the animal world, namely that of the vertebrates and of the different groups of invertebrates, not for the most interesting and most important, that is, their biological ascent to the level of organisation with which they are found in the Silurian or Cambrian periods. Only that would give us a deeper insight into the essence of biological ascent.

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Résumé Ce travail pose la question des critères de la progression biologique (Biologischer Aufstieg), d'après les documents fossiles, dans le monde des organismes, c'est-à-dire de ce perfectionnement qui ne s'arrête pas à l'intérieur du cadre d'un phylum (Bauplan) donné, comme le perfectionnement de l'adaptation, mais qui conduit, au-de-là de phylums (Baupläne) de rang différent, à des types supérieurs, par exemple, des Poissons pas les Amphibies et les Reptiles jusqu'aux Mammifères ou aux Oiseaux. Deux groupes de critères y sont recensés en détail, leur contenu est exposé, et on les examine pour voir s'ils caractérisent sans ambiguïté la progression biologique. Le premier groupe comprend les critères de différenciation croissante et d'intégration harmonique. Ils sont fondés sur la différenciation morphophysiologique ou plus exactement sur la totalité des organismes, c'est-à-dire leur multiplicité dans l'unité. Le second groupe de critères, à savoir indépendance croissante du milieu et autonomie individuelle croissante, part des relations de l'organisme au milieu et aux autres formes vivantes et souligne la subsistence des individus, c'est-à-dire leur plus ou moins grande indépendence ou leur stabilité interne. Comme totalité et subsistence sont les éléments décisifs d'une définition biologique de l'individu, on peut dire que la progression biologique d'un organisme est d'autant plus élevée que sa totalité et subsistence et par là son être individuel sont plus accusés.Tous les critères mentionnés ne sont pas uniformes. Les motifs de leur imprécision sont divers. Tout d'abord, il n'y a pas encore de définition unique et complète de l'individu biologique, de sorte qu'on ne peut circonscrire d'une manière univoque ce qui confère à un organisme une individualité plus forte ou moins forte. Ensuite les lignées au-delà desquelles s'accomplissent des perfectionnements, et dont l'une reste intérieur au phylum (perfectionnement de l'adaptation), tandis que l'autre le transcende (progression biologique), sont entrelacées si intimement et d'une façon si particulière qu'elles ne se laissent pas séparer franchement et décrire rigoureusement selon leurs signes distinctifs. Tout représentant d'un phylum, peu importe son palier, est en effet nécessairement inséré dans un milieu et en quelque façon spécialisé. Il n'existe pas des types à caractères phylétiques purs, qui ne montrent dans aucune direction un perfectionnement de l'adaptation, mais seulement des marques caractéristiques de la progression biologique. Enfin nous ne connaissons pas les restes fossiles que le développement ou la formation des grands phylums (Grossbaupläne) du règne animal, à savoir du rameau des Vertébrés et des divers groupes des Invertébrés, mais non pas le plus intéressant et le plus important, leur progression biologique jusqu'au degré d'organisation qu'ils présentent déjà à l'époque du Silurien ou plutôt du Cambrien. C'est cela seulement qui permettrait une vue plus profonde sur la nature de la progression biologique.

     

Protein kinase C (α, β, γ) in Pacinian corpuscle

Immunocytochemical demonstration of protein kinase C (PKC) subspecies (, , ) was carried out in Pacinian corpuscles of rat hind feet using monoclonal or polyclonal antibodies against each of these subspecies. The inner core cells and lamellae and the Schwann cell cytoplasm of the nerve fiber innervating the corpuscle were strongly positive for PKC -immunoreactivity (IR). In contrast, the axon terminal and the outer core did not display any positive -IR. Very weak PKC -IR was detected in the ultraterminal region of the axon terminal, while the trunk region showed no immunoreactivity. Very faint PKC -IR was found also in the lamellar cells located at the periphery of the inner core and the endoneurial fibroblasts in the intermediate layer. PKC -IR was not detected in any part of the corpuscle. The strong PKC -IR in the inner core and the presence of absence of PKC -, -, and -IR in the axon terminal are discussed from the point of view of the functional aspects of each part.     

Presence of hybridizing DNA sequences homologous to bovine acidic and basicβ-crystallins in all classes of vertebrates

Summary The eye lens-crystallins in cow and chicken are encoded by a family of at least six genes. In order to assess the distribution of the corresponding genes among other vertebrates we hybridized -crystallin sequences (A2, A3/A1, A4, B1, B2, B3), isolated from a bovine lens cDNA library, to Southern blots on whichEcoR1-digested chromosomal DNA was blotted from different vertebrate species. These included human, chimpanzee, calf, rat, pigeon, duck, monitor lizard, toad, trout, and lamprey. Positive hybridization signals were found in the representatives of virtually all classes of vertebrates. The basic B-crystallins gave hybridization signals in more species than the acidic A ones. In monitor lizard and toad the weakest hybridization signals for basic crystallin probes were found. For acidic crystallin probes the distribution pattern was more simple; among cold-blooded vertebrates a signal for A2 was found in trout and lamprey, for A4 in trout, and for A3/A1 only in toad. The results demonstrate that the duplications leading to the -crystallin gene family occurred before or during the earliest stages of vertebrate evolution.     

Phenogenetic Characterization of a Group of Giant φKZ-like Bacteriophages of Pseudomonas aeruginosa

A comparative study was made of a group ofPseudomonas aeruginosa virulent giant DNA bacteriophages similar to phage KZ in several genetic and phenotypic properties (particle size, particle morphology, genome size, appearance of negative colonies, high productivity, broad spectrum of lytic activity, ability to overcome the suppressing effect of plasmids, absence of several DNA restriction sites, capability of general transduction, pseudolysogeny). We have recently sequenced the phage KZ genome (288 334 bp) [J. Mol. Biol., 2002, vol. 317, pp. 1–19]. By DNA homology, the phages were assigned to three species (represented by phages KZ, Lin68, and EL, respectively) and two new genera (KZ and EL). Restriction enzyme analysis revealed the mosaic genome structure in four phages of the KZ species (KZ, Lin21, NN, and PTB80) and two phages of the EL species (EL and RU). Comparisons with respect to phage particle size, number of structural proteins, and the N-terminal sequences of the major capsid protein confirmed the phylogenetic relatedness of the phages belonging to the KZ genus. The origin and evolution of the KZ-like phages are discussed. Analysis of protein sequences encoded by the phage KZ genome made it possible to assume wide migration of the KZ-like phages (wandering phages) among various prokaryotes and possibly eukaryotes. Since the phage KZ genome codes for potentially toxic proteins, caution must be exercised in the employment of large bacteriophages in phage therapy.     

Partial sequence homologies between cytoskeletal proteins,c-myc,Rous sarcoma virus and adenovirus proteins,transducin, and β- and γ-crystallins

Computer based sequence comparisons indicate partial sequence homology between human c-myc, Rous sarcoma virus, adenovirus 7, and simian sarcoma virus proteins and the cytoskeletal proteins desmin, keratin and vimentin. In addition, sections of the oncogene proteins showed partial but significant homology to and subunits of transducin, -II and -BP crystallins showed partial but significant homology to the cytoskeletal proteins keratin, vimentin, desmin, and -tubulin, and to adenovirus 7 and simian sarcoma virus transforming gene proteins. -BP crystallin showed partial but significant homology to Rous sarcoma virus protein, and to and y subunits of transducin. Both crystallins showed partial sequence homology to the GTP-binding protein elongation factor TU fromEscherichia coli . These sequence homologies suggest a link between the mechanisms of normal lens cell differentiation, involving modifications to the cytoskeleton and subsequent changes to the pattern of protein synthesis, and mechanisms of neoplastic transformation. Furthermore the transducin-like region on -crystallin may be important for its interaction with lens membranes and the maintenance of short-range order for lens transparency.     

Upregulation of Fas-induced apoptosis by interferon-γ accompanied by increased ICE expression in renal cell cancer cells

The integration of Fas/Apo-1 (CD95) by Fas ligand or anti-Fas antibody induces apoptosis, and this system plays a pivotal role for the lysis of target cells by cytotoxic T lymphocytes. Fas-mediated apoptosis is also increased by a prior incubation of Fas-bearing cells with interferon(IFN)-. Interleukin-1- converting enzyme (ICE) and/or CPP32, or other members of ICE family act as direct cell death executors downstream of this mechanism, and a tetrapeptide inhibitor of these cysteine proteases blocks Fas-mediated apoptosis. In this study, we examined the effect of IFN- on Fas-mediated apoptosis in ACHN cells. IFN- augmented apoptosis in a dose dependent manner and reached a plateau at 400 U/ml when exposed for 48 h before the end of culture. The kinetics revealed a significant increase in apoptosis after 24 h. Exposing ACHN cells to IFN- increased pro-ICE expression accompanied with a decrease of pro-CPP32. These results suggest that direct enhancement of ICE expression and/or upregulation of conversion of pro-CPP32 to active form increases Fas-mediated apoptosis by IFN- in ACHN cells.     

Rapid in vitro Regeneration of Sesbania drummondii

This paper describes rapid propagation of Sesbania drummondii using nodal explants isolated from seedlings and young plants. The nodal segments proliferated into multiple shoots on Murashige and Skoog's (MS) medium supplemented with 22.2 M benzyladenine. MS medium containing 2.2 and 4.5 M thidiazuron induced 5 – 6 shoots per stem node from 3-month-old plants. Nodal explants when cultured on MS medium containing combinations of benzyladenine (8.8 and 11.1 M) and indole-3-butyric acid (0.24 – 2.46 M) or indole-3-acetic acid (0.28 – 2.85 M) gave lesser number of shoots. Callus induced on cotyledonary explants when subcultured on 2.2 M thidiazuron containing medium resulted in its mass proliferation having numerous embryoid-like structures. Indole-3-butyric acid (0.24 – 2.46 M) was found suitable for root induction. In vitro regenerated plants were acclimatized in greenhouse conditions.     

Porosity and available water of temporarily waterlogged soils in a Quercus robur (L.) declining stand

Pedunculate oak (Quercus robur L.) is particularly sensitive to decline in clayey soils presenting a high-perched temporary water table. These soils induce two successive constraints in one-year cycle: water excess (and hypoxy) in winter and early spring, and water shortage in summer (water stress being more restrictive to oak). We determined the porosity and water properties of temporarily waterlogged clayey soils supporting forest stands of decliningQuercus robur trees in a 101yr-old oak stand in Belgium (50°06N, 4°16E). Roots unevenly colonized the soil down to 1.6m: fine roots (diameter<5mm) were mostly distributed on the surface horizons (0–0.3 m) and around 1.3m deep, despite dense clayey horizons appearing at 0.35m depth. Clay content below this depth reached 46–51. Illite and vermiculite were the dominant clay minerals. The clayey horizons exhibited marked shrink–swell properties: bulk density at 30kPa increased from 1.41 to 1.88gcm^–3 from the surface to 2m depth. There was also evidence of hypoxic conditions caused by water saturation of pore space in the rooting zone from October to mid-April. Extractable water (EW), calculated between moisture tensions of 5 and 1600kPa was 152.8mm. The level of perched temporary water table strongly depended on the seasonal rhythm of water uptake by trees and on the shrink–swell behaviour of soil.